The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Claude Laurent Benhamou - One of the best experts on this subject based on the ideXlab platform.
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A new Anisotropy index on trabecular bone radiographic images using the fast Fourier transform
BMC Medical Imaging, 2005Co-Authors: Barbara Brunet-imbault, Gérald Lemineur, Christine Chappard, Rachid Harba, Claude Laurent BenhamouAbstract:Background The Degree of Anisotropy (DA) on radiographs is related to bone structure, we present a new index to assess DA.
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simulation of osteoporosis bone changes effects on the Degree of Anisotropy
Advances in Experimental Medicine and Biology, 2001Co-Authors: Laurent Pothuaud, P Levitz, Claude Laurent BenhamouAbstract:Osteoporosis is characterized by several kinds of microarchitecture changes, such as thinning or disconnection of trabeculae, or increase of resorption lacunae.l-3The first characterization of these trabecular bone alterations has been obtained by histomorphometry.4-7Several parameters characterizing the 3D microarchitecture of the trabecular bone network are available.8-12The most relevant parameters following the last years’ studies are the volume fraction of solid (Bv/Tv: Bone Volume/Total Volume)13-15the connectivity12,16and the Anisotropy.17-20These three parameters determine the mechanical properties of the trabecular bone micro-architecture.21
Philippe K Zysset - One of the best experts on this subject based on the ideXlab platform.
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Measurement of structural Anisotropy in femoral trabecular bone using clinical-resolution CT images
Journal of Biomechanics, 2013Co-Authors: Mariana E. Kersh, Dieter H Pahr, Philippe K Zysset, Uwe Wolfram, David Larsson, Marcus G. PandyAbstract:Discrepancies in finite-element model predictions of bone strength may be attributed to the simplified modeling of bone as an isotropic structure due to the resolution limitations of clinical-level Computed Tomography (CT) data. The aim of this study is to calculate the preferential orientations of bone (the principal directions) and the extent to which bone is deposited more in one direction compared to another (Degree of Anisotropy). Using 100 femoral trabecular samples, the principal directions and Degree of Anisotropy were calculated with a Gradient Structure Tensor (GST) and a Sobel Structure Tensor (SST) using clinical-level CT. The results were compared against those calculated with the gold standard Mean-Intercept-Length (MIL) fabric tensor using micro-CT. There was no significant difference between the GST and SST in the calculation of the main principal direction (median error=28°), and the error was inversely correlated to the Degree of transverse isotropy (r=−0.34, p
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principal stiffness orientation and Degree of Anisotropy of human osteons based on nanoindentation in three distinct planes
Journal of The Mechanical Behavior of Biomedical Materials, 2011Co-Authors: Andreas Reisinger, Dieter H Pahr, Philippe K ZyssetAbstract:Haversian systems or ‘osteons’ are cylindrical structures, formed by bone lamellae, that make up the major part of human cortical bone. Despite their discovery centuries ago in 1691 by Clopton Havers, their mechanical properties are still poorly understood. The objective of this study is a detailed identification of the anisotropic elastic properties of the secondary osteon in the lamella plane. Additionally, the principal material orientation with respect to the osteon is assessed. Therefore a new nanoindentation method was developed which allows the measurement of indentation data in three distinct planes on a single osteon. All investigated osteons appeared to be anisotropic with a preferred stiffness alignment along the axial direction with a small average helical winding around the osteon axis. The mean Degree of Anisotropy was 1.75 ± 0.36 and the mean helix angle was 10.3°±0.8°. These findings oppose two well established views of compact bone microstructure: first, the generally clear axial stiffness orientation contradicts a regular ‘twisted plywood’ collagen fibril orientation pattern in lamellar bone that would lead to a more isotropic behavior. Second, the class of transverse osteons were not observed from the mechanical point of view.
Emilie Poullain - One of the best experts on this subject based on the ideXlab platform.
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Anisotropic Surface Detection Over Coastal Environment Using Near-IR LiDAR Intensity Maps
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2015Co-Authors: Franck Garestier, Patrice Bretel, Olivier Monfort, Franck Levoy, Emilie PoullainAbstract:Near-IR LiDAR intensity maps have been investigated to detect surfaces characterized by spatially anisotropic properties. The developed estimators present an important sensitivity to the surface anisotropic properties (Degree of Anisotropy and relative Anisotropy) and can be corrected for signal-to-noise ratio, which can be highly variable over coastal environments due to heterogeneous moisture distribution in space and time. Two methodologies are proposed to investigate the data in order to unambiguously characterize the surface anisotropic properties by separating the pure textural information from the amplitude weighted one, which provides a more relevant information in geomorphology than the pure texture. As an example, data acquired over sandy beaches are considered to illustrate the potential of surface characterization using both Degree of Anisotropy and associated texture amplitude. Sea surfaces are also investigated to show how does the pure texture approach allow to discriminate different sea states.
L. Hubert-moy - One of the best experts on this subject based on the ideXlab platform.
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Vineyard identification and characterization based on texture analysis in the Helderberg Basin (South Africa)
2010 IEEE International Geoscience and Remote Sensing Symposium, 2010Co-Authors: A. Lefebvre, T. Corpetti, V. Bonnardot, H. Quénol, L. Hubert-moyAbstract:In this paper, a methodology for the spatial identification and characterization of vineyards using texture analysis is proposed to meet the need of ongoing and further viticultural “terroir” studies. The proposed method is based on the maximization of a criteria that deals with the coefficients enclosed in the different bands of a wavelet decomposition of the original image. More precisely, we search for the orientation that best concentrates the energy of the coefficients in a single direction. For each texture pattern, a Degree of Anisotropy and the angle of the main orientation is extracted. The methodology is validated on aerial-photographs in the Helderberg Basin (South Africa). The Degree of Anisotropy is a reliable information able to discriminate vineyards to other land-uses. Moreover, the row orientation turns out to be a relevant information for all applications related to mesoscale atmospheric modeling in vineyard areas.
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IGARSS - Vineyard identification and characterization based on texture analysis in the Helderberg Basin (South Africa)
2010 IEEE International Geoscience and Remote Sensing Symposium, 2010Co-Authors: A. Lefebvre, T. Corpetti, V. Bonnardot, H. Quénol, L. Hubert-moyAbstract:In this paper, a methodology for the spatial identification and characterization of vineyards using texture analysis is proposed to meet the need of ongoing and further viticultural “terroir” studies. The proposed method is based on the maximization of a criteria that deals with the coefficients enclosed in the different bands of a wavelet decomposition of the original image. More precisely, we search for the orientation that best concentrates the energy of the coefficients in a single direction. For each texture pattern, a Degree of Anisotropy and the angle of the main orientation is extracted. The methodology is validated on aerial-photographs in the Helderberg Basin (South Africa). The Degree of Anisotropy is a reliable information able to discriminate vineyards to other land-uses. Moreover, the row orientation turns out to be a relevant information for all applications related to mesoscale atmospheric modeling in vineyard areas.
Damodar R Ambur - One of the best experts on this subject based on the ideXlab platform.
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influence of bolt spacing and Degree of Anisotropy in single lap joints
Computers & Structures, 2000Co-Authors: B Sergeev, Erdogan Madenci, Damodar R AmburAbstract:Abstract This study concerns the effect of bolt spacing and Degree of Anisotropy on the bolt load distribution and nature of the failure mechanism. Bolt loads and failure prediction are determined using a solution method that treats the contact stresses and contact region as unknowns. Utilizing the boundary collocation technique, this method provides the non-linear solution while capturing the effects of finite geometry under general loading conditions. The nature of the failure mechanism is established by using the maximum strain criterion. Comparison of the predictions with experimental results reveals their close agreement.
