Equation Icon  ∮ i −4 ( τk k ττ) i Q AΘ = ε dSk Θ N − vAΘ N yA, (160 ) ∮∂BA ( ) i −4 τkαβ k τταβ i QA χ = ε ∂B dSk χ N ,αβ − vAχ N ,αβ yA, (161 ) A