Papers by Keyword: Wavelet

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Authors: Gang Yu, Chang Ning Li, Sagar Kamarthi
Abstract: In this paper, a cluster-based feature extraction from the coefficients of discrete wavelet transform is proposed for machine fault diagnosis. The proposed approach first divides the matrix of wavelet coefficients into clusters that are centered around the discriminative coefficient positions identified by an unsupervised procedure based on the entropy value of coefficients from a set of representative signals. The features that contain the informative attributes of the signals are computed from the energy content of so obtained clusters. Then machine faults are diagnosed based on these feature vectors using a neural network. The experimental results from the application on bearing fault diagnosis have shown that the proposed approach is able to effectively extract important intrinsic information content of the test signals, and increase the overall fault diagnostic accuracy as compared to conventional methods.
Authors: Xiu Feng Zhang, Ke Ren Shi, Li Nan Zheng
Authors: Bum Won Bae, In Pil Kang, Yeon Sun Choi
Abstract: A fault diagnosis method based on wavelet and adaptive interference canceling is presented for the identification of a damaged gear tooth. A damaged tooth of a certain gear chain generates impulsive signals that could be informative to fault detections. Many publications are available not only for the impulsive vibration signal analysis but the application of signal processing techniques to the impulsive signal detections. However, most of the studies about the gear fault detection using the impulsive vibration signals of a driving gear chain are limited to the verification of damage existence on a gear pair. Requirements for more advanced method locating damaged tooth in a driving gear chain should be a motivation of further studies. In this work an adaptive interference canceling combined with wavelet method is used for a successful identification of the damaged tooth location. An application of the wavelet technique provides a superior resolution for the damage detection to the traditional frequency spectrum based methods. An analysis and experiment with three pair gear chain show the feasibility of this study yielding a precise location of the damaged gear tooth.
Authors: Chang Hai Li, Yan Chun Liu, Zhen Dong Xu
Abstract: In allusion to non-exactness edge positioning in the process of place a three-dimensional model, a method of multi-scale wavelet transfer is applied to obtain edge signals from satellite image and perform pixel dot correction, which is proved to give prominence to the landmark edge curve without avoiding sacrificing the precision position of the target landmark edge .This method, with fixed dot correction, makes it more convenient and more precisely to settle down edge positioning in the process , in order to place a three-dimensional model.
Authors: Sheng Bao Wang, D.S. Dong, Z.Y. Wang, Philippe Goudeau, L.A. Li, J.W. Tong
Authors: Cun Zhi Yao, Gui Xiang Zhang
Abstract: The non-linear and time-varying natures of the process together with the large disturbances of several types are the key challenge for the control design. A controller based on multi- resolution decomposition using wavelets is presented in the paper. The wavelet is used to decompose the error signal into signals at different scales.These signals are then used to compensate for the uncertainties in the plant.The controller is similar to proportional integral derivative controller in principle and application. the output from this control system represents the cumulative effect of uncertainties such as measurement noise, frictional variations and external torque disturbances which manifest at different scales. This controller better solves the nonlinear and time-varying togetther with the great disturbance.
Authors: Sanaz Shahraeini, Mahdi Yaghoobi
Abstract: The recent progress in the digital multimedia technologies has offered many facilities in the transmission, reproduction and manipulation of data. However, this advance has also brought the problem such as copyright protection for content providers. Digital watermarking is one of the proposed solutions for copyright protection of multimedia. This paper proposes a blind watermarking algorithm based on fractal model in discrete wavelet domain for copyright protection. The idea of the presented scheme is to hide a binary image as a watermark with fractal parameters in wavelet domain of host image. Fractal compression technique is used to encode a gray image and fractal codes are embedded into the wavelet coefficients of the gray image according to well-connected watermark algorithm. The experimental results show that the algorithm is robust against geometric and non geometric attacks.
Authors: Hun Chi Kai, Xiao Lin Tian
Abstract: A new color fidelity algorithm to reduce sensor noise for high-ISO images has been proposed. The new algorithm uses HSV color space on wavelet domain to denoise high-ISO images by a weighted mean filter, which is designed based on analysis of the different noise models of high-ISO images. Testing results are satisfactory, which have shown that the new algorithm could reduce noise in high-ISO images faster, as well as no any color distortion in original images during the denoising processing.
Authors: Feng Yan, Shuang Shuang Li
Abstract: By using the advantages of C-type of traveling wave fault location method in distance measuring and the pattern recognition function of support vector machines (SVM),a new fault location method is presented.The first step of the method is determining the fault distance by C-type of traveling wave location method; the second one is locating the fault section by SVM. It also adopts the wavelet to reduce the noise of fault signal,and the accuracy can be more precise when the parameters of SVM are optimized.The simulation results of ATP and MATLAB show that the method can determine the single phase grounding fault point in 10kv distribution networks with branches accurately.
Authors: G.R. Gnana King, C. Christopher Seldev, N. Albert Singh
Abstract: Compound image is a combination of natural images, text, and graphics.This paper presents a compression technique for improving coding efficiency. The algorithm first decomposes the compound images by using 3 level biorthogonal wavelet transform and then the transformed image was further compressed by Parallel dictionary based LZW algorithm called PDLZW.In PDLZW algorithm instead of using a unique fixed word width dictionary a hierarchical variable word width dictionary set containing several dictionaries of small address space and increases the word widths used for compression and decompression algorithms. The experimental results show that the PSNR value is increased and the Mean Square error value was improved.
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