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image-based modelling and analysis of microstructures for two-scale problems in geomechanics

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS 2002年第3期26卷 273-297页

作者： Terada, K Kyoya, T Kazama, M Lee, K Oyang, L Tohoku Univ Dept Civil Engn Aoba Ku Sendai Miyagi 9808579 Japan Seoul Natl Univ Dept Civil Engn Seoul 151742 South Korea Kajima Corp Tohoku Branch Sendai Miyagi 9800802 Japan

This paper focuses on the geometry modelling and numerical analysis of microstructures of geomaterials employing the concept of image-based engineering. The novel modelling and analysis techniques with digital images are incorporated with the mathematical homogenization method to study the interaction between individual phases, each of whose shape and spatial distribution are irregular. Owing to the distinctive features of these computational techniques, the evaluation of homogenized properties for geomaterials provides the reliable information about the micro- or macroscopic mechanical behaviours for engineering practice. It is, naturally, inevitable that engineers' demands on safety and efficient design place emphasis on quantitative estimates for these values. Thus, calibration accompanied with actual measurements comes within the scope of this study so that these properties would be realistic and practical from the engineering viewpoints. Copyright (C) 2002 John Wiley Sons, Ltd.

关键词： image-based modelling numerical model of microstructures homogenization method digital images

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image-based modelling FROM UNMANNED AERIAL VEHICLE (UAV) PHOTOGRAMMETRY: AN EFFECTIVE, LOW-COST TOOL FOR ARCHAEOLOGICAL APPLICATIONS

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ARCHAEOMETRY 2015年第1期57卷 128-145页

作者： Fernandez-Hernandez, J. Gonzalez-Aguilera, D. Rodriguez-Gonzalvez, P. Mancera-Taboada, J. Univ Salamanca Dept Cartog & Land Engn C Hornos Caleros 50 Avila 05003 Spain

The recording and 3D modelling of complex archaeological sites is usually associated with high capital and logistical costs, because the data acquisition must be performed by specialists using expensive surveying sensors (i.e., terrestrial laser scanners, robotic total stations and/or ground-penetrating radar). This paper presents a novel, low-cost, user-friendly photogrammetric tool for generating high-resolution and scaled 3D models of complex sites. The results obtained with unmanned aerial vehicle (UAV) photogrammetry of an archaeological site indicate that this approach is semi-automatic, inexpensive and effective, and that it guarantees quality.

关键词： Unmanned aerial vehicle (UAV) archaeology software development image-based modelling photogrammetry computer vision

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image-based modelling of organogenesis

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BRIEFINGS IN BIOINFORMATICS 2016年第4期17卷 616-627页

作者： Iber, Dagmar Karimaddini, Zahra Unal, Erkan St Johns Coll Oxford England Swiss Fed Inst Technol Zurich Switzerland Univ Zurich CH-8006 Zurich Switzerland

One of the major challenges in biology concerns the integration of data across length and time scales into a consistent framework: how do macroscopic properties and functionalities arise from the molecular regulatory networks-and how can they change as a result of mutations? Morphogenesis provides an excellent model system to study how simple molecular networks robustly control complex processes on the macroscopic scale despite molecular noise, and how important functional variants can emerge from small genetic changes. Recent advancements in three-dimensional imaging technologies, computer algorithms and computer power now allow us to develop and analyse increasingly realistic models of biological control. Here, we present our pipeline for image-based modelling that includes the segmentation of images, the determination of displacement fields and the solution of systems of partial differential equations on the growing, embryonic domains. The development of suitable mathematical models, the data-based inference of parameter sets and the evaluation of competing models are still challenging, and current approaches are discussed.

关键词： image-based modelling computational biology developmental biology

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Three-dimensional observation and image-based modelling of thermal strains in polycrystalline alumina

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ACTA MATERIALIA 2013年第20期61卷 7521-7533页

作者： Gonzalez, D. King, A. Mostafavi, M. Reischig, P. du Roscoat, S. Rolland Ludwig, W. da Fonseca, J. Quinta Withers, P. J. Marrow, T. J. Univ Manchester Sch Mat Manchester M13 9PL Lancs England Univ Oxford Dept Engn Sci Oxford OX1 3PJ England ESRF F-38000 Grenoble France Univ Oxford Dept Mat Oxford OX1 3PH England Univ Grenoble 1 Lab R 3S F-38041 Grenoble France INSA Lyon GEMPPM MATEIS Lyon France

Diffraction contrast tomography (DCT) with synchrotron X-rays was used to map the three-dimensional microstructure of alumina. Each grain boundary (GB) of this coarse-grained ceramic was characterized by its orientation and the crystal misorientation of the adjacent grains. The microstructure of alumina was sufficiently well described by DCT to produce a microstructurally representative image-based finite-element model comprising similar to 400 grains. Grain boundary cohesive elements were used to calculate the local thermal stresses acting on each GB arising from the crystal anisotropy. Digital volume correlation of the CT images was used to gauge the degree of bending induced during loading and to extract polycrystalline elastic properties. The model simulations showed the average intergranular stress to be influenced by the orientation of the GB plane relative to the basal planes of the adjacent grains. Boundaries to which at least one of the basal planes was closely aligned tended to develop higher tensile stress;these boundaries were predicted to have a tendency for intergranular fracture. Under compressive loading, the normal stresses of the boundaries that cracked were slight more tensile relative to the general population due to grain-to- grain interactions. The predicted effect of crystal lattice strains and rotations on diffraction, due to the modelled thermal stresses, showed general agreement with the observed X-ray diffraction images of individual grains. (C) 2013 Published by Elsevier Ltd. on behalf of Acta Materialia Inc.

关键词： Alumina Diffraction contrast tomography Synchrotron X-ray residual stress image-based modelling

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Stochastic multi-scale prediction on the apparent elastic moduli of trabecular bone considering uncertainties of biological apatite (BAp) crystallite orientation and image-based modelling

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COMPUTER METHODS IN BIOMECHANICS AND BIOMEDICAL ENGINEERING 2015年第2期18卷 162-174页

作者： Basaruddin, Khairul Salleh Takano, Naoki Nakano, Takayoshi Keio Univ Grad Sch Sci & Technol Yokohama Kanagawa 2238522 Japan Keio Univ Dept Mech Engn Yokohama Kanagawa 2238522 Japan Osaka Univ Div Mat & Mfg Sci Suita Osaka 5650871 Japan Univ Malaysia Perlis Sch Mechatron Engn Ulu Pauh 02600 Perlis Malaysia

An assessment of the mechanical properties of trabecular bone is important in determining the fracture risk of human bones. Many uncertainty factors contribute to the dispersion of the estimated mechanical properties of trabecular bone. This study was undertaken in order to propose a computational scheme that will be able to predict the effective apparent elastic moduli of trabecular bone considering the uncertainties that are primarily caused by image-based modelling and trabecular stiffness orientation. The effect of image-based modelling which focused on the connectivity was also investigated. A stochastic multi-scale method using a first-order perturbation-based and asymptotic homogenisation theory was applied to formulate the stochastically apparent elastic properties of trabecular bone. The effective apparent elastic modulus was predicted with the introduction of a coefficient factor to represent the variation of bone characteristics due to inter-individual differences. The mean value of the predicted effective apparent Young's modulus in principal axis was found at approximately 460MPa for respective 15.24% of bone volume fraction, and this is in good agreement with other experimental results. The proposed method may provide a reference for the reliable evaluation of the prediction of the apparent elastic properties of trabecular bone.

关键词： image-based modelling uncertainties stochastic multi-scale analysis apparent elastic moduli trabecular bone

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An X-FEM and level set computational approach for image-based modelling: Application to homogenization

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INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING 2011年第7期86卷 915-934页

作者： Legrain, G. Cartraud, P. Perreard, I. Moes, N. Univ Nantes GeM Inst UMR CNRS 6183 Ecole Cent NantesCNRS F-44321 Nantes France Dartmouth Coll Hitchcock Med Ctr Dartmouth Med Sch Hanover NH 03756 USA

The advances in material characterization by means of imaging techniques require powerful computational methods for numerical analysis. The present contribution focuses on highlighting the advantages of coupling the extended finite elements method and the level sets method, applied to solve microstructures with complex geometries. The process of obtaining the level set data starting from a digital image of a material structure and its input into an extended finite element framework is presented. The coupled method is validated using reference examples and applied to obtain homogenized properties for heterogeneous structures. Although the computational applications presented here are mainly two-dimensional, the method is equally applicable for three-dimensional problems. Copyright (C) 2010 John Wiley & Sons, Ltd.

关键词： image-based modelling X-FEM level sets homogenization

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Comparison of advanced discretization techniques for image-based modelling of heterogeneous porous rocks

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ACTA GEOTECHNICA 2020年第1期15卷 57-77页

作者： Kamel, Karim Ehab Moustafa Colliat, Jean-Baptiste Gerard, Pierre Massart, Thierry J. Univ Libre Bruxelles BATir Bldg Architecture & Town Planning CP 194-2 B-1050 Brussels Belgium Univ Lille Lab Mecan Cent Lille CNRSMultiechelleMultiphys Lille France

This contribution presents an assessment of computational techniques enabling automated simulations of complex porous rocks microstructures based on 3D imaging techniques. A subset of a CT-scanned sandstone sample is used to compare the results obtained by two advanced discretization frameworks. Raw scan results are processed by a level-set-based segmentation technique to produce smooth geometries prone to finite element discretizations. A recently developed technique is outlined for conforming mesh generation for complex porous geometries described implicitly by functions. This allows generating high-quality tetrahedral meshes with selective refinement. Next to this, a technique that uses a kinematic enrichment by incompatible modes to represent the heterogeneous geometry is explained. Both techniques use the same implicit geometry as main input for the simulations. Mechanical simulations are conducted on a subset of a scanned sample of a sandstone under triaxial loading conditions for isotropic compressive loading and for loading conditions involving a stress deviator. The results are compared and discussed based on local stress distributions and on a Mohr-Coulomb criterion with tensile cut-off. The results show that both discretization strategies yield complementary tools and allow envisioning automated simulations based on raw CT scan data for porous rocks exhibiting complex pore space morphologies.

关键词： Automated meshing CT scan Embedded discontinuities Finite elements image-based modelling Porous rocks Rock mechanics

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Capturing the Past for the Future: an Evaluation of the Effect of Geometric Scan Deformities on the Performance of Aerial Archival Media in image-based modelling Environments

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Archaeological Prospection 2016年第4期23卷 325-334页

作者： Sevara, Christopher Univ Vienna Vienna Inst Archaeol Sci Initiat Coll Archaeol Prospect Vienna Austria

image-based modelling (IBM) applications can be used to successfully extract two-and three-dimensional information from historic aerial and satellite imagery for use in archaeological and other landscape-oriented research. The robust and highly automated nature of these applications can allow for image matching and dense scene reconstruction, even when input images lack information necessary for processing in traditional photogrammetric workflows. However, the overall quality of the content derived from IBM applications can be directly influenced by a number of variables, including the manner in which archival content is digitized. Significant geometric distortion can be induced in the scanning process when using non-photogrammetric scanning devices, which can have a negative effect on the subsequent processing of scanned imagery and accuracy of derived content such as orthomosaics and digital elevation models (DEMs). While this is a well-known issue for users of high end photogrammetry packages, the advent of IBM applications has brought the use of photogrammetric-style techniques to a wider audience who may not be aware of the impact that geometric errors of this nature can have on the quality of derived data products. This issue is demonstrated here using a set of degraded historic World War II (WWII) Allied reconnaissance photographs that have been digitized on both photogrammetric and non-photogrammetric platforms and subsequently processed in a well-known IBM application using identical processing parameters. The results are compared to those from a recently collected set of vertical stereopairs and an airborne laser scan derived DEM. Copyright (C) 2016 John Wiley & Sons, Ltd.

关键词： Digitization photogrammetry image-based modelling historic aerial photographs distortion terrain

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Influence of dental restorations and mastication loadings on dentine fatigue behaviour: image-based modelling approach

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JOURNAL OF DENTISTRY 2015年第5期43卷 556-567页

作者： Vukicevic, Arso M. Zelic, Ksenija Jovicic, Gordana Djuric, Marija Filipovic, Nenad Univ Kragujevac Fac Engn Kragujevac 34000 Serbia Bioengn Res & Dev Ctr Kragujevac Kragujevac 34000 Serbia Univ Belgrade Sch Med Inst Anat Lab Anthropol Belgrade 11000 Serbia

Objectives: The aim of this study was to use Finite Element Analysis (FEA) to estimate the influence of various mastication loads and different tooth treatments (composite restoration and endodontic treatment) on dentine fatigue. The analysis of fatigue behaviour of human dentine in intact and composite restored teeth with root-canal-treatment using FEA and fatigue theory was performed. Methods: Dentine fatigue behaviour was analysed in three virtual models: intact, composite restored and endodontically-treated tooth. Volumetric change during the polymerization of composite was modelled by thermal expansion in a heat transfer analysis. Low and high shrinkage stresses were obtained by varying the linear shrinkage of composite. Mastication forces were applied occlusally with the load of 100, 150 and 200 N. Assuming one million cycles, Fatigue Failure Index (FFI) was determined using Goodman's criterion while residual fatigue lifetime assessment was performed using Paris-power law. Results: The analysis of the Goodman diagram gave both maximal allowed crack size and maximal number of cycles for the given stress ratio. The size of cracks was measured on virtual models. For the given conditions, fatigue-failure is not likely to happen neither in the intact tooth nor in treated teeth with low shrinkage stress. In the cases of high shrinkage stress, crack length was much larger than the maximal allowed crack and failure occurred with 150 and 200 N loads. The maximal allowed crack size was slightly lower in the tooth with root canal treatment which induced somewhat higher FFI than in the case of tooth with only composite restoration. Conclusions: Main factors that lead to dentine fatigue are levels of occlusal load and polymerization stress. However, root canal treatment has small influence on dentine fatigue. Clinical significance: The methodology proposed in this study provides a new insight into the fatigue behaviour of teeth after dental treatments. Furthermore, it esti

关键词： Human dentine image-based modelling Finite element method Fatigue Mastication

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image-based modelling of skeletal muscle oxygenation

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JOURNAL OF THE ROYAL SOCIETY INTERFACE 2017年第127期14卷 20160992-20160992页

作者： Zeller-Plumhoff, B. Roose, T. Clough, G. F. Schneider, P. Helmholtz Zentrum Mat & Kustenforschung Geesthacht Germany Univ Southampton Bioengn Res Grp Fac Engn & Environm Southampton Hants England Univ Southampton Bioengn Res Grp Fac Engn & Environm Southampton Hants England

The supply of oxygen in sufficient quantity is vital for the correct functioning of all organs in the human body, in particular for skeletal muscle during exercise. Disease is often associated with both an inhibition of the microvascular supply capability and is thought to relate to changes in the structure of blood vessel networks. Different methods exist to investigate the influence of the microvascular structure on tissue oxygenation, varying over a range of application areas, i.e. biological in vivo and in vitro experiments, imaging and mathematical modelling. Ideally, all of these methods should be combined within the same framework in order to fully understand the processes involved. This review discusses the mathematical models of skeletal muscle oxygenation currently available that are based upon images taken of the muscle microvasculature in vivo and ex vivo. Imaging systems suitable for capturing the blood vessel networks are discussed and respective contrasting methods presented. The review further informs the association between anatomical characteristics in health and disease. With this review we give the reader a tool to understand and establish the workflow of developing an image-based model of skeletal muscle oxygenation. Finally, we give an outlook for improvements needed for measurements and imaging techniques to adequately investigate the microvascular capability for oxygen exchange.

关键词： skeletal muscle vasculature oxygenation imaging image-based modelling computational modelling

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