  We demonstrate a class of model nano-electromechanical systems (NEMS) based
on multiwalled carbon nanotubes (MWNTs) which has longer inner cores coaxially
oscillating inside their respective shorter outer shell holders and can operate
at continuously controllable frequencies up to the gigahertz range when fuelled
by AC electric fields. Its additional attributes include much larger
oscillation amplitudes and forces and much lower rates of thermal dissipation
(Q-factor = 10^5) and air damping (Q-factor = 10^4~10^5) than those of
nano-beam based NEMS. A crucial feature of the conceived model NEMS is that
after having tuned the electric field frequency to any prescribed value within
a permitted range, the NEMS will respond quickly (in sub-nanoseconds) at the
same oscillation frequency. These merits, when contrasted with the nano-beam
resonators developed so far, make it a better potential candidate for the
ongoing miniaturization progress from micro- to nano-electromechanical systems.
