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905 This Letter is devoted to the optical anisotropy arising in a moving medium, where the velocity of light propagation depends on the velocity and direction of motion of the medium. In a rotating medium, the light trajectory is curved The transverse entrainment can be observed for radiation propagating in a rotating optical disk (OD). In 1977, Bilger and Stowell [2] performed an experiment with light propagating in a rotating OD arranged in a laser ring interferometer. The results were interpreted in terms of the Fizeau effect. However, since the rotating disk features a tangential discontinuity of the light propagation velocity on the flat surface, the phase shift in circulating electromagnetic waves was related to both longitudinal and transverse entrainment of the wave. This is confirmed by calculations based on a solution to the dispersion equation, which show that an additional shift of the interference pattern in such experiments can amount to about 20% of the value due to the longitudinal Fizeau effect Below, we consider the results of interferometric experiments in which the optical anisotropy of light propagating in a rotating transparent medium has been studied as a function of the rotation speed. Here, by the optical anisotropy we imply the dependence of the velocity of light on the velocity and direction of motion of the medium where it propagates. The entrainment of light in a moving medium was studied using an interferometer, in which the light was introduced via a flat surface of a rotating OD In the proposed scheme, the beam of laser L is divided by beam splitter BS into two beams. These beams are directed by mirrors M 1 and M 2 so as to pass via the OD in opposite directions. As a result of the OD rotation, one beam acquires a positive, and the other beam, a negative phase shift. Then, the two beams are mixed in the BS, and the mixed beam directed by mirror M 3 passes through optical system OS and strikes photodetector PD. Reversal of the direction of OD rotation leads to a change in the direction of the shift of interference fringes observed in the aperture plane of the PD. The optical path length in the OD was increased due to the multiple reflection of beams from mirror flat surfaces (the front flat surface was mirror coated in the central part, and the rear surface was entirely mirror coated). To the first approximation, the proposed scheme is equivalent to a one-pass Fizeau interferometer. Let us Abstract -We consider the first results of measurements of the effect of a velocity vector field in a rotating transparent medium on the light propagation velocity c in this medium. Laser radiation with a wavelength of λ = 0.632991 µ m passed through a rotating optical disk with n = 1.7125 in an interferometer, where the beam path length projected on the flat disk surface was l = 30.4 mm, the disk thickness was d = 20 mm, and the angle of light incidence on the flat disk surface was ϑ 0 = 50.7 ° . The disk rotation speed was varied up to 380 Hz, which corresponded to a projection of V 2 n = 36 m/s of the medium velocity onto the wave vector of the electromagnetic wave. The experimental data confirmed to the first approximation the classical linear dependence of the shift of interference fringes on the velocity of a rotating medium

Применение метода корреляции цифровых изображений для построения диаграмм деформирования в истинных координатах

This article describes the features of determining strain curves in true stress–true strain coordinates, using samples of circular cross section from Al–Cu–Mg–Zn aluminum alloy. The calculation and experimental methods of determining true stresses and strains were compared Calculation methods based on the condition of volume constancy may not reflect actual regularities of deformation at the stage of strain localization in the considered material. Nevertheless, the use of systems of digital image correlation (DIC) allows measurements of both the geometrical sizes of deformed sample and strain fields on its surface to be performed, including on the sample neck. It was demonstrated that the measurement error of the sample diameter by the coordinate field was 0.02 mm at the instance of destruction. In order to improve the measurement precision, an increase in the recording frequency in proportion to increase in strain rate was proposed, as well as measuring the surface coordinates from both sides of the sample. It is also possible to supplement the strain curves obtained by DIC optical systems with the measurements of true fracture stress, and the true fracture strain determined by calculations on the destructed sample. The presented methods of analysis of plastic flow by direct measurement of field displacements and strains allow actual regularities between true stresses and strains at the interval of irregular plastic strain to be established. This cannot be achieved by analytical conversion of conventional curve. The obtained hardening coefficients and strain curves can be used for simulation and design of machinery structures and parts.Приведены особенности определения диаграмм деформирования в координатах «истинное напряжение – истинная деформация» на образцах круглого сечения из алюминиевого сплава системы Al–Cu–Mg–Zn. Выполнено сравнение расчетных и экспериментальных методов определения истинных напряжений и деформаций. Расчетные методы, основанные на применении условия постоянства объема, могут не отражать действительных закономерностей деформирования на этапе локализации деформации в материале исследуемого образца, в то время как использование систем корреляции цифровых изображений (КЦИ) позволяет проводить измерения как геометрических размеров деформируемого образца, так и полей деформаций на его поверхности, в том числе непосредственно в шейке образца. Показано, что ошибка измерения диаметра образца по полю координат в момент разрушения составила 0,02 мм. С целью повышения точности измерения предложено увеличение частоты съемки пропорционально возрастанию скорости деформирования, а также проведение измерения координат поверхности с двух сторон образца. Также возможно дополнять полученные с помощью оптических систем КЦИ кривые деформирования результатами измерения истинного разрушающего напряжения и истинной разрушающей деформацией, определенными расчетным способом по разрушенному образцу. Представленные способы исследования пластического течения материала непосредственным измерением полей перемещений и деформаций позволяют устанавливать действительные закономерности между истинными напряжениями и деформациями на участке неравномерного пластического деформирования, чего достичь аналитическим пересчетом условной диаграммы невозможно. Полученные коэффициенты упрочения и кривые деформирования могут быть использованы при моделировании и проектировании конструкций и деталей машин

КОНТРОЛЬ «ЖЕЛТОЙ» ФОТОЛЮМИНЕСЦЕНЦИИ ГЕТЕРОСТРУКТУР AlGaN/GaN

Photoluminescence with the peak corresponding to yellow light in the visible spectrum (the so−called yellow luminescence) is generated by deep levels in the buffer GaN layer of the ehterostructures and depeonds on heterostructure growth conditions. In turn, the deep levels affect the resistivity of the ohimic contacts of RF transistors based on these heterostructures. This determines the reliability of GaN HF transistor operation. Two types of instruments have been developed for controlling photoluminescence with the peak in the yellow spectral region for characterizing the quality of AlGaN/GaN/SiC and AlGaN/GaN/Al2O3 heterostructures. One of them provides for rapid control of yellow photoluminescence and the other allows mapping of photoluminescence across the heterostructure area. Examples of photoluminescence maps for experimental structures grown on different substrates have been given.Фотолюминесценция с максимумом, соответствующим желтому цвету свечения видимого спектра (так называемая желтая люминесценция), определяется глубокими уровнями в буферном слое GaN гетерооструктур и зависит от условий роста гетероструктур. В свою очередь, глубокие уровни влияют на сопротивление омических контактов СВЧ−транзисторов, изготовленных на таких гетероструктурах. Это обуславливает надежность работы СВЧ−транзисторов на основе GaN.Разработаны два типа установок для контроля фотолюминесценции c максимумом в желтой части видимого спектра, предназначенные для характеризации качества гетероструктур AlGaN/GaN/SiC и AlGaN/GaN/Al2O3. Одна их представленных установок позволяет проводить «экспресс− контроль» желтой фотолюминесценции, а другая — снимать «карты» фотолюминесценции по площади пластин с гетероструктурами. Приведены примеры «карт» фотолюминесценции для структур, выращенных на различных подложках

Condition, problems and trends of technological development in Russia

Today, technological development appears in several forms: on the one hand, it is an objective consequence of scientific and technological progress, on the other hand, it is an instrument that should lead to the accelerated socio-economic development of the country and increase the well-being of society. For Russia, ensuring technological development is paramount. However, despite the goals stated in the strategic documents of the Russian government, the state of the level of technological development of Russia in comparison with other countries of the world is not satisfactory. In a condition of the digital transformation of the economy and the unconditional desire for an innovative economic model, this issue is particularly relevant for Russia. Radical technological changes are currently the main driver of overcoming the crisis and the transition to an innovative economy. Russia is lagging behind in the global market in terms of technological development. The analysis of the situation shows that there is a serious gap between the planned and actual level, which leads to difficult problems for Russia on the path of technological development in the near future. The aim of the study is to attract the attention of researchers to the discussion of the identification of the state of technological development of the country, modernization of models of technological development and search for tools for intensification of technological development in Russia. The article presents a retrospective of economic and technological development theories, their main ideas and limitations. Considerable attention is paid to the analysis of the essence of the main economic categories of the research field and related approaches to assessing the level of technological development of the country. The authors identified and systematized the features of Russia’s technological development in comparison with other countries of the world, analyzed the main problems and limitations of technological development in Russia at the present time. The use of the system and structural analysis, the connection of historical and logical, the analysis of actual and statistical material ensured the objectivity of the conclusions. The main results are related to the identification of the categories «technology» and «technological development», the systematization of theoretical and practical research experience on this issue, the identification of the state of the level of technological development in Russia and the assessment of its problems and prospects. The results of the study can be taken into account in the development of macroeconomic policy, used as a theoretical basis for further research of technological changes and their impact on economic development and economic growth

Biosynthesis of Bacterial Cellulose by Extended Cultivation with Multiple Removal of BC Pellicles

Extended cultivation with multiple removal of BC pellicles is proposed herein as a new biosynthetic process for bacterial cellulose (BC). This method enhances the BC surface area by 5–11 times per unit volume of the growth medium, improving the economic efficiency of biosynthesis. The resultant BC gel-films were thin, transparent, and congruent. The degree of polymerization (DP) and elastic modulus (EM) depended on the number of BC pellicle removals, vessel shape, and volume. The quality of BC from removals II–III to VII was better than from removal I. The process scale-up of 1:40 by volume increased DP by 1.5 times and EM by 5 times. A fact was established that the symbiotic Medusomyces gisevii Sa-12 was adaptable to exhausted growth medium: the medium was able to biosynthesize BC for 60 days, while glucose ran low at 24 days. On extended cultivation, DP and EM were found to decline by 39–64% and 57–65%, respectively. The BC gel-films obtained upon removals I–VI were successfully trialed in experimental tension-free hernioplasty

КОНТРОЛЬ «ЖЕЛТОЙ» ФОТОЛЮМИНЕСЦЕНЦИИ ГЕТЕРОСТРУКТУР AlGaN/GaN

Photoluminescence with the peak corresponding to yellow light in the visible spectrum (the so−called yellow luminescence) is generated by deep levels in the buffer GaN layer of the ehterostructures and depeonds on heterostructure growth conditions. In turn, the deep levels affect the resistivity of the ohimic contacts of RF transistors based on these heterostructures. This determines the reliability of GaN HF transistor operation. Two types of instruments have been developed for controlling photoluminescence with the peak in the yellow spectral region for characterizing the quality of AlGaN/GaN/SiC and AlGaN/GaN/Al2O3 heterostructures. One of them provides for rapid control of yellow photoluminescence and the other allows mapping of photoluminescence across the heterostructure area. Examples of photoluminescence maps for experimental structures grown on different substrates have been given.Фотолюминесценция с максимумом, соответствующим желтому цвету свечения видимого спектра (так называемая желтая люминесценция), определяется глубокими уровнями в буферном слое GaN гетерооструктур и зависит от условий роста гетероструктур. В свою очередь, глубокие уровни влияют на сопротивление омических контактов СВЧ−транзисторов, изготовленных на таких гетероструктурах. Это обуславливает надежность работы СВЧ−транзисторов на основе GaN.Разработаны два типа установок для контроля фотолюминесценции c максимумом в желтой части видимого спектра, предназначенные для характеризации качества гетероструктур AlGaN/GaN/SiC и AlGaN/GaN/Al2O3. Одна их представленных установок позволяет проводить «экспресс− контроль» желтой фотолюминесценции, а другая — снимать «карты» фотолюминесценции по площади пластин с гетероструктурами. Приведены примеры «карт» фотолюминесценции для структур, выращенных на различных подложках