一类不确定采样系统的鲁棒D控制研究

本文对一类范数有界不确定线性采样系统,提出了存在状态反馈控制律,使得闭环系统的所有极点均位于一给定的圆盘中且具有最优鲁棒H∞性能的一个充分条件。结合控制律反馈增益参数极小化的要求,建立一个具有线性矩阵不等式约束的凸优化问题,通过该问题的解决,可以构造一个具有较小反馈增益参数和给定要求的控制律,算例结果进一步表明,该控制器具有更好的扰动抑制性能。     

新型增益调度变结构控制器的性能比较研究

为了提高变结构控制系统的控制效率,从节省控制能耗、消除颤振、快速进入滑动模态、获取稳定滑动模态等基本要求出发,将变结构控制器设计成具有增益调度控制器参数的增益调度变结构控制器,并提出了增益调度变结构控制器的设计方法.通过选择不同的调度变量、调度变量函数以及调度变量的变化范围,给出6种不同的增益调度变结构控制器,并进行了仿真研究,以比较其控制性能.     

GUI在含典型非线性系统分析中的应用

非线性系统的分析远比线性系统为复杂,缺乏能统一处理的有效数学工具。在许多工程应用中,由于难以求解出系统的精确输出过程。应用Matlab的GUI开发的典型非线性对系统性能分析仿真软件所设计的程序具有良好的用户界面。用此软件可使典型非线性对系统性能的仿真分析变得非常快捷、方便,是工程分析和教学中的一个有效的辅助工具。     

Controller design for flexible structure vibration suppression with robustness to contacts

Model-based feedback control of vibration in flexible structures can be complicated by the possibility that interaction with an external body occurs. If not accounted for, instability or poor performance may result. In this paper, a method is proposed for achieving robust vibration control of flexible structures under contact. The method uses robust linear state feedback, coupled with a state estimation scheme utilizing contact force measurement. Uncertain contact characteristics are modelled by a sector-bounded non-linear function, such that state feedback gains can be synthesized using a matrix inequality formulation of the Popov stability criterion. A separation theorem is used to establish a robust H₂ cost bound for the closed loop system. Experimental results from a multi-mode flexible structure testbed confirm that vibration attenuation and stability can be maintained over a broad range of contact characteristics, in terms of compliance and clearance.     

Finite-time optimal tracking control for a class of nonlinear systems with prescribed performance

In this paper, a finite-time optimal tracking control scheme based on integral reinforcement learning is developed for partially unknown nonlinear systems. In order to realize the prescribed performance, the original system is transformed into an equivalent unconstrained system so as to a composite system is constructed. Subsequently, a modified nonlinear quadratic performance function containing the auxiliary tracking error is designed. Furthermore, the technique of experience replay is used to update the critic neural network, which eliminates the persistent of excitation condition in traditional optimal methods. By combining the prescribed performance control with the finite-time optimization control technique, the tracking error is driven to a desired performance in finite time. Consequently, it has been shown that all signals in the partially unknown nonlinear system are semiglobally practical finite-time stable by stability analysis. Finally, the provided comparative simulation results verify the effectiveness of the developed control scheme.     

Characterization and evaluating the mechanical performance of halloysite nanotubes reinforced acrylonitrile butadiene styrene/polycarbonate composites exposed to aggressive environmental conditions

Developing light weight polymer based composites dispersed with novel reinforcements which can function well in the presence of aggressive environments is an active research field in the materials engineering. Hence, in the current work, halloysite nanotubes (1 %, 2 %, 4 %, 6 %, 8 % and 10 % by weight) were reinforced into acrylonitrile butadiene styrene/polycarbonate blend and the role of reinforcing phases on the mechanical performance under aggressive environmental conditions has been evaluated. Hardness was measured as gradually increased in the composites with the increased content of the reinforcements. Impact strength of the composites was observed as increased in the composites up to 4 % reinforcement and further decreased. Increased strength was measured for the composite up to 2 % reinforcement. Ductility of the composites was decreased as reflected form the decreased % of elongation with the higher fraction of reinforcements due to induced brittleness. The composites were exposed to diluted sulfuric acid for 3 h and 6 h at 60 °C and then subjected to tensile loading. With the increased time of exposure, composites with 1 % and 2 % reinforcement exhibited relatively better performance.     

基于SSH架构的高职院校成绩管理系统的分析和设计

本文介绍了当前基于Struts2、Spring、Hibernate框架的高职院校成绩管理系统的分析和设计。     

EDA9033A在分布式风机性能测试系统中的应用

针对以单片机为核心的风机性能测试系统存在稳定性差、抗干扰能力差、精度低等问题,开发了以PLC为核心、采用互感式采集模块EDA9033A采集风机电参数的分布式风机性能测试系统,给出了该风机性能测试系统的结构,详细介绍了EDA9033A的硬件及软件设计。实际应用表明,EDA9033A采集的风机电参数结果稳定、快速、准确。     

TPC-H自动测试工具TPCHDriver的研究

TPC—H基准测试可以比较不同数据库系统之间的查询性能差别,它的测试结果已经成为评价DBMS和服务器的重要标准。该文开发了自动化的TPC—H测试工具TPCHDriver,该工具应用面向对象设计、Java语言开发,图形用户界面,实现了从数据装载到Power测试和Throughtput测试、生成测试报告整个过程的自动化。简述了TPC—H基准的测试模型、TPCHDriver程序的结构和主要功能,阐述了TPCHDriver的关键实现技术。     

基于节点性能估算的应用层组播算法

提出一种基于节点性能估算的应用层组播树构建和维护算法(PPE)。综合考虑节点的性能及其在组播树中的位置,尽可能使高性能的节点接近源节点,使低性能的节点接近叶子节点,以此来提高组播树的效率,降低端到端的延迟,减小链路压力和控制开销。仿真结果表明,PPE在大规模节点环境中能有效改善组播树的性能。