导电盒上单极天线的方向图

系统地研究安装于接地平面上的立方体导电盒顶面上的单极天线的方向图的确定方法.对单极天线位置和导电盒电尺寸的影响与在平直接地平面上测量得到的类似方向图作了比较.还将试验结果同用矩插入码方法得到的数字预测值进行了比较.     

来科明公司将试验新的发动机核心机

达信集团来科明公司将于今年12月开始试验新的系列发动机的通用核心机;但是,如果来科明公司找不到合作伙伴,它的这项研制新的发动机系列与AE2100、AE3007竞争的计划在发动机取证前可能被迫终止。 来科明公司新的系列发动机编号为500系列,其核心机是由T55、ALF502及LF507发动机衍生而来,效率与性能均有所提高。来科明公司的经营计划要求:针对ATR84运输机的需要,在1996年下半年前研制出功率为5510千瓦(7500轴马力)的LP512涡桨发动机,估计ATR公司     

利用激光进行陀螺动平衡

利用控制的高能激光脉冲去除不平衡量的优点是:在极高转速的陀螺上,原则上能做到质量平衡。与此相反——如前所述——用普通的机械去重法(例如钻孔法)只能在静止的转子上进行不平衡量的去除。然而,从原则上来看,在陀螺工作时进行动平衡既节省时间又较精确。激光动平衡法还有的优     

Ground-based simulations of cosmic ray heavy ion interactions in spacecraft and planetary habitat shielding materials

This paper surveys some recent accelerator-based measurements of the nuclear fragmentation of high energy nuclei in shielding and tissue-equivalent materials. These data are needed to make accurate predictions of the radiation field produced at depth in spacecraft and planetary habitat shielding materials and in the human body by heavy charged particles in the galactic cosmic radiation. Projectile-target combinations include 1 GeV/nucleon 56Fe incident on aluminum and graphite and 600 MeV/nucleon 56Fe and 290 MeV/nucleon 12C on polyethylene. We present examples of the dependence of fragmentation on material type and thickness, of a comparison between data and a fragmentation model, and of multiple fragments produced along the beam axis.     

Dynamic change of ERPs related to selective attention to signals from left and right visual field during head-down tilt

To study further the effect of head-down tilt (HDT) on slow positive potential in the event-related potentials (ERPs), the temporal and spatial features of visual ERPs changes during 2 hour HDT (-10 degrees) were compared with that during HUT (+20 degrees) in 15 normal subjects. The stimuli were consisted of two color LED flashes appeared randomly in left or right visual field (LVF or RVF) with same probability. The subjects were asked to make switch response to target signals (T) differentially: switching to left for T in LVF and to right for T in RVF, ignoring non-target signals(N). Five sets of tests were made during HUT and HDT. ERPs were obtained from 9 locations on scalp. The mean value of the ERPs in the period from 0.32-0.55 s was taken as the amplitude of slow positive potential(P400). The main results were as follows. 1) The mean amplitude of P400 decreased during HDT which was more significant at the 2nd, 3rd and 5th set of tests; 2) spatially, the reduction of mean P400 amplitude during HDT was more significant for signals from RVF and was more significant at posterior and central brain regions than that on frontal locations. As that the positive potential probably reflects the active inhibition activity in the brain during attention process, these data provide further evidence showing that the higher brain function was affected by the simulated weightlessness and that this effect was not only transient but also with interesting spatial characteristics.     

二级轻气炮弹丸速度,质量和位置测量

二级轻气炮发射的氘冰弹丸的速度、质量和显示弹丸完整性的方法和所使用的仪器以及新开发的以波长编码、用光张赤传感器的弹丸进行位置的测量方法。     

高空长续航力传感器平台的大面积气动控制

文章对大面积气动控制方案在高空长续航力（HALE）传感器平台上的应用进行了研究。主要集中在联合翼飞行器上。这种飞行器具有主流高空长续航力飞行器所具有的两个典型的性能缺陷。第一个是由于这种布局产生的很大的转动阻尼导致在着陆时的最小的转动速率。它显示多点分布的控制面有助于满足转动速率要求。第二个是起飞总重对于最大升阻比的敏感性。设想的任务需求推动燃料比例达到一个很高的水平，升阻比小幅变化导致燃油需求减少进而大幅减少飞行器重量。这表明用于满足转动需求的技术也可以用于主动控制巡航中的扭转和弯度，并对飞行器的重量和续航力有适度的影响。     

C／A码差分GPS着陆系统用于I类着陆的试飞评估

所完成的飞行试验是为了评估Ｃ／Ａ码差分ＧＰＳ在Ｉ类条件下，提供精密进近操作的能力。机载ＤＧＰＳ接收设备，具有预置ＤＧＰＳ下滑着陆航道，计算航线偏差，并将偏差信息转换成驱动机载显示仪表信号的能力，地面配有相同的ＤＧＰＳ接收机和用于传送ＤＧＰＳ差分信号和ＶＨＦ发信机，在地面，以无线电经纬仪或激光跟踪器为基准，分析８２个手动操作的进近飞行数据，其结果表明，用窄相关ＧＰＳ接收机时，系统的垂直精度满足Ｉ类要     

Plant molecular biology in the space station era: utilization of KSC fixation tubes with RNAlater

Spaceflight experiments involving biological specimens face unique challenges with regard to the on orbit harvest and preservation of material for later ground-based analyses. Preserving plant material for gene expression analyses requires that the tissue be prepared and stored in a manner that maintains the integrity of RNA. The liquid preservative RNAlater (Ambion) provides an effective alternative to conventional freezing strategies, which are limited or unavailable in current spaceflight experiment scenarios. The spaceflight use of RNAlater is enabled by the Kennedy space center fixation tube (KFT), hardware designed to provide the necessary containment of fixatives during the harvest and stowage of biological samples in space. Pairing RNAlater with the KFT system provides a safe and effective strategy for preserving plant material for subsequent molecular analyses, a strategy that has proven effective in several spaceflight experiments. Possible spaceflight scenarios for the use of RNAlater and KFTs are explored and discussed.     

全球定位系统用作洲际导弹制导系统鉴定工具的测量性能

八十年代初期,在两次民兵Ⅲ型导弹发射中(编号为PVM-18,19),试飞了一种四信道全球定位系统(GPS)接收机——弹载接收设备(MBRS)。这两次发射试验是称为“飞-2”系列飞行中的一部分。每次带两个NS20惯性测量装置。这两次试验的主要目的是在洲际导弹实际飞行环境中验证、测定全球定位系统的性能。本文概括了这两次飞行中GPS性能的分析结果。由此验证了如何利用这种质量的数据来高精度地鉴定制导误差,并用该数据来识别出飞行过程中各种制导误差。这两次试飞所得到的GPS数据证实了短期精度达到了预期能力。典型的随机误差为2英尺~*和0.01英尺/秒(一秒平均)。有了这一精度就可利用GPS作为外部测量仪器,对自由段中摆式积分陀螺加速度表(PIGA)的磁敏感效应进行直接观测。实现这种观测还是第一次。由于缺乏合适的标准,尚不容易进行绝对精度鉴定。显然,GPS的精度比同时参与导弹跟踪的雷达(多台)的好,拟合后残差非常一致,说明总精度很高。因此可得出结论,GPS的总精度达到了预期性能指标。 (本文常用缩略语AIRS——高级惯性基准球,BREW——民兵导弹上装的第二惯性测量装置,CSDL——Charles Stark Draper实验室,ECI——地心惯性座标系,GPS——全球定位系统,MBRS——导弹装载的GPS接收机,MISTRAM——米斯特拉姆,高精度无线电外测系统,PIGA——摆式积分陀螺加速度表,PVB——民兵导弹试验编号,TI——德克萨斯仪器公司)