Analytical Solution for the Current Distribution in Multistrand Superconducting Cables

Current distribution in multistrand superconducting cables can be a major concern for stability in superconducting magnets and for field quality in particle accelerator magnets. In this paper we describe multistrand superconducting cables by means of a distributed parameters circuit model. We derive a system of partial differential equations governing current distribution in the cable and we give the analytical solution of the general system. We then specialize the general solution to the particular case of uniform cable properties. In the particular case of a two-strand cable, we show that the analytical solution presented here is identical to the one already available in the literature. For a cable made of N equal strands we give a closed form solution that to our knowledge was never presented before. We finally validate the analytical solution by comparison to numerical results in the case of a step-like spatial distribution of the magnetic field over a short Rutherford cable, both in transient and steady state conditions

Sustainment of High-Beta Mirror Plasma by Neutral Beams

The report presents two experiments carried out in Budker Institute for obtaining the maximum plasma beta (ratio of the plasma pressure to magnetic field pressure) in axially symmetric magnetic field. The experiments are based on injection of powerful focused neutral beams with high neutral power density in the plasma. The produced fast ion population significantly increases the plasma pressure. It the axially symmetric GDT experiment (Gas Dynamic Trap) the plasma beta exceeded 0.6 at the fast ion turning points. The CAT experiment (Compact Axisymmetric Toroid) is being prepared for obtaining a plasmoid with extremely high diamagnetism in axially symmetric magnetic field. Reversal of magnetic field in the plasmoid is possible in this experiment

Questions of providing with financial means and resources of economic entities, entrepreneurs and consumers

In the article some factors on acceleration of growth of national economy as a result of optimization of size of the key interest rate established to the Central Bank of the Russian Federation and the rate of inflation and ensuring steady and reliable work of a banking system of the country and innovative development of national economy are considered

Some directions of ensuring growth of national economy

In article problems and questions on acceleration ofgrowth ofnational economy, GDP, increase in labor productivity, development and introduction of achievements of scientific and technical (technological) progress, staffing of these processes in the country are considered and analyzed. Some offers and recommendations about implementation of these problems and questions are provided

Increase in overall performance of the enterprises and enterprise structures

In the article some problems and questions of entry of economy into the fourth industrial revolution, increases in efficiency of activity of the enterprises and entrepreneurs, formations of new hi-tech jobs, increases in labor productivity, processes of digitalization of economy are considered and analyzed

Acenaphthenoannulation Induced by the Dual Lewis Acidity of Alumina

We have discovered a dual (i. e., soft and hard) Lewis acidity of alumina that enables rapid one-pot π-extension through the activation of terminal alkynes followed by C−F activation. The tandem reaction introduces an acenaphthene fragment – an essential moiety of geodesic polyarenes. This reaction provides quick access to elusive non-alternant polyarenes such as π-extended buckybowls and helicenes through three-point annulation of the 1-(2-ethynyl-6-fluorophenyl)naphthalene moiety. The versatility of the developed method was demonstrated by the synthesis of unprecedented structural fragments of elusive geodesic graphene nanoribbons

TA INSTRUMENTS EQUIPMENT FOR FATIGUE TESTING OF STENTS AND IMPLANTS FOR CARDIOVASCULAR SYSTEM

В данной статье рассмотрены устройство и применение испытательных машин ElectroForce компании TA Instruments (США), для проведения широкого диапазона статических и многоцикловых испытаний и изучения физико-механических свойств материалов и готовых изделий. Особое внимание уделено применению систем ElectroForce для усталостных испытаний трансплантатов органов сердечно-сосудистой системы.Construction and application of ElectroForce test systems (TA Instruments, USA) for wide range of static and cycling tests and physical mechanical properties study of materials and complete products are described in this review. The focus attention is given to application of ElectroForce systems for long cycling testing of cardiovascular implants

Extracorporeal ultrasound exposure by the low-frequency acoustic amplitude-modulated signal on a ureteral stent for preventing its incrustation: experimental determination of optimal application points

Introduction. Incrustation and biofilms formation on the surface of ureteral stents are still the most significant complications of internal drainage of the upper urinary tract. There are much researchers conducted to combat these complications. The lack of a solution to this problem affects the ultimate results of treatment and economic losses. The issue of impact by physical methods on the ureteral stent, particularly the use of extracorporeal ultrasound acoustic exposure remains, promising and poorly covered.Purpose of the study. To determine the optimal application points of extracorporeal acoustic exposure by the low-frequency ultrasonic amplitude-modulated signal on a ureteral stent in an experiment.Materials and methods. The original device was designed. The main principle of its operation is the generation of an amplitude-modulated ultrasonic signal in two modes: pulsed and permanent. A sexually mature mongrel dog was an experimental animal. The ureteral stent was placed by laparotomy and cystotomy. Intraoperatively, the emitter of the developed device was applied to the skin of the animal, according to the previously indicated topographic and anatomical landmarks. At the same time, an ultrasonic wave noise analyzer was applied through the laparotomy wound to the appropriate level of the ureter. Measurements of ultrasound intensity indicators were performed three times in two operating modes of the device.Results. Pulsed mode: for the ureteral upper third, the highest ultrasonic intensity (123.67 dB) was achieved along the posterior axillary line. For the ureteral middle third, the best ultrasound intensity (115 dB) was obtained by the posterior axillary line. For the ureteral lower third, the highest ultrasound intensity (113.67 dB) was noted along the middle axillary line.Permanent mode: the best ultrasonic intensity in the projection of the ureteral upper, middle, and lower thirds was achieved along the posterior axillary line and was 118.67 dB, 117 dB and 116.67 dB, accordingly. However, there was an excessive heat effect, manifested by hyperemia and hyperthermia of the animal's skin, fascicular muscle contractions during the instrument functioned in the permanent mode, which can potentially lead to thermal burns and intolerance to the procedure.Conclusion. The pulsed mode of the device function is most safe. The optimal application points of the instrument emitter for the ureteral upper and middle thirds is the posterior axillary line, and for the ureteral lower third is the middle axillary line

Обоснование количества форсунок универсального вентиляторного опрыскивателя

The authors noted the disadvantages of fan sprayers such as OVH-600 and VP-1, associated with uneven application of pesticides due to the oscillatory motion of the working parts, especially in the junction of adjacent passages. (Research purpose) To increase the uniformity of the pesticide solution application over the entire width of the fan sprayer. (Materials and methods) The JV «Agriхim» developed a universal fan sprayer designed for the treatment of field crops, orchards and vineyards controlled by air-droplet flow. It was shown that the number of nozzles depends on the technological scheme of operation and the width of the sprayer. (Results and discussion) The authors determined the optimal number of injectors – 25 pieces. Depending on the flow rate of the working solution, three groups of tips were distinguished. (Conclusions) The authors revealed that the new design eliminates oscillatory movements of the working parts of the sprayer, a significant width (24 meters vs. 16 meters in production models) allows to increase dramatically the productivity of work, and the number of changeovers is minimized. They simplified and cheapened the design of the sprayer due to the rejection of a number of kinematic pairs and drives. They increased reliability of the unit, eliminating rubbing and moving parts and components. They presented the layout of 25 nozzles for high-quality pesticide treatment: 5 rear central nozzles were installed on the air ducts at an angle relative to the soil surface, and on the opposite direction of the air ducts placed 3 and 7 nozzles in each side of the axis of symmetry of the sprayer. It was calculated that the rate of flow of the working fluid in the range of 100-500 liters per hectare can be adjusted by changing the pressure in the system from 2 to 8 bar and the working speed from 3 to 7 kilometers per hour.Отметили недостатки вентиляторных опрыскивателей типа ОВХ-600 и ВП-1, связанные с неравномерностью внесения жидких средств химизации из-за колебательного движения рабочих органов. (Цель исследования) Повысить равномерность внесения раствора жидких средств химизации по всей ширине захвата вентиляторного опрыскивателя. (Материалы и методы) В СП «Agriхim» разработали универсальный вентиляторный опрыскиватель, предназначенный для обработки полевых культур, садов и виноградников управляемым воздушно-капельным потоком. Показали, что количество форсунок зависит от технологической схемы работы и ширины захвата опрыскивателя. (Результаты и обсуждение) Основными рабочими элементами универсального вентиляторного опрыскивателя, дозирующими норму внесения пестицидов, служат распыливающие наконечники, количество которых во многом зависит от технологической схемы работы и ширины захвата опрыскивателя. Определили оптимальное число форсунок – 25 штук. В зависимости от расхода рабочего раствора выделили три группы наконечников. (Выводы) Выявили, что в новой конструкции исключены колебательные движения рабочих органов опрыскивателя, значительная ширина захвата (24 метра против 16 метров в серийных моделях) позволяет резко повысить производительность работ, а число переналадок сведено к минимуму. Упростили и удешевили конструкцию опрыскивателя вследствие отказа от ряда кинематических пар и приводов. Повысили надежность агрегата, исключив трущиеся и движущиеся детали и узлы. Представили схему расположения 25 форсунок для качественной обработки пестицидами: 5 задних центральных установили на воздуховодах под углом относительно поверхности почвы, а на противоположно направленных воздуховодах разместили по 3 и 7 штук в каждой стороне от оси симметрии опрыскивателя. Рассчитали, что норму расхода рабочей жидкости в пределах 100-500 литров на гектар можно регулировать путем изменения давления в системе от 2 до 8 бар и рабочей скорости от 3 до 7 километров в час