Conceptual Links Between the Ewald‐Oseen Extinction Theorem and Return Stroke Modeling

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Within the last years, an increasing number of studies have been carried out in the field of acoustic metamaterials. These artificial composite materials aim at achieving new macroscopic properties, like negative refraction, that are not readily present in nature. In analogy to electromagnetics, where such concepts are more mature, a novel concept of artificial acoustic transmission line has recently been reported, which presents such artificial behavior. In this article, the design of the proposed transmis

The CaCu3Ti4O12 (CCTO) thin films were deposited on Pt/TiO2/Ti/SiO2/Si (100) substrates by pulsed laser deposition. The temperature dependences of dielectric constant were measured in the as-produced thin film samples, showing the so-called colossal dielectric constant (CDC) phenomenon. I-V and C-V characterizations evidenced that the electrode interface formed a Schottky barrier, whose depletion capacitance resulted in the observed CDC in CCTO thin films, while the interior of the material was found to be

At part load operation of Francis turbine, the swirl in the draft tube leads to flow instability known as vortex breakdown. This flow instability can interact with the rest of the hydraulic circuit through axially propagating plane-waves. Moreover, at low cavitation index , the gaseous rope is suspected to modify locally the propagation velocity. Acoustic models have been commonly used to tackle this problematic. In order to validate the parameters of those models, an experiment with equivalent phenomenolog

This work shows a self-consistent numerical model of ion cyclotron resonant heating (ICRH) in a plasma of arbitrary (2D or 3D) geometry. Effects of anisotropy and full shaping on both MHD equilibrium and the dielectric tensor are explored. In particular, it is shown that the dielectric tensor becomes dependent on poloidal angle. Also, the anisotropic effects dominate the dielectric tensor. Using single particle simulations it is demonstrated that anisotropy develops due to ICRH. The changing of the equilibr

Models of amorphous (HfO2)x(SiO2)(1), for varying hafnium, content x are generated by ab initio molecular dynamics. The structural properties are analyzed in terms of pair distribution functions from which typical bond lengths and coordination numbers are extracted. Electronic band gaps are calculated with a hybrid density functional and are found to decrease in a nonlinear way with increasing x, in accord with experimental observations. Static dielectric constants are evaluated through the application of a

We discuss the structural, electronic and dielectric properties of a model structure of the Si(100)-SiO2 interface that accounts for the amorphous nature of the oxide. After showing that the structural properties of this model are consistent with a variety of experimental data, we consider the variation of the valence and conduction band edges across the interface. Our calculations indicate that the width of the electronic structure transition from the substrate to the oxide is 0.7-0.8 nm. We also address t

In ferroelectric materials, domain wall displacement plays a key role in the dielectric properties measured with respect to the driving field amplitude and frequency. The low to medium field dielectric response in many ferroic systems can be often described by classical Rayleigh model, which is rate-independent i.e., it depends only on the strength of ac signal. However experiments show that the nonlinear parameters are frequency dependent. Thus a more general approach, which can describe both purely nonlin

We investigate the dielectric permittivity of SiO2 on Si(100) substrates using a first-principles approach. It is shown that both the static and high-frequency dielectric constants of the oxide overlayer increase when the oxide thickness is reduced. This behavior of the overlayer is found to be well reproduced by a classical two-layer model in which the pure oxide and the suboxide layer are treated as distinct dielectrics. Implications for interfaces between silicon and high-k gate oxides are discussed. (C)

Sol-gel process has successfully been applied for the deposition of porous PbZrxTi1-xO3 (x = 0.45, 0.15) thin films on platinized silicon wafers. Addition of a polymer as a volatile phase to the precursor sol prior to spin coating has been proved an excellent method to synthesize PZT-porous films. Introduction of pores creates a matrix void composite resulting in high figures of merit for pyroelectric applications. The dielectric constant was found to be strongly dependent to the porosity, whereas the pyroc

We introduce a density-functional perturbational scheme based on ultrasoft pseudopotentials for calculating dielectric tensors of periodic systems. We obtain a variational functional for the second-order derivative of the energy with respect to an electric field. Our scheme makes use of the correspondence between all-electron and pseudo-wave-functions introduced in the projector augmented wave method. While we here specifically focus on ultrasoft pseudopotentials, our scheme also covers the case of norm-con

Electromagnetic wave propagation in the Alfven frequency range in two-dimensional (2-D) and three-dimensional (3-D) plasma configurations is investigated by using a recently developed full-wave code, LEMan. The code solves the Maxwell equation globally in a fully 3-D numerical equilibrium geometry with nested magnetic surfaces and implements a cold plasma model with finite electron mass. Energy balance is used for the self-consistency and convergence checks. The code is applied for several 2-D systems and a

A review of the properties of ferroelectric materials that are relevant to microwave tunable devices is presented: we discuss the theory of dielectric response of tunable bulk materials and thin films; the experimental results from the literature and from own work are reviewed; the correspondence between the theoretical results and the measured properties of tunable materials is critically analyzed; nominally pure, real (defected), and composite bulk materials and thin films are addressed. In addition, tech

Conceptual Links Between the Ewald‐Oseen Extinction Theorem and Return Stroke Modeling

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Design of Acoustic Metamaterials based on the Concept of Dual Transmission Line

On origin and intrinsic electrical properties of the colossal dielectric constant state in CaCu3Ti4O12

ACOUSTIC RESONNANCE IN CAVITATION FREE AND CAVITATING FLOWS

Monte Carlo ICRH simulations in fully shaped anisotropic plasmas

Amorphous hafnium silicates: structural, electronic and dielectric properties

Atomic-scale modelling of the Si(100)-SiO2 interface

Analysis of the non linear domain wall response in ferroelectric thin films

Dielectric effect of a thin SiO2 interlayer at the interface between silicon and high-k oxides

Enhanced performance of pyroelectric microsensors through the introduction of nanoporosity

Density-functional perturbational theory for dielectric tensors in the ultrasoft pseudopotential scheme

Three-dimensional full-wave propagation code for cold plasma

Ferroelectric materials for microwave tunable applications