IV International Conference on Multimedia and Information & Communication Technologies in Education (m-ICTE2006)
e-Antenna : Antenna web based course using matlabserver Olivier Vidémé Bossou*,1, Juan R. Mosig1, and Emmanuel Tonye2 1
2
Ecole Polytechnique Fédérale de Lausanne, Electromagnetics and Acoustics Laboratory, Station 11, CH-1015 Lausanne, Switzerland Ecole Nationale Supérieure Polytechnique, Electronics and Signal Processing Laboratory, B.P 8390 Yaoundé, Cameroon
Teaching antenna electromagnetic theory at undergraduate level usually requires vector mathematics in a 3D continuous space. This makes the average course hard to understand by today's students, more used to deal with digital/discrete quantities in 1D or 2D spaces. With the purpose of rendering more attractive these courses, we have developed a series of teaching tools in MatLab environment. To make this process more interactive, and also to access a much wider number of students, we are proposing to use the nowadays well developed web-based tools for e-learning. The MatLab environment with his Matlab Web Server enables us to create Matlab applications that use the capabilities of the World Wide Web for inputting data and graphically displaying the output results with just a Web browser. More in detail, we have created the HTML documents for collection of the input data from users and for display of output with PHP codes. Besides Matlab codes, we use a data base server which provide data from an Access data base which will be used by Matlab programs. Keywords Antenna theory, e-learning, Matlab Server, web browser
1. Introduction Up to now, we have developed teaching tools in MatLab environment that can only be used in a noninteractive "ex-cathedra" way, where the teacher illustrates his course to an essentially passive auditorium [5], [6]. To make this process more interactive, and also access a much wider number of students, we are proposing to use the nowadays well developed web-based tools for e-learning. Also, although in the original version the demonstration tools are available only to students who have done their inscription to the course, a password system can be easily implemented. The choice of Matlab for our codes was originally done in because of the well known inherent Matlab facilities: ease of programming, impressive graphical interfaces... But in addition Matlab has now standardized its Matlab Web Server and selecting it is the best choice for us in order to make the codes widely available and easily maintaining them. We therefore have chosen the simplest configuration with a Web browser running on the client workstation, while MATLAB, the MATLAB Web Server (matlabserver), and the Web server daemon (httpd) run on another external machine [1]. This way, the end user needs just the most basic computer facilities, nowadays available almost everywhere in the world. More in detail, we have created the HTML documents for collection of the input data from users and for display of output with PHP codes [2], [3]. Besides Matlab codes, we use a data base server which provide data from an Access data base which will be used by Matlab programs. All these programs are only used inside the university and are transparent for the end user. As mentioned, outside the root university a password attributed by the course responsible teacher will permit the access by students.
2. e-Antenna architecture In our web site architecture (Fig. 1) we have two components : the web server and the client. On the client web browser the student can access the teacher’s slides which is use for the course. Before a stu*
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m-ICTE2006 – 22-25 November 2006 – Seville – Spain
IV International Conference on Multimedia and Information & Communication Technologies in Education (m-ICTE2006) dent accesses this course, he must be registered as EPFL student. After entering his logging name and his password he can view the teacher’s course. In the other hand, the student does not need password to set up input parameters and then launch the Matlab server. After a while, and depending on which operations is being perform, the server send to the client browser files and graphs, the output parameters of the Matlab files execution. The web server collects the data from input parameters via the HTTP daemon and calls the matweb file. The matweb file will call matlabserver file and transfer the data to the Matlab file which will be executed and save the results as figures and files. The graphs are the antenna’s electric currents or the radiation plot curves, where the files content the values of the current distribution and the intensity of the fields for both elevation (theta) and azimuth (phi) angles. The matlabserver collects data from an access data base, chooses the appropriate Matlab file to perform the operation, save the results and put them in a HTML file. The web server sends the HTML file to the client browser. The results come in another webpage file different from the first one. In order to put all in the same file the student have to click on the button “Show the Graphs” to appreciate the graphs and the results saved in files.
Fig. 1 e-Antenna architecture.
3. Functional diagram All the web site is built on one file (index.php) which can call many subroutines to execute the tasks. It is divided in directories : • The main directory has several folders. Each folder represents a chapter. • In each chapter’s directory we have simulation directory, the teacher course directory, and HTML file and figures related to the chapter. • In each simulation directory we have a Matlab directory and HTML file and figures related to the simulation. • In the Matlab directory we have Matlab program and input and output directories. In the simulation folder, the PHP program will create a session directory. In the session directory, we have sessions’ number and users’ directories. Each session’s number directory has a copy of the Matlab directory contents. All input and output data obtain during simulations are stored in input and output directories which are in sessions’ number directories. Every simulation output parameter is saved in
m-ICTE2006 – 22-25 November 2006 – Seville – Spain
IV International Conference on Multimedia and Information & Communication Technologies in Education (m-ICTE2006) different folders located in the output directory. All the simulation output parameters are not accessible to users. If a user needs to access later output parameters he must save the data in his folder. So in users’ directories there are only history data. To make all work properly there are some rules to be observed when writing the main.m file and the Matlab main program related to the simulation to be conducted. The first file contains the input parameters that will be used for the input parameter menu, and the second one must collect the data from the HTML web page. The flow chart (Fig. 2) below show globally how the web site works if a user is connected. This web site is only accessible inside the university. Outside you will need a password which will be given by the teacher responsible of the course. To access the teacher slides you need to be a student registered at the root university.
Fig. 2 e-Antenna flow chart.
4. Functional Example This courseware is accessible through the laboratory web site. First of all the user has to reach the web site. After he must log by using his login name and his password given by EPFL to any student. When the user is logged, the web page will be similar with the one on Figure 3. Then he can go through chapters (Fig. 4) and simulations (Fig. 5). If the user wants to lunch a simulation he will only fill in the input parameters menu with the appropriate values and then click on the button “Execute Matlab”. After the simulation is completely finished he can click on the button “Show the Graphs” (Fig. 6). If the results are convenient to him and if he wants to use them later, he can click afterwards on the button “Save this test” (Fig. 7). The saved results can be accessed at each time the user will need, unless the system manager clear the hard disk to make place.
m-ICTE2006 – 22-25 November 2006 – Seville – Spain
IV International Conference on Multimedia and Information & Communication Technologies in Education (m-ICTE2006)
Fig. 3 e-Antenna main page.
Fig. 4 e-Antenna chapter page
Fig. 5 e-Antenna simulation page m-ICTE2006 – 22-25 November 2006 – Seville – Spain
IV International Conference on Multimedia and Information & Communication Technologies in Education (m-ICTE2006)
Fig. 6 e-Antenna simulation results page
Fig. 7 e-Antenna history page
5. Conclusion This courseware is a useful tool for teachers to make student well understand the antenna courses. All these simulations give to the students a practical sense for the antenna course. Once the web site is built, any number of simulations can grow up if the specified rules are respected when writing the program files. This web course increases the number of users, but reduces the interactivity of the Matlab program. The use of the matlabserver is time consuming for the user who must wait for the response from the server. But beside this inconvenient, the development of this web site contributes to make the antenna course more understandable and accessible for the average student.
References [1] MathWorks Inc., MATLAB Web Server, (2005). [2] [3] [4] [5]
Paul Hudson, PHP in a nutshell, O’Reilly, 2006. George Schlossnagle, Advanced PHP programming, Developer’s library, 2004. http://ephotnics.epfl.ch Olivier Vidémé Bossou, J. R. Mosig, E. Tonyé, Kit Didactique Matlab pour le Traitement d’Antenne de Type Filiforme, 1st International Symposium on Electromagnetism, Satellites and Cryptography (ISESC'05), June 19-21, 2005, Jijel, Algeria. [6] Olivier Vidémé Bossou, J. R. Mosig, Teaching Matlab Based Toolbox for Antenna Course. "International Conference on Engineering Education, July 25–29, 2005, Gliwice, Poland".
m-ICTE2006 – 22-25 November 2006 – Seville – Spain
