where k is the slope of radius of curvature, determining the
shape of a scroll spiral; 0 is the initial radius of the
curvature;( 0 , 0 ),( 1, 1)are the initial points of the
moving scroll and the fixed scroll respectively; s is the tangential angle of a point on a moving scroll; s is the tangential angle of a point on a fixed scroll; s
is the orbit angle of the moving scroll; s is the radius of the moving
scroll orbit.