[Rollo, Andrew C.;Cameron, Joseph;Kettle, Jeff] Univ Glasgow, James Watt Sch Engn, Glasgow, Lanark, Scotland.^[Zang, Shoushou] Cent South Univ Forestry & Technol, Bangor Coll, Changsha, Peoples R China.^[Jia, Ren] Cent South Univ Forestry & Technol, Sch Elect & Phys, Changsha, Peoples R China.