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

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Particuology 2024年第4期87卷 99-105页

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

the stability of vapor nanobubbles in bulk liquid was investigated 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 argon,where stronger 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 diagram Critical size

Ion Dynamics in Concentrated Electrolyte Solutions:Relating Equilibrium Fluctuations of the Ions to transport Properties in Battery Cells

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Energy & Environmental Materials 2024年第1期7卷 131-138页

作者： Bernhard Roling Vanessa miß Janosch Kettner Department of Chemistry University of MarburgHans-Meerwein-Str.435032 MarburgGermany

In recent years,the interest in the development of highly concentrated electrolyte solutions for battery applications has increased *** electrolyte solutions are typically characterized by a low flammability,a high thermal and electrochemical stability and by the formation of a stable solid electrolyte interphase(SEI)in contact to electrode ***,the classification of concentrated electrolyte solutions in terms of the classical scheme"strong"or"weak"has been controversially discussed in the *** this paper,a comprehensive theoretical framework is presented for a more general classification,which is based on a comparison of charge transport and mass *** combining the Onsager transport formalism with linear response theory,center-of-mass fluctuations and collective translational dipole fluctuations of the ions in equilibrium are related to transport properties in a lithium-ion battery cell,namely mass transport,charge transport and Li^(+)transport under anion-blocking *** relevance of the classification approach is substantiated by showing that i)it is straightforward to classify highly concentrated electrolytes and that ii)both fast charge transport and fast mass transport are indispensable for achieving fast Li^(+)transport under anion-blocking conditions.

关键词： batteries concentrated electrolytes linear response theory Onsager formalism transport

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

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Particuology 2024年第7期90卷 558-580页

作者： Utkan Çalışkan Sanja mišković Norman B.Keevil Institute of mining Engineering 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 through the implemented continuity,momentum,and alpha transport *** coupled particle forces such as drag,pressure gradient,dense virtual mass,viscous,and interface forces are also integrated,with drag and dense virtual mass forces being dependent on local *** integrated conservative alpha transport equation ensures phase volume conservation during interactions between particles and ***,we have implemented a trilinear interpolation method designed 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 through three distinct test cases:single particle water entry,dam break with particles,and water entry of a group of particles *** experimental setup is built to study the dynamics of the water entry of a group of particles,where three key flow features are analyzed:the evolution of average 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).High-speed videometry and particle tracking velocimetry(using ImageJ/trackMate)methods are employed for experimental data *** is demonstrated that numerical results are in excellent agreement with theoretical predictions and experimental *** study highlights the significance 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

topological Dirac-vortex microcavity laser for robust on-chip optoelectronics

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Light(Science & Applications) 2024年第4期13卷 591-592页

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

Dirac-vortex microcavity laser based on InAs/InGaAs quantum dots have been experimentally realized on silicon *** topological laser features a large spectral range and high robustness against variations such as cavity... 详细信息

关键词： laser optoelectronics cavity

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

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High Voltage 2024年第2期9卷 484-494页

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

Computational screening of single gases to replace SF_(6)for electrical insulation has been challenged by the difficulty in combining various mutually exclusive properties especially for dielectric performance with liquefaction and environmental *** reveal the inherent correlations between dielectric strength(Er),boiling point(tb),and global warming potential(GWP)of dielectric materials,a coupled structure-activity relationship(CSAR)model has been proposed for the first *** means of the generic 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 GWP of the insulation gases is quantitatively characterised by the 3-D coupling *** coupling mechanism for the right balance of properties is uncovered in terms of the first-principle *** CSAR model outperforms the previous SAR models in predicting Er,tb,and GWP 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

Distributed Region tracking and Perimeter Surveillance for Second-Order Multi-Agent Systems in Star-Shaped Sets

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Journal of Systems Science & Complexity 2024年第5期37卷 1995-2020页

作者： SHANG Juan MO Lipo mi Rongxin CAO Xianbing School of Mathematics and Statistics Beijing Technology and Business University the Department of Foundation Shijiazhuang Institute of Railway Technology School of Computer and Artificial Intelligence Beijing Technology and Business University Research Centre for Agri-Product Quality traceability Beijing Technology and Business University Coordination Center of China National Computer Network Emergency Response Technical Team

this paper investigates region tracking and perimeter surveillance of second-order multi-agent systems, where all agents move within a star-shaped set. First, by coordination transformations,the region tracking problem is converted from the star-shaped sets to a circular region. the authors employ communication and collaboration to complete region tracking and perimeter surveillance tasks,and then revert back to the star-shaped set by using inverse transformations. Second, the authors propose a distributed control strategy based on attractive and interaction potential functions, under which all agents can quickly track a given circular region and move around the perimeter. Finally,the authors validate the effectiveness and performance advantages of the proposed method through simulation experiments.

关键词： Distributed control multi-agent systems star-shaped sets target tracking

Boundary points, minimal L^(2) integrals 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 Guan 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) integrals on the sublevel sets of plurisubharmonic functions on weakly pseudoconvex K?hler manifolds with Lebesgue measurable gain related to modules at boundary points of the sublevel sets, and establish a concavity property of the minimal L^(2) integrals. As applications, we present a necessary condition for the concavity degenerating 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)integrals plurisubharmonic functions boundary points weakly pseudoconvex K?hler manifold

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

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Acta Mathematica Sinica,English Series 2024年第9期40卷 2091-2152页

作者： Qi An GUAN 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) integrals on sublevel sets of plurisubharmonic functions related to modules at boundary points,and obtain a concavity property of the modified *** applications,we give characterizations for the concavity degenerating to linearity on open Riemann surfaces and on fibrations over open Riemann surfaces.

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

Impacts of Roof/Ground mitigation Strategies on Improving the Urban thermal Environment and Human Comfort over the Yangtze River Delta, China

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Journal of Meteorological Research 2024年第1期38卷 108-125页

作者： Hongyun MA mi ZHANG Haishan CHEN Yan WANG Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)/Key Laboratory of Meteorological 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 Meteorology and Environment Nanjing University of Information Science&TechnologyNanjing 210044

the combined effects of global 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 single-layer Urban Canopy Model(UCM), was used to study the impact of heat mitigation strategies. 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 groups of numerical experiments were designed, to increase the albedo and vegetation fraction of roof/ground parameters. the experiments were conducted for four heatwave events that occurred in the summer of 2013 in the Yangtze River Delta urban agglomeration of China. the simulated results demonstrated that, for the single roof/ground schemes, the mitigation effects were directly proportional to the albedo and greening. Among all the experimental schemes, the superposed schemes presented better cooling effects. For the ground greening scheme, with similar net radiation flux and latent heat flux, its storage heat was lower than that of the roof greening scheme, resulting in more energy flux into the atmosphere, and its daytime cooling effect was not as good as that of the roof greening scheme. In terms of human thermal comfort(HtC), the improvement achieved by the ground greening scheme was better than any other single roof/ground schemes, because the increase in the relative humidity was small. the comprehensive evaluation of the mitigation effects of different schemes on the thermal environment presented in this paper provides a theoretical basis for improving the urban environment through rational urban planning and construction.

关键词： urban heat island human thermal comfort urban canopy mitigation strategies Yangtze River Delta Weather Research and Forecasting Model(WRF) Urban Canopy Model(UCM)