Takayuki Shiraiwa 교수

Takayuki Shiraiwa, Teiji Watanabe, Late Quaternary Glacial Fluctuations in the Langtang Valley, Nepal Himalaya, Reconstructed by Relative Dating Methods, Arctic and Alpine Research, Vol. 23, No. 4 (Nov., 1991), pp. 404-416

Abstract A 45.97 m long ice core was recovered in the accumulation area of Glaciar Tyndall (50˚59’05’’ S, 73˚31’12’’W; 1756ma.s.l.), Campo de Hielo Patagόnico Sur (southern Patagonia icefield), during December 1999. the firn core was subjected to visual stratigraphic observation and bulk density measurements in the field, and later to analyses of water isotopes (δ 18 O, δD), major dissolved ions and snow algal biomass. the drillhole remained dry down to about 43 m depth, where a water-soaked lay

In this study, a method for the prediction of cyclic stress–strain properties of ferrite-pearlite steels was proposed. At first, synthetic microstructures were generated based on an anisotropic tessellation from the results of electron backscatter diffraction (EBSD) analyses. Low-cycle fatigue experiments under strain-controlled conditions were conducted in order to calibrate material property parameters for both an anisotropic crystal plasticity and an isotropic J2 model. Numerical finite eleme

Hydrogen-induced cracking behavior in high-strength steel mainly composed of martensite was analyzed by acoustic emission (AE) technique and finite element method (FEM) in slow strain-rate tensile (SSRT) tests and welding tests. The crack initiation was detected by the AE signals, and the time evolution of stress concentration and hydrogen diffusion were calculated by FEM. The effect of hardness and plastic strain on the hydrogen diffusion coefficient was explicitly introduced into the governing

Abstract A glacier at the summit of Ushkovsky volcano, Kamchatka peninsula, Russia, was studied in order to obtain information about the physical characteristics of a glacier that fills a volcanic crater. The glacier has a gentle surface and a concave basal profile with a maximum measured depth of 240 m at site K2. The annual accumulation rate was 0.54 m a −1 w.e., and the 10 m depth temperature was −15.8°C. A 211.70 m long ice core drilled at K2 indicates that (1) the site is categorized as a p

This paper examines machine learning methods to predict fatigue strength with high accuracy using existing database. The fatigue database was automatically classified by hierarchical clustering method, and a group of carbon steels was selected as a target of machine learning. In linear regression analyses, a model selection was conducted from all possible combinations of explanatory variables based on cross validation technique. The derived linear regression model provided more accurate predicti

The 7075 aluminum alloy is a promising material for the aerospace industry due to its combination of light weight and high strength. This study proposed a method for predicting fatigue crack initiation of the 7075 aluminum alloy by crystal plasticity finite element analysis considering microstructures. In order to accurately predict the total fatigue life, it is necessary to calculate the number of cycles for fatigue crack initiation, small crack growth, and long crack growth. The long crack gro

More than 400 glaciers exist in the mountains of Kamchatka Peninsula and they constitute the southern boundary of present-day glacierization along the eastern coast of the Eurasian continent. The mass balances of the glaciers are characterized by decadal and interdecadal oscillations, and they are closely related to those observed in the glaciers of Pacific North America. A negative relation was also found for the net accumulation timeseries reconstructed by ice cores from Ushkovsky Volcano, Kam