The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Meimei Sun - One of the best experts on this subject based on the ideXlab platform.

  • adaptive iterative learning control for a class of nonlinear time varying systems with unknown delays and input dead zone
    IEEE CAA Journal of Automatica Sinica, 2014
    Co-Authors: Jianming Wei, Meimei Sun
    Abstract:

    This paper presents an adaptive iterative learning control (AILC) scheme for a class of nonlinear systems with unknown time-varying delays and unknown input dead-zone. A novel nonlinear form of dead-zone nonlinearity is presented. The assumption of identical initial condition for iterative learning control (ILC) is removed by introducing boundary layer Function. The uncertainties with time-varying delays are compensated for by using appropriate Lyapunov-Krasovskii Functional and Young's inequality. Radial basis Function neural networks are used to model the time-varying uncertainties. The Hyperbolic Tangent Function is employed to avoid the problem of singularity. According to the property of Hyperbolic Tangent Function, the system output is proved to converge to a small neighborhood of the desired trajectory by constructing Lyapunov-like composite energy Function (CEF) in two cases, while keeping all the closed-loop signals bounded. Finally, a simulation example is presented to verify the effectiveness of the proposed approach.

Sunil Kumar Dube - One of the best experts on this subject based on the ideXlab platform.

  • Hyperbolic Tangent Function based least mean square control algorithm for distribution static compensator
    Iet Generation Transmission & Distribution, 2014
    Co-Authors: Bhim Singh, Sunil Kumar Dube, Sabha Raj Arya
    Abstract:

    A variable learning rate least mean-square (LMS) based on Hyperbolic Tangent Function is used to enhance the rate of convergence and to suppress the existing noise in the system for the control of distribution static compensator (DSTATCOM) consisting of a three-leg voltage source converter (VSC) with a zig-zag transformer to eliminate the significant neutral current caused by non-linear unbalanced loads in a three-phase four-wire supply system. Simulation is made for the proposed control algorithm in three-phase four-wire DSTATCOM system and its performance is compared with the conventional Adaline-based LMS control algorithm. It is also shown that the convergence rate of the proposed control algorithm is quite faster in comparison with the conventional control algorithm. A prototype of DSTATCOM is developed and the real-time implementation of the proposed control algorithm is performed on a digital signal processor. Test results have demonstrated the satisfactory performance of DSTATCOM with the proposed control algorithm under linear and non-linear loads.

  • load leveling and voltage control of permanent magnet synchronous generator based dg set for standalone supply system
    IEEE Transactions on Industrial Informatics, 2014
    Co-Authors: Bhim Singh, Ram Niwas, Sunil Kumar Dube
    Abstract:

    This paper deals with the voltage control and load leveling of permanent magnet synchronous generator (PMSG)-based diesel generator (DG) set for standalone supply system. The proposed system is composed of a PMSG and a prototype of diesel engine (DE), along with the distribution static compensator (DSTATCOM) and battery energy storage system (BESS). The DSTATCOM along with BESS is used for loads leveling and voltage control. It also provides balancing of loads, elimination of harmonics, and compensation of reactive power. The battery on dc link of voltage source converter (VSC) of DSTATCOM is used to supply the active power when the load is more than PMSG rating, and it stores the energy during light load periods. The PMSG is always loaded with an optimum load of 80%-100% of its rating. An optimum loading of DG set helps in improving the fuel efficiency of the DE and also helps in load leveling. The reference source currents are estimated using a Hyperbolic Tangent Function-based least mean square (LMS) algorithm. This control algorithm has reduced computation and provides fast convergence rate to eliminate the effect of noise as compared with other LMS algorithms based on adaptive filtering. The voltage control, load compensation, and fuel efficiency improvement in PMSG-based DG set using BESS and DSTATCOM controlled by Hyperbolic Tangent Function-based LMS algorithm are the main contributions of this paper.

Jianming Wei - One of the best experts on this subject based on the ideXlab platform.

  • adaptive iterative learning control for a class of nonlinear time varying systems with unknown delays and input dead zone
    IEEE CAA Journal of Automatica Sinica, 2014
    Co-Authors: Jianming Wei, Meimei Sun
    Abstract:

    This paper presents an adaptive iterative learning control (AILC) scheme for a class of nonlinear systems with unknown time-varying delays and unknown input dead-zone. A novel nonlinear form of dead-zone nonlinearity is presented. The assumption of identical initial condition for iterative learning control (ILC) is removed by introducing boundary layer Function. The uncertainties with time-varying delays are compensated for by using appropriate Lyapunov-Krasovskii Functional and Young's inequality. Radial basis Function neural networks are used to model the time-varying uncertainties. The Hyperbolic Tangent Function is employed to avoid the problem of singularity. According to the property of Hyperbolic Tangent Function, the system output is proved to converge to a small neighborhood of the desired trajectory by constructing Lyapunov-like composite energy Function (CEF) in two cases, while keeping all the closed-loop signals bounded. Finally, a simulation example is presented to verify the effectiveness of the proposed approach.

Enis A Cetin - One of the best experts on this subject based on the ideXlab platform.

  • time scale wavelet scattering using Hyperbolic Tangent Function for vessel sound classification
    European Signal Processing Conference, 2017
    Co-Authors: Gokmen Can, Cem Emre Akbas, Enis A Cetin
    Abstract:

    We introduce a time-frequency scattering method using Hyperbolic Tangent Function for vessel sound classification. The sound data is wavelet transformed using a two channel filter-bank and filter-bank outputs are scattered using tanh Function. A feature vector similar to mel-scale cepstrum is obtained after a wavelet packed transform-like structure approximating the mel-frequency scale. Feature vectors of vessel sounds are classified using a support vector machine (SVM). Experimental results are presented and the new feature extraction method produces better classification results than the ordinary Mel-Frequency Cepstral Coefficients (MFCC) vectors.

Feng Xiao - One of the best experts on this subject based on the ideXlab platform.

  • short note an interface capturing method with a continuous Function the thinc method on unstructured triangular and tetrahedral meshes
    Journal of Computational Physics, 2014
    Co-Authors: Bin Xie, Feng Xiao
    Abstract:

    A novel interface-capturing method is proposed to compute moving interfaces on unstructured grids with triangular (2D) and tetrahedral (3D) elements. Different from the conventional VOF (volume of fluid) method which involves geometric reconstructions of the interface, the present method is based on the algebraic reconstruction approach originally developed in the THINC (Tangent of hyperbola interface capturing) scheme by Xiao et al. (2005) [17]. A continuous multidimensional Hyperbolic Tangent Function is employed for retrieving the jump-like distribution of the indicator Function, which avoids the explicit geometric representation of the interface and thus substantially reduces the algorithmic complexity in unstructured grids. Numerical diffusion and smearing are effectively eliminated, and the compact thickness of the jump transition layer in the volume fraction is retained throughout the computation even for largely deformed interface. The solution quality of the present scheme is comparable to the VOF method with PLIC (piecewise linear interface calculation) algorithm.

  • an interface capturing method with a continuous Function the thinc method with multi dimensional reconstruction
    Journal of Computational Physics, 2012
    Co-Authors: Kazuyasu Sugiyama, Shintaro Takeuchi, Shu Takagi, Yoichiro Matsumoto, Feng Xiao
    Abstract:

    An interface capturing method with a continuous Function is proposed within the framework of the volume-of-fluid (VOF) method. Being different from the traditional VOF methods that require a geometrical reconstruction and identify the interface by a discontinuous Heaviside Function, the present method makes use of the Hyperbolic Tangent Function (known as one of the sigmoid type Functions) in the Tangent of hyperbola interface capturing (THINC) method [F. Xiao, Y. Honma, K. Kono, A simple algebraic interface capturing scheme using Hyperbolic Tangent Function, Int. J. Numer. Methods Fluids 48 (2005) 1023-1040] to retrieve the interface in an algebraic way from the volume-fraction data of multi-component materials. Instead of the 1D reconstruction in the original THINC method, a multi-dimensional Hyperbolic Tangent Function is employed in the present new approach. The present scheme resolves moving interface with geometric faithfulness and compact thickness, and has at least the following advantages: (1) the geometric reconstruction is not required in constructing piecewise approximate Functions; (2) besides a piecewise linear interface, curved (quadratic) surface can be easily constructed as well; and (3) the continuous multi-dimensional Hyperbolic Tangent Function allows the direct calculations of derivatives and normal vectors. Numerical benchmark tests including transport of moving interface and incompressible interfacial flows are presented to validate the numerical accuracy for interface capturing and to show the capability for practical problems such as a stationary circular droplet, a drop oscillation, a shear-induced drop deformation and a rising bubble.

  • a simple algebraic interface capturing scheme using Hyperbolic Tangent Function
    International Journal for Numerical Methods in Fluids, 2005
    Co-Authors: Feng Xiao, Y Honma, T Kono
    Abstract:

    This paper presents a simple and practical scheme for capturing moving interfaces or free boundaries in multi-fluid simulations. The scheme, which is called THINC (Tangent of hyperbola for interface capturing), makes use of the Hyperbolic Tangent Function to compute the numerical flux for the fluid fraction Function, and gives a conservative, oscillation-less and smearing-less solution to the fluid fraction Function even for the extremely distorted interfaces of arbitrary complexity. The numerical results from the THINC scheme possess adequate quality for practical applications, which make the extra geometric reconstruction, such as those in most of the volume of fluid (VOF) methods unnecessary. Thus the scheme is quite simple. The numerical tests show that the THINC scheme has competitive accuracy compared to most exiting methods. Copyright © 2005 John Wiley & Sons, Ltd.