Thermoelectric prospects of nanomaterials with spin-orbit surface bands

Nanostructured composites and nanowire arrays of traditional thermoelectrics like Bi, Bi(1-x)Sb(x) and Bi(2)Te(3) have metallic Rashba surface spin-orbit bands featuring high mobilities rivaling that of the bulk for which topological insulator behavior has been proposed. Nearly pure surface electronic transport has been observed at low temperatures in Bi nanowires with diameter around the critical diameter, 50 nm, for the semimetal-to semiconductor transition. The surface contributes strongly to the thermopower, actually dominating for temperatures T < 100 K in these nanowires. The surface thermopower was found to be -1 T microvolt/(K^2), a value that is consistent with theory. We show that surface electronic transport together with boundary phonon scattering leads to enhanced thermoelectric performance at low temperatures of Bi nanowire arrays. We compare with bulk n-BiSb alloys, optimized CsBi(4)Te(6) and optimized Bi(2)Te(3). Surface dominated electronic transport can be expected in nanomaterials of the other traditional thermoelectrics.Comment: 18 pages, 3 figure

Формування та оцінка податкового потенціалу регіонів України

У статті розглянуті теоретичні підходи до розкриття сутності поняття «податковий потенціал», досліджено питання оцінки податкового потенціалу, а також запропоновано науково-методичні підходи щодо визначення впливу податкового потенціалу на соціально-економічний розвиток регіонів України. The article deals with theoretical approaches to elucidate the essence of the concept of “tax a potential”, theoretical approaches to determination of tax potential and suggested the scientific and methodical approaches to determined the impact of tax potential to the social and economic regional’s development

Guidelines to individual tasks on discipline «Economic theory» for full-time students and distance learning training directions: 6.030502 «Economic Cybernetics», 6.030503 «International Economics», 6.030507 «Marketing»

Методичні вказівки підготовлені відповідно до кредитно-модульної системи в організації навчального процесу.Methodical instructions are prepared according to credit-modular system to the organization of educational process

Automation of optimization synthesis for modular technological equipment

Technological equipment design based on functionally modular methods is widely used in various technical fields. The designed object can be a technological machine, a production line, or a manufacturing complex. Special attention is paid to the optimization of its structure. The sequence of performing all stages of the optimization synthesis problem is presented in the article. To find a solution to this task, the developer should apply the complete or directed search of acceptable structure options and determine the best one using some optimization criteria to evaluate their quality. It can be simple enough if the designed technical system structure consists of no more than several elements. For example, if the number of alternative elements options is several dozen, it takes much time to accomplish the search correctly. Thus, the greater the number of components considered, the more difficult it is to do all the necessary calculations manually. In this case, machine resources should be involved. This scientific work aims to identify procedures of optimization synthesis that can be automated. Also, appropriate software has to be developed. Our computer program is based on the algorithm of a complete search of all options of the technical system structure. It can process an extensive array of input data and produce all possible and logically permissible results in the form the designer can analyze using the Pareto method to choose the best one. This software can be used for any technical system with a modular structure.info:eu-repo/semantics/publishedVersio

Impact of technological system’s characteristics on the machining accuracy of bearing rings

The article shows the influence of the technological system of an automated lathe, in particular cam chucks, on the accuracy of machining bearing rings for production conditions. The value of the deformation during machining, i.e., the non-circularity of the ring of a single row tapered roller bearing 32017X in outer diameter, was investigated. For the study, samples were selected that were processed under the same conditions directly in the production unit of PJSC “SKF Ukraine” without interference with the technological process. The use of replaceable floating cams in the chuck design was proposed to increase the accuracy and productivity of machining. Experimental studies have shown that the machined surface’s ovality depends on the chuck cams’ clamping force. The effectiveness of computer processing of statistical data on the accuracy control of engineering products was shown. Implementing machining accuracy control in production using the Minitab computer program was presented. It was proven that the quality of products is formed under the influence of the use of modern computer technologies at all stages of manufacturing and control of parts, which ensures research in a wide range of changes in technological parameters and comparison of individual studies with actual machining conditions on the machine, with the results of a sufficient level of reliability

Получение компактной меди из карбонатной руды электрохимическим способом

Розглянуто процес електроекстракції міді з розчинів, отриманих вилуговуванням міді з карбонатної руди сульфатною кислотою. Показано, що обробку руди доцільно проводити 10 %-ною кислотою впродовж 30-40 хв при інтенсивному перемішуванні суміші. Здійснено процес електроекстракції міді з концентрованого розчину при ступеневому зниженні густини струму пропорційно до концентрації іонів міді, що зменшується в ході процесу. Виконано порівняння параметрів реального процесу і розрахованого за теоретично отриманими формулами. Встановлено, що прогнозування оптимального режиму електролізу можливо здійснювати за електрохімічними характеристиками, початковою концентрацією металу і геометричними параметрами електрохімічної комірки. Одержано експериментальну залежність напруги на електролізері від концентрації кислоти, іонів міді та густини катодного струму. Виявлено, що основною складовою напруги на електролізері є електрохімічна — різниця потенціалів електродів під струмом. Показано зменшення напруги в часі й розраховано питомі витрати електроенергії при отриманні міді методом електроекстракції.A process of compact copper electrowinning from the solution obtained by leaching copper from the ore by sulfuric acid was discussed. It was shown that the ore leaching is advisable to carry out with 10 % hydrochloric acid for 30-40 minutes with intensive stirring of the mixture. Copper electrowinning process was done from a concentrated solution with a stepped reduction of the current density which was proportional to the copper ion concentration decreasing during the process. The comparison of the parameters of the real and theoretical calculated processes was performed. It was found that the prediction of optimal electrolysis conditions can be achieved by electrochemical characteristics, initial metal concentration and geometric parameters of the electrochemical cell. An experimental cell voltage dependence of the acid concentration, copper ions and the cathode current density was determined. It was found that the main component of the cell voltage is electrochemical component — the difference potential at the electric current. The decreasing of the cell voltage in time was shown and the relative cost of electricity in the producing of copper by electrowinning was calculated.Рассмотрен процесс электроэкстракции меди из растворов, полученных выщелачиванием меди из карбонатной руды серной кислотой. Показано, что обработку руды целесообразно проводить 10 %-ной кислотой в течение 30-40 мин при интенсивном перемешивании смеси. Осуществлен процесс электроэкстракции меди из концентрированного раствора при ступенчатом снижении плотности тока пропорционально концентрации ионов меди, уменьшающейся в ходе процесса. Выполнено сравнение параметров реального процесса и теоретически рассчитанного по формулам. Установлено, что прогнозирование оптимального режима электролиза возможно осуществлять с использованием электрохимических характеристик, начальной концентрации металла и геометрических параметров электрохимической ячейки. Получена экспериментальна зависимость напряжения на электролизере от концентрации кислоты, ионов меди и плотности катодного тока. Определено, что основной составляющей напряжения на электролизере является электрохимическая — разность потенциалов электродов под током. Показано уменьшение напряжения во времени, рассчитаны дельные затраты электроэнергии при получении меди методом электроэкстракции

Development of functional purpose snacks

The article provides information on the development of new functional snacks based on local traditional and non-traditional raw materials. The uniqueness of the composition of snacks is associated with the presence in the recipe of dry mare's and camel's milk, as well as fruit and vegetable purees, dry strains of lacto and bifidobacteria, fucoidan and other food ingredients with increased nutritional and biological value. Evaluation of the chemical composition of the nutritional and biological value of snacks indicates their targeted antioxidant, detoxifying and immunostimulating properties. Functional snacks are recommended for use by the general public, including climbers, pilots of civil and military aviation, athletes, as well as in emergencies and conditions that adversely affect human health

Radial-piston pump for drive of test machines

The article reviews the development of radial-piston pump with phase control and alternating-flow mode for seismic-testing platforms and other test machines. The prospects for use of the developed device are proved. It is noted that the method of frequency modulation with the detection of the natural frequencies is easily realized by using the radial-piston pump. The prospects of further research are given proof