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Wakai T.,Japan Atomic Energy Agency | Inoue O.,Kaigan Inc. | Ando M.,Japan Atomic Energy Agency | Kobayashi S.,Japan Atomic Energy Agency
Nuclear Engineering and Design | Year: 2015

In Japan, the basic designing works for a demonstration plant of Japan Sodium cooled Fast Reactor (JSFR) are now conducted. JSFR is an advanced loop type reactor concept. To enhance the safety and the economic competitiveness, JSFR employs modified 9% chromium-1% molybdenum (Mod.9Cr-1Mo) steel as a material for coolant pipes and components, because the steel has both excellent high temperature strength and thermal properties. The steel has been standardized as a nuclear material in Japan Society of Mechanical Engineers (JSME) code in 2012. In JSFR pipes, demonstration of Leak Before Break (LBB) aspect is strongly expected because the safety assessment may be performed on the premise of leak rate where the LBB aspect is assured. Although the authors have already performed a series of thermal fatigue crack growth tests of austenitic stainless steel cylinders (Wakai et al., 2005), crack growth behavior in the structures made of Mod.9Cr-1Mo steel has not been investigated yet. Especially for the welded joints of Mod.9Cr-1Mo steel, "Type-IV" cracking may occur at heat affected zone (HAZ). Therefore, this study performed a series of thermal fatigue crack growth tests of thick wall cylinders made of Mod.9Cr-1Mo steel including welds, to obtain the crack growth data under cyclic thermal transients. The test results were compared to the analytical results obtained from JAEA's simplified methods (Wakai et al., 2005). © 2015. Source


Matsumoto K.,Chuo University | Ito Y.,Kaigan Inc. | Hayashi K.,Chuo University | Murahashi K.,Chuo University | And 2 more authors.
International Journal of Refrigeration | Year: 2013

Since frosting to a cooling solid surface has caused many serious accidents accompanied by economic losses, it is necessary to clarify the mechanism of frosting to the cooling solid surface both scientifically and technologically. Thus, at first clarification of frosting from generation to primary stage of growth is very important. And considering the size of frost crystals until the primary stage, it is essential to investigate frost crystals in nano/micro scale field. In this paper, using a scanning probe microscope (SPM), frost crystals dimensions/distribution and scraping force of frost crystals were measured based on the method proposed by one of authors, under a fixed humidity varying cooling solid surface temperatures. And then, the correlations among frost crystals dimensions/distribution and scraping force were clarified. © 2012 Elsevier Ltd and IIR. All rights reserved. Source


Matsumoto K.,Chuo University | Honda M.,Chuo University | Ito Y.,Kaigan Inc. | Shirai D.,Chuo University
International Journal of Refrigeration | Year: 2014

Frosting to a cooling solid surface is often unavoidable and is severe problems. Thus, in order to control the frosting, it is necessary to clarify the mechanism of frosting, both scientifically and technologically. Furthermore, when investigating this mechanism, knowing how frost crystals start to form and grow is very important, therefore, frosting from generation to primary growth stage must be clarified. Since frost crystals dimensions are very small in their generation and primary growth stage, it is essential to conduct these investigations at the micro scale level. In this study, using a scanning probe microscope (SPM), frost crystals dimensions/distribution and scraping force of frost crystals, were measured under fixed surface temperatures, comparing influence of humidity with that of surface temperature via a method proposed by one of the authors. Then, correlations among the above frost crystals dimensions/distribution and scraping force were clarified, comparing with influence of cooling solid surface temperature. © 2013 Elsevier Ltd and IIR. All rights reserved. Source


Osawa K.,Hitachi Ltd. | Senda N.,Hitachi Ltd. | Minemura H.,Hitachi Ltd. | Watanabe K.,Hitachi Ltd. | And 2 more authors.
Progress in Biomedical Optics and Imaging - Proceedings of SPIE | Year: 2015

We developed a low cost, high resolution optical coherence tomography system utilizing a narrowband laser diode (LD), which is usually used in optical pickup for compact disc. To achieve high axial resolution even with the narrow bandwidth of the LD, we have constructed a free space interferometer including a phase-diversity detection system and a high numerical aperture (NA) objective. The axial and lateral resolution in the air was about 2.6 μm and 1 μm, respectively. The tomographic imaging of biological tissue was demonstrated, and the results showed that our OCT system enabled cellular-level imaging. © 2015 SPIE. Source


Dam H.C.,Japan Advanced Institute of Science and Technology | Dam H.C.,Vietnam National University, Hanoi | Pham T.L.,Japan Advanced Institute of Science and Technology | Ho T.B.,Japan Advanced Institute of Science and Technology | And 2 more authors.
Journal of Chemical Physics | Year: 2014

We develop a method that combines data mining and first principles calculation to guide the designing of distorted cubane Mn4+ Mn 33+ single molecule magnets. The essential idea of the method is a process consisting of sparse regressions and cross-validation for analyzing calculated data of the materials. The method allows us to demonstrate that the exchange coupling between Mn4 + and Mn3 + ions can be predicted from the electronegativities of constituent ligands and the structural features of the molecule by a linear regression model with high accuracy. The relations between the structural features and magnetic properties of the materials are quantitatively and consistently evaluated and presented by a graph. We also discuss the properties of the materials and guide the material design basing on the obtained results. © 2014 AIP Publishing LLC. Source

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