We propose one-dimensional photonic bandgap (PB) dielectric structures to be used at grazing incidence in order to obtain an extended bandgap exhibiting considerably reduced reflection loss and dispersion compared to similar structures used at a normal incidence of light. The well-known quarter-wave condition is applied for the design in this specific case, resulting in resonance-free reflectio...

In a previous paper the authors analyzed and discussed the specular reflection coefficient of a plane boundary comprised of a plate, a compliant layer, and a fluid. The analysis showed that a negligible specular reflection coefficient may be derived provided specific resonance conditions are met. The resonance of concern is that between the surface mass of the plate and the surface stiffness of...

Background/introduction In tcMRgFUS, acoustic and spatial heterogeneities of the skull cause reflection, attenuation, and phase aberrations of the acoustic beams, which may cause patient-specific thermal responses to the same transducer power. In this work, we use acoustic and thermal simulations based on patient-specific 3D heterogeneous tissue models to predict heating at the center of the br...

The lowest-order nonlocal small slope approximation (NLSSA) reflection coefficient is derived, and numerical results are presented for one-dimensional (1-D) surfaces, satisfying the Dirichlet boundary condition. Reduction to the perturbation expression occurs in the small height limit, and the first term of the reflection coefficient gives the Kirchhoff approximation (KA) result. Numerical resu...

A dynamical billiard is an idealization of the game of billiard, but where the table can have shapes other than the rectangular and even be multidimensional. We use only one billiard ball, and the billiard may even have regions where the ball is kept out. Formally, a dynamical billiard is a dynamical system where a massless and point shaped particle moves inside a bounded region. The particle i...

A ferrofluid layer separates into numerous subscale crests, which is referred to as Rosensweig instability, whose shape and size depend on the field condition composition of ferrofluid. consisting nanoscale magnetite particles also used an electromagnetic (EM) wave absorption reflection material. For this study, oil-based mixture layers that split various shapes crests in presence external magn...