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Impact of the Assimilation Frequency of Radar Data with the ARPS 3DVar and Cloud Analysis System on Forecasts of a Squall Line in Southern China

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Advances in Atmospheric Sciences 2019年第2期36卷 160-172页

作者： Yujie PAN mingjun wang Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters/Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment ChangeNanjing University of Information Science and Technology Key Laboratory of Mesoscale Severe Weather/Ministry of Education and School of Atmospheric Sciences Nanjing University

Assimilation configurations have significant impacts on analysis results and subsequent forecasts. A squall line system that occurred on 23 April 2007 over southern China was used to investigate the impacts of the data assimilation frequency of radar data on analyses and forecasts. A three-dimensional variational system was used to assimilate radial velocity data,and a cloud analysis system was used for reflectivity assimilation with a 2-h assimilation window covering the initial stage of the squall line. Two operators of radar reflectivity for cloud analyses corresponding to single-and double-moment schemes were used. In this study, we examined the sensitivity of assimilation frequency using 10-, 20-, 30-, and 60-min assimilation intervals. The results showed that analysis fields were not consistent with model dynamics and microphysics in general;thus, model states, including dynamic and microphysical variables, required approximately 20 min to reach a new balance after data assimilation in all experiments. Moreover, a 20-min data assimilation interval generally produced better forecasts for both single-and double-moment schemes in terms of equitable threat and bias scores. We conclude that a higher data assimilation frequency can produce a more intense cold pool and rear inflow jets but does not necessarily lead to a better forecast.

关键词： cloud analysis radar data assimilation data assimilation interval

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Secure and reliable computation offloading in blockchain-assisted cyber-physical IoT systems

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Digital Communications and Networks 2022年第5期8卷 625-635页

作者： Dan wang Bin Song Yingjie Liu mingjun wang The State Key Laboratory of Integrated Services Networks Xidian UniversityXi'an710071China

With the development of the Cyber-Physical Internet of Things System(CPIoTS),the number of Cyber-Physical System(CPS)applications accessed in networks has increased ***-sensitive resource orchestration in CPS applications is extraordinarily essential for maintaining the Quality of Experience(QoE)for *** edge-cloud computing performs effectively in achieving latency-aware resource allocation in CPIoTS,existing methods fail to jointly consider the security and reliability requirements,thereby increasing the process latency of tasks and degrading the QoE of *** paper aims to minimize the system latency of edge-cloud computing coupled with CPS while simultaneously considering the security and reliability *** first consider a time-varying channel model as a Finite-State Markov Channel(FSMC)and propose a distributed blockchain-assisted CPIoTS to realize secure consensus and reliable resource orchestration by offloading computation tasks in edge-cloud ***,we propose an efficient resource allocation algorithm,PPO-SRRA,that optimizes computing offloading and multi-dimension resource(e.g.,communication,computation,and consensus resource)allocation by using a policy-based Deep Reinforcement Learning(DRL)*** experimental results show that the proposed resource allocation scheme can reduce the system latency and ensure consensus security.

关键词： Cyber-physical internet of things system Blockchain Reinforcement learning(RL) Edge-cloud computing

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Statistic of a Gaussian beam from an arbitrary rough target in the single passage atmospheric turbulence

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Science China(Physics,Mechanics & Astronomy) 2014年第10期57卷 1854-1859页

作者： XIANG NingJing WU ZhenSen wang mingjun School of Physics and Electronic Engineering Xian Yang Normal College School of Science Xidian University

The extended Huygens-Fresnel principle and Goodman model was utilized for target surface to derive the mutual coherence function(MCF) of a Gaussian beam reflected from an arbitrary rough target in atmospheric turbulence. According to the MCF, expressions of the mean irradiance and average speckle size at the receiver were obtained. The analysis indicated that the mean intensity is closely related to the ratio of root mean square(rms) height to the lateral correlation length. In addition, the speckle size at the receiver is associated with turbulence strength, propagation distance and roughness of the target. The results can be reduced to the result of a Gaussian beam illuminating rough target and scattering from a target in free space.

关键词： atmospheric turbulence arbitrary rough target mutual coherence function speckle

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A numerical study of segmented cooling-stream injection in supersonic film cooling

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Chinese Journal of Aeronautics 2022年第6期35卷 156-171页

作者： Hang NI mingjun wang Peixue JIANG Wei PENG Yinhai ZHU Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyKey Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China School of Nuclear Science and Technology Xi’an Jiaotong UniversityXi’an 710049China Department of Energy and Power Engineering Key Laboratory for Thermal Science and Power Engineering of Ministry of EducationTsinghua UniversityBeijing 100084China Tsinghua University-Zhang Jiagang Joint Institute for Hydrogen Energy and Lithium-Ion Battery Technology Tsinghua UniversityBeijing 100084China

The present study proposes a segmented cooling-stream injection structure based on a certain coolant mass flow rate,and numerically investigates the effect of segmented cooling-stream injection on supersonic film *** results indicate that without shock-wave impingement and with helium as the coolant,segmented cooling-stream injection can reduce the mixing between the mainstream and the cooling stream to produce better cooling performance than single injection,especially at larger coolant Mach ***,with nitrogen as the coolant,the cooling effect of the segmented-injection system is very close to that of the single-injection *** at the impinging region is enhanced significantly when there is an incident shock *** the shock wave impinges between the two coolant inlets,segmented cooling-stream injection improves film cooling effectiveness in the midstream and downstream regions more than single injection because only part of the cooling stream undergoes the enhanced mixing effect of the shock *** advantage of segmented injection is reduced when the impinging region is behind the second coolant *** further downstream the impinging region,the smaller the associated advantage.

关键词： Film cooling Mach number Segmented injection Shock wave Supersonic flow

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CFD simulation of thermal hydraulic characteristics in a typical upper plenum of RPV

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Frontiers in Energy 2021年第4期15卷 930-945页

作者： mingjun wang Lianfa wang Yingjie wang Wenxi TIAN Jian DENG Guanghui SU Suizheng QI State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and TechnologyXi’an Jiaotong UniversityXi’an 710049China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of ChinaChengdu 610213China

A comparative computational fluid dynamics(CFD)study was conducted on the three different types of pressurized water reactor(PWR)upper plenum,named TYPE 1(support columns(SCs)and control rod guide tubes(CRGTs)with two large windows),TYPE 2(SCs and CRGTs without windows),and TYPE 3(two parallel perforated barrel shells and CRGTs).First,three types of upper plenum geometry information were collected,simplified,and adopted into the BORA facility,which is a 1/5 scale system of the four-loop PWR ***,the geometry,including the upper half core,upper plenum region,and hot legs,was built using the Salome *** that,an unsteady calculation to simulate the reactor balance operation at hot full power scenario was ***,the differences of flowrate distribution at the core outlet and temperature distribution and transverse velocity inside the hot legs with different upper plenum internals were *** results suggest that TYPE 1 upper plenum internals cause the largest flowrate difference at the core outlet while TYPE 3 leads to the most even distributed *** distribution and evolution pattern of the tangential velocity inside hot legs is highly dependent on the upper plenum *** counter-rotating swirls exist inside the TYPE 1 hot leg and only one swirl revolving around the hog leg axis exist inside the TYPE 2 hot *** TYPE 3,two swirls like that of TYPE 1 rotating around the hot leg axis significantly increase the temperature homogenization *** research provides meaningful guidelines for the future optimization and design of advanced PWR upper plenum internal structures.

关键词： pressurized water reactor(PWR) upper plenum internal structures temperature distribution computational fluid dynamics(CFD)

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A Prototype Regional GSI-based EnKF-Variational Hybrid Data Assimilation System for the Rapid Refresh Forecasting System：Dual-Resolution Implementation and Testing Results

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Advances in Atmospheric Sciences 2018年第5期35卷 518-530页

作者： Yujie PAN Ming XUE Kefeng ZHU mingjun wang Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters/Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment Change Nanjing University of Information Science and Technology Nanjing 210044 China Key Laboratory of Mesoscale Severe Weather/Ministry of Education and School of Atmospheric Sciences Nanjing University Nanjing 210093 China Center for Analysis and Prediction of Storms University of Oklahoma Norman Oklahoma 73072 USA

A dual-resolution（DR） version of a regional ensemble Kalman filter（EnKF）-3D ensemble variational（3DEnVar） coupled hybrid data assimilation system is implemented as a prototype for the operational Rapid Refresh forecasting system. The DR 3DEnVar system combines a high-resolution（HR） deterministic background forecast with lower-resolution（LR） EnKF ensemble perturbations used for flow-dependent background error covariance to produce a HR analysis. The computational cost is substantially reduced by running the ensemble forecasts and EnKF analyses at LR. The DR 3DEnVar system is tested with 3-h cycles over a 9-day period using a 40/13-km grid spacing combination. The HR forecasts from the DR hybrid analyses are compared with forecasts launched from HR Gridpoint Statistical Interpolation（GSI） 3D variational（3DVar）analyses, and single LR hybrid analyses interpolated to the HR grid. With the DR 3DEnVar system, a 90% weight for the ensemble covariance yields the lowest forecast errors and the DR hybrid system clearly outperforms the HR GSI *** and wind forecasts are also better than those launched from interpolated LR hybrid analyses, but the temperature forecasts are slightly worse. The humidity forecasts are improved most. For precipitation forecasts, the DR 3DEnVar always outperforms HR GSI 3DVar. It also outperforms the LR 3DEnVar, except for the initial forecast period and lower thresholds.

关键词： dual-resolution 3D ensemble variational data assimilation system Rapid Refresh forecasting system

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Controlling Liu Chaotic System with Feedback Method and Its Circuit Realization

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International Journal of Modern Nonlinear Theory and Application 2016年第1期5卷 40-47页

作者： mingjun wang School of Information Engineering Dalian University Dalian China

In the paper, the Liu system with a feedback controller is discussed. The influence of the feedback coefficient of the controlled system is studied through Lyapunov exponents spectrum and bifurcation diagram. Various attractors are demonstrated not only by numerical simulations but also by circuit experiments. Only one feedback channel is used in our study, which is useful in communication. The circuit experiments show that our study has significance in practical applications.

关键词： Liu System Chaotic Circuit Chaotic Control Circuit Realization

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Evaluation of Young's Modulus and Residual Stress of NiFe Film by Microbridge Testing

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Journal of Materials Science & Technology 2006年第3期22卷 345-348页

作者： Zhimin ZHOU Yong ZHOU mingjun wang Chunsheng YANG Ji＇an CHEN Wen DING Xiaoyu GAO Taihua ZHANG Key Laboratory for Thin Film and Microfabrication Technology of Ministry of Education Research Institute of Micro/Nanometer Science and TechnologyShanghai Jiao Tong University Shanghai 200030 China State Key Laboratory of Nonlinear Mechanics （LNM） Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

Microbridge testing was used to measure the Young＇s modulus and residual stress of metallic films. Samples of freestanding NiFe film microbridge were fabricated by microelectromechanical systems. Special ceramic shaft structure was designed to solve the problem of getting the load-deflection curve of NiFe film microbridge by the Nanoindenter XP system with normal Berkovich probe. Theoretical analysis of load-deflection curves of the microbridges was proposed to evaluate the Young＇s modulus and residual stress of the films simultaneously. The calculated results based on experimental measurements show that the average Young＇s modulus and residual stress for the electroplated NiFe films are 203.2 GPa and 333.0 MPa, respectively, while the Young＇s modulus measured by the Nano-hardness method is 209.6：1：11.8 GPa for the thick NiFe film with silicon substrate.

关键词： Mechanical properties Metal thin film Nanoindentation

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Comparison of Combustion Characteristics of Tars Produced with Tobacco Stem Biomass Gasification

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Journal of Renewable Materials 2024年第1期12卷 119-129页

作者： Bo Chen mingjun wang Bo Liu Chunping Lu Guohai Jia Yong Chao Chao Zhong School of Mechanical Engineering Hunan Institute of EngineeringXiangtan411104China School of Automotive Engineering Xiangtan Institute of TechnologyXiangtan411100China School of Electrical and Information Engineering Hunan Institute of EngineeringXiangtan411104China China Metallurgic Jingcheng(Xiangtan)Heavy Industry Equipment Co. Ltd.Xiangtan411100China Hunan Shuanghuan Fiber Molding Machinery Co. Ltd.Xiangtan411100China

In order to study the combustion characteristics of tar in biomass gasifier inner wall and gasification gas,“tobacco stem semi-tar inside furnace”,“tobacco stem tar inside furnace”and“tobacco stem tar out-of-furnace”were subjected to thermogravimetric experiments,and the combustion characteristics and kinetic characteristics were *** result shows that“tobacco stem semi-tar inside furnace”has the highest value and“tobacco stem tar out-of-furnace”is has the lowest value on ignition characteristics,combustion characteristics and combustible stability;“tobacco stem semi-tar inside furnace”has the lowest value and“tobacco stem tar outside furnace”has the highest value on burnout characteristics;“tobacco stem tar outside furnace”has the highest value and“tobacco stem tar inside furnace”has the lowest value on integrated combustion characteristics.

关键词： Tobacco stem tar gasifier combustion characteristics

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Smart Energy Resource Grid in China:What's the Path?

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Electricity 2011年第2期22卷 19-23,40页

作者： wang mingjun China Electric Power Research Institute Li Yuan

Initiated and approved in 2009,the project of Development Pattern and Implementation Design of Smart Energy Resource Grid in China is now accomplished with the research achievement released to the public and highly valued by authorized organizations such as the Global Smart Grid *** this paper,based on the description of the research achievement,the advantages of the smart energy resource grid in China and the consequential changes are analyzed and discussed,involving the industries of electric power,oil and gas,energy storage,water supply,architecture and transportations etc.

关键词： smart grid smart energy resource grid smart meter demand response

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