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。     

集成安全分析的模型驱动软件开发方法研究

提出了一种集成安全分析的软件设计与开发新方法,该方法以MDA为基础框架,使用VMLsec建立软件安全属性的平台无关模型,使得在软件设计的早期就能够囊括更多的安全需求,从而降低后期开发的风险与成本,提高软件的复用性.     

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。     

基于HTTP请求的ORM性能优化研究

针对对象关系映射工具,提出一种性能优化方法,该方法使得对象关系映射工具通过统计在HTTP请求处理过程中加载的和实际使用的对象字段,在后续请求处理中仅加载必需的对象字段,从而提升应用程序持久层性能。将改进过的对象关系映射工具应用到开源电子商务示例应用程序XPETSTORE后,HTTP请求响应时间平均降低8%。