A major issue in radar quantitative precipitation estimation is the contamination of radar echoes by non-meteorological targets such as ground clutter,chaff,clear air echoes etc.In this study,a fuzzy logic algorithm f...A major issue in radar quantitative precipitation estimation is the contamination of radar echoes by non-meteorological targets such as ground clutter,chaff,clear air echoes etc.In this study,a fuzzy logic algorithm for the identification of non-meteorological echoes is developed using optimized membership functions and weights for the dual-polarization radar located at Mount Sobaek.For selected precipitation and non-meteorological events,the characteristics of the precipitation and non-meteorological echo are derived by the probability density functions of five fuzzy parameters as functions of reflectivity values.The membership functions and weights are then determined by these density functions.Finally,the nonmeteorological echoes are identified by combining the membership functions and weights.The performance is qualitatively evaluated by long-term rain accumulation.The detection accuracy of the fuzzy logic algorithm is calculated using the probability of detection（POD）,false alarm rate（FAR）,and clutter–signal ratio（CSR）.In addition,the issues in using filtered dual-polarization data are alleviated.展开更多
针对直流微电网系统中双有源桥(Dual active bridge,DAB)变换器存在的直流母线电压和负载波动大、传输功率不稳定等问题,提出一种基于遗传算法的自抗扰控制与梯度下降算法优化回流功率的混合优化控制策略。首先,分析拓展移相调制下DAB...针对直流微电网系统中双有源桥(Dual active bridge,DAB)变换器存在的直流母线电压和负载波动大、传输功率不稳定等问题,提出一种基于遗传算法的自抗扰控制与梯度下降算法优化回流功率的混合优化控制策略。首先,分析拓展移相调制下DAB变换器的拓扑结构和功率特性,以回流功率为损失函数,引入梯度下降算法迭代寻找最优内移相比。随后,在DAB变换器小信号建模的基础上,设计线性自抗扰控制器,通过扩张状态观测器对输出电压和系统内外部扰动进行观测估计。同时,考虑到复杂环境下自抗扰控制器参数整定的不确定性,引入遗传算法对自抗扰控制器进行参数自整定。最后,搭建以TMS320F28335为控制器的试验平台对提出的混合优化控制策略(Hybrid optimal control strategy under extended phase shift modulation,EPS-HOCS)和传统PI控制(PI control strategy under extended phase shift modulation,EPS-PI)和自适应梯度下降算法控制(Adaptive gradient descent algorithm under extended phase shift modulation,EPS-AGDA)进行分析对比,验证了所提策略在回流功率和动态性能方面的优越性。展开更多
In this paper, we first consider the problem of distributed power control in a Full Duplex （FD） wireless network consisting of multiple pairs of nodes, within which each node needs to communicate with its correspond...In this paper, we first consider the problem of distributed power control in a Full Duplex （FD） wireless network consisting of multiple pairs of nodes, within which each node needs to communicate with its corresponding node. We aim to find the optimal transmition power for the FD transmitters such that the network-wide capacity is maximized. Based on the high Signal-to-Interference-Plus-Noise Ratio （SINR） approximation and a more general approximation method for logarithm functions, we develop effective distributed power control algorithms with the dual decomposition approach. We also extend the work to the general FD network scenario, which can be decomposed into subproblems of isolated nodes, paths, and cycles. The corresponding power control problem is then be solved with the distributed algorithm. The proposed algorithms are validated with simulation studies.展开更多
By converting an optimal control problem for nonlinear systems to a Hamiltonian system,a symplecitc-preserving method is proposed.The state and costate variables are approximated by the Lagrange polynomial.The state v...By converting an optimal control problem for nonlinear systems to a Hamiltonian system,a symplecitc-preserving method is proposed.The state and costate variables are approximated by the Lagrange polynomial.The state variables at two ends of the time interval are taken as independent variables.Based on the dual variable principle,nonlinear optimal control problems are replaced with nonlinear equations.Furthermore,in the implementation of the symplectic algorithm,based on the 2N algorithm,a multilevel method is proposed.When the time grid is refined from low level to high level,the initial state and costate variables of the nonlinear equations can be obtained from the Lagrange interpolation at the low level grid to improve efficiency.Numerical simulations show the precision and the efficiency of the proposed algorithm in this paper.展开更多
基金supported by a grant(14AWMP-B079364-01) from Water Management Research Program funded by Ministry of Land,Infrastructure and Transport of Korean government
文摘A major issue in radar quantitative precipitation estimation is the contamination of radar echoes by non-meteorological targets such as ground clutter,chaff,clear air echoes etc.In this study,a fuzzy logic algorithm for the identification of non-meteorological echoes is developed using optimized membership functions and weights for the dual-polarization radar located at Mount Sobaek.For selected precipitation and non-meteorological events,the characteristics of the precipitation and non-meteorological echo are derived by the probability density functions of five fuzzy parameters as functions of reflectivity values.The membership functions and weights are then determined by these density functions.Finally,the nonmeteorological echoes are identified by combining the membership functions and weights.The performance is qualitatively evaluated by long-term rain accumulation.The detection accuracy of the fuzzy logic algorithm is calculated using the probability of detection（POD）,false alarm rate（FAR）,and clutter–signal ratio（CSR）.In addition,the issues in using filtered dual-polarization data are alleviated.
文摘针对直流微电网系统中双有源桥(Dual active bridge,DAB)变换器存在的直流母线电压和负载波动大、传输功率不稳定等问题,提出一种基于遗传算法的自抗扰控制与梯度下降算法优化回流功率的混合优化控制策略。首先,分析拓展移相调制下DAB变换器的拓扑结构和功率特性,以回流功率为损失函数,引入梯度下降算法迭代寻找最优内移相比。随后,在DAB变换器小信号建模的基础上,设计线性自抗扰控制器,通过扩张状态观测器对输出电压和系统内外部扰动进行观测估计。同时,考虑到复杂环境下自抗扰控制器参数整定的不确定性,引入遗传算法对自抗扰控制器进行参数自整定。最后,搭建以TMS320F28335为控制器的试验平台对提出的混合优化控制策略(Hybrid optimal control strategy under extended phase shift modulation,EPS-HOCS)和传统PI控制(PI control strategy under extended phase shift modulation,EPS-PI)和自适应梯度下降算法控制(Adaptive gradient descent algorithm under extended phase shift modulation,EPS-AGDA)进行分析对比,验证了所提策略在回流功率和动态性能方面的优越性。
基金This paper was presented in part at IEEE WCNC 2015, New Orleans, LA, USA, Mar. 2015 [1]. This work is supported in part by the US National Science Foundation under Grants CNS-1247955, and by the Wireless Engineering Research and Education Center （WEREC） at Auburn University, Auburn, AL, USA.
文摘In this paper, we first consider the problem of distributed power control in a Full Duplex （FD） wireless network consisting of multiple pairs of nodes, within which each node needs to communicate with its corresponding node. We aim to find the optimal transmition power for the FD transmitters such that the network-wide capacity is maximized. Based on the high Signal-to-Interference-Plus-Noise Ratio （SINR） approximation and a more general approximation method for logarithm functions, we develop effective distributed power control algorithms with the dual decomposition approach. We also extend the work to the general FD network scenario, which can be decomposed into subproblems of isolated nodes, paths, and cycles. The corresponding power control problem is then be solved with the distributed algorithm. The proposed algorithms are validated with simulation studies.
基金supported by the National Natural Science Foundation of China(Nos.10632030,10902020,and 10721062)the Research Fund for the Doctoral Program of Higher Education of China(No.20070141067)+2 种基金the Doctoral Fund of Liaoning Province(No.20081091)the Key Laboratory Fund of Liaoning Province of China(No.2009S018)the Young Researcher Funds of Dalian University of Technology(No.SFDUT07002)
文摘By converting an optimal control problem for nonlinear systems to a Hamiltonian system,a symplecitc-preserving method is proposed.The state and costate variables are approximated by the Lagrange polynomial.The state variables at two ends of the time interval are taken as independent variables.Based on the dual variable principle,nonlinear optimal control problems are replaced with nonlinear equations.Furthermore,in the implementation of the symplectic algorithm,based on the 2N algorithm,a multilevel method is proposed.When the time grid is refined from low level to high level,the initial state and costate variables of the nonlinear equations can be obtained from the Lagrange interpolation at the low level grid to improve efficiency.Numerical simulations show the precision and the efficiency of the proposed algorithm in this paper.
