Let. 38, Št. 9 (2005)

Blaž Rodič

Faculty of Organisational Sciences, University of Maribor, Kidričeva cesta 55, 4000 Kranj, Slovenia

Miroljub Kljajić

Faculty of Organisational Sciences, University of Maribor, Kidričeva cesta 55, 4000 Kranj, Slovenia

Povzetek

Background/Purpose: This paper presents the use of mobile agents and XML for the connection of simulation models and data resources over a communication network. We have developed two types of agents: a mobile agent that functions as a mobile server for on-demand queries in SQL and transformation of results into XML compliant documents and a stationary agent functioning as a client for query forwarding and conversion of resulting XML documents into CSV files. We have established that software agents can be used to connect distributed simulation models, developed with different general purpose simulation tools and databases, thus improving the connectivity and usability of simulation models in distributed information systems. Keywords: software agents, Java, XML, middleware, distributed simulation

Miroljub Kljajić

University of Maribor, Faculty of Organizational Sciences Cybernetics & DSS Laboratory Kidričeva cesta 55a, SI-4000 Kranj, Slovenia

Carlos A. Legna Verna

University of La Laguna, Department of Institutional Economics, Economics Statistics and Econometrics 38071 La Laguna, Spain

Andrej Škraba

University of Maribor, Faculty of Organizational Sciences Cybernetics & DSS Laboratory Kidričeva cesta 55a, SI-4000 Kranj, Slovenia

Povzetek

Background/Purpose: The present paper centers on the problems of decision making and decision support related to strategic public decisions. A methodological approach was developed to support decision-making where decision-makers are confronted with unexpected events. The methodology considers the fact that strategic decisions involve a large breadth of variables, qualitative and quantitative; and that they imply distributed and remote interaction between different actors.The approach is based on the building of qualitative models and the application of system dynamics for the development of a simulation model.Variables were identified which affect the sustainable improvement of the quality of life in the Canary Islands. The relationships between the variables are expressed as an influence square Matrix M with dimension n = 53. Each element of M may take values between 0 and 3. If aij =0, changes in variable Vi do not affect Vj. If aij takes a value between 1 and 3, it means that the changes in variable “i” produce changes in “j” proportional to prescribed gain.We used two methods to address the problem: the analysis of the driving- dependent forces and systems dynamics. Key words: qualitative modeling, system dynamics, strategic public decisions

Milan Nikolić

University of Novi Sad, Mihajlo Pupin Technical Faculty, 23000 Zrenjanin, Djure Djakovića bb, Serbia and Montenegro

Zvonko Sajfert

University of Novi Sad, Mihajlo Pupin Technical Faculty, 23000 Zrenjanin, Djure Djakovića bb, Serbia and Montenegro

Branka Nikolić

Sonja Marinković Primary School, 23000 Zrenjanin, Teplička 7, Serbia and Montenegro

Povzetek

Background/Purpose: This paper presents the methodology used in the research of a complex problem in business decision-making: determining the relative importance of criteria when selecting a new product. It facilitates obtaining recommendations for defining the relative importance of criteria and sub-criteria for selecting a new product depending on the current situation in the company (which is selecting the new product) and its setting. By applying this methodology, dependence of the criteria-relative importance for selecting a new product on the company’s degree of success can be determined. For that reason, the whole procedure has a dynamic character, and can be applied in different situations and at different times of observation. The recommendations obtained represent the input data and support for subsequent multicriteria ranking of alternatives for new products. The methodology is confirmed in practice; however this paper does not give ample details related to this, because of the aim of stressing the research procedure of criteria for selecting a new product, as well as its importance. Also, the applied procedure has importance because of its universality, given that it can also be applied to the research of the criteria for other decision- making issues, with or without adequate adaptations. Key words: methodology, research, criteria for selecting a new product.

Uroš Breskvar

University of Maribor, Faculty of Organizational Sciences, Kidričeva 55a, 4000 Kranj, Slovenia

Miroljub Kljajić

University of Maribor, Faculty of Organizational Sciences, Kidričeva 55a, 4000 Kranj, Slovenia

Povzetek

Background/Purpose: To have useful information has always been an advantage against competition. Simulation can be used as a tool to predict events in the future or to analyze and explain events that occurred in the past. “What will happen if I do that and/or that?” has always been the question of many people. Simulation can give an answer to this question. With computer and software development, simulation has become widespread and user-friendly tool. Simulation is also more and more used in optimization of production systems. But many problems occur in attempt to use simulation in production companies. In this article we will try to point out these problems and to stress the benefits of simulation. As the case of simulation project performance, scheduling problem by means of VIM and GA is demonstrated. Keywords: Simulation, manufacture, optimisation, scheduling, genetic algorithms, discrete simulation, visualization

Carlos A. Legna Verna

Department of Institutional Economics, University of La Laguna, Spain. 38071, La Laguna, Spain

Carina S. González

School of Computers Sciences, University of La Laguna, Spain, 38071, La Laguna, Spain

Povzetek

Background/Purpose: This paper presents the design of an IDSS that allows the decision makers to identify key issues that matter for the future of a social system and helps them to improve the policy-making processes. The implementation is in process, so this paper presents the achievements up to the present. It combines IA techniques comwith qualitative models and Systems Dynamic Simulation. The selection of strategies and policies for complex social systems needs to take into account nonquantifiable variables. For this reason, we build models that allow the treatment of these kinds of variables.We propose a methodology divided into three phases. In the first one we build a model and simulate dynamic systems of particular scenarios, using this module as an analysis tool. This phase allows the detection of issues that matters. The results obtained by simulation are stored in a database and are used as entries in the reasoning process. So, they are the start point of the second phase. For this phase we use the CBR (Case Based Reasoning) technique, where each case is defined by a set of norms (common attributes), cases and indexes (attributes for discriminating cases), problem, solution and explanation. Different values of these attributes will be new cases. The last phase produces different solutions, giving to the decision maker explanations about pros and cons of these alternatives. In the case that none of these alternatives are accepted by the users of the IDSS, they can incorporate a new solution explaining that, for them, it is the best alternative to follow. It is important to emphasize that the IDSS is an instrument to promote and facilitate the attainment of a coherence and consensus between the decision makers. Key words: Decision Support System, Case Based Reasoning, Public Decision, strategic decision making

Robert Leskovar

Faculty of Organizational Sciences, University of Maribor, Kidričeva cesta 55a, SI-4000 Kranj, Slovenia

Neja Zupan

Faculty of Organizational Sciences, University of Maribor, Kidričeva cesta 55a, SI-4000 Kranj, Slovenia

Povzetek

Background/Purpose: This paper describes the cellular automata- based simulation model of electronic commerce diffusion in small organizations. The model and method is verified with historical data. The focus and purpose of the research was to study long-term influences on electronic commerce caused by organisational characteristics in small organisations. Five maturity levels of electronic commerce were defined. The study found that the most influential factor of diffusion is “management support”.The dynamics of electronic commerce introduction and usage in non-innovator organisations were significantly influenced by the verbalisation process through business partners. The greatest progress toward upper maturity levels were detected when internal factors strongly predominated over external factors. The developed methodology shows new approaches for cellular automata usage in the study of organisational systems. Key words: small organization, cellular automata, electronic commerce, innovation diffusion

Miroljub Kljajić

University of Maribor, Faculty of Organizational Sciences Cybernetics & DSS Laboratory Kidričeva cesta 55a, SI-4000 Kranj, Slovenia

Carlos A. Legna Verna

University of La Laguna, Department of Institutional Economics, Economics Statistics and Econometrics 38071 La Laguna, Spain

Andrej Škraba

University of Maribor, Faculty of Organizational Sciences Cybernetics & DSS Laboratory Kidričeva cesta 55a, SI-4000 Kranj, Slovenia

Povzetek

Background/Purpose: This paper deals with the system dynamics model for decision-making, related to strategic decisions for the development of the Canary Islands. The quantitative model incorporates relevant variables, which affect the sustainable development of the quality of life on the Canary Islands. The relationship between the variables was formalized in the influence matrix. The influence diagram defines the connection between the elements of the matrix. The Following submodels were considered: Population, Tourism market, Agriculture, Environment, and GDP. The program package Powersim was used to build the simulation model. Several strategic scenarios are described and their dynamic response was analyzed. Presently the model is in the validation phase.The initial results are promising according to the positive validation results. Key words: system dynamics, simulation, model, decision support system, sustainable development, tourism

Miroljub Kljajić

Andrej Škraba