The purpose of this paper is the design of neural network-based adaptive sliding mode controller for uncertain unknown nonlinear systems. A special architecture adaptive neural network, with hyperbolic tangent activat...The purpose of this paper is the design of neural network-based adaptive sliding mode controller for uncertain unknown nonlinear systems. A special architecture adaptive neural network, with hyperbolic tangent activation functions, is used to emulate the equivalent and switching control terms of the classic sliding mode control （SMC）. Lyapunov stability theory is used to guarantee a uniform ultimate boundedness property for the tracking error, as well as of all other signals in the closed loop. In addition to keeping the stability and robustness properties of the SMC, the neural network-based adaptive sliding mode controller exhibits perfect rejection of faults arising during the system operating. Simulation studies are used to illustrate and clarify the theoretical results.展开更多
Power efficiency and link reliability are of great impor- tance in hierarchical wireless sensor networks （HWSNs）, espe- cially at the key level, which consists of sensor nodes located only one hop away from the sink...Power efficiency and link reliability are of great impor- tance in hierarchical wireless sensor networks （HWSNs）, espe- cially at the key level, which consists of sensor nodes located only one hop away from the sink node called OHS. The power and admission control problem in HWSNs is comsidered to improve its power efficiency and link reliability. This problem is modeled as a non-cooperative game in which the active OHSs are con- sidered as players. By applying a double-pricing scheme in the definition of OHSs＇ utility function, a Nash Equilibrium solution with network properties is derived. Besides, a distributed algorithm is also proposed to show the dynamic processes to achieve Nash Equilibrium. Finally, the simulation results demonstrate the effec- tiveness of the proposed algorithm.展开更多
We consider first order quasilinear hyperbolic systems with vertical characteristics. It was shown in [4] that such systems can be exactly controllable with the help of internal controls applied to the equations corr...We consider first order quasilinear hyperbolic systems with vertical characteristics. It was shown in [4] that such systems can be exactly controllable with the help of internal controls applied to the equations corresponding to zero eigenvalues. However, it is possible that, for physical or engineering reasons, we can not put any control on the equations corresponding to zero eigenvalues. In this paper, we will establish the exact controllability only by means of physically meaningfnl internal controls applied to the equations corresponding to non-zero eigenvalues. We also show the exact controllability for a very simplified model by means of switching controls.展开更多
A control system aims at vibration reduction in a two-span rotor system with two shear mode magnetorheological （MRF） dampers is designed. A finite element model of the MRF damper- rotor system is built and used to a...A control system aims at vibration reduction in a two-span rotor system with two shear mode magnetorheological （MRF） dampers is designed. A finite element model of the MRF damper- rotor system is built and used to analyze the rotor vibration characteristics. Based on Hooke and Jeeves algorithm and the numerical simulation analysis, an optimal appropriate controller is proposed and designed. Experimental results show that rotor vibration caused by unbalance is well controlled （ first critical speed region 37% , second critical speed region 42% ）. To reflect advantages of optimi- zing strategy presented and validate the intelligent optimization control technology, detailed experi- ments were developed on a two-span rotor-vibration-control platform. The influence on accuracy, rapidity and stability of optimizing control for rotor vibration are analyzed. It provides a powerful technical support for the extension and application in target and control for shafting vibration.展开更多
Dynamic Models for predicting the concentration profiles of the reactants and product in a Continuous Stirred Tank Reactor for the transesterification of used cooking oil (triglyceride) to biodiesel has been developed...Dynamic Models for predicting the concentration profiles of the reactants and product in a Continuous Stirred Tank Reactor for the transesterification of used cooking oil (triglyceride) to biodiesel has been developed using the principle of conservation of mass. The developed system of differential equations were integrated numerically using fourth order Runge-Kutta algorithm embedded in ode 45 solver of 7.5 Mathlab program. The models were validated by solving the model equations with kinetic data and other relevant data from literatures. The results and trends were similar and in agreement with those from these literatures. Simulations of the reactor to (±) step changes in the inlet flowrates of the reactants (used cooking oil and methanol) showed great effect on biodiesel production, (instability—oscillations and reduction in output concentration of biodiesel). A feedback control strategy was developed with a Proportional-Integral (PI) Controller and a close loop model was developed for control studies. The closed loop response of the reactor output (biodiesel concentration) showed continuous oscillatory response with offset. Hence the controller parameters (proportional gain <em>K</em><em><sub>c</sub></em> and integral time <img src="Edit_b22777c4-287e-4ff4-a82a-0b5c9393b5ab.bmp" alt="" />) were tuned using the “On-Line Trial and Error Method” implemented using MathLab Simulink to obtain optimum values that ensured quick stability of the closed-loop system, reduced or no oscillatory response and no offset. The optimum controller parameters were: proportional gain <em style="white-space:normal;">K</em><em style="white-space:normal;"><sub>c</sub></em> =8.306 and integral time <img src="Edit_7ad87ff7-7563-48b0-865b-70efc6c433cd.bmp" alt="" />= 17.157 minutes. <p> <br /> </p>展开更多
随着电力系统中可再生能源比重逐渐增加,电力系统频率波动的风险增大。飞轮和锂电池可以优势互补,作为混合储能应用于电网一次调频中,有效解决系统频率波动问题。为了充分发挥飞轮和锂电池各自的调频优势,提出基于自适应荷电状态(state ...随着电力系统中可再生能源比重逐渐增加,电力系统频率波动的风险增大。飞轮和锂电池可以优势互补,作为混合储能应用于电网一次调频中,有效解决系统频率波动问题。为了充分发挥飞轮和锂电池各自的调频优势,提出基于自适应荷电状态(state of charge,SOC)的电池-飞轮混合储能一次调频控制策略。首先,建立含正、负虚拟惯性控制和虚拟下垂控制的权重分配一次调频模型;然后,利用飞轮和锂电池SOC对一次调频模型参数进行修正,提高混合储能在SOC阈值附近的一次调频能力;最后,仿真对比各调频场景下文中控制策略与其他控制策略的调频能力及SOC恢复效果。研究结果表明,文中控制策略下储能系统SOC波动范围最小,电池不会发生过充过放,且系统频率波动不超过±0.2 Hz,可以提高电网频率稳定性。展开更多
文摘The purpose of this paper is the design of neural network-based adaptive sliding mode controller for uncertain unknown nonlinear systems. A special architecture adaptive neural network, with hyperbolic tangent activation functions, is used to emulate the equivalent and switching control terms of the classic sliding mode control （SMC）. Lyapunov stability theory is used to guarantee a uniform ultimate boundedness property for the tracking error, as well as of all other signals in the closed loop. In addition to keeping the stability and robustness properties of the SMC, the neural network-based adaptive sliding mode controller exhibits perfect rejection of faults arising during the system operating. Simulation studies are used to illustrate and clarify the theoretical results.
基金supported by the National Natural Science Foundation of China (7070102571071105)+2 种基金the Program for New Century Excellent Talents in Universities of China (NCET-08-0396)the National Science Fund for Distinguished Young Scholars of China (70925005)the Program for Changjiang Scholars and Innovative Research Team in University (IRT/028)
文摘Power efficiency and link reliability are of great impor- tance in hierarchical wireless sensor networks （HWSNs）, espe- cially at the key level, which consists of sensor nodes located only one hop away from the sink node called OHS. The power and admission control problem in HWSNs is comsidered to improve its power efficiency and link reliability. This problem is modeled as a non-cooperative game in which the active OHSs are con- sidered as players. By applying a double-pricing scheme in the definition of OHSs＇ utility function, a Nash Equilibrium solution with network properties is derived. Besides, a distributed algorithm is also proposed to show the dynamic processes to achieve Nash Equilibrium. Finally, the simulation results demonstrate the effec- tiveness of the proposed algorithm.
文摘We consider first order quasilinear hyperbolic systems with vertical characteristics. It was shown in [4] that such systems can be exactly controllable with the help of internal controls applied to the equations corresponding to zero eigenvalues. However, it is possible that, for physical or engineering reasons, we can not put any control on the equations corresponding to zero eigenvalues. In this paper, we will establish the exact controllability only by means of physically meaningfnl internal controls applied to the equations corresponding to non-zero eigenvalues. We also show the exact controllability for a very simplified model by means of switching controls.
基金Supported by the National Program on Key Basic Research Project(973Program)(2012CB026000)Ph.D Programs Foundation of Ministry of Education of China(20110010110009)
文摘A control system aims at vibration reduction in a two-span rotor system with two shear mode magnetorheological （MRF） dampers is designed. A finite element model of the MRF damper- rotor system is built and used to analyze the rotor vibration characteristics. Based on Hooke and Jeeves algorithm and the numerical simulation analysis, an optimal appropriate controller is proposed and designed. Experimental results show that rotor vibration caused by unbalance is well controlled （ first critical speed region 37% , second critical speed region 42% ）. To reflect advantages of optimi- zing strategy presented and validate the intelligent optimization control technology, detailed experi- ments were developed on a two-span rotor-vibration-control platform. The influence on accuracy, rapidity and stability of optimizing control for rotor vibration are analyzed. It provides a powerful technical support for the extension and application in target and control for shafting vibration.
文摘Dynamic Models for predicting the concentration profiles of the reactants and product in a Continuous Stirred Tank Reactor for the transesterification of used cooking oil (triglyceride) to biodiesel has been developed using the principle of conservation of mass. The developed system of differential equations were integrated numerically using fourth order Runge-Kutta algorithm embedded in ode 45 solver of 7.5 Mathlab program. The models were validated by solving the model equations with kinetic data and other relevant data from literatures. The results and trends were similar and in agreement with those from these literatures. Simulations of the reactor to (±) step changes in the inlet flowrates of the reactants (used cooking oil and methanol) showed great effect on biodiesel production, (instability—oscillations and reduction in output concentration of biodiesel). A feedback control strategy was developed with a Proportional-Integral (PI) Controller and a close loop model was developed for control studies. The closed loop response of the reactor output (biodiesel concentration) showed continuous oscillatory response with offset. Hence the controller parameters (proportional gain <em>K</em><em><sub>c</sub></em> and integral time <img src="Edit_b22777c4-287e-4ff4-a82a-0b5c9393b5ab.bmp" alt="" />) were tuned using the “On-Line Trial and Error Method” implemented using MathLab Simulink to obtain optimum values that ensured quick stability of the closed-loop system, reduced or no oscillatory response and no offset. The optimum controller parameters were: proportional gain <em style="white-space:normal;">K</em><em style="white-space:normal;"><sub>c</sub></em> =8.306 and integral time <img src="Edit_7ad87ff7-7563-48b0-865b-70efc6c433cd.bmp" alt="" />= 17.157 minutes. <p> <br /> </p>
文摘随着电力系统中可再生能源比重逐渐增加,电力系统频率波动的风险增大。飞轮和锂电池可以优势互补,作为混合储能应用于电网一次调频中,有效解决系统频率波动问题。为了充分发挥飞轮和锂电池各自的调频优势,提出基于自适应荷电状态(state of charge,SOC)的电池-飞轮混合储能一次调频控制策略。首先,建立含正、负虚拟惯性控制和虚拟下垂控制的权重分配一次调频模型;然后,利用飞轮和锂电池SOC对一次调频模型参数进行修正,提高混合储能在SOC阈值附近的一次调频能力;最后,仿真对比各调频场景下文中控制策略与其他控制策略的调频能力及SOC恢复效果。研究结果表明,文中控制策略下储能系统SOC波动范围最小,电池不会发生过充过放,且系统频率波动不超过±0.2 Hz,可以提高电网频率稳定性。
