Characteristic Analysis of Visual Evoked Potentials and Posterior Dominant Rhythm by Use of EEG Model

Kazuhiko Goto,Takenao Sugi,Yoshitaka Matsuda,Satoru Goto,Hiroki Fukuda,Yoshinobu Goto,Takao Yamasaki,Shozo Tobimatsu 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10

Visual evoked potentials (VEPs) are the electrical responses from the brain concerned with visual information processing. Amplitude of VEPs is smaller than that of background EEG activity, and the stimulus-locked averaging method is usually used for obtained the waveform. VEP response to each stimulus is not completely the same however it is varying with its amplitude and duration. Therefore, amplitude of averaged VEP waveform deteriorates due to their variability in raw data. Feature extraction of background EEG activity during visual stimulation is also a one of significant items in VEP analysis. In that case, separation of VEP component and background EEG component (mainly posterior dominant rhythm) is crucial. In the past, we proposed the method of estimating both amplitude of VEP and dominant rhythm by use of EEG model. This present study, the proposed method was applied to actual recorded VEP data and its effectiveness was evaluated. EEGs with visual stimulus were recorded from nine healthy young adults. Usefulness of the proposed method was investigated by comparing the conventional power spectrum averaging method. The proposed method will be applicable to show an accurate VEP analysis and characteristic analysis of background activity under visual stimulus.

ENERGY CONSUMPTION AND MATERIAL FLOW IN SEWAGE TREATMENT PLANT IN JAPAN

GOTO, Naohiro,HU, Hong-Ying,FUJIE, Koichi 嶺南大學校 環境問題硏究所 1999 環境硏究 Vol.19 No.1

ABSTRACT There are some measures for reducing the resource/energy consumption such as selections of optimum treatment processes and optimum operating conditions in sewage treatment facility in Japan. The objective of this study is to get information about the selections of optimum treatment processes of sewage and the optimum operation conditions. The energy consumption and material flow in the sewage treatment facilities in Japan were analyzed using statistic data. Reuse rate of treated sewage outside the treatment facilities of sewage in Japan in 1994 was 18% of domestic treated water amount. Promotion of water reuse outside facilities is necessary. Average electrical power consumption per unit volume of wastewater in sewage treatment facilities varies widely among facilities and correlates closely with facility scale. The smaller the facility scale is, the larger electrical power consumption is. Treatment volume of sewage in smaller facilities was much less than their capacity. 3.7 million t/year of the emitted dehydration cake was disposed by incineration and 0.1 million t/year was disposed by composting. Recycle rate of the cake was low. Developing new treatment process of the sludge except incineration is necessary.

Hormetic effects of regular exercise in aging: correlation with oxidative stress

Goto, Sataro,Naito, Hisashi,Kaneko, Takao,Chung, Hae Young,Radá,k, Zsolt NATIONAL RESEARCH COUNCIL OF CANADA 2007 APPLIED PHYSIOLOGY NUTRITION AND METABOLISM Vol.32 No.5

<P> To explore mechanisms of the beneficial consequences of regular exercise, we studied the effects of regular swimming and treadmill exercise on oxidative stress in the brain and liver of rats. Protein carbonyl was significantly reduced and the activity of proteasome was upregulated in the brain extracts of young and middle-aged animals after 9 weeks of swimming training. Furthermore, their cognitive functions were significantly improved. In separate experiments, the activation of transcription nuclear factor κB was attenuated in the liver of old rats after 8 weeks of regular treadmill exercise and the DNA binding activity of glucocorticoid receptor reduced with age was restored, suggesting that inflammatory reactions are alleviated by the regimen. This was accompanied by upregulation of the glutathione level and reduced reactive oxygen species generation. Similar training reduced the 8-oxodeoxyguanosine content in the nuclear and mitochondrial DNA of the liver of old rats. Thus, these findings, together with reports of other investigators, suggest that moderate regular exercise attenuates oxidative stress. The mild oxidative stress possibly elicited by regular exercise appears to manifest a hormesis-like effect in nonmuscular tissues, constituting beneficial mechanisms of exercise by adaptively upregulating various antioxidant mechanisms, including antioxidative and repair-degradation enzymes for damaged molecules. Importantly, the adaptation induced by regular exercise was effective even if initiated late in life. </P>

Tensile Properties and Fatigue Strength of Ultrafine Grained Pure Copper

Goto, Masahiro,Han, Seung Zeon,Kim, Sang Shik,Kawagoishi, Norio,Lim, Cha Yong Trans Tech Publications, Ltd. 2007 Key Engineering Materials Vol.353-358 No.3

<P>Oxygen-free copper was processed by equal channel angular pressing with different numbers of ECAP process cycles, NP. Tensile strength was increased with an increase in NP, but it tended to saturate after NP = 4. Conversely, elongation was dramatically decreased by first pressing, but it tended to saturate up to NP = 3, followed by slight increasing trend after NP = 4. Fatigue tests of specimens processed with NP = 4 and 8 were performed. The change in surface morphologies during fatigue was monitored successively. In addition to this, the change in surface hardness was measured. Significant decrease in surface hardness due to cyclic stresses was measured. The physical basis of fatigue damage of UFG copper was discussed based on the experimental results.</P>

Monitoring and Scheduling Methods for MIMO-FIFO Systems Utilizing Max-Plus Linear Representation

Goto, Hiroyuki,Masuda, Shiro Korean Institute of Industrial Engineers 2008 Industrial Engineeering & Management Systems Vol.7 No.1

This paper proposes an approach to monitoring and scheduling methods for repetitive MIMO-FIFO DESs. We use max-plus algebra for modeling and formulation, known as an effective approach for controller design for this type of system. Because a certain type of linear equations in max-plus algebra can represent the system's behavior, the principal concerns in past researches were how to solve the equations. However, the researches focused mainly on analyses of the relation between inputs and outputs of the system, which implies that the changes or the slacks of internal states were not clarified well. We first examine several properties of the corresponding state variables, which contribute to finding and tracing the float times in each process. Moreover, we provide a rescheduling method that can take into account delays or changes of the internal states. These methods would be useful in schedule control or progress management.

Crack growth rate of inclined and deflected surface-cracks in round-bar specimens of copper processed by equal channel angular pressing under cyclic loading

Goto, M.,Yamamoto, T.,Han, S.Z.,Kim, S.,Ahn, J-H.,Kitamura, J.,Iwamura, T.,Lee, J. Elsevier 2017 Engineering fracture mechanics Vol.182 No.-

<P>For low-cycle fatigued, ultrafine grained copper, processed by equal channel angular pressing, a unique crack growth direction, either inclined at 45 degrees or perpendicular to the loading direction, was observed around the circumference of round bar specimens. In addition, the perpendicular cracks showed a 45 degrees deflected crack face toward the center of the specimens. To clarify the growth behavior of such inclined and deflected cracks, the role of the deformation mode at the crack-tip areas was discussed in terms of the surface damage caused by cyclic stressing and the mixed-mode deformation at the crack tips. The preexistent shear-bands/shear-cracks around the crack tips and the in-plane shear-mode deformation at the crack tips assisted the formation of shallow inclined- and deep deflected-cracks. To quantitatively estimate the severity of mechanical damage at the crack tips, the comparative stress intensity factor range under combined mode I, II and III conditions were calculated. The crack growth rate along the growth direction at the surface and bottom for inclined and deflected surface-cracks was discussed in terms of the comparative stress intensity factor range. (c) 2017 Elsevier Ltd. All rights reserved.</P>

Eutectic Ceramic Composites by Melt-Solidification

Goto, Takashi,Tu, Rong The Korean Ceramic Society 2019 한국세라믹학회지 Vol.56 No.4

While high-temperature ceramic composites consisting of carbides, borides, and nitrides, the so-called ultra-high-temperature ceramics (UHTCs), have been commonly produced through solid-state sintering, melt-solidification is an alternative method for their manufacture. As many UHTCs are binary or ternary eutectic systems, they can be melted and solidified at a relatively low temperature via a eutectic reaction. The microstructure of the eutectic composites is typically rod-like or lamellar, as determined by the volume fraction of the second phase. Directional solidification can help fabricate more sophisticated UHTCs with highly aligned textures. This review describes the fabrication of UHTCs through the eutectic reaction and explains their mechanical properties. The use of melt-solidification has been limited to small specimens; however, the recently developed laser technology can melt large-sized UHTCs, suggesting their potential for practical applications. An example of laser melt-solidification of a eutectic ceramic composite is demonstrated.

Formation of a high-cycle fatigue fracture surface and a crack growth mechanism of ultrafine-grained copper with different stages of microstructural evolution

Goto, M.,Han, S.Z.,Euh, K.,Kang, J.H.,Kim, S.S.,Kawagoishi, N. Elsevier Science 2010 Acta materialia Vol.58 No.19

Fatigue tests were conducted on smooth specimens of ultrafine-grained copper produced by 4 and 12 passes of equal channel angular pressing (henceforth referred to as UFG4 and UFG12, respectively). A major crack was initiated from shear bands at an early stage of stressing. The UFG4 and UFG12 samples exhibited different growth behavior tendencies at a low crack growth rate (CGR). For UFG12, the CGR initially increased as the crack was extended with continued fatigue cycling, but then abruptly decreased before CGR reaching 10<SUP>-6</SUP>mm/c. This drop was temporary and was gradually recovered with subsequent cycling. The drop and recovery in CGR corresponded to the transitions from planar to granular fracture surface and from granular to striated fracture surface, respectively. For UFG4, there was no temporary CGR reduction, which corresponded to the change in the fracture surfaces from a planar to striated surface without any granulated surface formation. To understand the changes in growth rate and fracture surface morphologies, a quantitative model describing the crack growth mechanism is developed in this study by considering the reversible plastic zone size and the microstructural factors. The relationship between the crack growth behavior and the formation of the fracture surface is discussed based on the model.

Effect of Trace Impurities on High-Cycle Fatigue Damage of Ultrafine Grained Copper Processed by Equal Channel Angular Pressing

Goto, Masahiro,Teshima, N.,Han, Seung Zeon,Yakushiji, T.,Kim, Sang Shik Trans Tech Publications, Ltd. 2008 Materials science forum Vol.584 No.-

<P>In order to study the effect of trace impurities on high-cycle fatigue damage of ultrafine grained (UFG) copper, fatigue tests were carried out for two samples: oxygen-free copper (OFC, 99.99 wt% Cu) and deoxidized low-phosphorous copper (DLP, 99.95 wt% Cu). After the processing by equal channel angular pressing (ECAP) using eight passes, equiaxed grains with an average size of 250 nm were formed for both the samples. Fatigue strength of UFG copper was enhanced by the impurities. The formation behavior of surface damage and the change in surface hardness was monitored. A close relationship was observed between the change in hardness and the formation behavior of surface damage. The physical background of the effect of trace impurities on the fatigue damage was discussed from the viewpoints of surface damage formation behavior.</P>

High-cycle fatigue strength and small-crack growth behavior of ultrafine-grained copper with post-ECAP annealing

Goto, M.,Teshima, N.,Han, S.Z.,Euh, K.,Yakushiji, T.,Kim, S.S.,Lee, J. Pergamon Press ; Elsevier Science Ltd 2013 Engineering fracture mechanics Vol.110 No.-

The effects of post equal channel angular pressing annealing on microstructure and high-cycle fatigue behavior of ultrafine-grained copper were examined. Grains with sizes up to a few tens of micrometers surrounded by fine grains were formed after the annealing as a result of discontinuous recrystallization. The fatigue life of annealed samples in the short- and medium-life fields was found to decrease, while in the long-life field, the fatigue strength at 3x10<SUP>7</SUP> cycles was about 9% greater than that of ultrafine-grained copper without annealing. Long-term stressing for as-received ultrafine-grained samples produced large grains over 100μm as a result of dynamic recovery and recrystallization. For annealed samples, there were no significant differences in grain sizes between pre- and post-stressing, showing the higher stability of bimodal microstructure. This stability was related to the slightly increased fatigue strength in long life fields. The effect of bimodal microstructure on the growth behavior of small surface-cracks was discussed.