Adaptive digital filtering has traditionally been developed based on the minimum mean square error （MMSE） criterion and has found ever-increasing applications in communications. This paper presents an alternative ad...Adaptive digital filtering has traditionally been developed based on the minimum mean square error （MMSE） criterion and has found ever-increasing applications in communications. This paper presents an alternative adaptive filtering design based on the minimum symbol error rate （MSER） criterion for communication applications. It is shown that the MSER filtering is smarter, as it exploits the non-Gaussian distribution of filter output effectively. Consequently, it provides significant performance gain in terms of smaller symbol error over the MMSE approach. Adopting Parzen window or kernel density estimation for a probability density function, a block-data gradient adaptive MSER algorithm is derived. A stochastic gradient adaptive MSER algorithm, referred to as the least symbol error rate, is further developed for sample-by-sample adaptive implementation of the MSER filtering. Two applications, involving single-user channel equalization and beamforming assisted receiver, are included to demonstrate the effectiveness and generality of the proposed adaptive MSER filtering approach.展开更多
In this paper,an adaptive nonsingular fast terminal sliding mode control(ANFTSMC)is proposed for underwater manipulator robotics with asymmetric actuator saturations and unknown time-varying(TV)external disturbances.F...In this paper,an adaptive nonsingular fast terminal sliding mode control(ANFTSMC)is proposed for underwater manipulator robotics with asymmetric actuator saturations and unknown time-varying(TV)external disturbances.Firstly,the nonsingular fast terminal sliding mode(NFTSM)control scheme is conducted for the underwater manipulator robotics,which guarantees the boundedness of all the signals in the control system.Secondly,the adaptive method and the smooth hyperbolic tangent(tanh)function are introduced to address the unknown TV external disturbances and the input saturation errors.Thus the prior knowledge about the upper bounds of the system uncertainties is not needed in this paper.To deal with the nonlinear asymmetric input saturation issue,a Gaussian error function is employed in the asymmetric saturation module so that the discontinuous input signals can be transformed into smooth forms.Thirdly,the rigorous mathematical verification is conducted to demonstrate the stability and finite-time convergence of the closed-loop control system via the Lyapunov theory.Finally,numerical simulations are performed on a two-link underwater manipulator robotic system to illustrate the effectiveness of the proposed controller.展开更多
It＇s well-known that there is a very powerful error bound for Gaussians put forward by Madych and Nelson in 1992. It＇s of the form｜f（x） - s（x）｜≤（Cd）c/d｜｜f｜｜h where C, c are constants, h is the Gaussian ...It＇s well-known that there is a very powerful error bound for Gaussians put forward by Madych and Nelson in 1992. It＇s of the form｜f（x） - s（x）｜≤（Cd）c/d｜｜f｜｜h where C, c are constants, h is the Gaussian function, s is the interpolating function, and d is called fill distance which, roughly speaking, measures the spacing of the points at which interpolation occurs. This error bound gets small very fast as d → 0. The constants C and c are very sensitive. A slight change of them will result in a huge change of the error bound. The number c can be calculated as shown in [9]. However, C cannot be calculated, or even approximated. This is a famous question in the theory of radial basis functions. The purpose of this paper is to answer this question.展开更多
Several numerical integration schemes for the evaluation of matrix elements in density functional theory calculations have been studied and compared by computational practice. The best scheme was found to be the combi...Several numerical integration schemes for the evaluation of matrix elements in density functional theory calculations have been studied and compared by computational practice. The best scheme was found to be the combination of the atomic partition function proposed by Becke with the scaled generalized Gauss-Laguerre quadrature formula for radial integration suggested by Yang, which achieve the highest convergence rate to the numerical integration. With the same number of integration points, the accuracy of the calculated results by this scheme is higher by 1 to 2 orders of magnitudes than that by other schemes. The reason for achieving higher accuracy by this scheme has been proposed preliminarily.展开更多
文摘Adaptive digital filtering has traditionally been developed based on the minimum mean square error （MMSE） criterion and has found ever-increasing applications in communications. This paper presents an alternative adaptive filtering design based on the minimum symbol error rate （MSER） criterion for communication applications. It is shown that the MSER filtering is smarter, as it exploits the non-Gaussian distribution of filter output effectively. Consequently, it provides significant performance gain in terms of smaller symbol error over the MMSE approach. Adopting Parzen window or kernel density estimation for a probability density function, a block-data gradient adaptive MSER algorithm is derived. A stochastic gradient adaptive MSER algorithm, referred to as the least symbol error rate, is further developed for sample-by-sample adaptive implementation of the MSER filtering. Two applications, involving single-user channel equalization and beamforming assisted receiver, are included to demonstrate the effectiveness and generality of the proposed adaptive MSER filtering approach.
基金supported by the National Natural Science Foundation of China(No.51979116)the HUST Interdisciplinary Innovation Team Project,the Innovation Foundation of Maritime Defense Technologies Innovation Center and the Fundamental Research Funds for the Central Universities(HUST:2018JYCXJJ045,HUST:2018KFYYXJJ012).
文摘In this paper,an adaptive nonsingular fast terminal sliding mode control(ANFTSMC)is proposed for underwater manipulator robotics with asymmetric actuator saturations and unknown time-varying(TV)external disturbances.Firstly,the nonsingular fast terminal sliding mode(NFTSM)control scheme is conducted for the underwater manipulator robotics,which guarantees the boundedness of all the signals in the control system.Secondly,the adaptive method and the smooth hyperbolic tangent(tanh)function are introduced to address the unknown TV external disturbances and the input saturation errors.Thus the prior knowledge about the upper bounds of the system uncertainties is not needed in this paper.To deal with the nonlinear asymmetric input saturation issue,a Gaussian error function is employed in the asymmetric saturation module so that the discontinuous input signals can be transformed into smooth forms.Thirdly,the rigorous mathematical verification is conducted to demonstrate the stability and finite-time convergence of the closed-loop control system via the Lyapunov theory.Finally,numerical simulations are performed on a two-link underwater manipulator robotic system to illustrate the effectiveness of the proposed controller.
文摘It＇s well-known that there is a very powerful error bound for Gaussians put forward by Madych and Nelson in 1992. It＇s of the form｜f（x） - s（x）｜≤（Cd）c/d｜｜f｜｜h where C, c are constants, h is the Gaussian function, s is the interpolating function, and d is called fill distance which, roughly speaking, measures the spacing of the points at which interpolation occurs. This error bound gets small very fast as d → 0. The constants C and c are very sensitive. A slight change of them will result in a huge change of the error bound. The number c can be calculated as shown in [9]. However, C cannot be calculated, or even approximated. This is a famous question in the theory of radial basis functions. The purpose of this paper is to answer this question.
基金Supported by State Major Key Project for Basic Researches and the National Natural Science Foundation of China.
文摘Several numerical integration schemes for the evaluation of matrix elements in density functional theory calculations have been studied and compared by computational practice. The best scheme was found to be the combination of the atomic partition function proposed by Becke with the scaled generalized Gauss-Laguerre quadrature formula for radial integration suggested by Yang, which achieve the highest convergence rate to the numerical integration. With the same number of integration points, the accuracy of the calculated results by this scheme is higher by 1 to 2 orders of magnitudes than that by other schemes. The reason for achieving higher accuracy by this scheme has been proposed preliminarily.
