太阳电池空间标定技术初探

随着各种新型空间太阳电池的发展和应用,在地面使用太阳模拟器对AMO标准太阳电池进行标定的方法在理论和实践上都遇到了严重的困难,最能反映其实际使用状态的空间标定成为解决问题的理想方案。国外太阳电池空间标定技术已十分成熟,主要航天国家如美国、欧洲、日本、巴西等都进行了各自的空间标定实验。北京东方计量测试研究所进行了太阳电池空间标定原理样机的研制工作。样机由太阳电池板、数据采集与处理模块、太阳敏感器和温度传感器组成,可同时对32路国产砷化镓多结太阳电池进行短路电流的测量,电流测试的标准不确定度小于0.5%(最佳点)。此项研究将形成标准太阳电池空间标定的完整方案,促进我国新型空间太阳电池的研究和应用。     

Optimal solar sail trajectory approximation with finite Fourier series

The heliocentric transfer of a solar sail-based spacecraft is usually studied from an optimal perspective, by looking for the control law that minimizes the total flight time. The optimal control problem can be solved either with an indirect approach, whose solution is difficult to obtain due to its sensitivity to an initial guess of the costates, or with a direct method, which requires a good estimate of a feasible (guess) trajectory. This work presents a procedure to generate an approximate optimal trajectory through a finite Fourier series. The minimum time problem is solved using a nonlinear programming solver, in which the optimization parameters are the coefficients of the Fourier series and the positions of the spacecraft along the initial and target orbits. Suitable constraints are enforced on the direction and magnitude of the sail propulsive acceleration vector in order to obtain feasible solutions. A comparison with the numerical results from an indirect approach shows that the proposed method provides a good approximation of the optimal trajectory with a small computational effort.     

Solar power sail membrane prototype for OKEANOS mission

This paper reports on the manufacturing and evaluation of a solar power sail membrane prototype for the OKEANOS project. The in-house prototype was built by the Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency. Mechanical and electrical evaluation tests were conducted. The membrane, thin-film solar cells, reflectivity control devices were good condition after the manufacturing and handling. The improvements in the manufacturing process and design were found. The manufacturing process and design were fundamentally established. After the prototype, improvement plans for the manufacturing process and design were tried. We have a prospect of manufacturing the flight model sail and continue to the development.     

On the dynamics of the heliosphere on intermediate and long time-scales

A time-dependent, three-dimensional model of the dynamics of the heliosphere as a result of solar activity and a time-varying local interstellar medium is presented. The model is based on a recent version of the well known ZEUS code and employs parallel processing. It includes the solar and interstellar plasma components as well as neutral atoms, and contains the heliospheric magnetic field in a kinematic fashion. We study the dynamics of the heliosphere due to solar activity on periods of months to years up to the so-called Schwabe (11-year) cycle as well as due to time variations of the local interstellar medium, all of which have drawn increasing attention during recent years, as the significance of their direct or indirect effect on the Earth and its environment is under lively debate.     

Space weather and commercial airlines

Space weather phenomena can effect many areas of commercial airline operations including avionics, communications and GPS navigation systems. Of particular importance at present is the recently introduced EU legislation requiring the monitoring of aircrew radiation exposure, including any variations at aircraft altitudes due to solar activity. With the introduction of new ultra-long-haul “over-the-pole” routes, “more-electric” aircraft in the future, and the increasing use of satellites in the operation, the need for a better understanding of the space weather impacts on future airline operations becomes all the more compelling. This paper will present the various space weather effects, some provisional results of an ongoing 3-year study to monitor cosmic radiation in aircraft, and conclude by summarising some of the identified key operational issues, which must be addressed, with the help of the science community, if the airlines want to benefit from the availability of space weather services.     

Education and public outreach program for IHY – A global approach

Education and public outreach (EPO) is one of the four components of the International Heliophysical Year (IHY). It is fundamental in achieving one of IHY’s primary objectives which is to “demonstrate the beauty, relevance and significance of Space and Earth science to the world.”     

Interplanetary Physics Research in China： 2006-2008

This brief report summarized the latest advances of the interplanetary physics research in China during the period of 2006-2007,made independently by Chinese space physicists and through international collaboration.The report covers all aspects of the interplanetary physics,including theoretical studies,numerical simulation and data analysis.     

Gnevyshev gap, Forbush decreases, ICMEs and solar wind electric field: relationships

We have studied annual frequency distribution of the Forbush decreases for three solar cycles (20, 21, 22); most are associated with the fast ICMEs and SSCs. The frequency varies in step with the solar cycle but the distribution has a notable gap embedded in it, near the maximum of the cycle leading to two peaks in Forbush decreases per cycle. We show that the gap coincides with the epoch of solar polar field reversal. There is an indication of an odd/even cycle effect in the frequency distribution of Forbush decreases and the associated SSCs. We find that two peaks in Forbush decrease and SSC distributions are separated by the Gnevyshev gap; second peaks occur well before the onset of the high-speed streams in the descending phase of a cycle which do not cause Forbush decreases but do contribute to a peak in the geomagnetic activity index Ap. We compare Forbush decrease and SSC distributions with the corresponding distribution of the solar wind electric field and find that a large amplitude of the electric field of itself does not cause a Forbush decrease to occur unless it is also associated with a fast ICME/SSC.     

Relativistic solar protons in the ground level event of 23 February 1956: New study

In this study we applied again to the outstanding solar particle event of 23 February 1956, the largest one in the entire history of observations of solar cosmic rays. Due to significant improvement of the analysis/modeling techniques and new understanding of physical processes in the solar atmosphere and interplanetary space, a possibility arises to interpret the old data in the light of modern concept of multiple particle acceleration at/near the Sun. In our new analysis the data of available then neutron monitors and muon telescopes are used. The technique of the analysis includes: (a) calculation of asymptotic cones of ground-based detectors; (b) modeling of cosmic ray detector responses at variable parameters of the flux of solar relativistic protons; (c) determination of primary solar proton parameters outside magnetosphere by comparison of computed responses with observations. Certain evidence was obtained that the flux of relativistic solar protons consisted of two distinct components: prompt and delayed ones. The prompt component with exponential energy spectrum caused a giant impulse-like increase at a number of European cosmic ray stations. The delayed component had a power-law spectrum and was a cause of gradual increase at cosmic ray stations in the North American region. A numerical simulation of the proton acceleration in the vicinity of the magnetic reconnection region brings to the proton spectrum with exponential dependence on energy. This agrees with observational data for the prompt component. It is also shown that the huge increase in ∼5000% on neutron monitors was due to the prompt component only with the exponential proton spectrum. The power-law spectrum of comparable intensity gave considerably smaller effect.     

大功率电动机软起动技术及其应用

本文介绍了几种适用于大功率电动机起动的软起动装置的工作原理,对其技术、经济性进行了比较,探讨了软起动装置在大型设施中应用的可行性.