Methods and apparatus for modeling noise present in an integrated circuit substrate are disclosed. Wear resistance of the prior-art Ti layers can be considerably enhanced by optimising the grain size and microstructure. An air outlet is adaptable to the air inlet height of standard, widely-used carpet dryer blowers. Furthermore, the present invention performs a cost evaluation based on all the activity costs spent on each production cell, so as to evaluate the performance of each production cell, and meanwhile, the related personnel is informed in time for achieving the objectives of profit center and consistently improving the production efficacy. The respective stators of the resolver units are connected together such that the stator magnetic poles of the stator of one resolver unit do not overlap the stator magnetic poles of the stator of another resolver unit, as viewed in the axial direction.