Polycrystalline solar wafers consist of various crystals and their surfaces have heterogeneous textures. The conventional defect detection methods cannot be applied to their solar wafers. In this paper, we propose a concept of local binary mean and its optimization method for selecting optimal threshold T . The input image is broken down into a set of K patch images. Each patch image is used to calculate its local binary mean. The local binary mean value is used as the discrimination measure for detecting defects. Experimental results show that our proposed method achieves a detection rate of 91∼94 %. Compared with related defect detection methods, the proposed method has the advantage of detecting various kinds of low gray-level defects such as micro-cracks, fingerprints, and contaminations simultaneously.
Generation of a quiet zone in noisy environment is undoubtedly of considerable realistic significance. This paper describes development and implementation of a multichannel real-time active noise control (ANC) system for 3 dimensional noisy environment to enhance the quiet zone performance in terms of size and noise cancellation gain. The proposed ANC system employes a multichannel delay-compensated filtered-X least mean square (FXLMS) algorithm; its real-time implementation is designed in TMS320C6713 digital signal processor (DSP) board. The system is evaluated for cancelling various tonal frequency noises in the range from 100 to 500 Hz, and the performance is then illustrated by measuring the quiet zone in terms of sound pressure level (SPL) attenuation. Experiment results show that a quiet zone of quiet with satisfactory size and maximum 24 dB noise attenuation is successfully generated.
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