Math S.J.T.U. Phase Transformation and Applications ·Total differential z=f(x,y) Euler 8z o Stiring approximately equation lnW！≈WlnW-W SJTU Thermodynamics of Materials Spring 2010 ©X.J.Jin Lecture 1 First law I 9/38Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2010 © X. J. Jin Lecture 1 First law I 9/38 Math • Total differential ln N! N ln N  N • Stiring approximately equation   1                          z y x z y x z y x x y z y z x z x y                             Euler z  f (x, y)