Abstract: Systems and methods involving engine models are provided. A representative method for updating a gas turbine engine reference model includes: determining whether an absolute difference between a dominant time constant of a sensor and an assumed sensor model time constant is outside a tolerance value; and responsive to determining that the absolute difference is outside the tolerance value, updating the assumed sensor model time constant with the dominant time constant of the sensor.

Abstract: Systems and methods involving engine models are provided. A representative method for updating a gas turbine engine reference model includes: determining whether an absolute difference between a dominant time constant of a sensor and an assumed sensor model time constant is outside a tolerance value; and responsive to determining that the absolute difference is outside the tolerance value, updating the assumed sensor model time constant with the dominant time constant of the sensor.

Abstract: A system and method is described by which the structural integrity of a building or other structure can be increased and made more resistant to earthquake damage. A structural member may be incorporated into a building structure. At least a portion of the structural member is made of a material that undergoes a shape or phase transformation in response to energy applied. This member can alter the natural frequency of the building structure from a first natural frequency to a second natural frequency when the material undergoes the transformation to make destructive resonance less likely to occur.