Debris Discs Around Stars: The 2004 ISO Legacy

Debris discs around stars were first discovered by the Infrared Astronomical Satellite (IRAS) in 1983. For the first time material orbiting another star than the Sun, but distinct from a circumstellar envelope, was observed through its far infrared emission. This major discovery motivated astronomers to investigate those discs by further analyzing the IRAS data, using ground-based telescopes for the hunting of exoplanets, developing several projects using the Infrared Space Observatory (ISO), and now exploiting the ISO Data Archive (IDA). This review presents the main ISO results, statistical as well as individual, on debris discs in orbit around pre-main-sequence and main-sequence stars. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, The Netherlands, and the United Kingdom), and with the participation of ISAS and NASA.     

对称性惩罚贴近度在等级划分中的应用

本文在分析了等级划分中的最大值法、贴近度分析方法的基础上,提出了一种改进型的等级划分方法;对称性惩罚贴近度方法。该方法运用对称性惩罚因子使等级划分中的信息得到比较充分的利用,最终的决策结果也更趋于合理。     

带滑移滞变系统的三阶段逐步收敛的识别方法

针对非线性带滑移滞变系统模型复杂，参数多，识别时收敛困难等问题，提出了一种三阶段逐步收敛的识别方法对Baber与Noori提出的带滑移滞变模型进行了参数识别。计算实例表明，该方法具有收敛速度快、且容易收敛的特点，对于参数较多、模型复杂的系统，是一种非常有效的参数识别方法。     

THE APPLICATION OF SATELLITE POSITIONING TECHNOLOGY AND ITS INDUSTRIALIZATION IN CHINA

Satellite positioning technology has been widely used in all kinds of military and civil land, marine, space and aeronautical target positioning tasks, naviga tion activities and accurate surveying measurements since 90 s in the last cen tury due to its advantage in providing all-weather, real-time, three dimensional and high precision positioning information, as well as speed and accurate timing information. By now, it has already formed a new hi-tech industry basically.This paper briefly reviews the development of the global satellite positioning and navigation technologies including the basic information of China's "Plough navigation system", introduces the history of satellite positioning technology and its major application fields as well as the status quo of this being industri alized trade in China, gives an account of the writers' vision for the application and prospect of the satellite positioning technologies in China, and approaches the tactics and stresses of the satellite positioning technology's application and its industrialization future in China.     

基于CSCW的分布式多媒体会议系统

CSCW是今后人们利用计算机进行工作的发展趋势，本文介绍了CSCW的背景、概念及其体系结构，重点讲述了目前技术较为完善的基于CSCW的分布式多媒体会议系统，包括其关键技术、系统结构模型以及工作流程等，进一步说明了CSCW在未来多学科领域的广阔前景。     

The Special Purpose Dexterous Manipulator (SPDM) Systems Engineering Effort – A successful exercise in cheaper,faster and (hopefully) better systems engineering

The Special Purpose Dexterous Manipulator (SPDM) is the latest Space Robot developed by the Canadian Space Agency (CSA) and McDonald Detwiller Space and Advanced Robotics (MD Robotics, previously Spar Aerospace) for the International Space Station (ISS). The SPDM has presented its designers with a number of new challenges in performing the Systems Engineering effort required for a complex robotic system:(1) The SPDM initial design was started and attained various levels of maturity for various components under the Space Station Freedom environment, then the Program was stopped and finally restarted under the harsher environment in which the International Space Station is being built.(2) The SPDM is the first space robot to utilize previously developed and space certified robotic components, as well as components with high-commonality to the previously developed ones (electronics, S/W).(3) New requirements levied by the Customer during the negotiations leading to the Program re-start necessitated significant architectural changes versus the SPDM configuration `frozen' when the Program was shut down.(4) The SPDM is the first robotic system of this complexity that is being built under a Firm Fixed Price contract, with the commonality assumptions as one of the cost drivers.This combination of components of various pedigree, coupled with the constraints imposed by an FFP contract have been addressed by the designers through the definition of a novel approach to integrated Systems and Design Engineering.     

液压系统卡紧的原因及排除措施

本文主要阐述了液压系统中出现液压卡紧现象的危害、原因以及排除方法等。     

飞机突防航迹的非线性解耦跟踪

针对12维非线性飞机动力学模型,利用非线性逆系统理论和现代最优控制理论设计了一组非线性飞行控制规律。这组控制规律通过解耦控制飞机的飞行速度(V)、滚转角(φ)、航迹角(γ)和偏航角(φ_w),使飞机能够精确地跟踪期望的三维突防航迹。计算结果表明,由于这组控制规律计及了飞机动力学模型中的非线性因素,能够完全消除飞机的剧烈耦合反应,从而有效地改善了飞机的动态特性,提高了其低空机动飞行的安全性,大大减轻了驾驶员的工作负担和精神压力,从而圆满地完成突防袭击任务。     

平均绝对差图象匹配系统的定位精度

本文证明了两个基本定理。在假定图象信号和附加噪声是相互独立的零均值齐次高斯随机场、且二次可微的条件下,解决了平均绝对差图象匹配系统的定位精度的分析和计算问题。用实例说明了精度分析和计算的方法,分析了影响定位精度的因素和参数。为匹配性能的定量分析提供了理论依据和方法。     

时变线性系统的全程滑态变结构控制研究

本文采用分段定常的处理方法研究了一般时变线性系统的滑态变结构控制方案，提出了实时自动分段原则与相应的全程滑态结构控制算法，并通过数字仿真验证了该方案的有效性。