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Showing papers on "Reflection (physics) published in 2017"


Journal ArticleDOI
TL;DR: A new paradigm for the design of perfect reflectors based on energy surface channeling is introduced, offering a versatile design method applicable to other scenarios, such as focusing reflectors, surface wave manipulations, or metasurface holograms, extendable to other frequencies.
Abstract: The use of the generalized Snell's law opens wide possibilities for the manipulation of transmitted and reflected wavefronts. However, known structures designed to shape reflection wavefronts suffer from significant parasitic reflections in undesired directions. We explore the limitations of the existing solutions for the design of passive planar reflectors and demonstrate that strongly nonlocal response is required for perfect performance. A new paradigm for the design of perfect reflectors based on energy surface channeling is introduced. We realize and experimentally verify a perfect design of an anomalously reflective surface using an array of rectangular metal patches backed by a metallic plate. This conceptually new mechanism for wavefront manipulation allows the design of thin perfect reflectors, offering a versatile design method applicable to other scenarios, such as focusing reflectors, surface wave manipulations, or metasurface holograms, extendable to other frequencies.

303 citations


Book
29 Oct 2017
TL;DR: In this article, the transmission/reflection and short-circuit line methods for measuring complex permittivity were examined and robust algorithms that eliminate the illbehaved nature of the commonly used transmission/reflect method a t frequencies corresponding to integral multiples of one-half wavelength in the sample are presented.
Abstract: The transmission/reflection and short-circuit line methods for measuring complex permittivity are examined. Equations for permittivity are developed from first principles. New robust algorithms that eliminate the illbehaved nature of the commonly used transmission/reflection method a t frequencies corresponding to integral multiples of one-half wavelength in the sample are presented. These allow measurements to be made on samples of any length. An uncertainty analysis is presented which yields estimates of the errors incurred due to the uncertainty in scattering parameters, length measurement and reference plane position. The equations derived here indicate that the minimum uncertainty for transmission/reflection measurements of nonmagnetic materials occurs a t integral multiples of one-half wavelength in the material. In addition, new equations for determining complex permittivity independent of reference plane position and sample length are derived. New equations are derived for permittivity determination using the short-circuit line allow positioning the sample arbitrarily in the sample holder.

183 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present a fully comprehensive implementation of wave generation and active wave absorption for second-order longcrested monochromatic and random waves in a WCSPH-based (Weakly Compressible Smoothed Particle Hydrodynamics) model.

171 citations


Journal ArticleDOI
TL;DR: In this article, three ultrathin devices with multiple polarization-dependent functionalities and very high efficiencies on both transmission and reflection sides were designed to manipulate EM waves in either mode, which significantly expand the capabilities of metasurfaces for more demanding and diverse applications.
Abstract: Metasurfaces offer great opportunities to control light, but so far most ``metadevices'' work either in pure reflection or pure transmission mode, leaving half of electromagnetic (EM) space untapped. Thus the authors design meta-atoms with polarization-dependent transmission and reflection properties, to efficiently manipulate EM waves in either mode. They fabricate three ultrathin devices with multiple polarization-dependent functionalities and very high efficiencies on both transmission and reflection sides. These findings significantly expand the capabilities of metasurfaces for more demanding and diverse applications.

169 citations


Journal ArticleDOI
TL;DR: In this paper, a generalized 4×4 matrix formalism for the description of light propagation in birefringent stratified media is presented. But unlike previous work, this algorithm is capable of treating arbitrarily anisotropic or isotropic, absorbing or non-absorbing materials and is free of discontinuous solutions.
Abstract: We present a generalized 4×4 matrix formalism for the description of light propagation in birefringent stratified media. In contrast to previous work, our algorithm is capable of treating arbitrarily anisotropic or isotropic, absorbing or non-absorbing materials and is free of discontinuous solutions. We calculate the reflection and transmission coefficients and derive equations for the electric field distribution for any number of layers. The algorithm is easily comprehensible and can be straightforwardly implemented in a computer program. To demonstrate the capabilities of the approach, we calculate the reflectivities, electric field distributions, and dispersion curves for surface phonon polaritons excited in the Otto geometry for selected model systems, where we observe several distinct phenomena ranging from critical coupling to mode splitting, and surface phonon polaritons in hyperbolic media.

132 citations


Proceedings ArticleDOI
21 Jul 2017
TL;DR: This work proposes a novel approach to suppress reflections, based on a Laplacian data fidelity term and an l-zero gradient sparsity term imposed on the output, which performs better than the state-of-the-art reflection removal techniques.
Abstract: Reflections are a common artifact in images taken through glass windows. Automatically removing the reflection artifacts after the picture is taken is an ill-posed problem. Attempts to solve this problem using optimization schemes therefore rely on various prior assumptions from the physical world. Instead of removing reflections from a single image, which has met with limited success so far, we propose a novel approach to suppress reflections. It is based on a Laplacian data fidelity term and an l-zero gradient sparsity term imposed on the output. With experiments on artificial and real-world images we show that our reflection suppression method performs better than the state-of-the-art reflection removal techniques.

122 citations


Journal ArticleDOI
TL;DR: In this article, the authors present a synthesis method of acoustic metasurfaces for anomalous reflection and transmission that overcomes the fundamental limitations of conventional designs, allowing full control of acoustic energy flow.
Abstract: Manipulation of acoustic wave fronts by thin and planar devices, known as metasurfaces, has been extensively studied, in view of many important applications. Reflective and refractive metasurfaces are designed using the generalized reflection and Snell's laws, which tell that local phase shifts at the metasurface supply extra momentum to the wave, presumably allowing arbitrary control of reflected or transmitted waves. However, as has been recently shown for the electromagnetic counterpart, conventional metasurfaces based on the generalized laws of reflection and refraction have important drawbacks in terms of power efficiency. This work presents a new synthesis method of acoustic metasurfaces for anomalous reflection and transmission that overcomes the fundamental limitations of conventional designs, allowing full control of acoustic energy flow. The results show that different mechanisms are necessary in the reflection and transmission scenarios for ensuring perfect performance. Metasurfaces for anomalous reflection require nonlocal response, which allows energy channeling along the metasurface. On the other hand, for perfect manipulation of anomalously transmitted waves, local and nonsymmetric response is required. These conclusions are interpreted through appropriate surface impedance models which are used to find possible physical implementations of perfect metasurfaces in each scenario. We hope that this advance in the design of acoustic metasurfaces opens new avenues not only for perfect anomalous reflection and transmission but also for realizing more complex functionalities, such as focusing, self-bending, or vortex generation.

118 citations



Journal ArticleDOI
TL;DR: In this paper, a gradient chiral metamirror tailored for spin-selective anomalous reflection based on the theory of Pancharatnam-berry phase is presented.
Abstract: Metasurfaces, the phase-engineered quasi-2D interfaces, have attracted intensive interest due to their great capabilities in manipulating the reflection, refraction and transmission of electromagnetic waves. Here, we demonstrate the design and realization of a gradient chiral metamirror tailored for spin-selective anomalous reflection based on the theory of Pancharatnam-Berry phase. Asymmetric split ring resonators are employed as the basic meta-atoms for strong circular dichroism. Dispersionless phase discontinuities are achieved by adjusting the orientation of the meta-atoms, and spin-dependent absorption is realized by introducing a chiral resonance. Theoretical results predict both broadband beam deflection and spin-selective absorption for circularly polarized waves in a designer metamirror. Experimental verification of this bifunctional performance is implemented at microwave frequencies and the measured results agree well with the simulation ones. Such chiral metamirrors could pave an avenue towards spin-selective modulation of the wavefront and might find promising applications in planar electromagnetic devices.

91 citations


Journal ArticleDOI
TL;DR: In this paper, a new type of labyrinthine acoustic metamaterials (LAMMs) with hybrid dispersion characteristics by exploiting spider web-structured configurations is proposed. But the proposed design approach consists in adding a square surrounding frame to sectorial circular-shaped labyrinthine channels described in previous publications.
Abstract: Attenuating low-frequency sound remains a challenge, despite many advances in this field. Recently-developed acoustic metamaterials are characterized by unusual wave manipulation abilities that make them ideal candidates for efficient subwavelength sound control. In particular, labyrinthine acoustic metamaterials exhibit extremely high wave reflectivity, conical dispersion, and multiple artificial resonant modes originating from the specifically-designed topological architectures. These features enable broadband sound attenuation, negative refraction, acoustic cloaking and other peculiar effects. However, hybrid and/or tunable metamaterial performance implying enhanced wave reflection and simultaneous presence of conical dispersion at desired frequencies has not been reported so far. In this paper, we propose a new type of labyrinthine acoustic metamaterials (LAMMs) with hybrid dispersion characteristics by exploiting spider web-structured configurations. The developed design approach consists in adding a square surrounding frame to sectorial circular-shaped labyrinthine channels described in previous publications (e.g. (11)). Despite its simplicity, this approach provides tunability in the metamaterial functionality, such as the activation/elimination of subwavelength band gaps and negative group-velocity modes by increasing/decreasing the edge cavity dimensions. Since these cavities can be treated as extensions of variable-width internal channels, it becomes possible to exploit geometrical features, such as channel width, to shift the band gap position and size to desired frequencies. Time transient simulations demonstrate the effectiveness of the proposed metastructures for wave manipulation in terms of transmission or reflection coefficients, amplitude attenuation and time delay at subwavelength frequencies. The obtained results can be important for practical applications of LAMMs such as lightweight acoustic barriers with enhanced broadband wave-reflecting performances.

88 citations


Journal ArticleDOI
TL;DR: In this paper, the authors proposed a beam steering method based on bianisotropic particles in a periodic array of isotropic dielectric rods, which can offer asymmetrical scattering of normally incident beams with unitary efficiency.
Abstract: Gradient metasurfaces have been extensively used in the past few years for advanced wave manipulation over a thin surface. These metasurfaces have been mostly designed based on the generalized laws of reflection and refraction. However, it was recently revealed that metasurfaces based on this approach tend to suffer from inefficiencies and complex design requirements. We have recently proposed a different approach to the problem of efficient beam steering using a surface, based on bianisotropic particles in a periodic array. Here, we show highly efficient reflective metasurfaces formed by pairs of isotropic dielectric rods, which can offer asymmetrical scattering of normally incident beams with unitary efficiency. Our theory shows that moderately broadband anomalous reflection can be achieved with suitably designed periodic arrays of isotropic nanoparticles. We also demonstrate practical designs using ${\mathrm{TiO}}_{2}$ cylindrical nanorods to deflect normally incident light toward a desired direction. The proposed structures may pave the way to a broader range of light management opportunities, with applications in energy harvesting, signaling, and communications.

Journal ArticleDOI
TL;DR: In this paper, the authors review progress made in the past decade toward understanding the different processes that can lead to turbulence during the generation, propagation, and reflection of internal waves and how these processes affect mixing.
Abstract: Internal gravity waves are a key process linking the large-scale mechanical forcing of the oceans to small-scale turbulence and mixing. In this review, we focus on internal waves generated by barotropic tidal flow over topography. We review progress made in the past decade toward understanding the different processes that can lead to turbulence during the generation, propagation, and reflection of internal waves and how these processes affect mixing. We consider different modeling strategies and new tools that have been developed. Simulation results, the wealth of observational material collected during large-scale experiments, and new laboratory data reveal how the cascade of energy from tidal flow to turbulence occurs through a host of nonlinear processes, including intensified boundary flows, wave breaking, wave-wave interactions, and the instability of high-mode internal wave beams. The roles of various nondimensional parameters involving the ocean state, roughness geometry, and tidal forcing are desc...

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate wide-angle, broadband and efficient reflection holography by utilizing coupled dipole-patch nano-antenna cells to impose an arbitrary phase profile on of the reflected light.
Abstract: We demonstrate wide-angle, broadband and efficient reflection holography by utilizing coupled dipole-patch nano-antenna cells to impose an arbitrary phase profile on of the reflected light. High fidelity images were projected at angles of 450 and 200 with respect to the impinging light with efficiencies ranging between 40%-50% over an optical bandwidth exceeding 180nm. Excellent agreement with the theoretical predictions was found at a wide spectral range. The demonstration of such reflectarrays opens new avenues towards expanding the limits of large angle holography.

Journal ArticleDOI
TL;DR: In this paper, a 3D transient mathematical model of chemically reacting gas mixture flows incorporating hydrogen air mixtures was developed to study detonation initiation due to focusing of a shock wave reflected inside a cone.

Proceedings ArticleDOI
01 Jul 2017
TL;DR: This paper proposes a low-rank matrix completion algorithm to remove reflection artifacts automatically from multiple glass images taken at slightly different camera locations, and reconstructs an original transmission image using the resulting optimal gradient map.
Abstract: The images taken through glass often capture a target transmitted scene as well as undesired reflected scenes. In this paper, we propose a low-rank matrix completion algorithm to remove reflection artifacts automatically from multiple glass images taken at slightly different camera locations. We assume that the transmitted scenes are more dominant than the reflected scenes in typical glass images. We first warp the multiple glass images to a reference image, where the gradients are consistent in the transmission images while the gradients are varying across the reflection images. Based on this observation, we compute a gradient reliability such that the pixels belonging to the salient edges of the transmission image are assigned high reliability. Then we suppress the gradients of the reflection images and recover the gradients of the transmission images only, by solving a low-rank matrix completion problem in gradient domain. We reconstruct an original transmission image using the resulting optimal gradient map. Experimental results show that the proposed algorithm removes the reflection artifacts from glass images faithfully and outperforms the existing algorithms on typical glass images.

Journal ArticleDOI
Huanhuan Yang1, Xibi Chen1, Fan Yang1, Shenheng Xu1, Xiangyu Cao, Maokun Li1, Jun Gao 
TL;DR: In this paper, two amplitude-controllable reflectarray elements with different phase tuning techniques are presented, where the reflection amplitude and phase can be controlled separately, and a full 360° phase range is achieved with a dynamic amplitude control over 10 dB.
Abstract: Conventional reflectarray elements have only phase-control property, and this letter presents novel reflectarray elements with both amplitude and phase control using proper resistor loading. Two amplitude-controllable reflectarray elements are presented with different phase tuning techniques. It is shown that the reflection amplitude for each element only depends on the resistor value, while the reflection phase only depends on the element size or the element rotation angle. Thus, the reflection amplitude and phase can be controlled separately, and a full 360° phase range is achieved with a dynamic amplitude control over 10 dB. Both elements are fabricated and measured using a customized waveguide. The measured results agree well with the simulations, which verify the effectiveness of the proposed designs.

Journal ArticleDOI
TL;DR: A simple scheme for the realization of propagation management of light beams by introducing a double-barrier potential into the FSE and some unique properties, including strong self-healing ability, high capacity of resisting disturbance, beam reshaping, and Goos-Hänchen-like shift are revealed.
Abstract: Generalization of Fractional Schrodinger equation (FSE) into optics is fundamentally important, since optics usually provides a fertile ground where FSE-related phenomena can be effectively observed. Beam propagation management is a topic of considerable interest in the field of optics. Here, we put forward a simple scheme for the realization of propagation management of light beams by introducing a double-barrier potential into the FSE. Transmission, partial transmission/reflection, and total reflection of light fields can be controlled by varying the potential depth. Oblique input beams with arbitrary distributions obey the same propagation dynamics. Some unique properties, including strong self-healing ability, high capacity of resisting disturbance, beam reshaping, and Goos-Hanchen-like shift are revealed. Theoretical analysis results are qualitatively in agreements with the numerical findings. This work opens up new possibilities for beam management and can be generalized into other fields involving fractional effects.

Journal ArticleDOI
TL;DR: In this paper, a Monte Carlo approach is used to estimate the sky-average brightness temperature from the 21-cm line emitted during the Epoch of Reionization (EoR) in the redshift range 14 and z & 6.
Abstract: The EDGES experiment strives to detect the the sky-average brightness temperature from the 21-cm line emitted during the Epoch of Reionization (EoR) in the redshift range 14 & z & 6. To probe this signal, EDGES conducts single-antenna measurements in the frequency range 100- 200 MHz from the Murchison Radioastronomy Observatory in Western Australia. In this paper we describe the current strategy for calibration of the EDGES instrument and, in particular, of its receiver. The calibration involves measuring accurately modeled passive and active noise sources connected to the receiver input in place of the antenna. We model relevant uncertainties that arise during receiver calibration and propagate them to the calibrated antenna temperature using a Monte Carlo approach. Calibration effects are isolated by assuming that the sky foregrounds and the antenna beam are perfectly known. We find that if five polynomial terms are used to account for calibration systematics, most of the calibration measurements conducted for EDGES produce residuals of 1 mK or less at 95% confidence. The largest residuals are due to uncertainty in the antenna and receiver reflection coefficients at levels below 20 mK when observing a low-foreground region. These residuals could be reduced by restricting the band to a smaller frequency range motivated by tighter reionization priors. They could also be reduced by 1) improving the accuracy in reflection measurements, especially their phase, 2) decreasing the changes with frequency of the antenna reflection phase, and 3) improving the impedance match at the antenna-receiver interface. Subject headings: early universe — cosmology: observations — methods: laboratory — methods: statistical

Journal ArticleDOI
TL;DR: In this paper, the authors developed a full solution for water wave reflection by a partially perforated caisson breakwater with a rubble mound foundation using multi-domain BEM (boundary element method).
Abstract: This study develops a full solution for water wave reflection by a partially perforated caisson breakwater with a rubble mound foundation using multi-domain BEM (boundary element method). Regular and irregular waves are both considered. A quadratic pressure drop condition on caisson perforated wall is adopted, and direct iterative calculations are performed. Due to the use of quadratic pressure drop condition, the effect of wave height on the energy dissipation by the perforated wall is well considered. This study also develops an iterative analytical solution for wave reflection by a partially perforated caisson breakwater on flat bottom using matched eigenfunction expansion method. The reflection coefficients calculated by the multi-domain BEM solution and the analytical solution are in excellent agreement. The present calculated results also agree reasonably well with experimental data from different literatures. Suitable values of discharge coefficient and blockage coefficient in the quadratic pressure drop condition are recommended for perforated caissons. The effects of the wave steepness, the blockage coefficient of perforated wall and the relative wave chamber width on the reflection coefficient are clarified. The present BEM solution is simple and reliable. It may be used for predicting the reflection coefficients of perforated caisson breakwaters in preliminary engineering design.

Journal ArticleDOI
TL;DR: This work illustrates this for a 1D reflection response in which the primary reflection of a specific interface is missing and it is possible to use multiples in Marchenko imaging with an “event-by-event” deconvolution imaging approach.
Abstract: Marchenko imaging can produce seismic reflection images in which artifacts related to multiples are suppressed. However, in state-of-the-art implementations, multiples do not contribute to the imaged reflectors. With an “event-by-event” deconvolution imaging approach, it is possible to use multiples in Marchenko imaging. We illustrate this for a 1D reflection response in which the primary reflection of a specific interface is missing.

Journal ArticleDOI
TL;DR: These sound diffusers are rigidly backed slotted panels, with each slit being loaded by an array of Helmholtz resonators, to present deep-subwavelength diffusing surfaces based on acoustic metamaterials, namely metadiffusers.
Abstract: We present deep-subwavelength diffusing surfaces based on acoustic metamaterials, namely metadiffusers. These sound diffusers are rigidly backed slotted panels, with each slit being loaded by an array of Helmholtz resonators. Strong dispersion is produced in the slits and slow sound conditions are induced. Thus, the effective thickness of the panel is lengthened introducing its quarter wavelength resonance in the deep-subwavelength regime. By tuning the geometry of the metamaterial, the reflection coefficient of the panel can be tailored to obtain either a custom reflection phase, moderate or even perfect absorption. Using these concepts, we present ultra-thin diffusers where the geometry of the metadiffuser has been tuned to obtain surfaces with spatially dependent reflection coefficients having uniform magnitude Fourier transforms. Various designs are presented where, quadratic residue, primitive root and ternary sequence diffusers are mimicked by metadiffusers whose thickness are 1/46 to 1/20 times the design wavelength, i.e., between about a twentieth and a tenth of the thickness of traditional designs. Finally, a broadband metadiffuser panel of 3 cm thick was designed using optimization methods for frequencies ranging from 250 Hz to 2 kHz.

Journal ArticleDOI
TL;DR: In this article, the authors theoretically investigate the propagation of torsional Alfvén waves in magnetic flux tubes expanding from the photosphere up to the low corona and explore the reflection, transmission, and dissipation of wave energy.
Abstract: It has been proposed that Alfvén waves play an important role in the energy propagation through the solar atmospheric plasma and its heating. Here we theoretically investigate the propagation of torsional Alfvén waves in magnetic flux tubes expanding from the photosphere up to the low corona and explore the reflection, transmission, and dissipation of wave energy. We use a realistic variation of the plasma properties and the magnetic field strength with height. Dissipation by ion–neutral collisions in the chromosphere is included using a multifluid partially ionized plasma model. Considering the stationary state, we assume that the waves are driven below the photosphere and propagate to the corona, while they are partially reflected and damped in the chromosphere and transition region. The results reveal the existence of three different propagation regimes depending on the wave frequency: low frequencies are reflected back to the photosphere, intermediate frequencies are transmitted to the corona, and high frequencies are completely damped in the chromosphere. The frequency of maximum transmissivity depends on the magnetic field expansion rate and the atmospheric model, but is typically in the range of 0.04–0.3Hz. Magnetic field expansion favors the transmission of waves to the corona and lowers the reflectivity of the chromosphere and transition region compared to the case with a straight field. As a consequence, the chromospheric heating due to ion–neutral dissipation systematically decreases when the expansion rate of the magnetic flux tube increases.

Journal ArticleDOI
TL;DR: It is numerically demonstrated that a transient blast‐induced elastic wave with broadband frequencies can be almost completely mitigated or absorbed at a subwavelength scale.

Journal ArticleDOI
TL;DR: In this paper, a method to counteract wave diffusion and to focus multiples-cattered waves to the deeply embedded target is presented, where the authors experimentally inject light to the reflection eigenchannels of a specific flight time where most of the multiple-scattered waves have interacted with the target object.
Abstract: The efficient delivery of light energy is a prerequisite for non-invasive imaging and stimulating of target objects embedded deep within a scattering medium However, injected waves experience random diffusion by multiple light scattering, and only a small fraction reaches the target object Here we present a method to counteract wave diffusion and to focus multiplescattered waves to the deeply embedded target To realize this, we experimentally inject light to the reflection eigenchannels of a specific flight time where most of the multiple-scattered waves have interacted with the target object and maximize the intensity of the returning multiple-scattered waves at the selected time For targets that are too deep to be visible by optical imaging, we demonstrated a more than 10-fold enhancement in light energy delivery in comparison with ordinary wave diffusion cases This work will lay a foundation for enhancing the working depth of imaging, sensing, and light stimulation

Journal ArticleDOI
TL;DR: In this paper, a simple method to form approximately unipolar halfcycle optical pulses via reflection of a single-cycle optical pulse from a thin flat metallic or dielectric layer was proposed.
Abstract: We propose a strikingly simple method to form approximately unipolar half-cycle optical pulses via reflection of a single-cycle optical pulse from a thin flat metallic or dielectric layer. Unipolar pulses in reflection arise due to specifics of one-dimensional pulse propagation. Namely, we show that the field emitted by the layer is proportional to the velocity of the oscillating charges in the medium, instead of their acceleration. Besides, the oscillation velocity of the charges can be forced to keep a constant sign throughout the pulse duration. That is, reflection of ultrashort pulses from broad-area layers with nanometer-scale thickness can be very different from the common reflection in the case of longer pulses and thicker layers. This suggests a possibility of unusual transformations of few-cycle light pulses in completely linear optical systems.

Journal ArticleDOI
TL;DR: Calculations show that by optimizing the thickness of the Be layer it should be possible to increase the reflection coefficient by another 0.5-1%.
Abstract: The effect of Be layers on the reflection coefficients of Mo/Be/Si multilayer mirrors in the extreme ultraviolet (EUV) region is reported. Samples were studied using laboratory and synchrotron based reflectometry, and high-resolution transmission electron microscopy. The samples under study have reflection coefficients above 71% at 13.5 nm and more than 72% at 12.9 nm in a near normal incidence mode. Calculations show that by optimizing the thickness of the Be layer it should be possible to increase the reflection coefficient by another 0.5–1%. These results are of considerable interest for EUV lithography.

Journal ArticleDOI
TL;DR: In this paper, a phase-resolving model is rigorously applied to model conditions from the prototype-scale BARDEXII experiment in order to examine and assess the influence of swash-based reflection on surf zone hydrodynamics at both the individual wave and time-averaged timescales.

Journal ArticleDOI
TL;DR: In this paper, the reflection and transmission of the plane wave propagating in three-dimensional multilayered magneto-electro-elastic (MEE) plates which are immersed in liquid are investigated.

Journal ArticleDOI
TL;DR: In this article, the wave fields reflected and transmitted by a thin floating plastic plate are reported for regular incident waves over a range of incident periods (producing wavelengths comparable to the plate length) and steepnesses (ranging from mild to storm-like).

Journal ArticleDOI
TL;DR: In this paper, the authors report the experimental realization of acoustic coherent perfect absorption (CPA) of four symmetric scatterers of very different structures, and demonstrate that these scatters could potentially be sensitive devices to detect the small differences between two nearly equal incident waves.
Abstract: We report the experimental realization of acoustic coherent perfect absorption (CPA) of four symmetric scatterers of very different structures. The only conditions necessary for these scatterers to exhibit CPA are that both the reflection and transmission amplitudes of the scatterers are 0.5 under one incident wave, and there are two collinear and counter-propagating incident waves with appropriate relative amplitude and phase. Nearly 1000 times in the modulation of output power has been demonstrated by changing the relative phase of the incident waves over 180°. We further demonstrate that these scatterers could potentially be sensitive devices to detect the small differences between two nearly equal incident waves. A 27% change in the strength of the scattering wave has been demonstrated for every degree of phase deviation from the optimum condition between the incident waves.