^pof;
Mechanical;
Electronic;
&;
Information;
Engineering,;
China;
University;
of;
Mining;
&;
Technology,;
Beijing;
100083,;
China;
^pof;
Mechanical;
and;
Aerospace;
Engineering,;
West;
Virginia;
University,;
Morgantown,;
WV;
26505,;
U.S.A;