Vojnotehnicki glasnik / Military Technical Courier

7-13

Authors: Gaćeša Nebojša N.

In 2012, the Military Technical Courier, a scientific journal of the Ministry of Defense of the Republic of Serbia, marks the 60th anniversary of its regular and continuous publishing. The Military Technical Courier was founded by a decree of the Chief of the General Staff of the Yugoslav Army in August 1952 in order to continue the tradition of five reviews of military branches and services (Artillery Courier, Tank Courier, Military Engineering Courier, Courier of Communications in the Yugoslav Army and Logistics and Support of the Yugoslav Army) which had been covering tactics and technique issues from 1947 to 1952. According to the founding act, the main tasks of the Military Technical Courier were 'to consider and study issues regarding armament, technical and other material equipment of the branches and services concerning the knowledge of the materials, their handling, application, effects, storage, repair and upgrading as well as to deal with technical issues of the organization, war experience of logistic services and military traffic and evacuation'. Chief of the General Staff's decree of 16th December 1952 founding the first editorial board that 'has a directive to be responsible for the review editing' was followed by the first issue of the Military Technical Courier in January 1953. The Military Technical Courier will pay special tributes to the military technical publications published in our country before 1945 (in the Kingdom of Serbia, Kingdom of Serbs, Croats and Slovenians and later the Kingdom of Yugoslavia). The following reviews represent the foundations of the Serbian military technology reasoning: Artillery and Engineering Courier (1905-1906), Artillery Courier (1926-1932), Infantry and Artillery Courier (1933-1941), Engineering Courier (1929-1940), Aviation Courier (1927-1941) and Nautical Courier (1933-1940). There is no doubt that their quality and professional profiles paved also the way to today's Military Technical Courier; however, unfavorable historical reasons pushed them unfairly into the background of our memories. We are proud to continue their tradition as well. The journal has been publishing papers dealing with military technical resources and provisions as well as with development, production and exploitation of weapons and military equipment, enhancing its reputation in both military and civilian structures. The journal has developed from a publication for the education of officers in the period of scarce adequate military technical literature to a professional and scientific journal presenting scientific and technical achievements and information important for the development, production and exploitation of weapons and military equipment. The journal's structure, sections and areas of interest have changed with respect to the Army's technical and organizational development and modernization, following the journal's conceptual and editorial policy. During its 60 years of existence, the journal has been changing its characteristics, form and content, aiming to meet the requirements of both practice and science. From 1952 to 1961, it was a professional review for weapon military equipment and supply; until 1966, it was a professional review of the YA branches and services and a YA professional journal onwards. Owing to its editorial policy, the journal continued to improve its conception, orientation, quality and position thus becoming a scientific and professional periodical highly regarded not only in military circles but in academic and scientific circles in the country as well. It has held the title of a professional and scientific journal since 1989. According to the Opinion of the Ministry of Science and Technological Development No 413-00-1201/2001-01 of 12th September 2001, the Military Technical Courier is a publication of special interest for science. Being classified as a scientific journal of national interest by the Ministry of Education and Science of the Republic of Serbia, the Military Technical Courier is today a scientific journal publishing scientific and professional papers from the following categories: mathematics, information science and mechanics, electronics and telecommunications, mechanical engineering, materials and chemical technologies, industrial software and information technologies, geosciences and astronomy. The journal is in the Serbian Citation Index - SC index and is constantly monitored depending on the impact within the base itself and on the international (Thompson-ISI) citation indexes. Since 2011, an electronic edition of the Military Technical Courier has been available at www.vtg.mod.gov.rs in Serbian, Russian, English, German and French. Since 2012 editorial applying the on-line Electronic Editing (e-Ur) system (http://scindeks-eur.ceon.rs/index.php/vtg) developed by the Center for Evaluation in Education and Science (CEES). The application of the e-Ur service shows the readiness of the Military Technical Courier, supported by IT technology, authors and the CEON, to endure in making constant advances in the influence, quality and internationalisation of papers, the journal and the Scindex base, including the progress in adherence to international ethical and publishing principles. As a unique and competent publication on a national level, the Military Technical Courier publishes and verifies scientific and professional papers, those of the members of the Ministry of Defence and the Army of Serbia in particular, who thus have the opportunity to quantify their scientific and research results. The Military Technical Courier will continue to represent the scientific potential of the Army of Serbia and the Ministry of Defense of the Republic of Serbia and to support the efforts of institutions and individuals aiming at solving existing problems and making improvement in all areas of military technical science. Nowadays, the Military Technical Courier is not only an institutional resource being developed within the defense system from 1952, but also a brand of national interest. It has therefore become an open forum for the publication and stimulation of innovative thinking about all aspects of science and technology, coming from not only the Army and MoD members, but from the national and international community as well.

39-56

Authors: Milić Milićević R., Župac Goran Ž.

This paper presents an objective approach to determining criteria weights that can be successfully used in multiple criteria models. The methods of entropy, CRITIC and FANMA are presented in this paper as well as a possible combination of the methods of objective and subjective approaches. Although based on different theoretical settings, and therefore with different algorithms of realization, all methods have a decision matrix as a starting point. An objective approach to determining the weight of criteria eliminates the negative impacts of a decision maker on criteria weights as well as on the final solution of multicriteria problems. The main aim of this paper is to systematize description procedures as a kind of help when encountering a problem of determining the criteria weights for solving multicriteria tasks. A possibility of the method application is shown in a numerical example.

70-98

Authors: Mladenović Dragan D., Jovanović Danko M., Drakulić Mirjana S.

Cyber warfare is a specific new form of military conflicts the use of which is growing rapidly in the international community. However, its nature is specific and differs from all previously known forms of warfare. For the purpose of clear understanding of the nature of cyber warfare, this paper covers the basic groups of preconditions for its broad application and fast development from technological, military and social aspects. Understanding the true nature of cyber warfare is a necessary condition for building national capacities for its application that are military justified and harmonized with the international law. The paper explores the characteristic instances of cyber warfare, ranging from information propaganda to physical destruction, with the goal to determine guidelines for the possible development of cyber capacities at the national level. Based on the analysis of previous cyber warfare cases, a prediction of future development directions is made and the necessity to apply suitable methods and techniques for defense against them is analyzed.

115-135

Authors: Ćuk Danilo V., Abobaker Mostafa H.S., Mandić Slobodan D.

Modern tactical surface-to-surface missiles, equipped with strapdown inertial navigation systems, achieve very good accuracy compared with free-flight rockets. The probable range dispersion mainly depends on instruments errors and longitudinal disturbances such as rocket motor total-impulse deviation as well as differences between the estimated and actual values of the axial force and head wind. This paper gives an extension of the correlated velocity concept for surface-to-surface missiles without a thrust-terminating mechanism. The calculated parameters of the correlated velocity are stored into the memory of an onboard guidance computer. On the basis of the correlated velocity concept, the modified proportional navigation with the adjustment of the time-to-go of the missile to the target was proposed. It is shown that the new guidance law can compensate for the longitudinal disturbances of different levels successfully. The effectiveness of the proposed guidance method was confirmed by means of the calculated probable range and lateral dispersion for the anticipated disturbances in the guidance system.

152-168

Authors: Đurđević Mile B.

The modeling of casting processes has remained a topic of active interest for several decades, and availability of numerous software packages on the market is a good indication of the interest that the casting industry has in this field. Most of the data used in these software packages are read or estimated from the binary or multi-component phase diagrams. Unfortunately, except for binary diagrams, many of ternary or higher order phase diagrams are still not accurate enough. Having in mind that most of the aluminum binary systems are very well established, it has been tried to transfer a multi-component system into one well known Al-Xi pseudo binary system (in this case the Al-Si phase diagram was chosen as a reference system). The new Silicon Equivalency (SiEQ) algorithm expresses the amounts of major and minor alloying elements in the aluminum melts through an 'equivalent' amount of silicon. Such a system could be used to calculate several thermo-physical and solidification characteristics of multi component as cast aluminum alloys. This lends the model the ability to make predictions of solidification characteristics of cast parts, where cooling rates are slow and the solidification process has to be known in great detail in order to avoid problems in the casting. This work demonstrates how the SiEQ algorithm can be used to calculate characteristic solidification temperatures of the multi-component hypoeutectic Al-Si-Cu alloys as well as their latent heats. SA statistical analysis of the results obtained for a wide range of alloy chemical compositions shows a very good correlation with the experimental data and the SiEQ calculations.

183-200

Authors: Mrdak Mihailo R.

This paper analyzes the influence of plasma spray parameters on the microstructure and mechanical properties of NiCrBSi coatings deposited by the atmospheric plasma spray (APS) process. The microstructure and mechanical properties of plasma spray coatings are determined by the interaction of plasma ions with powder particles when the rate and temperature of plasma particles are transferred to powder particles. The interaction effect directly depends on the time the powder particles spend in plasma, and that time is defined by the deposition distance for each type of powder, depending on the grain size, melting temperature and specific mass. In order to obtain homogeneous and dense coatings, three distances (70,120 and 170 mm) from the substrate were used in the research. The coating of the best structural and mechanical characteristics was remelted and fused to the base in order to obtain a better structure. Self - fluxing NiCrBSi alloys are widely used because of the good resistance of boride, carbide and silicide solid phases to wear and corrosion. The morphology of powder particles was examined in the SEM (Scanning Electron Microscope), while the microstructure of the layers was assessed using a light microscope. The microstructural analysis of the deposited layers was performed in accordance with the Pratt-Whitney standard. The mechanical properties of the layers were assessed by applying the HV0.3 method for microhardness testing and tensile testing was applied to test bond strength.

216-234

Authors: Milojević Ivan S., Guberinić Rade V.

If demand is known for the whole planning period (complete information), then this type of demand or a supply system is deterministic. In the simplest cases, the demand per time unit is constant. If demand levels change over time following a precisely determined and pre-known principle, this type of demand is also classified as deterministic. This quality of demand is very rare. In most cases demand is the product of a process, for example TMS maintenance, whose progression cannot be predicted due to a number of factors influencing the process and causing random demand changes. In this case, a supply system must function according to the complete information and with a certain degree of uncertainty. In cases when demand may be defined by some of the laws of the probability theory, we are talking about stochastic demand and a stochastic supply system. Demand can be described by mathematical expectation, mathematical expectation and standard deviation, probability distribution or as a random process. However, there is usually a need for the most complex description, i.e. the complex random process because both intensity of demand and the probability distribution change during the observed intervals. The level of temporal (dynamic) series is traditionally considered as a complex phenomenon consisting of four components: - basic tendency of phenomenon development - cyclical impact (long-term, 'ancient') - seasonal effects - random fluctuations. The basic tendency of phenomenon development means a long-term evolution of phenomena. A function that expresses the trajectory of changes of the basic tendency of a phenomenon development in the form of the equation is called a trend. Often, the trend involves time regression; i.e. the coefficients of the proposed functions are often determined by the least squares method. To roughly determine the coefficients of the proposed function, the sum of three and three-point methods are also used. After checking the hypothesis of the existence of phenomenon change trends, the next step in the methodology of forecasting is the determination of a specific growth curve that describes the regularity of the development in time. These curves of growth are obtained by the analytical representation (expression) of dynamic lines. There are two basic stages in the process of expression and they are: - The choice of the type of curve the shape of which corresponds to the character of the dynamic order variation - the determination of the number of values (evaluation) of the curve parameters. The most widespread method of forecasting is the trend extrapolation. The basis of the trend extrapolation is the continuing of past trends in the future. The simplicity of the trend extrapolation process, on the one hand, and the absence of other information on the other hand, are the main reasons why the trend extrapolation is used for forecasting. The trend extrapolation is founded on the following assumptions: - The phenomenon development can be presented as an evolutionary trajectory or trend, - General conditions that influenced the trend development in the past will not undergo substantial changes in the future. Spare parts demand forecasting is constantly being done in all warehouses, workshops, and at all levels. Without demand forecasting, neither planning nor decision making can be done. Demand forecasting is the input for determining the level of reserve, size of the order, ordering cycles, etc. The question that arises is the one of the reliability and accuracy of a forecast and its effects. Forecasting 'by feeling' is not to be dismissed if there is nothing better, but in this case, one must be prepared for forecasting failures that cause unnecessary accumulation of certain spare parts, and also a chronic shortage of other spare parts. All this significantly increases costs and does not provide a satisfactory supply of spare parts. The main problem of the application of this model is that each spare part has its own failure intensity; therefore, it is necessary to conduct a complete procedure for each part. If the average number of components of a complex asset were about 5000, along with the existence of a large number of resources, the forecasting by the trend extrapolating would practically require the newest information technologies. However, the analysis shows that in most cases 80-90% of component parts have a longer life than the asset itself. In addition, it is shown that during the life of the asset, these components do not fail, and that 10-15% of component parts have only rare failures (post optimal analysis of spare parts normative) or do not show any failing tendency meaning that failures are random. This procedure remains to be applied to 2-4% of component parts. It does not present a significant problem due to the process automation. This model enables us to determine the parts to which the trend extrapolation procedure should be applied. Forecast is obtained by the use of the second model to existing data. The trend extrapolation forecast or any other kind of forecast does not need to be done for those spare parts for which the long time forecast is close to zero. Provision of spare parts for the maintenance system considering the range, quantity, time and place is crucial for successful functioning of the maintenance system and ultimately for the accuracy of material resources. On the other hand, stocks of spare parts are costly and required to be reduced. Costs need to be minimized while ensuring the successful functioning of the maintenance system.

250-265

Authors: Markagić Milorad S.

Along with the development of confidentiality of data and resources, there is a need to develop systems that would provide confidentiality. Currently, the most used systems are classical cryptographic systems and encryption public key systems. However, none of these systems provides a solution for the famous 'catch 22' of cryptography. Owing to the intensive development of quantum mechanics, in the last 30 years emerged an entirely new kind of cryptography-quantum cryptography. Its greatest contribution is a possibility to discover an intercepted communication channel from a third party. The question is: is this really true? The question arises: 'If the quantum cryptography is so good, why is not widely used?' The aim of this paper is, on the one hand, to define the basic mechanisms of quantum cryptography IP, and, on the other hand, to point to the shortcomings, as they related to the opportunities of today's devices and flaws in protocols.

284-298

Authors: Jeremić Radun B.

In the last ten years, the Serbian Army has been facing the problem of surplus of various ordnance, which resulted from the changes in the organizational structure and rationalization. In addition, at several locations in Serbia there is still a large amount of unexploded ordnance remaining after the NATO bombing. The paper examined the environmental aspects of the destruction of surplus ammunition and unexploded ordnance. A brief survey of the methods of destruction and the technological conditions for their implementation are presented. The impact of toxic constituents of ordnance on human health and the environment is analyzed in particular. In order to minimize environmental risks during the demilitarization process of ordnance, appropriate proposals are given.

307-311

Authors: Đurković Vlado P.

The article does not contain abstract.