  We calculate the electron acceleration in random superluminal strong waves
(SLSWs) and radiation from them by using numerical methods in the context of
the termination shock of the pulsar wind nebulae. We pursue the electrons by
solving the equation of motion in the analytically expressed electromagnetic
turbulences. These consist of primary SLSW and isotropically distributed
secondary electromagnetic waves. Under the dominance of the secondary waves,
all electrons gain nearly equal energy. On the other hand, when the primary
wave is dominant, selective acceleration occurs. The phase of the primary wave
felt by the electrons moving nearly along the wavevector changes very slowly
compared to the oscillation of the wave, which is called "phase locked", and
such electrons are continuously accelerated. This acceleration by SLSWs may
play a crucial role in the pre-acceleration for the shock acceleration. In
general, the radiation from the phase-locked population is different from the
synchro-Compton radiation. However, when the amplitude of the secondary waves
is not extremely weaker than that of the primary wave, the typical frequency
can be estimated from the synchro-Compton theory by using the secondary waves.
The primary wave does not contribute to the radiation, because the SLSW
accelerates electrons almost linearly. This radiation can be observed as a
radio knot at the upstream of the termination shock of the pulsar wind nebulae
without counter parts in higher frequency range.
