Patent Document ID: 5499200
Application ID: 08062804
Patent Flag: 1

Claim One:
1. In an electrical system where components and environmental effects upon components within the system are modeled by a plurality of nodes which interact with each other, and where a field generated by a node and the susceptibility of that node dependent upon its shielding characteristics is determined, and where a most critical path between two of the nodes is determined based on the susceptibility, field generated, and shielding effectiveness, a method of determining the probability of failure of the system comprising the steps of: a) determining at least a value corresponding to the electromagnetic coupling between nodes in the critical path; b) determining at least an ambient field value for each nodes in the critical path; c) determining at least a susceptibility value for each node in the critical path; d) determining a probability function which approximates the values in step (a) wherein the probability function is integrated from minus infinity to plus infinity, a resulting integral of the probability function being a positive defined number; e) determining a probability function which approximates the values in step (b) wherein the probability function is integrable from minus infinity to plus infinity, a resulting integral of the probability function being a positive defined number; f) determining a probability function which approximates the values in step (c) wherein the probability function is integrable from minus infinity to plus infinity, a resulting integral of the probability function being a positive defined number; g) locating at least three points on a curve defined by each of the probability functions; h) determining a fuzzy value from the at least three points located in step (g) for each curve; i) performing fuzzy subtraction of the values in step (h) representing shielding effectiveness, ambient field and susceptibility; j) determining a probability function PF(x) of upset or damage of the whole system wherein the probability function is integrable from minus infinity to plus infinity, a resulting integral of the probability function being a positive defined number; k) adjusting the shielding or the system to reduce said positive defined number to an acceptable value.