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Unified gas-kinetic wave-particle methods IV: multi-species gas mixture and plasma transport

Advances in Aerodynamics 2021年第1期3卷 186-216页

作者： Chang Liu Kun Xu Department of Mathematics Hong Kong University of Science and TechnologyHong KongChina Institute of Applied Physics and Computational Mathematics Beijing 100088China Shenzhen Research Institute Hong Kong University of Science and TechnologyShenzhen 518057China.

In this paper,we extend the unified gas-kinetic wave-particle(UGKWP)methods to the multi-species gas mixture and multiscale plasma *** construction of the scheme is based on the direct modeling on the mesh size and time step scales,and the local cell’s Knudsen number determines the flow *** proposed scheme has the multiscale and asymptotic complexity diminishing *** multiscale property means that according to the cell’s Knudsen number the scheme can capture the non-equilibrium flow physics when the cell size is on the kinetic mean free path scale,and preserve the asymptotic Euler,Navier-Stokes,and magnetohydrodynamics(MHD)when the cell size is on the hydrodynamic scale and is much larger than the particle mean free *** asymptotic complexity diminishing property means that the total degrees of freedom of the scheme reduce automatically with the decreasing of the cell’s Knudsen *** the continuum regime,the scheme automatically degenerates from a kinetic solver to a hydrodynamic *** the UGKWP,the evolution of microscopic velocity distribution is coupled with the evolution of macroscopic variables,and the particle evolution as well as the macroscopic fluxes is modeled from a time accumulating solution of kinetic scale particle transport and collision up to a time step *** plasma transport,the current scheme provides a smooth transition from particle-in-cell(PIC)method in the rarefied regime to the magnetohydrodynamic solver in the continuum *** the continuum limit,the cell size and time step of the UGKWP method are not restricted by the particle mean free path and mean collision *** the highly magnetized regime,the cell size and time step are not restricted by the Debye length and plasma cyclotron *** multiscale and asymptotic complexity diminishing properties of the scheme are verified by numerical tests in multiple flow regimes.

关键词： Unified gas-kinetic wave-particle method Multiscale modeling gas mixture Plasma transport

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A new method to measure the concentration of argon-xenon gas mixture

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Radiation Detection Technology and Methods 2021年第2期5卷 280-283页

作者： Jiajun Li Mengyun Guan Youyu Gan Peng Zhang Institute of High Energy Physics Beijing 100049China University of Chinese Academy of Sciences Beijing 100049China North China Electric Power University Beijing 100096China

Rgas are widely used in molec Background Rgas are widely used in molecular component examination,impurity analysis,leak detection and test of vacuum system ***,Rgas have different sensitivities to different gases,and the sensitivities can change quickly and depend on so many parameters,which make its ability severely *** In thiswork we established a newpractical method to precisely measure noble gas ratio of argon-xenon *** argon and xenon were controlled,respectively,by two mass flow controller(MFC).A variable leak valve(VLV)was used to introduce the gas mixture sample into the RGA measurement *** mixtures with xenon concentration from 200ppm to 20000ppm(by mass)were introduced and tested by *** The time stability of RGA-measurement system was optimized to 2.1%.A good linearity of MFC-RGA response was achieved,verifying the reliability of RGA in measuring noble gas mixture with component concentration down to several hundred ppm *** Since the approach we used in our experiment is gas-species independent,we believe that it can be popularized to other gas species when properly applied.

关键词： Residual gas analyzers gas mixture Variable leak valve Noble gas

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Employing Per-Component Time Step in DSMC Simulations of Disparate Mass and Cross-Section gas mixtures

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Communications in Computational Physics 2013年第8期14卷 703-721页

作者： Roman V.Maltsev 8-22 KoltsovoNovosibirsk630559Russia

A new approach to simulation of stationary flows by Direct Simulation Monte Carlo method is *** idea is to specify an individual time step for each component of a gas *** approach consists of modifications mainly to collision phase simulation and recommendations on choosing time step *** allows lowering the demands on the computational resources for cases of disparate collision diameters of molecules and/or disparate molecular *** are cases important e.g.,in vacuum deposition *** tests of the new approach are ***,the usage of new approach is demonstrated on a problem of silver nanocluster diffusion in argon carrier gas under conditions of silver deposition experiments.

关键词： Direct Simulation Monte Carlo time step disparate masses gas mixture nanoclusters

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Effects of Xe gas Content and Total gas Pressure on the Discharge Characteristics of Colour Plasma Display Panels

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Plasma Science and Technology 2006年第4期8卷 447-450页

作者：胡文波韩梦驹梁志虎 Key Laboratory for Physical Electronics and Devices of the Ministry of Education Xi'an Jiaotong UniversityXi'an 710049China

The effects of the Xe gas content and total gas pressure on the discharge characteristics of colour plasma display panels including the sustaining voltage margin, white-field chromaticity, discharge time lag （DTL）, discharge current peak, and full-width-at-half-maximum （FWHM） of the discharge current pulse, are experimentally studied. The results indicate that as the Xe gas content in the He-Ne-Xe gas mixture or total pressure increases, the sustaining voltage margin increases, the white-field chromaticity improves, and the discharge current peak has a maximum value, while DTL and FWHM have a minimum value. The mean electron energy in the gas mixture discharge is also calculated through a numerical solution of Boltzmann equation. The experimental results are explained from a view of the mean electron energy variations with the Xe gas content and total gas pressure.

关键词： plasma display panel gas mixture discharge characteristic sustaining voltage margin discharge time lag

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Effect of shielding gas on microstructure and properties of GTAW joints of 2205 duplex stainless steel

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China Welding 2012年第1期21卷 70-75页

作者：王少刚韩志诚李燕 College of Material Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing210016

2205 duplex stainless steels （ DSSs） are welded in gas tungsten arc welding （GTAW） with the addition of N2 to argon, and the desirable microstructure and properties of the joints are obtained by altering the nitrogen percentage in the shielding gas mixture. The mechanical properties of joints are tested with tensile and microhardness machine, and the joint micrustructure is analyzed with scanning electron microscope （SEM） and optical microscope （ OM ） , and detrimental phase precipitate is investigated with X-ray diffraction （XRD）, respectively. Finally, the corrosion behaviour of joint is also evaluated. Results show that the favorable joint strength and corrosion resistance can be obtained with appropriate shielding gas mixture in GTA W. No detrimental phase precipitates in the weldment, and the joint tensile fracture obviously presents the characteristic of ductile fracture.

关键词： duplex stainless steel gas tungsten arc welding gas mixture microstructure properties

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Current status and technical challenges of C_(2)storage in coal seams and enhanced coalbed methane recovery:an overview

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International Journal of Coal Science & Technology 2014年第1期1卷 93-102页

作者： Xiaochun Li Zhi-ming Fang State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China

In the past two decades,research on C_(2)storage in coal seams and simultaneously enhanced coalbed methane recovery(ECBM)has attracted a lot of attention due to its win–win effect between greenhouse gas(C_(2))emission reduction and coalbed methane recovery *** paper presents an overview on the current status of research on C_(2)-ECBM in the past two decades,which involves C_(2)storage capacity evaluations,laboratory investigations,modelings and pilot *** current status shows that we have made great progress in the ECBM technology study,especially in the understanding of the ECBM ***,there still have many technical challenges,such as the definition of unmineable coal seams for C_(2)storage capacity evaluation and storage site characterization,methods for C_(2)injectivity enhancement,*** low injectivity of coal seams and injectivity loss with C_(2)injection are the major technique challenges of *** also search several ways to promote the advancement of ECBM technology in the present stage,such as integrating ECBM with hydraulic fracturing,using a gas mixture instead of pure C_(2)for injection into coal seams and the application of ECBM to underground coal mines.

关键词： C_(2)storage in coal seams ECBM Permeability Hydraulic fracture gas mixture

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Application of Bare Bones Sine Cosine Algorithm in Infrared Spectrum Analysis

Application of Bare Bones Sine Cosine Algorithm in Infrared ...

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第40届中国控制会议

作者： Li Yujun Du Jinghang Jiao Shangbin Cheng Xiaoli Zhang Qing Wang Qing School of Automation and Information Engineering Xi'an University of Technology School of Computer Science and Technology Xidian University

According to the difficulty of modeling parameters selection and the problem of the dimension of infrared spectral data is too large,in order to improve the accuracy of quantitative analysis of gas mixture based on infrared spectrum,least square support vector machine（LS-SVM） optimized by bare bones sine cosine algorithm（BBSCA） is proposed to build the regression *** are 470 sets infrared spectrum sample data of the gas mixture are used to build the regression model,which the gas mixture contains methane,ethane,and propane,the concentration of each component gas range from 0.01% to 0.15%,0.01% to0.15% and 0.01% to 0.1%.Firstly,in order to decrease to the dimension of the infrared spectrum data,principle component analysis（PCA） is adopted to extract eigenvalue,dimension of the model input variable is deduced form 1866 to *** the penalty parameter c,the kernel parameter σ of the LS-SVM and the model input variable dimension pc were optimized by ***,BBSCA is compared with standard sine cosine algorithm（SCA）,particle swarm optimization（PSO） algorithm,bare bones particle swarm optimization（BBPSO） *** experiments result show that the mean relative error（MRE） of the three component gas analysis models built by BBSCA are minimum,the MRE are reduced about 12% to 19%,and the modeling time is *** has great advantages in global optimization and convergence ***,BBSCA has certain practical significance and application value in the field of infrared spectrum analysis.

关键词： Quantitative analysis gas mixture Infrared spectrum Bare bones sine cosine algorithm Least square support vector machine

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gas Quantitative Analysis with Support Vector Machine

Gas Quantitative Analysis with Support Vector Machine

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2009中国控制与决策会议

作者： Liang Xie,Xiaodong Wang~* Department of Electronic Engineering,Zhejiang Normal University,Jinhua 321004,China

＜正＞gas sensor array is an important part of electronic *** gas analysis performance of electronic nose is affected badly by the cross sensitivity of gas sensor *** order to solve the problem of the cross sensitivity,in this work a new method based on support vector machine（SVM） is used for pattern analysis of gas mixture quantitative *** proposed method has been used for processing the measuring data obtained by a gas mixture experiment of butane and ethanol,in which the sensor array is composed of three *** results clearly show that the SVM is effective technique for gas mixture quantitative ***,the SVM can achieve better prediction accuracy than BP neural network.

关键词： Quantitative Analysis gas mixture Support Vector Machine Electronic Nose

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用双天平称重法实现高精度低浓度混和气的制备

用双天平称重法实现高精度低浓度混和气的制备

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中国质谱学会第七届会员代表大会暨学术报告会

作者：韦冠一 Adolf.Gtz 张子斌李雪松 H.Gerken 西北核技术研究所德国IPI公司 Otto-lilienthal-str.19.28199 BremenGermany

2003年,西北核技术研究所与德国IPI公司签订合同,共同开发一台气体四极质谱计,合同中含有高精度的校准混和气的供货,校准气中含～1%Ar,～0.5%Ne,～0.1%Kr,～0.1%Xe,其余为高纯N,其浓度准确度要求在0.1%左右。

关键词： double balance weighing method gas mixture preparing high accuracy low concentration

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