Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu. Y.Khadri, Badji Mokhtar University, Annaba, Algeria, e-mail: This email address is being protected from spambots.
Y.Mehidi, Larbi Tebessi University, Tebessa, Algeria S.Yahyaoui, National Polytechnic School, Algiers, Algeria I.Kahoul, Badji Mokhtar University, Annaba, Algeria, e-mail: This email address is being protected from spambots.
