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Applied Mathematics and Mechanics(English Edition) 2011年第8期32卷 981-996页

作者：吴海军蒋伟康 y.j.liu State Key Laboratory of Machinery System and Vibration Shanghai Jiao Tong University Shanghai 200240 P. R. China Mechanical Engineering University of Cincinnati Cincinnati Ohio 45221-0072 USA

This paper describes formulation and implementation of the fast multipole boundary element method （FMBEM） for 2D acoustic problems. The kernel function expansion theory is summarized, and four building blocks of the FMBEM are described in details. They are moment calculation, moment to moment translation, moment to local translation, and local to local translation. A data structure for the quad-tree construction is proposed which can facilitate implementation. An analytical moment expression is derived, which is more accurate, stable, and efficient than direct numerical computation. Numerical examples are presented to demonstrate the accuracy and efficiency of the FMBEM, and radiation of a 2D vibration rail mode is simulated using the FMBEM.

关键词： 2D acoustic wave problem Helmholtz equation fast multipole method boundary element method

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Advances in additively manufactured titanium alloys by powder bed fusion and directed energy deposition:Microstructure,defects,and mechanical behavior

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journal of Materials Science & Technology 2024年第16期183卷 32-62页

作者： H.y.Ma j.C.Wang P.Qin y.j.liu L.y.Chen L.Q.Wang L.C.Zhang Centre for Advanced Materials and Manufacturing School of EngineeringEdith Cowan University270 Joondalup DriveJoondalupPerthWA 6027SA School of Engineering M050The University of Western Australia35 Stirling HighwayCrawleyPerthWA 6009SA Institute of Metals College of Material Science and EngineeringChangsha University of Science&TechnologyChangsha 410004China School of Material Science and Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China State Key Laboratory of Metal Matrix Composites School of Material Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Ti and its alloys have been broadly adopted across various industries owing to their outstanding proper-ties,such as high strength-to-weight ratio,excellent fatigue performance,exceptional corrosion resistance and so *** manufacturing(AM)is a complement to,rather than a replacement for,traditional manufacturing *** enhances flexibility in fabricating complex components and resolves machin-ing challenges,resulting in reduced lead times for custom ***,owing to distinctions among various AM technologies,Ti alloys fabricated by different AM methods usually present differences in mi-crostructure and defects,which can significantly influence the mechanical performance of built ***,having an in-depth knowledge of the scientific aspects of fabrication and material properties is crucial to achieving high-performance Ti alloys through different AM *** article reviews the mechanical properties of Ti alloys fabricated by two mainstream powder-type AM techniques:powder bed fusion(PBF)and directed energy deposition(DED).The review examines several key aspects,en-compassing phase formation,grain size and morphology,and defects,and provides an in-depth analysis of their influence on the mechanical behaviors of Ti *** review can aid researchers and engi-neers in selecting appropriate PBF or DED methods and optimizing their process parameters to fabricate high-performance Ti alloys for a wide range of industrial applications.

关键词： Powder bed fusion Directed energy deposition Titanium alloys Phase transformation Defects Mechanical property

Comparison of microstructure and mechanical behavior of Ti-35Nb manufactured by laser powder bed fusion from elemental powder mixture and prealloyed powder

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journal of Materials Science & Technology 2022年第10期105卷 1-16页

作者： j.C.Wang y.j.liu S.X.Liang y.S.Zhang L.Q.Wang T.B.Sercombe L.C.Zhang School of Engineering Edith Cowan University270 Joondalup DriveJoondalupPerthWA 6027Australia School of Engineering M050The University of Western Australia35 Stirling HighwayCrawleyPerthWA 6009Australia Northwest Institute for Nonferrous Metal Research Xi’an 710016China State Key Laboratory of Metal Matrix Composites School of Material Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Although different types of powder feedstock are used for additive manufacturing via laser powder bed fusion(L-PBF),limited work has attempted to directly compare the microstructure and mechanical behavior of components manufactured from those powder *** work investigated the microstructure,phase composition,melt pool morphology,and mechanical properties of a prealloyed Ti-35Nb alloy manufactured using L-PBF and compared these to their counterparts produced from elemental powder *** samples manufactured from the powder mixture are composed of randomly distributed undissolved Nb in theα/βmatrix,resulting from the unstable melt pool during the melting of the powder *** contrast,parts produced from prealloyed powder display a homogeneous microstructure withβandαphases,owing to the full melting of prealloyed powder,therefore,a more stable melt pool to achieve a homogeneous *** Ti-35Nb manufactured from prealloyed powder exhibits large tensile ductility(about 10 times that of the counterparts using mixed powder),attributed to the high homogeneity in microstructure and chemical composition,strong interface bonding,relatively low oxygen content,and the existence of a large amount ofβ*** work sheds insights into understanding the effect of powder feedstock on the melt pool stability therefore the microstructure and mechanical behavior of the resultant parts.

关键词： Titanium-niobium Powder bed fusion Additive manufacturing Melt pool stability Microstructure Mechanical properties

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Construction of 2D/2D Ti_(3)C_(2)T_(x)MXene/CdS heterojunction with photothermal effect for efficient photocatalytic hydrogen production

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journal of Materials Science & Technology 2024年第4期171卷 1-9页

作者： T.y.Huang Z.yang S.y.yang Z.H.Dai y.j.liu j.H.Liao G.y.Zhong Z.j.Xie y.P.Fang S.S.Zhang Key Laboratory for Biobased Materials and Energy of Ministry of Education Guangdong Laboratory for Lingnan Modern AgricultureCollege of Materials and EnergySouth China Agricultural UniversityGuangzhou 510643China School of Physics and Optoelectronics South China University of TechnologyGuangzhou 510640China School of Chemical Engineering and Energy Technology Guangdong Provincial Key Laboratory of Distributed Energy SystemsDongguan University of TechnologyDongguan 523808China

The insensitivity of semiconductors to visible and infrared light is a key constraint on the utilization of light energy in photocatalytic *** photocatalysts with full-spectrum absorption through surface engineering is an effective approach to fully harnessing light energy in semiconductor ***,a novel stable Ti_(3)C_(2)T_(x)MXene/CdS heterojunction catalyst is obtained by in-situ epitaxial growth of two-dimensional(2D)CdS nanosheets on 2D MXene interface via a solvothermal *** exceptional light absorption properties of MXene confer outstanding full-spectrum driven photocat-alytic hydrogen evolution capability upon the heterogeneous *** unique 2D/2D structure effectively mitigated the recombination of photogenerated carriers,enhancing the photocatalytic performance of the ***,the composite catalyst exhibits a significantly higher surface temperature of 80.4℃under visible light irradiation at an intensity of 0.1 W/cm^(2),which is 1.84 times higher than that of *** irradiation of visible and near infrared light,the composite catalyst with photothermal ef-fect demonstrates a remarkable hydrogen evolution rate of 65.4 mmol g^(-1)h^(-1),which is 7.2 times higher than that of CdS *** study introduces a novel approach for constructing full-spectrum absorption catalysts and expands the application of the photothermal effect in photocatalytic hydrogen evolution research.

关键词： Two-dimensional structure Heterostructure Photothermal effect Photocatalyst Hydrogen evolution

A two-level non-intrusive coupling method for fatigue analysis

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A two-level non-intrusive coupling method for fatigue analys...

High-pressure/low-temperature Metamorphism in Northern Hubei Province,Central China

2016年航空科学与技术全国博士生学术论坛

作者： y.j.liu Q.SUN School of Aeronautics Northwestern Polytechnical University

In the present paper, based on the non-intrusive coupling concept and the continuum damage mechanics, a two-level non-intrusive coupling strategy for fatigue analysis procedure is developed to efficiently and accurately predict the fatigue damage of critical details in a large structure. Coupled multi-scale models including the global structure（coarse mesh） and local details（fine mesh） are involved to evaluate fatigue damage in local details and their effect on the global structure. In this method, the fatigue analysis in critical region is divided into two levels – the local boundary condition update and the local fatigue analysis. In the first level, the external cyclic load is transferred from global scale to the local scale. And in the second level, the local fatigue analysis driven by the local cyclic boundary is carried out. The computational procedure of this two-level analysis can be fully coupled, semi-coupled or uncoupled according to different scenarios. Furthermore, the low-cycle fatigue damage is studied and the corresponding fatigue life predictions are simulated on a plate with a central circular hole under cyclic loading. The results reveal that the present method greatly improves the numerical efficiency and accords well with the traditional FE analysis with global fine mesh.

关键词：转捩湍流翼型平板气动特性

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资源环境与工程 2016年第B4期30卷 89-104页

作者： G.Zhou y.j.liu E.A.Eide j.G.Liou W.G.Ernst Hubei Bureau of Geology and Mineral Resources Wuhan Hubei 430022 Department of Geology Stanford UniversityStanford California 94305

The Qinling-Dabie accretionary fold belt in east-central China represents the E-W trending suture zone between the Sino-Korean and yangtze cratons. A portion of the accretionary complex exposed in northern Hubei Province contains a high-pressure / low-temperature metamorphic sequence progressively metamorphosed from the blueschist through greenschist to epidote-amphibolite / eclogite facies. The Hongan metamorphic belt can be divided into three metamorphic zones,based on progressive changes in mineral assemblages: Zone Ⅰ,in the south,is characterized by transitional blueschist-greenschist facies; ZoneⅡis characterized by greenschist facies; ZoneⅢ,in the northern most portion of the belt,is characterized by eclogite and epidote-amphibolite facies sequences. Changes in amphibole compositions from south to north as well as the appearance of increasingly higher pressure mineral assemblages toward the north document differences in metamorphic P-T conditions during formation of this belt. Preliminary P-T estimates for Zone I metamorphism are 5 ~ 7 kbar,350 ~ 450℃; estimates for Zone III eclogites are 10 ~ 22 kbar,500 ±50℃. The petrographic,chemical and structural characteristics of this metamorphic belt indicate its evolutionin a northward-dipping subduction zone and subsequent uplift prior to and during the final collisionbetween the Sino-Korean and yangtze cratons.

关键词： central China eclogite high-P/T belt transitional blueschist-greenschist

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软组织肉瘤：基于MRI和组织病理切片的直接比较IVIM和DKI参数与Ki-67标记指数表达相关

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国际医学放射学杂志 2022年第5期45卷 619-620页

作者： K.Zhang y.Dai y.j.liu j.Tao Z.A.Pan L.Z.Xie 鹿娜

摘要目的探讨体素内不相干运动（IVIM）和扩散峰度成像（DKI）参数与Ki-67标记指数（LI）表达在软组织肉瘤（STS）中的相关性。方法共41例STS病人在3.0 T MR上接

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Down-regulation of nuclear protein-1 induces cell cycle arrest in G0/G1 phase in glioma cells in vivo and vitro via P27

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Down-regulation of nuclear protein-1 induces cell cycle arre...

第十六届中国医师协会神经外科医师年会

作者： j.LI Z.G.LIAN y.H.XU R.y.liu Z.Q.WEI T.LI H.T.LV y.S.ZHAO y.j.liu B.DONG X.FU Department of Neurosurgery First Affiliated Hospital of Dalian Medical University Department of Interventional therapy First Affiliated Hospital of Dalian Medical University

Nuclear protein-1(NUPR1),also named as p8 or Com1,has been since found overexpressed in several human malignant tumor cells,such as ***1 also regulates cell cycle progression,however,the role of NUPR1 in regulating glioma cell cycle remains poorly *** efficiency of U87and U251 cells infected with lentiviral vector was detected by quantitative real-time PCR and western blot in vitro and ***-activated cell sorting(FACS) and western blot were used to explore mechanism by which NUPR1 modulates cell cycle in U87 and ***(IHC) was applied to detect expression level of P27,CDK2 and cyclin E in human glioma tissues with NUPR1 positive expression and tumorigenesis in nude *** confirmed that down-regulation of NUPR1 arrested the cell cycle in the G0/G1 phase in U87 and U251 cells in ***,the expression level of P27 was increased,and CDK2 and cyclin E were decreased upon silencing NUPR1 expression in vitro and *** conclusion,Knockdown of NUPR1 induces cell cycle arrest in G0/G1 phase in glioma cells via P27.

关键词： Glioma NUPR1 P27 Cell Cycle

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联机手写汉字识别的理论与实践

中文信息学报 1988年第4期 1-13页

作者：刘迎建戴汝为中科院自动化所

本文以句法模式识别的理论为指导,以大量实践为基础,给出在第四代计算机基础上联机手写汉字识别的形式化和工程化的方法。从汉字识别角度提出,汉字应分成笔段、笔划、字根、字、词组五个层次,分别用模糊属性文法对各个层次进行描述。提... 详细信息

本文以句法模式识别的理论为指导,以大量实践为基础,给出在第四代计算机基础上联机手写汉字识别的形式化和工程化的方法。从汉字识别角度提出,汉字应分成笔段、笔划、字根、字、词组五个层次,分别用模糊属性文法对各个层次进行描述。提出启发式模板引导强制匹配方法,并给出了对根和字的具体匹配过程。在词组的识别中,提出对词组求距离的概念和利用上下文的粗分类方法,描述了词组的存贮结构和词组的匹配过程。利用本文的方法,可以联机识别从楷书至行书范围的手写体汉字,识别率的提高仅与增加各层次的模板有关,与识别方法无关。

关键词：笔段字形有限集产生式词组汉字识别短语文字识别粗分类笔划模糊自动机字根非终止符

MRI评价性别、年龄及体质量指数对正常腮腺腺体的脂肪含量和ADC值的影响

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国际医学放射学杂志 2014年第6期 593-594页

作者： H.C.Chang C.j.juan H.C.Chiu C.C.Cheng S.C.Chiu y.j.liu 高芬 MD.624 Department of Electrical EngineeringNational Taiwan University

摘要目的建立包括健康人群的年龄、性别、体质量指数(BMI)指标的方程公式来评估腮腺组织的标准表观扩散系数(ADC)、脂肪含量,并阐明脂肪抑制对ADC值测量的影

关键词：脂肪饱和 ADC MRI 脂肪含量体质量指数腮腺唾液腺