Fluidization, a relatively new unit operation by which a solid and gas or liquid may be contacted, is being widely developed in the field of catalytic cracking of petroleum because of its characteristic reduction of temperature gradients within the reaction mass. Basic research of the heat transfer properties of fluidized systems has lagged far behind industrial applications. It was the purpose of this investigation to evaluate the effect of temperature driving force and mass superficial air velocity on the coefficient of heat transfer at the bed wall of an externally heated, fluidized bed of Ottawa sand at wall temperature of 200, 400, and 600 °F , and average mass superficial air velocities of 82.5, 123.2, 170.3, and 217.5 pounds per hour-square foot. The tests were carried out under steady state conditions of air flow and bed wall temperature. A complete heat and material balance, including evaluation of heat losses, was made for each test. The boundary coefficients based on the internal area and temperature of the pipe wall were calculated. The effects of mass superficial air velocity and wall temperature on the boundary coefficient of heat transfer and on bed and bed wall temperature gradients were studied. From observations made it was noted that the fluidization range of the Ottowa sand bed began at a mass superficial air velocity of 91.0 pounds per hour-square foot and ended at 210.0 pounds per hour-square foot, the velocity at which slugging occurred throughout the bed. The horizontal temperature gradient across the bed increased with increasing bed wall temperature, increasing from a minimum of 0 °F at 200 °F wall temperature to 6 °F at 600 °F . The rate of heat flux to the air stream passing through the fluidized bed increased with mass air flow rate at constant bed wall temperature. The minimum heat flux was 84 Btu per hour and occurred at 200 °F and 82.5 pounds per hour-square foot, while the maximum was 1172 Btu per hour and occurred at 600 °F and 217.5 pounds per hour-square foot. The coefficient of heat transfer increased with bed wall temperature, reaching maximum values of 9.55, 13.40, 13.31, and 13.30 Btu per hour-square foot-°F at 600 °F and at mass superficial air velocities of 82.5, 123.2, 170.3, and 217.5 pounds per hour-square foot, respectively. / Master of Science

Québec Université Laval, Bibliothèque 2012

La présente recherche vise à faire ressortir certaines particularités chez deux grands penseurs de la Grèce Antique: Protagoras le sophiste et Socrate le philosophe. Le but fondamental de cette étude sera d'établir l'importance de cette maïeutique (la question de l'enseignement de la vertu en relation avec l'art de la citoyenneté) selon ces deux grands penseurs: Socrate ainsi que Protagoras. En effet, le Protagoras de Platon est un ouvrage qui suscite beaucoup de questions, surtout chez certains membres de la communauté philosophique qui s'y intéressent. En revanche, bien que Platon soit la source principale de cette œuvre, il est un témoin peu fiable de l'histoire de la philosophie. C'est la raison pour laquelle cette recherche est essentiellement basée sur l'étude du dialogue du Protagoras de Platon. II serait utile d'explorer d'autres dialogues de Platon afin d'approfondir cette analyse sur la question de l'enseignement de la vertu, mais l'auteur de cet ouvrage a préféré limiter sa recherche à une seule œuvre : Le Protagoras.

Québec Université Laval, Bibliothèque 2016

Cet essai étudie la fonction et le fonctionnement de la figure rimbaldienne dans la première partie de l'œuvre romanesque de Philippe Soupault. Nous formulons, d'une part, l'hypothèse que l'œuvre de Soupault est une lecture de l'œuvre-vie de Rimbaud, et proposons pour le vérifier une étude de la première décennie d'écriture de Soupault, soit de 1917 à 1925. Ce faisant, notre étude met au jour la figure rimbaldienne telle qu'elle apparaît et migre dans les poésies et la prose d'abord; puis étudie son fonctionnement et son évolution dans l'œuvre de Soupault. Plus simplement, il s'agit de voir comment le roman, lieu de représentation du monde, est structuré par une poétique placée sous le signe de l'échec et un idéal de rupture fondé sur le principe d'imitation de Rimbaud. Cette mise en perspective nous permet, à terme, de rendre hommage à une œuvre souvent oubliée derrière celle d'un Breton ou d'un Aragon, et surtout d'en souligner l'originalité et la sensibilité.

The velocity tracking problem is motivated by the desire to match a desired target flow with a flow which can be controlled through time dependent distributed forces or time dependent boundary conditions. The flow model is the Navier-Stokes equations for a viscous incompressible fluid and different kinds of controls are studied. Optimal distributed and boundary controls minimizing a quadratic functional and an optimal bounded distributed control are investigated. The distributed optimal and the bounded control are compared with a linear feedback control. Here, a unified mathematical formulation, covering several specific classes of meaningful control problems in bounded domains, is presented with a complete and detailed analysis of all these time dependent optimal control velocity tracking problems. We concentrate not only on questions such as existence and necessary first order conditions but also on discretization and computational aspects. The first order necessary conditions are derived in the continuous, in the semidiscrete time approximation and in the fully finite element discrete case. This derivation is needed to obtain an accurate meaningful numerical algorithm with a satisfactory convergence rate. The gradient algorithm is used and several numerical computations are performed to compare and understand the limits imposed by the theory. Some computational aspects are discussed without which problems of any realistic size would remain intractable. / Ph. D.

Echo in telephones is generally undesirable but inevitable. There are two possible sources of echo in a telephone system. The impedance mismatch in hybrids generates network (electric) echo. The acoustic coupling between loudspeaker and microphone, in hands-free telephones, produces acoustic echo. Echo cancelers are used to control these echoes. In this thesis, we analyze the Least Mean Squares (LMS), Normalized LMS (NLMS), Recursive Least Squares (RLS), and Subband NLMS (SNLMS) algorithms, and evaluate their performance as acoustic and network echo cancelers. The algorithms are compared based on their convergence rate, steady state echo return loss (ERL), and complexity of implementation. While LMS is simple, its convergence rate is dependent on the eigenvalue spread of the signal. In particular, it converges slowly with speech as input. This problem is mitigated in NLMS. The complexity of NLMS is comparable to that of LMS. The convergence rate of RLS is independent of the eigenvalue spread, and it has the fastest convergence. On the other hand, RLS is highly computation intensive. Among the four algorithms considered here, SNLMS has the least complexity of implementation, as well as the slowest rate of convergence. Switching between the NLMS and SNLMS algorithms is used to achieve fast convergence with low computational requirements. For a given computational power, it is shown that switching between algorithms can give better performance than using either of the two algorithms exclusively, especially in rooms with long reverberation times. We also discuss various implementation issues associated with an integrated echo cancellation system, such as double-talk detection, finite precision effects, nonlinear processing, and howling detection and control. The use of a second adaptive filter is proposed, to reduce near-end ambient noise. Simulation results indicate that this approach can reduce the ambient noise by about 20 dB. A configuration is presented for the real time single-chip DSP implementation of acoustic and network echo cancelers, and an interface between the echo canceler and the telephone is proposed. Finally, some results obtained from simulations and implementations of individual modules, on the TMS320C31 and ADSP 2181 processors, are reported. The real time NLMS DSP implementations provide 15 dB of echo return loss. / Master of Science

Serial or parallel data links have been the primary tools of data transfer across physical layer boundaries for point-to-point communication systems. However there exists a tradeoff between these two kinds of data transfer mechanisms based on their cost-effectiveness and complexity. A recent technological advancement has altered this trade-off considerations. A new chip-set from Advanced Micro Devices offers a high performance integrated alternative to traditional serial/parallel data transfer techniques. The Transparent Asynchronous Transmitter Receiver Interface chipset offers a new means to establish a transparent high speed serial link between two high performance parallel buses. The current TAXlchip set has a maximum effective data rate throughput of 140Mbps which is ten times faster than the RS-422 drivers and receivers. The TAXIchip set can be used in conjunction with the optical components and optical fiber to form a simple fiber optic communication link. The inherent advantages of optical communications can be combined with the versatility of the TAXIchip set to establish TAXI links using optical fiber to cover distances up to several kilometers. This thesis will systematically develop on the TAXI communication system Focus of the effort will be on understanding the functionality of the building blocks of the TAXIchip set and the encoding and decoding schemes of the chip set. On obtaining a complete understanding of the communication system fundamentals the communication system will be interfaced to the optical media with a specific reference to the development of the Optical Slip Ring. / Master of Science

Mathematical representation of military operations have long fascinated analysts and practitioners. In 1916 English mathematician Frederick W. Lanchester represented the attrition rates of two opposing forces in the form of two differential equations, functions of the size and combat effectiveness of each side. Lanchester's model was an intellectual breakthrough in the analysis of warfare insofar as it provided a deep insight into the possibilities inherent in simple models of combat. Interestingly enough, Lanchester's representation of the problem as a dynamic system is precisely the approach used in the system dynamics methodology employed here. In system dynamics, differential equations are converted to difference equations and there is virtually no limit to the number that can be employed to represent the known and complex details of a system. The attrition model developed here describes the interaction between twelve types of U.S. combat aircraft and twelve types of U.S.S.R. combat aircraft and indicates the winner or the loser at the end of an engagement or a battle during wartime. To guide the peacetime preparations, a generic baseline and modified aircraft are utilized and compared using an adaptation of the attrition model, so as to decide if the proposed modification of U.S. aircraft should be undertaken or not. Two measures of effectiveness are presented to evaluate the overall performance of the modified aircraft compared to the baseline aircraft -- decreased program life cycle cost and increased payload delivered to target per aircraft lost. Scenario analyses are performed to assess the combat aircraft effectiveness under changes to endogenous and exogenous parameters. / Ph. D.

Le but de l'étude était d'évaluer le rôle de Pautorégulatlon de la température dans le traitement de la migraine par la rétroaction biologique thermique en la comparant à une procédure tout aussi crédible mais qui ne provoquerait aucun effet significatif sur la température des mains. Vingt-quatre femmes migraineuses ont été assignées à l'une ou l'autre des deux conditions suivantes: la rétroaction biologique thermique ou le TENS (ou stimulation électrique transcutanée). Cette dernière était appliquée de façon à maximiser les attentes thérapeutiques et à minimiser les effets sur la température des mains. La manipulation expérimentale s'est avérée un succès. Cependant, aucune des différences observées entre les groupes au niveau des effets thérapeutiques n'était significative. Il en est de même des corrélations qui furent effectuées entre les changements de température au niveau de la main et l'amélioration thérapeutique. Ainsi, l'hypothèse selon laquelle l'efficacité de la rétroaction biologique serait médiée par l'autorégulation de la température n'est pas supportée dans cette étude.