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。     

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.     

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。     

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。     

卫星微波侦察技术现状、趋势和发展对策

未来高技术条件下的局部战争将是一场信息战。海湾战争、波黑行动、科索沃战争都充分证明卫星已成为高技术条件下局部战争中直接支持战场作战行动的重要支援保障系统，具有不可替代的作用，其中卫星成像侦察、电子侦察、海洋监视占有重要地位。本文介绍了卫星微波成你侦察、电子侦察、海洋监视技术的应用现状，重点介绍了卫星系统和星上有效载荷技术的现状和发展趋势，初步探讨了适应未来信息战；发展我国卫星侦察监视有效载荷技术的途径和需要尽快发展的一些关键技术及对策。     

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。     

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.     

Microbial rock inhabitants survive hypervelocity impacts on Mars-like host planets: first phase of lithopanspermia experimentally tested

The scenario of lithopanspermia describes the viable transport of microorganisms via meteorites. To test the first step of lithopanspermia, i.e., the impact ejection from a planet, systematic shock recovery experiments within a pressure range observed in martian meteorites (5-50 GPa) were performed with dry layers of microorganisms (spores of Bacillus subtilis, cells of the endolithic cyanobacterium Chroococcidiopsis, and thalli and ascocarps of the lichen Xanthoria elegans) sandwiched between gabbro discs (martian analogue rock). Actual shock pressures were determined by refractive index measurements and Raman spectroscopy, and shock temperature profiles were calculated. Pressure-effect curves were constructed for survival of B. subtilis spores and Chroococcidiopsis cells from the number of colony-forming units, and for vitality of the photobiont and mycobiont of Xanthoria elegans from confocal laser scanning microscopy after live/dead staining (FUN-I). A vital launch window for the transport of rock-colonizing microorganisms from a Mars-like planet was inferred, which encompasses shock pressures in the range of 5 to about 40 GPa for the bacterial endospores and the lichens, and a more limited shock pressure range for the cyanobacterium (from 5-10 GPa). The results support concepts of viable impact ejections from Mars-like planets and the possibility of reseeding early Earth after asteroid cataclysms.