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Iwao K.,National Institute of Technology, Kumamoto College | Inatsu M.,Hokkaido University | Kimoto M.,University of Tokyo
Journal of Climate | Year: 2012

This study investigated recent changes in the characteristics of explosively developing extratropical cyclones over the northwestern Pacific region in winter from 1979/80 to 2010/11 by using reanalysis data from the Japanese 25-yr Reanalysis/Japan Meteorological Agency Climate Data Assimilation System (JRA-25/ JCDAS). The results showed that the frequency of explosive cyclones increased in the northwestern Pacific region east of Japan. This increase was accompanied by a decrease in the number of slowly developing cyclones, indicating an increase in the cyclone growth rate. Moreover, most of the increased explosive cyclones east of Japan originated southwest of Japan. A comparison of the dynamical features and energy budgets of two composite cyclones in the earlier and later halves of the study period suggested that the increase was due to an enhancement of the low-level baroclinicity to the east of Japan and an increase in humidity associated with sea surface temperature warming and enhanced evaporation along the eastern shore of the Asian continent. © 2012 American Meteorological Society.


Goto K.,National Institute of Technology, Kumamoto College
Tubular Structures - Proceedings of the 15th International Symposium on Tubular Structures, ISTS 2015 | Year: 2015

Seismic response and damage of concrete filled steel tube frame (CFT frame) are calculated in relation with the column overdesign factor (rcb) and its distribution. The numerical analysis method to predict the damage of CFT frame under strong ground motion is obtained by introducing the damage ratios of cracking and local buckling of both CFT column and H-section beam. CFT frames with rcb distributed uniformly or not-uniformly are designed. By the use of the presented analysis method the static analysis and the seismic response analysis of these designed CFT frames have been calculated and the damages of CFT frame are obtained quantitatively. From these results it is pointed that the distribution of rcb is one of the important design factor. © 2015 Taylor & Francis Group, London.


Fuchida K.,National Institute of Technology, Kumamoto College
WIT Transactions on the Built Environment | Year: 2011

This paper presents an evaluating method for seismic behaviour of pipelines during earthquakes and studies the response characteristics of them for various conditions of ground displacements and pipelines. The proposed method consists of mainly two analytical methods which are the seismic response analysis of surface ground layers and the pseudo static response analysis of buried pipelines. The seismic response analysis method for surface ground layers is 2-dimensional effective stress analysis based on Biot's two phase mixture theory and Iai's constitutive equation. The pipeline analysis is based on a beam theory on an elastic foundation and modified transfer matrix method. Numerical computations are performed for various models with changing conditions of ground and pipes. As a result, axial and lateral response characteristics of pipelines are shown and evaluated by relating with earthquakes, grounds and pipelines conditions. © 2011 WIT Press.


Fujimoto S.-I.,National Institute of Technology, Kumamoto College | Kotake K.,Japan National Astronomical Observatory | Hashimoto M.-A.,Kyushu University | Ono M.,Kyushu University | Ohnishi N.,Tohoku University
Astrophysical Journal | Year: 2011

We investigate explosive nucleosynthesis in a non-rotating 15 M ∞ star with solar metallicity that explodes by a neutrino-heating supernova (SN) mechanism aided by both standing accretion shock instability (SASI) and convection. To trigger explosions in our two-dimensional hydrodynamic simulations, we approximate the neutrino transport with a simple light-bulb scheme and systematically change the neutrino fluxes emitted from the protoneutron star. By a post-processing calculation, we evaluate abundances and masses of the SN ejecta for nuclei with a mass number ≤70, employing a large nuclear reaction network. Aspherical abundance distributions, which are observed in nearby core-collapse SN remnants, are obtained for the non-rotating spherically symmetric progenitor, due to the growth of a low-mode SASI. The abundance pattern of the SN ejecta is similar to that of the solar system for models whose masses range between (0.4-0.5) M ∞ of the ejecta from the inner region (≤10, 000 km) of the precollapse core. For the models, the explosion energies and the 56Ni masses are ≃ 10 51erg and (0.05-0.06) M ∞, respectively; their estimated baryonic masses of the neutron star are comparable to the ones observed in neutron-star binaries. These findings may have little uncertainty because most of the ejecta is composed of matter that is heated via the shock wave and has relatively definite abundances. The abundance ratios for Ne, Mg, Si, and Fe observed in the Cygnus loop are reproduced well with the SN ejecta from an inner region of the 15 M ∞ progenitor. © 2011. The American Astronomical Society. All rights reserved.


Tsuzuki S.,Nanosystem Research Institute | Shinoda W.,Nagoya University | Matsugami M.,National Institute of Technology, Kumamoto College | Umebayashi Y.,Niigata University | And 5 more authors.
Physical Chemistry Chemical Physics | Year: 2015

Molecular dynamics simulations of equimolar mixtures of glymes (triglyme and tetraglyme) and Li[TFSA] (lithium bis(trifluoromethylsulfonyl) amide) show that the glyme chain length affects the coordination geometries of Li+, which induces the changes in interactions between the [Li(glyme)]+ complex and [TFSA]- anions and diffusion of ions in the equimolar mixtures. © the Owner Societies 2015.

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