Design and experimental realization of a robust decentralized PI controller for a coupled tank system

This paper presents design and realization of a robust decentralized PI controller for regulating the level of a coupled tank system. The proposed controller is designed based on a predefined reference transfer function model in which we adopt a frequency matching of actual and reference models. Realization of control algorithms for a multivariable system is often complicated owing to uncertainties in the process dynamics. In this paper, initially a frequency response fitting model reduction technique is adopted to obtain a First Order Plus Dead Time (FOPDT) model of each higher order decoupled subsystem. Further, using the obtained reduced order model, the proposed robust decentralized PI controller is designed. The stability and performance of the proposed controller are verified by considering multiplicative input and output uncertainties. The performance of the proposed robust decentralized controller has been compared with that of a decentralized PI controller. To validate the performance of the proposed control approach, real-time experimentation is pursed on a Feedback Instrument manufactured coupled tank system.     

CTS凝胶球表面印迹钼酸根吸附材料的制备

以壳聚糖(CTS)为基材,钼酸根离子为印迹离子,制备了一种新的CTS表面阴离子印迹凝胶球。以Mo(Ⅵ)的吸附量作为评价指标,对凝胶球的制备条件进行了优化。结果表明,当CTS质量分数为2%,凝固浴温度为20℃,钼酸铵和三乙醇胺的质量分数分别为2%和11%,热处理温度为60℃,洗脱剂NaOH的浓度为8.0g/L时,所制备的凝胶球吸附性能较佳。与不添加印迹阴离子的壳聚糖凝胶球相比,这种CTS表面阴离子印迹凝胶球吸附容量有了大幅度提升。     

FACTS元件对距离保护产生的影响分析

灵活交流输电系统(FACTS)装置如统一潮流控制器(UPFC)、晶闸管可控移相器(TCPST)、晶闸管可控f}5联电容补偿器(TCSC)和储能元件等设备的装设将对继电保护尤其是距离保护产生很大的影响。文中分析TCSC、UPFC、TCPST和储能元件对距离保护产生影响的决定性因素。     

专用集成电路设计中的时钟偏移分析

目前的专用集成电路设计中，时钟偏移对同步数字电路的影响越来越大，它也越来越受到高速电路设计者的关注。因此如何解决它给电路带来的不利影响成了设计中的重要挑战。本文分析了时钟偏移的产生机理，然后提出了怎样使用CTS在时钟树中插入不同驱动能力的缓冲器，以平衡时钟网络，最后还分析了如何利用有用的时钟偏移来改善电路的时序。     

新型CTS阵列天线的设计及仿真

提出一种新型的CTS(Coaxial Transverse Stub)阵列天线—CCTCS(Coaxial Continuous Transverse Conical Stub)阵列天线。天线由串联馈电单元组成,各单元采用圆锥状同轴开槽结构,具有成本低、易加工和易调节的特点。设计一个十单元的阵列天线模型,并通过有限积分数值方法对该阵列计算仿真,结果表明,相对于传统的CTS阵列,CCTCS阵列在满足全向性、低驻波、垂直极化和阻抗匹配的同时,工作带宽和旁瓣电平都有较好的改善。     

SolidWorks二次开发技术在风洞试验中的应用

本文采用VB对SolidWorks建模软件进行二次开发,建立一套形象直观的风洞捕获轨迹试验三维可视化系统。用VB 对SolidWorks 二次开发的轨迹显示系统中,采用OLE自动化技术,把VB 编写的应用程序作为客户程序,把应用软件SolidWorks 作为服务程序,用客户程序驱动服务程序完成SolidWorks 相应的操作。显示软件根据位姿信息对外挂物模型进行位姿变换,从而在运功分析的同时动态模拟外挂物的运动。运动分析完后,并且可以回放运动过程,实现了运动分析的可视化仿真。     

大型硫磺回收装置尾气提标单元问题分析及对策

介绍了大型硫磺回收装置尾气提标单元的运行现状及络合铁脱硫工艺的特点。阐述了尾气提标单元在实际生产过程中遇到的脱硫反应器填料层积硫、压滤机效率及循环溶液质量控制等问题,并详细分析了引起的原因。采用增设脱硫反应器跨线、更换填料及增大溶液循环量等方法,在非停工状态下彻底解决了填料层积硫问题。尾气提标部分反应器填料压降在合理范围内,且排放尾气中SO_2质量浓度≤10 mg/m~3,远低于国家最新环保标准,可为同类装置的技术改造提供参考。     

Fatigue crack propagation behavior in STS304 under mixed-mode loading

The use of fracture mechanics has traditionally concentrated on crack growth under an opening mechanism. However, many service failures occur from cracks subjected to mixed-mode loading. Hence, it is necessary to evaluate the fatigue behavior under mixed-mode loading. Under mixed-mode loading, not only the fatigue crack propagation rate is of importance, but also the crack propagation direction. In modified range 0.3≤a/W≤0.5, the stress intensity factors (SIFs) of mode I and mode II for the compact tension shear (CTS) specimen were calculated by using elastic finite element analysis. The propagation behavior of the fatigue cracks of cold rolled stainless steels (STS304) under mixed-mode conditions was evaluated by using K_I and K_II(SIFs of mode I and mode II). The maximum tangential stress (MTS) criterion and stress intensity factor were applied to predict the crack propagation direction and the propagation behavior of fatigue cracks.     

IEEE 802.11无线局域网中分布式协调功能的改进

结合无线局域网和TCP的特点提出了一种改进算法,当AP向无线节点发数据包时,无线节点用一个小的数据包(如:TCP层的ACK等)来代替CTS,这样可以避免无线节点单独发送小数据包,从而提高无线信道的利用率和无线网络的吞吐率。从试验结果可以看出,改进后的DCF协议不仅提高了信道的利用率和无线局域网的性能,而且更好的维护了无线节点间的公平性。     

双忙音多址接入-Ad Hoc网络中的多址接入控制机制的研究

在Ad Hoc网络中,隐藏终端和暴露终端的存在,严重影响了网络的通信能力。但是通常只采用RTS／CTS对话的MAC层机制不能完全解决隐藏终端和暴露终端的影响,正如单纯的分组侦听的MAC机制在全连通的网络中并不安全一样。为了解决这些问题,介绍一种新的MAC层协议——双忙音多址接入(DBTMA)机制。他的运行借助2个窄带带外忙音。通过使用RTS分组和接收端的接收忙音完全解决了隐藏终端的影响,接收端的CTS分组和接收忙音解决了暴露终端的影响。发送端建立的忙音保护了RTS分组,提高了接收RTS成功的概率,因此也就提高了吞吐量。