Mark Dzwonczyk

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During the past several years, an AH-1 Cobra aircraft at the NASA Ames Research Center has been instrumented with tri-axial accelerometers and a data acquisition system to support the experimental study of in-flight transmission vibration patterns. This paper describes the on-board HealthWatch system and presents important statistical analyses of the(More)
The development of a reliable helicopter gearbox health monitoring system (HMS) has been the subject of considerable research over the past 15 years. The deployment of such a system could lead to a significant saving in lives and vehicles as well as dramatically reduce the cost of helicopter maintenance. Recent research results indicate that a neural(More)
Many researchers have proposed damage detection techniques that exploit changes in modal parameters to identify the extent and location of damage in large structures. These analyses, however, generally neglect the e ects of environmental changes on modal parameters. Such environmental e ects include changes in loads, boundary conditions, temperature, and(More)
Damage detection techniques have been proposed to exploit changes in modal parameters and to identify the extent and location of damage in large structures. Most of such techniques, however, generally neglect the environmental e ects on modal parameters. Such environmental e ects include changes in loads, boundary conditions, temperature, and humidity. In(More)
A method is proposed to measure the performance of linear predictors as they track non-stationary stochastic processes. Classical linear regression techniques are combined with a novel use of instantaneous error to define the likelihood that the coefficients of a linear predictor adequately capture a system's state. The resultant probability measure serves(More)
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