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Ultrasonics

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https://www.readbyqxmd.com/read/30408679/phononic-crystal-as-a-neutron-detector
#1
Ahmed Mehaney
A perfect phononic crystal model composed of concrete and epoxy, and another defect model of Aluminum/Concrete/Epoxy were proposed. The two models were analyzed computationally and theoretically based on the transfer matrix method. The proposed models were capable of detecting and sensing neutrons irradiations over a wide fluence range based on the effects of neutrons fluence on the Young's modulus of the concrete. The neutrons fluence significantly changed the transmission spectra of the phononic crystal models whether the neutrons-induced temperature was considered or not as the phononic band gaps and the local resonant peaks were shifted...
November 2, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30408681/ultrasound-attenuation-and-phase-velocity-of-moderately-concentrated-silica-suspensions
#2
Hayato Mori, Tomohisa Norisuye, Hideyuki Nakanishi, Qui Tran-Cong-Miyata
Ultrasound attenuation coefficient and phase velocity of moderately concentrated suspensions of charged silica particles were measured as a function of frequency. The attenuation coefficients were found to be significantly smaller than the theoretical prediction, and such a difference did not appear in the neutral particle suspensions under the corresponding concentrations. In this study, we have investigated the acoustic spectra of silica particles with different particle sizes, concentrations as well as salt concentrations...
October 31, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30408680/a-combined-linear-and-nonlinear-ultrasound-time-domain-approach-for-impact-damage-detection-in-composite-structures-using-a-constructive-nonlinear-array-technique
#3
Gian Piero Malfense Fierro, Michele Meo
Discovery and evaluation concerns of barely visible impact damage in composite materials is a well-known issue in industries using these materials. This work proposes a frequency sweep method where damage assessment is conducted with respect to the time domain. Firstly, a combined linear and nonlinear ultrasound imaging technique is proposed, which focuses on the excitation of damage/defect regions using a frequency sweep methodology from multiple transducer locations. Secondly, the method deconstructs time domain signals, which allows for the visualisation of linear and nonlinear ultrasound components independently...
October 25, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30384008/towards-quantitative-quasi-static-ultrasound-elastography-using-a-reference-layer-for-liver-imaging-application-a-preliminary-assessment
#4
Sathiyamoorthy Selladurai, Arun K Thittai
Changes in tissue elasticity are generally correlated with pathological phenomena. For example, diffuse liver disease progressively reduces the elasticity of the liver. Quasi-static elastography is popular in clinical applications to visualize regions with different relative stiffness. However, the limitation of this technique is that it provides only qualitative information. To overcome this, we investigate the use of a calibrated reference layer, sandwiched between the transducer and the tissue surface, to quantitatively image the unknown modulus of the examined tissue...
October 17, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30384005/on-the-interpretation-of-shear-viscosity-ultrasonic-measurements
#5
Mihail Gitis
This article discusses the possibility of using the measurements of ultrasonic wave parameters to estimate numerical values of shear and bulk viscosities on-line. It is noted that to increase the reliability of such estimates, it is necessary to introduce classification criteria for liquids. The on-line classification of liquids can be carried out through the measurement and comparison of the real and imaginary parts of liquid acoustic shear impedances. When the measured real and imaginary parts of the impedance are equal, the calculated ultrasonic viscosity values do not differ from the shear viscosity measured by a capillary viscometer...
October 17, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30384007/a-real-time-data-based-scan-conversion-method-for-single-element-ultrasound-transducers
#6
Gergely Csány, Klára Szalai, Miklós Gyöngy
The current work investigates the performance of a real-time scan conversion algorithm for generating a 2-D ultrasound image from a laterally scanned single-element ultrasound transducer, which has applications in point-of-care devices such as for skin imaging. The algorithm employs a fixed calibration curve to update a predefined image grid in real time. Simulations showed that the calibration curve (with a maximum of 1) is robust to changes in scatterer concentration (8.3×10-3 mean absolute error), signal to noise ratio (1...
October 16, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30384006/acoustic-manipulation-of-particles-in-a-cylindrical-cavity-theoretical-and-experimental-study-on-the-effects-of-boundary-conditions
#7
Di Xu, Feiyan Cai, Mian Chen, Fei Li, Chen Wang, Long Meng, Dehui Xu, Wei Wang, Junru Wu, Hairong Zheng
Precise manipulation of microparticles in microchannels is a primary technique for numerous lab-on-a-chip bioengineering research and applications, as it determines the chip's functions and analytical results. Acoustic manipulation, using the acoustic radiation force, is a compact, versatile and contactless manipulation technique, which can be easily integrated with other microfluidic components. It is our main purpose to report the effect of boundary condition of a cylindrical microfluidic cavity on the acoustic particles' manipulation...
October 9, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30327130/backward-waves-and-energy-fluxes-excited-in-acoustic-medium-with-an-immersed-plate
#8
E V Glushkov, N V Glushkova, O A Miakisheva
Explicit integral representations for the wave fields generated by air-coupled or underwater transducers in an acoustic medium with a submerged elastic (metallic or laminate composite) plate are obtained in the form of path Fourier integrals. Together with the far-field asymptotics for the incident, reflected, transmitted and guided waves that were derived from those integrals, they proved to be a convenient tool for the in-depth study of wave phenomena inherent in such acoustic-elastic structures. The present paper is focused on the non-conventional properties of backward leaky waves such as the increased wave energy transfer through the plate due to the increasing occurrence of energy vortices impeding lateral outflow of wave energy...
October 4, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30322641/a-pdms-based-broadband-acoustic-impedance-matched-material-for-underwater-applications
#9
R-M Guillermic, M Lanoy, A Strybulevych, J H Page
Having a material that is matched in acoustic impedance with the surrounding medium is a considerable asset for many underwater acoustic applications. In this work, impedance matching is achieved by dispersing small, deeply subwavelength sized particles in a soft matrix, and the appropriate concentration is determined with the help of Coherent Potential Approximation and Waterman & Truell models. We show experimentally the validity of the models using mixtures of Polydimethylsiloxane (PDMS) and TiO2 particles...
October 3, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30293690/the-effect-of-the-conductivity-of-a-film-located-near-a-piezoelectric-resonator-with-a-lateral-electric-field-based-on-the-pzt-ceramics-on-its-characteristics
#10
B D Zaitsev, A P Semyonov, A A Teplykh, I A Borodina
In this paper, we investigated theoretically and experimentally the effect of the conductivity of the film located in the immediate vicinity of the free side of a piezoelectric resonator based on the PZT ceramics on its characteristics. It is shown that with increasing the conductivity of the film at first the parallel resonant frequency does not change, then it decreases in a certain interval and after that remains practically constant. With increasing the width of the gap between the film and the resonator, the resonant frequency increases and reaches the saturation...
October 1, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30301551/structures-and-dynamics-of-carbon-black-in-suspension-probed-by-static-and-dynamic-ultrasound-scattering-techniques
#11
Motoki Ozaki, Tomohisa Norisuye, Hideyuki Nakanishi, Qui Tran-Cong-Miyata
Carbon black (CB) suspension exhibits various structures depending on the properties of solvent and dispersant as well as the preparation process of suspension. In most cases, CB particles do not exist as independent nanoparticles but as aggregates or agglomerates. In order to evaluate the size distribution at different level of hierarchal structure, we carried out static/dynamic ultrasound scattering analysis for the CB suspensions in alcohol and/or water with or without Nafion, a perfluorinated polymer. The potential of the dynamic ultrasound scattering technique was demonstrated by discriminating diffusing nanoparticles and micron-sized aggregates/agglomerates without dilution of the sample...
September 29, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30293691/signal-noise-based-transfer-function-approach-for-reliability-estimation-of-ultrasonic-inspection
#12
Mohamed Subair Syed Akbar Ali, Anish Kumar, Prabhu Rajagopal
In recent years several methods for reducing the burden of experimentation for obtaining Probability of Detection (PoD) curves have been proposed, especially involving the use of numerical simulation. In particular, there is much interest in being able to estimate the PoD capabilities of a given NDE method, target embodiment and material, provided this is known for some canonical material for the same combination of method/embodiment. Ultrasonic experiments on materials with low signal to noise ratio (SNR) are often difficult and time consuming since the higher signal noise causes serious complications...
September 29, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30385046/synthetic-transmit-aperture-beamforming-for-sound-velocity-estimation-using-channel-domain-differential-phase-gradient-a-phantom-study
#13
Che-Chou Shen, Sheng-Hsuan Hsiao, Yen-Chung Lin
In medical ultrasound imaging system, degradation of image quality occurs due to mismatch between beamforming sound velocity and propagating sound velocity in tissue. Channel-domain differential phase gradient has been previously utilized to optimize the beamforming sound velocity but its efficacy is limited to transmit focal depth. Specifically, low spatial coherence of channel signal in the non-focal region could lead to over-estimation of beamforming sound velocity. In order to alleviate the estimation bias of beamforming sound velocity, synthetic transmit aperture beamforming is proposed in this study to maintain the spatial coherence of channel data over the entire imaging depth...
September 27, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30290958/evaluation-of-the-thermal-aging-of-aeronautical-composite-materials-using-lamb-waves
#14
Mathieu Ducousso, Alban Dalodière, André Baillard
This work aims to demonstrate the ability to evaluate bulk thermal aging of aeronautical composite materials using Lamb waves. These composite materials are bi-dimensional woven composite structures with polymers matrix. More than 20 different thermal aging profiles are obtained by modulating the temperature and curing duration. The impact on material properties is evaluated using normalized destructive characterization and x-ray computed tomography. Lamb waves are generated and detected using a single 3 MHz phased array transducer in contact with the composite structure...
September 27, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30301552/nonlinear-scattering-and-mode-conversion-of-lamb-waves-at-breathing-cracks-an-efficient-numerical-approach
#15
Yanfeng Shen, Carlos E S Cesnik
This article presents an efficient numerical approach to the investigation of nonlinear scattering and mode conversion phenomena of Lamb waves as they interact with breathing cracks. A Local Interaction Simulation Approach (LISA) is adopted, which possesses the versatility to capture arbitrary damage profiles. The stick-slip contact dynamics is implemented in the LISA model via the penalty method, which captures the nonlinear interactions between Lamb waves and breathing cracks. The LISA framework achieves remarkable computational efficiency with its parallel implementation using Compute Unified Device Architecture (CUDA) executed on powerful GPUs...
September 25, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30287073/numerical-prediction-of-ultrasonic-attenuation-in-concentrated-emulsions-and-suspensions-using-monte-carlo-method
#16
Bingfa Huang, Fengxian Fan, Yunsi Li, Mingxu Su
For the study of predicting ultrasonic attenuation of mixed particles and probing the effect of interaction between neighboring particles, the Monte Carlo method was investigated to establish a submicron particle size characterization model in concentrated particulate two-phase system and serve as a probability and statistics technique to evaluate the underlying ultrasonic events during the ultrasound propagation. The numerical simulation method was proposed to predict the ultrasonic attenuation characteristics in the two-phase system of silica suspensions and corn oil-in-water emulsions with different particle sizes, ultrasonic frequencies and concentrations...
September 21, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30287072/instantaneous-frequency-as-a-new-approach-for-evaluating-the-clinical-severity-of-duchenne-muscular-dystrophy-through-ultrasound-imaging
#17
Wen-Chin Weng, Chia-Wei Lin, Hui-Chung Shen, Chien-Cheng Chang, Po-Hsiang Tsui
Duchenne muscular dystrophy (DMD) results in loss of ambulation for the patients. Ultrasound attenuation correlates with fat content in muscles, resulting in changes in signal frequency. The Hilbert-Huang transform (HHT) allows time-frequency analysis with high time-frequency resolution. This study explored the feasibility of using the instantaneous frequency (IF) obtained from the HHT to diagnose the walking function of patients with DMD. Eighty-five participants (12 control and 73 patients with DMD) underwent a standard-care ultrasound examination of the gastrocnemius to acquire raw image data for ultrasound B-mode and IF calculations, which were compared with the DMD stage using Pearson correlation and receiver operating characteristic (ROC) curve analyses...
September 20, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30269931/thermally-tunable-topological-edge-states-for-in-plane-bulk-waves-in-solid-phononic-crystals
#18
Heng Liu, Shao-Yong Huo, Lu-Yang Feng, Hong-Bo Huang, Jiu-Jiu Chen
The remarkable properties of topological insulators have inspired numerous studies on topological transport for bulk waves, but the demonstrations of topological edge states with tunable frequency are few attempts. Here, we report on the active frequency tunability of topologically protected edge states for in-plane bulk waves by applying a thermal field. We find that the center frequency of topological band gap is shifted down and the band width is enlarged as the temperature increases. Meanwhile, the frequency range of topologically protected edge states is also shifted to low frequency region with the higher temperature...
September 14, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30337108/time-domain-model-and-experimental-validation-of-non-contact-surface-wave-scanner
#19
Ji Li, Bogdan Piwakowski
This paper presents a time-domain model for the prediction of acoustic field in an air-coupled, non-contact, ultrasonic surface wave scanner, which includes an air-coupled Emitter, the Propagation space, and an air-coupled Receiver (EPR). The computation is divided into three steps, with each step being modeled in the time domain by its spatio-temporal transfer function. The latter are then used in turn, to find the pulse response of the overall system. The model takes the finite size of the aperture receiver, the attenuation in both air and the tested solid sample, as well as the electric response of the emitter-receiver set he into account...
September 11, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30274854/distributed-point-source-modeling-of-the-scattering-of-elastic-waves-by-a-circular-cavity-in-an-anisotropic-half-space
#20
Samaneh Fooladi, Tribikram Kundu
The Distributed Point Source Method (DPSM) is a modeling technique based on superposition of fundamental solutions corresponding to individual pair of source and target points. A collection of source points distributed over the boundaries and interfaces are responsible for transmission, reflection, and refraction of acoustic waves in the solution domain. The strength of the source points may not be known a priory. By imposing the prescribed conditions on the boundaries and interfaces, a system of equations with the source strengths as the unknowns is obtained...
September 7, 2018: Ultrasonics
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