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Application of digital image correlation to full-field measurement of shrinkage strain of dental composites

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第1期14卷 1-10页

作者： Jian-ying LI Andrew LAU Alex S. L. FOK Minnesota Dental Research Centre for Biomaterials and Biomechanics School of Dentistry University of Minnesota Minneapolis MN 55455 USA

Objectives： Polymerization shrinkage of dental composites remains a major concern in restorative dentistry because it can lead to micro-cracking of the tooth and debonding at the tooth-restoration interface. The aim of this study was to measure the full-field polymerization shrinkage of dental composites using the optical digital image correlation （DIC） method and to evaluate how the measurement is influenced by the factors in experiment setup and image analysis. Methods： Four commercial dental composites, Premise Dentine, Z 100, Z250 and Tetric EvoCeram, were tested. Composite was first placed into a slot mould to form a bar specimen with rectangular-section of 4 mmx2 mm, followed by the surface painting to create irregular speckles. Curing was then applied at one end of the specimen while the other part were covered against curing light for simulating the clinical curing condition of composite in dental cavity. The painted surface was recorded by a charge-coupled device （CCD） camera before and after curing. Subsequently, the volumetric shrinkage of the specimen was calculated with specialist DIC software based on image cross correlation. In addition, a few factors that may influence the measuring accuracy, including the subset window size, speckle size, illumination light and specimen length, were also evaluated. Results： The volumetric shrinkage of the specimen generally decreases with increasing distance from the irradiated surface with a conspicuous exception being the composite Premise Dentine as its maximum shrinkage occurred at a subsurface distance of about 1 mm instead of the irradiated surface. Z100 had the greatest maximum shrinkage strain, followed by Z250, Tetric EvoCeram and then Premise Dentine. Larger subset window size made the shrinkage strain contour smoother. But the cost was that some details in the heterogeneity of the material were lost. Very small subset window size resulted in a lot of noise in the data, making it difficult to discern the g

关键词： image correlation Dental composite Polymerization shrinkage Depth of cure

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Fluorescence and SEM correlative microscopy for nanomanipulation of subcellular structures

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Light(Science & Applications) 2014年第1期3卷 13-19页

作者： Zheng Gong Brandon K Chen Jun Liu Chao Zhou Dave Anchel Xiao Li Ji Ge David P Bazett-Jones Yu Sun Advanced Micro and Nanosystems Laboratory University of TorontoTorontoON M5S 3G8Canada State Key Laboratory of Intelligent Control and Management of Complex Systems Institute of AutomationChinese Academy of SciencesBeijing 100190China The Genetics and Genome Biology Program the Hospital for Sick ChildrenTorontoON M5G 1X8Canada

Nanomanipulation under scanning electron microscopy(SEM)enables direct interactions of a tool with a *** recently developed a nanomanipulation technique for the extraction and identification of DNA contained within sub-nuclear locations of a single cell *** nanomanipulation of sub-cellular structures,a key step is to identify targets of interest through correlating fluorescence and SEM *** DNA extraction task must be conducted with low accelerating voltages resulting in low imaging *** is imposed by the necessity of preserving the biochemical integrity of the *** poor imaging conditions make the identification of nanometer-sized fiducial marks *** paper presents an affine scale-invariant feature transform(ASIFT)based method for correlating SEM images and fluorescence microscopy *** performance of the image correlation approach under different noise levels and imaging magnifications was quantitatively *** optimal mean absolute error(MAE)of correlation results is 68634 nm under standard *** with manual correlation by skilled operators,the automated correlation approach demonstrates a speed that is higher by an order of *** the SEM-fluorescence image correlation approach,targeted DNA was successfully extracted via nanomanipulation under SEM conditions.

关键词： correlative microscopy fluorescence image correlation nanomanipulation SEM subcellular structures

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Physical investigation on the behaviours of voussoir beams

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第3期12卷 516-527页

作者： Chaoshi Hu Derek Apel Les Jozef Sudak Wei Victor Liu Zhaoyuan Chu School of Mining and Petroleum Engineering Department of Civil and Environmental EngineeringUniversity of AlbertaEdmontonT6G 1H9Canada Department of Mechanical and Manufacturing Engineering University of CalgaryCalgaryT2N 1N4Canada Anhui Yitong Construction Consulting and Management Ltd.YuexiAnqing246000China

It is important to understand the behaviour of voussoir beams in the design of underground *** are a large number of discrepancies between the re sults obtained by differe nt researchers so *** resolve these discrepancies,physically testing the stress distribution at the mid span and abutment of voussoir beam is the *** this paper,a simple two-block voussoir beam was built with loading *** displacement and strain of the voussoir beam were measured by a digital image correlation *** strain distribution along the joints of voussoir beams was firstly ***,the relationship between transverse load and midspan displacement of voussoir beam was *** is found that the stress distributions at the midspan and abutment are different both in shape and *** stress distribution is changing as the loading changes as well.

关键词： Voussoir beam Stress distribution image correlation

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DEFORMATION ANALYSIS OF SOIL MICROSTRUCTURE USING COMPUTER-ASSISTED TRACKING TECHNIQUE

DEFORMATION ANALYSIS OF SOIL MICROSTRUCTURE USING COMPUTER-A...

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庆祝中国力学学会成立50周年暨中国力学学会学术大会’2007

作者： WANG Wei~(*,1)) HUXin~(**) HONG Baoning~(**) HE Xiaoyuan~+ *(College of Architecture Engineering,Institute of Technology,Hohai University,Nanjing210098,China) **(Research Institute of Geotechnical Engineering,Hohai University,Nanjing 210098,China) +(Department of Engineering Mechanics,Southeast University,Nanjing 210096,China)

Deformation properties of soil microstructure have more significant effects on many engineering *** order to reveal the movement properties of soil particles under dynamic loading conditions, computer-assisted trackin... 详细信息

关键词： soil microstructure deformation properties computer-assisted tracking technique image correlation

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