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Chikatoshi Honda - One of the best experts on this subject based on the ideXlab platform.
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the western bulge of 162173 ryugu formed as a result of a rotationally driven Deformation Process
arXiv: Earth and Planetary Astrophysics, 2019Co-Authors: Masatoshi Hirabayashi, Eri Tatsumi, Hideaki Miyamoto, Goro Komatsu, Seiji Sugita, Seiichiro Watanabe, Daniel J Scheeres, O S Barnouin, P Michel, Chikatoshi HondaAbstract:162173 Ryugu, the target of Hayabusa2, has a round shape with an equatorial ridge, which is known as a spinning top-shape. A strong centrifugal force is a likely contributor to Ryugu's top-shaped features. Observations by Optical Navigation Camera onboard Hayabusa2 show a unique longitudinal variation in geomorphology; the western side of this asteroid, later called the western bulge, has a smooth surface and a sharp equatorial ridge, compared to the other side. Here, we propose a structural Deformation Process that generated the western bulge. Applying the mission-derived shape model, we employ a finite element model technique to analyze the locations that experience structural failure within the present shape. Assuming that materials are uniformly distributed, our model shows the longitudinal variation in structurally failed regions when the spin period is shorter than ~3.75 h. Ryugu is structurally intact in the subsurface region of the western bulge while other regions are sensitive to structural failure. We infer that this variation is indicative of the Deformation Process that occurred in the past, and the western bulge is more relaxed structurally than the other region. Our analysis also shows that this Deformation Process might occur at a spin period between ~3.5 h and ~3.0 h, providing the cohesive strength ranging between ~4 Pa and ~10 Pa.
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the western bulge of 162173 ryugu formed as a result of a rotationally driven Deformation Process
The Astrophysical Journal, 2019Co-Authors: Masatoshi Hirabayashi, Eri Tatsumi, Hideaki Miyamoto, Goro Komatsu, Seiji Sugita, Seiichiro Watanabe, Daniel J Scheeres, O S Barnouin, P Michel, Chikatoshi HondaAbstract:162173 Ryugu, the target of Hayabusa2, has a round shape with an equatorial ridge, which is known as a spinning top shape. A strong centrifugal force is a likely contributor to Ryugu's top-shaped features. Observations by the Optical Navigation Camera on board Hayabusa2 show a unique longitudinal variation in geomorphology; the western side of this asteroid, later called the western bulge, has a smooth surface and a sharp equatorial ridge, compared to the other side. Here, we propose a structural Deformation Process that generated the western bulge. Applying the mission-derived shape model, we employ a finite element model technique to analyze the locations that experience structural failure within the present shape. Assuming that materials are uniformly distributed, our model shows the longitudinal variation in structurally failed regions when the spin period is shorter than ~3.75 hr. Ryugu is structurally intact in the subsurface region of the western bulge while other regions are sensitive to structural failure. We infer that this variation is indicative of the Deformation Process that occurred in the past, and the western bulge is more relaxed structurally than the other region. Our analysis also shows that this Deformation Process might occur at a spin period between ~3.5 and ~3.0 hr, providing the cohesive strength ranging between ~4 and ~10 Pa.
Masatoshi Hirabayashi - One of the best experts on this subject based on the ideXlab platform.
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the western bulge of 162173 ryugu formed as a result of a rotationally driven Deformation Process
arXiv: Earth and Planetary Astrophysics, 2019Co-Authors: Masatoshi Hirabayashi, Eri Tatsumi, Hideaki Miyamoto, Goro Komatsu, Seiji Sugita, Seiichiro Watanabe, Daniel J Scheeres, O S Barnouin, P Michel, Chikatoshi HondaAbstract:162173 Ryugu, the target of Hayabusa2, has a round shape with an equatorial ridge, which is known as a spinning top-shape. A strong centrifugal force is a likely contributor to Ryugu's top-shaped features. Observations by Optical Navigation Camera onboard Hayabusa2 show a unique longitudinal variation in geomorphology; the western side of this asteroid, later called the western bulge, has a smooth surface and a sharp equatorial ridge, compared to the other side. Here, we propose a structural Deformation Process that generated the western bulge. Applying the mission-derived shape model, we employ a finite element model technique to analyze the locations that experience structural failure within the present shape. Assuming that materials are uniformly distributed, our model shows the longitudinal variation in structurally failed regions when the spin period is shorter than ~3.75 h. Ryugu is structurally intact in the subsurface region of the western bulge while other regions are sensitive to structural failure. We infer that this variation is indicative of the Deformation Process that occurred in the past, and the western bulge is more relaxed structurally than the other region. Our analysis also shows that this Deformation Process might occur at a spin period between ~3.5 h and ~3.0 h, providing the cohesive strength ranging between ~4 Pa and ~10 Pa.
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the western bulge of 162173 ryugu formed as a result of a rotationally driven Deformation Process
The Astrophysical Journal, 2019Co-Authors: Masatoshi Hirabayashi, Eri Tatsumi, Hideaki Miyamoto, Goro Komatsu, Seiji Sugita, Seiichiro Watanabe, Daniel J Scheeres, O S Barnouin, P Michel, Chikatoshi HondaAbstract:162173 Ryugu, the target of Hayabusa2, has a round shape with an equatorial ridge, which is known as a spinning top shape. A strong centrifugal force is a likely contributor to Ryugu's top-shaped features. Observations by the Optical Navigation Camera on board Hayabusa2 show a unique longitudinal variation in geomorphology; the western side of this asteroid, later called the western bulge, has a smooth surface and a sharp equatorial ridge, compared to the other side. Here, we propose a structural Deformation Process that generated the western bulge. Applying the mission-derived shape model, we employ a finite element model technique to analyze the locations that experience structural failure within the present shape. Assuming that materials are uniformly distributed, our model shows the longitudinal variation in structurally failed regions when the spin period is shorter than ~3.75 hr. Ryugu is structurally intact in the subsurface region of the western bulge while other regions are sensitive to structural failure. We infer that this variation is indicative of the Deformation Process that occurred in the past, and the western bulge is more relaxed structurally than the other region. Our analysis also shows that this Deformation Process might occur at a spin period between ~3.5 and ~3.0 hr, providing the cohesive strength ranging between ~4 and ~10 Pa.
Woo Kyung Moon - One of the best experts on this subject based on the ideXlab platform.
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3 d breast ultrasound segmentation using active contour model
Ultrasound in Medicine and Biology, 2003Co-Authors: Darren Chen, Rueyfeng Chang, Wen Jie Wu, Woo Kyung Moon, Wen Lin WuAbstract:Abstract In this study, we made use of the discrete active contour model to overcome the natural properties of ultrasound (US) images, speckle, noise and tissue-related textures, to segment the breast tumors precisely. Determination of the real tumor boundary with the snake-Deformation Process requires an initial contour estimate. However, the manual way to sketch an initial contour is very time-consuming. Thus, we propose an automatic initial contour-finding method that not only maintains the tumor shape, but also is close to the tumor boundary and inside the tumor. During the Deformation Process, to prevent the snake trapping into the false position caused by tissue-related texture or speckle, we added the edge information as an image feature to define the external force. In addition, because the 3-D volume of a tumor is essentially constructed by a sequence of 2-D images, our method for finding boundaries of a tumor can be extended to 3-D cases. By precisely counting the volume of the 3-D images, we can get the volume of tumor. Finally, we will show that the proposed techniques have rather good performance and lead to a satisfactory result in comparison with the estimated volume and physician’s estimate. (E-mail: dlchen88@ms13.hinet.net)
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3 d breast ultrasound segmentation using active contour model
Ultrasound in Medicine and Biology, 2003Co-Authors: Darren Chen, Rueyfeng Chang, Woo Kyung MoonAbstract:In this study, we made use of the discrete active contour model to overcome the natural properties of ultrasound (US) images, speckle, noise and tissue-related textures, to segment the breast tumors precisely. Determination of the real tumor boundary with the snake-Deformation Process requires an initial contour estimate. However, the manual way to sketch an initial contour is very time-consuming. Thus, we propose an automatic initial contour-finding method that not only maintains the tumor shape, but also is close to the tumor boundary and inside the tumor. During the Deformation Process, to prevent the snake trapping into the false position caused by tissue-related texture or speckle, we added the edge information as an image feature to define the external force. In addition, because the 3-D volume of a tumor is essentially constructed by a sequence of 2-D images, our method for finding boundaries of a tumor can be extended to 3-D cases. By precisely counting the volume of the 3-D images, we can get the volume of tumor. Finally, we will show that the proposed techniques have rather good performance and lead to a satisfactory result in comparison with the estimated volume and physician's estimate.
Anton Hohenwarter - One of the best experts on this subject based on the ideXlab platform.
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incremental high pressure torsion as a novel severe plastic Deformation Process Processing features and application to copper
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2015Co-Authors: Anton HohenwarterAbstract:High pressure torsion is known as one of the most popular severe plastic Deformation Processes. However, it has certain size limitations, especially regarding the thickness of the Processed samples. In this contribution incremental high pressure torsion is introduced as a novel severe plastic Deformation Process. This further development of conventional high pressure torsion is capable of delivering specimens having an extraordinarily high aspect-ratio of thickness to diameter. The features of this Process combined with a case-study on a pure copper specimen with a deformed diameter of 50 mm and a thickness of 40 mm is presented.
X G Fan - One of the best experts on this subject based on the ideXlab platform.
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a numerical model based on internal state variable method for the microstructure evolution during hot working Process of ta15 titanium alloy
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2010Co-Authors: Zhichao Sun, H Yang, G J Han, X G FanAbstract:Abstract The microstructure and dynamic material properties of Ti–6Al–2Zr–1Mo–1V (TA15) titanium alloy are very sensitive to Process parameters, which directly determine the service properties. To explore and understand the Deformation behavior and the optimization of the Deformation Process, a microstructure-evolution model is needed not only to phenomenologically describe the hot Deformation Process, but also to reflect the interaction between Deformation and microstructure evolution and to reveal the Deformation mechanism. In this article, we present an experimental investigation of the microstructure-evolution law and the softening mechanism of TA15 Deformation in the two-phase region. By using the internal-state-variable method, a set of mechanically based equations that model the evolution of the dislocation density, the recrystallization and the grain size are developed for the TA15 alloy. By integrating the microstructure-evolution model into the DEFORM-3D software package, we predict microstructure evolution during an isothermal, compressive-Deformation Process, and the model is verified by comparing the experimental results with the calculation. Using the model a simulation and grain-size prediction of the TA15 large-component isothermal forming are carried out, and the results are confirmed experimentally.