Abstract: A precast prerotation basin system for use in a wet well for removing water or fluid therefrom is disclosed which comprises a prefabricated, three-dimensional body having a prerotation basin and fluid entrance channel. The precast prerotation basin presents an improvement over prior methods of forming prerotation basins downhole in a wet well because the basin system of the present invention is prefabricated, easily transportable and can be placed in a wet well without the need for providing a cement casing or floor beforehand. The precast prerotation basin of the present invention is pre-structured for accurate alignment of a centrifugal pump therein and eliminates the cost and inaccuracies of forming prerotation basins from molding cement downhole.

Abstract: A method for predicting yields for integrated circuit designs for given specification limits and process variations with respect to transistor parametric variations is based on a stastical analysis starting with response surface modeling techniques that relate desired circuit outcomes as a function of a set of defined independent variables. The response surfaces are converted to discrete C.sub.pk surfaces for all combinations of the independent variables. The C.sub.pk surfaces are next converted to discrete percent yield surfaces for each of the circuit outcomes which then are combined to provide a composite yield surface comprising all desired parametric operating points of the outcomes that may be used to predict the circuit yield.