Salvatore ALFONZETTI

Full Professor of Electrical engineering [ING-IND/31]

Salvatore (Toti) Alfonzetti was born in Catania, Italy, in 1952. He received his degree (summa cum laude) in electrical engineering from the University of Catania, Italy in 1976. Since 1977, he has been working at the same university with different positions: contract professor of 'Circuit Theory' from 1980 to 1983, university researcher of 'Electrotechnics' from 1983 to 1987, associate professor of 'Signal Theory' from 1987 to 1994 and of 'Electrotechnics' from 1994 to 2000, and full professor of 'Electrotechnics' since 2000. He has been the director of the Engineering Computing Centre from 1992 to 1998, the vice director from 1997 to 2003 and the director from 2005 to 2008 of the DIEES Department, the counselor of the IEEE Student Branch at the University of Catania from 1999 to 2001, the chairman of the Departmental Joint Commission of the DIEEI Department (Department of Electrical Engineering, Electronics and Computer Science) from 2012 to 2014, and the chairman of the board of the Master Course in Electrical Engineering from 2013 to 2016.

Since 1994 he has been the scientific coordinator of the Electrical Engineering Research Group at the University of Catania. His main research work is currently concerned with the finite element analysis and optimization of electromagnetic devices.

He is the author of more than two hundred papers. S. Alfonzetti acts as a member of the editorial boards of Compumag and CEFC conferences, a member of the editorial board of the 'Mathematical Problems in Engineering' journal, a member of the IEEE (The Institute of Electrical and Electronics Engineers), of the AEIT (The Italian Association of Electrotechnics, Electronics, Automation, Informatics and Telecommunications), and a founder member of ICS (International Compumag Society).

 

VIEW THE COURSES FROM THE A.Y. 2022/2023 TO THE PRESENT

Academic Year 2021/2022


Academic Year 2020/2021


Academic Year 2019/2020


Academic Year 2018/2019


Academic Year 2017/2018


Academic Year 2016/2017


Academic Year 2015/2016

In the last few years the activity of the research unit of Computational Electromagnetics at the University of Catania  has been mainly concerned with the theoretical and experimental study of numerical methods for the computation of electromagnetic fields. In this context the main tool is ELFIN, a finite element code entirely developed by the members of the reserach unit for electromagnetic CAD research. Presently the code consists of more than 600 subroutines for a total of 100,000 Fortran statements. By means of this code it is possible to study electromagnetic devices the analysis of which requires the solution of electrostatic, magnetostatic, eddy current and/or skin effect and wave scattering/radiation problems. The main research topics are briefly outlined below.

1) Static field computation in open boundaries.  A hybrid method, called FEM-DBCI (Finite Element Method - Dirichlet Boundary Condition Iteration), has been devised for the finite element computation of electrostatic fields induced by voltaged conductors in open boundaries. The method requires the introduction of a fictitious truncation boundary which includes all the conductors. The potential on this boundary (Dirichlet condition) is first guessed arbitrarily and then improved iteratively by means of an integral equation which makes use of the free-space Green function and whose integration surface is different from the truncation one. The procedure is simple to implement and rapidly converges to the exact solution of the unbounded problem. Moreover, in order to avoid some well-known drawbacks of the classical FEM-BEM (sharp corners, same shape functions for the field and its normal derivative) a new family of (2D, 3D and axisymmetric) simplex nodal boundary elements has been devised, in such a way that the nodes of the field variable are placed in the canonical positions, whereas the nodes of the normal derivative are placed in between them and inside the element.

2) Solution of skin effect and eddy current problems. Two-dimensional and axisymmetric skin effect problems have been successfully solved by means of an integro-differential formulation. The finite element discretization is based on the use of mutual universal matrices, which allow per-element assembly of the integral term in the global algebraic system. Problems set in unbounded domains are treated, as in FEM-DBCI, by introducing a fictitious boundary on which the magnetic vector potential is iteratively improved starting from the current density flowing in the conductors.

3) Non-linear transient magnetic field computation in open boundaries. The computation of non-linear transient magnetic fields is based on the setting up, at each discrete time, of two algebraic systems, one for the predictor and the other for the corrector. Both these systems are solved iteratively assuming an initial guess for the Dirichlet condition on the fictitious boundary and improving it by making use of the free-space Green function until convergence takes place. A great reduction in computing time is obtained with respect to the solution with a Newton-Raphson solver.

4) Electromagnetic scattering/radiation problems. A hybrid method called FEM-RBCI (Robin Boundary Condition Iteration) has been devised for the finite-element solution of scalar (2D) and vector (3D) scattering/radiation problems in unbounded domains. The scattering objects may have multiple connectivity, they may be of different materials or may have different boundary conditions. A fictitious boundary enclosing all the objects involved is introduced. An appropriate non-homogeneous Robin (mixed) condition is initially guessed on this boundary and is iteratively improved by means of an integral equation making use of the Green formula. It can be seen that the best choice for the Robin condition is an absorbing-like one. Comparisons with other methods and numerical examples show that the method is accurate and avoids internal resonances whatever the frequency of the incident wave.

5) Optimisation of electromagnetic devices. The research has had the aim of reducing the computing time of the whole process of optimisation by means of the stochastic methods Simulated Annealing and Genetic Algorithms. To compute the objective function, these employ the finite element code ELFIN, which is able to accept input data in a parametric way. A reduction in computing time has been achieved both by making the optimisation methods themselves more efficient, and by studying particular schemes which allow greater economy in the building of the global algebraic systems in the various finite element analyses.

6) Automatic mesh generation by means of ANNs. An automatic generator of triangular finite element meshes has been devised, based on the Let-It-Grow artificial neural network. Starting from a raw mesh of triangles, the generator grows the number of nodes up to a user-defined value. The insertion of new nodes is driven by a probability density function specified by the user. Several modifications have been made to the original Let-It-Grow algorithm to preserve the domain boundaries and the mean quality of the elements.

7) Finite element software. In the implementation of the ELFIN code, some particularly original algorithms have inspired the writing of scientific papers, mostly for conferences.