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Systematic Elastostatic Stiffness Model of Over-Constrained Parallel Manipulators Without Additional Constraint Equations

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Chinese Journal of mechanical engineering 2024年第4期37卷 258-276页

作者： Chao Yang wenyong yu Wei Ye Qiaohong Chen Fengli Huang College of mechanical and Electrical engineering Jiaxing UniversityJiaxing 314001ZhejiangChina Zhejiang Siekon Transmission technology Co. Ltd.Jiaxing 314001ZhejiangChina National and Local Joint engineering Research Center of Reliability Analysis and Testing for mechanical and Electrical Products Zhejiang Sci-Tech UniversityHangzhou 310018ZhejiangChina school of Computer science and technology Zhejiang Sci-Tech UniversityHangzhou 310018ZhejiangChina

The establishment of an elastostatic stiffness model for over constrained parallel manipulators(PMs),particularly those with over constrained subclosed loops,poses a challenge while ensuring numerical *** study addresses this issue by proposing a systematic elastostatic stiffness model based on matrix structural analysis(MSA)and independent displacement coordinates(IDCs)extraction *** begin,the closed-loop PM is transformed into an open-loop PM by eliminating constraints.A subassembly element is then introduced,which considers the flexibility of both rods and *** approach helps circumvent the numerical instability typically encountered with traditional constraint *** IDCs and analytical constraint equations of nodes constrained by various joints are summarized in the appendix,utilizing multipoint constraint theory and singularity analysis,all unified within a single coordinate ***,the open-loop mechanism is efficiently closed by referencing the constraint equations presented in the appendix,alongside its elastostatic *** proposed method proves to be both modeling and computationally efficient due to the comprehensive summary of the constraint equations in the Appendix,eliminating the need for additional *** example utilizing an over constrained subclosed loops demonstrate the application of the proposed *** conclusion,the model proposed in this study enriches the theory of elastostatic stiffness modeling of PMs and provides an effective solution for stiffness modeling challenges they present.

关键词： Parallel manipulator Elastostatic stiffness model Matrix structural analysis Subassembly element Independent displacement coordinates

Fully automatic AI segmentation of oral surgery-related tissues based on cone beam computed tomography images

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International Journal of Oral science 2024年第3期16卷 413-424页

作者： yu Liu Rui Xie Lifeng Wang Hongpeng Liu Chen Liu Yimin Zhao Shizhu Bai wenyong Liu Beijing Yakebot technology Co. Ltd.BeijingChina school of mechanical engineering and Automation Beihang UniversityBeijingChina State Key Laboratory of Oral&Maxillofacial Reconstruction and Regeneration National Clinical Research Center for Oral DiseasesShaanxi Key Laboratory of StomatologyDigital CenterSchool of StomatologyThe Fourth Military Medical UniversityXi’anChina Key Laboratory of Biomechanics and Mechanobiology of the Ministry of Education Beijing Advanced Innovation Center for Biomedical EngineeringSchool of Biological Science and Medical EngineeringBeihang UniversityBeijingChina

Accurate segmentation of oral surgery-related tissues from cone beam computed tomography(CBCT)images can significantly accelerate treatment planning and improve surgical *** this paper,we propose a fully automated tissue segmentation system for dental implant ***,we propose an image preprocessing method based on data distribution histograms,which can adaptively process CBCT images with different *** on this,we use the bone segmentation network to obtain the segmentation results of alveolar bone,teeth,and maxillary *** use the tooth and mandibular regions as the ROI regions of tooth segmentation and mandibular nerve tube segmentation to achieve the corresponding *** tooth segmentation results can obtain the order information of the *** corresponding experimental results show that our method can achieve higher segmentation accuracy and efficiency compared to existing *** average Dice scores on the tooth,alveolar bone,maxillary sinus,and mandibular canal segmentation tasks were 96.5%,95.4%,93.6%,and 94.8%,*** results demonstrate that it can accelerate the development of digital dentistry.

关键词： surgery CBCT beam

FLOW PATTERNS AND FORCE CHARACTERISTICS OF LAMINAR FLOW PAST FOUR CYLINDERS IN DIAMOND ARRANGEMENT

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Journal of Hydrodynamics 2011年第1期23卷 55-64页

作者： ZOU Lin LIN yu-feng LU Hong school of mechanical and Electronic engineering Wuhan University of Technology Wuhan 430070 China Department of mechanical engineering The Hong Kong Polytechnic University Hong Kong China

A three-dimensional numerical investigation of cross-flow past four circular cylinders in a diamond arrangement at Reynolds number of 200 is carried *** the spacing ratios（L /D）ranging from 1.2 to 5.0,the flow patterns can be classified into three basic *** critical spacing ratio for the transition from narrow gap flow pattern to vortex impingement flow pattern around the cylinders is found to beL /D=3.0,while a single bluff-body flow pattern is observed atL /D=*** relationship between the three-dimensional flow patterns and force characteristics around the four cylinders shows that the variation of forces and Strouhal numbers againstL /D are generally governed by these three kinds of flow *** is concluded that the spacing ratio has important effects on the development of the free shear layers about the cylinders and hence has significant effects on the force and pressure characteristics of the four cylinders with different spacing ratios.

关键词： four cylinders spacing ratio flow pattern force characteristics

A Fast RLE-based Reconstruction Technique for Real-time Robot Tracking

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武汉理工大学学报 2006年第S2期28卷 582-585页

作者： yu wenyong SHI Hui (school of mechanical engineering,wuhan university of technology,wuhan 430070,china school of mechanical engineering Wuhan University of TechnologyWuhan 430070China

Wheeled Mobile Robots (WMRs) are more and more widely used in advanced *** real time tracking of WMRs,a novel way for real-time color image reconstruction based on Run Length Encoding (RLE) is ***- dexed from a fast look up table (FLUT),color image can be encoded into multiple llne structures with different specified colors. Through object-oriented method,the RLE elements reconstruct the image *** application of this technique for mo- bile robots identification is reported.

关键词： machine vision mobile Robot RLE

Experimental research on characteristics of hole reaming and side cutting of one-cone bits

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Petroleum science 2008年第3期5卷 280-284页

作者： yu Kai＇an school of mechanical and Electronic engineering China University of Petroleum Beijing 102249 China

The hole reaming and side cutting characteristics of offset one-cone bit and conventional one- cone bit were investigated on simulated drilling experimental equipment. The borehole diameter was a little larger than the bit diameter due to side force. However, the reaming effect was not very apparent, whether drilling with an offset or conventional one-cone bit. The side cutting displacement increased gradually with increasing depth of drilling and side force. The side cutting displacement of offset onecone bits was larger than that of conventional ones under the same conditions of weight-on-bit （WOB）, rotary speed, side force and borehole depth.

关键词： Offset one-cone bit conventional one-cone bit hole reaming side cutting

The Remote Product Check and Acceptance technology Based on Web

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武汉理工大学学报 2006年第S1期28卷 335-338页

作者： YANG Musheng 1,2 ,ZHANG yu1 (1.school of mechanical engineering,Shandong university of technology,Zibo 255000,china 2.school of mechanical engineering,Nanjing university of science and technology, Nanjing 210094,china) school of mechanical engineering Shandong University of TechnologyZibo 255000China school of mechanical engineering Nanjing University of Science and TechnologyNanjing 210094China school of mechanical engineering Shandong University of TechnologyZibo 255000China

This paper analyzes the feasibility of the remote check and acceptance of product and presents an architecture through which the remote product check and acceptance system can be realized. This paper also illuminates the work process of this system and discusses the technological details of the quality inspection as well as the key technologies.

关键词： remote check and acceptance remote control e-purchase statistical process control

Rock matrix-fractured media model for heterogeneous and fractured coal bed

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中国有色金属学会会刊：英文版 2011年第S3期21卷 621-625页

作者： ZHANG Chun-hui1, yu Guang-ming2, ZHANG Chun1 1. school of Civil engineering, Hebei university of science and technology, Shijiazhuang 050018, china 2. school of Civil engineering, Qingdao Technological university, Qingdao 266033, china [a] school of Civil engineering Hebei University of Science and Technology Shijiazhuang 050018 China [b] school of Civil engineering Qingdao Technological University Qingdao 266033 China

Coal was considered rock matrix-fractured media composed of rock matrix and fractures, and the rock matrix-fractured media model for heterogeneous and fractured coal bed was presented. In this model the rock matrix is heterogeneous, and the mechanical parameters such as elastic modulus and strength follow Weibull distribution. Fractures in coal bed were generated with the discrete fracture network method, and the properties of fractures were simulated with Desai element. Then the virtual generating system (VGS) of natural heterogeneous and fractured coal bed was developed in Matlab 6.0. The coupled model of gas flow and deformation process based on the rock matrix-fractured media model method and VGS for heterogeneous and fractured coal bed was presented, and the numerical code was developed in Matlab 6.0. The gas flow process in the heterogeneous and fractured coal bed was simulated in a numerical case. The main conclusions are: 1) The natural heterogeneous and fractured coal bed could be simulated by the rock matrix-fractured media model and VGS; 2) The fractures connected with the well have much more effects on gas flow than those non-connected.

关键词： heterogeneity fractures rock matrix-fractured media

Preparation and Characterization of Polylactide/Montmorillonite Nanocomposites

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Journal of wuhan university of technology(Materials science) 2009年第4期24卷 562-565页

作者：吴选军 school of Chemical engineering Wuhan University of Technology

The montmorillonite, a form of layered silicate, was successfully intercalated into polylactide （PLA） matrix through solvent-casting technique. In addition, PLA/MMT nanocomposite films were produced, in which homogenous distribution of the silicate lamellae plays a key role in the mechanical properties of the films. A small amount（5wt%） of OMMT intercalated into the PLA matrix resulted in their flexibility enhancement, from 3.68%（pure PLA film） to 352.65%. The results of wide-angle X-ray diffraction （WAXD） patterns confirmed that the silicate interlayer distance increased from 3.044 nm （for OMMT） to 3.56nm （for 5wt%, maximum） with increasing OMMT contents, but decreased to 3.319 nm when OMMT content was over 8wt%. FT-IR also verified the molecular-level associations between PLA chains and OMMT lamellae by vibration variances of hydrogen bonding. DSC thermograms demonstrated that thermal stabilities of the nanocomposite films enhanced, due to the silicate lamellae dispersed into PLA matrix.

关键词： polylactide montmorillonite nanocomposite characterization thermo-mechanic at property

Study on Contact Fatigue Life and Failure Mechanism of Subquenched 42CrMo Steel

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材料热处理学报 2004年第5期25卷 260-262页

作者： HEBo-lin yuYing-xia SHAOEr-yu schoolofmechanical＆Electricalengineering EastChinaJiaotongUniversityNanchangChina MaterialInstitute HenanUniversityofScienceandTechnologyLuoyangChina

The effect of undissolved ferrite amount in subcritically quenched 42CrMo steel on contact fatigue properties and failure mechanism were studied. The amount of undissolved ferrite in the steel were 0%,3%,10%,15% and 20% in volume fraction, respectively. The experimental results show that the existence of undissolved ferrite can increase the contact fatigue life The contact fatigue life can be prolonged with increasing the amounts of undissolved ferrite The grain size can be fined by using subcritical quenching process and the area of phase boundaries can also be greatly increased. The stress relaxation and grain refinement due to occurring of plastic deformation are main reasons for improving the fatigue life. The existence of undissolved ferrite can increase the crack initiation period. Under the experiment conditions, when the amount of undissolved ferrite is 10%, the longest contact fatigue life can be the obtained.

关键词：亚临界灭弧接触疲劳失效机理铁素体 42CrMo钢