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Journal of Biomedical Science and Engineering 2013年第3期6卷 314-318页

作者： Yul-Wan Sung seiji ogawa Kansei Fukushi Research Institute Tohoku Fukushi University Sendai Japan

It is well known that auditory cortical areas are activated by visual stimulation in the deaf. However, it is not known whether the information enters from the primary visual area or high-level visual areas. In this study, we used visual language stimulation to examine visual-auditory functional connectivity. For this, we used functional magnetic resonance imaging (fMRI) in a congenitally deaf subject to localize areas in the auditory cortex that showed cross-modal reorganization for the processing of visual language inputs and estimate areas in the visual ventral stream, from which language signal inputs enter the auditory areas in the congenitally deaf. We found that the anterior region of the secondary auditory cortex in the superior temporal gyrus showed language-specific activation and that the visual inputs into the area were from the fusiform gyrus, which is a high-level visual area.

关键词： Deaf Visual Language Processing Functional MRI Fusiform Gyrus Auditory Cortical Areas

Invariance of Functional Characteristics to Task Difference at Low-Level and High-Level Areas in the Ventral Visual Pathway

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Journal of Behavioral and Brain Science 2014年第9期4卷 402-411页

作者： Yul-Wan Sung Uk-Su Choi seiji ogawa Kansei Fukushi Research Institute Tohoku Fukushi University Sendai Japan Neuroscience Research Institute Gachon University Incheon Korea

Tasks with stimuli are often used for the examination of stimulus-related functional characteristics of brain areas. However, the task can affect the response to a stimulus. Repetition suppression is a phenomenon that can be used to probe neuronal properties using macroscale functional magnetic resonance imaging (fMRI). The use of repetition suppression as an investigative tool to assess functional characteristics warrants the investigation of the invariance of repetition suppression to a given task. In this study, we examined repetition suppression using images of faces during different tasks. We found that the task difference did not change the response patterns related to repetition suppression in high-level areas and the primary visual area while it changed amplitudes of fMRI response to the visual stimuli. The result suggests that the repetition-suppression phenomenon is robust compared with the amplitude of fMRI response, and functional characteristics can be examined using the repetition-suppression phenomenon even under the condition that fMRI response is varied by task difference.

关键词： Task Difference Repetition Suppression FFA Central Stimulation Peripheral Stimulation fMRI Face Images

Eye Movements Provide Inhibitory Inputs to the Occipito-Temporal Region

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Open Journal of Medical Imaging 2012年第3期2卷 85-89页

作者： Yul-Wan Sung Hiroshi Tsubokawa Young-Bo Kim seiji ogawa Graduate School of Human Relations Keio University Incheon Korea Kansei Fukushi Research Institute Tohoku Fukushi University Sendai Japan

Eye movements play an important role in attention and visual processing. However, the manner in which eye move-ments are involved in object processing is not clear. The aim of this study is to examine the effects of eye movements on object-processing areas in the occipito-temporal region. Eye movements are always accompanied by visual perception;therefore, the effects of eye movements on object-processing areas in which visual object information is sent via eye movements instead of via retinal inputs of visual images must be measured. For this purpose, response to an eye- drawing stimulation in subjects who drew pictures of faces or buildings by their moving eyes under closed-eye condi-tions was measured by functional magnetic resonance imaging. Functional areas in the occipito-temporal region showed negative responses to the eye-drawing stimulation, and the pattern of negative activation maps in the region was almost the same as that of positive activation maps observed after visual image stimulation. Responses in cate-gory-selective area showed category dependency to the eye-drawing stimulation. This suggests that eye movements provide inhibitory inputs to the object-processing areas in the occipito-temporal region, and these inputs may modulate visual inputs to these areas coming through the retina in the visual perception process.

关键词： Eye Movements Visual Object Processing Occipito-Temporal Region Inhibitory Functional MRI (fMRI)

Guidance, navigation, and control of Hayabusa2 touchdown operations

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Astrodynamics 2020年第4期4卷 393-409页

作者： Fuyuto Terui Naoko ogawa Go Ono seiji Yasuda Tetsuya Masuda Kota Matsushima Takanao Saiki Yuichi Tsuda Institute of Space and A stronautical Science Japan A erospace Exploration AgencyKanagawa 252-5210Japan The 3nd Space Technology Department Space System DirisionNEC CorporationTokyo 183-8501Japan

Hayabusa2 is a Japanese sample return mission from the asteroid *** Hayabusa2 spacecraft was launched on 3 December 2014 and arrived at Ryugu on 27 June *** stayed there until December 2019 for in situ observation and soil sample collection,and will return to the Earth in November or December *** the stay,the spacecraft performed the first touchdown operation on 22 February 2019 and the second touchdown on 11 July 2019,which were both completed *** the surface of Ryugu is rough and covered with boulders,it was not easy to find target areas for *** were several technical challenges to overcome,including demanding guidance,navigation,and control accuracy,to realize the touchdown *** this paper,strategies and technical details of the guidance,navigation,and control systems are *** flight results prove that the performance of the systems was satisfactory and largely contributed to the success of the operation.

关键词： small body exploration touchdown astrodynamics guidance navigation control

Estimations of the Maximum Tangential Velocity V_(θm) in the Vortex Core Region and also the Mean Rotational Velocity V_(oi) near the Concave Wall Surface in the Returned Flow Type Cyclone Dust Collector

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Journal of Thermal Science 2010年第6期19卷 553-560页

作者： Akira ogawa T 110-0011. Minowa 2-14-7 Taitou-Ku Tokyo Japan

There are many types of cyclone dust collectors for separating the fine solid and dust particles from gases in the various industries and also in the home used purposes. For estimating the power loss and the collection efficiency, one of the most important factors is the maximum tangential velocity V0m in the vortex core region in the cyclone body. In order to determine V0~ by the simple method, it is useful to apply the mechanical balance of the angular momentum fluxes under the assumption of ogawa combined vortex model which is composed of the quasi-forced vortex in the vortex core region and also the quasi-free vortex surrounded the vortex core region and also under the assumption of the introduction of equivalent length Heq corresponding to the cone spaces of the cyclone body and the dust bunker. On the other hand, the mean rotational velocity Voi near the concave wall surface is also estimated by the mechanical balance of angular momentum fluxes with the moment of viscous friction force. For confirming the general applications of the obtained equations, the returned flow types cyclones changed the throat diameter D3 are designed. The material of the cyclone is the transparent acrylic resin. Therefore the inner surface of the cyclone body can be regarded as smooth surface. The comparisons of the measured velocities V~ and Voi by a cylindrical Pitot tube are shown in good agreement with those of the proposed equations. The above stated results are described in detail.

关键词： Cyclone Dust Collector Maximum Tangential Velocity Mean Rotational Velocity Angular Momentum Flux Equivalent Length Surface Frictional Force ogawa Combined Vortex Model Reynolds Number.

Progress in numerical simulation of cavitating water jets

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Journal of Hydrodynamics 2013年第4期25卷 502-509页

作者： PENG Guoyi SHIMIZU seiji College of Engineering Nihon University

This paper reviews recent progress made toward modeling of cavitation and numerical simulation of cavitating water jets. Properties of existing cavitation models are discussed and a compressible mixture flow method for the numerical simulation of high- speed water jets accompanied by intensive cavitation is introduced. Two-phase fluids media of cavitating flow are treated as a homo- geneous bubbly mixture and the mean flow is computed by solving Reynolds-Averaged Navier-Stokes （RANS） equations for com- pressible fluid. The intensity of cavitation is evaluated by the gas volume fraction, which is governed by the compressibility of bubble-liquid mixture corresponding to the status of mean flow field. Numerical results of cavitating water jet issuing from an orifice nozzle are presented and its applicability to intensively cavitating jets is demonstrated. However, the effect of impact pressure caused by collapsing of bubbles is neglected, and effectively coupling of the present compressible mixture flow method with the dynamics of bubbles remains to be a challenge.

关键词： cavitation water jet multi-phase flow numerical simulation

Effects of loading contact on electric-power generation of lead zirconate titanate piezoelectric ceramic plate

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Journal of Advanced Ceramics 2019年第4期8卷 509-518页

作者： Mitsuhiro OKAYASU Tsukasa ogawa Graduate School of Natural Science and Technology Okayama University

To better understand the generation of electric power for piezoelectric Pb Zr Ti O3(PZT)ceramic plate(?25 mm),an attempt was made to investigate experimentally and numerically electricpower generation characteristics during cyclic bending under various loading fixtures(?0–?20 mm),i.e.,different contact *** the load-contact area on the PZT ceramic leads to a nonlinear decrease in the generated *** contact area basically enhances the generated voltage,although the voltage saturates during loading when the contact area is less than?5 mm.A similar voltage is generated for?0 and?5 mm,which is attributed to strain status(ratio of compressive and tensile strain)and material failure due to different stress distribution in the PZT *** the basis of the obtained electric generation voltage,suitable loading conditions are clarified by loading with the?5 mm fixture,which generates a higher voltage and a longer lifetime of the PZT *** this approach,it is appeared that the area contact with the area ratio of 0.04(?5 mm/?20 mm)is suitable to obtain the high efficiency of the electric voltage.

关键词： piezoelectric ceramic lead zirconate titanate ceramic electric power generation

Spin-up and Spin-Down Times of Rotational Air Flow Depended on Mean Air Velocity and Surface Roughness on Inner Surface in Cylindrical Vortex Chamber

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Journal of Thermal Science 2004年第1期13卷 46-55页

作者： Akira ogawa Hiroyuki Murakami Department of Mechanical Eng.College of Eng. Nihon UniversityT-963.TokusadaTamura-machiKooriyama-CityJapanThe Marine Self Defense Forcethe Defense AgencyJapan

The spin-up time TA in the spin-up process and spin-down time TD in the spin-down process of rotational air flow in the cylindrical vortex chamber with three kinds of the artificial surface roughness were investigated. One of the most different characteristics between the smooth and rough surface conditions was the spin-down time TD. Also the transient response of the tangential velocity on the spin-up process was analyzed numerically and this result was compared with the experimental results. The above stated results are reported here in detail.

关键词： vortex chamber spin-up time spin-down time transient response surface roughness.

Control of Collection Efficiency for Axial Flow Cyclone Dust Collectors with Fixed Guide Vanes and with Funnel Shaped Exit Pipes

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Journal of Thermal Science 2006年第3期15卷 240-250页

作者： Akira ogawa Masaru Arakawa T-110-0011 Minowa 2-14-7Taitou-KuTokyoJapan SHINWA RULES Co. Ltd.Sanjo-ShiNiigataJapan

The experimental result of the collection efficiency of the axial flow cyclone with the fixed guide vanes is lower than that with the tangential inlet pipe to the cyclone body due to the weak angular momentum transfer given by flowing through the guide vanes. However, one of the interesting points is the control of the collection efficiency depended on the funnel shaped exit pipes. The collection efficiencies for these funnel shaped exit pipes are depended on the Froude number. Then, in this paper, the experimental results of the pressure drop and also the collection efficiency using the fly-ash particles and also the comparison of the calculated results of the collection efficiency with the experimental results are described i~ detail.

关键词： Axial flow cyclone funnel shaped exit pipe fixed guide vanes pressure drop collection efficiency,Froude number cut-Size

Analysis of Laser-Induced Plume During Disk Laser Welding at Different Speeds

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Plasma Science and Technology 2013年第8期15卷 821-824页

作者：王腾高向东 Katayama seiji School of Electromechanical Engineering Guangdong University of Technology School of Computer South China Normal University Joining and Welding Research Institute Osaka University

During high power disk laser welding, the high-speed photography was used to measure the dynamic images of the laser-induced plume at different laser welding speeds. Various plume features （area, height and brightness） were extracted from the images by the color space clustering algorithm. Combined with observation on the surface and the cross sections of welding samples, the effect of welding speed on welding stability was analyzed. From the experimental results, it was found that these features of plume could reflect the welding state. Thus changes of the plume features corresponded to different welding speeds, which was helpful for monitoring the laser welding stability.

关键词： disk laser welding laser-induced plume stability high-speed photography different welding speeds