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Chinese Science Bulletin 1997年第18期42卷 1517-1520页

作者： Liu, j xu, Y Department of Applied Mathematics Southwest Jiaotong University Chengdu China

IN order to research the logical system whose propositional value is given in a lattice from

关键词： lattice implication algebra filter generated filter.

Mechanical Properties and Defective Effects of 316LN Stainless Steel by First-Principles Simulations

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journal of Materials Science & Technology 2011年第11期27卷 1029-1033页

作者： X.Q. Li j.j. Zhao j.C. xu X. Liu Key Laboratory of Materials Modification by Laser Ion and Electron Beams Ministry of Education Dalian University of Technology Dalian 116024 China College of Advanced Science and Technology Dalian University of Technology Dalian 116024 China School of Chemical Engineering Dalian University of Technology Dalian 116024 China

In current International Thermonuclear Experimental Reactor （ITER） design, the 316LN austenitic stainless steel （316LN SS） is used for first-wall/blanket structures. Thus, it is necessary to study the fundamental mechanical properties and irradiation effect of 316LN SS. A random solid solution model of Fe-Cr-Ni-Mn- Mo-Si alloy is used for describing 310LN S$. Using first-principles approaches, the elastic constants and ideal strength of the alloy were calculated. Such alloy exhibits good ductile behavior according to the theoretical values of Cauchy pressure and ratio of bulk modulus and shear modulus. Within the 256-atom supercell, inclusion of single vacancy defect further enhances the ductility of the alloy, and the existence of interstitial （Fe, H, He） atoms enhances the Young＇s modulus.

关键词： Stainless steel Mechanical properties Vacancy Interstitial

Synthesis of Chitosan Quaternary Ammonium Salts

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Chinese Chemical Letters 2001年第12期12卷 1081-1084页

作者： xu, WL Wu, j Fu, CL Zhejiang Univ Dept Chem Hua Jia Chi Sect Hangzhou 310029 Peoples R China

A series of N-alkyl or N-aryl chitosan quaternary ammonium salts were prepared via Schiffs base intermediates. Quaternization of N-substituted chitosan derivatives was carried out using methyl iodide to produce water-soluble cationic chitosan quaternary ammonium salt. The products were characterized by IR, (HNMR)-H-1 and elemental analysis. The degree of substitution of chitosan quaternary ammonium salt was calculated by elemental analysis.

关键词： synthesis quaternization chitosan quaternary ammonium salts

Statistical moment-based structural damage detection method in time domain

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Earthquake Engineering and Engineering Vibration 2013年第1期12卷 13-23页

作者： j.Zhang Y.L.xu j.Li Y.Xia j.C.Li Department of Civil and Environmental Engineering The Hong Kong Polytechnic University Department of Building Engineering Tongji University Faculty of Engineering University of Technology Sydney

A novel structural damage detection method with a new damage index,i.e.,the statistical moment-based damage detection（SMBDD） method in the frequency domain,has been recently *** aim of this study is to extend the SMBDD method in the frequency domain to the time domain for building structures subjected to non-Gaussian and non-stationary *** applicability and effectiveness of the SMBDD method in the time domainis verified both numerically and *** buildings with various damage scenarios are first numerically investigated in the time domain taking into account the effect of measurement *** applicability of the proposed method in the time domain to building structures subjected to non-Gaussian and non-stationary excitations is then experimentally investigated through a series of shaking table tests,in which two three-story shear building models with four damage scenarios *** identified damage locations and severities are then compared with the preset *** comparative results are found to be satisfactory,and the SMBDD method is shown to be feasible and effective for building structures subjected to non-Gaussian and non-stationary excitations.

关键词： damage detection statistical moment time domain non-Gaussian non-stationary experimental investigation

A BIE-BASED DtN-FEM FOR FLUID-SOLID INTERACTION PROBLEMS

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journal of Computational Mathematics 2018年第1期36卷 47-69页

作者： Tao Yin Andreas Rathsfeld j Liwei xu College of Mathematics and Statistics Chongqing University Chongqing 401331 China Weierstrass Institute Mohrenstr. 39 10117 Berlin Germany

In this paper, we are concerned with the coupling of finite element methods and bound- ary integral equation methods solving the classical fluid-solid interaction problem in two dimensions. The original transmission problem is reduced to an equivalent nonlocal bound- ary value problem via introducing a Dirichlet-to-Neumann mapping by the direct boundary integral equation method. We show the existence and uniqueness of the solution for the corresponding variational equation. Numerical results based on the finite element method coupled with the standard Galerkin boundary element method, the fast multipole method and the NystrSm method for approximating the DtN mapping are provided to illustrate the efficiency and accuracy of the numerical schemes.

关键词： Fluid-solid interaction problem Dirichlet-to-Neumann mapping Finite element method Fast multipole method NystrSm method.

Aero-Acoustics of Modern Transonic Fans—— Fan Noise Reduction from Its Sources

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journal of Thermal Science 2003年第2期12卷 104-113页

作者： L.xu j.D.Denton Whittle Laboratory University of CambridgeUKWhittle LaboratoryUniversity of CambridgeUK

The noise of aerodynamics nature from modern transonic fan is examined from its sources with the perspective of noise reduction through aero-acoustics design using advanced Computational Fluid Dynamics (CFD) tools. In particular the problems associated with the forward propagating noise in the front is addressed. It is identified that the shock wave spillage from the leading edge near the fan tip is the main source of the tone noise. Two different approaches have been studied to reduce the forward arc tone noise and two state-of-art transonic fans are designed using the strategies developed. The following rig tests show that while the fans exhibit other noise problems, the primary goals of noise reduction have been achieved through both fans and the novel noise reduction concept vindicated.

关键词： transonic fan aero-acoustics noise reduction.

Approach for electrodynamic force for compensation in low voltage circuit breaker WP 630-1.2 type

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journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第3期8卷 393-396页

作者： LU Na xu L.j Miedzifiski B Automation School Beijing University of Posts and Telecommunications Beijing 100876 China Electrical Power Engineering Institute Wroclaw University of Technology Wroclaw Poland

Undesirable repulsive force between contact members due to both a current path shrink near a real contact area and/or so-called pinch effect is particularly onerous for power switch applications, and results in either contact floating or bouncing which are associated with an electric arc following contact welding. This problem is of great importance for any circuit breaker especially for compact low voltage vacuum circuit breakers. To avoid contact floating at closure and during any inrush current under short circuit conditions, the electrodynamic repulsive force can be employed successfully if we use a special compensation system flexibly combined with the contact itself. However to select and design the compensation system properly, its efficiency has to be known. This paper presents an approach to obtain the electrodynamic force value depending on different shaped (rectangular, square, circle and arch) copper plates used in the compensator by using ANSYS for current values 40 kA RMS. Curve-fitting was done according to the calculating results, the optimization designing of compensation unit is based on them.

关键词： Compensation. Electrodynamic force. FEM (Finite Element Method)

Fluctuation theorem for entropy production at strong coupling

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Chinese Physics B 2020年第1期29卷 175-180页

作者： Y Y xu j Liu M Feng Faculty of Science Kunming University of Science and TechnologyKunming 650500China Faculty of Mechanical and Electrical Engineering Kunming University of Science and TechnologyKunming 650500China State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and MathematicsChinese Academy of SciencesWuhan 430071China School of Physics and Microelectronics Zhengzhou UniversityZhengzhou 450001China

Fluctuation theorems have been applied successfully to any system away from thermal equilibrium,which are helpful for understanding the thermodynamic state *** investigate fluctuation theorems for strong coupling between a system and its reservoir,by path-dependent definition of work and heat satisfying the first law of *** present the fluctuation theorems for two kinds of entropy *** is the informational entropy production,which is always non-negative and can be employed in either strong or weak coupling *** other is the thermodynamic entropy production,which differs from the informational entropy production at strong coupling by the effects regarding the *** find that,it is the negative work on the reservoir,rather than the nonequilibrium of the thermal reservoir,which invalidates the thermodynamic entropy production at strong *** results indicate that the effects from the reservoir are essential to understanding thermodynamic processes at strong coupling.

关键词： fluctuation theorem entropy production strong coupling

Non-uniqueness of critical solid fraction considering boundary conditions and strain-rate effects

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Particuology 2021年第1期19卷 37-49页

作者： Mingze xu Zixin Zhang Xin Huang Kevin j.Hanley Department of Geotechnical Engineering Tongji UniversityShanghai 200092China State Key Laboratory of Geotechnical Engineering Ministry of EducationTongji UniversityShanghai 200092China School of Engineering Institute for Infrastructure and EnvironmentThe University of EdinburghEdinburgh EH93JLUnited Kingdom

The critical solid fraction(ϕj),which marks the transition between the solid and liquid phases in the jamming diagram,is influenced by several *** this study,the dependency ofϕj on strain rate and boundary conditions is examined through discrete element method simulations considering a frictionless polydisperse granular *** approaches are used to determineϕ*** observed boundary effect is due to the nonuniform solid fraction distribution induced by the clustering of particles close to rigid-wall boundaries at high compression *** solid fraction distribution within the sample in the rigid-wall simulations approaches that in the periodic-boundary simulations as the compression rate *** increasing compression rate,the major force transmission network contains fewer mechanically stable particles and a less stable force transmission *** causes jamming of the granular assembly at a lower solid *** force transmission networks,however,are fragile and disintegrate quickly upon relaxation.

关键词： jamming transition jamming density Strain rate dependency Boundary effects

Microwave sintered porous CoCrFeNiMo high entropy alloy as an efficient electrocatalyst for alkaline oxygen evolution reaction

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journal of Materials Science & Technology 2021年第20期79卷 171-177页

作者： j.Tang j.L.xu Z.G.Ye X.B.Li j.M.Luo School of Materials Science and Engineering Nanchang Hangkong UniversityNanchang330063China

Developing efficient,stable and economical electrocatalyst for oxygen evolution reaction(OER)is a significant pathway to produce clean energy from water ***,the promising and highly efficient porous CoCrFeNiMo high entropy alloys(HEAs)were prepared by microwave sintering using Mg space *** to unique properties of high entropy alloys and abundant active surface area,the porous CoCrFeNiMo-20 Mg exhibits excellent catalytic performance and prominent electrochemical stability with a low overpotential of 220 mV to reach current density of 10 mA cm^(-2),a small Tafel slope of 59.0 mV dec^(-1) and long-term durability for 24 h in 1.0 M *** results of microstructure and element states indicate that crystal defects,porous structure and villous hydroxides are the reasons for high OER performance of the *** work not only provides a new way to prepare electrocatalysts,but also proves the important application of high entropy alloys in functional materials.

关键词： CoCrFeNiMo High entropy alloys Electrocatalysts Oxygen evolution reaction Microwave sintering Mg space holder