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A Stability Analysis of Hybrid Schemes to Cure Shock Instability

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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Learning to Infer Weather States Using Partial Observations

Journal of Geophysical Research: Machine Learning and Comput...

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Journal of Geophysical Research: Machine Learning and Computation 2025年第1期2卷

作者： Jie Chao Baoxiang Pan Quanliang Chen Shangshang Yang Jingnan Wang Congyi Nai Yue Zheng Xichen Li Huiling Yuan Xi Chen Bo Lu Ziniu Xiao National Key Laboratory of Earth System Numerical Modeling and Application Institute of Atmospheric Physics Chinese Academy of Science Beijing China School of Atmospheric Sciences Chengdu University of Information Technology Chengdu China Key Laboratory of Mesoscale Severe Weather Ministry of Education and School of Atmospheric Sciences Nanjing University Nanjing China College of Computer National University of Defense Technology Hunan China Clustertech LTD Hong Kong China National Climate Center China Meteorological Administration Beijing China

Accurate state estimation of the high-dimensional, chaotic Earth's atmosphere marks a Sisyphean task, yet is indispensable for initiating weather forecasts and gauging climate variability. While much effort is devoted to assimilating observations and forecasts to infer weather states, the inherent low-dimensional statistical structure in atmospheric circulation, shaped by geophysical laws and geographic boundaries, is underutilized as an informative prior for state inference, or as reference for assessing representative of existing observations and planning new ones. We realize these potential by learning climatological distribution from climate reanalysis/simulation, using a deep generative model. For a case study of estimating 2 m temperature spatial patterns, the learned distribution faithfully reproduces climatology statistics. A combination of the learned climatological prior with few station observations yields strong posterior of spatial pattern estimates, which are spatially coherent, faithful and adaptive to observational constraints, and uncertainty-aware. This allows us to evaluate each observation's value in reducing pattern estimation uncertainty, and guide optimal observation network design by pinpointing the most informative sites. Our study showcases how generative models can extract and utilize information produced in the chaotic evolution of climate system. Deep generative model enables accurate spatial interpolation of weather variables from sparse observations The generative model produces spatially coherent and uncertainty-aware estimates, effectively constrained by observational data The approach provides a framework to quantify observation impact on uncertainty reduction, enabling optimization of observation networks Accurate estimation of weather conditions across a large area is crucial but challenging due to the complex and chaotic nature of the atmosphere. Traditional methods rely on combining observations with forecasts, which can be comp

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Stability analysis of discrete Boltzmann simulation for supersonic flows: Influencing factors, coupling mechanisms and optimization strategies

arXiv

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arXiv 2025年

作者： Wu, Yanhong Gan, Yanbiao Xu, Aiguo Yang, Bin Hebei Key Laboratory of Trans-Media Aerial Underwater Vehicle North China Institute of Aerospace Engineering Langfang065000 China National Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics P. O. Box 8009-26 Beijing100088 China National Key Laboratory of Shock Wave and Detonation Physics Mianyang621999 China HEDPS Center for Applied Physics and Technology College of Engineering Peking University Beijing100871 China State Key Laboratory of Explosion Science and Safety Protection Beijing Institute of Technology Beijing100081 China School of Energy and Safety Engineering Tianjin Chengjian University Tianjin300384 China

Supersonic flow simulations encounter challenges in threefold: trans-scale modeling, numerical stability and complex field analysis, due to their inherent nonlinear, nonequilibrium and multiscale characteristics. The discrete Boltzmann method (DBM) provides a multiscale kinetic modeling framework and a set of analysis tools to capture complex discrete/nonequilibrium states and effects. While the stable numerical scheme plays a fundamental role in DBM simulations, a comprehensive and systematic stability analysis remains lacking. Similar to the lattice Boltzmann method, the complexity lies mainly in the intrinsic coupling between velocity and spatiotemporal discretizations, compared with the traditional computational fluid dynamics. Based on the von Neumann stability analysis, we investigate influences of the following aspects: (i) approaches for determining equilibrium distribution functions and designing discrete velocities, (ii) thermodynamic nonequilibrium (TNE) levels, (iii) spatiotemporal discretization schemes, (iv) initial conditions, and (v) model parameters, on the stability of DBM simulation. key findings include: (i) Among the equilibrium distribution discretization methods considered, the moment-matching approach outperforms expansion- and weighting-coefficient-based methods in the test simulations. (ii) As TNE intensity/Knudsen number increases, the nonlinear behavior of the system is enhanced. Accordingly, the intrinsic nonlinearity embedded in the matching model equation increases, regardless of whether the model is kinetic or macroscopic. In numerical simulations, instabilities induced by fast-changing behaviors, such as shock waves, are often amplified by nonlinear terms in the model equation. Therefore, the higher the nonlinear order of the model, the weaker its capability to handle such rapidly varying modes, and the more demanding the requirements on the numerical scheme. This reflects a common phenomenon. (iii) Although additional viscous dissip

关键词： Supersonic flow

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numerical Simulations on Buckling Failure of Preloaded Cylindrical Shell Irradiated by High Power Laser Beam

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Journal of Beijing Institute of technology 2004年第3期13卷 236-241页

作者：王吉王肖钧王峰赵凯 Department of Mechanics and Mechanical Engineering University of Science and Technology of China Hefei Anhui230027 China .National Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing100088 China

With finite-element software ANSYS 7.0 and simple thermal-mechanical coupling constitutive relations,the buckling failure of preloaded cylindrical shell irradiated by high power laser beam was studied by numerical simulations. The buckling mode and buckling critical loading were analysed for different preloading conditions. The influence of laser intensity, beam irradiation time, preloading conditions and geometric parameters of cylindrical shell on the buckling mode were discussed. The numerical results show that: ① the buckling deformation of the cylindrical shell was concentrated in the area of laser spot and the radial buckling was the main buckling mode, ② a linear relationship between the buckling eigenvalue and the maximum temperature at the center of laser spot was approached, ③ the buckling failure of cylindrical shell was attributed to the coupling effect of the material softening and the radial deformation in the laser spot, and hence to raise the stiffness of the material would enhance the ability for anti-irradiation of structure substantially..

关键词： cylindrical shell buckling laser beam irradiation

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Recent developments on the lagrangian and remapping methods for compressible fluid flows

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International Conference on numerical Methods for Hyperbolic Equations: Theory and Applications

作者： Juan, Cheng Shu, Chi-Wang National Key Laboratory of Science and Technology on Computational Physics Institute of Applied Physics and Computational Mathematics China Division of Applied Mathematics Brown University United States

ISBN: (纸本)9780415621502

The Lagrangian method and the Arbitrary Lagrangian-Eulerian method (ALE) are widely used in many fields, especially for multi-material flow simulations, due to their distinguished advantage in capturing material interfaces automatically. In this paper we give a short survey on our recent research on the Lagrangian scheme and the remapping method, both of which constitute essential and important components of the ALE method. Specifically, we first introduce a class of high order Lagrangian schemes which are based on Essentially Non-Oscillatory (ENO) and Weighted Essentially Non-Oscillatory (WENO) reconstructions. The schemes are constructed both on straight-line quadrilateral meshes and on curvilinear quadrilateral meshes. Meanwhile, two approaches for high order time discretization in the Lagrangian scheme are investigated, namely, the Total Variation Diminishing (TVD) Runge-Kutta time discretization and the Lax-Wendroff (LW) type time discretization. Next, we give a class of cell-centered Lagrangian schemes with the properties of both conservation and spherical-symmetry-preserving in two-dimensional cylindrical coordinates. After that, we summarize a high order conservative ENO remapping algorithm. At last, several numerical examples are shown to further demonstrate the performance of these schemes. © 2013 Taylor & Francis Group, London.

关键词： Lagrange multipliers

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A Direct Position Determination Method for Four-station TDOA Location System

A Direct Position Determination Method for Four-station TDOA...

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Signal, Information and Data Processing (ICSIDP), IEEE International Conference on

作者： Sun-Rui Qi Chen-Shun Yuan Bai-Jin Liang Gao-Lu Li-Hu Sun-Heng BEIJING INSTITUTE OF SPACE LONG MARCH VEHICLE National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

ISBN: (数字)9781728123455

ISBN: (纸本)9781728123462

Aiming at the four-station networked TDOA (Time Difference of Arrival) localization system, a direct location method based on electronic elevation map search is proposed, the Geometric Dilution Precision (GDOP) is derived, and the factors affecting the location accuracy are analyzed. The location method under real conditions is also simulated, and its feasibility is demonstrated, which provides a new engineering method for networked TDOA location.

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Improving the simulation of terrestrial water storage anomalies over China using a Bayesian model averaging ensemble approach

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Atmospheric and Oceanic science Letters 2018年第4期11卷 322-329页

作者： LIU Jian-Guo JIA Bing-Hao XIE Zheng-Hui SHI Chun-Xiang School of Mathematics and Computational Science and Key Laboratory of Intelligent Control Technology for Wuling-Mountain Ecological Agriculture in Hunan Province Huaihua University State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences National Meteorological Information Center China Meteorological Administration

The ability to estimate terrestrial water storage(TWS)is essential for monitoring hydrological extremes(e.g.,droughts and floods)and predicting future changes in the hydrological ***,inadequacies in model physics and parameters,as well as uncertainties in meteorological forcing data,commonly limit the ability of land surface models(LSMs)to accurately simulate *** this study,the authors show how simulations of TWS anomalies(TWSAs)from multiple meteorological forcings and multiple LSMs can be combined in a Bayesian model averaging(BMA)ensemble approach to improve monitoring and *** using three forcing datasets and two LSMs were conducted over China's Mainland for the period 1979–*** the simulations showed good temporal correlations with satellite observations from the Gravity Recovery and Climate Experiment during 2004–*** correlation coefficient ranged between 0.5 and 0.8 in the humid regions(e.g.,the Yangtze river basin,Huaihe basin,and Zhujiang basin),but was much lower in the arid regions(e.g.,the Heihe basin and Tarim river basin).The BMA ensemble approach performed better than all individual member *** captured the spatial distribution and temporal variations of TWSAs over China's Mainland and the eight major river basins very well;plus,it showed the highest R value(>0.5)over most basins and the lowest root-mean-square error value(<40 mm)in all basins of *** good performance of the BMA ensemble approach shows that it is a promising way to reproduce long-term,high-resolution spatial and temporal TWSA data.

关键词： Terrestrial water storage anomalies multi-forcing and multi-model ensemble simulation Bayesian model averaging spatiotemporal variation uncertainty

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An Improved Adaptive Pulse Compression Algorithm Based on Linear Frequency Modulation Signal

An Improved Adaptive Pulse Compression Algorithm Based on Li...

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Signal, Information and Data Processing (ICSIDP), IEEE International Conference on

作者： Jinliang Bai Peng Qin Hu Li Ran Zhang Xinyu Zhang National key laboratory of science and technology on test physics and numerical mathematics Beijing Institute of Space Long March Vehicle Beijing China

ISBN: (数字)9781728123455

ISBN: (纸本)9781728123462

In this paper, the radar signal is optimized based on the pulse compression repair (PCR) algorithm, which mainly reduces the computational amount to makes it more advantageous to achieve. The main idea is to implement PCR in a parallel way. The method of implementing parallelism is well known, that is, the signal is segmented, and different segmentation methods can be adopted according to different signal models. In this paper, the chirp signal is mainly processed by decimation and segmentation, and some intrinsic benefits of the performance and computational balance of the proposed method are discussed.

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A Binary Sparrow-Hybridized Beluga Whale Optimization Algorithm for Jamming Task Assignment 6

A Binary Sparrow-Hybridized Beluga Whale Optimization Algori...

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6th IEEE International Conference on Electronic Information and Communication technology, ICEICT 2023

作者： Shen, Chen Gao, Jingpeng Jiang, Zhiye Zhang, Tianran Chen, Geng College of Information and Communication Engineering Harbin Engineering University Harbin150050 China Beijing Institute of Space Long March Vehicle National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China Beijing Institute of Electronic System Engineering Beijing100854 China

ISBN: (纸本)9798350399059

In the context of non-cooperative electronic countermeasures, the problem of formulating effective jamming task assignments arises due to insufficient collaborative jamming resources. This paper proposes a binary sparrow- hybridized beluga whale optimization algorithm based on jamming task assignments. The algorithm combines the binary sparrow search algorithm(BSSA) and the binary beluga whale optimization(BBWO), which is set with multi-dimensional constraints in the time, frequency and spatial domains. To achieve the optimal strategy for collaborative interference task assignment, a fitness function is constructed using both radar coverage and the signal-to-jamming ratio received by each radar. When the number of UAVs is 7 and the number of radars is 10, the simulation results show that the optimization speed and accuracy of the proposed algorithm are significantly higher than the BSSA and BBWO. Therefore, the algorithm has good coverage and performance in the field of jamming task assignments. © 2023 IEEE.

关键词： Optimization

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Broadband Dual-Polarized Antenna with Enhanced Front-To-Back Ratio Using Meta-surface

Broadband Dual-Polarized Antenna with Enhanced Front-To-Back...

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Asia-Pacific Conference on Microwave

作者： Pei Zheng Yuwei Qiu Jinliang Bai Ziwei Xu Xin Liu Jiaqi Liu Jun Li Shuo Zhang Hailiang Zhu Gao Wei National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China Northwestern Polytechnical University Xi'an Shaanxi China

ISBN: (数字)9781728135175

ISBN: (纸本)9781728135182

A novel broadband dual-polarized dipole antenna with enhanced front-to-back ratio is proposed. By placing metasurface around the radiators, the proposed dipole antenna exhibits wide impedance bandwidth (S11&S22 ≤ -12dB) of 52% from 0.675 to 1.15 GHz, covering the lower frequency band (0.69~0.96GHz) of base station antenna. Simulated results show that the front-to-back ratio can be increased by 4-5dB after adding the meta-surface, radiation pattern with enhanced frontto-back ratio (FBR) higher than 20dB were achieved over the operating frequency range. In addition, the antenna architecture is simple and easy to fabricate in base stations that can be used in modern mobile communication systems.

关键词： Dipole antennas Broadband antennas Antenna radiation patterns Probes Broadband communication Bandwidth

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