Perhaps you should try some spelling variations:
"mechanical engineers" » "mechanical engineering"
"electrical engineers" » "electrical engineering"
"chemical engineers" » "chemical engineering"
"electrical line" » "electrical life", "electrical engine", "electrical aging"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("electrical line") OR ((((("electrical engineers") OR ("mechanical engineers"))) OR ("chemical engineers")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"electrical line\") or (((((\"electrical engineers\") OR (\"mechanical engineers\"))) or (\"chemical engineers\"))))".
• Removing quotes may allow a broader search: (( electrical line ) or ((((( electrical engineers ) OR ( mechanical engineers ))) or ( chemical engineers )))).
• Adding a wildcard symbol may retrieve word variants: (("electrical line") or ((((("electrical engineers") OR ("mechanical engineers"))) or ("chemical engineers"))))*.