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The paper concerns improvement of the acoustic emission (AE) methods applied in diagnosing of insulations systems of electric power transformer. During detection of AE signals emitted by partial discharges (PD) occurring in insulation systems of power transformer, there exist different forms of interference sources, which may have a direct impact on the correct evaluation of the measured signals obtained...
In the era of technology, signal transmission or signal recording is inseparable with the advent of noise. This study aims to eliminate noise (noise) on the ultrasonic signals to dolphins recording voice, as well as to determine the level of decomposition and the best kind on wavelet threshold with evidentiary value of SNR (Signal to Noise Ratio). Haar wavelet type is used in this study. One of the...
The discrete cosine transform (DCT) is known to be asymptotically equivalent to the Karhunen-Loève transform (KLT) of Gaussian first-order auto-regressive (AR(1)) processes. Since being uncorrelated under the Gaussian hypothesis is synonymous with independence, it also yields an independent-component analysis (ICA) of such signals. In this paper, we present a constructive non-Gaussian generalization...
An orthosis embedded with a surface electromyography (sEMG) measurement system, integrated with metal-polymer composite fibers, was used to monitor the electrical activity of the forearm muscles during movement. The comfortable and noninvasive sEMG system was developed for long term monitoring during rehabilitation. Wavelets were used to denoise and compress the raw biosignals. The focus here is a...
The popular existing de-noising methods are compared and analyzed, including wavelet packet decomposition, coefficient shrinkage and modulus maxima method of wavelet transform, which advantages and disadvantages are analyzed and summarized. So their suitable scopes and premise condition are obtained. To accurately analyze high frequency part of signal in submarine tunnel monitoring, the maxima method...
Side-channel power analysis attacks have been proven to be the most powerful attacks on implementations of cryptographic primitives. DPA and CPA are probably the most wide-spread practical attacks on numerous embedded cryptographic systems. Additive noise is a kind of typical power analysis resistant implementing technique. The success rate of the DPA and CPA attacks is significantly affected by the...
Image in the process of collection and storage can produce noise. Wavelet threshold de-noising is a method to remove noise effectively. The threshold function is a key in wavelet threshold de-noising method. In view of the hard-threshold function discontinuity and soft-threshold function deviation problem, through the analysis of the existing wavelet threshold de-noising methods, we present the improvement...
The random noise is an important factor that affects the precision of MEMS gyroscope. Analyzed the noise characteristic of gyroscope by using Allan variance, introduced the thought of wavelet threshold de-noising method, and presented an improved wavelet threshold quantization function. Expatriate the complete build process of wavelet threshold denoising scheme and examined the effectiveness and repeatability...
In this article, the characteristics, theories and classification of the threshold de-noising method are introduced in detail. According to the study, when wavelet threshold de-noising method is compared with the wavelet packet threshold de-noising method, the first method is suitable for dealing with the low frequency information, but the second method is available to deal with the information with...
This paper presents a new method of threshold estimation for ECG signal denoising using wavelet decomposition. In this method, threshold is computed using the maximum and minimum wavelet coefficients at each level. Using this threshold and well known Hard thresholding process, the significant wavelet coefficients from each level are selected and denoised ECG signal is reconstructed with inverse wavelet...
In the avionics test, sensor signal samplings are often subjected to the interference of all kinds of noise, which could not accurately reflect the real operating status of the equipment and should not be directly used for data processing and analysis. In order to de-noise test data, a new threshold function is presented and the preprocessing wavelet is determined by reconstruction factor according...
In this research we scrutinize the face recognition system performance when the test images are imposed to different levels of noise. We tried to imitate the real world scenarios when the face images are captured from video cameras or scanners and suffer some noise. To investigate the performance of proposed system, we simulate this scenario by adding AWGN (additive white Gaussian noise) to the test...
In this paper, de-noising using Wavelet transforms and Empirical mode decomposition (EMD) was performed on two sets of atmospheric radar data. Wavelets and EMD has been applied to the time series data obtained from the mesosphere-stratosphere-troposphere (MST) region near Gadanki, Tirupati. Wavelet analysis is one of the most important methods for removing noise and extracting information from any...
It is possible to carry out PD location using the time difference of PD pulses received by a UHF antenna array. In practical applications, the electromagnetic interference within the substation will pollute these received signals and make it difficult to calculate the time difference of the PD pulses, which, thus, reduces the reliability of the PD source locating. Based on the segmented processing...
Impulse voltage tests are essential to inspect and test insulation integrity of high voltage apparatus. On the other hand, generated impulse currents are used for different test applications such as investigation of high current effects, electromagnetic interference (EMI) testing, etc. Obtained voltage and current waveforms usually have some sort of interferences originated from the different sources...
Aiming to the ECG signal including the noise such as the baseline drift, power frequency interference, and muscle power interference, etc, it is not easy to diagnose the patient's illness condition, so, the wavelet de-noising algorithm used in ECG signal is research in detail. This paper studied the wavelet multi-resolution decomposition and de-noising methods, as well as analyzes the way of the threshold...
In order to overcome the shortcoming of the soft-threshold denosing method in curvelet domain, which may cause edges blurred, a new denoising method based on the edge features of the given image is proposed. In this method, we make full use of the anisotropie advantages of curvelet, extract the detail and edge information from the low-frequency domain and restore it, which can prevent the destruction...
This paper applies empirical mode decomposition (EMD) combined with translation invariant (TI) scale-adaptive soft-hard compromise threshold method to achieve seismic random noise reduction. Commonly, the Gibbs phenomenon produced by wavelet transform is derived from the basis function which leads to artifacts in discontinuities. TI is a method which could suppress Gibbs artifacts efficiently and...
The learning algorithm and determination of network parameters of dynamic fuzzy neural network (DFNN) implements Takagi¨CSugeno¨CKang (TSK) fuzzy systems based on extended radial basis function neural networks (RBFNN) are introduced, combing wavelet transform with DFNN, a landslide deformation mornitoring data denoising by wavelet transform to divide noise from the original deformation data to obtain...
Aiming at the deficiencies of using traditional Fourier transform method to denoise the image data of visual measurement edge detection, the application on wavelet analysis in denoising of visual measurement edge detection. The three-dimensional model of visual measurement based on binocular vision camera was built up firstly, of which on the basis, the wavelet analysis method was used to combine...
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