环境试验数据和控制系统技术:过去、现在、将来

Michellich先生毕业于堪萨斯大学,获得博士学位。他1966年进入波音公司。他曾搞过土星V的仪表系统试验,S—IC级靜态点火数据处理,研究随机和瞬态数据处理程序、研究振动控制系统软件。现在他在波音航空工程实验室负责研制新的数据收集,试验控制和数据处理系统。     

Potential of cathodoluminescence microscopy and spectroscopy for the detection of prokaryotic cells on minerals

Detecting mineral-hosted ecosystems to assess the extent and functioning of the biosphere from the surface to deep Earth requires appropriate techniques that provide, beyond the morphological criteria, indubitable clues of the presence of prokaryotic cells. Here, we evaluate the capability of cathodoluminescence microscopy and spectroscopy, implemented on a scanning electron microscope, to identify prokaryotes on mineral surfaces. For this purpose, we used, as a first step, a simple model of either unstained or stained cultivable cells (Escherichia coli, Deinococcus radiodurans) deposited on minerals that are common in the oceanic crust (basaltic glass, amphibole, pyroxene, and magnetite). Our results demonstrate that the detection of cells is possible at the micrometric level on the investigated minerals through the intrinsic fluorescence of their constituting macromolecules (aromatic amino and nucleic acids, coenzymes). This allows us to distinguish biomorph inorganic phases from cells. This easily implemented technique permits an exploration of colonized rock samples. In addition, the range of spectrometric techniques available on a scanning electron microscope can provide additional information on the nature and chemistry of the associated mineral phases, which would lead to a simultaneous characterization of cells, their microhabitats, and a better understanding of their potential relationships.     

洁齿

在一个世纪以前及更早的时候,要想在自然环境下拍摄到野生动物,简直无法想象的困难。1906年,美国《国家地理》杂志首次刊登了74张夜行动物的照片,之后,就开始不断展现野生动物摄影突破性的成就。这张1966年摄于锡兰     

Lava cave microbial communities within mats and secondary mineral deposits: implications for life detection on other planets

Lava caves contain a wealth of yellow, white, pink, tan, and gold-colored microbial mats; but in addition to these clearly biological mats, there are many secondary mineral deposits that are nonbiological in appearance. Secondary mineral deposits examined include an amorphous copper-silicate deposit (Hawai'i) that is blue-green in color and contains reticulated and fuzzy filament morphologies. In the Azores, lava tubes contain iron-oxide formations, a soft ooze-like coating, and pink hexagons on basaltic glass, while gold-colored deposits are found in lava caves in New Mexico and Hawai'i. A combination of scanning electron microscopy (SEM) and molecular techniques was used to analyze these communities. Molecular analyses of the microbial mats and secondary mineral deposits revealed a community that contains 14 phyla of bacteria across three locations: the Azores, New Mexico, and Hawai'i. Similarities exist between bacterial phyla found in microbial mats and secondary minerals, but marked differences also occur, such as the lack of Actinobacteria in two-thirds of the secondary mineral deposits. The discovery that such deposits contain abundant life can help guide our detection of life on extraterrestrial bodies.     

力传递中的不确定度的极限

近年来国际间比较测量日益增多,本文着重讨论力传感器的试验问题。指出了影响测量不确定度的各种因素。用实例来说明这些误差,并介绍减小误差的方法。     

航天飞机时频传递实验

一、引言 1.背景美国航空航天局(NASA)的空间和地面应用处正在考虑一项航天飞机实验,用来验证几种比对全球高精密时钟和原始频标的技术。该实验准备在航天飞机上装一台氢脉泽时钟,利用微波和激光脉冲信号比对航天飞机上的空间时钟与地面站上的时钟。提出该项实验的目的是验证几种时间传递技术,这些技术能以1毫微秒以上的精度比对时钟时间,以10~(-14)以上的精度比对时钟频率。能以10~(-14)的精度比对频率这种能力是本项实验的独到之处。目     

冲压——火箭发动机的突扩喷射

对冲压——火箭发动机冲压级突扩喷射的重要性作了说明并简要地评论了这一领域最近的研究工作之后,本文介绍一种计算椭圆型内部反应流的数值方法。它是把算子分裂法用于物质守恒方程,使这些方程中通常是疑难的积分在两步演算中完成。对于无反应的第一阶段,应用Gosman等人的算法;而有反应的第二阶段,使方程式能改写成一组常微分方程。为处理常常与实际的化学动力学问题有关的刚性,应用Gear的方法对不同的几何构型解该常微分方程组。 实验结果同数值法的预估值很好地相符。发现在靠近喷射处有一强大的回流区。几何构型既影响化学反应又影响流动稳定性:45°喷射引起平均流率的增加,而90°时却不明显。垂直喷射比45°进气好象是更加稳定,这还取决于恰当的构型。