Relative efficacy of the proposed Space Shuttle antimotion sickness medications

Space motion sickness has been estimated as affecting between 1/3 and 1/2 of all space flight participants. NASA has at the moment proposed a combination of promethazine and ephedrine (P/E) and one of scopolamine and dextroamphetamine (S/D), both given orally, as well as a transdermally applied scopolamine (TAS), as preventive and ameliorative measures. The reported double-blind study, tests the early phase actions and efficacy of the transdermal scopolamine (Transderm (TM)-V of ALZA Corporation) and compares these in detail to the oral medications. Motion sickness resistance was tested by standardized head movements while accelerating at 0.2 degree/sec2 to a maximum rotation of 240 degrees/sec, with an intermediate plateau of 10 min at 180 degrees/sec. To permit weighting motion sickness protection against other system influences, cardiovascular, psychological (subjective and objective), and visual parameter changes were documented for the three therapeutic modes. The relative impact of the various modalities on operational and experimental components of space missions is discussed. A comparison to intramuscularly administered promethazine (a backup therapeutic mode suggested for Space Shuttle use) is also included.     

多孔药柱燃气发生器的燃速变化和重现性

研完了多孔药柱燃气发生器的燃速变化特性。对几种装药量为0.5～150kg、有19～235个平行圆孔的药柱的设计进行了评价。主要讨论了多孔药柱与通常的中孔内部燃烧药柱燃速变化曲线的形状和大小的差别,不同的多孔药柱之间的差别,这些效应与弹道预测的关系,多孔药柱的压力一时间曲线重现性分析。分析采用了燃速和燃面的点火前及点火后的弹道性能评估,也考虑了侵蚀燃烧、侵蚀和沉积引起的喉面变化及特性速度变化的影响。从多孔药柱燃气发生器的点火后分析,推导出多孔药柱一般燃速变化曲线,使性能预测精度提高达3%。多孔药柱燃气发生器的性能重现性很好。高燃速发生器最大压力偏差小于3%,低燃速发生器最大压力偏差小于5%。     

采用三种学习与表示策略的合成孔径雷达自动目标识别

阐述了一种新的合成孔径雷达自动目标识别结构，这种结构是以能高精度地估计目标姿态角为前提条件的。本文所述分类器设计的优点是：由于有姿态信息，可以采用较少的特征对目标实现高准确度的分类，从而降低了输入空间的复杂性。此外，对分类器的训练可以根据不同的情况区别对待，这也改进了分类器的性能，降低了复杂性。文中比较了三种构建模式空间与判别函数的学习与表示策略：Vapnik的支撑矢量机（SVM），针对神经网络新提出的一种二次互信息（QMI）代价函数， 以及最近利用多分辨率概念扩展的主分量分析方法（PCA－M）。利用MSTAR（运动与静止目标捕获与识别）数据库得到的实验结果表明，我们的分类器的性能优于标准的模板匹配型分类器。我们也评估了分类器对易混淆目标的检测、分类质量、表明对易混淆目标的抑制能力有显著的改善。     

Vibrografic signs of autonomous muscle tone studied in long term space missions

Signs of resting muscle tone, assessed by cardiac driven microvibrations (MV), were studied in two cosmonauts during long term space missions on the Russian MIR station. In the 1 g environment, MV showed the typical 7-13 Hz resonance oscillations triggered by the heart beat. In 0 g, these pulsations were damped and the waveform became similar to an acceleration ballistocardiogram. If resting tone was slightly increased by extending the arm in 0 g, the resonance oscillations reappeared in most cases. By means of a simple vibromechanic analog it is demonstrated that the elastic component of muscle has to be reduced during the fully relaxed state in 0g.     

利用GPS进行精密轨道确定

全球定位系统(GPS)完全布满卫星后,将成为近地卫星的精密轨道确定(POD)强有力的工具。该系统具有连续跟踪覆盖能力,不仅可实现传统的动力学精密轨道确定方法,而且还可进行运动学轨道确定。来自至少四个GPS卫星的伪距测量值,通过载波相位测量值的平滑,可测定天线相位中心的地心位置和用户卫星的时钟修正值,因而后一技术不需要用户卫星受力的动力学模型。运动学法对测量模型的影响非常敏感,如GPS星历误差(给定的或求解的)、信号的多径、接收机噪声等等;然而,动力学方法又受参数误差和/或力模型不完善的影响。为此研究出一种利用过程噪声补偿对运动学和动力学算法进行加权的混合方案。本课题的中心点是利用仿真辅以协方差分析,研究这几种定轨方法。建立了几种动力学和测量误差模型,这些模型造成的轨道不确定性与处理实际GPS数据而估计的星历误差大致相当。协方差分析经调整能反映这些误差,能看出各种滤波技术的特性。     

GPS用于MX导弹飞行试验的实时跟踪

霍普金斯大学应用物理实验室最近完成了一项MX导弹(和平卫士)试验飞行的实时GPS跟踪研究。因为飞向夸贾林环礁所需靶场安全提出了严格的精度要求,故分析了各种跟踪方案。本文简述了导弹跟踪的经验之后,介绍了各种系统方案。讨论了各种远站处理方案,接着专门研究了电离层误差修正方法和接收机锁相环路热噪声。最后,叙述了瞬时落点(IIP)时间协方差仿真结果。     

Titan and exobiological aspects of the Cassini-Huygens mission

Titan, the largest satellite of Saturn, has a dense N2-CH4 atmosphere rich in organic compounds, both in gas and in aerosol phases. Its surface is probably covered by oceans of liquid methane-ethane mixtures, with many dissolved organics. This quasi planet appears as a natural laboratory to study chemical evolution toward complex organic systems in a planetary environment over a long time scale. With the Cassini-Huygens mission NASA and ESA will jointly send an orbiter (Cassini) around Saturn and a probe (Huygens) in the atmosphere of Titan. This mission, currently planned to be launched in 1996-1997 for a Saturn - Titan arrival in 2004, offers a unique opportunity to study in detail extra-terrestrial organic processes. Consequently, it has important implications in the field of exobiology and the origins of life.     

数字频率合成的新途径

本文介绍了从1Hz到399999Hz以1Hz步进频率合成新技术。合成的波形是对称方波,与晶体管—晶体管逻辑(TTL)相容。它所使用的合成算法为高效率使用系统的数字式仪器创造了条件。整套设备是由一个输入装置、一个BCD/二进制转换器、一个二进制分频器、一个数字式比较器和一个锁相环(PLL)倍频器组成。     

TRKI-12遥测接收/记录机组中几个重要方面的进一步改进

本文考查了目前安装在东靶场的TRKI—12检前接收/记录机分系统中的几项主要性能,并考交了预期进一步改进的项目。介绍了两个系统的性能特点,这两个系统是由不同的厂商按同一规格分别生产的。几个需着重研究的方面是:接收部分、记录部分以及辅助测试和校准设备。 1962年,为接收/记录机分系统提出任务书的时候,就作出了这样的决定,即要求将接收机与另外一些部件分成若干组件。评述了该决定所碰到的问题及其产生的优点,但侧重于涉及即将改进的若干问题。本文最后简要列出了需进一步改进的项目。为了满足对遥测接收/记录所提的要求,这些改进是完全必要的。