ToUpperNamesOfArtistsOfTheSelectedTracks

to upper(aString)
	set UPPERCASE to "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
	set theResult to characters of aString
	repeat with aChar in theResult
		set i to offset of aChar in UPPERCASE
		if i is not 0 then
			set contents of aChar to character i of UPPERCASE
		end if
	end repeat
	return theResult as text
end upper

tell application "iTunes"
	repeat with aTrack in (a reference to selection)
		set anArtist to artist of aTrack
		set artist of aTrack to my upper(anArtist)
	end repeat
end tell