一种采用速度控制模式的动量轮控制系统

针对以无刷力矩电机驱动的动量轮提出了利用旋转变压器直接求差进行位置反馈闭路控制及以脉冲输入作为加速度给定量输入的控制系统。控制电路由FPGA芯片集成 ,结构简单、有效。初步实验结果表明 ,系统实现了动量轮在± 30 0 0r/min转速范围内速度控制精度优于 2× 10 - 5且加速度响应时间优于 2 0 0ms的预期要求     

火箭贮箱结构材料应用及发展现状

火箭贮箱是运载火箭的重要组成部件,但服役环境相对恶劣,在储存液体推进剂的同时还承担着复杂的结构载荷。结构材料是贮箱制造发展的根本,也是航天运载器变革的关键。本文主要介绍国内外运载火箭贮箱结构材料的应用及其发展现状,对铝合金、不锈钢、钛合金等金属材料以及复合材料贮箱进行了综述,系统性地总结了贮箱材料的变革历程和应用情况,并对未来贮箱材料的发展方向提出新的见解与展望。     

Study of physiological effects of weightlessness and artificial gravity in the flight of the biosatellite Cosmos-936.

In the 18.5-day flight of the Soviet biosatellite Cosmos-936 (3-22, August 1977) com-parative investigations of the physiological effects of prolonged weightlessness (20 rats) and artificial gravity of 1 g (10 rats) were carried out. Throughout the flight artificial gravity was generated by means of animal rotation in two centrifuges with a radius of 320mm. Postflight examination of animals and treatment of the flight data were performed by Soviet scientists in collaboration with the specialists from Bulgaria, Czechoslovakia, the German Democratic Republic, Hungary, Poland, Rumania, France and the U.S.A. During the flight the total motor activity of the weightless rats was higher and their body temperature was lower than those of the centrifuged animals. Postflight examination of the weightless rats showed a greater percentage of errors during maze an increase in water intake and a decrease in diuresis; a fall of the resistance of peripheral red cells; an increase in the conditionally pathogenic microflora in the mouth; a decrease of oxygen consumption, carbon dioxide production and energy expenditures; a drop in the static physical endurance; a decline in the capacity to keep balance on the rail; an increase in the latent period of the lifting reflex, etc. The centrifugal animals displayed lesser or no change of the above type. These findings together with the biochemical and morphological data give evidence that during and after flight adaptive processes in the centrifuged rats developed better.     

A method of technologic audit of technical re-equipment projects in aircraft production enterprises

A method of technologic audit for technical re-equipment of enterprises is considered. The method developed is intended to verify technological solutions of projects of technical re-equipment of enterprises according to indicators of productivity.     

Magnetic Field Fluctuations in the Solar Wind, Foreshock and Magnetosheath： Cluster Data Analysis

46 magnetosheath crossing events from the two years (2001.2-2003.1) of Cluster magnetic field measurements are identified and used to investigate the characters of the magnetic field fluctuations in the regions of undisturbed solar wind, foreshock, magnetosheath. The preliminary results indicate the properties of the plasma turbulence in the magnetosheath are strongly controlled by IMF orientation with respect to the bow shock normal. The amplitude of the magnetic field magnitude and direction variations behind quasi-parallel bow shock are larger than those behind quasi-perpendicular bow shock. Almost purely compressional waves are found in quasi-perpendicular magnetosheath.     

N2O单组元微推力器性能分析及试验

N₂O单组元微推进是当前微推进领域的一个热点问题.在N₂O催化分解热力计算的基础上开展了对N₂O单组元微推力器比冲性能影响因素的分析,分析结果表明微推力器比冲与N₂O分解效率及喷管扩张比有密切关系.所开展的亚牛级N₂O单元微推力器催化分解试验结果表明所设计N₂O单元推力器能在250℃初温条件下启动,初步验证了N₂O单元微推力器的可行性;也揭示了推力室结构及床载大小对亚牛级N₂O单元微推力器性能的影响,为进一步的结构及试验设计提供了参考.     

基于FPGA的星载步进电机控制电路设计

针对航天设备在轨运行时间长、不易更换的特点,提出了一种力矩宽且范围可调的步进电机控制电路设计。该电路原理样机以Xilinx公司的XC3S400pq-208型FPGA为核心控制芯片,以LMD18200为步进电机驱动芯片。在对电路总体设计进行介绍的基础上,重点阐述了航天过程中步进电机阻力矩增加的问题,以及通过脉冲频率和PWM控制技术调节输出力矩的方法。试验结果表明,力矩可调范围的最大值能够使力矩裕度达到4,匹配步进电机在轨运行过程中的力矩要求。     

环境减灾A、B星星座轨道维持技术与实践

为维持环境减灾A、B星星座的轨道构型,保证CCD相机48h对中国覆盖和对全球重访的特性,满足中国灾害与环境监测以及全球陆地观测的需求,制定了同时考虑地面轨迹和星座相位的轨道维持策略。在减灾和环保业务应用过程中,主要关注星座的重访和覆盖特性,严格的地面轨迹维持意义不大,因而形成了主要考虑星座相位的轨道维持方法。该方法能够减少轨道维持次数,降低操作风险,节省星上燃料,有利于延长卫星寿命。A、B星星座运行3年多,仅通过2次轨道调整就完成了星座轨道维持控制任务。     

新自由主义的社会福利思想

作为当代社会一个重要的理论范式，新自由主义是在与凯恩斯主义的论战中逐步发展起来的。在政治经济领域内，它拒绝国家的干预和控制；在社会福利领域内，它反对福利思想的传播和福利国家的构建，主张通过自由市场机制和个人的自我负责来取代长期由国家提供的社会福利，借以减轻国家的负担，激发个人的进取精神。在新自由主义思想的指引下，英国和美国分别实施了社会福利改革，短期内在减少社会福利开支的同时，也导致了社会福利水平的下降，从长期看，新自由主义的社会福利政策存在着缺陷。     

高负荷压气机静叶根部叶型气动性能实验研究

为研究高负荷压气机静叶根部流动状态,抽取该静叶根部叶型并模化成为平面叶栅进行吹风实验,冲角变化范围为-6°~+6°、进口马赫数变化范围为0.5~0.7。对叶栅出口截面气动参数进行了详细的测量,结果表明:非正冲角时叶展中部节距平均总压损失系数小于等于0.036,尾迹宽度和总压损失峰值随马赫数变化均不明显,正冲角时尾迹宽度和总压损失峰值急剧增加;端壁处的压力梯度随马赫数和冲角的增加而增加;0°冲角下随马赫数的增大,出口叶展中部截面二次流动能系数增加,二次流动得到加强,高能量损失区域增大并且尾迹略有变宽。