Biomedical support of man in space

In its broadest sense, biomedical support of man in space must not be limited to assisting spacecraft crew during the mission; such support should also ensure that flight personnel be able to perform properly during landing and after leaving the craft. Man has developed mechanisms that allow him to cope with specific stresses in his normal habitat; there is indisputable evidence that, in some cases, the space environment, by relieving these stresses, has also allowed the adaptive mechanisms to lapse, causing serious problems after re-entry. Inflight biomedical support must therefore include means to simulate some of the normal stresses of the Earth environment. In the area of cardiovascular performance, we have come to rely heavily on complex feedback mechanisms to cope with two stresses, often combined: postural changes, which alter the body axis along which gravitational acceleration acts, and physical exercise, which increases the total load on the system. Unless the appropriate responses are reinforced continuously during flight, crew members may be incapacitated upon return. The first step in the support process must be a study of the way in which changes in g, even of short duration, affect these responses. In particular we should learn more about effects of g on the "on" and "off" dynamics, using a variety of approaches: increased acceleration on one hand at recumbency, immersion, lower body positive pressure, and other means of simulating some of the effects of low g, on the other. Once we understand this, we will have to determine the minimal exposure dose required to maintain the response mechanisms. Finally, we shall have to design stresses that simulate Earth environment and can be imposed in the space vehicle. Some of the information is already at hand; we know that several aspects of the response to exercise are affected by posture. Results from a current series of studies on the kinetics of tilt and on the dynamics of readjustment to exercise in different postures will be presented and discussed.     

欧洲极轨平台上的中分辨率成像光谱仪

本文描述了中分辨率成像光谱仪(MERIS)的设计。该仪器已被选为计划于1997年发射的欧洲极轨平台上的一个核心仪器。其光谱覆盖范围为400nm到1050nm,覆盖区宽度为1500km,光谱分辨率为1.5nm,空间分辨率为260m。此仪器主要用于海洋、陆地和大气方面的研究。     

“主飞行操纵系统特性”组在无锡召开讨论会

军用飞机飞行品质规范(试用本)计算手册第四章“主飞行操纵系统特性”统编稿的讨论、审定会,于一九八三年四月三日至六日在无锡召开,参加会议的代表,除主编、副主编、编写和校对人员外,还邀请了高等院校老师和各主机所从事飞行力学和操纵系统专业的、具有丰富理论知识和实际经验的科技人员。     

论清代前期统一的历史局限性

对于清代前期的统一，我们既要看到它的深远影响，也应指出其严重失误。诸如排斥汉族将帅参与边疆事务，在边疆某些地区滥施淫威，对蒙古及黄教政策的消极影响，虚边政策的危害，闭关自守政策的恶果等等，结果很快从“盛世”坠入“衰世”，内忧外患，纷至沓来，到清末时已是不可救药了。     

采样成像系统中的混叠问题研究

文章就采样成像系统中的混叠问题进行了探讨。     

小卫星编队飞行的应用模式分析及展望

自上世纪90年代后期开始,国际上关于小卫星的研究越来越引起世界航天领域的极大兴趣和广泛关注。目前,关于小卫星及其应用研究也已进入了一个新的阶段。作为小卫星应用的一个重要方面,小卫星的编队飞行技术也被普遍认为是未来小卫星应用模式的必然趋势。正因为如此,在近10年的发展过程中,包括美国航宇局、喷气推进实验室、美国空军和欧空局在内的多家著名航空航天研究机构都斥资开展了多个编队飞行任务,小卫星编队飞行技术及其应用研究已经取得了相当的成就。     

低轨对地观测卫星凝视成像仪探讨

文章介绍了典型空间信息获取方式及特点，阐述了低轨对地观测卫星凝视成像面临的问题及解决对策，对两种低轨对地观测卫星凝视成像仪及其应用进行了探讨。     

Nitrogen reduction under hydrothermal vent conditions: implications for the prebiotic synthesis of C-H-O-N compounds

Dinitrogen is reduced in dilute hydrogen sulfide (H2S) solutions to ammonium at 120 degrees C. Experiments with dissolved dinitrogen (partial pressure 50 bar) in a 12 x 10(-3) mol/L H2S(aq) solution yield approximately 10(-5) mol/L NH4+ within 2-7 days. These yields are consistent with the equilibrium NH4+ concentration for the N-S-H system under these conditions. The formation of ammonium is catalyzed by the presence of freshly precipitated iron monosulfide. These results indicate that dinitrogen can be reduced at moderate temperatures in hydrothermal vent systems. Abiotic nitrogen reduction could have taken place within primordial hydrothermal vents, supplying some ammonia for the synthesis of C-H-O-N compounds via abiotic processes. The yield of ammonia via dinitrogen reduction by hydrogen sulfide, however, is so low that it is doubtful this process could have produced enough ammonia to sustain prebiotic hydrothermal synthesis of C-H-O-N compounds in or around vent systems.     

光学遥感器星上定标的新进展

文中简要阐述了光学遥感器星上定标的重要性,分析了光学遥感器星上定标的现状,重点介绍了增强型主题绘图仪(ETM)、中分辨率成像光谱仪(MODIS-N)、中分辨率成像光谱仪(MERIS)、可见/红外成像辐射计(VIRI)和红外多光谱扫描仪(IRMSS)等几个光学遥感器上的几种新的、典型的星上定标系统。最后,对星上定标的发展趋势进行了概括。