Non‐fragile H ∞ control for switched stochastic delay systems with application to water quality process

In this paper, the problem of non‐fragile observer‐based H _∞ control for discrete‐time switched delay systems is investigated. Both data missing and time delays are taken into account in the links from sensors to observers and from controllers to actuators. Because data missing satisfies the Bernoulli distribution, such problem is transformed into an H _∞ control problem for stochastic switched delay systems. Average dwell time approach is used to obtain sufficient conditions on the solvability of such problems. A numerical example and a real example for water quality control are provided to illustrate the effectiveness and potential applications of the proposed techniques. Copyright © 2013 John Wiley & Sons, Ltd.     

Efficient CVD diamond film/alumina composite substrate for high density electronic packaging application

Due to its extreme hardness, chemical and mechanical stability, large band gap, low dielectric constant and highest thermal conductivity, diamond film is expected to be an excellent electronic packaging material for high frequency and high power devices. Under an alcohol concentration of 0.8% and a substrate temperature of 850 °C, high quality diamond films deposited on alumina are obtained by hot filament chemical vapor deposition (HFCVD) method using the optimum parameters determined by an infrared spectroscopic ellipsometer. Prior to the deposition of diamond film, carbon ions are implanted into alumina wafers to release the residual stress between interfaces. The measurement results indicate that dielectric properties and the thermal conductivity of diamond film/alumina composites are improved further with the increase of diamond coating. When the thickness of diamond coating is up to 100 μm, dielectric constant and dielectric loss of diamond film/alumina composite are 6.5 and 1.1 × 10^− 3, respectively. However, a thermal conductivity of 3.98 W/cm·K is obtained.     

电爆炸过程中金属丝电阻变化规律的仿真分析

探讨了电爆炸过程中金属丝相关参数的变化规律,建立了金属丝电阻在气化前的PSpice模型,得到了电容器初始电压由10 kV到20 kV、回路电感由3.9μH到10.8μH、金属丝直径由0.3 mm到1 mm变化时,金属丝电阻变化的仿真结果。对仿真结果分析表明：初始参数影响金属丝上的能量沉积,决定着金属丝的电阻变化过程以及金属丝完全气化所需要的时间。     

基于EMTP/ATP的输电线路合闸过电压仿真分析

为研究高压输电网络中空载合闸产生的过电压对电气设备的安全运行的影响,以某段500 kV输电线路为研究对象,分析系统产生合闸过电压的机理,建立基于频率的J.MARTI型等值线路分布参数计算模型,运用电力系统电磁暂态仿真分析软件(EMTP/ATP)对500 kV输电线路合闸过电压进行分析.仿真结果表明:在非同期条件下,在输...     

Accelerating geospatial analysis on GPUs using CUDA

Inverse distance weighting (IDW) interpolation and viewshed are two popular algorithms for geospatial analysis.IDW interpolation assigns geographical values to unknown spatial points using values from ...     

The design and analysis of unequal error protection fountain coding for multiple source networks over binary erasure channels

A novel network model of multiple source fountain coding is developed and a novel class of generic multiple source fountain codes with unequal error protection(UEP)property is proposed.The And–Or tree analysis technique is generalized to analyze the asymptotic performance of the proposed codes and a joint optimization method employing both linear and nonlinear programs is developed to optimize the degree distributions.Furthermore,we propose three basic methods to achieve UEP property and the performance of each method is discussed.We employ these analytical results and optimization method to design and discuss several UEP codes with two and four sources for different application scenarios.Simulation results verify that the proposed codes can be applied to the networks with any number of sources and can provide strong UEP property in various ways based on the proposed three basic methods.     

管道机器人无线发射装置磁场分布研究

针对管道机器人无线通信定位精度低和距离近的问题,提出一种管道机器人发射装置的并行多级线圈结构,提高空间中电磁线圈的磁场发射强度.利用ANSYS对不同匝数的单级线圈进行仿真,仿真结果表明在线圈激励电压一定的情况下,线圈产生的磁场的强度与线圈匝数无关;在符合技术等指标要求下,线圈的产生的场强大小与线圈的级数成正比关系.     

三维点云模型特征张量描述符的构造及自相似性分析

三维模型局部自相似性是物体形状分析中的一个基本问题,其中,局部形状描述符的构建对自相似性分析的最终结果至关重要.针对此问题,提出了一种基于张量融合特征描述符的自相似性分析方法.首先利用相关面和反向点对点云模型进行形状直径函数(shapediameterfunction,SDF)的近似计算;然后利用谱聚类对模型进行过分割成模型子块,由K近邻(K-nearest neighbor, KNN)邻域点的SDF、形状指数(shape index, SI)和高斯曲率(Gauss curvature,GS)矩阵构造三维特征张量;最后利用张量范数构造映射得到形状描述符,并定义相似性度量分析模型子块之间的自相似性.对几种最新的方法(包括部分匹配和显著性检测)进行了实验,无论是直观视觉效果,还是相似性测度和相对误差上的评价指标,结果均表明,该方法可有效地对形状进行描述,提高了点云模型相似子块的识别精度.     

Bit-level color image encryption algorithm based on coarse-grained logistic map and fractional chaos

A novel color image encryption algorithm based on coarse-grained fractional chaotic system signals is proposed in this paper. First, color images are divided into three channels, which are encrypted based on the corresponding three states of the chaotic system. Second, the chaotic systems are defined as fractional chaotic, in which the fractional order enlarges the parameter space. Third, the fractional chaotic signals are handled with unfixed coarse-grained methods instead of being utilized directly. In addition, the original image and the chaotic signals are divided into bit signals from the pixel values, and the high and low bits are encrypted, respectively. To demonstrate the effectiveness and robustness of the proposed color image encryption algorithm, its properties, including the key space, information entropy, correlation analysis, key sensitivity, and resistance to differential attacks, are provided using a numerical simulation.