一种改进粒子滤波的双站无源定位跟踪算法

在非线性非高斯状态空间下，粒子滤波器是一种有效的非线性滤波算法，它的关键问题包括粒子权重的计算、粒子重采样和状态估计等。本文根据粒子滤波算法思想和双站无源定位跟踪的非线性，将粒子滤波算法用于双站无源定位跟踪问题，给出了一种改进的粒子滤波算法，并对其关键问题根据双站无源定位跟踪的特殊性进行了改进。利用Matlab进行了仿真实验，与最小二乘算法、扩展卡尔曼滤波算法进行了比较，结果表明所提算法定位跟踪精度优于其他方法。     

基于信息理论和概率假设密度的自适应多站多目标无源定位与跟踪算法

<正>本文针对密集杂波和冲击噪声条件下的多站多目标无源定位与跟踪问题，基于信息理论和随机有限集提出一种新的自适应高斯混合概率假设密度（PHD）滤波算法。该算法引入渐消因子，基于新息的方差动态修正滤波增益，并采用KL度量对量测更新步骤中多目标密度近似前后的差异进行衡量，在最小信息增量意义下对高斯元进行合并，得到更准确的多目标状态后验分布，提高了多站多目标无源定位与跟踪精度，并降低了冲击噪声等对估计结果的影响。本文给出了基于信息理论的自适应多目标跟踪算法的高斯混合实现方式，所提出的方法继承了PHD滤波器的优点，具有较好的实时性和多目标跟踪性能。最后，采用仿真实验对本文提出的算法进行验证，实验结果证明了本文所提出算法的有效性和优越性。     

空基多平台对空中机动目标的被动跟踪定位算法

针对空中机动目标的被动定位跟踪问题,提出了一种先用静态估计理论对空中目标进行最小二乘估计,再采用基于“当前”统计模型的自适应滤波算法进行滤波处理的方法,取得了比最小二乘估计与卡尔曼滤波相结合的算法更好的效果。仿真结果表明,在跟踪非机动目标时,该算法和最小二乘估计与卡尔曼滤波结合的办法相当;在跟踪机动目标时,该算法的误差明显小于原算法。     

反直升机雷群的机动目标跟踪

反直升机雷测距精度较低,而利用角度信息估计目标的距离和速度实质上是一个非线性状态估计问题,这种单站被动式跟踪可能构成一个不可观测系统,将导致跟踪滤波器的不稳定和发散。本文对由反直升机雷构成的雷群的目标定位和跟踪进行了研究,利用最小二乘法和基于“当前”统计模型的自适应滤波组合算法进行数据处理,最小二乘法的估计结果作为自适应滤波的观测值,结果表明算法简单而且有效,在目标机动和非机动时都能得到良好的估计结果。     

基于总体最小二乘算法的多站无源定位

将总体最小二乘算法应用于多站无源定位中,分别提出了基于角度估计的总体最小二乘算法,基于时差估计的总体最小二乘算法以及基于角度和时差估计的总体最小二乘算法。算法首先把非线性的观测方程转化为伪线性的观测方程,然后构造增广矩阵,并对该矩阵进行奇异值分解即可估计出目标位置,因此无需迭代计算或者获得目标位置的粗略估计,仿真结果表明该算法具有较高的定位精度。     

基于强跟踪容积卡尔曼滤波的单站无源跟踪算法北大核心CSCD

系统模型和滤波算法是机动目标单站无源定位跟踪要解决的核心问题。文中采用截断正态概率模型和一种新型的滤波算法--容积卡尔曼滤波,对机动目标进行单站无源定位跟踪。针对目标突发机动的情况,借鉴强跟踪滤波器的思想,在滤波过程中引入时变渐消因子,提出了一种强跟踪容积卡尔曼滤波算法(Strong Tracking Cubature Kalman Filter,STCKF)。该算法利用容积数值积分原则直接计算非线性随机函数的均值和方差,实现简单,估计精度高,并通过渐消因子自适应在线调节增益矩阵,增强了系统对突发机动的跟踪能力。结合空频域单站无源定位模型进行仿真实验表明,STCKF算法在对一般机动目标进行跟踪时,性能与CKF算法相当,并优于传统的EKF算法。当目标突变大机动时,STCKF算法的滤波性能要高于EKF以及CKF算法。     

基于纯角度信息的单站无源定位算法

本文研究了在纯角度测量信息下地面干扰源的单站无源定位问题,给出了一种新的基于纯角度信息的非线性滤波无源定位算法。该算法首先利用载机初始位置和目标角度测量值,计算得到初步的目标状态值和状态协方差值,其次用这些信息来初始化扩展卡尔曼滤波器,最后运用扩展卡尔曼滤波器进行非线性滤波,得到高精度的目标定位结果。经过仿真结果分析,该算法具有收敛速度快、定位精度高的特点,能够较好的满足工程实际的应用要求。     

考虑载机位置误差的CLS多机无源定位算法

多机无源定位中存在载机位置误差却不予考虑时必然会降低目标的定位跟踪精度。为了解决存在载机位置误差情况下的定位问题,提出了一种考虑载机位置误差的约束最小二乘（CLS）多机无源定位算法。该算法对伪线性观测方程中由于测量误差和载机位置误差而导致的增广系数矩阵的误差协方差阵进行约束,并对伪线性观测方程的误差进行约束最小二乘处理,最终转化为对一组矩阵束的广义特征分解问题。仿真结果表明,相对于最小二乘（LS）算法和扩展卡尔曼滤波（EKF）算法,该算法具有更快的收敛速度和较高的定位精度,并且受载机位置误差影响小,在观测噪声比较大时仍能保持良好的定位性能。      

一种基于最小化广义Rayleigh商的无源定位算法研究

 为改善只测角无源定位的性能,提出了一种基于最小化广义Rayleigh商的无源定位算法.该算法利用扰动观测矩阵和扰动观测向量的乘性结构,将约束总体最小二乘问题转化为最小化广义Rayleigh商问题,从而只需对一对矩阵束进行广义特征值分解即可求得全局最优定位解.仿真结果表明所提算法性能稳健且计算量较小,定位收敛精度逼近克拉美罗限(CRLB),远优于最小二乘(LS)算法和总体最小二乘(TLS)算法,实用性强.     

双站基于角度和时差的近似无偏定位算法

联合角度（DOA）和时差（TDOA）信息对运动目标进行无源定位实质上是一种非线性估计问题。针对将非线性观测方程转化为伪线性方程会产生有偏估计的缺点,该文基于双站定位中获得的角度和时差信息,给出了一种对三维空间目标定位跟踪的近似无偏估计滤波算法,它只需要对一对矩阵束进行广义特征分解,即可获得目标坐标和速度的估计值。计算机仿真结果表明,相比有偏估计滤波算法,如伪线性卡尔曼滤波（PLKF）算法或者最小二乘（LS）算法,该算法具有更高的定位精度,并且当观测误差增大时,其优势更加明显。     

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.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

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.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

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.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

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.     

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.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.