University proceedings. volga region. technical sciences

Background. The object of the research is the system of documentation support for management in organizations and project activities. The subject of the research is the management of documentation processes in the system. The purpose of the srudy is to develop and apply a workflow optimization strategy based on risk analysis. Materials and methods. The management task in the management documentation support system is solved based on a systematic analysis of models of document processes and risk events. Results. The management strategy in the documentation support system according to the risk criterion is proposed. Conclusions. The proposed method makes it possible to formulate a risk management strategy based on the results of a systematic analysis of inter-element relationships and reliability models and optimize the management of document processes and the costs of risk prevention.

Background. In recent years, there has been an information boom around fractal antennas designed for wireless communication systems at a wide variety of frequencies. However, there is still no clear opinion among experts on whether such antennas have better characteristics than conventional canonical antennas. In this regard, the purpose of this article is an investigation of fractal patch antennas in modern communication systems of the greatest practical interest at gigahertz and terahertz frequencies. Materials and methods. The paper considers two identical-shaped monopole fractal patch antennas of the “Sierpinski carpet” type: gigahertz and terahertz. The following characteristics of both antennas are investigated: frequency dependences of the scattering matrix, VSWR, input impedance and radiation pattern. It is taken into account that in the terahertz range it is necessary to take into account the fact that plasmon-polaritons with strongly pronounced dispersion properties are excited in the patch. The simulation was carried out in the CST Microwave Studio program separately for the initial triangular canonical antenna and its three fractal iterations. Results. It is shown that the fractalization of an electromagnetic GHz antenna does not provide tangible advantages over the original non-fractal antenna in terms of either the number of operating frequencies or the quality of the radiation pattern, and this fractalization even worsens the situation in a number of parameters. On the contrary, in the case of a plasmon-polariton THZ antenna, due to the dispersion properties of plasmon-polaritons, it is possible to increase both the number of antenna bandwidth, the intensity of the main lobe of the radiation pattern, and its angular width. Conclusion. The often advertised advantages of fractal antennas at frequencies up to gigahertz are actually just a fashion statement. At the same time, in the case of terahertz plasmon-polariton antennas, their fractalization makes it possible to realize new possibilities in terms of multiband and efficient control of characteristics.

Background. Current-vortex sensors are widely used to solve various technical problems. The efficiency of using sensors depends on the method used to process its output signal. The purpose of the work is to study the possibilities of measuring the frequency of the output signal of a sensor included in an auto-generator circuit. Materials and methods. Mathematical modeling of this method and its comparison with the traditional method of measuring the amplitude of the output signal are performed. The depth of penetration and distribution of eddy currents in a conductive object at different frequencies of an alternating magnetic field is modeled using the ELCUT program. Results. The dependences of the sensor parameters on the distance to the monitoring object and the operating frequency of the sensor are obtained. Conclusion. The results of the study showed the effectiveness of usingan autogenerator circuit for switching on a current-vortex sensor and showed that the operating range of the sensor with an inductor diameter of 15 mm is no more than 7 mm.

Background. Improving the reliability of printed circuit boards is associated with reducing the level of their defects in the production process. The task of forecasting the level of defects is especially relevant in a situation where an enterprise enters the so-called inflection point, where the existing technological level fails to ensure acceptable indicators of defects for the increasing volume of production of products of new complexity (for example, when changing the specialization of contract production of printed circuit boards from accuracy class 5 to accuracy class 6 and higher). Early determination of the level of future defects allows developing and implementing measures to reduce production costs. The purpose of the study is to develop a formula for forecasting defects in the production of printed circuit boards. Materials and methods. The following are used to solve the problem: the method of mathematical modeling, methods of reliability theory. Results. A formula for calculating the level of defects in the production of printed circuit boards has been developed, and the critical value of this level has been predicted for the "point" implementation of an enhanced quality control procedure within a specific printed circuit board. Conclusions. The calculation formula has been tested. The results of the test are demonstrated using a specific multilayer printed circuit board as an example. It is planned to conduct an extended test at a printed circuit board manufacturer.

Background. Among all fixed connections in mechanical engineering, tension connections are distinguished by a wide variety and make up about 20% of all connections. The article analyzes existing methods for assembling tension connections and indicates solutions for ensuring their tightness. The purpose of the work is to ensure the tightness of tension connections with a longitudinal assembly method. Materials and methods. The program of experimental studies is given. It is shown that control of shaping of the surface layer of mating parts in the longitudinal assembly method solves the problem of ensuring the tightness of joints. A technical solution is proposed. Results. The graphs of the dependence of pressing forces along the length of the joint on the value of the tension and the presence of sealant are presented. The graphs of the degree of tightness of pressed parts assembled from different materials are shown. Conclusions. Tension joints assembled using existing technology without sealant do not provide tightness of the joint, while the use of sealant increases the pressing force. Controlling the formation of the surface layer of the covered part is possible without complicating the design and manufacturing technology, which allows for ensuring the strength characteristics and the required tightness of the joints.

Background. Sublimation during high-temperature fracture of hard alloys affects the formation of a fraction of ultrafine particles. For subsequent technologies of using powder raw materials, this effect leads to significant changes in the molding modes of products. The determination of the mass fraction of sublimation is also relevant for assessing the profitability of the CDD method. The purpose of this work is to create a theoretical calculation methodology that makes it possible to determine which part of a rod dispersed using a plasma arc sublimates depending on the conditions. Materials and methods. Calculations that make it possible to predict the technological yield of sublimated material. These calculations are applicable for other technological processes related to high-temperature dispersion of materials. Data on powders obtained using CDD and EDD methods are presented. Results. The article contains calculations that make it possible to determine the percentage of evaporated and sublimated tungsten carbide in the process of the CDD method used by researchers from PSU; formulas have been created that are suitable for carrying out similar calculations by specialists engaged in work with similar processes. Conclusions. Based on data on evaporation and sublimation, as well as the required electricity, the CDD method is suitable for designing automated industrial plants for the production of powder raw materials for powder metallurgy.