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Automatic Bone Surface Restoration for Markerless Computer-Assisted Orthopaedic Surgery

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Chinese Journal of Mechanical Engineering 2022年第1期35卷 85-90页

作者： Xue Hu Ferdinando Rodriguez y Baena Mechatronics in Medicine Laboratory Imperial College LondonLondonUK

An automatic markerless knee tracking and registration algorithm has been proposed in the literature to avoid the marker insertion required by conventional computer-assisted knee surgery,resulting in a shorter and less invasive surgical ***,such an algorithm considers intact femur geometry *** bone surface modification is inevitable due to intra-operative *** mismatched correspondences will degrade the reliability of registered target *** solve this problem,this work proposed a supervised deep neural network to automatically restore the surface of processed *** network was trained on a synthetic dataset that consists of real depth captures of a model leg and simulated realistic femur *** to the evaluation on both synthetic data and real-time captures,the registration quality can be effectively improved by surface *** improvement in tracking accuracy is only evident over test data,indicating the need for future enhancement of the dataset and network.

关键词： Bone surface reconstruction Computer assisted orthopedic surgery Markerless femur tracking

Revealing the contribution of basilar membrane's biological activity to the mechanism of the cochlear phonosensitive amplification

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Applied Mathematics and Mechanics(English Edition) 2023年第5期44卷 823-840页

作者： J.y.LIANG Wenjuan yAO Genomic Medicine Institute Lerner Research InstituteCleveland Clinic FoundationClevelandOH 44106U.S.A. Shanghai Institute of Applied Mathematics and Mechanics Shanghai UniversityShanghai 200072China School of Mechanics and Engineering Science Shanghai UniversityShanghai 200072China

Explaining the mechanism of the cochlear active phonosensitive amplification has been a major problem in *** basilar membrane(BM)is the key *** 1960,Nobel Laureate von B′ek′esy first discovered BM's traveling wave *** that time,BM's models only have considered the traveling wave but not the biological ***,a new model considering changes of BM's stiffness in space and time is established based on the immersed boundary method to describe its biological *** not only reproduces the results of traveling wave motion but also explains the mechanization on the generation of traveling *** important discovery is that changes of BM's stiffness in space and time will cause the unstable global resonance,which will induce amplification of sounds in *** important inference is that biological activity shall be included in the application of mechanical principles to the analysis of life,which is the essential difference between biomechanics and general mechanics.

关键词： basilar membrane(BM) biological activity mechanical analysis cochlear phonosensitive amplification

Gradient Structured Copper by Rotationally Accelerated Shot Peening

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Journal of Materials Science & Technology 2017年第7期33卷 758-761页

作者： X.Wang y.S.Li Q.Z.ang y.H.Zhao y.T.Zhu Nano Structural Materials Center School of Materials Science and Engineering Nanjing University of Science and Technology Nanjing 210094 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing 210094 China Department of Materials Science and Engineering North Carolina State University Raleigh NC 27695 USA

A new technology-rotationally accelerated shot peening（RASP）, was developed to prepare gradient structured materials. By using centrifugal acceleration principle and large steel balls, the RASP technology can produce much higher impact energy compared to conventional shot peening. As a proof-of-concept demonstration, the RASP was utilized to refine the surface layer in pure copper（Cu） with an average grain size of 85 nm. The grain size increases largely from surface downwards the bulk, forming an800 ？m thick gradient-structured surface layer and consequently a micro-hardness gradient. The difference between the RASP technology and other established techniques in preparing gradient structured materials is discussed. The RASP technology exhibits a promoting future for large-scale manufacturing of gradient materials.

关键词： Microstructure Rotationally accelerated shot peening Gradient structure Hardness Copper

FEM SIMULATION FOR LASER FORMING PROCESSING

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Acta Metallurgica Sinica(English Letters) 2004年第3期17卷 317-322页

作者： L.Q.Li y.B.Chen X.y Wang S.y Lin State Key Laboratory of Advanced Welding Production Technology Harbin Institute of Technology Harbin 150001 China Harbin Research Institute of Welding Harbin 150001 ChinaState Key Laboratory of Advanced Welding Production Technology Harbin Institute of Technology Harbin 150001 China Harbin Research Institute of Welding Harbin 150001 ChinaHarbin Research Institute of Welding Harbin 150001 ChinaHarbin Research Institute of Welding Harbin 150001 China

Laser forming involves heating sheet metal workpiece along a certain path with adefocused laser beam directed irradiate to the surface. During laser forming, a tran-sient temperature fields is caused by the irradiation and travelling of a laser beam.Consequently, thermal expansion and contraction take place, and allows the thermal-mechanical forming of complex shapes. This is a new manufacturing technique thatforming metal sheet only by thermal stress. Therefore, the analysis of temperaturefields and stress fields are very useful for studying the forming mechanism and con-trolling the accuracy of laser forming. The non--liner finite element solver, MARC, isemployed to solve the thermal--mechanical analysis. Using this model, the stress andstrain distribution of pure aluminum plate with different thickness are analyzed. Theinfluence of scanning speed on temperature fields and plastic strain of metal sheet un-der the condition of constant line energy are also presented. Numerical results agreewell with the experimental results.

关键词： laser forming FEM simulation temperature fields stress distributton

SyNTHESIS AND MICROSTRUCTURE OF SUPERHARD TiN/SiN_x MULTILAyER THIN FILMS

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 242-248页

作者： Z.F.Zhou y.G.Shen y.W.Mai K.y.Li AdvancedCoatingsAppliedResearchLaboratory（ACARL） DepartmentofManufacturingEngineeringandEngineeringManagementCityUniversityofHongKongKowloonHongKongChina CentreforAdvancedMaterialsTechnology（CAMT） SchoolofAerospaceMechanicalandElectronicEngineeringUniversityofSydneySydneyNSW2006Australia

Multilayer thin films of TiN/SiNx have been deposited onto heated Si 100 substra tes (200℃) by reactive dc-magnetron sputtering from Ti and Si targets in an Ar- N2 gas mixture. The rotation speed of the substrate holder was varied from 1 to 20rpm, while target currents were held constant, to produce bilayer periods vary ing from approximately 22 to 0.6nm. These multilayer films were characterized by atomic force microscopy (AFM), cross-sectional transmission electron microscopy (TEM), scanning electron microscopy (SEM), and microhardness measurements. TEM and SEM studies showed elimination of columnar structure in TiN, owing to the in corporation of amorphous SiNx layers. The crystallinity of TiN and amorphous nat ure of SiNx were confirmed by high resolution TEM. An optimum rotation speed was observed, at which hardness was a maximum. The resulting bilayer period was fou nd to be approximately 1.6nm, which resulted in a significant improvement in mic rohardness (~57GPa). The rms surface roughness for this film was less than 1.5nm .

关键词： multilayers hardness supermodulu s stress TiN/SiNx

PREDICTION OF CARBON CONCENTRATION AND FERRITE VOLUME FRACTION OF HOT-ROLLED STEEL STRIP DURING LAMINAR COOLING

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Acta Metallurgica Sinica(English Letters) 2007年第4期20卷 251-257页

作者： y.T. Zhang C.Z. Wang D.Z. Li y.y. Li School of Material Science and Engineering Shenyang Ligong University Shenyang 110168 China Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

A phase transformation model was presented for predicting the phase fraction transformed and the carbon concentration in austenite for austenite to ferrite transformation during laminar cooling on run-out table in hot rolling strip mill. In this model, the parameter k in Avrami equation was developed for carbon steels. The wide range of chemical composition, the primary austenite grain size, and the retained strain were taken into account. It can be used to predict the ferrite volume fraction and the carbon concentration in austenite of hot-rolled steel strip during laminar cooling on run-out table. The coiling temperature controlling model was also presented to calculate the temperature of steel strip. The transformation kinetics of austenite to ferrite and the evolution of carbon concentration in austenite at different temperatures during cooling were investigated in the hot rolled Q235B strip for thickness of 9.35, 6.4, and 3.2mm. The ferrite volume fraction along the length of the strip was also calculated. The calculated ferrite volume fraction was compared with the log data from hot strip mill and the calculated results were in agreement with the experimental ones. The present study is a part of the prediction of the mechanical properties of hot-rolled steel strip, and it has already been used on-line and off-line in the hot strip mill.

关键词： carbon concentration ferrite volume fraction laminar cooling hot rolling

An electron moir■ method for a common SEM

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Acta Mechanica Sinica 2006年第6期22卷 595-602页

作者： y. M. Xing S. Kishimoto y. R. Zhao Department of Applied Mechanics Inner Mongolia University of Technology Hohhot 010051 China National Institute for Materials Sciences Tsukuba Ibaraki 305-0047 Japan

In the electron moiré method, a high-frequency grating is used to measure microscopic deformation, which promises significant potential applications for the method in the microscopic analysis of materials. However, a special beam scanning control device is required to produce a grating and generate a moiré fringe pattern for the scanning electron microscope （SEM）. Because only a few SEMs used in the material science studies are equipped with this device, the use of the electron moiré method is limited. In this study, an electron moiré method for a common SEM without the beam control device is presented. A grating based on a multi-scanning concept is fabricated in any observing mode. A real-time moiré pattern can also be generated in the SEM or an optical filtering system. Without the beam control device being a prerequisite, the electron moiré method can be more widely used. The experimental results from three different types of SEMs show that high quality gratings with uniform lines and less pitch error can be fabricated by this method, and moiré patterns can also be correctly generated.

关键词： Electron moiré Grating Multi-scanning Electron beam moiré

Effect of the Equilibrium Pair Separation on Cluster Structures

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Communications in Computational Physics 2009年第9期6卷 730-742页

作者： y.yang D.y.Sun State Key Laboratory of Precision Spectroscopy and Department of Physics East China Normal UniversityShanghai 200062China

The effect of the equilibrium pair separation on the evolution of cluster structures is investigated based on a new proposed pair *** computational results demonstrate that the potential with large equilibrium pair separation stabilizes decahedra and close-packed structures,while disordered structures appear for the potential with small equilibrium pair *** icosahedral clusters are dominated in the middle range of equilibrium pair *** the small size clusters(N≤24)the dominated structural motif is the polytetrahedra,which is almost independent of the details of the potential.

关键词： Cluster structure pair potential

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On B(5,20)2-Groups

Algebra Colloquium 2024年第3期31卷 429-440页

作者： E.A.Alhassan y.L.Tan y.Li School of Mathematical Sciences Jiangsu UniversityZhenjiangJiangsu 212013China Department of Mathematics Brock UniversitySt.CatharinesOntario L2S 3A1Canada

A finite group G is said to be a B(n,k)group if for any n-element subset[a_(1),…,a_(n)]of G,|{a_(i)a_(j)|1≤i,j≤n}|≤*** is of interest to characterize the structure of B(n,k)groups for n(n+1)/2≤k≤n^(2)-*** B(5,k)groups for 15≤k≤19 have been investigated by several *** this paper,we give a complete characterization of B(5,20)2-groups by showing there are five classes of such groups which are nontrivial and nonabelian.

关键词： B(n,k)groups small squaring property central extension GAP