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The Cauchy problem for non-autonomous nonlinear Schr(o)dinger equations

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Science China Mathematics 2005年第4期48卷 522-538页

作者： Peter y. h. Pang Department of Mathematics

In this paper we study the Cauchy problem for cubic nonlinear Schr(o)dinger equation with space-and time-dependent coefficients on Rm and Tm. By an approximation argument we prove that for suitable initial values, the... 详细信息

关键词： non-autonomous Schr(o)dinger equations, local existence, global existence.

Creep Behavior and Microstructure Evolution of Sand–Cast Mg–4y–2.3Nd–1Gd–0.6Zr Alloy Crept at 523–573 K

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Journal of Materials Science & Technology 2017年第1期33卷 79-89页

作者： y.h.Kang h.yan R.S.Chen The Group of Magnesium Alloys and Their Applications Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China University of the Chinese Academy of Sciences Beijing 100049China

high temperature tensile-creep behavior of Mg-4y-2.3Nd-IGd-O.6Zr （wt%, WE43（T6）） alloy at 523- 573 K was investigated. The creep stress exponent is equal to 4.6, suggesting the underlying dislocation creep mechanism. The activation energy is （199 _＋ 23） kJ/mol, which is higher than that for self- diffusion in Mg and is believed to be associated with precipitates coarsening or cross slip. The creep mechanism is further suggested to be dislocation climb at 523 K, while a cross slip at 573 K is possible. The metastable 13＇ and ~]1 phases in the WE43（T6） alloy were relatively thermal stable at 523 K and could be effective to hinder the dislocation climb, which contributed to its excellent creep resistance. however, at 573 K it readily transforms into equilibrium/3e phase and coarsens within two hours, thereby causing a decrease of creep resistance. In addition, precipitate free zones approximately normal to applied stress direction （directional PFZs） developed during the creep deformation, especially at 573 K. Those zones became preferential sites to nucleate, extend and connect microcracks and cavities, which lead to the intergranular creep fracture. Improving the thermal stability of precipitates or introducing thermally stable fine plate-shaped precipitates on the basal planes of Mg matrix could enhance the high temperature creep resistance.

关键词： WE43 alloy Creep PFZs Precipitate Fracture

A Mathematical Model for the heat Radiation Characteristics of Materials

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Journal of Thermal Science 2004年第1期13卷 75-79页

作者： D. h. Xia y. h. Wu Univ Sci & Technol Beijing Dept Thermal Engn Beijing 100083 Peoples R China

Based on the model of harmonic oscillators, a mathematical model for the heat radiation characteristics of materials such as semiconductors, metals, plasmas and ionic crystals is established in this paper. The main factors affecting the heat radiation characteristics of materials are also analyzed at length. The emissivity is calculated for revealing the mechanism of emitting, absorbing, transmitting and reflecting the heat radiation wave.

关键词： harmonic oscillator mathematical Model heat radiation wave emissivity.

Layered Machinable and Electrically Conductive Ti_2AlC and Ti_3AlC_2 Ceramics:a Review

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Journal of Materials Science & Technology 2010年第5期26卷 385-416页

作者： X.h. Wang y.C. Zhou Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang110016 China

Ti2AlC and Ti3AlC2 are the most light-weight and oxidation resistant layered ternary carbides belonging to the MAX *** review highlights recent achievements on the processing,microstructure,physical,mechanical and chemical properties of these two machinable and electrically conductive ***2AlC and Ti3AlC2 display superior properties such as fracture toughness,electrical and thermal conductivities,and oxidation resistance over their binary *** paper provides a comprehensive overview of the processing-microstructure-property correlations of these two *** fields of applications for Ti2AlC and Ti3AlC2 are *** addition,we point out methods for further improving their properties in some specific applications through appropriate structural design and modification.

关键词： MAX phases Ti2AlC Ti3AlC2 Machinable ceramics

hyBRID LINEAR AND QUADRATIC FINITE ELEMENT MODELS FOR 3D hELMhOLTZ PROBLEMS

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Acta Mechanica Solida Sinica 2013年第6期26卷 603-618页

作者： Q.h.Zhang K.y.Sze Guangdong Province Key Laboratory of Computational Science Sun Yat-Sen University Department of Mechanical Engineering The University of Hong KongPokfulam

In this paper, linear and quadratic finite element models are devised for the three- dimensional helmholtz problem by using a hybrid variational functional. In each element, contin- uous and discontinuous helmholtz fields are defined with their equality enforced over the element boundary in a weak sense. The continuous field is based on the C° nodal interpolation and the discontinuous field can be condensed before assemblage. hence, the element can readily be in- corporated seamlessly into the standard finite element program framework. Discontinuous fields constructed by the plane-wave, Bessel and singular spherical-wave solutions are attempted. Nu- merical tests demonstrate that some of the element models are consistently and considerably more accurate than their conventional counterparts.

关键词： finite element hybrid helmholtz Bessel plane-wave spherical-wave radial basis function

Current Status in Layered Ternary Carbide Ti_3SiC_2,a Review

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Journal of Materials Science & Technology 2009年第1期25卷 1-38页

作者： h.B. Zhang y.W. Bao y. C. Zhou Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

This article provides a review of current research activities that concentrate on Ti3SiC2. We begin with an overview of the crystal and electronic structures, which are the basis to understand this material. Followings are the synthetic strategies that have been exploited to achieve, and the formation mechanism of Ti3SiC2. Then we devote much attentions to the mechanical properties and oxidation/hot corrosion behaviors of Ti3SiC2 as well as some advances achieved recently. At the end of this paper, we elaborate on some new discoveries in the Ti3SiC2 system, and also give a brief discussion focused on the ＂microstructure -property＂ relationship.

关键词： Layered ternary ceramics Ti3SiC2 Mechanical properties Oxidation

Flux focusing with a superconducting nanoneedle for scanning SQUID susceptometry

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Microsystems & Nanoengineering 2023年第3期9卷 411-417页

作者： B.K.Xiang S.y.Wang y.F.Wang J.J.Zhu h.T.Xu y.h.Wang State Key Laboratory of Surface Physics and Department of Physics FudanUniversity200433 ShanghaiChina Shanghai Research Center for Quantum Sciences 201315 ShanghaiChina

A nanofabricated superconducting quantum interference device(nano-SQUID)is a direct and sensitive flux probe used for magnetic imaging of quantum materials and mesoscopic *** to the functionalities of superconductive integrated circuits,nano-SQUIDs fabricated on chips are particularly versatile,but their spatial resolution has been limited by their planar ***,we use femtosecond laser 3-dimensional(3D)lithography to print a needle onto a nano-SQUID susceptometer to overcome the limits of the planar *** nanoneedle coated with a superconducting shell focused the flux from both the field coil and the *** performed scanning imaging with such a needle-on-SQUID(NoS)device on superconducting test patterns with topographic *** NoS showed improved spatial resolution in both magnetometry and susceptometry relative to the planarized *** work serves as a proof-of-principle for integration and inductive coupling between superconducting 3D nanostructures and on-chip Josephson nanodevices.

关键词： lithography SQUID needle

Reactive destabilization and bidirectional catalyzation for reversible hydrogen storage of LiBh_(4) by novel waxberry-like nano-additive assembled from ultrafine Fe_(3)O_(4) particles

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Journal of Materials Science & Technology 2024年第6期173卷 63-71页

作者： S.Wang M.h.Wu y.y.Zhu Z.L.Li y.X.yang y.Z.Li h.F.Liu M.X.Gao Department of Material Science Shenzhen MSU-BIT UniversityShenzhen 518172China State Key Laboratory of Silicon and Advanced Semiconductor Materials&School of Materials Science and Engineering Zhejiang UniversityHangzhou 310027China Institute of Resources Utilization and Rare Earth Development State Key Laboratory of Rare Metals Separation and Comprehensive UtilizationGuangdong Provincial Key Laboratory of Rare Earth Development and ApplicationGuangdong Academy of SciencesGuangzhou 510650China Institute of Science and Technology for New Energy Xi’an Technological UniversityXi’an 710021China National Supercomputing Center in Shenzhen Shenzhen 518055China

LiBh_(4) containing 18.5 wt.%h_(2) is an attractive high-capacity hydrogen storage material,however,it suffers from high operation temperature and poor ***,a novel and low-cost bifunctional additive,waxberry-like Fe_(3)O_(4) secondary nanospheres assembled from ultrafine primary Fe_(3)O_(4) nanoparticles,is synthesized,which exhibits significant destabilization and bidirectional catalyzation towards(de)hydrogenation of LiBh_(4).With an optimized addition of 30 wt.% waxberry-like Fe_(3)O_(4),the system initiated dehydrogenation below 100℃ and released a total of 8.1 wt.%h_(2) to 400℃.After 10 cycles,a capacity retention of 70% was achieved,greatly superior to previously reported oxides-modified *** destabilizing and catalyzing mechanisms of waxberry-like Fe_(3)O_(4) on LiBh_(4) were systematically analyzed by phase and microstructural evolutions during dehydrogenation and hydrogenation cycling as well as density functional theory(DFT)*** present work provides new insights in developing advanced nano-additives with unique structural and multifunctional designs towards LiBh4 hydrogen storage.

关键词： LiBh_(4) hydrogen storage Waxberry-like Fe_(3)O_(4) Destabilization Catalysis

Mechanosynthesis and mechanochemical treatment of bismuth-doped vanadium phosphorus oxide catalysts for the partial oxidation of n-butane to maleic anhydride

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Journal of Natural Gas Chemistry 2008年第3期17卷 232-237页

作者： y. h. Taufiq-yap y.C. Wong y. Kamiya W.J. Tang Putra Center for Catalysis Science and Technology Department of Chemistry Faculty of Science Universiti Putra Malaysia 43400 UPM Serdang Selangor Darul Ehsan Malaysia Graduate School of Environmental Science Hokkaido Universit3 Sapporo 060-0810 Japan

Three Bi-doped vanadyl pyrophosphate catalysts were prepared via dihydrate route （VPD method）, which consisted of different preparation methods including mechanosynthesis, mechanochemical treatment, and the conventional reflux method. The catalysts produced by the above three methods were characterized by x-ray diffraction （XRD）, scanning electron microscopy （SEM）, and temperature programmed reduction （TPR）. Catalytic evaluation for the partial oxidation of n-butane to maleic anhydride （MA） was also carried out. The XRD patterns of all the Bi-doped catalysts showed the main peaks of pyrophosphate phase. Lower intensity peaks were observed for the mechanochemically treated Bi-doped catalyst （VPDBiMill） with two additional small peaks corresponding to the presence of a small amount of V5＋ phase. The TPR profiles showed that the highest amount of active oxygen species, i.e, V4＋–O- pair, responsible for n-butane activation, was removed from VPDBiMill. Furthermore, from the catalytic test results, the graph of selectivity to MA as a function of the conversion of n-butane demonstrated that VPDBiMill was the most selective catalyst. This suggests that the mechanochemical treatment of vanadium phosphate catalyst （VPDBiMill） is a potential method to improve the catalytic properties for the partial oxidation of n-butane to maleic anhydride.

关键词： mechanosynthesis mechanochemical treatment bismuth vanadyl pyrophosphate