Novelty detection

A method for detecting an abnormality in an apparatus or system including:

• providing a data sample set comprising a plurality of values of a measured physical parameter associated with the apparatus or system generated by repeating a measurement of the physical parameter a plurality of times;
• selecting an extremal measured parameter value from amongst the sample set;
• determining a probability of observing the selected parameter value by applying the selected parameter value to a probability distribution function comprising a weighted sum of a plurality of extreme value probability distribution functions each having a location parameter and a scale parameter wherein the value of the location parameter and the value of the scale parameter are determined according to an estimation of the probability thereof;
• conditionally indicating that the selected parameter value is abnormal according to the value of said probability of observing the selected parameter value.

Apparatus for detecting an abnormality in an apparatus or system including:

• data acquisition means for acquiring a data sample set comprising n (n=integer) values of a measured physical parameter associated with the apparatus or system generated by repeating a measurement of the physical parameter n times;
• selector means for selecting an extremal measured parameter value from amongst the data sample set;
• calculation means for determining a probability of observing the selected parameter value by applying the selected parameter value to an extreme value probability distribution function having a location parameter and a scale parameter wherein the value of the location parameter and the value of the scale parameter are each constructed using an integer value m (e.g. notionally representing the size of a sub-sample data set comprising m of said measured parameter values) in which m is less than n (i.e. m<n);
• indicator means for conditionally indicating that the selected parameter value is abnormal according to the value of said probability.

Apparatus for detecting an abnormality in an apparatus or system including:

• data acquisition means for acquiring a data sample set comprising a plurality of values of a measured physical parameter associated with the apparatus or system generated by repeating a measurement of the physical parameter a plurality of times;
• selector means for selecting an extremal measured parameter value from amongst the sample set;
• calculation means for determining a probability of observing the selected parameter value by applying the selected parameter value to a probability distribution function comprising a weighted sum of a plurality of extreme value probability distribution functions each having a location parameter and a scale parameter wherein the value of the location parameter and the value of the scale parameter are determined according to an estimation of the probability thereof;
• indicator means for conditionally indicating that the selected parameter value is abnormal according to the value of said probability of observing the selected parameter value.