The paper presents the results of simulation tests of the entry of a floating transporter to a water obstacle. The simulation tests were performed with the use of LS Dyna program, based on the finite ...element method (FEM). The computational model was developed and used in the simulation of the manoeuvre of entering the water obstacle for the extreme conditions, which are described by NATO standards. For a model, as an example vehicle, the floating transporter PTS-M was used. The results of the application of the elaborated model confirmed the possibility to utilise the method to verify the behaviour of a vehicle in a very important and difficult problem from the point of view of vehicle safety conditions.
The article deals with a solution of selected problems associated with evaluation of armoured vehicles flotation ability. Main attention is devoted to analysis of possible methods of vehicle ability ...evaluation to pass over a water obstacle with respect to its current speed.
U radu je prikazana faza u procesu donošenja odluke pri izboru lokacije za uspostavljanje mosnog mesta prelaska radi savlađivanja vodenih prepreka. Proces donošenja odluke propraćen je većim ili ...manjim stepenom neodređenosti kriterijuma koji su neophodni za donošenje relevantne odluke. Pošto je fuzzy logika veoma pogodna za izražavanje neodređenosti i neizvesnosti, u radu je prikazan proces donošenja odluke primenom fuzzy pristupa. / 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.
The aim was to examine whether a combat uniform (CU) influences the cadet's exercise performance in and out of the water.
Fourteen male Army Officer cadets performed on 6 separate days: (1) a maximal ...400-m freestyle swimming trial; (2) a 4 x 50-m all-out freestyle swimming trial with 10 s rest in between; (3) a 50-m swim obstacle course with a CU (CUs); (4) a 50-m swim obstacle course without a CU (NUs); (5) a 1000-m track run with a CU (CU(R)); and (6) a 1000-m track run without a CU (NUR). In each trial, performance time, oxygen uptake (Vo2), lactate concentration (La), and capillary oxygen saturation (SpO2) were recorded.
The mean performance time was 44.3 +/- 3.1 s and 33.4 +/- 1.8 s in CUs and NUs trials, respectively. Peak VO2 was similar in CUs, NUs, and 400 m (CUs: 59.1 +/- 1.1 ml x kg(-1) x min(-1), NUs: 57.3 +/- 2.1 ml kg(-1) x min(-1), 400 m: 58.2 +/- 1.6 ml x kg(-1) min(-1)). La was higher in CUs than in NUs (CUs: 10.0 +/- 2.0 mmol x L(-1), NUs: 8.5 +/- 1.8 mmol x L(-1)), but it was lower in CUs and NUs than during the 400 m and 4 x 50 m. SpO2 was lower (approximately 4.5%) in CUs than NUs. No differences were observed between running trials.
The results suggest that the use of CU during swimming tasks induces high demands for energy and, thus, leads to a significant impairment of the swimming performance of the cadets. However, the influence of the CU seems to be less crucial during dry land running performance.
A new method for quantitative study of small mammals swimming across water obstacles was developed. A line of 25 traps was installed on either poles or boards (“rafts”) with anchors at a distance of ...20–25 m from the bank and with 10-m distances between the items. The study was performed upstream along the Ilych River in August 2013. A total of 300 trap/day were accumulated. Twenty-four small mammal individuals of 8 species were captured. Their relative abundance was estimated as the number of individuals per 100 trap/day. It was found experimentally that floating poles neither repel nor attract animals. When an individual accidentally finds a floating pole, it climbs up and explores it for some time. The number of animals per total length of rafts per time unit can be suggested as an index of intensiveness of migration across a water obstacle. In the area studied, the number of small mammals of various species crossing the river was estimated at 26.7 individuals per 1 km/day. A length of 5 m for floating poles/boards and installation of two traps at the ends of an item is suggested to be used.
The impact of natural and artificial obstacles on the execution of modern combat operations is enormous. Finding a way to make the operational units more independent of the equipment for water ...obstacles remains an enigma for the materiel constructors. The paper presents the impact of the characteristics of water obstacles on the preparation and execution of the Land Forces offensive operation in terms of the selection of materiel and the location for crossing water obstacle. The selection of the location for crossing water obstacle has been made by implementation of one of the methods of multi-attribute decision-making, that is the method of linear ranking. The linear ranking method has been used in combination with the scheduling method. The paper emphasizes the importance of implementing multiple-criteria decision-making methods in the military decision-making process.
Assessment of risk in overcoming the water obstacles during a defensive operation of the Army forces is an important factor for the successful execution of the mission. High-quality risk assessment ...provides the decision-makers with a more complete understanding of the situation and creates a possibility for risk management as a precondition for successful overcoming of water obstacles. For the estimate to be well done, a fuzzy logic system has been developed, by which a range of data relevant for the risk assessment is processed with a final aim to obtain quantitative risk values. The paper defines relevant criteria that have an effect on the risk assessment and are the input values for the fuzzy logic system.
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