**Acknowledgements**

One of the authors (C.P.) would like to thank the Federal University of Paraiba and the University of Washington Tacoma for providing the opportunity to develop his research work in the United States.

This work was partially funded by the UWT Endowment in Engineering Systems (O.B.), by the Brazilian Center for Scientific Research (CNPq) through the Foreign Visiting Professor Program (PEV) and through the National Institute of Science and Technology of Micro and Nanoelectronics Systems (INCT-NAMITEC) and by FAPEMA-Universal (N° 40/2015 grant number 01550/16).
