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Peng Li, Li Cheng
The propagation of thickness shear waves in a periodically corrugated quartz crystal plate is investigated in the present paper using a power series expansion technique. In the proposed simulation model, an equivalent continuity of shear stress moment is introduced as an approximation to handle sectional interfaces with abrupt thickness changes. The Bloch theory is applied to simulate the band structures for three different thickness variation patterns. It is shown that the power series expansion method exhibits good convergence and accuracy, in agreement with results by finite element method (FEM)...
February 7, 2017: Ultrasonics
U Raghavendra, U Rajendra Acharya, Anjan Gudigar, Jen Hong Tan, Hamido Fujita, Yuki Hagiwara, Filippo Molinari, Pailin Kongmebhol, Kwan Hoong Ng
Thyroid is a small gland situated at the anterior side of the neck and one of the largest glands of the endocrine system. The abrupt cell growth or malignancy in the thyroid gland may cause thyroid cancer. Ultrasound images distinctly represent benign and malignant lesions, but accuracy may be poor due to subjective interpretation. Computer Aided Diagnosis (CAD) can minimize the errors created due to subjective interpretation and assists to make fast accurate diagnosis. In this work, fusion of Spatial Gray Level Dependence Features (SGLDF) and fractal textures are used to decipher the intrinsic structure of benign and malignant thyroid lesions...
February 6, 2017: Ultrasonics
I A Nedospasov, V G Mozhaev, I E Kuznetsova
It is found that leaky backward Lamb waves, i.e. waves with negative energy-flux velocity, propagating in a plate submerged in a liquid possess extraordinary energy properties distinguishing them from any other type of waves in isotropic media. Namely, the total time-averaged energy flux along the waveguide axis is equal to zero for these waves due to opposite directions of the longitudinal energy fluxes in the adjacent media. This property gives rise to the fundamental question of how to define and calculate correctly the energy velocity in such an unusual case...
February 1, 2017: Ultrasonics
Yue Jian, Zhiyuan Yao, Vadim V Silberschmidt
Thanks to their compactness and suitability for vacuum applications, linear ultrasonic motors are considered as substitutes for classical electromagnetic motors as driving elements in absolute gravimeters. Still, their application is prevented by relatively low power output. To overcome this limitation and provide better stability, a V-type linear ultrasonic motor with a new clamping method is proposed for a gravimeter. In this paper, a mechanical model of stators with flexible clamping components is suggested, according to a design criterion for clamps of linear ultrasonic motors...
February 1, 2017: Ultrasonics
I A Renteria Marquez, V Bolborici
This manuscript presents a method to model in detail the piezoelectric traveling wave rotary ultrasonic motor (PTRUSM) stator response under the action of DC and AC voltages. The stator is modeled with a discrete two dimensional system of equations using the finite volume method (FVM). In order to obtain accurate results, a model of the stator bridge is included into the stator model. The model of the stator under the action of DC voltage is presented first, and the results of the model are compared versus a similar model using the commercial finite element software COMSOL Multiphysics...
January 31, 2017: Ultrasonics
Kaige Zhu, Xinlin P Qing, Bin Liu
The paper presents an application of the reverberation-ray matrix (RRM) method for guided wave-based non-destructive evaluation (NDE). An exact analytical model for elastic wave propagation in multilayered anisotropic composites is developed with the RRM method. Dispersion curves, namely phase and group velocities varying with frequencies, can be calculated based on the analytical model, which are critical to the guided wave-based NDE. In addition, the characteristics of the guided wave propagation along different directions in laminated composites with different anisotropic degrees are investigated...
January 30, 2017: Ultrasonics
L Bonin, N Bains, V Vitry, A J Cobley
The effect of ultrasound on the properties of Nickel-Boron (NiB) coatings was investigated. NiB coatings were fabricated by electroless deposition using either ultrasonic or mechanical agitation. The deposition of Ni occurred in an aqueous bath containing a reducible metal salt (nickel chloride), reducing agent (sodium borohydride), complexing agent (ethylenediamine) and stabilizer (lead tungstate). Due to the instability of the borohydride in acidic, neutral and slightly alkaline media, pH was controlled at pH 12±1 in order to avoid destabilizing the bath...
January 30, 2017: Ultrasonics
Takahiro Hayashi, Ken Ishihara
Pulsed laser equipment can be used to generate elastic waves through the instantaneous reaction of thermal expansion or ablation of the material; however, we cannot control the waveform generated by the laser in the same manner that we can when piezoelectric transducers are used as exciters. This study investigates the generation of narrowband tone-burst waves using a fiber laser of the type that is widely used in laser beam machining. Fiber lasers can emit laser pulses with a high repetition rate on the order of MHz, and the laser pulses can be modulated to a burst train by external signals...
January 26, 2017: Ultrasonics
Kui Qian, Chenghai Li, Zhengyang Ni, Juan Tu, Xiasheng Guo, Dong Zhang
Both theoretical and experimental studies were performed here to investigate the lesion formation induced by high-intensity focused ultrasound (HIFU) operating in continuous scanning mode along a spiral pathway. The Khokhlov-Zabolotskaya-Kuznetsov equation and bio-heat equation were combined in the current model to predict HIFU-induced temperature distribution and lesion formation. The shape of lesion and treatment efficiency were assessed for a given scanning speed at two different grid spacing (3mm and 4mm) in the gel phantom studies and further researched in ex vivo studies...
January 24, 2017: Ultrasonics
M E Kiziroglou, D E Boyle, S W Wright, E M Yeatman
The use of energy harvesting for powering wireless sensors is made more challenging in most applications by the requirement for customization to each specific application environment because of specificities of the available energy form, such as precise location, direction and motion frequency, as well as the temporal variation and unpredictability of the energy source. Wireless power transfer from dedicated sources can overcome these difficulties, and in this work, the use of targeted ultrasonic power transfer as a possible method for remote powering of sensor nodes is investigated...
January 23, 2017: Ultrasonics
Anil Kumar Jain, Pulak M Pandey
Un-deformed chip thickness is a critical parameter in machining processes. Measuring un-deformed chip thickness experimentally is a complicated process, especially in micro machining and may not even be measured accurately. The un-deformed chip thickness has an influence on material removal rate, cutting forces, specific energy and surface finish etc. In ceramic machining, it is also an indication of material removal mode such as ductile or brittle fracture. In the present study, an effort is made to model undeformed chip thickness, cutting forces and specific cutting energy in rotary ultrasonic machining (RUM) applied to the side milling operation...
January 23, 2017: Ultrasonics
E Verona, V I Anisimkin, V A Osipenko, N V Voronova
A novel structure consisting of a Si plate sandwiched between two ZnO layers is suggested as propagation medium for Quasi Longitudinal (QL) acoustic Lamb waves. Considering a low-dispersive quasi-longitudinal mode as an example, the phase velocity v, electromechanical coupling constant k(2) and mechanical displacements U1, U3 versus plate and ZnO layers thicknesses have been calculated starting from uncoated plate through the same plate with one layer to the plate with two layers onto opposite faces. A remarkable increase in the electromechanical coupling, together with an essential decrease in the vertical displacement U3, at the ZnO surface, have been theoretically demonstrated and experimentally verified for definite combinations of the films/plate thicknesses...
January 23, 2017: Ultrasonics
Dongsheng Li, Wei Yang, Wenyao Zhang
Stress corrosion is the major failure type of bridge cable damage. The acoustic emission (AE) technique was applied to monitor the stress corrosion process of steel wires used in bridge cable structures. The damage evolution of stress corrosion in bridge cables was obtained according to the AE characteristic parameter figure. A particle swarm optimization cluster method was developed to determine the relationship between the AE signal and stress corrosion mechanisms. Results indicate that the main AE sources of stress corrosion in bridge cables included four types: passive film breakdown and detachment of the corrosion product, crack initiation, crack extension, and cable fracture...
January 18, 2017: Ultrasonics
Vincent Hingot, Claudia Errico, Mickael Tanter, Olivier Couture
Ultrafast Ultrasound Localization Microscopy uses microbubbles that are individually localized with a resolution below 10μm. Positions of the microbubbles are accumulated to create a super resolution image, which bypass the diffraction-limit of spatial resolution. However, microbubbles localization is affected by physiological motions at the micrometric scale. Here, we demonstrate a phase correlation method for rigid motion correction. Spatiotemporal filters extract tissue dominated images, which are tracked to correct linear motions and improve the precision of microbubbles' localization, improving the quality of the image...
January 18, 2017: Ultrasonics
Margot Pasternak, Eigil Samset, Jan D'hooge, Geir U Haugen
Ultrasound thermometry is based on measuring tissue temperature by its impact on ultrasound wave propagation. This study focuses on the use of transducer array channel data (not beamformed) and examines how a layer of increased velocity (heat induced) affects the travel-times of the ultrasound backscatter signal. Based on geometric considerations, a new equation was derived for the change in time delay as a function of temperature change. The resulting expression provides insight into the key factors that link change in temperature to change in travel time...
January 16, 2017: Ultrasonics
N Bahbah, A Novell, A Bouakaz, H Djelouah
The goal of this work is to exploit the statistical signatures for discrimination between biological tissues and contrast microbubbles in order to develop new strategies for contrast imaging and tissue characterization. For this purpose, the efficiency of the Nakagami statistical model, for describing the ultrasonic echoes of both contrast microbubbles and tissues, was investigated. Experimental measurements have been performed using a linear array probe connected to an open research platform. A commercially available in vitro phantom was used to mimic biological tissue in which SonoVue contrast microbubbles were flowing...
January 16, 2017: Ultrasonics
Rafika Ben Haj Slama, Bruno Gilles, Maher Ben Chiekh, Jean-Christophe Béra
This research evaluates the use of Particle Image Velocimetry (PIV) technique for characterizing acoustic streaming flow generated by High Intensity Focused Ultrasound (HIFU). PIV qualification tests, focusing on the seeding particle size (diameter of 5, 20 and 50μm) were carried out in degassed water subjected to a focused field of 550kHz-frequency with an acoustic pressure amplitude of 5.2, 10.5 and 15.7bar at the focus. This study shows that the ultrasonic field, especially the radiation force, can strongly affect seeding particle behavior...
January 14, 2017: Ultrasonics
Antonio Jiménez, Montaña Rufo, Jesús M Paniagua, Abel T Crespo, M Patricia Guerrero, M José Riballo
Ultrasound evaluation permits the state of milk being curdled to be determined quickly and cheaply, thus satisfying the demands faced by today's dairy product producers. This paper describes the non-invasive ultrasonic method of in situ monitoring the changing physical properties of milk during the renneting process. The basic objectives of the study were, on the one hand, to confirm the usefulness of conventional non-destructive ultrasonic testing (time-of-flight and attenuation of the ultrasound waves) in monitoring the process in the case of ewe's milk, and, on the other, to include other ultrasound parameters which have not previously been considered in studies on this topic, in particular, parameters provided by the Fast Fourier Transform technique...
January 10, 2017: Ultrasonics
Jian Liu, Jiamei Jin, Ruinan Ji, Di Chen
In this paper, a novel modal-independent ultrasonic motor with dual stator is proposed, in order to relieve the difficulty of adjustment for coincidence of modal frequencies of a stator for multi-modal coupling type ultrasonic motor (USM). It consists of two stators (an upper stator and a lower stator) and a rotor. The stators are excited the 3rd longitudinal vibration mode, by arranging the location of rotor and two stators, the rotor can realize rotary motion by friction effect with the stators. The rotor is mounted between the maximum deformation location of the upper stator and the nodal line of the lower stator...
January 10, 2017: Ultrasonics
Linas Svilainis, Kristina Lukoseviciute, Dobilas Liaukonis
ToF estimation errors for two reflections have been analyzed. Case of high signal-to-noise ratio was assumed, when accuracy of the order of few nanoseconds can be achieved. It was indicated that additional bias errors are introduced in ToF estimator when other reflection is in close temporal proximity to the reflection of interest. Research demonstrates that iterative deconvolution does not improve the accuracy significantly. Novel technique is suggested which addresses this issue by means of a reiterative deconvolution...
January 7, 2017: Ultrasonics
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