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A 3-dimensional well model in the flow transport through porous media

APPLIED MATHEMATICAL MODELLING 2014年第21-22期38卷 4949-4957页

作者： Zhang, Ting Lanzhou Univ Sch Math & Stat Lanzhou 730000 Gansu Peoples R China

In petroleum extraction and exploitation, the well is usually treated as a point or line source, due to its radius is much smaller comparing with the scale of the whole reservoir. Especially, in 3-dimensional situation, the well is regarded as a line source. In this paper, we analyze the modeling error for this treatment for steady flows through porous media and present a new algorithm for line-style well to characterize the wellbore flow potential. We also provide a numerical example to demonstrate the effectiveness of the proposed method. (C) 2014 Elsevier Inc. All rights reserved.

关键词： Well model Error estimate numerical algorithm

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Analysis and Verification of Repetitive Motion Planning and Feedback Control for Omnidirectional Mobile Manipulator Robotic Systems

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JOURNAL OF INTELLIGENT & ROBOTIC SYSTEMS 2014年第3-4期75卷 393-411页

作者： Zhang, Yunong Li, Weibing Liao, Bolin Guo, Dongsheng Peng, Chen Sun Yat Sen Univ Sch Informat Sci & Technol Guangzhou 510006 Guangdong Peoples R China Jishou Univ Coll Informat Sci & Engn Jishou 416000 Peoples R China

Mobile manipulator robotic systems (MMRSs) composed of a manipulator and a mobile platform are investigated in this paper. In order for the mobile manipulator robotic system (MMRS) to return to its initial state when the manipulator's end-effector is requested to execute cyclical tasks, a quadratic program (QP) based repetitive motion planning and feedback control (RMPFC) scheme is proposed and analyzed. Such an RMPFC scheme can not only mix motion planning and reactive control, but also consider the physical limits of the robotic system. Mathematically, the efficacy of the RMPFC scheme is verified via gradient dynamics analysis. To further demonstrate the effectiveness of the RMPFC scheme, a kinematically redundant MMRS composed of a three degrees-of-freedom (DOF) planar manipulator and an omnidirectional mobile platform is designed, modeled and analyzed. Then, repetitive motion planning and feedback control for the designed omnidirectional MMRS is studied. Besides, a numerical algorithm is developed and presented to solve the QP and resolve the redundancy of the robotic system. Moreover, computer simulations are comparatively performed on such an omnidirectional MMRS, and simulation results substantiate the effectiveness, accuracy and superiority of the proposed RMPFC scheme.

关键词： Mobile manipulator robotic system Quadratic program Repetitive motion planning Feedback control numerical algorithm

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Baselining network-wide traffic by time-frequency constrained Stable Principal Component Pursuit

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AEU-INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS 2014年第8期68卷 756-762页

作者： Hu, Kai Wang, Zhe Yin, Baolin Beihang Univ State Key Lab Software Dev Environm Beijing 100191 Peoples R China

The Internet traffic analysis is important to network management, and extracting the baseline traffic patterns is especially helpful for some significant network applications. In this paper, we study on the baseline problem of the traffic matrix satisfying a refined traffic matrix decomposition model, since this model extends the assumption of the baseline traffic component to characterize its smoothness, and is more realistic than the existing traffic matrix models. We develop a novel baseline scheme, named Stable Principal Component Pursuit with Time-Frequency Constraints (SPCP-TFC), which extends the Stable Principal Component Pursuit (SPCP) by applying new time-frequency constraints. Then we design an efficient numerical algorithm for SPCP-TFC. At last, we evaluate this baseline scheme through simulations, and show it has superior performance than the existing baseline schemes RBL and PCA. (C) 2014 Elsevier GmbH. All rights reserved.

关键词： Baseline of traffic matrix Robust PCA Time-frequency constraint numerical algorithm Simulation

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CONFORMING DELAUNAY TRIANGULATION OF STOCHASTICALLY GENERATED THREE DIMENSIONAL DISCRETE FRACTURE NETWORKS: A FEATURE REJECTION algorithm FOR MESHING STRATEGY

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SIAM JOURNAL ON SCIENTIFIC COMPUTING 2014年第4期36卷 A1871-A1894页

作者： Hyman, Jeffrey D. Gable, Carl W. Painter, Scott L. Makedonska, Nataliia Los Alamos Natl Lab Computat Earth Sci EES 16 Los Alamos NM 87544 USA

We introduce the feature rejection algorithm for meshing (FRAM) to generate a high quality conforming Delaunay triangulation of a three-dimensional discrete fracture network (DFN). The geometric features (fractures, fracture intersections, spaces between fracture intersections, etc.) that must be resolved in a stochastically generated DFN typically span a wide range of spatial scales and make the efficient automated generation of high-quality meshes a challenge. To deal with these challenges, many previous approaches often deformed the DFN to align its features with a mesh through various techniques including redefining lines of intersection as stair step functions and distorting the fracture edges. In contrast, FRAM generates networks on which high-quality meshes occur automatically by constraining the generation of the network. The cornerstone of FRAM is prescribing a minimum length scale and then restricting the generation of the network to only create features of that size and larger. The process is fully automated, meaning no adjustments of the mesh are performed, and the meshing of the individual fractures has been parallelized. Reported mesh statistics show that the computational meshes generated using FRAM are of high quality. Furthermore, the method does not require solving additional systems of linear equations which is needed if a nonconforming mesh is used. Details of the FRAM approach are provided, including its mathematical underpinnings and an algorithm for its implementation. We demonstrate the method's applicability by generating a DFN with similar statistics as the fractured granite at the Forsmark site in Sweden containing 6 700 fractures, and also solve the fully saturated Darcy flow equations to show the quality of the flow solutions which result from computation on the mesh.

关键词： Darcy flow Delaunay triangulation discrete fracture network (DFN) fractured media mesh generation numerical algorithm

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A proportional differential control method for a time-delay system using the Taylor expansion approximation

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APPLIED MATHEMATICS AND COMPUTATION 2014年 236卷 391-399页

作者： Xu, Ling Jiangnan Univ Sch Internet Things Engn Wuxi 214122 Peoples R China Wuxi Inst Commerce Sch Internet Things Technol Wuxi 214153 Peoples R China

In this paper, a proportional differential control algorithm is studied. According to the system performance indices, we uses the first-order Taylor expansion to approximate the time-delay, present an algorithm to determine the controller parameters so that the desired dynamic performance can be achieved. The numerical examples are provided to show the advantages of the proposed algorithm for small time-delay. (c) 2014 Elsevier Inc. All rights reserved.

关键词： numerical algorithm Proportional differential controller Taylor approximation Dynamic performance index

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An Adjoint-Based Hybrid Computational Method for Crosswell Seismic Inversion

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COMPUTING IN SCIENCE & ENGINEERING 2014年第6期16卷 60-67页

作者： Cao, Danping Liao, Wenyuan China Univ Petr Sch Geosci Huadong Peoples R China Univ Calgary Calgary AB T2N 1N4 Canada

Here, a cascade-like hybrid tomography technology is proposed to solve the crosswell seismic inversion problem. This new method combines several widely used tomography technologies, implemented in a sequence starting with the Radon-transform-based back-projection method, then the Linear Iterative Reconstruction method, next the nonlinear Gradient-based Eikonal Equation Tomography method, and finally full waveform inversion.

关键词： Radon transforms conjugate gradient methods geophysical techniques geophysics computing nonlinear equations seismology FWI Radon-transform-based back-projection method adjoint-based hybrid computational method cascade-like hybrid tomography technology crosswell seismic inversion problem full-waveform inversion linear iterative reconstruction method nonlinear-gradient-based Eikonal equation tomography method ray tomography methods selective internal radiation therapy velocity model reconstruction waveform tomography Computational modeling Iterative methods Mathematical model numerical models Seismic measurements Subspace constraints Tomography FWI GEET LIR algorithm design back projection inverse problem numerical algorithm ray tomography scientific computing waveform tomography

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Multi-loop PI/PID controllers design for disturbance rejection based on non-parametric effective model and non-convex optimisation

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IET CONTROL THEORY AND APPLICATIONS 2014年第15期8卷 1499-1512页

作者： Jin, Qibing Liu, Qie Beijing Univ Chem Technol Coll Informat Sci & Technol Inst Automat Beijing 100029 Peoples R China

In this study, the authors address the design of the multi-loop controllers for multi-input and multi-output (MIMO) processes for disturbance rejection. Three types of disturbance rejection are analysed, and they demonstrate that those disturbance responses are directly related to the integral terms of the controllers. A concept of non-parametric effective model is introduced here to decompose a MIMO control system into several equivalent single-input and single-output control systems. Based on the effective model in each loop, a non-convex optimisation problem is established to obtain the optimal controller parameters with certain robustness indices. Considering the drawbacks of using random search algorithm, they develop a numerical algorithm to solve this non-convex optimisation problem. Simulation studies demonstrate that the proposed method improves the disturbance rejection compared with other decentralised controllers.

关键词： MIMO systems three-term control PI control control system synthesis concave programming optimal control search problems numerical analysis multiloop PI-PID controllers design disturbance rejection nonparametric effective model multi-input and multi-output processes disturbance responses MIMO control system nonconvex optimisation problem equivalent single-input and single-output control systems optimal controller parameters certain robustness indices random search algorithm numerical algorithm decentralised controllers

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Recursive least squares estimation algorithm applied to a class of linear-in-parameters output error moving average systems

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APPLIED MATHEMATICS LETTERS 2014年 29卷 36-41页

作者： Wang, Cheng Tang, Tao Beijing Jiaotong Univ State Key Lab Rail Traff Control & Safety Beijing 100044 Peoples R China

This letter deals with the identification problem of a class of linear-in-parameters output error moving average systems. The difficulty of identification is that there exist some unknown variables in the information vector. By means of the auxiliary model identification idea, an auxiliary model based recursive least squares algorithm is developed for identifying the parameters of the proposed system. The simulation results confirm the conclusion. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： numerical algorithm Least squares Parameter estimation Recursive identification Linear-in-parameters model Dynamic system

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A conservative algorithm for parabolic problems in domains with moving boundaries

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JOURNAL OF COMPUTATIONAL PHYSICS 2014年 270卷 203-213页

作者： Novak, Igor L. Slepchenko, Boris M. Univ Connecticut Ctr Hlth Dept Cell Biol Richard D Berlin Ctr Cell Anal & Modeling Farmington CT 06030 USA

We describe a novel conservative algorithm for parabolic problems in domains with moving boundaries developed for modeling in cell biology. The spatial discretization is accomplished by applying Voronoi decomposition to a fixed rectangular grid. In the vicinity of the boundary, the procedure generates irregular Voronoi cells that conform to the domain shape and merge seamlessly with regular control volumes in the domain interior. Consequently, our algorithm is free of the CFL stability issue due to moving interfaces and does not involve cell-merging or mass redistribution. Local mass conservation is ensured by finite-volume discretization and natural-neighbor interpolation. numerical experiments with two-dimensional geometries demonstrate exact mass conservation and indicate an order of convergence in space between one and two. The use of standard meshing techniques makes extension of the method to three dimensions conceptually straightforward. Published by Elsevier Inc.

关键词： numerical algorithm Moving boundaries Parabolic equations Exact mass conservation Cell migration

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An inverse problem of Bilayer textile thickness determination in dynamic heat and moisture transfer

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APPLICABLE ANALYSIS 2014年第3期93卷 445-465页

作者： Xu, Dinghua Wen, Lei Xu, Boxi Zhejiang Sci Tech Univ Dept Math Zhejiang 310018 Peoples R China Fudan Univ Coll Math Sci Shanghai 200433 Peoples R China

An inverse problem of bilayer textile thickness determination in dynamic heat and moisture transfer is presented satisfying the heat-moisture comfort level of human body. Heat and mass transfer law in bilayer textiles is displayed by proving the existence and uniqueness of solution to the coupled partial differential equations with initial-boundary value conditions. The finite difference method is employed to derive the numerical solution to partial differential equations. The regularized solution of the inverse problem is reformulated into solving function minimum problem through the Tikhonov regularization method. The golden section method is applied to solve the direct search problem and achieve the optimal solution to the inverse problem. numerical algorithm and its numerical results provide theoretical explanation for textile materials research and development.

关键词： inverse problems of thickness determination numerical algorithm well-posedness partial differential equations of parabolic type bilayer textile materials regularized solution

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