Poles and Zeros – Examples of the Behavioral Approach Applied to Discrete Linear Repetitive Processes

In this paper the behavorial approach is applied to discrete linear repetitive processes, which are class of 2D systems of both systems theoretic and applications interest. The main results are on poles and zeros for these processes, which have exponential trajectory interpretations. Published online: April 2006     

基于人工智能方法的无源光网络优化规划

使用人工智能方法对PON网络拓扑结构进行优化,以富士通FPX－1000无源光网络系统为例进行了仿真实验,并对遗传算法,增添算法和Hopfield网络方法进行比较,仿真结果表明遗传算法明显优于增添算法和Hopfield网络方法,遗传算法可使网络建设代价最小化,它非常好地解决了PON规划问题。     

巡飞弹航迹导引方法研究

针对巡飞弹等高、常速巡飞等特点,将整条航迹分为直线段和转弯段,利用假设条件,提出一种导引方法:在直线段进行位置和偏差角控制,转弯段采用转弯控制,进而完成整个航迹导引并确保巡飞弹在飞行过程中偏离航线的误差较小。通过仿真可以看出,此方法使得巡飞弹在整个飞行过程中偏离航线的误差极小。     

直线振子和V形振子的时域辐射特性

本文用时间步进法求解线天线的时域积分方程,计算分析了直线振子和V形振子的时域辐射特性。分析了馈源位置、加载大小对振子输入电流及远区辐射场的影响。对V形振子的长度及张角等参数作了优化,找到了获得前向辐射场强最大瞬时冲击值的结构参数,结果可供此类天线的设计参考。     

有强内电场的GaN-基阶梯量子阱中的线性与非线性光吸收

采用密度矩阵方法,考察了带强内建电场GaN-基阶梯量子阱中的线性与非线性光吸收系数.基于能量依赖的有效质量方法,在考虑了带的非抛物性情况下,推导了结构中的精确解析的电子本征态,给出了系统中简单解析的线性与非线性光吸收系数表达式.以AlN/GaN/AlxGa1-xN/AlN阶梯量子阱为例进行了数值计算.结果发现阶梯量子阱的阱宽Lw、阶梯垒宽Lb、阶梯垒的掺杂浓度x的减小将提高体系的吸收系数.而且,随着Lw,Lb和x减小,吸收光子的能量有明显的蓝移,总吸收系数的半宽度及饱和吸收强度均减小.计算获得的部分结果与最近的实验观察完全一致.     

Chaos-Based transmitted-reference ultra-wideband communications

Transmitted-reference (TR) ultra-wideband (UWB) communication systems have gained increasing popularity for the usage in the low data rate application, due to its non-coherent receiver structure. In conventional TR system, non-coherency at the receiver is achieved by sending reference pulses prior to the data-bearing pulses. Then, at the receiver side, reference pulses are used as template signals for correlation with data-bearing pulses. Therefore, the orthogonality between reference and data pulses is obtained in time division multiple access (TDMA) fashion. However, the implementation of a wideband delay line is very difficult in the current low power integrated circuits. In this paper, a TR method called Chaos-Based TR (CB-TR) is proposed. In the proposed method, chaotic sequences are used to separate the reference and data pulses. Such approach exploits the benefits of chaotic signals, such as non-periodicity, easy-to-generate, impulse-like autocorrelation value and low cross-correlation value. Furthermore, in order to decrease the influence of some negative properties of conventional chaotic maps, a modified chaotic generator (MCS) is proposed. Simulation results over the IEEE 802.15.4a channel model show comparable bit error rate performance to other TR methods.     

Evaluation and protection of multi-level location privacy based on an information theoretic approach

A privacy metric based on mutual information was proposed to measure the privacy leakage occurred when location data owner trust data users at different levels and need to publish the distorted location data to each user according to her trust level,based on which an location privacy protection mechanism (LPPM)was generated to protect user’s location privacy.In addition,based on mutual information,a metric was proposed to measure the privacy leakage caused by attackers obtaining different levels of distorted location data and then performing inference attack on the original location data more accurately.Another privacy metric was also proposed to quantify the information leakage occurred in the scenario based on mutual information.In particular,the proposed privacy mechanism was designed by modifying Blahut-Arimoto algorithm in rate-distortion theory.Experimental results show the superiority of the proposed LPPM over an existing LPPM in terms of location privacyutility tradeoff in both scenarios,which is more conspicuous when there are highly popular locations.     

New detection algorithms based on the jointly Gaussian approach and successive interference cancelation for iterative MIMO systems

A new detection algorithm based on the jointly Gaussian approach (JGA) and successive interference cancelation (SIC), named the SIC‐JGA algorithm, is proposed for iterative MIMO systems. Both the a priori symbol estimates of the undetected layers and the a posteriori symbol estimates of the previously detected layers are used in the SIC process. To reduce the complexity of covariance matrix inversion in the proposed algorithm, simplified algorithms named S‐SIC‐JGA are investigated for both the single path and multipath block fading channels under M Phase Shift Keying modulations. A detailed complexity analysis is presented for both the SIC‐JGA and S‐SIC‐JGA algorithms. Numerical results exhibit that the system using the SIC‐JGA algorithm outperforms the JGA algorithm, with an additional complexity for determining the detection order of SIC. The S‐SIC‐JGA algorithm has a much lower complexity compared with the SIC‐JGA algorithm while experiencing an acceptable system performance degradation. Proper detection algorithms can be chosen in different iterations to balance the system performance and the detection complexity. Copyright © 2012 John Wiley & Sons, Ltd.     

Speech Enhancement Using Phase‐Dependent A Priori SNR Estimator in Log‐Mel Spectral Domain

We propose a novel phase‐based method for single‐channel speech enhancement to extract and enhance the desired signals in noisy environments by utilizing the phase information. In the method, a phase‐dependent a priori signal‐to‐noise ratio (SNR) is estimated in the log‐mel spectral domain to utilize both the magnitude and phase information of input speech signals. The phase‐dependent estimator is incorporated into the conventional magnitude‐based decision‐directed approach that recursively computes the a priori SNR from noisy speech. Additionally, we reduce the performance degradation owing to the one‐frame delay of the estimated phase‐dependent a priori SNR by using a minimum mean square error (MMSE)‐based and maximum a posteriori (MAP)‐based estimator. In our speech enhancement experiments, the proposed phase‐dependent a priori SNR estimator is shown to improve the output SNR by 2.6 dB for both the MMSE‐based and MAP‐based estimator cases as compared to a conventional magnitude‐based estimator.     

中国专利转化途径改进初探

基于中国专利申请的实际情况,分析目前专利转化率低的成因.从专利转化途径方面入手,提出通过专利转化政策的调整和相关制度的松绑,以及由国家知识产权局牵头搭建一个专业、权威、规范、统一、监管有力的信息服务平台,为专利权利人和相关企业提供切实服务,为国内知识产权战略的落实提供支撑,促进经济社会的快速、有序、健康发展.