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Quantitative gradient estimates for harmonic maps into singular spaces

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Science China Mathematics 2019年第11期62卷 2371-2400页

作者： Hui-chun Zhang xiao Zhong xi-Ping Zhu Department of Mathematics Sun Yat-sen UniversityGuangzhou 510275China Department of Mathematics and Statistics University of HelsinkiHelsinki F7-00014Finland

In this paper, we show the Yau’s gradient estimate for harmonic maps into a metric space(X, dX)with curvature bounded above by a constant κ(κ 0) in the sense of Alexandrov. As a direct application,it gives some Liouville theorems for such harmonic maps. This extends the works of Cheng(1980) and Choi(1982) to harmonic maps into singular spaces.

关键词： harmonic maps Bochner formula CAT(κ)-spaces Liouville theorem

Navigating the safe operation of high-voltage cathodes:Challenges and strategies

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Nano Research 2024年第10期17卷 8694-8705页

作者： Yue Sun Changjian Zuo Yi-chun lu Electrochemical Energy and Interfaces Laboratory Department of Mechanical and Automation EngineeringThe Chinese University of Hong KongHong Kong 999077China

Lithium-ion batteries play a crucial role in storing energy for renewable sources and electric vehicles,yet face challenges related to insufficient energy *** the working-voltage of cathodes is promising to boost the energy density of batteries by increasing both the output voltage and capacity of cathode,which however could compromise life cycle and *** review provides a comprehensive summary of essential factors governing pathways of cathode-induced thermal runaway,including electrolyte decomposition,phase transitions,and crosstalk-induced *** and electrolyte modifications aimed at mitigating parasitic reactions and preventing crosstalk were also *** review concludes with insights into the future application of these strategies,providing a comprehensive perspective on the realization of high-energy and safe batteries.

关键词： battery safety high-voltage cathode lithium-ion battery thermal runaway

Shear Fracture of Advanced High Strength Steels

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Journal of Iron and Steel Research International 2014年第10期21卷 938-944页

作者： Sheng HUANG Yi-xi ZHAO chun-feng HE State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures Shanghai Jiao Tong University

Failure experiments were carried out through a stretch-bending test system for advanced high strength steels, i.e. dual-phase （DP） steels and martensitic steels （MS）. The die radius in this system was designed from 1 to 15 mm to investigate the failure mode under different geometries. Two failure modes were observed during the ex- periments. As a result, critical relative radii （the ratio of inner bending radius R to sheet thickness t） for DP590 and DP780 steels were obtained. The stretch-bending tests of DP980 display some trends unlike DP590 and DP780 steels, and curve of DP980 in different thicknesses does not coincide well. High blank holder force exhibits more possibility of shear fracture tendency than low blank holder force. The unique character of high strength martensitic steel （1500MS） is that no shear fracture is found especially over small bending radius （R =2 mm） under the same experi- mental conditions. Microstructure analysis indicates that there are obviously elongated grains on shear fracture sur- face. It shows smaller diameter and shallower depth of the dimples than the necking failure.

关键词： advanced high strength steel shear fracture critical R/t blank holder force microstructure

Statistical Analysis of Coherent Vortical Structures in a Supersonic Turbulent Boundary Layer

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Chinese Physics Letters 2011年第3期28卷 124-127页

作者： WANG Li lu xi-Yun Department of Modern Mechanics University of Science and Technology of ChinaHefei 230026

Characteristics of coherent vortical structures in a compressible turbulent boundary layer are statistically analyzed by means or airect numerical simulation of the compressible Navier-Stokes equations for Mach number M=2and Reynolds number Reθ≈1000 based on the inlet momentum *** is found that a large variety of hairpin-like and cane-like vortical structures exist in the boundary layer and the most popular structure is the cane-like *** injection and sweep events contribute a major proportion of the total Reynolds *** study indicates structural similarities with the incompressible ***,the length scales of coherent structures in the streamwise and spanwise directions increase with the distance from the *** inclination angle of vortical structures with respect to the streamwise direction increases from the suboayer to the buffer layer and then decreases from the buffer layer to the wake region.

关键词： coherent Reynolds boundary

The Effect of Mach Number on Turbulence Behaviors in Compressible Boundary Layers

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Chinese Physics Letters 2011年第6期28卷 190-193页

作者： WANG Li lu xi-Yun Department of Modern Mechanics University of Science and Technology of ChinaHefei 230026

The effects of Mach number on turbulence behaviors are investigated by means of direct numerical simulation of compressible turbulent boundary layers with the free-stream Mach numbers 2,4 and *** typical turbulent quantities,including the velocity and vorticity fluctuations,intermittency,sweep and ejection events and turbulent kinetic energy budget,are *** turbulence intensities are significantly decreased with the increasing Mach *** onset of intrinsic intermittency occurs nearer the wall for a higher Mach *** ejection event is more frequent and the sweep event becomes less ***,the magnitudes of turbulent kinetic energy production,diffusion and transport terms are increased and the solenoidal dissipation is slightly decreased as the Mach number is increased.

关键词： turbulent turbulence quantities

Existence of Three Positive Solutions for Some Second-Order M-Point Boundary Value Problems

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Acta Mathematicae Applicatae Sinica 2008年第2期24卷 253-264页

作者： Liu Yang chun-fang Shen xi-ping Liu Department of Mathematics Hefei Teacher's College Heifei 230061 China College of Science University of Shanghai for Science and Technology Shanghai 200093 China

By using fixed-point theorems, some new results for multiplicity of positive solutions for some second order m-point boundary value problems are *** associated Green＇s function of these problems are also given.

关键词： second order m-point boundary value problem, positive solution cone, fixed point

Synthesis and Crystal Structure of [Cp_2Ln(OC(SEt)NPh )]_2

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Chinese Journal of Structural Chemistry 2006年第2期25卷 131-134页

作者： ZHANG chun-Mei LIU Rui-Ting ZHOU xi-Geng Department of Chemistry Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Fudan University Shanghai 200433 China Department of Chemistry East China University of Science and Technology Shanghai 200237 China

Treatment of Cp3Y with EtSH, followed by reaction with an equivalent of PhNCO, yielded the dinuclear complex [Cp2Y（μ-η^1：η^3-OC（SEt）NPh）]2. The structure was characterized by elemental analysis, IR, MS and single-crystal X-ray diffraction analysis. The title compound crystallizes in triclinic, space group P1^- with a = 8.643（3）, b = 10.752（4）, c = 11.161（4）A°, α= 117.840（5）, β = 94.086（5）, γ= 101.008（5）°, V = 884.8（6） A°^3, Z = 1, Mr = 798.66 （C38H40N2O2S2Y2）, λ（MoKα） = 0.710730 .A°, ,μ= 3.417 mm^-1, Dc = 1.499 g/cm^3, F（000） = 408, the final R = 0.0453 and wR = 0.1007 for 3067 unique reflections （Rint = 0.0317） with 2357 observed ones （I 〉 2σ（I））. X-ray analysis reveals an unusual bonding mode of the OC（SEt）NPh ligand and the OCN fragment acts as a both bridging and side-on chelating ligand. Each yttrium atom is coordinated by two η^5-cyclopentadienyl groups, one chelating η^3-OC（SEt）NPh ligand and one bridging O atom from another η^3-OC（SEt）NPh ligand.

关键词： organolanthanide isocyanate insertion structure cyclopentadienyl

Analysis and optimization of thermal management system for cylindrical power battery based on distributed liquid cooling plates

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Science China Technological Sciences 2024年第12期67卷 3695-3706页

作者： ZHAO Yang ZHANG Tao WANG chun TANG YinBo xi Huan National Innovation Platform (Center) for Industry-Education Integration of Energy Storage Technology Xi'an Jiaotong University Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education School of Energy and Power Engineering Xi'an Jiaotong University School of Future Technology Xi'an Jiaotong University Ningbo Deye Energy Storage Technology Co. Ltd.

To ensure the battery works in a suitable temperature range, a new design for distributed liquid cooling plate is proposed, and a battery thermal management system(BTMS) for cylindrical power battery pack based on the proposed cooling plate is also investigated. To verify the accuracy of the battery model and battery pack numerical calculation model used for simulation, an experiment is conducted for the liquid cooling BTMS. The influence of key working parameters, including the cooling water inlet flow, ambient temperature and working conditions, are investigated. The results show that at the discharge rate of 3 C, the best cooling performance can be achieved when the total inlet mass flow rate is 3.2 g/s and the flow distribution is 3:1:1:3. The obtained maximum temperature is 29.6°C and the maximum temperature difference is 2.1°C. When the ambient temperature is in the range of 20°C to 50°C, the proposed BTMS can keep the temperature of battery pack in the proper range. Finally, different inlet flow rates are recommended according to different battery working states.

关键词： lithium battery battery model battery thermal management liquid cooling plate distributed cooling

Theoretical Exploration of Stereochemical Nonrigidity for RfCo（PF3）x（CO）4-x（Rf=CF3, C2F5, C3F7, x=0-4）

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Chemical Research in Chinese Universities 2014年第4期30卷 656-660页

作者： LIU Tingting lu xi ZHANG Mingtao Computational Center for Molecular Science College of Chemistry Nankai University Tianjin 300071 P. R. China Department of Chemical and Materials Engineering University of Alberta Edmonton AB T6G 2V4 Canada

The stereochemical nonrigidity of RfCo（PF3）x（CO）4-x（Rf=CF3,C2F5,C3F7,x=0-4） was studied at the theoretical level of B3LYP/6-31 1＋G^＊ via Gaussian *** intramolecular rearrangements in these penta-coordinated compounds are mainly caused by the vibrations of perfluoroalkyl *** the barriers along the reaction coordinate are less than 66.9 kJ/mol,which indicates that the rearrangements are kinetically favorable and hard to elucidate by ***,ligand PF3 is a ligand similar to CO,the energy difference between the reactant and product is small.

关键词： Density functional theory(DFT) Intramolecular rearrangement Stereochemical nonrigidity Pentacoordination