A new software suite for electromagnetics

Mención Internacional en el título de doctorIn recent years, computational electromagnetics (CEM) techniques have become increasingly important with the rapid advancements in technology in areas such as electromagnetic compatibility, antenna analysis, radar cross section (RCS), cellular phone-human body interaction, design of electrical and medical devices, target recognition and lightning strike simulation. Among a variety of numerical simulation tools existing in the commercial market, many are based on the method of moments (MoM), the finite-difference time-domain method (FDTD), and the finite element method (FEM). Also, they implement hybridization with high-frequency or asymptotic technique such as, physical optics (PO), the uniform geometrical theory of diffraction (UTD) and Multilevel Fast Multipole Algorithm (MLFMA) among others. It is worth to note that many of the commercial simulation tools existing in the market has been born as numerical in-house codes in the academic sector. In this context, it is important to note the contribution of the research group guided by Prof. Tapan K. Sarkar (Syracuse University) to the CEM field during last decade. The development of a new electromagnetic solver based on MoM has been carried out in order to provide fast and accurate solutions of a wide range of electromagnetic problems, especially for the solution of electrically large and complex problems. From other hand, the research group to which the author of the present Ph. D dissertation belongs has an important research line focused on the development of codes based on FEM. Then, the implementation of a FEM code makes possible the development of, not only an electromagnetic software based on an integral formulation of the electromagnetic problem, but a complete electromagnetic suite with also a differential formulation approach. Hence, the development of a new software suite for electromagnetics becomes the main objective of this Ph. D. dissertation. The suite will be composed by a professional graphical user interface (GUI) and two solver modules based on MoM and FEM, respectively. The GUI will provide tools for an easy and quick simulation process, the parametrization of geometric models in terms of symbolic variables or the use of an automatic goal oriented optimizer. The FEM module of the suite will present important unique features compared with other commercial software such as, the use of a novel iterative integral equation method for mesh truncation, the use of its own higher order set of basis functions and the use of parallel programming schemes from the beginning on its development. This module will also be able to perform the analysis of large antenna arrays using an infinite array approach. Although, the infinite array approach make uses of structures that are not a physically realistic, the analysis of this structures provides a reasonable good approximation with a less computing requirement than the analysis of the full problem. Finally, taking advantage of the existence in the suite of two of the most important computational electromagnetics numerical techniques such as, MoM and FEM, the hybridization between them seems an appropriate choice to perform complex simulation where the use of these techniques alone may not be efficiently appropriate. Thus, a modular approach to combine MoM and FEM techniques for the analysis of large structures or finite arrays with complex radiating elements have also been performed.Programa Oficial de Doctorado en Multimedia y ComunicacionesPresidente: Maurizio Bozzi.- Secretario: Daniel Segovia Vargas.- Vocal: Rafael Rodríguez Boi

Método de Elementos Finitos hp con Adaptabilidad Automática Orientada a un Objetivo para Problemas Abiertos en 2D

In this paper, we describe a fully automatic goaloriented hp-adaptive Finite Element strategy, which is applied to open problems (radiation and scattering). The methodology produces exponential convergence rates in terms of an upper bound of an user-prescribed quantity of interest (in our case, the S-parameter, the far radiated field or far scattering field) against the problem size (number of degrees of freedom). We illustrate the efficiency of the method with 2D numerical simulations of open problems (radiation and scattering). Applications include the far scattering (radiated) field by an object (antenna) and the computation of mutual coupling of the antennas (S-parameters). Results show that self-adaptive goal-oriented hp obtains more accuracy in the quantity of interest than self-adaptive energynorm hp with the same number of degrees of freedom

An interface between an hp-adaptive finite element package and the pre- and post-processor GiD

An interface between GiD, the interactive graphical user interface used for numerical simulations, developed at the International Center for Numerical Methods in Engineering (CIMNE) of the Universidad Politécnica de Cataluña and the Geometrical Modeling Package (GMP) of the fully automatic hp-adaptive finite element (FE) software, developed at the Institute for Computational Engineering and Sciences (ICES) of the University of Texas at Austin, is presented. GiD is used to construct a tessellation of the problem domain into FE-like regions (blocks in GMP terminology), and the interface obtains and transfers all the topological and geometrical information to GMP. Then, GMP automatically constructs a parameterization for each FE-like region of the GMP mesh, which later can be used to generate the actual FE-mesh and support geometry updates during mesh refinements

Second-Order Nedelec Curl-Conforming Prismatic Element for Computational Electromagnetics

A systematic approach to obtaining mixed-order curl-conforming basis functions for a triangular prism is presented; focus is made on the second-order case. Space of functions for the prism is given. Basis functions are obtained as the dual basis with respect to suitably discretized Nedelec degrees of freedom functionals acting on elements of the space. Thus, the linear independence of the basis functions is assured while the belonging of the basis to the a priori given space of functions is guaranteed. Different strategies for the finite element assembly of the basis are discussed. Numerical results showing the verification procedure of the correctness of the implemented basis functions are given. Numerical results about sensibility of the condition number of the basis obtained concerning the quality of the elements of the mesh are also shown. Comparison with other representative sets of basis functions for prisms is included.This work was supported by "DiDaCTIC: Desarrollo de un sistema de comunicaciones inalambrico en rango THz integrado de alta tasa de datos"; TEC2013-47753-C3, CAM S2013/ICE-3004 "DIFRAGEOS" projects and "Ayudas para contratos predoctorales de Formación del Profesorado Universitario FPU

A Nonstandard Schwarz Domain Decomposition Method for Finite-Element Mesh Truncation of Infinite Arrays

A nonstandard Schwarz domain decomposition method is proposed as finite-element mesh truncation for the analysis of infinite arrays. The proposed methodology provides an (asymptotic) numerically exact radiation condition regardless of the distance to the sources of the problem and without disturbing the original sparsity of the finite-element matrices. Furthermore, it works as a multi Floquet mode (propagating and evanescent) absorbing boundary condition. Numerical results illustrating main features of the proposed methodology are shown.This work was supported in part by the National Key Research and Development Program of China under Grant 2016YFE0121600, in part by the China Postdoctoral Science Foundation under Grant 2017M613068, in part by the National Key Research and Development Program of China under Grant 2017YFB0202102, and in part by the Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund under Grant U1501501