Hi Hamidreza Safari ,

I think you can find your answers in this article: https://www.aje.com/en/arc/editing-tip-when-use-abbreviations/

Abbreviations should be defined in the introduction or at the first appearance in the paper, but not in the abstract.

Regards!

Dear Hamidreza Safari ,

Abstracts have a concise, simplified linguistic structure. As a rule you should not define or use abbreviations in them. You should also avoid things like examples, footnotes, citations and remarks in brackets.

Define your abbreviations only the first time you write them in your abstract and introduction.