Browsing by Author "Spinello, D."

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    Effects of van der Waals force and thermal stresses on pull-in instability of clamped rectangular microplates
    Batra, Romesh C.; Porfiri, M.; Spinello, D. (MDPI, 2008-02-01)
    We study the influence of von Karman nonlinearity, van der Waals force, and thermal stresses on pull-in instability and small vibrations of electrostatically actuated microplates. We use the Galerkin method to develop a tractable reduced-order model for electrostatically actuated clamped rectangular microplates in the presence of van der Waals forces and thermal stresses. More specifically, we reduce the governing two-dimensional nonlinear transient boundary-value problem to a single nonlinear ordinary differential equation. For the static problem, the pull-in voltage and the pull-in displacement are determined by solving a pair of nonlinear algebraic equations. The fundamental vibration frequency corresponding to a deflected configuration of the microplate is determined by solving a linear algebraic equation. The proposed reduced-order model allows for accurately estimating the combined effects of van der Waals force and thermal stresses on the pull-in voltage and the pull-in deflection profile with an extremely limited computational effort.
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    Nonlinear Estimation with State-Dependent Gaussian Observation Noise
    Spinello, D.; Stilwell, Daniel J. (Virginia Center for Autonomous Systems, 2008)
    We consider the problem of estimating the state of a system when measurement noise is a function of the system's state. We propose generalizations of the iterated extended Kalman filter and of the extended Kalman filter that can be utilized when the state estimate distribution is approximately Gaussian. The state estimate is computed by an iterative root-searching method that maximize a maximum likelihood function. For sensor network applications, we also address distributed implementations involving multiple sensors.