复合调制长周期光栅耦合器的研究

从麦克斯韦方程出发,推导了长周期光栅耦合器在折射率、增益、损耗复合调制下完整的耦合理论模型。在此基础上,详细分析了该复合调制长周期光栅耦合器直通与交叉臂间的功率耦合和多波长滤波特性。结果表明,当增益/损耗调制与折射率调制作用相等时,复合调制长周期光栅耦合器具有单向非互易的功率耦合特性,而且随着多波长复用信号输入光纤和输入方向的不同,具有不同的上下话路滤波特性。在增益调制作用下,满足相位匹配条件的信号不仅可有效地耦合到交叉臂下话路输出,还能得到明显的放大;但当损耗调制时,直通与交叉臂中的信号功率均保持各自的初值,而且不再具备波长选择滤波能力。     

由背面工艺导致的3.3-kV NPT-IGBT阳极注入效率降低效应的实验研究

The anode injection efficiency reduction of 3.3-kV-class non-punch-through insulated-gate bipolar transistors (NPT-IGBTs) due to backside processes is experimentally studied through comparing the forward blocking capabilities of the experiments and the theoretical breakdown model in this paper. Wafer lifetimes are measured by a μ-PCD method, and well designed NPT-IGBTs with a final wafer thickness of 500 μm are fabricated. The test results show higher breakdown voltages than the theoretical breakdown model in which anode injection efficiency reduction is not considered. This indicates that anode injection efficiency reduction must be considered in the breakdown model. Furthermore, the parameters related to anode injection efficiency reduction are estimated according to the experimental data.     

一种公交最佳路径选择方法

通过分析最短路径算法及城市公交网络的特点提出了城市公交网络换乘的实现方法.首先,针对城市公交网络构造公交网络模型.其次,根据城市公交网络特点引入公交网络的直达矩阵,并依据该直达矩阵将城市公交网络抽象表示成一个"公交网络邻接图".再次,利用最短路径算法结合城市公交抽象网络图计算,得出最少换乘次数和可能的换乘站点.最后,利用所建立公交网络模型及所得换乘次数和可能的换乘站点进行计算,得到了综合考虑最小换乘和最短路径的最佳路径.并用一算例检验了该算法的有效性.     

Dynamic sensor collaboration via sequential Monte Carlo

We consider the application of sequential Monte Carlo (SMC) methods for Bayesian inference to the problem of information-driven dynamic sensor collaboration in clutter environments for sensor networks. The dynamics of the system under consideration are described by nonlinear sensing models within randomly deployed sensor nodes. The exact solution to this problem is prohibitively complex due to the nonlinear nature of the system. The SMC methods are, therefore, employed to track the probabilistic dynamics of the system and to make the corresponding Bayesian estimates and predictions. To meet the specific requirements inherent in sensor network, such as low-power consumption and collaborative information processing, we propose a novel SMC solution that makes use of the auxiliary particle filter technique for data fusion at densely deployed sensor nodes, and the collapsed kernel representation of the a posteriori distribution for information exchange between sensor nodes. Furthermore, an efficient numerical method is proposed for approximating the entropy-based information utility in sensor selection. It is seen that under the SMC framework, the optimal sensor selection and collaboration can be implemented naturally, and significant improvement is achieved over existing methods in terms of localizing and tracking accuracies.     

基于NSCT变换和小波变换相结合的图像融合算法研究

针对小波变换在表达图像边界及线状特征上的缺陷,以及NSCT变换在表达图像细节信息的不足,提出了在红外图像与可见光图像融合的过程中采用基于NSCT变换和小波变换相结合的图像融合算法。在图像NSCT分解后,对低频系数使用基于小波变换的融合算法,对高频系数结合融合图像的特点采用了基于区域方差的融合规则。实验结果表明,基于NSCT变换和小波变换相结合的融合算法能更好地保持可见光图像的光谱信息和红外图像的目标信息,具有更多的细节特征以及更清晰的边缘。     

美海军CEC系统研究现状探析

协同作战能力CEC(Cooperative Engagement Capability)网络系统是网络中心战的重要组成部分,该系统的投入使用将有效提高航母战斗群的对空防御作战能力。研究了协同作战能力网络系统的组成、工作原理以及其具备的主要功能和作战性能。分析了协同作战能力网络系统的研究现状及其发展趋势等。对深入研究美海军航母战斗群作战能力及网络中心战的发展方向具有一定的指导作用。     

基于TDLAS的非均匀流场温度分布的测量

基于可调谐半导体激光吸收光谱（TDLAS）温度测量技术,使用多条谱线能够实现非均匀流场的气体温度分布的测量,主要有剖面拟合和温度离散两种方法。对剖面拟合方法进行理论分析和仿真,并且假设电炉上方0.5 cm处的温度分布为二次函数ax2+bx+c,采用剖面拟合方法进行测量,与热电偶测量的温度进行对比,温度最大波动为49 K。     

Moisture Sensitive Smart Yarns and Textiles from Self‐Balanced Silk Fiber Muscles

Smart textiles that sense, interact, and adapt to environmental stimuli have provided exciting new opportunities for a variety of applications. However, current advances have largely remained at the research stage due to the high cost, complexity of manufacturing, and uncomfortableness of environment‐sensitive materials. In contrast, natural textile materials are more attractive for smart textiles due to their merits in terms of low cost and comfortability. Here, water fog and humidity‐driven torsional and tensile actuation of thermally set twisted, coiled, plied silk fibers, and weave textiles from these silk fibers are reported. When exposed to water fog, the torsional silk fiber provides a fully reversible torsional stroke of 547° mm^?1. Coiled‐and‐thermoset silk yarns provide a 70% contraction when the relative humidity is changed from 20% to 80%. Such an excellent actuation behavior originates from water absorption‐induced loss of hydrogen bonds within the silk proteins and the associated structural transformation, which are corroborated by atomistic and macroscopic characterization of silk and molecular dynamics simulations. With its large abundance, cost‐effectiveness, and comfortability for wearing, the silk muscles will open up additional possibilities in industrial applications, such as smart textiles and soft robotics.     

主动锁模Nd：YAG激光器热稳腔的优化设计

本文首先讨论热稳谐振腔概念及其相应的热稳条件,提出了“综合热稳”的概念,并在各种假设的优化范围内,借助计算机选出了Nd:YAG主动锁模激光器对应的最优腔。实验结果与理论分析基本吻合。