发动机初级工况对冷却夹套隔片损伤影响分析

针对可重复使用液体火箭发动机推力室冷却夹套隔片的损伤问题,为确保发动机的工作寿命,对建立了冷却夹套隔片的夹芯梁结构模型、粘塑性模型和细化损伤模型,发动机起动过程中初级工况给冷却夹套隔片损伤发展的影响进行了仿真计算。结果表明:初级工况过高,压力等性能参数振荡明显,振幅也较大,但引起的冷却夹套隔片损伤较小;初级工况选择过低,引起的冷却夹套隔片损伤较大,且压力等性能参数振荡也比较明显,但振幅较小。通过对比分析给出了用于发动机起动的合适初级工况,采用此工况使发动机起动过程中引起的损伤较小,而且压力等性能参数的振荡也较小。     

基于卷取温度预测的层流冷却优化控制模型

卷取温度对带钢的金相组织影响很大,是决定成品带钢加工性能、力学性能、物理性能的重要工艺参数之一;层流冷却过程具有强非线性、不确定性、时变的特点,采用传统的基于传热机理和统计分析的建模方式难以满足卷取温度优化控制要求;针对某钢铁企业热轧板厂卷取温度控制过程中存在的问题,建立了基于神经网络的卷取温度预测模型,综合考虑多种因素对卷取温度的影响,将该模型预测值与目标卷取温度值的偏差作为原有前馈模型的输入,以提高前馈补偿的控制精度;仿真结果表明,模型预测精度高,具有在线应用前景.     

Adaptive control of a CSTR with a neural network model

An adaptive control algorithm with a neural network model, previously proposed in the literature for the control of mechanical manipulators, is applied to a CSTR (Continuous Stirred Tank Reactor). The neural network model uses either radial Gaussian or “Mexican hat” wavelets as basis functions. This work shows that the addition of linear functions to the networks significantly improves the error convergence when the CSTR is operated for long periods of time in a neighborhood of one operating point, a common scenario in chemical process control. Then, a quantitative comparative study based on output errors and control efforts is conducted where adaptive controllers using wavelets or Gaussian basis functions and PID controllers (IMC tuning with fixed parameters and self tuning PID) are compared. From this comparative study, the practicality and advantages of the adaptive controllers over fixed or adaptive PID control is assessed.     

Exact optimal solution for a class of dual control problems

This paper considers a discrete-time stochastic optimal control problem for which only measurement equation is partially observed with unknown constant parameters taking value in a finite set of stochastic systems. Because of the fact that the cost-to-go function at each stage contains variance and the non-separability of the variance is so complicated that the dynamic programming cannot be successfully applied, the optimal solution has not been found. In this paper, a new approach to the optimal solution is proposed by embedding the original non-separable problem into a separable auxiliary problem. The theoretical condition on which the optimal solution of the original problem can be attained from a set of solutions of the auxiliary problem is established. In addition, the optimality of the interchanging algorithm is proved and the analytical solution of the optimal control is also obtained. The performance of this controller is illustrated with a simple example.     

混合液温度流量解耦控制算法及系统虚拟

针对一种具体的混合液温度流量非线性控制问题，文中提出了一种解析方式的解耦控制算法。采用MatLab对算法的仿真表明，这种解耦控制算法具有良好的解耦和控制效果。为全面分析该算法，设计了交互式实时混合液温度流量解耦控制系统虚拟软件，该软件的使用结果说明，这种算法可以很好地解决这种解耦控制问题。     

图书馆温湿度智能控制系统研究与设计

针对当前高校图书馆智能化建设中温度调控和湿度调控彼此脱节的现象,设计了基于ZigBee的温度湿度采集系统,从而研究了某高校图书馆内温度和湿度的相关性,提出了该校图书馆内温度和湿度相互关系的经验公式,进而为综合调控图书馆内温度和湿度建立了理论基础。为解决图书馆内温度和湿度自动调控差的现状,在温湿度采集系统的基础上设计了软硬件协同运作的智能温度湿度控制系统,该系统作为该校图书馆智能化楼宇的建设的子系统已经取得了良好的实际运行效果。     

Application of nonlinear dynamic analysis to the identification and control of nonlinear systems-III. n-Dimensional systems

In two previous publications, the authors have shown that normal form theory, a method used extensively in dynamic analysis, can be applied in the structure identification of nonlinear systems. In particular, normal form theory bridges the gap between structure of a nonlinear, low order polynomial dynamical system and the behavior it is able to predict or represent. This is important because knowing a system's dynamic behavior automatically leads to a simple nonlinear normal form model that can be used for (nonlinear) control. Previously, only two-dimensional normal form models were derived. For this paper, simple, n-dimensional, low order polynomial dynamical models will be derived that can represent a nonlinear system with multiple steady states or a limit cycle in the operating region of interest. Using as a plant the nonisothermal Continuous Stirred Tank Reactor with consecutive reactions (A→B→C), it is shown that identification and control of this three-dimensional system using the aforementioned normal form models is feasible.     

圆筒型永磁动圈式直线电动机动态特性仿真

分析了永磁动圈式直线电动机的工作原理,给出了用于驱动电液比例阀的永磁动圈式直线电动机的数学模型,并采用Matlab/Simulink软件建立了该电动机的仿真模型。仿真结果表明,该电动机在位移指令为5 mm时的阶跃响应调节时间小于30 ms,具有较好的高频动态响应特性。     

一种双网络架构的煤矿监控系统

针对煤矿井下环境复杂和矿井检测节点、检测参数种类众多的情况,提出了一种双网络架构的煤矿监控系统。该系统根据监控对象的不同,采用不同的网络进行数据传输,视频流数据采用以太网传输,矿井环境监控数据采用CAN网传输;双网络共用同一条物理线路,具有所有监测对象整体组网、统一检测、网络利用率高等优点。     

DHP算法优化控制开发工具的设计与实现

针对目前自适应动态规划的研究中大多采用Matlab语言编程,存在代码执行效率低、使用不灵活等缺点,采用面向对象的编程技术和C++语言设计了一种基于双启发式动态规划算法(DHP)和执行依赖双启发式动态规划(ADDHP)算法的优化控制开发工具,介绍了开发工具的设计开发思路、工作流程、功能特点、主要界面和使用方法.将该工具用于三容液位实验装置的实时仿真控制,实验结果表明,该开发工具具有使用灵活、训练速度快、执行效率高等优点.     

Self-oscillating and chaotic behaviour of a PI-controlled CSTR with control valve saturation

The time response of a PI-controlled continuous stirred tank reactor (CSTR), where a first order irreversible reaction occurs, is analysed in this paper. The parameters of the PI controller and the saturation of the cooling water temperature flow are used as parameters to show that self-oscillations and chaotic dynamics can appear. The conditions under which self-oscillation occurs are investigated taking into account heat generation, heat removal and the variation of eigenvalues of the linearized system at the equilibrium points, respectively. Also, the appearance of a Silnikov type homoclinic orbit, giving chaotic dynamics, is realised. The existence of a new set of strange attractors with PI control has been verified and the sensitivity to the initial conditions is also analysed.     

煤矿电网三相五柱式消弧线圈改进型调谐方法

针对煤矿电网中三相五柱式消弧线圈采用谐振法调谐时存在谐振点难以确定导致电容电流测量存在误差的问题,提出了一种改进型调谐方法。根据调谐过程中阻尼率不变、脱谐度改变的特点,以总对地电导为导纳三角形固定边,可变总对地电纳和总对地导纳作为导纳三角形可变边,利用导纳角的变化计算电容电流。仿真与实验结果表明,改进型调谐方法较谐振法测量精度更高,且测量误差随着阻尼率的增大而减小。