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Andrew Feeney, Sakalima Sikaneta, Patrick Harkness, Margaret Lucas
It has been shown that the compaction of granular materials for applications such as pharmaceutical tableting and plastic moulding can be enhanced by ultrasonic vibration of the compaction die. Ultrasonic vibrations can reduce the compaction pressure and increase particle fusion, leading to higher strength products. In this paper, the potential benefits of ultrasonics in the compaction of geological granular materials in downhole applications are explored, to gain insight into the effects of ultrasonic vibrations on compaction of different materials commonly encountered in sub-sea drilling...
January 5, 2017: Ultrasonics
Emma Lubeigt, Serge Mensah, Sandrine Rakotonarivo, Jean-François Chaix, François Baqué, Gilles Gobillot
Detecting, imaging and sizing defects in a bounded elastic medium is still a difficult task, especially when access is complex. Adjoint methods simplify the task as they take advantage of prior information such as the geometry and material properties. However, they still reveal a number of important limitations. Artifacts observed on the conventional topological energy image result from wave interactions with the boundaries of the inspected medium. The paper describes a method for addressing these artifacts, which involves forward and adjoint fields specified in terms of the boundary conditions...
January 4, 2017: Ultrasonics
Hao-Wen Dong, Yue-Sheng Wang, Chuanzeng Zhang
Topology optimization of a waveguide-cavity structure in phononic crystals for designing narrow band filters under the given operating frequencies is presented in this paper. We show that it is possible to obtain an ultra-high-Q filter by only optimizing the cavity topology without introducing any other coupling medium. The optimized cavity with highly symmetric resonance can be utilized as the multi-channel filter, raising filter and T-splitter. In addition, most optimized high-Q filters have the Fano resonances near the resonant frequencies...
December 29, 2016: Ultrasonics
Woo Kyung Moon, I-Ling Chen, Jung Min Chang, Sung Ui Shin, Chung-Ming Lo, Ruey-Feng Chang
Screening ultrasound (US) is increasingly used as a supplement to mammography in women with dense breasts, and more than 80% of cancers detected by US alone are 1cm or smaller. An adaptive computer-aided diagnosis (CAD) system based on tumor size was proposed to classify breast tumors detected at screening US images using quantitative morphological and textural features. In the present study, a database containing 156 tumors (78 benign and 78 malignant) was separated into two subsets of different tumor sizes (<1cm and ⩾1cm) to explore the improvement in the performance of the CAD system...
December 28, 2016: Ultrasonics
H Chen, X P Li, Y Y Chen, G L Huang
In this study, a sandwich beam with periodic multiple dissipative resonators in the sandwich core material is investigated for broadband wave mitigation and/or absorption. An analytical approach based on the transfer matrix method and Bloch theorem is developed for both infinite and finite sandwich structures. Wave attenuation constants are theoretically obtained to examine the effects of various system parameters on the position, width and wave attenuation performance of the band gaps. The wave absorption coefficient of the sandwich beam is quantitatively studied to distinguish wave attenuation mechanisms caused by reflection and absorption...
December 26, 2016: Ultrasonics
Hamdi Ezzin, Morched Ben Amor, Mohamed Hédi Ben Ghozlen
A dynamic solution is presented for the propagation of harmonic waves in magneto-electro-elastic plates composed of piezoelectric BaTiO3(B) and magnetostrictive CoFe2O4(F) material. The state-vector approach is employed to derive the propagator matrix which connects the field variables at the upper interface to those at the lower interface of each layer. The ordinary differential approach is employed to determine the wave propagating characteristics in the plate by imposing the traction-free boundary condition on the top and bottom surfaces of the layered plate...
December 26, 2016: Ultrasonics
Bernard Masserey, Paul Fromme
The scattering of high frequency guided ultrasonic waves by a fatigue crack at the side of a fastener hole has been studied. The guided wave pulse consists of the superposition of the two fundamental Lamb modes A0 and S0 above the cut-off frequencies of the higher modes. The scattered field was simulated using a three-dimensional finite difference algorithm with a staggered, Cartesian grid for the limited area of interest around the hole and an analytical phase angle correction for the additional, variable propagation distance...
December 25, 2016: Ultrasonics
Wenke Lu, Yang Feng, Changchun Zhu, Jianli Zheng
The objective of this research was to investigate the possibility of the temperature compensation for the surface acoustic wave (SAW) yarn tension sensor. The motivation for this work was prompted by the oscillation frequency of the SAW yarn tension sensor varying with the temperature. In this paper, we deduce the functional relationship between the temperature variation and the oscillation frequency shift caused by the temperature. This functional relationship and the temperature sensor are used to get the oscillation frequency shift caused by the temperature, so that we can use the oscillation frequency shift caused by the temperature to implement the temperature compensation of the SAW yarn tension sensor...
December 23, 2016: Ultrasonics
Janusz Wojcik, Marcin Lewandowski, Norbert Żołek
A method of suppression of grating lobes is presented, analyzed, and verified. The method is based on creating a Virtual Receiving Subaperture (VRS) by adding virtual transducer elements not existing in the physical layout of the receiver. The VRS channels are filled with data based on signals from real channels. The analytical model of the synthetic aperture imaging system's impulse response is presented to describe the properties of the VRS. The model shows a reduction of the receiving grating lobes' amplitude (with a comparison to the main lobe's amplitude) by a magnitude equal to the number of receiving transducer elements...
December 21, 2016: Ultrasonics
Maryam Talebi, Milad Setareh, Majid Saffar-Avval, Reza Hosseini Abardeh
Application of ultrasonic waves for heat transfer augmentation has been proposed in the last few decades. Due to limited researches on acoustic streaming induced by ultrasonic oscillation, the effect of ultrasonic waves on natural convection heat transfer is the main purpose of this paper. At first, natural convection on up-ward-facing heating surface in a cylindrical enclosure filled with air is investigated numerically by the finite difference method, then the effect of upper surface oscillation on convection heat transfer is considered...
December 18, 2016: Ultrasonics
Fuda Ning, Hui Wang, Weilong Cong, P K S C Fernando
Rotary ultrasonic machining (RUM) has been investigated in machining of brittle, ductile, as well as composite materials. Ultrasonic vibration amplitude, as one of the most important input variables, affects almost all the output variables in RUM. Numerous investigations on measuring ultrasonic vibration amplitude without RUM machining have been reported. In recent years, ultrasonic vibration amplitude measurement with RUM of ductile materials has been investigated. It is found that the ultrasonic vibration amplitude with RUM was different from that without RUM under the same input variables...
December 18, 2016: Ultrasonics
Chen Jiang, Xiaozhou Liu, Jiehui Liu, Yiwei Mao, Philip L Marston
By means of series expansion theory, the incident quasi-Bessel-Gauss beam is expanded using spherical harmonic functions, and the beam coefficients of the quasi-Bessel-Gauss beam are calculated. According to the theory, the acoustic radiation force function, which is the radiation force per unit energy on a unit cross-sectional surface on a sphere made of diverse materials and immersed in an ideal fluid along the propagation axis of zero-order quasi-Bessel-Gauss progressive and standing beams, is investigated...
December 18, 2016: Ultrasonics
Zhihui Han, Hu Peng, Putian Lu
Freehand three-dimensional (3D) ultrasound imaging usually uses a moving elevation focused one-dimensional (1D) transducer to construct a series of B-mode slice images, and then these B-mode slice images are combined to form a 3D volume image. This method has poor elevation resolution and low frame rate. In this paper, a novel 3D imaging method with a moving 1D array transducer is proposed. Different from the freehand 3D reconstruction, a linear array transducer without elevation focusing is used in the proposed method, and the 1D transducer transmits limited diffraction beams and receives echo signals repeatedly when moving along the elevation direction...
December 16, 2016: Ultrasonics
Amir Gholampour, Sayed Mahmoud Sakhaei, Seyed Mehdi Hosseini Andargoli
Apodization is a common way to control the sidelobe level of the beampattern. To design the apodization, it is usually assumed that the medium is homogenous with a fixed value of sound speed, despite the fact that the speed may vary by a great value in practical situations. On the other hand, the beamforming performance is highly affected by the speed value. In this paper, the beampattern sensitivity to the speed variations is firstly investigated through both mathematical representations and simulation results showing that the speed errors lead to a sever degradation of the beampattern in terms of both mainlobe width and sidelobe level...
December 16, 2016: Ultrasonics
Tamara Kujawska, Wojciech Secomski, Michał Byra, Michiel Postema, Andrzej Nowicki
A technique using pulsed High Intensity Focused Ultrasound (HIFU) to destroy deep-seated solid tumors is a promising noninvasive therapeutic approach. A main purpose of this study was to design and test a HIFU transducer suitable for preclinical studies of efficacy of tested, anti-cancer drugs, activated by HIFU beams, in the treatment of a variety of solid tumors implanted to various organs of small animals at the depth of the order of 1-2cm under the skin. To allow focusing of the beam, generated by such transducer, within treated tissue at different depths, a spherical, 2-MHz, 29-mm diameter annular phased array transducer was designed and built...
December 12, 2016: Ultrasonics
Tiansi Wang, Chong Zhang, Aleksandar Aleksov, Islam Salama, Aravinda Kar
Phased array ultrasonic transducers enable modulating the focal position of the acoustic waves, and this capability is utilized in many applications, such as medical imaging and non-destructive testing. This type of transducers also provides a mechanism to generate tilted wavefronts in acousto-optic deflectors to deflect laser beams for high precision advanced laser material processing. In this paper, a theoretical model is presented for the diffraction of ultrasonic waves emitted by several phased array transducers into an acousto-optic medium such as TeO2 crystal...
December 9, 2016: Ultrasonics
Shuai Na, Lawrence L P Wong, Albert I H Chen, Zhenhao Li, Mirek Macecek, John T W Yeow
Air-coupled capacitive micromachined ultrasonic transducers (CMUTs) based on annular cell geometry have recently been reported. Finite element analysis and experimental studies have demonstrated their significant improvement in transmit efficiency compared with the conventional circular-cell CMUTs. Extending the previous work, this paper proposed a lumped element model of annular-cell CMUTs. Explicit expressions of the resonance frequency, modal vector, and static displacement of a clamped annular plate under uniform pressure were first derived based on the plate theory and curve fitting method...
November 23, 2016: Ultrasonics
Jing Liu, Jianke Du, Ji Wang, Jiashi Yang
We studied free vibrations of thin-film bulk acoustic wave filters with interdigital electrodes theoretically using the scalar differential equations by Tiersten and Stevens. The filters are made from AlN or ZnO films on Si substrates with ground and driving electrodes. They operate with thickness-extensional modes. The basic vibration characteristics including resonant frequencies and mode shapes were obtained. Their dependence on various geometric parameters was examined. It was found that for properly design filters there exist trapped modes whose vibrations are strong in regions with a driving electrode and decay away from the electrode edges...
March 2017: Ultrasonics
Giulia Matrone, Alessandro Stuart Savoia, Giosuè Caliano, Giovanni Magenes
The Synthetic Aperture Focusing (SAF) technique makes it possible to achieve a higher and more uniform quality of ultrasound images throughout depth, as if both transmit and receive dynamic focusing were applied. In this work we combine a particular implementation of SAF, called Synthetic Transmit Aperture (STA) technique, in which a single element in turn transmits and all the array elements receive the ultrasound wave, with the Filtered-Delay Multiply and Sum (F-DMAS) non-linear beamforming algorithm that we presented in a previous paper...
March 2017: Ultrasonics
Mingxi Deng, Guangjian Gao, Yanxun Xiang, Mingliang Li
The feasibility of using the nonlinear effect of primary Circumferential Guided Wave (CGW) propagation for assessing accumulated damage in circular tubes has been investigated. For a given circular tube, an appropriate mode pair of fundamental and double frequency CGWs is chosen to enable that the second harmonic of the primary wave mode can accumulate along the circumferential direction. After the given circular tube is subjected to compression-compression repeated loading for different numbers of loading cycles, the corresponding ultrasonic measurements are conducted...
March 2017: Ultrasonics
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