Revert "improvements in the introduction"

This reverts commit f537e5ed175f4c161dff2637639815a878165ef1.

Conflicts:
	2014_ELSEVIER_CEE_SI/paper_cee_special_issue.aux
	2014_ELSEVIER_CEE_SI/paper_cee_special_issue.log
	2014_ELSEVIER_CEE_SI/paper_cee_special_issue.pdf
	2014_ELSEVIER_CEE_SI/paper_cee_special_issue.tex