Publications by authors named "Shu-xin Du"

Spectral smoothing is commonly used as effective pretreatment methods in the spectral analysis. However, the conventional Savitzky-Golay polynomial smoothing methods used in two-dimensional spectral analysis can not be applied to three-dimensional spectrometry directly. In the present paper, a polynomial surface smoothing method is proposed, and the two-dimensional Savitzky-Golay polynomial smoothing methods are extended to three-dimensional fluorescence spectra.

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The absorption rate of ultraviolet could be used to measure the concentration of organic pollutant, as most of the organic pollutant has stronger absorption rate in ultraviolet region in water. In the present paper, principal component regression (PCR), partial least squares (PLS), and support vector machine (SVM) were respectively used to model a regression model after the spectrum preprocessing, such as smoothing, derivation, standard normal variate transformation (SNV), etc. Then, the concentration of organic pollutant could be measured via the ultraviolet spectrum and the regression model.

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Based on three-dimensional first-order derivative fluorescence spectrometry, an analysis method for detecting dissolved organ matter in water is proposed in the present paper. By using simplified least squares differentiation methods presented by Savitzky and Goly, the first-order partial derivatives for emission wavelength and excitation wavelength were calculated. As the fitting polynomial has the smoothing function in the calculation of derivative spectra, a separate smoothing method is not required to remove spectrometry noise.

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For linear switched system with both parameter uncertainties and time delay, a delay-dependent sufficient condition for the existence of a new robust H infinity feedback controller was formulated in nonlinear matrix inequalities solvable by an LMI-based iterative algorithm. Compared with the conventional state-feedback controller, the proposed controller can achieve better robust control performance since the delayed state is utilized as additional feedback information and the parameters of the proposed controllers are changed synchronously with the dynamical characteristic of the system. This design method was also extended to the case where only delayed state is available for the controller.

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A new neural network based method for solving the problem of congestion control arising at the user network interface (UNI) of ATM networks is proposed in this paper. Unlike the previous methods where the coding rate for all traffic sources as controller output signals is tuned in a body, the proposed method adjusts the coding rate for only a part of the traffic sources while the remainder sources send the cells in the previous coding rate in case of occurrence of congestion. The controller output signals include the source coding rate and the percentage of the sources that send cells at the corresponding coding rate.

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