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High Temperature Properties of Discontinuously Reinforced Titanium Matrix Composites:A Review

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Acta Metallurgica Sinica(English Letters) 2014年第5期27卷 787-797页

作者： lin geng Lujun Huang School of Materials Science and Engineering Harbin Institute of Technology

Further improvement on high temperature durability is one of the most important aims except for high specific strength, high specific stiffness, and excellent wear resistance, to design and fabricate discontinuously reinforced titanium matrix composites （DRTMCs）. Their superior properties render them extensive application potential in aerospace and military industries due to the urgent demand for the materials with characteristics of lightweight, high strength, high stiffness and high temperature durability. With development on fabrication methods and room temperature properties, testing, characterizing, evaluating and further increasing high temperature properties of DRTMCs are becoming more and more important to promote their applications. This review provides insights and comprehensions on the high temperature tensile properties, superplastic tensile properties, creep behaviors, and high temperature oxidation behaviors of DRTMCs,

关键词： Titanium matrix composites High temperature tensile properties Creep behaviors Oxidation behaviors Superplasticity

Solving Hardware/Software Partitioning via a Discrete Dynamic Convexized Method

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Wuhan University Journal of Natural Sciences 2019年第4期24卷 341-348页

作者： lin geng Collaborative Innovation Center of IoT Industrialization and Intelligent Production Minjiang University College of Mathematics and Data Science Minjiang University

Hardware/software partitioning is an important step in the design of embedded systems. In this paper, the hardware/software partitioning problem is modeled as a constrained binary integer programming problem, which is further converted equivalently to an unconstrained binary integer programming problem by a penalty method. A local search method, HSFM, is developed to obtain a discrete local minimizer of the unconstrained binary integer programming problem. Next, an auxiliary function, which has the same global optimal solutions as the unconstrained binary integer programming problem, is constructed, and its properties are studied. We show that applying HSFM to minimize the auxiliary function can escape from previous local optima by the increase of the parameter value successfully. Finally, a discrete dynamic convexized method is developed to solve the hardware/software partitioning problem. Computational results and comparisons indicate that the proposed algorithm can get high-quality solutions.

关键词： hardware software partitioning binary integer programming local search dynamic convexized method

SiCp/Al Composites Fabricated by Modified Squeeze Casting Technique

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Journal of Materials Science & Technology 2007年第5期23卷 641-644页

作者： Shoujiang QU lin geng Jiecai HAN Center for Composite Materials Harbin Institute of Technology Harbin 150001 China School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China

A cost effective method was introduced to fabricate pure aluminum matrix composites reinforced with 20% volume fraction of 3.5 μm SiC particles by squeeze casting followed by hot extrusion. In order to lower volume fraction of the composites, a mixed preform containing pure aluminum powder and the SiC particles was used. The suitable processing parameters for the infiltration of pure aluminum melt into the mixed preform are： melt temperature 800℃, preform temperature 500℃, infiltration pressure 5 MPa, and solidification pressure 50 MPa. Microstructure and properties of the composites in both as-cast and hot extruded states were investigated. The results indicate that hot extrusion can obviously improve the mechanical properties of the composite.

关键词： Aluminum Particulate reinforced composites Casting Liquid infiltration

High-content graphene nanoplatelet reinforced aluminum composites produced by ball milling and hot extrusion

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Science China(Technological Sciences) 2020年第8期63卷 1426-1435页

作者： ZHENG Zhong ZHANG XueXi LI JianChao geng lin School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

Due to the high specific surface area of graphene,the effective incorporation of high-content graphene in metals is ***,aluminum composites with graphene nanoplatelet(GNP)content up to 5.0 vol%were prepared by spark plasma sintering(SPS)of blended powders with various ball milling regimes and subsequent hot *** effects of GNP distribution state on the properties of GNP/Al composite were investigated.5.0 vol%GNPs were uniformly dispersed in aluminum matrix by high-speed ball milling(HSBM)process,but with damage GNPs due to the too high energy *** contrast,the wellstructured and dispersed GNPs in aluminum powders were obtained via shift-speed ball milling(SSBM).The clear GNP-Al interface in extruded SSBM composite was attributed to well-structured *** a result,the yield strength(YS)and ultimate tensile strength(UTS)of composite produced by SSBM reached 279 and 303 MPa,which are 166%and 116%higher than those of monolithic *** demonstrated that it may be promising to introduce high-content GNPs with tailorable interface in Al alloys via modified ball milling technique and hot extrusion.

关键词： aluminum-matrix composites graphene nanoplatelet ball milling hot extrusion mechanical properties

Combining Clustered Adaptive Multistart and Discrete Dynamic Convexized Method for the Max-Cut Problem

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Journal of the Operations Research Society of China 2014年第2期2卷 237-262页

作者： geng lin Wenxing Zhu Department of Mathematics Minjiang UniversityFuzhou 350108China Center for Discrete Mathematics and Theoretical Computer Science Fuzhou UniversityFuzhou 350002China

Given an undirected graph with edge weights,the max-cut problem is to find a partition of the vertices into twosubsets,such that the sumof theweights of the edges crossing different subsets *** based on auxiliary function can obtain high-quality solutions of the max-cut problem,but suffer high solution cost when instances grow *** this paper,we combine clustered adaptive multistart and discrete dynamic convexized method to obtain high-quality solutions in a reasonable *** experiments on two sets of benchmark instances from the literature were *** results and comparisons with some heuristics based on auxiliary function show that the proposed algorithm is much faster and can obtain better *** with several state-ofthe-science heuristics demonstrate that the proposed algorithm is competitive.

关键词： Max-cut Local search Dynamic convexized method Clustered adaptive multistart

Social Construction Functions of Consumption Space under Stratification:The Case of Guangzhou

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Chinese Geographical Science 2010年第5期20卷 450-460页

作者： lin geng WANG Lianjun ZHANG Xiaoying Department of Urban and Regional Planning/Center for Urban and Regional Studies School of Geography and Planning SUN Yat-Sen University Guangzhou 510275 China

As Chinese cities rapidly transformed themselves into consumerist societies,the relationship between consumers and consumption space under stratification has become a new research area in the field of urban social *** on a consumer behavior analysis,this study explores the relationship between consumption space and the social strata of consumers in typical shopping malls in Guangzhou where the first shopping mall in China was *** result shows that shopping malls have performed significant constructive functions of organizing consumers from different social classes into different consumption *** middle-and upper-class consumers,the function of shopping malls centers on utilitarian consumption,identity recognition,and identity construction;whereas for lower-class consumers,its function revolves around pleasure and *** symbolism of consumption space is the underlying reason for shopping malls to have their social constructive *** findings of this research suggest that:1) a shopping mall is a productive consumption space and a geographical space with subjectivity;2) the micro-location of a shopping mall has social construction function;and 3) symbolic consumption is the core of social construction.

关键词： consumption space stratification shopping mail social construction social identity symbolic consumption

Evolution of Unsteady Flow near Rotor Tip during Stall Inception

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Journal of Thermal Science 2011年第4期20卷 294-303页

作者： Shaojuan geng Feng lin Jingyi Chen Chaoqun Nie Institute of Engineering Thermophysics Chinese Academy of Sciences RO. Box 2706 Beijing 100190 China

Previously the features of circumferential propagation of self-induced tip leakage flow unsteadiness for a low speed isolated axial compressor rotor in the authors' laboratory were discovered and investigated via numerical simulation,which only occurs below a critical stable flow point that is close to but not yet at the stall *** in this paper,the detailed investigation on evolution of tip leakage flow during the throttling process into spike rotating stall was conducted by adopting the valve-throttling *** this process,the development of the circumferential propagation of tip leakage flow unsteadiness was especially focused *** to the unsteady characteristics of pressure signals,the evolvement of compressor flow field can be classified into four *** compressor throttled,the oscillation frequency of self-induced unsteady tip leakage flow decreased gradually,and thus resulted in the decrease of its circumferential propagation *** circumferential propagation of self-induced tip leakage flow unsteadiness is closely related with rotating *** the forward spillage of tip leakage flow at the leading edge occurred,the spike type rotating stall was *** flow struc-tures were given in the paper.

关键词： Axial compressor stall inception tip leakage flow rotating instability numerical simulation

Binary Particle Swarm Optimization Based Hyper-Heuristic for Solving the Set-Union Knapsack Problem

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Wuhan University Journal of Natural Sciences 2021年第4期26卷 305-314页

作者： CHEN Xiang LUO Jinyan lin geng College of Mathematics and Data Science Minjiang UniversityFuzhou 350121FujianChina

The set-union knapsack problem(SUKP)is proved to be a strongly NP-hard problem,and it is an extension of the classic NP-hard problem:the 0-1 knapsack problem(KP).Solving the SUKP through exact approaches is computationally ***,several swarm intelligent algorithms have been proposed in order to solve the ***-heuristics have received notable attention by researchers in recent years,and they are successfully applied to solve the combinatorial optimization *** this article,we propose a binary particle swarm optimization(BPSO)based hyper-heuristic for solving the SUKP,in which the BPSO is employed as a search *** proposed approach has been evaluated on three sets of SUKP *** results are compared with 6 approaches:BABC,EMS,gPSO,DHJaya,b WSA,and HBPSO/TS,and demonstrate that the proposed approach for the SUKP outperforms other approaches.

关键词： set-union knapsack problem binary programming hyper-heuristics particle swarm optimization

Microstructure of in-situ Synthesized (TiB+TiC)/Ti Composites Prepared by Hot-pressing

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Journal of Materials Science & Technology 2003年第z1期19卷 101-102页

作者： Zhenzhu ZHENG lin geng Honglin WANG Weimin ZHOU Hongyu XU School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China Hei Long Jiang Education College Harbin 150008 China

In-situ 5 *** TiB whiskers and TiC particulates reinforced Ti composites were fabricated by blending Ti powderand B4C particulates followed by reactive hot-pressing. The microstructure of the composites was investigated byusing differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscope (TEM)and scanning electron microscope (SEM). The results showed that the reactive temperature between Ti and B4C isabove 570°. Two kinds of reinforcements with different shapes were formed during hot-pressing: TiB short-fiber andequiaxed TiC particles. The interracial bonding between the reinforcements and Ti matrix is perfect. No interracialreaction between reinforcements and Ti matrix was found.

关键词： Ti matrix composite, In-situ synthesis, Powder metallurgy