The Experts below are selected from a list of 16395 Experts worldwide ranked by ideXlab platform
Wilfredo Moscoso - One of the best experts on this subject based on the ideXlab platform.
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Deformation Field in large strain extrusion machining and implications for Deformation processing
Scripta Materialia, 2012Co-Authors: Dinakar Sagapuram, Wilfredo Moscoso, Kevin P Trumble, Srinivasan ChandrasekarAbstract:The Deformation Field in large-strain extrusion machining, a constrained chip formation process, is characterized using high-speed imaging and particle image velocimetry. The Field is shown to be controllable and narrowly confined, with attributes ranging from conventional Deformation processing to severe plastic Deformation. Implications for Deformation processing of sheets, engineering of microstructures in bulk forms and on machined surfaces, and study of large-strain Deformation phenomena in metal alloys are highlighted.
Christophe Blondel - One of the best experts on this subject based on the ideXlab platform.
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4d Deformation Field of coronary arteries from monoplane rotational x ray angiography
Computer Assisted Radiology and Surgery, 2003Co-Authors: Christophe Blondel, Gregoire Malandain, Regis Vaillant, Nicholas AyacheAbstract:Abstract We present a new method to automatically compute a (3D+t) 4D parametric Deformation Field of coronary arteries from one single rotational X-ray angiography acquisition. We first build 3D centerline models of the coronary arteries and then compute 4D Deformations that make the 3D model fit the entire sequence, at all cardiac cycle phases. Taking advantage of the 4D Deformation Field knowledge, we propose a new clinical application in rotational X-ray angiography called “stabilized display”, presenting a focused and centered display of 3D points of interest. Results on patient data sets are presented.
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CARS - 4D Deformation Field of coronary arteries from monoplane rotational X-ray angiography
International Congress Series, 2003Co-Authors: Christophe Blondel, Gregoire Malandain, Regis Vaillant, Nicholas AyacheAbstract:Abstract We present a new method to automatically compute a (3D+t) 4D parametric Deformation Field of coronary arteries from one single rotational X-ray angiography acquisition. We first build 3D centerline models of the coronary arteries and then compute 4D Deformations that make the 3D model fit the entire sequence, at all cardiac cycle phases. Taking advantage of the 4D Deformation Field knowledge, we propose a new clinical application in rotational X-ray angiography called “stabilized display”, presenting a focused and centered display of 3D points of interest. Results on patient data sets are presented.
Srinivasan Chandrasekar - One of the best experts on this subject based on the ideXlab platform.
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Deformation Field in large strain extrusion machining and implications for Deformation processing
Scripta Materialia, 2012Co-Authors: Dinakar Sagapuram, Wilfredo Moscoso, Kevin P Trumble, Srinivasan ChandrasekarAbstract:The Deformation Field in large-strain extrusion machining, a constrained chip formation process, is characterized using high-speed imaging and particle image velocimetry. The Field is shown to be controllable and narrowly confined, with attributes ranging from conventional Deformation processing to severe plastic Deformation. Implications for Deformation processing of sheets, engineering of microstructures in bulk forms and on machined surfaces, and study of large-strain Deformation phenomena in metal alloys are highlighted.
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Deformation Field in Indentation of Granular Materials
AIP Conference Proceedings, 2009Co-Authors: Tejas G. Murthy, Ebenezer P. Gnanamanickam, Christopher Saldana, Srinivasan ChandrasekarAbstract:A preliminary study has been made of the Deformation Field in indentation of a model granular material using particle tracking optical flow analyses. A continuum composed of spherical sand particles with average size of 0.4 mm is indented with a flat punch under plane‐strain conditions. The region around the indenter/indentation is imaged in situ using a Charge‐Coupled Device (CCD) imaging system. By applying this hybrid analysis technique to image sequences of the indentation parameters of the Deformation Field such as displacement, velocity, and velocity gradient are measured at high spatial resolution. Implications of the measurement technique for accurate determination of local strain and strain rate, and exploring phenomena such as friction shear bands, in granular solids are briefly discussed.
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Characterization of Deformation Field in plane-strain indentation of metals
Journal of Physics D, 2008Co-Authors: Tejas G. Murthy, Chihyung Huang, Srinivasan ChandrasekarAbstract:A study has been made of the Deformation Field in plane-strain indentation of metals with a flat punch. Deformation Field parameters such as velocity and strain rate have been measured using the technique of particle image velocimetry. For this purpose, images of the indentation region were recorded in situ during the Deformation process, and motion of 'asperities' specially introduced onto a side of the sample being indented was analysed. The velocity and strain rate Fields in and around the indentation zone were obtained from an analysis of the asperity motions. The measurements have shown, among other things, the presence of a dead metal zone underneath the indenter, the formation and evolution of regions of intense strain rates or shear bands and a linear variation of the strain rate with indentation speed. Many of the characteristics of the Deformation Field, e.g. slip lines and dead metal zone, compare favourably with those inferred from classical solutions for this indentation problem. Extensions of the technique for the study of strain Field around indentations and Deformation in plane-strain indentation by wedges and cylinders are discussed.
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large strain Deformation Field in machining
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2006Co-Authors: Jihong Hwang, Srinivasan Chandrasekar, Ravi M Shankar, Dale W ComptonAbstract:Measurement of strain Field in the primary Deformation zone is of major interest for development of machining as an experimental technique for studying phenomena associated with large strain Deformation. A study has been made of the primary Deformation zone and tool-chip interface in planestrain (two-dimensional) machining of metals. The use of a high-speed, charge-coupled device (CCD) imaging system in conjunction with an optically transparent, sapphire cutting tool has enabled characteristics of the Deformation Field such as velocity, strain, and material flow, to be obtained at high spatial and temporal resolution. The velocity distributions in the primary Deformation zone and along the tool rake face have been obtained by applying a particle image velocimetry (PIV) technique to sequences of high-speed images of the chip-tool interface taken through the transparent tool, and of the primary Deformation zone recorded from a side of the workpiece. A procedure is presented and demonstrated for determining the strain and strain rate distributions in the primary Deformation zone. The measurements have provided data about the variations of velocity, strain rate, and strain, in and around the cutting edge and primary Deformation zone; confirmed the existence of a region of retarded sliding in the region of intimate contact between tool and chip; and highlighted the occurrence of a region of dead metal ahead of the cutting edge when cutting with a negative rake angle tool.
Nicholas Ayache - One of the best experts on this subject based on the ideXlab platform.
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4d Deformation Field of coronary arteries from monoplane rotational x ray angiography
Computer Assisted Radiology and Surgery, 2003Co-Authors: Christophe Blondel, Gregoire Malandain, Regis Vaillant, Nicholas AyacheAbstract:Abstract We present a new method to automatically compute a (3D+t) 4D parametric Deformation Field of coronary arteries from one single rotational X-ray angiography acquisition. We first build 3D centerline models of the coronary arteries and then compute 4D Deformations that make the 3D model fit the entire sequence, at all cardiac cycle phases. Taking advantage of the 4D Deformation Field knowledge, we propose a new clinical application in rotational X-ray angiography called “stabilized display”, presenting a focused and centered display of 3D points of interest. Results on patient data sets are presented.
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CARS - 4D Deformation Field of coronary arteries from monoplane rotational X-ray angiography
International Congress Series, 2003Co-Authors: Christophe Blondel, Gregoire Malandain, Regis Vaillant, Nicholas AyacheAbstract:Abstract We present a new method to automatically compute a (3D+t) 4D parametric Deformation Field of coronary arteries from one single rotational X-ray angiography acquisition. We first build 3D centerline models of the coronary arteries and then compute 4D Deformations that make the 3D model fit the entire sequence, at all cardiac cycle phases. Taking advantage of the 4D Deformation Field knowledge, we propose a new clinical application in rotational X-ray angiography called “stabilized display”, presenting a focused and centered display of 3D points of interest. Results on patient data sets are presented.
F H Cornet - One of the best experts on this subject based on the ideXlab platform.
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effects of topography on the interpretation of the Deformation Field of prominent volcanoes application to etna
Geophysical Research Letters, 1998Co-Authors: Valerie Cayol, F H CornetAbstract:We have investigated the effects of topography on the surface-Deformation Field of volcanoes. Our study provides limits to the use of classical half-space models. Considering axisymmetrical volcanoes, we show that interpreting ground-surface displacements with half-space models can lead to erroneous estimations of the shape of the Deformation source. When the average slope of the flanks of a volcano exceeds 20°, tilting in the summit area is reversed to that expected for a flat surface. Thus, neglecting topography may lead to misinterpreting an inflation of the source as a deflation. Comparisons of Mogi's model with a three-dimensional model shows that ignoring topography may lead to an overestimate of the source-volume change by as much as 50% for a slope of 30°. This comparison also shows that the depths calculated by using Mogi's solution for prominent volcanoes should be considered as depths from the summit of the edifices. Finally, we illustrate these topographic effects by analyzing the Deformation Field measured by radar interferometry at Mount Etna during its 1991–1993 eruption. A three-dimensional modeling calculation shows that the flattening of the deflation Field near the volcano's summit is probably a topographic effect.
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Effects of topography on the interpretation of the Deformation Field of prominent volcanoes—Application to Etna
Geophysical Research Letters, 1998Co-Authors: Valerie Cayol, F H CornetAbstract:We have investigated the effects of topography on the surface-Deformation Field of volcanoes. Our study provides limits to the use of classical half-space models. Considering axisymmetrical volcanoes, we show that interpreting ground-surface displacements with half-space models can lead to erroneous estimations of the shape of the Deformation source. When the average slope of the flanks of a volcano exceeds 20°, tilting in the summit area is reversed to that expected for a flat surface. Thus, neglecting topography may lead to misinterpreting an inflation of the source as a deflation. Comparisons of Mogi's model with a three-dimensional model shows that ignoring topography may lead to an overestimate of the source-volume change by as much as 50% for a slope of 30°. This comparison also shows that the depths calculated by using Mogi's solution for prominent volcanoes should be considered as depths from the summit of the edifices. Finally, we illustrate these topographic effects by analyzing the Deformation Field measured by radar interferometry at Mount Etna during its 1991–1993 eruption. A three-dimensional modeling calculation shows that the flattening of the deflation Field near the volcano's summit is probably a topographic effect.