Digital Commons Network^™

Finite Time Estimation For Time-Varying Systems With Delay In The Measurements, Saeed Ahmed, Michael Malisoff, Frédéric Mazenc

Faculty Publications

We build finite time observers for time-varying nonlinear systems with delays in the outputs, using a dynamic extension that computes fundamental matrices. Our observers achieve finite time convergence when no disturbances are present. When disturbances are present, we provide approximate values for the solutions, which lead to an upper bound on the approximation error after a suitable finite time. We illustrate our work in a class of systems arising in the study of vibrating membranes, where time-varying coefficients can be used to represent intermittent measurements.

Output Feedback Stabilization By Reduced Order Finite Time Observers Using A Trajectory Based Approach, Michael Malisoff, Frederic Mazenc, Saeed Ahmed

Faculty Publications

We use finite time reduced order continuous-discrete observers to solve an output feedback stabilization problem for a class of nonlinear time-varying systems whose outputs contain uncertainty. Unlike earlier works, our feedback is discontinuous, but it does not contain distributed control terms. Our trajectory based approach is based on a contrac-tivity condition. We illustrate our control in the context of a tracking problem for nonholonomic systems in chained form.

On Average Values Of Time-Varying Delays And A New Representation Of Systems With Time-Varying Delays, Frederic Mazenc, Michael Malisoff

Faculty Publications

We show by a counterexample that the asymptotic stability of a system with a pointwise periodic time-varying delay cannot be deduced from the average value of the delay. We use this counterexample to motivate our new representation of systems with time-varying delays, which we use to develop a new state feedback stabilization method.

Blueberry Pectin-Anthocyanin Binding Kinetics And Stability Under In Vitro Digestion, Jee Won Koh

LSU Doctoral Dissertations

Blueberry pectins were sequentially extracted from highbush blueberry powder and precipitated in alcohol to obtain water soluble fraction (WSF) and chelator soluble fraction (CSF). WSF was high methoxyl pectin (degree of esterification: 53), rich in in neutral sugars (40 mol%), and had less negative charge (-21 mV) whereas CSF was low methoxyl pectin (degree of esterification: 21), rich in uronic acids (92 mol%), and had lower negative charge ( -26 mV).

The stability of blueberry pectin-anthocyanin complex was investigated under simulated in vitro digestion. Binding of blueberry pectins with three anthocyanin standards (malvidin-3-glucoside; M3G, cyanidin-3-glucoside; C3G, and delphinidin-3-glucoside; D3G) and …

Reduced Order Finite Time Observers For Time-Varying Nonlinear Systems, Frederic Mazenc, Saeed Ahmed, Michael Malisoff

Faculty Publications

We build reduced order finite time observers for a large class of nonlinear time-varying continuous-time systems. We illustrate our results using a tracking problem for nonholonomic systems in chained form.

Sequential Predictors For Linear Time-Varying Systems With Delays In The Vector Field And In The Input, Michael Malisoff, Frederic Mazenc

Faculty Publications

We provide new sequential predictors for a large class of linear time-varying systems that contain constant delays in the vector fields and also constant delays in the inputs. We allow the input delays to be arbitrarily large. We prove global exponential stability of the origin for an augmented system that includes the original system in closed loop with our sequential predictors based feedback control. We illustrate our new theorem in an example from identification theory.