军用通信卫星与信息战

未来的战争将无疑是高技术条件下的信息化战争,信息战中对信息的传输提出了许多特殊的要求。报告依据90年代几次高技术局部战争的经验,论述了卫星通信系统在信息战中信息传输的诸多优势,详细讨论了国外军用卫星通信系统及其通信有效载荷技术的发展现状和特点,探讨了21世纪初期的发展规划、趋势及其需要发展的诸多相关技术。面对未来信息战以及我国周边环境的现状,提出了发展我国军用通信卫星的具体策略。     

精密压力压电敏感器件温度与压力间的函数关系

对石英压力压电敏感器件的原理分析表明:这种敏感器达到热平衡状态具有相当长的时间常数,大约一小时量级。在这种情况下,再也不能忽略敏感器件的温度随压力的变化关系。当人们一旦需要使用精密敏感器件时,使要考虑到这一关系;本文将论及这一函数关系。     

卫星系统社会经济效益评价指标体系探讨

简要地评述了国内外卫星系统社会经济效益的评价现状及其评价体系，论证了卫星特殊的社会经济属性，运用系统评价方法和经济效益理论综合出一个卫星系统社会经济效益评价指标体系，并指出了它的应用条件、评价作用及应注意的问题。     

Microbial populations in Antarctic permafrost: biodiversity, state, age, and implication for astrobiology

Antarctic permafrost soils have not received as much geocryological and biological study as has been devoted to the ice sheet, though the permafrost is more stable and older and inhabited by more microbes. This makes these soils potentially more informative and a more significant microbial repository than ice sheets. Due to the stability of the subsurface physicochemical regime, Antarctic permafrost is not an extreme environment but a balanced natural one. Up to 10(4) viable cells/g, whose age presumably corresponds to the longevity of the permanently frozen state of the sediments, have been isolated from Antarctic permafrost. Along with the microbes, metabolic by-products are preserved. This presumed natural cryopreservation makes it possible to observe what may be the oldest microbial communities on Earth. Here, we describe the Antarctic permafrost habitat and biodiversity and provide a model for martian ecosystems.     

Distribution and stable isotopic composition of amino acids from fungal peptaibiotics: assessing the potential for meteoritic contamination

The presence of nonprotein α-dialkyl-amino acids such as α-aminoisobutyric acid (α-AIB) and isovaline (Iva), which are considered to be relatively rare in the terrestrial biosphere, has long been used as an indication of the indigeneity of meteoritic amino acids. However, recent work showing the presence of α-AIB and Iva in peptides produced by a widespread group of filamentous fungi indicates the possibility of a terrestrial biotic source for the α-AIB observed in some meteorites. We measured the amino acid distribution and stable carbon and nitrogen isotopic composition of four α-AIB-containing fungal peptides and compared this data to similar meteoritic measurements. We show that the relatively simple distribution of the C(4) and C(5) amino acids in fungal peptides is distinct from the complex distribution observed in many carbonaceous chondrites. We also identify potentially diagnostic relationships between the stable isotopic compositions of pairs of amino acids from the fungal peptides that may aid in ruling out fungal contamination as a source of meteoritic amino acids.     

Public school teachers in the U.S. evaluate the educational impact of student space experiments launched by expendable vehicles, aboard Skylab, and aboard Space Shuttle

Space education is a discipline that has evolved at an unprecedented rate over the past 25 years. Although program proceedings, research literature, and historical documentation have captured fragmented pieces of information about student space experiments, the field lacks a valid comprehensive study that measures the educational impact of sounding rockets, Skylab, Ariane, AMSAT, and Space Shuttle. The lack of this information is a problem for space educators worldwide which led to a national study with classroom teachers. Student flown experiments continue to offer a unique experiential approach to teach students thinking and reasoning skills that are imperative in the current international competitive environment in which they live and will work. Understanding the history as well as the current status and educational spin-offs of these experimental programs strengthens the teaching capacity of educators throughout the world to develop problem solving skills and various higher mental processes in the schools. These skills and processes enable students to use their knowledge more effectively and efficiently long after they leave the classroom. This paper focuses on student space experiments as a means of motivating students to meet this educational goal successfully.     

通信卫星星上波束形成技术及发展

随着通信卫星技术的迅速发展,星上天线技术也不断取得重要的进展,其关键技术之一星上波束形成技术对提高系统性能有重要作用。目前,这种技术已从模拟波束形成向数字波束形成,从微波波束形成向光学波束形成发展。本文主要介绍国外一些典型通信卫星采用的星上波束形成技术,重点介绍数字波束形成（ＤＢＦ）技术及其在通信卫星上的应用。     

国外通信卫星有源相控阵天线及发展

本文介绍了国外通信卫星用有源相控天线及发展，主要介绍了低轨道个人移动通信系统的铱星和全球星，欧洲数据中继卫星及用于未来通信卫星的有源相控阵天线的研制和发展。