基于随机有限集的UPF-CPHD多目标跟踪

提出一种基于随机有限集的无迹粒子基数概率假设密度滤波（UPF-CPHD, unscented particle filter - cardinality probability hypothesis density）的多目标跟踪方法。在粒子滤波框架下采用随机有限集（RFS, random finite sets）对多目标状态和观测进行描述。在UPF滤波框架下引入CPHD算法同时递推目标状态和目标数目,并计算最新观测信息,估计结果更加精确,弥补PHD估计目标数目不可靠的缺点。仿真实验表明,UPF-CPHD多目标跟踪方法能够降低超过50%的目标数目估计误差,并提高目标状态的估计精度。     

视野有限的传感器网络中分布式多目标跟踪

在传感器网络的多目标跟踪研究中,大多数现有的跟踪算法通常设定网络中所有节点具有相同的视野,即所有节点都能够得到目标的测量,但在实际中,节点的感测范围通常是有限的。针对这一问题,本文提出了一种能够在感测范围有限的多传感器网络中实现多目标跟踪的分布式概率假设密度滤波算法,该算法通过融合传感器网络视野范围内的后验概率假设密度粒子集来克服传感器节点感测范围的局限。仿真结果表明,提出的算法可以在感测范围有限的情况下实现多目标状态和数目的有效跟踪,同时可以在一定程度上抑制杂波,具有较好的跟踪稳定性。      

基于GM-PHD的多目标跟踪算法仿真及影响因素

基于有限集统计学理论的多目标跟踪技术具备严格的贝叶斯理论解释基础,可以同时完成目标数目及状态的估计,并避免了复杂的数据关联过程。基于高斯混合概率假设密度滤波器(GM-PHD)实现了对数目时变目标的跟踪,准确估计出了每一时刻目标的数目。在此基础上进一步分析了目标生存概率ps、目标检测概率pd以及杂波密度λc等因素对跟踪效果的影响,为GM-PHD滤波器在多目标跟踪的实际应用中各参数的取值提供了有益的参考。     

基于PHD滤波的箱粒子划分多目标跟踪算法

针对现有箱粒子概率假设密度(BOX-PHD)滤波存在箱粒子冗余问题,提出一种箱粒子划分的概率假设密度滤波多目标跟踪算法。该算法在目标状态估计的更新阶段之前,将预测得到的每一个箱粒子划分成多个箱粒子,从而得到等价的箱粒子集,然后对这些箱粒子集的权值利用区间量测进行更新,从而估计目标的状态及数目。该划分由于将箱粒子划分更小,能更好地利用区间量测信息,可以有效避免箱粒子因压缩不足而导致的估计有偏情况。仿真结果表明所提方法可以有效地提高目标的跟踪性能。     

基于随机摄动再采样的粒子概率假设密度滤波器

作为概率假设密度滤波的典型实现方式,粒子概率假设密度滤波器无需线性高斯等先验假设,因而在多目标跟踪中得到了广泛的应用。为解决粒子退化问题并保持粒子规模,该滤波器引入了重采样机制,然而,该重采样机制易引起粒子多样性耗尽,导致粒子贫化问题产生。为解决这一问题,该文提出一种新的基于随机摄动再采样的粒子概率假设密度滤波器。首先,全面分析了粒子概率假设密度滤波因粒子贫化问题导致目标失跟的过程。然后设计了一种随机摄动再采样算法,该算法在重采样导致粒子多样性缺失时,根据源粒子的位置与复制次数随机产生相应数目的新粒子,并对源粒子进行删减,其可在保留源粒子信息的前提下保持粒子的多样性。最后,该文将该算法纳入概率假设密度滤波框架,提出了一种新的粒子概率假设密度滤波器。仿真结果表明该滤波器在不显著增加运行时间的前提下能够克服粒子贫化问题,相比标准的粒子概率假设密度滤波器具有更好的跟踪性能。     

中段弹道目标群的红外成像仿真研究

建立中段弹道目标的简化辐射模型和基于点扩散与拖尾的红外焦平面模型,结合目标群中各目标的运动位置和空间目标投射到二维焦平面位置坐标的计算,仿真天基低轨红外传感器对中段弹道目标群的成像.分析仿真结果,发现中段弹道目标群的存在对天基红外传感器的目标探测与跟踪提出了新的要求,并给出一些解决途径.     

观测最优分配的GM-PHD多目标跟踪算法

概率假设密度滤波器将目标的状态空间及观测空间描述为随机有限集合的形式,有效避免了多目标跟踪中复杂的数据关联问题。但对于不同类型的目标使用同样的全部观测数据集进行目标状态更新,未对观测数据进行合理分配,导致估计性能下降。该文提出一种观测最优分配的高斯混合概率假设密度多目标跟踪算法(MOA-GM-PHD),将目标分为已有目标和新生目标两类,推导极大似然门限来获得两类目标对应的最优观测数据,再分别进行目标状态更新。实验结果表明,该文方法目标跟踪效果优于传统GM-PHD滤波器。      

天基红外系统多目标快速跟踪方法

多传感器多目标跟踪是天基红外系统的核心关键技术之一,面临目标数目随时间变化、目标出现时间与位置难以预知、虚警干扰严重等难点,传统多目标跟踪方法存在组合爆炸问题。文中采用高斯混合概率假设密度滤波器（GM-PHD,Gaussian mixture probability hypothesis density）进行多目标跟踪,有效避免了复杂的数据关联运算;同时,针对GM-PHD滤波器新目标丢失问题,采用反馈滤波方法,通过将传感器量测假设作为新目标的量测,有效实现了对新目标的快速跟踪处理。仿真试验结果表明,本文所提反馈滤波方法具有更好的跟踪性能和更快的收敛速度。     

GM-PHD雷达密集多目标跟踪应用研究

针对雷达密集多目标跟踪数据关联的难题,深入研究了可以避免数据关联的多目标跟踪方法-高斯混合概率假设密度算法(GM-PHD)。首先,将多目标的运动和多目标量测建模为随机有限集的形式,并给出了相应的最优多目标贝叶斯滤波器;然后,在线性高斯假设条件下,详细给出了GM-PHD均值、方差和权值的递归形式,降低了计算复杂度,满足跟踪实时性要求;最后,开展了仿真实验和实测数据实验,实验结果显示GM-PHD在不需要数据关联的情况下,能够有效抑制大量杂波,稳定地跟踪密集多目标。     

多目标滤波中的多传感器概率假设密度算法

多传感器情况下的多目标概率假设密度(PHD)滤波是建立在假设模型上实现的。该文用随机有限集(RFS)方法描述多目标状态空间和传感器量测空间,分析了多传感器通用假设模型下的探测概率、似然函数和杂波分布,在此基础上利用概率产生泛函(PGFL)推导出了多传感器PHD滤波递归式,进而提出粒子标记法多传感器贯序蒙特卡洛PHD(SMC-PHD)滤波等价实现算法,降低了多传感器PHD滤波的计算复杂度。最后给出了算法的具体实现,得到了良好的多目标数目和可跟踪多目标状态的估计。     

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