  We study the scaling behavior of domain-wall energies in two-dimensional
Ising spin glasses with Gaussian and bimodal distributions of the interactions
and different types of boundary conditions. The domain walls are generated by
changing the boundary conditions at T=0 in one direction. The ground states of
the original and perturbed system are calculated numerically by applying an
efficient matching algorithm. Systems of size LxM with different aspect-ratios
1/8 <= L/M <= 64 are considered. For Gaussian interactions, using the
aspect-ratio scaling approach, we find a stiffness exponent theta=-0.287(4),
which is independent of the boundary conditions in contrast to earlier results.
Furthermore, we find a scaling behavior of the domain-wall energy as predicted
by the aspect-ratio approach. Finally, we show that this approach does not work
for the bimodal distribution of interactions.
