深層学習を用いた画像の情動的属性の認識

京都大学0048新制・課程博士博士(情報学)甲第22800号情博第730号新制||情||125(附属図書館)京都大学大学院情報学研究科知能情報学専攻(主査)准教授 中澤 篤志, 教授 西野 恒, 教授 鹿島 久嗣学位規則第4条第1項該当Doctor of InformaticsKyoto UniversityDGA

Low temperature and high strain rate superplastic flow in structural oxide ceramics induced by flash event

High-strength oxide ceramics are known to be brittle, with limited plastic deformability, even at high temperatures above 1000°C. However, structural ceramics with grain sizes of 1 μm or less can exhibit superplasticity, i.e., tensile elongation exceeding 100% via grain boundary sliding (GBS). Because deformation by GBS requires diffusion of atoms (ions) as a stress-relaxation process, a short accommodation length, i.e. a small grain size is critical for achieving superplasticity in ceramics. Superplastic forming is currently employed as a manufacturing technology for metals and alloys, typically at operation temperatures \u3c1000°C and strain rates \u3e10−3 s−1. In contrast, in typical superplastic ceramics such as Y2O3-stabilized tetragonal ZrO2 polycrystals (TZP), superplastic deformation only occurs at higher temperatures (\u3e1400°C) and lower strain rates (\u3c10−4 s−1), though an average grain size of superplastic TZP is usually in a range of 0.3-0.5 μm. Some of nano-grained ceramic composites have been shown to exhibit superplasticity at higher strain rates, but only at higher temperatures beyond 1600°C. In order to reduce the superplastic temperature and to increase the deformation speed, an approach other than grain-size refinement is required to activate GBS in structural ceramics. The application of a strong electric field during sintering is known to enhance densification in ceramics by accelerating diffusion mass transport. The use of flash sintering, in which a material is directly exposed to heat and a strong electrical field beyond threshold values, enables rapid sintering to achieve a fully dense sample at significantly lower furnace temperatures than conventional sintering. Field-assisted sintering and flash sintering have been used for fast manufacturing of TZP and other ceramic materials. The rapid densification during flash sintering is a result of accelerated self-diffusion and is accompanied by a non-linear increase in the electric conductivity of the material. Electron energy-loss spectrometry revealed the existence of extrinsic oxygen anion vacancies in flash-sintered Y2O3 and TZP, suggesting that flash sintering proceeds via the generation of atomic defects under the strong electric field. In addition, it has been pointed out that grain growth in Y2O3-stabilized ZrO2 is accelerated by an electric current as well as by reduction in N2+5%H2 atmosphere. Thus, one can expect that the application of a strong field could also facilitate high-temperature mass-transport phenomena, such as GBS. We demonstrate in this paper that by employing flash event under a strong DC field higher than 50 V·cm−1, conventional TZP ceramics can exhibit superplastic deformation with an elongation to failure of \u3e150%, at a lower furnace temperature of 800°C and a higher strain rate of 2 × 10−3 s−1 compared to previous methods. The flash event can also enhance bending deformation as well as tensile deformation. The flow stress-strain rate relationship indicated that the enhancement in the plastic flow of TZP resulted not only from increased specimen temperature due to Joule heating but also from accelerated diffusion by electric field and/or current. The field/current effect was equivalent to increase in temperature of about 200ºC

PERFORMANCE ANALYSIS OF THE START PHASE OF SKELETON ATHLETES AT INTERNATIONAL COMPETITIONS

The purpose of this study was to investigate characteristics of the skeleton start motion from the viewpoint of step frequency and step length. Twenty-six male and twenty female skeleton athletes at international competitions were videotaped and analysed their start motion with the three-dimensional DLT method. There were high significant correlations between the start time and the goal time in both men (r = 0.947, p \u3c 0.001) and women (r = 0.741, p \u3c 0.001). As for the start time, men showed a significant correlation with the step length at the 1st step (r = -0.606, p \u3c 0.01) while women showed significant correlations with the step frequency at the 1st (r = -0.475, p \u3c 0.05), 3rd (r = -0.497, p \u3c 0.05) and 5th (r = -0.471, p \u3c 0.05) step. These result indicated that men emphasized step length at the 1st step, while women relied more on step frequency

Athermally Enhanced High Temperature Plastic Flow in Zirconia Ceramics under Flash Event

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Self-joining of Y-TZP by flash event under an AC electric field

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A Case of Malignant T-Cell Lymphoma of Gastric Origin Accompanied by Pyothorax

The patient was a 74-year-old man suffering from tuberculotic chronic pyothorax. He had hematemesis in January 2006. Hb was 6.1 g/dl. A type 2 tumor 3 cm in diameter was found in the vaulted region on the greater curvature side. It was diagnosed as a malignant lymphoma. WBC and differential count were normal, and the patient tested negative for HTVL-1 antibody. sIL2-R was elevated to 1,500 U/ml. The superficial lymph nodes were not palpable. CT examination was not remarkable for the liver and spleen. There was no generalized lymph node enlargement. Based on these findings, a diagnosis of malignant lymphoma of gastric origin was made. As the patient had respiratory disorders, too, wedge-shaped gastrectomy was performed to inhibit invasion. Pathological examination revealed CD3 positive large atypical lymphocytes diffusely, EBV positive, HP negative. As a result, a diagnosis of non-Hodgkin T-cell lymphoma was made. The tumor did not return for 1 year and 8 months after surgery, but the patient died of sudden aggravation of respiratory disorders in September 2007. Pathological anatomy was performed. The gastric remnant was left with lymphoma, and the bone marrow and systemic lymph nodes were negative for a malignant lymphoma. The possibility of stomach metastasis from the preoperative pyothorax-related malignant lymphoma was considered, but was ruled out because the lungs were devoid of a malignant lymphoma. We report a case of an extremely rare malignant T-cell lymphoma of gastric origin