Interfacial dynamics in transport-limited dissolution

Various model problems of ``transport-limited dissolution'' in two dimensions are analyzed using time-dependent conformal maps. For diffusion-limited dissolution (reverse Laplacian growth), several exact solutions are discussed for the smoothing of corrugated surfaces, including the continuous analogs of ``internal diffusion-limited aggregation'' and ``diffusion-limited erosion''. A class of non-Laplacian, transport-limited dissolution processes are also considered, which raise the general question of when and where a finite solid will disappear. In a case of dissolution by advection-diffusion, a tilted ellipse maintains its shape during collapse, as its center of mass drifts obliquely away from the background fluid flow, but other initial shapes have more complicated dynamics.Comment: 5 pages, 4 fig

Application Of Rf (13.56 MHz) Arc Discharge For Plasma Chemical Conversion Of Volatile Fluorides

The report discusses the use of a new type of plasma source of hydrogen plasma based on a RF (13.56 MHz) arc discharge of atmospheric pressure between two electrodes. This discharge was used for hydrogen reduction of the tetrafluorides of silicon, boron and molybdenum. As a result of the studies, the main regularities of the hydrogen reduction process were established and the main synthesized products were determined. Samples of carbides of silicon, boron and molybdenum were prepared

Novel Regime of Operation for Superconducting Quantum Interference Filters

A new operating regime of the Superconducting Quantum Interference Filter (SQIF) is investigated. The voltage to magnetic field response function, V(H), is determined by a Fraunhofer dependence of the critical current and magnetic flux focusing effect in Josephson junctions (F-mode). For SQIF-arrays made of high-Tc superconducting bicrystal Josephson junctions the F-mode plays a predominant role in the voltage-field response V(H). The relatively large superconducting loops of the SQIF are used for inductive coupling to the external input circuit. It is shown that the output noise of a SQIF-array measured with a cooled amplifier in the 1-2 GHz range is determined by the slope of the V(H) characteristic. Power gain and saturation power were evaluated using low frequency SQIF parameters. Finally, we consider the influence of the spread in the parameters of Josephson junctions in the SQIF-array on the V(H) characteristic of the whole structure.Comment: 7 pages, 4 figure

Application of RF (13.56 MHz) Arc Discharge for Plasma Chemical Conversion of Volatile Chlorides of Silicon and Germanium.

The processes of hydrogen reduction of silicon and germanium chlorides are studied under RF conditions (40.68 MHz) of contracted atmospheric pressure arc discharge stabilized between two rod electrodes. The main gas-phase and solid products of plasma-chemical transformations are determined. Using the hydrogen reduction of SiCl4 as an example, the numerical simulation of gas-dynamic and heat exchange processes for this type of discharge was performed. The studies were carried out for the optimal conditions for obtaining trichlorosilane using modern computational technologies of fluid dynamics which made it possible to detail the velocity and temperature fields, the gas flow rates in the plasma region, and also determine the main temperature zones affecting the hydrogen reduction process

Учет паразитных эффектов при измерении эффективной диэлектрической проницаемости методом четвертьволнового резонатора

The analysis, approximations and accounting of the influence of the main parasitic effects that affect the results of the measurement are provided in this paper. The method of dielectric constant measurement of coaxial connectors support beads is suggested. The comparison between the acquired results using the suggested method and the reference is made. The results suggest that the method can be used for dielectric constant measurement of the coaxial connector support beads with the accuracy comparable to the method of the volume resonator for rod samples H01p by GOST 8.623-2015. В статье предложена методика измерения диэлектрической проницаемости опорных шайб коаксиальных соединителей на основе четвертьволнового коаксиального резонатора. Проведен анализ, аппроксимация и учет паразитных эффектов, оказывающих наибольшее влияние на результат измерения диэлектрической проницаемости. Проведено сравнение результатов измерения шайб из разных материалов по предложенной методике с диэлектрической проницаемостью, измеренной на эталонной установке. Полученные результаты говорят о точности измерения эффективной диэлектрической проницаемости шайб по предложенному методу, сравнимой с точностью метода объемного резонатора для стержневых образцов H01p по ГОСТ 8.623-2015.Коренев А. В., Гошин Г. Г. Учет паразитных эффектов при измерении эффективной диэлектрической проницаемости методом четвертьволнового резонатора. Ural Radio Engineering Journal. 2021;5(3):272–283. DOI: 10.15826/urej.2021.5.3.005.

"MARKS" SMALL AVIATION-ROCKET SPACE LAUNCH SYSTEM

The problems of delivery of small space vehicles into low earth orbits are pointed out. The up-to-date means for the ascent of small space vehicles into low earth orbits are analysed. The solution for responsive and economical ascent of small space vehicles into low earth orbits in the form of "MARKS" small aviationrocket space launch system is offered. Implementation of the offered idea will provide the price of delivery of 1 kg payload into 500 km sun-synchronous orbit equal to 3750 US dollars

Многоуровневый вейвлет анализ в задаче сегментации электрокардиограмм

Пропонується алгоритм сегментації електрокардіограм (ЕКГ) з використанням багаторівневого вейвлет аналізу сигналів. Алгоритм був протестований, на прикладах кардіограм, що були взяті з міжнародної бази даних електрокардіограм MIT-BIH Arrhythmia Database. Тестовий матеріал має широкий набір форм: нормальні та патологічні сигнали, сигнали, ускладнені шумами різних частот та потужностей. Точність локалізації QRS комплексу ЕКГ складає 98%, точки J – 95%, T зубця – 86%, P зубця – 80%.This article proposes an electrocardiogram (ECG) segmentation algorithm, using multi-resolution wavelet analysis of signals. The algorithm was tested using ECG taken from international electrocardiogram databases: MIT-BIH Arrhythmia Database. Test material has a wide range: normal and pathological signals, signals, complicated by noise of different frequencies and capacities. Accuracy of ECG QRS complex localization is 98%, the point J - 95%, T wave - 86%, P wave - 80%.Предлагается алгоритм сегментации электрокардиограмм (ЭКГ) с использованием многоуровневого вейвлет анализа сигналов. Алгоритм был протестирован на примерах кардиограмм, которые были взяты из международной базы данных электрокардиограмм MIT-BIH Arrhythmia Database. Тестовый материал имеет широкий набор форм: нормальные и патологические сигналы, сигналы, осложненные шумами различных частот и мощностей. Точность локализации QRS комплекса ЭКГ составляет 98%, точки J - 95%, T зубца - 86%, P зубца - 80%