Vojnotehnicki glasnik / Military Technical Courier / Военно-технический вестник

The plasma spray process is a leading technology of powder depositing in the production of coatings widely used in the aerospace industry forthe protection of new parts and for the repair of worn ones. Cermet 75Cr3C2 - 25Ni(Cr) coatings based on Cr3C2 carbides are widely used to protectparts as they retain high values of hardness, strength and resistance to wear up to a temperature of 850°C. This paper discusses the influence of theparameters of the plasma spray deposition of 75Cr3C2 - 25Ni(Cr) powder onthe structure and mechanical properties of the coating. The powder is deposited using plasma spraying at atmospheric pressure (APS). The plasmagas is He, which is an inert gas and does not react with the powder; it produces dense plasma with lower heat content and less incorporated ambient air in the plasma jet thus reducing temperature decomposition and decarburization of Cr3C2 carbide. In this study, three groups of coatings were deposited with three different powder feed rates of: 30, 45 and 60 g/min. The coating with the best properties was deposited on the inlet flange parts of theturbo - jet engine TV2-117A to reduce the influence of vibrations and wear. The structures and the mechanical properties of 75Cr3C2 - 25Ni(Cr) coatings are analyzed in accordance with the Pratt & Whitney standard. Studieshave shown that powder feed rates have an important influence on themechanical properties and structures of 75Cr3C2 - 25Ni(Cr) coatings.

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Разработана молекулярно-кинетическая теория работы винта с поверхностью Мёбиуса и осуществлено компьютерное моделирование в различных условиях эксплуатации такого винта. Применение механизации винта с поверхностью Мёбиуса позволяет в определенных условиях использовать такой винт в качестве вихревого теплового насоса. Проведена экспериментальная проверка разработанной теории работы винта с поверхностью Мёбиуса в лабораторных условиях.

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Применение способа разминирования вымыванием взрывчатого вещества растворителем позволяет сохранить большие материальные ценности, снижает риск для пиротехников, связанный с перемещением боеприпаса к месту утилизации. Затраты на специальное оборудование незначительны. Технология легко поддается автоматизации, за счет электронного и телеуправления процессом сверления на расстоянии, что снижает риск подрыва пиротехников к минимуму. Способ будет эффективен в зонах действия против партизанской минной войны.

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The kinetic study of the crystallization process of the α-Fe phase from the amorphous Fe81B13Si4C2 alloy was investigated by DSC and XRD techniques. The kinetic parameters (lnA, Ea) of the investigated process were determined using the Kissinger and isoconversional (model-free) methods. It was established that the α-Fe crystallization process can be described by the JMA (Johnson-Mehl-Avrami) kinetic equation. In accordance with the XRD analysis and the calculated crystallization parameters (n = 4; m = 3), it was concluded that the crystallization stages of the considered process can be described by the bulk nucleation and the three-dimensional (3D) growth of nuclei.

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Limited resources in the defense domain impose the acceptance of an analytical, essentially economic, management point of view. There is a necessity to use available resources rationally and to implement sustainable development strategies, defined on the basis of proper understanding and analyses of internal and external environment.

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Cryptography is as current as ever. The need to protect data and resources from unauthorised access and use has never ceased. This resulted in creating stronger protection and breaching most of those thought to be unbreachable. This paper analyses core problems and their implementation in breaching the translational cipher by using the programme language C.

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The efficiency of special purpose radio-communications depends on transport layer protocols. Meny factors have an impact on special purpose radio-communications efficiency, as well as TCP and UDP protocols. This paper presents the transport protocols throughput analysis in the HF and VHF radio-communications versus RTT and packet error rate probability. This paper considers a posibility of the application of TCP and UDP protocols in special purpose radio-communications. The following factors will be considered: RTT, Round Trip Time, data packet size, window size and bit error rate. It can be seen from the analysis which transport protocol is the most suitable for special purpose radio-networks.

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Education on the protection of classified information should be the top priority when it comes to ensuring the protection of the vital interests of the state. Some information should not be made available to the public because it is mainly related to national security, and no one should question the need to protect this kind of data. This paper is intended for educators dealing with the protection of classified information, and especially to those who work with or come into contact with confidential information in order to inform them of our national system of protection of classified information and enable the implementation of the existing legislation applying the heuristic model of education. This article describes the legal regulations governing the protection of data and shows mandatory standards and measures for the protection of classified information.

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Complex technical systems are different in comparison with other technical systems due to their complex constructions and assignments such as protection of human resources, material resources or a territory. In order that complex technical systems work correctly and have a satysfactory level of reliability and readiness, the maintenance and overhauling of such systems must take into consideration their specific technological and technical characteristics. The maintenance and overhauling of these systems must be programable and a QMS must be integrated in the maintenance and overhauling process through the whole system. The organization of complex technical systems maintenance in the Technical Overhauling Institution in Cacak for the Defence system of the Republic of Serbia is an example of such a system whose maintenance process is based on a process model of the QMS. This paper describes the maintenance and the overhauling process of Complex Technical Systems with its QMS process model which is a prerequisite for an effective and efficient maintenance and overhauling process. The overhauling process is illustrated on an example of overhauling a millitary tracked vehicle.

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Protection when handling construction machinery and construction work is a significant and important factor in the whole complex process of construction. Careful handling to protect human lives and the environment as well as building materials themselves is necessary. Careful and good handling and performance can lead to financial savings and to avoiding additional costs. Protective measures to be taken are: protection from risk during construction and protection from exploitation of the danger of the object. This area is defined by strict legislation. The Law on safety and health at work prescribed measures whose implementation and enforcement ensure safety and health at work. In addition, the law governs the rights and obligations of employers and employees to allow for more complete implementation of safety measures at work. Analyses of legal provisions show that the responsibility for creating and maintaining safe work environment lies with both employers and employees, who, each in a manner appropriate to their role in the process of work, comply with the prescribed measures.

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Nowadays, the knowledge of using the amphibious transporter STMM ( STM-M) is very limited. A small number of professional soldiers in the Serbian Armed Forces know how to use thisvery useful and high-quality military vehicle in a regular way. From the day onethis vehicle has remained in its basic shape without any modifications since it was made in the former Soviet Union. Today, the Serbian Armed Forces have only 12 of these vehicles in the operational use. The Serbian Armed Forces have two amphibious platoons in two pontoon batalions in the River Flotilla. As the author of this article was an officer in charge of maintaining this complex and “unusual” vehicle, the article deals with the provisions from the Regulations on preventive measures for safety and health while using work equipment (Ministry of Labour, 2012), applied to work with STM-Ms, The article makes a parallel between the provisions of the Regulations and the actual situation and specific conditions of using and maintaining STM-Ms .

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