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Design of operable reactive distillation columnsSchenk, Myrian Andrea January 1999 (has links)
Reactive distillation is an integrated process which considers simultaneous physical and chemical transformations. It is increasingly receiving attention both from industry and academia. Significant advances have been made in the area of modelling and simulation as well as the implementation of such units industrially. However, the area of control and optimisation of such units has not been explored thoroughly. The thesis presents a general framework for simulation and design, which can handle reactive and non-reactive systems. Various different aspects of the modelling and simulation of distillation have been described in order to understand the behaviour of the reactive distillation columns. In the framework both simulation modes, steady-state and dynamic, are considered and the process is described by equilibrium and non equilibrium-based models. In a rate-based (or non equilibrium) model, mass transfer rates between liquid and vapour phase are considered explicitly, based on the Maxwell-Stefan equations. Equilibrium is attained at the phase interface in the non-equilibrium model. A switching policy makes it possible to go from one model to the other, based on the knowledge gained, by following the Gibbs free energy as a function of time. Tray efficiency has also helped in determining the switch between the non-equilibrium and equilibrium models, and has been studied for various systems. The existence of multiple steady state has been verified through simulation with the hybrid model. Bifurcation diagrams also confirmed the existence of output multiplicity obtained in the simulations. Analysis of process controllability at the design stage has been shown to provide guidance for improving process operation. In the thesis controllability measures for the reactive systems studied are presented as a first step towards control structure selection. A method for obtaining the design of reactive separation columns at minimum total annualised cost (investment and operating costs) and which will be able to maintain stable operation in the presence of variability is also presented.
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Conditions de bifurcation dans les solides /Hachich, Mohamed. January 1994 (has links)
Th. doct.--Mécanique des solides et des structures--Paris 6, 1994. / Bibliogr. p. 89-92. Résumé en français et en anglais.
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Continuation methods applied to non linear flight dynamics and controlRichardson, Thomas Stuart January 2002 (has links)
No description available.
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Characterisation and suppression of chattering in impacting structuresLee, June-Yule January 1997 (has links)
No description available.
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Existence of periodic travelling waves to reaction-diffusion equations with excitable-oscillatory kineticsHaaf, Hermann January 1993 (has links)
No description available.
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Fundamental flow phenomena in a sudden symmetric expansionFearn, R. M. January 1988 (has links)
No description available.
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Forced convection in curved ducts multiplicity and stability /Liu, Fang, January 2006 (has links)
Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.
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Nonlinear aeroelastic analysis of high aspect-ratio wings using the method of numerical continuationNichkawde, Chetan 16 August 2006 (has links)
This research explores the impact of kinematic structural nonlinearities on the
dynamics of a highly deformable cantilevered wing. Two different theoretical formulations
are presented and analysed for nonlinear behavior. The first formulation, which
is more conventional, assumes zero equilibrias and structural nonlinearities occur as
terms up to third order in the Taylor series expansion of structural nonlinearities.
In the second approach, no prior assumption about equilibria states of the wing is
made. Kinematic nonlinearities due to curvature and inertia were retained in their
exact form. Thus, the former becomes a special case of the latter. This nonlinear formulation
permits the analysis of dynamics about nonzero trims. Nonzero trim states
are computed as a system parameter is varied using a continuation software tool. The
stability characteristics of these trim states are also ascertained. Various bifurcation
points of the system are determined. Limit-cycle oscillations are also investigated for
and are characterized in terms of amplitude of vibration. The research in particular
examines the impact of in-plane degree of freedom on the stability of nonzero trim
states. The effect of variation of system parameters such as stiffness ratio, aspect
ratio and root angle of attack is also studied. The method of direct eigenanalysis of
nonzero equilibria is novel and new for an aeroelastic system.
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Hypersurfaces à courbure moyenne constanteJleli, Mohamed Boussaïri Pacard, Franck. January 2004 (has links)
Thèse de doctorat : Mathématiques : Paris 12 : 2004. / Titre provenant de l'écran-titre.
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Stability and bifurcation in flow induced vibration徐善強, Chui, Sin-keung. January 1997 (has links)
published_or_final_version / Civil and Structural Engineering / Doctoral / Doctor of Philosophy
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