用于飞机健康监控的传感器技术不断升级

得益于数据处理和存储技术的进步，从飞机上获取的数据量呈爆发式增长，可对飞机实施预测性维修的机会也越来越多。其中，不断进步的传感器技术是支撑飞机健康监控技术发展的关键因素。     

“阿波罗11”号与UFO

“阿波罗11”号登月才过去几十年，但这一事件已经成为历史课本中的传奇，标志着人类第一次在另一个世界登陆，同时也展示了20世纪60年代美国的科技和组织、管理、协调能力。对U10领域的专家、粉丝以及反对者来说，“阿波罗11”号登月也意义非凡。多年以来，在这次史诗级的空间旅行中，一直有关于UFO的报告和照片流传。     

测量燃烧室内温度时的热辐射修正

我们在进行某一环形燃烧室扇形形试验件的试验研究时,用热电偶测量了燃烧室内的温度分布。一般来说,热电偶不能获得与热燃气同样的温度,这是因为热电偶和周围环境有着辐射能量的交换。通常是热电偶节点向冷的壁面辐射能量。在稳态时,燃气通过对流传热向热电偶节点提供能量来平衡这一损失。这就是说,热电偶节点测得的温度较燃气的真实温度要低,这一温差就是由辐射热损失造成的。下面介绍对此热辐射损失进行修正的一个简化方法。      

21世纪士兵的新装备——微型无人飞行器

由于高能量储备和微型精确飞行控制技术的突破性进展,一种供士兵用的比鸟还小的微型侦察无人机已被列入美国国防研制计划     

冷轧无间隙原子钢中的微带生成机理

分析了冷轧体心立方金属中微带的形成原因.基于塑性变形理论,运用Taylor模型和Bishop＆Hill最大功原理,计算了变形体心立方晶体中滑移系上的切应变分布.计算结果表明,冷轧时当晶粒的轧向平行于晶粒的某些特定取向时,大量的局部切应变将集中产生在一个滑移面上并在此形成微带.这一高度局域性的切应变是形成剪切带的原因.此时,剪切带与轧制方向之间夹角为30°.另外,微带呈片状是双交滑移的结果,透射电子显微镜观察到的剪切带所在晶粒的取向和所在滑移面证实了这一微带的形成机制.     

一种新型多普勒噪声抑制技术对BepiColombo任务无线电科学实验的性能提升

在欧洲空间局和日本宇宙开发机构联合开展的BepiColombo水星任务中,将开展水星轨道器无线电科学实验,包括估计水星的引力场及其旋转状态,并对广义相对论进行验证。目前地面系统和星上设备的主流配置可以在无线电科学实验中建立X/X、X/Ka和Ka/Ka多个频段的链路,测速精度可达3 um/s（1 000 s积分）,测距精度为20 cm。提出了基于时延机械噪声对消技术提高无线电科学实验性能的方案。时延机械噪声对消技术需要处理在两个测站不同时刻的测量数据,一个测站实施双向多普勒测距,对另一个单收测站的要求较为严格,该测站需要具有较好的对流层条件。这种方法能够显著降低Ka频段双向链路的主要测量噪声,包括由对流层和天线机械系统震动引起的噪声。我们给出了端到端的仿真性能,并估计了在使用时延机械噪声对消技术前提下的水星引力场和旋转状态。考虑使用NASA位于美国本土戈尔德斯敦的DSS-25天线或欧空局位于阿根廷马拉圭的DSA-3天线作为双程测量站,并考虑使用位于智力的APEX天文观测天线作为单收站。分析结果表明在最好的噪声条件下,使用DSA-3天线作为双程测量站时,时延机械噪声对消技术可将待估计的全局和局部参数的估计精度提升一倍。对于无线电科学实验的目标,这一可能的性能提升对行星地质物理学很有意义,它将有益于研究水星内部的结构。     

Calcification and silicification: fossilization potential of cyanobacteria from stromatolites of Niuafo'ou's Caldera Lakes (Tonga) and implications for the early fossil record

Calcification and silicification processes of cyanobacterial mats that form stromatolites in two caldera lakes of Niuafo'ou Island (Vai Lahi and Vai Si'i) were evaluated, and their importance as analogues for interpreting the early fossil record are discussed. It has been shown that the potential for morphological preservation of Niuafo'ou cyanobacteria is highly dependent on the timing and type of mineral phase involved in the fossilization process. Four main modes of mineralization of cyanobacteria organic parts have been recognized: (i) primary early postmortem calcification by aragonite nanograins that transform quickly into larger needle-like crystals and almost totally destroy the cellular structures, (ii) primary early postmortem silicification of almost intact cyanobacterial cells that leave a record of spectacularly well-preserved cellular structures, (iii) replacement by silica of primary aragonite that has already recrystallized and obliterated the cellular structures, (iv) occasional replacement of primary aragonite precipitated in the mucopolysaccharide sheaths and extracellular polymeric substances by Al-Mg-Fe silicates. These observations suggest that the extremely scarce earliest fossil record may, in part, be the result of (a) secondary replacement by silica of primary carbonate minerals (aragonite, calcite, siderite), which, due to recrystallization, had already annihilated the cellular morphology of the mineralized microbiota or (b) relatively late primary silicification of already highly degraded and no longer morphologically identifiable microbial remains.     

The PROCESS experiment: an astrochemistry laboratory for solid and gaseous organic samples in low-earth orbit

The PROCESS (PRebiotic Organic ChEmistry on the Space Station) experiment was part of the EXPOSE-E payload outside the European Columbus module of the International Space Station from February 2008 to August 2009. During this interval, organic samples were exposed to space conditions to simulate their evolution in various astrophysical environments. The samples used represent organic species related to the evolution of organic matter on the small bodies of the Solar System (carbonaceous asteroids and comets), the photolysis of methane in the atmosphere of Titan, and the search for organic matter at the surface of Mars. This paper describes the hardware developed for this experiment as well as the results for the glycine solid-phase samples and the gas-phase samples that were used with regard to the atmosphere of Titan. Lessons learned from this experiment are also presented for future low-Earth orbit astrochemistry investigations.     

Alfvn Waves in the Solar Wind

Alfvn waves are found to be ubiquitous in the solar wind.Recent progress in observational studies of the waves is reviewed to formulate a microscopic picture for the Alfvenic fluctuations. The main aspects of the observational properties of these waves,including the wave intervals, propagation,evolution,origin and generation,are presented.Then Alfven wave heating and acceleration of the solar wind plasma are briefly introduced.The relation of the waves to rotational and tangential discontinuities,magnetic decreases,and other relatively large-scale structures such as flux tubes/ropes,magnetic clouds and interplanetary coronal mass ejections in the solar wind is particularly investigated.Finally,some remaining open questions are also indicated due to their fundamental importance of understanding of the physical nature of Alfven waves and the role of the waves in heating and accelerating the solar wind.     

Sunspot dynamics are reflected in human physiology and pathophysiology

Periodic episodes of increased sunspot activity (solar electromagnetic storms) occur with 10-11 and 5-6 year periodicities and may be associated with measurable biological events. We investigated whether this sunspot periodicity characterized the incidence of Pap smear-determined cervical epithelial histopathologies and human physiologic functions. From January 1983 through December 2003, monthly averages were obtained for solar flux and sunspot numbers; six infectious, premalignant and malignant changes in the cervical epithelium from 1,182,421 consecutive, serially independent, screening Pap smears (59°9″N, 4°29″E); and six human physiologic functions of a healthy man (oral temperature, pulse, systolic and diastolic blood pressure, respiration, and peak expiratory flow), which were measured ～5 times daily during ～34,500 self-measurement sessions (44°56″N, 93°8″W). After determining that sunspot numbers and solar flux, which were not annually rhythmic, occurred with a prominent 10-year and a less-prominent 5.75-year periodicity during this 21-year study span, each biological data set was analyzed with the same curve-fitting procedures. All six annually rhythmic Pap smear-detected infectious, premalignant and malignant cervical epithelial pathologies showed strong 10-year and weaker 5.75-year cycles, as did all six self-measured, annually rhythmic, physiologic functions. The phases (maxima) for the six histopathologic findings and five of six physiologic measurements were very near, or within, the first two quarters following the 10-year solar maxima. These findings add to the growing evidence that solar magnetic storm periodicities are mirrored by cyclic phase-locked rhythms of similar period length or lengths in human physiology and pathophysiology.