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Vojnotehnički glasnik
2010, vol. 58, iss. 1, pp. 129-145
article language: Serbian
document type: Professional Paper
doi:10.5937/vojtehg1001129B


Evaluating locations for river crossing using fuzzy logic
Vojna akademija, Prodekanat za planiranje i organizaciju nastave, Beograd

e-mail: dbozanic@yahoo.com

Abstract

The managing process in every organization is developed by making appropriate decisions and by their transformation into actions. The managing process is, therefore, often considered as equal with the decision making process, which shows that decision making plays a significant role in the managing process of organizations. Managing efficiency as well as functioning and development of every organization depends on decision making correctness, i.e. on the correctness of undertaken actions. The Serbian Armed Forces is an organizational system where the managing process is carried out as well. The levels of decision importance in the Army are different, from daily-operative to strategic ones, but the importance of the decision making process itself is equal, regardless the level of decisions. Decision makers sometimes face situations when they have only one action and in that case the decision making process is reduced to either accepting or refusing the action. However, decision makers often face a situation when, by ranking many offered actions, they decide which one is the best. Ranking itself is carried out by evaluating offered actions, and the selection is made based on the best results of an action. These conclusions require a careful and systematical approach to the decision making process, regardless the decision type, since any wrong decision leads to the weakening of the combat readiness of The Serbian Armed Forces. The paper shows the stage in the decision making process during the selection of a pontoon bridge location for the purpose of overcoming water obstacles. The decision making process includes a higher or lower level of indefiniteness of criteria needed for making a relevant decision. Since the fuzzy logic is very suitable for expressing indefiniteness and uncertainty, the decision making process using a fuzzy logic approach is shown in the paper. Characteristics of multi-criteria methods and selection of methods for evaluation With the development of the evaluation theory, evaluation models were being developed as well. Different objectives of evaluation and other differences in the whole procedure had an impact on the development of the majority of evaluation models adapted to different requests. The main objective of multi-criteria methods is to define the priority between particular variants or criteria in the situation with a large number of decision makers and a large number of decision making criteria in repeated periods of time. Main notions of fuzzy logic and fuzzy sets In a larger sense, the fuzzy logic is a synonym for the fuzzy sets theory which refers to the class of objects with unclear borders the membership of which is measured by certain value. It is important to realize that the essence of the fuzzy logic is different from the essence of the traditional logic system. This logic, based on clear and precisely defined rules, has its foundation in the set theory. An element can or cannot be a part of a set, which means that sets have clearly determined borders. Contrary to the conventional logic, the fuzzy logic does not define precisely the membership of an element to a set. The membership value is expressed in percentage, for example. The fuzzy logic is very close to human perception. Fuzzy system modeling for evaluation of selected locations The fuzzy logic is usually used for complex system modeling, when it is difficult to define interdependences between certain variables by other methods. The criteria for the selection of locations for crossing water obstacles are: water obstacle width, water obstacle flow rate, quality and number of access roads and volume of works around the bridge and on terrain all the way to the access roads. In the fuzzy system for evaluating offered locations, the input criteria values are presented in numbers or linguistic expressions. The fuzzy system is composed of four input linguistic variables and one output linguistic variable - decision preference for the selection of a particular location. For defining rules in a fuzzy logic model, the data obtained from the interviewed infantry officers who took part in the selection of a pontoon bridge location were used. Fuzzy system testing The valley of the Juzna Morava River between the towns of Bujanovac and Vladicin Han, with the towns of Vranjska Banja, Kobrevac and Gramada, was chosen for testing the described model. Vranjska Banja was chosen as the most appropriate pontoon bridge location in crossing the Juzna Morava River between Bujanovac and Vladicin Han, because the highest degree of preference was obtained as an output linguistic variable from the fuzzy system.

Keywords

decision making; fuzzy logic; water obstacle

References

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