保持粒子多样性的非退化粒子滤波方法研究

针对现有粒子滤波算法中的粒子退化问题以及重采样所引起的粒子多样性减弱问题,将自适应遗传算法与粒子滤波结合设计一种新的非退化粒子滤波算法。该算法通过对粒子使用遗传算子操作以保证粒子的多样性和有效性,根据粒子在前一时刻计算出来的先验信息自适应地实时调节当前时刻的遗传操作概率,有效增加了粒子对系统状态变化的适应性。实验结果表明,该算法可有效提高非线性系统状态的估计精度,尤其在系统状态发生突变的时候,可以得到较好的估计精度。     

一种基于差分演化的粒子滤波算法

针对粒子滤波(Particle Filter, PF)存在的粒子退化和贫化问题,该文提出一种基于差分演化(Differential Evolution, DE)的PF算法。首先,为了充分利用最新的观测信息,采用无迹卡尔曼滤波(Unscented Kalman Filter, UKF)来产生重要性分布,对重要性分布产生的采样粒子不再做传统重采样操作,而是直接把采样粒子当作DE中的种群样本,粒子权重作为样本的适应函数,对粒子做差分变异、交叉、选择等迭代优化,最后得到最优的粒子点集。试验结果表明,该算法有效缓解了传统PF算法中的粒子退化和贫化,提高了粒子的利用率,具有较好的估计精度。     

一种新的改进辅助变量粒子滤波算法北大核心CSCD

针对辅助变量粒子滤波(AVPF)对状态估计无法获得较好的滤波精度的问题,本文提出了一种改进的辅助变量粒子滤波算法.将正则化的思想引入到辅助变量粒子滤波的重采样中,在重采样中将离散的概率分布函数近似为连续的分布函数,该方法不仅保留了AVPF在重采样之前依据似然值的大小对原粒子集中的各个权值进行修正,从经过平滑后的后验密度中重采样的特点,在重采样中引入正则化思想后还能够保持粒子的多样性,增加有效样本数目,能够有效抑制样本退化.针对一个被广泛采用的双峰,高度非线性的系统模型,在选取不同的过程噪声下,进行Monte Carlo仿真实验.仿真实验表明,改进的辅助变量粒子滤波具有更好滤波精度.     

基于空间分布和时间序列分析的粒子滤波算法

针对粒子滤波存在的粒子贫化问题,提出了一种改进的重采样粒子滤波算法.在重采样步骤中基于采样粒子集的空间分布引入时间序列分析,选取相关度最高的粒子进行传递,避免了只关注采样粒子权值的传统重采样算法中仅复制大权值粒子而任意丢弃小权值粒子的缺陷,因此能够消弱粒子贫化现象,提高算法的估计精度.在理论上利用两样本Kolmogorov-Smirnov检验原理证明了改进算法重采样后的粒子集和采样前的粒子集来自同一总体.仿真结果表明,尤其是在初始采样粒子数目较小时,该算法在非线性系统状态估计中的精度优于传统的粒子滤波算法.     

基于CPFDE的目标跟踪算法研究

在目标跟踪中,为了克服粒子滤波的粒子退化和贫化问题,提高滤波精度,文中将差分演化算法与容积粒子滤波相结合,形成了差分演化容积粒子滤波算法。在粒子进行先验更新时, 使用容积卡尔曼滤波算法融入当前时刻的量测信息并用其来产生重要性密度函数,并且在重采样阶段,用差分演化算法对根据重要性密度函数抽取的采样粒子做优化操作,从而克服粒子滤波存在的粒子退化及贫化问题,提高滤波性能。实验结果表明,和粒子滤波、无迹粒子滤波、容积粒子滤波相比,该算法有着更高的滤波精度和更好的稳定性,并且能够提高雷达机动目标跟踪的精确性。     

基于最优采样函数的粒子滤波算法与贝叶斯估计

传统粒子滤波器(PF)直接根据状态演化方程产生新的粒子,由于没有考虑新近观测对状态估计的影响,这种滤波器性能较差,即便在粒子数目很大的情况也是如此。为此,本文提出一种基于序贯重要采样(SIS)的改进粒子滤波算法,该算法采用集成了新近观测量的最优采样(或重要密度)函数指导粒子的生成,使粒子权值的方差最小化,能有效减轻粒子退化问题;同时。在粒子重采样之后增加了马尔科夫链蒙特卡洛(MCMC)过程,消除了重采样引起的粒子贫化的负面影响,从而使粒子的多样性得以保持。对非线性系统的状态估计和只测角跟踪的仿真实例均表明,本文所提出的算法比传统估计算法如EKF,UKF具有更高的精度和更强的鲁棒性;与标准PF相比,其性能也有较大的提高,并可以在相同的估计精度下大大减少所需的粒子数目,是一种有效的非线性滤波算法。     

宽带波达方向估计的辅助粒子滤波算法

针对粒子滤波宽带波达方向估计中因采样粒子权值不稳定导致估计误差较大的问题,提出了基于辅助粒子滤波的宽带波达方向估计算法。该算法利用贝叶斯重要性采样算法,在权值大的粒子基础上引入辅助粒子变量,重新定义重要性采样分布函数。经过两次加权计算,进而改善粒子退化问题,并引导粒子向高似然区域移动,使粒子在真实状态周围分布更均匀,粒子权值比仅用重采样的粒子权值变化更稳定。仿真实验表明,该算法在均方根误差和检测概率性能上优于粒子滤波算法。      

裂变自举粒子滤波

自举粒子滤波(BPF:Bootstrap Particle Filtering)是一种经典而应用广泛的粒子滤波算法,但其重采样后常会引起严重的样本枯竭问题.本文提出在权值蜕化较为严重时,在原先的重采样前增加SFN预处理,即权值排序、裂变繁殖(fission)和权值归一,得到裂变BPF(FBPF)算法.针对一个典型的后验密度为双峰的强非线性滤波估计问题,通过Monte Carlo仿真表明,FBPF算法在保持与BPF算法相当的估计精度和运算时间的条件下,克服了样本枯竭问题,算法的鲁棒性更强.     

基于有限差分扩展卡尔曼粒子滤波的多特征自适应融合的目标跟踪算法研究

针对复杂环境下目标跟踪问题,提出了一种基于 有限差分扩展卡尔曼粒子滤波的多 特征自适应融合跟踪算法。采用有限差分扩展卡尔曼滤波器对采样粒子集合进行滤波更新, 通过融入最新观测信息的方法消弱权值退化现象;在新算法的框架内,利用目标静态和动态 互补特征作为观测量,实现不同环境下目标的多特征自适应融合跟踪。实验结果表明,本文 方法具有较好的跟踪精度和抗噪声干扰能力。     

基于Sh相关系数的非线性系统状态粒子估计算法

本文提出一种适用于非线性系统状态的粒子估计算法--基于Sh相关系数的粒子估计(PE)算法.该算法主要由预测、更新和平滑组成,利用被估计状态观测值路径和粒子观测值路径之间的Sh相关系数来修正粒子权值.仿真实验结果表明,该算法在状态估计精度上优于序列重要性重采样(SIR)算法、辅助粒子滤波(APF)算法、正则化粒子滤波(RPF)算法、高斯粒子滤波(GPF)算法和高斯混合粒子滤波(GSPF)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