Guided waves on a dielectric-coated cylinder immersed in a plasma

1965 ◽  
Vol 1 (1) ◽  
pp. 19 ◽  
Author(s):  
S.R. Seshadri
Keyword(s):  
Guided Waves ◽  
Coated Cylinder

Recent progress in computing guided waves dispersion curves

2007 ◽  
Author(s):  
Mihai V. Predoi ◽  
Michel Castaings ◽  
Bernard Hosten ◽  
Christophe Bacon
Keyword(s):  
Recent Progress ◽  
Guided Waves ◽  
Dispersion Curves

FAULT-ZONE EXPLORATION IN HIGHLY URBANIZED SETTINGS USING GUIDED WAVES: AN EXAMPLE FROM THE RAYMOND FAULT, LOS ANGELES, CALIFORNIA

2017 ◽  
Author(s):  
R.D. Catchings ◽  
◽  
Janis L. Hernandez ◽  
Robert R. Sickler ◽  
M.R. Goldman ◽  
...  
Keyword(s):  
Los Angeles ◽  
Fault Zone ◽  
Guided Waves

LOCATING 1906 SAN FRANCISCO EARTHQUAKE SURFACE FAULT RUPTURES USING PGV OF GUIDED WAVES

2020 ◽  
Author(s):  
Rufus Catchings ◽  
◽  
M.J. Rymer ◽  
M.R. Goldman
Keyword(s):  
San Francisco ◽  
Guided Waves

ULTRASONIC GUIDED WAVES FOR THE INSPECTION OF ADHESIVELY BONDED JOINTS

2008 ◽  
Author(s):  
Padma Kumar Puthillath ◽  
Fei Yan ◽  
Clifford J. Lissenden ◽  
Joseph L. Rose ◽  
Donald O. Thompson ◽  
...  
Keyword(s):  
Guided Waves ◽  
Ultrasonic Guided Waves ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Adhesively Bonded Joints

scholarly journals Estimation of the Filling Distribution and Height Levels Inside an Insulated Pressure Vessel by Guided Elastic Wave Attenuation Tomography

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 179
Author(s):  
Robert Neubeck ◽  
Mareike Stephan ◽  
Tobias Gaul ◽  
Bianca Weihnacht ◽  
Lars Schubert ◽  
...  
Keyword(s):  
Guided Waves ◽  
Oil And Gas ◽  
Wave Attenuation ◽  
Oil And Gas Industry ◽  
Pressure Vessels ◽  
Prototype System ◽  
Gas Industry ◽  
Distributed Sensor ◽  
Conversion Rates ◽  
Scale Experiment

The operation efficiency and safety of pressure vessels in the oil and gas industry profits from an accurate knowledge about the inner filling distribution. However, an accurate and reliable estimation of the multi-phase height levels in such objects is a challenging task, especially when considering the high demands in practicability, robustness in harsh environments and safety regulations. Most common systems rely on impractical instrumentation, lack the ability to measure solid phases or require additional safety precautions due to their working principle. In this work, another possibility to determine height levels by attenuation tomography with guided elastic waves is proposed. The method uses a complete instrumentation on the outer vessel shell and is based on the energy conversion rates along the travel path of the guided waves. Noisy data and multiple measurements from sparsely distributed sensor networks are translated into filling levels with accuracies in the centimeter range by solving a constrained optimization problem. It was possible to simultaneously determine sand, water, and oil phases on a mock-up scale experiment, even for artificially created sand slopes. The accuracy was validated by artificial benchmarking for a horizontal vessel, giving references for constructing an affordable prototype system.

scholarly journals Strain Sensitivity Enhancement of Broadband Ultrasonic Signals in Plates Using Spectral Phase Filtering

2021 ◽  
Vol 11 (6) ◽  
pp. 2582
Author(s):  
Lucas M. Martinho ◽  
Alan C. Kubrusly ◽  
Nicolás Pérez ◽  
Jean Pierre von der Weid
Keyword(s):  
Fourier Transform ◽  
Guided Waves ◽  
Strain Level ◽  
Energy Concentration ◽  
Short Time Fourier Transform ◽  
Time Frequency ◽  
Frequency Representation ◽  
The Fourier Transform ◽  
Short Time ◽  
Sensitivity Gain

The focused signal obtained by the time-reversal or the cross-correlation techniques of ultrasonic guided waves in plates changes when the medium is subject to strain, which can be used to monitor the medium strain level. In this paper, the sensitivity to strain of cross-correlated signals is enhanced by a post-processing filtering procedure aiming to preserve only strain-sensitive spectrum components. Two different strategies were adopted, based on the phase of either the Fourier transform or the short-time Fourier transform. Both use prior knowledge of the system impulse response at some strain level. The technique was evaluated in an aluminum plate, effectively providing up to twice higher sensitivity to strain. The sensitivity increase depends on a phase threshold parameter used in the filtering process. Its performance was assessed based on the sensitivity gain, the loss of energy concentration capability, and the value of the foreknown strain. Signals synthesized with the time–frequency representation, through the short-time Fourier transform, provided a better tradeoff between sensitivity gain and loss of energy concentration.

Stress evaluation in seven-wire strands based on singular value feature of ultrasonic guided waves

2021 ◽  
pp. 147592172110053
Author(s):  
Qian Ji ◽  
Li Jian-Bin ◽  
Liu Fan-Rui ◽  
Zhou Jian-Ting ◽  
Wang Xu
Keyword(s):  
Dispersion Curve ◽  
Support Vector Regression ◽  
Stress Level ◽  
Guided Waves ◽  
Guided Wave ◽  
Singular Value ◽  
Support Vector ◽  
Support Vector Regression Model ◽  
Various Boundary Conditions ◽  
Wave Methods

The seven-wire strands are the crucial components of prestressed structures, though their performance inevitably degrades with the passage of time. The ultrasonic guided wave methods have been intensely studied, owing to its tremendous potential for full-scale applications, among the existing nondestructive testing methods, for evaluating the stress status of strands. We have employed the theoretical and finite element methods to solve the dispersion curve of single wire and steel strands under various boundary conditions. Thereafter, the singular value decomposition was adopted to work with the simulated and experimental signals for extracting a feature vector that carries valuable stress status information. The effectiveness of the vector was verified by analyzing the relationship between the vector and the stress level. The vector was also used as an input to establish a support vector regression model. The accuracy of the model has been discussed for different sample sizes. The results show that the fundamental mode dispersion curve offset on the high-frequency part and cut-off frequency increases as the boundary constraints enhance. Simulated and experimental results have demonstrated the effectiveness and potential of the proposed support vector regression method for evaluating the stress level in the strands. This method performs well even at low stress levels and the reliability can be enhanced by adding more samples.

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