Unless it is a common acronym (like AI is), the original word (no matter how long it is) should be preferred instead of an abbreviation (since it hasn't the aesthetics that the original word has and also it could cause a misinterpretation (if it is not a common abbreviation)).
yes Its Aimechanism.com not Amechanism.com last week thought register it but some one registerd it demanding 2500$ on dan.com so am curious to ask domain appraisal guys thanks. unable to buy price is too high