The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The objective of this work is to detect delay times between two ultrasonic signals, one of them considered as a reference and the other signal as the signal to be evaluated, using the wavelet transform, to indirectly estimate temperature changes. In this work the evaluation of 3 types of wavelets (Morlet, Mexican Hat and Daubechies 5) was made to detect the delay time in echo ultrasonic signals which...
Some improvements in the classification of masses in the breast are proposed in this paper. First, for the purpose of enriching the information concerning the shape of the mass, a new morphological feature is extracted. Then, the textural features of the region of interest (ROI) are extracted by combining the undecimated wavelet transform (UWT) and the gray level co-occurrence matrix (GLCM). Finally,...
Aiming at the image distortion caused by turbulence, an infrared image fuzzy measure algorithm based on local kurtosis of wavelet transform is proposed to identify the Two-dimensional (2D) Gaussian function model of the turbulence degraded image. In the process of image restoration, the Haar wavelet transform is applied to reduce the correlation of the image region. Then, the transformed coefficients...
Cushing response is the reaction of blood pressure, heart rate and respiratory pattern to increased intracranial pressure. We try to recognize this well-known phenomenon in a patient with head injury, using wavelet transform to abolish noises and preserve the true signals.
This paper presents an analog-to-digital converter with a novel adaptive wavelet-based sampling scheme. The proposed algorithm uses the wavelet transform to localize critical points in the signal, while the estimated Lipschitz exponent describes the signal's shape. Also, a polynomial reconstruction method is proposed and applied to the converter's outputs for a test signal. Results show that it is...
This paper proposes an image steganography for hiding secret images. The objective of the proposed work is to increase the embedding capacity while ensuring the security of the image. This has been addressed using two levels of processing. First is the application of Genetic Algorithm (GA) as ‘before embedding hiding technique’ which tries to identify suitable places in cover image where embedding...
In this paper, we extend the recent definition of graph stationarity into a definition of local stationarity. Doing so, we present a metric to assess local stationarity using projections on localized atoms on the graph. Energy of these projections defines the local power spectrum of the signal. We use this local power spectrum to characterize local stationarity and identify sources of non-stationarity...
Scale-free dynamics commonly appear in individual components of multivariate data. Yet, while the behavior of cross-components is crucial in modeling real-world multivariate data, their examination often suggests departures from exact multivariate self-similarity (also termed fractal connectivity). The present paper introduces a multivariate Gaussian stochastic process with Hadamard (i.e., entry-wise)...
With the development of Internet technology, Internet security issues become increasingly prominent. People transfer a large amount of digital images on the Internet every day, in order to protect the security of the digital image, the most direct and effective way is to encrypt the digital image. Chaotic encryption system with natural characteristics, chaotic image encryption can effectively protect...
Interturn faults are a critical problem in power transformers that can eventually escalate into catastrophic faults and probably result in an overall network failure. Also, failures in transformer windings are still a major cause of transformer outages, and failure rates vary widely between different countries and systems, depending on many factors. Therefore, in this work, interturn faults with various...
Traffic analysis using classical methods of queuing theory supposes independent or at least uncorrelated traffic counts. This article is about using wavelet transform for decreasing correlation in strongly correlated traffic. Also shown the transform of the probability density function of the source of traffic using two-dimensional probability density function and a “model” distribution based on cumulant...
Synchronization can be considered as a fundamental property for dynamical system in scientific fields, which is used to describe the asynchronous behaviour in time-frequency domain. The statistical analysis of solar time series can obtain some useful information to characterise and predict the long-term variability of the Sun. In this paper, two analysis approaches, including wavelet coherence transform...
Correct incipient fault diagnosis is crucial to the health management of the analog circuits, though remaining challenging. This paper presents a novel fault diagnosis method to diagnose ordinary soft fault and incipient soft fault for linear analog circuit. Due to the presence of analog circuit noise stress and the tolerance of the components, the linear circuit responses are considered as a stochastic...
Commutation failure is one of the common faults in HVDC system, which has an adverse impact on the safe operation of the entire power system. Fast and accurate diagnosis for commutation failure plays an important role in controlling the commutation failure. Firstly this paper introduces the concept of HVDC system and situation of research on commutation failure fault diagnosis, in which the shortcomings...
Nowadays, wavelet transform (WT) is widely used in the realm of signal denoising, has proven a high effectiveness in terms of time and quality concerning denoising methods. Despite there are several achievements denoising through wavelet thresholding methods, these do not disclose an optimal configuration. In this paper, we proposed a comparative performance analysis of several thresholding methods...
In side channel attacks (SCA), noise has been a hot topic for affecting the quality of obtained observations. In this paper, we propose a kind of improved wavelet transform denoising method based on singular spectral analysis (SSA) and detrended fluctuation analysis (DFA). Principal signal component in SSA can be selected by DFA adaptively, and residual part can be denoised by wavelet transform to...
Cyber-Physical Systems (CPS) require tools that enable development of design methodology that supports analysis and modeling of Interaction Dynamics of Concurrent Processes (IDCP) represented by the measurement data provided by smart acquisition systems. In this paper, are presented some results of the project aiming at the development of algorithms and software tools that could detect short-lived...
Advances in hyper spectral imaging sensors makes it possible to obtain high dimensional and high resolution data which poses challenges for computational cost and time. As the inter-band resolution is high in hyper spectral images, the spectral dimension could be reduced without significant loss of useful information. This requires careful application of dimensionality reduction techniques to reduce...
In the last few years, numerous new methods have been proposed to overcome the complexity of the signals generated by complex machines and those generated by faults. Monitoring and fault diagnosis methods based on signal processing have proved effective in fault identification. The present paper introduces the theory of wavelet transforms coefficients (WTC) processes and autocorrelation as powerful...
Cardiac auscultation is a non-invasive procedure that is mainly used in primary care, and involves diagnosis through analysis of the two heart sounds emanating from the cardiac cycle. None of the existing methods of computer aided auscultation can run in real time, and identify both S1 and S2 heart sounds, and operate without prior learning, and operate without making crude assumptions about the signal...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.