Proceedings of the National Academy of Sciences of Belarus, Physical-Technical Series / Известия Национальной академии наук Беларуси. Серия физико-технических наук
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РАЗРАБОТКА КОМПЬЮТЕРНОЙ МОДЕЛИ ГЕРМАНИЕВОГО ДЕТЕКТОРА И ПОЛУЧЕНИЕ МОДЕЛЬНЫХ СПЕКТРОВ СТАНДАРТНЫХ ОБРАЗЦОВ УРАНА U3O8 SRM-969
Get PDFComputer modeling was carried out for gamma-ray spectra of nuclear materials, which were measured by using a semiconductor high-purity germanium detector ORTEC GEM25P4-70. The standard SRM-969 samples were used as sources of gamma radiation, which are cylindrical tanks of fixed volume, made of aluminum alloy 6061, filled with a dispersed uranium oxide powder (U3O8) with different concentrations of 235U. The products from radioactive decay chains are determined for uranium isotopes 235U and 238U, which give the main contribution to the gamma spectrum of uranium oxide (U3O8). A technique that makes it possible to compare the results of measurements with model spectra is developed. The correlation of the measured spectra to the model spectra was made by comparing the areas of the total absorption peaks for energies of 185 keV and 1001 keV, which are often used in gamma spectrometry to determine uranium enrichment. The selected parameters of the model and the source of the detector allowed to describe the measured gamma-ray spectra with an accuracy of better than 6 % at the total areas of the absorption peaks in the energy range 150–1100 keV. The developed model makes it possible to obtain the model of gamma spectra of various fissile materials, provided that there are the data available about the isotopic composition, the quantum yield of gamma lines for each isotope, and the activity of fissile material. These model spectra can be used for the development of measurement techniques and software testing in the field of nuclear spectroscopy.
ЧИСЛЕННОЕ МОДЕЛИРОВАНИЕ ПРОЦЕССОВ КОНДЕНСАЦИИ ТОНКИХ ПЛЕНОК И ПРЕДПРОИЗВОДСТВЕННЫЙ АНАЛИЗ ЛИНЕЙНЫХ ПЕРЕСТРАИВАЕМЫХ ФИЛЬТРОВ
Get PDFLinear variable filters are one of the promising types of optical elements for creating multipurpose spectrometers. Application of this type of elements allows simplifying the optical scheme of the device significantly without great reduction of its characteristics. Using classical optical systems, linear variable filters improve the performance of optical devices. From the technology point of view, making this type of bandpass filter is a rather complex task. Current results of technology development of linear variable filters are considered in the article. In the course of work, a software was developed to calculate the distribution of condensed material on the substrate surface, taking into account the geometry of the source, substrate, masks and the whole system. Calculation of optical characteristics and analysis of the physical thicknesses of a linear variable filter were performed, and the dependence of the thickness of the coating on the coordinate of the substrate was obtained. The geometrical model for calculation was based on the geometry of the vacuum technological equipment – Advanced Optical Coater (VTE AOC), manufactured by IZOVAC Ltd. (Republic of Belarus). Based on the data obtained by using the software, the optimal geometry of the vacuum mask was proposed to obtain the required spectral gradient
АВТОМАТИЗАЦИЯ РАСКРОЯ ЗАГОТОВОК ДЕТАЛЕЙ ИЗ ПРОФИЛЬНОГО МЕТАЛЛОПРОКАТА
Get PDFThe role of automation of technological preparation of production to ensure the competitiveness of engineering products. At manufacturing of engineering products the determining factor of cost reduction is to reduce material consumption, primarily in the blank production (billets of machine parts need to have minimal allowances for further machining). The Maximum use of business waste metal can also reduce the consumption of metal. The technological possibilities of modern equipment for nesting has increased considerably. Experience of machine-building enterprises, which use equipment for cutting sheets, including specialized computer-aided manufacturing (CAM) for nesting, which fit the equipment, proves, that the utilization ratio of metal can be increased in average by 22...28 % when the specialized CAM for nesting is using. Analysis of specialized CAM for nesting, available on the market, shows that these software tools generally correspond to the modern scientific-technical level of developments of this type. However, they have some drawbacks. The peculiarities of software package “Module nesting” are considered. The methods of automation technology cutting of parts made of profile rolled metal, calculation of norms of material consumption and utilization are described. Algorithms of linear, rectangular shaped layouts, which are implemented in the software package “Module nesting” are shown
КРИТЕРИИ ОЦЕНКИ ЗАЩИЩЕННОСТИ ОТ УТЕЧКИ РЕЧЕВЫХ СИГНАЛОВ
Get PDFA method of assessing of normative protection indicator of speech signal by the criterion of speech intelligibility at high noise level in the band of speech signal, equal to intelligibility, by means of complex measuring signal with a large base, is substaniated. The advantage of the complex measuring signal with a large base over harmonic measuring signal when assessing protection of speech data leakage channels is shown. Voice signals in digital form along with voice signals in analog form are widely used. It is necessary to find mathematical relation between bit-error probability and speech intelligibility for voice signals in digital form. It is also necessary to establish mathematical relation between compound signal with large base and harmonic measuring signal. The main purpose of the study is to establish a normative characteristic of leakage protection of voice signals on the base of determined mathematical relations. The given mathematical relations will allow realizing the automated measuring system for estimation of security of the confidential information transformed into the analog and digital form, in channels of its leak.
ТЕРМОГИДРОДИНАМИЧЕСКИЕ ПРОЦЕССЫ В РАСПЫЛИТЕЛЬНОЙ КАМЕРЕ СО ВСТРЕЧНЫМИ ПОТОКАМИ ТЕПЛОНОСИТЕЛЯ
Get PDFThe article deals with the results of thermohydrodynamic processes in a spraying chamber with direct gas flow and counter-current flows. The upper gas distribution device in a spraying chamber is shaped as a grid system, while the bottom device represents a branch pipe with a swirler pointing upwards. The chamber features counter-current flow interactions, and the bottom flow is introduced as a swirling jet. The experimental calculations of gas axial flow rates, temperature and thermal conductivity distribution in different chamber sections are provided. The thermal conductivity properties were determined with the normal mode method. The study was performed with ball-shaped sensors made of materials with high thermal conductivity (copper, brass) with centered thermocouples. The upper gas distribution system in the form of two grids (if no bottom gas inlet was involved) was found to build up an axisymmetric thermal conductivity model, and, consequently, the model-specific gas distribution in the spraying chamber. Referring to the study device, a hole (nozzle) near the burner results in asymmetric pattern, irregular gas distribution and generation of low-activity areas. Thermal conductivity values in the chamber central area turn to be higher than at the peripheral areas due to gas jet flow. Besides, heat exchange intensity in the chamber central area decreases significantly upon distance from the chamber floor. An extra bottom inlet of heat medium and creation of counter flows was shown to result in substantial increase in thermal conductivity (1.5–2 times) in the chamber central paraxial area and lower section, thus evidencing the hydrodynamic activation and heat and mass exchange intensification, which benefits to more effective use of chamber capacity and improved drying performance
НЕКОТОРЫЕ ПУТИ СОВЕРШЕНСТВОВАНИЯ БЕЛОРУССКОЙ КОСМИЧЕСКОЙ СИСТЕМЫ ДИСТАНЦИОННОГО ЗОНДИРОВАНИЯ ЗЕМЛИ
Get PDFThe article discusses the possibility of improving the characteristics of the Belarusian space system of Earth remote sensing resulting from the implementation of multilevel information-integrated structure. The statement of this problem is related to the limitations that are typical for the shooting of the Earth’s surface from space, caused by both natural (insufficient viewability), and technical (inadequate recording equipment) factors. The proposed configuration of the multi-level information complex includes, besides the traditional space and ground segments, also an aviation segment and another supplementary ground measuring segment. And the aviation segment can contain both manned and unmanned aerial vehicles of different kinds, equipped with the necessary target equipment, and the supplementary ground segment – the system of accurate positioning. The main technical characteristics of the target devices that can be used to implement the complex are considered. As an example, the forecast of information capabilities of the complex for the solution of geodetic problems was considered: integration of such heterogeneous information resources at the stages of issue of the flight missions and complex data processing can significantly increase the likelihood of obtaining the necessary information for consumers.Обсуждаются возможности улучшения характеристик Белорусской космической системы дистанционного зондирования Земли, вытекающие из реализации ее многоуровневой информационно-интегрированной структуры. Предлагаемая конфигурация многоуровневого информационного комплекса включает в себя помимо традиционных космического и наземного сегментов также авиационный и дополнительный наземный сегменты. При этом авиационный сегмент может содержать как пилотируемые, так и беспилотные летательные аппараты различных типов, оснащенные необходимой целевой аппаратурой, а дополнительный наземный сегмент – спутниковую систему точного позиционирования. В качестве примера рассмотрен прогноз информационных возможностей такого комплекса при решении геодезических задач
ОСОБЕННОСТИ МАГНИТНО-АБРАЗИВНОЙ ОБРАБОТКИ ШТОКОВ ГИДРОЦИЛИНДРОВ
Get PDFObtaining high parameter of roughness of chrome-plated surfaces with rather big productivity and accuracy of geometrical parameters represents a serious problem. A process of magnetic and abrasive processing of rods of hydraulic cylinders which provides reduction of roughness of working surfaces is considered. Hydraulic cylinders which have been made of steel 20Cr GB 3077-88 were used as samples. Samples were exposed to heat treatment to HRC 61–64, grounded to obtain roughness of a surface of Ra 0.8 microns, prepared for chromium plating by polishing by the method of magnetic and abrasive processingand then chromeplated (thickness of a layer of chrome of 0.02–0.03 mm). The conducted researches of magnetic and abrasive processing of the chrome-plated rods of hydraulic cylinders have shown that the roughness of a surface decreases by 54 % at change of time of processing from 60 to 150 seconds. Further increase of the processing time leads to falling of intensity of material removal therefore decrease of a roughness at time of processing within the range from 60 to 210 seconds is equal to 61 %. Application of the method of magnetic and abrasive processing for rods of hydraulic cylinders before their chromium plating has provided the decrease of roughness Ra from 0.8 to 0.2 microns in 90 seconds of processing. It allows drawing a conclusion that the mechanism of process of magnetic and abrasive processing, which provides mass and dimensional removal of metal of chrome-plated surfaces is similar to the processes of treatment of not chrome-plated ones. The difference of removal intensity is explained by the fact that the chromic covering of details, having considerable wear resistance and hardness, interferes with more intensive course of process
ОЦЕНКА ЭФФЕКТИВНОСТИ ПРОСТРАНСТВЕННО-ЧАСТОТНОГО КОВАРИАЦИОННОГО ДЕСКРИПТОРА МАЛОРАЗМЕРНЫХ ОБЪЕКТОВ НА АЭРОИЗОБРАЖЕНИЯХ
Get PDFEfficiency estimation of a spatial-frequency covariance descriptor of small objects in aerial images is provided. It is based on analysis of computational complexity, storage capacity, Riemann distance values, ROC and DET curves for real video sequences. A criterion of QR-algorithm of choosing of number of steps to compute generalized eigenvalues of covariance matrices is proposed. It is based on analysis of generalized eigenvalues histograms, probability of object correct detection in an aerial image and influence of scale factor and rotation angle of object on Riemann distance value. An estimation of discrimination ability of the spatial-frequency covariance descriptor based on analysis of AUC of ROC-curve is given. A criterion to choose the optimal threshold of object detection based on the Youden’s index and Equal Error Rate is defined. A range of threshold values to make decision of object detection based on the analysis of ROC- and DET-curves for real video sequences is determined. It provides a high probability of object correct detection at given probability of its false detection and optimal ratio between probabilities of type I errors and type II errors
МЕТОДЫ ИНЖЕНЕРИИ ПОВЕРХНОСТИ И НАНОТЕХНОЛОГИИ ДЛЯ ПОВЫШЕНИЯ РЕСУРСА ИЗНАШИВАЕМЫХ ПОВЕРХНОСТЕЙ
Get PDFThe physical and chemical basis of formation of nanostructured state of material are represented and processing methods of nanostructured materials and coatings used in surface engineering are described. The information about the degree of influence of treatment regimes of gas-thermal spraying, electrochemical deposition, microarc oxidation, tribomechanical treatment and frictional cladding by a flexible tool on the processes of formation of structural-phase state and the level of the surface layer properties is given. A new generation of surface engineering technologies on the basis of the research is developed. The formed coating and surface layers maintain stability of structural-phase state under high loads and temperatures and have high wear resistance, thermal resistance and corrosion resistance for a long time. The examples of practical implementation of the developed methods of surface engineering and nanotechnologies for industrial plants are shown. Manufacturing sites are built and the developed technologies of coating application and modification of the surface layers by the activated surface engineering methods are used in more than 50 enterprises of Belarus, Russia, Korea and other countries. The using of developed nanostructured materials and coatings as well as methods and means of surface engineering technologies allows increasing the technical level of the engineering techniques, reducing the cost of production and improving the competitiveness of products
УСТОЙЧИВЫЙ МЕТОД НОРМАЛИЗАЦИИ ОТСКАНИРОВАННОГО МОБИЛЬНЫМ УСТРОЙСТВОМ ИЗОБРАЖЕНИЯ ШТРИХКОДА
Get PDFA robust method of normalizing barcode images scanned with a mobile device based on iterative threshold binarization, forming the edge binary image, Hough transform, correction of the angular position of the boundary points and the projective transform is developed. The results of the computer simulation are presented. The method provides the invariance to conditions of printing and lightening (image rotation invariance in the range from -450 to 450, and noninform barcode image illumination invariance) due to using procedures of preprocessing, boundary corner point localization and geometric distortion compensation of the digital barcode images.Разработан метод нормализации отсканированного мобильным устройством изображения штрихкода, основанный на итерационной пороговой бинаризации, формировании контурного бинарного изображения, преобразовании Хафа, коррекции позиций угловых граничных точек и проективном преобразовании плоскости. Представлены результаты компьютерного моделирования. Данный метод обеспечивает инвариантность к условиям печати и съемки (к вращению изображения в диапазоне от –45° до 45° и неравномерному освещению изображений штрихкода) за счет использования процедур предварительной обработки, локализации граничных угловых точек и компенсации геометрических искажений цифровых изображений штрихкода