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K Zong, H Franklin, A Tinel
The directional emission properties of a circular device formed of a small number of metallic rods placed at the nodes of Penrose's tiling are investigated. At the center of the device a non-directional primary source emits monochromatic acoustic waves. In a wide frequency range, the beams come out of the device along preferential directions related to the symmetry of order 5 of the tiling and the non-periodicity in the radial direction. There are some frequencies for which the waves are completely trapped by the device...
January 3, 2019: Ultrasonics
Irem Demirkan, Mehmet Burcin Unlu, Bukem Bilen
The purpose of this study is to explore the feasibility of time-dependent acoustic impedance measurement by Scanning Acoustic Microscopy (SAM) for analyzing the sodium diffusion. The purpose is motivated by the fact that sodium monitoring is challenging and still in the area of exploratory analysis despite its biological importance. To our knowledge, this is the first study in which sodium diffusion has been investigated by time-dependent acoustic impedance measurements provided by SAM. We first tested the idea in an agarose phantom as a proof-of-concept...
December 26, 2018: Ultrasonics
Song Lu, Shi Jingzhuo
The model of ultrasonic motor (USM) is the foundation of the analysis and control of the motor. Ultrasonic motor maintains nonlinear and complicated in dynamics due to its special structure and unique operating, which makes it difficult to establish a good model with traditional modeling. Moreover, the model should be established in line with strong nonlinearities. The nonlinear Hammerstein model of USM is established in this paper, which can better characterize the nonlinear motor. To adapt the model to the need of position control of ultrasonic motor, driving frequency and rotor position are considered as the input and output variables of the Hammerstein model respectively...
December 23, 2018: Ultrasonics
Mawia Khairalseed, Katherine Brown, Kevin J Parker, Kenneth Hoyt
H-scan ultrasound (US) is a new imaging technique that relies on matching a model that describes US image formation to the mathematics of a class of Gaussian-weighted Hermite polynomials (GH). In short, H-scan US (where the 'H' denotes Hermite or hue) is a tissue classification technique that images the relative size of acoustic scatterers. Herein, we detail development of a real-time H-scan US imaging technology that was implemented on a programmable US research scanner (Vantage 256, Verasonics Inc, Kirkland, WA)...
December 20, 2018: Ultrasonics
Ngoc Nguyen, Agne Johannessen, Stig Rooth, Ulrik Hanke
The dependence of the performance of thin film bulk acoustic resonator (FBAR) and solidly mounted resonator (SMR), on their areas is studied with the aid of finite element method (FEM) software. Dual step frame method is applied for both types of the resonators in order to improve their quality factors at resonance and at antiresonance frequency when they are miniaturized. The important role of the material quality in promoting the benefit of this method is also emphasized in this study.
December 14, 2018: Ultrasonics
Souhail Dahmen
Before a nondestructive testing process gets set up, the sensitivity of the Lamb waves to the bonded plate's properties must be well understood. The dispersion and attenuation curves in thin bonded Aluminum/Adhesive/Aluminum plate are calculated by the Stiffness matrix method. The increase in the volumic fraction d caused the appearance of backward mode in the S0 and S2 dispersion curves. The effect of d on forward waves, and on backward waves and associated ZGV-modes, are studied. The frequencies of ZGV-modes decrease when d increases...
December 11, 2018: Ultrasonics
Shokichi Tanaka, Hideyuki Nomura, Tomoo Kamakura
Underwater ultrasonic devices using the Doppler effect generally presuppose that the speed of sound is uniform in a propagation medium. Actually, however, the speed of sound in the sea varies with water depth, so that the assumption of such uniform speed has the potential to cause measurement errors. The present study is then involved in theoretically improving the conventional Doppler shift equation by taking into account the fact that the speed of sound is dependent on the propagation path. The study also evaluates measurement errors caused by spatial variation in the speed of sound...
December 11, 2018: Ultrasonics
M Y Matuda, F Buiochi, J C Adamowski
In ultrasonic nondestructive testing, when using an ultrasonic linear array transducer for imaging objects with nonplanar surfaces, a coupling medium must be used. To compensate for the refraction at the coupler-object interface, its shape must be known. Two methods for surface detection of convex objects in immersion are proposed, using the same linear array transducer for surface detection and for SAFT imaging. One is based on imaging technique and the other is based on the time-of-flight of the echoes on the captured ultrasonic signals...
December 7, 2018: Ultrasonics
Crislene Silva, J J S de Figueiredo, Tatiana Chichinina, Murillo J S Nascimento, Leo Kirchhof
The study of fractures in subsurface is very important since they are, in some cases, the main conduits for hydrocarbon flow in a reservoir. There are many ways to study the behavior of seismic waves in different fracturing conditions, including the use of physical modeling. This method allows, among other approaches, the analysis of the behavior of seismic wave properties in complex fractured media, such as media with orthorhombic symmetry. In this work we performed ultrasonic measurements on fractured physical models with orthorhombic symmetry from which we analyzed the behavior of elastic velocities and anisotropy parameters for different number of fractures...
December 6, 2018: Ultrasonics
R G Kryshtal, A V Medved
Surface acoustic waves (SAW) in dynamic magnonic crystals (DMC) are considered for their use to create tunable spin-wave gadgets for processing of microwave signals. To understand the principles of operation of the proposed gadgets, the necessary basic properties of DMC created by a SAW in the structure of "yttrium iron garnet film on a substrate of gallium gadolinium garnet" are given. The prototype of the unique nonreciprocal notch filter working in the range of 3600-4100 MHz at the biasing magnetic field of 640 Oe is fabricated and its main characteristics such as dependences of the frequency and the depth of rejection pits on the frequency and power of the controlling SAW are measured...
December 4, 2018: Ultrasonics
Nauman Munir, Hak-Joon Kim, Jinhyun Park, Sung-Jin Song, Sung-Sik Kang
Ultrasonic flaw classification in weldment is an active area of research and many artificial intelligence approaches have been applied to automate this process. However, in the industrial applications, the ultrasonic flaw signals are not noise free and automatic intelligent defect classification algorithms show relatively low classification performance. In addition, most of the algorithms require some statistical or signal processing techniques to extract some features from signals in order to make classification easier...
December 1, 2018: Ultrasonics
Zhongtao Hu, Zhiwu An, Yuanyuan Kong, Guoxuan Lian, Xiaomin Wang
The aim of this paper is to investigate propagation characteristics and the generation mechanism of the nonlinear lowest-order symmetric Lamb mode (S0 ) which propagates downslope in free elastic plates with slowly linearly varying-thickness. From theoretical analyses, in a low frequency-thickness product (fd) range, the S0 mode is slightly dispersive, it is easy to generate, and it approximately satisfies the principle of the phase velocity matching. Therefore, if a S0 mode is excited at a proper frequency in the low fd range, the amplitude of the second harmonic wave is linearly increasing in a certain propagating-distance, which is valuable for the practical NDE application of the second harmonic wave...
November 30, 2018: Ultrasonics
Francisco Javier Oyaga Landa, Silvia Ronda Penacoba, Francisco Montero de Espinosa, Daniel Razansky, Xosé Luís Deán-Ben
Medium-intensity focused ultrasound (MIFU) concerns therapeutic ultrasound interventions aimed at stimulating physiological mechanisms to reinforce healing responses without reaching temperatures that can cause permanent tissue damage. The therapeutic outcome is strongly affected by the temperature distribution in the treated region and its accurate monitoring represents an unmet clinical need. In this work, we investigate on the capacities of four-dimensional optoacoustic tomography to monitor tissue heating with MIFU...
November 27, 2018: Ultrasonics
Amrita Das, Abhishek Kumar Singh, Prajnya Parimita Patel, Kshitish Ch Mistri, Amares Chattopadhyay
The rapid development of the modern age has increased the urge of using composite structures having applications in the realm of various engineering fields. Specifically, fibre-reinforced piezoelectric composites are in the forefront of the present era because of its light weight, great strength and hence improved performance over the piezoelectric materials alone. Therefore, the present paper delves with the problem of reflection and refraction of plane waves when it is incident at the interface of a Piezoelectric Fibre-reinforced Composite (PFRC) medium and Fibre-reinforced Composite (FRC) medium...
November 27, 2018: Ultrasonics
Francesco Cenni, Davide Monari, Simon-Henri Schless, Erwin Aertbeliën, Kaat Desloovere, Herman Bruyninckx
The ultrasound (US) probe spatial calibration is a key prerequisite for enabling the use of the 3D freehand US technique. Several methods have been proposed for achieving an accurate and precise calibration, although these methods still require specialised equipment. This equipment is often not available in research or clinical facilities. Therefore, the present investigation aimed to propose an efficient US probe calibration method that is accessible in terms of cost, easy to apply and capable of achieving results suitable for clinical applications...
November 27, 2018: Ultrasonics
Fushi Bai, Yangyang Long, Kai-Alexander Saalbach, Jens Twiefel
Ultrasonic cavitation peening is a potential surface enhancement process. During this process a high input power is necessary to obtain an effective process result. A small gap, usually less than 1 mm, between the sonotrode tip and the treated surface is also required to avoid substantial energy loss. Due to the high vibration of the sonotrode, many cavitation bubbles are generated, forming a thin bubbly liquid layer in the small gap. The cavitation bubbles in the layer seriously disturb the sound wave propagation and interact with each other...
November 27, 2018: Ultrasonics
Florian Staab, Frank Balle
Ultrasonic metal welding is a promising process for joining light metals with fiber-reinforced thermoplastics. The technique is characterized by high reproducibility, short process times, low energy input, no additional filler materials and finally the possibility of extensive process data logging. With this process, dissimilar aerospace materials are ultrasonically welded and the applied process parameters are optimized by statistical methods. A prediction of ageing resistance is possible by the evaluation of the electrical resistivity of the multi-material-joints...
November 22, 2018: Ultrasonics
Wuwei Mao, Yang Yang, Wenli Lin
Shallow foundation is a common foundation type that is usually used for small to medium size structures. The bearing ability and the failure mechanism of shallow foundation are the fundamental concerns for geotechnical engineers, and the demand for new insights into the relevant issue is still increasing. This paper presents an acoustic emission (AE) characterization of the failure process of shallow foundation, with the aim of revealing the fundamental information on AE signals associated with shallow foundation loading as well as its connection with the ground bearing behavior...
November 22, 2018: Ultrasonics
M M Narayanan, Anish Kumar, S Thirunavukkarasu, C K Mukhopadhyay
An ultrasonic guided wave based methodology is developed for inspection of steam generator tubes of the prototype fast breeder reactor. To this aim, axisymmetric longitudinal mode (L(0,2)) at the frequency of 250 kHz is optimized using 3D-finite element simulation and experiments. The group velocity of mode L(0,2) at 250 kHz is found to be 5387 m/s. First, the long range propagation of the L(0,2) mode at 250 kHz is examined and the mode is found to propagate over a distance of 45.6 m with a sufficiently good SNR...
November 10, 2018: Ultrasonics
G Kolappan Geetha, D Roy Mahapatra
In this paper, a thermodynamically consistent generalized three-dimensional modeling scheme is developed to simulate vibro-thermography and subsequently perform a quantitative investigation on a test structure. Simulation results are analyzed considering a plate with Structural Features (SF) which are used in a gas turbine engine structural components to reduce structural mass and enhance cooling. The modeling framework includes (i) coupled thermo-elastic heat generation and (ii) effects of various sources of nonlinear vibration arising due to the amplitude of the excitation, the engagement force on the target structure due to the ultrasonic horn, and structural boundary conditions...
November 5, 2018: Ultrasonics
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