一种天线罩结构的设计分析

针对天线罩对天线电性能的影响问题,提出采用天线的驻波参数来评价天线罩性能的新途径。在采用微波网络理论对天线罩进行分析的基础上来选定具体形式的天线罩。利用矩量法对选定的U形天线罩进行了研究,得出了天线罩的宽度、高度及厚度在不同频率下与天线驻波的关系。通过设计出符合要求的天线罩证明了算法的有效性。     

基于远场的薄壳式天线罩壁厚修磨量反求方法

复杂的成型工艺使得机载弹载天线罩罩体各处的材料介电常数往往不一致,这将影响带罩天线系统的电性能,需要通过修磨罩壁几何厚度来补偿材料介电常数偏差的影响。提出了一种基于远场的天线罩壁厚修磨量的反求方法,根据带罩天线的远场计算公式,建立了求解罩体各处透射系数的反演模型,然后根据透射系数以及天线罩的外形、厚度等已知信息反求出各处的介电常数值,再按照电厚度一致的原则确定出壁厚修磨量。此外又提出了一种不增加天线罩网格数的近场积分网格细化方法,提高了反演模型的精度。最后对某1.2 m口径正切卵形天线罩进行了数值仿真,结果验证了所提方法的正确性和有效性。     

带罩天线远场仿真中有效等效源的确定

采用平面波谱～表面积分法或口径积分一表面积分法计算带罩天线远场特性时,都需要把天线罩表面作为等效辐射源,等效源的确定直接影响到算法的精度和效率.通过对天线近场分布特性的分析,提出一种通用于多种外形天线罩的确定有效等效源的实用方法:在采用三次样条函数理论,为多种流线形天线罩建立具有统一数学表达式的天线罩外形方程的基础上,建立以天线口径中心为顶点的天线辐射锥面,把包含在锥面内部的罩体表面作为有效等效源.仿真结果与试验结果相比较,表明该等效源确定方法的正确性.     

天线罩远场方向图的一种数值仿真方法

在分析天线罩综合电性能数值仿真方法基础上,结合平面波谱-表面积分法和样条函数理论,探讨了天线罩远场方向图的数值仿真方法.并根据加工后的天线罩实测数据,对其进行了实例计算,获得了较好效果.同时还重点讨论了由天线方程和天线罩曲面方程所确定的天线罩表面积分的积分区域的计算方法.     

关于气动力控制寻的导弹雷达天线罩引起的脱靶距离

本文介绍了关于气动力控制寻的导弹雷达天线罩引起的脱靶距离的分析。文中对导弹制导系统的稳定性作了分析并研究了稳定性与脱靶距离的关系,还阐述了脱靶距离的无量纲曲线与一些重要参数,从而证明有可能在天线罩设计与气动力设计之间进行一些折中。为保证气动力设计与天线罩设计之间的适当平衡和保证系统能在实际碰到的参数允许范围内工作,在初步设计中这些折中是非常重要的。     

地面雷达天线罩概述

地面雷达天线罩已广泛应用于各种雷达、卫星通信、射电天文、太空通信等各种天线。 天线罩的研制开始于五十年代。仅美国太空电子公司和爱尔兰的埃斯可科林斯有限公司(ESSCO),从六一年到现在已经生产天线罩六百多座,遍及世界各地。再加上各国自行制造的就更多了。 本文着重介绍八○年在北京举办的“爱尔兰技术周”座谈会上有关雷达罩的讨论情     

机械扫描天线电磁计算与距离像特征分析

针对主动雷达导引头对防空导弹武器系统制导雷达站检测与识别的需求,研究了机械扫描天线电磁散射特性的计算方法,并对其距离像特征进行了分析。首先采用图形电磁计算法对反射面天线的电磁散射特性进行了建模和计算,然后利用其宽频带雷达散射截面计算数据合成天线的一维距离像,进而对不同姿态下天线的距离像特征进行了分析。结果表明,由于天线的旋转,距离像序列的强度、宽度和位置呈现周期性的变化规律,从而为采用距离像序列对机械扫描天线进行识别以及对旋转周期和尺寸等参数的估计提供了可能。     

波束折射模型在天线罩补偿中的应用

导引头天线罩的流线型结构对天线阵列造成了能量损失、角度检测误差等电磁性能方面的影响, 给制导性能带来严重损失。本文利用电磁波折射理论建立了波束指向偏移模型, 通过数学公式推导验证了该模型的合理性, 为角度检测误差补偿提供了理论基础。波束偏移理论和相控阵天线阵列测角原理的结合定位了阵列在有天线罩时检测角所对应的最大波束指向角度, 提升了相对于无天线罩时检测角误差的准确性。实验数据表明，所提方法所得到的误差角度补偿表将阵列角度检测误差从1°降低到可接受的0.1°以下的误差范围, 验证了该方法的创新性和先进性。     

新型毫米波微带天线H槽耦合馈电设计

针对毫米波段微带天线频带窄,馈电对天线辐射影响严重等缺点,提出了一种新型天线单元结构.该单元采用H型槽耦合馈电和增加寄生贴片的方法,实现了天线带宽的增加.此方法可使得带宽达到11%(VSWR<2).通过采用多层寄生贴片对单元进一步改进研究,验证了该单元具有进一步展宽带宽和作为天线罩保护天线的作用,天线的带宽可达到22%.     

关于减小天线罩瞄准误差的补偿方法的研究

天线罩是保护天线在恶劣环境下能够正常工作的一种装置,由于制造工艺、材料等因素的影响,其电性能指标往往难以满足设计要求,必须采取补偿措施。在分析了瞄准误差产生原因基础上,探讨了主要的补偿方法,并提出了减少瞄准误差的一种新方法—内廓面修磨法。     

The 12th International Conference on Service Systems and Service Management ICSSSM'15

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Enterprise resource planning implementation decision & optimization models

To study the uncertain optimization problems on implementation schedule, time-cost trade-off and quality in enterprise resource planning (ERP) implementation, combined with program evaluation and review technique (PERT), some optimization models are proposed, which include the implementation schedule model, the timecost trade-off model, the quality model, and the implementation time-cost-quality synthetic optimization model. A PERT-embedded genetic algorithm (GA) based on stochastic simulation technique is introduced to the optimization models solution. Finally, an example is presented to show that the models and algorithm are reasonable and effective, which can offer a reliable quantitative decision method for ERP implementation.     

A calculus for services innovation

Innovation in the services area - especially in the electronic services （e-services） domain - can be systematically developed by first considering the strategic drivers and foci, then the tactical principles and enablers, and finally the operational decision attributes, all of which constitute a process or calculus of services innovation. More specifically, there are four customer drivers （i.e., collaboration, customization, integration and adaptation）, three business foci （i.e., creation-focused, solution-focused and competition-focused）, six business principles （i.e., reconstruct market boundaries, focus on the big picture not numbers, reach beyond existing demand, get strategic sequence right, overcome organizational hurdles and build execution into strategy）, eight technical enablers （i.e., software algorithms, automation, telecommunication, collaboration, standardization, customization, organization, and globalization）, and six attributes of decision informatics （i.e., decision-driven, information-based, real-time, continuously-adaptive, customer-centric and computationally-intensive）. It should be noted that the four customer drivers are all directed at empowering the individual - that is, at recognizing that the individual can, respectively, contribute in a collaborative situation, receive customized or personalized attention, access an integrated system or process, and obtain adaptive real-time or just-in-time input. The developed process or calculus serves to identify the potential white spaces or blue oceans for innovation. In addition to expanding on current innovations in services and related experiences, white spaces are identified for possible future innovations; they include those that can mitigate the unforeseen consequences or abuses of earlier innovations, safeguard our rights to privacy, protect us from the always-on, interconnected world, provide us with an authoritative search engine, and generate a GDP metric that can adequately measure the growing knowledge economy,     

THE 8~(th) INTERNATIONAL CONGRESS ON INDUSTRIAL AND APPLIED MATHEMATICS

正August 10-14,2015Beijing,China The International Congress on Industrial and Applied Mathematics(IClAM)is the premier international congress in the field ofapplied mathematics held every four years under the auspices ofthe International Council for Industrial and Applied Mathematics.From August 10 to 14,2015,mathematicians,scientists and entrepreneurs fiom around the world will gather in Beijing,China for the 8th IClAM to be held at     

论生物系统中的功能不守恒性

根据能量守恒定律，能量一次转换所做的总功应等于输入的总能量。但在生物系统中，能量的转换是多次的，其总功之和大于系统输入的总能量，此现象称之为功能不守恒性。能量转换效率越高，功能差别越大。能量通过细胞水平的多次转换，总功可提高至2倍左右。能量通过生态系统水平多次转换，总功可提高至1．4倍左右。通过系统内各子系统能流之和称为序能，反映了系统有序性大小，它取决于系统输入总能量和能量转换效率。根据序能原理，用GDP^2／9(GDP为国内生产总值，Q为能量总输入)反映人类社会功能和效率，要比单纯用GDP更客观。绿色GDP应同时考虑使GDP^2／Q增长最大和使自然生态系统的序能最大。人的经济行为和动物的行为对策也符合序能原理。     

Dealing with Human Relations in Chinese Systems Practice

This paper is about the Wuli, Shili, Renli (WSR) systems methodology. An important concept within this, Renli, has been developed from Confucian philosophy to clarify to Chinese researchers the necessity of dealing with human relations in systems practice. At present, the only formal means of operationalizing Renli that people are exploring in China is to import from the West methods for organizing debate. However, the concept of Renli suggests that more is needed than methods alone. In particular, facilitation skills are required. It is argued that the development of facilitation skills can be enhanced if researchers can gain both theoretical and practical knowledge of group dynamics, and engage in activities of self-reflection to look at, and alter, their own roles in these dynamics and the wider sociopolitical system. There are therefore three aspects to Renli: the use of systems methods for organizing debate, the acquisition of facilitation skills, and self-reflection geared toward the development of facilitation skills and enhanced critical awareness of the politics of intervention.     

云环境中邮件服务器面向传输的优化设计

随着云计算的发展,新的应用不断涌现,但电子邮件服务依然占有着重要的地位.邮件服务器是一种I/O密集的应用.在云计算时代,越来越多的用户邮件保存在服务器端,邮件在从客户端传输到服务器端之前,邮件或者邮件的部分内容在服务器端可能已经存在.基于这种现象,提出了一种方案,通过引入计算的代价来降低通信量,从而提高邮件服务器的处理能力.对电子邮件的格式和SMTP协议进行了扩充,引入了附件和正文分离传输的模式.在邮件传输时,客户端先计算附件的散列值,并作为正文的一部分传输到服务器端,服务器端再根据散列值来判断附件是否需要传输.     

金工工艺的优化设计

运用价值工程与运筹工程理论, 在金工工艺单项设计指标优化的基础上, 对其设计指标也进行了全面优化。     

THE 8~(th) INTERNATIONAL CONGRESS ON INDUSTRIAL AND APPLIED MATHEMATICS

正August 10-14,2015Beijing,ChinaThe International Congress on Industrial and Applied Mathematics(ICIAM)is the premier international congress in the field of applied mathematics held every four years under the auspices of the International Council for Industrial and Applied Mathematics.From August 10 to 14,2015,mathematicians,scientists