Firstly, don't use "Please help me" as a subject - try to make it a short summary of your problem so that we can tell if we know anything about the subject before we read the problem in full.
Secondly, Google is your friend: Be nice and visit him often. He can answer questions a lot more quickly than posting them here...
A very quick search <b><i>using your subject as the search term</i></b> gave:
http://www.google.co.uk/search?aq=f&sourceid=chrome&ie=UTF-8&q=Adaptive+cluster+distance+bounding[
^]
In future, please try to do at least basic research yourself, and not waste your time or ours.