用单片机控制多路萃取试剂流量

提出了一种由单片机控制的萃取试剂流量控制系统。该系统采用定容式计量腔,以时间作为控制变量,具有结构简单、制作要求不高、易满足耐腐蚀要求、不需机械动力和停电自动阻断试剂的特点。     

多路模拟量输入选择器的应用

针对一些老设备和一些现场需要进行优化监控的设备,提出利用一个模拟量输入端口和多个数字量输出端口实现对现场同类型模拟量的采集和监控的方法。     

张力辊与单机架间的物流控制在连轧机中的应用

首先阐述了前馈控制和物流控制的概念 ,然后分析了物流控制在连轧机的两单机架间的常规应用 ,最后提出一种将物流控制应用于张力辊与单机架的方法 ,并说明了它的优点。     

Robust Control of Spacecraft Formation Flying

In this paper, a robust control scheme for two spacecraft in formation subjected to time-variant external disturbances in the space environment was developed. The proposed controller consists of two parts, the first part is for the nominal system without disturbances and the second part is to compensate for effects of system disturbances. A dynamic relative motion error model was established to design the second part of the controller and to analyze the stability of the closed-loop system using Lyapunov stability theory. Furthermore, the robustness of proposed control method to the system disturbances is analyzed based on robust control theory. It is proven that the relative motion error of two spacecraft in formation is uniformly ultimately bounded under the proposed controller for the assumed disturbances in the dynamic model.     

Coupled and Decoupled Numerical Modeling of Flow and Morphological Evolution in Alluvial Rivers

Existing numerical river models are mostly built upon asynchronous solution of simplified governing equations. The strong coupling between water flow, sediment transport, and morphological evolution is thus ignored to a certain extent. An earlier study led to the development of a fully coupled model and identified the impacts of simplifications in the water-sediment mixture and global bed material continuity equations as well as of the asynchronous solution procedure for aggradation processes. This paper presents the results of an extended study along this line, highlighting the impacts on both aggradation and degradation processes. Simplifications in the continuity equations for the water-sediment mixture and bed material are found to have negligible effects on degradation. This is, however, in contrast to aggradation processes, in which the errors purely due to simplified continuity equations can be significant transiently. The asynchronous solution procedure is found to entail appreciable inaccuracy for both aggradation and degradation processes. Further, the asynchronous solution procedure can render the physical problem mathematically ill posed by invoking an extra upstream boundary condition in the supercritical flow regime. Finally, the impacts of simplified continuity equations and an asynchronous solution procedure are shown to be comparable with those of largely tuned friction factors, indicating their significance in calibrating numerical river models. It is concluded that the coupled system of complete governing equations needs to be synchronously solved for refined modeling of alluvial rivers.     

Robust Control of PVTOL Aircraft with a Nonlinear Optimal Control Solution

In this paper, a new nonlinear control strategy is proposed for hovering control of planar vertical takeoff and landing (PVTOL) aircraft. The control of this typical nonlinear, nonminimum-phase system is treated as a robust control problem. The robust control design is then converted to an equivalent optimal control design so that both stabilization and performance can be guaranteed. The primary contribution of this work is to provide a closed-form solution to the resultant nonlinear optimal control problem by employing a recently emerging nonlinear control approach, called the θ?D technique. The θ?D technique is based on optimal control theory and derived from an approximate solution to the Hamilton-Jacobi-Bellman equation via a perturbation process. This formulation will not only enhance the system performance but also simplify the design process in that robustness and optimality are integrated in one unified optimal control framework. Furthermore, the closed-form control law is very suitable for onboard implementation. The effectiveness of the proposed method is demonstrated by simulation results and comparison studies with a similar linearization based optimal control formulation.     

通讯方式控制多台变频器

本文介绍基于RS485接口实现变频器远程控制的方案，重点阐述利用SIEMENS CP340通讯模块和DANFOSS变频器通过ASCⅡ协议实现通讯控制的设计思想。     

步进炉控温系统鲁棒容错控制设计

步进炉是冶金领域广泛使用的多区段大型热处理设备,炉温在系统运行过程中存在时滞及不确定性,本文基于李雅普诺夫稳定性定理及LMI方法,针对炉温进行鲁棒稳定性分析及容错控制器设计。考虑实际系统中存在的测温传感器各种故障情况,引入多模态故障模型,实现了变增益控制器设计,得到了系统渐进稳定的充分条件。最后根据系统温度模型,借助Matlab的LMI工具箱进行仿真及验证,仿真结果表明所得定理能够保证系统具有鲁棒完整性。     

单嘴精炼炉流场及环流速度的水模型研究

经用水模型实验证明，单嘴精炼炉内钢水循环流动良好．上升和下降流股之间的相互干扰不大。增大气体流量和单嘴内径可显著增大环流量，但单嘴内径对环流速度影响不大。单嘴出口处钢水下降速度约为0.4～0.5m／s，对35t的单嘴精炼炉而言，其钢水环流量约为47～53t／min。     

大型同步电动机变频调速系统的模糊自适应控制

将模糊控制方法引入大型同步机交 -直 -交变频调速矢量控制系统中 ,以模糊控制器代替 PI控制的速度调节器。仿真实验表明 ,这几种模糊控制方法的各项指标基本上均优于传统 PI控制方式     

Erosion of Finite Thickness Sediment Beds by Single and Multiple Circular Jets

Sediment management in reservoirs with the help of water jets has motivated this work. Erosion caused by single and multiple submerged circular turbulent wall jets on a noncohesive sediment bed of finite thickness lying on a fixed boundary was studied with the help of laboratory experiments. Different combinations of jet diameter, jet separation, and sediment thickness to jet diameter ratio were tested. Results show a relation between dimensionless parameters characterizing the steady state bed profile and the densimetric particle Froude number F0 given by the velocity at the nozzle and the effective diameter and submerged specific density of the sediment. Evolution of scour with time confirms previous studies where the erosion was found to initially grow with the logarithm of time up to a certain reference time t*. This time, made dimensionless with a time scale tc involving the volume of sediment scoured and the rate of erosion, was also related to the densimetric Froude number. A comparison with studies regarding erosion of a semiinfinite layer of sediment is also presented.     

Nonlinear Control of Open-Channel Water Flow Based on Collocation Control Model

This paper is devoted to the nonlinear control of open-channel water flow dynamics via a one-dimensional collocation control model for irrigation canals or dam-river systems. Open channel dynamics are based on the well-known Saint-Venant nonlinear partial differential equations. In order to obtain a finite-dimensional model an orthogonal collocation method is used, together with functional approximation of the solutions of Saint-Venant equations based on Lagrange polynomials. This method can give a more tractable model than those obtained from classical finite-difference or finite-element methods (from the viewpoint of both state dimension and structure), and is well suited for control purposes. In particular it is shown how such a model can be used to design a nonlinear controller by techniques of dynamic input–output linearization with the goal of controlling water levels along an open-channel reach. Controller performance and robustness are illustrated in simulations, with a simulated model for the canal chosen as more accurate than the one used for control design.     

Optimization of Multiple Reservoir Networks for Sedimentation Control

An optimal control methodology is developed to evaluate reservoir management policies that minimize sediment scour and deposition in multiple-reservoir river networks. Consideration is given to adverse effects occurring in both reservoirs and rivers of a hydraulic network. The sedimentation problem is formulated as a discrete-time optimal control problem in which a successive approximation linear quadratic regulator optimization scheme is coupled with the U.S. Army Corps of Engineers HEC-6 sediment transport simulation model. Operational constraints imposed on reservoir storage levels and releases are accommodated using either a bracket or hyperbolic penalty function method. The resulting model also allows the user to evaluate policies that alternatively maximize sedimentation or consider adverse effects only at specified locations. Comparisons of the computational efficiencies between the successive approximation linear quadratic regulator and differential dynamic programming methodology and between different penalty functions are performed. Capabilities of the model are demonstrated through applications to a hypothetical three-reservoir network and the Yazoo Basin river-reservoir network in Mississippi.     

单流板坯中间包内湍流抑制器对流场的影响

通过水力学模型实验,研究了湍流抑制器对单流板坯中间包内钢液流动的影响,并比较了有无湍流抑制器时中间包内钢液流动的特性。湍流抑制器使钢液由长水口注入中间包后再返回,从而消除了中间包短路流,发展了表面流,延长了滞止时间和平均停留时间,有利于中间包内夹杂物的去除。湍流抑制器与单挡坝的结构在控制中间包内钢液流动方面效果较好。     

步进梁热处理炉鲁棒优化控制研究

针对冶金领域广泛应用的大型步进梁热处理炉,采用基于热传导及离散化技术得到的状态空间模型,进行鲁棒稳定性分析及控制器设计.考虑系统运行过程中的非线性及不确定性,基于李雅普诺夫稳定性定理及LMI方法,给出了系统稳定的充分条件,并进行变增益控制器设计.对辨识得到的系统模型,借助Matlab的LMI工具箱进行仿真及验证,仿真结果表明所得定理能够保证系统具有鲁棒完整性.     

单流厚板坯中间包物理模拟研究和应用

为得到更加合理的50 t中间包控流装置,通过建立几何相似比1∶4的单流中间包水模型,采用物理模拟试验,研究了不同流量(1.09、1.24 m3/h)、长水口插入深度(25、50、75 mm)、挡坝高度(90、135 mm)以及长水口和堰距离(190、390 mm)等参数对中间包流场的影响.模拟结果表明,当响应时间更小时...     

连铸中间包内钢液流动特性及控流技术

中间包内钢液的流动状态对钢中夹杂物的去除效率影响较大。增加中间包容量可使铸坯内弧—侧Al2O3总量显著降低，在中间包使用挡墙和坝可减少内、外侧钢流温度差和拉漏发生率，去除钢中夹杂物。过滤器、湍流缓冲器和旋涡控制装置等相关技术的应用均提高了铸坯的清洁度。     

单个限位开关多点位置控制技术的应用

采用单个限位开关和PLC(或时间继电器),实现对近距离的多点位置控制。     

Robust Dynamic Sliding Mode Control of a Rotating Thin-Walled Composite Blade

This paper presents a robust control methodology for the dynamic response control of a rotating blade exposed to external excitations and modeling uncertainty. The blade is modeled as a tapered thin-walled beam with fiber-reinforced composite material. The dynamic response characteristics of a rotating composite beam are investigated; namely, ply angle, taper ratio, and various selected rotational speeds. To extend life and improve efficiency, a robust control methodology is implemented and structural tailoring composite properties are used. To this end, considering modeling uncertainties and external disturbance conditions, a sliding mode control is proposed and its performance and robustness are compared with the conventional linear quadratic Gaussian control.