  A possible approach to the statistical description of granular assemblies
starts from Edwards' assumption that all blocked states occupying the same
volume are equally probable (S.F. Edwards, R. Oakeshott, Physica A 157, 1080
(1989)). We performed computer simulations using two-dimensional polygonal
particles excited periodically according to two different protocols: excitation
by pulses of "negative gravity" and excitation by "rotating gravity". The first
protocol exhibits a non-monotonous dependency of the mean volume fraction on
the pulse strength. The overlapping histogram method is used in order to test
whether or not the volume distribution is described by a Boltzmann-like
distribution, and to calculate the inverse compactivity as well as the
logarithm of the partition sum. We find that the mean volume is a unique
function of the measured granular temperature, independently of the protocol
and of the branch in $\phi(g)$ and all determined quantities are in agreement
with Edwards' theory.
