Efficient 3-D Finite Element Modeling of Periodic XBAR Resonators.

An efficient technique is presented for 3-D finite element modeling of large-scale periodic excited bulk acoustic resonator (XBAR) resonators in the time-harmonic domain. In this technique, a domain decomposition scheme is used to decompose the computational domain into many small subdomains whose FE subsystems can be factorized with a direct sparse solver at a low cost. Transmission conditions (TCs) are enforced to interconnect adjacent subdomains, and a global interface system is formulated and solved iteratively. To accelerate the convergence, a second-order TC (SOTC) is designed to make the subdomain interfaces transparent for propagating and evanescent waves. An effective forward-backward preconditioner is constructed that when combined with the SOTC significantly reduce the number of iterations at no additional cost. Numerical results are given to demonstrate the accuracy, efficiency, and capability of the proposed algorithm.

A comparison of two anatomical body models derived from the female visible human project data.

Two electromagnetic human body models independently developed from the same image dataset-the voxel-based AustinWoman and surface-based VHP-Female models- are compared. In addition to contrasting volumes and crosssection images of their tissues, the power absorbed by the two models under plane-wave excitation is also compared. Five different numerical methods are used to compute the absorbed power and to evaluate modeling and computational errors.

AustinMan and AustinWoman: High-fidelity, anatomical voxel models developed from the VHP color images.

The current versions (v2.3) of AustinMan and AustinWoman anatomical voxel models are presented with the methodology used to generate them from the Visible Human Project's color cross-sectional anatomical images. Both models are freely available online and documented in detail to increase their reproducibility. Visualizations of the models are shown to highlight their complexity.

Homogenization of three-dimensional metamaterial objects and validation by a fast surface-integral equation solver.

A homogenization model is applied to describe the wave interaction with finite three-dimensional metamaterial objects composed of periodic arrays of magnetodielectric spheres and is validated with full-wave numerical simulations. The homogenization is based on a dipolar model of the inclusions, which is shown to hold even in the case of densely packed arrays once weak forms of spatial dispersion and the full dynamic array coupling are taken into account. The numerical simulations are based on a fast surface-integral equation solver that enables the analysis of scattering from complex piecewise homogeneous objects. We validate the homogenization model by considering electrically large disk- and cube-shaped arrays and quantify the accuracy of the transition from an array of spheres to a homogeneous object as a function of the array size. Simulation results show that the fields scattered from large arrays with up to one thousand spheres and equivalent homogeneous objects agree well, not only far away from the arrays but also near them.