Solvability of Singular Equations of Peridynamics on Two-Dimensional Periodic Structures

2021 ◽  
Author(s):  
Shavkat Alimov ◽  
Asal Yuldasheva
Keyword(s):  
Periodic Structures ◽  
Two Dimensional ◽  
Singular Equations

scholarly journals Two-dimensional photonic crystals increasing vertical light emission from Si nanocrystal-rich thin layers

2018 ◽  
Vol 9 ◽  
pp. 2287-2296
Author(s):  
Lukáš Ondič ◽  
Marian Varga ◽  
Ivan Pelant ◽  
Alexander Kromka ◽  
Karel Hruška ◽  
...  
Keyword(s):  
Photonic Crystals ◽  
Light Emission ◽  
Periodic Structures ◽  
Normal Direction ◽  
Thin Layers ◽  
Two Dimensional ◽  
Lattice Constants ◽  
Leaky Modes ◽  
Si Nanocrystals ◽  
Si Nanocrystal

We have fabricated two-dimensional photonic crystals (PhCs) on the surface of Si nanocrystal-rich SiO2 layers with the goal to maximize the photoluminescence extraction efficiency in the normal direction. The fabricated periodic structures consist of columns ordered into square and hexagonal pattern with lattice constants computed such that the red photoluminescence of Si nanocrystals (SiNCs) could couple to leaky modes of the PhCs and could be efficiently extracted to surrounding air. Samples having different lattice constants and heights of columns were investigated in order to find the configuration with the best performance. Spectral overlap of the leaky modes with the luminescence spectrum of SiNCs was verified experimentally by measuring photonic band diagrams of the leaky modes employing angle-resolved spectroscopy and also theoretically by computing the reflectance spectra. The extraction enhancement within different spatial angles was evaluated by means of micro-photoluminescence spectroscopy. More than 18-fold extraction enhancement was achieved for light propagating in the normal direction and up to 22% increase in overall intensity was obtained at the spatial collection angle of 14°.

Wave Propagation in Two-Dimensional Nonlinear Periodic Lattices

2009 ◽  
Author(s):  
Raj K. Narisetti ◽  
Massimo Ruzzene ◽  
Michael J. Leamy
Keyword(s):  
Wave Propagation ◽  
Linear Models ◽  
Periodic Structures ◽  
Harmonic Wave ◽  
Excitation Amplitude ◽  
Pass Band ◽  
Perturbation Approach ◽  
Nonlinear Stiffness ◽  
Two Dimensional ◽  
Low Amplitude

This paper investigates wave propagation in two-dimensional nonlinear periodic structures subject to point harmonic forcing. The infinite lattice is modeled as a springmass system consisting of linear and cubic-nonlinear stiffness. The effects of nonlinearity on harmonic wave propagation are analytically predicted using a novel perturbation approach. Response is characterized by group velocity contours (derived from phase-constant contours) functionally dependent on excitation amplitude and the nonlinear stiffness coefficients. Within the pass band there is a frequency band termed the “caustic band” where the response is characterized by the appearance of low amplitude regions or “dead zones.” For a two-dimensional lattice having asymmetric nonlinearity, it is shown that these caustic bands are dependent on the excitation amplitude, unlike in corresponding linear models. The analytical predictions obtained are verified via comparisons to responses generated using a time-domain simulation of a finite two-dimensional nonlinear lattice. Lastly, the study demonstrates amplitude-dependent wave beaming in two-dimensional nonlinear periodic structures.

Powerful surface-wave oscillators with two-dimensional periodic structures

2012 ◽  
Vol 100 (14) ◽  
pp. 143510 ◽  
Author(s):  
N. S. Ginzburg ◽  
A. M. Malkin ◽  
A. S. Sergeev ◽  
V. Yu. Zaslavsky
Keyword(s):  
Surface Wave ◽  
Periodic Structures ◽  
Two Dimensional

Wave Beaming in Nanostructured Materials With Engineered Defects

2008 ◽  
Author(s):  
Mahmoud I. Hussein ◽  
Michael J. Leamy ◽  
Massimo Ruzzene
Keyword(s):  
Periodic Structures ◽  
Graphene Nanosheets ◽  
Low Frequency ◽  
Two Dimensional ◽  
Propagation Characteristics ◽  
Nanoscale Material ◽  
Material Systems ◽  
Acoustic Focusing ◽  
Acoustic Waveguides ◽  
Draft Paper

Recent advances in the fabrication of nanoscale material systems have made it possible to alter precisely the atomic structure in ways that enhance the properties and allow for certain functions to be realized. This work is concerned with two-dimensional periodic structures and emphasizes the effects of intentional defects on their wave propagation characteristics. In this draft paper, investigations are limited to a two-dimensional spring-mass lattice, composed of “super-cells” where mass inclusions are added to alter band-gap properties, as well as low frequency directionality. The presented results will then be extended to two-dimensional nanostructures, such as graphene nanosheets, in order to investigate their application as nanoscale acoustic waveguides, where engineered defects, uniformally distributed across the entire sheet, are introduced by design with the objective of rendering the medium anisotropic. Such anisoptropy leads to acoustic directionality, which can be exploited for waveguiding or acoustic-focusing purposes.

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