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Correlating dynamic relaxation and viscoelasticity in metallic glasses

Science china(Physics,Mechanics & Astronomy) 2024年第5期67卷 81-90页

作者： GuangHui Xing Qi Hao fan {1. {2.-Jiang Wang Yong Yang Hidemi Kato Eloi Pineda Si Lan JiChao Qiao school of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi'an 710072China State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China school of Engineering Science University of Chinese Academy of SciencesBeijing 100049China Department of Mechanical Engineering College of EngineeringCity University of Hong KongHong Kong 999077China Department of Materials Science and Engineering College of EngineeringCity University of Hong KongHong Kong 999077China Institute for Materials Research Tohoku UniversitySendai 980-8577Japan Department of Physics Institute of Energy TechnologiesUniversitat Politècnica de CatalunyaBarceona 9Spain school of Material Science and Engineering Herbert Gleiter Institute of NanoscienceNanjing University of Science and Technology.Nanjing 210094China State Key Laboratory of Clean and Efficient Turbomachinery Power Equipment Northwestern Polytechnical UniversityXi'an 710072China

Relaxation dynamics,essential for the structural evolution of non-equilibrium systems like glassy materials,remain ***,we explore relaxation dynamics and viscoelastic properties in three types of metallic glasses with distinctβrelaxation *** systems with significantβrelaxation,stress relaxation and creep experiments reveal a transition from two-step to one-step relaxation with rising ***,such a phenomenon is absent in systems with weakerβ*** model the two-step relaxation process using a double Kohlrausch-Williams-Watts equation,and the obtained relaxation times elegantly adhere to the Arrhenius *** combining fitted activation energies with theoretical analysis,we conclusively attribute these relaxation processes toβrelaxation andαrelaxation,***,we analyze the relaxation time spectra of two processes and establish a comprehensive picture linking dynamic relaxation with *** study provides new strategies for probing the complex relaxation behaviors of glasses from the perspective of viscoelasticity.

关键词： creep relaxation glasses

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Airflow Analytical Toolkit(AAT):A MATLAB-based analyzer for holistic studies on the dynamic characteristics of airflows

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Building Simulation 2024年第7期17卷 1137-1159页

作者： Zuoyu Xie Junhui fan Bin Cao Yingxin {1. Department of Building Science School of ArchitectureTsinghua UniversityBeijingChina Key Laboratory of Eco Planning&Green Building Ministry of Education(Tsinghua University)BeijingChina

The dynamic characteristics of different airflows on micro-scales have been explored from many perspectives since the late *** the one hand,most analytical tools and research subjects in previous contributions vary significantly:some only focus on fluctuant velocity features,while others pay attention to directional *** the other hand,despite the wide variety of existing analytical methods,they are not systematically classified and *** paper aims to establish a system including state-of-the-art tools for airflow analysis and to further design a holistic toolkit named Airflow Analytical Toolkit(AAT).The AAT contains two tools,responsible for analyzing the velocity and direction characteristics of airflows,each of which is integrated with multiple analytical *** assess the performance of the developed toolkit,we further take typical natural and mechanical winds as cases to show its excellent analytical *** the help of this toolkit,the great differences in velocity and directional characteristics among different airflows are *** comparative results reveal that not only is the velocity of natural wind more fluctuating than that of mechanical wind,but its incoming flow direction is also more *** AAT,serving as a powerful and user-friendly instrument,will hopefully offer great convenience in data analysis and guidance for a deeper understanding of the dynamic characteristics of airflows,and further remedy the gap in airflow analytical tools.

关键词： airflow analysis dynamic characteristic wind velocity wind direction thermal comfort wind comfort

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Evaluation of transmission risk of respiratory particles under different ventilation strategies in an elevator

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Building Simulation 2024年第5期17卷 771-784页

作者： Liangyu zhu Xian Li Bujin Feng {1. Liu school of Civil Engineering and Architecture Linyi UniversityLinyi276000China College of Agriculture Shandong Agricultural UniversityTaian271018China school of Environment and Architecture University of Shanghai for Science and TechnologyShanghai200093China

People in elevators are at risk of respiratory infection because the elevator cabin is crowded and has poor *** exhaled particles may be inhaled by the susceptible person,deposited on the surface and suspended in the elevator,which can result in direct and indirect ***,whether the air vent designs adopted in the elevator can effectively reduce the transmission risk of respiratory particles remains *** this study,the dispersion of particles under four common ventilation strategies used in the commercial elevator was investigated by proven computational fluid dynamics(CFD)*** flow field was simulated with the RNG κ-ξ turbulence model and the Lagrangian method was adopted to track particle *** effects of air vent layout and airflow rate on particle transmission were *** found that more than 50% of exhaled particles(average value)were suspended in the cabin and difficult to discharge under the investigated ventilation *** deposited fraction of particles on the susceptible person reached up to 39.1.% for infiltration ventilation,which led to a high risk of contact *** the ventilation rate could not significantly reduce the inhalation proportion of particles due to the poor airflow distribution inside the elevator.A more proper ventilation strategy should be explored for the elevator to control transmission risk.

关键词： particle dispersion transmission risk elevator ventilation strategy computational fluid dynamics(CFD)

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Study on the preparation and fretting behavior of bonded oriented MoS_(2.solid lubricant coating

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Friction 2024年第11期12卷 2505-2518页

作者： Liangliang XIONG Mengxue WU Xiaoqiang fan Minhao {1. Key Laboratory of Advanced Technologies of Materials(Ministry of Education) School of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China Tribology Research Institute School of Mechanical EngineeringSouthwest Jiaotong UniversityChengdu 610031China

The bonded MoS_(2.solid lubricant coating is an effective measure to mitigate the fretting wear of AISI 1.45 *** this work,the amino functionalized MoS_(2.was protonated with acetic acid to make the MoS_(2.positively *** directional arrangement of protonated MoS2.in the coating was achieved by electrophoretic deposition under the electric field *** bonded directionally aligned MoS_(2.solid lubricant coating showed high adaptability to various loads and excellent lubrication performance under all three working *** a load of 1. N,the friction coefficient and wear volume of the coating with 5 wt%protonated MoS_(2.decreased by 2..0%and 37.2.compared to the pure epoxy coating,respectively,and by 0.07%and 1..8%than the randomly arranged MoS_(2.sample,*** remarkable lubricating properties of MoS_(2.with directional alignment were attributed to its effective load-bearing and mechanical support,barrier effect on longitudinal extension of cracks,and the formation of a continuous and uniform transfer film.

关键词： bonded solid lubricant coating MoS_(2. fretting oriented alignment

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Effect of Tin on the Reaction Synthesis of Ternary Carbide Ti_3AlC_2

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Journal of wuhan university of Technology(Materials Science) 2009年第2期24卷 283-286页

作者：周卫兵 school of Materials Science and Engineering Wuhan University of Technology

The effect of tin on synthesis of Ti3AlC2.by spark plasma sintering （SPS） from TiC/Ti/Al powders was investigated. X-ray diffraction （XRD） and scanning electron microscopy （SEM） were used for phase identification and microstructure evaluation. The experimental results show that addition of tin can considerably accelerate the synthesis reaction of Ti3AlC2.and fully dense, essentially single-phase polycrystalline Ti3AlC2.could be successfully obtained by sintering 2.iC/1.i/1.l/0.2.n powders at 1.0}0-1.0}0 ℃ under a pressure of 30 MPa. SEM images show that Ti3AlC2.samples in about 2.5 μm thick and 1.-2.μm long platelets can be obtained. The fracture toughness and flexural strength of Ti3AlC2.were 6.5±0.2.MPa·m^1.2.and 560±1. MPa, respectively.

关键词： titanium aluminum carbide spark sintering technique synthesis

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Research on theory and key technology of trusted computing platform security testing and evaluation

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Science china(Information Sciences) 2010年第3期53卷 434-453页

作者： ZHANG HuanGuo1,2. YAN Fei1,2. FU JianMing1,2. XU MingDi1,2. YANG Yang1,2. HE fan1,2.& ZHAN Jing1,2.1school of Computer,{2., wuhan 430072. china 2.ey Laboratory of Aerospace Information Security and Trusted Computing, Ministry of Education, wuhan 430072. china 1. school of Computer Wuhan University Wuhan 430072 China2. Key Laboratory of Aerospace Information Security and Trusted Computing Ministry of Education Wuhan 430072 China

Trusted computing has become a new trend in the area of international information security, and the products of trusted computing platform begin to be used in application. Users will not use the products of information security, unless it goes through the testing and evaluation. Here we concentrate on the testing and evaluation problem of trusted computing platform, begin with constructing proper formalization model of trusted computing platform for testing, and establish a mathematical chain of trust model based on SPA. Moreover, we give a verification method of composite characteristics and find the potential factors threatening the trusted system in the process of remote attestation through analysis. For trusted software stack, we study the problem of automatic generation of test case and propose an improved method of generating the random test case, to raise the quality of test case. Finally, we give a prototype system of trusted computing platform and the actual test data related. The result demonstrates that there exist some flaws in the architecture of the present TCG computing platform. At the same time, some flaws are found in the products of existing trusted computing platform, thus a basis is laid for the improvement and development of trusted platform technology and its products.

关键词： information security trusted computing trusted computing platform testing and evaluation

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Checking for normality in linear mixed models

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Science china {1. 2012年第4期55卷 787-804页

作者： WU ping 1,,zhu LiXing 2.3 & {2.G yun 4 1 school of Finance and statistics,East china Normal university,Shanghai 2.02.1,china 2.school of statistics and mathematics,yunnan university of Finance and Economics,yunnan 6502.1,china 3 The Department of mathematics,Hong Kong Baptist university,Hong Kong 999077,china 4 mathematics and Science College,Shanghai Normal university,Shanghai 2.02.4,china 1. school of Finance and {1. East China Normal University Shanghai 200241 China2. School of Statistics and Mathematics Yunnan University of Finance and Economics Yunnan 650221 China3. The Department of Mathematics Hong Kong Baptist University Hong Kong 999077 China4. Mathematics and Science College Shanghai Normal University Shanghai 200234 China

Linear mixed models are popularly used to fit continuous longitudinal data, and the random effects are commonly assumed to have normal distribution. However, this assumption needs to be tested so that further analysis can be proceeded well. In this paper, we consider the Baringhaus-Henze-Epps-Pulley （BHEP） tests, which are based on an empirical characteristic function. Differing from their case, we consider the normality checking for the random effects which are unobservable and the test should be based on their predictors. The test is consistent against global alternatives, and is sensitive to the local alternatives converging to the null at a certain rate arbitrarily close to 1.V~ where n is sample size. ^-hlrthermore, to overcome the problem that the limiting null distribution of the test is not tractable, we suggest a new method： use a conditional Monte Carlo test （CMCT） to approximate the null distribution, and then to simulate p-values. The test is compared with existing methods, the power is examined, and several examples are applied to illustrate the usefulness of our test in the analysis of longitudinal data.

关键词： linear mixed models estimated best linear unbiased predictors BHEP tests conditional MonteCarlo test

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Grain refinement of Mg-Ca alloys by native MgO particles

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Journal of Magnesium and Alloys 2024年第3期12卷 980-996页

作者： Shihao Wang yun Wang Quentin M.Ramasse Zhongyun {2. Super STEM Laboratory SciTech Daresbury CampusDaresbury WA44ADUK school of Chemical and Process Engineering University of LeedsLeeds LS29JTUK BCAST Brunel University LondonUxbridgeMiddlesex UB83PHUK

In Mg-Ca alloys the grain refining mechanism,in particular regarding the role of nucleant substrates,remains the object of *** native MgO is being recognised as a nucleating substrate accounting for grain refinement of Mg alloys,the possible interactions of MgO with alloying elements that may alter the nucleation potency have not been elucidated ***,we design casting experiments of Mg-xCa alloys varied qualitatively in number density of native MgO,which are then comprehensively studied by advanced electron *** results show that grain refinement is enhanced as the particle number density of MgO *** native MgO particles are modified by interfacial layers due to the co-segregation of Ca and N solute atoms at the MgO/Mg *** aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy,we reveal the nature of these Ca/N interfacial layers at the atomic *** of the crystallographic termination of MgO,Ca and N co-segregate at the MgO/Mg interface and occupy Mg and O sites,respectively,forming an interfacial structure of a few atomic *** interfacial structure is slightly expanded,less ordered and defective compared to the MgO matrix due to compositional deviations,whereby the MgO substrate is altered as a poorer template to nucleate Mg *** solidification in a TP-1.mould,the impotent MgO particles account for the grain refining mechanism,where they are suggested to participate into nucleation and grain initiation processes in an explosive *** work not only reveals the atomic engineering of a substrate through interfacial segregation but also demonstrates the effectiveness of a strategy whereby native MgO particles can be harnessed for grain refinement in Mg-Ca alloys.

关键词： Mg-Ca alloy Grain refinement MgO Interfacial segregation STEM/EELS Solidification.

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Dynamic Allocation Strategy Based on Pre-allocation and Agent to Implement Ada95's Distributed Computing

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wuhan {1. Journal of Natural Sciences 2003年第4A期8卷 1061-1064页

作者： zhu Fu-xi, Fu Jian-ming,Wu Chan-le, Cao Zheng {1. of Computer,{2. university,{2. 430072.hubei, china wuhan {1. School of Computer Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***)

This paper discusses the model of how the Agent is applied to implement distributed computing of Ada95 and presents a dynamic allocation strategy for distributed computing that based on pre-allocationand Agent. The ... 详细信息

关键词： distributed computing Ada95 Agent equilibrium allocation

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Dynamic Mechanical and Thermal Properties of Cross-linked Polystyrene/Glass Fiber Composites

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Journal of wuhan university of Technology(Materials Science) 2010年第5期25卷 780-784页

作者：朱泉峣陈文 school of Materials Science and Engineering Wuhan University of Technology State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology

Cross-linked polystyrene/glass fiber composites were fabricated using cross-linked polystyrene （CLPS） as matrix and E-glass fiber as the reinforcement. Surfaces of E-glass fibers were modified by vinyl triethoxysilane （VTES）, vinyl trimethoxysilane （VTMS） and γ-methacryloylpropyl trimethoxysilane （MPS）. The treated glass fibers were analyzed by fourier transform infrared spectroscopy （FTIR）. Dynamic mechanical thermal analysis （DMTA） and thermo-gravimetric analysis （TGA） were employed to investigate the effect of glass fibers surface modification on viscoelastic behavior and thermal properties. The morphology of fracture surfaces of various composites was observed by scanning electron microscopy （SEM）. The results revealed that these coupling agents were connected to the surfaces of the fibers by chemical bonding. Dynamic mechanical properties as well as thermal stability of the composites were improved considerablely, but to varying degrees depending on the fiber modification. The diversities of improvement of properties were attributed to the different interfacial adhesion between CLPS matrix and the glass fibers.

关键词： polymer-matrix composite cross-linked polystyrene (CLPS) fiber/matrix bond dynamic mechanical thermal analysis.

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