一次火箭参数对RBCC引射模态性能的影响

应用经过校验的三维湍流有限体积数值算法，对引射模态下RBCC模型不同一次引射火箭结构和工作参数条件下的多种工作状态进行了模拟。结果发现：提高一次火箭燃烧室工作压强，二次流量增加，系统推力增加，混合效果增强；一次火箭喷管形状直接影响引射掺混效果，但在保证足够一次流量的前提下，方形管道中可以使用锥形一次喷管，不会带来性能上的较大差异；一次火箭喷管数目增加，掺混质量提高；一次喷管扩张半角的改变不会影响二次引入流量，但会影响掺混效果和一次火箭自身推力；一次喷管面积膨胀比的变化，不会影响二次引入流量．但会改变混合效果。     

对RLC串联电路中通频带与RLC参数关系的讨论——从一道习题引起的问题

讨论了RLC串联电路中通频带与RLC参数的关系,说明在设计一个RLC串联谐振电路时,在给定谐振频率,电感量和频带宽度时,上下边界频率不能只满足通频带宽度而任意假定,还应满足通频带与RLC这些参数之间关系的表达式.     

The OSIRIS-REx Visible and InfraRed Spectrometer (OVIRS): Spectral Maps of the Asteroid Bennu

The OSIRIS-REx Visible and Infrared Spectrometer (OVIRS) is a point spectrometer covering the spectral range of 0.4 to 4.3 microns (25,000–2300 cm^?1). Its primary purpose is to map the surface composition of the asteroid Bennu, the target asteroid of the OSIRIS-REx asteroid sample return mission. The information it returns will help guide the selection of the sample site. It will also provide global context for the sample and high spatial resolution spectra that can be related to spatially unresolved terrestrial observations of asteroids. It is a compact, low-mass (17.8 kg), power efficient (8.8 W average), and robust instrument with the sensitivity needed to detect a 5% spectral absorption feature on a very dark surface (3% reflectance) in the inner solar system (0.89–1.35 AU). It, in combination with the other instruments on the OSIRIS-REx Mission, will provide an unprecedented view of an asteroid’s surface.     

Results and perspectives in the field of space materials science (SMS)

This paper is a review dealing with recent publications on theoretical and experimental investigations on space materials science under lower gravity. The importance of the results obtained by the present time and the wide perspectives for future investigations in this field are outlined.     

美军实施基于性能的保障(PBL)过程中的问题和改进对策

<正>基于性能的保障(PBL)已成为美国国防部首选的产品保障策略。本文总结了美军实施PBL过程中出现的问题和实施改进的经验做法。基于性能的保障(PBL)是指将产品保障作为一个综合的、经济上可承受的性能包来购买,目的是适应新的作战环境和作战样式对装备保障的要求,缩减后勤保障规模,降低使用和保障费用,提高经济可承受性以及装备的战备完好性。美军自20世纪90年代后期开始实     

The Mercury Gamma-Ray and Neutron Spectrometer (MGNS) Onboard the Mercury Planetary Orbiter of the BepiColombo Mission: Design Updates and First Measurements in Space

Space Science Reviews - Volatiles and refractories represent the two end-members in the volatility range of species in any surface-bounded exosphere. Volatiles include elements that do not interact...     

交互绘图软件（MTSCAD2.0）开发中的深层次问题研究（2）

本文进一步介绍图形编辑和几何交切方面的程序设计的经验，如图形的映射、平移和旋转，交互绘图时常用到的九种几何交切的有关内容。用实例来说明程序设计原理和方法。     

Navier—Stokes（NS）方程组差分计算中的物理和网格尺度效应及NS方程组的简化

对于高Re数流动计算，在通常二阶精度NS差分格式和网格数条件下，存在某些粘性项落入修正微分方程截断误差项的问题。这类NS方程组计算实际是计算某种简化NS方程组，而且重复计算误差物理粘性项既浪费机时和内存，误差积累又会对数值解产生不可预测的影响，避免外述缺陷的办法一个提高NS差分格式的精度，另一个是丢掉可能落入截断误差项的物理粘性项，把NS方程组简化为广义NS方程组，广义NS计算避免了误差物理粘性项误差积累对数值解的不可知影响，又可节省内存和机时，对高Re数流体工程计算很有好处。利用广义NS方程组计算超声速绕前向和后向台阶流动的结果表明：广义NS方程组与NS方程组的数值结果很好相符符。     

The IMPACT Solar Wind Electron Analyzer (SWEA): Reconstruction of the SWEA Transmission Function by Numerical Simulation and Data Analysis

The IMPACT SWEA instruments on board the twin STEREO spacecraft detect the solar wind electrons with energies between 1 and 2000 eV. The instruments provide 3-dimensional velocity distributions, pitch angle distributions and solar wind properties at two vantage points in the ecliptic at 1 AU. A few days after launch suppression of the low energy solar wind electrons was detected, which makes data analysis challenging and causes a significant loss of information below 50 eV. This paper describes the methods used to both understand the nature of the problem and to recover the most information about the low energy solar wind electrons from the measured datasets. These include numerical simulations, in-flight calibration results, and data reconstruction methods that allow the calculation of solar wind parameter proxies with minor limitations.     

Interaction between whistler-mode waves and electrons in the vicinity of interplanetary shocks as seen by Ulysses: A preleminary study

We present a study of wave particle interaction in the vicinity of interplanetary shocks in the ecliptic plane, as observed by the Ulysses spacecraft. We focus here on some events, for which electromagnetic waves are observed, mainly down-stream of the shock. The whistler mode waves are studied by means of the Unified RAdio and Plasma wave experiment (URAP) and the electron distribution functions are obtained from the Ulysses' plasma experiment (SWOOPS). The results are discussed in the light of electron-cyclotron instabilities.     

一种全长cDNA抑制缩减杂交方法及其水稻诱导表达基因分离的应用

以缩减杂交的原理和SMART cDNA合成方法为基础,开发了一种全长cDNA缩减杂交方法.该方法从微量的2个RNA样品合成全长cDNA,经PCR扩增和在两端连接不同的接头,通过2次缩减杂交获得含有高度浓缩的差异表达的全长或较大的基因片段,克隆后筛选出差异表达的基因.以噻菌灵(Probenazole,PBZ)为诱导剂处理水稻,获得了2个上调表达和1个下调表达基因的较长的cDNA片段.     

三轴台中框轴系静态设计与装调(上)

论述了首次采用双列圆柱滚子轴承于三轴台中框水平轴系上,使三轴精密角运动台达到了三个轴摆角１″、两个轴垂直度１″的要求。     

Theoretical and experimental technique of determining the mechanical characteristics of folded structure filler in the form of Z-crimp (shear of a filler in cross-sectional planes)

The analytical formulas to determine the averaged elastic and strength characteristics of the folded structure core in the form of Z-crimp in shear in the cross-sectional planes are obtained based on the assumption on momentless work of its elements (walls) at loading and their elimination from the work after buckling under bilateral tension-compression with shear. The dimensionless coefficients of the structural formulas obtained that appear in solving the problems formulated, are determined based on the data of the specially performed experiments of filler test-specimens on pure shear in two planes.     

BMCMC法分析2009年墨西哥H1N1流感病毒与中国流感病毒的进化关系

从GenBank上下载所有1978-2009年在中国分离的H1N1亚型流感病毒的HA和NA基因及所有同期在中国分离的A型流感病毒(宿主包括人、猪和禽)的PB1、PB2、PA、NS、NP和M基因的序列,将这些基因序列与2009年在中国发生的墨西哥H1N1流感病毒的对应基因序列进行BMCMC法分析,绘制BMCMC进化树,结果揭示中国发生的墨西哥H1N1流感病毒的HA和NA基因相对独立于中国季节性H1N1流感病毒;M基因相对独立于中国国内的季节性流感病毒和禽源流感病毒;PB1基因包含在季节性流感病毒的分群内;PB2基因和NS基因与国内重排的流感病毒相关,但相对独立于国内的季节性流感病毒和禽源流感病毒;PA基因包含在国内禽流感病毒的分群内;NP基因则与国内传统的猪流感病毒相关,但相对独立于国内的季节性流感病毒和禽源流感病毒.