This paper proposes a discrete-time robust control technique for an uncertain nonlinear system. The uncertainty mainly affects the system dynamics due to mismatched parameter variation which is bounded by a predefined...This paper proposes a discrete-time robust control technique for an uncertain nonlinear system. The uncertainty mainly affects the system dynamics due to mismatched parameter variation which is bounded by a predefined known function. In order to compensate the effect of uncertainty, a robust control input is derived by formulating an equivalent optimal control problem for a virtual nominal system with a modified costfunctional. To derive the stabilizing control law for a mismatched system, this paper introduces another control input named as virtual input. This virtual input is not applied directly to stabilize the uncertain system, rather it is used to define a sufficient condition. To solve the nonlinear optimal control problem, a discretetime general Hamilton-Jacobi-Bellman(DT-GHJB) equation is considered and it is approximated numerically through a neural network(NN) implementation. The approximated solution of DTGHJB is used to compute the suboptimal control input for the virtual system. The suboptimal inputs for the virtual system ensure the asymptotic stability of the closed-loop uncertain system. A numerical example is illustrated with simulation results to prove the efficacy of the proposed control algorithm.展开更多
A linear matrix inequality （LMI）-based sliding surface design method for integral sliding mode control of uncertain time- delay systems with mismatching uncertainties is proposed. The uncertain time-delay system und...A linear matrix inequality （LMI）-based sliding surface design method for integral sliding mode control of uncertain time- delay systems with mismatching uncertainties is proposed. The uncertain time-delay system under consideration may have mis- matching norm bounded uncertainties in the state matrix as well as the input matrix, A sufficient condition for the existence of a sliding surface is given to guarantee asymptotic stability of the full order slJdJng mode dynamics. An LMI characterization of the slid- ing surface is given, together with an integral sliding mode control law guaranteeing the existence of a sliding mode from the initial time. Finally, a simulation is given to show the effectiveness of the proposed method.展开更多
为解决采用频域反射技术进行长电缆缺陷检测时,其结果易受低频段数据缺失占比的影响,而难以判断电缆缺陷极性的问题,该文提出一种基于频域反射技术的电缆阻抗失配点时频脉冲转换算法以实现缺陷的定位和极性判别。首先,采用2阶Nuttall自...为解决采用频域反射技术进行长电缆缺陷检测时,其结果易受低频段数据缺失占比的影响,而难以判断电缆缺陷极性的问题,该文提出一种基于频域反射技术的电缆阻抗失配点时频脉冲转换算法以实现缺陷的定位和极性判别。首先,采用2阶Nuttall自卷积窗的快速傅里叶计算方法对不同类型的电缆阻抗失配点进行定位。其次,提出电缆阻抗失配点时频脉冲转换算法,利用高斯窄带包络信号良好的频段调节能力和时频特性,详细阐述了时频脉冲的参数设计和极性判断方法。之后,运用仿真,对不同类型的阻抗失配点进行时频脉冲转换,验证了该算法的有效性。最后,采用该算法对实验室含接头长1500m的10k V XLPE电缆进行实验验证。仿真和实验结果表明:时频脉冲转换算法可以有效地定位长电缆阻抗失配点并且实现不同类型阻抗失配点的极性识别;同时,不同长度电缆阻抗失配点的时频脉冲转换结果不受低频段数据缺失占比的影响,有效提高了长电缆阻抗失配点的极性识别率。展开更多
目的分析阿替普酶静脉溶栓治疗DWI-FLAIR不匹配指导发病时间不明的急性缺血性脑卒中的有效性及安全性。方法回顾性分析2021年3月—2023年6月广宁县人民医院收治的60例经影像学及临床症状检查确诊为急性缺血性脑卒中患者的临床资料,根据...目的分析阿替普酶静脉溶栓治疗DWI-FLAIR不匹配指导发病时间不明的急性缺血性脑卒中的有效性及安全性。方法回顾性分析2021年3月—2023年6月广宁县人民医院收治的60例经影像学及临床症状检查确诊为急性缺血性脑卒中患者的临床资料,根据发病时间是否明确将其分为发病时间不明组与发病时间明确组,每组30例。均选用重组组织型纤溶酶原激活剂阿替普酶(recombinant tissue plasminogen activator,rt-PA)进行静脉溶栓治疗。对比两组患者的临床疗效及溶栓后出血情况和预后效果。结果治疗前后两组患者的美国国立卫生研究院卒中量表(National Institute of Health Stroke Scale,NIHSS)评分比较,差异无统计学意义(P>0.05);两组治疗前后改良Rankin评分(Modified Rankin Scale,MRS)比较,差异无统计学意义(P>0.05);两组溶栓后不良事件发生率分别为6.67%和10.00%,差异无统计学意义(χ^(2)=0.000,P>0.05)。结论rt-PA溶栓治疗发病时间不明的急性缺血性脑卒患者中同治疗发病时间明确的患者效果相似。展开更多
文摘This paper proposes a discrete-time robust control technique for an uncertain nonlinear system. The uncertainty mainly affects the system dynamics due to mismatched parameter variation which is bounded by a predefined known function. In order to compensate the effect of uncertainty, a robust control input is derived by formulating an equivalent optimal control problem for a virtual nominal system with a modified costfunctional. To derive the stabilizing control law for a mismatched system, this paper introduces another control input named as virtual input. This virtual input is not applied directly to stabilize the uncertain system, rather it is used to define a sufficient condition. To solve the nonlinear optimal control problem, a discretetime general Hamilton-Jacobi-Bellman(DT-GHJB) equation is considered and it is approximated numerically through a neural network(NN) implementation. The approximated solution of DTGHJB is used to compute the suboptimal control input for the virtual system. The suboptimal inputs for the virtual system ensure the asymptotic stability of the closed-loop uncertain system. A numerical example is illustrated with simulation results to prove the efficacy of the proposed control algorithm.
基金supported in part by the National Basic Research Program of China(973 Program)(61334)
文摘A linear matrix inequality （LMI）-based sliding surface design method for integral sliding mode control of uncertain time- delay systems with mismatching uncertainties is proposed. The uncertain time-delay system under consideration may have mis- matching norm bounded uncertainties in the state matrix as well as the input matrix, A sufficient condition for the existence of a sliding surface is given to guarantee asymptotic stability of the full order slJdJng mode dynamics. An LMI characterization of the slid- ing surface is given, together with an integral sliding mode control law guaranteeing the existence of a sliding mode from the initial time. Finally, a simulation is given to show the effectiveness of the proposed method.
文摘为解决采用频域反射技术进行长电缆缺陷检测时,其结果易受低频段数据缺失占比的影响,而难以判断电缆缺陷极性的问题,该文提出一种基于频域反射技术的电缆阻抗失配点时频脉冲转换算法以实现缺陷的定位和极性判别。首先,采用2阶Nuttall自卷积窗的快速傅里叶计算方法对不同类型的电缆阻抗失配点进行定位。其次,提出电缆阻抗失配点时频脉冲转换算法,利用高斯窄带包络信号良好的频段调节能力和时频特性,详细阐述了时频脉冲的参数设计和极性判断方法。之后,运用仿真,对不同类型的阻抗失配点进行时频脉冲转换,验证了该算法的有效性。最后,采用该算法对实验室含接头长1500m的10k V XLPE电缆进行实验验证。仿真和实验结果表明:时频脉冲转换算法可以有效地定位长电缆阻抗失配点并且实现不同类型阻抗失配点的极性识别;同时,不同长度电缆阻抗失配点的时频脉冲转换结果不受低频段数据缺失占比的影响,有效提高了长电缆阻抗失配点的极性识别率。
文摘目的分析阿替普酶静脉溶栓治疗DWI-FLAIR不匹配指导发病时间不明的急性缺血性脑卒中的有效性及安全性。方法回顾性分析2021年3月—2023年6月广宁县人民医院收治的60例经影像学及临床症状检查确诊为急性缺血性脑卒中患者的临床资料,根据发病时间是否明确将其分为发病时间不明组与发病时间明确组,每组30例。均选用重组组织型纤溶酶原激活剂阿替普酶(recombinant tissue plasminogen activator,rt-PA)进行静脉溶栓治疗。对比两组患者的临床疗效及溶栓后出血情况和预后效果。结果治疗前后两组患者的美国国立卫生研究院卒中量表(National Institute of Health Stroke Scale,NIHSS)评分比较,差异无统计学意义(P>0.05);两组治疗前后改良Rankin评分(Modified Rankin Scale,MRS)比较,差异无统计学意义(P>0.05);两组溶栓后不良事件发生率分别为6.67%和10.00%,差异无统计学意义(χ^(2)=0.000,P>0.05)。结论rt-PA溶栓治疗发病时间不明的急性缺血性脑卒患者中同治疗发病时间明确的患者效果相似。
