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Influence of nanometric CeO2 coating on high temperature oxidation of Cr

Progress in Natural Science:Materials International 2007年第5期17卷 601-606页

作者： Jin Huiming , Zhang Linnan and Liu Xiaojun (Materials research center, Department of Mechanical engineering, Yangzhou university, Yangzhou 225009, china College of Materials Science and engineering, North-East university, Shenyang 110014, china) [a]Materials research center Department of Mechanical Engineering Yangzhou University Yangzhou China [b]College of Materials Science and engineering North-East University Shenyang China

Isothermal and cyclic oxidation behavior of chromium and its superficially applied nanometric CeO2 samples were studied at 900℃in air. Scanning electronic microscopy (SEM), transmission electronic microscopy (TEM) and high resolution electronic microscopy (HREM) were used to examine the morphology and micro-structure of oxide films. It was found that ceria addition greatly improved the anti-oxidation ability of Cr both in isothermal and cyclic oxidizing experiments. Acoustic emission (AE) technique was used in situ to monitor the cracking and spalling of oxide films, and AE signals were analyzed in time-domain and number-domain according to the related oxide fracture model. Laser Raman spectrometer was also used to study the stress status of oxide films formed on Cr with and without ceria. The main reason for the improvement in anti-oxidation of chromium was that ceria greatly reduced the growing speed and grain size of Cr2O3. This fine-grained Cr2O3 oxide film might have better high temperature plasticity and could relieve parts of compressive stress by means of creeping, and maintained the ridge character and relatively low internal stress level. Meanwhile, ceria application reduced the size and the number of interfacial defects, while remarkably enhanced the adhesive property of Cr2O3 oxide scale formed on Cr substrate.

关键词： oxidation stress CeO2 nanoparticle coating chromium.

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SIMULATION SYSTEM FOR FIVE-AXIS NC MACHINING USING GENERAL CUTTING TOOL

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Chinese Journal of Mechanical engineering 2001年第2期14卷 144-150页

作者： Wang Chenpei Zhou Yunfei Zhou Yanhong Zhou Ji national NC System engineering research center, Huazhong university of Science and Technology 华中科技大学数控技术所湖北

A simulation system for five axis NC machining using general cutting tools is presented This system differs from other simulation system in that it not only focuses on the geometric simulation but also focuses on the collision detection which is usually not included in NC machining simulation Besides all of these, estimating cutting forces is also discussed In order to obtain high efficiency, all algorithms use swept volume modeling technique, so the simulation system is compact and can be performed efficiently

关键词： Simulation Envelope Z buffer structure Octree

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Liquid propellant analogy technique in dynamic modeling of launch vehicle

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Science china(Technological Sciences) 2010年第8期53卷 2102-2110页

作者： PAN ZhongWen 1,2 ,XING YuFeng 1 ,ZHU LiWen 2 ,DONG Kai 2 &SUN Mu 2 1Solid Mechanics research center,Beijing university of Aeronautics and Astronautics,Beijing 100191,china 2 Beijing Astronautics Systems engineering Institute,Beijing 100076,china 1. Solid Mechanics research center Beijing University of Aeronautics and Astronautics Beijing 100191 China2. Beijing Astronautics Systems Engineering Institute Beijing 100076 China

The coupling effects among lateral mode,longitudinal mode and torsional mode of a launch vehicle cannot be taken into account in traditional dynamic analysis using lateral beam model and longitudinal spring-mass model *** deal with the problem,propellant analogy methods based on beam model are proposed and coupled mass-matrix of liquid propellant is constructed through additional mass in the present *** an integrated model of launch vehicle for free vibration analysis is established,by which research on the interactions between longitudinal and lateral modes,longitudinal and torsional modes of the launch vehicle can be *** examples for tandem tanks validate the present method and its necessity.

关键词： dynamic characteristics coupled mass integrative modeling propellant analogy

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Numerical simulation on electromagnetic field,flow field and temperature field in semisolid slurry preparation by A-EMS

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Rare Metals 2010年第6期29卷 635-641页

作者： ZHANG Zhifeng,CHEN Xingrun,XU Jun,and SHI Likai national engineering & Technology research center for Nonferrous Metal Matrix Composites,General research Institute for Nonferrous Metals,Beijing 100088,china national engineering & Technology research center for Nonferrous Metal Matrix Composites General Research Institute for Nonferrous Metals Beijing China

A two-dimensional computational model coupling an annular electromagnetic stirring（A-EMS） with a macroscopic heat and fluid flow analysis in Al-alloys semisolid slurry preparation was *** dynamic evolutions of the electromagnetic field,flow field,and temperature field were presented successfully by commercial software ANSYS 10.0 with corresponding experimental verification.A horizontally rotational electromagnetic field and,thereby,a more intensive velocity field were uniformly distributed in the stirred melt even at commercial frequency,and thus,a lower temperature difference in the stirred melt and subsequent uniformly fine microstructures were obtained compared with the normal electromagnetic *** simulation results were in good agreement with experimental ones.

关键词： metal forming electromagnetic stirring numerical analysis semisolid slurry

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Application analysis of empirical mode decomposition and phase space reconstruction in dam time-varying characteristic

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Science china(Technological Sciences) 2010年第6期53卷 1711-1716页

作者： ZHANG ZhiJun1,2,3,GU ChongShi1,2,BAO TengFei1,2,ZHANG Lan1,2 & YU Hong1,2 1 State Key Laboratory of Hydrology-Water Resources and Hydraulic engineering,Hohai university,Nanjing 210098,china 2 national engineering research center of Water Resources Efficient Utilization and engineering Safety,Hohai university,Nanjing 210098,china 3 Department of Civil,Environmental and Geomatic engineering,Swiss Federal Institute of Technology,Zurich 8093,Switzerland 1. State Key Laboratory of Hydrology-Water Resources and Hydraulic engineering Hohai University Nanjing 210098 China2. National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Hohai University Nanjing 210098 China3. Department of Civil Environmental and Geomatic Engineering Swiss Federal Institute of Technology Zurich 8093 Switzerland

In view of some courses of the time-varying characteristics processing in the analysis of dam deformation,the paper proposes a new method to analyze the dam time-varying characteristic based on the empirical mode decomposition and phase space reconstruction *** of all,to reduce the influences on the traditional statistical model from human factors and assure the analysis accuracy,response variables of the time-varying characteristic are obtained by the way of the empirical mode decomposition;and then,a phase plane of those variables is reconstructed to investigate their processing *** methods have already been applied to an actual project and the results showed that data interpretation with the assists of empirical mode decomposition and phase space reconstruction is effective in analyzing the perturbations of response variables,explicit in reflecting the entire development process,and valid for obtaining the evolution rules of the time-varying *** methodology is a powerful technical support for people to further master the rules of dam operation.

关键词： dam safety monitoring dam time-varying characteristic empirical mode decomposition phase space reconstruction

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Distribution,formation and evolution of sand ridges on the East china Sea shelf

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Science china(Technological Sciences) 2010年第3期53卷 822-828页

作者： ZHAO RenBao 1,2,SUN HaiTao 3,WU YaSheng 3 &ZHAO ChuanFeng 1,2 1MOE Key Laboratory of Petroleum engineering,china university of Petroleum,Beijing 102249,china 2 Enhanced Oil Recovering research center,china university of Petroleum,Beijing 102249,china 3Faculty of Natural Resource&Information Technology,china university of Petroleum,Beijing 102249,china 1. MOE Key Laboratory of Petroleum engineering China University of Petroleum Beijing 102249 China2. Enhanced Oil Recovering Research Center China University of Petroleum Beijing 102249 China3. Faculty of Natural Resource & Information Technology China University of Petroleum Beijing 102249 China

Influence of CO2 corrosion on reservoir mineralogical composition,pore structure and their mechanical characteristics was studied using XRD,SEM,rock tri-axial machine and core flow experimental *** was found that the corrosion effect was mainly attributed to rock texture and structure,fluid composition and external dynamical conditions in the experimental *** cores with bedding structures,their bedding surfaces were the preferential corrosion regions,because micro-cracks would evolve at these surfaces in the pressure-releasing ***,for cores with massive structures controlled by stable water environment,the CO2 corrosion would result in pore enlargement and secondary pore *** gas velocity from outlet showed sharp increase in the injection process of CO2-H2O *** could be explained by two changes caused by *** was the opening and closure of *** other was particle *** the corrosion time increased,both tensile strength and compressive strength decreased,which confirmed decrease of cementation *** should also be noted that permeability increase and micro-cracks generation would pose damage to the capacity of CO2 geological storage.

关键词： carbon dioxide geological storage mineralization enhanced oil recovery corrosion

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Surface electromagnetic modes contribution to the anomalous terahertz transmission through double-layered metal hole array

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Science china(Information Sciences) 2012年第1期55卷 90-97页

作者： RAO Lei1&YANG DongXiao1,2 1Department of Information Science and Electronic engineering,Zhejiang university,Hangzhou 310027,china 2research center for Terahertz Technology,Zhejiang university,Hangzhou 310027,china 1. Department of Information Science and Electronic engineering Zhejiang University Hangzhou 310027 China2. Research Center for Terahertz Technology Zhejiang University Hangzhou 310027 China

Terahertz transmission spectra through both single-layered and double-layered sub-wavelength metal hole arrays were calculated using rigorous mode-matching *** dispersion relations of the single-layered and double-layered metal hole arrays were obtained by FDTD *** are three anomalous peaks in the spectrum of the double-layered metal hole array,which arise from the three surface electromagnetic modes appearing in the dispersion *** comparing the transmission spectra and the dispersion relations of the single-layered and double-layered metal hole arrays,it was found that the two surface electromagnetic modes at higher frequencies are introduced by the single-layered metal hole array,while the one at lower frequencies is introduced by the double-layered metal hole *** validity of the analysis was qualitatively verified by the experimental *** structure can be finely designed for potential applications,such as wideband filtering.

关键词： surface electromagnetic modes double-layered metal hole array terahertz

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AZ61镁合金挤锻复合成形技术研究

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特种铸造及有色合金 2009年第4期29卷 384-387页

作者：李亚宁龙思远曹韩学重庆大学材料科学与工程学院国家镁合金材料工程技术研究中心

采用镁合金挤锻复合成形的试验方法,研究了AZ61镁合金微观组织演化与塑性变形机制之间的规律。结果表明,挤压和等温模锻后镁合金均发生了动态再结晶,生成了细小均匀的等轴晶粒,经T5热处理后其屈服强度、抗拉强度、伸长率分别可达249MPa... 详细信息

采用镁合金挤锻复合成形的试验方法,研究了AZ61镁合金微观组织演化与塑性变形机制之间的规律。结果表明,挤压和等温模锻后镁合金均发生了动态再结晶,生成了细小均匀的等轴晶粒,经T5热处理后其屈服强度、抗拉强度、伸长率分别可达249MPa、305MPa、15.4%。在此基础上进一步对镁合金的塑性变形机制进行了探讨。

关键词：镁合金挤锻复合成形塑性变形动态再结晶晶粒细化热处理

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Finite Element Harmonic Solution of the Coupled Rotor-bearing System

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厦门大学学报（自然科学版） 2002年第S1期41卷 180-181页

作者： CAI Ting, YANG Jian-gang (national engineering research center of Turbogenerator Vibration, So utheast university, Nanjing 210096, china)

Fluid-solid interaction problems have been studied q uite extensively in the past years. Rotor-bearing system is a typical example. Fluid field is changed under the exciting of rotor vibration. On the same ti me, a net force caused by fluid pressure exerts on rotor, which will change roto r vibration. So, the fluid-solid coupled analysis method must be used. Traditionally, numerical difference method was used to solve fluid problems. The coupled fluid-solid equation could not be set up based on the method. It is no t until finite element method was used in fluid dynamics area then can the coupl ed dynamics be researched. Recently many experimental, analytical and numerical studies have been used in the area . But in these investigations, it is a ssumed that the solid vibration could not be influenced by fluid. In the other w ords, the force exerted on solid from fluid was neglected in the papers. So, the models built were some kinds of semi-coupled model only. In this paper, the Galerkin finite-element method, two-dimension vibration equ ation of rigid body and Navier-Stokes equations are used to build a full-coupl ed fluid-solid model in rotor-bearing system. Some assumptions are taken: 1) In fluid equation, the nonlinear terms are relatively small and neglected. 2) The gravity takes no effect on this system. 3) The bearing and the rotor are long. Flow and leakage along the axis is neglec ted. 4) The fluid is a kind of Newtonian incondensable viscous fluid. 5) The rotor is considered to be a rigid body. Using the model established, we calculated all the examples given by paper , results show the error are less than 7%. So the full-coupled model is built c orrectly. Examples are given in the end of the paper. After analyzing the examples, we get some conclusions: 1) In rotor-bearing system, while being taken under two conditions that whether coupled method is taken or not, difference of pressure and vibration amplitude could reach 76% and 120%. Therefore coupled met

关键词： Finite Element Harmonic Solution of the Coupled Rotor-bearing System

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research ON PRODUCT INNOVATION DESIGN IN VIRTUAL PRODUCT DEVELOPMENT

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Chinese Journal of Mechanical engineering 2002年第4期15卷 353-359页

作者： Wu Qunbo Zhang Linxuan Xiao Tianyuan Long Xinghai State CIMS engineering research center, Tsinghua university, Beijing 100084, china State CIMS engineering research center Tsinghua University Beijing 100084 China

An integrated template of virtual product development alters primarilysequential tradition mode of product life cycle. The template integrates all processes of productdevelopment using digital modem. An environment of virtual product development provides productdevelopment environment of integration, communion, network, concurrent and collaboration. Combiningdevelopment of new rapier loom, an innovated design process is researched in virtual productdevelopment, which consists three portions: constructing an integration development environment,innovation design and manufacturing simulation. The innovated design process realizes reversedesign, mechanism concept design, structural design and analysis, performance analysis andmanufacturing process simulation of virtual product, which can enhance greatly product performanceand reduce cost and development cycle of new product.

关键词： virtual product development innovation design product data management

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