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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ИССЛЕДОВАНИЕ КИНЕТИКИ ТЕРМИЧЕСКОГО РАЗЛОЖЕНИЯ ПИРОЛИЗНОЙ СМОЛЫ
Get PDFОбсуждаются результаты экспериментального исследования термического разложения смолы, образовавшейся в процессе пиролиза древесных опилок. Опыты по разложению смолы выполнены в изотермических условиях на лабораторной установке при 500, 600, 700 и 850 °С. Определены скорость гомогенного процесса термического разложения смолы и предельные степени разложения. Энергия активации гомогенного процесса по данным настоящей работы составила 63,1 кДж/моль. Установлено, что скорость термического разложения смолы повышается в случае внесения в реакционную зону образцов природных доломитов Беларуси. Это обусловлено протеканием гетерогенной каталитической реакции разложения смолы. Кажущаяся энергия активации данного процесса составила 57,2 кДж/моль, что согласуется с оценками других исследователей. Сделан вывод о перспективности природных доломитов Беларуси в качестве катализаторов термического разложения тяжелых углеводородов, образующихся в процессах термохимической конверсии биомассы
АППАРАТНО-ПРОГРАММНЫЙ КОМПЛЕКС АВТОМАТИЗИРОВАННОГО ПОИСКА С ВОЗМОЖНОСТЬЮ ИДЕНТИФИКАЦИИ РАДИОЭЛЕКТРОННЫХ СРЕДСТВ СКРЫТОГО СЪЕМА ИНФОРМАЦИИ
Get PDFАn overview of main characteristics of modern non-linear radiolocators is presented. The main factors that negatively affect the health of operator are identified. The analysis of the effective methods of searching, detection and identification of covert radioelectronic means is carried out. It is noted that the accuracy of the radio-electronic means identification depends on the selection criteria of the classification system. It presents a fundamentally new way to recognize the type of semiconductor based on the use of a special probing AM-signal with suppressed carrier (DSB-signal). The possibility of automated identification on the basis of developed method of nonlinearity recovery is demonstrated. The results of modern and developed methods in the form of a chart of their performance are provided. The block-diagram of hardware-software system developed for detection and identification of covert radioelectronic means is designed. The term «identity portrait» is deseribed. A method for producing an identification portrait is introduced. The work presents the real current-voltage characteristics of I307G and D18 diodes and reconstructed ones performed by calculating the approximating polynomial coefficients of the third degree. Identification portraits of I307G and D18 diodes are provided
ОСОБЕННОСТИ ИСПОЛЬЗОВАНИЯ МЕТОДА МОНТЕ-КАРЛО ДЛЯ АППРОКСИМАЦИИ СТАТИСТИЧЕСКИХ РАСПРЕДЕЛЕНИЙ РЕЗУЛЬТАТОВ НЕЛИНЕЙНЫХ ПРЕОБРАЗОВАНИЙ В РАДИОЛОКАЦИОННЫХ ЗАДАЧАХ
Get PDFAn approach to the decision of mathematical problems with use of modelling random variables, the method which has received the name of Monte-Carlo is considered. The given method has got the greatest popularity for numerical calculation of high frequency rate integrals because it is rather easily realised on modern computers.Possibility of use Monte-Carlo method for statistical approximation of radar-tracking data distributions at which the initial density of probability is replaced with its discrete analogue, which formed on the basis of random samples (particles) weights is illustrated. Nonlinear transformations of observable data are widely used at the decision of some problems connected with processing of random realisations of observable signals (radar-tracking, radio navigating, coherent, etc.) Noted transformations inevitably lead to transformation of distribution laws of the solving statistics which results it is rather difficult described by analytical methods. In article the basic features of application statistical approximation method for typical distributions, formed as a result of nonlinear transformations of radar-tracking observation data are considered. It is shown, that at some nonlinear transformations errors of law the distributions approximations caused by effect «scanty» of sample are observed. It is shown, that the effect «scanty» samples is overcome by a resampling of random particles ina vicinity of the most significant samples. The resulted material allows to expand a scope of the numerical methods, based on use of modelling random variables
ОПТИМИЗАЦИЯ СОСТАВА ПОЛИМЕРНОЙ КОМПОЗИЦИИ И ПАРАМЕТРОВ ТЕХНОЛОГИЧЕСКОГО ПРОЦЕССА ДЛЯ ТЕРМОГЕРМЕТИЗАЦИИ СПЕЦИАЛЬНОЙ ЗАЩИТНОЙ ОДЕЖДЫ ПОЖАРНЫХ
Get PDFNow broad application at production of special protective clothes of firefighters is found by the metallized materials steady against influence of fire and high temperatures and thermal streams. Application of traditional ways of a fastening of details from the metallized materials with a film covering, steady against influence of fire, high temperature and thermal streams, promotes formation of connections with low operational and heat-physical characteristics. There is a need for creation of technology solutions providing release of qualitative, reliable samples of special protective clothes for firefighters, made from heat- and fire-resistant metallized materials. Main methodological approaches used at optimization of structure of the thermo-sealing composition and parameters of technological process chosen for realization of original technology of thermo-sealing and hardening of knots and connections of special protective firefighter’s clothes from increased thermal influences are stated. The objective is solved with use of methods of mathematical planning of a multifactor experiment and a simplex planning. The expense of polymeric composition, mass of fire-retarding agent, time and temperature of contact drying are chosen as the varied factors. The indicators “Explosive loading at stretching perpendicular to a seam” and “An oxygen index” are the criteria of optimization. The rational combination of the components of the thermo-sealing composition and the parameters of the technological process for obtaining strong, fire-resistant joints details of special protective firefighter’s clothing is determined. The developed recipe of the thermo-sealing composition and the parameters of the technological process have been tested at production of fragments of heat-shielding firemen’s suits
ВЛИЯНИЕ РЕЖИМА ЭЛЕКТРОЛИЗА НА ОБРАЗОВАНИЕ «УСОВ» В ПОКРЫТИЯХ НА ОСНОВЕ ОЛОВА
Get PDFThe article is devoted to the investigation of potential defects that can appear in thin-film electrochemical coatings based on tin, which do not contain lead, during their long storage. The purpose of the study is to develop technological regimes of electrolysis, which ensure minimization of the probability of the appearance such defects and reliable operation of radio electronic equipment The problems of tin and lead-free alloys based on it, as well as methods of elimination of such potential defects as the formation of “whiskers” are considered. To control the growth of “whiskers” in the post-electrolysis period (12 months of natural aging under laboratory conditions), a Sn-Bi coating was chosen, which was formed using both a constant and a pulse-reversed current. Based on the results which were obtained with scanning electron microscope, it was established that deposition of an alloy using pulsed and reverse current not only improves the structure of the coatings formed, but also significantly reduces the propensity to form whiskers, their length and density per unit area in comparison with coatings obtained with direct current. Possible reasons for achievement of high quality electrochemical coatings with Sn-Bi alloy have been established. The slowest growth of “whiskers” was obtained at reversed current with an average density i av= 2 A/dm2, frequency f = 1 Hz and duty ratio γ = 1.5.
ЭЛЕКТРОХИМИЧЕСКИ ОСАЖДЕННЫЕ ПОКРЫТИЯ НА ОСНОВЕ ВИСМУТА И ЭФФЕКТИВНОСТЬ ИХ ЗАЩИТЫ ОТ ЭЛЕКТРОННОГО ИЗЛУЧЕНИЯ
Get PDFMicroelectronic products are widely used in aerospace, aviation, military and nuclear engineering. However, they are very sensitive to various ionizing radiations (electrons, protons, heavy charged particles, X-ray and gamma radiation). The common used material for radiation protection is lead. In recent years, bismuth deposition has become an interesting subject for the electrochemical community because of bismuth’s unique electrical, physical and chemical properties. There is a limited number of authors dealing with continuous bismuth films onto metallic substrates by electrodeposition. The conditions of electrochemical deposition of bismuth and the structure of coatings were examined. Electrochemical deposition with the inputted various organic additives and without them was carried out. It is shown that bismuth coatings have a rhombohedral lattice, and thаt adding of a number of organic additives into the electrolyte results changing in a coatings growth texture. The protection efficiency of shields based on bismuth under 1.6–1.8 MeV electron irradiation energy was measured. The electron beam attenuation efficiency was estimated by changing of current-voltage characteristics of semiconductor test structures which were located behind the shields and without them. It has been determined that bismuth shields with 2 g/cm2 reduced thickness and attenuation coefficient of 156 have optimal protection effectiveness and mass dimensional parameters
ОПРЕДЕЛЕНИЕ ОСНОВНЫХ ПАРАМЕТРОВ СИСТЕМЫ ОХЛАЖДЕНИЯ ЭНЕРГЕТИЧЕСКОГО БЛОКА НА ОСНОВЕ СУХИХ ГРАДИРЕН
Get PDFA technique for calculation of thermohydraulic and mass-sized parameters of a cooling system based on a dry cooling tower and applied in power units is described. The calculations were performed for the heat load on a tower of 1000 MW. The height of the concrete tower was 180 m. Heat exchange column, made from steel ribbed galvanized pipes with the diameter of 22×1.5 mm and a length of 20 m had standard dimensions: width – 2.4 m, height – 20 m. Determination of the minimum reduced costs for the studied parameters allowed justifying the choice of the best values in the cooling system of the power unit. The minimum reduced costs correspond to 4-row bundle with 2-way traffic pattern chilled water. The optimal parameters of fin match the height of the rib – 7 mm fin step – 3.5 mm, the distance between the finned tubes – 2 mm. The optimal number of columns on a heat exchange cooling tower is 600 pcs., with cooling of the water in a cooling tower at 10 °C. The analysis of changing of mass-sized and cost values has been carried out and the alternative design of the cooling system for the power unit with the capacity of 1200 MW is propose
ИСПОЛЬЗОВАНИЕ ВНЕШНИХ ЭЛЕКТРИЧЕСКИХ ПОЛЕЙ ПРИ ДОВОДКЕ РАСПЛАВОВ В ПЛАВИЛЬНЫХ АГРЕГАТАХ
Get PDFSome advanced methods for alloy composition regulation at negligible consumption of slag-forming additives are suggested. When implementing the proposed technology, the slag functions as a protector and electric conductor, and redox processes are determined by the magnitude and the applied potential function. Both cathodic and anodic polarization of aluminum alloys in alundum and graphite crucibles is studied with the curves polarization method. The behavior of components of aluminum alloys is studied under external cathodic and anodic effects of the melt with a constant electric field. During the cathode polarization there is a significant decrease of Mg loss in the aging process of the melt; on the contrary, anodic polarization increases the loss in comparison with the melting without external electrochemical action. The content of Fe and Ni under anodic polarity of the melt is not reduced if it is compared to the melting without electrochemical action due to passivation. The elements at the end of the electrochemical series are mostly protected. Thus, copper is wasted less under the cathodic and, especially, anodic polarization.
О РОЛИ ОТЕЧЕСТВЕННОЙ НАУКИ В РАЗВИТИИ АТОМНОЙ ЭНЕРГЕТИКИ В РЕСПУБЛИКЕ БЕЛАРУСЬ
Get PDFThe history of the development of nuclear science researches in the nuclear center of the Republic of Belarus is described. There were two State programs in Belarus devoted to the problems of the nuclear power. One of them was finished in 2010. Within the program, there have been resolved such tasks as: necessity of the nuclear power engineering, selection of the site for the nuclear power plant, developments of the legislation and regulations to ensure nuclear and radiation safety, as well as project of the strategy for radioactive waste management and spent fuel management. At the second stage for fulfilling the tasks of development and implementation of scientific and technical suggestions, the State program «Scientific support of nuclear power development in the Republic of Belarus for 2009–2010 and for the period till 2020» is carried out. The results of researches within the second program for 2013–2015 years are presented