  Within Yang-Mills gravity with translation group $T(4)$ in flat space-time,
the invariant action involving quadratic translation gauge-curvature leads to
quadrupole radiations which are shown to be consistent with experiments. The
radiation power turns out to be the same as that in Einstein's gravity to the
second-order approximation. We also discuss an interesting physical reason for
the accelerated cosmic expansion based on the long-range Lee-Yang force of
$U_{b}(1)$ gauge field associated with the established conservation law of
baryon number. We show that the Lee-Yang force can be related to a linear
potential $\propto r$, provided the gauge field satisfies a fourth-order
differential equation. Furthermore, we consider an experimental test of the
Lee-Yang force related to the accelerated cosmic expansion. The necessity of
generalizing Lorentz transformations for accelerated frames of reference and
accelerated Wu-Doppler effects are briefly discussed.
