Search results for "Surface wave"
showing 10 items of 66 documents
Bloch surface waves engineering in one-dimensional photonic crystals with a chiral cap layer
2019
We investigate the localization properties of surface waves created at the interface between a truncated 1D photonic crystal and homogeneous medium in the presence of a chiral cap layer using the transfer matrix method. The numerical results show that the interface can support surface waves with both transverse electric and transverse magnetic polarizations. We demonstrate that the surface waves can be engineered by varying the chirality parameter of the cap layer, which plays an important role in controlling and localization of surface states. It is shown that the effect of a chirality parameter on surface waves with transverse electric polarization is more remarkable compared with surface…
Generation of narrowband antisymmetric lamb waves using a formed laser source in the ablative regime
2007
A formed laser source, using a four-element lenticular array, is used in the ablative regime to generate select, narrowband, acoustic plate waves. The arrangement of the array produces acoustical signals that have frequencies compatible with the response of the broadband capacitive air-coupled transducer used in this study. A simplified concept is presented to explain the effect of a line array source on the frequency content of acoustic waves. The analytical model for a point pulse surface displacement is derived from the point load solution to Lamb's problem. The point pulse displacement elements of a line array source are summed mathematically, taking into account all applicable propagat…
Design of a narrow-band filter based on the Brewster phenomenon for microwave applications
2017
A high-efficiency narrow-band filter based on a Dielectric Frequency-Selective Surface (DFSS) has been predicted theoretically for oblique plane-wave incidence. A DFSS showing total reflection at a frequency of 10.5 GHz, based on the Brewster phenomenon for TM polarization, has been designed with a single dielectric grating, showing extremely low-reflectance sidebands adjacent to the resonance peak. The angular and spectral response of the designed filter has been studied. In addition, dielectric ohmic losses have been accounted for in this structure. This work was supported by the Agencia Estatal de Investigación (AEI) and by the Unión Europea through the Fondo Europeo de Desarrollo Region…
PROPAGAZIONE DI ONDE DI RAYLEIGH LUNGO SUPERFICI CURVE: UNO STUDIO NUMERICO E SPERIMENTALE
2014
Il fenomeno della propagazione delle onde di superficie lungo confini rettilinei (superfici piane) è stato studiato adeguatamente. Tuttavia le indagini riguardanti la loro propagazione in superfici cilindriche sono limitate e risultano insufficienti ai fini di un loro utilizzo nelle tecniche d’ispezione non distruttive (NDE), nonostante possano essere di grande interesse per svariate applicazioni. E’ stato dimostrato sperimentalmente che l’onda superficiale subisce un cambiamento di fase durante la sua propagazione lungo una superficie cilindrica. Un approccio numerico è stato sviluppato per studiare questi effetti per diversi materiali, curvature e frequenze. I risultati numerici e sperime…
Pedagogical models of surface mechanical wave propagation in various materials
2004
We report on a teaching approach oriented to the understanding of some relevant concepts of wave propagation in solids. It is based on simple experiments involving the propagation of shock mechanical waves in solid slabs of various materials. Methods similar to the generation and propagation of seismic waves are adopted. Educational seismometers, interfaced with computers, are used to detect and visualize the shock waves and to analyse their propagation properties. A qualitative discussion of the results concerning the propagation and the attenuation of the waves allows us to draw basic conclusions about the response of the matter to solicitation impacts and their propagation.
Charge-Induced Deformation of the 4He Solid-Superfluid Interface
1984
The interface between solid and superfluid 4He has revealed unusual dynamic properties. Characteristic of this quantum system are the very high thermal conductivity of the superfluid phase, and an extremely small heat of fusion below temperatures of about 1 K. As a result, equilibrium at the solid-superfluid 4He interface is established quite rapidly, which gives rise, e.g., to melting — crystallization waves [1,2] — similar in appearance to surface waves on a free liquid surface — and to anomalous transmission of sound [3].
Design and analysis of a one-dimensional sea surface simulator using the sum-of-sinusoids principle
2015
Simulators for sea surface waves are useful for many practical applications, such as the construction of offshore structures and ocean surface animations. This paper studies three methods for the design of one-dimensional sea surface waves simulators with given wave spectra using the sum-of-sinusoids (SOS) principle. The wave spectrum provides insight into important statistical properties of the sea surface waves, such as the autocorrelation function (ACF) of the sea surface waves, significant wave height, and the moments of the spectrum. The sea surface simulator is designed by applying the concept of deterministic channel modelling on two main classical wave spectra, namely the Pierson-Mo…
Surface waves on cylindrical solids: numerical and experimental study.
2013
The use of Rayleigh waves enables the solution of several important inspection problems. Propagation of surface waves along straight boundaries has been properly studied but investigations about their propagation on cylindrical surfaces are not sufficient, despite they can be still of interest for NDE applications. It has been proved experimentally that a surface wave pulse suffers a phase shift during its propagation along a cylindrical surface. A numerical approach has been developed to efficiently study these effects for different materials, curvatures and frequencies. This study can help the scientific community to better understand the phenomenon, quite complex and not yet fully explor…
Cylindrical surface waveguide modes using a surface impedance dyadic method
1987
The fields and characteristic parameters of nonradiating modes of a dielectric-coated wire with an intervening airgap are derived using a surface impedance dyadic method. This method shows several advantages and provides a straightforward method for working out the characteristic equation, cutoff conditions, far-from-cutoff conditions and field coefficients. Important results about the hybrid nature of these modes are shown, and some of them are common to any cylindrical surface waveguide.
Back-scattering of whispering-gallery-modes resonances of cylindrical microcavities: Refractometric applications
2009
Whispering-gallery modes (WGM) resonances of microcapillaries are directly compatible with microfluidic systems and have demonstrated its suitability for refractometric applications [1]. Microcapillaries with a submicrometric wall exhibit very large wavelength shifts as a function of the refractive index of the liquids that fill the inside of the capillary [2]. The spatial separation between the surface where the total internal reflection takes place (the outer surface) and the sensing surface (the inner surface) where the wave interacts with the analyte is a unique property that can be exploited to deal with analytes with a refractive index higher than that of the capillary [2].