MIMO雷达弱目标检测前跟踪算法

相比相控阵雷达,多输入多输出(MIMO)雷达发射功率密度低,在低信噪比条件下空间分集特性优势不明显,检测概率降低。针对此问题,提出了基于逐目标消除-动态规划的多目标检测前跟踪(TBD)算法。该算法先利用统计量筛选航迹点,对信号进行积累,在降低TBD运算量的同时,减小了噪声的积累;再采用逐目标消除的思想,克服了动态规划的航迹分叉和仅能处理单目标的缺陷,实现了多目标的有效检测。文中还推导了目标检测的虚警概率和检测概率,给出了检测门限与虚警概率的关系。复杂度分析和仿真表明,相比传统TBD算法,所提算法的运算量明显降低;相比传统MIMO雷达检测方法,在相同虚警概率和检测概率条件下,所提算法要求的信噪比降低了5 dB,有效提升了检测性能。     

基于高阶累积量的LPI雷达信号检测

低截获概率（LPI）雷达的广泛应用导致电子侦察系统难以从噪声中检测到LPI信号的存在。针对这一问题,提出一种基于多相滤波器组和高阶累积量联合处理的121雷达信号检测算法。该算法首先利用多相滤波器组实现信号在频域上的快速均匀划分,然后对输出的每个子带信号进行三阶累积量对角切片短时估计,有效抑制高斯噪声,并设计检测器对每个子带信号进行信号存在性检测,进而判断整个信号中是否含有有用信号。仿真结果表明,该方法的检测性能远优于传统的能量检测器,在信噪比大于-20dB时具有较高的检测概率。     

高速运动目标的积累检测研究

针对Ch irp雷达在低信噪比下对高速运动目标的有效积累检测问题,首先分析Ch irp雷达运动目标的回波特性,指出包络走动是影响高速运动目标相参积累性能的主要因素,然后提出用频分包络移位算法来解决该问题。MonteCarlo仿真实验表明,在信噪比-4 dB的条件下,采用该算法,对高速运动目标的检测性能可以达到在虚警概率为10-6时截获概率大于98%。     

基于包络插值移位补偿的高速运动目标的积累检测算法研究

本文针对Chirp雷达在低信噪比下对高速运动目标的有效积累检测问题,首先分析Chirp雷达运动目标的回波特性,指出包络走动是影响高速运动目标积累性能的主要因素,然后提出“基于包络插值补偿的相参积累”检测算法来解决这一问题。Monte Carlo仿真实验表明,在信噪比-8dB的条件下,采用该算法,对高速运动目标的检测性能可以达到在虚警概率为10-6时截获概率大于95%,证明了本算法的有效性。     

复杂背景下小目标恒虚警检测技术研究

为了实现复杂背景下的弱小目标恒虚警检测,提出了一种基于CEM算法的恒虚警探测算法.在分析CEM算法滤波处理结果分布规律的基础上,采用TM-CFAR方法选择恒虚警探测门限,并结合形态学方法克服了背景虚警概率曲线中的拖尾现象.以ETM数据为例进行了计算机模拟.结果表明,该方法在信干比为-5dB和虚警率为10-4的条件下,可以有效地检测出被探测目标.     

基于Duffing振子的机场异物自动判决算法

基于毫米波雷达的机场异物(FOD)检测技术具有高分辨率和低功耗的特点,但是传统恒虚警(CFAR)类检测算法在低信杂比(SCR)情况下虚警过高.该文提出一种基于Duffing振子的FOD检测算法.该算法首先利用杂波图CFAR检测算法将雷达接收机接收回波中的背景杂波初步分离,获得目标(包含虚警)的距离信息,并利用该信息构造Duffing方程,之后将此方程作为系统检测模型,输入接收回波信号,求解输出信号方差,采用方差极值法区分目标和虚警.仿真结果表明,在低信杂比情况下,即使虚警概率为10-3,该文检测算法也可以降低虚警率,实现目标与虚警的自动判决.与传统CFAR检测算法相比,该算法的检测概率高于传统检测算法且随信杂比的下降减小速度缓慢,即使在信杂比-30 dB的情况下所提算法仍然可以保持84％的检测概率.     

海杂波下的双门限恒虚警目标检测新方法

 相参雷达海杂波实测数据拟合结果表明,其能量在多普勒域的分布是变化的.各多普勒频率分量的幅度可分别用瑞利分布和威布尔分布来描述其分布规律.据此提出一种双门限恒虚警(CFAR)检测器,其采用级联结构实现,具有恒虚警性能,运算量与列窗检测器相当,但检测性能得到大大提升.采用实测海杂波与仿真目标信号进行蒙特卡洛实验,在保持虚警概率10^-5,检测概率大于90%的条件下,相对列窗检测器,信噪比改善大于9dB,具有很好的工程应用前景.     

一种机载组网雷达协同目标检测算法

多机协同的机载雷达组网联合目标探测可有效提高复杂电磁干扰环境下对隐身弱目标的探测能力。文中针对机载雷达组网探测时空间配准误差大、协同探测难以实现的难题,提出了一种基于轨迹空间配准的协同目标检测算法,通过雷达间少量距离-多普勒域数据及低检测门限下目标轨迹域数据的交互,采用极大似然估计广义似然比检测器对目标进行联合恒虚警检测(CFAR),并通过轨迹域空间配准与CFAR的迭代计算,实现配准精度和目标联合检测性能的双提升。数值仿真实验的结果表明,在四部雷达组网工作时,在相参积累后信噪比9 dB、虚警概率10^-4的典型场景下,经过迭代处理,空间配准精度可达到一个距离-多普勒分辨单元;对目标的检测概率由单部雷达的28.5%提高到四部雷达协同下的83.67%。     

一种简单的相干雷达极化恒虚警检测算法

该文提出了高斯杂波背景下一种结构简单的相干雷达极化恒虚警检测算法。利用雷达回波的极化信息来提高检测性能,推导出了虚警概率表达式。研究结果表明,该相干雷达极化恒虚警检测算法相对于杂波协方差矩阵有恒虚警的性质。该检测算法比极化广义似然比检测算法计算量小,易于工程实现,适合于强信杂比和目标信号导向矢量未知的情况。同时仿真分析了不同极化状态时的检测性能。     

基于压缩感知的CFAR目标检测算法

该文提出一种基于压缩感知(Compressive Sensing, CS)的恒虚警率(Constant False Alarm Rate, CFAR)目标检测算法,首先分析了目标在距离单元上具有稀疏特性,并构造了目标回波的稀疏字典,设计特定的测量矩阵以及基于CS的CFAR检测结构,然后实现了对回波信号的压缩测量和CFAR检测,无需对回波信号重构。该文提出的算法具有很好的降噪性能并提高了检测效率,可以对低信噪比、低信杂比信号成功检测。仿真结果表明：当信噪比为-14 dB,信杂比为-10 dB时,该算法与传统匹配滤波检测算法相比,减少了一半数据运算量,性能明显优于压缩匹配滤波检测算法。     

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.     

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.     

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.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.