Computing the information content of decoupled designs

The information content of uncoupled designs can be computed by summing the information content associated with each functional requirement. This pape r proves that information cannot be summed for decoupled designs. To overco me this problem, this paper presents two algorithms for computing informati on content of decoupled designs. One algorithm is applicable to any joint p robability density function far the design parameters; the second algorithm applies only to uniformly distributed design parameters. The algorithm for uniform distributions is based on a recursive procedure for computing the volume of a convex polytope in n-dimensional real space, where n is the num ber of design parameters. An engineering application of the algorithms is p resented. The example demonstrates that summing information content can sig nificantly over-estimate total information when compared to an algorithm th at accounts for correlation. The example also demonstrates that decoupled d esigns can have lower information content than uncoupled systems with the s ame functional requirements and similar components.