政府公共服务和社会治理中物联网技术的应用

随着时代的进步和社会经济的发展,我国开始致力于服务型政府的创建工作,通过物联网技术的应用,可以促使政府公共服务能力和社会管理能力得到有效提升.它可以对目前城市管理系统资源进行整合,然后将政务领域应用开展于物联网统一的公共平台上,具有一系列的优势.本文简要分析了政府公共服务和社会治理中物联网技术的应用,希望可以提供一些有价值的参考意见.     

CDMA2000网络优化及典型掉话案例分析

网络覆盖状况是衡量移动通信网络性能优劣的关键,CDMA2000网络的覆盖、容量和质量相互制约。本论文介绍了CDMA2000网络优化流程,面临的挑战,路测中需重点观察的指标,常见的掉话原因,对典型的掉话案例越区覆盖进行分析,对从事网络优化工作者有一定的借鉴意义。     

用于局域网的网络嗅探器的设计

目前,世界上主流的嗅探器都是以捕获数据包为其核心技术,而对于抓包过程有两种常见的机制,第一种是常见的UNIX／LINUX内核本身所具有的抓包功能。第二种是使用第三方软件和抓包驱动来实现抓包功能。本文根据网络嗅探的技术、原理、方法做出详细的论述,同时,讨论了现在使用较为广泛的嗅探软件与技术,然后,通过进行软件功能需求分析,我们论述了一个嗅探技术的新思路,用它来帮助网络管理人员对局域网进行监控。     

关系数据库技术在计算机网络设计中的运用

随着我国社会经济建设水平的不断提高和计算机网络技术的推广普及,关系数据库技术在计算机网络设计中的运用成为社会各领域关注的焦点,本文将从关系数据库技术的角度出发,结合计算机网络设计的实际,对关系数据库技术在计算机网络设计中的运用进行深入的研究和探讨。     

Decentralized weighted control for a class of large‐scale systems with multi‐modes

In this paper, the control synthesis problem for a class of large‐scale systems with multi‐modes that are called large‐scale switched systems is addressed. By introducing the concept of decentralized switching signal and the relevant decentralized average dwell time, the asymptotic stability and weighted ?₂ gain performance are investigated. It should be noted that the decentralized switching covers general switching cases for large‐scale switched systems, namely, it admits both time‐dependent switching signal and arbitrary switching signal blended in the decentralized switching. Then, on the basis of the analysis results, the decentralized weighted control scheme including state feedback controller gains and switching signals is studied. Several design algorithms are proposed to meet different controller design problems. Finally, numerical examples are provided to illustrate theoretical findings within this paper. Copyright © 2013 John Wiley & Sons, Ltd.     

关联维数在往复压缩机气阀故障诊断中的应用

针对传统方法难以有效进行往复压缩机气阀故障诊断的现状,提出了应用关联维数对往复压缩机气阀故障进行诊断的方法。通过对气阀常见故障类型的诊断,表明关联维数可以有效地分析出往复压缩机气阀的常见故障。     

纳米级无机粒子对聚乙烯的增强与增韧

对μｍ级ＣａＣＯ３、ＴｉＯ２和ｎｍ级ＳｉＣ／Ｓｉ３Ｎ４粒子填充ＬＤＰＥ的性能进行了研究。实验证明，μｍ级粒子对ＬＤＰＥ虽无明显的增强增韧作用，但也未使基体的机械性能大幅度下降。ｎｍ级ＳｉＣ／Ｓｉ３Ｎ４对ＬＤＰＥ有较大的增强增韧作用，在５％质量分数时冲击强度出现最大值，缺口冲击强度达５５．７ｋＪ／ｍ２为纯ＬＤＰＥ的２０３％；伸长率到６２５％时仍未断裂，为纯ＬＤＰＥ的５００％，但熔体流动速率急剧下降，仅为纯ＬＤＰＥ的２６％，当含量在３％和１５％质量分数时，熔体流动速率分别为纯ＬＤＰＥ的３３７％和１５１％。     

Observer‐based H ∞ output tracking control for networked control systems

This paper is concerned with observer‐based H _∞ output tracking control for networked control systems. An observer‐based controller is implemented through a communication network to drive the output of a controlled plant to track the output of a reference model. The inputs of the controlled plant and the observer‐based tracking controller are updated in an asynchronous way because of the effects of network‐induced delays and packet dropouts in the controller‐to‐actuator channel. Taking the asynchronous characteristic into consideration, the resulting closed‐loop system is modeled as a system with two interval time‐varying delays. A Lyapunov–Krasovskii functional, which makes use of information about the lower and upper bounds of the interval time‐varying delays, is constructed to derive a delay‐dependent criterion such that the closed‐loop system has a desired H _∞ tracking performance. Notice that a separation principle cannot be used to design an observer gain and a control gain due to the asynchronous inputs of the plant and the controller. Instead, a novel design algorithm is proposed by applying a particle swarm optimization technique with the feasibility of the stability criterion to search for the minimum H _∞ tracking performance and the corresponding gains. The effectiveness of the proposed method is illustrated by an example. Copyright © 2013 John Wiley & Sons, Ltd.     

Robust consensus for uncertain multi‐agent systems with discrete‐time dynamics

This paper investigates robust consensus for multi‐agent systems with discrete‐time dynamics affected by uncertainty. In particular, the paper considers multi‐agent systems with single and double integrators, where the weighted adjacency matrix is a polynomial function of uncertain parameters constrained into a semialgebraic set. Firstly, necessary and sufficient conditions are provided for robust consensus based on the existence of a Lyapunov function polynomially dependent on the uncertainty. In particular, an upper bound on the degree required for achieving necessity is provided. Secondly, a necessary and sufficient condition is provided for robust consensus with single integrator and nonnegative weighted adjacency matrices based on the zeros of a polynomial. Lastly, it is shown how these conditions can be investigated through convex programming by exploiting linear matrix inequalities and sums of squares of polynomials. Some numerical examples illustrate the proposed results. Copyright © 2013 John Wiley & Sons, Ltd.     

均匀沉淀法制备AI／ZnS复合粒子

介绍了以硫代乙酰胺(TAA)和乙酸锌[Zn(Ac)2]为主要原料，在片状铝粉表面包覆一层ZnS，制备出包覆式复合粒子Al／ZnS，改变母粒子Al粉的加入量及反应温度，确定制备包覆完全致密复合粒子的最佳条件，通过SEM、XRD及粒度测试等分析方法对复合粒子进行表征。