The NASA Astrobiology Roadmap

The NASA Astrobiology Roadmap provides guidance for research and technology development across the NASA enterprises that encompass the space, Earth, and biological sciences. The ongoing development of astrobiology roadmaps embodies the contributions of diverse scientists and technologists from government, universities, and private institutions. The Roadmap addresses three basic questions: How does life begin and evolve, does life exist elsewhere in the universe, and what is the future of life on Earth and beyond? Seven Science Goals outline the following key domains of investigation: understanding the nature and distribution of habitable environments in the universe, exploring for habitable environments and life in our own solar system, understanding the emergence of life, determining how early life on Earth interacted and evolved with its changing environment, understanding the evolutionary mechanisms and environmental limits of life, determining the principles that will shape life in the future, and recognizing signatures of life on other worlds and on early Earth. For each of these goals, Science Objectives outline more specific high-priority efforts for the next 3-5 years. These 18 objectives are being integrated with NASA strategic planning.     

流媒体技术及其应用

本文主要研究了流媒体的相关原理和技术支持,包括流媒体技术基础、流媒体播放方式、媒体服务器平台等主要内容,并简要介绍了视频直播解决方案、校园网视频解决方案和网上流式视音频解决方案等流媒体技术应用方案.     

利用小波分析对合成孔径雷达图像分类

本文旨在提出一种利用小波变换获得的多分辨率图像表示对合成孔径雷达图像进行分类的方法。     

制导雷达的战备完好率研究

根据作战要求，建立了地空导弹制导雷达战备完好率的数学模型，并进行了分析。分析认为，制导雷达的战备完好率主要取决于系统的可靠性设计和功能检查的覆盖面；系统的故障检测率和修复率由设备的ＢＩＴＥ的检测率和在规定时间内故障的修复率来决定。     

小遥控飞行器用毫米波雷达

已经研制了一台９５ＧＨｚ的实验型毫米波雷达用来对小遥控飞行器所用的具有当今工艺水平的器件和技术进行评价。雷达被设计用于左恶劣天气时进行战术监视，工作方式包括高分辨率地面测绘、固定目标增强和动目标显示。     

X波段单发多收体制下用于解距离模糊的时变二相码波形优化设计

针对小卫星雷达系统由于天线尺寸受限、宽波束照射面积大而带来的方位模糊,通过采用高脉冲重复频率来解方位模糊,然后利用发射波形的时变特性来解决高重频带来的距离模糊。基于此,采用了一种梯度遗传算法对多发射二相码波形进行优化,使其自相关峰值、积分旁瓣电平和互相关主副比、积分旁瓣电平尽可能的低。同时对多约束构成的适应度函数进行自适应尺度因子加权,以克服不同约束带来的不同数量级所造成的优化倾向问题。仿真结果和性能分析验证了该算法的有效性和可行性。     

Ll—CFAR—一种灵活的鲁棒设计

本文介绍一种新的恒虚警率（ＣＦＡＲ）处理器。Ｌｌ－ＣＦＡＲ通过对参考集排列样本线性滤波来形成其噪声功率估值；但是，这一组合的权值不仅仅取决于排列，而且还取决于样本与测试单元的相对接近程度。这类Ｌｌ－ＣＦＡＲ中有些能有效检查假目标；有些可以在有杂波边缘时对虚警进行令人信服的控制；而另一些则对这两种不均匀性均具有鲁棒性。当设计中含有这些方案时，它们执行起来不比普通序列统计ＣＦＡＲ（ＯＳ－ＣＦＡＲ）累赘     

Carotid artery pulsatility during parabolic flights

In cardio-vascular hemodynamic, the arterial pulsatility, represented by the arterial pulse pressure (PP= systolic blood pressure-diastolic blood pressure), is different from one site to another, in opposite with the mean blood pressure almost identical in the whole body in supine position (or in microgravity). This is due to the arterial tree geometry and regional differences in the distensibility properties of the arterial wall. As the level of blood pressure opposed to the cardiac left ventricle work is the central pressure, on one hand and as the arterial pulsatility at the site of arterial baro-receptors (located on aortic arch and carotid arteries' bifurcation) regulates the sympathetic and vagal control of heart and peripheral resistances on the other hand, to determine the evolution of this central pulse pressure is of major importance in the knowledge of cardio-vascular hemodynamic during hyper or hypogravity as observed during parabolic flights. The aim of this study was to evaluate noninvasively the carotid artery pulsatility and mechanic properties during parabolic flights.     

李家祥局长与空管团干班座谈

10月13日,民航局李家祥局长前往民航管理干部学院与正在学习的学员们进行座谈。民航空管系统第一期共青团干部和青年工作骨干培训班的全体学员参加了座谈会。