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Wave Propagation of Porous Nanoshells
摘要： This study aims at investigating the wave propagation of porous nanoshells. The Bi-Helmholtz non-local strain gradient theory is employed in conjunction with a higher-order shear deformation shell theory, in order to include the size-dependent effects. The nanoshells are made of a porous functionally graded material (P-FGM), whose properties vary continuously along the thickness direction. A variational approach is here applied to handle the governing equations of the problem, which are solved analytically to compute the wave frequencies and phase velocities as function of the wave numbers. The sensitivity of the wave response is analyzed for a varying porosity volume fraction, material properties, non-local parameters, strain gradient length scales, temperature, humidity, and wave numbers. Based on the results, it is verified that the size-dependence of the response is almost the same to the one of plates, beams and tubes.
关键词： doubly-curved nanoshell,wave propagation,higher-order shear deformation shell theory,porous materials,generalized non-local strain gradient theory
更新于2025-09-23 15:23:52
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Contrast of optical activity and rogue wave propagation in chiral materials
摘要： We report the contrast of optical activity and properties of nonparaxial optical rogue waves for the higher-order nonparaxial chiral nonlinear Schr?dinger (NLS) equation. The latter describes the propagation of ultrashort optical pulses in chiral optical fibers. Both first- and second-order rogue wave solutions are investigated analytically by the modified Darboux transformation (MDT) and numerically by one pseudo-spectral method. The interplay of chiral materials on rogue wave propagation is elucidated, and the results can be applied on optical communication and in others physical systems.
关键词： Chirality and optical activity,Chiral optical fibers,Rogue wave propagation,Chiral materials
更新于2025-09-23 15:23:52
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Effects of the microstructure and density profiles on wave propagation across an interface with material properties
摘要： The characterization of the interphase condition between two materials is current in mechanics. In general, its modeling is achieved by considering an interface with only purely elastic properties. In this paper, following previous works, also inertial interface properties are taken into account. For sufficiently low-frequency regime, we investigate two density profiles (affine and quadratic), for the interphase. Moreover, the interface and the interphase are placed between two solids with different characteristics. The first one is non-dispersive, while for the second one three cases are considered: (a) solid without microstructure, i.e., a Cauchy continuum, (b) solid with microstructure characterized by normal dispersion, i.e., a strain gradient continuum, and (c) by anomalous dispersion. The reflection coefficients are plotted for each case. These results are evaluated with respect to a benchmark finite elements simulation of the finite heterogeneous interphase, and the error is discussed. It is shown that the effects of microstructure can be appreciated at higher frequencies and that the proposed model results to be accurate.
关键词： Strain gradient,Reflection coefficient,Interface,Interphase,Density profiles,Wave propagation
更新于2025-09-23 15:23:52
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Numerical simulation on terahertz wave propagation in plasma channels
摘要： Terahertz (THz) wave generated by femtosecond laser ?lamentation can spatially constrained inside the plasma channels. Our simulation results show that this constraint to THz wave will gradually weaken with the increasing THz frequency. At the same time, results also indicate that the higher plasma density possesses the stronger constraint. In addition, the model ?eld radius and width of THz wave will become larger with the increasing plasma channel radius. Based on the simulation results we ?nd the changes of refractive index at THz wave play an important role on THz wave propagation in plasma channels.
关键词： Plasma channel,Waveguiding,Terahertz wave propagation
更新于2025-09-23 15:23:52
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Numerical and experimental investigation of damage severity estimation using Lamb wave–based imaging methods
摘要： In this article, estimation of crack size, shape, and orientation was investigated numerically and experimentally using Lamb waves. A hybrid global–local approach was used in conjunction with the imaging methods for the numerical simulation. The hybrid global–local approach allowed fast and efficient prediction of scattering wave signals for Lamb wave interaction with crack from various incident directions. The simulation results showed the directionality effect of the scattering wave signals and suggested an optimum transmitter–sensor configuration. Two imaging methods were used: one involves the synthetic time reversal concept and the other involves Gaussian distribution function. Both imaging methods show very good agreement during simulations. Experiments were designed and conducted based on the simulated results. A network of eight piezoelectric wafer active sensors was used to capture the scattering waves from the crack. Both the pitch-catch and pulse-echo experimental modes were used. The directionality effect of incident Lamb waves on the imaging results was studied. The effect of summation, multiplication, and combined algorithms for each imaging method was studied. It was found that both methods can successfully predict the crack size and orientation. An attempt was made to use these imaging methods for detecting and sizing smaller sized damage (1- to 3-mm-diameter hole). It was found that these methods can successfully localize the hole, but size estimation was a bit challenging because of the smaller dimensions. The scattering waves for various hole sizes were studied.
关键词： synthetic time reversal,crack sizing,Structural health monitoring,wave propagation,scattering waves
更新于2025-09-23 15:23:52
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Study of In-Plane Wave Propagation in 2-Dimensional Anisotropic Elastic Metamaterials
摘要： Objective Due to its multiple applications, elastic metamaterial is of great interest for researchers today. In this article, in-plane wave propagation in 2-D anisotropic metamateials with anisotropic density and anisotropic Young’s modulus is comprehensively studied. Method Characteristics of wave propagation in 2-D metamaterial with different combinations of negative properties are provided, and the unnatural phenomenon is also explained. Based on Snell’s law and weld boundary condition, analysis of wave propagation from conventional isotropic material into anisotropic metamaterial is performed. Significance This paper can serve as a foundation for future study of massive modeling and simulation of both isotropic and anisotropic metamaterials.
关键词： Anisotropy,Snell’s law,Wave propagation,Christoffel equations,Elastic metamaterials
更新于2025-09-23 15:23:52
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Frozen Gaussian approximation for high frequency wave propagation in periodic media
摘要： Propagation of high-frequency wave in periodic media is a challenging problem due to the existence of multiscale characterized by short wavelength, small lattice constant and large physical domain size. Conventional computational methods lead to extremely expensive costs, especially in high dimensions. In this paper, based on Bloch decomposition and asymptotic analysis in the phase space, we derive the frozen Gaussian approximation for high-frequency wave propagation in periodic media and establish its converge to the true solution. The formulation leads to ef?cient numerical algorithms, which are presented in a companion paper [SIAM J. Sci. Comput. 38 (2016), A2440–A2463].
关键词： lattice potential,high-frequency wave propagation,Bloch decomposition,Frozen Gaussian approximation
更新于2025-09-23 15:22:29
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Stilbene derivative as a photosensitive compound to control the excitability of neonatal rat cardiomyocytes
摘要： Substances that can be used as photosensitizers for cardiac tissue are very helpful in modeling various excitation patterns in a cardiac tissue culture and may have prospective use in the temporary and permanent ablation of unwanted excitation sources in the heart. The aim of the present work is to study the effect of stilbene derivative c-TAB (2- {4- [(E) -2- (4-ethoxyphenyl) vinyl] phenoxy} ethyl) trimethylammonium bromide) on the cardiomyocyte layers and voltage-gated ion channels in cardiac cells. C-TAB is a structural analogue to AzoTAB, reported previously as a photoswitch for cardiac and neural cells, in which the azobenzene moiety is replaced by a stilbene grouping. Such a replacement makes c-TAB less toxic to living cells. c-TAB has been shown to successfully inhibit excitation in cardiac cells in both trans- and cis- forms. The excitation inhibition of cardiac cells under c-TAB is reversible and can be overturned easily by washing out the c-TAB; however, not by light illumination. The irradiation of cardiac cells with near-UV when the trans- form of c-TAB is applied changes reversible inhibition to a permanent one that cannot be overturned by a washout.
关键词： Excitation wave propagation,Stilbene derivative,Voltage-gated Ion channels,Neonatal rat cardiomyocyte
更新于2025-09-23 15:22:29
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Superpositions of Gaussian beams and column Gaussian packets in heterogeneous anisotropic media
摘要： Based on the integral superposition of Gaussian packets, we derive the equations for the integral superposition of Gaussian beams and for the integral superposition of column Gaussian packets in smoothly heterogeneous media. Whereas Gaussian beams extend along their central rays, column Gaussian packets extend along an arbitrary system of lines. The equations are applicable to both the anisotropic ray theory and the coupling ray theory in anisotropic media, or to the isotropic ray theory in isotropic media. The superpositions corresponding to the coupling ray theory can be applied to various kinds of reference rays. The equations can be used in both Cartesian and curvilinear coordinates.
关键词： Electromagnetic anisotropy,Seismic attenuation,Body waves,Theoretical seismology,Wave propagation,Seismic anisotropy
更新于2025-09-23 15:22:29
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Measurements of Beamswitching Gains and Fade Dynamics for 28 GHz Indoor Static Links in the Presence of Pedestrian Traffic
摘要： We measured channel dynamics for fixed wireless indoor channels at 28 GHz. We characterize pedestrian-induced fades in open indoor spaces and the effectiveness of beamswitching to mitigate them. We find that fades of the dominant propagation path may be as deep as 9 dB at the 90th percentile and that alternative signal paths are typically not strong enough to provide significant beamswitching gains.
关键词： Millimeter wave propagation,Rician channels,Channel models,Multipath channels,Fading channels
更新于2025-09-23 15:22:29