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25 May 2015, Volume 32 Issue 3 Previous Issue    Next Issue

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A Primal Equation Free Projective Integration Scheme in Multi-Scale Plasma Dynamics LI Baiwen, SEIJI Ishiguro, M. M. Skoric 2015, 32(3): 253-263.  Abstract ( )   PDF (3447KB) ( )   A coarse projective method for simulation of multi-dimensional macroscopic systems,Primal Equation Free Projective Integration(p-EFPI)method,was developed and applied to simulation of plasma ion acoustic wave.The method consists of two parts: Time stepper and time projection.For election velocities, probability distribution function or cumulative distrihution function are recorded in time to project,while,corresponding electron positions are reloaded(restricted)via electron charge density.Ion motion is assumed inherently coarse-grained as compared to electron dynamics,to describe possibly macro scale plasma evolution sufficiehtly well. To preserve full ion kinetic effects,individual ion orbits are tracked in time and simply extrapolate to pmject.This is one attempt to test method in p-EFPI framework on plasma physics phenomenon.Our calculations for ion acoustic wave paradigm indicate that P-EFPI simulation follows PIC results nice before ion trapping in phase space appears.However,as ion trapping takes place,main characteristic still keeps,except for ion trapping characteristic.

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Uncertainty Quantification of Temperature-and-Density Dependent Atomic Structures in Radiative Opacity Calculation MENG Xujun, MA Zhibo, WANG Ruili, ZHU Xirui 2015, 32(3): 264-276.  Abstract ( )   PDF (1645KB) ( )   Main cause for uncertainty of atomic structure theory is indicated. A method for uncertainty of temperature-and-density-dependent atomic models in radiative opacity calculation is described via various functional exchange potentials. Uncertainty quantification(UQ) calculation of atomic structures in density-functional at arbitrary temperature and density is carried out by definition of algorithms of modulus. Several procedures indispensable for uncertainty study, and formulae about UQ of electron energy levels and of matrix elements are given. A criterion is proposed to estimate atomic models quantificationally. Feasibility of UQ method is verified by of data of mercury, gold and iron compared with data from‘quasi true’atomic model.

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Adaptive Mesh Refinement Kinetic Scheme for Equations of Radiation Hydrodynamics SUN Wenjun, FAN Zhengfeng 2015, 32(3): 277-292.  Abstract ( )   PDF (2617KB) ( )   By using kinetic BGK scheme with new Maxiwellian distribution function and block-structured adaptive mesh refinement (AMR) algorithm, we construct a second-order BGK-AMR scheme for radiation hydrodynamics equation (RHE) in zero diffusion limit. Merits of the scheme are that we can reduce computational meshes and put more refinement meshes on location where should be concerned mostly, at the same time computational time is reduced greatly comparing with uniform finer meshes. And comparing with old Maxiwellian distribution for kinetic scheme of radiation hydrodynamics, parameters in new Maxwellian function are deeoupled, so construction of the scheme is simplified greatly. One- and two-dimensional numerical examples demonstrate performance of the scheme.

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Probability Weighted Conjugate Gradient Algorithm for Concrete Ultrasonic Tomography Imaging LIU Jianjun, XU Lingzhou 2015, 32(3): 293-298.  Abstract ( )   PDF (1707KB) ( )   In order to improve efficiency and resolution of inversion and computation in concrete tomography, we propose a probability weighted conjugate gradient algorithm, in which weight is added on imaging unit instead of equation. IART algorithm is adopt to determine weight factor and initial value. Simulation examples and a real physical experiment show that the algorithm is of fast convergence, feasibility and validity.

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GPU-accelerated Boundary Element Method for Large-scale Problems in Acoustics ZHANG Rui, WEN Lihua, XIAO Jinyou 2015, 32(3): 299-309.  Abstract ( )   PDF (2442KB) ( )   A boundary element method (BEM) for large-scale acoustic analysis is accelerated efficiently and precisely with Graphics Processing Units (GPUs). Based on Burton-Miller boundary integral equation, an implementation scheme that can be handled efficiently in GPU is derived and applied to accelerate conventional BEM. Data caching techniques in GPU are introduced to improve efficiency of the prototype algorithm. A double-single precision algorithm implemented with single-precision floating-point numbers is employed to reduce numerical errors. It shows that the improved algorithm sustained a highest GPU efficiency of 89.8% for large-scale problems, and its accuracy was almost the same as that with double-precision numerals directly while costing only 1/28 in time and half in GPU memory consumption of the latter. The largest problem size up to 3 million unknowns was solved rapidly on a desktop PC (8GB RAM, NVIDIA GeForce 660 Ti) by the method. Its performance was better than the fast BEM algorithms in both time and memory consumption.

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Propagation Analysis of Two-dimensional Linear Elastic Crack with Boundary Element Method GE Renyu, NIU Zhongrong, CHENG Changzheng, HU Zongjun, XUE Weiwei 2015, 32(3): 310-320.  Abstract ( )   PDF (3357KB) ( )   Boundary element method (BEM) is used to study propagation of crack under loading. First, all leading unknown coefficients in Williams series expansion and complete stress field for notched structures are calculated with BEM and former eigenanalysis for notch tip region. Then, with consideration of non-singular stress term and maximum circumferential stress criterion of brittle fracture, crack initiation extended direction from crack tip in a semicircular bending specimen is determined by BEM. Strategy for BEM tracking crack propagation is given. Numerical examples show that the method is correct and effective in simulating propagation of plane crack.

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Some Inverse Mixed Problems of Discrete System of a Rod WANG Qishen, LIU Minghui, ZHANG Lihua 2015, 32(3): 321-326.  Abstract ( )   PDF (261KB) ( )   Inverse mixed problems of a discrete system for a rod are studied, i.e., stiffness and mass matrices of discrete system of a rod are reconstructed from some frequency data and part of mode data. Three inverse mixed problems are formulated. Solving methods for these problems are given. And conditions of existing solutions for these inverse problems are discussed. Numerical examples are also shown. Potential worth for this type of inverse problems is analysed.

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A Critical Production Rate Model for Deep High Temperature High Pressure Gas Wells AI Shuang, CHENG Linsong, LIU Hongjun, ZHANG Jin, WANG Tao, ZHANG Jian 2015, 32(3): 327-333.  Abstract ( )   PDF (1722KB) ( )   Based on two annular pressure buildup mechanisms, coupling of wellbore heat transfer and formation heat transfer and coupling of gas temperature and gas pressure, we build a calculation model for critical rate in deep high temperature high pressure( HT/HP) gas wells. It takes account of influence of gas well profile, string assembly and fluid properties. The model is solved with programm based on iterative method. Finally, it is applied to a deep HT/HP gas well in Tarim oilfield. Critical rate under several operational modes are calculated and they provide basis for optimum allocation in deep HT/HP gas wells.

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A Model for Stress Sensitivity Measured by Liquid in Tight Oil Reservoirs TIAN Xiaofeng, CHENG Linsong, LI Chunlan, LI Caiyun, ZHANG Miaoyi, JIANG Liwei, HOU Tao, LI Qiu, WANG Hanlin 2015, 32(3): 334-342.  Abstract ( )   PDF (3701KB) ( )   A model to calculate stress sensitivity is established based on theory of accumulation of geology, geomechanics and theory of flow through porous media. Compared with experimental results, the model is accurate and reliable. Distribution range of tight oil reservoir in Daqing Field is narrower than that of Changqing Field. It results in that stress sensitivity of Daqing Field is severer than that of Chaingqing Field. And productivity of Daqing Field is lower than that of Changqing Field. We make a quantitative description on mechanism of stress sensitivity in tight oil reservoirs.

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Numerical Reservoir Simulation Constrained to Fine Separated Layer Water Injection GAO Dapeng, YE Jigen, HU Yongle, WANG Daigang, CHEN Yihe, GAO Yuying 2015, 32(3): 343-351.  Abstract ( )   PDF (1850KB) ( )   Wellbore constrained equations were deduced considering separated layer water injection in a heavy oil model. A numerical model constrained by fine separated layer water injection was constructed. A linear system consisted of a seven-diagonal sparse coefficient matrix with attached columns and rows was derived, which was solved by partitioned matrix multiplication combined with preliminary treatment of conjugate gradient. Development effects of separated layer water injection and generalized water injection were compared and influences of segmentation and injection allocation models were assessed.

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Hopf Bifurcation in a Fluid-Flow Model of Congestion Control in Wireless Networks with State Feedback Control ZHOU Yunlong, XU Chao 2015, 32(3): 352-360.  Abstract ( )   PDF (1347KB) ( )   Controlling Hopf bifurcation in a fluid-flow model for congestion control in wireless networks, we propose a state feedback controller. Choosing communication delay as a bifurcation parameter, we proved that with the controller, one can change critical value of bifurcation and enlarge stable region. Hopf bifurcation of the system is delayed. Moreover, by choosing appropriate parameters, we change easily stability and direction of bifurcating periodic solutions. Theoretical analysis and numerical results verifies that the method controls Hopf bifurcation effectively.

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Electron Resonance States in Liberman's Statistical Self-consistent Field INFERNO Model MA Guicun, QI Jin, WANG Min 2015, 32(3): 361-368.  Abstract ( )   PDF (2289KB) ( )   Electron resonant characteristics in Liberman's statistical self-consistent INFERNO model are fully studied. Electron resonant states of uranium are calculated at two temperatures and densities. Electron density of states, wave function and scattering phase shift are given in energy interval containing resonance. Phase of wave function in amplitude-phase form changing with energy is also given. Resonant characteristics are the same as in non-relativistic case.

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An Approach for Defect Mode of 1D Doped Photonic Crystal LIU Qineng, LONG Tao, DAI Hongxia 2015, 32(3): 369-373.  Abstract ( )   PDF (1189KB) ( )   For defect mode of 1D doped photonic crystal, a resonant cavity model of 1D doped photonic crystal is established. With coherent superposition principle, transmittance formula and frequency formula of defect mode are derived in I D doped photonic crystal. Coherent superposition theory has advantages of characteristic matrix theory and resonance theory, while it does not have disadvantages of them. Coherent superposition theory is a good approach to study defect mode of 1D doped photonic crystal.

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Ground States of Dimerized Spin-1 lsing Chain with Both Longitudinal and Transverse Single-Ion Anisotropies WU Haina, GONG Weijiang, YI Guangyu, WEI Guozhu 2015, 32(3): 374-378.  Abstract ( )   PDF (1190KB) ( )   We study dimerized spin-1 Ising chain with both longitudinal and transverse single-ion anisotropies by means of Jordan-Wigner transformation. The system has a hidden conserved quantity with which it can be exactly mapped onto spin-1/2 transverse Ising model. We obtained analytical expressions of quasi-particles' spectra, minimal energy gap for exciting a fermion quasi-particle, minimal energy gap for exciting a hole, transverse magnetism, static transverse susceptibility, the nearest neighboring longitude spin-spin-correlation function and ground state phase diagram. It shows that ground states of system are strongly dependent on system parameters. As system parameters periodly change, a series of quantum phase transition appear.