Kezhong Zhao, PhD
Ansys Fellow at Ansys, Inc.
http://www.ansys.com/zh-cn (中文）
Kezhong is a passionate computational engineer with very strong background in computational electromagnetics, applied mathematics and numerical methods. He has conducted advanced researches on computational algorithms for solving Maxwell's equations (vector wave equations) over 15 years.
He is the key researcher in the solver team of commercial software HFSS. His research efforts have contributed significantly to HFSS for its recent advances including domain decomposition solver, hybrid finite element boundary integral solver, 3D component array and mesh fusion solvers.
Professional Experiences:
Ansys, Inc. (formerly Ansoft), Pittsburgh, PA (05/2007-present)
Ansys Fellow 04/2023--present
Distinguished Engineer 04/2019--03/2023
Principal R&D Engineer 04/2013--03/2019
Lead R&D Engineer 01/2010--03/2013
Senior R&D Engineer 07/2009--12/2009
R&D Engineer 05/2007--07/2009
ElectroScience Lab, The Ohio State University, Columbus, OH (07/2001-05/2007)
Graduate Research Associate
Recent Research Activities:
Effective Circuit Element and Circuit Port Modeling
Maintain FEM's symmetric and sparse system matrix without condition number deterioration
Allow domain decomposition split of circuit port and circuit element
CAD-Based Domain Decomposition Method
Full-wave rigorous iteration-free approach that enables domain decomposition at any arbitrary location
Allow concurrent meshing of individual components
Accurate parallel component-based adaptive mesh refinement
Integral Equation Domain Decomposition Method
Hybrid Finite Element Boundary Integral (FEBI) Solver in Ansys-HFSS
FEBI solver is, in essence, a powerful state-of-art multi-region and multi-solver hybrid solver. It was first introduced in HFSS v13.0 where it is capable of analyzing problems composed of disjoint regions. In this version, each region is modeled via finite element method (FEM) with boundary integral (BI) truncation scheme. Regions are coupled exactly via integral equation (IE) method. In HFSS v14.0, regions with pure metallic structures is allowed to use method of moments in stead of finite element method. For many real-life problem such as antennas placement on a large platform like aircraft, different regions are no longer disjoint but in fact contacting. This important application is tackled in HFSS v15.0 by allowing finite element method touching integral equation solver. In any application of FEBI including FEM touching IE, every boundary condition is taken into account exactly. Therefore this solver is very accurate in theory.
Distributed Domain Decomposition Method (DDM) in Ansys-HFSS
First introduced in HFSS v12.0 to analyze general problems. Extended to include finite array applications where periodicity can be taken advantage of in HFSS v14.0. In HFSS v15.0, DDM solver is rewritten by utilizing MPI parallelization. This DDM solver contains a robust higher order transmission condition, a novel multiple right-hand-side iterative solver and a new parallelizable DD precoditioner. In each domain, eiher FEM or IE solver can be applied. To solve even larger problems, massive parallelization is taken place in HFSS R15.0 where distributed RHS solver is introduced to solve multiple excitations in parallel. For electrically large IE domains, 2-level DDM is employed to solve these IE domains efficiently by applying distributed additive Schwarz preconditioner in the second level.
Acceleration of near/far field computations via innovative fast integral equation methods
First implemented in HFSS v11.1 where 5+ speed up was observed compared with HFSS v11.0. Further acceleration of near/far field computations and their parallel implementations were done in HFSS v13.0, 90+ speed up compared to HFSS v11.0.