High temperature mechanical properties of BN particle dispersion SiC composites

Silicon carbide composites basically require weak fiber/matrix interphase like carbon or boron nitride (BN). The interphase material and its thickness are keys to determine mechanical properties. However precise control is the critical issue in terms of large scale production and material cost. The interphase is the weakest link for the environmental effects. The SiC composites were developed by applying BN particle dispersion in SiC matrix without the interphase. The objective is to understand the high temperature mechanical properties of the SiC composites. Please click Additional Files below to see the full abstract

[Report on Investigation and Research Activity] Elucidating the History of Yaponesian Based on Archaeological Data : Researches in FY 2021 (2)

departmental bulletin pape

The spread of rice to Japan: insights from Bayesian analysis of direct radiocarbon dates and population dynamics in East Asia

The shift from foraging to agriculture as an economic way of life can be influenced by multiple ecological and cultural factors. The introduction of rice cultivation in Japan appears to have facilitated a dietary and cultural transition from the Jomon to the Yayoi cultural repertoire (10th/4th century BCE). Here we examine how rice spread across the Yayoi cultural arena (Kyushu, Shikoku, and Honshu regions) using Bayesian modelling applied to a set of radiocarbon (14C) dates obtained from carbonized rice grains. The combined results of radiocarbon analysis and archaeological data suggest that rice could have appeared in the Central Highlands already in the 11th century BCE when the region was occupied by people of the Final Jomon culture group and was mainly used for ritual purposes. It then appeared in western Japan (northern Kyushu) in the 9th century BCE and continued to disperse discontinuously across eastern Japan. This dispersal pattern likely results from the fusion of Jomon hunter–fisher–gatherer groups in eastern Japan with cultural traits introduced from the Eurasian mainland. The main driving factors for the immigration of early rice farmers into Japan (starting around 1000 BCE) appears to have been sociopolitical. Transformations in China led to the dissemination of rice farmers into the Korean Peninsula about 500 years earlier. The main drivers likely comprised: (i) the eastward expansion of the Shang dynasty (ca. 1600–1400 BCE); (ii) the eastward expansion of the Zhou kingdom, accompanied by the establishment of satellite states, such as Lu (Shandong Province) and Yan (Beijing), following the defeat of the Shang in 1045 BCE; and (iii) the strengthening of local states during the early 8th century BCE after the weakening of the Zhou, due to conflicts with agropastoralists from the Asian steppes. In addition, it is likely that the gradual middle–late Holocene decrease in summer monsoon precipitation negatively affected agricultural yields in the regions located closer to the summer monsoon boundary, such as the middle Yellow River, and thus further fostered the observed population dynamics including the spread of rice farmers to the Korean Peninsula and Japan

Miniaturization of Worm-type Soft Robot Actuated by Magnetic Field

Recently, many studies on bio-mimic soft robots have been reported. Among living organisms, locomotion of soft bodies, such as snails, worms, and nematodes, have been actively studied. These soft creatures locomote by deforming the muscles of the whole body into waveforms and propagating the waves of the deformation. These locomotion of soft creatures could be applicable to develop a worm-type soft robot which can move in drain pipes and even if in a human body. In this study, we developed worm-like robots which could generate wavy motion under a rotating magnetic field using silicone and magnetic rubber, and investigated its movement characteristics. In addition, based on deformation experiment of a silicone cantilever with a single magnetic element inside made of the same material of worm-like robot, we investigated the effect of the size of the worm robot for further miniaturization