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.
Yuji J.-I.,National Institute of Technology, Kumamoto College |
Shiraki S.,National Institute of Technology, Kumamoto College
Proceedings of the International Conference on Sensing Technology, ICST | Year: 2013
This paper describes a magnetic tactile sensor with Indium antimonide (InSb) Hall elements for multifunctional sensing devices to detect the normal contact force and the temperature. This sensor consists of two Hall elements and a magnet that are embedded in a silicone rubber. The temperature characteristic of InSb Hall elements depends on the bias circuit to generate the Hall voltage. Two output Hall voltages driven by two kinds of bias circuits were measured in the normal contact force range from 0 to 50 N, the temperature range from-10 to 50°. The inverse response surface to identify the normal contact force and the temperature was formulated using the experimental results. © 2013 IEEE.
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.
Yamamoto Y.,Waseda University |
Fujimoto S.-I.,National Institute of Technology, Kumamoto College |
Nagakura H.,Kyoto University |
Nagakura H.,Waseda University |
Yamada S.,Waseda University
Astrophysical Journal | Year: 2013
We perform experimental simulations with spherical symmetry and axisymmetry to understand the post-shock-revival evolution of core-collapse supernovae. Assuming that the stalled shock wave is relaunched by neutrino heating and employing the so-called light bulb approximation, we induce shock revival by raising the neutrino luminosity up to the critical value, which is determined by dynamical simulations. A 15 M⊙ progenitor model is employed. We incorporate nuclear network calculations with a consistent equation of state in the simulations to account for the energy release by nuclear reactions and their feedback to hydrodynamics. Varying the shock-relaunch time rather arbitrarily, we investigate the ensuing long-term evolutions systematically, paying particular attention to the explosion energy and nucleosynthetic yields as a function of relaunch time, or equivalently, the accretion rate at shock revival. We study in detail how the diagnostic explosion energy approaches the asymptotic value and which physical processes contribute in what proportions to the explosion energy. Furthermore, we study the dependence of physical processes on the relaunch time and the dimension of dynamics. We find that the contribution of nuclear reactions to the explosion energy is comparable to or greater than that of neutrino heating. In particular, recombinations are dominant over burnings in the contributions of nuclear reactions. Interestingly, one-dimensional (1D) models studied in this paper cannot produce the appropriate explosion energy and nickel mass simultaneously; nickels are overproduced. This problem is resolved in 2D models if the shock is relaunched at 300-400 ms after the bounce. © 2013. The American Astronomical Society. All rights reserved.
Czarnecki M.A.,Wrocław University |
Morisawa Y.,Kinki University |
Futami Y.,National Institute of Technology, Kumamoto College |
Ozaki Y.,Kwansei Gakuin University
Chemical Reviews | Year: 2015
The usefulness and uniqueness of near-infrared (NIR) spectroscopy in the study of molecular structure and interactions was studied. The uniqueness of NIR spectroscopy arises mainly from the anharmonicity of the molecular vibrations. Thus, a deeper understanding of anharmonicity and molecular vibrational potentials provides further insight into chemical bonding, molecular structure, and interactions. The examinations of the gas-phase overtone spectra coupled with the high-level theoretical calculations provided valuable information on the molecular structure and interactions. Recently the first studies of matrix-isolated complexes and ionic liquids by using NIR spectroscopy have been reported. All these works clearly show that the NIR region is not simply an extension of the MIR region, it provides specific information on molecular structure and hydrogen bonding not available from any other spectral range. In analyzing NIR spectra, one should take into account the specific properties that make this spectral region unique and different from the MIR region. The elimination or significant restriction of the possible resonances one can achieve by measurement of the NIR spectra in the higher overtones region, where the vibrations are well described by the LMM and are less coupled to other modes and to each other.
Sayama H.,Binghamton University State University of New York |
Akaishi J.,Binghamton University State University of New York |
Akaishi J.,National Institute of Technology, Kumamoto College
PLoS ONE | Year: 2012
Researchers' networks have been subject to active modeling and analysis. Earlier literature mostly focused on citation or co-authorship networks reconstructed from annotated scientific publication databases, which have several limitations. Recently, general-purpose web search engines have also been utilized to collect information about social networks. Here we reconstructed, using web search engines, a network representing the relatedness of researchers to their peers as well as to various research topics. Relatedness between researchers and research topics was characterized by visibility boost-increase of a researcher's visibility by focusing on a particular topic. It was observed that researchers who had high visibility boosts by the same research topic tended to be close to each other in their network. We calculated correlations between visibility boosts by research topics and researchers' interdisciplinarity at the individual level (diversity of topics related to the researcher) and at the social level (his/her centrality in the researchers' network). We found that visibility boosts by certain research topics were positively correlated with researchers' individual-level interdisciplinarity despite their negative correlations with the general popularity of researchers. It was also found that visibility boosts by network-related topics had positive correlations with researchers' social-level interdisciplinarity. Research topics' correlations with researchers' individual- and social-level interdisciplinarities were found to be nearly independent from each other. These findings suggest that the notion of "interdisciplinarity" of a researcher should be understood as a multi-dimensional concept that should be evaluated using multiple assessment means. © 2012 Sayama, Akaishi.
Kaneda T.,National Institute of Technology, Kumamoto College |
Motoki J.Y.D.,National Institute of Technology, Kumamoto College
Developmental Biology | Year: 2012
Studies of meso-endoderm and neural induction and subsequent body plan formation have been analyzed using mainly amphibians as the experimental model. . Xenopus is currently the predominant model, because it best enables molecular analysis of these induction processes. However, much of the embryological information on these inductions (. e.g., those of the Spemann-Mangold organizer), and on the morphogenetic movements of inductively interacting tissues, derives from research on non-model amphibians, especially urodeles. Although the final body pattern is strongly conserved in vertebrates, and although many of the same developmental genes are expressed, it has become evident that there are individually diverse modes of morphogenesis and timing of developmental events. Whether or not this diversity represents essential differences in the early induction processes remains unclear. The aim of this review is to compare the gastrulation process, induction processes, and gene expressions between a urodele, mainly . Cynops pyrrhogaster, and an anura, . Xenopus laevis, thereby to clarify conserved and diversified aspects. . Cynops gastrulation differs significantly from that of . Xenopus in that specification of the regions of the . Xenopus dorsal marginal zone (DMZ) are specified before the onset of gastrulation, as marked by blastopore formation, whereas the equivalent state of specification does not occur in . Cynops until the middle of gastrulation. Detailed comparison of the germ layer structure and morphogenetic movements during the pre-gastrula and gastrula stages shows that the entire gastrulation process should be divided into two phases of notochord induction and neural induction. . Cynops undergoes these processes sequentially after the onset of gastrulation, whereas . Xenopus undergoes notochord induction during a series of pre-gastrulation movements, and its traditionally defined period of gastrulation only includes the neural induction phase. Comparing the structure, fate, function and state of commitment of each domain of the DMZ of . Xenopus and . Cynops has revealed that the true form of the Spemann-Mangold organizer is suprablastoporal . gsc-expressing endoderm that has notochord-inducing activity. . Gsc-expressing deep endoderm and/or superficial endoderm in . Xenopus is involved in inducing notochord during pre-gastrulation morphogenesis, rather than both . gsc- and . bra-expressing tissues being induced at the same time. © 2012 Elsevier Inc.
Suzuki M.,Nagoya Institute of Technology |
Yanagitani T.,Nagoya Institute of Technology |
Odagawa H.,National Institute of Technology, Kumamoto College
Applied Physics Letters | Year: 2014
Polarity inversion in wurtzite film is generally achieved by the epitaxial growth on a specific under-layer. We demonstrate polarity inversion of c-axis oriented ScAlN films by substrate ion beam irradiation without using buffer layer. Substrate ion beam irradiation was induced by either sputtering a small amount of oxide (as a negative ion source) onto the cathode or by applying a RF bias to the substrate. Polarity of the films was determined by a press test and nonlinear dielectric measurement. Second overtone thickness extensional mode acoustic resonance and suppression of fundamental mode resonance, indicating complete polarity inversion, were clearly observed in bilayer highly oriented (000-1)/(0001) ScAlN film. © 2014 Author(s).