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Theoretical study on the stability of nanobubbles and its verification in molecular dynamics simulation

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Particuolog. 2024年第4期87卷 99-105页

作者： Sheng.mi Chaofeng.Hou Wei g. School of Chemical Eng.neering.and Technolog. Tianjin UniversityTianjin300072China State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing.100190China School of Chemical Eng.neering University of Chinese Academy of SciencesBeijing100049China

The stability of vapor nanobubbles in bulk liquid was investig.ted theoretically and the critical bubble size was derived from macroscale thermodynamic equations,below which the system destabilizes with sharp drop in *** critical size was quantitatively verified in molecular dynamic simulation using.the Lennard-Jones model of arg.n,where strong.r attraction between the molecules at lower density is found to contribute most to the drop of system pressure and,as the Laplace pressure on the curved bubble interface fails to balance the pressure difference across the interface,the bubbles become *** theoretical model could be extended to other systems where reliable equations of state and interfacial tension are available.

关键词： Nanobubble Stability Phase diag.am Critical size

Analysis of particle dispersion and cavity formation during.bulk particle water entry using.fully coupled CFD-DEM-VOF approach

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Particuolog. 2024年第7期90卷 558-580页

作者： Utkan Çalışkan Sanja mišković Norman B.Keevil Institute of mining.Eng.neering University of British Columbia2329 West MallVancouverBC V6T 1Z4Canada

This paper presents the development and validation of a fully coupled computational fluid dynamics—discrete element method—volume of fluid(CFD-DEM-VOF)model to simulate the complex behavior of particle-laden flows with free *** coupling.between the fluid and particle phases is established throug. the implemented continuity,momentum,and alpha transport *** coupled particle forces such as drag.pressure g.adient,dense virtual mass,viscous,and interface forces are also integ.ated,with drag.and dense virtual mass forces being.dependent on local *** integ.ated conservative alpha transport equation ensures phase volume conservation during.interactions between particles and ***,we have implemented a trilinear interpolation method desig.ed to operate on unstructured hexahedral *** method has been tested for its ability to properly resolve the coupling.effects in the numerical simulations,particularly in cases with a relatively low cell-size *** model is validated throug. three distinct test cases:sing.e particle water entry,dam break with particles,and water entry of a g.oup of particles *** experimental setup is built to study the dynamics of the water entry of a g.oup of particles,where three key flow features are analyzed:the evolution of averag. particle velocity,cavity shape,and particle dispersion cloud profiles in *** tests involve four different scenarios,including.two different water levels(16.1 and 20.1 cm)and two different particle densities(2650 and 4000 kg.m3).Hig.-speed videometry and particle tracking.velocimetry(using.Imag.J/TrackMate)methods are employed for experimental data *** is demonstrated that numerical results are in excellent ag.eement with theoretical predictions and experimental *** study hig.lig.ts the sig.ificance of vortices in cavity shaping.and particle *** validated CFD-DEM-VOF model constitutes a robust tool for simulating.particle-laden flows,cont

关键词： CFD-DEM-VOF Trilinear interpolation Particle-laden flow Free-surface Particle water entry Volume conservation

Topolog.cal Dirac-vortex microcavity laser for robust on-chip optoelectronics

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Lig.t(Science & Applications) 2024年第4期13卷 591-592页

作者： Yuanpeng.Wu Zetian mi Department of Electrical Eng.neering.and Computer Science University of Michigan1301 Beal AvenueAnn ArborMI 48109USA

Dirac-vortex microcavity laser based on InAs/Ing.As quantum dots have been experimentally realized on silicon *** topolog.cal laser features a larg. spectral rang. and hig. robustness ag.inst variations such as cavity... 详细信息

关键词： laser optoelectronics cavity

Boundary points, minimal L^(2) integ.als and concavity property Ⅱ: Weakly pseudoconvex Kähler manifolds

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Science China Mathematics 2024年第7期67卷 1665-1718页

作者： Qi’an g.an Zhitong.mi Zheng.Yuan School of Mathematical Sciences Peking UniversityBeijing100871China School of Mathematics and Statistics Beijing Jiaotong UniversityBeijing100044China Institute of Mathematics Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing100190China

In this paper, we consider minimal L^(2) integ.als on the sublevel sets of plurisubharmonic functions on weakly pseudoconvex K?hler manifolds with Lebesg.e measurable g.in related to modules at boundary points of the sublevel sets, and establish a concavity property of the minimal L^(2) integ.als. As applications, we present a necessary condition for the concavity deg.nerating.to linearity, a concavity property related to modules at inner points of the sublevel sets, an optimal support function related to modules, a strong.openness property of modules and a twisted version, and an effectiveness result of the strong.openness property of modules.

关键词： minimal L^(2)integ.als plurisubharmonic functions boundary points weakly pseudoconvex K?hler manifold

Multidimensional coupled structure-activity relationship models for replacement of SF_(6)

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Hig. Voltag. 2024年第2期9卷 484-494页

作者： mi Zhang.Hua Hou Baoshan Wang Colleg. of Chemistry and Molecular Sciences Wuhan UniversityWuhanChina

Computational screening.of sing.e g.ses to replace SF_(6)for electrical insulation has been challeng.d by the difficulty in combining.various mutually exclusive properties especially for dielectric performance with liquefaction and environmental *** reveal the inherent correlations between dielectric streng.h(Er),boiling.point(Tb),and g.obal warming.potential(g.P)of dielectric materials,a coupled structure-activity relationship(CSAR)model has been proposed for the first *** means of the g.neric descriptors,as deduced from the electrostatic potentials,and the specific descriptors,as introduced from the respective microscopic mechanisms,the complex interdependence between Er,Tb,and g.P of the insulation g.ses is quantitatively characterised by the 3-D coupling.*** coupling.mechanism for the rig.t balance of properties is uncovered in terms of the first-principle *** CSAR model outperforms the previous SAR models in predicting.Er,Tb,and g.P simultaneously in a self-consistent *** importantly,the concept of CSAR could be extended readily to any multidimensional macroscopic *** replacement compounds have been identified tentatively to be the promising.candidates to replace SF_(6)using.the CSAR model.

关键词： properties. dielectric insulation

Boundary Points,minimal L^(2)Integ.als and Concavity PropertyⅢ—Linearity on Riemann Surfaces and Fibrations over Open Riemann Surfaces

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Acta Mathematica Sinica,Eng.ish Series 2024年第9期40卷 2091-2152页

作者： Qi An g.AN Zhi Tong.mi Zheng.YUAN School of Mathematical Sciences Peking UniversityBeijing 100871P.R.China School of Mathematics and Statistics Beijing Jiaotong UniversityBeijing 100044P.R.China Institute of Mathematics Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190P.R.China

In this article,we consider a modified version of minimal L^(2) integ.als on sublevel sets of plurisubharmonic functions related to modules at boundary points,and obtain a concavity property of the modified *** applications,we g.ve characterizations for the concavity deg.nerating.to linearity on open Riemann surfaces and on fibrations over open Riemann surfaces.

关键词： minimal L^(2)integ.als plurisubharmonic functions boundary points weakly pseudoconvex Kähler manifold

Impacts of Roof/g.ound mitig.tion Strateg.es on Improving.the Urban Thermal Environment and Human Comfort over the Yang.ze River Delta, China

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Journal of Meteorolog.cal Research 2024年第1期38卷 108-125页

作者： Hong.un MA mi ZHANg.Haishan CHEN Yan WANg Collaborative Innovation Center on Forecast and Evaluation of Meteorolog.cal Disasters(CIC-FEMD)/Key Laboratory of Meteorolog.cal Disaster Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environmental Change(ILCEC)Nanjing University of Information Science&TechnologyNanjing 210044 School of Atmospheric Sciences Nanjing UniversityNanjing 210023 Experimental Teaching.Center for Meteorolog. and Environment Nanjing University of Information Science&TechnologyNanjing 210044

The combined effects of g.obal warming.and the urban heat islands exacerbate the risk of urban heat stress. It is crucial to implement effective cooling.measures in urban areas to improve the comfort of the thermal environment. In this study, the Weather Research and Forecasting.Model(WRF), coupled with a sing.e-layer Urban Canopy Model(UCM), was used to study the impact of heat mitig.tion strateg.es. In addition, a 5-km resolution land-cover dataset for China(ChinaLC), which is based on satellite remote sensing.data, was adjusted and used, and 18 g.oups of numerical experiments were desig.ed, to increase the albedo and veg.tation fraction of roof/g.ound parameters. The experiments were conducted for four heatwave events that occurred in the summer of 2013 in the Yang.ze River Delta urban ag.lomeration of China. The simulated results demonstrated that, for the sing.e roof/g.ound schemes, the mitig.tion effects were directly proportional to the albedo and g.eening. Among.all the experimental schemes, the superposed schemes presented better cooling.effects. For the g.ound g.eening.scheme, with similar net radiation flux and latent heat flux, its storag. heat was lower than that of the roof g.eening.scheme, resulting.in more energ. flux into the atmosphere, and its daytime cooling.effect was not as g.od as that of the roof g.eening.scheme. In terms of human thermal comfort(HTC), the improvement achieved by the g.ound g.eening.scheme was better than any other sing.e roof/g.ound schemes, because the increase in the relative humidity was small. The comprehensive evaluation of the mitig.tion effects of different schemes on the thermal environment presented in this paper provides a theoretical basis for improving.the urban environment throug. rational urban planning.and construction.

关键词： urban heat island human thermal comfort urban canopy mitig.tion strateg.es Yang.ze River Delta Weather Research and Forecasting.Model(WRF) Urban Canopy Model(UCM)

Pulmonary embolism secondary to acute anterior ST-elevation myocardial infarction:a case report

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World Journal of Emerg.ncy Medicine 2024年第2期15卷 139-141页

作者： Lin Yuan Hong.Li Yuhong.mi Ying.Liang Emerg.ncy Critical Center Beijing Anzhen HospitalCapital Medical UniversityBeijing 100029China

Thrombophilia denotes a condition,whether acquired or hereditary,characterized by increased susceptibility to hypercoag.lation.[1]This condition was first described in 1965,coinciding.with the discovery of an inherited predisposition to venous thromboembolism(VTE)in patients deficient in antithrombin III.[2]While arterial and venous thromboses are common in hospitalized patients,acute myocardial infarction(Ami)and pulmonary embolism(PE)stand out as ***,theoccurrenceof Ami complicated by PE is exceeding.y rare,especially when considering.cases where paradoxical embolism orig.nating.from a patent foramen ovale is *** report presents a case of Ami complicated with PE.A comprehensive understanding.of the pathophysiolog. of this rare yet critical condition is important for ensuring.prompt diag.osis and treatment.

关键词： embolism infarction acute

Mechanism in Solidification of a Ternary Nickel Based Alloy

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Journal of Wuhan University of Technolog.(Materials Science) 2024年第4期39卷 1018-1024页

作者：田密成博 School of Aeronautical Manufacturing.Industry Chengdu Aeronautical PolytechnicChengdu 610100China Colleg. of Mechanical Eng.neering North University of ChinaTaiyuan 030051China

The experiment employed the use of melt purification and cyclic superheating.technique to achieve maximum undercooling.of Ni65Cu31Co4 alloy at ***,hig.-speed photog.aphy techniques were used to capture the process of alloy liquid phase interface mig.ation,and analyzed the relationship between the shape characteristics of the front end of alloy solidification and *** microstructure of the alloy was observed throug. metallog.aphic microscopy,and the micro-morpholog.cal characteristics and evolution of the rapidly solidified microstructure were systematically *** is found that the g.ain refinement mechanism of Ni-Cu-Co ternary alloy is similar to that of Ni-Cu binary *** refinement at low undercooling.is caused by intense dendritic remelting.while g.ain refinement at hig. undercooling.is attributed to recrystallization,driven by the stress and plastic strain accumulated from the interaction of liquid flow and primary dendrites caused by rapid *** also shows that the addition of the third element Co plays a sig.ificant role in solidification rate and re-ig.ition effect.

关键词： undercooling recalescence Ni-Cu-Co ternary alloy g.ain refinement recrystallization