The STEP Standards in Semantic Web — A Way to Integrate the ...

The STEP Standards in Semantic Web – A Way to Integrate the Product Development Chain

K. Schützer, A.A.A. Moura /DERUDWRU\IRU&RPSXWHU$SSOLFDWLRQLQ'HVLJQDQG0DQXIDFWXULQJ Methodist University of Piracicaba, Santa Bárbara d’Oeste, Brazil

Abstract 1RZDGD\VWKHSURGXFWLRQHQWHUSULVHPD\EHFRPHDQHWZRUNRILQGHSHQGHQWFRPSDQLHVZKLFKVKDUHH[SHULHQFHVNQRZOHGJHDQGFDSDFLWLHV+RZHYHUWRWUDQVIRUP WKLVQHWZRUNLQWRDFRPSHWLWLYHDGYDQWDJHUHTXLUHVWKDWLQIRUPDWLRQEHH[FKDQJHG HIÀFLHQWO\$VSURMHFWDQGFRPSRQHQWSURGXFWLRQDUHHODERUDWHGLQFUHDVLQJO\E\D QHWZRUNRIVXSSOLHUVDQGDVWKHSURFHVVEHFRPHVIDVWHUWRDQVZHUFRQVXPHUV·GHmands, the integration problem extends beyond the limits of the system and company. A new approach to this problem is the Semantic Web, an emerging area of research that purposes to guarantee interaction among information systems, to permit a variety of complex applications through the characteristics of semantic descripWLRQVRIZHEUHVRXUFHVGDWDDQGVHUYLFHV 

Keywords STEP Standards, Semantic Web, Product Development Process, Data exchange

1

Product Development Chain

The product development chain starts with an idea that came from a need RUDQLQVSLUDWLRQIRUDSSURSULDWHPHWKRGVWRÀQGVROXWLRQV$PRGHOLVFRQstructed from this idea and its objective is to start a process which will end with the material execution of the product. In the process of producing a mechanical product through machining, the development cycle is well established and is followed by computer aided systems.

116

Design Theory

The digital integration of the phases of the product development chain is one of the objectives of the modeling systems. To achieve this objective it is necessary to permit that the specialist in charge of any development phase be focused on the information that is relevant to this phase, without losing the overall view of development [1]. The adoption of a friendly system, without restrictions to data exchange among different systems, will allow new levels of interaction in product GHYHORSPHQWZLWKUHGXFHGQHHGIRUPRGLÀFDWLRQV>@VLQFHWKHSURGXFW data do not need to be mapped or translated. In a heterogeneous scenario the initiative of the ISO 10303 or STEP 6WDQGDUGIRUWKH([FKDQJHRI3URGXFWPRGHOGDWD LQWHUQDWLRQDOVWDQGDUG has provided a neutral means for the exchange of data about the product model [4]. However, it can be argued that the use of standards per se cannot solve the problem of integrating the product development chain.

2

Conception of the Product Data

Due to the fact that each activity of the product cycle may generate a component of the product data model independently and with no concern for the subsequent phase and its integration, the product data model may be characterized by a heterogeneous database system [5]. 7KHGLVFUHSDQFLHVPD\RFFXUDWDQ\OHYHORIDEVWUDFWLRQGDWDVFKHPDVRU PRGHOV +HWHURJHQHLW\PD\EHGLUHFWO\FKHFNHGLQWKHGDWDUHSUHVHQWDWLRQ or just be an interpretation matter. The integration of different database may diminish the capacity of each component to manage its own data without general interference by the heterogeneous database system [5]. 7KHLQWHJUDWLRQRIKHWHURJHQHRXVGDWDUHTXLUHVFRQÁLFWUHVROXWLRQRIKHWHURgeneity and the transformation of data sources into an integrated whole [6]. Among the ideas developed for the integration of heterogeneous data, the one that offers the widest range is the establishment of standards for data modHOV DQG V\QWD[ VSHFLÀFDOO\ WKH 67(3 VWDQGDUGV ZKLFK KDYH DFKLHYHG JUHDW success. The use of semi-structured data gives versatility to data representation, allowing data transformation and mapping of irregular structures. 2QHRIWKHJUHDWHVWGLIÀFXOWLHVLQWKHLQWHJUDWLRQRIKHWHURJHQHRXVGDWDLV WKHVHPDQWLFORVVRIFRPSRQHQWV$VW\SLFDOGDWDPRGHOLQJWDNHVVHPDQWLFV with it, information may be lost in the conversion of data from a data model into semi-structured data. This problem may be managed by the maintenance of a metadata set associated to converted semi-structured data. Therefore the VROXWLRQWRVHPDQWLFFRQÁLFWVLVLQWKHQRUPDOL]DWLRQRIPHDQLQJVFRQFHSWV

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terminology and in the structuring of the data source. This has been achieved by STEP standards, which enriches the metadata to support the investigation of the semantic adjustment among data values of different data sets.

3

STEP Standards

7KH,62PHHWLQJLQ)UDQNIXUW*HUPDQ\LQPDUNHGWKHLPSOHPHQWDWLRQ of the STEP standards. The present structure of the STEP standards is a consequence of a great number of contributions. With the aim of achieving the proposed objectives, the STEP standards ZHUH GHYHORSHG LQ D PRGXODU VWUXFWXUH WR JXDUDQWHH QHFHVVDU\ ÁH[LELOLW\ The various modules are documented in separate parts in the ISO 10303 ,QWHUQDWLRQDO 6WDQGDUG >@7KH JURXS RI SURGXFW GDWD GHÀQLWLRQV WKDW FDQ be supported by STEP is subdivided into a number of independent modules ZLWKFOHDUO\GHÀQHGLQWHUIDFHV7RH[FKDQJHGDWDDPRQJ&$'V\VWHPVWKH 67(3VWDQGDUGVSURYLGHDQLPSOHPHQWDWLRQPHWKRGGHÀQHGLQ3DUWDVD SK\VLFDO ÀOH LQ VHTXHQWLDO WH[W IRUPDW ,Q WKH GHYHORSPHQW SKDVH 3DUW  GHÀQHVWKHSK\VLFDOÀOHLQ;0/H;WHQVLEOH0DUNXS/DQJXDJH  Since it is not possible to have all the possible applications in a single data group, or offer a concrete context for the data, the STEP standards use Application Protocols, which describe the utilization of data exchange for a particular application, thus reducing the scope of each protocol to a business area. Although the VWDQGDUGVDUHDNH\IDFWRUWRGDWDLQWHJUDWLRQVXFFHVVWKH\DUHQRWE\WKHPselves the guarantee to this success [1].

4

Semantic Web

The Semantic Web is an emerging research area, whose objective is to guarantee integration among information systems and to permit a variety of FRPSOH[DSSOLFDWLRQVWKURXJKVHPDQWLFGHVFULSWLRQVRI:HEUHVRXUFHVGDWD DQGVHUYLFHV ,WLVDQLQIUDVWUXFWXUHLQZKLFKGLIIHUHQWDSSOLFDWLRQVPD\EH developed. Another proposal is to increase the present Web with the formalL]DWLRQRINQRZOHGJHDQGGDWDWKDWGLIIHUHQWKXPDQVDQGRUFRPSXWHUVPD\ share and process [8]. 7KHNH\UHTXLUHPHQWWR6HPDQWLF:HELVLQWHURSHUDELOLW\'DWDDQGPHWDdata must correspond to consensual formats and concepts to enable sharing and processing. Figure 1 shows the layers of standards and technologies of Semantic Web.

118

Design Theory

Fig. 1: Infrastructure of the Semantic Web

The bottom layer, Character Encoding and URI, establishes an internaWLRQDOVWDQGDUG²81,&2'(²IRUWKHVHWRIFKDUDFWHUVDQGDPHDQLQJIRUD VLQJOHLGHQWLÀFDWLRQRIUHVRXUFHVLQWKH6HPDQWLF:HE 7KH ;0/ OD\HU ZKLFK LQFOXGHV QDPHVSDFHV DQG VFKHPD GHÀQLWLRQV is constituted by a standard syntax, which gives the basis for data model description in such a way that the exchange of information and schemas may become possible. 2QWKHWKLUGOD\HUWKH5')5HVRXUFH'HVFULSWLRQ)UDPHZRUN SHUPLWV VWDWHPHQWV WKDW DVVRFLDWH UHVRXUFHV ZLWK SURSHUW\ ZKLOH WKH 5')6 5') 6FKHPD HQDEOHVWKHGHÀQLWLRQRIYRFDEXODULHVWKDWPD\UHIHUWRWKH85,VLQ which they are published. These vocabularies may be used to associate types to resources and properties. The ontology layer enriches the vocabulary and permits its evolution, extending the repertory of concepts and semantic relations among words. 7KHXSSHUOD\HUV²/RJLF3URRIVDQG7UXVW²DUHLQGHYHORSPHQW



&RUUHODWLRQVEHWZHHQ67(3DQG6HPDQWLF:HE

The proposed solutions to data integration come from common pretexts and DUH WKHUHIRUH VLPLODU ,Q D VSHFLÀF DSSOLFDWLRQ WKH 67(3 VWDQGDUGV ZHUH GHYHORSHGDVPHWDGDWDVWDQGDUGV>@ZKLFKÀWSHUIHFWO\LQWRWKH6HPDQWLF Web proposals. Since a wider amplitude is their initial objective, they also present a wider solution. In the next part, the existing correlations between the two solutions will be presented.

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First Layer: Unicode and URI

The use of an international standard for the characters used in the whole Semantic Web is the minimum requirement for subsequent phases to be able WRZRUNZLWKWKHVDPHGDWD

Fig. 2: ;0/'RFXPHQWIRUDPHFKDQLFDOSURGXFW

,QWKLVDVSHFWWKH67(3VWDQGDUGVGRQRWDVVLJQ81,&2'(H[SOLFLWO\EXW implicitly the whole standard is structured according to this international standard, though just a part of it is used. )LJXUH  SUHVHQWV D GRFXPHQW LQ ;0/ XVLQJ 81,&2'( FKDUDFWHUV WR GHVFULEHDPHFKDQLFDOSURGXFW7KH;0/V\QWD[QRWRQO\SHUPLWVWKDWWKLV ÀOHLVH[KLELWHGLQDQ\ZHEEURZVHUEXWDOVRDFFXPXODWHVLQIRUPDWLRQDERXW the product in an extensible way. 5.2

Second Layer: XML and XML Schema – AAM

7KH VFKHPD ODQJXDJHV IRU ;0/ DUH '7' 'RFXPHQW 7\SH 'HFODUDWLRQ  DQG;0/6FKHPD6FKHPDVSHFLÀFDWLRQVPD\EHVWRUHGWRJHWKHUZLWKGDWD LQ;0/RULQVHSDUDWHGRFXPHQWVZKLFKFDQEHUHIHUHQFHGE\VHYHUDO;0/ GRFXPHQWV7KH'7'LVLWVHOIDVSHFLÀFDWLRQRI;0/GHÀQLQJWKHVWUXFWXUHRIWKH;0/GRFXPHQWE\WKHXVHRIDOLVWRIHOHPHQWW\SHGHFODUDWLRQV 7KHVHGHFODUDWLRQVGHÀQHW\SHVRIDWRPLFFRPSRQHQWVLQ;0/DQGWKHQHVWed structure of compounded elements. 7KH;0/6FKHPDVRIIHUDV\QWD[EDVHGRQ;0/WRGHVFULEHWKHVWUXFWXUH DQGWKHFRQWHQWOLQNVRIDQ;0/GRFXPHQW>@)LJXUHSUHVHQWVDQ;0/ Schema for a document of a mechanical part with the following structure:

120

Design Theory

WKHÀUVWOLQHKDVWKHGHVFULSWLRQRIWKHDUHDQDPHGIRUWKHYRFDEXODU\RIWKH ;0/VFKHPDWKHVHFRQGOLQHVKRZVWKDWDGRFXPHQWLQFRQIRUPLW\ZLWK WKHSUHVHQWHGVFKHPDPXVWKDYHDQHOHPHQWQDPHG´0HFKDQLFDO3DUWµRI WKH´0HFK3DUW7\SHµ7KLVW\SHLQFOXGHVQHVWHG´$JJUHJ9DOXHVµHOHPHQWVWR store the essential information of each one of the manufacturing features.

Fig. 3: ;0/6FKHPDIRUDPHFKDQLFDOSDUW

'XHWRWKHODFNRIVHPDQWLFLQIRUPDWLRQWKHVFKHPDGHVFULSWLRQE\LWVHOI LVQRWHQRXJKWRHQVXUHWKHFRUUHFWLQWHUSUHWDWLRQRIGDWDLQ;0/RUWRSHUPLW their integration. For example, there is no indication of the measurement units and of the co-ordinate system used. This example shows the need for DVVRFLDWLQJWKHFRQFHSWXDOPHDQLQJZLWKGDWDLQ;0/DQGLWVPDUNLQJV7KH use of schema and standardized metadata, once well documented and with common meanings, may reduce this problem [10]. 7KH$$0$SSOLFDWLRQ$FWLYLW\0RGHO LVRQHRIWKHWKUHHPDLQHOHPHQWV of a STEP application protocol [7] that describes the business process that supSRUWVWKHLQIRUPDWLRQPRGHO7KXVLWKDVWKHVDPHREMHFWLYHDVWKH;0/OD\HU DQG;0/6FKHPD6LQFHLWLVGHVFULEHGLQDVSHFLÀFODQJXDJHRIWKHQRUPWKH EXPRESS/ESPRESS-G, the characteristics of object orientation are present in both languages and there are no barriers to a direct translation [9]. 5.3

Third Layer: RDF and RDFS-ARM

7KH5HVRXUFH'HVFULSWLRQ)UDPHZRUN²5')²LVWKHPDLQIRUPDWIRUFRPputer processing of metadata in Semantic Web. RDF is based on the repreVHQWDWLRQRIIRUPDONQRZOHGJHVXFKDVWDEOHVDQGORJLFGHVFULSWLRQV7KHEDsic building of a RDF model is an assertion, a triple in the form of a ‘subject

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SUHGLFDWHREMHFWµZKHUHWKHVXEMHFWUHIHUVWRDQ\UHVRXUFHDQ\WKLQJWKDW PD\EHGHVFULEHGZLWKWKH85, WKHSUHGLFDWHLVDSURSHUW\RIWKLVUHVRXUFH DQGWKHREMHFWLVWKHYDOXHRIWKLVSURSHUW\7KHREMHFWFDQEHDOLWHUDOHJD VHQWHQFH RUDQ\RWKHUUHVRXUFH 5')65')6FKHPD LVDQH[WHQVLRQRI5')ZLWKFODVVHVRIUHVRXUFHV YDOXHVDQGSURSHUWLHV$Q5')6VSHFLÀFDWLRQGHÀQHVDVWUXFWXUHRIFODVVHV properties and sub-classes for a particular domain or application, similar to a category diagram of an object oriented model [10]. Figure 4 shows the use of RDF and RDFS for the description of Web resources. At the upper part, two different schemas, describe resources to ZRUN WKH GDWD RI D PRGHO7KH 5') VFKHPD RQ WKH OHIW GHVFULEHV WKH UHVRXUFHVWRZRUNZLWKWKHJHRPHWULFPRGHOIRUH[DPSOHYLVXDOL]DWLRQZKLOH the system on the right collects the product data for the process and carries out process planning services. (DFKVSHFLÀHGUHVRXUFHLQ5')DWWKHERWWRPRIÀJXUHLVDQLQVWDQFHRI VRPHFODVVHJDQRWKHUUHVRXUFHRIWKHVDPHW\SH RIDQRWKHU5')VFKHPD in the upper part. For example, the slot is an instance of a prism in the schema on the left and an instance in the machining operation on the right. 'HÀQLWLRQVLQYROYLQJLQVWDQFHVRIUHVRXUFHVPXVWEHFRPSDWLEOHZLWKGHÀQLtions of the RDFS level. Besides providing different views for the same resources, RDF/RDFS DOVRKHOSWRGHÀQHXQLÀHGYLHZVRIKHWHURJHQHRXVUHVRXUFHV)RUH[DPSOH a slot has a geometric interest in modeling, while for the process this same HQWLW\GHÀQHVWKHW\SHRIWRRODQGLWVSDWK7KHWROHUDQFHFKDUDFWHULVWLFVKDYH different consequences in machining and measurement. The different comSXWHUDLGHG V\VWHPV DOVR GHÀQH WKH VDPH HQWLWLHV GLIIHUHQWO\ )RU D &$' V\VWHPDVORWLVDSULVPGHÀQHGE\LWVERUGHUVIRUD&$0V\VWHPWKHVDPH VORWLVGHÀQHGE\WKHZD\WKHWRROSHUIRUPVWRPDFKLQHLW$QRWKHUPDMRU problem is the different ways of describing an entity among different sysWHPV9DULRXVOHYHOVRI5')5')6GHVFULSWLRQVPD\SURYLGHWKHVROXWLRQ WRWKHVHFRQÁLFWV7KH5')5')6VWDQGDUGL]DWLRQVDUHLPSRUWDQWLQWKHIROlowing aspects of Semantic Web: % State the relations involving resources and resource description; % Allow different views of the same resources, adjusted to their different ÀHOGVRIDFWLRQRUDSSOLFDWLRQV % %XLOGXQLÀHGYLHZVIRUFROOHFWLRQVRIKHWHURJHQHRXVUHVRXUFHV % 'HVFULEHNQRZOHGJHXVLQJYRFDEXODU\RIFRQFHSWVDQGWKHVHPDQWLFUHODtions among these concepts.

122

Design Theory

Fig. 4: RDF and RDFS for a mechanical part

,QFRPSDULVRQZLWKWKH67(3VWDQGDUGVWKH$50$SSOLFDWLRQ5HIHUHQFH 0RGHO VSHFLÀHVWKHLQIRUPDWLRQUHTXLUHPHQWVZLWKLQWKHVFRSHRIDVSHFLÀF DSSOLFDWLRQSURWRFROWRUHGXFHWKHGRPDLQWRDQDUHDRINQRZOHGJH $VZHOODVIRUWKHSUHYLRXVOD\HUWKHUHLVQRGLIÀFXOW\LQWUDQVODWLQJWKH 5HIHUHQFH0RGHORI(;35(66(;35(66*WR;0/ 5.4

Fourth Layer – Ontology – AIM

2QWRORJ\ LV WKH VFLHQFH WKDW VWXGLHV WKH FRQFHSWV WKDW HQDEOH XV WR NQRZ and determine the consistence of things. A consequence of ontology is the VHW RI FRQFHSWV WKDW ZKHQ VKDUHG HVWDEOLVK NQRZOHGJH DERXW D GHOLPLWHG GRPDLQ$QRQWRORJ\RUJDQL]HVGHÀQLWLRQVDQGLQWHUUHODWLRQVLQYROYLQJVHWV RIFRQFHSWVHJHQWLWLHVDWWULEXWHVSURFHVVHV 2QWRORJ\LVDEOHWRFDSWXUH the meaning of class and instances in a speech universe by the arrangement RIV\PEROVHJZRUGVH[SUHVVLRQVV\PEROV DFFRUGLQJWRWKHLUVHPDQWLF relations [11]. 'HÀQLQJRQWRORJ\IRUVKDUHGNQRZOHGJHDOORZVDSUHFLVHGHÀQLWLRQRIDQ\ consultation and the correct answer, even in open environments. Ontologies also help in data integration, particularly in the investigation of correspondence among data elements that come from heterogeneous sources [12]. The basis for the implementation of the STEP standards within an appli-

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FDWLRQSURWRFRODQGWKHUHIRUHLQDVSHFLÀFGRPDLQLVWKH,QWHUSUHWHG0RGHO which is based on STEP integrated resources. This mode is described in ,'()ZKLFKFRXOGUHVXOWLQDQRWKHUGLIÀFXOW\ZLWKWUDQVODWLQJWRWKHRQWRlogical languages expected by the Semantic Web, but since the concepts are the same, this obstacle is easily overcome [13].

6

Conclusions

The Semantic Web is a vision for the future of the web in which information is given explicitly, facilitating the automatic processing and integration of the LQIRUPDWLRQDYDLODEOHLQWKHZHE7KH6HPDQWLF:HEZLOOEHEXLOWZLWK;0/ DELOLW\WRGHÀQHWDJVFKHPDVDQG5')ÁH[LELOLW\IRUGDWDUHSUHVHQWDWLRQ The Semantic Web requires a layer of ontology on RDF, which can describe the meaning of the terminology used in Web documents formally. ,QWKHKRSHWKDWFRPSXWHUVH[HFXWHXVHIXODQGPHDQLQJIXOWDVNVZLWKZHE GRFXPHQWVWKHODQJXDJHWRVXSSRUWWKH5')VFKHPDLV;0/H[DFWO\DVLW is previewed by the STEP standards and Semantic Web. 7RWUDQVIRUPWKH67(3SK\VLFDOWH[WIRUPDWÀOHWR;0/LVWKHÀUVWDQG most important step to the integration of the whole product development F\FOH (QODUJLQJ WKH SURGXFW LQWHJUDWLRQ WR WKH (53 (QWHUSULVH 5HVRXUFH 3ODQQLQJ DQG&50&XVWRPHU5HODWLRQVKLS0DQDJHPHQW WRROVLVDWDVN for the future. -XVWXVLQJ;0/ZLWKRXWDQ\RWKHULPSOHPHQWDWLRQHQDEOHVVHYHUDOSURcesses: the data product model may be viewed in a simple browser, the additional attributes are not lost in the model and the sequence of model construction may be maintained.



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This study was done with the support of CAPES, a Brazilian federal agency WKDWSURPRWHVVFLHQWLÀFUHVHDUFK

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Design Theory

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/LEHV'HWDO 7KH&KDOOHQJHVRI$XWRPDWHG0HWKRGVIRU,QWHJUDWLQJ 6\VWHPV ,Q 6RIWZDUH (QJLQHHULQJ   )HEUXDU\ ,QQVEUXFN Austria, IASTED. pp. 89-111 %DUNPH\HU(-HWDO &RQFHSWVIRU$XWRPDWLQJ6\VWHP,QWHJUDWLRQ 1DWLRQDO,QVWLWXWHRI6WDQGDUGVDQG7HFKQRORJ\*DLWKHUEXUJ ;X;:+H4 6WULYLQJIRUDWRWDOLQWHJUDWLRQRI&$'&$33&$0 DQG &1& -RXUQDO RI 5RERWLFV DQG &RPSXWHU,QWHJUDWHG 0DQXIDFWXULQJ 20:101-109 3UDWW 0-$QGHUVRQ %'  $ VKDSH PRGHOLQJ DSSOLFDWLRQV SURJUDPming interface for the STEP standard. Computer-Aided Design 33:531543 'HQQR 3 7KXUPDQ 7   5HTXLUHPHQWV RQ ,QIRUPDWLRQ 7HFKQRORJ\ IRU 3URGXFW /LIHF\FOH 0DQDJHPHQW ,QWHUQDWLRQDO -RXUQDO RI 3URGXFW Development 2:109-122 3HDN56HWDO 67(3;0/DQG80/&RPSOHPHQWDU\7HFKQRORJLHV Journal of Computing and Information Science in Engineering, 4:379-390 )HHQH\$%3ULFH'0 $0RGXODU$UFKLWHFWXUHIRU67(31DWLRQDO Institute of Standards and Technology. In. World Automation Congress, 2000. December, 1999. %HUQHUV/HH7+HQGOHU-/DVVLOD2 7KH6HPDQWLF:HE6FLHQWLÀF American, May, 2001. +DUGZLFN 0  $ PRGXODU ;0/ LPSOHPHQWDWLRQ PHWKRG IRU 67(3 KWWSZZZVWHSWRROFRPDVRI6HSWHPEHU )LOHWR 5   $ $ERUGDJHP 32(6,$ SDUD D ,QWHJUDomR GH 'DGRV H 6HUYLoRVQD:HE6HPkQWLFD3K'WKHVLV8QLFDPS 5RVDWL5 2QWKHGHFLGDELOLW\DQGFRPSOH[LW\RILQWHJUDWLQJRQWRORJ\ and rules. Journal of Semantic Webs 3:61-73 /HH-*RRGZLQ5 2QWRORJ\PDQDJHPHQWIRU/DUJHVFDOH(QWHUSULVH Systems. Electronic Commerce Research and Applications, 5:2-15 3UDWW 0-$QGHUVRQ %' 5DQJHU 7   7RZDUGV WKH VWDQGDUGL]HG H[change of parameterized features-based CAD models. Computer-Aided Design 37:1251-1265