The aim of this study was to optimize the parameters of the plasmaspray and to deposit WC17Co layers with optimal structural - mechanical characteristics. The powder was deposited by the plasma spraying process at the atmospheric pressure (APS). When choosing the parameters, the flow of the He plasma gas was taken as the basic parameter. In relation too their gases, helium does not react with the powder,it produces a denserplasma with a lower heat content and it incorporates less ambient air into the plasma jet which reduces decarburization of the powder. The study shows three groups of samples obtained with three plasma gas flows of 12,22 and 32 l/min He. The coating with the best properties was deposited onthe shaft sleeve of the main rotor of the Gazelle H42 helicopter, in order to reduce the influence of vibrations and bearings on sleeve wear up to 500°C.The estimates of the WC17Co layers of the coating were made on the basis of their structural -mechanical properties. The surface morphology of the WC17Co powder particles was examined on the SEM. The mechanical properties of the deposited coatings were tested in accordance with the ‘TURBOMECA’standard. The estimate of the mechanical properties of layers was done by examining microhardness with the method HV0.3 and bond strength with tensile testing. Metallographic assessment of the pore proportion in the layers of the WC17Co coating (image analysis) was performed with the technique of light microscopy in accordance with the ‘Pratt & Whitney’ standard. Studies have shown that the rate of the plasma gas flow significantly affects the mechanical properties and the structure of coatings.
Vojnotehnicki glasnik / Military Technical Courier / Военно-технический вестник
2013. — Выпуск 3
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Dynamic simulation, based on modeling, has a significant role during the process of vehicle development. It is especially important in the first stages of vehicle design, when relevant vehicle parameters are to be defined. Shock absorbers as executive parts of vehicle semi-active suspension systems suffer thermal loads, which may result in damage and degradation of their characteristics. Therefore,this paper shows an attempt to analyze converting of mechanical work into heat by using the dynamic simulation method.
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The paper gives the results of work on melting, pouring, forging and heat treatment of 415-ton 45H3M1F steel ingots as semiproducts for manufacturing large backup rolls at the request of «Severstal» Company. For the production of rollers, a new grade of steel based on 0.45%С and 3%Cr, additionally alloyed by Mo and V, was developed in PJSC «Energomashspetsstal» and applied in industry. Steel of bainite class provides the best combination of strength and plasticity properties. Metal was prepared by melting 7 heats in arc steel-melting furnaces with the capacity of 100 and 50 tons with subsequent out-of-furnace treatment on ladle - furnace and ladle - degassing units. The pouring of steel was carried out from four steel-pouring ladles into a vertical mould under vacuum through a tundish ladle with the protection of stream by argon. The forging of ingots was conducted on the automated 150MN forging system. The obtained billets were exposed to primary heat treatment which consisted of heating for recrystallization, isothermal soaking, in order to provide the removal of residual stresses, additional dehydrogenization to give the material lower hardness and controlled cooling for the prevention of snowflake formation. Heating of ingots for forging and preliminary heat treatment was carried out in heat treatment furnaces with the carrying capacity of up to 500 tons. For the heat treatment of the backup roll, a horizontal sprayer unit was applied. The tooling of the backup roll was executed on a lathe with one pace-plate and the final mechanical treatment was conducted on the machine-tool of Hercules NWD 1500×18000 CNC. Finished products with 225-ton mass of the following dimensions: a barrel with a diameter and a length of 2,360 mm and 4,800 mm, respectively, at a general length of 10,650 mm were obtained.
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Pyrotechnic robots are service robots used to reduce the time for intervention of pyrotechnic troops and to diminish the danger for the opera tors. Pyrotechnic robots are used to inspect dangerous areas or/and to remove and to destroy explosive or suspicious devices/objects. These robots can be used to make corridors through mined battle fields, for manipulation and neutralization of unexploded ammunition, for inspection of vehicles, trains, airplanes and buildings. For these robots, a good functional activity is determined with regard to work space dimensions, robotic arm kinematics and gripper characteristics. The paper shows the structural, kinematic, static synthesis and analysis as well as the design and functional simulation of the robotic arm and the grippers attached on the pyrotechnic robot designed by the authors.
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In this paper, an overview of the algorithms for access control in mobile wireless networks is presented. A review of adaptive control met hods of accepting a call in WCDMA networks is discussed, based on the overview of the algorithms used for this purpose, and their comparison. Appropriate comments and conclusions in comparison with the basic characteristics of these algorithms are given. The OVSF codes are ex plained as well as how the allocation method influences the capacity and probability of blocking.
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The synthesis of metallic nanoparticles from the precursor solution of salts using the ultrasonic spray pyrolysis method was considered in this work. During the control of process parameters (surface tension and density, the concentration of solution, residence time of aerosol in the reactor, presence of additives, gas flow rate, decomposition temperature of aerosol, type of precursor and working atmosphere) it is possible to guide the process in order to obtain powders with such a morphology which satisfies more complex requirements for the desired properties of advanced engineering materials. Significant advance in the improvement of powder characteristics (lower particles sizes, better spheroidity, higher surface area) was obtained by the application of the ultrasonic generator for the preparation of aerosols. Ultrasonic spray pyrolysis is performed by the action of a powerful source of ultrasound on the corresponding precursor solution forming the aerosol with a constant droplet size, which de pends on the characteristics of liquid and the frequency of ultrasound. The produced aerosols were transported into the hot reactor, which enables the reaction to occur in a very small volume of a particle and formation of nanosized powder. Spherical, nanosized particles of metals (Cu, Ag, Au,Co) were produced with new and improved physical and chemical characteristics at the IME, RWTH Aachen University. The high costs associated with small quantities of produced nanosized particles represent a limitation of the USP-method. Therefore, scale up of the ultrasonic spray pyrolysiswas performed as a final target in the synthesis of nanosized powder.
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In general, digital forensics could be defined as a compilation of methods of collecting, analysing and presenting digital evidence that could be found on computers, servers, in networks, databases, mobile devices and all other electronic devices where data is stored. This pa per explains the methods of collection of digital evidence in electronic mail and their analysis as well as taxonomy (classification) of digital forensics .
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Quality of life on Earth in the future will largely depend on the amount of safe water. As the most fundamental source of life, water is relentlessly consumed and polluted. To halt this trend, many countries are taking extensive measures and investing substantial resources in order to stop the contamination of water and return at least tolerably good water quality to nature. The goal of water purification is to obtain clean water with the sewage sludge as a by-product. Clean water is re turned to nature, and further treatment of sludge may be subject to or her procedures. The conclusion of this paper is simple. The procedure with purified water is easily achievable, purified water is discharged in to rivers, lakes and seas, but the problem of further treatment of sludge remains. This paper presents the basic methods of waste water treatment and procedures for processing the products from contaminated water. The paper can serve as a basis for further elaboration.
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Hydraulic servo controls are designed to facilitate rotation in place without providing increased power to steering wheels. In the initial design phase, the dimensions required for control systems are usually obtained through the calculation of their load when wheels rotate in place, where the torque is calculated empirically. The starting point in the project calculation is thus to determine the hydraulic power steering torque torsional resistance which is then used to determine the maximum value of force i.e. the torque on the steering wheel. The calculation of the control system servo control consists of determining the basic parameters, the required pump capacity, the main dimensions of the hub and the pipeline and the conditions for the stability of the system control mechanism.
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The cost-benefit-benefit analysis is a comprehensive analysis of benefits and cost-benefits of a project which that project brings to the project owner and to the society as a whole (including investors). The selection of the best investment alternative is realized on the basis of financial and economic analyses, as two integral parts of the cost-benefit benefit analysis. The first of these was dealt by the same group of authors in the article „Application of the cost-benefit-benefit analysis in the evaluation and selection of public projects (financial aspect)“, published in the previous issue of the Military Technical Courier. The subject of this paper is the processing of an economic analysis as a logical extension of the previous work. Therefore, the number of labels included in the table of the financial analysis content (1-5) supplements (in the chronological order) label tables that belong to the economic analysis (6-8).
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This article describes the dynamic processes within the gun barrel during the firing process in exploitation. It generally defines the basic principles of constructing tube elements, and shows the distortion of the basic geometry of the tube interior due to wear as well as the impact it causes during exploitation. The article also defines basic empirical models as well as a model based on fracture mechanics for the calculation of a use-life of the barrel, and other elements essential for the safe use of the barrel as the basic weapon element. Erosion causes are analysed in order to control and reduce wear and prolong the lifetime of the gun barrel. It gives directions for the reparation of barrels with wasted resources. In conclusion, the most influential elements of tube wear are given as well as possible modifications of existing systems, primarily propellant charges, with a purpose of prolonging lifetime of gun barrels. The guidelines for a proper determination of the lifetime based on the barrel condition assessment are given as well.
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The paper describes the restrictions on the joint transportation of dangerous goods in the same vehicle, with a focus on dangerous goods of Class 1 (explosive materials and objects with explosive materials), which are, considering their purpose, typical of the Serbian Army. It also describes the conditions under which the transport of dangerous goods does not apply specific requirements that must be met during the transport of dangerous goods, as well as a way of labeling vehicles for ordnance transportation.
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This article presents a ballistics module as a part of the fire control system of weapons for fire support (mortars, artillery weapons and rocket launchers). The software is "open" with the prominence of autonomy work. It can be modulated and adapted on the user demand. Moreover, it is independent of the hardware base.
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This paper deals with management system requirements in telecommunications. A TMN (Telecommunication Management Network) is necessary to be well designed and constantly upgraded. The ETOM (Enhanced Telecommunication Operation Map) framework, defined by the ITU-T Recommendation M.3050, is used to describe various processes that occur in the network for monitoring and control of military telecommunications systems. Their definition is an essential precondition for introducing management applications that would manage all of the processes in their end-to-end structure. Telecommunication net works are categorized in accordance with their functions. A set of relevant network processes important for supervision and management is explained for each described subsystem. This defining represents a prerequisite for the management application configuration which aims to automate management functions and services.
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Modern business is characterized by greater and greater market competition through all business areas and all activities. Establishment of market positions is a very important element of business activities in every organization. Quality of products and/or services provides recognizability at market and raising of ratings. Implementation of the ISO 9001 quality management system opens positions for secure national and international markets; it is also an identifier of an efficiently and effectively process-wise organized system in an organization.
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In order to have the best execution of required job tasks, the best task performer should be chosen. The problem of selection of job candidates has been present for long and it was mainly based on empirical estimates and feelings. Multicriteria analysis methods allow a more objective approach to the selection of job candidates. One of these methods is the method of analytical hierarchy process (AHP), which, besides the selection, provides the sensitivity analysis of solutions.This paper considers the criteria for manager selection and analyzes the sensitivity of the obtained solutions with the assumed set of alternatives.
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This work describes the Archive Digitization Application - ADA. The application was made on the request of the Military Archives of the Ministry of Defence of the Republic of Serbia and follows the complete structure of archives organization. The most important parts of the application for digitization of documents have been described as well as tasks of work posts for digitization of documents. The process of digitization can be divided into three phases in order to protect documents and to present them in the most efficient way to users - researchers. Though a term ’scanning’ is commonly used, digitization is a complex process and requires realization of all phases in order to get the final product. At the same time, an increased possibility of access to a larger number of documents is given to researchers with no dependency on available resourses in terms of bringing out and returning archival material from and to archives depots. This work also presents the visual appearance of the application for some parts of the digitization process.
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The movable robotic solar electric generator (imp-MSG), the Center for Robotics Institute "Mihajlo Pupin" in Belgrade; DARPA hidden earth sensors; Mini-Andros II robot to a dangerous situation; New oktokopter from Tekskorpa in Colombia; New Iranian armed drone; The camera in the helmet
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Swallow flies again; Published new tactical and technical data for the MiG-29M / M2; Saab develops deck Sea Gripen and optionally unmanned Gripen OP; Chengdu presented the model two-seater version of the aircraft FC-1; Viewed transport plane C296W; The US Army chose Bell V-280 Valor for your JMR-TD program.
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Why extinguishes the Global Hawk Block 40 program; Turkey seeks an amendment to a fifth-generation fighter for JSF; Northrop is fighting for its Global Hawk flies while Triton departs; Su-35 in the center of attention in Paris; Stop and ejected; Quick blow with a hammer; The allegations in the terminal stage; Purchase of Russian weapons continues.
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Инструкция для авторов о порядке подготовки статьи к опубликованию в журнале «Военно-технический вестник» разработана в соответствии с Актом о редактировании научных журналов Министерства науки и технологического развития Республики Сербия, № 110-00-17/2009-01 от 09.07.2009 г. Применением этого Акта, в первую очередь, обеспечивается совершенствование качества отечественных журналов и их более полного включения в международную систему обмена научной информацией. Инструкция соответствует международным стандартам ISO 4, ISO 8, ISO 18, ISO 215, ISO 214, ISO 18, ISO 690, ISO 690-2, ISO 999, ISO 5122 и соответствующим отечественным стандартам.