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GLONASS (Global Orbiting Navigation Satellite System) is the most recent satellite navigation system developed by the Soviet Union and currently in the pre-operational stage. Obvious parallels exist between GLONASS and the NAVSTAR Global Positioning System (GPS) developed in the United States and also, at present, in a pre-operational phase. In the progress towards operational status, the launch capability for NAVSTAR satellites has been seriously affected by the recent failure of the Space Shuttle Challenger, clearly increasing the prospects of GLONASS reaching operational status first. It is therefore the main purpose of this paper to discuss certain aspects of the GLONASS satellite navigation system, in particular its orbital features and radio-frequency signal characteristics. Comparisons with NAVSTAR are inevitable and for this reason, the paper begins with a brief resume of relevant features of the NAVSTAR GPS system for later reference. The main section of the paper then deals with orbital behaviour, radio frequency signal structure and channelisation using NAVSTAR as a reference point for discussion. 相似文献
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J. G. Luhmann 《Space Science Reviews》1986,44(3-4):241-306
This paper assesses our current understanding of the solar wind interaction with Venus in light of developments since the last major reviews were published in 1983. Suggestions for making further progress in the area of solar wind interactions with planetary atmospheres and ionospheres are offered based on the available observations and techniques, and from the viewpoint of forthcoming missions to Mars. 相似文献
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2002年度中国空气动力学研究进展报告 总被引:1,自引:0,他引:1
Chinese Aerodynamics Research Society has been motivated by the mission statement "Academic Innovation, Economical Provision, Personnel Education, Science and Technology Popularization" and by the suggestion of "To be Creative, Competitive, Cohesive, Autonomous", which were raised by Professor Zhang Hanxin, the board chairman of Chinese Aerodynamics Research Society in the Forth National Convention of the society. Under the leadership of the participating organizations of the society, through the diligent work of numerous scientists and technicians, Chinese Aerodynamics Research Society has made significant progress and obtained important research achievements in the fields of theoretical analysis, experimental research, computational fluid mechanics, development of the experimental facilities and equipments system, and the engineering application of aerodynamics in the year 2002. Such progress has established a solid foundation for the breakthrough in the aerodynamic research in the near future and for making the aerodynamic technologies the critical element in the national economy and defense in China. 相似文献
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以某潜艇防空导弹武器系统的作战过程为对象,建立了该武器系统综合作战效能的指标体系,采用层次分析法(AHP法)与专家组决策法(Delphi法)相结合的方法确定各指标的权重,并且对各指标进行量化后规范化处理,给出分级的潜艇防空导弹武器系统综合作战效能综合评估模型,并举例进行定量分析和计算。 相似文献
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The proposed KAAD (knowledge-based automated air defense) system demonstrates a man-machine environment for airspace defense systems. When the unknown aircraft is hostile, a threat rating and response methods are generated by the system. It serves as a double-check decision-making system for a war control center. In addition to this application, the KAAD system can also be a useful tool as a training program for the war controller. The capabilities of the system are limited due to the shortage of knowledge resources. It requires communications among war controllers and air fighter pilots to organize a practical knowledge base. It is shown that the KAAD system can be combined with an automated ATC (air traffic control) system to become a practical system for air defense applications 相似文献
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弹道导弹预警探测识别技术是反导理论和实践需要突破的核心关键技术.美国为了取得反导方面的战略优势地位,长期致力于推动预警探测识别技术的发展,美国预警探测识别系统发展可分为部署初期预警系统、发展新型预警探测识别技术、升级预警探测识别系统并提升目标识别能力等3个重要阶段,目前仍在不断改进完善.其中,林肯实验室在预警探测识别技术方面进行了长期的探索研究,在美国预警探测识别系统建设中发挥了至关重要的作用.此外,美国还利用原有导弹试验靶场,建立太平洋反导试验台,开展了大量反导试验,这也是美军加快生成反导作战能力的“孵化器”和“磨刀石”.通过分析美国预警探测识别系统发展情况,可以得出一些有用的启示. 相似文献
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"异化"是马克思在一百多年前所提出的一个重要概念,它对工业化进程的批判意义历久而弥新,对于我们今天建设社会主义和谐社会也具有启示作用。从对"异化"与"人化"概念的解析入手,把马克思的"异化"概念同我国社会的发展观联系起来,力图发掘出理论批判的现实力量。 相似文献
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Clouds and Hazes of Venus 总被引:1,自引:0,他引:1
Dmitrij V. Titov Nikolay I. Ignatiev Kevin McGouldrick Valérie Wilquet Colin F. Wilson 《Space Science Reviews》2018,214(8):126
More than three decades have passed since the publication of the last review of the Venus clouds and hazes. The paper published in 1983 in the Venus book summarized the discoveries and findings of the US Pioneer Venus and a series of Soviet Venera spacecraft (Esposito et al. in Venus, p. 484, 1983). Due to the emphasis on in-situ investigations from descent probes, those missions established the basic features of the Venus cloud system, its vertical structure, composition and microphysical properties. Since then, significant progress in understanding of the Venus clouds has been achieved due to exploitation of new observation techniques onboard Galileo and Messenger flyby spacecraft and Venus Express and Akatsuki orbiters. They included detailed investigation of the mesospheric hazes in solar and stellar occultation geometry applied in the broad spectral range from UV to thermal IR. Imaging spectroscopy in the near-IR transparency “windows” on the night side opened a new and very effective way of sounding the deep atmosphere. This technique together with near-simultaneous UV imaging enabled comprehensive study of the cloud morphology from the cloud top to its deep layers. Venus Express operated from April 2006 until December 2014 and provided a continuous data set characterizing Venus clouds and hazes over a time span of almost 14 Venus years thus enabling a detailed study of temporal and spatial variability. The polar orbit of Venus Express allowed complete latitudinal coverage. These studies are being complemented by JAXA Akatsuki orbiter that began observations in May 2016. This paper reviews the current status of our knowledge of the Venus cloud system focusing mainly on the results acquired after the Venera, Pioneer Venus and Vega missions. 相似文献
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殷荣 《西安航空技术高等专科学校学报》2008,26(6):23-24
通过对世界各国辩诉交易制度的分析,指出了辩诉交易中的共同点和不同点,以期对我国借鉴这一制度的合理成分,为我所用有所裨益。 相似文献
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提出了一种基于贝叶斯分类算法的分布式拒绝服务攻击防御技术。利用贝叶斯分类算法来计算数据包的分值特征,按照分值表对数据包进行评分并映射成危险等级。然后对危险等级进行评估,根据不同危险等级对网络流量进行过滤。基于该防御技术,设计并实现了防御系统。通过实验分析,该系统在DoS/DDoS攻击发生时能有效区分正常流量与异常流量,从而实现对DoS/DDoS攻击进行实时防御。 相似文献
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随着国际形势的缓和,美国国防工业及半导体制造业发生着微妙的变化,于是美国防部果断地提出军杯改革。面对这种情况,国内机载计算机造型、指令系统结构标准的制定和选择目前变成一个热门话题。本文介绍了几种典型的32位计算机指令系统结构标准和美国此方面的应用现状和特点,给出了机载计算机指令系统结构标准确定的可行性与途径。 相似文献
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根据美国导弹防御系统(NMD)的防御特点,对弹道导弹突防的战略技术进行简要评估,分析了弹道导弹突防采用不同弹头、释放有源或无源干扰物、隐身和反探测、助推段机动及旋转导弹等技术。 相似文献
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Monopulse radars have played an important role in air and missile defense systems since the development of the monopulse technique in the late 1940s. This paper outlines the application of monopulse radars in Russian defense systems, starting with the Moscow ABM system and continuing in instrumentation and air defense radars now widely deployed in Russia and elsewhere 相似文献
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In 1983 the NSIA sponsored the first Integrated Diagnostics National Conference. The major finding from this Conference was the lack of integration of those technologies which are part of the diagnostic process. Since that time, much has been done to implement the concept of integrated diagnostics. The NSIA has produced a baseline report on the implementation of the concept. This was followed by a series of Service programs aimed at implementation. The Office of the Secretary of Defense considers solutions to the diagnostic problem to be one of its major R&D goals. This paper discusses the progress made during the last three years on the implementation of integrated diagnostics. The paper also discusses the author's ideas on where the program is going. 相似文献