Subcritical water extractor for Mars analog soil analysis

Abstract Technologies that enable rapid and efficient extraction of biomarker compounds from various solid matrices are a critical requirement for the successful implementation of in situ chemical analysis of the martian regolith. Here, we describe a portable subcritical water extractor that mimics multiple organic solvent polarities by tuning the dielectric constant of liquid water through adjustment of temperature and pressure. Soil samples, collected from the Yungay region of the Atacama Desert (martian regolith analogue) in the summer of 2005, were used to test the instrument's performance. The total organic carbon was extracted from the samples at concentrations of 0.2-55.4 parts per million. The extraction data were compared to the total organic carbon content in the bulk soil, which was determined via a standard analytical procedure. The instrument's performance was examined over the temperature range of 25-250 degrees C at a fixed pressure of 20.7 MPa. Under these conditions, water remains in a subcritical fluid state with a dielectric constant varying between approximately 80 (at 25 degrees C) and approximately 30 (at 250 degrees C).     

传感器融合的统计集群分析法

传感器融合(SF)问题需要考虑的是，利用从多个独立传感器接收到的目标位置测量值来估计目标的数量和位置。采用集群分析法来解决这种问题。在集群分析问题中，我们应用多假设测试技术，并已开发出判断规则，它可确保产生虚假目标的概率小于假定概率，同时采用更精确的测量值可降低遗漏已存在目标的可能性，还可获得目标位置估计值。已经研究出了实现以上判定规则的计算方法。     

The Urey instrument: an advanced in situ organic and oxidant detector for Mars exploration

The Urey organic and oxidant detector consists of a suite of instruments designed to search for several classes of organic molecules in the martian regolith and ascertain whether these compounds were produced by biotic or abiotic processes using chirality measurements. These experiments will also determine the chemical stability of organic molecules within the host regolith based on the presence and chemical reactivity of surface and atmospheric oxidants. Urey has been selected for the Pasteur payload on the European Space Agency's (ESA's) upcoming 2013 ExoMars rover mission. The diverse and effective capabilities of Urey make it an integral part of the payload and will help to achieve a large portion of the mission's primary scientific objective: "to search for signs of past and present life on Mars." This instrument is named in honor of Harold Urey for his seminal contributions to the fields of cosmochemistry and the origin of life.     

采用GMTI雷达跟踪难以确定的动-停-动目标的VS-IMM评估器

提出了可变结构相互作用的多模型(V-IMM)评估器的设计，它采用从机载传感器中获得的地面动目标指示(GMTI)的报告来跟踪难以确定的地面目标。为了避开GMTI传感器的探测，目标采用“动-停-动”模式，即目标在加速之前的某个时候以非常低的速度运动或停止。在这种情况下，当目标的径向速度(沿传感器的视线方向)降至低于某个最小的可探测速度时，传感器就无法探测到目标。在这种条件下，如果使用的传感器不能识别“动-停-动”运动模式，将破坏目标的运动轨迹。本文所提出的VS-IMM评估器就是处理难以确定“动-停-动”目标的运动，在这里，当目标的速度降至某个门限以下，跟踪模型就包括了“停止-目标”模式。采用停止目标模型后，即使在目标检测不连续时仍能保持跟踪的稳定。文中采用仿真的方法来说明设计参数的选择和跟踪器的具体设计。最后，对使用停止目标模式的VS-IMM评估器和传统的：IMM评估器进行性能比较。     

采用旋转时频-Radon变换的地面动目标的叶簇穿透SAR成像

本文介绍了旋转傅里叶变换、双线性旋转时频变换和Radon变换的基本概念。根据动目标雷达回波的某种模型，提出了一种采用旋转时频-Radon变换用于树林中动目标SAR成像的方法。     

Positive pressure breathing by total body negative pressure: a new simulation model for fluid balance in weightlessness?

A systems study is proposed to explore correctly the effects of the combination of HDT (Head Down Tilt) and TBNP (Total Body Negative Pressure).     

雷达海杂波模型的比较

雷达性能预计一直是雷达系统设计和研究的重要部分。现在的雷达自适应强，性能可靠，可重构并且能在脉冲间变换其波形。这些如此复杂的系统的实现和接受不能仅仅从多种雷达模式的实验中所获得，目标和杂波条件是受限的。性能预计的结果提出了一种将在白天环境条件下获得的有限实验结果扩展到全部理想运行中的方法。在自由空间中雷达性能的分析已得到了充分证明和理解，但在杂波环境中雷达目标的模拟还是个有待研究的领域。