Closed‐Loop Identification for Control of Linear Parameter Varying Systems

This paper deals with system identification for control of linear parameter varying systems. In practical applications, it is often important to be able to identify small plant changes in an incremental manner without shutting down the system and/or disconnecting the controller; unfortunately, closed‐loop system identification is more difficult than open‐loop identification. In this paper we prove that the so‐called Hansen scheme, a technique known from linear time‐invariant systems theory for transforming closed‐loop system identification problems into open‐loop‐like problems, can be extended to accommodate linear parameter varying systems as well. We investigate the identified subsystem's parameter dependency and observe that, under mild assumptions, the identified subsystem is affine in the parameter vector. Various identification methods are compared in direct and Hansen Scheme setups in simulation studies, and the application of the Hansen Scheme is seen to improve the identification performance.     

浅谈C语言中循环结构的教学--回答好循环结构的“三个问题”

循环结构是C语言程序设计中的重难点,其掌握情况对于后续章节的学习效果尤为关键。本文以什么是循环、何时需要使用循环以及如何使用循环三个问题为主线,通过精心选择的教学案例和灵活有效的教学方法来进行解答,以激发学生兴趣,培养编程思想。     

气升式环流反应器强制振荡周期对传质影响的研究

在同一反应器中比较了不同振荡周期下的气液传质特性,为最优强制振荡周期的确定提供了实验依据和分析基础。选择体积传质系数及气含率作为传质研究的主要评价指标,实验结果表明,动态操作下的传质效果明显优于稳态,而不同振荡周期传质效果也大不一样。在0.8~2.4m3h-1的气速范围内,由静压力、导流管顶部截面流体速度、全床气含率(及传质系数)周期性变化所确定的振荡周期TP、TV、TK比稳态操作下的全床平均传质系数分别提高了3.92%~27.3%,2.35%~24.5%,28.2%~43.3%。由反应器内全床平均气含率或传质系数确定的振荡周期TK是最佳振荡周期。     

一步法合成6-乙酰氨基-2-氨基- 4,5,6,7 -四氢苯并噻唑

本文以4-乙酰氨基环己酮为原料,采用一步成环工艺合成6-乙酰氨基-2-氨基-4,5,6,7-四氢苯并噻唑,研究了反应条件及影响因素,产品红外光谱及物性参数与文献报道相符。此合成方法操作简单,工艺条件易控制,产物收率高。     

有界闭域上的线性赋值循环终止性分析

对有界闭域上的线性赋值循环程序终止性问题进行研究.利用Jordan 标准型技术将原循环程序的终止性问题约减为终止性等价的具有简单结构的循环程序的终止性问题.证明了当线性迭代映射满足一定条件时,该类循环程序不可终止的充分必要条件是：迭代映射在有界闭域上有不动点或周期轨.     

Frequency analysis and compensation of valve stiction in cascade control loops

Valve stiction is often a common problem in control loops and stiction induced oscillation is the main cause of poor performance in control systems. Cascade control is extensively applied in process industry as an effective strategy to restrain disturbances and compensate process nonlinearities. In recent years many studies have been performed on the detection and quantification of valve stiction in single feedback control loops. However, there is a lack in developing a mechanism which can analyze stiction induced oscillation in cascade control loops. This work focuses on the frequency analysis of stiction induced oscillations in cascade control loops and proposes a mechanism of oscillation compensation through outer and inner controller tuning. The effect of oscillation compensation by changing control strategies is also discussed. The theoretical analysis is evaluated through simulation examples and a pilot-scale flow-level cascade control experiment.     

基于Matlab闭环直流调速系统的分析与仿真

论文通过对单闭环直流调速系统的介绍,阐述和分析了自动控制系统的一般步骤与方法,并给予解决采用常规比例调节器为电压放大和电压比较环节时存在的问题的控制方案,同时通过软件MATLAB进行了实验验证,结果表明控制方案可行,效果良好.     

基于FPGA的自动变模控制感应加热电源全数字锁相环研究

针对感应加热电源频率跟踪设计中传统锁相环电路设计复杂、跟踪速度慢、锁相频带窄、单独模块设计修改繁琐等问题,提出一种基于FPGA的自动变模控制感应加热电源全数字锁相环,即拓展锁相环中心频率频带和采用变模控制实现快速频率跟踪.应用SOC技术完成系统设计,并进行典型频带的计算机仿真.仿真结果证实了该设计具有宽范围的锁相能力及快速精确的频率跟踪性能,满足感应加热电源对负载频率变化的快速跟踪要求.     

两液相生物反应器研究进展

介绍了两液相反应器的进展及存在问题，两液相反应器仍处于试验阶段，其主要问题是生物催化剂在界面的聚集损失活性等。     

Controller design for nonlinear systems using the Contoured Robust Controller Bode plot

In this paper, we develop the Contoured Robust Controller Bode (CRCBode) plot and demonstrate its use in the design of robust controllers for nonlinear single‐input single‐output (SISO) systems. The CRCBode plot shows contours (level sets) of a robust performance quantity on the Bode magnitude and phase plots of the controller. An iterative frequency domain loop‐shaping design approach is employed to eliminate all intersections of the controller frequency response with certain ‘forbidden regions,’ indicating that a standard SISO robust stability and performance criterion is satisfied. Nonlinearities are accounted for by avoiding the maximum forbidden regions over a structured uncertainty set consisting of linearizations of the system dynamics about several operating points. We demonstrate this technique by designing and experimentally verifying a flow‐rate controller for a butterfly‐valve based liquid cooling system, which is robust to valve nonlinearities and flow disturbances. Finally, we compare this compensator with one generated using an automated H _∞ synthesis algorithm and discuss the advantages of the CRCBode approach. Copyright © 2013 John Wiley & Sons, Ltd.