Affiliation: | a Key Laboratory of Radioactive Geology and Exploration Technology, Fundamental Science for National Defense, East China Institute of Technology, Fuzhou, Jiangxi 344000, Chinab School of Mathematics and Information Sciences, East China Institute of Technology, Fuzhou, Jiangxi 344000, Chinac Department of Mathematics Education (and RINS), Gyeongsang National University, Chinju 660-701, Republic of Koread Department of Mathematics, Hubei University for Nationalities, Enshi, Hubei Province 445000, China |