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Full-Text Articles in Mechanical Engineering

Optimal Control Of A Class Of One-Dimensional Nonlinear Distributed Parameter Systems With Discrete Actuators, Radhakant Padhi, S. N. Balakrishnan Jan 2005

Optimal Control Of A Class Of One-Dimensional Nonlinear Distributed Parameter Systems With Discrete Actuators, Radhakant Padhi, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Combining the principles of dynamic inversion and optimization theory, a new approach is presented for stable control of a class of one-dimensional nonlinear distributed parameter systems with a finite number of actuators in the spatial domain. Unlike the existing ''approximate-then-design'' and ''design-then-approximate'' techniques, this approach does not use any approximation either of the system dynamics or of the resulting controller. The formulation has more practical significance because one can implement a set of discrete controllers with relative ease. To demonstrate the potential of the proposed technique, a real-life temperature control problem for a heat transfer application is solved through simulations. …


On The Stability Of Rotor Bearing Systems Based On Hopf Bifurcation Theory, Jianke Wang Jan 2005

On The Stability Of Rotor Bearing Systems Based On Hopf Bifurcation Theory, Jianke Wang

LSU Doctoral Dissertations

This research is aimed to establish instability criteria for a rotor-bearing system which consists of a rotor supported by two fluid-film journal bearings. The static and dynamic characteristics of rotor-bearing systems with consideration of turbulent effects are evaluated by applying the Hopf bifurcation theory (HBT) to the equations of motion. A method is developed for predicting the stability envelope of rotor-bearing systems using HBT. Results are compared with published literature obtained using a trial-and-error method. A method based on HBT is presented for predicting the occurrence of a hysteresis phenomenon, which is observed in experimental results dealing with the instability …