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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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Fast numerical algorithm for a high-precision 6D electromagnetic positioning navigation system

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TURKISH JOURNAL OF PHYSICS 2014年第2期38卷 165-173页

作者： Xiang, Qian Wang, Shiqing Liu, Haifeng Southwestern Inst Phys Chengdu Sichuan Peoples R China Chengdu Univ Technol Engn & Tech Coll Inst Nucl Engn & Technol Leshan Peoples R China

A fast numerical algorithm is proposed for the 6 degrees of freedom electromagnetic navigation system, which can be used to improve surgical operations guided by medical images. Both the rotation transformation technique and optimization technique are adopted in the algorithm. The results from simulations show that the calculating time is improved greatly under the required precision in the surgery. A navigation system based on the algorithm can make the medical device's dimensions miniaturized and the structure simplified and portable. The performance and application scope of the electromagnetic positioning navigation system can be improved.

关键词： Six degrees of freedom electromagnetic positioning navigation numerical algorithm

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A numerical algorithm for Nuclear Reaction in Deuterium-Tritium Plasma

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FUSION SCIENCE AND TECHNOLOGY 2019年第4期75卷 317-323页

作者： Pan, Dongmei Zhao, Zijia Chen, Zhong Lv, Zhongliang Li, Junhan Univ Sci & Technol China Sch Nucl Sci & Technol Hefei 230027 Anhui Peoples R China Natl Univ Def Technol Coll Liberal Arts & Sci Changsha 230027 Hunan Peoples R China Southwest Sci & Technol Univ Sch Natl Def Sci & Technol Mianyang 621000 Sichuan Peoples R China

Rates of neutron production in deuterium-tritium (D-T) plasmas below the temperature of 100keV have been widely studied with analytical cross sections based on nuclear physics. In the present work, a new algorithm of numerical simulation using the latest nuclear database ENDF/B-VII, discrete ordinate (S-N) method, and Monte Carlo methods was developed to describe nuclear reactions in D-T plasma. Compared with the method that used analytical cross section, this new method can predict the nuclear reaction in plasma to several hundreds of kilo-electron-volts and has the potential to give information about directionality of the neutron flux and other interesting nuclear reactions, if needed.

关键词： Deuterium-tritium plasma neutron source nuclear database numerical algorithm

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An efficient numerical algorithm for stability testing of fractional-delay systems

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ISA TRANSACTIONS 2009年第1期48卷 32-37页

作者： Merrikh-Bayat, Farshad Karimi-Ghartemani, Masoud Sharif Univ Technol Tehran Iran

This paper presents a numerical algorithm for BIBO stability testing of a certain class of the so-called fractional-delay systems. The characteristic function of the systems under consideration is a multi-valued function of the Laplace variable s which is defined on a Riemann surface with finite number of Riemann sheets where the origin is a branch point. The stability analysis of such systems is not straightforward because there is no universally applicable analytical method to find the roots of the characteristic equation on the right half-plane of the first Riemann sheet. The proposed method is based on the Rouche's theorem which provides the number of the zeros of a given function in a given simple closed contour. One advantage of the proposed method over previous works is that it gives the number and the location of the unstable poles. The algorithm has a reliable result which is illustrated by several examples. (C) 2008 ISA. Published by Elsevier Ltd. All rights reserved.

关键词： Fractional delay equation Stability analysis numerical algorithm Fractional-order system

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

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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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A numerical algorithm for calculating microbial survival curves during thermal processing

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FOOD RESEARCH INTERNATIONAL 2007年第1期40卷 203-208页

作者： Chen, Guibing Campanella, Osvaldo H. Corvalan, Carlos M. Purdue Univ Dept Agr & Biol Engn W Lafayette IN 47907 USA Purdue Univ Dept Food Sci W Lafayette IN 47907 USA

Assuming that the targeted microorganism's isothermal survival curves follow the Weibullian pattern, which describes a large number of microbial isothermal survival curves, a simple numerical algorithm was developed to calculate the momentary survival ratio during non-isothermal thermal processes. The algorithm is based on a mathematical expression derived from a non-isothermal survival rate model proposed in the literature. Simulations indicated that the proposed algorithm generated the same results as those obtained from other non-isothermal models found in the literature. However, compared to the published models, the proposed algorithm has two advantages. One is that the calculation speed is very fast because only simple algebraic operations are involved, and the other is that it can be programmed very easily in different computer languages and spreadsheets. In addition, the algorithm provides an effective way to estimate changes of microbial survival ratio with time from product temperatures that are either directly measured during thermal processing or predicted by proper heat transfer models. Thus, the algorithm can also be easily incorporated into control systems of commercial thermal process equipment. (c) 2006 Elsevier Ltd. All rights reserved.

关键词： numerical algorithm microbial survival curves thermal processing Weibullian model

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An implicit numerical algorithm for solving non-hydrostatic free-surface flow problems

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INTERNATIONAL JOURNAL FOR numerical METHODS IN FLUIDS 2001年第3期35卷 341-356页

作者： Namin, MM Lin, B Falconer, RA Cardiff Univ Cardiff Sch Engn Cardiff CF2 3TB S Glam Wales

Details are given of the development of a two-dimensional vertical numerical model for simulating unsteady free-surface flows, using a non-hydrostatic pressure distribution. In this model, the Reynolds equations and the kinematic free-surface boundary condition are solved simultaneously, so that the water surface elevation can be integrated into the solution and solved for, together with the velocity and pressure fields. An efficient numerical algorithm has been developed, deploying implicit parameters similar to those used in the Crank-Nicholson method, and generating a block tri-diagonal algebraic system of equations. The model has been applied to simulate a range of unsteady flow problems involving relatively strong vertical accelerations. The results show that the numerical algorithm described is able to produce accurate predictions and is also easy to apply. Copyright (C) 2001 John Wiley & Sons, Ltd.

关键词： free-surface flow hydrodynamic modelling non-hydrostatic pressure distribution 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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