Using a relay feedback approach,mathematical expressions for identification of real-time level control system in transfer function form are proposed in this paper.An ideal relay with hysteresis is feedback to a simple...Using a relay feedback approach,mathematical expressions for identification of real-time level control system in transfer function form are proposed in this paper.An ideal relay with hysteresis is feedback to a simple level control system for the generation of sustained oscillations.Subsequently,limit cycle information is utilised in deduced expressions for the estimation of unknown system parameters.Using describing function analysis,the gain of an ideal relay with hysteresis is approximated to yield simple mathematical expressions.Typical examples from literature are considered to show the effectiveness of the proposed identification scheme.Yokogawa distributed control system:CENTUM CS 3000 is considered as a platform for the realisation of both relay feedback and Ziegler-Nichols(ZN)method.The accuracy of derived transfer function models is compared with a model derived from ZN method and thereafter demonstrated through frequency response plots which illustrate the experimental validation of the identified real-time process model.展开更多
The accurate control for the vehicle height and leveling adjustment system of an electronic air suspension(EAS) still is a challenging problem that has not been effectively solved in prior researches. This paper propo...The accurate control for the vehicle height and leveling adjustment system of an electronic air suspension(EAS) still is a challenging problem that has not been effectively solved in prior researches. This paper proposes a new adaptive controller to control the vehicle height and to adjust the roll and pitch angles of the vehicle body(leveling control) during the vehicle height adjustment procedures by an EAS system. A nonlinear mechanism model of the full?car vehicle height adjustment system is established to reflect the system dynamic behaviors and to derive the system optimal control law. To deal with the nonlinear characters in the vehicle height and leveling adjustment processes, the nonlinear system model is globally linearized through the state feedback method. On this basis, a fuzzy sliding mode controller(FSMC) is designed to improve the control accuracy of the vehicle height adjustment and to reduce the peak values of the roll and pitch angles of the vehicle body. To verify the effectiveness of the proposed control method more accurately, the full?car EAS system model programmed using AMESim is also given. Then, the co?simulation study of the FSMC performance can be conducted. Finally, actual vehicle tests are performed with a city bus, and the test results illustrate that the vehicle height adjustment performance is effectively guaranteed by the FSMC, and the peak values of the roll and pitch angles of the vehicle body during the vehicle height adjustment procedures are also reduced significantly. This research proposes an effective control methodology for the vehicle height and leveling adjustment system of an EAS, which provides a favorable control performance for the system.展开更多
Research on level 2 control system of 100 tons LF furnace was carried out. According to the principle of energy conservation and principle of mass conservation, the LF temperature prediction model and the composition ...Research on level 2 control system of 100 tons LF furnace was carried out. According to the principle of energy conservation and principle of mass conservation, the LF temperature prediction model and the composition prediction model were established. At the same time, the set value calculated by heating model and addition model could be sent to PLC. The results show that the technical indexes of LF furnace level 2 control system reach the demand and the system realizes automatic control.展开更多
In this paper, simulated and experimental results on the conical tank level control are presented. PI/PID controllers of integer order （IO） as well as of fractional order （FO） are studied and compared. The tuning ...In this paper, simulated and experimental results on the conical tank level control are presented. PI/PID controllers of integer order （IO） as well as of fractional order （FO） are studied and compared. The tuning parameters are obtained first by using root locus （RL） and Ziegler and Nichols methods, for comparison purposes. Next, particle swarm optimization （PSO） is employed to determine the optimal controllers＇ parameters using as fitness function the integral of the absolute value of tracking error （IAE）. From the experimental results it is concluded that PI/FOPI are the controllers presenting the lowest IAE indexes, whereas PID/FOPID controllers present the lowest energy consumption by the control signal.展开更多
An intelligent fuzzy-PID controller consisting of fuzzy logic controller and PID controller was developed to control the molten steel level of twin-roll strip caster.Additionally,a feedforward differential PID control...An intelligent fuzzy-PID controller consisting of fuzzy logic controller and PID controller was developed to control the molten steel level of twin-roll strip caster.Additionally,a feedforward differential PID controller was used for stopper position control in order to avoid differential kick.It is proved by simulation that the proposed intelligent controller is able to obtain zero steady state error asymptotically and the control system is robust due to its fuggy behavior of the controller.展开更多
The implementation of modular multilevel converters(MMC)in an electric ship to create a medium voltage direct current(MVDC)energy conversion system that is efficient,small,dependable,and easily scalable has garnered c...The implementation of modular multilevel converters(MMC)in an electric ship to create a medium voltage direct current(MVDC)energy conversion system that is efficient,small,dependable,and easily scalable has garnered considerable interest.In this research,an improved two-step nearest level control(E-NLC)is presented for MMC with a three-level submodule(3L-SM)as the rectifier of the electric ship power generation units in order to ease the economical and reliable operation of MMCs in MVDC systems.To achieve DC fault-clearing capability,the use of MMC with 3L-SM minimizes the number of switching devices when compared to the regular MMC topology.The suggested E-NLC scheme aims to reduce total harmonic distortion(THD)and achieve the nearest zero common mode voltage(CMV).The output voltage vector of the three phases is tuned using eight candidate vectors capable of suppressing CMV rather than the nearest-level vector,and the rounding function is modified to improve harmonic performance by increasing the approximation between stepped and modulated waves.The generator-connected MMC with THD reduction and CMV elimination maximizes the mover's protection in the generating unit of the electric ship's MVDC system.Simulation and experiment results validate the efficacy of the suggested approach with respect to steady-state and dynamic-state performance.展开更多
Concern about the biological hazards involved in microbiological research, especially research involving laboratory animals, has increased in recent years. Working in an animal biosafety level 2 facility （ABSL-2）, c...Concern about the biological hazards involved in microbiological research, especially research involving laboratory animals, has increased in recent years. Working in an animal biosafety level 2 facility （ABSL-2）, commonly used for research on infectious diseases, poses various biological hazards. Here, the regulations and standards related to laboratory biosafety in China are introduced, the potential biological hazards present in ABSL-2 facilities are analyzed, and a series of strategies to control the hazards are presented.展开更多
Level control in flotation columns is an important factor that influences the recovery and the grade of concentrate from the column. A flotation column is a nonlinear, multi-variable problem with changeable parameters...Level control in flotation columns is an important factor that influences the recovery and the grade of concentrate from the column. A flotation column is a nonlinear, multi-variable problem with changeable parameters that traditional methods have difficulty controlling. We have applied fuzzy control methods to the flotation column and tested the performance of the design by Matlab/Simulink simulation. The simulations show that level control in the flotation column becomes smoother and more rapid with the fuzzy controller. Compared to PID control methods the overshoot in valve position, the adjustment time, and the robustness of the controller are all improved. This indicates that it is suitable to model fuzzy controllers in applications for the study of automatic control of flotation column.展开更多
In this paper, a new analysis and design method for proportional-integrative-derivative （PID） tuning is proposed based on controller scaling analysis. Integral of time absolute error （ITAE） index is minimized for ...In this paper, a new analysis and design method for proportional-integrative-derivative （PID） tuning is proposed based on controller scaling analysis. Integral of time absolute error （ITAE） index is minimized for specified gain and phase margins （GPM） constraints, so that the transient performance and robustness are both satisfied. The requirements on gain and phase margins are ingeniously formulated by real part constraints （RPC） and imaginary part constraints （IPC）. This set of new constraints is simply related with three parameters and decoupling of the remaining four unknowns, including three controller parameters and the gain margin, in the nonlinear and coupled characteristic equation simultaneously. The formulas of the optimal GPM-PID are derived based on controller scaling analysis. Finally, this method is applied to liquid level control of coke fractionation tower, which demonstrate that the proposed method provides better disturbance rejection and robust tracking performance than some commonly used PID tuning methods.展开更多
The aim of the present study was to implant an efficient strategy for controlling the level of the effluent-oily foam interface in a DAF （dissolved air flotation） chamber of a pilot-scale prototype. DAF has been suc...The aim of the present study was to implant an efficient strategy for controlling the level of the effluent-oily foam interface in a DAF （dissolved air flotation） chamber of a pilot-scale prototype. DAF has been successfully used in the treatment of oily water, which is one of the main environmental problems in different industrial facilities. Along with important operational parameters, such as microbubble size and flow rate, the control strategy for the automation of a DAF chamber may be an important tool for increasing efficiency. Controlling the level was the strategy chosen to enhance the separation efficiency in a pilot-scale DAF prototype, with monitoring performed using a computational program in LabVIEW （laboratory virtual instrument engineering workbench）. The findings demonstrate that it is possible to maintain the level of the fluid at a reference value established by the operator using the software program through the application of classic proportional integral derivative controllers. Using this control tool, the efficiency of water-oil separation in the pilot flotation chamber prototype was increased to nearly 98%.展开更多
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...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.展开更多
In order to achieve an automatic leveling function for work platforms of aerial vehicles with mixed-booms( MAV) in full elevating domain,an auto-leveling mechanism for the platform is proposed based on a control metho...In order to achieve an automatic leveling function for work platforms of aerial vehicles with mixed-booms( MAV) in full elevating domain,an auto-leveling mechanism for the platform is proposed based on a control method of booms-constraint,where mixed-boom structures and elevating characteristics are considered. Three models of constraint strategies include non-constraint model,elevating constraint model and lowering constraint model,which is designed to meet the leveling requirements in full working extent. Through the hydro-mechatronic unified modeling,a virtual prototype model is set up based on the auto-leveling mechanism,and leveling performances of the platform are studied during booms elevating to the maximum working height and extent. Simulation results show that the control method of booms-constraint can realize auto-leveling of the platform under two typical working conditions,meanwhile a leveling deviation appears at the constrained point,but the platform inclination is adjusted in the permissible range. The control method does not only restrict booms' freedom elevating to a certain extent,but also impacts the booms extending to the maximum working range. Experimental results verify that the auto-leveling mechanism based on booms-constraint control is valid and rational,which provides an effective technology approach for development of the platform leveling of MAV.展开更多
This article describes the development of automatic control system on the basis of Festo ＂Compact Workstation＂ training stand. Such control systems are used in different branches of industry and infrastructure inclu...This article describes the development of automatic control system on the basis of Festo ＂Compact Workstation＂ training stand. Such control systems are used in different branches of industry and infrastructure including oil industry, chemical industry, water treatment, canalization and others. The stand allows realizing level, flow, pressure and temperature control systems, using pump, valves, discrete and analog sensors. Level control system is described in this work. PID （proportional integral derivative） controllers are used in these systems. Control is switched on and off and the parameters of control systems are changed by means of SCADA （supervisory control and data acquisition） system. During real technological processes, these actions are performed by the operator. The algorithm of the control system is realized using PLC （programmable logic controller）. At the end of the article conclusions about the research are drawn.展开更多
Objective: to explore and compare the effects of different health education methods on blood pressure control level of patients with essential hypertension in physical examination center. Methods: 80 patients with ess...Objective: to explore and compare the effects of different health education methods on blood pressure control level of patients with essential hypertension in physical examination center. Methods: 80 patients with essential hypertension were divided into groups by touching the ball in the physical examination center. 40 patients in the control group received basic health education and 40 patients in the observation group received systematic health education. The results were observed and recorded. Results: the blood pressure index of the observation group was lower, and the score of quality of life and nursing satisfaction were higher (P < 0.05). Conclusion: systematic health education plays a very important role in stabilizing and controlling blood pressure. The quality of life of patients is generally improved. They are very satisfied with the nursing model, which is worthy of popularization and use.展开更多
In this paper, the robust control problem of general nonlinear multi-input multi-output (MIMO) systems is proposed. The robustness against unknown disturbances is considered. Two algorithms based on the Sliding Mode C...In this paper, the robust control problem of general nonlinear multi-input multi-output (MIMO) systems is proposed. The robustness against unknown disturbances is considered. Two algorithms based on the Sliding Mode Control (SMC) for nonlinear coupled multi-input multi-output (MIMO) systems are proposed: the first order sliding mode control (FOSMC) with saturation (sat) function and the FOSMC with sat combined with integrator controller. Those algorithms were simulated and implemented on the three tanks test-bed system and the exprimental results confirm the effectiveness of our control design.展开更多
In recent decades, due to the increasing risk of diabetes, the measurement and control of the blood sugar is of great importance. In typeI diabetes, because of the lack of insulin secretion, the cells cannot absorb gl...In recent decades, due to the increasing risk of diabetes, the measurement and control of the blood sugar is of great importance. In typeI diabetes, because of the lack of insulin secretion, the cells cannot absorb glucose, and thus have a low level of glucose. To control blood glucose, the insulin must be injected to the body. In fact, the injection must be in a completely controlled environment. If the level of the insulin exceeds the physiological limits, it may cause death. This paper presents an online approach to control the blood glucose level using a nonlinear model predictive control. This method, maintains the level of blood glucose concentration within a normal range. Thus, the blood glucose level is measured in each minute and predicted for the next time interval. If that is not in the normal range, amount of the insulin which must be injected will be determined. The proposed control approach includes important features such as model uncertainties and prevents acute decrease in the blood glucose level, and instability. In order to assess performance of the proposed controller, computer simulations have been carried out in Matlab/Simulink. Simulation results will reveal the effectiveness of the proposed nonlinear model predictive controller in adjusting the blood glucose level by injecting required insulin. So if the nutrition of the person decreases instantly, the hypoglycemia does not happen.展开更多
An artificial aquatic food web (AAFW) system was designed to remove the non-point source pollutants in eutrophic Jiyu river. A certain amount of Scenedesmus obliquus and Daphnia pulex was cultured in the system for th...An artificial aquatic food web (AAFW) system was designed to remove the non-point source pollutants in eutrophic Jiyu river. A certain amount of Scenedesmus obliquus and Daphnia pulex was cultured in the system for the control of serious cyanobacterial bloom. The AAFW system was a continuous-flow system including one storage basin of 3 m<sup>3</sup> capacity with polluted river water (the total nitrogen-TN: 4.49 mg⋅l<sup>-1</sup><sup></sup>;the total phosphorus-TP: 0.192 mg⋅l-1</sup></sup><sup></sup>), one phytoplankton tank of 3 m<sup>3</sup> capacity with an initial concentrations of S. obliquus about 5.8 × 10<sup>3</sup> ind⋅l-1</sup><sup></sup>, and one zooplankton growth chamber of 1.5 m<sup>3</sup> capacity with an initial abundance of D. pulex about 22.5 ind⋅l-1</sup></sup>. The system was optimized by setting hydraulic retention time of phytoplankton tank as 5 days and the experiments were operated for 45 days. Compared with the polluted river, TN and TP were removed about 28% and 47% by the AAFW system, respectively. The biomass of phytoplankton decrease from 6.33 mg⋅l-1<sup></sup> to 1.48 mg⋅l-1</sup><sup></sup> and the percentage of cyanobacteria decrease from 43.93% to 2.36%, the biomass of Crustacean zooplankton increase from 0.34 mg⋅l-1</sup></sup><sup></sup> to 1.53 mg⋅l-1</sup></sup><sup></sup> and the percentage of D. pulex increase from 19.19% to 57.62%. Our results indicated that the AAFW system not only is an efficient, flexible system for reducing nutrient levels in tributary rivers, but also has an ability to control the cyanobacteria bloom and rebuilding the aquatic ecosystem from the polluted river water.展开更多
文摘Using a relay feedback approach,mathematical expressions for identification of real-time level control system in transfer function form are proposed in this paper.An ideal relay with hysteresis is feedback to a simple level control system for the generation of sustained oscillations.Subsequently,limit cycle information is utilised in deduced expressions for the estimation of unknown system parameters.Using describing function analysis,the gain of an ideal relay with hysteresis is approximated to yield simple mathematical expressions.Typical examples from literature are considered to show the effectiveness of the proposed identification scheme.Yokogawa distributed control system:CENTUM CS 3000 is considered as a platform for the realisation of both relay feedback and Ziegler-Nichols(ZN)method.The accuracy of derived transfer function models is compared with a model derived from ZN method and thereafter demonstrated through frequency response plots which illustrate the experimental validation of the identified real-time process model.
基金Supported by National Natural Science Foundation of China(Grant Nos.51375212,61601203)Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions of China+1 种基金Key Research and Development Program of Jiangsu Province(BE2016149)Jiangsu Provincial Natural Science Foundation of China(BK20140555)
文摘The accurate control for the vehicle height and leveling adjustment system of an electronic air suspension(EAS) still is a challenging problem that has not been effectively solved in prior researches. This paper proposes a new adaptive controller to control the vehicle height and to adjust the roll and pitch angles of the vehicle body(leveling control) during the vehicle height adjustment procedures by an EAS system. A nonlinear mechanism model of the full?car vehicle height adjustment system is established to reflect the system dynamic behaviors and to derive the system optimal control law. To deal with the nonlinear characters in the vehicle height and leveling adjustment processes, the nonlinear system model is globally linearized through the state feedback method. On this basis, a fuzzy sliding mode controller(FSMC) is designed to improve the control accuracy of the vehicle height adjustment and to reduce the peak values of the roll and pitch angles of the vehicle body. To verify the effectiveness of the proposed control method more accurately, the full?car EAS system model programmed using AMESim is also given. Then, the co?simulation study of the FSMC performance can be conducted. Finally, actual vehicle tests are performed with a city bus, and the test results illustrate that the vehicle height adjustment performance is effectively guaranteed by the FSMC, and the peak values of the roll and pitch angles of the vehicle body during the vehicle height adjustment procedures are also reduced significantly. This research proposes an effective control methodology for the vehicle height and leveling adjustment system of an EAS, which provides a favorable control performance for the system.
文摘Research on level 2 control system of 100 tons LF furnace was carried out. According to the principle of energy conservation and principle of mass conservation, the LF temperature prediction model and the composition prediction model were established. At the same time, the set value calculated by heating model and addition model could be sent to PLC. The results show that the technical indexes of LF furnace level 2 control system reach the demand and the system realizes automatic control.
文摘In this paper, simulated and experimental results on the conical tank level control are presented. PI/PID controllers of integer order （IO） as well as of fractional order （FO） are studied and compared. The tuning parameters are obtained first by using root locus （RL） and Ziegler and Nichols methods, for comparison purposes. Next, particle swarm optimization （PSO） is employed to determine the optimal controllers＇ parameters using as fitness function the integral of the absolute value of tracking error （IAE）. From the experimental results it is concluded that PI/FOPI are the controllers presenting the lowest IAE indexes, whereas PID/FOPID controllers present the lowest energy consumption by the control signal.
基金Item Sponsored by National Natural Science Foundation of China(59995440)State Key Fundamental Research Project of China(G2000067208-4)
文摘An intelligent fuzzy-PID controller consisting of fuzzy logic controller and PID controller was developed to control the molten steel level of twin-roll strip caster.Additionally,a feedforward differential PID controller was used for stopper position control in order to avoid differential kick.It is proved by simulation that the proposed intelligent controller is able to obtain zero steady state error asymptotically and the control system is robust due to its fuggy behavior of the controller.
文摘The implementation of modular multilevel converters(MMC)in an electric ship to create a medium voltage direct current(MVDC)energy conversion system that is efficient,small,dependable,and easily scalable has garnered considerable interest.In this research,an improved two-step nearest level control(E-NLC)is presented for MMC with a three-level submodule(3L-SM)as the rectifier of the electric ship power generation units in order to ease the economical and reliable operation of MMCs in MVDC systems.To achieve DC fault-clearing capability,the use of MMC with 3L-SM minimizes the number of switching devices when compared to the regular MMC topology.The suggested E-NLC scheme aims to reduce total harmonic distortion(THD)and achieve the nearest zero common mode voltage(CMV).The output voltage vector of the three phases is tuned using eight candidate vectors capable of suppressing CMV rather than the nearest-level vector,and the rounding function is modified to improve harmonic performance by increasing the approximation between stepped and modulated waves.The generator-connected MMC with THD reduction and CMV elimination maximizes the mover's protection in the generating unit of the electric ship's MVDC system.Simulation and experiment results validate the efficacy of the suggested approach with respect to steady-state and dynamic-state performance.
基金supported by the National Science and Technology Major Projects of Infectious Disease(2012ZX10004-404)
文摘Concern about the biological hazards involved in microbiological research, especially research involving laboratory animals, has increased in recent years. Working in an animal biosafety level 2 facility （ABSL-2）, commonly used for research on infectious diseases, poses various biological hazards. Here, the regulations and standards related to laboratory biosafety in China are introduced, the potential biological hazards present in ABSL-2 facilities are analyzed, and a series of strategies to control the hazards are presented.
基金support from the Fundamental Research Funds for the Central Universitiesthe National Key Technology R & D Program in the 11th Five Year Plan of China (No. 2008BAB31B03)
文摘Level control in flotation columns is an important factor that influences the recovery and the grade of concentrate from the column. A flotation column is a nonlinear, multi-variable problem with changeable parameters that traditional methods have difficulty controlling. We have applied fuzzy control methods to the flotation column and tested the performance of the design by Matlab/Simulink simulation. The simulations show that level control in the flotation column becomes smoother and more rapid with the fuzzy controller. Compared to PID control methods the overshoot in valve position, the adjustment time, and the robustness of the controller are all improved. This indicates that it is suitable to model fuzzy controllers in applications for the study of automatic control of flotation column.
基金supported by National Natural Science Foundation of China(Nos.61403149 and 61273069)Natural Science Foundation of Fujian Province(No.2015J01261)the Scientific Research Foundation of National Huaqiao University
文摘In this paper, a new analysis and design method for proportional-integrative-derivative （PID） tuning is proposed based on controller scaling analysis. Integral of time absolute error （ITAE） index is minimized for specified gain and phase margins （GPM） constraints, so that the transient performance and robustness are both satisfied. The requirements on gain and phase margins are ingeniously formulated by real part constraints （RPC） and imaginary part constraints （IPC）. This set of new constraints is simply related with three parameters and decoupling of the remaining four unknowns, including three controller parameters and the gain margin, in the nonlinear and coupled characteristic equation simultaneously. The formulas of the optimal GPM-PID are derived based on controller scaling analysis. Finally, this method is applied to liquid level control of coke fractionation tower, which demonstrate that the proposed method provides better disturbance rejection and robust tracking performance than some commonly used PID tuning methods.
文摘The aim of the present study was to implant an efficient strategy for controlling the level of the effluent-oily foam interface in a DAF （dissolved air flotation） chamber of a pilot-scale prototype. DAF has been successfully used in the treatment of oily water, which is one of the main environmental problems in different industrial facilities. Along with important operational parameters, such as microbubble size and flow rate, the control strategy for the automation of a DAF chamber may be an important tool for increasing efficiency. Controlling the level was the strategy chosen to enhance the separation efficiency in a pilot-scale DAF prototype, with monitoring performed using a computational program in LabVIEW （laboratory virtual instrument engineering workbench）. The findings demonstrate that it is possible to maintain the level of the fluid at a reference value established by the operator using the software program through the application of classic proportional integral derivative controllers. Using this control tool, the efficiency of water-oil separation in the pilot flotation chamber prototype was increased to nearly 98%.
文摘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.
基金Supported by the National Natural Science Foundation of China(No.51509006)National Key Technology R&D Program(No.2015BAF07B08)Fundamental Research Funds for the Central Universities of Chang’an University(No.310825161008)
文摘In order to achieve an automatic leveling function for work platforms of aerial vehicles with mixed-booms( MAV) in full elevating domain,an auto-leveling mechanism for the platform is proposed based on a control method of booms-constraint,where mixed-boom structures and elevating characteristics are considered. Three models of constraint strategies include non-constraint model,elevating constraint model and lowering constraint model,which is designed to meet the leveling requirements in full working extent. Through the hydro-mechatronic unified modeling,a virtual prototype model is set up based on the auto-leveling mechanism,and leveling performances of the platform are studied during booms elevating to the maximum working height and extent. Simulation results show that the control method of booms-constraint can realize auto-leveling of the platform under two typical working conditions,meanwhile a leveling deviation appears at the constrained point,but the platform inclination is adjusted in the permissible range. The control method does not only restrict booms' freedom elevating to a certain extent,but also impacts the booms extending to the maximum working range. Experimental results verify that the auto-leveling mechanism based on booms-constraint control is valid and rational,which provides an effective technology approach for development of the platform leveling of MAV.
文摘This article describes the development of automatic control system on the basis of Festo ＂Compact Workstation＂ training stand. Such control systems are used in different branches of industry and infrastructure including oil industry, chemical industry, water treatment, canalization and others. The stand allows realizing level, flow, pressure and temperature control systems, using pump, valves, discrete and analog sensors. Level control system is described in this work. PID （proportional integral derivative） controllers are used in these systems. Control is switched on and off and the parameters of control systems are changed by means of SCADA （supervisory control and data acquisition） system. During real technological processes, these actions are performed by the operator. The algorithm of the control system is realized using PLC （programmable logic controller）. At the end of the article conclusions about the research are drawn.
文摘Objective: to explore and compare the effects of different health education methods on blood pressure control level of patients with essential hypertension in physical examination center. Methods: 80 patients with essential hypertension were divided into groups by touching the ball in the physical examination center. 40 patients in the control group received basic health education and 40 patients in the observation group received systematic health education. The results were observed and recorded. Results: the blood pressure index of the observation group was lower, and the score of quality of life and nursing satisfaction were higher (P < 0.05). Conclusion: systematic health education plays a very important role in stabilizing and controlling blood pressure. The quality of life of patients is generally improved. They are very satisfied with the nursing model, which is worthy of popularization and use.
文摘In this paper, the robust control problem of general nonlinear multi-input multi-output (MIMO) systems is proposed. The robustness against unknown disturbances is considered. Two algorithms based on the Sliding Mode Control (SMC) for nonlinear coupled multi-input multi-output (MIMO) systems are proposed: the first order sliding mode control (FOSMC) with saturation (sat) function and the FOSMC with sat combined with integrator controller. Those algorithms were simulated and implemented on the three tanks test-bed system and the exprimental results confirm the effectiveness of our control design.
文摘In recent decades, due to the increasing risk of diabetes, the measurement and control of the blood sugar is of great importance. In typeI diabetes, because of the lack of insulin secretion, the cells cannot absorb glucose, and thus have a low level of glucose. To control blood glucose, the insulin must be injected to the body. In fact, the injection must be in a completely controlled environment. If the level of the insulin exceeds the physiological limits, it may cause death. This paper presents an online approach to control the blood glucose level using a nonlinear model predictive control. This method, maintains the level of blood glucose concentration within a normal range. Thus, the blood glucose level is measured in each minute and predicted for the next time interval. If that is not in the normal range, amount of the insulin which must be injected will be determined. The proposed control approach includes important features such as model uncertainties and prevents acute decrease in the blood glucose level, and instability. In order to assess performance of the proposed controller, computer simulations have been carried out in Matlab/Simulink. Simulation results will reveal the effectiveness of the proposed nonlinear model predictive controller in adjusting the blood glucose level by injecting required insulin. So if the nutrition of the person decreases instantly, the hypoglycemia does not happen.
文摘An artificial aquatic food web (AAFW) system was designed to remove the non-point source pollutants in eutrophic Jiyu river. A certain amount of Scenedesmus obliquus and Daphnia pulex was cultured in the system for the control of serious cyanobacterial bloom. The AAFW system was a continuous-flow system including one storage basin of 3 m<sup>3</sup> capacity with polluted river water (the total nitrogen-TN: 4.49 mg⋅l<sup>-1</sup><sup></sup>;the total phosphorus-TP: 0.192 mg⋅l-1</sup></sup><sup></sup>), one phytoplankton tank of 3 m<sup>3</sup> capacity with an initial concentrations of S. obliquus about 5.8 × 10<sup>3</sup> ind⋅l-1</sup><sup></sup>, and one zooplankton growth chamber of 1.5 m<sup>3</sup> capacity with an initial abundance of D. pulex about 22.5 ind⋅l-1</sup></sup>. The system was optimized by setting hydraulic retention time of phytoplankton tank as 5 days and the experiments were operated for 45 days. Compared with the polluted river, TN and TP were removed about 28% and 47% by the AAFW system, respectively. The biomass of phytoplankton decrease from 6.33 mg⋅l-1<sup></sup> to 1.48 mg⋅l-1</sup><sup></sup> and the percentage of cyanobacteria decrease from 43.93% to 2.36%, the biomass of Crustacean zooplankton increase from 0.34 mg⋅l-1</sup></sup><sup></sup> to 1.53 mg⋅l-1</sup></sup><sup></sup> and the percentage of D. pulex increase from 19.19% to 57.62%. Our results indicated that the AAFW system not only is an efficient, flexible system for reducing nutrient levels in tributary rivers, but also has an ability to control the cyanobacteria bloom and rebuilding the aquatic ecosystem from the polluted river water.
