  Orthogonal Fractional Factorial Designs and in particular Orthogonal Arrays
are frequently used in many fields of application, including medicine,
engineering and agriculture. In this paper we present a methodology and an
algorithm to find an orthogonal array, of given size and strength, that
satisfies the generalized minimum aberration criterion. The methodology is
based on the joint use of polynomial counting functions, complex coding of
levels and algorithms for quadratic optimization and puts no restriction on the
number of levels of each factor.
