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Rh single atom catalyst for direct conversion of methane to oxygenates

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Science China Materials 2018年第5期61卷 758-760页

作者： jian lin Xiaodong Wang State Key Laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences

Along with the fast development of economy and growthof world＇s population, the demand for energy is sig-nificantly enhanced. The conventional petroleum andcoal resources are unrenewable and bring about severepollution to the environment. In the past decade, thetechnological advances in drilling and exploitation lead toa significant increase in the production capacity of shalegas worldwide.

关键词：中国科学材料科学

Scalability Analysis of Request Scheduling in Cloud Computing

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Tsinghua Science and Technology 2019年第3期24卷 249-261页

作者： chao Xue Chuang lin Jie Hu Tsinghua National Laboratory for Information Science and Technology (TNList) & Department of Computer Science and Technology Tsinghua University

Rapid advancement of distributed computing systems enables complex services in remote computing clusters. Massive applications with large-scale and disparate characteristics also create high requirements for computing systems. Cloud computing provides a series of novel approaches to meet new trends and ***, some scalability issues have to be addressed in the request scheduling process and few studies have been conducted to solve these problems. Thus, this study investigates the scalability of the request scheduling process in cloud computing. We provide a theoretical definition of the scalability of this process. By modeling the scheduling server as a stochastic preemptive priority queue, we conduct a comprehensive theoretical and numerical analysis of the scalability metric under different structures and various environment configurations. The comparison and conclusion are expected to shed light on the future design and deployment of the request scheduling process in cloud computing.

关键词： cloud computing request scheduling scalability model evaluation

TDDFT Studies of Electronic Structure and First Hyperpolarizability of Tetra-nuclear Cubane-like Transition Metal Clusters

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Chinese Chemical Letters 2002年第12期13卷 1205-1208页

作者： Rong jian SA Ke Chen WU Ping LIU Chen Sheng lin chao Yong MANG State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002 The Graduate school of the Chinese Academy of Sciences Beijing 100036

The TDDFT method is first applied in a series of tetra-nuclear transition metal clusters studies for nonlinear optical properties. The results indicate that the charge transfer inside the metal core [MCu3X4] (M=W, Mo; X=S, O, Cl, Se, Br) makes contribution to the optical nonlinearity. It is possible to enhance the hyperpolarizability by substituting the ligands of the clusters.

关键词： Nonlinear optical properties transition metal clusters TD- DFT method.

Support vector classification algorithm based on variable parameter linear programming

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Journal of Systems Engineering and Electronics 2007年第2期18卷 355-359页

作者： Xiao jianhua lin jian Systems Science and Technology Inst. Wuyi Univ. Jiangmen 529020 P. R. China School of Economy and Management Beijing Univ. of Aeronautics and Astronautics Beijing 100083 P. R. China

To solve the problems of SVM in dealing with large sample size and asymmetric distributed samples, a support vector classification algorithm based on variable parameter linear programming is proposed. In the proposed algorithm, linear programming is employed to solve the optimization problem of classification to decrease the computation time and to reduce its complexity when compared with the original model. The adjusted punishment parameter greatly reduced the classification error resulting from asymmetric distributed samples and the detailed procedure of the proposed algorithm is given. An experiment is conducted to verify whether the proposed algorithm is suitable for asymmetric distributed samples.

关键词： Support vector machine linear programming Classification Variable parameter.

On the use of the discontinuous Galerkin method for numerical simulation of two-dimensional compressible turbulence with shocks

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Science China(Physics,Mechanics & Astronomy) 2014年第9期57卷 1758-1770页

作者： YU jian YAN chao jianG ZhenHua School of Aeronautic Science and Engineering Beijing University of Aeronautics and Astronautics

In this paper,the discontinuous Galerkin(DG)method combined with localized artificial diffusivity is investigated in the context of numerical simulation of broadband compressible turbulent flows with shocks for under-resolved ***,the spectral property of the DG method is analyzed using the approximate dispersion relation(ADR)method and compared with typical finite difference methods,which reveals quantitatively that significantly less grid points can be used with DG for comparable numerical *** several typical test cases relevant to problems of compressible turbulence are simulated,including one-dimensional shock/entropy wave interaction,two-dimensional decaying isotropic turbulence,and two-dimensional temporal mixing *** results indicate that higher numerical accuracy can be achieved on the same number of degrees of freedom with DG than high order finite difference ***,shocks are also well captured using the localized artificial diffusivity *** results in this work can provide useful guidance for further applications of DG to direct and large eddy simulation of compressible turbulent flows.

关键词： discontinuous Galerkin compressible turbulence shock capturing artificial diffusivity

Carbothermal reduction characteristics of oxidized Mn ore through conventional heating and microwave heating

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International Journal of Minerals,Metallurgy and Materials 2021年第2期28卷 221-230页

作者： Yang He jian Liu jian-hua Liu Chun-lin Chen Chang-lin Zhuang Institute of Engineering Technology University of Science and Technology BeijingBeijing 100083China Commonwealth Scientific and Industrial Research Organisation Melbourne 3168Australia Dongbei Special Steel Group Co. Ltd.Dalian 116105China College of Materials and Metallurgy Guizhou UniversityGuiyang 550025China

For the purpose of exploring a potential process to produce FeMn,the effects of microwave heating on the carbothermal reduction characteristics of oxidized Mn ore was *** microwave heating curve of the mixture of oxidized Mn ore and coke was analyzed in association with the characterization of dielectric *** comparative experiments were conducted on the carbothermal reductions through conventional and microwave heatings at temperatures ranging from 973 to 1373 *** thermogravimetric analysis showed that carbothermal reactions under microwave heating proceeded to a greater extent and at a faster pace compared with those under conventional *** metal phases were observed in the microstructures only under microwave *** carbothermal reduction process under microwave heating was *** electric and magnetic susceptibility differences were introduced into the thermodynamics analysis for the formation of metal *** developed thermodynamics considered that microwave heating could make the reduction of MnO to Mn more accessible and increase the reduction extent.

关键词： carbothermal reduction manganese ore manganese oxides microwave heating thermodynamics electromagnetic fields

Effect of Recycled Mixed Powder on the Mechanical Properties and Microstructure of Concrete

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Journal of Renewable Materials 2022年第5期10卷 1397-1414页

作者： chao Liu Huawei Liu jian Wu Shaanxi Key Laboratory of Safety and Durability of Concrete Structures Xijing UniversityXi’an710123China School of Civil Engineering Xi’an University of Architecture and TechnologyXi’an710055China

In this paper,recycled bricks and recycled concrete were applied to prepare eco-friendly recycled mixed powder(RMP)cementitious material,as a supplementary to replace conventional cement for improve the recycling of construction and demolition *** on the effect of cementitious materials on the hydration of silicate cement,the effects of RMP on the workability,mechanical properties and microstructure of recycled mixed powder concrete(RMPC)with the different replacement ratios and the 8:4 and 6:4 mixing ratio of recycled brick powder(RBP)and recycled concrete powder(RCP)were *** results showed that the fluidity of the mix decreased with increasing of the replacement ratio and the mixing ratio of RBP and RCP,but the influence of the fluidity was smaller within 15%replacement *** the replacement ratio increases,the internal pore structure of RMPC tends to be loose and porous,which exhibits a significant pore volume distribution *** number of large capillaries was considerably increased at replacement ratio of 45%.The 7 d compressive strength of RMPC was slightly lower than that of ordinary *** compressive and splitting tensile strengths of RMPC at 28 d increased by 4.2%and 10.1%,respectively,with increasing curing age at 15%replacement ratio and 6:4 mixing *** RMPC mechanical strengths with RBP and RCP at the mixing ratio of 6:4 was higher than those of 8:***,a basis for the recycling of RBP and RCP in the construction industry can be provided by the results of this study.

关键词： Recycled concrete recycled mixed powder pore structure mechanical properties

Degenerate Orbit Flip Homoclinic Bifurcations with Higher Dimensions

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Acta Mathematica Sinica,English Series 2006年第6期22卷 1651-1656页

作者： Ran chao WU jian Hua SUN Department of Mathematics Nanjing University Nanjing 210093 P. R. China

Bifurcations of a degenerate homoclinic orbit with orbit flip in high dimensional system are studied. By establishing a local coordinate system and a Poincare map near the homoclinic orbit, the existence and uniqueness of 1-homoclinic orbit and 1-periodic orbit are given. Also considered is the existence of 2-homoclinic orbit and 2-periodic orbit. In additon, the corresponding bifurcation surfaces are given.

关键词： Orbit flip Homoclinic bifurcations Poincaré map

A unified analysis of a micro-beam,droplet and CNT ring adhered on a substrate:Calculation of variation with movable boundaries

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Acta Mechanica Sinica 2013年第1期29卷 62-72页

作者： jian-lin Liu Re Xia School of Pipeline and Civil Engineering China University of Petroleum School of Power and Mechanical Engineering Wuhan University

In this study, we developed a general method to analytically tackle a kind of movable boundary problem from the viewpoint of energy variation. Having grouped the adhesion of a micro-beam, droplet and carbon nanotube （CNT） ring on a substrate into one framework, we used the developed line of reasoning to investigate the adhesion behaviors of these systems. Based upon the derived governing equations and transversality conditions, explicit solutions involving the critical parameters and morphologies for the three systems are successfully obtained, and then the parameter analogies and common characteristics of them are thor- oughly investigated. The presented method has been verified via the concept of energy release rate in fracture mechanics. Our analyses provide a new approach for exploring the mechanism of different systems with similarities as well as for understanding the unity of nature. The analysis results may be beneficial for the design of nano-structured materi- als, and hold potential for enhancing their mechanical, chemical, optical and electronic properties.

关键词： Variational theory - Transversality condition Beam adhesion Droplet adhesion Carbon nanotube ring adhesion