Maneuvering Multi-target Tracking Using the Multi-model Cardinalized Probability Hypothesis Density Filter

Tracking an unknown and time-varying number of maneuvering targets is a challenging problem in the presence of noise, clutter uncertainties in target maneuvers, data association, and detection. To account for this problem, a multi-model extension of the Cardinalized probability hypothesis density （CPHD） filter is proposed in this paper. Additionally, a particle implementation and a Gaussian mixture implementation of the proposed extension are given for generic models and linear Gaussian models, respectively. The effectiveness of the extension is illustrated through Monte Carlo simulation.     

Semi-flex印制板制作工艺研究

使用半固化片(PP)开窗法制作Semi-flex印制电路板时,半固化片开窗的尺寸及品质直接影响压合时树脂向Semi-flex印制板挠性区域的流动情况,进而影响其挠曲性能。本文使用开窗法制作挠性层为L5/L6层的10层Semi-flex印制板,研究了铣刀转速、叠合张数等加工参数对半固化片开窗品质的影响,以及半固化片开窗放大尺寸与压合时刚挠结合处PP溢胶长度的关系。为了验证产品其可靠性,对其进行了漂锡测试、回流焊测试和冷热冲击测试。     

新型太赫兹光子晶体OAM光纤设计

太赫兹通信兼具微波通信和光波通信的优势,是解决通信容量紧缺难题的最有效技术手段之一。针对太赫兹波段吸收损耗严重及抗外在扰动差,难以支持长距传输问题,设计了一种基于环形光子晶体光纤(PCF)结构的新型太赫兹光纤。以现有常见材料作为光纤基底材质,通过创新光纤结构中空气孔排布方式,抵消材料高吸收损耗,以支持高性能轨道角动量(OAM)模式传输。选择最优参数,实现6个OAM模式群的高模式质量、低限制损耗和宽带宽的稳定传输。在0.2~0.9 THz宽波段内,实现模式纯度超过88.9%,限制损耗小于10^-7 dB/m。通过软件仿真实验设计,解决了太赫兹与OAM技术相结合的关键问题,为模分复用(MDM)技术在太赫兹通信系统的应用奠定了理论研究基础。     

基于时空感知的用户角色推理

随着大数据和信息技术的发展,更好地理解用户的行为轨迹在个性化推荐、广告推荐等方面越来越重要。该文依据大数据环境下的城市计算理论,提出一种基于情境感知的用户角色推理模型。通过用户的行为轨迹分析其行为的时空特性;结合时间、语义分析等构造识别用户角色概率推理模型;通过算法克服识别用户角色的主观性、动态适应性差等问题。实验结果证明了该文所提模型的可行性、精确性和预测准确性。     

基于渐变结构的矩形腔表面波 等离子体源仿真和设计*

目前,大尺寸矩形腔表面波等离子体源的设计中,利用缝隙辐射器耦合微波能量时,绝大部分都是在波导的宽 边开缝,这在一定程度上限制了电场均匀性的进一步提高。本文提出了一种基于渐变结构的缝隙辐射器设计,即扩展波导宽 边同时压缩窄边形成具有稳定模式的宽边更宽窄边更窄的结构。设计了加载短路面的缝隙阵列耦合结构并利用时域有限差 分（FDTD）方法计算了电子密度为1.79×1018 m-3、碰撞频率为3×108 Hz 时石英-等离子体分界面上电场幅度分布,并与传统波 导开缝结构对比,实现了电场均匀性的有效提升,并得到了稳定的表面波模式。     

Inter‐cell interference mitigation based on joint beamforming

In cellular networks, global channel state information (CSI) shall be shared among neighboring cells to mitigate various inter‐cell interference (ICI). In this paper, we propose that comparable ICI is mitigated while weak ICI is treated as noise. The amount of shared CSI is highly reduced, because of that only the CSI corresponding to comparable ICI is shared among neighboring cells. In the case of single user equipment in each cell, a joint singular value decomposition and interference alignment method is proposed along with the analysis of its approximate sum rate. Some nodes select singular value decomposition method, while others choose interference alignment method. The method at each node is determined by global selection principle or user classification principle. In the case of multiple UEs in each cell, all nodes utilize minimum mean square error method, but ICI is neglected at cell center users. Copyright © 2014 John Wiley & Sons, Ltd.     

一种基于二维细化的自适应信号捕获算法

该文针对低信噪比(SNR)情况下信号捕获精度较低的问题提出一种基于伪码相位和载波频率的2维细化自适应捕获算法,该算法根据信号强度自适应调整频率步进值和捕获门限,首先对伪码相位和载波频率进行粗捕,在此基础上对捕获到的伪码相位方格和载波频率方格进行细化,再对伪码相位和载波频率进行细捕以提高捕获精度。该文对算法进行了理论分析和仿真验证,结果表明,该算法能提高捕获的伪码相位分辨率和载波频率分辨率,有效提高检测概率,适用于低信噪比和高精度要求下的信号快速捕获。     

基于扩散小波的社会网络多尺度分析简

针对社会网络中的同质性关系提出一个基于扩散小波的多尺度分析框架,通过局部相似性度量构造扩散算子,在统一的框架下对社会网络中的结构、内容、用户行为等进行多尺度分析。在合成和真实网络数据上进行实验,与典型算法的对比表明,本算法在无参数的条件下快速收敛并得到更好的结果。     

Phosphorus Removal from Silicon by Vacuum Refining and Directional Solidification

Silicon is widely used as a raw material for production of solar cells. As a major impurity in silicon, phosphorus must be removed to 1 × 10^?5 wt.%. In the present study, based on the distribution of phosphorus in a silicon ingot obtained by vacuum refining and directional solidification, the mechanism for removal of phosphorus from silicon is investigated. The results show that the distribution is controlled not only by segregation at the solid–liquid interface but also by evaporation at the gas–liquid interface, showing some deviation from Scheil’s equation. A modified model which considers both segregation and evaporation is used to simulate the distribution, matching quite well with the experimental results. The temperature and solidification rate are two important parameters that affect the overall mass transfer coefficient and the effective segregation coefficient and thus the distribution of phosphorus. A high removal efficiency and a homogeneous distribution can be obtained by adjusting these two parameters.     

基于双并联Boost电路的光伏系统最大功率点跟踪控制方法

光伏电池的输出功率取决于外界环境（温度和光照条件）和负载状况,需采用最大功率点跟踪（MPPT）电路,才能使光伏电池始终输出最大功率,从而充分发挥光伏器件的光电转换效能.在比较了常用光伏发电系统控制的优缺点后,依据MPPT控制算法的基本工作原理,主电路采用双并联Boost电路,具有电压提升功能,并且能够提高DC-DC环节的额定功率和减小直流母线电压的纹波.针对传统扰动观察法存在的振荡和误判问题,提出了一种新型的基于双并联Boost电路的改进扰动观察法最大功率跟踪策略.在Matlab/Simulink下进行了建模与仿真,仿真结果表明,当外界环境发生变化时,系统能快速准确跟踪此变化,避免算法误判现象的发生,通过改变当前的负载阻抗,使之与光伏电池的输出阻抗等值相匹配采满足最大功率输出的要求,使系统始终工作在最大功率点处,并且在最大功率点处具有很好的稳态性能.最后通过实验验证了该算法的有效性.