Atomistic/continuum coupling methods aim to achieve optimal balance between accuracy and efficiency. Adaptivity is the key for the efficient implementation of such methods. In this paper, we carry out a rigorous a pos...
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Atomistic/continuum coupling methods aim to achieve optimal balance between accuracy and efficiency. Adaptivity is the key for the efficient implementation of such methods. In this paper, we carry out a rigorous a posteriori analysis of the residual, the stability constant, and the error bound for a consistent atomistic/continuum coupling method in two dimensions. We design and implement the corresponding adaptive mesh refinement algorithm, and the convergence rate with respect to degrees of freedom is optimal compared with a priori error estimates.
This paper views the classical Chiu-Jain algorithm, originally proposed for congestion control of network links, as a decentralized algorithm for the fair allocation of a total of c units of a shared resource among n ...
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This paper views the classical Chiu-Jain algorithm, originally proposed for congestion control of network links, as a decentralized algorithm for the fair allocation of a total of c units of a shared resource among n users. A new analysis is given of the general case of additive increase and multiplicative decrease (AIMD) dynamics, from the perspective of virtual equilibria and variable structure systems, leading to a better understanding of the Chiu-Jain algorithm, which is one example of AIMD dynamics. It is shown that the variable structure discrete dynamical system that describes the evolution of the share of each individual, starting from an arbitrary initial allocation, always attains a neighbourhood of the fair share (c/n) for each user, under the assumption that the latter is known. Subsequently, a new adaptive version of the algorithm, called adaptive AIMD, is described, with the same property of converging to the fair share, without assuming that it is known. Simulations that show the behaviour and advantages of the proposed adaptive AIMD adaptive algorithm are given. Copyright (C) 2015 John Wiley & Sons, Ltd.
In this paper, we propose a normalization method dividing the gradient vector by the sum of the diagonal and two adjoining elements of the matrix expressing the correlation between the components of the discrete Fouri...
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In this paper, we propose a normalization method dividing the gradient vector by the sum of the diagonal and two adjoining elements of the matrix expressing the correlation between the components of the discrete Fourier transform (DFT) of the reference signal used for the identification of unknown system. The proposed method can thereby improve the estimation speed of coefficients of adaptive filter.
In this paper, we propose a parameter-free algorithm to calculate epsilon, a parameter of small quantity initially introduced into the nonlinear weights of weighted essentially nonoscillatory (WENO) scheme to avoid de...
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In this paper, we propose a parameter-free algorithm to calculate epsilon, a parameter of small quantity initially introduced into the nonlinear weights of weighted essentially nonoscillatory (WENO) scheme to avoid denominator becoming zero. The new algorithm, based on local smoothness indicators of fifth-order weighted compact nonlinear scheme (WCNS), is designed in a manner to adaptively increase epsilon in smooth areas to reduce numerical dissipation and obtain high-order accuracy, and decrease epsilon in discontinuous areas to increase numerical dissipation and suppress spurious numerical oscillations. We discuss the relation between critical points and discontinuities and illustrate that, when large gradient areas caused by high-order critical points are not well resolved with sufficiently small grid spacing, numerical oscillations arise. The new algorithm treats high-order critical points as discontinuities to suppress numerical oscillations. Canonical numerical tests are carried out, and computational results indicate that the new adaptive algorithm can help improve resolution of small scale flow structures, suppress numerical oscillations near discontinuities, and lessen susceptibility to flux functions and interpolation variables for fifth-order WCNS. The new adaptive algorithm can be conveniently generalized to WENO/WCNS with different orders.
OFDM is a good scheme to transmit high rate data under a multi-path environment. With a sufficiently long guard interval (GI), it is possible to totally eliminate interference between symbols or carriers with OFDM. Ho...
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OFDM is a good scheme to transmit high rate data under a multi-path environment. With a sufficiently long guard interval (GI), it is possible to totally eliminate interference between symbols or carriers with OFDM. However, long guard intervals reduce the spectrum efficiency of OFDM. Thus, shortening the guard interval as much as possible is highly desirable. As short guard intervals will usually result in interference in an OFDM system, an interference canceller would be necessary to enable the use of short guard intervals without unduly degrading system performance. This paper presents a possible adaptive interference cancellation scheme for OFDM to help attain this objective.
The vertex cover (VC) problem has been studied for past few years, and some centralized and distributed algorithms have been proposed. In this paper, we propose the so-called random memory length adaptive (RMLA) algor...
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The vertex cover (VC) problem has been studied for past few years, and some centralized and distributed algorithms have been proposed. In this paper, we propose the so-called random memory length adaptive (RMLA) algorithm for the VC problem in networks. Any initial state can reach the stable pure strict Nash equilibrium state through finite iterations by the RMLA algorithm. We find that by setting the minimum edge-keeping probability reasonably, the convergence rapidity and accuracy can be improved simultaneously. Our algorithm also removes the requirement for consistent node memory length. Through theoretical analysis and intensive numerical simulations, we verify the convergence and effectiveness of the RMLA algorithm.
The paper searches for solutions to the problem of detecting a signal from low-flying small-sized objects against the background of interference in the urban environment using radar stations. We propose an adaptive al...
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The paper searches for solutions to the problem of detecting a signal from low-flying small-sized objects against the background of interference in the urban environment using radar stations. We propose an adaptive algorithm that can be used in modern radar systems for detecting and tracking small objects. The developed adaptive algorithm for resolving signals reflected from low-flying objects allows us to take into account the multipath effect. A variant of the practical realization of the adaptive detection algorithm, implemented on an experimental sample of the X-range radar of wavelength, is presented.
The aim of this work is to compare different marking strategies, their influence on the work of adaptive algorithms with a posteriori error control for plane elasticity problems. The error control was performed using ...
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The aim of this work is to compare different marking strategies, their influence on the work of adaptive algorithms with a posteriori error control for plane elasticity problems. The error control was performed using a functional error majorant. The implemented adaptive algorithms were based on the functional error majorant with no symmetry limitation on the free tensor, computed using the zero-order Raviart–Thomas approximations on triangular meshes. The four most commonly used element-marking criteria were used in adaptation. Numerical results for several plane-strain problems have been presented, including the case of different materials and geometry. A comprehensive analysis of the obtained results was given.
作者：
Bu, WeipingQu, MinXiangtan Univ
Sch Math & Computat Sci Xiangtan 411105 Hunan Peoples R China Xiangtan Univ
Hunan Key Lab Computat & Simulat Sci & Engn Xiangtan 411105 Hunan Peoples R China
This study proposes a time-stepping L-1 scheme to approximate the linear fractional dynamical systems based on nonuniform mesh. The developed numerical scheme is unconditionally stable, and exhibits second-order accur...
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This study proposes a time-stepping L-1 scheme to approximate the linear fractional dynamical systems based on nonuniform mesh. The developed numerical scheme is unconditionally stable, and exhibits second-order accuracy when the suitable graded mesh is used. A posteriori error estimation is derived for the obtained numerical scheme and the corresponding adaptive algorithm is devised. Finally, two numerical examples are provided to demonstrate the effectiveness of our approach and verify the theoretical results.
By using a liquid crystal shutter to periodically modulate the infrared energy received by the on-board passive infrared (PIR) sensor, the synchronized low energy electronically chopped PIR sensor recently developed b...
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By using a liquid crystal shutter to periodically modulate the infrared energy received by the on-board passive infrared (PIR) sensor, the synchronized low energy electronically chopped PIR sensor recently developed by our team can detect stationary occupancy. However, the fixed threshold value-based detection accuracy is largely dependent on environmental settings, such as the room and floor surface temperature. In this letter, we first developed a thermoelectric model to quantify the environmental impact on the threshold value and then created an adaptive algorithm to generate temperature-sensitive threshold values to compensate environmental effects. We validated our thermoelectric model and tested our adaptive algorithm in two uncontrolled environmental settings, and results show that the detection accuracy reaches over 92%, which is much higher than that using the fixed threshold approach.
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