Impact of physical exercises in rehabilitation of Multiple sclerosis

https://www.ester.ee/record=b530138

Error Analysis of Method for Calculation of Non-Contact Impact on Space Debris from Ion Thruster

International audienceKeywords: space debris removal, ion beam shepherd technology, spacecraft-space debris object system, contour of the central projection, simplified calculation of the impact, error analysis, simulation of the relative motion. ABSTRACT. A simplified approach to determine the impact on a space-debris object (a target) from the ion thruster of a spacecraft (a shepherd), which was proposed before in the context the ion beam shepherd technology for space debris removal, was considered. This simplified approach is based on the assumption of the validity of the self-similar model of the plasma distribution in the thruster plume. A method for the calculation of the force impact using the information about the contour of the central projection of the object on a plane, which is perpendicular to the ion beam axis, was proposed within the framework of this model. The errors of this method, including the errors caused by an inaccuracy of its realization, are analyzed. The results of the analysis justify the admissibility of the application of the specified approach within the self-similar model of the plasma distribution. The preliminary conclusion has been made that this simplified approach can be used to control the relative motion of the shepherd-target system as well. This conclusion is based on the results of the simulation of the system motion, when the " real " value of the thruster impact is calculated by the direct integration of the elementary impacts over the target surface and the value of the same impact used in the control algorithms is determined using the information about the contour of the target. A number of factors such as the orbital motion of the system, external perturbations, and the attitude motion of the shepherd were neglected in the simplified model which was used for the simulation. These factors and errors in the interaction model are necessary to consider during a more detailed analysis of this approach. The analysis of the calculation errors presented in this paper can be used during implementation of the ion beam shepherd technology for active space debris removal. Introduction. The technology for the removal of large debris from the low-Earth-orbit called ion beam shepherd is presented in the papers [1], [2]. This technology provides space debris de-orbiting due to the impact of the ion plume of the electric thruster (ET) of a spacecraft (a shepherd) located in close proximity to space debris object (a target). A certain distance between ion beam shepherd (IBS) and the target must be maintained to provide effectiveness of the impact of the ion beam. The ion beam impact can be determined by integration over the surface of a target when the mechanism of the ion interaction [3] with an elementary area of the surface and its relative position are known. This approach can be used for modeling of the system motion but not recommended to apply in a control loop due to its computational costs and the incomplete information about the position and shape of the target. A simplified approach to calculate the impact from the ion beam on the target, based on the information about the contour of its central projection on the image plane of the IBS camera was proposed in [4, 5]. The central projection of the target on the reference plane, which is perpendicular to the beam axis, is considered within the framework of this approach instead of its surface. This paper justifies the application of this approach to control the relative motion of the shepherd-target system by analyzing errors of the determination of the plasma beam impact on the target Calculation of the force impact by the direct integration over the target surface. The model of the interaction of the ion beam with a space debris object, as well as the model of the ion plume should be considered for the calculation of the impact from the ET force on the target

The task of multi-criteria optimization of metal frame structures

Optimal design of a frame structure with a specified geometric scheme consists in finding control parameters that provide the highest or lowest value of composite functions which present some quality criteria. Searching for optimal parameters is related to a number of design and calculation constraints. When it is necessary to vary a geometrical scheme, node coordinates are also considered as unknown varied parameters that affect the quality criteria. When designing frames with a specified scheme, the volume of material is typically the primary criterion for solving an optimization task and is written as a function of control parameters and state settings. In problem specification it is also important to reduce the deformation of the system. This is accomplished by introducing an additional criterion -maximum moments of inertia of the sections of the system. There is a two-phase design and calculation model existing in design practice now. In the first stage, the work is based on the experience or existing prototype. On their basis stiffness of the bars is assigned, and then a load vector is calculated. In the second stage, the sections are chosen according to known forces

Improving the Conditions for the Provision of Tax Benefits in the Framework of Consuming Relations on State Support of Capital Investments

This article discusses the application of newly introduced investment benefits to investment projects for the implementation of capital investments that began and (or) ended to the appropriate change in the legislation. As a significant direction in the development of the state tax policy in the field of stimulating capital investments, the need for a balanced approach is indicated in the resolution of this issue. So, the application of a less favorable previous law should not overcome subsequent norms that provide the best position for the taxpayer. At the same time, unlimited records of past investments for new benefits should also not be allowed

Generation of Long-Lived Isomeric States via Bremsstrahlung Irradiation

A method to generate long-lived isomeric states effectively for Mossbauer applications is reported. We demonstrate that this method is better and easier to provide highly sensitive Mossbauer effect of long-lived isomers (>1ms) such as 103Rh. Excitation of (gamma,gamma) process by synchrotron radiation is painful due mainly to their limited linewidth. Instead,(gamma,gamma') process of bremsstrahlung excitation is applied to create these long-lived isomers. Isomers of 45Sc, 107Ag, 109Ag, and 103Rh have been generated from this method. Among them, 103Rh is the only one that we have obtained the gravitational effect at room temperature.Comment: ICAME 05 conference repor

Scripts and Politics in the USSR

No country in the world has changed its language policy – including the choice of alphabet – as frequently as the Soviet Union did. There were three main periods of alphabet change: the 1920s; the second part of the 1930s; and the last years of the USSR. The revolution set new goals – it expressed the need to transfer official communication from Russian into the languages of ethnic minorities, to create middle and higher education in them and so on. However, many languages were unwritten; the existing scripts of some other languages (traditional Arabic or Mongolian) were considered unacceptable. It was necessary to create new alphabets. After some hesitation, the Latin script was chosen as predominant in the world. More than 80 alphabets were constructed in the 1920s and '30s. However from 1935 to 1938 it was decided that all Soviet languages using the Latin alphabet would adopt Cyrillic. This Cyrillisation was completed in 1941, before the beginning of the war. The official slogans remained the same, but the spread of Russian and the Cyrillic script became a main task of Soviet language policy. This situation did not change until the 1980s when national movements in the USSR spoke out against Russian and the use of the Cyrillic script. After the disintegration of the USSR in 1991 and the formation of new states, the problem of alphabet choice became urgent. Latinisation was accomplished in Azerbaijan, Uzbekistan, Turkmenistan and Moldavia; it is planned in Kazakhstan and Kyrghyzstan. Some proposals to Latinise Russian have no practical significance

Scripts and Politics in the USSR

No country in the world has changed its language policy – including the choice of alphabet – as frequently as the Soviet Union did. There were three main periods of alphabet change: the 1920s; the second part of the 1930s; and the last years of the USSR. The revolution set new goals – it expressed the need to transfer official communication from Russian into the languages of ethnic minorities, to create middle and higher education in them and so on. However, many languages were unwritten; the existing scripts of some other languages (traditional Arabic or Mongolian) were considered unacceptable. It was necessary to create new alphabets. After some hesitation, the Latin script was chosen as predominant in the world. More than 80 alphabets were constructed in the 1920s and '30s. However from 1935 to 1938 it was decided that all Soviet languages using the Latin alphabet would adopt Cyrillic. This Cyrillisation was completed in 1941, before the beginning of the war. The official slogans remained the same, but the spread of Russian and the Cyrillic script became a main task of Soviet language policy. This situation did not change until the 1980s when national movements in the USSR spoke out against Russian and the use of the Cyrillic script. After the disintegration of the USSR in 1991 and the formation of new states, the problem of alphabet choice became urgent. Latinisation was accomplished in Azerbaijan, Uzbekistan, Turkmenistan and Moldavia; it is planned in Kazakhstan and Kyrghyzstan. Some proposals to Latinise Russian have no practical significance

Numerical studies of steel pipe sheet pile

The sheet pile wall (SPW) is carried out from pipes of big diameter which plunge into soil very deeply. Depth of pipes is the settlement size depending on a set of parameters. Depth of pipes provides rigidity and reliability of a construction. SPW has a high rate of a consumption of steel on his production. Authors of the present article suggest to reduce a material capacity of SPW at the expense of reduction of depth of blockage of every second pipe. Decrease in depth of blockage of separate pipes is carried out at preservation of the maximum depth of blockage of other pipes. The design similar to a «comb» because of alternation of long and short pipes turns out. Such decision allows to reduce the total depth of blockage of pipes and as a result leads to decrease in a material capacity and cost of a construction in general. The problem of search of possible reduction of length of a part of pipes is the purpose of the real research. As solutions of the put problem we suggest to execute numerical experimenting in iterative statement with use of modern software. Results of numerical researches of SPW are presented in the present article. The presented results allow to draw a conclusion on efficiency of the solution on decrease in a material capacity of SPW proposed by authors. For obtaining the generalized decision and obtaining undoubtedly the best result of a design of SPW authors consider necessary to execute problem definition in the form of parametrical optimization

On the choice of the ballistic parameters of an on-orbit service spacecraft

The aim of this paper is to assess the ballistic potential of modern and prospective OOS spacecraft and to develop a methodology for planning rational OOS routes. Various ground- and space-based OOS systems are considered and analyzed. The expediency of their use is estimated depending on the service tasks to be performed. The most promising OOS schemes are identified. A technique for planning a rational sequence of orbit transfers between the orbits of the spacecraft to be serviced is proposed and illustrated by the example of a test calculation.Целью статьи является оценка баллистического потенциала современных и перспективных орбитальных сервисных аппаратов и разработка методики планирования рациональных маршрутов ОСО. Рассмотрены и проанализированы различные системы ОСО наземного и космического базирования. Проведена оценка целесообразности их использования в зависимости от планируемых для выполнения сервисных задач. Выявлены наиболее перспективные схемы ОСО. Предложена методика планирования рационального маршрута последовательного обхода орбит обслуживаемых КА и приведен тестовый пример расчета.Метою статті є оцінка балістичного потенціалу сучасних і перспективних орбітальних сервісних апаратів і розробка методики планування раціональних маршрутів ОСО. Розглянуто й проаналізовано різні системи ОСО наземного та космічного базування. Проведено оцінку доцільності їх використання в залежності від плануємих для виконання сервісних завдань. Виявлено найбільш перспективні схеми ОСО. Запропоновано методику планування раціонального маршруту послідовного обходу орбіт КА, що обслуговуються, й наведено тестовий приклад розрахунку