I know that Google’s search algorithm is mainly based on pagerank. However, it also does analysis and uses the structure of the document H1, H2, title and other HTML tags to enhance the search results.
What is the name of this technique "using the document structure to enhance the search results"?
And are there any academic papers to help me study this area?
The fact that Google is taking the HTML structure into account is well covered in SEO articles however I could not find it in the academic papers.
I think it's called "Semantic Markup"
[...] semantic markup is markup that is descriptive enough to allow us and the machines we program to recognize it and make decisions about it. In other words, markup means something when we can identify it and do useful things with it. In this way, semantic markup becomes more than merely descriptive. It becomes a brilliant mechanism that allows both humans and machines to “understand” the same information. http://www.digital-web.com/articles/writing_semantic_markup/
A more practical article here http://robertnyman.com/2007/10/29/explaining-semantic-mark-up/