Browsing by Author "Yazar, A."

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    Fall detection using single-tree complex wavelet transform
    (Elsevier, 2013) Yazar, A.; Keskin, F.; Töreyin, B. U.; Çetin, A. Enis
    The goal of Ambient Assisted Living (AAL) research is to improve the quality of life of the elderly and handicapped people and help them maintain an independent lifestyle with the use of sensors, signal processing and telecommunications infrastructure. Unusual human activity detection such as fall detection has important applications. In this paper, a fall detection algorithm for a low cost AAL system using vibration and passive infrared (PIR) sensors is proposed. The single-tree complex wavelet transform (ST-CWT) is used for feature extraction from vibration sensor signal. The proposed feature extraction scheme is compared to discrete Fourier transform and mel-frequency cepstrum coefficients based feature extraction methods. Vibration signal features are classified into "fall" and "ordinary activity" classes using Euclidean distance, Mahalanobis distance, and support vector machine (SVM) classifiers, and they are compared to each other. The PIR sensor is used for the detection of a moving person in a region of interest. The proposed system works in real-time on a standard personal computer.
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    An investigation on the optimization of electrochemically pigmented aluminum oxide collector coatings
    (Elsevier, 1997-03) Kadirgan, F.; Söhmen, M.; Türe, I. E.; Süzer, Ş.; Wetherilt, J.; Yazar, A.
    In order to produce selective coatings on aluminium substrates to be used as absorber plates in high efficiency solar collectors, nickel pigmentation has been applied to anodically oxidized surfaces. Optical and structural properties of electrochemically formed aluminium oxide films as function of electrolysis conditions such as, applied current, pH, temperature and concentration of metal ions have been examined using electron spectroscopy and scanning electron microscopy. The optimisation of the absorptivity/emissivity ratio of the surfaces in terms of preparation conditions is described. Nickel pigmentation of porous aluminum surfaces was also investigated as a function of electrochemical pigmentation conditions. Mechanisms contributing to selectivity in anodically produced oxides and electrodeposits are discussed. Copyright © 1996 Published by Elsevier Science Ltd.