Mars Express/ASPERA-3/NPI and IMAGE/LENA observations of energetic neutral atoms in Earth and Mars orbit

The low energy neutral atom imagers on Mars Express and IMAGE have revealed that the neutral atom populations in interplanetary space come from a variety of sources and challenge our current understanding of heliospheric physics. For example, both in cruise phase and at Mars, the neutral particle instrument NPD on Mars Express observed “unexplained neutral beams” unrelated to Mars which appear to be either of heliospheric or solar wind origin. Likewise, the NPI instrument on Mars Express has revealed streams of neutral atoms with different properties than those observed by NPD. Independently, IMAGE/LENA has reported neutral atom observations that may be interpreted as a “secondary stream” having different characteristics and flowing from a higher ecliptic longitude than the nominal upstream direction. Both sets of observations do not appear to fit in easily with the neutral atom environment from 1.0 to 1.57 AU as it is currently understood. In this paper, we examine some highly suggestive similarities in the IMAGE/LENA and Mars Express/ASPERA-3/NPI data to try to determine potential origins for the observed signal.     

能源合理利用与人类住区的可持续发展

本文针对近期石油涨价以及全社会都在提倡节约的大气候,从现有能源的利用和新能源的开发两大方面谈能源合理利用与人类住区的可持续发展过程中应注意的问题,并提出相应的看法和建议。     

复合材料圆筒件静态吸能特性研究

本文通过一系列圆筒件的静态吸能试验研究了复合材料圆筒件静态吸能的特性。表明材料的吸能性能不仅同材料性能关系密切,而且也受材料纤维方式和工艺方法的影响。     

砷化镓异质外延薄膜的近红外光致发光研究

本文通过在硅衬底上用ＭＯＣＶＤ方法生长的砷化镓外延薄膜的变激发强度的近红外光致发光，研究了在液氮温度下峰值为１．１３与１．０４ｅＶ两个发光带的发光特性。     

The Science Case for STEP

The Satellite Test of the Equivalence Principle (STEP) will advance experimental limits on violations of Einstein’s Equivalence Principle (EP) from their present sensitivity of 2 parts in 10¹³${10}^{13}$ to 1 part in 10¹⁸${10}^{18}$ through multiple comparison of the motions of four pairs of test masses of different compositions in an earth-orbiting drag-free satellite. Dimensional arguments suggest that violations, if they exist, should be found in this range, and they are also suggested by leading attempts at unified theories of fundamental interactions (e.g., string theory) and cosmological theories involving dynamical dark energy. Discovery of a violation would constitute the discovery of a new force of nature and provide a critical signpost toward unification. A null result would be just as profound, because it would close off any possibility of a natural-strength coupling between standard-model fields and the new light degrees of freedom that such theories generically predict (e.g., dilatons, moduli, quintessence). STEP should thus be seen as the intermediate-scale component of an integrated strategy for fundamental physics experiments that already includes particle accelerators (at the smallest scales) and supernova probes (at the largest). The former may find indirect evidence for new fields via their missing-energy signatures, and the latter may produce direct evidence through changes in cosmological equation of state—but only a gravitational experiment like STEP can go further and reveal how or whether such a field couples to the rest of the standard model. It is at once complementary to the other two kinds of tests, and a uniquely powerful probe of fundamental physics in its own right.     

冲击载荷下受轴向约束的点阵材料夹芯简支梁

对受到均布冲击载荷的轴向不可移点阵材料夹芯简支梁进行了刚塑性动力响应理论分析和弹塑性有限元分析.首先给出了夹芯梁在外包和内接屈服条件下中点最大挠度的理论预测值,并与有限元结果进行了比较,有限元计算结果介于两种屈服条件给出的理论预测结果之间,有限元计算的支座处最大转角与外包屈服条件给出的理论预测结果接近.然后考察了点阵材料夹芯梁的抗冲击性能和吸能效果.结果表明:夹芯梁的最大挠度和塑性耗散能对杆元与面板夹角及相对密度十分敏感,设计合理的夹芯梁具有很好的吸能效果和抗冲击性能.     

乙醇燃料微型燃气轮机设计

推广生物质燃料在以微型燃气轮机为核心的分布式能源技术中的应用,设计了一种可燃用乙醇燃料的微型燃气轮机.通过整机热力循环参数分析,确定了乙醇燃料微型燃气轮机的设计点参数,并结合乙醇燃料特点,对燃烧室的几何尺寸进行了设计,获得了适用于乙醇燃烧的微型燃气轮机燃烧室技术.初步的整机实验结果表明,该乙醇燃料微型燃气轮机成功实现自行运转,证明了设计方案可行.     

点火能量对脉冲爆震发动机性能的影响

针对以汽油-空气为推进剂的吸气式脉冲爆震发动机,研究了点火能量及工作频率对发动机点火-起爆时间和发动机推进性能的影响。结果显示,随着点火能量的提高,点火-起爆时间逐渐减小,脉冲爆震发动机平均推力逐渐增加。随着发动机工作频率的提高,点火-起爆时间也逐渐减小,发动机稳定工作的最佳油气当量比减小,发动机平均推力接近线性增加;但是点火能量对发动机点火-起爆时间的影响随着工作频率的提高而有所降低。     

串联机器人运动控制方法的研究

通过对某型串联机器人进行运动学分析,从而确定了此串联机器人的工作空间,应用绘图软件Aulo CAD,利用其方便的数据文件生成功能,探索出了一种串连机器人模型轨迹数据的生成方式.采用面向硬件的控制方式,主要通过向PCL-839板卡写命令的方式实现控制功能.软件应用Visual C++语言写成.利用C++语言中的地址操作函数向PCL-839步进电机控制卡接口中写入指令,从而完成控制机器人运动的功能.     

SGKW轨道在线生成技术研究

天基对地打击动能武器(SGKW)用于从太空对地面高价值战略目标进行快速、准确的打击.针对作战实时性要求,探讨了SGKW的轨道在线生成技术.首先,利用庞特里亚金极大值原理将时间最短打击轨道的最优控制问题转化为两点边值问题.由于约束条件中存在优化参数,一种基于"遗传算法+序列二次规划"的组合优化算法被用于求解伴随变量初值和再入点参数.为了提高轨道生成的速度,在大量离线优化数据的基础上建立了BP神经网络预测模型,其预测值通过序列二次规划算法稍加修正,即可满足相应任务的落点精度要求.仿真结果验证了上述方案的有效性.