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1.
为解决机翼翼尖等弱散射源所带来的雷达散射截面(RCS)贡献问题,针对典型机翼设计了几种不同的机翼翼尖方案,建立了典型翼尖数值模型。利用基于多层快速多极子算法(MLFMA)的FEKO软件,计算、分析不同方案翼尖外形在不同频段、不同方位角下的RCS量级,并优选出对机翼RCS贡献最低的翼尖外形方案。计算结果表明,针对典型机翼,从翼尖到翼根方向上15%处顺气流直切的翼尖外形方案,其翼尖尖点所带来的RCS贡献最小。  相似文献   

2.
针对空间卫星目标的雷达散射截面(RCS)预估问题,提出了一种基于Kd-tree射线追踪法的 改进物理光学(PO)方 法,实现了对具有较强耦合结构的卫星目标电磁特性计算。基于卫星目标的三维面元模型, 建 立了其对应的Kd-tree空间分割描述结构,将其用于射线追踪,结合PO方法就可以得到给定 模型的RCS预估值。数值计算结果表明,改进方法和MoM方法相比,具有相同计算精度但计算 效率高得多,相比单纯PO方法,改进方法也更接近测量值。  相似文献   

3.
针对空间探测任务中采用雷达散射截面积(RCS)序列估计卫星旋转周期存在的问题,建立了基于多频段RCS的卫星自旋周期估计分析模型。根据卫星的外推弹道,计算了卫星的可跟踪弧段,推导了自旋模式下卫星本体坐标系下电磁波入射角的计算公式。采用电磁场数值算法快速计算卫星的RCS,通过RCS匹配获得卫星可跟踪弧段的理论RCS序列,研究了自旋周期在RCS序列中的表现形式。仿真分析了雷达频段、采样率及弧段选择对周期估计的影响,结果表明入射角序列相对于垂直于卫星自旋轴方向变化平稳的弧段,RCS序列呈现的周期性特征显著,利用该类弧段进行卫星自旋周期估计可以得到准确的结果,证明该方法可以应用于卫星自旋周期估计。  相似文献   

4.
本文首先讨论并分析了各种插值DFT(离散傅里叶变换)算法,然后提出了一种实正弦信号的快速插值频率估计方法。该方法只需 3个DFT变换系数的实部构造频率修正项,计算量低,具有精度高、测频速率快的特点。计算机模拟和FPGA仿真均证实了该方法的有效性。  相似文献   

5.
针对在阵元数多、分辨率要求高的情况下,基于均匀圆阵的空间谱直接计算方法存在计算量大、实时性差的缺点,利用循环矩阵、离散傅里叶变换、卷积运算之间的内在联系,提出了一种快速空间谱计算方法。仿真结果表明,在保持测向性能完全一致的情况下,所提快速算法降低空间谱计算过程中角度搜索阶段的计算量随阵元数增加而增加;且在相同计算量条件下,所提快速算方法可以用于更高精度和分辨率的角度搜索。  相似文献   

6.
在雷达目标跟踪中,系统量测信息通常在球坐标系下获得。为了采用经典卡尔曼滤波算法实现有效目标跟踪,通常采用量测转换方法将非线性量测信息转换到直角坐标系中。针对传统量测转换方法基于量测值计算转换误差统计特性而导致的估计结果有偏问题,提出了一种基于预测值的量测转换方法,并将其与卡尔曼滤波算法相结合,获得了一种基于预测值量测转换的卡尔曼滤波跟踪算法。仿真结果表明,与现有的基于量测转换的卡尔曼滤波算法相比,该算法能在不提高运算量的情况下有效改善目标跟踪效果,跟踪精度提升约20%。  相似文献   

7.
多重信号分类(Multiple Signal Classification,MUSIC)法在估计多信号频率时需要对采样数据序列的自相关矩阵进行特征值分解,并准确划分出信号和噪声子空间,使得其计算量比较大。利用自相关矩阵的Toeplitz特性快速计算其逆矩阵,通过计算逆矩阵的多次幂来逼近噪声子空间,避免了MUSIC法的特征值分解和估计信号个数的过程。在谱峰搜索环节,采用先粗估计频率值再在小区间进行精细搜索的策略,能够避免搜索无用的频率范围。计算量比较分析以及与理论克拉美罗界(Cramer-Rao Bound,CRB)的对比验证结果表明,快速方法性能与MUSIC法相当,能够较好地逼近CRB,且计算量更小,适合实时性要求高的应用场合。  相似文献   

8.
涂敷雷达吸波材料(RAM)是目前最为常用的一种减缩雷达散射截面(RCS)的方法 ,可以在全角度下减小雷达目标的RCS值。采用非均匀有理B样条(NURBS)参数曲面模拟目 标外形,运用物理光学法计算电大尺寸部分涂敷目标的RCS。结果显示,在目标一定的部位 上 而不是在所有部件上涂敷吸波材料,在一定的观察点上仍然能起到减小RCS的作用,既满足 了角度范围的需要又节省了RAM的使用费用。  相似文献   

9.
针对航天发射场测控设备操作人员使用常规训练手段与实际操作环境差距较大的问题,提出了一种较为实用的无人机模拟训练方法。利用实际任务中获取的真实测量数据生成训练任务,由无人机搭载相关任务载荷执行,并结合发射场已有的测控设备来跟踪无人机完成模拟训练。通过对无人机的飞行航路模拟和任务载荷测量信号的动态模拟,可为参训人员提供接近实战的训练环境。仿真结果表明,该方法可实现与真实测量数据极为接近的模拟训练数据,因而参训人员通过模拟训练中获得的训练效果与实战基本一致,在提升了训练的真实性和针对性的同时,可有效提高操作人员的综合操作能力。  相似文献   

10.
在多目标情况下,统计多输入多输出(MIMO)雷达需要对不同观测通道中估计出的目标参数 进行配对,才能完成多个目标定位及其速度估计 。针对这一问题,对统计MIMO雷达提出了一种映射搜索配对法来实现在不同观测通道中的目 标距离延时和多普勒频率估计值的配对,从而获得目标位置及其速度估计值。仿真结果表明 ,该方法在目标雷达散射截面(RCS)闪烁情况下能对多个目标进行有效定位和速度估计。  相似文献   

11.
Holding 88 percent of train media resources across China, based on "Time Cube", on the 2008 Intermedia Recommendation and Introduction Meeting on December 19, 2007, HTC announced its high-profile strategy of tour marketing and tapping the immeasurable potentials on the train. Meanwhile, HTC officially launched its brand new product Olympic Train on the meeting, providing a fabulous platform for all the brands that are prepared to do a smart marketing on the occasion of 2008 Olympic Games.  相似文献   

12.
In the end of 2007, Air China Limited (hereinafter "Air China") and Shanghai Airlines, formally joined Star Alliance at a ceremony held in the new Terminal Three at Beijing Capital International Airport. With the addition of the two Chinese airlines, Star Alliance now has 19 member carriers operating 17,000 daily flights to 897 destinations in 160 countries.  相似文献   

13.
Under the guidance of the theme slogan of the 29th Olympic Games - One World One Dream, with dream, love and dedication as its theme, the 2008 Music Grand Ceremony & 1000 People Charity Concert on 100 days cotmtdown to Paralympic Gamesis officiaily launched on December 22, 2007. The 2008 Music Grand Ceremony is sponsored by China Disabled Persons' Federation, and co-hosted by National Paralympic Committee of China,  相似文献   

14.
MUYANG GROUP     
With its headquarters in the historic city of Yangzhou,Jiangsu Muyang Group Co.,Ltd has since its founding in 1967 grown into a well-known group corporation whose activities cover research & development,project design,manufacturing,installation and services in a multitude of industries including feed machinery and engineering,storage engineering,grain machinery and engineering,environmental protection,conveying equipment and automatic control systems.  相似文献   

15.
Aseries of events that occurred in October 2007, are rewriting the history of China's energy industry: November 3 an Energy Law Committee asked the public for suggestions on improvements; forty top experts came together to form the National Energy Expert Advisory Committee on November 6; and the National Oil Reserve Center (NORC)became the nerve centre of oil reserves on November 18. Yet, behind the progress of these recent activities remains the fact that international oil prices still hover around a very high price of US$ 90/barrel, and China's oil imports are close to accounting for half of its total oil reserves.  相似文献   

16.
2007 China Harbor Ten People elected the entrepreneurs who contributed a lot to port economy and enterprises this year trough their talent management.These ten people embody their social responsibility,professional skills,creative ability,and charming personality.Bearing full confidence in China's port economy,the port entrepreneurs are brave enough to explore a brand new area,so as to promote harbor economic development. At the very beginning of 2008,China Shipping Website,Dalian Maritime University,and China Port and Shipping In- stitute jointly select the 2007 China Harbor Ten People,demonstrate port entrepreneurs' stunning minds,disclose their secrets to success,and providing abundant experiences to others in harbor development.The top ten people are various excellence during the ups and downs harbor development.  相似文献   

17.
Since the normalization of the diplomatic ties between China and ) Japan, the bilateral economic relations have deepened continually. According to the statistic of Japan, China passed U.S. to become Japan's top trade partner as well as is the second largest export market for Japan and is the largest import resource for Japan. Japan companies such as Mitsui, Sumitomo, Sony and Panasonic, have set the subsidiaries in China and explored their scales. This year 2008 marks the 30th anniversary of the signing of the ChinaJapan Treaty of Peace and Friendship.  相似文献   

18.
China's textile and apparel industry suffered an unprecedented cold market for exports in the first quarter this year,the result of a few factors including: the appreciating RMB, decreasing export rebate rate,expanding influence of the U.S. subprime crisis, increasing costs of production and rising labor cost.  相似文献   

19.
The May 12 earthquake in Sichuan caught Chinese people by surprise and took the nation's heart. While mourning the dead and searching for the missing, many services must be provided for the survivors in the wake of the earthquake. Available post-quake financial services have become an important part of the reconstruction effort in the disasterstricken areas of Sichuan province.  相似文献   

20.
Aristotle saw ethics as a habit that is modeled and developed though practice. Shelly's Victor Frankenstein, though well intentioned in his goals, failed to model ethical behavior for his creation, abandoning it to its own recourse. Today we live in an era of unfettered mergers and acquisitions where once separate and independent media increasingly are concentrated under the control and leadership of the fictitious but legal personhood of a few conglomerated corporations. This paper will explore the impact of mega-media mergers on ethical modeling in journalism. It will diagram the behavioral context underlying the development of ethical habits, discuss leadership theory as it applies to management, and address the question of whether the creation of mega-media conglomerates will result in responsible corporate citizens or monsters who turn on their creators.  相似文献   

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