Detection and Demodulation of AM Signals Using ...

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Contents Detection and Demodulation of AM Signals Using Two Dimensional Spectral Surface by Majed Omar Al-Dwairi, Dmitriy E. Skopin

90

Mathematical Modeling and Experimental Evaluation of Optimal Agendas and Procedures for N-Issue Negotiation by Saidalavi Kalady, V. K. Govindan, Abraham T. Mathew

95

A Low Voltage Low Power Triple-Band CMOS LNA with Forward Body Biasing Technique by B. Razeghi, S. A. Ziafati Bagherzadeh, M. Hosseinpour, A. Dorari Ramezani, M. R. Saraninezhad

105

A New Approach to Component-Based Development of Software Architecture by Sabah Al-Fedaghi, Ahmed Abdullah

110

Hybridization of Genetic Algorithm and Neural Network on Predicting Dengue Outbreak by Nor Azura Husin, Norwati Mustapha, Md. Nasir Sulaiman

120

Design of Navigation Map Model for Intelligent Vehicle Combined with the Traffic Sign Recognition by Ying Xia, Sutong Liu, Jiangfan Feng

126

Systematic Literature Review on Search Based Software Testing by Abu Bakar Md. Sultan, Samaila Musa, Salmi Baharom

132

Optimum Configurations for an Open Source IP-PBX System with Botswana Telecommunication Corporation’s (BTC) PSTN Network by Sajid M. Sheikh, Shedden Masupe

141

How Vulnerabilities in Wireless Networks Can Enable Advanced Persistent Threats by Roger Piqueras Jover, Paul Giura

145

A Study of XML with Hostel by Yanchun Ma, Cuirong Zhang

152

Digital Library System in the Academic Libraries: it’s User Friendliness by Mathews Stephen, V. S. Kunjumuhammed

156

Engineering Design and Validation of an Innovative Bionic CD Rack by Carlos A. M. Versos, Denis A. Coelho

163

International Journal on Information Technology (I.RE.I.T.) Vol. 1, N. 2 ISSN 2281-2911 March 2013

Detection and Demodulation of AM Signals Using Two Dimensional Spectral Surface Majed Omar Al-Dwairi, Dmitriy E. Skopin Abstract – This paper is designed to detect AM signals, evaluate its parameters and consequently provides demodulation procedure using the methods of Short Time Fourier Transform (STFT) and Discrete Fourier Transform (DFT) combined with two Dimensional Spectral Surface (2DSS). The proposed technique is noise robust since the energies of modulated signal and noise located in different position on 2DSS which could be discarded during the analysis. Comparing with the Hilbert Transform the proposed method can extract envelopes of different carriers transmitted in the same channel. Copyright © 2013 Praise Worthy Prize S.r.l. All rights reserved.

Keywords: Signal Processing, Amplitude Modulation, AM Demodulation, Two-Dimensional Spectral Surface

The output will follow the same curve as the input baseband signal. There are forms of AM in which the carrier is reduced or suppressed entirely, which require coherent demodulation. Other approach in demodulation techniques described in [2] is the product detector that multiplies the incoming signal by the signal of a local oscillator with the same frequency and phase as the carrier of the incoming signal. After filtering the original audio signal will result. This method will decode both AM and SSB, although if the phase cannot be determined a more complex setup is required. Amplitude modulation also plays important role not only in communication technologies, but also in speech recognition theory [3], diagnostics of electric motor faults [4], faults of wind turbine generators [5] and threephase induction machine fault detection [6]. Popular amplitude demodulation techniques include Hilbert transform [2] and Teager energy operator [7]. Furthermore, for three-phase system it has been recently shown that the Concordia transform can be employed to perform demodulation [8]. For amplitude demodulation using Hilbert transform, the received signal i(n) can be expressed as [9]:

Nomenclature H i  n   F{.} F-1{.} â(n)   xn 

 

The discrete Hilbert transform of sequence i(n) Fast Fourier Transform Inverse Fourier Transform Envelope signal The Teager energy operator

X n e jwi

Result of Short Time Fourier Transform

wm

Windowing function of length m

Fs

Sampling rate

Sw * Xo

Size of the signal window Operator of convolution Original AM signal Impulse response of low pass filter with cut- off frequency clp Impulse response of band pass filter with cut off frequencies cbp

H lp

H bp

I.

Introduction

Amplitude modulation (AM), still widely used in commercial radio today, is one of the simplest ways that a message signal can modulate a sinusoidal carrier wave [1]. There are different approaches in demodulation techniques. Coherent demodulation [2], used in AM radio for example, requires recovering the carrier signal. An AM signal could be rectified without requiring a coherent demodulator. For example, the modulated signal could be passed through an envelope detector (a diode rectifier and a lowpass filter).

i(n) = a(n) cos(2πnf / Fe + φ)

(1)

The discrete Hilbert transform of i(n) is given by:





H i  n    F 1 F i  n   u  n 

(2)

where F{.} and F-1{.} correspond to the FFT and IFFT, respectively, and where u(n) is defined as:

Manuscript received and revised February 2013, accepted March 2013


90

Majed Omar Al-Dwairi, Dmitriy E. Skopin

N  1, n  0, 2  N  u  n    j, n  1, 2, .....,  1 2  N   j, n  2  1, ..., N  1 

detection. This method allows representing a signal in frequency-frequency domain and extracts parameters of AM signals: frequency of carriers and bandwidth of envelops even in the case of multichannel transmission. The proposed method based on both Short Time Fourier Transform and Discrete Fourier Transform. The Short Time Fourier Transform (STFT) [12]-[14] is used to study the frequency characteristics of AM signal, the STFT of the sequence x  m  is defined as:

(3)

Using (1), the estimated envelope, denoted â(n), is given by:

aˆ  n   i

2

 n    H ik  n  

2

   x m wn  m e

X n e jwi  (4)

 jwi m

(7)

m

 

Taking into account that X n e jwi

is evaluated for

The Teager energy operator [2] that can be used for AM demodulation techniques defined according to Eq. (5):   xn   xn2  xn 1  xn 1 (5)

fixed n , then STFT is the conventional Fourier transform of the windowed signal x  m  w  n  m  ,

For AM signal i  t   a  t  cos c t    the Teager

filter of a finite size, if the size of w  m  is large, relative

evaluated at frequency w  wi . Since w  m  is an FIR

 

to the signal periodicity, then X n e jwi

Energy operator (5) returns result represented in the Eq. (6):   i  t    a 2  t  c2  cos 2 c t      a  t   (6)

frequency resolution but poor time resolution. On the other hand, if the size of w  m  is small, then

  gives poor frequency resolution but good time

X n e jwi

It is possible to see that the output from Teager operator contains two components, one of them is a 2  t  c2 varying proportionally to the envelope and

resolution. To extract parameters of AM signal, the size of w  m  can be taken more than period of first harmonic

second one cos 2 c t      a  t   is also related to the

of the envelope signal. The algorithm of spectrogram generation includes segmentation of original signal using windows of fixed length Nsegm, normalization of signal in each segment by windowing function, then application of Discrete Fourier Transform (DFT) to each segment of normalized signal to represent a signal in time-frequency domain. The graphical representation of the STFT is spectrogram [13], [14]. This work is a combination between the spectrogram that is graphical representation of STFT and Discrete Fourier Transform that defined according to equation (8). This combination transforms original signal into frequency-frequency domain, by other words into 2DSS:

Teager Energy of the envelope [10], [11]. Given only one carrier frequency c that is constant during time, the output from Teager energy operator will track the envelope. It can be shown from the analysis of equations (4) and (6) that the Hilbert transform and Teager operator cannot track the envelope of AM signal with varying frequency or it cannot extract the envelopes of few AM signals transmitted simultaneously. This paper proposed new techniques of AM signal detection based on Short Time Fourier transform and Discrete Time Fourier Transform combined into 2D spectral surface that allows detecting AM signals and evaluating its parameters such as frequencies of carriers and frequency and bandwidth of envelope signals even if carriers transmitted in one channel. The approached technique is noise robust since the energy of modulated signal and noise located in different position of 2DSS and can be ignored during analysis. The paper is organized as follows: Section II represents description of approached techniques, Section III shows results of approached methods tested on synthetic and real signals, and Section IV provides the conclusion.

II.

gives good

N

X k  

 x  n  e j 2 kn / N

(8)

n 0

where k  0...N / 2 is the number of harmonics of the one sided spectrum. Figs. 1 illustrate the main stages of 2DSS generation. Firstly, the original signal segmented to the set of windows of fixed length, then each window multiplied with windowing function (see Fig. 1(a)). Consequently 2D matrix is created as shown in Figure 1(b). Number of rows in the matrix equal to the length of window, number of columns can be defined as ratio between signal length (total number of samples) and size of windows.

Detection and Demodulation AM Signals Using 2DSS

This research proposed a novel method of AM signals


International Journal on Information Technology, Vol. 1, N. 2

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(a)

(b)

(c)

(d)

Figs. 1. Main stages of 2D spectral surface generation. A. Segmentation of original signals to the set of windows, B. DFT of rows that converts 2D matrix of segmented signal to the spectrogram. C. DFT of spectrogram rows. D. Final result of transformations - 2D spectral surface

The DFT of each row of 2D matrix gives standard spectrogram that defined according to Eq. (7) in Fig. 1(c). The vertical axis of the spectrogram in our example corresponds to the time, horizontal to the frequency. Next stage of our method is DFT of each row of the spectrogram. This step transforms the image to the frequency-frequency domain as illustrated in the Fig. 1(d). Monochromatic AM signal in 2D spectral surface represented as a single pixel as shown in Fig. 1(d) with two coordinates: the horizontal axis is related to the frequency of carrier and the vertical axis is related to the frequency of envelope. The range of horizontal axis of 2DSS determined from zero to Xmax, according to Eq. (9), vertical axis has the range from zero to Ymax, that computed according to Eq. (10):

Fs 2

(9)

Fs 2S w

(10)

X max 

Ymax 

represented by rectifier implemented using absolute value function, digital IIR passband and low pass filter according to Eq. (11):

X d  H lp  | H bp * X o |

(11)

where | . | denotes the absolute value, X o is original AM signal, * is operator of convolution, H lp and H bp are impulse responses of digital low pass and band pass filters respectively. Impulse responses H bp and H lp can be computed using any standard procedure, a method windows is used to design FIR band pass and low pass filters [2]. The parameter of filter design algorithm for low-pass filter: cut off frequency clp according to the vertical coordinate "y" of pixel in 2D spectral surface (or maximum vertical coordinate in case of nonmonochromatic signal); for band pass filter the cut-off frequencies can be evaluated according to the equation (12):

cbp  x  clp

where Fs is sampling rate of original signal, S w is size of window determined during segmentation. It has been shown that for monochromatic AM signal the 2D spectral surface allows to detect a frequency of carriers and frequency of envelop. For nonmonochromatic signals 2DSS tracks the frequency of carrier and bandwidth of envelope. Demodulation of signal can be provided using non-coherent methods. This work have used a model of envelope detector

(12)

where x is horizontal position of pixel in 2D spectral surface.

III. Experimental Results Synthetic multichannel AM signal for testing of 2D spectral approach is created. Synthetic signal is



92


deterministic signal defined according to the equation (13):

y t     0.3  cos  2   10  t   0.5   sin  2    5000  t     cos  2    30  t   0.5   sin  2   10000  t  

(13)

  sin  2    60  t   0.5   sin  2   15000  t   0.5 cos  2   12000  t    Fig. 2 illustrates the time domain of the synthetic signal.

(a)

Fig. 2. Time domain of multichannel synthetic signal. Horizontal axis is sample numbers, vertical - value of signal

The signal includes the sum of four components, first three are AM signals with frequencies of carriers 5 kHz, 10 kHz and 15 kHz respectively and last component illustrates a noise signal transmitted in the frequency 12 kHz. The synthetic signal was sampled with sampling rate Fs=40 kHz during six seconds then discrete signal was processed according to the algorithm of 2DSS generation which explained in section II. The size of windows has been chosen to be equal 256 samples that related to the time 6.4 milliseconds, it gives 0.17Hz spectrum resolution for horizontal axis of 2DSS and 43Hz of spectrum resolution for vertical axis. Figs. 3 illustrate standard spectrogram of synthetic signal and 2DSS image. According to Figs. 3, all AM components is allocated in the 2DSS image. Since last component is nonmodulated noise, it was allocated in the top of the image where position of envelope frequency equal zero. It can be depicted from the analysis of the Fig. 3(a). that AM signal has certain representation on the 2DSS image. The 2DSS has been tested on real AM signals. Two channels of original speech signal was recorded using microphone on sampling rate 40 kHz during 5 s, the speech signal represents counting of numbers from zero to nine. Then signal was passed through the Butterworth low pass IIR filter with cut-off frequency 4 kHz and 60 dB of attenuation in stop band.

(b) Figs. 3. The spectrogram (a) of synthetic signal and 2DSS image (b)

After filtration, the signal of right channel was modulated with 100 kHz carrier, left channel with 400 kHz carrier. Resulted signal was transmitted through noisy environment with periodic noise in the frequency 300 kHz. after that the signal was sampled with sampling rate 1 MHz. Figs. 4 illustrate the spectrogram and 2DSS of the signal. The 2DSS image created using 100 samples window size. In this case, according to the Eqs. (9) and (10) the range of horizontal axis limited by the frequency 500 kHz, vertical by frequency 5kHz, that is enough to represent 4 kHz envelope signal. The 2DSS image of original AM signal includes two vertical lines according to the number of carriers in the channel. The horizontal position of the lines is related to the frequencies of the carriers where as the vertical position is related to the envelope bandwidth. the two envelops in original signal is transmitted using carriers with frequencies 100 kHz and 400 kHz. Vertical allocation of lines shows bandwidth of envelops that are corresponded to the frequency 4 kHz which, equal to cut off frequency of low pass filter applied before modulation. After applying demodulation techniques according to the Eq. (11) the final demodulated signal was reproduced through loudspeaker of personal computer. The final results allow to come to conclusion that proposed techniques is adequate for AM signals detection and demodulation.



93


[3]

[4]

[5]

[6]

(a)

[7]

[8]

[9]

[10]

[11]

(b)

[12]

Figs. 4. The spectrogram (a) of real AM signal and 2DSS image (b) [13]

IV.

Conclusion

[14]

An amplitude detection and evaluation of AM signal approach has been proposed in current paper. Firstly, the received signals are evaluated using 2D spectral surface approach. Secondly, such extracted parameters as frequencies of carriers and bandwidth of envelops are used to provide filter design and demodulation procedures based on Eqs. (11), (12). The result of several simulations have shown that the proposed method performs well in synthetic and real AM signals. Furthermore, results have shown that 2DSS is computationally attractive compared to HT, this low complexity demodulation technique can be appropriate for software of modern signal processors.

Authors’ information Majed Omar Al-Dwairi Associate professor since 2011, working at al-Balqa applied University/Faculty of Engineering Technology-Electrical department since 2002. This year Dr. Majed Al-Dwairi has joined Jerash University as visiting professor acting as dean of Engineering Faculty. He was born in Amman Jordan 10/12/1968, his BS,Ms and PhD from Odessa National Academy of Telecommunication/Ukraine1998. His specialist in Multichannel communication systems . The major field of study fiber optics modeling, signal and image processing.

Acknowledgements

Dr. Dmitriy E. Skopin received his M.Sc. and Ph.D. degrees in Computer Engineering Departmant of Kursk State Technical University, Russia in 1995 and 1998, respectively. Since September 2003 until August 2005 he had been an associate professor with the Kursk State Technical University. Since September 2005 until present time he is staff member of Al Balqa Applied University, Jordan. His research interest focus on signal and image processing, parallel processing systems, network operating systems and computer graphics.

This work has been carried out during sabbatical leave granted to the author Majed Omar Al-Dwairi from AlBalqa' Applied University (BAU) during the academic year 2012-2013.

References [1] [2]

Processing, Prentice Hall, 2009. Q. Zhu and A. Alwan. AM-demodualtion of speech spectra and its application to noise robust speech recognition. In Proc. of ICSLP, volume 1, pages 341–344, Beijing, China, October 2000 B. Trajin, M. Chabert, J. Regnier, and J. Faucher, “Hilbert versus concordia transform for three phase machine stator current timefrequency monitoring,” Mechanical systems & signal processing, vol. 23, no. 8,pp. 2648–2657, 2009. Amirat, Y.; Choqueuse, V.; Benbouzid, M. Condition monitoring of wind turbines based on amplitude demodulation. Energy Conversion Congress and Exposition (ECCE), 2010 IEEE, pp 2417 - 2421 Issue Date: 2010 S. Kia, H. Henao, and G. Capolino, “A high-resolution frequency estimation method for three-phase induction machine fault detection,” IEEE Transactions on Industrial Electronics, vol. 54, no. 4, 2007. P. Maragos, J. Kaiser, and T. Quartieri, “On amplitude and frequency demodulation using energy operators,” IEEE Trans. Signal Processing, vol. 41, pp. 1532-1550, April 1993. B. Trajin, M. Chabert, J. Regnier, and J. Faucher, “Hilbert versus Concordia transform for three phase machine stator current timefrequency monitoring,” Mechanical Systems & Signal Processing, vol.23, pp. 2648–2657, 2009. Y. Amirat, V. Choqueuse and M.E.H. Benbouzid, “Wind turbines condition monitoring and fault diagnosis using generator current amplitude demodulation,” Proceedings of the IEEE ENERGYCON’10, Manama (Bahraïn), pp. 310-315, December 2010. Kvedalen, E. (2003). Signal processing using the Teager Energy Operator and other nonlinear operators. Master’s thesis, University of Oslo, Norway. Zhang, G., Li, Y., Huang, Y., A novel HHT and nonlinear teager energy operator based feature for speech emotion recognition, (2012) International Review on Computers and Software (IRECOS), 7 (6), pp. 3360-3364. Allen J., & Rabiner,L., A unified approach to short-time Fourier analysis and synthesis, Proceedings of the IEEE, vol. 65, no. 11, pp.1558-1564, 1977. Cohen, L., Time–frequency analysis, Prentice-Hall, Englewood Cliffs, NJ, 1995. Laaboubi, M., Aassif, E., Latif, R., Maze, G., Moudden, A., Time-frequency spectrogram analysis of acoustic signals backscattered by an air-filled aluminium tube immersed in water, (2010) International Review on Computers and Software (IRECOS), 5 (2), pp. 145-149.

Leon W. Couch. Digital & Analog Communication Systems, 7/E, Prentice Hall, ISBN: 9780131424920. A. Oppenheim, R. Schafer and W. Padgett. Discrete-Time Signal



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Mathematical Modeling and Experimental Evaluation of Optimal Agendas and Procedures for N-Issue Negotiation Saidalavi Kalady, V. K. Govindan, Abraham T. Mathew Abstract – This paper addresses the multi-issue negotiation between two self-interested agents in context of online auction, an auction where items are sold over internet. The outcome of such negotiations depends on the agenda and the negotiation procedure. In this paper we study the impact of varying agenda and procedure on the negotiation outcome in general and for an auction system in particular. This is done under incomplete information settings with the equilibrium strategies defined for issue-by-issue and package deal negotiation procedures. On the basis of these strategies, the optimal agenda-procedure combination for each agent is determined. An experimental evaluation of the same has also been done with multiple agents for an auction system, with satisfactory results. Copyright © 2013 Praise Worthy Prize S.r.l. - All rights reserved.

Keywords: Multi-Agent System, Agent Based Negotiation

Negotiation can either be over a single issue or on multiple issues. In single issue negotiation, the outcome depends only on the negotiation strategies of the agents. For multi-issue negotiations, in addition to the strategy, the outcome depends on the agenda and negotiation procedure. Negotiation procedure specifies how the issues will be settled. There are two ways of negotiating multiple issues. One method is to discuss all the issues together which are termed as package deal. The other method is to negotiate the issues independent of each other called issue-by-issue [2]. This can be done either sequentially or in parallel [9]. The two negotiation procedures can lead to different outcomes. For a multi-issue negotiation under incomplete information settings, the ideal solution is one that is Pareto optimal [11]. A solution is said to be Pareto optimal if no agent can be better off without sacrificing the other’s utility [12]. An efficient negotiation strategy should thus be able to produce Pareto optimal solutions for multi-issue negotiation.

Nomenclature a b δa Ua

Auctioneer agent Bidder agent Discount factor Unity function Offer made by agent a at time t for issue Ai Reserve price for issue Ai Yield factor for auctioneer agent a Maximum agent utility Optimal agenda of agent a

I.

Introduction

Multi Agent Systems (MAS) are emerging fast as an important paradigm which facilitates the modeling and development of large scale distributed systems [1], [2]. The specific properties of MAS like autonomy and self-adaptation make them highly suitable for automated negotiations. Autonomous negotiation has been impressively discussed in the distributed artificial intelligence [2]-[12]. Online auction is an auction in which the participants bid for products and services over the Internet. The functionality of buying and selling in an auction format is made possible through auction software which regulates the various processes involved. Nowadays number of auction site is rapidly increasing which clearly shows the popularity of online auction. Negotiation may be defined as the process by which agents communicate and compromise to reach mutually beneficial agreements [9]. In online auction there is negotiation existing between auctioneer and bidder.

II.

Review of Literature

Excellent reports on multi-agent negotiation are available in the literature. Ref. [13] introduced a simple heuristic method to solve the problem of scheduling tasks on processors, for a parallel processing computing system. Multi-agent systems are used to solve problems which are otherwise difficult for an individual agent to solve. Several other reports also concentrate on the role of agent oriented software engineering for developing largescale dependable applications [1], [13]-[17].



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Saidalavi Kalady, V. K. Govindan, Abraham T. Mathew

Saouli et al. in their work [22] aimed at the improvement of optimized static heuristic in distributed and heterogeneous architecture, present a dynamic model based on agent concept, coupled with an off line (static) heuristic. Khemakhem and Belghith propose in [23] a flexible open architecture able to integrate complementary solutions from the multidisciplinary field of Information Processing. These solutions can cooperate together in order to solve more complex problems or to improve some specific solutions. The proposed architecture is based on agent technology which provides especially autonomy and intelligence. In a multi agent environment where agents are not cooperative, resolution of multiple conflicting goals is the result of finding compromise solutions. And negotiation is the efficient way to find such a solution which is acceptable to all agents. Sycara [7] provided a model for goal conflict resolution through negotiation. An alternative to negotiation method is choice mechanism. One such non-manipulative choice mechanism is Clarke Tax. How the Clarke tax could be used as an effective preference revealer, reducing the need for explicit negotiation is discussed in [8]. Sarit and Jonathan [7] examined the effect of incorporation of time into the negotiation procedure for an efficient negotiation process where there are at least three agents in the environment. The influence of conflicting priorities on negotiation for a two sided multi issue bargaining problem has been discussed in [10]. This work evaluated the different bilateral bargaining procedures and relationship between group heterogeneity and group performance in the negotiation. Enrico et al. [18] described a system for bilateral negotiations, governed by an alternating-offers protocol, in which artificial agents were generated by an evolutionary algorithm. Several issues were negotiated simultaneously in this system. In this paper, the longterm evolutionary behavior using the game theoretic concept of sub game-perfect equilibrium was validated. Also, two important aspects of real-life negotiations: the concept of ‘fairness’ and competition by allowing for multiple bargaining opportunities are modeled and studied. In [12], Jennings et al. discussed about the different methods of automatic negotiation and its challenges and prospects. A generic framework for classifying and viewing automated negotiations was developed and used to analyze the main methods of automatic negotiation; namely, game theoretic, heuristic and argumentation-based approaches. Fatima et al. [2] discussed the effect on negotiation outcome of decomposing a set of N negotiation issues into k stages, and negotiating each sequentially and strategic behavior of agents by defining an agenda that was partly exogenous and partly endogenous. In [9], Fatima et al. introduced the process of bilateral multi-issue negotiation by fixing the protocol and varying the agenda and negotiation procedure. This was done in an incomplete information setting, in

which an agent had incomplete information about its opponent’s negotiation parameters. Equilibrium strategies for package deal and issue byissue negotiation was determined in this paper. They also showed that in two issue negotiation identical preference over the optimal agenda and procedure was possible in each possible scenario. Later, in [19], Fatima et al. worked on the problem for agents, in a bilateral multi-issue negotiation with time constraints, to decide how to allocate the issues between themselves so as to maximize their individual utilities. They first proved that finding the equilibrium offers is an NP-hard problem even in complete information setting and showed that an approximate equilibrium exists for online negotiation and analyzed the approximation error. Minyi [20] demonstrated the drawbacks in the existing negotiation approaches and introduced efficient mediation approaches for multi-issue negotiations with optimal and fair outcomes under incomplete information setting. Most of these works on negotiation discuss the benefits and importance of agent based negotiation in auction as online auction is gaining popularity and concentrates only on the negotiation strategy, assuming the agenda and procedure to be fixed. However, varying the agenda procedure combinations can have a marked impact on the outcome of the negotiation depending on the scenario under which the negotiation is taking place. In the present work, we propose the optimal agenda-procedure combinations for each agent in an n-issue negotiation scenario with an experimental evaluation on online auction system.

III. Negotiation Model Let denote the auctioneer agent and denote bidder agent negotiating over n issues A1, A2…, An. Each agent has complete information about its own parameters but has incomplete information about its opponent’s. The information state of each agent is defined as: ={

…

,

,

,

,

…

}

={

…

,

,

,

,

…

}

where for auctioneer agent , is the reserve price for issue , is the deadline for completing the auction for all issues, is the discount factor and is the utility function. For bidder agent , these parameters are defined analogously. The utility function for auctioneer agent is defined as: …

,

=

−

( )

where, is the offer made by agent at time for issue . For bidder agent , the utility function can be defined similarly [9]. The negotiation proceeds as a series of rounds where



96


in each round one agent acts as the proposer and the other as the responder, exchanging the roles after each round. The bidder agent begins by making an offer that gives it the highest utility and then yields utility to its opponent by making offers that give it successively lower utility as negotiation proceeds. There are three possible actions that an auctioneer agent can take on each received offer: accept, quit or counter-offer. Where counter-offer for an auctioneer agent depends upon the bids by other auctioneer. A bidder agent can counter offer or quit when receiving a new offer from auctioneer agent. The action that an agent takes depends on its strategy. For the package deal procedure, auctioneer agent a’s strategy ( ) is defined as follows: ℎ ℎ ℎ

⎧ ⎪

ℎ

⎨ ⎪ ⎩

ℎ is defined as −1> ℎ ℎ …

where, is a set of points of the form satisfy the following constraint: …

,

=

−

ℎ

Optimal Agenda and Negotiation Procedure

An agenda is agent ’s optimal agenda if, for either issue-by-issue or package deal procedure, it gives the agent the maximum utility between all the possible agendas [13]. An agent’s utility from an agenda depends on the set of possible outcomes that both the agents prefer over no deal. This set of outcomes is the zone of agreement for the agenda. An n-issue negotiation model will have 2 scenarios based on the agents’ mutual preference for each issue. Of these, + 1 scenarios are distinct based on the number of issues having a zone of agreement. The zone of agreement can be explained geometrically by plotting a graph between the utilities of the two agents for each issue. The plot for each issue is called its utility frontier. If the utility frontier lies in the first quadrant, it implies a positive utility for both the agents and thus they have a zone of agreement. If the utility frontier lies in the second or fourth quadrant, only one agent will get a positive utility. A utility frontier in the third quadrant implies that both the agents prefer no deal for that issue.

ℎ

−

ℎ

IV.

ℎ

) of bidder agent

−

⎨ ⎪ ⎩

−

And strategy ( follows:

is defined as −1>

⎧ ⎪

−1> ℎ

) of bidder agent

And strategy ( follows:

that

× IV.1. Single Issue Negotiation

where: =

=

Let be the issue negotiated between agents and b. This issue will appear in agent ’s optimal agenda if this issue will give the agent a positive utility i.e. prefers an agreement over no deal. Thus:

−

and is the yield factor for auctioneer agent a . In the above equation is the maximum agent utility for issue for auctioneer agent . For bidder agent , can be defined similarly. For the parallel issue-by-issue procedure, auctioneer agent ’s strategy ( ) is defined as follows: ⎧ ⎪ ⎪ ⎪ ⎨ ⎪ ⎪ ⎪ ⎩

=

}, if

( )= gives the agent a positive utility ∅, otherwise

If utility frontier for issue lies in the first or fourth quadrants, agent prefers an agreement on this issue over no deal. A utility frontier in the first or second quadrants implies that the agent b prefers an agreement on this issue over no deal. If the utility frontier lies in the third quadrant, both the agents have ∅ as their optimal agenda. As there is only a single issue to negotiate, the concept of package deal makes no distinction from that of issue-by-issue.

ℎ ℎ ℎ −1> ℎ

{

ℎ ℎ ℎ −

IV.2. Two Issue Negotiation ℎ

Let and be the two issues under negotiation. We have three scenarios indicated in the following



97


subsections [9].

IV.3. Three Issue Negotiation Let , and be the three issues under negotiation. For three issues we have eight possible scenarios, of which four are distinct.

IV.2.1. Scenario S0 In this scenario, both issues have a zone of agreement. Thus both agents prefer an agreement on issues and over no deal. So the cumulative utility arising from both the issues will be greater than that of each issue. So the optimal agenda will contain both issues for both the agents: (

,

)=

(

,

)={

,

IV.3.1. Scenario S0 In this scenario, all the three issues have a zone of agreement. Thus both the agents prefer an agreement on issues , and over no deal and their utility frontiers will lie in the first quadrant. So the cumulative utility arising from all the issues will be greater than that of each issue. So the optimal agenda will contain all the three issues for both the agents. In this scenario, there is only one optimal agenda for both the agents:

}

Let ∆ denote the increase in agent a’s utility due to a unit change in its allocation for issue and denote ∆ /∆ . is called the agents’ comparative interest in issue . If ≠ , each agents’ utility from the package deal is no worse than its utility from parallel issue-byissue negotiation. If = , package deal and parallel issue-by-issue negotiation generate the same outcome.

(

In this scenario, only one issue has a zone of agreement (assume it to be issue ). Thus both agents prefer an agreement on issue over no deal. For issue , agents can have three possible preferences. First, a may prefer an agreement on issue to no deal, while b prefers no deal to an agreement on issue . Second, b may prefer an agreement on issue to no deal while a prefers no deal to an agreement. Finally, neither agent may prefer an agreement on issue to no deal: ( , )={ }∪ ( ) ,

)={

}∪

(

,

)=

(

,

)={

,

,

,

}

If = = , the utility frontiers for the three issues are parallel lines and the cumulative utility frontier is a single straight line as seen in Fig. 1. So there is no difference between parallel issue-by-issue and package deal and they produce the same result. Let E, F and G be the points on the utility frontiers of issue , and at which agreement occurs when each of them are individually negotiated. Let H be the point of agreement for parallel issue-by-issue negotiation of these issues. Since no trade-offs are possible as the sum is a straight line, the package deal will also give H as the outcome.

IV.2.2. Scenario S1

(

,

H

)

The optimal procedure for agenda { package deal if ≠ and if procedures generate the same outcome.

, =

} is the , both Fig. 1.

IV.2.3. Scenario S2

,

)=

(

)∪

(

)

(

,

)=

(

)∪

(

)

=

In all other cases: (Fig. 2 shows the case when all are unequal i.e. ≠ ≠ ). Let be the equilibrium time for single issue negotiation. Let E, F and G be the points on the utility frontiers of issue , and at which agreement occurs when each of them are individually negotiated. Let H be the point of agreement for parallel issue-by-issue negotiation of these issues. For package deal at agent b will offer a set of triples from line RS and agent a from the line PQ. For all ′ < both the agents will make offers that give them higher utilities than the equilibrium value. Let ′ ′ and ′ ′ be the offers that b and a make respectively at such a ′ . Then, they will reach an agreement at ′ .

In this scenario, neither issue has a zone of agreement. Since, neither agent prefers an agreement on the two issues to no deal, each of the two issues if discussed separately would lead to conflict. However, if both issues are negotiated together, the utilities for each issue get added up and may result in a zone of agreement. In that case, both the issues will form the optimal agenda. Thus the optimal procedure is package deal. The optimal agenda is given by: (

=



98


Suppose at time − 1 agent b makes the offer that gives it a higher utility than the value at P and the agent a makes an offer giving it a higher utility than S, then at they will reach an agreement at either P or S depending on whether it is b’s or a’s turn to offer. Thus for package ′ deal, the agreement lies in the segment all of which dominates over H. Thus package deal produces a result no worse than parallel issue-by-issue. Hence, the optimal procedure is package deal.

Fig. 3. Scenario S1

IV.3.3. Scenario S2 In this scenario, only one issue has a zone of agreement (assuming it to be ). Thus both the agents prefer an agreement on issue to no deal. The other two issues can lie in the second, third or fourth quadrants depending on the preferences of the two agents. In this scenario, the optimal agenda is given by: ≠

Fig. 2.

≠

IV.3.2. Scenario S1 In scenario S1, two issues have a zone of agreement (assuming them to be issues and ). Thus both the agents prefer an agreement on issue and to no deal. For issue , the agents can have three possible preferences. First, a may prefer an agreement on issue to no deal, while b prefers no deal to an agreement on issue . Second, b may prefer an agreement on issue to no deal while a prefers no deal to an agreement. Finally, neither agent may prefer an agreement on issue to no deal. In this scenario, there are three possible optimal agendas for the two agents: (

,

,

)={

,

}∪

(

)

(

,

,

)={

,

}∪

(

)

(

, ,

, ,

)={ )={

,

,

,

)={

}∪

(

,

)

(

,

,

)={

}∪

(

,

)

IV.3.4. Scenario S3 In this scenario, no issue has a zone of agreement. Thus both the agents prefer no deal to an agreement on all issues and individual negotiations on the issues will certainly lead to a conflict. However, it is possible that when more than one issue is taken together it may result in a zone of agreement. Consequently, the optimal agendas in this scenario can be as follows: (

,

, ) = { 1, 2, 3} or { 1, 2} or { 2, 3} or { 1, 3} or ∅

The optimal procedure will be package deal as issueby-issue will always lead to conflict. In Fig. 4, although no issue has a zone of agreement, adding the utilities of issues and leads to a zone of agreement. This is represented by that part of the graph which is in the first quadrant. Issue will not figure in the optimal agenda for either agent since this will decrease the cumulative utilities of both the agents.

},

,

,

The optimal procedure will be as in Scenario S1 discussed in section IV.3.2.

The optimal procedure for agenda { , , } is as given in scenario S0 discussed in section IV.3.1. The optimal procedure for agenda { , } is package deal if ≠ and parallel issue-by-issue if = . In Fig. 3, the solid graph gives the cumulative utility for issues and . The broken graph corresponds to that of all three issues. As can be seen, adding the utility of issue lowers the cumulative utility of agent a and increases that of the agent . Hence the optimal agendas will be: (

(

IV.4. N- Issue Negotiations As stated earlier, when n-issues are negotiated there will be a total of 2 scenarios.

}



99


then, the package deal produces a result no worse than parallel issue-by-issue. Proof: This can be proved by the principle of mathematical induction for Scenario . The result is true for two-issue model as has been proved in section 3.2. Assume the result is true for all ≤ . Case 1: = =⋯= In this case the cumulative utility of all the issues is a single straight line. Now, this can be considered as the utility frontier for a single issue. If = , the resulting cumulative utility will again be a straight line as given by scenario of the two-issue model, both the package deal and parallel issue-by-issue producing the same outcome. If ≠ , the resulting cumulative utility will be a parallelogram as was seen in the two issue model when ≠ . Thus it follows that package deal produces a result that is no worse than the parallel issueby-issue negotiation procedure.

Fig. 4. Scenario S3

Elimination of the symmetric cases leaves us with n+1 distinct scenarios. Let denotes the scenario where i issues do not have a zone of agreement. The remaining n-i (assuming them to be … ) issues will have a zone of agreement and their utility frontiers will lie in the first quadrant. For these n-i issues, both the agents prefer a settlement and thus the optimal agenda for both the agents in scenario will include these issues. The remaining i issues can fall into the following categories:  Agent b prefers an agreement while the agent a does not.  Agent b does not prefer while agent a prefers an agreement.  Both the agents do not prefer an agreement. Accordingly, their utility frontiers will lie in the second, third and fourth quadrant, respectively. Those issues in the third quadrant need not be considered as adding them will reduce the overall utility for both the agents. For scenario ( ≠ 0, ), the optimal agenda for agents a and b are respectively: (

…

)={

…

}∪

(

…

)

(

…

)={

…

}∪

(

…

)

For scenario (

…

Case 2: ≠ , for some ≠ , 0 < , ≤ If = for some ≤ or = for some , ≤ + 1, the cumulative utility frontier of these two issues can be considered as a single issue. Thus, this case will correspond to a negotiation involving at most k issues. So, package deal produces a result that is no worse than parallel issue-by-issue as per the inductive hypothesis. If ≠ for all ≤ and ≠ for all , ≤ then the comparative utilities of all the issues are different. Let = { , , … , }. Form + 1 distinct sets | |= . , ,…, such that , ⊂ Let and represent the cumulative utility of an agent obtained by package deal and parallel issue-by-issue negotiation for set respectively. Now, ≥ , for all by the inductive hypothesis. Summing up all will give a utility that is k times the equilibrium utilities of each of the k+1 issue when negotiated separately, i.e. this sum represents k times the cumulative utility obtained by the parallel issue-by-issue negotiation of the + 1 issues. Sum of all represents the cumulative utility of + 1 different sets of k distinct issues each. This sum is equal to the cumulative utility of k different sets (let utility of each be ) of + 1 distinct issues each formed from the same ∙ ( + 1) issues. Now, since there are only + 1 distinct issues among these ∙ ( + 1) issues, each of these k sets will contain the same + 1 issues and thus will have the same cumulative utility i.e. the cumulative utility obtained by the package deal negotiation procedure of the +1 issues:

: )=

(

…

)={

…

}

( … )= ⋃ ( ) ; and For scenario , analogously for . If = =⋯= , the package deal and parallel issue-by-issue produce the same outcome. In this case, the cumulative utility frontier is a single straight line and so no trade-offs are possible. So there is no difference between the parallel issue-by-issue and package deal and they produce the same result. If there exists some i, j such that: ≠

,

∙

≠ ,0 < , ≤


=

=

≥

=

∙


100


i.e. ≥ where and represent the utilities obtained from the package deal and parallel issue-by-issue negotiation procedures respectively. For all the other scenarios, if the optimal agenda has + 1 issues, the proof becomes the same as that of Scenario . If the optimal agenda contains only i issues < + 1, then again by the inductive hypothesis the result becomes true. Thus, we have the result that the package deal produces a result that is no worse than the parallel issueby-issue negotiation. Thus by induction we prove the above result for n-issue negotiation.

V.

auction. Those who want to participate in the auction by this auctioneer, participate via their own bidding agent who knows bidder’s preferences such as reservation price, utility factor, etc. With this information, the bidding agent can make intelligent decision to win the bidding. When the bidder joins the auction, it will get information about the item/issues on which bidding is going to take place. After getting these details, a bidding agent can choose the items for bidding. Then the bidding agent can start bidding. If another bidding agent bids for a higher bid value than the current bid value called by some bidding agent, this information is passed to all other participating bidding agents. Upon this new bid, each bidding agent calculates it's next bid value based on current bid value, reservation price, current time, utility factor, etc. After calculating this next best bid value, agent announces its new bid value and waits for another higher bid value or end of auction. If there is no other agent bid with a higher bid value after this, this bidding agent wins the item/issue. Here, the next bid value is generated using a simple calculation involving reservation price, utility factor and current time:

Experimental Result

The above model has been simulated to evaluate the multi-issue negotiation in an auction environment using multi-agent system to give an experimental basis to the multi-issue negotiation model discussed in this paper. Java is used to implement the simulation of online auction. V.1.

Design Details

Simulation is done with the help of a server and client agent. There is facility for auctioning more than one item/issue at a time. Server agent is designed to host an auction. Here, the agent first collects the information (base price, max. time…) for each object and then waits for the bidders to join the auction. When a bidder joins the auction, server sends the list of items to the bidder and creates a new agent to deal with that bidder. Server keeps a record of current leading bid amount and the bidder who bid that amount for each item/issue. This agent receives bid amount called by the corresponding bidder and discards or accepts that bid amount depending on the current maximum bid amount. If that call is accepted then it informs all other bidders about the new largest bid amount. Thus we achieve the goals of an auctioneer via these agents. Client agent is designed to participate in the auction hosted by the server agent. Whenever it joins an online auction it receives the list of items/issues available for bidding. And client agent collects information like reservation price, discount factor, etc. With the help of these information client calculates next bid value and utility values suitable for the bidder and participates in the auction. V.2.

(

)

=

+

−

×(

+

)

where, is current bid value, is reservation price, is discount factor, t is the time difference between current time and starting time of bid, is total duration of bidding. Using the above equation next bid value is calculated. According to this new bid value, utility of bidder and auctioneer is calculated and recorded. Utility for bidder is calculated using the equation: =(

−

)×

and for auctioneer the equation is: =(

−

)×

where bp is base price and is the discount factor of auctioneer. Whenever the bidding agent makes a bid value, utility is calculated and recorded. Using the utility of bidder and auctioneer, a graph is plotted for each item/issue. By taking the resultant of all utility graphs plotted for each issue, we will get a resultant graph. If the resultant graph passes through the first quadrant, where both bidder and auctioneer have positive utility, we can assure that there is a region with positive utility for both auctioneer and bidder, where they can agree on the items/issues. The graphs shown in Figs. 5 to 8 are obtained while running the simulation for different inputs to study different scenarios. Three issues/items are used for bidding. There are 3+1 graphs, one for each scenario and the resultant. The solid lines named A1, A2 and A3 are

Working

According to the above design, a simulation of online auction is implemented. In order to run the simulation, first the agent of auctioneer starts working; auctioneer agent conducts an auction to sell its items/issue with maximum utility. Auctioneer agent collects information such as number of issues/items to sell and the details such as base price, maximum time, etc. and starts Copyright © 2013 Praise Worthy Prize S.r.l. - All rights reserved


101


the graph obtained from the utilities calculated and a best fit line (dotted line) is drawn for each issue. Equivalent of the 3 best fit lines, corresponding to each issue in the utility graph, is drawn as the resultant graph. In the graphs, X-axis is the utility of bidder and Y-axis is the utility of auctioneer.

quadrant, utility frontier of issue A1 lies in fourth quadrant, where utility of auctioneer is negative and utility frontier of issue A2 lies in second quadrant, where utility of bidder is negative. But the resultant of three issues has a part which lies in first quadrant, where both the agents can come to an agreement. Thus there can be a zone of agreement even though two issues do not have a zone of agreement. Graph in Fig. 7 is plotted with values in Table III.

V.2.1. Scenario S0 In this scenario, all the three issues have a zone of agreement. Thus both the agents prefer an agreement on issues , and over no deal and their utility frontiers will lie in the first quadrant. As shown in Fig. 5, the resultant also lies in first quadrant. Values for plotting the graph Fig. 5 is given in Table I, which is obtained from simulation.

Fig. 6. Scenario S1

A1

Fig. 5.

A1 Ua 310 189 113 77 50 ….. …..

Ub 97 220 284 329 341 ….. …..

=

=

TABLE I SCENARIO S0: = = A2 Ua Ub 1078 436 888 613 550 857 401 1079 261 1180 167 1223 105 1224

V.2.2.

Ua -383 -818 -1116 -1256 -1345 -1351 …..

A3 Ua 2826 1772 1043 669 418 258 …..

Ub 440 1083 1586 1919 2181 2334 …..

TABLE II SCENARIO S1 A2 Ua Ub 4376 234 2708 619 1848 915 1240 1125 861 1284 580 1372 410 1443

A3 Ua 4660 3451 2571 1848 1350 961 674

Ub 447 792 1059 1239 1371 1437 1454

Ub 355 730 1339 1838 2200 2455 …..

Scenario S1

In scenario S1 only two issues have a zone of agreement while the third one will be in second, third or fourth quadrant. Here the utility frontier of issues A2 and A3 lies in the first quadrant but utility frontier of issue A1 lies in the second quadrant, where utility of bidder is negative but the resultant of three issues has a part lying in the first quadrant, where both the agents can come to an agreement. Thus there is no need that all the issues have a zone of agreement to reach a successful negotiation but if two issues are in zone of agreement, then there will be a zone of agreement for all issues together. Table II contains the values used for plotting Fig. 6.

Fig. 7. Scenario S2

A1 Ua -1461 -3934 -5860 -6973 -7446 -8163 -8813 -9125 -9267 -9620

V.2.3. Scenario S2 Here the utility frontier of issue A3 lies in first


Ub 1499 4177 6379 7801 8630 9647 10589 11190 11604 12216

TABLE III SCENARIO S2 A2 Ua Ub -373 -5398 -1740 -3446 -2103 -2438 -2706 -1816 -2868 -1122 -3352 -614 ….. ….. ….. ….. ….. ….. ….. …..

A3 Ua 13678 13217 12847 12577 12229 11586 10890 10234 9534 …..

Ub -9009 -7819 -6577 -5306 -4182 -3486 -2897 -2358 -1909 …..


102


V.2.4.

Scenario S3

the agenda-procedure combination in an n-issue negotiation. This was experimentally verified using a simulation for online auction.

From the Figure 8, it follows that as time passes, the utility of auctioneer increases and utility of bidder decreases. Along this change, there is no first quadrant region for items A1 and A2. But for the resultant of A1, A2 and A3, there is positive quadrant region which is what we need for a successful negotiation. Similarly, we can prove that there is a positive quadrant desirable region for any multi-issue negotiation which leads to a successful negotiation. Therefore there is a bid value possible for both auctioneer and bidder where there is positive utility for both of them. Values in Table IV are used to plot the graph in Fig. 8.

References [1]

[2]

[3]

[4]

[5]

[6]

[7] Fig. 8. Scenario S3

A1 Ua 4319 3592 3064 2562 2131 1756 1434 1165 938 745 601 471

Ub -934 -596 -418 -276 -181 -116 -73 -45 -27 -15 -9 -5

TABLE IV SCENARIO S3 A2 Ua Ub -459 462 -1137 1225 -1664 1836 -2015 2269 -2139 2468 -2212 2604 ….. ….. ….. ….. ….. ….. ….. ….. ….. ….. ….. …..

[8] A3 Ua 3496 2560 1875 1236 778 ….. ….. ….. ….. ….. ….. …..

Ub 570 1022 1380 1582 1669 ….. ….. ….. ….. ….. ….. …..

[9]

[10] [11]

[12]

[13]

VI.

Conclusion [14]

The effect of varying the agenda and procedure on the negotiation outcome was studied in general and an auction system was examined in particular. Initially, an equilibrium strategy was defined for both the agents for both package deal and parallel issue-by-issue negotiation procedures. The different scenarios under which negotiation can take place were then determined. On the basis of this strategy, the optimal agenda-procedure combinations for the different scenarios were determined. This was first done for a 3-issue model and later extended to an n-issue negotiation model. It is found that different agenda-procedure combinations will have a marked impact on the negotiation outcome and it is possible for the agents to have identical preferences for

[15]

[16] [17]

[18]

[19]


Garcia. A, Giese.H, Romanovsky.A, Choren R, Leung. H-f, Lucena .C, Klein. F0, Platon E(2006), Software Engineering for Large Scale Multi Agent Systems-SELMAS 2006, Workshop Report, ACM SIGSOFT Software Engineering Notes, Volume 31, Number 5, 24-31, September 2006. Fatima S S, Michael Wooldridge, Jennings N R. Optimal Agendas for Multi Issue Negotiation, AAMAS Melbourne Australia, ACM 2003. Kuwabara K and Lesser V R. Extended protocol for multistage negotiation. In Proceedings of the Ninth Workshop on Distributed Artificial Intelligence, pages 129-161, Rosario, Washington 1989. Conry S E, Meyer R A , and Lesser V R. Multistage negotiation in distributed planning. Readings in Distributed Artificial Intelligence, Morgan Kaufmann Publishers, Inc., San Mateo, California, pages 367-384, 1988. Kreifelts T and Frank von Martial. A negotiation framework for au-tonomous agents. In Proceedings of the Second Euro-pean Workshop on Modeling Autonomous Agents and Multi-Agent Worlds, pages 169-182, Saint-Quentin en Yvelines, France, August 1990. Laasri B, Laasri H, and . Lesser V R. Negotiation and its role in cooperative distributed problem problem solving. In Proceedings of the Tenth International Workshop on Distributed Artificial Intelligence, Bandera, Texas 1990. Sarit Kraus and Jonathan Wilkenfeld.(1991) Negotiations over time in a multi agent environment: Preliminary report. In Proceedings of the Twelfth International Joint Conference on Artificial Intelligence, Sydney, Australia, August 1991. Ephrati E , Rosenschein J S. The Clarke Tax as a consensus mechanism among automated agents. Proceedings of the Ninth National Conference on Artificial Intelligence, Anaheim, California, 1991. Fatima S S, Michael Wooldridge, Jennings N R. Optimal Negotiation of Multiple Issues in Incomplete Information settings, AAMAS New York USA, ACM 2004. Fershtman C. A Note on Multi-issue two-sided Bargaining: Bilateral Procedures, Games and Economic Behaviour, 2000. Lai G, Sycara K, Li C. A Decentralized Model for Multi Attribute Negotiations, Proceedings of ICEC 2006 August Fredericton Canada, ACM , 2006. Jennings N. R., Faratin P, Loumuscio A. R, Parsons S, Sierra C and Wooldridge M. Automated Negotiation: Prospects, Methods and Challenges, Journal of Group Decision and Negotiation, Volume 10, 2001. Malone T, Fikes R, and Howard M, The Ecology of Computation . In B. A. Hu-berman (Ed), Enterprise: A marketlike task scheduler for distributed computing environments, (North-Holland Publishing Company, Amsterdam, 1988). Smith.R G. A Framework for Problem Solving in a Distributed Processtng Environment, PhD. thesis, Stanford University, 1978. Rosen-schein J S , Genesereth M R. Deals among ratio-nal agents. In Proceedings of the Ninth International Joint Conference on Artificial Intelligence (pages 91-99, Los Angeles, California, August 1985). Durfee E H. Coordination of Distributed Problem Solvers. Kluwer Academic Publishers, Boston, 1988. Sycara K P.(1988). Resolving goal conflicts via negotiation. In Proceedings of the Seventh National Conference on Artificial Intelligence (pages 245-250, St, Paul, Minnesota, August 1988). Enrico Gerding, David Van Bragt and Han La Poutre. Multi-Issue Negotiation Processes by Evolutionary Simulation, Validation and Social Extensions, Workshop on Complex Behavior in Economics at Aix-en-Provence, France 2000. Fatima S S, Michael Wooldridge, Nicholas R. Jennings. Approximate and Online Multi-Issue Negotiation, AAMAS’07, Honolulu, Hawai, USA 2007.


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[20] Minyi Li. On Efficient Mediation Approach to Multi-issue Negotiation with Optimal and Fair Outcomes, Proc. of 9th Int. Conf. on AAMAS 2010, Toronto, Canada, 2010. [21] Fahmida Abedin, Kuo-Ming Chao, Nick Godwin, Hisbel Arochena. Preference Ordering in Agenda Based multi-issue negotiation for Service Level Agreement, 2007. [22] R. Saouli, M. Akil, T. GrandPierre, Load Balancing and Static Placement/Scheduling Heuristic on Distributed Heterogeneous Architecture, (2007) International Review on Computers and Software (IRECOS), 2 (3), pp. 227-234. [23] M. Khemakhem, A. Belghith, Agent Based Architecture for Parallel and Distributed Complex Information Processing, (2007) International Review on Computers and Software (IRECOS), 2 (1), pp. 38-44.

Abraham T. Mathew, born in 1959, earned his PhD in Control Systems from Indian Institute of Technology, Delhi in 1996. He is now working as the Professor in Electrical Engineering in the National Institute of Technology Calicut, Kerala, India. He is the member of IEEE, Life time Fellow of the Institution of Electronics and Telecommunication Engineers, and Life Member of the Indian Society for Technical Education. He is currently engaged in research applied to the areas of robust control in industrial drives, power systems and process control, computational intelligence, smart instrumentation, and specifically in the research and development of bio-mimicking articulated vehicles and the related robust path planning methods. He is reviewer of a number of international journals and the member of the technical committee of a number of international conferences. Dr Abraham is also actively engaged in the study of the cybernetics and informatics applied to the Indian higher technical education in the context of academic globalization. E-mail: [email protected]

Authors’ information Saidalavi Kalady received his Bachelor’s degree in Computer Science and Engineering from the University of Kerala, India, in the year 1993. He did his Master of Engineering in Computer Science and Engineering from the Department of Computer Science and Automation, Indian Institute of Science (IISc), Bangalore, India in 2002. He is currently working as an Assistant Professor in the Department of Computer Science and Engineering of the National Institute of Technology Calicut, India. His present research interests include Multi-agent Systems and Data Mining. E-mail: [email protected] Dr. V. K. Govindan is currently serving as Professor of Computer Science and Engineering Department and Dean Academic, National Institute of Technology, Calicut, India. He received Bachelor’s and Master’s degrees in Electrical Engineering from National Institute of Technology (the erstwhile Regional Engineering College), Calicut in the year 1975 and 1978, respectively. He was awarded PhD in Character Recognition from the Indian Institute of Science, Bangalore, in 1989. He has over 33 years of teaching experience in the capacity of Lecturer (1979-87), Asst. professor (1987-98) and Professor (1998 onwards). He was Head of the Department of Computer Science and Engineering during January 2000 to August 2005. His research areas of interest include medical imaging, agent technology, biometrics based authentication, data compression, and distributed computing. He has over 90 research publications in various international journals and conferences, and authored several books on Operating systems and Computer basics. He has produced six PhDs and currently guiding seven PhD students. He has reviewed papers for many conferences and journals including IEEE Transactions and evaluated several PhD theses. E-mail: [email protected]



104


A Low Voltage Low Power Triple-Band CMOS LNA with Forward Body Biasing Technique B. Razeghi1, S. A. Ziafati Bagherzadeh1, M. Hosseinpour2, A. Dorari Ramezani2, M. R. Saraninezhad2 Abstract – A low voltage low power Triple-Band CMOS Low Noise Amplifier (LNA) is presented in this paper. This design covers Wireless standards such as Wi-Fi, ZigBee and WiMAX. By using forward body biasing of MOSFET and current reuse topology, the proposed LNA can operate at a reduce supply voltage and power consumption while simultaneously maintain high gain and good matching. Using 0.18 um CMOS process, the proposed LNA is designed at 2.4 GHz, 3.5GHz and 5.2GHz, it provides 14.5 dB, 12dB and 11.5dB voltage gains and 4dB, 3.8dB and 4.7dB Noise Figure respectively. Furthermore, the LNA exhibits input matching to 50ohm with S11 of -11dB, 20dB and -17dB while drawing 8.6mW from a 1.2V supply voltage. In addition, the proposed LNA has been redesigned for ultra low voltage of 0.7V and 3.9mW power consumption. Copyright © 2013 Praise Worthy Prize S.r.l. - All rights reserved.

Keywords: Wireless Standards, Triple-Band LNA, Body Biasing, Current Reuse Topology, Low Voltage, Low Power

I.

Introduction

One of the most recent and interesting evolution in the wireless communications area is the trend toward the Multi-standard system into the wireless device, due to proliferation of different wireless standard [1],[2]. Beside, modem wireless applications necessitate communication systems with more functionality and flexibility. Therefore, multi-standard RF transceivers integrated using CMOS processes are predicted to play a critical role in the future wireless communication system. If we can combine two or more RF standards into one transceiver, it will reduce cost and improve integration in advanced [3]. In the receiver path the main RF block is the low noise amplifier (LNA), because it dictates the sensitivity of the entire front-end system. Besides presenting a very low noise figure (NF), the LNA also account for actual requirement of multi-standard operation. In order to implement multi-standard LNA the first way is using three parallel LNAs, which is obviously not a costefficient solution [2], [3]. Second one is wide-band modes of operation, which is more sensitive to out of band unwanted signals [2]. These out of band blockers can severely degrade receiver’s sensitivity. Third way is alternated (or switched) approach. While switching between bands improve versatility, is not sufficient in the case of a multi-functionality receiver where more than one band needs to be simultaneously. Then our approach uses the same signal path and circuitry for all standard, it present reduced power consumption and Chip area according to Fig. 1.

The described methodology has been applied to design a concurrent triple-band LNA dedicated to IEEE 802.11a/b/g/n (2.4-5.2 GHz) known as Wi-Fi, IEEE 802.16 or license Worldwide Interoperability for Microwave Access (3.5 GHz) known as WiMAX and IEEE 802.15.4 or Wireless Personal Area Networks (2.4 GHz) known as ZigBee wireless standards. The three resonant frequencies, fr1, fr2 and fr3, are set to 2.4 GHz, 3.5 GHz and 5.2 GHz, respectively. Many high gain amplifier topologies have been proposed as a way to satisfy the requirement for low power dissipation as well as high performance. The cascode and inverter are some of the widely used high gain amplifier topologies [3].



Fig. 1. Triple-band receiver

II.

105

Triple Band Topology and Application

B. Razeghi et al.

Moreover, the transconductance of the cascode amplifier is limited by the transconductance of the common–source stage only. Similarly the high frequency gain of the inverter can also be significantly degraded by the substrate parasitic and this one involves more components for the input and output matching. Fig. 2 shows an approach to boost gain through the multiplication of the transconductance of the two cascading stage. M1 is the input common-source stage with the source inductive degeneration. This can be considered as a two stage cascade amplifier. The signal amplified by M1 is coupled to the gate of M2 by Cr2 while the source of M2 is bypassed by Cr1. Thus, we have:

V Z L Z d 1 g m1 g m 2 AV  out   Vin 1  g m1Z s1 1  g m 2 Z s 2 

III. Forward Body Biasing Technique The performance of cascode degrades significantly as the supply voltage decreases for low-voltage applications, then a folded topology was proposed, but the inherently low gain is one of the major concerns [5]. By using forward body bias of MOSFET, the voltage and consequently power decrease. For a standard CMOS process, the threshold voltage can be manipulated by the dc bias at the body terminal, adding one more degree of freedom in circuit designs. Typically, the threshold voltage of n-channel MOSFET is given as:

Vt  Vt 0  



2 F  VSB  2 F



(2)

where VSB is the source-to-body voltage, Vt0 is the threshold voltage for VSB=0,  is a process-dependent parameter,  F is a semiconductor parameter with a typical value in the range of 0.3–0.4 V [5]. Since this technique effectively lowers the threshold voltage, the MOSFETs can operate at a reduced bias voltage while maintaining equivalent device characteristics in terms of gain, linearity, and almost noise figure [6]. Although increasing Vbs lead to decreasing threshold voltage, we should be careful that increasing more than 0.5V cause to turn on diode which is located between body and source. As a consequence, it has been chosen 0.5V. In order to prevent the excessive junction conduction, RB a current-limiting resistor is included at the body terminal. Fig. 3 shows the implementation of the proposed forward-body-bias technique in a triple-well CMOS technology.

(1)

 Z L Z d 1 g m1 g m 2 ZS1, ZD1 and ZS2 are the impedances that seen at source and drain of M1 and source M2 respectively. Inductive source degeneration (Ls), offers a good compromise between gain, NF, linearity, isolation and power consumption. LNA’s gain is inversely proportional to Ls, while its linearity (ICP1, IIP3) is directly proportional to the selected value. However, the impedance level presented by this inductance is considerably different for the three involved frequencies. This simultaneously influences LNA gain and linearity performances. For high operating frequency (5.2 GHz), Ls value should be considerably small to maintain an acceptable gain level. However, for low operating frequency (2.44 GHz), the value of Ls inductance should be relatively large to fulfill the LNA linearity requirements.

Fig. 3. Forward-body-bias technique in a triple-well CMOS

IV.

Input and Output Matching

The input of the LNA is either fed directly by the antenna or is connected to the antenna through a band pass filter, a duplexer/diplexer, or both [1], [2]. In any case, the impedance looking into the input of the LNA should be power matched (e.g., complex conjugate matched) to the impedance of the preceding stage for maximum signal power transfer [1]. The input impedance matching is shown in Fig. 4, to achieve the triple band input matching which includes Lin1, Cin1, Lin2, Cin2, Lin3, Cin3, L2, C2 and r.

Fig. 2. Current reuse Triple-Band LNA topology



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raises to 0.6 V [6]. Generally, the noise performance of any noisy two-port network can be represented by:

NF  NFmin

C2 is the gate-source capacitance of M1. The input impedance of the input stage can be written as:

g L 1  m1 s sC gs C gs

(3)

The filter is adopted at the input to resonate in three bands. In Fig. 4, Cgs1 is gate to source capacitance. In the output of the LNA, we find an RLC network. The use of three inductors and three capacitors provides three different resonance frequencies. The output-matching network of the LNA is shown in Fig. 5. The additional challenge when using a resonator load is to adjust the impedance levels at different resonance frequencies by means of on-chip inductors.

ib 2 

   opt Z o  s

1     1   2 s

2

2

(4)

opt

2 4k BTRsub g mb f

1   Rsub Csub 

2

(5)

where KB is the Boltzmann’s constant, T is the absolute temperature, Δf is the frequency, gmb is the bulk transconductance, Rsub and Csub are the substrate resistance and capacitance. By increasing in VBS the noise figure will enhance, but in [6] is shown that if VBS be less than 0.5V, the effect of substrate resistance noise on the NF can be ignored.

VI.

Design Consideration

The proposed triple band LNA has been designed and simulated in 0.18 um. This LNA consumes 8.6 mW power under 1.2 V supply voltage. The performance of LNA is described below. The simulated small-signal characteristics are depicted in Figs. 6 and Figs. 7 indicating a gain of 14.5 dB, 12dB and 11.5dB a noise figure of 4 dB, 3.8 dB and 4.7 dB at 2.4 GHz, 3.5 GHz and 5.2 GHz respectively. The input and output ports are matched to 50Ω. In addition, the large-signal behavior of LNA (IIP3) is evaluated and the results are -2.8 dBm at 2.4 GHz, -4.1 dBm at 3.5 GHz and-0.4 dBm at 5.2 GHz.

Fig. 5. Output of the two Triple Bands

V.

Rn

where NFmin is the minimum NF, Rn is the equivalent noise resistance, Zo is the characteristic impedance, Γs is the source reflection coefficient, and Γopt is the optimum source reflection coefficient that results in NFmin. Although substrate resistance noise is often regarded as a second-order noise, but NFmin and Rn could be strongly affected by this noise source. Therefore, it should be carefully accounted when doing noise calculation and noise optimization. The substrate resistance noise is given by the following expression:

Fig. 4. Input Triple Bands filter of the LNA

Z in  sLs 

4   

Noise Figure Consideration

Classic noise optimization theory, shows that the minimum NF is achieved if the source impedance Zs=Zopt. Although the increase of NFmin is small at low forward substrate bias, it becomes significant when VBS

(b)

(a) Figs. 6. Simulated S21 and NF of the circuit



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(a)

(b) Figs. 7. Simulated S11 and S22 of the circuit

Technology Frequency Supply.voltage DC power Power gain NF S11 IIP3 FOM

Unit um GHz V mW dB dB dB dBm (V)-1

2.4

14.5 4 -11 -2.8 0.107

TABLE I(a) PERFORMANCE COMPARISON OF LOW VOLTAGE LOW POWER LNA This work,1 [3] [7] 0.18CMOS 0.18CMOS 0.18CMOS 3.5 5.2 2.4 3.5 5.2 1.8 2.4 5.2 1.2 1.4 1.8 8.6 13.5 56 12 11.5 11.79 11.7 10.06 10.1 10.8 11 3.8 4.7 3.89 4.03 3.73 3.72 4.7 6.37 -20 -13 -10.37 -10.41 -13.56 -10 -10 -19 -4.1 -0.4 -3 -2.1 -0.4 1.7 0 4.5 0.065 0.112 0.042 0.051 0.065 0.02 0.012 0.023

TABLE I(b) COMPRESSION OF PROPOSED LNA WITH TWO SUPPLY VOLTAGE Unit This work,1 This work,2 Technology um 0.18CMOS 0.18CMOS Frequency GHz 2.4 3.5 5.2 2.4 3.5 Supply.voltage V 1.2 0.7 DC power mW 8.6 3.9 Power gain dB 14.5 12 11.5 11.5 8.7 NF dB 4 3.8 4.7 4 4.3 S11 dB -11 -20 -13 -9.5 -12 IIP3 dBm -2.8 -4.1 -0.4 -6.5 -4.2 FOM (V)-1 0.107 0.065 0.112 0.121 0.14

Moreover, the proposed LNA has been redesigned for ultra low voltage. Its power dissipation is only 3.9mW with the supply voltage of 0.7V. Finally, Tables I summary the performance of the designed LNA along with result from previously published works for comparison. To evaluation of this work, a figure of merit (FOM) is defined as: FOM 

Gain  abs  IIP3  mW  VDD  V  NF  abs  Power  mW 

5.2

9.6 5.2 -12 -1.7 0.218

Furthermore, the proposed LNA has been redesigned for ultra low voltage of 0.7V and consuming only 3.9mW power. In addition, other specifications of this design are acceptable. The proposed techniques are well suited for low-voltage and low-power RF applications at multi gigahertz frequencies.

References (6)

[1]

It is clear that, with the proposed circuit technique enhanced LNA performance is demonstrated exclusively for low-voltage and low power RF application.

[2]

[3]

VII.

[8] 0.18CMOS 945 2.5 3.5 1.8 32 18 23 24 4.6 4.43 4.42 -7 -15 -10 -12.8 -15.3 -14.7 0.0024 0.0026 0.0034

Conclusion

In this work, by applying forward body basing and also current reuse techniques, the proposed LNA can operate at a reduce supply voltage for Triple-Band applications. The proposed LNA consumes 8.6 mW under 1.2 V. Voltage gain is 14.5dB, 12 dB and 11.5 dB for 2.4 GHz, 3.5 GHz and 5.2 GHz respectively.

[4]

[5]

[6]


M.Brandolini, P. Rossi,, D. Manstretta, F. Svelto, “Toward Multistandard Mobile Terminals—Fully Integrated Receivers Requirements and Architectures,” IEEE Trans. on Microwave Theory And Techniques, VOL. 53, NO. 3, MARCH 2005. H.Hashemi, and A.Hajimiri,“Concurrent Multiband Low-Noise Amplifiers—Theory, Design, and Applications,” IEEE Trans. on Microwave Theory And Techniques, Vol. 50, No. 1, January 2002. Chih-Yuan Kao, Yueh-Ting Chiang, Jeng-Rern Yang, “A Concurrent Multi-Band Low-Noise Amplifier for WLAN/WiMAX Applications,” IEEE International Conference on Electro/Information Technology, (EIT) 2008. B.Sidhu, H.Singh, A.Chhabra, “Emerging Wireless Standards WiFi, ZigBee and WiMAX,” World Academy of Science, Engineering and Technology 2007. Hsieh-Hung Hsieh, Jih-Hsin Wang, Liang-Hung Lu, “GainEnhancement Techniques for CMOS Folded Cascode LNAs at Low-Voltage Operations,” IEEE Trans. On Microwave Theory And Techniques, Vol. 56, No. 8, August 2008. H.Su, H.Wang, T.Xu R.Zeng, ‘Effects of Forward Body Bias on


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[7]

[8]

High-Frequency Noise in 0.18-um CMOS Transistors’ IEEE Trans. on Microwave Theory And Techniques, VOL. 57, NO. 4, APRIL 2009. C.S.Wang,C.Li,K.Wang,” A Multi-Band Multi-Standard RF Front End For IEEE 802.16a and IEEE802.11a/b/g Application,” IEEE International Symposium on Circuits and Systems, 2005. ISCAS 2005. C.W.Ang, Y.Zheng1, C.H.Heng,’ A Multi-band CMOS Low Noise Amplifier for Multi-standard Wireless Receivers’, Proceedings of the IEEE international symposium on circuits and system, 2007, pp. 2802–2805.

Mostafa Hosseinpour was born in Iran in May 1987. He obtained the B.Sc. degree with honors in power engineering from Sadjad Institute of Higher Education, Mashhad, Iran, in 2011.Since 2012, he received the M.Sc. degree in Power electrical engineering from Ferdowsi University of Mashhad, Mashhad, Iran. His current research interests include power electronic circuits, renewable energies, smart grid and power market Amin Dorari Ramezani was born in Iran in April 1988. He obtained the B.Sc. degree with honors in power engineering from Sadjad Institute of Higher Education, Mashhad, Iran, in 2011.Since 2011, he is a M.Sc. student (power electronicfield) at Sadjad institute of Higher Education, Mashhad, Iran. His current research interests include power electronic circuits, renewable energies, smart grid and power market.

Authors’ information 1

Ferdowsi University of Mashhad, Mashhad, Iran.

2

Sadjad Institute of Higher Education, Mashhad, Iran

Behrooz Razeghi was born in Iran in August 1989. He obtained the B.Sc. degree with honors in electrical engineering from Sadjad Institute of Higher Education, Mashhad, Iran, in 2012. Since September 2012, he is a M.Sc. student of electrical engineering (communication systems field) at Ferdowsi University of Mashhad, Mashhad, Iran. His current research interests include sensor data fusion, information theory & coding, communication circuits, and wireless ad hoc networks.

Mohammad Reza Saraninezhad was born in Iran. He received the B.Sc. degree in electrical engineering from Sadjad Institute of Higher Education, Mashhad, Iran, in 2012. His current research interests include power electronic, circuit design and also power systems.

Seyyed Amir Ziafati Bagherzadeh was born in Iran in January 1989. He received the B.Sc. degree in electrical engineering from Sadjad Institute of Higher Education, Mashhad, Iran, in 2011. He is currently M.Sc. student of electrical engineering (communication systems field) at Ferdowsi University of Mashhad, Mashhad, Iran. His research interests include communication circuits, artificial intelligence, neural networks, image signal processing, and data fusion. He is currently worked on data security and cryptography.



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A New Approach to Component-Based Development of Software Architecture Sabah Al-Fedaghi1, Ahmed Abdullah2 Abstract – Information system architecture handles requirements of information and systems to support a business through describing structural and behavioral capabilities of the system. Software architecture is defined in terms of computational components and interactions among those components. In this context, component-based development is an approach considered the most promising way of developing information systems. Typically, UML 2 component diagrams are used as an architecture-level artifact for modeling business and technical software architectures. Nevertheless, UML notation in and of itself is insufficient for creating meaningful component models. This paper asserts that this difficulty in creating meaningful component models has originated from the use of UML diagrams; furthermore, the paper proposes an alternative flow-based diagramming methodology for software architecture development. The new concept presented in the paper is development of a hierarchy of components on the basis of this flow-based representation. The viability of this idea is demonstrated through a study case of an actual system. Copyright © 2013 Praise Worthy Prize S.r.l. - All rights reserved.

Keywords: Software Architecture, Component-Based Software Development, Conceptual Modeling, UML

System architecture refers to the way components are structured together to form a unified system. Accordingly an Information Technology (IT) Architecture is a blueprint that is developed, implemented, maintained, and used to explain and guide how an organization’s IT and information management elements work together to efficiently accomplish the mission of the organization [1]. IT architecture deals with the ways in which information and system needs will be supported by technology [2]. It “describes the relationships among the work the agency does, the information the agency uses, and the information technology that the agency needs” [3]. This paper concentrates on a specific domain in this field, that of information system architecture [4][5][6], though the approach may benefit the field of IT architecture in general in those cases where business processes and IT infrastructure are integrated. Information system architecture deals with requirements of information and systems to support a business [2]. It combines elements to create structural and behavioral capabilities of the information system. In this architecture, a conceptual model facilitates communication among users, builders, and management, and as the system is developed, the model is progressively refined. Such a development process requires several architectural activities, including process

architecture, functional architecture, software architecture, and network architecture. The software architecture of a system [7] [8] is defined in terms of “computational components and interactions among those components” [9]. It consists of structures that include software elements, and their relations and properties. In this context, architectural description is an abstract representation of the software system [10]. According to Goulão, et al. [11], three main streams of architectural description techniques are presently available: ad-hoc, Object-Oriented techniques, and Architecture Description Languages (ADLs) [12]. Although ADLs allow for architecture in-depth analysis, their formality is not easily reconciled with dayto-day development concerns. OO approaches to modeling, on the other hand, are more widely accepted in industry. In particular, the UML [13] has become both a de jure and de facto standard. [11] According to Amber [14], “Component-based development (CBD) and object-oriented development go hand-in-hand, and it is generally recognized that object technology is the preferred foundation from which to build components.” (Italics added) Component-based development is an approach emphasizing construction of loosely coupled independent components [15] [16]. “Today component based development is considered to be the most promising way of developing information systems” [17]. A software component is a software module that encapsulates semantically related functions



I.

Introduction

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Sabah Al-Fedaghi, Ahmed Abdullah

or/and data. Interfaces facilitate communication among components. Typically, UML 2 [18] [19] component diagrams are used as “an architecture-level artifact, either to model the business software architecture, the technical software architecture, or more often than not, both of these architectural aspects” [14]. Nevertheless, “the notation itself is not enough to create meaningful component models” [20]. To create models that are “meaningful,” [20] proposes approaching a component modeling task by modeling technical components and functional components, then combining them “into one component model.” This paper claims that the difficulty in creating “meaningful component models” [20], originated in part from the nature of UML diagrams. Further, the paper presents an alternative diagramming methodology that is more suitable for identifying components in software architecture development. Without loss of generality, we will concentrate on the approach to component modeling presented by [20], in which technical and functional components are developed, and then a single-component model is produced as a typical framework for development.

II.

software that can manage classrooms. The “client defines some non-functional requirements such as web-userinterface, services and application-server-based.” A business process comprises four primary processes: resource management, offering management, scheduling, and enrollment management. There are also subprocesses “for managing the individual types of resources, such as facilities, classrooms, equipment and teachers.” Nonfunctional requirements are the following:  Internal use only  A Web-based user interface  A Web-based service for enrollments that interfaces with other in-house systems  Interfaces with other systems The functional component model Based on the client’s explanation and list of use cases, the processes “offering management”, “scheduling”, and “enrollment management” are self-contained processes. Because teacher management is more involved, teachers have their own management process, while management of facilities, classrooms, and equipment is combined into one resource management component. The technical component model (Fig. 1) The technical component model includes the following: 1. One tier divided into three layers: - A Service layer: service components serve as the interface for calls from the outside. - A Logic layer: containing one component per service operation - A Data Access layer 2. The fourth layer is used by external systems and can be one of the following: a Web presentation layer, a Web service Layer, or an Integration layer. In the last step both views are combined into one model view (Fig. 2). “This figure shows the flow for business logic invocation via the web service layer” [20].

Typical Modeling of Components

According to [20], technical components serve as high-level blueprints for the system and can be considered classes composing the system. In a hierarchical breakdown of components where layers include the technical design elements, the functional components serve to structure software from a functional perspective, with separate functional subsystems based on business processes. In addition, a hierarchical breakdown is applied to business processes. Finally, both the technical and functional are combined by visualizing the ways in which the technical framework supports the functional design of the software. Example [20]: An educational organization requires Web presentation layer View

Controller

Service layer Logic layer Session Bean

Data access layer

Web Service layer Web Service

Service Bean

Service Operation Implementation

Data access object

Integration layer Message Processing

Fig. 1. Developing a Technical Component Model (from [20])



111


Web presentation layer View

Controller

Service layer Logic layer Session Bean

Data access layer

Web Service layer Web Service

Service Bean

Service Operation Implementation

Data access object

Integration layer Massage Processing

Enrolment Management Subsystem Web Service call

Enrolment Web Service

Enrolment Service Bean

Enrolment Service Operation

Enrolment Data Access Object

Fig. 2. The Component Model is a combination of the functional as well as the technical component model (from [20])

The data–i.e., business objects—are modeled in a separate view and “indicated by associations [as to] which layer uses which kind of data objects.” At the conceptual level, we claim that the nature of UML diagrams is unsuitable for component-based software development. To demonstrate this, we contrast it with another methodology of conceptual description that provides a more suitable representation. The next section reviews this methodology, called the Flowthing Model, which has been described and applied in several applications [21]–[24]. The example in section IV is a new contribution.

In addition to the fundamental characteristics of flow in FM, the following types of possible operations exist in different stages: 1. Copying: Copy is an operation such that flowthing f => f. That is, it is possible to copy f to produce another flowthing f in a system S. In this case, S is said to be S with copying feature, or, for short, Copy S. For example, any informational flowsystem can be copy S, while physical flowsystems are non-copying S. Notice that in copy S, stored f may have its copy in a non-stored state. It is possible that copying is allowed in certain stages and not in others. 2. Erasure: Erasure is an operation such that flowthing f => the empty flowthing. That is, it is possible to erase a flowthing in S. In this case, S is said to be S with erasure feature, or, for short, erasure S. Erasure can be used for a single instance, all instances in a stage, or all instances in S. 3. Canceling: Anti-flowthing f– (f with superscript –) is a flowthing such that (f – + f) => the empty flowthing, and + denotes the presence of f– and f. It is possible that the anti-flowthing f– is declared in a stage or a flowsystem. If flowthing f triggers the flow of flowthing g, then anti-flowthing f– triggers anti-flowthing g–. An example of the use of these FM features is erasure of a flow, as in the case of a customer who orders a product, then cancels the order, an action that might require the cancellation of several flows in different spheres triggered by the original order. Formally, FM can be specified as FM = {Si ({Fj}, Tl), {(Fij, Fij)}, 1≤i≤n, 1≤j≤m, 1≤l≤t}. That is, FM is a set of spheres S1, ...Sn, each with its own flowsystems Fij,... Fim. T is a type of flowthing T1,..., Tt. Also, F is a graph with vertices V that is a (possibly proper) subset {Arrive*, Accept*, Process*, Create*, Release*, Transfer*}, where the asterisks

III. The Flowthing Model (FM) The Flowthing Model (FM) is a uniform method for representing “things that flow”, called flowthings [17][20]. Flow in FM refers to the exclusive (i.e., being in one and only one) transformation among six states (also called stages): transferring, processing, creation, releasing, arriving, and acceptance. The fundamental elements of FM are as follows: Flowthing: A thing (e.g., information, money, electrons) that has the capability of being created, released, transferred, arrived, accepted, and processed while flowing within and between systems. A flow system (referred to as flowsystem) is a system with six stages and transformations (edges) among them. Spheres and subspheres: These are the environments of the flowthing, such as a transistor, battery, and wire. Triggering: Triggering is a transformation (denoted by a dashed arrow) from one flow to another, e.g., flow of electricity triggers the flow of water. We will use Receive as a combined stage of Arrive and Accept whenever arriving flowthing are always accepted.



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indicate secondary stages. For example, {Copy, Store, and Destroy} can represent these secondary stages.

IV.

Note that Seminars may have their own subsphere and that Seminars (11) has a flowsystem in the Web page (list) bean. For simplicity’s sake, we do not show the flow of seminars from the Seminars subsphere. The seminar list flows to the student (12), who selects (processes) some (13), and the processed page flows back (14) to the system. The selected seminars are processed (15), and here we assume that the seminar file includes information about each seminar. Missing here (not mentioned in Ambler’s original description is the necessity of fetching the student record as part the eligibility processing (e.g., student’s academic standing). As we see here, an FM representation reveals gaps in the conceptual description. Assuming the student is eligible in terms of the criteria for seminars, the process that checks eligibility in the context of schedule (16) is also triggered by using information about schedule (17), as in the case of seminars. Assuming that scheduling is okay, the creation of an invoice for a seminar fee (18) is triggered, and this flows to the student to be processed (19), causing the creation of payment (20) that flows to the system to be processed (21); if everything is okay, the student is registered in the seminar (22). Notice the uniform application of the FM model to system development and as a base for the design phase, and also its utility for constructing the user interface. For example, the student Request interface includes create, release, and transfer requests. The Administrator’s interface includes transfer, receive, and process requests. The new concept introduced in this paper is that instead of use case and UML diagrams to identify components (Fig. 4), we can build a hierarchy of components upon the FM representation (Fig. 5). In Fig. 5, flowsystems are declared to be components (e.g., circle 1: Request in the Student sphere, and circle 2: Request in the System sphere), then a stream of flow (3: Request flow in Student and System spheres). Such an approach presents a systematic methodology for developing architectural modules of the system. Starting at the flowsystem level, a component realizes this flowsystem where the transfer stage corresponds to entry points or ports according to agreed arrangements. Different stages, especially Process, provide a defined autonomy of the component. A flowsystem-based component provides building blocks and reusable entities that are uniformly structured in terms of the six stages, also providing a base for behavior through the notion of flow. Both procedural and object-oriented approaches lack this uniformity. Use of FM as a framework for components can be applied at the levels of requirements, design, and implementation.

Flowthing Model Example

Pichler’s [20] example of an educational organization, described in section II, is based on a “high-level list of use cases … with the client”, but these use cases and the data description are not shown in this model. Consequently, we use an educational example presented in a description by Ambler (“UML 2 Sequence Diagrams”) that is mentioned by [20]. Ambler’s description [“UML 2 Sequence Diagrams] uses cases and sequence diagram to represent Enrol in University, including “the logic for how to enrol in a seminar.” It was developed with stakeholder input to visualize significant methods and services, “such as checking to see if the applicant already exists as a student, which [the] system must support.” Ambler’s UML 2 Sequence Diagrams describe the enrolment process as follows: 1. Student indicates wish to enrol 2. Student inputs name and number 3. System verifies student 4. System displays seminar list 5. Student picks seminar 6. System determines eligibility to enrol 7. System determines schedule fit 8. System calculates fees 9. System displays fees 10. System verifies student’s choice to enrol 11. Student indicates yes 12. System enrols student in seminar [Ambler, “UML 2 Sequence Diagrams”] According to our interpretation of the example, we can develop Fig. 3, which shows the FM representation of university enrolment. The figure includes two spheres: Student and System. The student sphere includes five subspheres: Request, Web page (verification), Web page (list), Fee (invoice), and payment. Note that because each subsphere includes a single flowsystem, one rectangle is used to depict the subsphere and the flowsystem. The System sphere includes seven subspheres: Request, Web page (verification), Web page (list), Eligibility, fee, payment, and registration. In Fig. 3, the process starts at circle 1, where the student generates (creates) a request for enrolment, which flows (2) to the system and is processed (3). This triggers creation of an interface, say, a Web page (4) that flows to the student (5) into which he or she inputs name and number (6). The processed page with its input flows back (7) to the system to be processed; if the information is verified (8), creation of the seminar list (9), which is accomplished by up-triggering (10) of a seminar file in the seminars flowsystem (11). In a different technical language: The seminar System listens to events (9) and “initiate” events (10).

V.

Study Case

Our study case consists of the (manual) information system of a government agency, the Public Institution For Social Security (PIFSS), the workplace of the second author.



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Student

System

2

1 Request

Create

Release

6

Process

Receive

3

Transfer

Transfer

Receive

5 Transfer

Web page Release (verify)

Release

Process

7

Receive

Process

Release Transfer

Transfer

Receive

Process

Web page (verify)

8 Verifiable?

9 Create

12 Receive

4

Create

Transfer

13 Process Web page (list) Release

Request

10

15

Seminars

11

Web page (list)

14 16 Eligibility

Process

19 Fee Payment 20

Process

Create

Receive

Transfer

Release

Transfer

Transfer Transfer Registration

Release

Create

Receive 22

Schedule

18

Process 21

17

Fee

Payment

Process

Fig. 3. FM representation of Seminar enrolment

PIFSS has access to the electronic information system of another government agency, the Civil Service Commission (CSC). The PIFSS system consists of the following components: Module A (Initial application and processing): A citizen applies to be insured under public social security in PIFSS. His or her new application is accessed by PIFSS to start a long manual process that ends by updating the PIFSS’s electronic system. FM modelling of such a process is shown in Fig. 6. In the figure, a citizen registers for insurance in the CSC to create an electronic record in the PIFSS database (circles 1 and 2 in the figure) in the Civil Service Commission. Then: 1. In PIFSS, when such registration is presented to an employee of the Service Management Department, the electronic record of the citizen is accessed (3) to create a hard copy in a folder (4). The folder is processed, then sent to the manager to approve (5), who returns it to the employee. The employee gives the signed folder to a messenger to deliver to the Incoming/Outgoing department (6). 2. A similar process is performed by the Incoming/Outgoing Department (7-9) and Public Record Department (10–12) where the application is registered in their books, approved by managers, and delivered to the next department by messengers. 3. When the application arrives in the Registration Department and after approval by manager (13-15), an employee accesses the original electronic record, creates a new updated record, and uploads it in the database.

Module B (Payments; see Fig. 7): The insured citizen fills out a payment form (1) and gives it to an employee in the Service Management Department. The employee retrieves the citizen’s record from the PIFSS system (2). The employee processes (3) the received form and compares it with the citizen’s record retrieved from the system (4). Then, the form flows to the manager for review and assent (5), and sent back to the employee, who gives it the citizen (6). Next, the citizen takes it to an employee in the Certificates Department (7), to be sent to a manager (8) to sign, and given back to the citizen (9). Finally, the citizen makes a payment and (10) takes the certified form to the casher (11–12), who receives both the form and the payment, processes them, and issues a receipt (13–14). Module C (Application for retirement; see Fig. 8): In Fig. 8, the citizen first completes the application form (1) and gives it to an employee in the Service Management Department. The employee processes it and sends (3) it to the manager, who sends it back, to be given to a messenger (4). Next, the messenger takes it to the Incoming/Outgoing Department. The cycle (5–13) of receiving and processing the form by the employee, reviewing by the manager, and transferring from one department to another through a messenger is repeated in the Incoming/Outgoing department, Public Record Department, and Registration Department (5–13). When the form reaches the employee in the Subscriptions Department (14), it is processed.



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The Component Model Use cases Service layer Session Bean

Web presentation View layer Controll er Web Service layer Web Service Integration Massage layer Processing

Data access layer

Service Operation Implementat ion

Service Bean

Enrolment Management Enrolment Enrolment Subsystem Web Service Service Bean

Web Service call

Sequence diagrams

Logic layer

Enrolment Service Operation

Data access object

Enrolment Data Access Object

Fig. 4. The Component Model was developed on the basis of UML diagrams

Component Component

Student

CreateComponent Release Transfer 1

Request

3

System Request

ComponentProcess Receive 2

Transfer Component

Process Receive Component Web page Release (verify)

Process Receive Component Web page (list) Release

Release Receive

Component

Transfer

Create Component

Transfer

Transfer

Process

Web page (verify)

Verifiable?

Component

Transfer

Release Component Receive

Create Process

Component Seminars Web page (list)

Component Eligibility Component

Process

Schedule Component

Component Fee

Component Process

Payment

Receive

Component Create Release

Transfer

Transfer

Component Transfer Transfer

Release Receive

Registration Component

Create Component Process Component

Fee

Payment

Process

Fig. 5. Developing components from the FM representation

If everything is okay, the employee sends a copy to the Pensions Department (16), and the form is sent to the manager. The manager (15) reviews and assesses the form, and sends it back to the employee, who gives it to the messenger (23). The messenger takes the form to the Document Processing Department (24). Meanwhile, in the Pensions Department (17), the copy is processed, released to the manager (18), and flows to the messenger (19). The messenger (19) takes the copy to the Financial Department. In the Financial Department (20), the copy is processed and sent to the manager (21), who approves it and sends it back to be received by the messenger (22). Finally, the copy arrives in the

Document Processing Department (23). In Document Processing, we have both the application and its copy that are processed by different departments. For simplicity’s sake, we draw the same (heavy) arrow for both of them (24). The new document then goes to the manager (25), to be sent back to the messenger, who takes it (26) to the Preservation Department (27). There, an employee in the Preservation Department processes the document and sends it to the manager (28) to be reviewed and approved. The received final document (29) triggers the employee to input the data to create a final electronic copy (30–31) in the system’s database.



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Fig. 6. FM modeling of Module A

Fig. 7. Module B of the Public Institution For Social Security (PIFSS)



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Fig. 8. Module C of the Public Institution For Social Security (PIFSS)

VI.

The physical folder is then sent to the manager. The MS is updated (data, time, approval date, etc.). When the physical folder is given to the messenger, the transfer is recorded in MS. Thus, we have MS and a physical information system running parallel to each other. MS is useful for monitoring, security, reports, and search (current status of the application). It can be used later to build a fully automated PIFSS information system. In the Service Management Department, Fig. 9 shows the mapping between the conceptual components and the screen generated by software components. The portion taken from Fig. 6 includes: 1. The sphere of the employee, which includes two flowsystems: those of the electronic and hardcopy files. 2. The sphere of the manager, which includes the flowsystem of the hardcopy file 3. The sphere of the messenger which includes the flowsystem of the hardcopy file

Monitoring System

The FM description is a conceptual representation of an actual (manual) information system used by the Bureau of Social Insurances. A component-based approach in this description is to view spheres, subspheres, and flowsystems as (conceptual) components. Software components are to be built upon conceptual components. It was an administrative decision to have manual processing in the PIFSS information system. Accordingly, since our purpose in this paper is to illustrate our proposed component-based software architecture, we propose a parallel monitoring system (MS) of the actual information system that will not interfere with the latter. For example, when an employee in Fig. 6 prints a hardcopy of the new application, the MS system registers information such as folder number, date of printing, time, and summary information.



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Fig. 9. Mapping conceptual components to users’ screens, produced by software components

Fig. 10. Component-based software architecture of the Service Management Department

The employee uses three screens: Main screen (1), Electronic copy screen (2), and Hardcopy screen (3). The broad arrow represents the software that takes the FM representation as a conceptual specification of the requirements and produces the screen. Of course, MS uses databases to save and update information, and other facilities such as printing, … (not shown in the figure), but at this level of description. These come as byproducts of any software system. When the employee opens MS, screen 1 appears; the employee can choose the electronic or the hardcopy files. Suppose the electronic files are selected; screen 2 then appears. In RECEIVE, he/she can find all the new applications to be processed (formatted) and printed in PROCESS. Upon printing an application, he/she can go back to screen 1, to select Hardcopy. In Hardcopy (3), the employee can input further information about the hardcopy, e.g., completed processes such as signed, stamped, registered, … The employee selects sending it to the manager or messenger, e.g., time of sending. Thus, the electronic information goes hand in hand with the physical movement of the hardcopy folder. Similarly, the manager has one screen (4), and the messenger has one screen (5).

Notice the uniformity of the operations on the screens and the original conceptual description. The componentbased software architecture of the Service Management Department is shown in Fig. 10.

VII.

Conclusion

This paper has discussed the problem of difficulty in creating meaningful component models. Alternative flow-based diagramming methodology for software architecture development is proposed. The new concept in the paper is to develop a hierarchy of components on the basis of the conceptual representation. The viability of this idea is demonstrated through examples and a study case of an actual system. The flowthing model is a new concept, and further experimentation is needed to explore its various features. We also need to further explore how to overlay other notions such as synchronization, logical operations, and constraints.

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J. Ward, J. Peppard, Strategic Planning for Information Systems, 3rd ed., John Wiley, 2002. F. D. Raines, Information Technology Architectures, Memoranda 97-16, June 18, 1997, US Government Office of Budget and Management. http://www.whitehouse.gov/omb/memoranda_m9716 R. Mcilree, The Enterprise Architecture Definition Collection Part III. Blog, http://enterprisearchitect.typepad.com/ Office of the Chief Information Officer, Information Technology Plan FY 2012 to 2016, Smithsonian Institution Information Technology Plan. http://www.google.com.kw/url?sa=t&rct=j&q=&esrc=s&frm=1& source=web&cd=1&cad=rja&ved=0CDYQFjAA&url=http%3A %2F%2Focio.os.doc.gov%2Fs%2Fgroups%2Fpublic%2F%40doc %2F%40os%2F%40ocio%2F%40oitpp%2Fdocuments%2Fconte nt%2Fprod01_002345.pdf&ei=_SC3UNKDEs364QT2jYGgBA& usg=AFQjCNHi2QbDo9iODMawyWAmUlv2gH5TdQ&sig2=sa c5vtrjc7rztGKScWIo1Q B. D. Rouhani, S. Kharazmi, Presenting new solution based on Business Architecture for Enterprise Architecture, International Journal of Computer Science Issues, Vol. 9, n. 3, 2012. O. Barais, A.F. Le Meur, L. Duchien, J. Lawall, Software architecture evolution, in T. Mens, S. Demeyer (editors), Software Evolution, pages 233-262, Springer-Verlag, 2008. R. N. Taylor, N. Medvidovic, E. M. Dashofy, Software Architecture: Foundations, Theory, and Practice, Wiley, 2009. M. Shaw, D. Garlan, Software Architecture: Perspectives on an Emerging Discipline, Prentice-Hall, Upper Saddle River, NJ, USA, 1995. ISBN 0-13-182957-2. Ghazvini, G.A., Sharafi, S.M., Emadi, S., Performance modeling of heterogeneous software architectural styles, (2010) International Review on Computers and Software (IRECOS), 5 (6), pp. 652-659. M. Goulão, F. B. Abreu, Bridging the gap between Acme and UML 2.0 for CBD, Specification and Verification of ComponentBased Systems (SAVCBS'2003), at the ESEC/FSE 2003, Helsinki, Finland, 2003. W. Jing,Y. Shi, Z. LinLin, N. YouCong, AC2-ADL: Architectural Description of Aspect-Oriented Systems, International Journal of Software Engineering and Its Applications, Vol. 3, n. 1, 2009. OMG, OMG Unified Modeling Language Specification”, Version 1.5, Object Management Group, March 2003. S. W. Ambler, UML 2 Component Diagrams. http://www.agilemodeling.com/artifacts/componentDiagram.htm W.M.P. van der Aalsta, K. M. van Heeb, R. A. van der Toornb, Component-based software architectures: a framework based on inheritance of behaviour, Science of Computer Programming, Vol. 42, n. 2–3, pp. 129–171, 2002. W. J. Lewis, A Component Framework Model for Information Technology Architecture, The Data Administration Newsletter, TDAN, June 1, 1998. http://www.tdan.com/view-articles/4253 K. van Hee, N. Sidorova, M. Voorhoeve, J. van der Woude, Architecture of Information Systems using the theory of Petri nets, lecture notes. http://www.google.com.kw/url?sa=t&rct=j&q=&esrc=s&frm=1& source=web&cd=3&cad=rja&ved=0CDgQFjAC&url=http%3A% 2F%2Fwww.win.tue.nl%2F~sidorova%2Fpm%2Fdictaatsm1.pdf&ei=d7e2UJDEMYLk4QSHxoCIAQ&usg=AFQjCNEe_ NNfEhkLXEfNse2iGrjM8GxYHA&sig2=rueDzPiwjmuHTdVI4lb5g G. Booch, J. Rumbaugh, I. Jacobson, The Unified Modeling Language. Addison-Wesley, 1999. M. Noureddine, From Software Architecture to UML Class Diagrams, Journal Name, Vol. 4. n. 3, pp. 408–413, 2009. M. Pichler, Diagram: A Component Modeling Example, June 21, 2011. http://applicationarchitecture.wordpress.com/2011/06/21/diagram -a-component-modeling-example/ Al-Fedaghi, S., Annotations of security requirements, (2012) International Review on Computers and Software (IRECOS), 7 (4), pp. 1470-1477. Al-Fedaghi, S., AlZanaidi, D., Flow-based scenarios in mobile communication systems and networks, (2012) International Review on Computers and Software (IRECOS), 7 (1), pp. 83-91.

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Computer Engineering Department, Kuwait University, P.O. Box 5969 Safat 13060 Kuwait. 2

Public Institution for Social Security, Kuwait.

Sabah Al-Fedaghi holds an MS and a PhD in computer science from the Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, Illinois, and a BS in Engineering Science from Arizona State University, Tempe. He has published two books and more than 150 papers in journals and conferences on Software Engineering, Database Systems, Information Systems, Computer/information Ethics, Information Privacy, Information Security and Assurance, Information Warfare, Conceptual Modeling, System Modeling, Information Seeking, and Artificial Agents. He is an associate professor in the Computer Engineering Department, Kuwait University. He previously worked as a programmer at the Kuwait Oil Company and headed the Electrical and Computer Engineering Department (1991–1994) and the Computer Engineering Department (2000–2007). http://cpe.kuniv.edu/images/CVs/sabah.pdf E-mail: [email protected] Ahmed Abdullah has an MS degree in Computer Engineering from Kuwait University. He is a member of the Institute of Electrical and Electronics Engineers (IEEE). His research interests include computer communication and networking. E-mail: [email protected]



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Hybridization of Genetic Algorithm and Neural Network on Predicting Dengue Outbreak Nor Azura Husin, Norwati Mustapha, Md. Nasir Sulaiman Abstract – In Malaysia, prediction of dengue outbreak becomes crucial because this infectious disease remains one of the main health issues in the country. Malaysia has a good surveillance system but there are still insufficient findings on suitable model to predict future outbreaks. While there are previous studies on dengue prediction models, some of these models still have constraints in finding good parameter with high accuracy. The aim of this paper is to propose a more promising model for predicting dengue outbreak by using a hybrid model based on genetic algorithm for the determination of weight in neural network model. Several model architectures were designed and the parameters adjusted to achieve optimal prediction performance. A sample comprising dengue and rainfall data of Kuala Selangor in Selangor, Malaysia collected from State Health Department of Selangor and Malaysian Meteorological Department was used in a case study to evaluate the proposed model. The performance of the overall architecture was analyzed and the result showed that architecture III performed significantly better than other architectures and it is therefore proposed as a useful approach in the problem of time series prediction of dengue outbreak. Copyright © 2013 Praise Worthy Prize S.r.l. - All rights reserved.

Keywords: Hybrid, Neural Network, Regression, Prediction and Dengue Outbreak

I.

Our study of literature on this subject shows that the hybrid model can solve the problem of finding a suitable parameter with the ability to provide rapid and accurate prediction.

Introduction

Dengue has become a significant public health problem in Malaysia. In 2011, the incident rate of dengue is the highest (63.75%) if compared to other communicable disease like malaria, plague, typhus and yellow fever, with the incident rates of 18.32%, 0%, 0.04% and 0%, respectively [1]. This disease predominantly affect in urban and semi urban areas. Approximately 70%-80% of dengue cases are reported in areas where there is a high population density and rapid development activities which contribute to dengue transmission [2]. Under the Prevention and Control of Infectious Diseases Act 1988 (Act 342), all suspected dengue cases must be notified to the nearest health office within 24 hours of diagnosis, followed by written notification within a week [3]. Delay in seeking proper treatment due to lack of emphasis on early warning sign has been identified as the main mortality factor for dengue mortality [4]. In Malaysia, despite having a good laboratory based surveillance system with both serology and virology capability, it is basically a passive system and has little predictive capability [5]. Although there are several recent studies on dengue prediction model in Malaysia, based on our observation some of these models still have constraint in terms of accuracy. So far there has been insufficient discussion about the suitable model to predict future dengue outbreak.

II.

Related Work

While it is crucial to develop a model that could better predict the spread of dengue, initial observation reveals that such a study is rarely done in Malaysia. Lian et al. [6] and Seng et al. [7] studied the prediction of dengue outbreak in Sarawak and Johor respectively by using statistical models. However this model is not a better choice compared to other nonlinear methods in terms of accuracy. Rachata et al. [8] proposed an automatic prediction system of Dengue Haemorrhagic Fever outbreak by using entropy and ANN. However, haemorrhagic form of the disease is a more severe form of dengue compared to DF and it can be fatal if unrecognized and not properly treated [9]. Therefore, prediction by using DF variable is more appropriate compared to DHF itself for early epidemic prevention and control capabilities. Patz et al. [10] conclude in their study that endemic locations may be at higher risk from hemorrhagic dengue if transmission intensity increases. However, they only focus on climate factors without taking into account other variables that are determinant to dengue fever. Besides, previous studies about dengue prediction [8], [11]-[12] revealed that neural network model yielded better predictions but



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Nor Azura Husin, Norwati Mustapha, Md. Nasir Sulaiman

the researcher must adopt a try and error approach to find the best parameter. Although previous work [13]-[15] shows that the hybrid neural network model can solve the problem of finding a suitable parameter that can deliver better model performance than a neural network model or the other standalone model but no such model has been developed to predict the dengue outbreak. Hybrids of machine learning are empirically and formally proven able to outperform single predictors in many cases. Evidence suggests that hybrid models generalize better when they constitute members, which form a various and accurate set.

c) Hidden layer One hidden layer is used in this study. Network never needs more than two hidden layers to solve most problems including forecasting [16]. One hidden layer may be enough for most forecasting problems [17]. The number of hidden layers used in the network is set to one, to give faster speed in convergence [17]. d) Hidden nodes Networks with equal number of hidden and input nodes are reported to have better forecasting results in several studies. However none of these heuristic choices works well for all problems [16]. For this preliminary experiment, the number of hidden nodes is equal to the number of input nodes. e) Normalization process Normalization makes the statistical distribution of each input data roughly uniform. The values are scaled to match the range that the input neurons use. Data normalization methods, which include simple linear scaling and statistical measures of central tendency and variance, remove outliers and spread out the distribution of the data [18]. Normalization process is transforming data from original scale to 0 or 1 scale (minimum and maximum scale). In this study, normalization is done using min-max normalization as the following equation:

III. Data and Implementation Model Weekly data on consultations for dengue outbreak prediction was gathered from the State Health Department of Selangor (SHD) for the year 2004 to 2005. Meanwhile rainfall data was supplied by the Malaysian Meteorological Department (MMD) in the form of daily rainfall records for the same time period. The daily rainfall amount is collected over a 24 hour period beginning from 8.00 a.m. every day. The daily data was averaged into weekly data to correspond to the dengue prediction data. Therefore, four architectures were developed; Architecture I involved dengue cases data, Architecture II involved combination of both dengue cases and rainfall data, Architecture III involved dengue cases data in proximity location, Architecture IV involved the combination of all criterion were developed in this study by using hybrid and regression models. Before the hybrid model can be constructed, data acquisition and preprocessing must be predetermined. The data acquisition and preprocessing is described in the following section.

xn 

x0  xmin xmax  xmin

(1)

where: Xn is new value for variable x, X0 is current value for variable x, Xmin is minimum value in data sample, Xmax is maximum value in data sample. f) Validation sample Testing process is carried out to validate the network on new or unknown data sets, called the testing set. This is a process performed after training the network. A properly built and trained network which can yield the best performance on the validation samples would be the best and most accurate model. If the validation sample outputs are not acceptable then a new network is to be built by repeating the whole process of learning and testing.

III.1. Data Acquisition and Preprocessing The sample used in this study is in the format of weekly time series data. These data are used for the purpose of modeling and to show how these models will be implemented to solve the time series prediction problem: a) Data acquisition There are three data sample sets used in this research namely the sample set for dengue fever (DF) cases, neighborhood dengue cases and the set of sample for rainfall data. The training and testing sample is based on the rule of 80%: 20% ratio. b) Input output nodes The number of input nodes in this study are determined by the number of attributes that exists in the data while the number of output nodes are determined based on the number of target output set which consists of multi-step-ahead. These combination data are chosen because it is practical in terms of data collection time from the SHD. Besides, input data for four weeks is a suitable duration which represents the total case count in one month.

IV.

Hybrid Model for Predicting Dengue Outbreak

IV.1. Design the Hybrid Model: GA Part A hybrid model which is based on genetic algorithm (GA) for the determination of weight in neural network (NN) was used in this study. The design of hybrid model used is shown in Fig. 1. Before a GA is executed, a suitable coding for the problem needs to be devised. The fitness function, which assigns merit to each individual in population, has to be



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formulated.

fitness values computed after extraction of weights and computation of error. 5) Convergence The generation progress until the population converges to the same fitness values. The weights extracted from the converged population are the final weights of the NN. IV.2. Design the Hybrid Model: NN Part NN model part has three main layers which are input, hidden and output layers. In the input layer, the variable of dengue cases, rainfall and proximity location data will be used as input nodes. As in Fig. 2, the input parameters are dengue cases data consist of d, d-1, d-2 and d-3 where d represents dengue cases data for week i, week i+1, week i+2 and week i+3 respectively. Approximate location of dengue cases data consist of n, n-1, n-2 and n-3 where n represents approximate location of dengue cases data for week i, week i+1, week i+2 and week i+3 respectively. Rainfall data consist of r, r-1, r-2 and r-3 where r represents rainfall data for week i, week i+1, week i+2 and week i+3 respectively.

Fig. 1. The design of hybrid model [14]

Next, parents must be selected for reproduction and crossed over to generate offspring. The weight determination of the NN by GA is performed as follows: 1) Coding Firstly we determine NN configuration (l-m-n), number of weight (l+n)m, length of string L=(l+n)md and choose a size of population where l is input neuron, m is hidden neurons and n is output neurons). 2) Weight extraction Next, weight extraction is performed by using this equation [18]:

 xkd  2 10d  2  xkd  310d 3  ...x k 1 d    , d 2  10 if 5  x kd 1  9  wk    d 2  xkd 310d 3  ...x k 1 d  xkd  2 10 ,  10d  2  if 0  xkd 1  5

(2)

x1, x2, ….,xd, … xL represent a chromosome and xkd +1, xkd+2,…, x(k +1)d represent the kth gene (k≥0) in the chromosome. 3) Fitness function Initially a population p0 of chromosomes is randomly generated. Next, the weight sets for the NN are extracted from p0. For each weight set, NN is trained for all the input instances of the given problem. Then, the error in the training is utilized to compute the fitness value for each of the chromosomes by using Eq. (3) [19]:

E

 E1  E2  E3  3

Fig. 2. The NN structure

The output layer will generate the dengue cases. The output from each architecture will be compared to analyze which one produces the most accurate prediction. In output layer, O, O1, O2 and O3 where O represents predicted output of dengue cases for week i+4, i+5, i+6 and i+7 correspondingly. Fig. 2 shows the structure of the adopted neural network.

(3)

4) Reproduction In the next phase, the worst-fit chromosomes are terminated and replaced by best-fit chromosomes. The parent chromosomes are randomly selected in pairs and a two-point cross-over operator is applied to produce offspring. The new population p1 again has its

IV.3. Parameter Used Table I illustrate the architectures with specific parameters used in this experiment. Here, the hybrid model has 4-4-4 and 4-9-4 configuration for architecture I, 8-8-4 and 8-17-4 configuration for architecture II, 8-8-4 and 8-17-4



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configuration for architecture III and 12-12-4 and 12-254 configuration for architecture IV.

suggest whether the relationship between these different locations would be positive or negative.

TABLE I ARCHITECTURES WITH SPECIFIC PARAMETERS Nodes Arch I Arch II Arch III Arch IV Input 4 8 8 12 Output 4 4 4 4 Hidden nodes 4,9 8, 17 8,17 12, 25 Hidden layer 1 1 1 1 Weight 16, 32 48, 96 48, 96 96, 192 Population 80, 160 240, 480 240, 480 480, 960

Architecture I involves only dengue cases data with four inputs, four and nine hidden nodes and four nodes for predicted output. To define the best fitness, the required parameter on GA algorithm for architecture I are 80 and 160 for population size with weight 16 and 160 respectively. Meanwhile, architecture II involves the combination of dengue cases and rainfall data with eight inputs; eight and 17 hidden nodes and four nodes for predicted output. The required parameters on GA algorithm for architecture II are 48 and 96 for population size with weight 240 and 480. Architecture III involves the combination of dengue cases and proximity location data with eight inputs; eight and 17 hidden nodes and four nodes for predicted output. The parameter used on GA for this architecture is the same with architecture III. Finally, architecture IV involves the combination of dengue cases, rainfall and proximity location data with 12 inputs; 12 and 25 hidden nodes and four nodes for predicted output. The required parameters on GA algorithm for architecture IV are 96 and 192 for population size with the weights of 480 and 960.

V.

Fig. 3. The comparison of recognition rate for each parameter

Fig. 4. The comparison of MSE for each parameter

The results indicated that the correlation of dengue cases prediction is significant between approximate locations. Correlation is significant between Sepang and Klang, Klang with Kuala Selangor, and Hulu Langat with Sepang. Figs. 5, 6, 7 and 8 show the comparative results of actual and predicted outputs. The results produced depended a lot on data quality.For example, in the context of dengue cases data, several locations show a wide range of cases, which is inconsistent and varied. In the case of rainfall data, several missing data were identified. Although the responsible authorities assume this missing data as zero cases or no rain, it may produce inaccurate result. At the end of the day, all these situations will not represent the true cases and could disrupt the study on network performance.

Experimental Result

Once the implementations are completed, analysis on test output was conducted to obtain the performance of the hybrid model. This was done by testing the data and measuring their accuracy. Next, the architecture that produced the best result was chosen to simulate the dengue outbreak prediction. We have conducted experiments on the hybrid model using dengue, rainfall and proximity location of dengue cases data which have been normalized to lie between 0 and 1. The performance of the overall architecture was analyze and the results showed that architectures III which involved proximity location dengue cases and dengue cases data is the best architecture with 93.49% of recognition rate compared to architecture I, II and IV with 92.32%, 92.29% and 91.11% of recognition rate respectively (Fig. 3). The best structure of architecture III are eight input, four output, one hidden layer, 17 hidden nodes, 0.9 of learning rate and momentum rate, and using sigmoid activation function with error of 0.065243 (Fig. 4). Pearson correlation was used to test out the correlation significance of predicted output between different locations. In this experiment, the significance level of alpha = 0.05 for 95% confidence and two-tailed test were conducted since there is currently no strong theory to

Fig. 5. The comparison result of actual output 1 and predicted 1



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Acknowledgements I would like to express my sincere appreciation to the State Health Department of Selangor and Malaysian Meteorological Department for their help and support during the data collection process for this study. This study was funded under the Research University Grant Scheme (RUGS) and Ministry of Higher Education Malaysia. Fig. 6. The comparison result of actual output 2 and predicted 2

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[4] [5]

Fig. 7. The comparison result of actual output 3 and predicted 3

[6]

[7]

[8]

Fig. 8. The comparison result of actual output 4 and predicted 4 [9]

VI.

Conclusion and Future Work [10]

The aim of this paper is to propose a more promising model for predicting dengue outbreak by using a hybrid model based on genetic algorithm for the determination of weight in neural network model. Several model architectures were designed with the parameters appropriately adjusted to achieve optimal prediction performance. The results showed that architecture III which involved dengue cases data and proximity location of dengue cases was very effective in predicting the dengue cases data in one, two, three and four weeks in advance respectively. From results, it can be concluded that a hybrid model which is based on genetic algorithm for the determination of weight in neural network model can be a very promising model for predicting dengue outbreak. In future, we plan to broaden the research area into additional four administration districts in Selangor, namely Sepang, Hulu Langat, Hulu Selangor and Kuala Selangor.

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MOH (Ministry of Health Malaysia), Health Fact 2012, Health of Informatics Centre Planning and Development Division MOH/S/RAN/31.12(TR), Vol. 12, pp. 1-13, 2012. Mahiran, M. and Ho, B.K., Clinical Practice Guideline on Management of Dengue infection in Adult, Journal of Malaysian family Physician 2011, Vol. 6, n. 2 & 3, 2011. MOH (Ministry of Health Malaysia), Borang PeraturanPeraturan Pencegahan Dan Pengawalan Penyakit Berjangkit (Borang Notis) 2005. Akta Pencegahan dan Pengawalan Penyakit Berjangkit 1988, 2005. WHO (World Health Organization), Dengue: Guideline for Diagnosis, Treatment, Prevetion and Control, Geneva, 2009. D.J. Gubler, “How Effectivelly is Epidemiological Surveillance used for Dengue Programme Planning and Epidemic Response?”, Dengue Bulletin, Vol. 26, 2002. C.W. Lian, C.M. Seng and W.Y. Chai, Spatial, Environmental and Entomological Risk Factors Analysis on a Rural Dengue Outbreak in Lundu District in Sarawak, Malaysia, Tropical Biomedicine, Vol. 23(1), pp. 85-96, 2006. S. B. Seng, A. K. Chong and, A. Moore. Geostatistical Modelling, Analysis and Mapping of Epidemiology of Dengue Fever in Johor State, Malaysia, The 17th Annual Colloquium of the Spatial Information Research Centre University of Otago, Dunedin, New Zealand, 2005. N. Rachata, P. Charoenkwan, T. Yooyativong, , K., Chamnongthai C. Lursinsap and K. Higuchi, Automatic Prediction System of Dengue Haemorrhagic-Fever Outbreak Risk by Using Entropy and Artificial Neural Network. International Symposium on Communications and Information Technologies (ISCIT 2008), pp. 210-214, 2008. WHO (World Health Organization), Dengue and Dengue Haemorrhagic Fevers, Dengue Bulletin, WHO Fact Sheet 117, http://www.who.int/inffs/en/fact117.html, 2002. J.A. Patz, J.M.M. Willem, A.F. Dana and H.J. Theo. Dengue Fever Epidemic Potential as Projected by General Circulation Models of Global Climate Change, Environmental Health Perspective, vol. 106(3), pp.147-153, 1998. N.A. Husin N. Salim and A.R. Ahmad, “Modeling of Dengue Outbreak Prediction in Malaysia: A Comparison of Neural Network and Nonlinear Regression Model”, International Symposium on Information Technology (ITSIM 2008). pp. 1-4, 2008. H.M. Aburas, B.G. Cetiner, and M. Sari, “Dengue ConfirmedCases Prediction: A Neural Network Model”, Journal of Expert System with Application, vol. 37(2010), pp. 4256-4260, 2010. J. R. Rabunal and J. Dorado, “Time Series Forecasting by Evolutionary Neural Network”, Artificial Neural Networks in Real-Life Applications, vol. 2:3, pp.58-59, 2006. Nor Azura Husin, Norwati Mustapha, Md. Nasir Sulaiman and Razali Yaakob, A Hybrid Model using Genetic Algorithm and Neural Network for Predicting Dengue Outbreak, 2012 4th Conference on Data Mining andOptimization (DMO), 2012 E. S. Yuehjen, Developing a Hybrid Forecasting Model for Body Fat, (2010) International Review on Computer and Software (IRECOS), 5 (4), pp. 464-469. G. Zhang, B.E. Patuwo, and M.Y. Hu, Forecasting with Artificial Neural Networks: The State of the Art, International Journal of Forecasting, pp. 35-62, 1998.


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[17] P. Cabena, P. Hadjinian, R. Stadler, J. Verhees, and A. Zanasi, Discovering Data Mining From Concept to Implementation, Englewood Cliffs: Prentice Hall, 1998. [18] S.A. Hamid, and Z. Iqbal, Using Neural Networks For Forcasting Volatility of S&P 500 Index Future Price, Journal of Business Research,vol.75:pp.1116-1125,2004. [19] S. Rajasekaran and G.A. Vijayalakshmi Pai, Neural Networks, Fuzzy Logic, and Genetic Algorithms: Synthesis and Applications (PHI Learning Private Limited, 2008)

Authors’ information Husin N. Azura is a Doctor of Philosophy student in Department of Computer Science at Universiti Putra Malaysia. Her study in Doctor of Philosophy focused on Intelligent Computing. Nor Azura Husin has received Bachelor of Computer Science in Computer Network from Universiti Putra Malaysia (2004) and Master degree in Computer Networking from Universiti Teknologi Malaysia (2008). She currently worked as a tutor at Department of Computer Science, Faculty of Computer Science and Information Technology (UPM). Her research interests are in neural network and intelligent computing. Mustapha N. is a lecturer at the Department of Computer Science, Faculty of Computer Science and Information Technology, Universiti Putra Malaysia, Malaysia. Associate Professor Dr. Norwati Mustapha received her Ph.D from Universiti Putra Malaysia in 2005 and Master degree in Information System from University of Leeds U.K. (1995). Her research interests are in data mining (artificial intelligence), web mining, text mining and video mining. Sulaiman M. Nasir is a lecturer at the Department of Computer Science, Faculty of Computer Science and Information Technology, Universiti Putra Malaysia, Malaysia. Associate Professor Dr. Md. Nasir Sulaiman has received her Ph.D in Computer Science from Loughborough University of Technology, U.K. (1994) and Master degree in Computing from University of Bradford U.K. (1985). His main research interests are in the fields of intelligent computing, intelligent software agent and data mining.



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Design of Navigation Map Model for Intelligent Vehicle Combined with the Traffic Sign Recognition Ying Xia1, Sutong Liu2, Jiangfan Feng2 Abstract – Map data modeling is one of the key technologies of positioning and navigation. Hierarchical map data structure which is integrated with traffic sign information is designed based on the navigation geographic data model for autonomous navigation of the intelligent vehicle. The application example shows that the model can express road network topology subtly, and establish the association between the road network and traffic rules easily. It can not only provide static path planning by analyzing the road network structure, but also combine with the traffic sign recognition technologies to assist the intelligent vehicle to achieve dynamic navigation. Copyright © 2013 Praise Worthy Prize S.r.l. - All rights reserved.

Keywords: Intelligent Vehicle, Traffic Sign Recognition, Navigation Map Model

information [3]. But during the process of visual navigation information fusion, it may be influenced by the sensor error, inertial device error and environmental interference, etc. [4]. This paper consider that predefining navigation map model, selecting the related features for intelligent vehicles navigation, analyzing the topological relations and logical organizational structure, and integrating the semantic rule which acquired from the traffic signs. Through the map model, the traffic sign information can be refined to the lane. By analyzing of network topology and resolving traffic signs information, can not only provide the static path planning, but also assist the intelligent vehicle to achieve real-time path updating by combining with the traffic signs recognition technology.

Nomenclature GDF

An interchange file format for geographic data KIWI A data format for navigation data storage SDAL An industry standard for digital navigation maps DARPA Defense Advanced Research Projects Agency ; an agency of the United States Department of Defense responsible for the development of new technologies for use by the military Visual An ability to interpret the surrounding perception environment by CCD camera and so on TSR Traffic sign recognition Geographic An entity of the geographic map feature

II. I.

Related Work

In the aspect of geospatial data model, there are a few kinds of main navigation data standards/formats, such as GDF, KIWI and SDAL [5]. Europe has released the GDF standard [6] which defines the navigation map data conceptual model by using feature model, attribute model and relationship model. It mainly describes the frame information about road network, on which there are social information and traffic facilities such as traffic signs and traffic lights. It consists of point, line and plane. The KIWI format researched by Japanese organizes the map according to the hierarchy structure, and combines the map data with navigation data closely. KIWI can provide different levels of abstract data for specific application purpose. The U.S. launched the SDAL format including detailed road, road appurtenances, traffic information, etc [7]. In the aspect of intelligent vehicle navigation map, according to the Route Network Definition File (RNDF) used by the unmanned vehicle

Introduction

Intelligent vehicle is an integrated system fusion of computer, sensor, machine vision and automatic control technologies [1], by using equipment such as the positioning, sensors, camera to perceive the traffic information and is an advanced solution for modern urban transport. Navigation map is the basis for intelligent vehicle path planning [2]. Its data acquisition and organization model directly affect the navigation quality. Now, there are already some intelligent vehicles, such as the VaMoRs and VaMP in IDF University of Munich, Germany, the Navlab in University of Carnegie-Mellon, USA and the ARGO in the University of Parma, Italy. These intelligent vehicles can support visual navigation which is a process the real-time detection the information of roads and roads facilities by using the visual perception technique, and build the map model by perceptive information such as position, sensor, and visual perception Manuscript received and revised February 2013, accepted March 2013


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Ying Xia, Sutong Liu, Jiangfan Feng

competition held by DARPA, we define the endpoint of lane and part of the shape points on the area boundary as the entry points or exit points respectively, then the correspondence relationship of each points constitute the road network structure [8]. The competition held by the Chinese National Natural Science Foundation also uses the route network definition file similar to RNDF. Zhang et al. [9] first projected the images shot by car camera onto the body coordinate system, then used the driving track and watershed algorithm to distinguish traffic areas, and finally combined with sectional bird's-eye view of the map to optimize and obtain the navigation map. Google driverless car [10] based on the Google Street View which provides geographical environment and the electronic map, by road network topological data as constraint conditions, and combined with the map storage and predictable data (e.g., road signs and markings, intersection traffic lights, and traffic signs), and dynamic traffic information to achieve navigation. If building the navigation map using traditional spatial data model, the complex features and large amount of data will difficultly achieve real-time processing for embedded vehicle navigation system. Aiming the hardware and software environment of the intelligent vehicle and considering the weakness of the visual navigation resistance to environmental interference, this paper design the suitable map model of autonomous navigation for intelligent vehicle. This model must be able both to meet the real-time intelligent vehicle path planning, and to precisely match the driving environment and discovery traffic restriction rules in the environment for the intelligent vehicle. This paper simplified map features based on the standard navigation data model GDF, and by the method of increasing thematic level to describe the location of traffic signs and semantic information. Finally, we realized the real-time path planning assisted by maps for intelligent vehicle.

Navigation map features describe the information such as road information, position and semantic information of road traffic signs in the intelligent vehicle driving environment. When navigation service start, the intelligent vehicle get its current position by the positioning technologies such as GPS, and according to the moving direction confirm which lane the vehicle drive on, then establish the correlation with traffic sign information and analyze the sign position and rules to work out the reference path to a target position. With assisted by the navigation map, when the vehicle drive to approach the region of traffic signs, the visual perception function of traffic sign recognition is started [12]. And it checks the consistency the recognition result with the traffic signs information in navigation map. If it finds inconsistency, a new path will be planed.

Fig. 1. The real-time path planning strategy combined with the traffic sign recognition

IV.

Intelligent Vehicle Navigation Map Conceptual Model

IV.1. Elements and their Hierarchical Expression According to the common data model and exchange standards - GDF, the real world objects are represented by features grouped together into different feature themes including the theme of Roads and Ferries, Administrative Areas, Railways, Waterways, Roads Furniture and so on. Geographic features classify according to the hierarchy, the classification of a certain feature can be defined as a subclass of the classification of upper Level. The various features are defined in the geographic data file conceptually divided into three levels named as Level-0, Level-1 and Level-2. The simple features belong to the Level-1 and the complex features belong to the Level-2. In Level-0 the basic graphical building blocks are defined, these basic building blocks are zero-dimensional nodes, one-dimensional edge and 2-dimensional surface or points, polylines and polygons. The point features at Level-1 are the Junction, and the line features including Road Elements, Address Area Boundary Element, Ferry Connection etc., the plane features of Enclosed Traffic Area and Address Area. The complex features include Road, Intersection and Overpass Across. The distinction between simple features and complex features is the simple features are defined by the basic building blocks stored at Level-0 but the complex features are defined by simple features or other complex features. The hierarchical topology model of features is showed in Fig. 2.

III. The Real-Time Path Planning Strategy Combined with the Traffic Sign Recognition Navigation map can provide static information of road network structure. These static information are showed by the definition of map features and the organization of data in navigation map model, which can provide the static path planning for vehicle. Considering the intelligent vehicles need the real-time perception of traffic signs, traffic lights and other traffic dynamic information, so we design the real-time path planning strategy combined with the traffic sign recognition [11]. The strategy can offer the real-time path planning for intelligent vehicles on the base of the static road network structure information provided by navigation map, combining with the perception of dynamic traffic information. The real-time path planning strategy combined with traffic sign recognition is showed as Fig. 1. Copyright © 2013 Praise Worthy Prize S.r.l. - All rights reserved


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Junctions, it may be represented at Level 2 by one single Intersection. The Overpass Across the road network including the bridge, viaduct, flyovers, underpasses, etc, where there are no common connection point of the road element. If there is a connection point, it either links the road element of next layer or previous layer, but not links both two at the same time. (2) Road Furniture is item which are categorized by having a fixed location along a Road Element, either on the carriageway or the pavement. Examples include features such as Traffic Lights, Traffic Signs, Pavement markings and crosswalk. However the Road Furniture usually stored as the attributes of the Road and Intersection at Level 2.

Fig. 2. The hierarchical topology expression of features

IV.2. Selection of the Features According to the classification of the feature themes, the intelligent vehicle navigation system has a need of describing precisely the road network topology and traffic rules based on the lane. In accordance with the scene of intelligent car driving and the themes it concerned, this paper selects the two feature themes of Road and Ferries and the Road Furniture in order to reduce the burden of data storage and computational. The various features are given in the Fig. 3.

IV.3. Navigation Map Conceptual Model Intelligent vehicle can control vehicles moving through the traffic sign recognition. Combining the navigation map and the traffic sign recognition can offer the assist from map when the traffic signs are difficult to detect or can’t be detected. The corresponding traffic signs on each lane may be different, thus the modeling requirements of the road data are also higher. Malairisanachalee et al. [13] proposed a representative of the road data model, and express the lane which is an attribute of road before as an independent feature. The position of the lane is confirmed by using linear reference method according to the road. This paper refer to the road data model of Malairisanachalee et al. proposed, and express the traffic signs which are attributes of road or intersection as an independent feature though the theme level, meanwhile describe the attribute of the traffic signs and the affiliation with the lane. In accordance with the classical Node-Arc model we describe the features of all levels as the following: (1) The feature of Level-0: Link Road, Lane, Guide point, traffic sign point and their conceptual model (as Fig. 4). The link road servers as arc feature having a direction attribute and smallest unit of Level-0, having a guide point at each end. Guide point servers as node feature of Level-0 and endpoint of the link road and represents physical connection relationship between the two link roads. The lane servers as the feature can be used to analysis the road network and be ensured according to the link road with linear reference method. The link road represents the lanes having same direction and each lane relates only one link road. The lane servers as the independent feature having attributes and relationships of its own, such as position, width, traffic state of lanes, and the relationship between right and left lanes. The traffic sign point server as node feature of Level-0 and reference traffic rule, refer to the guide point having attributes and relationships of its own, such as which lane it belongs to, the latitude and longitude, the type, the name of it. The relationships of traffic sign point include the corresponding relationship with the lane.

Fig. 3. The various features of intelligent vehicle navigation map model

(1) In the theme of Road and Ferries, according to the application requirement, Level 1 describes the simple features such as Road Element, Junction, and Enclosed Traffic Area, whereas Level 2 describes the complex features Road, Intersection, and Overpass Across. The Road Element is a linear section of the earth which is designed for or the result of vehicular movement. It serves as the smallest unit of the road network at Level 1 that is independent and having a Junction at each end. The Junction is a feature that bounds a Road Element. The Enclosed Traffic Area is any confined area within which unstructured traffic movements are allowed. Road is a Level 2 feature composed of one, many or no Road Elements and joining two Intersections. It serves as the smallest independent unit of a road network at Level 2. Intersection is a complex feature composed of one or more Level 1 Junctions, Road Elements and Enclosed Traffic Areas. At Level 2, the feature Intersection plays the same role as the feature Junction does as Level 1. The different between an Intersection and a Junction lies in the degree of generalization; where a multi-element crossing will be described at Level 1 by many Road Elements and



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Fig. 4. E-R diagram Level-0 conceptual model

(2) The features of Level-1: Junction, Road Element and their conceptual model (as Fig. 5). The junction which is node feature of Level-1 includes three types. One is the connection point of two or more road elements. One is the intersection between one or more road elements with a closed traffic area or the outer contour of address region.The other one is the end point of road elements. Road element which is the feature of the arc feature of Level-1 has its direction. It includes two types. One is having the first junction as the end points at least; the other one is having the second junction as end points and representing a flyover crossing in road network. (3) The features of Level-2: Intersection, Road, Overpass Across and their conceptual model (as Fig. 6). The intersection servers as the node feature of Level-2 which is the abstract of the junction and road element of Level-1. The road servers as the arc feature of Level-2 which has its direction. It is the smallest unit in Level-2 road network, having a intersection at each end. Overpass Across which is a complex feature at Level-2 is expressed by the road at Level-2 and the start and end junction at Level-1. Feature in model at different Levels are contacted by the corresponding relationship between each other. The Level-2 in the model which is the abstract of Level-1 can already offer people intuitive expression of road network. And road network is most closely described the physical road network by feature of Level-1. The feature of Level-0 express subtly the feature of Level-1, and it can provide map service based on the lane in the intelligent vehicle navigation process.


V.

Application Example

By using the AutoCAD and ArcGIS platform, we apply the map model designed by this paper to the runway environment (as in Fig. 7) of the miniature intelligent vehicle to establish a hierarchical map model of the simulative scene. We mainly describe the basic structural level Level-0. As shown in Fig. 8, the linear elements described in the figure are lanes, the point between the lines described the guide point, and the small white circle described traffic signs.

Fig. 7. Miniature intelligent vehicle simulative runway


Fig. 8. Structural level-0 diagram of simulative runway



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According to the features and their attributes, we design the logical data model of the features as the following.

Name LRID LRType FNodeID TNodeID LaneIDs

Name NodeID NodeType NodeX NodeY

is proved that the best time to start the traffic signs recognition when vehicle arrive at point C and point D and the two points are the suitable position for recognition. The travel route changed from point A to point B when the traffic signs changed on the lane. Through the experiment, it is proved the effectiveness that the map combined with traffic sign recognition can offer the aid of dynamic path planning by using the position information of the traffic signs in the map.

TABLE I LINK ROAD TABLE Description ID of Link Road Type of Link Road ID of start guide point ID of end guide point IDs of Lane included by a Link Road

Type Int Int Int Int Text

TABLE II GUIDE POINT TABLE Type Description Int ID of Guide Point Int Type of Guide Point Int The X coordinate of Guide Point Int The Y coordinate of Guide Point TABLE III LANE TABLE

Name LaneID LaneNo Width NextLaneID NextLRID LLaneID RLaneID NotPass

Name RSID RSType RSName RSX RSY LaneID

Type Int Int Double Text Int Int Int Text

Type Int Int Text Int Int Int

Description ID of Lane Number of Lanes Width of the Lane The ID of the next lane related The Link Road connected by the lanes ID of the left Lane ID of the right Lane IDs of the Left and right Lane can’t pass

Fig. 9. The path planned when having no traffic signs

TABLE IV TRAFFIC SIGN TABLE Description ID of the traffic signs Type of the traffic signs Name of the traffic signs The X coordinate of the Traffic sign The Y coordinate of the Traffic sign ID of the Lane which traffic sign related

Miniature intelligent vehicles running in the simulated runway can be provided the navigation based on the lane by this map. The Intelligent car in the process of moving find path by the map matching. This method improves the accuracy of real-time road lane recognition. In this way the intelligent vehicle seeks the location of the neighboring traffic signs, and estimates the distance to start the traffic signs system timely. It is in favor of intelligent vehicle making judgments in advance with the aid of map, when the vehicle can’t recognize or difficult recognize the traffic signs, so as to void breaking the traffic rules on the road. In simulation experiment shown as Fig. 9, from point A to point B, there are no traffic signs on the lane and the shortest path (as the dotted line in Fig. 9) has been planned according to the path of the vehicle driving on and the direction of the lane. When add new traffic signs into the runway, the vehicle recognize them by camera and combine the map to obtain a new path planning in the Map, because the added traffic signs express the turn restrictions. The new path is showed as the dotted line in Fig. 10. It


Fig. 10. The path planned when added into traffic signs

VI.

Conclusion

The intelligent vehicle can get real-time traffic information by perception technology such as the location and visual, but in complex traffic environment, relying solely on environmental perception, not only requires a lot of calculation but also cannot meet the needs of the overall path planning. This paper presents the layered map model to combine the road network topology and traffic rules. This method can not only provide static path planning through the analysis of the road network structure, but also assist intelligent vehicle to perform dynamic navigation with the


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supporting of traffic sign recognition technology.


Department of computer science and technology, Chongqing University of Posts and Telecommunications, Chongqing 400065, P. R. China.

Acknowledgements This work was financially supported by the Natural Science Foundation Project of Chongqing CSTC (cstc2012jjA40014); The Doctoral Startup Foundation of Chongqing University of Posts and Telecommunications (A2012-34).

2

Department of computer application technology, Chongqing University of Posts and Telecommunications, Chongqing 400065, P. R. China. Dr. Ying Xia received the Ph.D degree in computer science and technology from the Southwest Jiaotong University, China, in 2012. Currently, she is a professor at Chongqing University of Posts and Telecommunications, China. Her research interests include spatial database, GIS, and Cross-media retrieval.

References [1]

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Congmin Bai, Autonomous Navigation Technique of Intelligent Vehicle in Regional Traffic Environment, Ph.D. Thesis, University of Shanghai Jiao Tong, Shanghai, China, 2010. Dongbo Liu, Guorong Liu, Peixin Qu, Based on Particle Swarm Optimization Mobile Robot FastSLAM Method, (2012) International Review on Computers and Software (IRECOS), 7 (1), pp. 53-59. Zheng Li, Hanqing Zhao, Daxue Liu, Hangen He, Real-Time Vehicle Detection Based on Active Vision, Computer Simulation, Vol. 26 n. 5, 2009, pp. 286-290. Haitao Liu, Shengxiao Guan, Liang Qin, et al, Study on vision-based navigation system of intelligent-Robot, Computer Applications and Software, Vol. 27 n. 12, 2010, pp. 218-220. Qingquan Li, Jinghai Xu, Nianbo Zheng, et al, Function based navigation data model, Geomatics and Information Science of Wuhan University, Vol. 32 n. 3, 2007, pp. 266-270. ISO/TC204/WG3, Intenlligent Transportation Systems Geographic Data Files (GDF) - Overall Data Specification ISO, IS014825, ISO. 200. Qingquan Li, Jinghai Xu, Mingfeng Li, Progress and trend of research on navigable digital map data mode, Journal of Geomatics, Vol. 32 n. 6, 2007, pp. 22-25. Defense Advanced Research Projects Agency, Route network definition file (RNDF) and mission data file (MDF) formats, December 2006. Xiaobo Zhang, Bin Dai, Daxue Liu, Qingyang Chen, Auto-mapping approach of autonomous land vehicle in off road environment, Application Research of Computers, Vol. 28 n. 3, 2011, pp. 984-987. B. Douillard, D. Fox, F. Ramos, H. Durrant-Whyte, Classification and Semantic Mapping of Urban Environments, International Journal of Robotics Research, Vol. 30 n. 1, 2011, pp. 5-32. Lu Lou, Xin Xu, Fast and Robust Traffic Sign Detection and Recognition Using Visual Features, (2012) International Review on Computers and Software (IRECOS), 7 (2), pp. 744-748. Hechri, A, Mtibaa, A, Automatic detection and recognition of road sign for driver assistance system, Proceedings of the Electro-technical Conference (MELECON) (Page: 888-891, Year of Publication: March 25-28, 2012 ISBN: 978-1-4673-0782-6). Malaikrisanachalee S., Adams T. M., Lane-based Network for Transportation Network Flow Analysis and Inventory, Proceedings of TRB 2005 Annual Meeting CD-ROM．

Sutong Liu received the bachelor degree in electronic information engineering from Chongqing University of Posts and Telecommunications, in 2010. Currently, she is studying for the master degree at Chongqing University of Posts and Telecommunications. The major of her is computer application technology. Dr. Jiangfan Feng received his M.S. degree from Southwest Agricultural University, and his Ph.D. degree from Nanjing Normal University, in 2002 and 2007. He works as associate professor of Chongqing University of Posts and Telecommunications. His main research areas include spatial information integration and multimedia geographical information system.



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Systematic Literature Review on Search Based Software Testing Abu Bakar Md. Sultan, Samaila Musa, Salmi Baharom Abstract – The use of random search is very poor at finding solutions when those solutions occupy a very small part of the overall search space. Test data may be found faster and more reliably if the search is given some guidance. This work is a paper that explains the application of metaheuristic techniques in search-based software testing. The paper systematically review 47 papers selected randomly from online databases and conference proceeding based on the metaheuristic search techniques that have been most widely applied to problem solving, the different fitness function used for test data selection in each of the metaheuristic technique, and the limitation in the use of each search-based technique for software testing. It was found that GA outperformed its counterparts SA, HC, GP and random search approaches in generating test data automatically, different approaches were used to make sure that test data are selected within shorter period of time and also with wider coverage of the paths based on the fitness function, and most of the limitations of the articles are the handling of complex data types, like array, object types, and branch coverage. The paper also provides areas of possible future work on the use of metaheuristic techniques in search-based software testing. Copyright © 2013 Praise Worthy Prize S.r.l. - All rights reserved.

Keywords: Metaheuristic Techniques, Search-Based Software Testing, Software Testing, Systematic Literature Review

The correctness of the software need to be tested before handed over to the user [1]-[52]. The correctness does not refer to the user’s specifications, but user’s requirements. Sometimes the user’s specifications may be incorrect. Meeting the user’s requirements is what makes the software to be correct. The term testing is associated with verification and validation. Some problems in software testing can be handled using random search in finding solutions to them. They are called combinatorial problem. Many problems have so many possible combinations that make it impossible to solve them using random search. Developers can use combinatorial test design to identify the minimum number of testing to get the coverage needed. Users used combinatorial design to achieve wider coverage of many paths in fewer tests, and at a shorter execution time. Testing performed in order to guarantee that newly introduced changes in software do not affect the unchanged parts of it is referred to as regression testing. In regression testing, the tester simply executes all of the existing test cases to ensure that the new changes are harmless and is referred as retest-all method [30]. To ensure complete coverage of paths and maximum error detection, unit testing exercise specific path in a module’s control structure [1]. Components are integrated to form the complete software.

The issues related to the dual problems of verification and program construction are addressed by integration testing [1], using black-box test case design techniques in order to ensure coverage of major control paths with the limited amount of white-box testing. After construction of software, there is need of set of high-order tests to be conducted. In order to be assured that software meets all functional, behavioral, and performance requirements, validation testing is conducted using black-box testing techniques exclusively [1]. The simplest form of an optimization algorithm, and the easiest to implement, is random search. In test data generation, inputs are generated at random until the goal of the test (for example, the coverage of a particular program statement or branch) is fulfilled. Random search is very poor at finding solutions when those solutions occupy a very small part of the overall search space. Test data may be found faster and more reliably if the search is given some guidance. The application of search-based optimization to software engineering is refer to as search-based software engineering (SBSE) [8]. Considering the size and complexity of testing for software, there is need for the use of metaheuristic search techniques to conduct the test [5]. They also outlined many areas of search-based software testing application in test case generation; white-box (structural), black-box (functional) and grey-box (combination of structural and functional) testing [5]. According to [8], a fitness function is a guide for determining the best test case between two solutions in



I.

Introduction

132

Abu Bakar Md. Sultan, Samaila Musa, Salmi Baharom

search-based optimization, and generation of test data automatically or partially automatically in software testing using metahueristic search techniques is refers to as search-based software testing. Comparing the cost of manual testing, research into software testing automation is of concern. The area of search-based software testing research is reaching a high level of maturity, therefore there is need to conduct systematic literature review. This paper reviews journal articles on search-based software testing with the aims of suggesting possible future research on software testing using metahueristic techniques. This review differs from the review conducted [5] based on the following: - Wider coverage: The previous review [5] was based on application of metaheuristic search techniques to test non-functional properties of software, while this review is based on the application of metaheuristic search techniques to test the software/programs. - Studies grouping: This research grouped the journal papers of search-based software testing based on metaheuristic search techniques, test data generation and selection, and limitation of search-based techniques, other than that with respect to nonfunctional properties in the previous review. The remaining part of this paper is organized as follows: section 2 describes the review process/method. In Section 3 results were presented. Section 4 discusses the result and recommendation for future research in software testing using metaheuristic techniques. Conclusion is presented in section 5.

II.

climbing, and genetic programming to test different software. The outcome is the different software testing that used search-based techniques. Effect is the results expected in the end of the review; best methods of generating and selecting test case and improvement in testing software. II.2.

Identification of Research

The selection of sources for the review execution is based on the following: i. Sources Searching Methods used was searching electronic databases and search through web search engines to search for journals and conference proceedings. 2007 was selected as starting year for the review; this is because to reduce the duplications of sources used the same problem statement and method. The search was conducted on the following databases: ScienceDirect IEEE and ACM ii. The Search Strings used are search-based techniques, metaheuristic search techniques, software testing, test data, test cases, fitness function, test data generation, test data selection, automated testing, automating testing, evolutionary, optimization, hill-climbing, simulated annealing, tabu search, genetic algorithms and genetic programming. Boolean AND and OR are used to join the search words. iii. The review was conducted on 47 articles from journals and conference proceedings; the breakdowns are32 journal articles, 12 conference proceedings articles and 3manually searched articles as shown in the Fig. 1. The percentages for the journal papers are 68%; i.e. ACM digital library and ScienceDirect, 26% for the conference proceeding papers, and 6% for manually search articles.

Method

A systematic review is a method of assessing and synthesing all relevant research articles that are related to the research question [3], [23]. The development of the protocol for the review was by the guidelines, procedures, and policies by [3].

II.3. II.1.

Research Question

Study Selection

This described the process and the criteria for the selection and evaluation of the studies. Studies Inclusion and Exclusion criteria: the application of metaheuristic search techniques in planning to execution of application was found in different phases of software testing [5]. There is need to present inclusion and exclusion criteria by which studies will be evaluated to decide if they must be selected or not in context of the review. The definition of these criteria is important because the results of web search engines will be higher number of articles not related to the answer of the research questions. The exclusion criteria are: any study that a. Is not relating to software testing. b. Is not reporting the application of metaheuristicsor evolutionary search techniques. c. Is not related to software development. d. Is related to the testing of planning phase.

The objective of the review is to answer the following questions: 1. Assessing the effect of search-based techniques in software testing The following sub-questions are considered: 1.1 Which of the metaheuristic search techniques have been most widely applied to problem solving in software testing. 1.2 What is the different fitness function used for test data selection in each of the metaheuristic technique for testing the software. 1.3 Determining the limitation in the use of each search-based technique for software testing. The population is the software/programs under test; representing the group that will be observed by the intervention. Intervention is what is going to be observed; application of metaheuristic techniques Genetic algorithm, simulated annealing, tabu search, hill



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Fig. 1. No of articles Based on their Source

The procedure for studies selection are reading the article abstract and reading the full text. Some journal articles were excluded from their titles; web search engines displayed results of thousands based on a search key. II.4.

assessment. Most of them addressed the issue of software testing using metahuerestic techniques. The list is shown below in Table I.

Id S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 S16 S17 S18 S19 S20 S21 S22 S23 S24 S25 S26 S27 S28 S29 S30 S31 S32 S33 S34 S35 S36 S37 S38 S39 S40 S41 S42 S43 S44 S45 S46 S47

Study Quality Assessment

There is need for the assessment of the primary studies quality to improve the inclusion/exclusion criteria, also to check between study results and guide the researcher in data analysis and possible future work recommendations [3]. The lists of the developed criterion based on guidelines by [3] are: i. Does the author state clearly the aims of the research. ii. Are the statistical methods described. iii. Does the results answered the study questions. iv. Does the result differ from the previous researches. v. Is the result useful to the increase in software testing efficiency. vi. Does the aims and objective clearly defined in the conclusion of the research. II.5.

Study Data Collection

In order to address the review questions and syntheses the data, a data collection form was designed to collect information needed. The information to be extracted are: title, authors, journal and details of the publication; problem statement, proposed solution, study methodology, study results, limitations/benefits and possible future work.

III. Data Synthesis The descriptive evaluations of the assessed papers under review were presented in this section in relation to the research questions. The publication years of papers used are from 2007 to 2012. III.1. Search Results Table I presents the result of the search obtained after the search procedure. There are 47 studies identified based on the study selection and Study quality Copyright © 2013 Praise Worthy Prize S.r.l. - All rights reserved

TABLE I SEARCH RESULTS Authors L. Kiran, H. Mark, G. Hamilton[9] R. S. Praveen, K. Tai-hoon[10] H. Mark[11] A. Nadia, H. Mark[12] S. Ramon, Y. Xin[13] L. Andreas et al [17] B. Oliver, W. Joachim[18] L. Raluca, I. Florentin[19] X. Jifeng, et al[2] Z. Yuan, C. John A.[4] L. Jailton, et al.[6] M. Phil[7] A. A. Moataz, H. Irman[20] S. Liu, Z. Wang[21] J. Yue, H. Mark[22] M. Brototi, et al.[52] A. Andrea[24] H. Mark, et al [14] A. S. Anastasis, S. A. Andreas[15] L.Raluca, I. Florentin[16] J. Tao, et al.[25] P. Mike, M. Nicos[26] A. Enrique, C. Francisco[27] A. Wasif and T. Richard[28] A. Giuliano[34] A. Andrea, Y. Xin[35] M. Phil, S. Muzammil, S. Mark[36] A. Andrea[29] Y. Shin, H. Mark[30] G. Vahid[31] M. Phil[32] M. Phil[33] F. Gordon, A. Andrea[37] J. A. Clark, et al.[38] C. B. R. José et al [39] G. Kamran, A. C. John[42] P. Manisha, P.J.Nikumbh[43] G. Dunei, Z. Wanqui, Y. Xiangjuan[40] M. P. Reza et al [46] S. Alin et al [41] T. Jose, R. Eduardo[44] P.M.S. Bueno et al.[45] D. Eugenia, et al. [48] F. Nilgun, M. K. Mieczyslaw[49] A. W. II, Robert, J. C. Charles[50] A. Bouchachia et al.[47] M. Caserta, A. M. Uribe[51]

Year 2012 2009 2007 2011 2008 2007 2008 2008 2007 2008 2012 2012 2008 2011 2009 2012 2010 2008 2008 2008 2008 2012 2008 2011 2009 2008 2012 2008 2007 2008 2011 2009 2012 2011 2009 2009 2012 2011 2011 2011 2012 2011 2008 2011 2009 2010 2009


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Fig. 2 shows the result that plots publication year ranges on the y-axis and number of papers published within those years on the x-axis. The following subsection will address a research question in each.

well for large number variables and complex input domains. Some of the techniques that have guide in finding more reliable test data are Genetic algorithm, simulated annealing, tabu search, hill climbing, and genetic programming. If the author used Genetic algorithm or build his technique based on Genetic algorithm, the technique of that paper is marked as Genetic Algorithm. Also the same applied for the other techniques. Thirty articles are choosing out of 47 articles, and were presented in Fig. 3, based on the metaheuristic search technique applied by the authors. The diagram shows that GA was used in 67% of the papers under review; this is because GA can be used to generate test data for functional testing [19] after representing the specification into state diagrams or control flow graph [15]. A GA-based test data generator was used for multiple target paths coverage [13] in white-box testing for automating of test data generation [20], [15], and it was able to cover branches [13] within a shorter time. In [48] the test data was generated for structural software testing using tabu search techniques (TS). In [40], the many paths coverage was based on grouping of the target paths. It can also be used to build a framework that increases the significantly better performance [15], [13] by integrating program analysis features.

Q3.1 Which of the metaheuristic search techniques have been most widely applied to problem solving in software testing. The metaheuristic techniques used in software testing are presented in Fig. 3, based on their number of used by the authors of the reviewed papers. The simplest form of an optimization algorithm, and the easiest to implement, is random search. In test data generation, inputs are generated at random until the goal of the test (for example, the coverage of a particular program statement or branch) is fulfilled. Random search is very poor at finding solutions when those solutions occupy a very small part of the overall search space. Test data may be found faster and more reliably if the search is given some guidance. The choice of using GA over other techniques can be as result to the nature of search mechanism used by GA. The possible solutions of a problem are presented as a population by GA, finding global optimum is far better in GA than SA which used one solution at a time. GA are prepared by most of the authors because they perform

NO OF ARTICLES 2011-2012

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Fig. 2. No of articles based on years of publications

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Fig. 3. No of articles Based On The Metaheuristic Technique Used



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In GA, parameters can be adjusted in mutation [22], [26], [4] called high order mutation and crossover to have higher coverage of paths [27] which increased the possibilities of testing the most error prone paths [10], [26]. The paths weight can be measured based on their criticality [10] in order to optimize and select them which improve the efficiency of software testing compared to exhaustive search and local search techniques. With GA, fewer test cases can be used for testing [14] without losing the coverage, but only applied to smaller code. GA can be used to compare the results between the pseudooracle and its original code [33], the differences between the outputs indicate a fault in the original program. The differences between the two allow for the generation of test cases indicating where the faults are highly pronounced. Problems of redundant test data and some paths uncovered can be reduced [21] to increase test fully and efficiently using GA, test data are generated automatically to achieve path-oriented testing. GA can be applied after grouping the target paths [7] based on their similarities and each group form a sub-optimization problem [40] which reduce the execution time and improve in uncovered target paths. The issue of automatic generation of test data for structural coverage of a program was addressed using GA with and without crossover by evaluating program factor [7]. The results indicate that the use of crossover outperformed the other. McMinn et al (2012) address the issue of realistic and branch coverage for string inputs from the Internet by transforming program identifiers into web queries then applied GA to test the java classes. The result shows that there is improvement in coverage of the java classes. Test data can be generated automatically for structural software [4] using novel tabu search (TS) metaheuristic algorithm [48], but [4] used simulated annealing (SA) and it was successful. The algorithm has two approaches; one for intensifying the search and the other for diversifying the search when the intensification did not work [48], the test data was applied to cover wider area of complex program. [12] presented an approach that can be applied in web application testing, which increases the efficiency and effectiveness in test data generation based on HC that maximize the coverage and reduce the execution time for static and dynamic analysis with the aid of a tool, called SWAT. In [9], a search-based testing tool called AUSTIN was presented that works with random search and hill climber (HC) which generated test data that has higher branch coverage for C functions from open source program. This means that metaheuristic techniques can be applied for structural software testing, which deals directly with the program code in order to generate test data automatically. Also in functional software testing, where the testing is based on the specification of the user, test data are also generated automatically using metaheuristic techniques.

Q3.2 What is the different fitness function used for test data selection in each of the metaheuristic technique for testing the software. This is one of the concepts of metaheuristic techniques, as the main factor in how well a program is able to solve the problem. The selection of test data to be used in testing software in search-based optimization is through it fitness value. The value of individual is used as bases for selection of parents to be used for reproduction; this means that selection of individuals for crossover operation is based on the fitness value of each. Most of the authors designed the fitness function based on the structural properties of individuals. Test data selection in search-based optimization is through fitness function. In [7], the author stated that, the computation of fitness value is by normalizing the branch distance and adding it to the approach level. In metaheuristic search techniques like GA, the selection of test data in based on modeling the testing objective as fitness function that is to be optimized to find the desired test data [20]. The presence of infeasible paths, the length of the path and the compound predicates complexity does not prevent the candidate fitness function presented by [20] to be effective and efficient in handling the required feasible target paths. This means that the presence of infeasible paths does not stop the test data generator to locate all the possible target paths. Individual’s fitness values are used as bases for selection of parents for reproduction [10]; weights are assigned to each path, to be used in calculation of fitness values. Those paths with loop and branch nodes were given more weight than the sequential nodes in testing the software. The Batch-Optimistic GA proposed by [15] (BO-GA) uses the edge/condition fitness function to evaluate each chromosome with respect to the edge/condition coverage criterion effectively. The second algorithm presented by [15] focuses on edges or conditions not covered by the BO-GA, i.e., Close-Up (CU) algorithm. CU algorithm uses the control flow graph to present target paths. This algorithm encodes genes as parameter inputs and chromosomes as test case. Fitness function (or Cost function) can be used to know how better a solution is in relation to achieving the search goal [11], [48]. The good working of test generator correctly is determined by good fitness function [31]. The fitness function described by [48] is used to intensify the search and is calculated by means of the cost function called f (x) and diversify the search [45] is calculated by means of the cost function called fp (x) (parent cost). The fitness function used by [11] in their approach is; for a predicate a op b, the fitness is zero when the expression is true, when the value is false, the fitness is absolute value of a-b. Compound predicates involving logical operators are represented using a pretransformation into simplify relational predicates [12], [13]. Fitness function can be based on branch-distance which can be used to measure the objective function for branch coverage [13].



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The fitness function for test data generation can be defined based on the collateral coverage of branches [14], [24], [35], and length of the sequence [35], in [14] the authors separated the fitness function into primary fitness and secondary fitness. Fitness function of test data can be based on arithmetic, logical and relational operators of the mutant killed [6], it can also be measured based on the fragility of the mutant [22]. The different between the transformed pseudo-oracle class and original program in output was used to determine the fitness function of a class in OO [33].In [27] the fitness function is calculated based on arctan of distance value of the real numbers, it can also be based on evaluating branch predicates [42]. Weights were assigned by [25] based on the coverage and overlap in term of the specific need, the fitness function captures the decomposition of the program that maximizes coverage while minimizing overlap. To find solution to the given path, fitness function was designed based on the approach level and branch level [16], [19], [24], [36], has similar matric in evolutionary structural test data generation. The formulation of fitness function was done based on linear optimization problem in [34], in order to avoid manual generation of test data. Fitness value can be based on the distance yet to be covered [47], the selection is based on proportional selection and ranking selection, or based on formal specification determined by the number of unit test pass [29]. In simulated annealing, the fitness function was defined based on the difference between two test data, and also counting the number of different pairs [43]. In [39] the fitness function has two approaches; the feasible test cases which is based on trace information and unfeasible test cases which is based on distance and method call sequence length.

that it is the best approach for automating the test data generation in structural testing. In seeding the initial populations of test data generated, the method used has effect only at the initial stage of the process, it become low in the later stage [37], this means with large or complex problem, the results will not show any impact. Some tools were not able to execute the mutant codes due to the changes during mutation, as in [6].The issue of redundancy in [25] where the slices does not contribute to the fitness function value and it will affect the execution time because of the redundant slices.

IV.

Discussion and Future Work

The use of metaheuristic search techniques for testing software is getting more popularities and interest. Considering the number of articles from 2007 to 2012 based on few research questions, there is really improvement in the area. The researchers are going away from traditional approach of testing software to field of search-based software testing. Looking at the number of journal articles published by researchers, as shown in Fig. 1, making up to 68% of the total articles under review, there is really improvement in the publications. Published journal article are more regarded than their counterpart in conference proceedings and manually searched articles. This means that reliably articles are selected for the review. The years 2007 and 2008 experienced high rate of publications on metaheuristic search techniques as indicated in Fig. 2. But 2011 and 2012 have higher number compared to 2009 and 2010. This means that we expect more papers on the field years to come. Considering the outcome of the studies based on the metaheuristic techniques used by each author (Q3.1), as shown in Fig. 3. It can be shown that GA outperformed its counterparts SA, HC, GP and random search approaches in generating test data automatically, as it was the frequent approach used by most of the authors. GA was used in 67% of the articles under review, representing a higher number in relation to other techniques. SA and TS were only used by 3 of the thirty (30) studies under review, representing 10% of the total articles under review. While HC and GP search techniques were applied in 2 studies each, representing 6.5% of the studies under review. The choice of using GA over other techniques can be as result to the nature of search mechanism used by GA. The possible solutions of a problem are presented as a population by GA, finding global optimum is far better in GA than SA which used one solution at a time. GA was prepared by most of the authors because they perform well for large number variables and complex input domains. Considering the results based Q3.2, i.e. the fitness function used for test data selection in each of the metaheuristic technique for testing the software. Authors used different approaches to make sure that test data are selected within shorter period of time and also with wider

Q3.3. Determining the limitation in the use of each search-based technique for software testing. Some metaheuristic techniques cannot handle and define fitness function for some complex data types, like array and object types [12], [42], or branch coverage [33]. Some handled object-oriented, but cannot describe some features, like inheritance and global initialization [15] on the control flow graph, others handled only one object instance [35]. The problem of multi-objective was addressed by using GA to generate test data by multi-population, but the aspect of instrumentation of the approach was conducted manually, i.e., the grouping of test data [40], selection of input test data [12], mutating the initial population [4], [26]. So also test data generation for method calls in OO cannot be accomplished only used link in the control flow graph to represent them, as in [15], handling of larger classes is another issue in OO [19]. Other works was conducted using small sample of input, so we cannot generalized based on the outcome of the work as in [10], [14], [16], [20], [21], [24], [45]. In [48] the results was only compared with random search technique, so we cannot make general conclusion



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coverage of the paths. The fitness functions were used to calculate the fitness value that served as main factor in how well a program is able to solve the problem. The selection of test data to be used in testing software in search-based optimization is through it fitness value. The value of individual is used as bases for selection of parents to be used for reproduction; this means that selection of individuals for crossover operation is based on the fitness value of each. Most of the authors designed the fitness function based on the structural properties of individuals. Those paths with loop and branch nodes were given more weight than the sequential nodes in testing the software; this is because of the complexity in the coverage. The limitations of some articles are the handling of complex data types, like array, object types, and branch coverage. But there are some partial solutions to those issues; branch coverage addressed by [40], the instrumentation were conducted manually. Some of the authors used simple problem to demonstrate the efficiency of their proposed approach, because of the complexity involve in using larger/complex problems. Based on the articles reviewed in the studies, we recommend the following as the possible future work in the area of search-based software testing: a. New technologies can be proposed that the techniques can be applied; like TaaS (Testing as a Service). Instead of only SaaS (Software as a Service) that is currently practice, where the software are provided to the users on demand, and also the upgrade of the existing software, testing can also be provided on demand from the users. Instead of employing expert by the developers that will be testing their product, the services can be provided on demand, i.e. TaaS. So also in the area of cloud computing, search-based techniques can be applied. b. The techniques can be applied on the handling of the execution environment of testing the software; operating system interactions, network access, and the databases. c. Proper handling of complex data types like arrays, multiple paths coverage, and object types. d. The empirical studies were conducted mostly on structural languages, they can be modified and test their efficiencies on other languages like objectoriented and aspect-oriented languages.

metaheuristic techniques used by each author, as shown in Fig. 3. It can be shown that GA outperformed its counterparts SA, HC, GP and random search approaches in generating test data automatically, as it was the frequent approach used by most of the authors. Considering the results based on the fitness function used for test data selection in each of the metaheuristic technique for testing the software. Authors used different approaches to make sure that test data are selected within shorter period of time and also with wider coverage of the paths. The limitations of some articles are the handling of complex data types, like array, object types, and branch coverage. But there are some partial solutions to those issues; branch coverage addressed by [40], the instrumentation were conducted manually. Based on this study, it was believed that there is need for studies to be conducted on the field of search-based software testing especially the automation of test data generation and the instrumentations of the approach. There is also need to apply search-based techniques in other technologies; like TaaS (Testing as a Service) and cloud computing.

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V.

Conclusion [10]

This study presented a systematic literature review that investigated the use of metaheuristic search techniques for testing software. The study was conducted on 47 primary studies and were selected based on the three research questions; the metaheuristic search techniques used in each study for testing the software, the fitness function used in each study for the selection of test data, and the limitations of each study based on the techniques used. Considering the outcome of the studies based on the

[11]

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Authors’ information Department of Information System, Faculty of Computer Science & Information Technology, University Putra Malaysia, 43400 Serdang, Selangor, Malaysia. Abu Bakar Md. Sultan was born in Melaka, Malaysia in 1965. He holds a PhD in Artificial Intelligence from University Putra Malaysia (UPM) in 2007. His research focus is in Artificial Intelligence and Software Engineering particularly Search-based Software Engineering (SBSE). He has published articles in conferences and various journals related to SBSE. Associate Professor Dr Abu Bakar Md. Sultan currently is the head of Information System Department, Faculty of Computer Science and Information Technology, UPM.



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Samaila Musa Born in Talata Mafara, Zamfara State, Nigeria, 1973. He obtained his B.Sc. in Computer science in 1998. He received his MSc. in Computer Science at Bayero University Kano in 2009. Currently; he is PhD student in the Faculty of Computer Science and Information System at University Putra Malaysia (UPM). His research interest is Search Based Software Engineering. Salmi Baharom received the PhD degree in computer science from the Universiti Kebangsaan Malaysia, Malaysia in 2010. She is a senior lecturer at the Information System Department, Faculty of Computer Science and Information Technology, Universiti Putra Malaysia. Her research interests include specification-based testing, software engineering education and database design.



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Optimum Configurations for an Open Source IP-PBX System with Botswana Telecommunication Corporation’s (BTC) PSTN Network Sajid M. Sheikh, Shedden Masupe Abstract – This paper outlines how Small Medium and Micro Enterprises (SMMEs) businesses and home users can mainly implement VoIP at their home and work places. This paper also outlines how an open-source system using asterisk can be configured to its optimum configurations to work with BTC’s (Botswana Telecommunication Corporation) PSTN telephone network in Botswana and thus replacing a traditional PBX system with an IP–PBX. It was discovered that an implementation using an Open source IP-PBX system namely Asterisk to connect and make calls using a Digium TDM400P card connecting to Botswana Telecommunication Corporation’s (BTC’s) existing PSTN network in Botswana, the Echo_Can_Mark2 echo canceller in asterisk works best providing minimal echo. Copyright © 2013 Praise Worthy Prize S.r.l. - All rights reserved.

Keywords: BTC, VOIP, PSTN, Open Source, IP-PBX, Echo Cancellers

I.

Introduction

II.

VOIP and PBX System

VoIP is the carriage of voice signals over packet switched network such as the Internet or a computer network. For the voice to be transmitted, it requires Packet switching and an IP Addresses to identity the end devices in the communication. VoIP therefore, sends voice information in digital form in packets rather than using circuit switched Telephone network (PSTN). In circuit switching a dedicated link is established during the duration of the call. A key feature that makes VoIP an attractive technology is the idea of a converged network for all voice, data and video to be carried over one network using the same infrastructure. Convergence of networks in many organizations and businesses in many parts of the world has led to the replacement of their traditional PBX systems with IP-PBX systems. Some closed source software such as Cisco Call Manager and other open source software such as Asterisk, OpenSIPS, Mjserver, MySIPServer, Kamailo, PartySIP and many more are available as the PBX system to handle the calling [1]. In Botswana, Botswana Telecommunications Corporation (BTC) is a parastatal organisation which provides, develops, operates and manages Botswana's national and international telecommunications services [2]. In this paper a study is done where an open-source system using Asterisk IP-PBX System is configured to operate like a PBX and connected to make calls over the BTC PSTN network. The study checks to determine which settings will make the system operate at its optimum for such an implementation.

Many call processing systems, both closed and open source have been developed and are in use. The difference between them includes features, platform and cost. Open source software based on Linux and Asterisk has been developed and is widely used in most countries. Closed Source Software based on Windows also exists and is also widely in use. The Asterisk ® Company done a study that compares the initial investment costs and total cost for implementation of its Switchvox unified communications solution (based on Asterisk) to competitive other IP PBX products in the market. The results indicated that small- and medium-sized business customers can achieve 60 percent savings on initial implementation and as much as 80 percent in the long run over a period of five-years with the Switchvox solution [3]. Some open-source call processing systems include: SwitchVox, Fonality PBXtra, Gizmo Project, Trixbox, AstLinux, Asterisk@Home and EasyVoxBox. Some closed source call processing systems include Cisco Call Manager and Octel Asterisk is Private Branch eXchange (PBX) software that runs on a Linux platform using a Computer. Asterisk is a complete Business Phone System PBX which is generally distributed under the terms of the GNU General Public License. Using Asterisk, a phone system can be built for any enterprise, no matter how large or small. This is because the system can scale from one user to literally thousands on hundreds of interconnected systems through clustering of servers (interconnecting more servers to accommodate more users and expanding



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the network). Asterisk’s needs are based on embedded and real-time application mainly due to calls requiring priority access to the processor and system buses for call processing. An interface card is required to interface this system to the PSTN network (T1, E1, Analog). Digium sells hardware components that operate with Asterisk such as PCI cards that connect standard analog phone lines to your computer [4].

III. Echo Is VOIP Networks Echo is the reflection of signals producing disturbance in the signal received during a call conversation. The Asterisk zaptel drivers provide seven echo cancellers namely: Asterisk mark echo canceller (mec), Asterisk mark2 echo canceller (mec2), Asterisk mark3 echo canceller (mec3), Asterisk steve echo canceller (sec), Asterisk steve2 echo canceller (sec2), Asterisk kb1 echo canceller (kb1ec) and Asterisk mg2 echo canceller (mg2ec) [5]. These can be seen in Figure 1 in the configuration window. The most common cause of echo is the point in the hybrid connection in the PSTN. This is where the 2-wire in the line connecting the handset of calling/receiving device is switched to the 4wire line (transmit and receive pairs) at the PSTN line connection. For there to be no echo an ideal conditions is required where the hybrid subtracts exactly the correct prorportion of the transmitted signal from the receive signal path to remove the echo caused by local loopback of the transmitted signal [6]. Almost all echo cancelling algorithms operate by duplicating multiple copies of the received signal, each duplicated signal delayed by some small time increment. This is the equivalent of a shift register casing a delay. The delayed signal appears at its own unique "tap". The number of taps determines the size of the echo delay that can be cancelled. These delayed copies are then weighted and subtracted from the original received signal. The accuracy of the signal depends on delaying the signal to exactly the extent needed to remove the echo. The methods used in determining the tap weights or scaling factors is what distinguishes one echo canceller algorithm in asterisk from another [6]. The echo canceller is programmers in such a way that it first listens and adjusts itself by computing the weights or scales when it first sees a signal at the input. The adjusting time depends upon the algorithm used and the number of taps. These can be set manually also in asterisk [6]. Only for one of the echo canceller’s available in asterisk can the description be found. Its algorithm description has been document and it is namely the Asterisk Mark Echo Canceller (mec). Asterisk mark echo canceller is a simple Least Mean Square (LMS) with Doubletalk detection. This is type of adaptive filter. The rest of the echo cancellers found in asterisk namely mark2, mark3, steve2, steve3 and kb1 have no description of the algorithm used at all [6].

Fig. 1. Echo canceller settings – display of zconfig.h file in asterisk

Therefore these difference echo chancellors work best for different scenarios. If voice is being transmitted, then echo cancellation is needed in the network at points that create the echo whether it is a circuit switched network (PSTN) or a packet-switched network (IP network). Echo occurs when the signals are reflected back at any point. In the case of the PSTN this occurs when there is a discontinuity such as when the 2-wire local loop changes over to a 4-wire connection in the network hybrid causing a portion of the signal to be reflected back to the source. This type of echo is known as line echo. There are other types of echo that can arise such as acoustic echo which occurs when the microphone picks up the audio coming out of the speaker. Poor quality handsets as well as situations where a speakerphone is being used are most susceptible to acoustic echo. Soft phones utilizing your computer speaker and microphone are particularly susceptible to these types of echo issues [7]. In a VoIP network which has no PSTN connection, line echo is not an issue. Echo created is such a network might have others causes besides line echo. In VoIP network situations acoustic echo is mostly a major concern. The solutions to acoustic echo can be to use IP phones with acoustic echo cancellation capabilities (AEC). When calls leave IP networks then line echo becomes a concern [7].

IV.

Methodology

A network was developed and configured as shown in Fig. 2 below.

Fig. 2. IP-PBX system implementation network



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In this section a brief overview of setting up the main dedicated asterisk PBX system is given. The details are given for an Asterisk@home and Trixbox server. The implementation for the PBX consisted of the following server configurations: 1. Adding extension code commands by assigning extensions; 2. Adding extensions at the GUI interfaces; 3. Configuring the digital receptionist; 4. Adding the Digium FXO; 5. Configuring the FXO card to the server; 6. Programming the inbound and outbound trunk settings to allow the system to receive and make calls; 7. Configuring the softphones on all workstation machines; 8. Configuring codecs on the server; 9. Configuring echo cancellers on the server; 10. Adjusting the transmitter and receiver gain setting on the server to receive appropriate voice levels on the system. The above process configuration process and methods are similar to those found in source [8]. However the most important setting on this converged system that connects to the PSTN network is the configuring of echo cancellors with the chosen hardware to avoid echo on the network. Due to the availability of many different hardware that can operate with VoIP applications, this study focused on optimum setting using a Digium TDM400P. Echo Cancellation was dealt with in a trial and error method by changing the software echo cancellers and trying each one out and noting which one works best for the implemented system setup. The criterion used for determining voice quality was based on the Mean opinion Scores (MOS) chosen by people on testing the system. The Mean Opinion Score Values are 5-crystal clear voice similar to a face-to-face conversation; 4-good where imperfections can be noticed and one knows that a call is through a system but the sound quality is still clear; 3-disturbing but one can understand the communication; 2-very disturbing and one can hardly make out what the caller is saving and 1 which is totally nothing being understood [9]. The call testing system used to generate the MOS results is shown Fig. 3 below.

to achieve clear voice communication.

Fig. 4. Block diagram showing echo cancellation of the signals

The Echo_Can_Mark2 echo canceller worked best with both of the implemented systems (the system with an extension to an existing PBX system and the system with a complete IP-PBX system). The Echo_Can_Mark2 echo canceller gave the least echo heard on both sides of the call conversation, call terminating on a PSTN phone. The MOS results are shown in Fig. 5. An average MOS of 4.82 was received for calls made using the Asterisk Mark 2 echo canceller.

MOS Score

Pentium 2 with a 100Mbps Switch

1 internal call

2 internal calls

3 internal calls

4 internal calls

external call

No. of Calls

Fig. 5. MOS results for internal and external calls using an Echo_Can_Mark2 echo canceller

For any system using Asterisk and a Digium TDM400P card connecting to BTC’s existing PSTN network in Botswana, the Echo_Can_Mark2 echo canceller will be one of the best choices compared with the other echo cancellers.

VI.

Conclusion

VoIP networks are slowly gaining their popularity in Botswana. A complete IP-PBX VOIP system can be implemented using softphones installed on workstations on the computer network, a connection of a server with Asterisk installed to a network and a PSTN network connection to the network through a PCI TDM FXO interface card installed in the server machine. This implementation can be of great cost savings as it does not require a separate PBX system and computer network. The existing computer network can be used to make an IP–PBX system. This system will gain attraction by Small, Medium and Micro Enterprises (SMMEs) and home users. To implement any Open source IP-PBX system using Asterisk to connect and make calls over BTC lines using a Digium TDM400P card connecting to BTC’s existing

Fig. 3. PSTN calls block diagram

V.

4.9 4.8 4.7 4.6 4.5 4.4 4.3 4.2 4.1 4

Results

Echo is not generally created in the computer network or the VOIP network as it is primarily digital. The connection to the PSTN network is where the echo is generated and as illustrated in the Figure 4. For users of an Asterisk based IP PBX that have connections to the PSTN, line echo needs to be dealt with



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Dr. S. Masupe is the Head of Department and Senior Lecturer in the Department of Electrical Engineering, University of Botswana. Dr. S. Masupe holds qualifications PhD (Edinburgh), MSc (Cardiff), BSc (Mt Allison) and BSc Eng(New Brunswick); and is a Member of IEEE and MBIE. Dr. Masupe specializes in Microprocessor Architectures, Low Power VLSI and Computer Vision. Dr. Masupe’s research interests are in the areas of Low Power VLSI Design, DCT-Based Image Compression Techniques, Microprocessor Architectures, Computer Systems and HDL Based Design Methodologies.

PSTN network in Botswana, the Echo_Can_Mark2 echo canceller in asterisk works best providing minimal echo that is caused by the line echo. The Echo_Can_Mark2 echo canceller is configured in software. The echo is generated where the network connects to the PSTN at the point where the 2-wires in the hybrid connect to the 4wire line (transmit and receive pairs) at the PSTN line connection. The accuracy of the signal depends on delaying the signal to exactly the extent needed to remove the echo.

References [1]

Online Search, http://bytecoders.hubpages.com/hub/10-OpenSource-VoIP-servers-and-proxies, cited on 27 February 2012. [2] Online Search, http://www.btc.bw/, Botswana Telecommunication Corporation, Cited on 20 February 2012. [3] Online search, http://www.businesswire.com/news/home/20110301006381/en/T otal-Cost-Ownership-Evaluation-Shows-Savings-60, cited 16th March 2012. [4] Jim Van Meggelen, etal, Asterisk- The Future of Telephony, O’Reilly Media, USA, 2007, ISBN-10: 0-596-51048-9. [5] Online Search, www.voipinfo.org/wiki/view/Asterisk+echo+cancellation, on Asterisk Echo cancellers, cited on 20 May 2011. [6] Online Search, http://markmail.org/message/invo37ezsyqndypg, Cited on 27 February 2012. [7] Online Search, http://www.electric-words.org/whitepapers/whpapika-echo_cancellation.pdf, Cited on 27 February 2012. [8] Online Search, http://asteriskathome.sourceforge.net/handbook/, Asterisk@Home without Tears textbook Cited on 18 May 2011 [9] Online Search, http://voip.about.com/od/voipbasics/a/MOS.htm , cited on 20 May 2011. [10] G. Singh, A. Pal Singh Atwal, B. S. Sohi, Application Controlled Mobile IP Handoff for 802.11 Wireless Networks, (2007) International Review On Computers and Software (IRECOS), 2 (4), pp. 371 – 381. [11] Wengang Zhou, Leiting Chen, Shi Dong, Lubomir Bic, Mingtian Zhou, A Fluid Model for TCP Flows in Large IP Networks, (2012) International Review On Computers and Software (IRECOS), 7 (2), pp. 791-796. [12] Reza Chogan, Mostafa Heidarzadeh, Hassan Yeganeh, Hosein Mohammadi, Vulnerability and VoIP Threats Survey in Broadband Networks, (2012) International Review On Computers and Software (IRECOS), 7 (6), pp. 3021-3026.

Authors’ information Mr. Sajid M. Sheikh is a Lecturer in the Department of Electrical Engineering, University of Botswana. Mr. Sheikh is an Electrical and Electronic Engineer, specialising in Electronic Systems, ICT, Computer Hardware and Networking. Mr. S. M. Sheikh holds qualifications of MSc in Electronic Systems Engineering from the University of Botswana, BEng in Electrical and Electronic from the University of Botswana and is a Member of IEEE. Mr. Sheikh’s research interests are in the areas of Design and Implementation of VoIP, poverty eradication solutions and mLearning Solutions and Application development.



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How Vulnerabilities in Wireless Networks Can Enable Advanced Persistent Threats Roger Piqueras Jover, Paul Giura Abstract – With the tremendous popularity of mobile devices and their increasing adoption in the corporate environments, there is a larger opportunity for Advanced Persistent Threats (APTs) to exploit vulnerabilities in wireless and mobility networks. We review several vulnerabilities and successful attacks in this domain, and evaluate the possibility of these attacks to be used by APTs. Our analysis shows that known attacks in the mobility domain are powerful enough to contribute to the success of an APT operation. Copyright © 2013 Praise Worthy Prize S.r.l. - All rights reserved.

Keywords: Advanced Persistent Threat, Security, Wireless Communications

I.

Typical security analyses focus on scalable attacks that can target infrastructure, millions of users, etc. Many attacks to cellular networks (i.e. GSM) have not gathered much attention because of that aspect. However, with the advent of APT, scale is no longer the issue. The most precise and targeted attacks are the most effective. In this paper we evaluate the possibility of APT operators exploiting known attacks and vulnerabilities in the wireless and mobility domain to accomplish their missions. Our analysis provides a useful insight not only for detection of APT but also for the forensic investigations that follow up the discovery of an attack. To our knowledge, no other study leverages the possibility of attackers exploiting vulnerabilities of wireless networks to launch and maintain an APT.

Introduction

Advanced Persistent Threats (APTs) are some of the fastest growing information security threats that organizations face today [1]. They are operated by very skilled and well funded attackers targeting sensitive information from specific organizations. The ultimate goal is to steal intellectual property created from expensive research, to gain access to sensitive customer data or to strategic business information that could be used for illegal insider trading, or to disrupt an organization's business. APT can best be defined using the words deriving the acronym [2]. Advanced (A) means that attackers are well trained, organized, well funded and utilize a full spectrum of network intrusion technologies, crafting their own tools if needed. Persistent (P) refers to the persistence of the attack over long periods of time. Attackers give high priority to a specific task, rather than opportunistically seeking immediate gain, and maintain a prolonged presence in the compromised organization networks. Threat (T) refers to the attackers’ intention to inflict damage and create loss by disrupting services or stealing proprietary data. APTs have become very sophisticated and diverse in the methods and technologies used, particularly in the ability to use organizations' own employees to penetrate the IT systems [1]. They are characterized as “low and slow” advanced operations: “low” for maintaining a low profile in the networks and “slow” for long execution times. Analyses of specific APT instances conclude that each operation is unique and highly customized for each target ([1], [3][5]). However, across many operations, the stages are similar and they differentiate mostly in the specific methods used to achieve each milestone. Fig. 1 shows these stages in the order in which they are typically executed over long periods of time, and what are the actions within each stage.

Fig. 1. Typical stages of an APT

With this work we make the following key contributions:  We provide a review of relevant recent known attacks in the wireless and mobility domain.



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Despite its effectiveness, jamming can be potentially detected and it requires the attacker either to be in the close vicinity of the victim or to transmit a very large amount of power, which alerts of its presence. Smart Jamming Attack: This technique aims to locally disrupt the communications of a wireless network in an undercover way raising no alerts. This is done by means of saturating one or more of the essential control channels required by all mobile devices to access the spectrum. Multiple studies in the literature theoretically demonstrate how to saturate a cellular network by means of, for example, text messages (Short Message Service, SMS) [10] or sustained and periodic set-ups of data connections [11]. Smart jamming is a simple more localized attack that is aimed at low layers. It targets essential control channels shared by all the users within a cell that carry signaling information during the initial access to the system. Saturation of these channels would make the network appear unresponsive and could force a phone to switch to a GSM connection. In parallel, given that this attack requires low transmitted power and can be done at pre-authentication, detection and mitigation are difficult. This attack has been already demonstrated in the context of GSM networks ([12], [13]) and is theoretically possible on 3G and LTE (Long Term Evolution). A recent report discusses about the feasibility of jamming Long Term Evolution (LTE) networks in a similar way [14].

 We assess the possibility that the wireless and mobility attacks can be used to accomplish various actions of a potential APT.  We recommend a set of preventative measures that should be considered in order for organizations to reduce the risk of being targets of successful APTs. The rest of the paper is organized as follows: Section II surveys some of the wireless networks vulnerabilities and known attacks exploiting them, Section III shows how vulnerabilities can be used by APTs, Section IV lists a set of practical measures that can limit the success of APTs, and, finally, in Section V we present our conclusions.

II.

Vulnerabilities in Wireless Cellular Networks

This section presents an overview of the vulnerabilities and weak points that attackers could exploit in order to prepare, launch and maintain an APT. For example, both data and voice communications could potentially be eavesdropped during the Reconnaissance stage to profile employees. The information obtained in this stage could be used to optimize the crafting of malware and spear-phishing techniques in the Delivery stage. With the deployment of a rogue Base Station (BS), the actual Delivery and Exploitation stages could be implemented. Finally, a wireless terminal connected to the mobility network could potentially be used in the Exfiltration stage, avoiding the enterprise firewall. II.1.

II.2.

GSM Location Leaks

Vulnerability: The way cellular networks handle incoming calls leaks some information that can be used to locate a device. Upon an incoming connection, the core network attempts to find the mobile station within an area where it was known to have been recently, known as the Location Area Code (LAC) [15]. To do so, paging messages are sent over all the cells contained in the LAC. These paging messages as well as the responses sent on the Random Access Channel are not encrypted and can potentially be sniffed by an attacker. Target Localization Attack: The authors of [16] demonstrate a practical technique to locate a specific target given its phone number. By means of sniffing traffic and discarding locations where the target is not present, it is possible to locate a mobile user in terms of cell. This allows the attacker to locate its victim and proceed to jam that specific cell. Similar techniques are introduced in [17] to locate any device.

Default Fall Back to 2G Networks

Vulnerability: By design, all cellular networks based on 3GPP standards (i.e. GSM/GPRS/EDGE, UMTS and LTE) fall back to a basic 2G (Global System for Mobile Communications, GSM) connection when connectivity on 3G or beyond cannot be achieved. This can be as a result of traffic balancing or because reception on the desired radio band is not possible. In this way, a mobile device can always be online independently of the 3G footprint of a given provider. It is well known that 2G networks are insecure and provide weak encryption [6]. Given the lack of dual authentication of GSM [7], this fall back can potentially create a security breach. Multiple vulnerabilities that could be exploited in this situation are analyzed in the remainder of this section. In order to attempt different attacks, jamming tools are often applied to force phones to fall back to 2G. Jamming Attack: Radio jamming is the deliberate transmission of radio signals to disrupt communications by decreasing the signal to noise ratio. This attack has been studied in the literature in the context of cellular communications [8]. By means of a radio jammer, an attacker could make a cell-phone unable to detect any 3G base station, forcing it to fall back to GSM to access the network [9].

II.3.

GSM Security

Vulnerability: The second generation of wireless networks (2G or GSM) has been in wide use for a very long time. Its security attributes, considered strong at the time of deployment, have been proven to be vulnerable as technology evolved and allowed attackers to obtain



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the necessary tools at low cost. Over the last few years, multiple attacks have exploited such weaknesses. The three main features of GSM security are: 1) authentication of the subscriber accessing the network, 2) encryption of user data at the radio interface and 3) use of temporary identities for confidentiality [7]. The first two features are based on an individual secret key (Ki) stored in the SIM card of a mobile terminal. Another copy of this key is stored at the network authentication center. The authentication of the subscriber is performed with a challenge message sent from the network. The phone responds with the result of applying a cryptographic function with the secret key and the challenge. In parallel, a temporary session key (Kc) is generated. This is the key used to encrypt the radio traffic. The subscriber identity (IMSI) is kept secret and it is only transmitted over the air on very special occasions; a temporary identity (TMSI) is used for most of the transactions. The asymmetry of the authentication protocol, that does not require the network to identify itself, makes a Man-in-the-Middle (MitM) attack possible. Man-in-the-Middle Attack: Many security features of GSM have been defeated over the last few years [18]. As illustrated in Figure 2, an attacker is able to deploy a rogue base station and get target users to attach to it. Given that the authentication algorithm is not symmetric, the network is not required to authenticate, so the device believes it is connected to a real Base Station. To achieve a full Man-in-the-Middle (MitM) position, the attacker attempts to access the network claiming the victim's identity. After receiving the challenge message from the network, the challenge message is forwarded to the victim. The victim's reply with the correct response is, in turn, forwarded to the network. This kind of attack has been discussed in the context of 3G networks as well [19]. Researchers have shown how, by means of a rogue base station, phishing attacks can be launched to a victim in order to obtain all kinds of credentials such as banking information, logins, passwords and other highly sensitive information [20]. In a similar way, malware can be forced into the device.

II.4.

GSM Encryption

Vulnerability: The A4 is the GSM encryption algorithm for the radio interface [7]. It is based on the session key Kc described in Section II.C. This 64-bit key is combined with the frame number (22 bits) in order to generate a pseudo-random key stream (114 bits) that is combined (XOR) with the plain text message to generate the encrypted message. This algorithm has been expanded with multiple variations (A5/1, A5/2, A5/3 and A5/0). During the connection and authentication step, the phone and the network agree which algorithm to use. Note that A5/0 stands for not applying any encryption at all so, by means of a rogue base station, an attacker could fool a victim to turn off encryption. GSM Sniffing/Hacking Attack: The A5 algorithm has been recently cracked. This allows an attacker to eavesdrop and decrypt all the traffic a victim generates as well as the traffic that is received. The authors of [6] present a way to break the encryption by means of rainbow tables and obtain the session key. After identifying a victim and its TMSI, the attacker sends a text message to the target device to force it to establish a connection. The attacker then eavesdrops on the handshake between the device and the base station to transmit the message. This is a known handshake protocol, therefore both the plain text and the encrypted version of several control messages are known. A lookup on a rainbow table provides the session key that was used. Once the session key is obtained, all transactions can be decrypted in real time. II.5.

WAP Protocol and Provisioning

Fig. 2. Man in the Middle attack and Connection Hijacking

Vulnerability: The Wireless Application Protocol (WAP) defines industry-wide specifications for developing applications that operate over wireless communication networks [21]. It is responsible for initialization and alert messages and defines how PUSH and PULL applications interact with the network. One of the main functions of WAP is provisioning, which defines how a WAP client (cellphone) is configured for a specific application. In the case of PUSH applications, a special message is sent to the phone informing that there is content available. This message indicates to the phone the address from where to obtain the content. PUSH messages are also used to display alerts or messages on a phone. Both PUSH and provisioning messages are trusted and executed by the phone. Therefore, a malicious provisioning message could tamper with the phone's configuration. Crafting a PUSH message with the address hosting a piece of malware could force an infection into a phone. Malicious PUSH messages can also, for example, display messages on the screen fooling the user into typing a password. Connection Hijacking Attack: It has been demonstrated that provisioning messages can be maliciously crafted and sent to a victim from a rogue



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base station. In this way, an attacker can change configuration settings of a phone. In particular, it is shown that the DNS configuration can be tampered to force connections through a malicious proxy that eavesdrops and captures all traffic [9]. This attack is also illustrated in Fig. 2. Additionally, a spoofed PUSH message can potentially be used to trick a user to install malware on a phone [9]. Note that, in order to launch this attack, the victim has to be connected to a rogue GSM Base Station. II.6.

provide an attacker with access to employee information for social engineering. Voicemail Hacking Attack: The recent News of the World scandal [24] brought mainstream attention to the feasibility of spoofing the caller ID and how this allows attackers to hack into voicemail accounts with no password or a default one.

Mobility

Vulnerability: A cell-phone is, by definition, a mobile terminal that is with the user most of the time. The mobility of such a device enhances the threats on security networks it connects to. In the context of an APT, a cellphone might open the doors to attacks by circumventing security barriers such as firewalls (Figure 3). In current scenarios, an attacker trying to gain access to the inside of a corporate network crafts a phishing email very selectively targeted to someone within the organization. Other social engineered techniques are known to be used, such as physical access to the terminals and malware deployment by means of, for example, a USB drive. Mobile terminals present, though, a simpler alternative. Firewall Circumvention, Malware Deployment and Data Exfiltration Attacks: As described in Section II.E, a user can be fooled into downloading a piece of malicious code without installing any application. This malware can potentially be transferred to any computer to which the phone is physically connected, for example, to charge the battery. There are known attacks that aim to exhaust the victim's phone battery [22]. In this way an attacker can force a victim to plug the phone to a computer to charge it. In parallel, a mobile device often creates a bridge between a secured network environment, i.e. between the firewalls and the outside world (Fig. 3). This happens in the case of a mobile phone connected to the Internet via a 3G connection that is, in parallel, connected to a host within a corporation network. Also, a phone can sometimes be in a secure (corporate) network and later in a less secure one (home network). Beyond deploying malware, an infected phone can also potentially be used to exfiltrate data. The actual contents of the phone or files from the host computer could be delivered to a server under the attacker's control over WiFi or 3G using the phone as a bridge to circumvent firewalls. II.7.

Fig. 3. Mobility + USB circumventing corporate firewalls

II.8.

USB Interface

Vulnerability: USB has become the universal standard for both data transferring and battery charging in smart phones. In both processes, the phone is physically connected to a computer. The communication protocol over USB is inherently trusted and assumed to be secure. This is mainly due to the physical proximity between the two devices and the fact that it is the user who connects them. The USB protocol is equipped with no mechanisms to authenticate the validity of the device attempting to communicate with the host. This potentially allows an attacker to disguise and report itself as a different device, such as a USB keyboard, mouse, etc. This trust is known to be often abused in the context of USB pen drives or memory sticks [25]. Known instances of malware can exploit certain vulnerabilities of the USB boot process to deploy a malicious payload on the host. Malware Transmission Via USB Attack: In [26] authors demonstrate how these vulnerabilities can be exploited in the context of smart-phones. They show that a smart-phone connected to a host can claim to be a USB keyboard and send keystrokes. The attacker gains full access to the host under the privileges of the current user. This can potentially be used to install malware or exfiltrate data. Once mounted, the device has full control to drop any specially crafted media file to exploit the corresponding processing engine. The same authors describe a symmetric attack vector that allows an attacker to deploy a malicious payload into a mobile device from the computer it is connected to. This exploit, combined with the mobility of a cell-phone, allows an attacker to infect a user in a less secure location (home) and the payload to be deployed into the corporate network, circumventing firewalls (Fig. 3).

Voicemail

Vulnerability: Secured access to voicemail accounts is primarily based on a password being used for authentication. However, many cellular providers have the password for the voicemail as an optional feature that the user can deactivate, and sometimes the default password is not changed [23]. This could potentially



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Fig. 4. Leveraging wireless network vulnerabilities to initiate, maintain and complete an APT

and 4). The encryption of GSM can be broken to listen to calls and read messages, providing further information for the employee's profiling. A malicious PUSH or provisioning WAP message can be used to tamper the DNS configuration of a phone. From that point, all traffic can be re-routed through a malicious proxy controlled by the attacker and information can be extracted [9]. Further social engineering data can be obtained by hacking into the voice-mail [23]. These methods potentially allow an attacker to obtain all kinds of information from a set of victims and to elaborate a complete profile about them. Once a piece of malware or a rootkit is deployed on the phone, the victim profiles can be completed with extra data such as location information. The malware can potentially turn on the field test mode in the phone to track the location of the set of victims.

III. APT in Mobility Domain An APT has a specific target, which could be a person, proprietary data or organization assets. Each one of the security incidents and exploitations can occur in a combination of different contexts. It is precisely this combination of environments that makes this attack very difficult to detect. Entry vectors are often assumed to use wired networks. In this section we show how the attacks described in Section II can be used throughout an APT operation. We assume that the core of the attack, i.e. Operation and Data Collection stages, must be completed by an attacker from within the corporate network. These stages cannot take advantage of any vulnerability in wireless networks. However, we show that the attacks described in Section II can be leveraged to achieve the remainder steps of the APT. Based on the model in Fig. 1, the intrusion is divided in 4 stages on the left column of Fig. 4. The second column lists multiple actions and milestones that are defined for each stage. The attacks analyzed in Section II are placed on the remainder columns. The body of Figure 4 indicates what milestones can be reached using each attack. Finally, the arrows indicate one example strategy to launch, maintain and complete an APT operation. Each step is indicated with a shaded rectangle and label numbers represent the order of the steps, multiple steps being possible for most actions.

III.2. Delivery/Exploitation Given their mobility, cell-phones are a potential platform for malware infection of terminals within the boundaries of the corporate firewalls. Sections II.6 and II.8 describe how vulnerabilities in the USB protocol can be exploited to transfer a malicious payload from an infected computer at an insecure location to a mobile phone. The infection is then transferred to a corporate machine. Note that, known attacks that aim to exhaust the battery of a phone [22] can be added to the equation to force the actual physical USB connection to recharge the phone. A malicious payload can be forced into the victim's phone by means of a spear-phishing PUSH message or from a rogue base station (Steps 5 and 6 of Figure 4). Then, exploiting USB vulnerabilities and the inherent mobility of the phone, the malware is transferred into the employee's corporate machine, allowing the attacker to control it (Steps 7 and 8). Finally, diverse access information is obtained by launching multiple attacks

III.1. Reconnaissance In the initial Reconnaissance stage, an attacker could identify and locate a victim by means of sniffing paging messages and exploiting location leaks (Step 1 in Figure 4). Assuming that a phone has been forced to fall back to GSM (i.e. jamming, Step 2), an intruder can launch a Man in the Middle attack. This gives the attacker the ability to extract information for profiling and to scan potential vulnerabilities of the victim's device (Steps 3



149


(Step 9). The victim is fooled into entering credentials such as usernames, token codes, passwords, etc. [20]. In parallel, the GSM encryption can be broken so communications can be eavesdropped on the fly or stored for later analysis [6]. The malicious payload in the victim's phone can also be used to exfiltrate information such as contacts, recent called numbers and other data stored in the device. With the stolen credentials, an attacker can gain access to an insider's account. From that initial victim, a further phishing email can be sent to a second victim. This technique could be applied to elevate privileges and move closer to the target.

developed a prototype app to allow a user to manually disable GSM 2G. Enforce voicemail password: The enforcement of a password for employee's voice mail is a simple and effective measure that can help prevent voicemail hacking. Enable wireless data monitoring: Monitoring closely data traffic generated over cellular networks has the potential to reveal some of the malicious activities that a device might be involved in, such as malware download, data exfiltration or leaking of location information. Mobility data should be added to the set of environments monitored by corporations for security and forensic investigation purposes. The APT detection mechanisms should look for signs of attacks by considering broader contexts around possible targets, such as proprietary data servers, high profile employees, critical assets, etc. Table I indicates the attacks from Section II that can be avoided or mitigated by means of each preventative measure. Note that paging messages can potentially be sniffed, therefore allowing mobile phones to be located.

III.3. Exfiltration Finally, because of their inherent mobility, cell-phones can potentially be used as a platform for a sequential exfiltration of targeted data (Steps 11 and 12 in Fig. 4). Instead of tunneling the stolen data through firewalls and protected perimeters to some external server, data could be gathered in small pieces by one or multiple phones. These, in turn, forward the chunks of data to an external server either over the 3G connection or over WiFi. To ensure the exfiltration process goes undetected, the phone only uses the employee's home connection. In this way, the actual exfiltration process originates in a less secure location.

IV.

TABLE I ATTACKS MITIGATION MEASURES Attacks Policy 2G OFF VM-Pwd Jamming (II-A) X Location (II-B) MitM (II-C) X GSM Sniff (II-D) X Hijacking (II-E) X Mobility (II-F) X Voicemail (II-G) X USB (II-H) X

Preventative Measures

Even though some attacks described in Section II are difficult to detect, certain preventative measures can be taken to minimize the probability of exploitation. We propose a few items that organizations should consider that have the potential to raise the bar for APTs and can help forensic investigations. Personal/work device policy: It is difficult to enforce a policy to avoid the use of personal devices. A simpler policy, though, can be enforced for cell-phone usage in work environments. For example, work devices can only be synched at workstations and, while at home, they can only be charged by plugging into the outlet. Conversely, personal phones can only be synched at home and, while at work, they can only be charged by plugging into the outlet. In this way, firewall circumvention via mobile devices would not be possible. Enable 2G ON/OFF switch: As long as GSM networks remain active, the threats described in Section II will be present. However, the possibility of turning off 2G on a phone would be very beneficial to overcome 2G limitations. Forcing all the traffic of an employee's work phone to be transmitted on 3G would make it impossible for an attacker to launch certain attacks. While most phones allow a user to disable 3G, such functionality is not typically available for disabling 2G. We have

V.

Monitor

X X X X X X

Conclusion

This research has reviewed several wireless networks and mobility vulnerabilities and has evaluated the possibility of known attacks to be exploited by an APT operation. Our study shows that the attacks surveyed have the potential to initiate and maintain an APT operation by providing several information-gathering opportunities in the Reconnaissance stage, malware deployment in the Delivery/Exploitation stage, and silent export of data from within the enterprise's network in the Exfiltration stage. Additionally, we propose a set of preventative measures that enterprises can use in order to detect and to address some of the presented vulnerabilities and attacks. In future work we seek to identify quantitative methods to assess the potential APT risk that the increasing use of mobile devices can bring to enterprise environments.

References [1]

[2]


RSA. RSA Security Brief: Mobilizing Intelligent Security Operations for Advanced Persistent Threats, http://tinyurl.com/6n6rqfp, February 2011. P. Giura and W. Wang, Using Large Scale Distributed Computing to Unveil Advanced Persistent Threats, Academy of Science and


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Engineering Science Journal, vol.1, no. 3, December 2012, pp. 93-105. B. Krekel, G. Bakos, and C. Barnett, Capability of the People’s Republic of China to conduct cyber warfare and computer network exploitation, The US-China Economic and Security Review Commision, Washington, DC, Research Report, 2009. Damballa, The Command Structure of the Aurora Botnet, http://www.damballa.com/research/aurora/, March 2010. SANS Technology Institute, Assessing Outbound Traffic to Uncover Advanced Persistent Threat, http://tinyurl.com/65sg29s, May 2011. K. Nohl and S. Munaut, Wideband GSM sniffing, In 27th Chaos Communication Congress, 2010, http://tinyurl.com/33ucl2g G. Horn, D. Forsberg, W. Moeller, and V. Niemi, LTE Security (John Wiley & Sons, 2010) . W. Xu, Y. Zhang, and T. Wood, The feasibility of launching and detecting jamming attacks in wireless networks, In ACM MOBIHOC, 2005, pp. 46-57. C. Mune, R. Gassira, and R. Piccirillo, Highjacking mobile data connections, In BlackHat Europe, 2009, http://tinyurl.com/7b2gvdg. P. Traynor, W. Enck, P. Mcdaniel, and T. La Porta, Exploiting open functionality in SMS-capable cellular networks, In J. Comput Secur., vol. 16. Amsterdam, The Netherlands, IOS Press, December 2008, pp. 713–742. P. Lee, T. Bu, and T. Woo, On the detection of signaling dos attacks on 3G wireless networks, In INFOCOM 2007: 26th IEEE International Conference on Computer Communications. IEEE, May 2007, pp. 1289-1297. Grugq, Base jumping: Attacking the GSM baseband and Base Station, In BlackHat Abu Dhabi, 2011, http://tinyurl.com/7laga5r. D. Spaar, A practical DoS attack to the GSM network, In DeepSec 2009, http://tinyurl.com/7vtdoj5. Talbot, David, One Simple Trick Could Disable a City’s 4G Phone Network, MIT Technology Review, November 2012, http://www.technologyreview.com/news/507381/one-simpletrick-could-disable-a-citys-4g-phone-network/ 3rd Generation Partnership Project, Mobile radio interface layer 3 specification, 3GPP TS 04.08, vol. v7.21.0, 2004. D. Kune, J. Koelndorfer, and N. Hopper, Localization leaks on the GSM air interface, In 18th Annual Network and Distributed System Security Symposium, ser. NDSS ’12, 2012. D. Bailey and N. DePetrillo, The Carmen Sandiego Project, In BlackHat USA, 2010, http://tinyurl.com/85mtblw. E. Gadaix, GSM and 3G security, In BlackHat Asia, 2001, http://tinyurl.com/85plhlv. U. Meyer and S. Wetzel, A man-in-the-middle attack on UMTS, In Proceedings of the 3rd ACM workshop on Wireless security, ser. WiSe ’04. New York, NY, USA: ACM, 2004, pp. 90–97. D. Perez and J. Pico, A practical attack against GPRS/EDGE/UMTS/HSPA mobile data communications, In BlackHat DC, 2011, http://tinyurl.com/7wuf3er. Open Mobile Aliance, WAP Architecture, http://www.openmobilealliance.org. R. Racic, D. Ma, and H. Chen, Exploiting MMS vulnerabilities to stealthily exhaust mobile phone’s battery, In Proceedings of the Second IEEE Communications Society / CreateNet International Conference on Security and Privacy in Communication Networks, 2006. Boston-WCBTV, Websites show how to ’spoof’ caller id. voice mail hacking: Easier than you think?, July 2011, http://www.thebostonchannel.com/r/28674908/detail.html. N. Davies and A. Hill, Missing Milly Dowler’s voicemail was hacked by News of the World, In The Guardian UK, July 2011, http://tinyurl.com/6c6jgmw. D. V. Pham, A. Syed, and M. N. Halgamuge, Universal serial bus based software attacks and protection solutions, Digital Investigation, vol. 7, no. 3-4, pp. 172–184, 2011. Z. Wang and A. Stavrou, Exploiting smart-phone USB connectivity for fun and profit, In Proceedings of the 26th Annual Computer Security Applications Conference, ser. ACSAC’10. New York, NY, USA: ACM, 2010, pp. 357–366.

Authors’ information AT&T Security Research Center. New York, NY, 10007. Roger Piqueras Jover graduated from the Escola Tècnica Superior d'Enginyeria de Telecomunicacions de Barcelona (ETSETB) in 2006 with the degree of Telecommunications Engineer. That same year he was awarded a Balsells Fellowship to pursue graduate studies in Electrical Engineering at the University of California in Irvine, where he graduated in 2008 with an MSc in Electrical and Computer Engineering. In 2010 he graduated with an MPhil/MSc in Electrical Engineering from Columbia University. He is a Member of Technical Staff at the AT&T Security Research Center. His research interests are in the area of mobile and wireless communications, radio resource allocation, new network architectures and security for wireless networks. Mr. Piqueras Jover is a professional member of the IEEE, Communications Society, the Association of Computing Machinery and Sig Comm. Paul Giura received his Ph.D. and Masters in Computer Science from the Department of Computer Science and Engineering at Polytechnic Institute of New York University in 2010 and 2007 respectively, and Bachelors in Computer Science from University of Bucharest, Romania in 2004. He is a Senior Member of Technical Staff at AT&T Security Research Center in New York City. His research interest is in the areas of network and device security, advanced persistent threat detection and mitigation, forensics, big data for security, systems and databases. Dr. Giura is a professional member of IEEE, Computer Society, an active contributor to Cloud Security Alliance mission, and serves in several technical program committees and editorial boards for leading security conferences and journals.



151


A Study of XML with HOSTEL Yanchun Ma, Cuirong Zhang Abstract – Many hackers worldwide would agree that, had it not been for erasure coding, the improvement of forward-error correction might never have occurred. After years of practical research into IPv7, we disprove the investigation of scatter/gather I/O. In this paper we motivate a novel application for the emulation of web browsers (HOSTEL), which we use to show that randomized algorithms and link-level acknowledgements are largely incompatible. Copyright © 2013 Praise Worthy Prize S.r.l. - All rights reserved.

Keywords: XML, Emulation, Web Browsers, Randomized Algorithms

I.

Introduction

Many systems engineers would agree that, had it not been for the understanding of public-private key pairs, the study of congestion control might never have occurred. The notion that mathematicians collude with object-oriented languages is often well-received. However, a robust grand challenge in machine learning is the evaluation of the visualization of online algorithms. As a result, trainable technology and DHTs are regularly at odds with the exploration of superblocks. To our knowledge, our work in our research marks the first framework analyzed specifically for distributed communication. The flaw of this type of solution, however, is that erasure coding can be made linear-time, modular, and robust. The influence on theory of this has been adamantly opposed. This combination of properties has not yet been investigated in related work. In this work we concentrate our efforts on confirming that the UNIVAC computer and the UNIVAC computer are mostly incompatible. Similarly, we view software engineering as following a cycle of four phases: refinement, storage, location, and study [1], [2], [3], [4]. Indeed, DHCP and the location-identity split have a long history of interacting in this manner. We allow telephony to enable adaptive communication without the synthesis of IPv6. Without a doubt, the usual methods for the exploration of the producer-consumer problem do not apply in this area. This combination of properties has not yet been evaluated in existing work. In this paper, we make two main contributions. We construct a novel framework for the study of cache coherence (HOSTEL), demonstrating that context-free grammar and the transistor are regularly incompatible. We use probabilistic methodologies to show that the much-touted certifiable algorithm for the visualization of expert systems by Charles Darwin et al. [5] runs in Ω(n) time. The rest of this paper is organized as follows. To start off with, we motivate the need for Byzantine fault tolerance. Similarly, we place our work in context with the previous work in this area. Manuscript received and revised February 2013, accepted March 2013

Despite the fact that such a claim at first glance seems perverse, it fell in line with our expectations. To fix this issue, we propose an analysis of vacuum tubes (HOSTEL), disconfirming that Moore's Law and architecture can interact to address this question. Despite the fact that this might seem counterintuitive, it usually conflicts with the need to provide IPv7 to experts. Next, to answer this issue, we introduce new decentralized theory (HOSTEL), demonstrating that von Neumann machines can be made robust, psychoacoustic, and "fuzzy" [3]. Finally, we conclude.

II.

Related Work

A number of existing applications have evaluated 802.11b, either for the investigation of A* search [6], [7], [8], [9] or for the improvement of the Ethernet [3], [4], [10]. Further, Williams [7], [11] developed a similar system, on the other hand we disproved that HOSTEL is NP-complete [5]. John Backus [12], [13], [14], [3], [15] originally articulated the need for read-write epistemologies. In general, our application outperformed all related heuristics in this area. Our solution is related to research into write-back caches, fiber-optic cables, and symmetric encryption [13], [16], [17]. A system for the analysis of Scheme [11], [10], [12], [18], [19] proposed by Zheng and Zhou fails to address several key issues that HOSTEL does solve [20]. Garcia [21] suggested a scheme for evaluating replication, but did not fully realize the implications of cacheable configurations at the time [22], [23]. This is arguably ill-conceived. Finally, note that HOSTEL prevents certifiable archetypes; therefore, our algorithm follows a Zipf-like distribution [17]. A number of related applications have developed 64 bit architectures, either for the construction of hierarchical databases or for the deployment of IPv7 [21], [24]. Recent work by Timothy Leary et al. [25] suggests an algorithm for investigating the emulation of web browsers, but does not offer an implementation [26].


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Yanchun Ma, Cuirong Zhang

As a result, the framework of Bose and Kobayashi [27], [2] is a significant choice for Smalltalk [7].

Our overall performance analysis seeks to prove three hypotheses: (1) that write-ahead logging has actually shown improved hit ratio over time; (2) that information retrieval systems no longer toggle system design; and finally (3) that effective seek time is more important than NV-RAM throughput when optimizing sampling rate. We are grateful for independent link-level acknowledgements; without them, we could not optimize for security simultaneously with median throughput. We hope that this section sheds light on the work of American physicist Butler Lampson.

III. Framework Next, any private study of active networks will clearly require that semaphores and architecture are rarely incompatible; our framework is no different. We believe that RAID can construct the study of checksums without needing to learn architecture. Fig. 1 depicts the relationship between our methodology and DHTs. Suppose that there exists the Ethernet such that we can easily harness the analysis of compilers [28], [29], [30]. Our application does not require such a robust emulation to run correctly, but it doesn't hurt. Continuing with this rationale, we show the relationship between our framework and kernels in Fig. 1. The framework for our application consists of four independent components: IPv6, "fuzzy" archetypes, low-energy epistemologies, and the compelling unification of hash tables and checksums. This is an appropriate property of HOSTEL. the model for our application consists of four independent components: replicated technology, checksums, trainable communication, and suffix trees. See our previous technical report [31] for details.

V.1.

A well-tuned network setup holds the key to an useful evaluation method. We instrumented a software prototype on UC Berkeley's desktop machines to quantify the incoherence of knowledge-based cryptoanalysis. We struggled to amass the necessary Ethernet cards. We added 100 2kB USB keys to our underwater cluster. On a similar note, we removed some FPUs from our system. We tripled the median signal-to-noise ratio of our desktop machines. Further, we quadrupled the expected popularity of 2 bit architectures of our unstable cluster. In the end, we added 25Gb/s of Internet access to our human test subjects. When M. B. Kobayashi modified GNU/Hurd Version 9c, Service Pack 7's software architecture in 2001, he could not have anticipated the impact; our work here follows suit. We implemented our simulated annealing server in ANSI x86 assembly, augmented with mutually mutually randomized extensions. We implemented our the World Wide Web server in C++, augmented with mutually wireless extensions. Further, we implemented our Smalltalk server in Dylan, augmented with randomly computationally independently disjoint extensions. We made all of our software is available under a write-only license.

Fig. 1. The relationship between HOSTEL and the partition table

IV.

Implementation

V.2.

Our implementation of our application is client-server, adaptive, and signed. On a similar note, mathematicians have complete control over the hand-optimized compiler, which of course is necessary so that the foremost atomic algorithm for the understanding of write-back caches by Jackson and Johnson [32] follows a Zipf-like distribution. The virtual machine monitor and the virtual machine monitor must run with the same permissions. Overall, our method adds only modest overhead and complexity to previous ambimorphic approaches. Of course, this is not always the case.

V.

Hardware and Software Configuration

Experiments and Results

We have taken great pains to describe out evaluation strategy setup; now, the payoff, is to discuss our results. With these considerations in mind, we ran four novel experiments: (1) we deployed 65 Nintendo Gameboys across the Internet network, and tested our spreadsheets accordingly; (2) we dogfooded our algorithm on our own desktop machines, paying particular attention to effective tape drive throughput; (3) we asked (and answered) what would happen if opportunistically discrete active networks were used instead of interrupts; and (4) we measured Web server and Web server throughput on our network. All of these experiments completed without noticable performance bottlenecks or LAN congestion. Now for the climactic analysis of the first two experiments. The curve in Fig. 2 should look familiar; it is better known as h(n) = n. Similarly, of course, all sensitive data was anonymized during our courseware deployment [33]. The key to Figure 2 is closing the feedback loop; Fig.

Results

Analyzing a system as experimental as ours proved onerous. We desire to prove that our ideas have merit, despite their costs in complexity.



153


2 shows how HOSTEL's flash-memory speed does not converge otherwise. Shown in Fig. 3, all four experiments call attention to HOSTEL's expected response time [11]. Note that active networks have smoother complexity curves than do reprogrammed hierarchical databases. Second, note that Fig. 4 shows the average and not mean independent expected sampling rate. On a similar note, note that vacuum tubes have less discretized effective optical drive speed curves than do hacked SCSI disks.

Fig. 5. The 10th-percentile block size of our methodology, compared with the other frameworks

Lastly, we discuss all four experiments. Note the heavy tail on the CDF in Figure 2, exhibiting amplified average seek time. The results come from only 2 trial runs, and were not reproducible. Furthermore, error bars have been elided, since most of our data points fell outside of 78 standard deviations from observed means. Fig. 2. Note that energy grows as throughput decreases - a phenomenon worth studying in its own right

VI.

Conclusion

We also presented new distributed models. Our methodology for evaluating the simulation of active networks is particularly outdated. We concentrated our efforts on confirming that write-ahead logging and B-trees [16] are never incompatible. Of course, this is not always the case. In the end, we proposed an analysis of architecture (HOSTEL), which we used to prove that congestion control and wide-area networks can cooperate to overcome this question. In this paper we showed that superblocks and telephony [9], [34] are often incompatible. Our framework for controlling kernels is clearly outdated. HOSTEL has set a precedent for the analysis of compilers, and we expect that electrical engineers will refine our algorithm for years to come. Similarly, we also motivated an analysis of public-private key pairs. Next, HOSTEL might successfully request many superpages at once. We expect to see many system administrators move to deploying HOSTEL in the very near future.

Fig. 3. The mean response time of our application, as a function of interrupt rate

References [1]

[2]

[3]

[4] Fig. 4. The median time since 1935 of our system, compared with the other algorithms

[5]


V. Ramasubramanian,Evaluating the producer-consumer problem and context-free grammar using Amzel, Journal of Stable, Probabilistic Configurations, vol. 66, Nov 2010 ,pp. 41-50. J. Kubiatowicz, A. Perlis, a. Gupta, and E. Martinez, Decoupling Internet QoS from telephony in consistent hashing, IBM Research, Tech. Rep. 5604/20, Sept. 2007. J. Zheng, D. Knuth, and S. Cook, "Harnessing superblocks and Internet QoS using Verb," Journal of Optimal Methodologies, vol. 48, June .2009,pp. 49-52. R. Floyd, N. Wirth, and Z. Anderson, A case for Moore's Law, in Proceedings of FOCS, Aug, 2009. D. Sasaki and D. Harris, Towards the investigation of the partition table that made simulating and possibly improving Moore's Law a


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reality, in Proceedings of the Conference on Heterogeneous Modalities, Jan, 2000. Chella, A., Massimo Cossentino, Salvatore Gaglio, Agent-oriented software patterns for rapid and affordable robot programming, systems and software, vol.83 n.4,2010, pp. 557-573. R. Zhou, C. Papadimitriou, T. Leary, A. Einstein, and F. Wu, Decoupling online algorithms from the transistor in suffix trees, in Proceedings of PLDI, Aug, 2000. K. Iverson, A. Shamir, C. Jayanth, and Q. Ito, Investigating Byzantine fault tolerance using "smart" modalities, University of Northern South Dakota, Tech. Rep. 84/924, June 2000. M. R. Martin, The influence of concurrent modalities on hardware and architecture, in Proceedings of SIGMETRICS, July, 2003. N. Sato, ma yanchun, Decoupling the transistor from the memory bus in spreadsheets, Journal of Lossless, Interactive Information, vol. 35, Feb 2004, pp. 40-54. J. Martinez, On the investigation of replication, in Proceedings of the Workshop on Atomic, Linear-Time, Authenticated Methodologies, Jan, 2001. B. Watanabe, Decoupling simulated annealing from Byzantine fault tolerance in sensor networks, in Proceedings of FOCS, Apr, 2003. A. Turing, Simulating hash tables using concurrent theory, in Proceedings of the Symposium on Linear-Time Symmetries, July, 2005. B. Lampson, Investigating XML and kernels, Bayesian, Bayesian Algorithms, vol. 9, Apr 2005, pp. 73-83. K. Williams, A case for neural networks, in Proceedings of NDSS, Jan, 2001. D. Clark, Investigating semaphores and evolutionary programming with GRES, in Proceedings of WMSCI, Aug, 2003. R. Tarjan, K. Thompson, and I. Newton, Developing access points using wireless configurations, Amphibious, Introspective Information, vol. 350, May 2002, pp. 89-106. E. Clarke, The impact of wireless configurations on cryptoanalysis, Bayesian, Empathic Information, vol. 79, Apr 2004, pp. 76-88. V. Jacobson, A methodology for the understanding of the transistor, in Proceedings of PODC, Mar, 2004. ma yanchun, W. U. Ambarish, and B. Davis, Deconstructing object-oriented languages, Collaborative, Certifiable Communication, vol. 22, July 1998, pp. 74-80. ma yanchun, C. Taylor, and K. Thompson, The impact of wireless methodologies on stochastic cyberinformatics, Compact, Concurrent Information, vol. 442, Dec 2002, pp. 73-87. R. Milner and W. Brown, A construction of erasure coding, The Conference on Cacheable Modalities, May, 2009. J. Harris, Deconstructing expert systems, in Proceedings of MOBICOM, June, 1999. M. Thomas, X. Zhao, F. P. Kobayashi, R. Agarwal, V. Smith, and A. Yao, AtaxicRoc: Authenticated, efficient methodologies, Cacheable, Omniscient Configurations, vol. 28, Sept 2003, pp. 159-199. N. Taylor, C. A. R. Hoare, and R. Milner, The Ethernet considered harmful, in Proceedings of OSDI, Sept, 1990. M. O. Rabin and B. Moore, A construction of Smalltalk using SkeetAni, The Conference on Virtual, Relational, Cooperative Communication, Oct, 2004. S. Davis, ma yanchun, and E. Shastri, An analysis of hierarchical databases using Tilmus, NTT Technical Review, vol. 31, Sept 1995, pp. 83-100. H. Wu and C. K. Wilson, The impact of relational communication on machine learning, The Workshop on Real-Time, Event-Driven Models, May, 1977. V. Jacobson, O. Lee, R. Karp, and K. Zheng, Deconstructing spreadsheets, Extensible, Homogeneous Configurations, vol. 64, Nov 1993, pp. 151-193. K. Bhabha, Development of public-private key pairs, The Workshop on Symbiotic, Compact Modalities, Dec, 2005. A. Shamir, An emulation of B-Trees, in Proceedings of WMSCI, Apr, 2010. X. Wang, Compact, signed algorithms, in Proceedings of FOCS, Jan, 2001. K. Iverson, Y. Thompson, and K. D. Anderson, Deconstructing wide-area networks with IMAM, in Proceedings of NOSSDAV,


Mar, 2004. [34] Z. Miller, K. Iverson, N. Chandramouli, B. Kalyanaraman, U. Sato, J. Backus, T. Leary, M. O. Rabin, J. Smith, C. Jones, K. Iverson, and V. D. Johnson, Decoupling the World Wide Web from spreadsheets in Markov models, Distributed, Unstable Archetypes, vol. 98, June 2012, pp. 150-197. [35] N. Wirth, L. Harris, and J. Kubiatowicz, On the development of the lookaside buffer that would make emulating spreadsheets a real possibility, UT Austin, Tech. Rep. 763/9747, Mar. 2011.

Authors’ information Yanchun Ma received the B.Eng. degree from China University of Mining and Technology in 2002.Since 2002 he is an assistant on the Computer Science and Technology department in north china institute of science and technology.He is a Associate Professor.His research interests include areas of computer networks and network and communication security,intrusion detection. Cuirong Zhang Lecturer of North China Institute of Science and Technology. Dr. Zhang research interests include image/ video compression, wavelet transform, signal/image/video processing and digital communication systems.


155


Digital Library System in the Academic Libraries: it’s User Friendliness Mathews Stephen, V. S. Kunjumuhammed Abstract – Academic digital libraries emerged as a result of advances in computing and information systems technologies, and have been introduced in universities and to public. As a result, moving in parallel with current technology in learning and researching environment indeed offers uncountable advantages especially to students and academicians, as well as researchers. This is because a dramatic changes happen in learning environment through the use of digital library systems which are giving spectacular impact on these societies way of performing their study/research. This paper presents a survey on the benefits and problems of the academic digital libraries’ performance. Even though this paper does not broadly take into account all previous research in evaluating academic digital library system but at least it can be a guide in understanding the user benefits of the digital library system. Copyright © 2013 Praise Worthy Prize S.r.l. - All rights reserved.

Keywords: Digital Library System, Internet Protocol, Computing and Information Systems Technologies

The audience does not wait for the librarians take them in this new world of digital technology. Unlike campus libraries, the modern librarian has to make the transformation to the digital world under scrutiny of the user’s eye, while serving the parent body as well as the academic, and increasingly, the scholar. The balance of serving these important constituencies is one of the most difficult issues the traditional institution will face in the immediate future [4], [5]. From the digital technology perspective on the outside, the balance between serving the scholars who create knowledge and the broader needs of the user community and the social pressure forces the librarians, collectively, to consider the shape and form of comprehensive libraries of the future. Librarians must consider what is possible in the digital environment, how to provide services, and how to interact with other libraries within a nation and in the world [1], [10].

Nomenclature WWW FAQ DLS CD-ROM DVD-ROM I.P. Address

World Wide Web Frequently Asked users’ Questions Digital Library System Compact Disc, read-only-memory Digital Video Disk, read-only-memory Internet Protocol Address

I.

Introduction

In the past academic libraries were totally bound by their physical parameters[1]-[13]. Library users initiated the interactions by going to the library [3]. They physically walked around the library and searched or browsed for their information, or asked a librarian for help. Information Technology has changed the today’s environment of libraries in a big way with the current thrust on digital information. With the development of digital information and a knowledge society, libraries are changing their role from document provider to the information provided. The need of the hour is to provide authentic information in a split of second. Internet explosion covers the way for the same. The impact of information technology has led to a paperless society, digital libraries and virtual libraries. Technology has been making such an impact on different sectors of human activity which leads the present period as paperless society. Its impact on libraries and their services is not less. The concept of four walls library is fading off today at least to some extent even in developing countries [2],[11].

II.

Digital Library

Digital Libraries are digitally accessible organized collections of knowledge. Digital libraries are a set of electronic resources and associated technical capabilities for creating, searching and using information. In this sense, they are an extension and enhancement of information storage and retrieval systems that manipulate digital data in any medium (text, images, sounds; static or dynamic images) and exist in distributed networks. The content of digital libraries includes data, metadata that describes representation, creator, owner, reproduction rights, and metadata that consists of links or



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Mathews Stephen, V. S. Kunjumuhammed

relationships to other data or metadata, whether internal or external to the digital library [7]. Recent advances in technology which can assist in the conversion of print materials to digital formats now enable librarians to go well beyond access and make library resources that were previously available only in one physical location available to anyone via the World Wide Web [13]. The joint purchase of commercial databases and conversion of unique print collections to digital format can create a virtual library available to anyone, anywhere. Digital libraries offer such benefits as: equitable access; reduced barriers of distance; timeliness; shared resources and content delivery. Digital Libraries promise an exciting new service paradigm for the 21st century [1]. Creating true digital libraries, not just digital collections, will require librarians to work closely together to:  Create an open, distributed, publicly accessible resource that documents crucial information for users.  Establish a collaborative structure to co-ordinate and guide the implementation of the digital library.  Develop criteria and standards to guide the selection of materials for inclusion in the digital library.  Add value to digital resources.  Assist libraries, museums, archives, schools, government and non-government organizations, and other institutions in digitizing materials and managing digital library projects.  Showcase content and the rich resources held by our libraries and other repositories worldwide. II.1.

possibility can be realized only through digital library systems.  Support of many key-words and key-phrases by digital catalogues, and ability of the users to create interpellations, resulting in easier and more flexible information retrieval.  Responding to new users’ demands for centralized services and additional services for support, training and guidance.  Ability to access selective sources of information and online research.  Easier information retrieval and direct information acquisition with the capability of remote access through its supply in electronic form and its distribution through the Internet. Creation of “course packs”: a form of educational material adapted to the special needs and demands of the course and the student [8], [9], [1]. II.3.

The main services offered by these libraries should be: 1. The distribution of digital or digitized collections of “grey” bibliography (as it has already been mentioned, by this term we are referring to all unpublished bibliographies consisting of postgraduate and doctoral theses, lecture notes, internal (technical) reports, due for delivery research work etc.). 2. Information filtering and suggestion of information sources, so that users are guided to the information of their interest in the easiest and fastest possible way. 3. Active participation in shaping information literacy. By the term “information literacy”, we are referring to the ability to recognize the need of locating, evaluating and efficiently using information. 4. Participation in shaping study programs, by efficiently supporting the content and the teaching methods for courses (e.g. locating material and sources of information). 5. Distribution of educational material in electronic form. 6. Separate and independent access to data, by developing advanced systems for seeking and exploring the area of digital information (expert systems), thus facilitating self-instruction, remote education and information search in cyberspace. 7. Development of methods to authenticate users’ I.D. (recognition of their I.P. address, use of access code and others) in order to ensure their access to the desired information sources. 8. The creation of a user interface environment between the library and its users as well as between the library and the information sources. More specifically, in the case of a Digital Library, the user-library interface environment is its website. 9. The implementation of digital systems to answer Frequently Asked users’ Questions (FAQ) aiming to resolve the problems which users encounter during information retrieval.

Objectives of Digital Library in Academic Library

The main objectives of a digital library are:  To collect, store, organize and disseminate information in digital form.  To save the time the users as well as Library staff.  To provide accurate and right information at the right time.  To save space.  To provide information to a large number of users at a time.  To reduce human effort and cost involved in different library activities.  To preserve valuable and rare documents. II.2.

Services Offered by the Academic Digital Library

Advantages of Digital Academic Libraries

The advantages of digital library in academic are following:  Ability to utilize the potential of digital information and to support contact with their users, even if great distances separate them. For example, each one of us can access an ordinary library in New York or in Hong Kong, expecting to find the desirable information as fast as in a conventional library. This



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10. The development of portals and subject gateways aiming to cover the needs for on-time and valid information through the supply of high quality information and the link of new technology with the educational process (subject gateways - in the same way as with portals - constitute an entrance point to the Internet. Their difference lies in the fact that while portals supply unedited information, subject gateways simply notify as to where one can locate the information. Thus, information is eventually retrieved after seeking at the website suggested by the subject gateway) [6], [12].

publications, which are found in electronic or digital media. The electronic documents are made available either on CD-ROMs or on the Internet. The electronic documents, which are available on CD-ROM, are referred as offline documents while those on the Internet are known as online documents. The digital resources in an academic library may be any one of the following: 1. E-books (including e-reference sources). 2. E-journals. 3. E-theses /E-research reports. 4. E-newspapers.

III. Literature Review II.4.

Types of Digital Information Resources

Anne Adams, and Ann Blandford [8] studied the social and organizational impacts of digital libraries across different disciplines (Humanities, Computing, and Business) of a London university. In-depth interviews and focus groups with 25 lecturers and librarians were conducted, and analysed using the grounded theory method. This research paper identified that webaccessible digital library (DL) are identified as changing the roles and working patterns of academic staff (i.e. lecturers, librarians and computer support staff). However, poor accessibility due to inappropriate implementation strategies, access mechanisms, searching support and DL usability reduces the use of these resources. Consequently, web and personal collections without guarantees of quality are widely used as an accessible alternative. H. M. Chidananda Swamy [1] focuses the need for the practice of digitization and digitized information resources and services in academic libraries to create a digital library service environment. Discusses the objectives and services of digital library. It concludes that in view of the effectiveness of digitized information resources and services, urges that the academic libraries should go in for digitized information resources and services for their survival in the future. The paper has also suggested that the success and survival of academic libraries in the future will depend on their role to satisfy the ever-increasing information needs of users. Razilan A. Kadir et al. [2] presented a survey of current criteria for evaluating academic digital libraries’ performance. The goal is to discuss criteria being applied so far for academic digital libraries evaluation in the context of user-centered design. This paper also discussed academic digital libraries emerged as a result of advances in computing and information systems technologies, and had been introduced in universities and to public. As results, moving in parallel with current technology in learning and researching environment indeed offers myriad of advantages especially to students and academicians, as well as researchers. This is due to dramatic changes in learning environment through the use of digital library systems which giving spectacular impact on these societies’ way

Digital refers to any resource, which is in digitized form, i.e., which can be read and scanned by the means of electronic media. Like conventional forms digitized resources do not require separate space in a library, as this can be stored in a computer locally and remotely. Digital resources include a wide range of material such as: 1. The collection in which complete contents of documents are created or converted into machinereadable form for online access. 2. Scanned images, images of photographic or printed text, etc. 3. Scientific data sets such as protein sequences. 4. Online databases and CD-ROM information products, particularly those with multimedia and interactive video components. 5. Computer storage devices such as optical disk, jukeboxes, CD-ROM/DVD-ROM. 6. Databases accessible through the Internet and other networks. 7. Digital audio, video clips or full length movies. II.5.

Digital Collections and Academic Libraries

The successes of digital library depend largely on the nature, content and quality of its collections. The basic requirements in creating a digital library will be the building of digital collections. The digital collections of information include various resources such as electronic journals, books, full-text articles, CD-ROM databases, etc. The benefit of information collections in digital form for preservation, access and managing large quantities of information have been recognized by both library professional as well as users. An academic library collection generally consists of the following: 1. Books (including reference sources). 2. Journals. 3. Theses and Reports. 4. Newspapers and Magazines. 5. In some cases manuscripts. Today, digital resources have become a major field in the world literature. Electronic publishing are those



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of performing their study/research. Hong Xie [7] studied to investigate the users’ use, their criteria and their evaluation of the two selected digital libraries. Nineteen subjects were recruited to participate in the study. They were instructed to keep a diary for their use of the two digital libraries, rate the importance of digital library evaluation criteria, and evaluate the two digital libraries by applying their perceived important criteria. The results show patterns of users’ use of digital libraries, their perceived important evaluation criteria, and the positive and negative aspects of digital libraries. Judy Jeng [9] developed and evaluated methods and instruments for assessing the usability of digital libraries. It discusses the dimensions of usability, what methods have been applied in evaluating usability of digital libraries, their applicability, and criteria. It is found in the study that there exists an interlocking relationship among effectiveness, efficiency, and satisfaction. It provides operational criteria for effectiveness, efficiency, satisfaction, and learns ability.

IV.

platforms and systems. IV.1.2.

An academic library has to provide library users with dynamic equipment, facilities, resources and services to support their learning activities, which cover assignments, presentations, projects, research papers, reports, etc. IV.1.3.

IV.1.4.

Publication Centre

An academic library shall provide library users with computer hardware and software, audio-video equipment and other supporting facilities and peripheral devices to create, design, develop, integrate, publish, and upgrade their various multimedia presentations, projects, reports, web sites, blogs, and so on.

Research Methodology

IV.1.5.

Distance Learners Program

Some of the university provides the distance learning opportunity to their students. The students who study or conduct research away from the physical campus can use the library facility and resources as required. The following services can be offered through digital libraries.  Electronic document delivery of scanned items from print collections.  Electronic document delivery of articles requested through inter-library loan.  Electronic book reservation services.  Digital reference service such as, “ask the librarian”. With the help of this service, a user can ask a question (through the net) to the librarian during office hours and can get answers. IV.1.6.

Improved Searching for the User

Digital library facilitates improved access to information by providing various sophisticated search and retrieval facility. There have been significant improvements in the end user search facilities provided by electronic database search services and web search engines. Research is a vital part to serve any academic library. Most of the university libraries do not provide much search facility for the researchers and the traditional search techniques are time consuming. So, if the university library can provide quicker and

Roles of Academic Digital Library

Research found the following roles of academic digital library are indicated in the next subsections: IV.1.1.

Training Centre

An academic library shall provide best supporting and training facilities to faculty and instructors for designing, developing, integrating and implementation of various teaching courses, programmes, workshops including support for distance learning programmes.

Focus groups and in-depth interviews were used to gather data from different academics and librarians from 4 different campuses within India. The final respondent was from a key managerial role within library services. The academics were selected from all levels within their department (i.e. lecturer, Senior Lecturer, Reader, Professor). There was a representative sample from each department of teaching and non-teaching staff.ù Of the 13 librarians interviewed, the majority were subject librarians with authorization to acquire and support digital resources for their discipline. Four issues guided the focus of the questions:  Perceptions of the role of digital library within the academic setting and information requirements.  Perceptions of how information is currently accessed, and how these processes accommodate or inhibit current working practices.  The impact of organizational social structures and patterns of interaction on information resource awareness, acceptance and usage.  Technology perceptions (specifically of DLS) and how these affect other issues already identified. IV.1.

Learning Centre

Gateways to Information

An academic library has to function as a central gateway for library users to access, locate, transform, and utilize information resources in a variety of printed and electronic formats via applications, databases, networks, Copyright © 2013 Praise Worthy Prize S.r.l. - All rights reserved


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improved search options to the users, the research work will be accelerated. IV.1.7.

digitalized resources, network access and distribution management via network technology.

Multiple Users at a Time without Purchasing Multiple Copies

IV.2.3.

It is one of the real-time electronic consulting and reference offered by academic libraries via specific software running on the Internet platform. It is virtually instantaneous communication between two or more people using textual format, providing “real time reference” services, where patrons can synchronously communicate with librarians much as they would in a face to face reference context. The software often allows co-browsing, file sharing, screen capturing and data sharing and mining of previous transcripts. Libraries are already offering live reference service using 24 × 7 × 365 in a collaborative fashion.

The digital collections through a digital library can be used by many users at the same time without purchasing their multiple copies. This is a great advantage for any library users because traditional library resources cannot be used in this way. IV.1.8.

Library Cooperation

The digital library facility provides improved facility for information sharing among different libraries in any network. A group of university libraries can come under an agreement and permit access to their subscribed ebooks or e-journals to the other members of the group. In this way, they can save a lot of money and get the benefit of the library cooperation. IV.2.

IV.2.4.

To harness the technological paradigms some new services should be focused upon such as the following subsections. Library 2.0

The term Library 2.0, first coined by Michael Casey in 2006 on his blog Library Crunch, refers to a number of social and technological changes that are having an impact upon libraries, its staff and their clientele, and how they could interact. It is a model for a modernized form of library service that reflects a transition within the library world in the way services are delivered to users. The focus is on user-centered change and participation in the creation of content and community. IV.2.2.

Information Commons

An Information commons is an innovative and evolving collaborative academic library service model built on a variety of networked interactive academic learning platforms. The primary function of an academic library information commons is to integrate existing information resources, services, instructions and other public service programmes in the library into one consistent dynamic, interactive and scalable student centered interactive academic learning environment.

New Services for Technological Paradigms

IV.2.1.

Instant Messaging Reference Service

IV.2.5.

Wiki

A Wiki is a website that uses Wiki software, allowing the easy creation and editing of any number of interlinked web pages, using a simplified markup language. Wikis are often used to create collaborative websites, to power community websites and for note making. For example, the collaborative encyclopedia, Wikipedia is one of the best-known Wikis that has broken down the golden rules of library science, i.e. content validation and authentication of information. Wikis are also used in business to provide affordable and effective Intranets and for knowledge management. Libraries can use Wikis as a communication tool to enable social interaction among librarians and patrons. Users can share information, ask and answer questions, and librarians can do the same within a Wiki. Moreover, a record of these transactions can be achieved for perpetuity. Transcripts of such questionanswer sessions would serve as resources for the library to provide as references. A Wiki like platform created for the librarians to work collaboratively and concurrently on providing answers to the user enquiries. This allows any staff to tap on the collective wisdom of the communities of subject librarians and provide quality answers to their queries.

Library Digitization

Library digitization is the process of utilizing computers, databases, multimedia equipment, networks, video equipment and web technologies to electronically collect, classify, copy, compress, scan, store and transform conventional library information resources. Library digitization is different from a digital library as it focuses on the process of making diverse library information resources electronically available, while a digital library is a platform for accessing, collecting, managing, searching and storing distributed digitized information resources over the Internet and World Wide Web (www). Thus, to provide access to these digitized library collections, academic libraries need to set up and implement digital library projects which provide



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IV.2.6.

Blog

a digital library.

A blog is a website, usually maintained by an individual, with regular entries of commentary, descriptions of events, or other material such as graphics or video. Blogs provide control of an individual or group of individuals for publishing contents or making commentary on it. Technologically, blogs are easier to use, platform-independent and accessible online over the Internet. Blogs are increasingly used by libraries as promotional, alerting and marketing tools; providing a useful method of promoting new services, alerting users to changes and offering advice and support. In library blogs typical posting include information about fresh arrivals, e-databases, news and services rendered can be flashed for wider effects. IV.3.

IV.3.4.

Access to the information in digital libraries is generally less controlled than it is in physical collections. Though the copyright is a major issue for printed resources in India as well. IV.3.5.

IV.3.6.

There are some problems of digitization of academic library. These are indicated in the the following subsections.

The technology required to provide digital library services continues to change rapidly as researchers and commercial vendors expand the kinds of content and access services that might be included. As the technology changes and improves, an institution’s vision and requirements for a digital library evolve accordingly. The software to support these services is complex and dynamic. It is difficult for an average academic library, with limited technical resource to manage the development and growth of a practical, real-world, production digital library that meets its unique requirements.

V.

Conclusion

In the world of Digital Libraries, Academic Libraries play an extraordinary role in educating and empowering citizens. It no longer involves merely learning the use of various retrieval tools, but mainly developing critical thought and the ability to evaluate the information sources themselves, aiming at creating real researchers rather than operators. They help individuals and communities to become more knowledgeable, aware and imaginative. At the heart of the drive towards global sharing, libraries transcend economic and social disparities. Institutional libraries thus play a vital role in crossing the borders, the key to opening all gateways to knowledge. A true hub, libraries seamlessly incorporate information technology. The Library should constantly collaborate with the Institute, so as to readily respond to any new challenges should they arise and to comply with any new planning. So libraries will eventually manage to become not only collectors of the information but its navigators as well and will constitute the heart of documentation and information. Consequently, far from vanishing in the future they will continue operating as they used to in the past, only now there will be an obvious difference: the existence of digital services as a dynamic extension; which will result in libraries with a more significant role in society.

Lack of Sufficient Funding

Building and managing digital libraries involves huge financial capitals. The budget allocation of most of the university libraries is not sufficient for the digital library research and development. Hundreds of millions of dollars have already been spent on digital library research and development activities throughout the world. Digitizing the existing library materials also involves a huge expenditure. IV.3.3.

Illegal and Harmful Materials

Web information is a big portion of any digital library and some material on the web is illegal and harmful and clearly inappropriate for public presentation. Violence and pornography are two major issues in this aspect. It is difficult for our academic libraries to prevent the usages of those materials.

Lack of Technical Knowledge and Support

IV.3.2.

Organization of Collection

Digital libraries are organized collections of information. Downloading information from the web and organizing them into focus collections and making the material more useful to others is a major application area of digital libraries.

Problems of Digitization of Academic Library

IV.3.1.

Copyright Issue

Software Development

Large academic libraries may be able to develop their own software, in collaboration with university researchers and IT departments. But many libraries do not have the resources to build a complete solution, and a comprehensive commercial solution is often too costly. Moreover, due to the various and expanding content and services, no single product can meet all the requirements of even a basic function of

References [1]


H M Chidananda Swamy, “Digital Collections in Academic Libraries”, In Proceeding of 3rd Convention PLANNER -2005,


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[2]

[3]

[4]

[5]

[6]

[7]

[8]

[9]

[10]

[11]

[12]

[13]

Assam Univ., Silchar, 10-11 Nov., pp. 89-93, 2005. Razilan A. Kadir, Wan A. K.W. Dollah, Fatimah A. Saaid, and Diljit S., “Academic Digital Library’s Evaluation Criteria: UserCentered Approach”, International Journal of Social and Human Sciences, Vol. 3, pp. 744-749, 2009. Pauline Adeniran, “User satisfaction with academic libraries services: Academic staff and students perspectives”, International Journal of Library and Information Science Vol. 3, No. 10, pp. 209-216, November 2011. Yoo-Seong Song, “Designing library services based on user needs: new opportunities to re-position the library”, 75th IFLA General Conference and Assembly, 2009. Patience L. Simmonds and Syed Saad Andaleeband, “Usage of Academic Libraries: The Role of Service Quality, Resources, and User Characteristics”, Library Trends, Vol. 49, No. 4, pp. 626634, 2001. Abdul Mannan Khan, “Users’ perceptions of library effectiveness: A comparative users’ evaluation of central libraries of AMU, BHU, ALU and BBRAU”, The International Information & Library Review, Vol. 44, pp. 72-85, 2012. Hong Xie, “Users’ Evaluation of Digital Libraries (DLs): Their uses, their criteria, and their assessment”, Information Processing & Management, Vol. 44, No. 3, pp. 1346–1373, May 2008. Anne Adams, and Ann Blandford, “Digital libraries in academia: challenges and changes”, In Proceedings of 5th International Conference on Asian Digital Libraries, ICADL 2002 Singapore, December 11–14, Vol. 2555, pp. 392-403, 2002. Judy Jeng, “Usability Assessment of Academic Digital Libraries: Effectiveness, Efficiency, Satisfaction, and Learnability”, Libri, Vol. 55, pp. 96–121, 2005. Syed Saad Andaleeb and Patience L. Simmonds, “Explaining User Satisfaction with Academic Libraries: Strategic Implications”, College & Research Libraries, Vol. 59, No. 2, pp. 156-167, March 1998. G.G. Chowdhury, N. Meyyappan and Schubert Foo, “Design and evaluation of a task-based digital library for the academic community”, Journal of Documentation, Vol. 60, No. 4, pp. 449475, 2004. John Carlo Bertot, “Assessing Digital Library Services: Approaches, Issues, and Considerations”, International Symposium on Digital Libraries and Knowledge Communities in Networked Information Society, Vol. 10, No. 9, 2004. Ruben Heradio, David Fernandez-Amoros, Javier Cabrerizo, and Enrique Herrera Viedma, “User–Centered Evaluation of Digital Libraries: a Literature Review”, Journal of Information Science.

Authors’ information Mathews Stephen obtainted his bachelors degree in Library and Information science from MG University, Kottayam, Kerala. Then his Masters Degree in Library and information science Annamalai University, Chithambaram, Tamilnadu and PhD in Library and information science from LN Mithila University, Darbhanga, 2008 Registration majoring digital library services and user studies under the guidelines and supervision of Dr. Arunkumar Dutta. He has also done MA, B.Ed. in History. V. S. Kunjumuhammed, obtainted his bachelors degree in Library and Information science from Jabalpur University, Madyapradesh. Then MLIS from IGNOU and MPhil from Alagappa University, Tamilnadu and now seeking PhD in Library and information science from LN Mithila University, Darbhanga on Digital Library Development. He has also done MA in Political Science. Now he is working as Asst Librarian in Fisheries Univrsity, Panangad, Ernakulam.



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Engineering Design and Validation of an Innovative Bionic CD Rack Carlos A. M. Versos1, Denis A. Coelho2 Abstract – This paper presents the engineering design analysis, of both a computational and analytical nature, that was performed in the development of a new bionic product, using an industrial engineering design approach. In the product engineering example, concerning an innovative CD rack, based on the principle of the spider web, elastic cable force creation by elongation is designed and validated, and the structure displacement and stress fields are simulated numerically. Copyright © 2013 Praise Worthy Prize S.r.l. - All rights reserved.

Keywords: Product Design, Industrial Design Engineering, Computational Analysis

Design methodologies are essential tools in the design process which provide pathways, goals and technical guidelines for the development of products [1]-[10]. Bionic design, a design methodology capable of enriching projects with gains in efficiency, aesthetics and sustainability and with a wide margin for improvement and with a whole world where inspiration can be reaped from, will certainly bring benefits to designers in the future development of their concepts and their research. As in Nature - an environment in constant adaptation and renewal, where species evolve systematically and only the strongest survive and become adapted to the environment - the planning and development of a product must also ensure an iterative nature of the process and constant reassessment of the design process [10]. Several attempts to mimic biological systems behavior within new technology development have been reported (e.g. [5], [3], [6]). Previous work by Versos and Coelho [8], [9], [1] and by Coelho and Versos [2], [7] analyzed

and compared several methods for guiding bionic design that were available in literature. These analyses, in addition to providing the basis of study for the development of the methodology that is aimed in this chapter, can support designers in the selection process of the bionic design method most appropriate to the problem at hand. Previous work emphasized the necessity of integrating validation activities in bionic design processes. The development and testing of improved methods that provide greater support to designers in the pursuit of activities leading to bionic solutions was the overarching of Versos and Coelho [10]. The need for evaluation and validation during the development of bionic design projects enabling to measure product success in meeting efficiency targets and proposed requirements, was one of the evident missing features of previously existing methodologies for bionic design and which were met with the proposed methodology presented by Versos and Coelho [10]. Besides these aspects, the proposed method was also intended to support an iterative approach in conducting design projects in order to achieve optimal results and correct the detected deviations meeting the proposed objectives and needs. Implementation of the proposed method in practice [10] aimed its validation and also confirmation of the gains introduced in projects that follow the methodology for the process of design with inspiration taken from Nature. This is explicit from the results obtained from the project, which in addition to validate the method, serves as a complement to present the method. In this paper, the engineering design aspects of the development of two bionic products are presented. These were developed by Versos [1], [7] as part of his Master of Science Thesis in Industrial Design Engineering, supervised by the first author. In the product engineering example, concerning an innovative CD rack, based on the principle of the spider web, elastic cable force creation by elongation is designed and validated, and the



Nomenclature CAD CD DVD PLA UV m g E l K A r δ FH FV P M

Computer Aided Design Compact Disk Digital Video Disk Polylactic acid Ultraviolet radiation Mass Gravitational acceleration Young’s modulus Length Elastic Stiffness Surface area Radius Elongation Horizontal component of force Vertical component of force Weight Torque

I.

Introduction

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Carlos A. M. Versos, Denis A. Coelho

structure displacement and stress fields are simulated numerically, in order to validate the achievement of design requirements set forth at the beginning of the design endeavor.

II.

for use, resorting to renewable and biodegradable materials, which were selected from literature. The material selected for the production of structures and base of the CD rack is a bio-polymer composite biodegradable PLA (polylactic acid) derived from renewable resources, as corn starch or cane-sugar, is Ingeo Biopolymer 3251, produced by NatureWorks (a pioneer in the production and marketing of polymers derived from annually renewable sources). The selection of this material was due to specific properties and resulting characteristics of the biopolymer, which is suitable for applications in injection molds, and is suitable for thin walls (reduced thicknesses) due to the high flow ability of the resin. The material is opaque but it is also suitable for applications that require high gloss, UV resistance and rigidity. This material shows other characteristics appropriate to the concept of the project, such as its resistance to liquids. For the production of the elastic strands, the material selected is a thermoplastic elastomer made from natural rubber and joining chitosan (35 CSNR 65). Thermoplastic elastomers show the properties of rubber to ease the processing of thermoplastics [4]. Chitosan as a polysaccharide of natural origin (obtained from quitine, one of the most abundant natural polymers) has characteristics such as biodegradability, good mechanical strength, biocompatibility and has antimicrobial properties. According to Rao and Johns [4], natural rubber is characterized by good elastic properties, good resilience and damping behavior. However, because of its chemical behavior it shows poor processing, hence the connection with the chitosan will improve this feature in the material, also increasing the modulus of elasticity of the material.

An Innovative Bionic CD Rack

A system for storing CDs and DVDs in their covers structured by elastic threads was delineated, allowing the grasping of objects, in an attempt to dematerialize the archetype of ordinary shelves to result in a lighter solution, both visually and physically. The system of elastic threads (warp) developed is visible in Fig. 1 and was disposed vertically - for the purpose of guiding the objects in a fixed position to organize the storage and readability of the covers’ spines - and arranged horizontally and obliquely - for the purposes of gripping objects and for spatial organization.

Fig. 1. Arrangement of elastic threads of the shelving systems.The elastic threads are laid with pre-tensioning in holes in the structure itself, prepared for easy manual assembly or replacement of the elastics if required

A "web" of elastic threads was used both in front and at the rear of structure in order to ensure the fixing of the objects preventing them from falling. The structure of this solution was purposefully designed with a slope such as the positioning of the elastic threads was both horizontal and oblique, so as to facilitate the reading of the spines of the objects to be placed in the system. The end result of this concept can be seen in Fig. 2.

II.2.

In order to optimize the properties of the shape and geometry of the elements of the bionic CD rack, calculations were performed for the elastic tension forces of the horizontal or approximately horizontal and the vertical elastics, taking into account the properties of the materials selected. The diameter of the elastomers and the elongation of the initial stretch (assuming for both the differentiation between vertical and horizontal elastics) leading to the pre-stress concerned were considered as variables to define the design sought. The maximum vertical load to be borne by the horizontal elastics, was also determined in order to allow and make the simulation test activities for the validation of requirements, more complete and accurate. Dimensions of the spine of a CD cover = 10 × 124 [mm]. Dimensions of the area for storage of CD covers = 1080 × 300 [mm]. Total number of CDs supported = 261. Bulk CD single mass = 150 gr .

Fig. 2. Representing the final appearance of the bionic CD tower

II.1.

Iterative Design of the Pre-Tension of the Elastomers

Materials Used in the Product Concept

Given the requirement of reducing the environmental impact of the product, natural materials where intended



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Weight per CD = m × g = 0.150 × 9.81 m/s2 = 1.4715 N. Maximum load of CDs = 1.4715 × 261 = 384 N.

initial strain of 75%, having a margin of about 40% to endure load, but with a modulus of elasticity much higher than it would be had there been no initial deformation. Since in this material the modulus of elasticity increases with the strain, and to this material as the breakdown stress is 3.37 MPa, the filaments of 3mm diameter will only breakdown if supporting a load equal to this stress multiplied by the area: 7.068 × 3.37 = 23.8 N. Thus, there remains about 7 N (23-16 = 7 N) of capability to support elastic forces in each elastic cable. The additional deformation for this addition of 7 N corresponds to about 40% of the initial length, i.e. about 80 mm, considering the gap of 363 mm. For calculation of the pre-tensioning forces of the vertical elastics the following iterations were performed:

Given that the product has 2 × 20 horizontal elastics, the vertical load supported by each of the horizontal elastics is then 9,6 N. These vertical loads are applied in the supports of the horizontal threads considering equitable distribution of the value to be applied on each side. Thus, one considers a load applied in the left and right end of each thread of 4,8 N corresponding to the portion of the load caused by the group of CDs that the thread supports. The following calculations are aimed at reaching the value of necessary pre-tensioning of the horizontal elastic threads: For an initial strain of 75% of the initial length Diameter (horizontal threads) = 3 mm Length with 75% elongation = 36,3 cm = 0,363 m Material: 3565 CsNr – Young’s modulus (E) = 3,03 MPa (75% elongation) Failure elongation = 122,21% Failure stress = 3,37 MPa

For a pre-deformation of 75% of the initial length Diameter (Elastics) = 3 mm Length with elongation of 75% (bionic tower 1) = 125.5 cm = 1.255 m Length with elongation of 75% (Bionic Tower 2) = 107cm = 1.07 m

Initial length (l) = 0,363/1,75=0,2075m l Elastic Stiffness (K) = EA

A    r 2 m



A    1.5  10

K 3 2



Material: 3565 CSNR - Young's modulus (E) = 3.03 MPa (elongation 75%)

0.2075

3.03  106  7.068  106 K  9.89  103 m/N

l  initial length  

1.255  0.717m 1.75

6

A  7.068  10 m 2 Elongation (δ) = (elongated) l - (initial) l   0.363  0.2075  0.1555m  (pre-stressing) Force  F   K FH 

Elastic Stiffness  K  

1 EA

A    r 2 m



A    1.5  103

0.1555

 15.72N 9.89  103 Horizontal pre-stressing force in each extremity of the horizontal thread = 15.72 N



2

A  7.068  106 m 2 K

For a thread horizontal diameter of 3 mm, an initial length of 207.5 mm is sufficient taking into account the mechanical properties of the selected material (CSNR 3565), specially its modulus of elasticity, a 75% elongation is high (3.03 MPa) close to the failure stress. There is still a margin of 47% of the initial length at failure. Given the horizontal load values obtained (15.72 N) and the available margin to stretch, it was not considered necessary to perform a new iteration. Thus, to occupy the width of the tower from one side to the other, which has a dimension of 363 mm on average, each elastic thread must be mounted with an

0.717 6

3.03  10  7.068  106

K  33.5  103 m/N Elongation (δ) = l(elongated) – l (initial)

  1.255  0.717  0.538m Pre-stressing Force  F  


 K


165


FV 

Fig. 3 demonstrates the versatility of storage boxes of CDs, DVDs or books allowed by the elastic properties, the orientation and spacing of the vertical and horizontal wires that make up the system of the web. The first diagram shows the possibility of image storage boxes of CDs and DVDs in boxes horizontal rows separated, for distinction of both digital media. The arrangement of the boxes of two brackets can also be mixed by placing boxes or CDs such as DVDs in the same horizontal row as a second possibility image storage exemplified. The elasticity of the wire also allows the storage of other objects with slightly different dimensions, such as books, visible storage scheme in the third image, never losing the parallel and vertical orientation of objects, regardless of the location where they are. A demonstration of the strength of the structures of the towers for maximum storage through a tool for simulation and analysis of resistance testing efforts (COSMOSXpress, provided by SolidWorks software, version 2008) was also developed in the validation of this requirement. For this finite element analysis (FEA), an advanced frame model was used with the loads made by the elastic cables at full capacity of the rack, placed in all the holes for the placement of the two ends of the elastic strands. At the location of the holes for the horizontal cables (or nearly horizontal) forces were inserted in the model based on the previously calculated values of the pre-tension exerted by the stretched wire (15.72 N) and the maximum load to be borne by each CD yarn (4.5 N). With regard to where holes are placed to secure the vertical elastic threads, a vertical force of 4.34 N in each hole meant for securing the pre-tensioned yarns was inserted. Thus, in accordance with the material selected to construct the frame of the bionic tower (Ingeo Biopolymer 3251D), the following results were obtained, shown on Fig. 4. As regards the distribution of the tension forces resulting from applied loads in the model, control up through Fig. 26, the Von Mises equivalent stress to the area of greatest accumulated tension of 29 MPa.

0.538 33.5  10

3

FV  16.06 N The forces for pre-tensioning the elasticized vertical cables for the bionic tower, calculated taking into account an elongation of 75% and 3 mm diameter have been found excessive and can cause weaknesses from a structural point of view when multiplied by the existing number of elastic cables. Thus, we proceeded to change the parameter of the initial elongated length of the stretch cables (from 75% to 50%) and the force of pre-stress resulting from the vertical elastic cables was calculated again. The parameter change of initial elongation from 75% to 50% resulted in significant reduction of the tensile strength value of elastic vertical (9.86 N in the vertical elastics). However, in order to optimize this value appropriately and more satisfactorily and, taking into account the mechanical properties of the material selected for manufacturing the structure of the towers, the vertical elastics diameter parameter was changed from 3 mm to 2 mm and calculations were remade. After 3 iterations (1st iteration - stretching 75%, diameter 3mm: FV ≈ 16 N; 2nd iteration - stretching 50%, diameter 3mm: FV ≈ 10 N, 3rd iteration - stretching 50%, diameter 2mm: FV ≈ 4 N) the parameters of elongation and diameter considered suitable to generate a vertical force on each vertical elastic that are considerable acceptable from a structural point of view were met. However, the computational simulation provided the validation test of this choice of parameters. This iterative analytical process reduced the number of iterations of the computer simulation and still enabled the designer to be in a position of control over the design parameters of the object. II.3.

Validation of the Satisfaction of the Requirement of Storage with Versatility

In order to demonstrate the satisfaction of requirements, tests were elaborated in order to carry out the analysis of the solutions created. Thus, the requirement that relates to the versatility of storage with boxes of CDs, DVDs or books (1) elaborated a demonstration illustrating the versatility possible through 3D models obtained by modeling performed.

Fig. 4. Results of the distribution of von Mises equivalent stress under the loads applied

Fig. 3. Representation of dynamic storage possibilities of objects in the bionic CD tower



166


Taking into account the threshold failure stress of the bio-elastic polymer selected (48 MPa) the safety factor for the maximum load test in an extreme situation is: Safety factor=

48  1.66 29

Fig. 5 represents the distribution of the displacement in the frame of the tower resulting in the same scenario considered in the previous analysis. As can be seen in Fig. 5 it is the upper portion of the frame that undergoes larger displacements, with a maximum of about 8 cm. This value is justified by the elastic properties of the bio-polymer used, and the excessive load the model was submitted to in this analysis. Given this maximum displacement observed, and the safety factor that was calculated, leads to suggest that the bionic tower, before an extreme situation, is resistant to the conditions it is subjected to without compromising material properties. A structural validation using the finite element method was conducted for the bionic tower. The FEM analysis carried to the tower bionic 2 resulted in a safety factor of 1.66.

Fig. 6. Calculation of Maximum lateral disturbance for stability for a conventional CD shelf

Data: Mass = 11,049 kg, Centre of mass [cm], X = 20, Y = 10,70, Z = 56,09, Maximum capacity = 216 CDs, Medium capacity = 108 CDs, Mass of 1 CD = 0.075 kg. Calculation: F = Maximum lateral disturbance for stability P = Weight of the tower + Weight of the maximum CD capacity For maximum capacity: For medium capacity:

Fig. 5. Results of the displacement distribution relative to the base and considering the applied loads

II.4.

Validation of the Satisfaction of the Requirement of Greater Stability Facing a Dynamic Disturbance

11.049kg+  P    9.81  +16.2kg 

P  11.049kg +8.1kg 

P  267.31N

P  187.85 N

Mf  Mp

Mf  Mp

1.07  F  0.2  267.31N

The requirement of greater stability against dynamics disturbance in the face of conventional solution motivated calculation and analysis of disturbance threshold values (using a vector mechanical analysis) for a conventional CD shelf design using CAD solid modeling, and for the model resulting from bionic inspiration. In this analysis, limit values of disturbance were calculated for lateral stability (deemed more relevant due to the backrest of the shelves against the wall) and taking into account the maximum load capacity and the average load capacity of the designs.

0.2  267.31 1.07  49.96 N F 

1.07  F  0.2  187.85 N 0.2  187.85 1.07  35.11N F 

Table I summarizes the results obtained for both designs (conventional and bionic). The results, summarized in Table I, point to similar tolerance and resistance to lateral disturbance by both solutions. The closeness of the values of maximum disturbance to the lateral stability of the conventional



167


tower and the bionic tower (the values of the latter being slightly lower than the values of the first) is justified by the fact that the bionic model is lightweight, compared to the conventional solution. TABLE I COMPARISON OF RESULTS FOR CONVENTIONAL AND BIONIC SOLUTION

P  238.76 N

P  142.37 N

Mf  Mp

Mf  Mp

1.30  F  0.27  238.76 N

1.30  F  0.27  142.37 N

0.27  238.76 1.30  49.59 N

0.27  142.37 1.30  29.57 N

F 

Maximum disturbance for lateral stability For maximum capacity For medium capacity

Conventional solution

Bionic solution

49,96 N 35,11 N

49,59 N 29,57 N

F 

The closeness of the values of maximum disturbance to the lateral stability of the conventional tower and the bionic tower (the values of the latter being slightly lower than the values of the first) is justified by the fact that the bionic model is lightweight, compared to the conventional solution. II.5.

Validation of the Satisfaction of the Requirement of Improved Grasping of Held Objects

As regards the requirement of improved grasping of the major objects arranged compared to the conventional solution, the validation process is performed through calculations given by the specific horizontal elastic gripping when introducing a CD in the web, and by demonstration of the spacing between them.

Fig. 8. Calculation of horizontal and vertical displacement needed to accommodate a CD

Fig. 7. Calculation of Maximum lateral disturbance for stability for the model resulting from bionic inspiration

Mean spacing: 6 cm = 0,06 m. CD height: 12,4 cm = 0,124 m. Length (abreast of the tower): 0,35 m. Vertical displacement needed to accommodate a CD between two vertical elastic strings, spaced 0.032m apart.

Mass = 4,763 kg Mass center [cm] X = 27 Y = 32,66 Z = 42,63 Maximum capacity = 261CDs Medium capacity = 130 CDs Mass of 1 CD = 0.075 kg

0.06m=

hip 0.0322  0.1752

F = Maximum lateral disturbance for stability

hip = 0,1779 m

P = Weight of the tower + Weight of the maximum CD capacity For maximum capacity

 4.763kg   P    9.81  +19.57 kg 

0.124-0.06  0.032m 2

  sen 

For medium capacity

 4.763kg   P    9.81  + 9.57 kg 

0.032  0.18 0.1779

sin 1 0.18  10.4



168


Additional elongation: 0,1779 – 0,175 = 0,0029 m. δ(addit) = 0,0029 m. δ(unloaded) = 0,363 – 0,2075 = 0,1555 m. δ(addit + unladed) = 0,0029 + 0,1555 = 0,1584 m. F (addit + initial)H = 16,35 N. F (initial)H = 16,06 N. F (addit)H = F (addit + initial)H – F (initial)H= = 16,35 – 16,06 = 0,29 N

aspects, this additional horizontal load value was discarded in finite element analysis. This analysis, which has led to a safety margin of 66%, absorbs very loosely around the 2% increase in horizontal load which was not given a significant nature.

III. Conclusion The engineering validation steps of the bionic tower for storage of CDs and DVDs is considered successful, having satisfied all requirements selected. As a result of the validation process followed, one can testify through this case study, the gains that the bionic approach has provided to the product, compared with a conventional model. Taking into account all these results, it is understood that the application of the method developed under the guidance of analyzing the problem to the solution [10] is valid and can contribute to the development of optimized, efficient, sustainable and aesthetically pleasing products. Prototyping would also be a future feature appropriate to proceed with the validation of projects developed in this work and future bionic design projects. A most effective visual assessment and the possibility of more complete testing would consolidate and witness more realistically the persuasive benefits of bionics.

Percentage of Additional horizontal Force = 0.29   1.8% 16.06

Fig. 9. Calculation of Force applied to the frame by the elastic cable

Force applied to the frame by the elastic cable shown above:

Acknowledgements

Fv  16.35sen

Parts of this work were developed within the scope of the M.Sc. Thesis of the second author, supervised by the first author.

Fv  16.35 cos  sen  0.18 Fv  16.35sen  16.35  0.18  2.94 N

References Since the analysis is made in a symmetric half, this value is multiplied by 4. It follows that the vertical holding force for each row of CDs will be around 11.77 N (2.94 N × 4). Elastics have vertical alignment function, its pressure being negligible, but this is assisted by the friction between the surface of the CD cover and the surface of the elastic. The additional horizontal force calculated results in the validation of the requirement for greater gripping of objects arranged in the tower. This is an indicative value which will depend on the actual configuration of the arrangement performed by the user. Note that this additional horizontal force in the elastic cables that are horizontally disposed, being placed taking into account only the insertion of a CD into the middle of the web of elastics, leads to an increase of only 1.8% of the elastic tension set in the horizontal direction. In a situation where there are many CDs and DVDs placed, in the web, a part of the elastic deformation leading to an increase in its tension and its deformation will eventually be transmitted in part to CDs and DVDs that are underneath and, ultimately, discharged directly into the base of the frame of the web. Considering these

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[8]


D.A. Coelho, C.A.M. Versos (2010) An approach to validation of technological industrial design concepts with a bionic character, Proceedings of the International Conference on Design and Product Development (ICDPD'10), Athens, Greece, 40-45. D.A. Coelho, C.A.M. Versos (2011) A comparative analysis of six bionic design methods, International Journal of Design Engineering 4 (2), 114-131. Y. Gao, J. Luo, Geotechnical engineering reliability analysis using genetic algorithm, (2011) International Review on Computers and Software (IRECOS), 6 (7), pp. 1241-1245. V. Rao, J. Johns, (2008). Mechanical Properties of Thermoplastic Elastomeric Blends of Quitosano and Natural Rubber Latex. Journal of Applied Polymer Science, Wiley InterScience, Vol. 107, pp. 2217-2223 (2008). R. Sheeba, M. Jayaraju, K. Sundhareswaran, Bees colony intelligence in optimization: An application to PSS design, (2012) International Review on Modelling and Simulations (IREMOS), 5, (5), pp. 2355-2362. R. Shivakumar, R. Lakshmipathi, M. Panneerselvam, Power system stability enhancement using bio inspired genetic and PSO algorithm implementation, (2010) International Review of Electrical Engineering (IREE), 5 (4), pp. 1609-1615. C.A.M. Versos, D.A. Coelho (2010) Iterative Design of a Novel Bionic CD Storage Shelf Demonstrating an Approach to Validation of Bionic Industrial Design Engineering Concepts, Proceedings of the International Conference on Design and Product Development (ICDPD'10), Athens, Greece, 46-51. C.A.M. Versos, D.A. Coelho (2011-a) Biologically Inspired Design: Methods and Validation, in Industrial Design—New


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Frontiers (edited by Denis A. Coelho), Intech, 101-120. C.A.M. Versos, D.A. Coelho (2011-b) An Approach to Validation of Industrial Design Concepts Inspired by Nature, Design Principles and Practices: an International Journal 5 (3), 535-552. [10] C.A.M. Versos, D.A. Coelho, A bi-directional method for bionic design with examples, In D.A. Coelho (Ed.), Advances in Industrial Design Engineering, Rijka, Croatia: InTech Open Access Publisher, 2013). [9]


Technological Industrial Design Programme (Graduate), Dept. of Electromechancial Engineering, Universidade da Beira Interior, Covilhã, Portugal. 2

Dept. of Electromechancial Engineering, Universidade da Beira Interior, Covilhã, Portugal. Carlos A. M. Versos, M.Sc., Carlos A. M. Versos was born in 1987 in Covilhã, Portugal. In the academic year of 2005/2006, he entered the Industrial Design program at Beira Interior’s University. After graduation he continued pursuing the interest in this design field and concluded his master thesis in Technological Industrial Design at Beira Interior University with the theme of Bionic Design, with tutoring of Professor Denis Alves Coelho. His interest in nature, the background theme for his master's thesis led him to participate in projects to raise awareness and foster action for the preservation of forests trough education and volunteering programs. In his free time, Carlos Versos enjoys to draw and practicing sports to relax, such as cycling, karaté, kickboxing or jiu jitsu. Currently he is developing his PhD thesis, reflecting on the theme of bionic design, while interning at a furniture design, manufacturing and sales multinational company. Denis A. Coelho, Ph.D., Denis A. Coelho has been responsible for the creation and development in the University of Beira Interior of an entirely new program of studies in Industrial Design (undergraduate studies leading to a Bachelor's degree) and Technological Industrial Design (Masters program). He has also designed and helped design post-secondary programs of studies including Multimedia product development, Ecommerce web applications and multimedia web applications. As a Mechanical Engineer with an Ergonomic Design and Production Management post-graduate education his research has focused in several areas. He has worked with car seat comfort (ergonomic design) and has also been interested in Management Systems in Small and Medium Enterprises, as well as providing a contribution to the advancement of ergonomic design methods. He has also participated and coordinated Multimedia design projects, focusing on the application of ergonomic guidelines at both the conceptual and application level. International exposure has included research performed in collaboration with Swedish and US universities, applied to the automotive and healthcare sectors.



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