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Carbon isotopes of graphite:Implications on fluid history

Geoscience frontiers 2012年第2期3卷 197-207页

作者： f.j.Luque E.Crespo-feo j.f.Barrenechea L.Ortega Departamento de Cristalografía y Mineralogía facultad de Geología Universidad Complutense de Madrid 28040 MadridSpain Instituto de Geociencias(UCM-CSIC) Jos Antonio Novais 228040 MadridSpain Departamento de Cristalografia y Mineralogia facultad de Geología Universidad Complutense de Madrid28040 MadridSpain Departamento de Cristalografía y Mineralogía facultad de Geología Universidad Complutense de Madrid28040 MadridSpain

Stable carbon isotope geochemistry provides important information for the recognition of funda- mental isotope exchange processes related to the movement of carbon in the lithosphere and permits the elab- oration of models for the global carbon cycle. Carbon isotope ratios in fluid-deposited graphite are powerful tools for unravelling the ultimate origin of carbon （organic matter, mantle, or carbonates） and help to constrain the fluid history and the mechanisms involved in graphite deposition. Graphite precipitation in fluid-deposited occurrences results from C02- and/or CH4-bearing aqueous fluids. fluid flow can be considered as both a closed （without replenishment of the fluid） or an open system （with renewal of the fluid by successive fluid batches）. In closed systems, carbon isotope systematics in graphite is mainly governed by Rayleigh precipi- tation and/or by changes in temperature affecting the fractionation factor between fluid and graphite. Such processes result in zoned graphite crystals or in successive graphite generations showing, in both cases, isotopic variation towards progressive 13C or 12C enrichment （depending upon the dominant carbon phase in the fluid, C02 or CH4, respectively）. In open systems, in which carbon is episodically introduced along the fracture systems, the carbon systematics is more complex and individual graphite crystals may display oscillatory zoning because of Rayleigh precipitation or heterogeneous variations of 613C values when mixing of fluids or changes in the composition of the fluids are the mechanisms responsible for graphite precipitation.

关键词： Graphite Carbon isotopes Crust C-O-H fluids

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pH-distribution of cerium species in aqueous systems

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journal of Rare Earths 2012年第6期30卷 559-562页

作者： B.Bouchaud j.Balmain *** f.Pedraza University of La Rochelle Laboratory of Engineering Science for the Environment LaSIE FRE-CNRS3474Avenue Michel Crépeau 17042 La Rochelle cedex 01FRANCE

Cerium-based oxide coatings can be obtained through either chemical or electrochemical processes on various conductor and semiconductor substrates. In both cases the films develop through a precipitation mechanism, which strongly depends on the solution chemistry. In the particular case of the electrolytic approach, the elaboration parameters play a key role on the interfacial pH modification thereby leading to an indirect precipitation mechanism. Indeed, the nucleation and growth mechanisms of crystallites and the composition of the resulting layers have been shown to be also strongly affected by the deposition conditions as well as by the substrate composition, which could in turn modify the protectiveness provided by such coatings. Therefore a better fundamental understanding of the system is required, in particular of the distribution of cerium-containing species in aqueous solution. To this end, the present work intended to develop a diagram showing the distribution as well as the relative amount of Ce（Ⅲ）/Ce（Ⅳ） species in aqueous media as a fimction of the pH range. The resulting pH-distribution diagram turned out to be a useful tool to predict the relevant precipitation mechanisms and species involved during the growth of ceriuna-containing films and to draw correlations with the characteristics of the as-deposited films.

关键词： pH-distribution diagram electrodeposition cerium-based oxide films precipitation mechanisms rare earths

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Unsteady magnetohydrodynamic stagnation point flow — closed-form analytical solutions

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Applied Mathematics and Mechanics(English Edition) 2019年第4期40卷 449-464页

作者： T.G.fANG f.j.WANG Bo GAO Mechanical and Aerospace Engineering Department North Carolina State University School of Energy & Power Engineering Jiangsu University

This paper investigates the unsteady stagnation point flow and heat transfer of magnetohydrodynamic(MHD) fluids over a moving permeable flat surface. The unsteady Navier-Stokes(NS) equations are transformed into a similarity nonlinear ordinary differential equation, and a closed form solution is obtained for the unsteadiness parameter of 2. The boundary layer energy equation is transformed into a similarity equation,and is solved for a constant wall temperature and a time-dependent uniform wall heat flux case. The solution domain, velocity, and temperature profiles are calculated for different combinations of parameters including the Prandtl number, mass transfer parameter, wall moving parameter, and magnetic parameter. Two solution branches are obtained for certain combinations of the controlling parameters, and a stability analysis demonstrates that the lower solution branch is not stable. The present solutions provide an exact solution to the entire unsteady MHD NS equations, which can be used for validating the numerical code of computational fluid dynamics.

关键词： unsteady stagnation point flow stretching/shrinking sheet magnetohy-drodynamic(MHD) Navier-Stokes(NS)equation

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3D flow Past Transonic Turbine Cascade SE 1050-Experiment and Numerical Simulations

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journal of Thermal Science 2013年第4期22卷 311-319页

作者： D.imurda j.fürst M.Luxa Institute of Thermomechanics AS CR v.v.i.Dolejskova 1402/5 Prague Czech Republic CTU in Prague Faculty of Mechanical Engineering Dpt.of Technical MathematicsKarlovo Náměstí 13 Prague Czech Republic

This paper is concerned with experimental and numerical research on 3D flow past prismatic turbine cascade SE1050 （known in QNET network as open test case SE1050）. The primary goal was to assess the influence of the inlet velocity profile on the flow structures in the interblade channel and on the flow field parameters at the cascade exit and to compare these findings to results of numerical simulations. Investigations of 3D flow past the cascade with non-uniform inlet velocity profile were carried out both experimentally and numerically at subsonic （M2 = 0.8） and at transonic （M2 = 1.2） regime at design angle of incidence. Experimental data was obtained using a traversing device with a five-hole conical probe. Numerically, the 3D flow was simulated by open source code OpenfOAM and in-house code. Analyses of experimental data and CfD simulations have revealed the development of distinctive vortex structures resulting from non-uniform inlet velocity profile. Origin of these structures results in increased loss of kinetic energy and spanwise shift of kinetic energy loss coefficient distribution. Differences found between the subsonic and the transonic case confirm earlier findings available in the literature. Results of CfD and experiments agree reasonably well.

关键词： blade cascade vortex structures transonic flow CfD

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Torsional mechanics of single walled carbon nanotubes with hydrogen for energy storage and fuel cell applications

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Science China(Physics,Mechanics & Astronomy) 2019年第3期62卷 93-101页

作者： V.Vijayaraghavan j.f.N.Dethan Liang Gao School of Mechanical and Manufacturing Engineering University of New South Wales School of Engineering Monash University Malaysia State Key Laboratory for Digital Manufacturing Equipment and Technology Huazhong University of Science and Technology

Torsional mechanics of single walled carbon nanotubes(SWCNTs) encapsulated with hydrogen molecules was investigated in this study, using the molecular dynamics(MD) simulation approach. The torsional properties of hydrogen stored SWCNTs were crucial for determining the durability and lifetime of SWNCTs-based energy storage and proton exchange membrane fuel cell(PEMfC) applications. The influence of hydrogen storage concentration, SWCNT geometry, vacancy defects, temperature variation and varying boundaries of rotated as well as fixed groups on the torsional mechanics of SWCNT was investigated. The results and conclusions provide an insight into the torsional properties of SWCNTs with hydrogen storage that could be used for the development of SWCNTs-based hydrogen storage devices and PEMfC applications.

关键词： single walled carbon nanotubes torsional properties hydrogen molecules vacancy defects

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Comparisons of jOULE 1 rocket thermospheric wind observations in high latitudes with GITM simulations

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Science China(Technological Sciences) 2017年第3期60卷 412-418页

作者： DENG Yue LARSEN Miguel f RIDLEY Aaron j ZHAN TianYu Department of Physics University of Texas at Arlington Department of Physics Clemson University Center for Space Environment Modeling The University of Michigan

4 Summary and conclusion The jOULE sounding rocket 1 experiment was carried out at Poker flat Research Range in Alaska around 1200 UT on March 27th,2003 with two instrumented rockets and one chemical tracer *** the released TMA trails,neutral wind measurements from approximately 85 to 160 km altitude showed a vertically propagating wave and a jet structure around 120 km *** shears appeared at the bottom side of the jet with Richardson numbers close to or smaller than the critical value of 0.25,which implies the possible existence of Kelvin-Helmholtz instabilities caused by the vertical shear in the fast flows.

关键词： target tracking parallel vision processor MRID skipping searching image processing

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Biothermomechanical behavior of skin tissue

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Acta Mechanica Sinica 2008年第1期24卷 1-23页

作者： f.Xu T.j.Lu K.A.Seffen Engineering Department Cambridge University Cambridge CB2 1PZ UK MOE Key Laboratory of Strength and Vibration School of Aerospace Xi'an Jiaotong University 710049 Xi'an China

Advances in laser, microwave and similar technologies have led to recent developments of thermal treatments involving skin tissue. The effectiveness of these treatments is governed by the coupled thermal, mechanical, biological and neural responses of the affected tissue： a favorable interaction results in a procedure with relatively little pain and no lasting side effects. Currently, even though each behavioral facet is to a certain extent established and understood, none exists to date in the interdisciplinary area. A highly interdisciplinary approach is required for studying the biothermomechanical behavior of skin, involving bioheat transfer, biomechanics and physiology. A comprehensive literature review pertinent to the subject is presented in this paper, covering four subject areas：（a） skin structure, （b） skin bioheat transfer and thermal damage, （c） skin biomechanics, and （d） skin biothermomechanics. The major problems, issues, and topics for further studies are also outlined. This review finds that significant advances in each of these aspects have been achieved in recent years. Although focus is placed upon the biothermomechanical behavior of skin tissue, the fundamental concepts and methodologies reviewed in this paper may also be applicable for studying other soft tissues.

关键词： Review Skin tissue Bioheat transfer Biomechanics Biothermomechanics

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Numerical Simulation of the Tip Aerodynamics and Acoustics Test

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journal of Thermal Science 2016年第2期25卷 153-160页

作者： f Tejero E P Doerffer O Szulc j L Cross The Szwalski Institute of fluid-flow Machinery Polish Academy of Sciences. Fiszera 14 80-231 Gdansk Poland NASA Ames Research Center (retired) Moffett Field CA USA

The application of an efficient flow control system on helicopter rotor blades may lead to improved aerodynamic performance. Recently, our invention of Rod Vortex Generators(RVGs) has been analyzed for helicopter rotor blades in hover with success. As a step forward, the study has been extended to forward flight conditions. for this reason, a validation of the numerical modelling for a reference helicopter rotor(without flow control) is needed. The article presents a study of the flow-field of the AH-1G helicopter rotor in low-, medium- and high-speed forward flight. The CfD code fLOWer from DLR has proven to be a suitable tool for the aerodynamic analysis of the two-bladed rotor without any artificial wake modelling. It solves the URANS equations with LEA(Linear Explicit Algebraic stress) k-ω model using the chimera overlapping grids technique. Validation of the numerical model uses comparison with the detailed flight test data gathered by Cross j. L. and Watts M. E. during the Tip Aerodynamics and Acoustics Test(TAAT) conducted at NASA in 1981. Satisfactory agreements for all speed regimes and a presence of significant flow separation in high-speed forward flight suggest a possible benefit from the future implementation of RVGs. The numerical results based on the URANS approach are presented not only for a popular, low-speed case commonly used in rotorcraft community for CfD codes validation but preferably for medium- and high-speed test conditions that have not been published to date.

关键词： AH-1G TAAT helicopter rotor forward flight chimera overlapping grid

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International Commission on Stratigraphy （ICS）

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Episodes 2005年第1期28卷 67-68页

作者： Ogg, j Gradstein, f Purdue Univ Dept Earth & Atmospher Sci W Lafayette IN 47907 USA Museum Geol & Paleontol N-0316 Oslo Norway

The International Commission on Stratigraphy (ICS) of IUGS is a body of expert stratigraphers founded for the purpose of promoting and coordinating long-term international cooperation and of establishing standards in ... 详细信息

关键词：地层学国际委员会 IUGS 学术交流组织体制科学合作

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Trans-scale mechanics: looking for the missing links between continuum and micro/nanoscopic reality

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Acta Mechanica Sinica 2008年第2期24卷 111-126页

作者： Y.L.Bai H.Y.Wang M.f.Xia f.j.Ke State Key Laboratory of Non-linear Mechanics (LNM) Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China State Key Laboratory of Non-linear Mechanics (LNM) Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China Department of Physics Peking University Beijing 100871 China State Key Laboratory of Non-linear Mechanics (LNM) Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China Department of Applied Physics Beihang University Beijing 100083 China

Problems involving coupled multiple space and time scales offer a real challenge for conventional frame-works of either particle or continuum mechanics. In this paper, four cases studies （shear band formation in bulk metallic glasses, spallation resulting from stress wave, interaction between a probe tip and sample, the simulation of nanoindentation with molecular statistical thermodynamics） are provided to illustrate the three levels of trans-scale problems （problems due to various physical mechanisms at macro-level, problems due to micro-structural evolution at macro/micro-level, problems due to the coupling of atoms/ molecules and a finite size body at micro/nano-level） and their formulations. Accordingly, non-equilibrium statistical mechanics, coupled trans-scale equations and simultaneous solutions, and trans-scale algorithms based on atomic/molecular interaction are suggested as the three possible modes of trans-scale mechanics.

关键词： Multi-scale Missing-links Continuum mechanics Particle mechanics Trans-scale mechanics

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