The problem of the robust D-stability analysis for linear systems with parametric uncertainties is addressed. For matrix polytopes, new conditions via the affine parameter-dependent Lyapunov function of uncertain syst...The problem of the robust D-stability analysis for linear systems with parametric uncertainties is addressed. For matrix polytopes, new conditions via the affine parameter-dependent Lyapunov function of uncertain systems are developed with the benefit of the scalar multi-convex function. To be convenient for applications, such conditions are simplified into new linear matrix inequality （LMI） conditions, which can be solved by the powerful LMI toolbox. Numerical examples are provided to indicate that this new approach is less conservative than previous results for Hurwitz stability, Schur stability and D-stability of uncertain systems under certain circumstances.展开更多
由于统一电能质量调节器(unified power quality conditioner,UPQC)系统结构复杂、控制难度大,单一的控制策略不足以使其应对电网系统中的各种故障情况。因此,文中采用一种线性自抗扰控制(linear active disturbance rejection control,...由于统一电能质量调节器(unified power quality conditioner,UPQC)系统结构复杂、控制难度大,单一的控制策略不足以使其应对电网系统中的各种故障情况。因此,文中采用一种线性自抗扰控制(linear active disturbance rejection control,LADRC)与模型预测控制(model predictive control,MPC)的复合控制策略。在电压外环控制中采用LADRC策略以提高系统快速性与抗扰性,并给电流内环提供更精确的参考电流信号;在电流内环控制中采用电流MPC策略以提高跟踪参考信号的能力与系统的鲁棒性,同时对模型预测的空间电压矢量的分区进行优化,减少控制器计算量,在保证输出电流质量的前提下提高运算速度。最后,基于MATLAB/Simulink仿真实验平台对系统进行建模仿真,结果验证了采用LADRC-MPC控制策略对电网电压暂升/暂降、负载不对称引起的电流畸变与谐波污染等综合电能质量问题,可以起到更好的补偿效果,对电网电压的支撑能力也更强。展开更多
单相统一电能质量调节器(single-phase unified power quality conditioner,SPUPQC)是一个强耦合的多输入多输出非线性系统.本文在平衡流形重构系统模型,基于逆系统方法对重构后的系统构造解耦的伪线性系统.针对该伪线性系统采用线性二...单相统一电能质量调节器(single-phase unified power quality conditioner,SPUPQC)是一个强耦合的多输入多输出非线性系统.本文在平衡流形重构系统模型,基于逆系统方法对重构后的系统构造解耦的伪线性系统.针对该伪线性系统采用线性二次型调节器(LQR)设计了满足一定性能指标的控制器.该控制策略有良好的动态响应与补偿效果并有一定的实用价值.仿真实验证明了该控制器设计的可靠性与有效性.展开更多
算法将模型中的条件线性状态方程代入观测方程,并融合线性状态的过程噪声和观测噪声,再与非线性状态方程联立,由高斯和滤波器(Gaussian sum filter,GSF)获得非线性状态的估计;然后将估计值代入线性状态方程与观测方程,由卡尔曼滤波器(Ka...算法将模型中的条件线性状态方程代入观测方程,并融合线性状态的过程噪声和观测噪声,再与非线性状态方程联立,由高斯和滤波器(Gaussian sum filter,GSF)获得非线性状态的估计;然后将估计值代入线性状态方程与观测方程,由卡尔曼滤波器(Kalman Filter,KF)获得线性状态的估计。此外,获得的非线性状态估计的方差还用于修正线性状态的估计。将GSF-KF算法应用于目标跟踪的仿真结果表明,与现有Rao-Blackwellized粒子滤波器(Rao-Blackwellized Particle Filter,RBPF)相比,新方法在保证精度的同时,明显提高了实时性,计算时间仅约为RBPF的7%。展开更多
A knowledge-based network for Section Yidong Bridge,Dongyang River,one tributary of Qiantang River,Zhejiang Province,China,is established in order to model water quality in areas under small data.Then,based on normal ...A knowledge-based network for Section Yidong Bridge,Dongyang River,one tributary of Qiantang River,Zhejiang Province,China,is established in order to model water quality in areas under small data.Then,based on normal transformation of variables with routine monitoring data and normal assumption of variables without routine monitoring data,a conditional linear Gaussian Bayesian network is constructed.A "two-constraint selection" procedure is proposed to estimate potential parameter values under small data.Among all potential parameter values,the ones that are most probable are selected as the "representatives".Finally,the risks of pollutant concentration exceeding national water quality standards are calculated and pollution reduction decisions for decision-making reference are proposed.The final results show that conditional linear Gaussian Bayesian network and "two-constraint selection" procedure are very useful in evaluating risks when there is limited data and can help managers to make sound decisions under small data.展开更多
By using the upper and lower solution method and fixed point theory, we investigate some nonlinear singular second-order differential equations with linear functional boundary conditions. The nonlinear term f（t, u） ...By using the upper and lower solution method and fixed point theory, we investigate some nonlinear singular second-order differential equations with linear functional boundary conditions. The nonlinear term f（t, u） is nonincreasing with respect to u, and only possesses some integrability. We obtain the existence and uniqueness of the C[0, 1] positive solutions as well as the C1 [0, 1] positive solutions.展开更多
This note concerns the problem of the robust stability of uncertain neutral systems with time-varying delay and saturating actuators. The system considered is continuous in time with norm bounded parametric uncertaint...This note concerns the problem of the robust stability of uncertain neutral systems with time-varying delay and saturating actuators. The system considered is continuous in time with norm bounded parametric uncertainties. By incorporating the free weighing matrix approach developed recently, some new delay-dependent stability conditions in terms of linear matrix inequalities （LMIs） with some tuning parameters are obtained. An estimate of the domain of attraction of the closed-loop system under a priori designed controller is proposed. The approach is based on a polytopic description of the actuator saturation nonlinearities and the Lyapunov- Krasovskii method. Numerical examples are used to demonstrate the effectiveness of the proposed design method.展开更多
基金supported by the National Natural Science Foundation of China (6090405161021002)
文摘The problem of the robust D-stability analysis for linear systems with parametric uncertainties is addressed. For matrix polytopes, new conditions via the affine parameter-dependent Lyapunov function of uncertain systems are developed with the benefit of the scalar multi-convex function. To be convenient for applications, such conditions are simplified into new linear matrix inequality （LMI） conditions, which can be solved by the powerful LMI toolbox. Numerical examples are provided to indicate that this new approach is less conservative than previous results for Hurwitz stability, Schur stability and D-stability of uncertain systems under certain circumstances.
文摘由于统一电能质量调节器(unified power quality conditioner,UPQC)系统结构复杂、控制难度大,单一的控制策略不足以使其应对电网系统中的各种故障情况。因此,文中采用一种线性自抗扰控制(linear active disturbance rejection control,LADRC)与模型预测控制(model predictive control,MPC)的复合控制策略。在电压外环控制中采用LADRC策略以提高系统快速性与抗扰性,并给电流内环提供更精确的参考电流信号;在电流内环控制中采用电流MPC策略以提高跟踪参考信号的能力与系统的鲁棒性,同时对模型预测的空间电压矢量的分区进行优化,减少控制器计算量,在保证输出电流质量的前提下提高运算速度。最后,基于MATLAB/Simulink仿真实验平台对系统进行建模仿真,结果验证了采用LADRC-MPC控制策略对电网电压暂升/暂降、负载不对称引起的电流畸变与谐波污染等综合电能质量问题,可以起到更好的补偿效果,对电网电压的支撑能力也更强。
文摘单相统一电能质量调节器(single-phase unified power quality conditioner,SPUPQC)是一个强耦合的多输入多输出非线性系统.本文在平衡流形重构系统模型,基于逆系统方法对重构后的系统构造解耦的伪线性系统.针对该伪线性系统采用线性二次型调节器(LQR)设计了满足一定性能指标的控制器.该控制策略有良好的动态响应与补偿效果并有一定的实用价值.仿真实验证明了该控制器设计的可靠性与有效性.
基金Project(50809058)supported by the National Natural Science Foundation of China
文摘A knowledge-based network for Section Yidong Bridge,Dongyang River,one tributary of Qiantang River,Zhejiang Province,China,is established in order to model water quality in areas under small data.Then,based on normal transformation of variables with routine monitoring data and normal assumption of variables without routine monitoring data,a conditional linear Gaussian Bayesian network is constructed.A "two-constraint selection" procedure is proposed to estimate potential parameter values under small data.Among all potential parameter values,the ones that are most probable are selected as the "representatives".Finally,the risks of pollutant concentration exceeding national water quality standards are calculated and pollution reduction decisions for decision-making reference are proposed.The final results show that conditional linear Gaussian Bayesian network and "two-constraint selection" procedure are very useful in evaluating risks when there is limited data and can help managers to make sound decisions under small data.
基金. Supported by National Natural Science Foundation of China （Grant No. 10871116）, Natural Science Foundation of Shandong Province of China （Grant No. ZR2010AM005） and the Doctoral Program Foundation of Education Ministry of China （Grant No. 200804460001）Acknowledgements The authors would like to thank the referees for their valuable comments.
文摘By using the upper and lower solution method and fixed point theory, we investigate some nonlinear singular second-order differential equations with linear functional boundary conditions. The nonlinear term f（t, u） is nonincreasing with respect to u, and only possesses some integrability. We obtain the existence and uniqueness of the C[0, 1] positive solutions as well as the C1 [0, 1] positive solutions.
文摘This note concerns the problem of the robust stability of uncertain neutral systems with time-varying delay and saturating actuators. The system considered is continuous in time with norm bounded parametric uncertainties. By incorporating the free weighing matrix approach developed recently, some new delay-dependent stability conditions in terms of linear matrix inequalities （LMIs） with some tuning parameters are obtained. An estimate of the domain of attraction of the closed-loop system under a priori designed controller is proposed. The approach is based on a polytopic description of the actuator saturation nonlinearities and the Lyapunov- Krasovskii method. Numerical examples are used to demonstrate the effectiveness of the proposed design method.
