scholarly journals Sub-wavelength lateral detection of tissue-approximating masses using an ultrasonic metamaterial lens

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Ezekiel L. Walker ◽  
Yuqi Jin ◽  
Delfino Reyes ◽  
Arup Neogi
Keyword(s):  
Biomedical Imaging ◽  
Fresnel Zone ◽  
Phononic Crystal ◽  
Lateral Resolution ◽  
Spatial Characterization ◽  
Tissue Phantoms ◽  
Subwavelength Resolution ◽  
Object Features ◽  
Sub Wavelength

AbstractPractically applied techniques for ultrasonic biomedical imaging employ delay-and-sum (DAS) beamforming which can resolve two objects down to 2.1λ within the acoustic Fresnel zone. Here, we demonstrate a phononic metamaterial lens (ML) for detection of laterally subwavelength object features in tissue-like phantoms beyond the phononic crystal evanescent zone and Fresnel zone of the emitter. The ML produces metamaterial collimation that spreads 8x less than the emitting transducer. Utilizing collimation, 3.6x greater lateral resolution beyond the Fresnel zone limit was achieved. Both hard objects and tissue approximating masses were examined in gelatin tissue phantoms near the Fresnel zone limit. Lateral dimensions and separation were resolved down to 0.50λ for hard objects, with tissue approximating masses slightly higher at 0.73λ. The work represents the application of a metamaterial for spatial characterization, and subwavelength resolution in a biosystem beyond the Fresnel zone limit.

scholarly journals Sub-wavelength phononic crystal liquid sensor

2011 ◽  
Vol 110 (2) ◽  
pp. 026101 ◽  
Author(s):  
Manzhu Ke ◽  
Mikhail Zubtsov ◽  
Ralf Lucklum
Keyword(s):  
Phononic Crystal ◽  
Sub Wavelength

Ultrafast Rayleigh-like streaming in a sub-wavelength slit between two phononic crystal plates

2019 ◽  
Vol 125 (13) ◽  
pp. 134903 ◽  
Author(s):  
Fei Li ◽  
Xiangxiang Xia ◽  
Zhiting Deng ◽  
Junjun Lei ◽  
Yaxi Shen ◽  
...  
Keyword(s):  
Phononic Crystal ◽  
Sub Wavelength

scholarly journals the Interaction of Resonance And Bragg Scattering Effects for the Locally Resonant Phononic Crystal with Alternating Elastic and Fluid Matrices

2017 ◽  
Vol 42 (4) ◽  
pp. 725-733 ◽  
Author(s):  
Bo Yuan ◽  
Yong Chen ◽  
Min Jiang ◽  
Shuai Tang ◽  
Miao He ◽  
...  
Keyword(s):  
Phononic Crystal ◽  
Three Dimensional ◽  
Band Gaps ◽  
Acoustic Properties ◽  
Bragg Scattering ◽  
Wavelength Band ◽  
Local Resonance ◽  
Scattering Effects ◽  
Acoustic Speed ◽  
Sub Wavelength

Abstract Three-dimensional (3D) locally resonant phononic crystals (LRPCs) are studied with the aim of optimising the sub-wavelength band gaps of such composites. By analysing their effective acoustic properties, it has been found that the effective acoustic speed of the composite will drop to zero when local resonance arise, and will increase monotonically when Bragg scattering effects occur. Moreover, if the matrix is a low-shear-speed medium, local resonators can significantly reduce the effective acoustic speed of the composite and, therefore, lower the frequency where Bragg scattering effects occur. Hence, a specific LRPC with alternating elastic and fluid matrices is proposed, whose resonance and Bragg gaps are already close in frequency. The fluid matrix behaves as a wave filter, which prevents the shear waves from propagating in the composite. By using the layer-multiple-scattering theory, the coupling behaviour of local resonance and Bragg scattering band gaps has been investigated. Both gaps are enhanced when they move closer to each other. Finally, a gap-coupled case is obtained that displays a broad sub-wavelength band gap. Such proposal excels at the application of underwater acoustic materials since the arrangement of structure can be handily adjusted for tuning the frequency of coupled gap.

scholarly journals A High-Frequency Homogenization Approach Near the Dirac Points in Bubbly Honeycomb Crystals

2020 ◽  
Vol 238 (3) ◽  
pp. 1559-1583 ◽  
Author(s):  
Habib Ammari ◽  
Erik Orvehed Hiltunen ◽  
Sanghyeon Yu
Keyword(s):  
High Frequency ◽  
Arbitrary Shape ◽  
Phononic Crystal ◽  
The Other ◽  
Numerical Examples ◽  
Dirac Equations ◽  
Homogenization Approach ◽  
First Time ◽  
Compare And Contrast ◽  
Sub Wavelength

Abstract In (Ammari et al. in SIAM J Math Anal. arXiv:1811.03905), the existence of a Dirac dispersion cone in a bubbly honeycomb phononic crystal comprised of bubbles of arbitrary shape is shown. The aim of this paper is to prove that, near the Dirac points, the Bloch eigenfunctions is the sum of two eigenmodes. Each eigenmode can be decomposed into two components: one which is slowly varying and satisfies a homogenized equation, while the other is periodic across each elementary crystal cell and is highly oscillating. The slowly oscillating components of the eigenmodes satisfy a system of Dirac equations. Our results in this paper prove for the first time a near-zero effective refractive index near the Dirac points for the plane-wave envelopes of the Bloch eigenfunctions in a sub-wavelength metamaterial. They are illustrated by a variety of numerical examples. We also compare and contrast the behaviour of the Bloch eigenfunctions in the honeycomb crystal with that of their counterparts in a bubbly square crystal, near the corner of the Brillouin zone, where the maximum of the first Bloch eigenvalue is attained.

Estimating lateral and vertical resolution in receiver function data for shallow crust exploration

2019 ◽  
Vol 218 (3) ◽  
pp. 2045-2053 ◽  
Author(s):  
Senad Subašić ◽  
Nicola Piana Agostinetti ◽  
Christopher J Bean
Keyword(s):  
Fresnel Zone ◽  
Receiver Function ◽  
Function Analysis ◽  
Probability Distributions ◽  
Receiver Functions ◽  
Lateral Resolution ◽  
Vertical Resolution ◽  
Data Set ◽  
Velocity Inversion ◽  
Shallow Crust

SUMMARY In order to test the horizontal and vertical resolution of teleseismic receiver functions, we perform a complete receiver function analysis and inversion using data from the La Barge array. The La Barge Passive Seismic Experiment was a seismic deployment in western Wyoming, recording continuously between November 2008 and June 2009, with 55 instruments deployed 250 m apart—up to two orders of magnitude closer than in typical receiver function studies. We analyse each station separately. We calculate receiver functions and invert them using a Bayesian algorithm. The inversion results are in agreement with measurements from nearby wells, and from other studies using the same data set. The resulting posterior probability distributions (PPDs), obtained for each station, are compared to each other by computing the Bhattacharyya coefficients, which quantify the overlap between two PPDs. Our results indicate that (a) the lateral resolution of 8 Hz receiver functions is approximately equal to the width of their first Fresnel zone, (b) minimum investigable depth is about 400 m at 8 Hz, (c) lateral resolution depends on the local geology as expected and (d) velocity inversion in the shallow-crust can be resolved in the first few kilometres, even in case of dipping interfaces.

scholarly journals Low-cost fabrication of optical tissue phantoms for use in biomedical imaging

Heliyon ◽  
2020 ◽  
Vol 6 (3) ◽  
pp. e03602
Author(s):  
Lindokuhle Ntombela ◽  
Bamise Adeleye ◽  
Naven Chetty
Keyword(s):  
Biomedical Imaging ◽  
Low Cost ◽  
Tissue Phantoms

Lateral resolution of the electron microbeam analysis

1978 ◽  
Vol 36 (1) ◽  
pp. 542-543
Author(s):  
H.J. Dudek
Keyword(s):  
Quantitative Analysis ◽  
Depth Resolution ◽  
Lateral Resolution ◽  
Cylindrical Particle ◽  
Correction Procedure ◽  
X Ray ◽  
Element Concentrations ◽  
Microbeam Analysis ◽  
The Matrix

The chemical inhomogenities in modern materials such as fibers, phases and inclusions, often have diameters in the region of one micrometer. Using electron microbeam analysis for the determination of the element concentrations one has to know the smallest possible diameter of such regions for a given accuracy of the quantitative analysis.In th is paper the correction procedure for the quantitative electron microbeam analysis is extended to a spacial problem to determine the smallest possible measurements of a cylindrical particle P of high D (depth resolution) and diameter L (lateral resolution) embeded in a matrix M and which has to be analysed quantitative with the accuracy q. The mathematical accounts lead to the following form of the characteristic x-ray intens ity of the element i of a particle P embeded in the matrix M in relation to the intensity of a standard S

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