Browsing by Author "Chen, Chih-Min"

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High-Performance Seizure Detection System Using a Wavelet-Approximate Entropy-fSVM Cascade With Clinical Validation
(2013-10-01)
Shen, Chia-Ping
;
Chen, Chih-Chuan
;
Hsieh, Sheau -Ling
;
Chen, Wei-Hsin
;
Chen, Jia-Ming
The classification of electroencephalography (EEG) signals is one of the most important methods for seizure detection. However, verification of an atypical epileptic seizure often can only be done through long-term EEG monitoring for 24 hours or longer. Hence, automatic EEG signal analysis for clinical screening is necessary for the diagnosis of epilepsy. We propose an EEG analysis system of seizure detection, based on a cascade of wavelet-approximate entropy for feature selection, Fisher scores for adaptive feature selection, and support vector machine for feature classification. Performance of the system was tested on open source data, and the overall accuracy reached 99.97%. We further tested the performance of the system on clinical EEG obtained from a clinical EEG laboratory and bedside EEG recordings. The results showed an overall accuracy of 98.73% for routine EEG, and 94.32% for bedside EEG, which verified the high performance and usefulness of such a cascade system for seizure detection. Also, the prediction model, trained by routine EEG, can be successfully generalized to bedside EEG of independent patients.
Spiral surface plasmon modes inside metallic nanoholes
(2015-11-16)
Chen, Chih-Min
;
Ke, Jian-Liang
;
Lan, Yung-Chiang
;
Chan, Ming-Che
;
光電學院
Spiral surface plasmon (SSP) modes that propagate inside a silver (Ag) nanohole are investigated by performing both simulations and theoretical analyses. The SSP modes are formed by a linear combination of two rotating SP eigenmodes of the Ag nanohole in the fast-wave branch. Inside a uniform Ag nanohole, the handedness and the number of strands of the SSP modes are determined by both the component SP eigenmodes and their rotation directions. The spiral pitch of the SSP mode increases with the nanohole radius for a fixed wavelength and is inversely related to the incident wavelength for a fixed nanohole radius. Inside a tapered Ag nanohole, the spiral pitch decreases with the reduction of nanohole radius. However, the azimuth-integrated field energy density increases to a maximum value and then falls. For a tapered Ag-clad fiber capped by a tapered Ag nanorod, the SSP mode reverses its handedness when it passes through the fiber-nanorod interface. Furthermore, using this composite structure, the field energy density of SSP mode that arrives at the tip of the tapered nanorod is largely increased. (C) 2015 Optical Society of America