Appeal No. 1997-3205
Application 08/389,545
defining a distribution of degradation values which surround an expected degradation value at a
particular time point, the method of claim 1 is able to generate an index commensurate with an
uncertainty at each time point, thereby providing data such as shown in appellants’ Figure 5 (see tube
array failure confidence level curves 38 and 40). Accordingly, appellants’ uncertainty index provides
the ability to treat uncertainties in the failure model parameters, as well as the ability to display and
record a distributional presentation of the results with explicit confidence limits (see specification, page
4). As further discussed, infra, we find that the applied references to Clark and Maguire fail to teach or
suggest at least this salient feature as it is recited in the claims on appeal.
Representative claim 1 is reproduced below:
1. A method for generating an index commensurate with a degree to which a tube array
degrades over a period of time due to corrosion in a particular operating environment, comprising:
creating a data array defining a number of tubes in the tube array, a plurality of time points
defining time intervals during which the degradation is to be assessed, and operating conditions that
induce corrosion during each time interval;
computing an expected degradation value of the tube array over each of a plurality of time
points using a deterministic failure model having at least one parameter that is assumed to have a
constant value at each time point;
for each time point generating a plurality of values of said parameter that deviate from said
assumed constant value;
for each time point, computing a plurality of degradation values using said deterministic failure
model with each of said plurality of deviated values of said parameter, thereby defining a distribution of
degradation values at said time point surrounding said expected degradation value at said time point;
and
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