EUV coronal pattern of complexes of solar activity

Studying of the coronal plasma associated with long-lived complexes of the solar activity is important for understanding a relationship between the magnetic activity and the solar corona changing during the solar cycle.

In the present paper, two long-lived complexes of the solar activity at the beginning of the current solar cycle 23 are investigated by using the Extreme-Ultraviolet data (EUV) from SOHO/EIT. For this purpose the EIT limb synoptic maps during the CR1916–CR1919 (11 November 1996–1 March 1997) are obtained.

The coronal temperature structures derived from the three lines 171A (Fe IX,X), 195A (Fe XII)and 284A (Fe XV) are investigated by applying an algorithm developed by Zhang et al. [Zhang, J., White, S.M., Kundu, M.R. ApJ 527, 977, 1999]. Standard EIT software are used for the temperature estimation from the ratio of two lines of Fe IX,X and Fe XII.

The method of the rotational tomography with a correction for an inclination of the Earth’s orbit (B-angle) to the helioequator is applied to obtain the three-dimensional (3-D) coronal structure of the complex of the solar activity. The results reveal difference in temperature structures related to multi-poles magnetic structures of the complex of solar activity and to the typical, the bipolar activity complex.     

对AVR403型电压调节器的分析

当同步发电机输出电流大小与功率因数改变时,其电枢反应与内阻抗压降将改变,则发电机输出电压也将改变。为使发电机输出电压保持额定值,通常都有自动电压调节器与发电机配套工作。本文较详细地分析了MD-80飞机使用的AVR403型电压调节器各部分电路的工作原理,以及整机调压的工作过程,并阐述了该调压器的特点。     

紫外-短波红外航天遥感探测器光电性能测试装置的研制和标定

为解决紫外-短波红外探测器光电性能测试和评价问题,研制了一套探测器的光谱响应、时间响应和偏压响应测试装置,为紫外-短波红外探测器的光谱响应和光电特性参量测试提供测试装置和评价依据,以便评价其综合性能指标是否满足设计和使用要求。介绍了测试装置的研制和标定过程,该测试系统由宽光谱复合光源、样品室、单色仪、锁相放大器、标准探测器等构成,实现了200～2 500 nm光谱范围内光电探测器绝对/相对光谱响应度、量子效率、归一化探测率、频响特性、偏压响应度和时间响应参量的测试功能。最后分析了照明光斑波长校准和光谱辐射照度标定的重要性,并给出标定方法和结果。     

固体姿轨控发动机燃气电磁阀快速驱动电路研究

提出了一种高压RC延时控制的高低压驱动电路,用于姿轨控发动机燃气阀控制。在闭合的启动阶段对线圈施加高电压提供大电流,加速电磁阀闭合;闭合的保持阶段施加低电压维持较小电流,保证线圈安全,降低功耗;开启阶段加速线圈电流泄放,提高开启速度,满足了发动机快速关断和开启的要求;信号电路和功率电路相互隔离;RC电路作为高电压延时器件,只需1路控制信号,电路得以简化。     

进气畸变下压气机过失速三维非定常模型探索

针对原压气机稳定性三维分析模型CSAC(compressor stability analysis code)加以改进,添加了轴对称左支特性。采用改进的CSAC+模型分析了NASA Rotor37在周向总压进气畸变下的稳态性能和失速起始特性,并与软件NUMECA模拟结果进行了对比,两者模拟的特性趋势一致,畸变进气下CSAC+近失速点压比与NUMECA的误差为1.05%。针对近失速点流场分析发现:随着流量的减小,在畸变区边缘的转子叶尖首先出现低速甚至逆流区,可认为该区域为失速起始位置。利用CSAC+模拟了该压气机过失速状态下的主要流动特征,分析得出进气畸变下该失速先兆为模态波,完全发展后为部分叶高失速,失速团占据约40%叶高,其传播频率约为转子转动频率的60%,并在传播过程中显示出周期性的剥离和融合过程。      

Fault-tolerance wide voltage conversion gain DC/DC converter for more electric aircraft

In this paper, a fault-tolerance wide voltage conversion gain DC/DC converter for More Electric Aircraft (MEA) is proposed. The proposed converter consists of a basic Cuk converter module and n expandable units. By adjusting the operation state of the expandable units, the voltage conversion gain of the proposed converter could be regulated, which makes it available for wide voltage conversion applications. Especially, since mutual redundancy can be realized between the basic Cuk converter module and the expandable units, the converter can continuously work when an unpredictable fault occurs to the fault-tolerant parts of the proposed converter, which reflects the fault tolerance of the converter and significantly improves the reliability of the system. Moreover, the advantages of small input current ripple, automatic current sharing and low voltage stress are also integrated in this converter. The working principle and features of the proposed converter are mainly introduced, and an experimental prototype with 800 W output power has been manufactured to verify the practicability and availability of the proposed converter.     

Evolution of an electron beam pulse influenced by coulomb collision effects in the solar corona

Electrons accelerated in the corona during solar activity give rise to radio emission events that can be observed over a wide range of frequencies. Among different finer-scale structures in the dynamic spectra observed in the radio range, fast transients with extents of some milliseconds known as solar radio spikes are observed accompaning the background continuum emission. Fundamental to the generation of radio spikes is a propagating electron beam and following its evolution allows us to understand the physical processes occurring in the solar corona. With the use of a numerical Fokker–Planck code we follow a previous numerical study to simulate the propagation of an electron beam pulse injected in a small region at the top of a magnetic field and outwards the solar corona under typical flare conditions. It was found that in large ambient densities of ${10}^{10}$ cm⁻³ at the injection point, Coulomb collision effects have an important effect on the propagation of the electrons, causing that the injected electrons thermalize faster in a time of $0.1$ and $0.4$ s for an electron distribution with a low-energy cut off of 16 and 7 keV respectively and a spectral index of 3. For a tenous ambient medium of density ${10}^9$ cm⁻³ thermalization occurs only for an electron distribution with smaller low-energy cut off (7 keV) with a duration of $\approx$1.5 s, while for a larger low-energy cut off (16 keV) the loss of accelerated electrons is very slow, regardles of the spectral index ($3,7$). The electron loss time by Coulomb collisions, which depends on the low boundary ambient density, might be an important parameter that influences the generation of radio spikes due to the formation of instabilities in the corona.     

交流发电机电压调节器负载电流限制电路的研究

发电机负载电流限制对保护飞机电源系统安全工作有重要意义，控制发电机励磁系统可以较灵活地实现这一功能。本文在发电机电压调节器励磁控制的基础上，提出增加一套负载电流限制电路的方案，并为某型飞机电压调节器设计出负载电流限制电路。理论分析和实验表明：该电路克服了已有电路影响调压精度的缺点，能可靠地将发电机输出短路电流限制在3倍额定值，获得理想的飞机电源系统输出外特性。     

尖峰电压信号发生器的研制

尖峰电压信号发生器的核心是产生尖峰电压信号,通过CPU控制串联接入被试设备的供电电源的回路中,能够输出尖峰电压信号、电压浪涌信号的试验设备。本文将项目的阶段管理应用于尖峰电压信号发生器的研发中,以期更好的了解这些阶段,顺利实现既定目标。     

SOHO: The Solar and Heliospheric Observatory

The Solar and Heliospheric Observatory (SOHO), together with the Cluster mission, constitutes ESA's Solar Terrestrial Science Programme (STSP), the first Cornerstone of the Agency's long-term programme Space Science — Horizon 2000. STSP, which is being developed in a strong collaborative effort with NASA, will allow comprehensive studies to be made of the both the Sun's interior and its outer atmosphere, the acceleration and propagation of the solar wind and its interaction with the Earth. This paper gives a brief overview of one part of STSP, the SOHO mission.