多输入多输出雷达发射天线低旁瓣设计

多输入多输出(MIMO)雷达发射波形的多样性,为发射方向图设计提供了更多的自由度。针对阵元等功率条件下获得低旁瓣高增益发射波束的问题,提出了一种采用极小极大准则优化设计发射波形相关矩阵的方法,并将该约束优化问题转换为无约束优化问题,便于采用经典迭代法求解。仿真结果表明:采用极小极大准则设计的发射方向图旁瓣区域平坦,最高旁瓣电平接近理论最低值。最后采用循环(CA)算法,获得易于数字阵列系统实现的相位编码信号,使用该相位编码信号得到的实际发射方向图与理论结果匹配良好。     

任意波形相关性的机载MIMO雷达杂波建模与分析

为了分析任意发射波形相关性影响下的机载MIMO雷达杂波分布特性,从信号空间与阵元空间变换的数学角度构建了发射波形合成模型。在此基础上,提出了任意发射波形合成影响下的机载MIMO雷达杂波统一模型,论述了发射波形合成与杂波统一模型之间的关系。仿真揭示了统一模型下发射波形从全正交、相关到全相干的演变过程中杂波的分布特性。研究得出,发射波形互相关矩阵的结构决定了杂波谱展宽的程度,而该互相关矩阵的秩决定了杂波自由度大小。该模型为波形设计影响下的机载MIMO雷达STAP算法的设计提供了理论依据。     

发射波形合成下的机载MIMO雷达杂波统一模型

针对发射波形相关及非理想因素影响下的机载MIMO雷达杂波分布特性的问题,给出了理想情况下机载MIMO雷达杂波模型。利用信号集合及阵列导向矢量投影变换的原理,提出了基于波形合成的机载MIMO雷达杂波统一模型,分析了模型与理想MIMO雷达、相关MIMO雷达及相控阵雷达的统一关系。然后给出了多种非理想因素影响的误差矩阵,建立了非理想因素影响下的机载MIMO雷达杂波统一模型。最后仿真分析了波形相关及非理想因素影响下的MIMO雷达杂波特性,并得出结论:波形合成会产生子阵合成,当合成子阵间发射信号全正交,且合成子阵内各阵元发射信号全相干时,杂波谱的斜脊线最窄。该统一模型为机载MIMO雷达杂波特性分析及STAP算法设计提供了理论依据。     

机载相干MIMO雷达杂波自由度估计研究

针对任意发射波形合成结构影响下的机载相干MIMO雷达杂波自由度的估计问题。论文提出了一种机载相干MIMO雷达杂波自由度估计的构造法,该方法利用发射波形合成结构直接构造等效矩阵代替杂波协方差矩阵进行求秩。通过递推分解等效矩阵,提出并证明了一种杂波自由度快速估计准则,建立了机载相干MIMO雷达发射波形合成结构、阵列稀布构型与杂波自由度之间的定量关系。研究表明:该方法和准则能够准确预测任意发射波形合成结构下的机载MIMO雷达的杂波特征谱结构。该理论既保证了降秩STAP算法性能的最优又具有较小的计算量,并为最优发射波形合成方案和MIMO STAP算法的设计提供了依据。     

频分MIMO雷达波形捷变抗自卫式假目标干扰

针对频分MIMO雷达在自卫式欺骗干扰情况下,空域自适应波束形成算法无法有效抑制干扰的问题,提出了一种基于波形捷变的时域自卫式假目标干扰抑制方法.首先阐述了支援式主瓣假目标干扰抑制机理,指出其抗自卫式干扰的局限性;然后分析了波形捷变抗自卫式干扰的基本原理;最后对频分MIMO雷达在不同周期发射的正交信号波形进行了设计,使干...     

一种基于先验信息的机载MIMO雷达发射方向图设计方法

在非均匀杂波背景下,针对旁瓣杂波抑制问题,该文提出一种基于先验信息的机载多输入多输出(MIMO)雷达发射方向图设计方法。该方法利用目标和杂波在空域和多普勒域的2维先验信息,以最大化雷达空时匹配滤波后的输出信杂噪比(SCNR)为准则,建立关于发射信号相关矩阵的优化代价函数,并采用半正定规划(SDP)方法进行求解。仿真表明,在非均匀杂波背景下,采用该文方法优化设计的发射方向图可有效提高空时2维匹配滤波后的输出信杂噪比。     

MIMO雷达波形设计方法综述

MIMO雷达是一种新兴的有源探测技术,波形分集能力赋予MIMO雷达潜在的探测能力,使得波形设计成为一项重要研究内容.文中综述了MIMO雷达的波形设计方法,重点探究了正交波形设计、发射方向图匹配设计、发射信号波形合成等方法,并指出了MIMO雷达波形设计下一步的研究方向.     

一种MIMO雷达非高斯杂波中的信号分离方法

针对传统匹配滤波方法对非高斯相关杂波下MIMO雷达信号分离性能下降的问题,本文基于线性约束最小功率波束形成器原理,给出了一种适用于非高斯相关杂波条件下的MIMO雷达自适应信号分离算法。该方法将需要分离的发射信号以外的信号和相关杂波作为干扰,利用接收信号的分数低阶统计量在线性约束最小功率准则下导出了滤波器权系数,实现了非高斯相关杂波中对信号实时有效的分离。最后采用本文方法在SG-Alpha稳定分布杂波背景下进行了仿真实验,结果表明,本文方法可有效实现非高斯相关杂波中的MIMO雷达信号分离。      

MIMO雷达方向图与稀疏频率波形联合设计

发射方向图设计与波形优化是MIMO雷达领域的热点,随着研究的深入越来越需要考虑包括频谱特性在内的雷达系统工作环境特性。针对采用传统波形容易产生互相干扰的频谱拥挤情况,本文提出了一种MIMO雷达方向图与稀疏频率波形联合设计方法。一方面保证了将能量集中辐射到所感兴趣的区域上的探测性能,另一方面由得到的稀疏频率波形可以避免MIMO雷达系统与其他同频工作设备互相干扰。该方法首先根据MIMO雷达方向图与波形矩阵的关系,列出具有稀疏频率约束与恒模约束的目标函数式;然后通过从期望方向图到自相关矩阵,再到恒模稀疏频率波形的步骤,应用循环算法求解目标函数;最后所得结果波形的方向图接近期望方向图,同时结果波形具有稀疏频率特性和良好的自相关特性。仿真结果验证了文中方法的有效性。      

基于交替投影的MIMO雷达信号盲分离算法研究

多输入多输出（multiple-input-multiple-output,MIMO）雷达利用灵活的发射波形设计以及阵列配置,在微弱目标探测及高分辨参数估计方面有着巨大优势.为侦察识别MIMO雷达信号,建立了MIMO雷达信号侦察模型.基于最大似然估计以及交替投影算法,并利用MIMO雷达信号的恒模特性对MIMO雷达信号进行了盲分离.通过理论推导和数值仿真分析了所提算法分离MIMO雷达信号的性能.结果表明该算法在信噪比高于0dB时,其分离后的信号与原信号具有很高的相关系数,且分离指数较低,性能明显优于现有的非圆复信号Fast ICA（non-circular complex Fast ICA,NC-Fast ICA）算法.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks