Vojnotehnicki glasnik / Military Technical Courier

263-272

Authors: Korolija Dušan

Increased demands for low cost of hardware, small size and low power consumption of equipment in cellular mobile communications have driven designers to resurrect the direct conversion receiver. Long abandoned in favor of the mature superheterodine receiver, the direct conversion receiver has emerged over the last decade. Direct conversion reception has several qualities which makes it very suitable for integration as well as multi-band multi-standard operation. This paper describes the characteristics of the direct conversion receiver as well as the inherent imperfections of the superheterodine receiver from the aspect of integration.

280-287

Authors: Tot Lajoš

These investigations included experimental and theoretical study of acetone vapours influence on the propellant mechanical properties. The tests were carried out on two defined propellants. Herein shown are the results of the mechanical tests of both non-treated and treated propellants as well as an attempt to explain the observed phenomenon.

300-308

Authors: Demić Miroslav

Steering wheels vibrations around king pins, known as "shimmy", produce a harmful influence on motor vehicle steering parameters. They appear to be a result of the influence of road irregularities, clearance in the steering system, wheels unbalance, wheels and tires nonuniformity, etc. In a vehicle steering system design process, an optimal choice of vehicle parameters is of major importance for minimum values of wheels shimmy. This paper presents an attempt to model a truck steering system with power and mechanical steering so as to study steering wheels shimmy.

320-330

Authors: Cvijović Milanko

The study analyzes the forces affecting a parachuting system at the moment of its opening at different heights and flight velocities. The strain peak occurs at the moment when the filling of the parachute cupola with air is to be finished. Therefore, a special attention during calculations is paid to the cupola and the elements connecting it with the rest of the parachuting system. The study presents the calculation methodology for a parachuting system without a brake-parachute and for systems with one or more brake-parachutes.

145-154

Authors: Galović Danijela

The problem of inventory control of spare parts in a hierarchical two-level system in uncertain environment is considered. The hierarchical two-level system consists of one central depot and N branch warehouses. A demand of each kind of treated spare parts is uncertain and modeled by fuzzy numbers. A new procedure of classification according to the fuzzy ABC method is developed. The control models are determined for spare parts of great importance. A new fuzzy mathematical model for determining the optimum order quantities of the central depot and branch warehouses is presented. The values of unit procurement price, unit holding costs and unit shortage costs are deterministic. The developed procedure for the classification and the algorithm for determining the optimum order quantities is illustrated by an example.

166-175

Authors: Medan Branko, Đorđević Momčilo, Veselinovič Dejan

The technical support service in the Army has a great importance within the frames of combat service support. By the application of information technology in the planning of work of the Technical support service and by controlling the plan realization, the following is ensured: the most rational utilization of available resources, the balanced employment of staff elements and personnel within the frames of combat service and the most efficient realization of plans. This program is applied for observing the realization of the maintenance process in a technical company and it is apart of the logistic information system.

184-194

Authors: Građin Zoran

Ecological trends and movements in the modern world grow stronger and more active, due to a real danger of Earth pollution. One of the main sources of pollution are 1C engines and their influence on environment is significant. However, conventional combustion engines still are and will be dominant powering systems for numerous future applications. Two solutions are possible answers to this problem: first, the replacement of conventional fuels by alternative ones and second, modifications on the 1C engine design in order to decrease fuel emission and consumption. One of the solutions for the improvement of 1C engine design is the modification of engine parts or their design, with great influence on the decrease of mechanical losses, especially on partial rating. Therefore, it is important to say that complex problems of engine (automotive) decrease of fuel consumption and exhaust gas emission can be solved only by simultaneous development of oil and engine (automotive) industry

202-207

Authors: Anđelković-Lukić Mirjana

The paper deals with production processes of manufacturing and coating Ugh explosives which pollute environment with waste waters. Some methods of refining waste waters before letting them into open water current are presented.

14-27

Authors: Erić Miljko M., Dukić Miroslav L., Pokrajac Ivan

The MUSIC based Direction of Arrival estimation using the ADCOCK antenna arrays is considered. Starting from signal model formulation, the cost function of the MUSIC algorithm and the ambiguity functions for the ADCOCK antenna array have been formulated. Some simulation results and some preliminary results of the verification in practice are presented.

36-41

Authors: Stojanović Miroslav, Bulajić Đuro, Rakić Vladimir

We presented the results of the realization of the logistic information system. While fulfilling this task we connected computers physically and succored logical functioning of the system on three levels (command management and execution level). We designed software, using modern software development tools and worked on the education of professional military officials for PC using and basic maintenance of computer equipment.

50-60

Authors: Živković Dejan, Basarić Gradimir, Jovelić Stojan

The aim of the work was to measure the whole body vibration on helicopter pilot seats in two types of helicopters with jet engines and to accomplish the third octave analysis of whole body vibration acceleration in all three axes. The results of measurement on the first type of helicopters showed that the highest acceleration levels were in third octave band with the mid frequency of 16 Hz. The highest whole body vibration acceleration values were for the following regimes: the regime of levitation and the regime of horizontal flight with a speed of 250 km/h. The permissible exposure time periods for these acceleration levels were around 5 hours. The results of measurement on the second type of helicopters showed that the highest acceleration levels were in the third octave band with the mid frequency of 6,3 Hz. The highest whole body vibration acceleration values were for the following regimes: the regime of turning point and the regime of horizontal flight with a speed of 200 km/h. The permissible exposure time periods for these acceleration levels were around 3 hours. The acceleration levels in X or Y axes for both types of helicopters, in all regimes and all third octave bands, were very far below from the exposure levels for 24 hours. Since the pilots 'continuous exposure in the investigated regimes of flights is below these mentioned time periods, we can conclude that the whole body vibration levels do not have significant effects on the pilots' working ability.

73-81

Authors: Borisov Mirko

The article deals with the analysis of deformations of geographic map contents and the procedure of eliminating deformations. Geographic maps are used for visualizing and studying geospatial data and for identifying metric features. For that reason the accuracy analyses are very important as well as the elimination of all possible deformations of the maps.

90-100

Authors: Pokorni Slavko

The article does not contain abstract.

555-570

Authors: Debeljković Dragutin Lj., Jovanović Mića B., Milinković Stevan A.

Singular systems are those the dynamics of which is governed by a mixture Of algebraic and differential equations. In that sense the algebraic equations represent the constraints to the solution of the differential part. These systems are also known as descriptor, semi-state and generalized systems. They appear as a linear approximation of systems models, or linear system models in many applications such as electrical networks, aircraft dynamics, neutral delay systems, large-scale systems, interconnected systems economics, optimization problems, feedback systems, robotics, etc. The basic dynamic analysis in time domain is devoted to the question of stability in the sense of Lyapunov as well as in the sense of finite time stability. Besides that, it is of particular interest to maintain the systems characteristics under the action of undesirable perturbations. This question is in the connection with the problems treated well by the modern concept of stability robustness within the area of control engineering.

580-594

Authors: Ristić Zoran, Ilić Slobodan, Davidović Mile

A numerical solution of a model for the hydraulic recoil brake in the artillery weapon is presented. A program solution and an algorithm for the identification of dynamic recoil brake parameters and the recoil process simulation have been worked out in the procedure of numerical modeling. The analysis of the influence of hydraulic brake input parameters on the level of estimated parameters has been performed as well as the optimization of estimated parameters to according to defined limitations.

612-621

Authors: Građin Zoran B.

Influences of up-to-date design trends and ecology requirements on working conditions of actual lubricants in internal combustion engines were considered in the paper. Designs with reduced dimensions and designs with high thermal and mechanical efficiency are favourised in IC engine development. The increase of diesel engine break power for commercial trucks is continuing. At the same time, requirements for further increase of reliability and lifetime are established. Additionally, demands for further emission reduction require low oil consumption (0,5 g/kWh and lower), even for charging diesel engines. All this implies that very high thermal loads can be expected. The trend of the lubricant use decrease appeared in developed countries in the early 1990s. This is not surprising, because the ecotoxicological impact of lubricants became a big problem. Thus, an intensive research for new principles of lubrication, based on new lubricants and new friction materials, is in progress.

638-650

Authors: Brčić Krsta

The topic of this paper is using the programmable logic controller (PLC) connected with a PC in order to control equipment in training areas. PLCs are typically designed to withstand high amounts of impact and vibration in industry. Personal computer technology is an extraordinary powerful platform for innovators in finding the solution to the problem of automatic control. Such systems can provide economical full featured monitoring and control solution. In order to explain the problem, we will show one example of a target control system in an infantry training area.

391-403

Authors: Andrejić Marko, Andrić Andreja, Stojanović Nikola

The paper presents an expert system to support decision making in the field of diagnostics of equipment defects in joint tactical units. The theoretical bases of diagnostics and expert systems are briefly presented as well as the structure of a developed expert system, the method and the effects of its application. The developed system comprehends the Knowledge of experts in design, diagnostics and maintenance of equipment in joint tactical units as well as corresponding literature data. The guidelines for improving the developed expert systems have been proposed.

412-423

Authors: Gardijan Petar

In this paper, on the basis of the known methods of failure analysis developed primarily for electronic devices FMEA and FMECA, the possibility of their application on a complex machine conditioned the development of an 'adjusted' method of the working of FMECA. The practical application has shown that the information gained by using this methodology of failure analysis can indeed be of assistance in all phases of a machine lifetime.

429-438

Authors: Miškovic Vladislav

This paper considers the application of inductive machine learning methods in data mining and knowledge discovery in databases tasks. Some characteristics of the author's noncommercial System for Data Mining and Knowledge Discovery are presented as Well as the experimental comparison of its inductive rules learning component with some best known systems from the same category.

452-465

Authors: Đorđević Aleksandar B., Karanović Dušan M.

The discharge curve of a cell/battery was defined either as a set Of ordered pairs: voltage, Vt vs time, ti = ti-1 + ∆t or time, ti vs discharge voltage, Vi, where U0 > Vi > V cutoff. In addition to the experimental measured discharge curve, the cell relaxation curve needs to be monitored. The Calculated Discharge Curve Method (CDCM) was developed to improve cell/battery monitoring as well as its characterization. The CDCM may be used for type qualification, product acceptance, and periodical test during service. The Algorithm procedure was presented. The Alkaline manganese cell LR 20-VARTA load 10 Ω, at ambient temperature, was used for the CDCM demonstration. The mathematical calculations were conducted on an IBM personal computer using the Symphony software.

478-483

Authors: Anđelković-Lukić Mirjana

In this paper different processes of coating high explosives HMX with different polymer materials are given. A process of coating depends on used polymers and waxes. Some formulations are presented, based on HMX and bonding agents (polymers and waxes) and their effects on detonation velocity.

496-503

Authors: Pokorni Slavko

(not available in English) Pasivni dipoli i IC mamci i dalje su najjeftiniji i najisplativiji način protivelektronskih dejstava u odnosu na postignuti efekat zaštite aviona od radarski i IC samonavođenih raketa i sistema za praćenje. To je i najčešće korišćen oblik protivelektronskih dejstava kada se radi o vojnim avionima. Osim u vazduhoplovstvu, sve više se primenjuju i u zaštiti brodova, pa i borbenih sredstava na kopnu, kod kojih se koriste i sredstva za zadimljavanje. Mogu da ih nose i koriste skoro sve vrste platformi, od aviona svih tipova, preko bespilotnih letilica, jedrilica padobrana, balona, do brodova i oklopnih borbenih vozila. Osnovne tendencije u razvoju pasivnih mamaca ogledaju se u pronalaženju pogodnijih materijala novih tehnika za njihovo izbacivanje u okolinu štićenog objekta i boljeg prilagođavanja spektralnim osobinama zračenja štićenog objekta. Pasivni dipoli, IC mamci i aktivni mamci mogu se izbacivati na razne načine, a način izbacivanja ima veliki uticaj na njihovu efikasnost. Većina mamaca izbacuje se uređajima sličnim minobacaču ili topu. U razvoju, a i upotrebi nalaze se tzv. pametni izbacivači, a teži se izradi modularnih unificiranih izbacivača dipola i IC mamaca. Pored pasivnih, sve više su u upotrebi aktivni mamci, od kojih se očekuje mnogo, posebno od aktivnih mamaca povezanih optičkim kablovima sa platformom koja ih nosi. Procenjuje se da, za sada, aktivni mamci nisu zamena za pasivne i da ih neće potpuno istisnuti iz upotrebe, već da najbolje rezultate može dati zajednička (kombinovana) upotreba.