The purpose of the article is to carry out mathematical modeling of the main characteristics and parameters of a microstrip antenna, the dielectric substrate of which is created from a domestic ceramic sample and to substantiate the use of a microstrip antenna as a transmitting and receiving antenna in a radio altimeter. It is shown that a microstrip antenna on a ceramic material substrate with a relative permittivity ε = 9.6 and a thickness of 0.2 mm has good electrical parameters in the frequency range of 31.5–33.5 GHz. Including the width of the antenna radiation pattern at the level of –3 dB is 12.5 degrees in the horizontal plane and 26.7 degrees in the vertical plane. In this case, the antenna gain is 17 dB and the level of the first side lobe is –20 dB relative to the main antenna lobe. Also the practical application of microstrip array antennas inphase as a transmitting and receiving antenna for a radio altimeter installed on aircraft is described in the article. The range of the altimeter reaches 300 m.

A study of the technical and dosimetry characteristics of brachytherapy afterloaders and applicators was carried out. Ring applicator has been taken as an example, the correctness of positioning of a radiation source (RS) inside the applicators was tested as part of the comissioning and quality control procedure of the brachytherapy applicators. The magnitudes of inconsistencies in the position of RS were established when planning and implementing treatment plans for radiation therapy. The identification of the values of the discrepancy was carried out using the obtained X-ray images of the applicator at the time of the implementation of the irradiation plans. The treatment plan was a sequential positioning of RS in the body of the applicator in each active position with a minimum step from the tip to the vaginal part of the applicator. The X-ray image was obtained by locating the source sequentially at each active position of the applicator. When carrying out dosimetric planning, 3 methods of applicator reconstruction were used. The analysis revealed that the applicator reconstruction method affects the magnitude of the discrepancy in determining the position of the source in the lumen of the applicator ring. Using the methods of statistical analysis, the mean, median, maximum and minimum values of the detected deviations were calculated. The results are presented in the form of tables and graphs for all investigated stop positions of IRS. Based on the results of the study, we consider it expedient to carry out quality control procedures when putting applicators into clinical operation. Based on the results obtained, we consider it acceptable to conduct a quality control procedure for the positioning accuracy of radiation sources in the applicators at least 1 time per month. Taking into account the results of the study when carrying out dosimetric planning will improve the quality of the irradiation sessions using the brachytherapy method, thereby improving the quality of oncological care for the population.

Complex interaction of incisors of the multi-element system “jaw – tooth – periodontium – enamel – dentinˮ is considered in the present work. The model was created on the basis of tomographic images taking into account previous studies of the human dental apparatus for a simplified model of three molars. The aim of the work is to determine the stress-strain states of the “jaw – periodontium – tooth – dentinˮ system for a different number of incisors and their location using three-dimensional computer finite-element modeling. The results of the study allow obtaining a more complete and accurate assessment of the state of the human dentofacial apparatus as a whole and each of its elements separately in order to improve the technologies and methods of prosthetics.

Using computer simulation, a study of the effect of a potential jump on the interaction processes in O-type traveling-wave tubes has been carried out. In these devices, the interaction of the electron beam with a slowed down electromagnetic wave is carried out. To slow down the electromagnetic wave, various electrodynamics systems are used: spiral, on chains of coupled resonators, etc. In this work, we have chosen a slowing down system in the form of a chain of looping rectangular waveguides. Its advantage is that it has a wide bandwidth and each link in such a chain is coordinated with the adjacent ones. To assess the effect of a potential jump on the interaction processes in O-type traveling-wave tubes, a mathematical model has been developed, which takes into account most fully all the factors influencing the interaction processes. These include: relativistic effects during the motion and interaction of electrons, sagging of fields in the gaps of the waveguide, losses in the walls of the waveguide, taking into account the space charge fields (taking into account the periodization of the fields). Based on the developed model, a program was compiled and calculations of various variants of TWT were carried out for accelerating voltages of 20–500 kV, electron beam currents of 0.3...160 A. When performing calculations, the gap with a potential jump was located in different places of the TWT slow-wave structure and its location was chosen where the maximum effect on the electron bunching processes is manifested. As the calculations have shown, the potential jump makes it possible to increase the output power of the TWT by 15–20 %. It can be noted for comparison that the use of a potential jump in multi-cavity klystrons [1] also leads to an increase in the output power by 15-25 %. This confirms the reliability of the mathematical models used in TWT and klystrons.

The purpose of the article is to present computationally economical algorithms for long-term coherent accumulation of signals reflected from a point target with compensation for range and frequency migration and accumulation of signals in the spectral region. The algorithms include intra-period processing with simultaneous correction of range and frequency migration and inter-period processing with coherent accumulation of signals at the output of intra-period processing. In the first variant of the algorithm, intra-period processing is implemented by calculating the spectra of the received signals in each repetition period, multiplying the samples of the spectra by the samples of the amplitude-phase-frequency characteristic of the matched filter of a single signal and correcting phase coefficients determined by the number of the repetition period and the values of the range derivatives, and the inverse Fourier transform of the transformed spectra. The difference between the second version of the algorithm at the stage of intraperiod processing is the correction of only the quadratic and subsequent components of the range and frequency migration and the use of the keystone transformation, which eliminates the linear range migration. Coherent accumulation for both variants is realized due to the fast Fourier transform of the signal samples over the repetition periods for all samples over the range. The concept of “rough speed resolutionˮ is introduced, which determines the arrangement of channels when compensating for range migration. The uncertainty function in the coordinates “velocity–acceleration” is obtained. The equivalence of the two variants of the algorithm is shown and estimates for the required number of receiver channels are given. The simulation results confirming the operability of the proposed algorithms are presented.

This paper presents the results of a search for the optimal design of a high-orbit gyro-TWT, which would make it possible to reduce the magnetostatic field when operating at high frequencies close to the millimeter wavelength range, increase the gain and gain bandwidth, and increase the efficiency of the gyro-TWT. To search for the optimal configuration of the high-orbit gyro-TWT, the Gyro-K program was used, in which the equations for the excitation of an irregular waveguide by an electron beam are constructed on the basis of the coordinate transformation method of A.G. Sveshnikov, which is based on replacing the problem of exciting an irregular waveguide with the problem of exciting a regular waveguide with a unit radius. This method allows one to search for the solution of wave equations in the form of expansions in terms of the system of basis functions of a regular cylindrical waveguide. To solve Maxwell's equations, the Galerkin method was used, which is also called the orthogonalization method. The coefficients of the expansion of the field in terms of eigenbasic functions are determined in this method from the condition of the orthogonality of the residuals of the equations for the eigenbasis functions of a regular waveguide. The boundary conditions at the open ends of the waveguide are determined for each mode of the regular waveguide separately, which eliminates the incorrectness of setting the boundary conditions for the full field, as is the case when using the “picˮ technology. As a result, we obtain a system of ordinary differential equations for the expansion coefficients, which now depend only on the longitudinal coordinate. This approach makes it possible to transform the threedimensional problem of excitation of an irregular waveguide into a one-dimensional problem. Ohmic losses in the walls of the waveguide are taken into account on the basis of the Shchukin – Leontovich boundary conditions. For a self-consistent solution of the problem of excitation of an irregular waveguide by an electron beam, the iterative method of sequential lower relaxation was used. An optimized version of a high-orbit gyroTWT has been obtained, which has an electronic efficiency of 28 %, a wave efficiency of 23 %, a gain of 34 dB and a gain band of 11 % at an operating frequency of more than 30 GHz. This was achieved by introducing an additional conducting section of the waveguide into the absorbing part of the waveguide, which led to an improvement in the azimuthal grouping of electrons in the Larmor orbit and, as a consequence, to an increase in the lamp efficiency. A twofold increase in the waveguide length made it possible to increase the lamp gain. Ohmic energy losses in the walls of the waveguide reach 5 % of the power of the electron beam. The implementation of such a powerful gyro-TWT (2 MW) in the millimeter wavelength range will significantly increase the capabilities of radar at long distances and increase the resolution of the radar.

A multi-differential operational amplifier, called OAmp3, designed for operation at temperatures up to minus 197 °С and developed on bipolar transistors and junction field-effect transistors of the master slice array МН2ХА030, is considered in the article. The circuitry features of the OAmp3 allow, due to the use of various negative feedback circuits, to implement a set of functions necessary for signal processing on a single amplifier: amplification (or current – voltage conversion), filtering, shift of the constant output voltage level. The performed measurements of OAmp3, connected as instrumentation amplifier circuit, showed that all manufactured products retain their performance in the temperature range from minus 150 °С to 20 °С, and individual samples – at minus 197 °С. It was found that the main reason for the loss of OAmp3 performance is an increase of the resistance of semiconductor resistors by almost 5.4 times at minus 197 °С compared to normal conditions and decrease in the junction field-effect transistor drain current. Together, these factors lead to decrease in the current consumption of the OAmp3 by almost 31 times at minus 180 °С compared to normal conditions. To reduce the temperature dependence of the current consumption and, thus, save the OAmp3 operability at low temperatures without changing the technological route of integrated circuits manufacturing, it is proposed to replace high-resistance semiconductor resistors with “pinch-resistors” formed on a small-signal p-junction field-effect transistor. The article presents the OAmp3 connection circuit in the form of an instrumental amplifier, the method and results of low-temperature measurements of experimental samples.

The purpose of this work is to use information technology to help management decisions. The crux of the problem is the choice of suppliers of materials and components for mechanical engineering companies. Periodically, in the procurement process, suppliers should be assessed on a number of criteria. The importance of rating is due to the fact that in today's market there are a large number of suppliers of the same material resources. Purchase is made from the most competitive suppliers, constantly confirming their status as a reliable business partner. The company developed a method of evaluating suppliers based on the system of management of the bases of the bath Microsoft Office Access. MS Access works in the Windows operating environment and allows users to organize a local database (DB). The local Access database has its own tables, forms, reports and other DB facilities of the organization with a relatively small amount of data. With the help of the scoring method, suppliers are ranked by their level of reliability. The relationship is terminated with a supplier that does not meet the required level of reliability. In this way, management solutions for logistics of supply receive a tool to hang the efficiency and get good results of the enterprise, to achieve its market stability.

The aim of this work is to develop a method for the synthesis of matching devices for broadband radio engineering systems with varying impedance in different operating conditions. To achieve this goal, a criterion (complex criterion) is proposed for minimizing the value of the modulus of the sensitivity invariant of the reflection coefficient function to a change in the load impedance with restrictions on the square of the deviation of the power transmission ratio from a given level. It is proposed to use a combination of methods of real frequencies together with the shown complex criterion, which made it possible to implement an effective approach to the synthesis of matching devices for broadband radio engineering systems with an unstable load impedance. To verify the approach, a matching device was synthesized, which made it possible to reduce the loss of the power transmission factor level transmitted to the UHF/VHF antenna of the AD-44 / CW-TA-30-512 range when it is located in various operating conditions by at least 50 % in relation to losses obtained with a standard matching device.

The purpose of this article is to reduce the cost and time for the formation of a project team, as well as improve the quality of selected teams, by automating the process of calculating the labor resources of project teams. The objectives of the article are to study and analyze theoretical works on project teams formation and the construction of aggregated coefficients of a project and an employee for IT projects labor resources calculation. The article reveals the basic concepts and mechanisms of project management and human resources of an IT organization; the process of a project team forming and its structure, which is made up of the customer's team and the executor's team, is considered. A set of key indicators of a project and an employee is highlighted, which are necessary components for introducing the concept of an aggregated coefficient. The description of the calculation of the aggregate coefficient of the project (Iп), the aggregate coefficient of the employee (Ic), as well as the project aggregated coefficient of the employee (Ic п ) is provided, since the aggregated indicators of the project and the employee are independent in relation to each other, and to solve the tasks we need a coefficient that describes usefulness and efficiency of attracting a specific employee for a specific project. The theoretical significance of the work lies in the fact that it describes the process of project teams building in details, proposes aggregated coefficients of projects and employees, which make it possible to assess and select labor resources for project teams. The obtained theoretical results can be used to assess the role of each employee on a separate project and in the company as a whole, to calculate the labor resources of IT projects, as well as by the search and project planning department when choosing the scope and nature of work for the period under consideration.

The hardware implementations of fixed-point DCT blocks, known as IntDCT [1] and BinDCT [2], require some solutions. One of the main issues is the choice between the implementation of the conversion on FPGA, or the implementation on a digital signal processor (Digital Signal Processor, DSP). Each of the implementations has its own pros and cons. One of the most important advantages of the DSP implementation is the presence of special instructions used in DSP, in particular, the ability to multiply two numbers in one clock cycle. Therefore, with the advent of DSP, the limitation on the number of multiplications in algorithms was removed. On the other hand, when implementing a block on an FPGA, we can limit not ourselves to the bitness of the data (within reasonable limits), we have the ability to parallelize all incoming data and implement specialized computing cores for various tasks. In fact, designing multimedia systems on FPGAs reminds the design of similar systems based on the logic of a small and medium degree of integration. Such an implementation has the same limitations: a relatively small amount of available memory, the need to design basic structural elements (multipliers, divisors), etc. It is the inequality of the addition and multiplication operations when they are implemented on FPGAs that caused the search for DCT algorithms with the smallest number of factors. However, even this is not enough, since the structure of the multiplier is many times more complex than the structure of the adder, which made it necessary to look for ways to transform without using multiplications at all. This article shows how, on the basis of integer direct and inverse DCT and distributed arithmetic, to create a new universal architecture of decorrelated transform on FPGAs without multiplication operations for image transformation coding systems that operate on the principle of lossless-to-lossy (L2L), and to obtain the best experimental results in terms of hardware resources compared to comparable compression systems.

The aim of this work is to analyze existing detectors for the relative dosimetry of small radiation fields in external beam radiation therapy and the requirements for them, consider the problems in carrying out dosimetry of small radiation fields, determine the physical conditions under which an external photon beam can be designated as a small field. In modern radiation therapy, there is an increase in the use of small static fields, which is facilitated by the general availability of standard and optional multileaf collimators and new generation treatment machines of various designs. There is growing interest in the use of such radiation techniques as stereotactic radiosurgery, stereotactic body radiotherapy, intensity modulated radiotherapy, which are widely used small fields. This has increased the uncertainties in clinical dosimetry, especially for small fields. Accurate dosimetry of small fields is important when commissioning linear accelerators and is a difficult task, especially for very small fields used in stereotactic radiotherapy. In the course of the work, a study of topical problems in the dosimetry of small radiation fields in external beam radiation therapy has been carried out. The physical conditions under which the external photon beam can be designated as a small field are considered. A review and analysis of existing detectors for the relative dosimetry of small radiation fields, as well as an analysis of the requirements for the character. The analysis revealed that liquid ionization chambers, silicon diodes, diamond detectors, organic scintillators, radiochromic films, thermoluminescent dosimeters and optically stimulated luminescence detectors are considered suitable for relative dosimetry of small photon fields and are recommended for use in clinics where radiotherapy is performed.