1. CCAF, IFM/CDTec-PPGCEM, Federal University of Pelotas, CEP: 96010-610, Pelotas, RS, Brazil
2. Federal Institute of Sul-rio-grandense, CEP: 96015-360, Pelotas, RS, Brazil
3. IFM/PPGFis, Federal University of Pelotas, CEP: 96160-000, Capão do Leão, RS, Brazil