Orthogonal frequency division multiplexing (OFDM) systems have attracted attention as the fourth generation mobile communication systems. In OFDM systems, the impact of a fading is identified by using the channel estimation (CE). However, a large number of pilot symbols is required to identify an accurate channel state information (CSI) in the conventional OFDM systems. To reduce this problem, a time frequency interferometry (TFI) for OFDM has been proposed. Under the fast fading environment, since the channel is rapidly changed, many errors are occurred. Therefore, we have proposed the fast fading compensation method by using the decision direct and linear prediction methods. However, this method has several problems. To overcome these problems, in this paper, we propose the nonlinear prediction method based on the weighted channel variance.

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In DCT-based image watermarking, the optimal embedding of the watermark into some of the selected coefficients should depend both on the image content and the trade-off between watermark imperceptibility and watermark robustness. To deal with the image content, an image block classification was applied on each 8 × 8 DCT block. For each region type, Ant Colony System Algorithms were designed and developed to search for the optimal trade-off between watermark imperceptibility and watermark robustness. The resulting optimal frequency bands and embedding strength for watermark embedding were therefore dependent on the region type. The experimental results show that the proposed scheme yielded a watermark that was invisible and robust against various image manipulations. The effectiveness of this algorithm was also compared with those of previous studies.

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Electric power systems in Japan suffer from major damage from typhoons almost every year. Typhoons often cause undesirable long-time power failures. To speedily restore the electric power supply, one needs to predict the amount of damage accurately for an approaching typhoon. This paper presents a method of predicting the amount of electric power damage for the Amami archipelago using Gaussian process (GP) regression. The typhoon track is evaluated by considering its wind characteristics. A nonstationary kernel is introduced as the covariance function of the GP in consideration of the nonstationarity of damage. This predictor can yield not only the predicted amounts of damage but also their confidence measures. Simulation results based on actual data are shown to illustrate the effectiveness of this approach.

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In this paper, we propose an audio watermarking method in the discrete wavelet transform (DWT) and discrete cosine transform (DCT) domains using singular value decomposition (SVD) and quantization. In our proposed method, the original audio is initially segmented into nonoverlapping frames. Watermark information is embedded into the largest singular value of the DCT coefficients obtained from the DWT coefficients of each audio frame by quantization. Simulation results demonstrate that the proposed watermarking method is not only robust against various attacks but also achieves a good trade-off among imperceptibility, robustness, and payload. In addition, audio quality evaluation tests indicate the high imperceptibility of the watermark in the audio signal. The performance analysis of the proposed method shows low error probability rates. Moreover, it has a high data payload and superior performance to state-of-the-art audio watermarking methods.

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This paper presents a method of maturity detection of the tropical fruits using a smell sensor. We investigate many sensing data of different fruits and find out that the data of the fruits are characterized as a first-order lag element. The first-order lag element has two parameters: gain and time constant. Knowing the gain and time constant of the smell data is useful for detecting the maturity of the fruits. In this paper, we apply a genetic algorithm to identify the gain and time constant parameters for the sensing data. Experiments of the maturity detection for monkey bananas and guavas show good results.

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In case of the motion equation for molecules supposed as represented by a difference equation for the displacement of molecules, LC ladder circuit of a periodic system is obtained as an equivalent circuit. As the LC circuit shows reciprocal and lossless, we can apply the iteration parameter theory and we obtain complex impedances. That is, we have to consider complex power for a one-dimensional crystal, although in kinetic theory a crystal is analyzed by a real function. Since the time integral of complex power denotes energy, reactive power is not related to energy, but is related to oscillation. As the result, we can show that the eigen oscillation of a one-dimensional crystal is caused by reactive power.

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