σ V , W   = ( Q V ε  Q W η   )  × (   t  ∇ G V  × C × ∇ G W   )        ( 32  )    MathType@MTEF@5@5@+=feaafiart1ev1aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacH8akY=wiFfYdH8Gipec8Eeeu0xXdbba9frFj0=OqFfea0dXdd9vqai=hGuQ8kuc9pgc9s8qqaq=dirpe0xb9q8qiLsFr0=vr0=vr0dc8meaabaqaciaacaGaaeqabaqabeGadaaakeaaiiGacqWFdpWCdaWgaaWcbaGaemOvayLaeiilaWIaem4vaCfabeaakiabg2da9maabmaabaGaemyuae1aa0baaSqaaiabdAfawbqaaiab=v7aLbaakiabdgfarnaaDaaaleaacqWGxbWvaeaacqWF3oaAaaaakiaawIcacaGLPaaacqGHxdaTdaqadaqaaiabbccaGmaaCaaaleqabaGaemiDaqhaaOGaey4bIencbeGae43raC0aaSbaaSqaaiabdAfawbqabaGccqGHxdaTcqGFdbWqcqGHxdaTcqGHhis0cqGFhbWrdaWgaaWcbaGaem4vaCfabeaaaOGaayjkaiaawMcaaiaaxMaacaWLjaWaaeWaaeaacqaIZaWmcqaIYaGmaiaawIcacaGLPaaaaaa@550C@