Reflection and transmission of P-waves at a very rough interface between two isotropic elastic solids

This paper deals with the reflection and transmission of P-waves at a very rough interface between two isotropic elastic solids. The interface is assumed to oscillate between two straight lines. By mean of homogenization, this problem is reduced to the reflection and transmission of P-waves through an inhomogeneous orthotropic elastic layer. It is shown that a P incident wave always creates two reflected waves (one P wave and one SV wave), however, there may exist two, one or no transmitted waves. Expressions in closed-form of the reflection and transmission coefficient have been derived using the transfer matrix of an orthotropic elastic layer. Some numerical examples are carried out to examine the reflection and transmission of P-waves at a very rough interface of tooth-comb type, tooth-saw type and sin type. It is found numerically that the reflection and transmission coefficients depend strongly on the incident angle, the incident wave frequency, the roughness and the type of interfaces.

Generalized model of Kapitza conductance across rough interfaces

This paper is devoted to the theoretical prediction of the interfacial heat transfer in nanostructured materials. The main task of this work is the analysis of interaction of elastic waves with the rough interface between two different solids. The presence of toughness leads to a significant increase in the resistance to heat transfer in nanostructures. This fundamental problem is discussed in relation to the commonly used method of wave scattering at rough surface: the Kirchhoff tangent plane method. The method assumes that at the point of the rough surface profile, the surface is regarded as locally smooth, and the reflection and transmission of the incident wave can be described by the scattering at the tangent plane of this point. Based on the elastic wave theory, we use the frequency-dependent continuity conditions to calculate the energy transmission coefficient at the interface. And then its effective value at the rough interface is estimated by using the Kirchhoff method. By substituting this effective value into the formula of Kapitza conductance, we can calculate the Kapitza conductance at the rough interface and analyze the effect of roughness on the interfacial heat transfer.

Interface construction for charge transportation of ZnO/graphene multilayer films

In order to clarify the effect of interface construction on the charge transportation, the interfaces between zinc oxide (ZnO) and graphene layers were designed into the following types: the smooth interface by direct deposition ZnO layer onto the surface of fresh graphene/glass substrate; the nanoscale rough interface by Ar[Formula: see text] bombardment etching the surface of graphene/glass substrate before deposition of a ZnO layer, and rough ZnO/Ag/graphene interface by deposition Ag first and then ZnO layers on the rough graphene/glass substrate. The results showed that, compared to the morphology of the ZnO/graphene film with smooth surface, the particle sizes of the film with rough interface became fine and their shapes changed from sharp to round. The carriers’ mobility increased from 0.3 cm2 ⋅ V[Formula: see text] ⋅ s[Formula: see text] to 0.6 cm2 ⋅ V[Formula: see text] ⋅ s[Formula: see text] due to the enhancement of the nanocontact at the rough interface between ZnO and graphene layers. In order to improve the electrical properties of ZnO/graphene multilayer film, a 10 nm Ag layer was inserted into the rough graphene/glass and ZnO layer to construct the rough metal interface. The carrier concentration was enhanced from 10[Formula: see text] cm[Formula: see text] of ZnO/graphene to 10[Formula: see text] cm[Formula: see text] ZnO/Ag/graphene films, although the carrier mobility reduced slightly from ZnO/graphene 0.6 to ZnO/Ag/graphene 0.2 cm2 ⋅ V[Formula: see text] ⋅ s[Formula: see text]. The sheet resistance and resistivity of the ZnO/Ag/graphene multilayer film decreased dramatically by inserting the conductive Ag layer, which took the roles of both the provider of charge carriers from Ag layer and bridges of the carriers from graphene layer.

On the reflection of time-domain acoustic spherical waves by a sinusoidal diffraction grating

This work reports on some results obtained from numerical simulations of time-domain acoustic wave propagation in the presence of a periodically rough interface. Emphasis is put on the structure of the reflected signals in the presence of a sinusoidal grating. More specifically, we investigate the effect of the frequency bandwidth of the emitted signal and the effect of the incident wavefront sphericity on the signals reflected from the rough interface and associated with the different diffraction orders.