It is given that an another proof for the classical affine relative difference set by using Gauss sums,and we construct a new family of divisible difference sets with parameters \%q\+n-1q-1,q-1,q\+\{n-1\}-1,q\+\{n-1\}-1,q\+\{n-2\}-1,\%where \%n≥2,q\% is a power of a prime.

A subset difference(SD) key management method is very suitable to the member change circumstance in MANET.

So it solves subset and layered subset difference scheme’s unscalability.

The algorithm of centralization differential and Kalman filter used in GPS position differential and vessel positioning are studied.

In this paper we introduce special morphisms on difference sets and we prove that the quotient of the equivalence classes defined by special morphisms is a difference set.

This thesis focuses on the algebraic structures of partial Abeliansemigroups and difference sets, which were introduced ten years before, and theoperation continuity of a class of important quantum logics.