On the transient response of serpentine (antigorite) gouge to stepwise changes in slip velocity under high-temperature conditions

Shear-sliding tests were conducted on serpentine (antigorite) gouge to understand the rheology of serpentine-bearing faults. The experiments were carried out using a constant confining pressure (100 MPa), a constant pore water pressure (30 MPa), and a range of temperatures (from room temperature to 600 degrees C). The transient response in frictional behavior following stepwise changes in the slip velocity were documented at each temperature. Slip rates varied between 0.0115 and 11.5 mu m/s. Both the general level of frictional strength and the transient responses changed drastically at around 450 degrees C. As the temperature increased from 400 degrees C to 450 degrees C, the strength of antigorite rose sharply. The transient response also indicated a change in the mode of deformation from flow-type behavior at temperatures below 400 degrees C to frictional behavior (stick-slip) at temperatures above 450 degrees C-500 degrees C. Although only a limited volume of serpentine was involved in the dehydration reaction, X-ray diffraction analyses and scanning electron microscopy observations showed that forsterite had nucleated in the experimental products at the higher temperatures that were associated with frictional behavior. Submicron-sized, streaky forsterite masses in shear-localized zones may be evidence of shear-induced dehydration that caused strengthening and embrittlement of the gouge. Although antigorite rheology is complicated, the subsequent change in friction coefficient per order-of-magnitude change in sliding velocity increased with both increasing temperature and decreasing velocity, implying that a possible flow mechanism of intragranular deformation became activated

咀嚼運動における平均経路予測モデルの開発

The purpose of this study was to develop a new statistical model to predict mandibular kinematics, especially for chewing cycles. Two subjects without indicators or symptoms of temporomandibular disorders and with normal occlusion and anterior crossbite were selected. The chewing movement of the mouth was recorded by an opto-electric system (TRIMET system). Each curve was modeled as spline function with random coefficients. To determine the optimal number of knots, two criteria were used : DIC (deviance information criteria) and pD (effective number of parameters). The aim was to estimate a typical population curve. Self-modeling regression (SEMOR) was extended to three dimensions to model groups of three-dimensional curves. Each curve was modeled as a spline function using 25 knots, and a population average curve was created using SEMOR. The chewing cycles were modeled using a combination of spline function with random coefficients and SEMOR. These models provide a new tool for the analysis of mandibular kinematics to understand commonalities and difference among subjects

仮想歯列モデルを用いた歯と歯列弓形態の評価

The aim of this study was to clarify the three-dimensional (3D) morphological characteristics of dentition using a virtual model of dental arches. Full-mouth dental cast sets were prepared from 217 volunteers (121 male and 96 female). Dental casts were scanned by optTOP-HE scanner. The 3D models were measured and analyzed with Rapidform 2004 software. For the measurements of four morphological parameters(maxillary and mandibular arch lengths, width and first molar width), linear regressions were performed using each variable as the predictor and each other variable as the outcome. In all parameters, the male group showed higher values than the female groups. In the case of the combined and male groups, correlation coefficients of all items were statistically significant (P<0.01). The approach used in this study provides a reliable reference point definition and may provide basic information for dentistry

Autonomous Underwater Vehicle with Vision-based Navigation System for Underwater Robot Competition

The underwater robot competition in international conference Techno-Ocean 2021 was held to advance underwater technology, in Dec. 2021. The competition consists of five leagues including AUV (Autonomous Underwater Vehicle) league, and Kyushu underwater robotics which is the Underwater Student Project team at our university that joint the AUV league using developed AUV. The wet test of the AUV league includes a Gate Pass mission which requires passing through an underwater green gate, Buoy Touch mission requiring contact with the yellow and red buoys, and Special mission requiring contact with the Pinger which has an unknown location. Our AUV navigates by image processing using underwater camera to achieve the mission. This paper explains the AUV system, the mission strategy and detail of image processing.The 2022 International Conference on Artificial Life and Robotics (ICAROB 2022), January 20-23, 2022, on line, Oita, Japa

ノジマ ダンソウ ガウジ ノ コウソク マサツ キョドウ ト ソノ ジシンセイ ダンソウ ウンドウ ニ タイスル イギ

京都大学0048新制・課程博士博士(理学)甲第11334号理博第2892号新制||理||1432(附属図書館)22977UT51-2005-D85京都大学大学院理学研究科地球惑星科学専攻(主査)教授 嶋本 利彦, 助教授 山路 敦, 助教授 田上 高広学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDA