基于协方差矩阵重构的阵元失效MIMO雷达DOA估计

在实际应用中由于恶劣环境或人为干扰等因素而导致多输入多输出(Multiple-Input Multiple-Output,MIMO)雷达部分阵元失效,使得其接收数据缺失及其协方差矩阵秩亏,从而导致子空间类算法的波达方向(Direction of Arrival,DOA)估计性能恶化甚至完全失效。针对上述问题,提出了一种接收阵元失效下基于协方差矩阵重构的MIMO雷达DOA估计方法。该方法根据MIMO雷达协方差矩阵中以接收阵元数划分的子方块矩阵具有Toeplitz特性,利用正常工作接收阵元的协方差矩阵元素来恢复相应的缺失元素,从而重构出完整的数据协方差矩阵,提高阵元失效MIMO雷达的DOA估计性能。仿真结果验证了所提方法的有效性。     

一种最小冗余线阵的目标DOA估计方法

针对目标波达方向(DOA)估计的子空间类算法工程实现上的问题,提出了一种次最小冗余线阵的目标DOA估计方法。该方法应用孔径合成理论和最小冗余线阵理论,在保证阵列孔径等价的前提下,从工程应用的实际问题出发,对次最小冗余线阵的阵元配置进行研究。在分析MUSIC及MMUSIC算法的基础上,对次最小冗余线阵进行仿真。通过与相同孔径的均匀线阵和最小冗余线阵对比表明,次最小冗余线阵与相同孔径的均匀线阵性能相仿,并有更小的计算复杂度,比最小冗余线阵有更大的阵元灵活性,可以解决一般最小冗余线阵不能解决的相干信源的DOA估计问题。     

采用降秩多级维纳滤波器的二维DOA估计快速算法

针对双平行线阵的二维波达方向（DOA）估计问题,为有效降低计算复杂度,提出了一种基于降秩多级维纳滤波器（MSWF）的快速算法。首先利用MSWF的前向递推实现信号子空间的快速估计,无需估计协方差矩阵和特征分解;然后,通过MUSIC算法对方位角和俯仰角的估计进行分维估计,使二维DOA估计退化为两个一维DOA估计问题,且方位角和俯仰角自动配对,进一步降低了运算量。仿真结果表明,该方法的估计精度优于同样基于双平行线阵提出的波达方向矩阵法（DOAM）,俯仰角兼并时同样适用,计算复杂度低,适用于实时性要求高的应用背景。     

基于压缩感知DOA估计的稀疏阵列设计

根据格拉姆(Gram)矩阵优化测量矩阵的方法，给出了一种基于压缩感知波达方向（DOA）估计的均匀线阵的稀疏阵列设计方法。该方法不需要对阵列的输出数据进行压缩采样，直接利用稀疏阵列的输出数据，然后利用稀疏恢复算法求解DOA估计信息。实验仿真证明，相比于原均匀线阵，所提方法在阵元数目较少且信噪比较低的情况下具有更好的DOA估计性能。     

基于稀疏非均匀COLD阵列的极化信号DOA估计

基于稀疏非均匀COLD(concentered orthogonal loop and dipole)阵列,提出了一种极化信号的DOA(direction-of-arrival)无模糊估计算法.该算法利用了稀疏非均匀COLD阵列的阵元数少和孔径大等特点,因而在阵元数目一定的情况下,可获得较高的DOA估计精度.由于稀疏非均匀COLD阵列可分成电磁环和偶极子两个子阵列,通过分析每个子阵列DOA估计的模糊性,给出了整个稀疏非均匀COLD阵列不发生DOA估计模糊的条件.通过计算机仿真证明了该算法的有效性.     

一种改进的基于传播算子的二维DOA估计算法

针对面阵中的波达方向估计算法复杂度过大的问题,提出了一种改进的基于传播算子的二维面阵波达方向（Direction of Arrival,DOA）估计算法。该改进算法基于面阵平移不变性质,将原始子面阵在X和Y轴上分别平移得到两个子面阵,将两个子面阵相加得到虚拟子面阵,利用原始子阵和虚拟子面阵构造新的信号矢量,基于传播算子算法求出其特征值,特征值中的模值和相位值包含信源的二维角度信息,由此可求出自动配对的二维角度。与基于传播算子的二维DOA估计算法相比,该算法有效降低了运算复杂度,且保持性能相近。仿真实验验证了算法的有效性。     

基于提升小波算子的MUSIC法的DOA估计

在低信噪比且不增加接收阵元数目的条件下,提出利用提升小波算子对接收 信号进行预处理,然后用MUSIC法进行谱估计。仿真试验表明该算法有效提高了DOA估计的 分辨率和精度,与传统的基于一代小波域的DOA估计的算法对比,该算法具有复杂度低、收 敛快且精度高的性能,为实时信号的处理提供了支持,在科研和工程实践领域具有一定的 理论价值和应用价值。     

基于矩阵重构的非相干分布源参数估计方法

针对现有非相干分布源参数估计算法计算量大等问题,提出了一种新的DOA和角度扩展估计算法.该算法利用空间频率近似模型下的非相干分布源协方差矩阵的结构特点.协方差矩阵可分为相位信息矩阵和幅度信息矩阵.对相位信息矩阵进行重构,对重构后的协方差矩阵利用MUSIC等传统方法即可实现DOA的估计;对幅度信息矩阵的各主次对角线上的元素均进行平滑得到幅度信息平滑向量,估计得到的DOA代入幅度信息中即可得到角度扩展的估计,从而实现非相干分布源DOA和角度扩展分离估计.计算机仿真验证了算法的性能.     

分布式嵌套阵列及其DOA估计

提出了一种分布式嵌套阵列天线结构,由两个相互独立的四级嵌套子阵构成。两个子阵间存在一个基线长度,且满足一定条件。对该阵列天线接收到的信号进行高阶累积量和Khatri-Rao积运算可以得到三个完全相同的均匀直线阵列天线结构。针对新得到的阵列天线结构,使用基于空间平滑技术的双尺度酉旋转不变子空间（ESPRIT）波达方向（DOA）估计算法对信号进行DOA估计。该方法可以有效地提高阵列天线的自由度,进而达到提高估计精度的目地。仿真结果证明了基于所提出阵列天线结构的DOA估计方法的有效性。     

基于BPSK和MASK信号源特点的实值ESPRIT算法

在信号源为BPSK和MASK的情况下，提出了一种波达方向（DOA）估计方法。对于等距线阵上的接收数据，此算法根据信号源为实信号的特点，利用欧拉公式形成正弦和余弦数据，并将其加以串联，这相当于将阵元个数加倍，然后在此基础上运用ESPRIT类算法估计波达方向。由于正（余）弦数据为实值数据，所以本文提出的算法可以有效地将运算量减少到相同维数复值运算量的1／4。仿真实验表明新算法不仅估计精度高，而且能够处理的信号个数可大于阵元个数。     

Brown＇s Blossom in Britain-China

The overall strategic relationship between U.K. and China is ＂better than ever＂, China- Britain relations have maintained good momentum, with increased high-level exchanges and the reinforcement of strategic mutual trust, with more room for growth in the future.     

Challenge and Opportunity Go Hand in Hand——What Global Economic Agitation Brings to the China's Economy?

Domino effects of the global finance agitation As the origin of the subprime crisis,US financial institutions lost USS45 billion last year,accounted for over half of the total US,EU & Japan loss.Since January 15th,Chtigroup released its financial statement of the 4th quarter,showing a net deficit of USS9.83 billion,which marked the hisoric high of its quarterly deficit.     

Sinosteel：Extraordinary Moves in Industry Chess

Among the Fortune 500 firms,more and more images from China emerge out.On the 2008 list,Sinosteel Corporation,a landmark group of China industries quietly squeezes into the candidate line.As the largest steel service ＆ trade enterprise,its sales reached at RMB 111.24 billion,with a year-on-year increase of 83.03 percent,and the profit grew by 180.03 percent.On the Sinosteel 2008 Work Meeting,the president Huang Tianwen uttered,＂In the coming year,we will work for US$20 billion sales,and look forward to getting a position in Fortune 500 firms for ourselves.＂     

Walk Through Unusual Five Years—— An Exhibitor＇s Canton Fair Course

When the 103rd Canton Fair is approaching, an old friend of Canton Fair, Li Ying from Jiangsu prov-ince recollected his past five years＇ experiences to the grand trade meeting. Each year is special, with some unforgettable memories colored by the year.     

Jean-Pierre Duprieu： Willing to Be A Legate of Sino-French Business

Estaing, former French president, Valery Giscard d＇Estaing attended Sino-French Economic Seminar held in Shanghai in early April and said that the world center has shifted from the west to the east with many European and US companies entering into Asia, and China has the ability to play an important role in the world stage. Estaing, naming himself＂French Confucian＂, then said in Chinese that a cook-group includes 10 people in ancient Chinese soldier system and the cook is in charge of cooking for them. And people who belong to the same cook are actually ＂Partners＂.     

China''''s Stock Market Wave

The annual meeting of the World Economy Forum was held in Davos,a little town in Switzerland,on January 23rd to the 27th this year,with the theme"the Power fo Collaborative Innovation",over 2500 celebrates from ture political and cconomic circles of more than 80 countries and challengred logether to talk about the future of the global economy in 2008,A Forum for the problems and challenges that face whole world,some of the keywords which drew attention during the event were:the U.S.subprime mortgage crisis,soaring energy prices,the economic slowdown in the U.S.ermerging economic bodies,authority funds and the general unpredictable nature of the global economy.     

Trade Promotion from Neighborhood

If you are considering to trade with companies in Japan or expanding your .business to Japan, we are ready to help from the very beginning.＂ You will find this greeting at the first sight on the Chinese website of Japan External Trade Organization （JETRO）. JETRO has committed itself in delivering highly efficient and quality services to meet the demand of internal and external customs including Japanese companies, hence winning a good reputation in the international trade arena. In recent years, with its priority in advancing business cooperation in South and East Asia, JETRO has made great achievement in promoting trade between China and Japan. Therefore, China＇s Foreign Trade interviewed Mr. Yoichi Maine, Deputy Director General of JETRO BEIJING.     

Auto Parts Market Potential Coming into Surface

Looking at the increasingly fierce competition in the world auto market. global automobile manufacturing industry, taking Europe, the U.S. and Japan as representatives, is gradually forming a new type of relationship, mutual cooperation between whole vehicle and parts manufacturers. We can clearly see that auto parts manufacturers have become independent from the whole vehicle manufacturing companies, which means that the former structure of auto industry has greatly changed, and a new relationship,     

Domino Effect on Electricity and Coal Prices

In the middle of last December, the key purchase contracts for coal used in power generation in 2008 were signed, reflecting a demand for more than 1.085 billion tons. It is important to note that the country＇s five biggest power producers, China Huaneng Group, China Guodian Corporation, China Power Investment Corporation, China Huadian Corporation and China Datang Corporation, had settled on the prices on their purchase contracts, and they are expected to consume 290 million tons of coal for generating electricity,     

Slimmed May Day Holiday

Last November the State Council of China decided to renew its holiday system by reducing the seven-day May Day holiday to three days and introducing three new one-day public holidays, namely the Qingming Festival, Dragon Boat Festival and Moon Festival. By doing so, the three golden-week holidays that were introduced in 1999, namely the Spring Festival, May Day and National Day, could be better distributed.