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Effect of furnace atmosphere on sintering process of chromium-containing steel via powder metallurgy

Journal of Iron and Steel Research International 2021年第7期28卷 889-900页

作者： Zhao-qiang Tan Ulf EngstrÖm Kun Li Yong Liu State Key Laboratory of Powder metallurgy Central South UniversityChangsha 410083HunanChina HÖganäs China Co. Ltd.Shanghai 201799China

During a powder metallurgy process such as sintering,the primary role played by the atmosphere in furnace is to prevent an excessive oxidation of powder compacts in case of the formation of oxides as residuals on powder *** particular,the adjustment of furnace atmosphere is the key to eliminate the phenomenon"decarburization"likely to occur in carbon-containing compacts.A continuous belt furnace was used to stabilize the potentials of carbon and oxygen in zones divided by sintering,delubrication,and *** and manganese,which are sensitive to oxygen,were added to improve mechanical properties in a cost-effective *** of steel containing chromium were sintered in an atmosphere composed of CO,O_(2),and H_(2).The effects of atmosphere,lubricant,and graphite on oxidation(or reduction)and decarburization(or carburization)were *** quality was achieved under the control of delubrication *** is indicated that in a protective atmosphere,the chemical reactions occurring at various stages took remarkable effect on the quality of sintered *** potentials of oxygen and carbon in a continuous belt furnace were monitored and analyzed using an on-line thermal measuring unit consisting of thermocouple,oxygen probe,and carbon monoxide *** avoidance of oxidation and decarburization promises desired micro structure and carbon content and satisfactory properties through the adjustment of technical parameters,e.g.,the composition of gases in delubrication and various sintering zones,the rate of gas inlet,and cooling rate.

关键词： Powder metallurgy steel Sintering atmosphere Carbon potential Oxygen partial pressure Chromium alloy

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Element-Free modelling of Topological Gels with Peculiar multiaxial Large Deformation Behavior

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Acta mechanica Solida Sinica 2022年第5期35卷 880-890页

作者： D.m.Li Jia-Hui Liu Jia-Xuan Xie School of Civil Engineering and Architecture Wuhan University of TechnologyWuhan430070China School of Science Wuhan University of TechnologyWuhan430070China

With slidable cross-links along the polymer strands,topological gels can adjust their network topology in response to the imposed *** reported in experimental studies from the literature,the unique cross-linking strategy and the distinct deformation mechanism result in a peculiar multiaxial behavior with minimal strain-coupling between different principal directions at relatively low cross-linking *** paper presents an element-free modelling of the topological gels focusing on their nonlinear stress–strain behavior under general biaxial ***,conditions of uniaxial stretching and the three types of biaxial deformation,i.e.,equibiaxial stretching,pure shear deformation,and“two-step”biaxial deformation are *** numerical stress–strain curves for these conditions are compared against those from the literature.

关键词： Topological gel multiaxial deformation Large deformation Element-free method Hyperelasticity

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molecular dynamics simulation of the Stribeck curve: Boundary lubrication, mixed lubrication, and hydrodynamic lubrication on the atomistic level

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摩擦:英文版 2023年第12期11卷 2342-2366页

作者： Simon STEPHAN Sebastian SCHmITT Hans HASSE Herbert m.URBASSEK Laboratory of Engineering Thermodynamics(LTD) Department of Mechanical and Process EngieeringTU KaiserslauternRheinland-Pfalz 67663Germany Physics Department and Research Center(OPTImAS) TU KaiserslauternRheinland-Pfalz 67663Germany

Lubricated contact processes are studied using classical molecular dynamics simulations for determining the entire range of the Stribeck ***,the lateral movement of two solid bodies at different gap height are *** each simulation,a rigid asperity is moved at constant height above a flat iron surface in a lubricating *** methane and decane are considered as *** three main lubrication regimes of the Stribeck curve and their transition regions are covered by the study:Boundary lubrication(significant elastic and plastic deformation of the substrate),mixed lubrication(adsorbed fluid layer dominates the process),and hydrodynamic lubrication(shear flow is set up between the surface and the asperity).We find the formation of a tribofilm in which lubricant molecules are immersed into the metal surface—not only in the case of scratching,but also for boundary lubrication and mixed *** formation of a tribofilm is found to have important consequences for the contact ***,the two fluids are found to show distinctly different behavior in the three lubrication regimes:For hydrodynamic lubrication(large gap height),decane yields a better tribological performance;for boundary lubrication(small gap height),decane shows a larger friction coefficient than methane,which is due to the different mechanisms observed for the formation of the tribofilm;the mixed lubrication regime can be considered as a transition regime between the two other ***,it is found that the nature of the tribofilm depends on the lubricant:While methane particles substitute substrate atoms sustaining mostly the crystalline structure,the decane molecules distort the substrate surface and an amorphous tribofilm is formed.

关键词： boundary lubrication mixed lubrication hydrodynamic lubrication molecular dynamics simulation tribofilm

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Saxicolous lichen communities in three basins associated with mining activity in northwestern Argentina

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Journal of Arid Land 2023年第8期15卷 989-1005页

作者： Juan m HERNÁNDEZ Renato A GARCÍA Edith R FILIPPINI Cecilia ESTRABOU martha S CAÑAS Juan m RODRÍGUEZ Faculty of Technology and Applied Sciences Regional Centre of Energy and Environment for Sustainable DevelopmentNational University of CatamarcaCatamarca 4700Argentina Laboratory of Biodiversity and Environmental Genetics National University of AvellanedaAvellaneda 1870Argentina Institute of Biological and Technological Research Centre for Ecology and Renewable Natural ResourcesFaculty of ExactPhysical and Natural SciencesNational University of CordobaCordoba 5000Argentina

mining activity affects the vegetation and soils of the ***,the effects of mining activity on saxicolous lichen communities are less ***,the aim of this study was to characterize saxicolous lichen communities in three basins(Vis-Vis River basin,Poteros River basin,and Capillitas River basin)surrounding metalliferous mining projects of different types of operation and at different stages of exploitation.A large-scale mine(Bajo de la Alumbrera)with more than 25 a of open-pit mining located in the Vis-Vis River basin(CRV).A pre-exploitation mine(Agua Rica)located in the Poteros River basin(CRP),and a small-scale mine(minas Capillitas)with more than 160 a of underground mining located in the Capillitas River basin(CAC).In each basin,species richness,cover,and frequency of lichen communities were measured on 40 rock ***,explanatory variables were recorded,i.e.,altitude,slope,aspect,vegetation cover,rock,and soil cover around the rocky area *** and total cover of lichen communities were analysed using linear models,and species composition was explored using multivariate ordination *** showed that a total of 118 lichen species were *** species richness differed among basins and the lichen composition present in areas close to mining sites responded mainly to basins,altitude,and microsite *** lichen cover showed no difference among basins,but it changed under different rock and vegetation *** was not possible to quantify the effects of mining activity on species richness and ***,the low richness values found in the downstream of minera Alumbrera could be associated with the negative impact of open-pit ***,the effects of large-scale mining activity on lichen communities needs more investigation.

关键词： lichen community altitude microsite metalliferous mining vegetation

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Two-fluid modelling for cylindrical fluidized beds using kinetic theory for rough spheres

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Particuology 2020年第3期18卷 25-34页

作者： Lei Yang J.T.Padding J.A.m.Kuipers Helmholtz Institute Erlangen-Nürnberg for Renewable Energy(IEK-11) Fürther Straβe 24890429 NurnbergGermany Department of Process and Energy Delft University of Technology2628CB DelftThe Netherlands Department of Chemical Engineering and Chemistry Eindhoven University of Technology5600MB EindhovenThe Netherlands

Recently,we have extended the kinetic theory of granular flow (KTGF) to include friction between the spherical particles and tested it in rectangular *** this study,the extended KTGF implemented in cylindrical coordinates is used to model the more-commonly employed cylindrical bubbling fluidized *** attention is paid to the anti-symmetric part of the velocity gradient in the solids stress *** verification of the implementation,a comparison of the present model in the limit of zero friction with the original (frictionless) KTGF model was ***,simulations of bubbling fluidized beds of inelastic particles were performed using our extended KTGF and an effective KTGF model for inelastic particles of Jenkins and *** simulation results show good agreement for the time-averaged solids volume fraction distribution and solids circulation ***,our model is validated by predicting the individual bubble behavior in dense bubbling fluidized beds containing different granular materials in a comparison with experimental data from Verma et al.(2014).The extended KTGF leads to an improved agreement with experimental bubble *** to previous work (Yang et al.,2016b,2017c),and by introducing cylindrical coordinates,the current work demonstrates that the extended KTGF improves predictions for the temporal bubble behavior of cylindrical fluidized beds.

关键词： Fluidization Frictional collision Rough particles Cylindrical bed hydrodynamics Two-fluid model

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Reservoir stress path and induced seismic anisotropy： results from linking coupled fluid-flow/geomechanical simulation with seismic modelling

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Petroleum Science 2016年第4期13卷 669-684页

作者： D.A.Angus Q.J.Fisher J.m.Segura J.P.Verdon J.-m.Kendall m.Dutko A.J.L.Crook School of Earth and Environment University of LeedsLeeds UK Formerly School of Earth and Environment University of Leeds Leeds UK Department of Earth Sciences University of Bristol BristolUK Rockfield Software Ltd. Swansea UK Three Cliffs Geomechanics Swansea UK Repsol Madrid Spain ESG Solutions Kingston Canada

We present a workflow linking coupled fluid-flow and geomechanical simulation with seismic modelling to predict seismic anisotropy induced by non-hydrostatic stress changes. We generate seismic models from coupled simulations to examine the relationship between reservoir geometry, stress path and seismic anisotropy. The results indicate that geometry influences the evolution of stress,which leads to stress-induced seismic anisotropy. Although stress anisotropy is high for the small reservoir, the effect of stress arching and the ability of the side-burden to support the excess load limit the overall change in effective stress and hence seismic anisotropy. For the extensive reservoir, stress anisotropy and induced seismic anisotropy are high. The extensive and elongate reservoirs experience significant compaction, where the inefficiency of the developed stress arching in the side-burden cannot support the excess *** elongate reservoir displays significant stress asymmetry,with seismic anisotropy developing predominantly along the long-edge of the reservoir. We show that the link betweenstress path parameters and seismic anisotropy is complex,where the anisotropic symmetry is controlled not only by model geometry but also the nonlinear rock physics model used. Nevertheless, a workflow has been developed to model seismic anisotropy induced by non-hydrostatic stress changes, allowing field observations of anisotropy to be linked with geomechanical models.

关键词： Coupled fluid-flow/geomechanics Reservoir characterization Seismic anisotropy Stress path

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The Representation of Soil moisture−Atmosphere Feedbacks across the Tibetan Plateau in CmIP6

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Advances in Atmospheric Sciences 2023年第11期40卷 2063-2081页

作者： Joshua TALIB Omar V.mÜLLER Emma J.BARTON Christopher m.TAYLOR Pier Luigi VIDALE U.K.Centre of Ecology and Hydrology WallingfordOX108BBU.K. National Centre for Atmospheric Science ReadingRG66BBU.K. Consejo Nacional de Investigaciones Científicas y Técnicas(CONICET) Centro de Estudios de Variabilidad y Cambio Climático(CEVARCAM)Facultad de Ingeniería y Ciencias HídricasUniversidad Nacional del LitoralSanta FeArgentina National Centre for Earth Observation WallingfordOX108BBU.K. Department of meteorology University of ReadingReadingRG66BBU.K.

Thermal processes on the Tibetan Plateau(TP)influence atmospheric conditions on regional and global *** this,previous work has shown that soil moisture−driven surface flux variations feed back onto the *** soil moisture is a source of atmospheric predictability,no study has evaluated soil moisture−atmosphere coupling on the TP in general circulation models(GCms).In this study,we use several analysis techniques to assess soil moisture−atmosphere coupling in CmIP6 simulations including:instantaneous coupling indices;analysis of flux and atmospheric behaviour during dry spells;and a quantification of the preference for convection over drier *** these metrics we partition feedbacks into their atmospheric and terrestrial *** with previous global studies,we conclude substantial inter-model differences in the representation of soil moisture−atmosphere coupling,and that most models underestimate such *** on dry spell analysis,most models underestimate increased sensible heat during periods of rainfall *** example,the model-mean bias in anomalous sensible heat flux is 10 W m−2(≈25%)smaller compared to *** dry-spell sensible heat fluxes lead to a weaker atmospheric *** also find that most GCms fail to capture the negative feedback between soil moisture and deep *** poor simulation of feedbacks in CmIP6 experiments suggests that forecast models also struggle to exploit soil moisture−driven *** improve the representation of land−atmosphere feedbacks requires developments in not only atmospheric modelling,but also surface processes,as we find weak relationships between rainfall biases and coupling indexes.

关键词： model evaluation land-atmosphere feedbacks Tibetan Plateau precipitation surface energy balance

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Epidemiological characteristics and genetic alterations in adult diffuse glioma in East Asianpopulations

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Cancer Biology & medicine 2022年第10期19卷 1440-1459页

作者： Zongchao mo Junyi Xin Ruichao Chai Peter Y.m.Woo Danny T.m.Chan Jiguang Wang Division of Life Science and State Key Laboratory of molecular Neuroscience The Hong Kong University of Science and TechnologyClear Water BayKowloonHong Kong SARChina HKUST Shenzhen-Hong Kong Collaborative Innovation Research Institute Shenzhen 518000China Department of molecular Neuropathology Beijing Neurosurgical InstituteCapital Medical UniversityBeijing 100070China Department of Neurosurgery Kwong Wah HospitalHong Kong SARChina Hong Kong Neuro-Oncology Society Hong Kong SARChina Division of Neurosurgery Department of SurgeryPrince of Wales HospitalHong Kong SARChina Department of Chemical and Biological Engineering The Hong Kong University of Science and TechnologyClear Water BayKowloonHong Kong SARChina Hong Kong Center for Neurodegenerative Diseases Hong Kong Science ParkHong Kong SARChina

Understanding the racial specificities of diseases—such as adult diffuse glioma,the most common primary malignant tumor of the central nervous system—is a critical step toward precision ***,we comprehensively review studies of gliomas in East Asian populations and other ancestry groups to clarify the racial differences in terms of epidemiology and genomic ***,we observed a lower glioma incidence in East Asians than in Whites;notably,patients with glioblastoma had significantly younger ages of onset and longer overall survival than the *** genome-wide association studies of various cohorts have revealed single nucleotide polymorphisms associated with overall and subtype-specific glioma ***,only 3 risk loci—5p15.33,11q23.3,and 20q13.33—were shared between patients with East Asian and White ancestry,whereas other loci predominated only in particular *** instance,risk loci 12p11.23,15q15-21.1,and 19p13.12 were reported in East Asians,whereas risk loci 8q24.21,1p31.3,and 1q32.1 were reported in studies in White *** the somatic mutational profiles of gliomas between East Asians and non-East Asians were broadly consistent,a lower incidence of EGFR amplification in glioblastoma and a higher incidence of 1p19q-IDH-TERT triple-negative low-grade glioma were observed in East Asian *** summarizing large-scale disease surveillance,germline,and somatic genomic studies,this review reveals the unique characteristics of adult diffuse glioma among East Asians,to guide clinical management and policy design focused on patients with East Asian ancestry.

关键词： Glioma East Asian epidemiology germline somatic

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Effect of particle size distribution on magnetic behavior of nanoparticles with uniaxial anisotropy

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Chinese Physics B 2018年第9期27卷 572-576页

作者： S Rizwan Ali Farah Naz Humaira Akber m Naeem S Imran Ali S Abdul Basit m Sarim Sadaf Qaseem Department of Physics Federal Urdu University of Arts Science and Technology Department of Applied Chemistry and Chemical Technology University of Karachi Department of Computer Science Federal Urdu University of Arts Science and Technology

The effect of particle size distribution on the field and temperature dependence of the hysteresis loop features like coercivity（HC）, remanence（mR）, and blocking temperature（TB） is simulated for an ensemble of single domain ferromagnetic nanoparticles with uniaxial anisotropy. Our simulations are based on the two-state model for T 〈 TB and the metropolis monte-Carlo method for T 〉 TB. It is found that the increase in the grain size significantly enhances HC and TB. The presence of interparticle exchange interaction in the system suppresses HC but causes mRto significantly *** results show that the parameters associated with the particle size distribution（D（d,δ）） such as the mean particle size d and standard-deviation δ play key roles in the magnetic behavior of the system.

关键词： magnetic nanoparticles monte Carlo simulations size distribution interparticle interaction hysteresis

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multi-quasiparticle excitations in ^(145)Tb

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Science China(Physics,mechanics & Astronomy) 2004年第5期47卷 561-570页

作者： T. Hayakawa m. Oshima T. Toh T. Shizuma J. Katakura Y. Hatsukawa m. matsuda H. Kusakari m. Sugawara Japan Atomic Energy Research Institute Tokai Ibaraki 319-1195 JapanJapan Atomic Energy Research Institute Tokai Ibaraki 319-1195 JapanJapan Atomic Energy Research Institute Tokai Ibaraki 319-1195 JapanJapan Atomic Energy Research Institute Tokai Ibaraki 319-1195 JapanJapan Atomic Energy Research Institute Tokai Ibaraki 319-1195 JapanJapan Atomic Energy Research Institute Tokai Ibaraki 319-1195 JapanJapan Atomic Energy Research Institute Tokai Ibaraki 319-1195 JapanChiba University Inage-ku Chiba 263-8512 JapanChiba Institute of Technology Narashino Chiba 275-0023 Japan

High-spin states in 145Tb have been populated using the 118Sn (32S, 1p4n) reaction at beam energy of 165 meV. The level scheme of 145Tb has been established up to Ex ≈7.4 meV. The level scheme shows characteristics of a spherical or slightly oblate nucleus. Based on the systematic trends of the level structure in the neighboring N = 80 isotones, the level structure in 145Tb below 2 meV excitation is well explained by coupling an h11/2valence proton to the even-even 144Gd core. Above 2 meV excitation, most of the yrast levels are interpreted with multi-quasiparticle shell-model configurations.

关键词： high-spin states, level scheme, multi-quasiparticle excitations.

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