2d And 3d Acoustic Metamaterials Using Space Coil Design

2015 ◽  
Vol 1753 ◽  
Author(s):  
Santosh K. Maurya ◽  
Manu Sahay ◽  
Shobha Shukla ◽  
Sumit Saxena
Keyword(s):  
Acoustic Wave ◽  
Mass Density ◽  
3D Structure ◽  
Three Dimensional ◽  
Acoustic Metamaterials ◽  
Coil Design ◽  
Frequency Range ◽  
2D And 3D ◽  
Constitutive Parameters ◽  
Sub Wavelength

ABSTRACTVarious promising applications such as acoustic cloaking, sub-wavelength imaging, acoustic wave manipulation, transmission or reflection control etc. are feasible because of the ability of manipulating sounds and vibrations using artificially engineered “Acoustics meta-materials”. Recent works on space-coiling acoustic metamaterials show their extreme constitutive parameters like large refractive index, double negativity and zero mass density. Three dimensional structures have a wide application in sub-wavelength broadband acoustic wave suppression due to huge attenuation. Here we report the study of propagated and transmitted wave through 3D acoustic metamaterials structure using finite element method. Our simulations on 3D structure show a huge absorption/damping over few hundreds kilohertz frequency range.

Acoustical Scattering by Multilayer Spherical Objects Containing Electrorheological Fluid

2009 ◽  
Author(s):  
Liang-Wu Cai ◽  
Dacio K. Dacol ◽  
Gregory J. Orris ◽  
David C. Calvo ◽  
Michael Nicholas
Keyword(s):  
Acoustic Wave ◽  
Fundamental Problem ◽  
Fluid Layer ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Electrorheological Fluid ◽  
Acoustic Metamaterials ◽  
Spherical Object ◽  
Spherical Scatterer ◽  
Acoustic Media

Scattering is the most fundamental problem in the research on phononic crystals and acoustic metamaterials; and scattering in a three-dimensional space poses challenging issues; and yet, the most challenging of all, is the scattering by elastic objects since an acoustic wave splits into different types of waves, propagating at different speeds, when it enters an elastic object. In this paper, a unified formalism is developed to analyze the scattering of an acoustic wave by a multilayer spherical object that is made of a mixture of an arbitrary number of concentric layers of elastic and acoustic media. Using this formalism, acoustical scattering by a multilayer spherical scatterer encasing an electrorheological (ER) fluid layer in an underwater environment is studied. Numerical examples show that ER fluids can alter the scattering characteristics above the first resonant frequency, which itself can be tuned by the applied electric field.

scholarly journals Acoustic metamaterials: From local resonances to broad horizons

2016 ◽  
Vol 2 (2) ◽  
pp. e1501595 ◽  
Author(s):  
Guancong Ma ◽  
Ping Sheng
Keyword(s):  
Acoustic Wave ◽  
Mass Density ◽  
Constitutive Parameter ◽  
Acoustic Metamaterials ◽  
Resonant Structures ◽  
Wave Transport ◽  
Mechanical Metamaterials ◽  
Original Definition ◽  
Diverse Application ◽  
Recent Developments

Within a time span of 15 years, acoustic metamaterials have emerged from academic curiosity to become an active field driven by scientific discoveries and diverse application potentials. This review traces the development of acoustic metamaterials from the initial findings of mass density and bulk modulus frequency dispersions in locally resonant structures to the diverse functionalities afforded by the perspective of negative constitutive parameter values, and their implications for acoustic wave behaviors. We survey the more recent developments, which include compact phase manipulation structures, superabsorption, and actively controllable metamaterials as well as the new directions on acoustic wave transport in moving fluid, elastic, and mechanical metamaterials, graphene-inspired metamaterials, and structures whose characteristics are best delineated by non-Hermitian Hamiltonians. Many of the novel acoustic metamaterial structures have transcended the original definition of metamaterials as arising from the collective manifestations of constituent resonating units, but they continue to extend wave manipulation functionalities beyond those found in nature.

Simulation study of acoustic refraction wave manipulation based on sub-wavelength artificial periodic structure

2020 ◽  
pp. 2150082
Author(s):  
Shuai Tang ◽  
Jianning Han
Keyword(s):  
Acoustic Wave ◽  
Steel Plate ◽  
Three Dimensional ◽  
Unit Cell ◽  
Asymmetric Transmission ◽  
Plate Structures ◽  
Coding Method ◽  
Acoustic Focusing ◽  
Unit Cells ◽  
Sub Wavelength

We proposed a kind of unit cell composed of simple steel plate structures in this work. A variety of acoustic phenomena including anomalous refraction, asymmetric transmission, acoustic splitting and acoustic focusing were realized by coding the unit cells with different splicing modes. The transformation from plane acoustic wave to vortex acoustic wave was also realized by using the coding method of three-dimensional rotation. This work increased the functionality of the unit cell and provided a method for the design of sub-wavelength acoustic devices.

scholarly journals Overall dynamic properties of three-dimensional periodic elastic composites

2011 ◽  
Vol 468 (2137) ◽  
pp. 269-287 ◽  
Author(s):  
Ankit Srivastava ◽  
Sia Nemat-Nasser
Keyword(s):  
Effective Properties ◽  
Dynamic Properties ◽  
Mass Density ◽  
Three Dimensional ◽  
Linear Momentum ◽  
Three Dimensions ◽  
Theoretical Treatment ◽  
Periodic Composite ◽  
Constitutive Parameters ◽  
Elastic Composites

This article presents a method for the homogenization of three-dimensional periodic elastic composites. It allows for the evaluation of the averaged overall frequency-dependent dynamic material constitutive tensors relating the averaged dynamic field variable tensors of velocity, strain, stress and linear momentum. Although the form of the dynamic constitutive relation for three-dimensional elastodynamic wave propagation has been known, this is the first time that explicit calculations of the effective parameters (for three dimensions) are presented. We show that for three-dimensional periodic composites, the overall compliance (stiffness) tensor, as produced directly by our formulation, is Hermitian, regardless of whether the corresponding unit cell is geometrically or materially symmetric. Overall, mass density is shown to be a tensor and, like the overall compliance tensor, always Hermitian. The average strain and linear momentum tensors are, however, coupled, and the coupling tensors are shown to be each others' Hermitian transpose. Finally, we present a numerical example of a three-dimensional periodic composite composed of elastic cubes periodically distributed in an elastic matrix. The presented results corroborate the predictions of the theoretical treatment illustrating the frequency dependence of the constitutive parameters. We also show that the effective properties calculated in this paper satisfy the dispersion relation of the composite.

scholarly journals Design Analysis of High Frequency Linear Transformer with Ārtap Framework

2021 ◽  
Author(s):  
Tamás Orosz ◽  
Mariusz Stępień ◽  
Peter Poór
Keyword(s):  
High Frequency ◽  
Mass Density ◽  
Three Dimensional ◽  
Fem Analysis ◽  
Design Analysis ◽  
Leakage Inductance ◽  
Design Variables ◽  
Calculation Results ◽  
Transformer Design ◽  
2D And 3D

This paper presents the design and a design analysis of a coaxial, linear transformer. This is a novel high frequency transformer concept for energy conversion. The examined transformer was designed for 1 MHz nominal frequency. One of the main advantages of the proposed transformer design is its simple winding system. It contains only two coaxial copper tubes, which can be easily manufactured and modeled with high precision. One of the key design tasks is the minimization of the leakage inductance. The inductance of the straight coils depends on the ratio of the height and the diameter of the coil. Therefore, a three-dimensional FEM analysis is sufficient to calculate the optimal length of the linear transformer. The planar 2D model and the 3D model of the transformer are presented in this paper. The accuracy of the 2D and 3D calculation results were compared to each other and to the measurements to show the applicability of the planar 2D models. Moreover, the sensitivity of the losses and the leakage inductance with respect to the winding parameters is presented. The dependencies of the design variables on the performance parameters, such as the power mass density and the leakage inductance of this transformer concept were examined. It was shown that the value of the leakage inductance is a linear function of the ratio of the length and the diameter of the transformer windings.

Coordination Polymers Constructed from TCNQ2– Anions and Chelating Ligands

2014 ◽  
Vol 67 (12) ◽  
pp. 1871 ◽  
Author(s):  
Brendan F. Abrahams ◽  
Robert W. Elliott ◽  
Richard Robson
Keyword(s):  
Coordination Polymers ◽  
3D Structure ◽  
Three Dimensional ◽  
Binding Mode ◽  
Coordination Geometry ◽  
Chelating Ligands ◽  
Metal Centre ◽  
3D Network ◽  
2D And 3D ◽  
Dianionic Form

Coordination polymers containing tetracyanoquinodimethane (TCNQ) in its dianionic form, TCNQ–II, have been formed by combining the acid form of the dianion, TCNQH2, with divalent metal centres in the presence of chelating ligands such as 2,2′-bipyridine (bipy) and 1,10-phenanthroline (phen). When MnII or CdII is employed, two-dimensional (2D) corrugated sheet structures with the formula MII(TCNQ–II)L (M = Mn, Cd; L = bipy, phen) are obtained. In contrast, when CoII is used as the metal centre a complex three-dimensional (3D) structure of composition [CoII(TCNQ–II)(phen)] is formed. Despite the significant differences between the 2D and 3D network structures, the metal coordination geometry and the binding mode of the TCNQ dianion are very similar in all cases.

scholarly journals Band Gaps and Vibration Isolation of a Three-dimensional Metamaterial with a Star Structure

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3812 ◽  
Author(s):  
Heng Jiang ◽  
Mangong Zhang ◽  
Yu Liu ◽  
Dongliang Pei ◽  
Meng Chen ◽  
...  
Keyword(s):  
Band Gap ◽  
Vibration Isolation ◽  
Dynamic Properties ◽  
Structural Parameters ◽  
Mass Density ◽  
Three Dimensional ◽  
Low Frequency ◽  
Band Gaps ◽  
Acoustic Metamaterials ◽  
Star Structure

Elastic metamaterials have promising applications in wave control and vibration isolation, due to their extraordinary characteristics, e.g., negative Poisson ratio, band gaps, effective negative mass density and effective negative modulus. How to develop new functional metamaterials using a special structure has always been a hot topic in this field. In this study, a three-dimensional (3D) star structure is designed to construct metamaterials with both negative static and dynamic properties. The results show that the 3D star structure formed a wide band gap at lower frequency and had a negative Poisson’s ratio. Different from conventional acoustic metamaterials, the main physical mechanism behind the low-frequency band gap of the 3D star structure is the resonance mode formed by the bending deformation of each rib plate, which made it easier to achieve effective isolation of low-frequency elastic waves with a low mass density. In addition, many structural parameters of the 3D star structure can be modulated to effectively adjust the band gap frequency by changing the angle between the concave nodes and aspect ratio. This study provides a new way to design the 3D acoustic metamaterials and develop the lightweight vibration isolation devices.

Simulation of Fabry-Perot Resonance for 3D Printable Complex Holey Acoustic Metamaterials

2020 ◽  
Author(s):  
Sanjay Ravichandran ◽  
Xin Wu ◽  
Yutai Su ◽  
Jing Shi
Keyword(s):  
Resonance Condition ◽  
Simulation Method ◽  
Complex Structures ◽  
Sound Waves ◽  
Acoustic Metamaterials ◽  
Frequency Range ◽  
Acoustic Metamaterial ◽  
Fabry Perot ◽  
Audible Frequency ◽  
Sub Wavelength

Abstract An acoustic metamaterial is a kind of material that is artificially designed in such a way that it can manipulate, control and direct sound waves. To date, various designs for acoustic metamaterials in the imaging applications have been proposed. However, these designs are generally simple due to the restriction from conventional manufacturing methods. By taking advantage of the additive manufacturing (AM) techniques, many complex acoustic metamaterials could be realized. However, the research on the complex structures for imaging applications has been very limited. In this paper, various 3D printable holey structured metamaterials with only one aperture are proposed, and the application possibility for sub-wavelength acoustic imaging in the audible frequency range is investigated. By using numerical simulation method, the effect of transmission properties of incident evanescent waves is analyzed to see whether these waves can completely transmit through the metamaterial. The phenomenon of Fabry-Perot resonances (FPR) that occur inside the hole for five different aperture shapes which are air-filled is studied, and the possibility of operating in a broadband resonance condition for the five designs are analyzed. These results can also be used to obtain valuable information for realizing a broadband acoustic hyperlens, which is an emerging application of 3D printable acoustic metamaterials.

Density-based discrimination of protein and RNA in the ribosome

1992 ◽  
Vol 50 (1) ◽  
pp. 464-465
Author(s):  
Joachim Frank
Keyword(s):  
Transfer Function ◽  
Spatial Frequency ◽  
Three Dimensional ◽  
Wiener Filter ◽  
Dark Field Image ◽  
Dark Field ◽  
Frequency Range ◽  
Bright Field ◽  
Contrast Transfer Function ◽  
Pass Filter

Cryo-electron microscopy combined with single-particle reconstruction techniques has allowed us to form a three-dimensional image of the Escherichia coli ribosome.In the interior, we observe strong density variations which may be attributed to the difference in scattering density between ribosomal RNA (rRNA) and protein. This identification can only be tentative, and lacks quantitation at this stage, because of the nature of image formation by bright field phase contrast. Apart from limiting the resolution, the contrast transfer function acts as a high-pass filter which produces edge enhancement effects that can explain at least part of the observed variations. As a step toward a more quantitative analysis, it is necessary to correct the transfer function in the low-spatial-frequency range. Unfortunately, it is in that range where Fourier components unrelated to elastic bright-field imaging are found, and a Wiener-filter type restoration would lead to incorrect results. Depending upon the thickness of the ice layer, a varying contribution to the Fourier components in the low-spatial-frequency range originates from an “inelastic dark field” image. The only prospect to obtain quantitatively interpretable images (i.e., which would allow discrimination between rRNA and protein by application of a density threshold set to the average RNA scattering density may therefore lie in the use of energy-filtering microscopes.

Methods for three-dimensional reconstruction of cellular components within a thick section

1986 ◽  
Vol 44 ◽  
pp. 18-21
Author(s):  
J. Frank ◽  
B. F. McEwen ◽  
M. Radermacher ◽  
C. L. Rieder
Keyword(s):  
Tilt Angle ◽  
Tomographic Reconstruction ◽  
3D Structure ◽  
Three Dimensional ◽  
Thick Section ◽  
Three Dimensional Reconstruction ◽  
Axis Ratio ◽  
Dimensional Reconstruction ◽  
Cellular Components

The tomographic reconstruction from multiple projections of cellular components, within a thick section, offers a way of visualizing and quantifying their three-dimensional (3D) structure. However, asymmetric objects require as many views from the widest tilt range as possible; otherwise the reconstruction may be uninterpretable. Even if not for geometric obstructions, the increasing pathway of electrons, as the tilt angle is increased, poses the ultimate upper limitation to the projection range. With the maximum tilt angle being fixed, the only way to improve the faithfulness of the reconstruction is by changing the mode of the tilting from single-axis to conical; a point within the object projected with a tilt angle of 60° and a full 360° azimuthal range is then reconstructed as a slightly elliptic (axis ratio 1.2 : 1) sphere.

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