ANALYSIS OF CAROTID ARTERIAL DOPPLER SIGNALS USING STFT AND WIGNER–VILLE DISTRIBUTION (WVD)

2009 ◽  
Vol 09 (01) ◽  
pp. 49-62
Author(s):  
MELLE SEDDIK AMINA ◽  
M. BEREKSI REGUIG FETHI
Keyword(s):  
Power Spectra ◽  
Doppler Imaging ◽  
Time Frequency ◽  
Ultrasound Frequency ◽  
Doppler Signals ◽  
Cross Terms ◽  
Noticeable Reduction ◽  
Doppler Power ◽  
Short Time

The study presented in this paper is concerned with the analysis of the ultrasound Doppler signal of the carotid arteries in the time-frequency domain using the short time Fourier transform (STFT) and the Wigner–Ville distribution (WVD). This study is carried out in order to investigate the behavior of the spectral broadening index (SBI) derived from spectra obtained using these methods. The variations in the shape of the Doppler power spectra as a function of time are presented in the form of sonograms in order to determine the degree of primitive carotid artery stenosis. The obtained results show a qualitative improvement in the appearance of the sonograms generated using the WVD over the STFT. However, despite this qualitative improvement the WVD suffers from some drawbacks: the presence of the cross terms which are primarily due to its quadratic nature. The application of the Choi–Williams distribution (CWD) in this analysis shows a noticeable reduction of these cross terms, improving therefore the quality of the sonograms. From these generated sonograms, the ultrasound frequency envelopes are extracted. The maximum and the mean frequencies in these envelopes are used to determine the SBI. The magnitude of the CWD-SBI is significantly greater than that of the STFT-SBI. In addition, there is a correlation between the SBIs obtained using the STFT and the CWD and the degree of severity of stenosis measured by 2D Doppler imaging.

Evaluation of potential auras in generalized epilepsy from EEG signals using deep convolutional neural networks and time-frequency representation

2020 ◽  
Vol 65 (4) ◽  
pp. 379-391 ◽  
Author(s):  
Hasan Polat ◽  
Mehmet Ufuk Aluçlu ◽  
Mehmet Siraç Özerdem
Keyword(s):  
Eeg Signals ◽  
Deep Convolutional Neural Networks ◽  
One Dimensional ◽  
Time Frequency ◽  
Specificity And Sensitivity ◽  
Frequency Representation ◽  
Proposed Model ◽  
Generalized Epilepsy ◽  
Short Time

AbstractThe general uncertainty of epilepsy and its unpredictable seizures often affect badly the quality of life of people exposed to this disease. There are patients who can be considered fortunate in terms of prediction of any seizures. These are patients with epileptic auras. In this study, it was aimed to evaluate pre-seizure warning symptoms of the electroencephalography (EEG) signals by a convolutional neural network (CNN) inspired by the epileptic auras defined in the medical field. In this context, one-dimensional EEG signals were transformed into a spectrogram display form in the frequency-time domain by applying a short-time Fourier transform (STFT). Systemic changes in pre-epileptic seizure have been described by applying the CNN approach to the EEG signals represented in the image form, and the subjective EEG-Aura process has been tried to be determined for each patient. Considering all patients included in the evaluation, it was determined that the 1-min interval covering the time from the second minute to the third minute before the seizure had the highest mean and the lowest variance to determine the systematic changes before the seizure. Thus, the highest performing process is described as EEG-Aura. The average success for the EEG-Aura process was 90.38 ± 6.28%, 89.78 ± 8.34% and 90.47 ± 5.95% for accuracy, specificity and sensitivity, respectively. Through the proposed model, epilepsy patients who do not respond to medical treatment methods are expected to maintain their lives in a more comfortable and integrated way.

Using ASTFT Spectrum to Suppress Cross Terms in WVD and its Application in Fault Diagnosis

2009 ◽  
Vol 626-627 ◽  
pp. 535-540
Author(s):  
B.P. Tang ◽  
F. Li ◽  
W.Y. Liu
Keyword(s):  
Feature Extraction ◽  
Fourier Transform ◽  
Fault Diagnosis ◽  
Short Time Fourier Transform ◽  
Time Frequency ◽  
Effective Suppression ◽  
Cross Terms ◽  
Diagnosis Method ◽  
Simulation Results ◽  
Short Time

A new fault diagnosis method to suppress cross terms of Wigner-Ville distribution (WVD) using Adaptive Short-time Fourier Transform (ASTFT) spectrum is put forward. The relationships of correlation between auto terms and cross terms of WVD are obtained theoretically by analyzing the WVD. Firstly, the signal ASTFT spectrum which can determine the signal component positions in the time-frequency plane is obtained. Then, the ASTFT spectrum as a window function is selected to process the signal WVD. Thus the cross terms can be effectively restrained. The simulation results show that a better resolution and more effective suppression of cross terms can be obtained. At last, the proposed method is applied to the fault diagnosis of bearing. The simulation and the experiment results indicate that the proposed method is effective in feature extraction.

scholarly journals Packets Wavelets and Stockwell Transform Analysis of Femoral Doppler Ultrasound Signals

2018 ◽  
Vol 8 (6) ◽  
pp. 4212
Author(s):  
M. Latfaoui ◽  
F. Bereksi Reguig
Keyword(s):  
Wavelet Packet ◽  
Short Time Fourier Transform ◽  
Time Frequency ◽  
Femoral Arteries ◽  
Continuous Wavelets ◽  
S Transform ◽  
Doppler Signals ◽  
Cardiovascular Pathologies ◽  
Stockwell Transform ◽  
Short Time

<p>Ultrasonic Doppler signals are widely used in the detection of cardiovascular pathologies or the evaluation of the degree of stenosis in the femoral arteries. The presence of stenosis can be indicated by disturbing the blood flow in the femoral arteries, causing spectral broadening of the Doppler signal. To analyze these types of signals and determine stenosis index, a number of time-frequency methods have been developed, such as the short-time Fourier transform, the continuous wavelets transform, the wavelet packet transform, and the S-transform.</p>

Inter-Harmonics Analysis Based on the STFT Applied to the Power System

2013 ◽  
Vol 662 ◽  
pp. 864-867
Author(s):  
Hui Guo ◽  
Shu Chuan Gan ◽  
Hao Wu
Keyword(s):  
Fourier Transform ◽  
Power System ◽  
Frequency Characteristics ◽  
Theoretical Base ◽  
Harmonic Detection ◽  
Short Time Fourier Transform ◽  
Time Frequency ◽  
Short Time

This paper introduces a method of analyzing the time-frequency characteristics for inter-harmonics by Short Time Fourier Transform (STFT). Compared with the traditional arithmetic, the STFT can acquire more precise results and provides theoretical base for inter-harmonic detection. The STFT is used to analyze the inter-harmonics by selecting proper window slides function in Matlab which can acquire more precise resolution for the time-frequency characteristics. This method is useful to eliminate the inter-harmonics in power system. So the quality of power energy can be further improved.

The STFT Applied to Inter-Harmonics Analysis in Transformer

2013 ◽  
Vol 373-375 ◽  
pp. 1595-1598
Author(s):  
Hui Luo ◽  
Hao Li ◽  
Liang Cao
Keyword(s):  
Fourier Transform ◽  
Theoretical Basis ◽  
Frequency Characteristics ◽  
Harmonic Detection ◽  
Short Time Fourier Transform ◽  
Time Frequency ◽  
Clear Result ◽  
Short Time

This paper introduces that the Short Time Fourier Transform (STFT) could be applied to analyze the time-frequency characteristics of inter-harmonics in transformer. Compared with the traditional Fourier Transform, the STFT could acquire more clear result, and offers theoretical basis for inter-harmonic detection. The STFT is used to analyze the inter-harmonics by selecting proper window slides function in Matlab which can obtain more precise resolution for the time-frequency characteristics. This method is useful to eliminate the inter-harmonics in transformer. It is helpful to improve the quality of power.

Wear state evaluation of inner-diameter saw blade based on vibration and noise signals during processing

2020 ◽  
pp. 095440542094910
Author(s):  
Yong-Chen Pei ◽  
Qin-Jian Liu ◽  
Ru-Shi Zhao ◽  
Hang Zhang
Keyword(s):  
Real Time ◽  
Low Cost ◽  
Good Method ◽  
Short Time Fourier Transform ◽  
Time Frequency ◽  
State Evaluation ◽  
Inner Diameter ◽  
Saw Blade ◽  
Short Time

Slicing and cutting processing by inner-diameter saw blade has advantages of low cost and convenient adjustment of machine tool. In small size and batch processing, inner-diameter saw blade slicing and cutting is a common-used processing method. However, the wear of inner-diameter saw blade will seriously affect surface quality of workpiece cross section. It is necessary to monitor and evaluate the wear in real time. Based on the short-time Fourier transform, this article introduces a new method for assessing the wear of inner-diameter saw blade. By measuring and analyzing time–frequency characteristics of vibration and machining noise signals, wear is monitored in real time. The results show that it is a good method to monitor the wear of inner-diameter saw blade based on vibration of machine and machining noise signals. In addition, this method has no interference and influence on cutting work of inner-diameter saw blade, which provides a new idea for other forms of tool wear detection in engineering.

Time Frequency Analysis of Femoral Doppler Ultrasound Signals by AR Modelling

2013 ◽  
Vol 302 ◽  
pp. 319-325
Author(s):  
Latfaoui Mahieddine ◽  
Bereksi Reguig Fethi
Keyword(s):  
Moving Average ◽  
Frequency Resolution ◽  
Doppler Spectrum ◽  
Autoregressive Moving Average ◽  
Ultrasonic Signals ◽  
Time Frequency ◽  
Power Spectral ◽  
Doppler Signals ◽  
Short Time ◽  
The Impact

In this study, we have compared the efficiency of the short time Fourier transform (STFT) and autoregressive modelling (AR) and autoregressive moving average (ARMA) of the femoral Doppler artery ultrasonic signals, in order to determine the spectral broadening index (SBI). Our aim is to detect the impact of the two modelling approaches on sonograms and of power spectral density- frequency diagrams obtained from femoral arterial Doppler Signals. The sonograms have been then used to compare the methods in terms of their frequency resolution and effects in determining the stenosis of femoral artery. In this paper we have used generated frequency envelopes from the Doppler spectrum to determine an index showing the degree of severity of stenosis cases. This index called broadening spectral index is calculated for various real cases.

ANALISIS VISUAL PADA SAMPUL DEPAN MAJALAH DESAIN GRAFIS “CONCEPT” EDISI ULTAH PERDANA (Sebuah Kajian Semiotika)

DeKaVe ◽  
2013 ◽  
Vol 1 (2) ◽  
Author(s):  
Prayanto WH
Keyword(s):  
Graphic Design ◽  
Roland Barthes ◽  
Specific Design ◽  
Design Work ◽  
Design Elements ◽  
Semiotic Approach ◽  
Short Time ◽  
Content Information ◽  
Magazine Cover

Magazine is one of the forms of mass media that has fungsikomunikasi to convey information to mass audiences. The cover is an important element because it is through cover / cover one can guess the contents of the magazine, as well as further interested to know further information contained therein. On a magazine cover consists of drawings and writings are arranged in such a way that looks interesting and has meaning Press publications, especially magazines, today's not enough just to rely on the quality of news or manuscript, although verbal aspect is very important. It must be recognized that the visual aspects (design) as the cover / envelope has crucial role to capture the prospective reader. For the cover of a magazine is a window that shows the content information, can be either a text or photographs, illustrations, and design elements. The function of a magazine cover is to attract, dazzle prospective readers, by way influence the thoughts flow in a short time. So it's no wonder much current the magazine publisher who made the cover of such a way as to attract the attention of prospective readers. Thus the task of designers to magazine cover to create designs that attract the attention of the reader becomes increasingly severe. This study tries to analyze a visual on the front cover Magazine Graphic Design 'Concept' birthday inaugural edition by using the Roland Barthes' semiotic approach. As Roland Barthes (1984), any simple "design work (magazine cover)" continue to play in management of the sign. So that will generate a message (image) specific. Design cover, usually contains the elements of the sign in the form of objects, context of the environment, people or other beings who provide meaning to objects, and text (of writing) that reinforce the meaning.Keyword: cover, magazine Concept, semiotics

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