[1] Siddaganga Inst Technol, Dept Math, Tumkuru, India
[2] Davangere Univ, Dept Math, Davangere, India
[3] Xi An Jiao Tong Univ, Inst Bldg Environm & Sustainabil Technol, Sch Human Settlements & Civil Engn, Xian 710049, Peoples R China
[4] Lund Univ, Dept Energy Sci, S-22100 Lund, Sweden