研究了具有 m 维输出和 n 阶可观测的连续时间系统的具有任意极点最小阶数函数观测器的设计问题。文中将构成具有任意极点的函数观测器问题化为对于降阶观测器左向量的限制条件,将满阶观测器转化为一些极点向着左半复数平面无限远渐近...研究了具有 m 维输出和 n 阶可观测的连续时间系统的具有任意极点最小阶数函数观测器的设计问题。文中将构成具有任意极点的函数观测器问题化为对于降阶观测器左向量的限制条件,将满阶观测器转化为一些极点向着左半复数平面无限远渐近的降阶观测器,在此基础上给出在μ≤m 时具有任意极点函数观测器的最小阶数及μ>m 时最小阶数的上限。展开更多
The state-space representation of linear time-invariant (LTI) fractional order systems is introduced, and a proof of their stability theory is also given. Then an efficient identification algorithm is proposed for tho...The state-space representation of linear time-invariant (LTI) fractional order systems is introduced, and a proof of their stability theory is also given. Then an efficient identification algorithm is proposed for those fractional order systems. The basic idea of the algorithm is to compute fractional derivatives and the filter simultaneously, i.e., the filtered fractional derivatives can be obtained by computing them in one step, and then system identification can be fulfilled by the least square method. The instrumental variable method is also used in the identification of fractional order systems. In this way, even if there is colored noise in the systems, the unbiased estimation of the parameters can still be obtained. Finally an example of identifying a viscoelastic system is given to show the effectiveness of the aforementioned method.展开更多
本文设计出一种针对脉冲噪声的二维鲁棒高分辨率波达方向(DOA,Direction of Arrival)估计算法,以解决雷达、声纳等无线通信领域中脉冲噪声环境下IAA(Iterative Adaptive Approach)无法准确估计出DOA的问题.该算法中,用最小p阶范数代替WL...本文设计出一种针对脉冲噪声的二维鲁棒高分辨率波达方向(DOA,Direction of Arrival)估计算法,以解决雷达、声纳等无线通信领域中脉冲噪声环境下IAA(Iterative Adaptive Approach)无法准确估计出DOA的问题.该算法中,用最小p阶范数代替WLS(Weighted Least Squares)作为最优化求解的代价函数.此外,根据Toeplitz-Block-Toeplitz(TBT)矩阵性质和FFT简化计算过程,提出该算法的快速实现方法,提高算法的计算效率.该算法在对称α-稳定(SαS,Symmetric Alpha-Stable)分布噪声环境下建模,仿真结果表明:与CRCO-MUSIC(Co Rrentropy based COrrelationMUltiple Signal Classification)算法和MUSIC-FLOM(MUltiple Signal Classification-Fractional Lower-Order Moment)算法相比,二维lp-IAA算法可以在低信噪比、单快拍条件下有效分辨出相邻多目标信号;快速算法可以在保证高分辨率的前提下,算法平均运算时间降低至原来的约1/40.展开更多
The generalized Tikhonov regularization method is one of the most classical methods for the solution of linear systems of equations that arise from the discretization of linear ill-posed problems.However,the approxima...The generalized Tikhonov regularization method is one of the most classical methods for the solution of linear systems of equations that arise from the discretization of linear ill-posed problems.However,the approximate solution obtained by the Tikhonov regularization method in general form may lack many details of the exact solution.Combining the fractional Tikhonov method with the preconditioned technique,and using the discrepancy principle for determining the regularization parameter,we present a preconditioned projected fractional Tikhonov regularization method for solving discrete ill-posed problems.Numerical experiments illustrate that the proposed algorithm has higher accuracy compared with the existing classical regularization methods.展开更多
We are concerned with the existence of least energy solutions of nonlinear Schrodinger equations involving the fractional Laplacian（-△）%s u（x）＋λV（x）u（x）=u（x）^（p-1）,u（x）〉=0,x∈R^N,for sufficiently lar...We are concerned with the existence of least energy solutions of nonlinear Schrodinger equations involving the fractional Laplacian（-△）%s u（x）＋λV（x）u（x）=u（x）^（p-1）,u（x）〉=0,x∈R^N,for sufficiently large λ,2〈p〈N-2s^-2N for N≥2. V（x） is a real continuous function on RN. Using variational methods we prove the existence of least energy solution uλ（x） which localizes near the potential well int V-1 （0） for A large. Moreover, if the zero sets int V-1 （0） of V（x） include more than one isolated component, then ux（x） will be trapped around all the isolated components. However, in Laplacian case s = 1, when the parameter A is large, the corresponding least energy solution will be trapped around only one isolated component and become arbitrarily small in other components of int V^-1（0）. This is the essential difference with the Laplacian problems since the operator （-△）s is nonlocal.展开更多
文摘研究了具有 m 维输出和 n 阶可观测的连续时间系统的具有任意极点最小阶数函数观测器的设计问题。文中将构成具有任意极点的函数观测器问题化为对于降阶观测器左向量的限制条件,将满阶观测器转化为一些极点向着左半复数平面无限远渐近的降阶观测器,在此基础上给出在μ≤m 时具有任意极点函数观测器的最小阶数及μ>m 时最小阶数的上限。
文摘The state-space representation of linear time-invariant (LTI) fractional order systems is introduced, and a proof of their stability theory is also given. Then an efficient identification algorithm is proposed for those fractional order systems. The basic idea of the algorithm is to compute fractional derivatives and the filter simultaneously, i.e., the filtered fractional derivatives can be obtained by computing them in one step, and then system identification can be fulfilled by the least square method. The instrumental variable method is also used in the identification of fractional order systems. In this way, even if there is colored noise in the systems, the unbiased estimation of the parameters can still be obtained. Finally an example of identifying a viscoelastic system is given to show the effectiveness of the aforementioned method.
文摘本文设计出一种针对脉冲噪声的二维鲁棒高分辨率波达方向(DOA,Direction of Arrival)估计算法,以解决雷达、声纳等无线通信领域中脉冲噪声环境下IAA(Iterative Adaptive Approach)无法准确估计出DOA的问题.该算法中,用最小p阶范数代替WLS(Weighted Least Squares)作为最优化求解的代价函数.此外,根据Toeplitz-Block-Toeplitz(TBT)矩阵性质和FFT简化计算过程,提出该算法的快速实现方法,提高算法的计算效率.该算法在对称α-稳定(SαS,Symmetric Alpha-Stable)分布噪声环境下建模,仿真结果表明:与CRCO-MUSIC(Co Rrentropy based COrrelationMUltiple Signal Classification)算法和MUSIC-FLOM(MUltiple Signal Classification-Fractional Lower-Order Moment)算法相比,二维lp-IAA算法可以在低信噪比、单快拍条件下有效分辨出相邻多目标信号;快速算法可以在保证高分辨率的前提下,算法平均运算时间降低至原来的约1/40.
基金supported in part by the National Natural Science Foundation of China(No.62073161)the Fundamental Research Funds 2019“Artificial Intelligence+Special Project”of Nanjing University of Aeronautics and Astronautics(No.2019009)
文摘The generalized Tikhonov regularization method is one of the most classical methods for the solution of linear systems of equations that arise from the discretization of linear ill-posed problems.However,the approximate solution obtained by the Tikhonov regularization method in general form may lack many details of the exact solution.Combining the fractional Tikhonov method with the preconditioned technique,and using the discrepancy principle for determining the regularization parameter,we present a preconditioned projected fractional Tikhonov regularization method for solving discrete ill-posed problems.Numerical experiments illustrate that the proposed algorithm has higher accuracy compared with the existing classical regularization methods.
基金supported by National Natural Science Foundation of China (Grant No. 11171028)
文摘We are concerned with the existence of least energy solutions of nonlinear Schrodinger equations involving the fractional Laplacian（-△）%s u（x）＋λV（x）u（x）=u（x）^（p-1）,u（x）〉=0,x∈R^N,for sufficiently large λ,2〈p〈N-2s^-2N for N≥2. V（x） is a real continuous function on RN. Using variational methods we prove the existence of least energy solution uλ（x） which localizes near the potential well int V-1 （0） for A large. Moreover, if the zero sets int V-1 （0） of V（x） include more than one isolated component, then ux（x） will be trapped around all the isolated components. However, in Laplacian case s = 1, when the parameter A is large, the corresponding least energy solution will be trapped around only one isolated component and become arbitrarily small in other components of int V^-1（0）. This is the essential difference with the Laplacian problems since the operator （-△）s is nonlocal.
