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Identification of Kinematic Errors of Five-axis Machine Tool Trunnion Axis from Finished Test Piece

Chinese Journal of Mechanical Engineering 2014年第5期27卷 999-1007页

作者： ZHANG Ya FU Jianzhong chen Zichen The State Key Lab of Fluid Power Transmission and Control Zhejiang University Zhejiang Industry Polytechnic College

Compared with the traditional non-cutting measurement,machining tests can more accurately reflect the kinematic errors of five-axis machine tools in the actual machining process for the ***,measurement and calculation of the machining tests in the literature are quite difficult and time-consuming.A new method of the machining tests for the trunnion axis of five-axis machine tool is ***,a simple mathematical model of the cradle-type five-axis machine tool was established by optimizing the coordinate system settings based on robot ***,the machining tests based on error-sensitive directions were proposed to identify the kinematic errors of the trunnion axis of cradle-type five-axis machine *** adopting the error-sensitive vectors in the matrix calculation,the functional relationship equations between the machining errors of the test piece in the error-sensitive directions and the kinematic errors of C-axis and A-axis of five-axis machine tool rotary table was established based on the model of the kinematic *** to our previous work,the kinematic errors of C-axis can be treated as the known quantities,and the kinematic errors of A-axis can be obtained from the *** method was tested in Mikron UCP600 vertical machining *** machining errors in the error-sensitive directions can be obtained by CMM inspection from the finished test piece to identify the kinematic errors of five-axis machine tool trunnion *** results demonstrated that the proposed method can reduce the complexity,cost,and the time consumed substantially,and has a wider *** paper proposes a new method of the machining tests for the trunnion axis of five-axis machine tool.

关键词： five-axis machine tool kinematic errors trunnion axis test piece error-sensitive directions

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Feasibility study of a large-scale tuned mass damper with eddy current damping mechanism

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Earthquake Engineering and Engineering Vibration 2012年第3期11卷 391-401页

作者： Wang Zhihao chen Zhengqing Wang Jianhui Wind Engineering Research Center Hunan UniversityChangsha 410082China School of Civil Engineering and Communication North China University of Water Resources and Electric PowerZhengzhou 450011China

Tuned mass dampers （TMDs） have been widely used in recent years to mitigate structural vibration. However, the damping mechanisms employed in the TMDs are mostly based on viscous dampers, which have several well-known disadvantages, such as oil leakage and difficult adjustment of damping ratio for an operating TMD. Alternatively, eddy current damping （ECD） that does not require any contact with the main structure is a potential solution. This paper discusses the design, analysis, manufacture and testing of a large-scale horizontal TMD based on ECD. First, the theoretical model of ECD is formulated, then one large-scale horizontal TMD using ECD is constructed, and finally performance tests of the TMD are conducted. The test results show that the proposed TMD has a very low intrinsic damping ratio, while the damping ratio due to ECD is the dominant damping source, which can be as large as 15% in a proper configuration. In addition, the damping ratios estimated with the theoretical model are roughly consistent with those identified from the test results, and the source of this error is investigated. Moreover, it is demonstrated that the damping ratio in the proposed TMD can be easily adjusted by varying the air gap between permanent magnets and conductive plates. In view of practical applications, possible improvements and feasibility considerations for the proposed TMD are then discussed. It is confirmed that the proposed TMD with ECD is reliable and feasible for use in structural vibration control.

关键词： tuned mass damper eddy current damping permanent magnets conductive plate modal damping ratio

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Effects of electric parameters on microstructure and properties of MAO coating fabricated on ZK60 Mg alloy in dual electrolyte

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Rare Metals 2012年第2期31卷 172-177页

作者： chen, Jing Wang, Zexin Lu, Sheng School of Materials Science and Engineering Jiangsu University of Science and Technology Zhenjiang 212003 China School of Mechanical Engineering Jiangsu University of Science and Technology Zhenjiang 212003 China

Micro-arc oxidation (MAO) process was carried out in a dual electrolyte system of NaAlO 2 and Na 3 PO 4 on ZK60 Mg alloys to explore the effect of electric parameters including current density, frequency, duty cycle and oxidation time on the evolution of coatings and other characteristics. The microstructural characteristics of coatings were observed by scanning electron microscopy (SEM) combined with the analysis of voltage-time responses during MAO process. Test of weight loss was conducted at a 3.5% NaCl solution to assess the resistance to corrosion. The results indicate that the current density and duty cycle play key roles on the coating quality. The peak voltage during MAO process increased with the increase in current density but the coating would be more easily detached when the current density was beyond a critical value. Voltage during MAO and microstructure of the coating were affected remarkably by duty cycle, and corrosion resistance was improved greatly when duty cycle was 40%. By means of single variable experiments, MAO process with optimized electric parameters was developed, which corresponds to the current density of 20 A dm 2 , frequency of 500 Hz, duty cycle of 40% and oxidation time of 15 min.

关键词： magnesium alloys micro-arc oxidation electrical parameters microstructure performance

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Highly efficientγ-ray generation by 10 PW-class lasers irradiating heavy-ion plasmas

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Plasma Science and Technology 2022年第7期24卷 201-207页

作者： Mi TIAN Ziyu chen Key Laboratory of High Energy Density Physics and Technology(MoE) College of PhysicsSichuan UniversityChengdu 610064People's Republic of China National Key Laboratory of Shock Wave and Detonation Physics Mianyang 621999People's Republic of China

10 PW-class lasers irradiating overcritical plasmas in the quantum electrodynamics regime promise to generate ultrabrightγ-ray sources in the *** using two-dimensional particle-in-cell simulations,we report highly efficientγ-ray generation in the parameter regime of 10 PW-class lasers at an intensity level of 10^(23)W cm^(–2)interaction with heavy-ion plasmas which have large-scale *** laser-to-γ-ray(>1 MeV)energy conversion efficiency reaches close to 60%with an above 10^(14)γ-photons/*** averageγ-photon energy is about 14 MeV with the highest photon energy exceeding 1 *** high-energyγ-photons are mainly directed in the forward *** also find that plane target geometry is efficient enough for high powerγ-ray radiation,which is beneficial for easing the difficulty of complex target manufacturing and alignment in experiments.

关键词： laser plasma interactions γ-ray source particle-in-cell simulations

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A Novel Method to Extract Rocks from Mars Images

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Chinese Journal of Electronics 2015年第3期24卷 455-461页

作者： WANG Shuliang chen Yasen YUAN Hanning School of Software Beijing Institute of Technology Tencent Inc. Hi-tech Park Nanshan District

Automatically extracting rocks from Martian surface images is valuable for hazard avoidance and rover localization in rover missions. To extract rocks, data field on image is proposed to model the interaction between two pixels of an image under the imagery characteristics of Martian surface. Foreground rocks are firstly grouped into clusters by locating the centers and edges in data field after they are differed from background information via binarizing partition. Then target rocks are discovered for the Rover to keep healthy paths. The experiment shows the data field on image is practical and potential.

关键词： Data fields Mars image Rock extraction

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Embracing connected intelligence with the YuanOS architecture:one OS kit for all

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Frontiers of Computer Science 2024年第1期18卷 1-3页

作者： Haibo chen Ning JIA Jie YIN Institute of Parallel and Distributed Systems School of Electronic Information and Electrical EngineeringShanghai Jiao Tong UniversityShanghai 200240China OS Kernel Lab Huawei Technologies Co.Ltd.Beijing 100085China

Operating system abstracts hardware and creates application execution environment,and thus is the key pillar for IT *** its first invention in 1956,operating system has been evolved over three main stages:Mainframe,PC&Internet,Mobile Internet[1].Now,the entire society is firmly stepping towards the connected intelligence era[2],how should operating system be evolved to embrace this new era?

关键词： hardware execution connected

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Influence of groove surface texture on temperature rise under dry sliding friction

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Science China(Technological Sciences) 2016年第2期59卷 183-190页

作者： WU Wei SHAO TianMin chen GuiMing State Key Laboratory of Tribology Tsinghua University Beijing 100084 China Xi'an Research Institute of High Technology Xi'an 710025 China

Parallel groove surface textures with different area densities were fabricated on ASTM 1045 steel. Friction tests were con- ducted under dry sliding condition. Temperature rise, friction coefficient and wear of both the textured and untextured speci- mens were studied. An embedded K-type thermocouple beneath the friction surfaces was employed to measure frictional tem- perature rise. The results indicated that the temperature rise of the textured specimen was obviously reduced compared with that of the untextured specimen, although the difference between the friction coefficients was not significan.. The specimen with high texture density exhibited a small temperature rise. The difference in temperature rise between the specimens with different texture densities can be primarily attributed to differences in heat dissipation and energy allocation between the tri- bo-pairs caused by the textured structure. The energy consumed by wear and plastic deformation was small in ~：omparison with the total energy input by friction, thus, the influence of these factors on temperature rise can be considered to be~ negligible.

关键词： groove surface texture temperature rise heat dissipation wear plastic deformation

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IMPLEMENTATION OF MIXED METHODS AS FINITE DIFFERENCE METHODS AND APPLICATIONS TO NONISOTHERMAL MULTIPHASE FLOW IN POROUS MEDIA

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Journal of Computational Mathematics 2006年第3期24卷 281-294页

作者： Zhang-xin chen Xi-jun Yu Center for Scientific Computation Box 750156 Southern Methodist University Dallas TX 75275-0156 USA Research Center for Science Xi'an Jiaotong University Xi'an 710049 China Center for Advanced Reservoir Modeling and Simulation College Vof Engineering'PekingI University China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing 100088 China

In this paper we consider mixed finite element methods for second order elliptic problems. In the case of the lowest order Brezzi-Douglas-Marini elements （if d = 2） or Brezzi- Douglas-Duran-Fortin elements （if d = 3） on rectangular parallelepipeds, we show that the mixed method system, by incorporating certain quadrature rules, can be written as a simple, cell-centered finite difference method. This leads to the solution of a sparse, positive semidefinite linear system for the scalar unknown. For a diagonal tensor coefficient, the sparsity pattern for the scalar unknown is a five point stencil if d = 2, and seven if d = 3. For a general tensor coefficient, it is a nine point stencil, and nineteen, respectively. Applications of the mixed method implementation as finite differences to nonisothermal multiphase, multicomponent flow in porous media are presented.

关键词： Finite difference Implementation Mixed method Error estimates Superconvergence Tensor coefficient Nonisothermal multiphase Multicomponent flow Porousmedia.

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Metallafurans and their synthetic chemistry

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Science Bulletin 2016年第6期61卷 430-442页

作者： Guomei He Jiangxi chen Haiping Xia Key Laboratory of High Performance Ceramic Fibers ofMinistry of Education Department of Materials Science and Engineering College of Materials Xiamen University State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry College of Chemistry and Chemical Engineering Xiamen University

Based on isolobal analogy,the definition of metallafuran was described and its synthetic chemistry was briefly *** the structure of furan,when one of CH groups was replaced by an isolobal metal fragment ML n(M=metal;L=ligand),the corresponding organometallic complex was called metallafuran,which should be two possible isomers called a-metallafuran(metal fragment at a-carbon of original furan)and b-metallafuran(metal fragment at b-carbon of original furan).As an organometallic complex,a-metallafuran has two resonant forms:one can be viewed as carbonyl coordinated vinyl metal complex and the other can be viewed as alkoxymetal ***,a-metallafuran was also called chelated vinyl ketone metal complex or oxametallacyclopentadiene in the early *** synthesis of metallafurans,a-metallafurans were very common and easily prepared,for example,from alkynes insertion into acyl metal complexes and so *** there were rare examples reported for *** this mini review,the synthetic chemistry of metallafuran was mainly focused on its formation mechanism.

关键词： Metallafuran Aromaticity Metallaaromatics Synthesis Mechanism

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KLF6 facilitates differentiation of odontoblasts through modulating the expression of P21 in vitro

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International Journal of Oral Science 2022年第2期14卷 220-230页

作者： Zhuo chen Wenzhi Wu chen Zheng Yanhua Lan Huizhi Xie Zhijian Xie Stomatology Hospital School of StomatologyZhejiang University School of MedicineClinical Research Center for Oral Diseases of Zhejiang ProvinceKey Laboratory of Oral Biomedical Research of Zhejiang ProvinceCancer Center of Zhejiang UniversityHangzhouChina

Multiple signaling pathways are involved in the regulation of cell proliferation and differentiation in odontogenesis and dental tissue renewal,but the details of these mechanisms remain ***,we investigated the expression patterns of a transcription factor,Krüppel-like factor 6(KLF6),during the development of murine tooth germ and its function in odontoblastic ***6 was almost ubiquitously expressed in odontoblasts at various stages,and it was co-expressed with P21(to varying degrees)in mouse dental *** determine the function of Klf6,overexpression and knockdown experiments were performed in a mouse dental papilla cell line(iMDP-3).Klf6 functioned as a promoter of odontoblastic differentiation and inhibited the proliferation and cell cycle progression of i MDP-3 through p21 ***-luciferase reporter assay and chromatin immunoprecipitation showed that Klf6 directly activates p21 ***,the in vivo study showed that KLF6 and P21were also co-expressed in odontoblasts around the reparative *** conclusion,Klf6 regulates the transcriptional activity of p21,thus promoting the cell proliferation to odontoblastic differentiation transition in *** study provides a theoretical basis for odontoblast differentiation and the formation of reparative dentine regeneration.

关键词： KLF6 inhibited details

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