基于原子范数的MIMO雷达发射波形设计方法

针对现有多输入多输出(MIMO)雷达发射波形设计方法存在运算量高的问题,该文提出一种基于原子范数的MIMO雷达发射波形设计方法。根据原子范数的信号模型,该算法首先选择一个具有特殊结构的发射滤波器组以及一组正交信号,将MIMO雷达发射波形设计问题转化为原子范数最小化问题,然后采用半正定规划(SDP)对原子范数进行求解,得到(半)正定Toeplitz矩阵,并对其进行范德蒙分解实现发射滤波器组的估计,最后综合发射滤波器组与正交信号获得MIMO雷达的发射波形。理论分析与仿真结果表明,该算法满足等能量发射准则以及小的峰均功率比(PAPR)。同时,该算法相比于现有算法有较低的运算量以及良好的匹配性能。     

MIMO雷达分组正交波形集优化设计方法

在现代电子对抗中,数字射频存储(DRFM)设备能够快速截获机载脉冲多普勒雷达信号,能够实现对多输入多输出(MIMO)雷达的干扰。MIMO雷达可基于多组相互正交的波形集来对抗DRFM干扰。同时,为最大化MIMO雷达波形分集增益,每个脉冲内发射的波形也需要正交。为了平衡组内和组间的正交性,文中建立了一种分组正交波形集优化模型,其目标函数为组内和组间相关函数性能评估指标值的加权和;为了求解该优化问题,提出了一种分组正交波形集设计方法。所提方法将原优化问题简化为p-范数优化问题,基于MM算法导出了最小化目标函数的迭代求解表达式。仿真结果表明,所提方法可通过改变权重系数来灵活平衡MIMO雷达的干扰抑制性能和距离压缩性能。     

MIMO雷达不完全正交波形下的DOA估计算法

当前多输入多输出(MIMO)雷达的波达方向(DOA)估计算法都是在各发射阵元的发射信号间完全正交(POWS)的条件下提出的.当发射信号正交性无法满足时,DOA算法的估计性能会出现明显衰减.针对发射信号不完全正交(Non-POWS)时的DOA估计问题,文中提出了基于修正矩阵转换的MIMO阵列降维Root-MUSIC算法....     

基于幺模矩阵的MIMO雷达正交编码信号设计

针对MIMO雷达发射正交波形的要求,提出一种基于幺模矩阵的MIMO雷达信号设计的方法,该方法采用循环迭代算法,设计产生一组幺模的正交相位编码信号,通过仿真实验表明,由此算法设计信号波形具有较低的相关峰值旁瓣电平(PSL)和归一化的互相关峰值(CP)、支持更长的发射信号码长及良好的多普勒分辨率。且此算法具有收敛速度快、性能稳定、运算量低的特点。     

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。     

基于SQP 算法的MIMO 雷达波形设计与工程实现

为了有效利用MIMO 体制雷达的波形分集能力,需要对雷达发射波形进行正交性设计,从工程实现 的角度出发,针对MIMO 雷达发射信号的正交性要求,利用序列二次规划方法设计正交相位编码信号波形。通过仿 真分析,重点研究了信号数量、码长对波形正交性能的影响以及波形与雷达发射方向图之间的关系,验证了该方法 的有效性和优异性,并与经典的遗传算法进行了仿真比较,最后依托波形产生系统完成了波形的工程实现,并且成 功应用到了雷达系统中。结果表明,采用该方法能够获得较低的自相关旁瓣峰值和互相关峰值,设计出符合雷达系 统要求的正交波形。     

集中式多输入多输出雷达多功能波形优化设计

针对集中式多输入多输出(MIMO)雷达波形设计中多个设计目标同时优化的问题,基于交替投影的思想,该文提出一种以任意维迭代谱逼近算法(ADISAA)为基础的波形设计框架,通过可调的权重来协调发射方向图匹配、良好的相关特性和频谱凹口等多种功能的波形设计目标,最终实现恒模波形设计。仿真结果表明,相对于已有的算法,在发射方向图匹配的基础上,该算法改善了发射波形在指定区间的相关特性,同时通过频谱凹口的设计避开了受到色噪声和有源干扰污染的频段,算法的计算复杂度更低。     

MIMO雷达正交混沌调频波形集设计

正交波形设计是实现MIMO雷达的关键技术之一,目前正交波形设计方法主要多采用统计优化算法,如模拟退火、遗传算法等,此类方法主要缺点是算法耗时长、效率低,且所设计的波形集性能随着波形个数的增加而下降,针对此问题,提出一种基于混沌调频的MIMO雷达正交波形集设计方法,采用混沌调频信号作为MIMO雷达的发射波形,利用混沌序列良好的统计特性,无需寻优处理即可得到性能优越的正交波形集,且理论上可以得到任意数目的波形而不损失波形集性能,因此,该方法在算法效率和波形多样性方面具有优势,计算机仿真实验验证了设计方法的有效性。      

基于随机步进频信号的MIMO波形设计和成像方法

基于MIMO雷达系统的宽带雷达成像是空间感知领域一个很有前景的研究方向.波形设计是宽带MIMO雷达系统需要解决的首要问题.对于MIMO宽带信号一般要求各雷达发射信号相互正交且自相关函数具有窄的主瓣和低旁瓣特性.文中详细分析了随机步进频信号自相关函数的统计特性,证明大的步进频数利于MIMO雷达成像,进而提出了一种基于遗传算法的MIMO波形设计方法,该算法中利用随机频率编码矩阵生成遗传算法的初始种群.最后将所设计的波形用于MIMO雷达成像的仿真实验,其结果证明了文中的波形设计方法可以有效降低MIMO雷达系统中不同通道之间的相互干扰,利于雷达成像.     

MIMO雷达正交相位编码信号设计及分析

针对MIMO雷达发射正交波形的要求,提出一种采用相位编码设计MIMO雷达信号的方法。该方法采用遗传优化算法,设计产生一组正交相位编码信号,并分析该组信号的自相关和互相关特性。文章最后分析了采用正交相位编码信号设计MIMO雷达信号存在的一些问题。     

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.     

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.     

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.     

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.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

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.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.