Sensors are configured to repeatedly monitor variables of a physical
system during its operation. A novelty detection system is responsive to
the sensors and is configured to repeatedly observe into an associative
memory, states of associations among the variables that are repeatedly
monitored, during a learning phase. The novelty detection system is
further configured to thereafter observe at least one state of
associations among the variables that are sensed relative to the states
of associations that are in the associative memory, to identify a novel
state of associations among the variables. The novelty detection system
may determine whether the novel state is indicative of normal operation
or of a potential abnormal operation. Multiple layers of learning for
real-time diagnostics/prognostics also may be provided.