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Accelerated procedure to solve kinetic equation for neutral atoms in a hot plasma

International Journal of Modeling, Simulation, and Scientific Computing 2018年第5期9卷 233-246页

作者： mikhail Z.Tokar Institute for Energy and Climate Research—Plasma Physics(IEK-4)Research Center J¨ulich J¨ulich52428Germany

By reaching the first wall of a fusion reactor, charged plasma particles, electrons and ionsare recombined into neutral molecules and atoms of hydrogen isotopes. These speciesrecycle back into the plasma volume and participate, in particular, in charge–exchange(cx) collisions with ions. As a result, hot atoms with chaotically directed velocities aregenerated and some of them hit the wall. Statistical Monte Carlo methods often usedto model the behavior of cx atoms are too time-consuming for comprehensive parameter studies. Recently1 an alternative iteration approach to solve one-dimensional kineticequation2 has been significantly accelerated, by a factor of 30–50, by applying a passmethod to evaluate the arising integrals from functions, involving the ion velocity distribution. Here, this approach is used by solving a two-dimensional kinetic equation,describing the transport of cx atoms in the vicinity of an opening in the wall, e.g.,the entrance of a duct guiding to a diagnostic installation. To assess the erosion rateand lifetime of the installation, one need to know the energy spectrum of hot cx atomsescaping from the plasma into the duct. Calculations are done for a first mirror of molybdenum under plasma conditions expected in a fusion reactor like DEMO.3,4 The resultsof kinetic modeling are compared with those found by using a diffusion approximation5relevant for cx atoms if the time between cx collisions with ions is much smaller thanthe time till the ionization of atoms by electrons. The present more exact kinetic consideration predicts a mirror erosion rate by a factor of 2 larger than the approximatediffusion approach.

关键词： Kinetic equation numerical solution neutrals plasma.

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Satellite mapping of air temperature under polar night conditions

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Geo-Spatial Information Science 2022年第2期25卷 325-336页

作者： Kritsuk Sergei Victor Gornyy Tatiana Davidan Iscander Latypov Alexandra Manvelova Pavel Konstantinov Andrei Tronin mikhail Varentsov mikhail Vasiliev Saint-Petersburg Scientific Research Center for Ecological Safety Russian Academy of SciencesSaint-PetersburgRussia Faculty of Geography/Research Computing Center Lomonosov Moscow State UniversityMoscowRussia

A novel satellite technique for air temperature mapping with a spatial resolution of~100 m was proposed for the town of Apatity,the Kola Peninsula(Russia),taken as a case *** main idea behind this novel technique is to find the statistical relationships between the land surface temperatures in each point of the study area,observed by multiple infrared thermal satellite imagery,and the time series of air temperatures recorded by World Meteorological Organization(WMO)weather *** scenes of infrared thermal spectral band of the Landsat satellites for the period 2014–2019 were used,as well as the long-term time series of air temperature from the weather station and the results of air temperature observations carried out by the network of *** calm weather conditions,according to the ground truth,the error of air temperature mapping wasσ=1.5°C,and the precision was estimated asδ=1.0°*** analysis of the compiled air temperature map showed that,under polar night conditions,the air temperature on the hilltops was by 10–18°C higher than in the *** was concluded that,for economic reasons,as well as for the reasons of population health protection in the Arctic,it would be advisable to plan the placement of new cities on the *** of these new areas should be designed in a“semi-isolated”manner in order to minimize the time needed by the local people for crossing the lowlands between the nearby districts.A characteristic feature of modern megalopolises is their internal structure formed by the growing primary settlements that can be considered as nuclei interlinked by transportation ***,the new Arctic cities can be called“Arctic megalopolises”because of their internal structure that is specific to megalopolises.

关键词： Polar night town of Apatity air temperature satellite images time series regression mapping bioclimatic comfort

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THE EARLY INFLUENCE OF PETER LAX ON COMPUTATIONAL HYDRODYNAMICS AND AN APPLICATION OF LAX-FRIEDRICHS AND LAX-WENDROFF ON TRIANGULAR GRIDS IN LAGRANGIAN COORDINATES

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Acta Mathematica Scientia 2011年第6期31卷 2195-2202页

作者： Richard Liska mikhail Shashkov Burton Wendroff Faculty of Nuclear Sciences and Physical Engineering Czech Technical University in Prague Group XCP-4 MS-F644Los Alamos National Laboratry Group T-5 MS-B284Los Alamos National Laboratry

We give a brief discussion of some of the contributions of Peter Lax to Com- putational Fluid Dynamics. These include the Lax-Friedrichs and Lax-Wendroff numerical schemes. We also mention his collaboration in the 1983 HLL Riemann solver. We de- velop two-dimensional Lax-Friedrichs and Lax-Wendroff schemes for the Lagrangian form of the Euler equations on triangular grids. We apply a composite scheme that uses a Lax- Friedrichs time step as a dissipative filter after several Lax-Wendroff time steps. Numerical results for Noh＇s infinite strength shock problem, the Sedov blast wave problem, and the Saltzman piston problem are presented.

关键词： Lax-Friedrichs Lax-Wendroff conservation laws Lagrangian coordinates,triangular grid

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GNSS-based BiSAR imaging using modified range migration algorithm

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Science China(Information Sciences) 2015年第8期58卷 144-156页

作者： ZENG Tao LIU FeiFeng ANTONIOU Michail CHERNIAKOV mikhail Beijing Key Laboratory of Embedded Real-time Information Processing Technology Beijing Institute of Technology School of Electronic Electrical and Systems Engineering University of Birmingham

This paper proposed a new focusing approach for the bistatic SAR systems with a GNSS(Global Navigation Satellite System) satellite as the transmitter. Because of the long integration time the inherited curvature of the transmitter’s trajectory was adopted and the spatial variance of the equivalent velocity was derived under the principal of equivalent slant range model in the system signal model. The proposed focusing approach consists of two-step processing. Firstly, the general Doppler phase from constant velocity of the echo data is focused by modified Stolt mapping. Secondly, the residual nonlinear Doppler phase due to velocity variation is compensated by means of block-processing-based adaptive phase compensation to achieve large scene focusing. The simulation and experimental results validate the proposed algorithm in GNSS-based Bi SAR systems.

关键词： GNSS-based Bi SAR equivalent slant range model curvature of trajectory two-step processing modified Stolt mapping

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E-beam generation in discharges initiated by voltage pulses with a rise time of 200 ns at an air pressure of 12.5-100 kPa

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Plasma Science and Technology 2019年第4期21卷 52-60页

作者： Victor TARASENKO Dmitry BELOPLOTOV mikhail LOMAEV Dmitry SOROKIN Institute of High Current Electronics Siberian Bran ch.Russian Academy of Sciences.Tomsk&34055.Russia National Research Tomsk State University.Tomsk 634050 Russia

The effect of air pressure(12.5,25,50,and 100 kPa)on the gen eration of runaway electron beams in a non-uniform electric field when applying voltage pulses(~35 kV)with a rise time of?200 ns has been *** results show that the discharge has various stages:streamer,diffuse,and ***,a wide streamer develops in the gap and a diffuse discharge is formed.A spark is formed u 100 ns after the *** current pulse of a supershort avalanche electron beam(SAEB)was measured with a collector at various pressures of *** show that there are two modes of generation of run away *** an air pressure of 25-100 kPa,a single SAEB current pulse with a full width at half-maximum(FWHM)of 120-140 ps is *** the air pressure of 12.5 kPa,two current pulses of the electron beam are *** of the first and second current pulses are ul40ps and u300 ps,*** current pulse amplitude of the second electron beam is higher than that of the first one,but the electron energy is less.

关键词： diffuse discharge runaway electrons streamer breakdown displacement current

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Kinetics of oxidative coupling of methane:Bridging the gap between comprehension and description

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Journal of Natural Gas Chemistry 2009年第3期18卷 273-287页

作者： mikhail Sinev Zukhra Fattakhova Vladimir Lomonosov Yurii Gordienko Semenov Institute of Chemical Physics ZAO "SCHAG" Company

The development of notions about the mechanism of the oxidative coupling of methane （OCM） over oxide catalysts and corresponding progress in its kinetic description are reviewed and discussed. The latter becomes essential at the stage of scaling up and optimization of the process in pilot and industrial reactors. It is demonstrated that the main achievements in the development of kinetic models can be reached by combining the approaches conventionally used in homogeneous gas-phase kinetics and in heterogeneous catalysis. In particular, some important features of the OCM process can be described if several elementary reactions of free radical species （formation and transformation） with surface active sites are included into the detailed scheme of methane oxidation in gas. However, some important features, such as a non-additive character of the reciprocal influence of methane and ethane in the case of their simultaneous presence in the reaction mixture, cannot yet be described and comprehended in the framework of schemes developed so far. Possible ways towards an advanced kinetic model, accounting the main principles of catalyst functioning （redox nature of active sites） and pathways of product formation （via free radicals） are traced.

关键词： natural gas methane oxidative coupling of methane ethane ethylene kinetics mechanism rate equations

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Non-classical solutions of a continuum model for rock descriptions

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Journal of Rock Mechanics and Geotechnical Engineering 2014年第3期6卷 180-185页

作者： mikhail A.Guzev Institute for Applied Mathematics Far Eastern Branch of the Russian Academy of Sciences

The strain-gradient and non-Euclidean continuum theories are employed for construction of non- classical solutions of continuum models. The linear approximation of both models＇ results in identical structures in terms of their kinematic and stress characteristics. The solutions obtained in this study exhibit a critical behaviour with respect to the external loading parameter. The conclusions are obtained based on an investigation of the solution for the scalar curvature in the non-Euclidean continuum theory, The proposed analysis enables us to use different theoretical approaches for description of rock critical behaviour under different loading conditions.

关键词： Zonal disintegrationStrain-gradient theoryNon-Euclidean continuum model

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近代俄国和德国在吐鲁番考古领域的合作与冲突

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西域研究 2024年第1期 58-71,187页

作者：郑丽颖米哈伊尔·德米特里耶维奇·布哈林敦煌研究院敦煌学信息中心兰州大学敦煌学研究所俄罗斯科学院

本文根据俄罗斯科学院档案馆新近公布的俄国考古学家奥登堡、克莱门茨与德国探险家格伦威德尔的书信档案,结合柏林亚洲艺术博物馆史料,详细梳理了俄德新疆考察队的短暂合作、考古范围的划分、冲突原因及结果。本文认为乌鲁木齐领事馆医... 详细信息

本文根据俄罗斯科学院档案馆新近公布的俄国考古学家奥登堡、克莱门茨与德国探险家格伦威德尔的书信档案,结合柏林亚洲艺术博物馆史料,详细梳理了俄德新疆考察队的短暂合作、考古范围的划分、冲突原因及结果。本文认为乌鲁木齐领事馆医生科哈诺夫斯基的吐鲁番考古是双方冲突的导火索,勒柯克考察队进入库车标志俄德冲突的加剧和合作的破灭。

关键词：科哈诺夫斯基奥登堡格伦威德尔勒柯克新疆考古

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Corrosion performance,corrosion fatigue behavior and mechanical integrity of an extruded Mg4Zn0.2Sn alloy

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Journal of Materials Science & Technology 2020年第24期59卷 107-116页

作者： Pingli Jiang Carsten Blawert Jan Bohlen mikhail L.Zheludkevich Magnesium Innovation Centre-MagIC Institute of Materials ResearchHelmholtz-Zentrum GeesthachtMax-Planck Str.1Geesthacht 21502Germany Faculty of Engineering University of KielKaiserstrasse 224143 KielGermany

Magnesium alloys are promising as load bearing *** are inevitably exposed to cyclic loading and corrosive environment in actual service,which can consequently result in corrosion fatigue failure and loss of mechanical integrity of the ***,in the present study,the corrosion behavior,corrosion fatigue performance and mechanical integrity of an extruded Mg4Zn0.2Sn(wt.%)alloy were thoroughly studied in two corrosive *** localized corrosion occurred when the alloy was immersed in deionized water based sodium chloride(NaCl)*** poor corrosion resistance of the alloy resulted in a fast deterioration of the tensile properties after pre-exposure to salt spray and a poor fatigue resistance in deionized water based NaCl *** comparison,the active dissolution of the substrate was sufficiently suppressed in artificial tap water based NaCl solution due to the formation of highly protective corrosion product *** consequently conferred longer fatigue life on the alloy in the *** results emphasized the influence of corrosion on the fatigue behavior and tensile properties of magnesium alloys.

关键词： Magnesium alloy Tin Artificial tap water Corrosion fatigue Mechanical integrity

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The Error-Minimization-Based Strategy for Moving Mesh Methods

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Communications in Computational Physics 2006年第1期1卷 53-80页

作者： Konstantin Lipnikov mikhail Shashkov Los Alamos National Laboratory MS B284Los AlamosNM87545USA

The typical elements in a numerical simulation of fluid flow using moving meshes are a time integration scheme,a rezone method in which a new mesh is defined,and a remapping(conservative interpolation)in which a solution is transferred to the new *** objective of the rezone method is to move the computational mesh to improve the robustness,accuracy and eventually efficiency of the *** this paper,we consider the onedimensional viscous Burgers’equation and describe a new rezone strategy which minimizes the L2 norm of error and maintains mesh *** efficiency of the proposed method is demonstrated with numerical examples.

关键词： Moving meshes Burgers’equation error estimates

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