CC BY
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1НФОРМАТИКА
main advantage that it permits a structural analysis of all the subsystems that compose the system and a structural analysis of the global system. We have shown that the architecture presented reduces significantly the computational requirements, especially for a high number of interconnected subsystems and by using a multi-processor environment. We are now trying to evaluate the performances of our algorithms in terms of elementary operations (like addition, multiplication,...).
REFERENCES
[1] T. Murata, "Petri Nets: properties, analysis and applications," Proceedings of IEEE Vol. 77, N° 4, pp. 541-580, April 1989.
[2] R. David, H. Alla "Petri Nets for modeling of dynamic systems". Automatica, 2:175-202,1994.
[3] G. Berthelot "Verification des Reseaux de Petri" These de doctorat de troisieme cycle, universite P. et M. Curie (PARIS IV), 12 January 1978.
[4] K. Lauterbach, "Linear algebraic calculation of deadlocks and traps" {\it Concurrency and nets}, ed. K. Voss and H. J. Gen-rich, Springer-Verlag, 1987.
[5] E. R. Boer and T. Murata, "Generating basis siphons and traps of Petri nets using sign incidence matrix" {\it IEEE Trans. Circuits and Systems}, Vol. 41, No 4, pp 266-271, April 1994.
[6] A. Bourjij & al. "Algebraic Analysis of Discrete Event Systems Modelled by Generalized Petri Nets by use of Invariants" Mathematical Theory of Networks and Systems MTNS'96, Saint-Louis Missouri, June 1996.
[7] A. Bourjij "Contribution a la surete de fonctionnment des processus industriels par les reseaux de Petri", PhD Thesis, University Henri Poincare of Nancy I, France, 5 Dec, 1994.
0ДК 681.32
В статье представлены результаты сотрудничества между Германией и Румынией в рамках проекта EU-TEMPUS INCOT по разработке Web-центра. Этот центр поддерживает управление знаниями и европейскую сеть экспертов.
In this paper some results of a co-operation between the Germany and Romania within the EU-TEMPUS-project INCOT about the development of a Web-based competence centre are presented. This centre supports processes of knowledge management and telelearning and an European network of experts.
1. INTRODUCTION
The Internet with different forms of supported networking and knowledge management processes play an important role within the transition to the information society and knowledge-based economy.
On one hand, new information technologies (IT) e.g. the Internet and multimedia support knowledge management through services like information-transfer, navigation and access to different applications; on the other hand, the Internet causes an increasing flood of information and a decreasing validity period of it. So (potential) users of information
[8] M. Boutayeb, A. Bourjij, M. Darouach, "A decentralized algorithm to determine invariants in Petri Nets" MATHMOD Vienna, IMACS, 5-7 February, 1997.
[9] A. Kusiak, S. C. Wing, "Decomposition of manufacturing systems" IEEE Journal of Robotics and Automation, Vol. 4, N°5, Oct. 1988.
[10] N. Dridi, J. M. Proth "Ordonnancement des taches: une methode basee sur la technologie de groupes" Second International Conference on Production Systems, INRIA, tome 1, pp. 67-74, April 1987.
[11] J. Farkas, "Theorie der einfachen Ungleichungen" J.F.d. reine Angew Math., 124, 1902, 1-27.
[12] J. Martinez and M. Silva, "A simple and fast algorithm to obtain all invariants of a generalized Petri Net," 2nd European workshop on application and theory of Petri Net, Bod-honneff, 1981.
[13] H. Alaiwan and J.M. Toudic, "Recherche de semi-flots, de verrous et de trappes dans les reseaux de Petri," TSI Vol. 4, N° 1, pp. 104-112, 1985
[14] M. Silva and J.M. Colom, "On the computation of structural synchronic invariants in P/T nets," Lecture Notes in Computer Science Vol. 340, pp. 386-417, Springer-Verleg, 1988.
[15] T. Murata, B. Shenker and S.M. Shatz, "Detection of Ada deadlocks using Petri Net invariants" IEEE Trans. on Software Engineering Vol. 15, N° 3, pp. 314-326, march 1989.
[16] D.C. Marinescu, M. Beaven and R. Stansifer "A parallel algorithm for computing invariants of Petri Net models" Proceedings of the fourth international workshop on PNs and performance models, Melbourne, IEEE Computer Soc., pp. 136-43, 1991.
[17] P. Naudin and C.Quitte "Algorithme Algebrique" Masson 1992.
[18] K. Garg "An approach to performance specification of communication protocols using timed Petri Nets" IEEE Trans. on Software Engineering Vol. SE11, N° 10, pp. 1216-1224, 1985.
[19] A. Bourjij & al. "A decentralized approach for computing invariants in Petri Nets". IEEE SMC'97 orlando pp 1741-1746.
[20] A. Bourjij & al. "On generating a basis of invariants in Petri Nets". IEEE SMC'97 orlando pp 2228-2233.
PROCESSES
should be able to identify relevant one, to transform it in goal-oriented skills (knowledge generating), to process this knowledge according to the target group and so to contribute to the development of the organization they work with.
Innovative forms of IT-based learning (e-learning) like open distance learning (ODL) by using the Internet - tele-learning - are required in order to achieve such key competencies for the staff of the companies.
In part 2 of this paper we present some aspects of knowledge management (KM), particularly knowledge distribution (KD) which are important for manufacturing companies and some possibilities to support it by using IT -[1].
In part 3, telelearning methods and virtual communities which are based on the World Wide Web (WWW) are briefly described.
WWW is a global information system with a hypermedia structure; it is independent on the operating system and facilities the searching, retrieval and browsing of information via the Internet.
Virtual Competence centres which can be developed as suitable forums for KM, communication and experience
BUILDING EUROPEAN COMPETENCE CENTRES TO SUPPORT KNOWLEDGE DISTRIBUTION AND LEARNING
I.Hamburg, S.Balanica
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exchange between experts and for learning in a determined field are presented in part 4.
A Web-based virtual environment which supports a competence centre and a network of experts in telelearning from Germany and Romania and is being developed within the EU-Tempus project INCOT is presented in part 5.
2. KNOWLEDGE MANAGEMENT
Effective KM is considered as an important step to intelligent company building. The tasks knowledge acquisition (KA), knowledge identification (KI), knowledge codification (KC), knowledge distribution (KD) -[2] and knowledge use (KU) are assigned to KM in order to deal successfully with knowledge in the companies.
Many companies lose big potentials because knowledge which already exists (e.g. tacit knowledge in the brain of experts or explicitly one in archives) is not further processed, intensified, distributed and used.
Some experts consider that many companies know only a fraction of their knowledge which is potential accessible. Some causes can be the following -[3]:
- Missing methods for the identification of internal and external sources (e.g. individual knowledge of experts) and for the processing of containing knowledge,
- Missing structure for the transformation of it in knowledge accessible for all company staff,
- Troubles at the separation of "important knowledge" from "garbage".
Figure 1 shows three important trends which are connected between them and which produce "turbulence " instead of "transparency" within the knowledge society: extremely fast propagation of knowledge, far-reaching fragmentation and increasing globalisation of it. These determine also the structure of knowledge environment in the companies, which is more complex than some decades ago.
Figure 1 - Trends -[3]
KD is one of the main modules of KM. Some of main functions of it are the followings:
- Multiplication of knowledge through fast distribution on many persons,
- Saving and sharing of previous experience,
- Simultaneous knowledge exchange, which led to the creation of new knowledge.
Knowledge is distributed within the organization through carriers, named vehicles of knowledge -[4]. A vehicle of knowledge is a means by which knowledge can be transferred in spite of existing time and space barriers in the organization.
Such vehicles are the following:
- Organizational, like methods and organizational structures; they can help e.g. in case of projects to provide a common language,
- People as a source and carrier of knowledge; it is important to combine individual learning with organizational learning while people work co-operatively,
- Knowledge management systems (KMS), e.g. IT that support knowledge management.
Knowledge can be distributed:
- Through face to face, personal communication between individuals within work processes, meetings, training, seminars, social activities,
- By using IT like the Internet,
- By creating efficient virtual knowledge networks -[5] supported by virtual competence centres (see part 4).
The Web, which was developed in 1990 at CERN in Geneva to help researchers in sharing information and documents, is an important client-server based knowledge retrieval tool.
The management often controls knowledge processes in companies. Some barriers for KD in many companies are individual or cultural ones. They could have functional sources or hierarchical ones and refer to questions of power or confidence (Figure 2).
j + ^^ = / \
Hierarchical Functional not binded
barriers barriers knowledge isles
Figure 2 - Barriers -[3]
3. TELELEARNING AND VIRTUAL LEARNING
COMMUNITIES
Telelearning e.g. ODL via the Internet is one of the "most promising" forms of learning which can be applied within continuous vocational training programs but it means the beginning of a new paradigm of education: tutor and participants are "separated" in space and time, there is no necessity for courses to be place- or time-based, the student can control the learning process more than in traditional class rooms.
Today, the Web is a basic element in educational tele-learning environments -[6].
IHÔOPMATHKA
It is able to support images as well as many other file types, including hypermedia documents containing sound and videos, which can be viewed with external viewer programs. In order to be able to send and receive hypermedia files, servers and clients communicate using the HyperText Transmission Protocol (HTTP). Files are written by using the Hypertext Markup Language (HTML), which is a language for logical document layout. Web-based learning technologies are drastically changing how distance learners communicate with their professors and with each other. Nowadays, distance students have not to wait days and weeks for responses; e-mails are answered faster than phone calls or faxes. They can access not only local libraries but also other vast amounts of information available on the Internet.
A main advantage of the Web is that information is dynamic. So trainers can update their material whenever there is a need for it, students are kept up to date with the most recent changes and news about the learning material. The hyperlinks allow students to browse, jump between links in order to find relevant information and to perform searches easily. Flexibility is another main advantage of web-based learning. This refers to flexibility of time or/and of place of study, to the choice ("modularity") of learning content, to possible frequent updates and to the ability to respond to specific demands. So the Internet and Web-based learning facilitates the development of continuous and life-long learning processes by serving ever-changing needs of learners throughout their life span and by supporting connections between learning and working. In order to achieve this objective, the content of web-based learning modules can be closely integrated with the work of the trainees, and the knowledge and skills they are learning should find immediate application within their work and life.
Features offered by telelearning Web-based software are useful to students, instructors and administrators.
In the following we present some of these features. At the development of our telelearning environment we are going to implement some of them (see part 5).
Student-related features typically include communication tools like asynchronous conferencing among course participants, e-mails to individual course participants or to groups and discussion forum, course content search tools, tests to be performed at specific points in the course, self-evaluation multiple choice quizzes that can be performed at any time as well as presentation tools including students home pages.
Instructor-related features typically are content-related tools referring authoring and/or the ability to import content from other software, management tools to set up students groups for discussion, testing tools including automatic marking of multiple choice quizzes.
Features for administration could be creation and deletion of individual courses, performance monitoring for response time of Web servers, statistics related to number of students accessing the system at different times of day, access control and on-line registration.
The use of the Web has also limitations like the following:
- powerful computers are needed for users in order to fully benefit from the potential of the WWW,
- much time is consumed for downloading multimedia files or accessing popular URLs because of limited band width on Internet,
- the evaluation of thousands of links which are found by students related to their subject is often difficult,
- sometimes-active addresses given by instructors as references disappear before the students access them due to the dynamic process of updating and modifying materials.
Another downside of Web-based virtual classrooms is that distance students are not able to meet trainers/tutors and classmates face-to-face. Social communication, which is an essential component of every educational activity, is missing. The Co-operation, which in traditional classroom settings happens sometimes instantaneously, has to be facilitated by a conscious effort to build learning communities -[7].
An online learning community cannot be created by one person. Although the trainer (professor) is responsible for facilitating the creation process, the community or learning network is entirely dependent on participants and their willingness to contribute time, attention, ideas and commitment. In order to be considered "present" in a virtual classroom, the students have to access the course site online regularly, and to put in their answers and comments.
Stephen Covey -[8] affirms that the collaboration involved in learning in communities creates a sense of synergy and an atmosphere of excitement and passion for learning and working together, supporting the process of knowledge acquisition. In the traditional model of training the tutor imparts knowledge to participants, who are expected to absorb it. In the telelearning processes, the relationships and interactions among people are main objectives for generating knowledge. It is important that the tutor acts as a facilitator of the knowledge acquisition process. This process is supported by the choice of exercises to be solved by the participants. Therefore, the exercises phrasing has to be clear, to promote the distribution of existing individual knowledge and the creation of new individual and collective knowledge to be used by the participants. Another important factor - particularly in the field of staff qualification - is that learning environments foster personal meaning through interactions with communities of learners.
In the following we present the Web-based virtual competence centres, which can promote telelearning processes.
4. VIRTUAL COMPETENCE CENTRES
Virtual competence centres (VCCs) can be understood as a combination of competence centres (CC) and virtual communities (e.g. telelearning ones). VCC structure the relations between different participating groups (persons) in a new way.
In many cases VCCs are developed as professional platforms for KD, learning or communication and facilitate staff of different organizations to get information referring to different topics, products, services as well as to exchange experiences within discussion forums, per e-mail or in chat-rooms.
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Figure 3 - Potential participants within a VCC -[9]
Within a Web-based VCC, the user can have advantages from the hypermedia-based preparing of document contents. In this case, the corresponding computers have to fulfil some requirements (see part 3) in order to avoid long waiting periods for the downloading of multimedia documents.
One of the main objectives of a VCC is to develop a durable partnership between the participating persons (groups) not only to support a one or two time visit of the centre.
VCCs facilitate the learning from experience of other people through the advantages of new IT.
Through the unification of previous CC and virtual communities advantages, the VCCs support the combination of proved static elements with dynamical, forward-looking ones.
There exist many VCCs, also in German-speaking area. They differ in the type and structure of the co-ordination and of the users, in topics, in regional focus as well as in the content.
Some characteristics of the existing VCCs are the follow-ings -[9]:
- Many of them are an early stage of development,
- In most cases they are not really VCCs but service centres with additional entrance for the Internet,
- Only few VCCs can realize a close connection with the clients through registration and limitation of the users,
- Often they only supply information and do not offer interaction and communication services,
- Many of the VCCs could be improved by using multimedia and other new IT,
- They are rarely regional oriented.
5. A WEB-BASED ENVIRONMENT TO SUPPORT
A COMPETENCE CENTRE
For the development of the environment supporting the virtual centre we chose WEB because is the IT-distributed medium the most easy to access. Nowadays, you can access the web from your office, from your home, from your car, and even from your mobile phone. Every firewall, no matter how tight the security is, allows outgoing web connections. In short, World-Wide-Web, with it's support for images as well as many other file types, including sound and videos, is the most popular environment on the Internet. That's why, most of the times, it is associated with the Internet.
In the following we present some requirements on the software environment:
- A web server (Apache, IIS, etc), PHP 3.0+, and a MySQL server (either on the same machine, or on a remote one),
- For the client, a cookie-enabled browser (IE 3.0+, Netscape 2.0+).
The Security Module provides the support for several security levels clearance, as well as a way to verify if a certain person who requires accessing the VCC is a member of the community. This module can add new members, granting them the user level, after they complete an on-line form containing miscellaneous information (name, age, e-mail, fields of interest, etc.).
The Virtual Community Database is the database where all the information regarding a member is kept: name, e-mail, fields of interest, age, etc. This database can be accessed for updates by the security module, the testing module and the members that are administrators.
Figure 4 - The environment, which supports the VCC
Figure 5 - The homepage of the competence centre
IHÔOPMATÈKA
Information Sources module is a WEB-based document collection regarding various fields of interest. An expert, who will be the owner of the source, can add an information source.
The Forum Module provides further discussion regarding an information source where members can share information, experience and opinions.
Non-members of the centre will be able to get information about this Competence Centre, browse the categories available, but not access them, or the discussion forum. Of course, they will be able to register on-line and get access to all the information.
The community members are divided into three categories:
- Administrators: They add other administrators and experts, remove other users from the community, to change the owners of an information source, delete information sources and entries in any discussion forum).
- Experts: They can add new information sources, they are considered to be the "owners" of the information source they have added (they can modify or delete it), and they can share the ownership of an information source with other experts. They are also allowed to create test question (and modify and delete them) for the training materials that they own. If they post an entry in a discussion forum regarding an information source that they own, their entry is shown in a different, high contrast font, being considered as an "authorized entry".
- Users: This category of community members represents the "knowledge seekers". They can access here information sources, access the discussion forums, and contact the "owners" of an information source, or the poster of an entry in a discussion forum, for additional information.
Because the environment uses a modular approach, it is
easy to maintain, update, develop or reuse it. The object-oriented facilities offered by the language PHP allows that also the modules have this orientation. They are easier and faster even a module-level upg.
CONCLUSION
Virtual forms of co-operation and communication like VCCs which support processes of KM and Internet-based ODL have the future before them.
Within our EU-co-operation we would like to work out didactical principles of Internet-based ODL and to expand our VCC for other European countries.
REFERENCES
[1] Brodner P., Hamburg I. (Eds.) Strategische Wissensnetze: Wie Unternehmen die Resource Wissen nutzen, Schneider, Gelsenkirchen, 1999.
[2] Brodner P. Helmstadter E. Widmaier B. (Hg.) Wissensteilung -zur Dynamik von Innovation und kollektivem Lernen, Munchen/Mering. 1999.
[3] Probst, G. J. B. Wissen managen: wie Unternehmen ihre wertvollste Ressource optimal nutzen, Frankfurt am Main. New York. 1998.
[4] HART H., 1999: Knowledge transfer and knowledge management in a global organisation // P. Brodner, I. Hamburg (Hrsg.), Strategische Wissensnetze: Wie Unternehmen die Ressource Wissen nutzen, Schneider, Gelsenkirchen, 27-46.
[5] Engert S., Hamburg I., Terstriep J. Kompetenznetzwerke zur Kontextsteuerung von Wissensteilung: Ein Beispiel. 1999.
[6] Engert S., Hamburg I., Terstriep J. Web based Training: Experience within a German Project. // Supporting Learning Communities in Education, Paper presented at the i3 Spring Days 2000, Athens.
[7] Pallof R., Pratt K. Building Learning Communities in Cyberspace, San Francisco, 1999.
[8] Covey S., The Seven Habits of Highly Effective People: Powerful Lessons in Personal Change, Fireside, New York 1989.
[9] Schmidtmann A.,Felser W. Virtuelle Kompetenzzentren. // WIRTSCHAFTSINFORMATIK , 1999, 41 6, S. 554-560.
ÔÂÊ 681.32:007.58
ОБЗОР СОВРЕМЕННЫХ ТИПОВ НЕЙРОННЫХ СЕТЕЙ
М.В.Аникеев, Л.К.Бабенко, О.Б.Макаревич
В работе рассматривается современное состояние теории нейронных сетей. Проведен обзор некоторых наиболее часто применяемых в настоящее время нейросетевых архитектур. Рассмотрены различные подходы к обучению, проектированию и настройке нейронных сетей. Особое внимание уделено различным вариантам метода обратного распространения ошибки.
The current theory of neural networks is considered in this paper. Some of the most widely used architectures of neural networks are reviewed. Various methods of training and design are analyzed. Particular attention is paid to the backpropagation method of training.
ВВЕДЕНИЕ
Возможности современных компьютеров позволяют производить различные вычисления со скоростью на десятки порядков превышающей возможности челове-
ческого мозга. Однако ряд даже тривиальных для человека задач, не связанных с вычислениями, остается весьма сложным для вычислительной техники. Способность человека к ассоциативному хранению информации, обучению, обобщению и обработки информации с учетом контекста остается непревзойденной даже для современных суперкомпьютеров. Целью проектирования искусственных нейронных сетей (ИНС) является построение вычислительной структуры или алгоритма, работающего по принципам естественного интеллекта. К основным можно отнести следующие свойства нейронных сетей.
1. Нейронные сети, по аналогии с мозгом человека и животных, строятся из множества простых элементов, выполняющих элементарные действия и соединенных между собой различными связями.
2.Нейронные сети способны совершенствовать свою работу (обучаться или адаптироваться), используя примеры.
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