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A novel numerical algorithm based on self-tuning controller to support TCP flows

MATHEMATICS AND COMPUTERS IN SIMULATION 2008年第4期79卷 1178-1188页

作者： Xiong, N. Yang, L. T. Yang, Y. Defago, X. He, Y. Japan Adv Inst Sci & Technol Sch Informat Sci Nomi Ishikawa 9231211 Japan Wuhan Univ State Key Lab Software Engn Wuhan Peoples R China St Francis Xavier Univ Dept Comp Sci Antigonish NS B2G 1C0 Canada

Active queue management (AQM) is an effective method used in Internet routers for congestion control, and to achieve a trade off between link utilization and delay. The de facto standard, the random early detection (RED) AQM scheme, and most of its variants use average queue length as a congestion indicator to trigger packet dropping. This paper proposes a novel numerical algorithm based on self-tuning control circuit, called loss ratio and rate control RED (LRC-RED), to regulate the queue length with small variation and to achieve high utilization with small packet loss. This scheme is based on random early detection (RED) of the loss ratio and the total send rate control, and measures the latest packet loss ratio, then uses the latest packet loss ratio and the total input rate as complements to queue length in order to dynamically adjust packet drop probability. Furthermore, we also give a theoretical analysis of system stability and develop a simple, scalable and systematic guideline for the selection of feedback gains for the dynamic TCP/RED system to stabilize the queue length at a desirable level. Extensive simulations have been conducted with ns - 2. The simulation results have demonstrated that the proposed LRC-RED algorithm outperforms the loss ratio-based RED (LRED) [C. Wang, B. Li, Y.T. Hou, K. Sohraby, Y. Lin, LRED: a robust active queue management scheme based on packet loss ratio. in: Proceedings of IEEE INFOCOM 2004, IEEE, 2004] algorithm in terms of stability, fast response time and robustness. (C) 2007 IMACS. Published by Elsevier B.V. All rights reserved.

关键词： Active queue management numerical algorithm Random early detection (RED) Congestion control TCP

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Analysis of seepage evolution law of rock mass based on the numerical algorithm considering strength weakening water absorption

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ARABIAN JOURNAL OF GEOSCIENCES 2018年第13期11卷 1-10页

作者： Guo, Ying Jiang, Xinliang Song, Zhifei Tianjin Univ Sch Civil Engn 92 Weijin Rd Tianjin 110032 Peoples R China Shenyang Univ Sch Civil Engn 21 Wanghua South St Shenyang 110044 Liaoning Peoples R China North China Univ Technol Sch Civil Engn 5 Jinyuanzhuang Rd Beijing 100144 Peoples R China

Conventional numerical methods for modeling water seepage hardly provide a realistic description for the associated degradation of rock material and the permeability evolution mechanism. A numerical algorithm was utilized to investigate the rock seepage evolution process and the course of deformation failure. A theoretical model for depicting the weakening of rocks modulus and strength caused by water absorption in rock substrate was developed, and the mathematical relationships are presented in this paper. The softening process of a siltstone specimen due to water absorption was simulated under low- and high-fluid pressures as the boundary condition based on the theoretical model. Moreover, uniaxial compression test was performed for the specimen under different time of water absorption. The results indicated that the higher the fluid pressure, the quicker that the rock specimen reached saturation. It was observed that at the beginning of a seepage process, the openings are mainly filled by free water, but as time proceeds, there is a transition from absorption of free water in openings to water absorption by rock substrate. Fluid pressure, as the boundary condition, has a controlling effect on seepage rate but barely has any effect on the rate of water absorption in rock substrate. As the time of water absorption increases, rock strength (cohesion and angle of internal friction) decreases gradually until reaching the residual value. The numerical estimation of the changes in water content of rock substrate over time agrees with the theoretical explanations, which indicates high precision of the developed numerical method.

关键词： Rock mass Seepage evolution Strength weakening numerical algorithm

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A fast numerical algorithm for a basic dual integral equation of the flapping wing in a flow of non-viscous incompressible fluid

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JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS 2018年 344卷 457-472页

作者： Popuzin, V. V. Sumbatyan, M. A. Tarasov, A. E. Southern Fed Univ Inst Math Mech & Comp Sci Milchakova St 8a Rostov Na Donu 344090 Russia

The present paper proposes a new approach to the classical problem of the harmonic oscillations of a thin wing in a flow of non-viscous incompressible fluid. The problem is reduced to a dual integral equation, permitting application of numerical methods. The numerical experiments are performed by using some advanced fast non-stationary iterative methods, with the help of the two-dimensional Fast Fourier Transform. There is given a brief survey on the iterative methods, to evaluate the most efficient algorithms in application to the considered problem of the flapping wing theory. (C) 2018 Elsevier B.V. All rights reserved.

关键词： Flapping wing Dual integral equation numerical algorithm Toeplitz blocks Conjugate gradients Bi-conjugate gradients

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A numerical algorithm of fuzzy reliability

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RELIABILITY ENGINEERING & SYSTEM SAFETY 2003年第3期80卷 299-307页

作者： Jiang, QM Chen, CH Nanyang Technol Univ Sch Mech & Prod Engn Singapore 639798 Singapore

In this paper, a computational model of fuzzy reliability focusing on solving the engineering problems with random general stress-fuzzy general strength is presented. The mathematical basis of this computational model is that the fuzzy probability can be computed with the computational method of conventional probability by use of a mathematical transition. Based on this computational model, a numerical algorithm is given which can be applied to compute the fuzzy reliability of mechanical components, sensors, electronic units, etc. This establishes a basis for the reliability analysis of systems consisting of components with fuzzy reliability. As an example, a case study about the fuzzy reliability analysis of a kind of sensor used in railway systems is provided to verify the logic of this algorithm. The computation results show that this algorithm fits the engineering experience. (C) 2003 Elsevier Science Ltd. All rights reserved.

关键词： numerical algorithm fuzzy reliability random general stress-fuzzy general strength model

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A numerical algorithm and a Variational Iteration Technique for Solving Higher Order Fuzzy Integro-differential Equations

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FUNDAMENTA INFORMATICAE 2014年第4期133卷 421-431页

作者： Narayanamoorthy, S. Murugan, K. Bharathiar Univ Dept Appl Math Coimbatore 641046 Tamil Nadu India

In this paper, we present an algorithmic form of the variational iteration method (VIM) to handle both linear and nonlinear higher order fuzzy integro-differential equations. Using parametric form of fuzzy numbers to convert higher order fuzzy integro-differential equation to a system of higher order integro-differential equations in crisp case. By using the variational integration method we find the approximate solution of this system and consequently we obtain an approximation for fuzzy solution of the higher order fuzzy integro-differential equations. The numerical results are examined.

关键词： numerical algorithm fuzzy number fuzzy integro-differential equations variational iteration method convergence

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An efficient numerical algorithm in the classical 3d theory of thin lifting surface in a flow of non-viscous incompressible fluid

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MECHANICS RESEARCH COMMUNICATIONS 2018年 89卷 18-22页

作者： Sumbatyan, M. A. Bondarchuk, A. A. Mescheryakov, K. I. Southern Fed Univ Milchakova St 8a Rostov Na Donu Russia

The work is devoted to a new semi-analytical method, to treat the classical dual integral equation of the lifting surface theory. The method operates with the initial form of the integral equation, and no preliminary ... 详细信息

关键词： Lifting surface theory Two-dimensional integral equation numerical algorithm

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Design of rectangular directional coupler using simple numerical algorithm

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ELECTRONICS LETTERS 1999年第8期35卷 627-628页

作者： Yun, JH Lee, JW Chae, JS Elect & Telecommun Res Inst Radio Technol Dept Yusong Gu Taejon 305350 South Korea

A simple numerical algorithm for the design of a rectangular directional coupler (RDC) with arbitrary couplings is proposed. The performance of a designed RDC is also described. It is seen that the measured data agree... 详细信息

关键词： numerical algorithm Waveguide and microwave transmission line components directional couplers rectangular directional coupler design

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Theoretical study on electronic excitation spectra: A matrix form of numerical algorithm for spectral shift

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CHEMICAL PHYSICS 2017年 492卷 27-34页

作者： Ming, Mei-Jun Xu, Long-Kun Wang, Fan Bi, Ting-Jun Li, Xiang-Yuan Sichuan Univ Coll Chem Chengdu 610064 Peoples R China Sichuan Univ Coll Chem Engn Chengdu 610065 Peoples R China Sichuan Univ Inst Atom & Mol Phys Chengdu 610065 Peoples R China

In this work, a matrix form of numerical algorithm for spectral shift is presented based on the novel nonequilibrium solvation model that is established by introducing the constrained equilibrium manipulation. This form is convenient for the development of codes for numerical solution. By means of the integral equation formulation polarizable continuum model (IEF-PCM), a subroutine has been implemented to compute spectral shift numerically. Here, the spectral shifts of absorption spectra for several popular chromophores, N,N-diethyl-p-nitroaniline (DEPNA), methylenecyclopropene (MCP), acrolein (ACL) and p-nitroaniline (PNA) were investigated in different solvents with various polarities. The computed spectral shifts can explain the available experimental findings reasonably. Discussions were made on the contributions of solute geometry distortion, electrostatic polarization and other non-electrostatic interactions to spectral shift. (C) 2017 Elsevier B.V. All rights reserved.

关键词： Nonequilibrium solvation Spectral shift Constrained equilibrium Vertical excitation energy numerical algorithm

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Calculation boundary vulnerability of numerical algorithm in milling stability prediction

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INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 2022年第11-12期119卷 8271-8286页

作者： Dai, Yuebang Li, Hongkun Liu, Bo Yang, Chao Dalian Univ Technol Sch Mech Engn Dalian 116024 Peoples R China

Though considerable efforts have been made to improve the precision of numerical algorithms for obtaining more accurate chatter stability prediction in milling process, a calculation boundary vulnerability, existing generally in numerical predictive methods, is usually ignored, which can significantly reduce accuracy of chatter stability prediction in certain calculated step lengths. Starting from the numerical solution of delay differential equation, this paper first gives a detailed mathematical derivation to demonstrate the beingness of the numerical calculation errors at the crucial step for two equal interval calculation methods of cutting force coefficients, and then discusses the impact of the errors on the convergence effect and prediction accuracy. Afterwards, the methods seeking and repairing the discrete number of time period with vulnerability are proposed, which are verified by the classic milling models. The presented technique could prevent this undesirable boundary vulnerability happening in numerical prediction of milling stability, and help the path planers obtain more accurate parameters which can achieve chatter free in the manufacturing process.

关键词： Chatter stability prediction numerical algorithm Calculation boundary vulnerability

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Symmetrical components estimation through nonrecursive Newton-type numerical algorithm

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IEEE TRANSACTIONS ON POWER DELIVERY 2003年第2期18卷 359-363页

作者： Terzija, VV Markovic, D Univ Belgrade Fac Elect Engn Belgrade Serbia Elektromorava YU-12000 Pozarevac Serbia

The paper reports new software developments for symmetrical components estimation. Nonrecursive Newton-type algorithm is extended with the second stage algorithm for symmetrical components calculation from the estimated fundamental phasors of three-phase signals (arbitrary voltages or currents). The algorithm is not sensitive to power system frequency changes and to the harmonic distortion of input signals. The algorithm is tested through computer simulations and by using laboratory obtained input signals and those recorded in the real distribution network.

关键词： Newton-type algorithm nonlinear estimation numerical algorithm symmetrical components

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