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Polar Coordinate Lattice Boltzmann Kinetic Modeling of Detonation Phenomena

Communications in Theoretical physics 2014年第11期61卷 737-748页

作者：林传栋许爱国张广财李英俊 State Key Laboratory for GeoM echanics and Deep Underground Engineering China University of Mining and Technology National Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Center for Applied Physics and Technology MOE Key Center for High Energy Density Physics Simulations College of Engineering Peking University State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology State Key Laboratory of Theoretical Physics Institute of Theoretical Physics Chinese Academy of Sciences

A novel polar coordinate lattice Boltzmann kinetic model for detonation phenomena is presented and applied to investigate typical implosion and explosion processes. In this model, the change of discrete distribution function due to local chemical reaction is dynamically coupled into the modified lattice Boltzmann equation which could recover the Navier–Stokes equations, including contribution of chemical reaction, via the Chapman–Enskog *** the numerical investigations, the main focuses are the nonequilibrium behaviors in these processes. The system at the disc center is always in its thermodynamic equilibrium in the highly symmetric case. The internal kinetic energies in different degrees of freedom around the detonation front do not coincide. The dependence of the reaction rate on the pressure, influences of the shock strength and reaction rate on the departure amplitude of the system from its local thermodynamic equilibrium are probed.

关键词： lattice Boltzmann method detonation wave nonequilibrium behavior polar coordinate

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A blur-sure-let algorithm to blind PSF estimation for deconvolution

A blur-sure-let algorithm to blind PSF estimation for deconv...

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IEEE International Conference on Signal Processing, Communications and Computing (ICSPCC)

作者： Feng Xue Jiaqi Liu Chengguo Liu Gang Meng National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

In this paper, we consider blind deconvolution that consists of PSF (point spread function) estimation and non-blind deconvolution. It has been proved that blur-SURE - a modified version of SURE (Stein's unbiased risk estimate) - is a valid criterion for parametric PSF estimation. The key contribution of this work is to propose a fast algorithm for the blur-SURE minimization. Incorporating a linear combination of multiple smoother matrices with different but fixed regularization parameters, the optimal regularized processing is obtained by a closed-form solution. This linear parametrization of the processing greatly accelerates the minimization. The extensive experiments show the significant improvement of computational time. The low computational complexity enables the blur-SURE criterion to be readily applied to more complicated parametric forms of PSF.

关键词： Deconvolution Abstracts Minimization Estimation

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Detecting Changes in Precipitation and Temperature Extremes over China Using a Regional Climate Model with Water Table Dynamics Considered

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Atmospheric and Oceanic science Letters 2014年第2期7卷 103-109页

作者： QIN Pei-Hua XIE Zheng-Hui WANG Ai-Wen The National Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences School of Applied Science Beijing Information and Science Technology University

Simulations were conducted with the regional climate model RegCM incorporating water table dynamics from 1 September 1982 to 28 August 2002 to detect precipitation and temperature extremes. Compared with observed r10(number of days with precipitation ≥ 10 mm d–1), RegCM3_Hydro(the regional climate model with water table dynamics considered) simulated rain belts, including those in southern China and the middle and lower reaches of the Yangtze River, and provided data for arid to semi-arid areas such as the Heihe River Basin in northwestern China. RegCM3_Hydro indicated a significant increasing trend of r95p(days with daily precipitation greater than the 95th percentile of daily amounts) for the Yangtze, Yellow, and Pearl River basins, consistent with r95p observations. The Haihe River Basin was also chosen as a specific case to detect the effect of groundwater on extreme precipitation using peaks over threshold(POT)-based generalized Pareto distribution(GPD) with parameters estimated by the L-moment method. Quantile plots showed that all but a few of the plotted points were distributed near diagonal lines and the modeled data fitted well with the samples. Finally, the effects of water table dynamics on temperature extremes were also evaluated. In the Yellow River Basin and Songhuajiang River Basin, the trends of the number of warm days(TX95n) from RegCM3_Hydro matched observed values more closely when water table dynamics were considered, and clearly increasing numbers of warm days from 1983 to 2001 were detected.

关键词： climatic extreme groundwater runoff river basin regional climate

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A Stability Analysis of Hybrid Schemes to Cure Shock Instability

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Communications in Computational physics 2014年第5期15卷 1320-1342页

作者： Zhijun Shen Wei Yan Guangwei Yuan National Key Laboratory of Science and Technology on Computational Physics Institute of Applied Physics and Computational MathematicsP.O.Box 8009-26Beijing 100088China Center for Applied Physics and Technology HEDPSPeking UniversityBeijing 100871China.

The carbuncle phenomenon has been regarded as a spurious solution produced by most of contact-preserving *** hybrid method of combining high resolution flux with more dissipative solver is an attractive attempt to cure this kind of non-physical *** this paper,a matrix-based stability analysis for 2-D Euler equations is performed to explore the cause of instability of numerical *** combining the Roe with HLL flux in different directions and different flux components,we give an interesting explanation to the linear numerical *** on such analysis,some hybrid schemes are compared to illustrate different mechanisms in controlling shock *** experiments are presented to verify our analysis *** conclusion is that the scheme of restricting directly instability source is more stable than other hybrid schemes.

关键词： Godunov methods numerical shock instability hybrid scheme.

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Carbon Nanostructures: Covalently Connected Carbon Nanostructures for Current Collectors in Both the Cathode and Anode of Li–S Batteries (Adv. Mater. 41/2016)

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Advanced Materials 2016年第41期28卷

作者： Song Jin Sen Xin Linjun Wang Zhenzhen Du Lina Cao Jiafeng Chen Xianghua Kong Ming Gong Junling Lu Yanwu Zhu Hengxing Ji Rodney S. Ruoff Department of Materials Science and Engineering CAS Key Laboratory of Materials for Energy Conversion iChEM (Collaborative Innovation Center of Chemistry for Energy Materials) University of Science and Technology of China Hefei 230026 China School of Chemistry and Chemical Engineering Hefei University of Technology Hefei 230009 China Hefei National Laboratory for Physical Sciences at the Microscale and Center for Micro‐ and Nanoscale Research and Fabrication University of Science and Technology of China Hefei 230026 China Department of Chemical Physics and CAS Key Laboratory of Materials for Energy Conversion University of Science and Technology of China Hefei 230026 China Material Test and Analysis Lab Engineering and Materials Science Experiment Center University of Science and Technology of China Hefei 230026 China Center for Multidimensional Carbon Materials (CMCM) Institute for Basic Science (IBS) Center at the Ulsan National Institute of Science & Technology (UNIST) Campus Department of Chemistry and School of Materials Science UNIST Ulsan 689‐798 South Korea

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Composite data fusion algorithm for miniature vehicles building navigation base in formation flying

Composite data fusion algorithm for miniature vehicles build...

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IEEE Workshop on Signal Processing Systems (SIPS)

作者： Runle Du Jiaqi Liu Zhifeng Li Zhenhong Niu Zhiye Jiang Yadong Yang National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China (100076) China Academy of Launch Vehicle Technology Beijing China (100076)

When multiple miniature vehicles with individual position and inter-vehicle distance measurement ability collaborate in a formation, navigation base can be established by data fusion in a decentralized and standalone scheme. A Composite Data Fusion (CDF) algorithm which combines Least Square Error and Kalman Filtering is proposed in this paper to build navigation base with optimized computing stress. In CDF, Enhanced LSE is incorporated as the preprocessing stage to build a coarse estimation and handle temporary or permanent group number failure. KF stage is then built to further alleviate noises in the pre-processed estimations In CDF, the dynamic model can be much simpler than KF, so the computation load is reduced while the result still has the advantage of high precision. Simulation results show that, when the fault rate of measurement in each vehicle goes 5 thousandth, the result is still acceptable. The computation time of the proposed method is less than three percent of that of KF, while its precision is almost the same to that of KF.

关键词： Vehicles Kalman filters Navigation Mathematical model Equations Data integration

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Development of spectrometer for ultra-high-field human non-proton magnetic resonance imaging system

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Beijing Ligong Daxue Xuebao/Transaction of Beijing Institute of technology 2015年 35卷 39-44页

作者： Zhang, Zhi He, Yu-Gui Wang, Chao Yang, Chun-Sheng Wang, Dong Wang, Lei Chen, Fang Liu, Chao-Yang State Key Laboratory of Magnet Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences WuhanHubei430071 China University of Chinese Academy of Sciences Beijing100048 China Wuhan National Laboratory for Optoelectronics School of Optoelectronic Science and Engineering Huazhong University of Science and Technology WuhanHubei430074 China

A digital multi-channel MRI spectrometer based on USB 3.0 bus structure was presented to improve data transmission efficiency and communication reliability. This system is also suitable for multi-channel extension. High-speed external memory chips were used to store pulse sequence binary (PSB) elements and acquisition data. In this way, the execution speed of pulse sequence and transmission efficiency of acquisition data can be greatly improved, thereby implementing the ultra-fast MRI sequences. A preliminary test has been accomplished on a Bruker 4.7 T MRI system, and high quality 1H spin-echo MRI images for a phantom and 23Na MRI images for NaCl solution with different concentrations have been obtained successfully. Results suggest that the design of the control system is feasible and reliable. ©, 2015, Beijing Institute of technology. All right reserved.

关键词： Magnetic resonance imaging

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Fast data fusion algorithm for building navigation base in formation flying

Fast data fusion algorithm for building navigation base in f...

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19th International Conference on Automation and Computing, ICAC 2013

作者： Du, Runle Liu, Jiaqi Jiang, Zhiye Liu, Guojuan National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing 100076 China

ISBN: (纸本)9781908549082

When multiple miniature vehicles with inter-vehicle distance measurement ability collaborate in a formation, navigation base can be established without external assisting systems. Shared navigation data is fused to compensate the drift of navigation system and the noise from distance measurement. Existing algorithms like Least Squared Error (LSE) can process nonlinear measurements at high speed, but the noise level of result is high. Kalman Filtering can achieve lower noise level, but it needs huge amount of calculation. The amount of calculation rendered it unsuitable for onboard computing systems. To reduce the computation load of the data fusion algorithm and maintain high precision, Fast Data Fusion (FDF) algorithm which combines LSE and KF is proposed. In this algorithm, LSE is used as the preprocessing stage to build a coarse estimation and KF is then used to further alleviate noises in the pre-processed estimations. In FDF, the dynamic model can be much simpler than KF, so the computation load is reduced while the result still has the advantage of high precision. Simulation results show that, proposed method uses no more than 2.5% of computation time of Kalman Filtering and achieved matching precision. © 2013 Chinese Automation and Computing Society in the UK - CACS.

关键词： Navigation systems

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Laser-sub-cycle two-dimensional electron-momentum mapping using orthogonal two-color fields

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Physical Review A 2014年第6期90卷 061401(R)-061401(R)页

作者： Li Zhang Xinhua Xie Stefan Roither Daniil Kartashov YanLan Wang ChuanLiang Wang Markus Schöffler Dror Shafir Paul B. Corkum Andrius Baltuška Igor Ivanov Anatoli Kheifets XiaoJun Liu André Staudte Markus Kitzler Photonics Institute Vienna University of Technology 1040 Vienna Austria State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071 China Joint Laboratory for Attosecond Science of the National Research Council and the University of Ottawa 100 Sussex Drive Ottawa Ontario Canada K1A 0R6 Department of Physics of Complex Systems Weizmann Institute of Science Rehovot 76100 Israel Research School of Physical Sciences The Australian University Canberra ACT 0200 Australia

We study laser-sub-cycle control over electron trajectories concomitantly in space and time using orthogonally polarized two-color laser fields. We compare experimental photoelectron spectra of neon recorded by coincidence momentum imaging with photoelectron spectra obtained by semiclassical and numerical solutions of the time-dependent Schrödinger equation. We find that a resolution of a quarter optical cycle in the photoelectron trajectories can be achieved. It is shown that depending on their sub-cycle birth time the trajectories of photoelectrons are affected differently by the ion's Coulomb field.

关键词： ELECTRON optics PARTICLE tracks (Nuclear physics) TIME-dependent Schrodinger equations PHOTOELECTRON spectroscopy COULOMB potential GAUSSIAN distribution

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Ground-state cooling of a trapped ion by quantum interference pathways

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Physical Review A 2014年第4期90卷 043409-043409页

作者： Shuo Zhang Jian-Qi Zhang Qian-Heng Duan Chu Guo Chun-Wang Wu Wei Wu Ping-Xing Chen State Key Laboratory of High Performance Computing National University of Defense Technology Changsha 410073 People's Republic of China College of Science National University of Defense Technology Changsha 410073 People's Republic of China State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences and Wuhan National Laboratory for Optoelectronics Wuhan 430071 People's Republic of China

We investigate the possibility of enhancement of cooling a trapped ion by combining the electromagnetically induced transparency (EIT) effect with the standing-wave coupling. Our study shows that the quantum destructive interference which is caused by the EIT effect and the standing-wave coupling can cancel all the dominant heating effects if appropriate parameters are chosen. The analytical predictions and numerical simulations show that the final temperature can be much lower than the recoil energy. In addition, this fast-cooling scheme is robust against fluctuations of the strength of the laser beams, which makes it more feasible for experimental realization.

关键词： QUANTUM interference ION traps GROUND state energy COOLING LASER beams

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