Search
Results
-
Coal characterization for ECBM recovery: Gas sorption under dry and humid conditions, and its effect on displacement dynamics
(2011)Energy Procedia ~ 10th International Conference on Greenhouse Gas Control TechnologiesEnhanced Coal Bed Methane (ECBM) recovery is a technique under investigation as a possible approach to the geological storage of CO2 in a carbon dioxide capture and storage (CCS) system. This technology allows enhancing the recovery of coal bed methane by injecting CO2 in the coal seam at supercritical conditions. Through an in situ sorption/desorption process the displaced methane is produced and the adsorbed CO2 is permanently stored. ...Conference Paper -
The influence of phase separation on the flow patterns of mid-ocean ridge hydrothermal systems
(2008)Geochimica et Cosmochimica ActaConference Paper -
Parallel estimators and communication in spacecraft formations
(2005)IFAC Proceedings Volumes ~ Proceedings of the 16th IFAC World CongressThis paper investigates the closed-loop dynamics of systems controlled via parallel estimators. This structure arises in formation flying problems when each spacecraft bases its control action on an internal estimate of the complete formation state. For LTI systems a separation principle shows that the necessary and sufficient conditions for overall system stability are more stringent than the single controller case; the controllers’ ...Conference Paper -
Asynchronous switching decentralized controllers for spacecraft formations
(2004)IFAC Proceedings Volumes ~ Automatic control in aerospace 2004The spacecraft formation control design problem is specified in terms of the relative positions of all spacecraft in the formation. Each spacecraft controller requires only a subset of the formation relative positions, and can switch asynchronously between many such information subsets, allowing it to replace measured information by information communicated from other spacecraft. A two dimensional simulation example is used to illustrate ...Conference Paper -
Nonlinear functional characterizations of uncertainty in model validation
(2002)IFAC Proceedings Volumes ~ Proceedings of the 15th IFAC World CongressModel validation provides a useful means of assessing the ability of a model to account for a specific experimental observation, and has application to modeling, identifi- cation and fault detection. In this paper we consider a new approach to the linear fractional transformation (LFT) model validation problem by deploying quadratic functionals, and more generally nonlinear functionals, to specify noise and dynamical perturbation sets. ...Conference Paper -
Emissions and performance tradeoffs for advanced marine diesel propulsion
(1998)IFAC Proceedings Volumes ~ Control applications in marine systems : a proceedings volume from the IFAC conferenceA multivariable control scheme is designed that reduces smoke generation on an experimental marine Diesel engine equipped with a variable geometry turbocharger (v). The variable geometry turbocharger allows the improvement of the steady-state ship hydrodynamic and propulsion characteristics and requires coordination with the injected mass fuel to achieve a good transient performance.Conference Paper -
Capturing nonlinearities with perturbation models
(1997)IFAC Proceedings Volumes ~ IFAC Symposium on System Identification (SYSID'97)This paper investigates the use of robust control perturbation models for describing nonlinear systems. We use model validation techniques to find the smallest linear dynamic perturbation required to describe a particular behaviour of a nonlinear system. The Moore-Greitzer model of rotating stall in jet engines is used as a detailed example.Conference Paper -
Control-oriented model validation
(1997)IFAC Proceedings Volumes ~ IFAC Symposium on System Identification (SYSID'97)Model validation is a means of assessing model quality with respect to experimental data. In a robust control context this amounts to determining whether or not a perturbation model is consistent with observed data. T his paper offers a survey of recent results on model validation for H-infinity compatible perturbation models. Several model paradigms and experiment frameworks are considered. The first is a frequency-domain setting for ...Conference Paper -
The stability analysis of sampled-data systems with averaging samplers and time delays
(1996)IFAC Proceedings Volumes ~ Proceedings of the 13th World CongressAn exact analysis of the stability of a sampled-data feedback loop, involving an averaging sampler and continuous-time delays, is presented. An equivalent discrete-time model is derived and it is shown that the continuous-time behaviour at frequencies greater than the sample frequency can significantly affect the system stability, leading to counterintuitive analysis results. An optical fiber link synchronization application is studied ...Conference Paper -
Modeling and Control of a Metalorganic Chemical Vapor Deposition Process for III-V Compound Semiconductor Epitaxy
(1996)IFAC Proceedings Volumes ~ Proceedings of the 13th World CongressReal-time control of metalorganic chemical vapor deposition (MOCVD) processes has been shown to improve the composition and thickness precision in the growth of compound semiconductor films. A system model of the MOCVD process is developed to improve the application of control. The model is used to simulate growth of GaInAs. Estimates of the GaAs fraction, from simulated growths, are compared to measured composition results. The model ...Conference Paper