Robust observer–controller compensator design using the loop shaping design procedure and the algebraic method

This paper investigates robust observer‐controller compensator design using Vidyasagar's structure (VS). VS has a unit matrix parameter H similar to the Q parameter for the Youla–Kucera parameterization. VS can be designed based on the left coprimeness of the central controller in the H_∞‐loop shaping design procedure (H_∞‐LSDP) and therefore can preserve the intrinsic properties of the H_∞‐LSDP. This paper introduces algebraic methods to simplify the design of H in the VS controller by solving specific algebraic equations. In particular, the algebraic design of H can achieve two things. First, a dynamic H adjusts the tracking performance and yields the integral action. Second, a dynamic H rejects the input and output sinusoidal disturbances with known frequencies. These attributes are indications of the flexibility of the proposed method since the output‐feedback controller design of the H_∞‐LSDP cannot easily deal with such conditions. This paper discusses the achieved loop and the closed‐loop behavior of the system with VS, and also gives two numerical examples. The first example shows that the proposed method results in a better design in many aspects than the resulting from H_∞‐LSDP. The second example shows the application of the proposed method to rejecting input and output step disturbances, and input and output multiple sinusoidal disturbances, for which the H_∞‐LSDP can hardly be used. Copyright © 2009 John Wiley & Sons, Ltd.     

Attribute-based on-demand multicast group setup with membership anonymity

In many applications, it is desired to dynamically establish temporary multicast groups for secure message delivery. It is also often the case that the group membership information itself is sensitive and needs to be well protected. However, existing solutions either fail to address the issue of membership anonymity or do not scale well for dynamically established groups. In this paper, we propose a highly scalable solution for dynamical multicast group setup with group membership anonymity. In the proposed solution, scalability and membership anonymity are achieved via a novel design that integrates techniques such as ciphertext-policy attribute-based encryption (CP-ABE). In our design, multicast groups are specified through group member attributes. As these attributes are potentially able to be shared by unlimited number of group members, our proposed scheme scales well. Also, high level of membership anonymity is guaranteed such that every group member knows nothing but his own group membership only. The complexity of our proposed scheme in terms of computational overhead and ciphertext size is O(n), where n is the number of attributes and independent to the group size.     

基于LabVIEW的空调水系统优化控制策略研究

在对空调水系统中的压差控制与温差控制两种控制策略进行分析后,为提高系统节能效果,将串级控制方法引入到空调水系统控制中;以西安建筑科技大学变风量空调实验室内的冷冻水系统为对象,提出用最小二乘法辨识串级回路主、副环的传递函数模型,并在此基础上,基于LabVIEW软件对控制系统进行仿真分析和实验研究;仿真和实验结果证明了串级控制策略在空调水系统控制中的有效性和良好的应用价值。     

雷达视频回波信号实时采集、压缩转发装置

介绍了一种基于FPGA和DSP的六通道雷达视频回波实时信号采集、压缩转发装置,该装置单通道采样率为20MSPS,采样精度为12bit,采集后的数据经过DSP压缩处理后再转化为2Mbps的PCM码流,实时发送给遥测发射机进行遥测下传和实时检测;并对相位一致性控制、基于流水线的数据处理方法等关键技术做了详细介绍;该装置已成功应用于某飞行器综合匹配试验,其性能和指标均优于应用要求。     

面向数字媒体技术专业的数字化学习平台建设

数字媒体技术专业通过数字化学习平台,为教师和学生、学生与学生、学生与教学资源间的互动提供了一种新的更有效的交互方式,也让整个教育方式更加高效。结合数字媒体技术专业特点和数字化学习平台应用优势,对数字媒体专业数字化学习平台建设进行系统阐释。     

实时数据库在冷轧厂的应用

在分析实时数据库的基础上,采用工业实时关系型数据库搭建出了冷轧系统网络构架,并给出其主要功能模块;最后实现动态数据传送、显示及历史数据采集的具体应用。该系统有助于提高冷轧企业的生产管理水平和生产效率,使整个企业成为一个整体上的信息系统。     

基于JPEG2000的码率控制算法的研究

码率控制是JPEG2000编码的重要过程,其算法的优劣直接决定着整个编码效率的高低和压缩图像质量的好坏.针对JPEG2000标准建议的码率控制算法的计算复杂度高且占用存储空间大的问题,提出了对隔行扫描编码通道算法ACPI的一种改进算法,包括添加估计斜率值阶段、逆转扫描分辨率水平顺序,以及逆转同等级子带扫描的顺序.实验结果表明,该算法有效地减少了一JPEG2000的计算复杂度和存储量,提高了性能.     

基于改进惯性权重的粒子群优化算法

惯性权重是粒子群算法中平衡全局搜索和局部搜索能力的重要参数,提出了一种基于改进惯性权重的粒子群优化算法。该算法在进化初期采用基于不同粒子不同维的动态自适应惯性权重策略,加快收敛速度,在进化后期采用线性递减权重策略,同时为防止陷入局优,适时引入混沌变异增加种群多样性。对5个典型测试函数的测试结果表明,NPSO在收敛速度、收敛精度、稳定性和全局搜索能力等方面比线性权重PSO(LDIWPSO)均有很大程度上的提高。     

Stability analysis for discrete delayed Markovian jumping neural networks with partly unknown transition probabilities

This paper addresses the analysis problem of asymptotic stability for a class of uncertain neural networks with Markovian jumping parameters and time delays. The considered transition probabilities are assumed to be partially unknown. The parameter uncertainties are considered to be norm-bounded. A sufficient condition for the stability of the addressed neural networks is derived, which is expressed in terms of a set of linear matrix inequalities. A numerical example is given to verify the effectiveness of the developed results.