著者

上原 賢祐 齊藤 俊

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

pp.18-00218, (Released:2018-08-01)

参考文献数

13

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Electroencephalogram (EEG) which has a chaotic fluctuation is difficult to analyze. However, quantitative analysis is sufficiently possible since EEG behavior is deterministic dynamics. Our method identifies EEG model parameters experimentally in consideration of chaotic dynamics of EEG. The purpose of this study is to examine the specific characteristics of model parameters. Validation of the method and investigation of characteristics of model parameters were conducted based on alpha frequency EEG data in the relax state and stress state. The results of the parameter identification with the time sliding window for 1 second, the nonlinear mathematical model is shown to produce outputs that can closely match the complicated experimental EEG data. Further, the results showed that the existence of nonlinear term in the EEG analysis is important and the linearity parameter shows a certain tendency as the nonlinearity increases. Furthermore, the activities of EEG become linear on the mathematical model when suddenly changing from the relax state to the stress state. Therefore, it is the effective analysis method that can calculate the degree of concentrate from the dynamics of EEG signal directly. The results suggest that our method may provide useful information in various field including the quantification of human mental or psychological state, diagnosis of brain disease such as epilepsy and design of brain machine interface.

著者

上原 賢祐 森 浩二 齊藤 俊

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.83, no.849, pp.16-00473-16-00473, 2017 (Released:2017-05-25)

参考文献数

19

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A Peltier element is considered as a way to enable local temperature control and also has several advantages including rapid thermal response, no vibration and compactness. Therefore, a focal cooling device using a Peltier element for treatment is expected to apply to various parts of a living body. In the design of the device ensuring both the energy efficiency and therapeutic effect, it is necessary to understand the thermoelectric conversion characteristics of the Peltier element and the thermal conductivity of the attachment in the device, which should be designed in accordance with the cooling performance and size. Therefore, the investigation using a mathematical model is believed to play an important role in such case. The purposes of this study are to clarify the characteristics of the model parameters and to investigate whether performance evaluation of the device from its characteristics is possible. Model parameters were identified experimentally using three prototypes of different sizes and cooling abilities. From the result of the parameter identification, internal resistance and thermal conductance of the Peltier device are dependent on the cooling performance. The parameters representing the thermal conductance between each attachment in the device are strongly depend on the size. However, changes of these parameters were smaller than the size ratio of the device. Our results suggest that it can provide useful information to the designer.