Finite-Time H∞ Control of Switched Nonlinear Systems under State-Dependent Switching

This paper investigates the finite-time H∞ control problem of switched nonlinear systems via state-dependent switching and state feedback control. Unlike the existing approach based on time-dependent switching strategy, in which the switching instants must be given in advance, the state-dependent switching strategy is used to design switching signals. Based on multiple Lyapunov-like functions method, several criteria for switched nonlinear systems to be finite-time H∞ control are derived. Finally, a numerical example with simulation results is provided to show the validity of the conclusions.

On similitude law of sub-systems

Based on Buckingham＇s π-Theorem, dimensional analysis has achieved considerable success over the past near-century. Model testing has long been a powerful tool in both scientific studies and engineering applications. However, the prototype objects are becoming more and more complicated nowadays, and many of the prototype systems can contain several sub-systems. The conventional theories on model-prototype similarity and dimensional analysis have only limited application since the π-Theorem itself does not distinguish between the original system and subsystems. This is particularly true in the field of structural dynamics, where the structure is often modeled as a multi-degree-of-freedom system. In this paper, we attempt to show that, if a system can be decoupled into several nontrivial subsystems, then, in each subsystem, the number of π-terms will be reduced and therefore simplify the model testing. On the other hand, if a system cannot be decoupled into subsystems, then using model testing with reduced π-term analysis, both experimentally and theoretically, may introduce severe errors.

Robust Finite-Time H∞ Filtering for ItôStochastic Systems

This paper investigates the problem of robust finite-time H∞ filter design for Itô stochastic systems. Based on linear matrix inequalities (LMIS) techniques and stability theory of stochastic differential equations, stochastic Lyapunov function method is adopted to design a finite-time H∞ filter such that, for all admissible uncertainties, the filtering error system is stochastic finite-time stable (SFTS). A sufficient condition for the existence of a finite-time H∞ filter for the stochastic system under consideration is achieved in terms of LMIS. Moreover, the explicit expression of the desired filter parameters is given. A numerical example is provided to illustrate the effectiveness of the proposed method.

Delay-Dependent Robust H∞ Control for Uncertain 2-D Discrete State Delay Systems Described by the General Model

This paper considers the problem of delay-dependent robust optimal H∞ control for a class of uncertain two-dimensional (2-D) discrete state delay systems described by the general model (GM). The parameter uncertainties are assumed to be norm-bounded. A linear matrix inequality (LMI)-based sufficient condition for the existence of delay-dependent g-suboptimal state feedback robust H∞ controllers which guarantees not only the asymptotic stability of the closed-loop system, but also the H∞ noise attenuation g over all admissible parameter uncertainties is established. Furthermore, a convex optimization problem is formulated to design a delay-dependent state feedback robust optimal H∞ controller which minimizes the H∞ noise attenuation g of the closed-loop system. Finally, an illustrative example is provided to demonstrate the effectiveness of the proposed method.

Robust Optimal H∞ Control for Uncertain 2-D Discrete State-Delayed Systems Described by the General Model

This paper investigates the problem of robust optimal H∞ control for uncertain two-dimensional (2-D) discrete state-delayed systems described by the general model (GM) with norm-bounded uncertainties. A sufficient condition for the existence of g-suboptimal robust H∞ state feedback controllers is established, based on linear matrix inequality (LMI) approach. Moreover, a convex optimization problem is developed to design a robust optimal state feedback controller which minimizes the H∞ noise attenuation level of the resulting closed-loop system. Finally, two illustrative examples are given to demonstrate the effectiveness of the proposed method.

网络化条件下的态势信息分发与Pub/Sub通信范型

探讨了网络化条件下态势信息分发的概念和机制。首先介绍态势信息分发的现状并分析其存在的不足;其次将发布/订阅(Pub/Sub)通信范型引入网络化态势信息分发机制之中,提出基于Pub/Sub网络化态势信息分发机制,分析其合理性和有效性;最后根据未来网络化战争的发展方向,预测其发展趋势。

MOOC平台下“Pub/Sub互动式”教学大纲设计的课程改革应用——以《果蔬保藏学》为例

文章分析了"互动式"教学大纲研究现状,阐述了MOOC(Massive Open Online Courses)平台的教学模式特性.以《果蔬保藏学》为例,从教学大纲的编制、"发布/订阅"、动态调整三个方面,研究MOOC平台下"Pub/Sub(Publish/Subscribe)互动式"教学大纲的设计与实施.

以教学大纲Pub/Sub双向互动模式为导向的课程探索——以河北工程大学《无线网络技术》课程为例

针对传统教学大纲编制存在的主要问题及局限性,本文从改革现行教学大纲的使用状况为切入点,将发布/订阅(Publish/Subscribe,Pub/Sub)消息传输模式创新性地引入到教学大纲编制中,建立了教学大纲Pub/Sub双向互动模式,有效解决了教学大纲编制过程中缺乏双向性、互动性、创造性、动态性的问题。为评价及验证该模式,本文采用了层次分析法,建立了教学大纲Pub/Sub双向互动模式评价指标体系,针对评价指标信息的灰色性问题,采用灰色理论建立了教学大纲Pub/Sub双向互动模式综合评价方法。在此基础上,结合河北工程大学通信工程专业《无线网络技术》课程的实际展开探索,本文给出了教学大纲Pub/Sub双向互动模式的实践路径。

基于“Pub/Sub互动式”教学大纲设计的食品学科实验课程改革

文章阐述了“互动式”教学大纲核心理念。研究了借鉴和引入具有“契约”机制作用的“发布/订阅(Publish/Subscribe,Pub/Sub)互动式”教学大纲的设计和使用方法,根据专业最相近原则,构建专业食品学科实验课程“一体化、三层次”新体系。

基于Pub/Sub模式的智能消息中间件研究

通过总结消息传递模式和消息队列模式,及其中都可用到的点对点通信方式和发布/订阅通信方式的优缺点,提出了一种基于Pub/Sub模式的智能消息中间件,并对该智能消息中间件的系统架构及工作流程进行了研究。此种消息中间件可以根据消息的不同类型来自动选择最佳的传递方式,以此来满足不同消息在及时性,高速性,可靠性等方面的不同要求,它适用于多种领域,尤其在企业应用集成中。

基于CPN的pub/sub系统中事件订阅的分析

提出了一种基于着色petri网(CPN)理论的pub/sub系统协议分析方法,并就一种p2p网络之上的pub/sub系统协议,用CPN对系统中的订阅事件的消息处理进行形式化描述和建模。用CPN Tools对模型进行模拟仿真,通过对模型的可达图进行分析,证明了协议具有活性、可达性和有界性等,验证了协议的可用性。

基于Pub/Sub模型的天地一体化网络移动性管理方法

天地一体化网络中,星基网络具有时变性,从而导致天地一体化网络难以采用传统地基网络体系完成终端管理。针对这一问题,提出低轨卫星或天基终端发生移动时主动更新位置信息,由低轨卫星充当天基终端的移动接入网关(MAG),由高轨卫星组成的网络充当天基网络的移动性管理代理(MMA),移动终端和低轨卫星的移动性控制信息由基于Pub/Sub的模型来管理,以维护MAG之间和MAG与地面网关(GW)之间的隧道,从而减少星间移动性管理消息交互和移动过程对传统PMIP网络的LMA和HA的依赖,提升了移动性管理的效率和可靠性。仿真结果表明,与传统MIP相比,基于Pub/Sub模型的天地一体化网络移动性管理方法以少量信令开销为代价,取得了传输时延方面的明显优势。

基于Publish/Subscribe系统的角色访问控制策略

Publish/Subscribe通信范型能很好的满足大型的分布式系统松散通信的需求,然而,安全问题往往被忽略,文章把Pub/Sub的通信范型与角色的访问控制相结合,用来实现Pub/Sub的安全通信,同时给出了用户与客体事件在不同域的通信策略,角色的引入减少了Pub/Sub系统的授权管理代价,同时增加了访问控制的安全性和灵活性。

基于无标度网络的Pub/Sub免疫路由

为避免Pub/Sub系统遍历路由带来的广播风暴,在基于无标度网络的Pub/Sub系统遍历路由过程中,引入病毒传播动力学的免疫思想,提出基于度的免疫遍历路由。通过设置节点度阈值δ,选择免疫节点控制消息的流向,避免全网遍历,降低广播开销。仿真实验结果表明,与洪泛法和Epidemic算法相比,该算法能更好地降低网络的遍历负载,增强网络的可扩展性。

基于内容的Pub/Sub系统中分发器网络自重构的研究

提出了提高基于内容的Pub/Sub系统健壮性和交互效率的系统自重构方法。该方法包括系统的恢复策略和系统的自组织策略。系统的恢复策略,预防了节点的意外崩溃造成的系统瘫痪;系统自组织策略,有效地降低了系统的事件交互成本,提高了基于内容的Pub/Sub系统的效率。自重构方法在基于内容的Pub/Sub系统SOES中得到了体现。

服务总线支持Pub-Sub模式的路由研究

近年来,随着电信行业业务应用的发展,对电信业务服务质量提出了更高的要求。面向服务的体系结构(SOA)提供面向业务的系统框架。采用SOA架构的电信业务系统能满足处理性能、稳定性、完整性及其智能化程度等因素上的高要求。本文以电信行业业务服务性能为目的,从SOA架构的核心基础设施企业服务总线(ESB)对服务路由的支持着眼,提供服务跨系统的Pub/Sub交互,在基础设施上满足服务性能需求,并应用到电信行业中。

OPC UA PUB/SUB模式的研究与实现

针对核电等工业现场设备对OPC UA Pub/Sub技术的需求,对OPC UA Pub/Sub规范进行了研究,分析OPC UA Pub/Sub模式的技术特点和应用场景,开发实现了符合规范的基于OPC UA服务器的Pub/Sub通讯模式。该通讯模式使用OPC UA Client/Server连接模式进行OPC UA Pub/Sub的配置,使用OPC UA Pub/Sub模式进行数据传输。与标准实现的应用进行通讯测试表明,该服务器具备OPC UA Pub/Sub数据传输能力。

Damping characteristics of friction damped braced frame and its effectiveness in the mega-sub controlled structure system

Based on energy dissipation and structural control principle, a new structural configuration, called the megasub controlled structure （MSCS） with friction damped braces （FDBs）, is first presented. Meanwhile, to calculate the damping coefficient in the slipping state a new analytical method is proposed. The damping characteristics of one-storey friction damped braced frame （FDBF） are investigated, and the influence of the structural parameters on the energy dissipation and the practical engineering design are discussed. The nonlinear dynamic equations and the analytical model of the MSCS with FDBs are established. Three building structures with different structural configurations, which were designed with reference to the conventional mega-sub structures such as used in Tokyo City Hall, are comparatively investigated. The results illustrate that the structure presented in the paper has excellent dynamic properties and satisfactory control effectiveness.

Present status and one upgrading method with a cold compressor of the EAST sub-cooling helium cryogenic system

Since 2006, the superconducting toroidal field（TF） coils of the Experimental Advanced Superconducting Tokomak（EAST） have been successfully cooled by supercritical helium at a temperature of 4.5 K and a pressure of 4 bara in eleven experiments. To obtain higher operating currents and magnetic fields it is necessary to lower the operating temperature of the TF coils.The EAST sub-cooling helium cryogenic system, with a warm oil ring pump（ORP）, was tested twice in cool-down experiments, which made the TF coils operate at 3.8 K. However, the long term operational stability of the sub-cooling system cannot be guaranteed because of the ORP＇s poor mechanical and control performance. In this paper, the present status of the EAST subcooling helium cryogenic system is described, and then several cooling methods below 4.2 K and their merits are presented and analyzed. Finally, an upgrading method with a cold compressor for an EAST sub-cooling helium cryogenic system is proposed. The new process flow and thermodynamic calculation of the sub-cooling helium system, and the main parameters of the cold compressor, are also presented in detail. This work will provide a reference for the future upgrading of the sub-cooling helium system for higher operation parameters of the EAST device.

Frequency of Cardiovascular Risk Factors in Systemic Lupus Erythematosus: A Case-Control Study in a Department of Internal Medicine in Sub-Saharan Africa

Background: The morbidity and mortality of systemic lupus erythematosus are largely due to accelerated atherosclerosis. This is partly related to the high prevalence of traditional cardiovascular risk factors. The aim of our study was to determine the frequency of these factors in lupus patients compared to a control population in a department of internal medicine. Methods: We realized a case-control study in patients with systemic lupus erythematosus according to ACR criteria in 1997. Patients were matched by age and gender with controls subjects without autoimmune disease. We studied the frequency of traditional cardiovascular risk factors in both populations. The study was done in the department of internal medicine of Aristide Le Dantec teaching Hospital, in Senegal, during the period from August 2017 to December 2018. The statistical analysis was performed with SPSS 23.0 software and the level of significance was retained for a p-value Results: We recruited 100 subjects including 50 patients and 50 controls. The mean age was 33.5 ± 11.3 years in cases and 33.3 ± 11.3 years in controls. Dyslipidemia was significantly associated with systemic lupus erythematosus (p = 0.009). Levels of triglycerides (p Conclusion: Traditional cardiovascular risk factors including dyslipidemia and hyperuricemia were more common in patients. Similarly, renal failure was associated with lupus.