Method for acquiring time of flight from high aliasing signal in heat exchange fouling ultrasonic testing

2021 ◽  
pp. 014233122198911
Author(s):  
Xia Li ◽  
Lingfang Sun ◽  
Jing Li ◽  
Heng Piao
Keyword(s):  
Heat Exchange ◽  
Ultrasonic Testing ◽  
Reference Signal ◽  
Time Of Flight ◽  
High Order ◽  
Spectrum Estimation ◽  
Time Domain Signal ◽  
Iterative Correction ◽  
Testing Signal ◽  
The Time Domain

In heat exchange fouling ultrasonic testing, the time-domain signal waveform often contains high aliasing due to small fouling thickness or high order echo interference, and so forth. This paper studies the method of acquiring time of flight from heat exchange fouling ultrasonic testing signal with high aliasing and presents the method that combined the Wiener deconvolution and high order cumulative spectrum estimation. For reference signal distortion problem, which may exist in real application, an iterative correction process is introduced in the form of Incremental Wiener algorithm. Simulation and experimental results show that the proposed method has better anti-noise ability, better time of flight accuracy and practicability.

scholarly journals Reconstruction algorithm for tunneling ionization with a perturbation for the time-domain observation of an electric-field

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wosik Cho ◽  
Jeong-uk Shin ◽  
Kyung Taec Kim
Keyword(s):  
Laser Pulse ◽  
Electric Field ◽  
Time Domain ◽  
Reconstruction Algorithm ◽  
High Order ◽  
Reconstruction Process ◽  
Tunneling Ionization ◽  
Order Contribution ◽  
High Order Contribution ◽  
The Time Domain

AbstractWe present a reconstruction algorithm developed for the temporal characterization method called tunneling ionization with a perturbation for the time-domain observation of an electric field (TIPTOE). The reconstruction algorithm considers the high-order contribution of an additional laser pulse to ionization, enabling the use of an intense additional laser pulse. Therefore, the signal-to-noise ratio of the TIPTOE measurement is improved by at least one order of magnitude compared to the first-order approximation. In addition, the high-order contribution provides additional information regarding the pulse envelope. The reconstruction algorithm was tested with ionization yields obtained by solving the time-dependent Schrödinger equation. The optimal conditions for accurate reconstruction were analyzed. The reconstruction algorithm was also tested using experimental data obtained using few-cycle laser pulses. The reconstructed pulses obtained under different dispersion conditions exhibited good consistency. These results confirm the validity and accuracy of the reconstruction process.

scholarly journals Oscillator-based High-order Harmonic Generation at 4MHz for Applications in Time-of-Flight Photoemission Spectroscopy

2013 ◽  
Vol 41 ◽  
pp. 01019 ◽  
Author(s):  
Cheng-Tien Chiang ◽  
Alexander Blättermann ◽  
Michael Huth ◽  
Jürgen Kirschner ◽  
Wolf Widdra
Keyword(s):  
Harmonic Generation ◽  
Time Of Flight ◽  
High Order ◽  
Photoemission Spectroscopy ◽  
High Order Harmonic Generation ◽  
High Order Harmonic

scholarly journals Is the time domain signal-averaged electrocardiogram helpful in patients with ventricular tachycardia without apparent structural heart disease?

1995 ◽  
Vol 18 (10) ◽  
pp. 568-572 ◽  
Author(s):  
Yelena S. K. Orlov ◽  
Michael A. Brodsky ◽  
Michael V. Orlov ◽  
Byron J. Allen ◽  
Rex J. Winters
Keyword(s):  
Heart Disease ◽  
Ventricular Tachycardia ◽  
Time Domain ◽  
Structural Heart Disease ◽  
Time Domain Signal ◽  
The Time Domain

scholarly journals NMR Resolution Enhancement and Homonuclear Decoupling Using Non-Uniform Weighted Sampling

2020 ◽  
Author(s):  
Chris Waudby ◽  
John Christodoulou
Keyword(s):  
Linear Prediction ◽  
Resolution Enhancement ◽  
Simple Method ◽  
Uniform Sampling ◽  
Homonuclear Decoupling ◽  
Time Domain Signal ◽  
Window Functions ◽  
Uniform Noise ◽  
Increased Sensitivity ◽  
The Time Domain

Non-uniform weighted sampling (NUWS) is a simple method for multi-dimensional NMR spectroscopy in which window functions are applied during acquisition by sampling varying numbers of scans across indirect dimensions. While NUWS was previously shown to provide modest increases in sensitivity, here we describe a complementary application to enhance spectral resolution by increasing the sampling of later points of the time domain signal. Moreover, by combining NUWS with carefully constructed apodization functions signal envelopes can be modulated in an arbitrary manner while retaining a uniform noise level, permitting further signal manipulations such as linear prediction and non-uniform sampling (NUS). We leverage this to develop a combined NUWS-NUS scheme for broadband homonuclear decoupling, with substantially increased sensitivity in comparison to constant time experiments.

Fault Diagnosis of Motor Rotor Based on Fuzzy C-Means Clustering Analysis

2013 ◽  
Vol 273 ◽  
pp. 409-413 ◽  
Author(s):  
Yu Xiang Cao ◽  
Xue Jun Li ◽  
Ling Li Jiang
Keyword(s):  
Time Domain ◽  
Clustering Analysis ◽  
Statistical Features ◽  
Fuzzy C Means ◽  
Time Domain Signal ◽  
Fuzzy C Means Clustering ◽  
Important Means ◽  
Fault Diagnostic ◽  
Characteristic Features ◽  
The Time Domain

For the fuzziness of the fault symptoms in motor rotor, this paper proposes a fault diagnostic method which based on the time-domain statistical features and the fuzzy c-means clustering analysis (FCM). This method is to extract the characteristic features of time-domain signal via time-domain statistics and to import the extracted characteristic vector to classifier. And then the fuzzy c-means realizes the classification by confirming the distance among samples, which is based on the degree of membership between the sample and the clustering center. The fault diagnostic cases of motor rotor show that the method which bases on the time-domain statistical features-FCM can detect the rotor fault effectively and distinguish the different types of fault correctly. Therefore, it can be used as an important means of rotor fault identification.

scholarly journals Ultrawideband Impulse Radar Through-the-Wall Imaging with Compressive Sensing

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Wenji Zhang ◽  
Moeness G. Amin ◽  
Fauzia Ahmad ◽  
Ahmad Hoorfar ◽  
Graeme E. Smith
Keyword(s):  
Compressive Sensing ◽  
Time Domain ◽  
Measurement Data ◽  
Acquisition Time ◽  
Time Domain Signal ◽  
Spatially Extended ◽  
Data Volume ◽  
Order Of Magnitude ◽  
New Perspective ◽  
The Time Domain

Compressive Sensing (CS) provides a new perspective for addressing radar applications requiring large amount of measurements and long data acquisition time; both issues are inherent in through-the-wall radar imaging (TWRI). Most CS techniques applied to TWRI consider stepped-frequency radar platforms. In this paper, the impulse radar two-dimensional (2D) TWRI problem is cast within the framework of CS and solved by the sparse constraint optimization performed on time-domain samples. Instead of the direct sampling of the time domain signal at the Nyquist rate, the Random Modulation Preintegration architecture is employed for the CS projection measurement, which significantly reduces the amount of measurement data for TWRI. Numerical results for point-like and spatially extended targets show that high-quality reliable TWRI based on the CS imaging approach can be achieved with a number of data points with an order of magnitude less than that required by conventional beamforming using the entire data volume.

Exact Interpolation of Fourier Transform Spectra

1983 ◽  
Vol 37 (2) ◽  
pp. 153-166 ◽  
Author(s):  
Carlo Giancaspro ◽  
Melvin B. Comisarow
Keyword(s):  
Fourier Transform ◽  
Graphical Form ◽  
Acquisition Time ◽  
Time Domain Signal ◽  
Parabolic Interpolation ◽  
Interpolation Procedure ◽  
True Frequency ◽  
Fourier Transform Spectra ◽  
The Time Domain ◽  
Absorption Mode

A systematic study of interpolation of Fourier transform (FT) spectra is reported. Interpolation errors are examined for both frequency determination and intensity determination for different interpolation procedures for both absorption mode and magnitude mode FT spectra. The errors are presented in both analytical and graphical form as functions of the number of zero-fillings and ( T/τ), the ratio of the acquisition time to the relaxation time of the time domain signal. For interpolation of absorption mode spectra, parabolic interpolation is superior to Lorentzian interpolation if T/τ < 2. For T/τ > 2, Lorentzian interpolation is superior. For small values of T/τ, both parabolic interpolation and Lorentzian interpolation of the absorption line shape give greater errors than no interpolation. For interpolation of the magnitude lineshape, interpolation with the “magnitude-Lorentzian” function gives the exact frequency of the continuous spectrum. This interpolation procedure permits exact determination of the true frequency and true intensity for both absorption mode and magnitude mode FT spectra.

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