Kobe City College of Technology

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Kobe, Japan
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Ogiwara A.,Kobe City College of Technology | Watanabe M.,University of Shizuoka
Applied Optics | Year: 2015

Formation of holographic polymer-dispersed liquid crystal (HPDLC) memory for an optically reconfigurable gate array is discussed for angle-multiplexing recording by controlling the laser interference exposure in LC composites. The successive laser illumination system to record the various configuration contexts at the specified region and angle in HPDLC memory is constructed by using the combination of a half-mirror and a photomask placed on the motorized stages under the control of a personal computer. The effect of laser exposure energy on the formation of holographic memory is investigated by measuring diffraction intensity as a function of exposure energy during the grating formation process and observing the internal grating structure by scanning electron microscopy. The optical reconfiguration in the gate-array VLSI is executed for configuration contexts of OR and NOR operations shown as logical operators that are reconstructed by laser irradiation at different incident angles for a specified region in the HPDLC memory. © 2015 Optical Society of America.


Ogiwara A.,Kobe City College of Technology | Watanabe M.,University of Shizuoka
Applied Optics | Year: 2012

Holographic polymer dispersed liquid crystal (HPDLC) memory is fabricated by a photoinduced phase separation comprised of polymer and liquid crystal (LC) phases using laser light interference exposures. The anisotropic diffraction induced by the alignment of LC in the periodic structure of the HPDLC memory is applied to reconstruct the configuration contexts for the optically reconfigurable gate arrays. Optical reconfiguration for various circuits under parallel programmability is implemented by switching the polarization state of incident light on the HPDLC memory using a spatial light modulator. © 2012 Optical Society of America.


Ogiwara A.,Kobe City College of Technology | Watanabe M.,University of Shizuoka | Moriwaki R.,University of Shizuoka
Optics Letters | Year: 2013

Grating devices using photosensitive organic materials play an important role in the development of optical and optoelectronic systems. High diffraction efficiency and polarization dependence achieved in a holographic polymerdispersed liquid crystal (HPDLC) grating are expected to provide polarization controllable optical devices, such as the holographic memory for optically reconfigurable gate arrays (ORGAs). However, the optical property is affected by the thermal modulation around the transition temperature (T ni) that the liquid crystal (LC) changes from nematic to isotropic phases. The temperature dependence of the diffraction efficiency in HPDLC grating is discussed with two types of LC composites comprised of isotropic and LC diacrylate monomers. The holographic memory formed by the LC and LC diacrylate monomer performs precise reconstruction of the context information for ORGAs at high temperatures more than 150°C. © 2013 Optical Society of America.


Uenaka K.,Kobe City College of Technology
Journal of Constructional Steel Research | Year: 2016

Concrete filled double skin steel tubular (CFDST) members, having a hollow section consisting of two concentric steel tubes and filled concrete between the two walls of the tubes, are lighter than the ordinary concrete filled steel tubular (CFT) members, which have solid cross-sections. Therefore, the CFDST members can work effectively as seismic resistant structures such as bridges high piers during earthquake. The present study aims to investigate experimentally centric loading characteristics of the CFDST stub column consisting of an outer circular steel tube and an inner square steel tube with in-filled concrete between the double walls, which are abbreviated as CS-CFDST. The two selected testing parameters are the outer tube's diameter-to-thickness ratio and inner width to outer diameter ratio. From the results, observed failure modes were divided into two groups: local buckling associated with shear failure of in-filled concrete and local buckling of the double tubes. These failure modes were affected by inner width to outer diameter ratio. Axial load capacities were also determined by the above described failure modes. Additionally, elasto-plastic biaxial stress behavior of both tubes under plane stress condition is also mentioned. Methods to predict the axial load capacities of CS-CFDST stub columns are also provided. © 2015 Elsevier Ltd. All rights reserved.


Nishimura S.,Kobe City College of Technology
Journal of the Physical Society of Japan | Year: 2015

On the basis of a kinetic energy principle, it is shown that the interchange mode in helical systems is excited by trapped energetic ions, where the ideal interchange mode is stable. The mode has a rotation frequency comparable to precession drift frequencies of trapped energetic ions. The theory explains how to apply the fishbone mode theory originally developed in tokamaks to helical systems. ©2015 The Physical Society of Japan.


Ogiwara A.,Kobe City College of Technology
Applied Optics | Year: 2011

Volume gratings fabricated by interferometric exposure using composite materials composed of nematic liquid crystals (LC) and LC diacrylate monomers are discussed in the effects of diffraction properties on different grating formations, such as varying LC content ratios, film thicknesses, and the surface conditions composed of alignment layers and rubbing directions. Diffraction properties are experimentally investigated in the viewpoints of anisotropic diffraction and LC orientation. The polarization-azimuth dependence of diffraction efficiencies as functions of the incident polarization states shows the controllability of anisotropic diffractions based on the effects of different surface conditions. © 2011 Optical Society of America.


Yamamoto K.,Kobe City College of Technology
IEEJ Transactions on Power and Energy | Year: 2012

CFRP (Carbon Fiber Reinforced Plastic) is widely used in the structures of aircrafts, automobiles, wing turbines, and rockets because of its qualities of high mechanical strength, low weight, fatigue resistance, and dimensional stability. However, these structures are often at risk of being struck by lightning. When lightning strikes such structures and lightning current flows through the CFRP, it may be structurally damaged because of the impact of the lightning strike or ignitions between layers. If there are electronic systems near the CFRP, they may break down or malfunction because of the resulting electromagnetic disturbance. In fact, the generation mechanisms of these breakdowns and malfunctions depend on the current distribution in the CFRP. Hence, it is critical to clarify the current distribution in various kinds of CFRPs. In this study, two kinds of CFRP panels-one composed of quasi-isotropic lamination layers and the other composed of 0°/90° lamination layers of unidirectional CFRP prepregs-are used to investigate the dependence of current distribution on the nature of the lamination layers. The current distribution measurements and simulations for CFRP panels are compared with those for a same-sized aluminum plate. The knowledge of these current distribution characteristics would be very useful for designing the CFRP structures of aircrafts, automobiles, wing turbines, rockets, etc. in the future. © 2012 The Institute of Electrical Engineers of Japan.


Uenaka K.,Kobe City College of Technology
Thin-Walled Structures | Year: 2013

Concrete filled double skin circular tubular (CFDST) members consist of double concentric circular steel tubes with concrete sandwiched between them. Having hollow cross-section, CFDST members are lighter than ordinary concrete filled steel tubular (CFT) members, which have solid cross-sections. Therefore, by alleviating seismic force against the foundation during earthquake, CFDST members can be effectively applied to seismic resistant structures such as a high raise bridge pier. The present study aims to investigate shear characteristics of deep CFDST beams experimentally through an asymmetric static four-point loading test. Two main parameters were selected, namely, the diameter-to-thickness and the inner-to-outer diameter ratios. The results showed that the shear resistance of CFDST gradually decreased as inner-to-outer diameter ratio increased. Methods to predict the shear resistance of deep CFDST beams are also provided. Additionally, stress histories of both tubes are discussed based upon their elasto-plastic stress behavior under plane stress condition. © 2013 Elsevier Ltd.


Uenaka K.,Kobe City College of Technology
Thin-Walled Structures | Year: 2014

A concrete filled elliptical/oval steel tubular (CFEST) member consists of elliptical/oval steel tube and in-filled concrete. The CFEST member is a new type of steel-concrete composite member and is part of a family of concrete filled steel tubular members known as CFT. The present study aims to investigate, experimentally, the characteristics of CFEST stub columns under centric loading. The main test parameters selected are diameter-to-thickness and diameters ratios of elliptical/oval steel tube. From the results, local buckling of the elliptical/oval steel tube associated with shear failure of in-filled concrete could be observed. Axial loading capacity decreased as diameter-to-thickness ratio increased. Whereas, those capacities normalized by the summation of the individual strengths, namely the elliptical/oval steel tube and in-filled concrete strengths, are regulated in case the diameter-to-thickness ratio becomes larger. Finally, a method to predict the axial loading capacity induced by confinement effects of the in-filled concrete is proposed. © 2014 Elsevier Ltd.


Nishimura S.,Kobe City College of Technology
Physics of Plasmas | Year: 2015

The kinetic energy principle describing the interaction between ideal magnetohydrodynamic (MHD) modes with trapped energetic ions is revised. A model is proposed on the basis of the reduced ideal MHD equations for background plasmas and the bounce-averaged drift-kinetic equation for trapped energetic ions. The model is applicable to large-aspect-ratio toroidal devices. Specifically, the effect of trapped energetic ions on the interchange mode in helical systems is analyzed. Results show that the interchange mode is excited by trapped energetic ions, even if the equilibrium states are stable to the ideal interchange mode. The energetic-ion-induced branch of the interchange mode might be associated with the fishbone mode in helical systems. © 2015 AIP Publishing LLC.

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