Ultrasonic Wave Propagation in CdS Phonon Maser Structures

1973 ◽  
Vol 51 (12) ◽  
pp. 1350-1358 ◽  
Author(s):  
J. Vrba ◽  
R. R. Haering
Keyword(s):  
Wave Propagation ◽  
Ultrasonic Wave ◽  
Mode Conversion ◽  
Ultrasonic Waves ◽  
Coupling Constant ◽  
Velocity Of Sound ◽  
Angular Variation ◽  
Ultrasonic Wave Propagation ◽  
Piezoelectric Coupling ◽  
Maser Action

An analysis of phonon maser action in CdS is given which includes the complications arising from the presence of off-axis ultrasonic waves. The treatment includes the angular variation of the velocity of sound and of the piezoelectric coupling constant and takes account of mode conversion at the cavity walls. Numerical results are given for CdS maser structures.

scholarly journals High Frequency Ultrasonic Wave Propagation in  Anisotropic Materials

2021 ◽  
Author(s):  
◽  
Andrew Paul Dawson
Keyword(s):  
Wave Propagation ◽  
Ultrasonic Wave ◽  
High Frequency ◽  
Guided Wave ◽  
Ultrasonic Waves ◽  
Tissue Characterisation ◽  
Ultrasonic Wave Propagation ◽  
Matching Layer ◽  
Fibrous Tissues ◽  
Wave Modes

<p>The influence of highly regular, anisotropic, microstructured materials on high frequency ultrasonic wave propagation was investigated in this work. Microstructure, often only treated as a source of scattering, significantly influences high frequency ultrasonic waves, resulting in unexpected guided wave modes. Tissues, such as skin or muscle, are treated as homogeneous by current medical ultrasound systems, but actually consist of highly anisotropic micron-sized fibres. As these systems increase towards 100 MHz, these fibres will significantly influence propagating waves leading to guided wave modes. The effect of these modes on image quality must be considered. However, before studies can be undertaken on fibrous tissues, wave propagation in more ideal structures must be first understood. After the construction of a suitable high frequency ultrasound experimental system, finite element modelling and experimental characterisation of high frequency (20-200 MHz) ultrasonic waves in ideal, collinear, nanostructured alumina was carried out. These results revealed interesting waveguiding phenomena, and also identified the potential and significant advantages of using a microstructured material as an alternative acoustic matching layer in ultrasonic transducer design. Tailorable acoustic impedances were achieved from 4-17 MRayl, covering the impedance range of 7-12 MRayl most commonly required by transducer matching layers. Attenuation coefficients as low as 3.5 dBmm-1 were measured at 100 MHz, which is excellent when compared with 500 dBmm-1 that was measured for a state of the art loaded epoxy matching layer at the same frequency. Reception of ultrasound without the restriction of critical angles was also achieved, and no dispersion was observed in these structures (unlike current matching layers) until at least 200 MHz. In addition, to make a significant step forward towards high frequency tissue characterisation, novel microstructured poly(vinyl alcohol) tissue-mimicking phantoms were also developed. These phantoms possessed acoustic and microstructural properties representative of fibrous tissues, much more realistic than currently used homogeneous phantoms. The attenuation coefficient measured along the direction of PVA alignment in an example phantom was 8 dBmm-1 at 30 MHz, in excellent agreement with healthy human myocardium. This method will allow the fabrication of more realistic and repeatable phantoms for future high frequency tissue characterisation studies.</p>

Probabilistic characterization of ultrasonic wave propagation in wood poles

2012 ◽  
Vol 39 (4) ◽  
pp. 484-493 ◽  
Author(s):  
Fernando Tallavo ◽  
Mahesh D. Pandey ◽  
Giovanni Cascante
Keyword(s):  
Wave Propagation ◽  
Ultrasonic Wave ◽  
Cross Section ◽  
Wave Velocity ◽  
Orthotropic Material ◽  
Ultrasonic Waves ◽  
Reference Wave ◽  
Ultrasonic Wave Propagation ◽  
Probabilistic Characterization

Wood poles are widely used in North America to support power electric transmission and distribution lines. Wood poles are continuously exposed to wide ranging temperature and moisture conditions, making them vulnerable to internal decay and rotting. The resulting loss of strength makes the poles vulnerable to failure under adverse weather conditions, such as wind and snow storms. These failures can result in forced outages and customer disruptions with significant economic losses. Ultrasonic testing is a non-destructive method that has been used for detection of internal deterioration of in-service wood poles, which is based on the comparison of the measured wave velocity with a reference wave velocity associated with sound wood. The current ultrasonic methods assume that the reference wave velocity for a given wood species is constant in a pole cross section. This approach is simplistic because wood is an orthotropic material with highly variable material properties. This paper presents a method for probabilistic characterization of ultrasonic wave propagation in wood poles considering wood as an orthotropic material. A better understanding and characterization of ultrasonic wave propagation in a pole cross section will contribute to improve the condition assessment of in-service wood poles based on ultrasonic tests. As an example, P-wave velocity, surface waves, frequency response function, and magnitude spectrum area are used to characterize the propagation of ultrasonic waves at a cross section of a Douglas-fir pole of 25 cm diameter.

scholarly journals Artificial Intelligence-Based Bolt Loosening Diagnosis Using Deep Learning Algorithms for Laser Ultrasonic Wave Propagation Data

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5329
Author(s):  
Dai Quoc Tran ◽  
Ju-Won Kim ◽  
Kassahun Demissie Tola ◽  
Wonkyu Kim ◽  
Seunghee Park
Keyword(s):  
Neural Network ◽  
Signal Processing ◽  
Wave Propagation ◽  
Deep Learning ◽  
Ultrasonic Wave ◽  
Ultrasonic Waves ◽  
Support Vector ◽  
Laser Ultrasonic ◽  
Data Set ◽  
Ultrasonic Wave Propagation

The application of deep learning (DL) algorithms to non-destructive evaluation (NDE) is now becoming one of the most attractive topics in this field. As a contribution to such research, this study aims to investigate the application of DL algorithms for detecting and estimating the looseness in bolted joints using a laser ultrasonic technique. This research was conducted based on a hypothesis regarding the relationship between the true contact area of the bolt head-plate and the guided wave energy lost while the ultrasonic waves pass through it. First, a Q-switched Nd:YAG pulsed laser and an acoustic emission sensor were used as exciting and sensing ultrasonic signals, respectively. Then, a 3D full-field ultrasonic data set was created using an ultrasonic wave propagation imaging (UWPI) process, after which several signal processing techniques were applied to generate the processed data. By using a deep convolutional neural network (DCNN) with a VGG-like architecture based regression model, the estimated error was calculated to compare the performance of a DCNN on different processed data set. The proposed approach was also compared with a K-nearest neighbor, support vector regression, and deep artificial neural network for regression to demonstrate its robustness. Consequently, it was found that the proposed approach shows potential for the incorporation of laser-generated ultrasound and DL algorithms. In addition, the signal processing technique has been shown to have an important impact on the DL performance for automatic looseness estimation.

scholarly journals Out-Of-Plane Permeability Evaluation of Carbon Fiber Preforms by Ultrasonic Wave Propagation

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2684 ◽  
Author(s):  
Francesca Lionetto ◽  
Francesco Montagna ◽  
Alfonso Maffezzoli
Keyword(s):  
Wave Propagation ◽  
Carbon Fiber ◽  
Ultrasonic Wave ◽  
Ultrasonic Transducer ◽  
Gravimetric Method ◽  
Ultrasonic Waves ◽  
Ultrasonic Wave Propagation ◽  
Out Of Plane ◽  
Set Up ◽  
Fiber Preforms

Out-of-plane permeability of reinforcement preforms is of crucial importance in the infusion of large and thick composite panels, but so far, there are no standard experimental methods for its determination. In this work, an experimental set-up for the measurement of unsaturated through thickness permeability based on the ultrasonic wave propagation in pulse echo mode is presented. A single ultrasonic transducer, working both as emitter and receiver of ultrasonic waves, was used to monitor the through thickness flow front during a vacuum assisted resin infusion experiment. The set-up was tested on three thick carbon fiber preforms, obtained by stacking thermal bonding of balanced or unidirectional plies either by automated fiber placement either by hand lay-up of unidirectional plies. The ultrasonic data were used to calculate unsaturated out-of-plane permeability using Darcy’s law. The permeability results were compared with saturated out-of-plane permeability, determined by a traditional gravimetric method, and validated by some analytical models. The results demonstrated the feasibility and potential of the proposed set-up for permeability measurements thanks to its noninvasive character and the one-side access.

THREE-DIMENSIONAL TIME DOMAIN MODELING OF ULTRASONIC WAVE PROPAGATION IN CONCRETE IN EXPLICIT CONSIDERATION OF AGGREGATES AND POROSITY

2001 ◽  
Vol 09 (04) ◽  
pp. 1543-1560 ◽  
Author(s):  
FRANK SCHUBERT ◽  
BERND KOEHLER
Keyword(s):  
Wave Propagation ◽  
Ultrasonic Wave ◽  
Time Domain ◽  
Energy Transport ◽  
Mode Conversion ◽  
Imaging Techniques ◽  
Three Dimensional ◽  
Complex Mixture ◽  
Domain Modeling ◽  
Ultrasonic Wave Propagation

Concrete as strongly heterogeneous and highly-packed composite material represents a very important but also very difficult object for ultrasonic nondestructive testing (NDT). Due to the high scatterer density, ultrasonic wave propagation in this material consists of a complex mixture of multiple scattering, mode conversion and diffusive energy transport. In order to obtain a better understanding of the effect of aggregates and porosity on elastic wave propagation in concrete and to optimize imaging techniques, e.g. synthetic aperture focusing technique (SAFT),1 it is useful to model the wave propagation and scattering process explicitly in the time domain. In this paper, the three-dimensional EFIT-Code (EFIT: Elastodynamic Finite Integration Technique)2 with periodic boundary conditions is used to model attenuation and dispersion of a plane longitudinal wave propagating in a synthetic three-dimensional concrete plate. Systematic parameter studies are carried out in order to demonstrate the effect of porosity and that of different aggregates. Finally, the simulation results are compared with former plane strain simulations, revealing significant differences in attenuation and signal-to-noise ratio between the two-dimensional and the more realistic three-dimensional case.

Concrete Damage Assessment by Coda Waves: Wave propagation simulations to support experimental investigations

2020 ◽  
Author(s):  
Leslie Anne Saydak ◽  
Erik H. Saenger
Keyword(s):  
Wave Propagation ◽  
Ultrasonic Wave ◽  
Mode Conversion ◽  
Concrete Structures ◽  
Complex Mixture ◽  
Coda Wave ◽  
Staggered Grid ◽  
Experimental Investigations ◽  
Ultrasonic Wave Propagation ◽  
Coda Wave Interferometry

&lt;p&gt;&lt;span&gt;Concrete is a strongly heterogeneous and densely packed composite material. Due to the high density of scattering constituents and inclusions, ultrasonic wave propagation in this material consists of a complex mixture of multiple scattering, mode conversion and diffusive energy transport. For a better understanding of the effect of aggregates, porosity and of crack distribution on elastic wave propagation in concrete and to optimize inverse techniques it is useful to simulate the wave propagation and scattering process explicitly in the time domain. For this purpose, we use the rotated staggered grid (RSG) finite-difference technique for solving the wave equations for elastic, anisotropic and/or viscoelastic media. This study is part of the CoDA project (DFG project 398216472, FOR 2825), which aims to develop a novel method based on ultrasonic coda wave interferometry (CWI) for the assessment of safety and durability of reinforced concrete structures. For this purpose, the coda technique is a suitable method to detect small changes in concrete members. In order to distinguish changes in the coda signal in terms of their origin (i.e. mechanical load, temperature, moisture), wave propagation simulations are performed to support the experimental investigations within the project. The idea is to create realistic digital twins for the experiments on two different scales: The specimen scale and the structural scale. In this study, high-performance simulations of ultrasonic wave propagation within concrete structures on the specimen scale were performed and evaluated using coda wave interferometry (CWI).&lt;/span&gt;&lt;/p&gt;

scholarly journals High Frequency Ultrasonic Wave Propagation in  Anisotropic Materials

2021 ◽  
Author(s):  
◽  
Andrew Paul Dawson
Keyword(s):  
Wave Propagation ◽  
Ultrasonic Wave ◽  
High Frequency ◽  
Guided Wave ◽  
Ultrasonic Waves ◽  
Tissue Characterisation ◽  
Ultrasonic Wave Propagation ◽  
Matching Layer ◽  
Fibrous Tissues ◽  
Wave Modes

<p>The influence of highly regular, anisotropic, microstructured materials on high frequency ultrasonic wave propagation was investigated in this work. Microstructure, often only treated as a source of scattering, significantly influences high frequency ultrasonic waves, resulting in unexpected guided wave modes. Tissues, such as skin or muscle, are treated as homogeneous by current medical ultrasound systems, but actually consist of highly anisotropic micron-sized fibres. As these systems increase towards 100 MHz, these fibres will significantly influence propagating waves leading to guided wave modes. The effect of these modes on image quality must be considered. However, before studies can be undertaken on fibrous tissues, wave propagation in more ideal structures must be first understood. After the construction of a suitable high frequency ultrasound experimental system, finite element modelling and experimental characterisation of high frequency (20-200 MHz) ultrasonic waves in ideal, collinear, nanostructured alumina was carried out. These results revealed interesting waveguiding phenomena, and also identified the potential and significant advantages of using a microstructured material as an alternative acoustic matching layer in ultrasonic transducer design. Tailorable acoustic impedances were achieved from 4-17 MRayl, covering the impedance range of 7-12 MRayl most commonly required by transducer matching layers. Attenuation coefficients as low as 3.5 dBmm-1 were measured at 100 MHz, which is excellent when compared with 500 dBmm-1 that was measured for a state of the art loaded epoxy matching layer at the same frequency. Reception of ultrasound without the restriction of critical angles was also achieved, and no dispersion was observed in these structures (unlike current matching layers) until at least 200 MHz. In addition, to make a significant step forward towards high frequency tissue characterisation, novel microstructured poly(vinyl alcohol) tissue-mimicking phantoms were also developed. These phantoms possessed acoustic and microstructural properties representative of fibrous tissues, much more realistic than currently used homogeneous phantoms. The attenuation coefficient measured along the direction of PVA alignment in an example phantom was 8 dBmm-1 at 30 MHz, in excellent agreement with healthy human myocardium. This method will allow the fabrication of more realistic and repeatable phantoms for future high frequency tissue characterisation studies.</p>

Simulation study of axial ultrasonic wave propagation in heterogeneous bovine cortical bone

2016 ◽  
Vol 140 (5) ◽  
pp. 3710-3717 ◽  
Author(s):  
Toshiho Hata ◽  
Yoshiki Nagatani ◽  
Koki Takano ◽  
Mami Matsukawa
Keyword(s):  
Wave Propagation ◽  
Cortical Bone ◽  
Ultrasonic Wave ◽  
Simulation Study ◽  
Ultrasonic Wave Propagation

Mathematical Formulation of the Global Coefficients of Transmission and Reflection of Ultrasonic Waves in Bi-Phase Porous Medium

2015 ◽  
Vol 1101 ◽  
pp. 471-479
Author(s):  
Georges Freiha ◽  
Hiba Othman ◽  
Michel Owayjan
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Wave Propagation ◽  
Mathematical Formulation ◽  
Ultrasonic Waves ◽  
Ultrasonic Wave Propagation ◽  
Local Coefficients ◽  
Important Field ◽  
New Formulation ◽  
Transmission And Reflection

The study of signals propagation inside porous media is an important field especially in the biomedical research related to compact bones. The purpose of this paper is to determine a mathematical formulation of the global coefficients of transmission and reflection of nondestructive ultrasonic waves in any bi-phase porous medium. Local coefficients of transmission and reflection on the interface of the porous medium will be determined based on a study of boundary conditions. The behavior of different waves inside the porous medium will be developed so that we can derive a new formulation of global coefficients that takes interior phenomena into consideration. Results are found independently of the geometrical and physical characteristics of the medium. Note that this study is based on normal incident ultrasonic wave propagation.

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