DCS devices based non-linear process control system design for plants with distributed time-delay using particle filter

Remote control process system with distributed time-delay has attracted much attention in different fields.In this paper,non-linear remote control of a single tank process system with wireless network is considered.To deal with the distributed time-delay in a large-scale plant,the time-delay compensation controller based on DCS devices is designed by using operator theory and particle filter.Distributed control system(DCS)device is developed to monitor and control from the central monitoring room to each process.The particle filter is a probabilistic method to estimate unobservable information from observable information.First,remote control system and experimental equipment are introduced.Second,control system based on an operator theory is designed.Then,process system with distributed time-delay using particle filter is carried out.Finally,the actual experiment is conducted by using the proposed time-delay compensation controller.When estimating with the proposed method,the result is close to the case in which the distributed time-delay does not exist.The effectiveness of the proposed control system is confirmed by experiment results.

Load Frequency Control of Small Hydropower Plants Using One-Input Fuzzy PI Controller with Linear and Non-Linear Plant Model

This study presents an intelligent approach for load frequency control (LFC) of small hydropower plants (SHPs). The approach which is based on fuzzy logic (FL), takes into account the non-linearity of SHPs—something which is not possible using traditional controllers. Most intelligent methods use two- input fuzzy controllers, but because such controllers are expensive, there is economic interest in the relatively cheaper single-input controllers. A non- linear control model based on one-input fuzzy logic PI (FLPI) controller was developed and applied to control the non-linear SHP. Using MATLAB/Si- mulink SimScape, the SHP was simulated with linear and non-linear plant models. The performance of the FLPI controller was investigated and compared with that of the conventional PI/PID controller. Results show that the settling time for the FLPI controller is about 8 times shorter;while the overshoot is about 15 times smaller compared to the conventional PI/PID controller. Therefore, the FLPI controller performs better than the conventional PI/PID controller not only in meeting the LFC control objective but also in ensuring increased dynamic stability of SHPs.

Comparative Study of Linear and Non-Linear Controls of Three-Phase Shunt Active Filters for Improving the Quality of Electrical Energy

The aim of this work is to comparatively study two types of control of a three-phase shunt active filter (TSAF) in order to realize a system of depollution of electrical networks so as to improve the quality of electrical energy. We used two TSA control models which differ in the method of disturbed currents detection, one linear and the other non-linear. The results show that the non-linear control method, although with high calculation blocks, gives more promising results than the linear control method. When connecting a non-linear load (televisions, lamps, variable speed drives, etc.) directly to the public distribution network, the non-linear nature of the load causes the source current to be deformed due to the presence of harmonic currents and voltages. These harmonics thus generate a high reactive power, and therefore considerable electrical losses in the network. One of the solutions to reduce losses on the electricity grid is to incorporate an electronic circuit called a filter into the electricity grid. This work carried out a comparative study of two types of control of a three-phase shunt active filter (TSAF) in order to carry out a system for cleaning up electricity networks in order to improve the quality of electrical energy. We used two TSA control models that differ in the method of detecting disturbed currents, one linear and the other non-linear. The results show that the non-linear control method, although with high calculation blocks, gives better results than the linear control method.

Non-Linear Tank Level Control for Industrial Applications

Tank level control is ubiquitous in industry. The focus of this paper is on accurate liquid level control in single tank systems which can be actuated continuously and modulation of the level setpoint is also required, for example in cascade control loops or supervisory Model Predictive Control (MPC) applications. To avoid common problems encountered when using fixed gain or adaptive/gain scheduled schemes, an accurate technique based around feedback linearization and Proportional Integral (PI) control is introduced. This simple controller can maintain linear performance over the full operating range of a uniform tank. As will be demonstrated, the implementation overhead compared to a regular PI controller is negligible, making it ideal for industrial implementation. Implementation details and parameter identification for adaptive implementation are discussed. Simulations coupled with experimental results using a large-scale laboratory level control system using commercial industrial control equipment validate the approach, and illustrate its effectiveness for both level tracking and disturbance rejection.

Optimal variable structure control with sliding modes for unstable processes

In this work,a variable structure control(VSC)technique is proposed to achieve satisfactory robustness for unstable processes.Optimal values of unknown parameters of VSC are obtained using Whale optimization algorithm which was recently reported in literature.Stability analysis has been done to verify the suitability of the proposed structure for industrial processes.The proposed control strategy is applied to three different types of unstable processes including non-minimum phase and nonlinear systems.A comparative study ensures that the proposed scheme gives superior performance over the recently reported VSC system.Furthermore,the proposed method gives satisfactory results for a cart inverted pendulum system in the presence of external disturbance and noise.

A PID Sliding Mode Control for Ropeless Elevator Maglev Guiding System

In this paper, three different controllers are proposed and simulated for maglev guiding systems to have convenient and smooth elevator motion. The proposed controllers are PID, sliding mode, and PID sliding mode controllers. The advantages and disadvantages of the proposed controllers are discussed. Although, PID controller is fast, its response affected considerably by external disturbances. Unlike PID, the sliding mode controller is so robust, but its transient is unsuitable based on application conditions. However, an acceptable controller for ropeless elevator guiding system should guaranty the passengers safety and convenient. Consequently, the response of the system should be fast, robust, and without considerable overshoots and oscillations. These required advantages are compromised in the proposed parallel PID sliding mode controller. The affectivity of the introduced controllers for maglev guiding system is investigated through conducted simulations in MATLAB/Simulink environment. The obtained results illustrate that PID sliding mode controller is a so fast and robust controller for a ropeless elevator maglev guiding system.

Research on improved active disturbance rejection control of continuous rotary motor electro-hydraulic servo system

In order to meet the precision requirements and tracking performance of the continuous rotary motor electro-hydraulic servo system under unknown strong non-linear and uncertain strong disturbance factors,such as dynamic uncertainty and parameter perturbation,an improved active disturbance rejection control(ADRC)strategy was proposed.The state space model of the fifth order closed-loop system was established based on the principle of valve-controlled hydraulic motor.Then the three parts of ADRC were improved by parameter perturbation and external disturbance;the fast tracking differentiator was introduced into linear and non-linear combinations;the nonlinear state error feedback was proposed using synovial control;the extended state observer was determined by nonlinear compensation.In addition,the grey wolf algorithm was used to set the parameters of the three parts.The simulation and experimental results show that the improved ADRC can realize the system frequency 12 Hz when the tracking accuracy and response speed meet the requirements of double ten indexes,which lay foundation for the motor application.

Dynamic modelling and PFL-based trajectory tracking control for underactuated cable-driven truss-like manipulator

In recent years,an innovative underactuated robot was developed,named as underactuated cable-driven trusslike manipulator(UCTM),to be suitable in aerospace applications.However,there has been strong consensus that the stabilization of planar underactuated manipulators without gravity is a great challenge since the system includes a second order nonholonomic constraint and most classical control methods are not suitable for this kind of system.Furthermore,the complexity of the truss-like structure results in tremendous difficulty of computational complicacy and high nonlinearity during dynamic modelling in addition to controller design.It is paramount to solve these difficulties for UCTM's future applications.To solve the above difficulties,this paper presents a dynamic modelling method for UCTM and a trajectory tracking control method based on partial feedback linearization(PFL)that fulfills the control goal of moving UCTM from its original position to a desired position by tracking a given trajectory of the joint angles.To achieve this,a model equivalent method is proposed to make UCTM equivalent with a three-link manipulator in the sense of dynamic behavior.Then the Lagrangian equation combined with complex vector method is proposed in the dynamic modelling process of UCTM,which simplifies the derivation procedure.Based on the established dynamic model,a coordinate transformation method is proposed to transform the control force matrix into the conventional form of an underactuated system,so that the control force can be separated from the unactuated term.The PFL method in combination with the LQR control method is then proposed to realize the targets that the joint angles can track given desired trajectory.Simulation experiments are conducted to verify the correctness and effectiveness of the proposed methods.

Improvement of Dynamic and Steady Characteristics of Pneumatic Position Servo with Fuzzy-PI Control

This paper provided a fuzzy-PI control. It makes use of the advantages of fuzzy controller for dynamic characteristics, and the advantages of PI control for steady characteristics of pneumatic position servo. Experimental results show that positioning accuracy meets the conventional industrial needs, and prove that the fuzzy-PI controller to be correct and more effective than the usual PID controller. The control method improve the dynamic and steady characteristics of the system.

Dynamic Tracking Control of Space Robot Flexible Arm

An inverse dynamic model is deve1oped through further deduction from the dynamic model of a flexible arm based upon the lagrangian formula,and a dynamic non-linear tracking control scheme,which combines an inverse dynamic method with PD control and non-linear compensator,is proposed for flexible arms.Simulation reaults show this non-linear control scheme can put the flexible arm system under effective control and realize accurate trajectory tracking.

Control of Ideal Heat Integrated Distillation Columns

The operation of an ideal heat integrated distillation column (HIDiC) is addressed. Five kinds of control configurations, i.e. single-loop control, multi-loop control, multivariable internal model control (IMC), modified multivariable internal model control (MIMC) and nonlinear process model-based control (NPMC), are designed and applied to the process. Simulation results demonstrate that all of the above control configurations are valid for product quality control. NPMC control configuration is found to be the best one among all the alternatives. It can readily realize setpoint transitions and conduct effectively against external disturbances. MIMC control configuration ranks second in the row for its regulatory responses to feed composition disturbances with relatively extended setting time. Next comes from the multi-loop control configuration, which is more or less handicapped by its greater deviations and overshootings. IMC control configuration can not compete with the multi-loop control configuration because it is extremely sensitive to operating condition changes. Single-loop control configuration is the worst one among all the mentioned control configurations. Its responses for the uncontrolled end products are extremely sluggish.

A Suitable Active Control for Suppression the Vibrations of a Cantilever Beam

In our consideration,a comparison between four different types of controllers for suppression the vibrations of the cantilever beam excited by an external force is carried out.Those four types are the linear velocity feedback control,the cubic velocity feedback control,the non-linear saturation controller(NSC)and the positive position feedback(PPF)controller.The suitable type is the PPF controller for suppression the vibrations of the cantilever beam.The approximate solution obtained up to the first approximation by using the multiple scale method.The PPF controller effectiveness is studied on the system.We used frequency-response equations to investigate the stability of a cantilever beam.We notified that,there is a good agreement between the analytical solution and the numerical solution.

Duffing Oscillator’s Vibration Control under Resonance with a Negative Velocity Feedback Control and Time Delay

An externally excited Duffing oscillator under feedback control is discussed and analyzed under the worst resonance case.Multiple time scales method is applied for this system to find analytic solution with the existence and nonexistence of the time delay on control loop.An appropriate stability analysis is also performed and appropriate choices for the feedback gains and the time delay are found in order to reduce the amplitude peak.Different response curves are involved to show and compare controller effects.In addition,analytic solutions are compared with numerical approximation solutions using Rung-Kutta method of fourth order.

Optimum Control for Spread of Pollutants through Forest Resources

Pollution has become the most critical factor spread by forest resources through wood-based and non-wood based industries. In other words, pollution is omnipresent. In this paper, the major pollutants caused due to wood and non-wood based industries are discussed which are the primary resources of the forest in spreading the pollution. In order to study the impact of industrialization and associated pollution on forest resources, the system of non-linear ordinary differential equations is formulated. The controls are advised on both types of industries to reduce the pollution.

Modified Single Phase SRF d-q Theory Based Controller for DVR Mitigating Voltage Sag in Case of Nonlinear Load

This paper mainly concentrates on design of improved controller and its implementation based on single phase synchronous reference frame theory (SRFT) for Dynamic Voltage Restorer (DVR) compensating voltage sag particularly for nonlinear load. In case of single phase distribution line with nonlinear load, the complexity of controller’s design becomes more serious issue. The present single phase and/or three phase theories applicable to DVR shows poor response to restore voltage sag in case of nonlinear load due to presence of harmonics. Hence restoration of voltage sag in single phase nonlinear load connected system has been a serious concern. Therefore, new controller for DVR has been proposed incorporating effective design concept for fundamental component extraction in case of nonlinear load. The single phase SRFT based main controller for DVR works on two separate closed path viz. feed forward path for quick transient response and feedback path for reducing the steady state error. Moreover, pre-sag mitigation strategy of DVR has been adapted through these two aforementioned paths. Complete design of proposed controller is based on phasor analysis. It also consist of proportional integral (PI) controller to reduce the error in the DC-link voltage during compensation time. The controller performance has been verified in MATLAB Simulink for both types (linear and nonlinear) of load. The results obtained indicates that the proposed controller is effective in its performance.

77%乙·莠·滴异辛酯悬乳剂除草剂对春玉米田一年生杂草的防除效果

【目的】为了早期防除一年生单子叶、双子叶杂草对春玉米生长发育的危害,明确试验药剂对一年生杂草的防除效果及其对春玉米的安全性。【方法】选用三元混配除草剂77%乙·莠·滴异辛酯悬乳剂和单剂900 g/L乙草胺乳油、38%莠去津悬浮剂、87.5%2,4-滴异辛酯乳油对春玉米田进行土壤封闭处理防除杂草试验。【结果】77%乙·莠·滴异辛酯悬乳剂不同用量[1732.5、2310.0、2887.5、4620.0 g(a.i)/hm^2]处理可以有效地防除田间一年生杂草稗草、狗尾草、反枝苋和龙葵,施药后45 d各处理总株防效均在96.9%以上,优于各单剂处理的防效,而且差异达到极显著水平(P<0.01)。同时,三元混配除草剂各处理增产作用显著,与空白对照处理相比增产幅度达35.4%~50.8%。各药剂处理对春玉米生长无不良影响。【结论】利用该三元混配除草剂进行春玉米田土壤封闭处理,田间选择用药量1732.5~2310.0 g(a.i)/hm^2,可实现一次用药有效控制一年生单子叶、双子叶杂草、避免杂草与春玉米生长早期竞争水肥、节本增效的目的。

现代应用数学理论在电力系统稳定分析中的应用

电力系统稳定分析是一项很重要的工作。目前电力系统稳定分析最常用的两种方法是基于采集的数据进行辨识分析和对系统进行建模分析。将分别研究现代应用数学的相关理论在这两种方法中的应用。采用辨识方法时,由于现场采集的数据噪声较多,往往得不到正确的结果,因此需要采用去噪技术对数据进行预处理,介绍了小波去噪在电力系统低频振荡辨识中的应用。采用数学建模方法时,由于电力系统属于非线性系统,当分析一些特定运行状态时(如电力系统受到大干扰后),要用非线性方法才能得出正确的结果,介绍了微分几何理论在电力系统非线性控制中的应用。

A Study on the Dynamic Performance of Hydroviscous Driyes

Gives a dynamic mathematical model of a typical type of multiple discs hydroviscous drive device which has been proved to be correct through tests.Utilizing the method of root-locus analysis the dynamic performance of this device is studied according to the model.Theoretical analysis and test re- suits show that the dynamic performance of the object of study can be greatly improved by speed negative feedback.

基于宏基因组测序的植物叶表微生物富集及DNA提取方法

获得高质量的微生物基因组DNA是进行复杂微生物群落宏基因组学研究的基础和难点。植物叶表是一个微生物多样性丰富的复杂生态系统,这些微生物群落可以调节叶片功能性状,影响植物的适应性。深入了解叶表微生物群落的基本结构和功能原理,有助于在促进植物生长和植物保护方面发挥重要的应用价值。由于叶表严苛的环境,导致富集叶表微生物难度较大,严重限制了高质量叶表微生物基因组DNA的提取。基于现有DNA提取方法,加入表面活性剂Silwet L-77进行前处理,同时循环利用洗脱液,加强叶表微生物的富集,以提高叶表微生物的获取量。结合商业试剂盒方法进行提取得到高纯度、高浓度的基因组DNA。经过质量控制和建库测序验证,DNA质量达到宏基组建库的要求。通过此方法可以提高叶表微生物分离和收集效率的方法,提高叶表微生物DNA提取成功率,为应用高通量测序技术研究叶表微生物组成和其他植物分子生物学研究提供参考。

Decentralised dynamic high-gain scaling-based output-feedback control of large-scale non-linear interconnected systems with delays

A general class of non-linear large-scale interconnected systems is considered,wherein each subsystem is comprised of a nominal part in a general strict-feedback-like structure and a set of appended dynamics.Parametric and functional uncertainties and time delays are allowed throughout the overall system structure including the nominal strictfeedback-like parts and appended dynamics of each subsystem as well as the non-linear subsystem interconnections.The controller design is based on the dual dynamic highgain scaling technique and provides a robust adaptive delay-independent globally stabilising decentralised output-feedback controller.The disturbance attenuation properties of the proposed output-feedback decentralised controller to an exogenous disturbance input are also analysed and specific conditions under which properties such as Input-toOutput-practical-Stability and asymptotic stabilisation are attained are also discussed.