Multi-defect detection based on ultrasonic Lamb wave sign phase coherence factor imaging method

The ultrasonic Lamb wave total focusing method (TFM) only uses the amplitude of the defective scattered signal for virtual focused imaging, while ignoring the phase information of the scattered signal and the dispersion characteristics of the Lamb wave, resulting in low imaging resolution and easily produced artefacts in imaging. To solve this problem, an ultrasonic Lamb wave imaging method based on phase coherence is proposed in this paper and the sign coherence factor (SCF) in the full matrix scattering signal is extracted. Moreover, the method uses the SCF to weight the amplitude of the full matrix scattering signal, suppresses the side lobes of the defect echo signal and the Lamb wave dispersion effect, improves the ultrasonic Lamb wave imaging resolution and weakens the artefacts. Finally, single- and multiplehole defects in aluminium plates are detected for experimental validation using an ultrasonic phased array. The array performance indicator and signal-to-noise ratio are used as indicators for quantitative assessment of imaging performance. The results show that compared with the TFM imaging, the SCF imaging can effectively suppress the noise and scattered signal side lobes, improve the array performance indicator (API) by 69.1% and improve the signal-to-noise ratio (SNR) by 73.9%. In addition, the SCF imaging can effectively weaken the interference of scattered signals between multiple through-hole defects, resulting in fewer artefacts in imaging.

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Demonstration of improvement in the signal-to-noise ratio of Thomson scattering signal obtained by using a multi-pass optical cavity on the Tokyo Spherical Tokamak-2

Review of Scientific Instruments ◽

10.1063/1.4891707 ◽

2014 ◽

Vol 85 (11) ◽

pp. 11D846 ◽

Cited By ~ 1

Author(s):

H. Togashi ◽

A. Ejiri ◽

J. Hiratsuka ◽

K. Nakamura ◽

Y. Takase ◽

...

Keyword(s):

Signal To Noise Ratio ◽

Optical Cavity ◽

Thomson Scattering ◽

Spherical Tokamak ◽

Signal To Noise ◽

Noise Ratio ◽

Scattering Signal

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Multiplane wave imaging increases signal-to-noise ratio in ultrafast ultrasound imaging

Physics in Medicine and Biology ◽

10.1088/0031-9155/60/21/8549 ◽

2015 ◽

Vol 60 (21) ◽

pp. 8549-8566 ◽

Cited By ~ 40

Author(s):

Elodie Tiran ◽

Thomas Deffieux ◽

Mafalda Correia ◽

David Maresca ◽

Bruno-Felix Osmanski ◽

...

Keyword(s):

Ultrasound Imaging ◽

Signal To Noise Ratio ◽

Signal To Noise ◽

Wave Imaging ◽

Noise Ratio

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Three-Dimensional Microwave Holographic Imaging Employing Forward-Scattered Waves Only

International Journal of Antennas and Propagation ◽

10.1155/2013/897287 ◽

2013 ◽

Vol 2013 ◽

pp. 1-15 ◽

Cited By ~ 18

Author(s):

Reza K. Amineh ◽

Maryam Ravan ◽

Justin McCombe ◽

Natalia K. Nikolova

Keyword(s):

Signal To Noise Ratio ◽

Three Dimensional ◽

Imaging Method ◽

Two Dimensional ◽

Signal To Noise ◽

High Loss ◽

Holographic Imaging ◽

Multiple Receivers ◽

Satisfactory Performance ◽

Resolution Limits

We propose a three-dimensional microwave holographic imaging method based on the forward-scattered waves only. In the proposed method, one transmitter and multiple receivers perform together a two-dimensional scan on two planar apertures on opposite sides of the inspected domain. The ability to achieve three-dimensional imaging without back-scattered waves enables the imaging of high-loss objects, for example, tissues, where the back-scattered waves may not be available due to low signal-to-noise ratio or nonreciprocal measurement setup. The simulation and experimental results demonstrate the satisfactory performance of the proposed method in providing three-dimensional images. Resolution limits are derived and confirmed with simulation examples.

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Low-latency time-of-flight non-line-of-sight imaging at 5 frames per second

Nature Communications ◽

10.1038/s41467-021-26721-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Ji Hyun Nam ◽

Eric Brandt ◽

Sebastian Bauer ◽

Xiaochun Liu ◽

Marco Renna ◽

...

Keyword(s):

Signal To Noise Ratio ◽

Time Of Flight ◽

Motion Blur ◽

Line Of Sight ◽

Low Latency ◽

Imaging Method ◽

Signal To Noise ◽

Array Detectors ◽

Noise Ratio ◽

Non Line Of Sight

AbstractNon-Line-Of-Sight (NLOS) imaging aims at recovering the 3D geometry of objects that are hidden from the direct line of sight. One major challenge with this technique is the weak available multibounce signal limiting scene size, capture speed, and reconstruction quality. To overcome this obstacle, we introduce a multipixel time-of-flight non-line-of-sight imaging method combining specifically designed Single Photon Avalanche Diode (SPAD) array detectors with a fast reconstruction algorithm that captures and reconstructs live low-latency videos of non-line-of-sight scenes with natural non-retroreflective objects. We develop a model of the signal-to-noise-ratio of non-line-of-sight imaging and use it to devise a method that reconstructs the scene such that signal-to-noise-ratio, motion blur, angular resolution, and depth resolution are all independent of scene depth suggesting that reconstruction of very large scenes may be possible.

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Time-Domain Topological Energy Imaging Method of Concrete Cavity Defect by Lamb Wave

Shock and Vibration ◽

10.1155/2019/6294603 ◽

2019 ◽

Vol 2019 ◽

pp. 1-13 ◽

Cited By ~ 1

Author(s):

Wen-Fa Zhu ◽

Wei Shao ◽

Le-Le Peng ◽

Guo-Peng Fan ◽

Xing-Jie Chen ◽

...

Keyword(s):

Time Domain ◽

Lamb Wave ◽

Wave Dispersion ◽

Imaging Method ◽

Sound Fields ◽

Wave Imaging ◽

Reference Medium ◽

Synthetic Aperture Focusing ◽

Synthetic Aperture Focusing Technique ◽

Defect Imaging

This paper presents an ultrasonic Lamb wave imaging method based on time-domain topological energy to address artifacts in the results of traditional ultrasound imaging methods. This method is based on topological theory and the calculation of the direct and adjoint sound fields in a defect-free reference medium. It focuses the direct and adjoint sound fields at the cavity defect using time reversal and their time-domain topological energy as the pixel values of the image to reduce the artifacts. The physical mechanism of time-domain topological energy (TDTE) imaging is revealed by finite element simulation and experiment. The feasibility of this method for multilayer concrete cavity defect imaging is verified. Compared with the traditional synthetic aperture focusing technique (SAFT) imaging method, the numerical simulation and experimental results show that the method can overcome the influence of ultrasonic Lamb wave dispersion and locate cavity defects with high accuracy and few artifacts. These features indicate the potential of the method in imaging damage concrete structures.

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On the signal-to-noise ratio of a synthetic aperture ultrasound imaging method

European Journal of Ultrasound ◽

10.1016/0929-8266(95)00160-s ◽

1996 ◽

Vol 3 (3) ◽

pp. 277-281 ◽

Cited By ~ 12

Author(s):

J. Ylitalo

Keyword(s):

Ultrasound Imaging ◽

Signal To Noise Ratio ◽

Synthetic Aperture ◽

Imaging Method ◽

Signal To Noise ◽

Noise Ratio

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FSR Systems for Detection of Air Objects Using Cosmic Radio Emissions

Sensors ◽

10.3390/s21020465 ◽

2021 ◽

Vol 21 (2) ◽

pp. 465

Author(s):

Hristo Kabakchiev ◽

Vera Behar ◽

Ivan Garvanov ◽

Dorina Kabakchieva ◽

Avgust Kabakchiev ◽

...

Keyword(s):

Signal To Noise Ratio ◽

Cosmic Radio ◽

Joint Detection ◽

Signal To Noise ◽

Theoretical Possibility ◽

Forward Scatter ◽

Direct Signal ◽

Radio Emissions ◽

Detection Characteristics ◽

Scattering Signal

The paper analyses the possibility of Forward Scatter Radar (FSR) systems to detect airplanes using cosmic emission from pulsars and planets (pulsar, Sun, Moon). A suboptimal multichannel algorithm for joint detection and evaluation of the parameters of the forward scattering signal created by an airplane (duration and velocity) is proposed, with preliminary compensation of the powerful direct signal emitted by cosmic sources (pulsar, Sun and Moon). The expressions for calculation of the Signal-to-Noise Ratio (SNR) at the input of the detector and the compensator are obtained. The detection characteristics are also obtained, and the requirements for the suppression coefficient of the compensator are evaluated. A methodology for calculating the maximum distance for detecting an aircraft using a described algorithm is proposed. The obtained results show that due to the Forward Scatter (FS) effect, there is the theoretical possibility to detect airplanes at close ranges by FSRs, which use very weak signals from cosmic sources.

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Increasing reliability of forensic analysis while research on destroyed relief marking with magneto-optical devices

Theory and Practice of Forensic Science and Criminalistics ◽

10.32353/khrife.1.2021.11 ◽

2021 ◽

Vol 23 (1) ◽

pp. 148-166

Author(s):

Yu. Agalidi ◽

O. Koshel

Keyword(s):

Optical Imaging ◽

Signal To Noise Ratio ◽

Forensic Analysis ◽

Imaging Method ◽

Signal Recognition ◽

Visualization Method ◽

Signal To Noise ◽

Instrumental Data ◽

Noise Ratio ◽

Correct Signal

While research on destroyed relief marking of metal objects using the magneto-optical method, visualization of (invisible) fields of internal stress in the VIN plate area is performed and then a forensic analysis of obtained instrumental data is carried out (indirect organoleptic observation of the visualization results); thus, forensic analysis reliability of results directly depends on sensitivity of instruments and informativeness of instrumental data. The main quantitative characteristic in this case is probability of correct signal recognition (contours of marking signs) against the background of noise (structural noise of investigated surface and the noise of the visualization method itself) determined by the signal-to-noise ratio. This article presents results of a comparative experimental assessment of signal-to-noise ratio and probability of correct signal recognition while restoringthe destroyed relief markings for two complexes of magneto-optical imaging – models of 2006 and 2018. This article purpose is a quantitative and qualitative comparative assessment of results of visualization of internal stresses in areas of completely removed relief marking of metal objects. The results of successful practical research obtained by forensic experts from different countries make it possible to assess effectiveness and prospects of using the magneto-optical imaging method. In a new modification of the magneto-optical complex: signal level is 4.35 dB higher (contrast of reconstructed marking signs); 2.71 dB lower noise level (surface relief/texture and magnetic copying noise);• probability of correct character recognition is P> 0.995 (increased by 14.9%). Technical improvements in implementation of magneto-optical visualization method made it possible to expand the range of materials for research objects(magnetic and electrically conductive materials were investigated). The high efficiency of method for restoring marking is illustrated by results of forensic examinations for materials with a low level of residual stresses (aluminum alloy, low-carbon steel) which chemical etching method did not give results for. The use of new modification allows examining the rust layer, up to cases of corrosion to the entire depth of marks. Considering non-destructive nature of magneto-optical researches, possibility of their repeated repetition without losing object properties, this method (in accordance with the order of application of types of studies) deserves more attention for application.

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