ELECTRONICS, RADIOPHYSICS, RADIOENGINEERING, INFORMATICS
Heat pipes are designed to effective removing heat from heating elements and reducing the temperature of various devices. Heat pipes with capillary porous structures are designed to operate under conditions of unfavorable gravity forces. Their main advantages are their high heat transfer capacity, as well as the ability to retain the coolant in a capillary-porous structure under dynamic power loads. The purpose of this work is to study the process of obtaining capillary-porous materials from metal powders for heat pipes with increased efficiency of using the vibration molding method. The article substantiates the relevance of creating heat pipes from metal powders. The information about the influence of the contact angle, surface tension and capillary pressure on the heat transfer capacity of a heat pipe is provided. It is shown that for the efficient operation of the heat pipe it is necessary to create such a capillary structure of the porous material, which could simultaneously provide a high speed of movement of the coolant and its rise to a given height. The above requirements can be satisfied by creating a capillary structure using powder metallurgy methods by optimizing the distribution of pore sizes. In this case, the most promising method seems to be the method of molding when applying a vibration to a mold with a powder. It is possible to obtain the required pore distribution in this way by choosing the correct particle size, shape and vibration parameters. This makes it possible to ensure the packing of particles in size, which affects their packing density, pore size, tortuosity and length of pore channels. The distribution of the maximum pore sizes over the thickness of the samples obtained from powders of various granulometric composition with the use of vibration has been investigated. As a result, a process was developed for obtaining capillary structures by the method of vibration molding of metal powders, depending on the size of the powder particles, the amplitude and frequency of vibration. It is shown that this method can provide a given pore distribution of the capillary structure for heat pipes, which makes it possible to increase their heat transfer capacity.
The paper proposes a histogram estimate of the probability density based on fuzzy data belonging to a grouping interval. A methodology for constructing a histogram estimate using a histogram smoothing filter is presented. The technique of constructing such a filter is described. The main filter parameter is established – the coefficient of the statistical relationship between the amount of data falling into the grouping interval for a single inclusion function and when approaching to use the membership function. The use of an iterative procedure for a histogram filter allows for a greater “smoothness” of the histogram. The simulation results show the effectiveness of using a histogram filter for different data volumes. At the same time, the choice of the number of grouping intervals for the “correct” recognition of probability density becomes not critical. The histogram filter is a simple tool that can easily be built into any algorithm for constructing histogram estimates.
The paper considers a digital image processing method that provides efficient transmission, redistribution and storage of aerospace environmental monitoring videographic information. The requirement to increase the monitoring efficiency, if necessary, to carry out regular monitoring of changes in the image field of the observed object is especially relevant when describing spatially aligned sets of images obtained after multi-zone, multi-time and multi-polarization shooting. In many remote sensing applications, the processing efficiency reflects the degree of reduction in the volume of transmitted, described, analyzed and stored videographic information. The computational processing of digital images based on the coordinate survey scheme is presented. The method can be used to perform the procedure for decoding images in order to solve the problem of classifying objects of interest, analyzing images. Such characteristics of binary objects as a spatial boundary and a contour were used as deciphering signs. These features make it possible to describe the shape of an object, its geometric parameters and search for images with specific spatial structures. The processing method is realized by executing efficient algorithms for coding an image on a discrete grid by means of a chain code and spectral coding based on the fast discrete Hartley transform. The result of processing comes down to minimizing the number of such basic computational operations as multiplication, addition, transferring, as well as reducing the time and capacitive complexity of the program, and reducing the redundancy of the initial data. An example of an effective representation and description of a segmented image of an object is given. The proposed method makes it possible to expand the technical capabilities of more efficient transmission and processing of images for solving problems in the field of remote sensing.
Biofeedback based on electrodermal activity of the skin is used as a method for optimizing the functional state of drivers and assistant drivers of locomotive crews. High-quality inter-trip rest of locomotive crew drivers ensures the preservation of health, labor protection and higher indicators of professionally important psychophysiological qualities necessary for the successful performance of locomotive management activities. The purpose of this work is to determine the nature of the relationship between the relaxation abilities of locomotive crew drivers and their professionally important psychophysiological and personal qualities. The experiment was conducted on the basis of the office of the psychological service of the Motor Car depot in Minsk. A personal computer and the NeuroDog hardware and software complex were used as the equipment for the biofeedback training. A factor analysis of the primary empirical data of subjects who successfully developed the relaxation skill was performed. Factor analysis was carried out using the principal component method and the Varimax method available in the Statistica 10.0 package. The results of the analysis allowed us to determine the structure of psychophysiological and personal qualities of locomotive crew drivers, as well as the degree of their influence on the successful development of relaxation skills. The results obtained will later be used to develop a methodology for training drivers in relaxation skills in accordance with their individual characteristics and algorithms for its implementation in the context of the UPDK-MK hardware and software complex, used by the psychological service of the Belarusian railway to monitor the current state of functional systems of locomotive crew drivers.
Random number generators are required for the operation of cryptographic information protection systems. For а correct application of the generator in the field of information security, it is necessary that its output sequence to be indistinguishable from a uniformly distributed random sequence. To verify this, it is necessary to test the generator output sequence using various statistical test suites such as Dihard and NIST. The purpose of this work is to test a prototype hardware random number generator. The generator is built on the basis of the ND103L noise diode and has a random digital sequence of binary numbers at the output. In the prototype there is a possibility of regulating the amount of reverse current through the noise diode, as well as setting the data acquisition period, i.e. data generation frequency. In the course of operation, a number of sequences of random numbers were removed from the generator at various values of the reverse current through the noise diode, the period of data acquisition and the ambient temperature. The resulting sequences were tested using the NIST statistical test suite. After analyzing the test results, it was concluded that the generator operates relatively stably in a certain range of initial parameters, while the deterioration in the quality of the generator's operation outside this range is associated with the technical characteristics of the noise diode. It was also concluded that the generator under study is applicable in certain applications and to improve the stability of its operation, it can be improved both in hardware and software. The results of this work can be useful to developers of hardware random number generators built according to a similar scheme.
An effectiveness of the application of classical non-destructive tests for testing storage devices and their main disadvantages, among which there are great time complexity and low diagnostic ability, are analysed. The concept of double address sequence 2A is defined and the examples of their formation based on counter address sequences and Gray code are provided. The basic element of non-destructive tests with the use of double address sequences is synthesized and its detecting and diagnostic abilities for different storage devices defects are explored. There are two new non-destructive tests of memory devices March_2A_1 and March_2A_2 and an estimation of their time complexity and efficiency of failure detection are given. A significantly lower time complexity of the proposed tests and their high diagnostic ability in comparison with classical non-destructive tests are shown.
Structured arrays and master slice arrays are often used to reduce cost, design and test time for radiation hardened analog integrated circuits. One of such master slice arrays is МН2ХА030, which uses bipolar and junction field-effect transistors. The purpose of this article is to estimate the effect of ionizing radiation on the parameters of the operational amplifier OAmp2 and comparators ADComp1 and ADComp3 created on the МН2ХА030 master slice array. Еhe results of measurements of analog components after exposure to 60Co gamma quanta with an absorbed dose of up to 700 krad and a fast electron fluence of up to 2.9·1015 el./cm2 with an energy of 6 MeV are presented. The OAmp2 operational amplifier provides a satisfactory level of basic static parameters (input current, offset voltage, voltage gain) at a fast electron fluence of up to 3.7·1014 el./cm2 with an energy of 6 MeV. There are a decrease in the voltage gain and an increase in the offset voltage at electron fluence of greater than 1015 el./cm2. The latter can be caused by a decrease in the efficiency of the common-mode signal feedback integrated into operational amplifier with a significant drop in current gain of bipolar transistors. All considered analog components provide a satisfactory level of basic static parameters at a fast electron fluence of up to 3.7·1014 el./cm2 with an energy of 6 MeV and an absorbed dose of 60Co gamma quanta of at least 700 krad. It is assumed that resistance of OAmp2, ADComp1, ADComp3 to the action of 60Co gamma quanta is significantly higher and requires further research. The developed analog components can be used in signal reading devices required in front-end of sensors for space instrumentation and nuclear electronics.
In this paper, the problem of segmentation of halftone images is considered, in which areas of local maxima and minima (extrema) are distinguished with a monotonic change in the brightness of pixels from local extrema to the boundaries of areas. To solve this problem, a mathematical model is proposed and a segmentation algorithm is developed on the basis of counter-wave growing of local extremum regions. The developed algorithm differs from the known segmentation algorithms by using a set of brightness thresholds (by the number of regions), varying by one in each cycle, starting from the values of local extrema, taking into account the increase or decrease in brightness to select adjacent pixels that are attached to the regions formed from these local extrema. The algorithm provides a greater deviation of pixel brightness from the average value within the region compared to known segmentation algorithms. This does not allow evaluating its efficiency using known indicators based on the variance of the brightness within the region. In this regard, estimates of the monotonicity of changes in the brightness of regions are proposed based on a) the shortest distances from each pixel of the region to the corresponding local extremum along the routes determined by the maximum increase (for the region of the local maximum) or decrease (for the region of the local minimum) the brightness of pixels and b) taking into account the number pixels that break the monotony of the segment brightness change. Using these estimates, it is shown that the proposed algorithm provides segmentation of artificial and natural grayscale images with a monotonic change in the brightness of pixels in the areas of local extrema. These properties allow us to consider the developed algorithm as a basis for the selection of texels, spots, low-contrast objects in images.
An algorithmic support for metallographic images preprocessing and analysis is presented. The software product implements metallographic methods for the grain size determination by comparison of rating scales, counting beans, calculation of grain boundaries intersections for equiaxed and elongated grains, measuring a chords length. Multiple digital images can be used as initial data. Pre-processing is used to remove noise, sharpen and improve contrast using Adaptive Contrast-Limiting Histogram Equalization (CLAHE). The next step is grain segmentation. A combination of distance transform and adaptive watershed binarization is used. Binary images filtration based on the operations of mathematical morphology is provided. Contour analysis is used to determine grain boundaries. The study’s results of the entire rating scales and on the real metallographic images are presented. High efficiency of an algorithmic support is confirmed by the experiments. The software implementation has the following main features: the ability to calibrate the actual grain size, automatic or manual image preprocessing, grain size analysis with saving the results as a report in jpg format. Batch processing provides the ability to download images for processing with the same type of algorithm.
Gigabit passive optical networks (GPON) are the most advanced technology. The data transfer rate is 2.5 Gbps for downstream and 1.25 Gbps for upstreams. But this network architecture has a limited physical network length of 20 km. This is due to the high budgetary losses of the network. This restriction of access makes the network difficult to access for subscribers located far from the facilities of the telecom operator, and coverage of remote settlements is quite costly (cost of design work, fiber, laying of fiber-optic cable), thereby complicating the elimination of the digital divide between the city, the suburbs and the countryside. To solve this problem, it is proposed to use quantum dot semiconductor optical amplifiers (QD-SOA), which will expand the GPON reach up to 60 km, which is the limit for the logical length under the current protocols. Quantum dot semiconductor optical amplifiers are promising devices for optical communication technology, but for commercial use they have one disadvantage. They are polarization sensitive. In this paper the authors constructed a polarization diversity scheme to avoid polarization sensitivity of QD-SOAs.
The processes of reactive magnetron sputtering of a V target in Ar/O2 gas mixture are investigated. It was found that when using a pulsed current for sputtering and a pressure in the chamber less than 0.06 Pa, the intensities of the emission lines of vanadium at 437.922 nm, argon at 750.386 nm, and oxygen at 777.417 nm with a change in the oxygen concentration in Ar/O2 gas mixtures (ГO2) have no hysteresis and unambiguously depend on the parameters of the sputtering process, which makes it possible to stabilize the process without using feedback systems. By monitoring the sputtering process by optical emission spectroscopy and depositing films on a rotating substrate of diameter 100 mm, vanadium oxide (VOx) films with nonuniformity thickness less than ±2.4 % and surface resistance less than ±2.5 % were obtained. Studies by transmission line method of the influence of the parameters of the reactive magnetron sputtering and subsequent annealing at O2 pressure of 0.04 Pa on the characteristics of thermoresistive structures based on VOx films showed that when the contacts are deposited without ion cleaning, the current-voltage characteristics (IV) and the dependence of the resistance on the length of resistors R(L) are nonlinear, which indicates the presence of a potential barrier in the contacts. Preliminary ion cleaning can significantly improve the linearity of the IV characteristic. The most linear IV characteristics were obtained for Ti contacts. However, the specific contact resistance of the VOx/Ti contact increases with an increase in the oxidation state of the VOx films and reaches ρc = 0.1 Ohm·m2 at the specific resistance of vanadium oxide ρ = 0.1 Ohm·m. The analysis of the dependences of the temperature coefficient of resistance (TCR) and ρ of VOx films on the annealing temperature showed that, upon annealing, ρ and TCR slightly decrease, i. e. there occurs a partial deoxidation of the films. However, unlike annealing at atmospheric pressure, there are no temperature regions at which a sharp decrease in the resistivity and TCR occurs.
A brief description of information system for nuclear material accounting developed for the national regulator in the field of nuclear and radiation safety - the Department for Nuclear and Radiation Safety of the Ministry of Emergency Situations of the Republic of Belarus (Gosatomnadzor) is given. The information system is a part of the Intellectual information system of a Gosatomnadzor employee to ensure control (supervision) in the field of nuclear and radiation safety. It is developed on the basis of free software. The system has been implemented in Gosatomnadzor and at present in the Republic of Belarus all nuclear material accounting with reporting to the IAEA is carried out with its help. The system, in full compliance with the IAEA requirements, provides automatic generation with all the necessary calculations based on the input data of the following reporting documents: physical inventory listing, inventory change report, material balance report, textual report, General Ledger. All reports are fully consistent each with other. An efficient mechanism has been developed for importing and exporting data from / to the system according to formats of fixed and labelled Code 10 required by the IAEA. All logs of the system describing reports contain a field “IAEA approved” (yes / no). If it set to “yes”, they are closed for editing and correction. A special tool has been developed for making adjustments to these documents in accordance with the IAEA rules. The system contains fully completed reference books (small journals referenced by all major journals in the database) with the necessary reference data in accordance with Code 10. The information system meets all the IAEA requirements for such systems of national regulators in the field of accounting, control and supervision of nuclear material. It can be easily translated into other languages and adapted for the needs of accounting and control of nuclear material in operating organizations.
Investigations of the thickness and optical characteristics of thin SiO2 films obtained by one-, two-, or three-stage rapid thermal processing (RTP) at atmospheric pressure, pulses of 6, 12, and 20 s duration have been carried out. To obtain thin SiO2 films by the RTP method, N-type:Ph 4.5 Оhm/□ (100) silicon wafers were used as initial samples. The samples were preliminarily oxidized at 1000 °C of the obtained wet oxygen (SiO2 d = 100 nm), then the silicon oxide was completely removed in a solution of hydrofluoric acid, after which the wafers were subjected to chemical cleaning using the Radio Corporation of America (RCA) technology. Oxidation in a stationary oxygen atmosphere was carried out in one or two stages by heating the plates with a light pulse of different power up to maximum temperatures of 1035 – 1250 °C, as well as a three-stage process, where the final stage was annealing in a nitrogen atmosphere or in a forming gas (N2 97% + H2 3%). The characteristics of SiO2-Si barrier structures nitrided in N2, obtained by the RTP process by light fluxes with pulses of a second duration, were studied to improve the electrophysical parameters of gate oxides by the RTP method. It is of interest for integrated circuits (ICS) with a high density of the active regions of devices.
ISSN 2708-0382 (Online)