Structural topology optimization has been extensively studied in aeronautical, civil, and mechanical engineering applications in order to improve performance of systems. This thesis focuses on an optimal design of damping treatment using topology optimization, and the reduction of computational expense of the topology optimization procedure. This thesis presents mainly two works on topology optimization. In the first work, topology optimization is implemented to optimally design damping treatments in unconstrained-layer damping material. Since the damping effect relies on the placement of damping treatment, and the weight of damping material may be an important factor, the placement of damping material is optimally determined using topology optimization with an allowable maximum. Unconstrained-layer plate and shell structures are modeled. The damping layer on the unconstrained-layer structures is considered as the design domain. Using topology optimization, the damping layer is designed numerically, and then experimentally validated by comparing the damping effects. In the numerical example, the topological damping treatment usually provides much higher damping effects compared to other approaches such as strain energy distribution (SED) and an evolutionary structural optimization (ESO). In the second work, a numerical algorithm, named as reducible design variable method (RDVM) topology optimization, is proposed in order to efficiently reduce the computational expense. Since it usually requires thousands to millions of design variables and up to hundreds of iterations in topology optimization, the major difficulty is its computational expense. The RDVM topology optimization is implemented into static (minimization of compliance) and dynamic (maximization of the fundamental resonance frequency) problems. The RDVM significantly reduces computing time, as confirmed by numerical examples. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2011-07-08 10:10:20.606

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No description available.

Ce mémoire a pour objectif de comprendre l’impact de la satisfaction envers les régimes de rémunération variable sur l’engagement organisationnel des travailleurs. Pour étudier cette question, nous avons utilisé trois hypothèses basées sur la théorie des attentes ainsi que sur la théorie de l’agence. La première hypothèse stipule que la satisfaction envers les régimes de bonis fait augmenter le niveau d’engagement organisationnel des travailleurs. La deuxième hypothèse est que la satisfaction envers les régimes de partage des bénéfices fait augmenter le niveau d’engagement organisationnel des travailleurs. La troisième hypothèse stipule que la satisfaction envers les régimes d’actionnariat fait augmenter le niveau d’engagement organisationnel des travailleurs. Nous avons utilisé une base de données provenant d’une enquête plus large portant sur « les liens entre la rémunération, la formation et le développement des compétences et l’attraction et la rétention d’employés clés ». L’entreprise où les données ont été collectées œuvre dans le secteur des technologies de l’information et des communications (TIC). Les nouveaux employés embauchés dans cette entreprise établie à Montréal ont été interrogés. Nos résultats nous permettent de confirmer deux de nos hypothèses, soit celle qui concerne les régimes de bonis et celle qui concerne les régimes d’actionnariat. Nos résultats indiquent que les individus satisfaits à l’égard des régimes de rémunération variable, plus précisément envers les régimes de bonis et les régimes d’actionnariat, présentent de plus hauts niveaux d’engagement organisationnel. Le soutien organisationnel perçu est également un facteur important dans le développement de l’engagement organisationnel. Finalement, nous concluons ce mémoire avec l’implication de nos résultats pour les différents acteurs en relations industrielles. / The objective of this study is to understand the impact of the satisfaction with variable pay plans on organizational commitment of workers. To investigate this question, we used three hypotheses based on the theory of expectations and on the agency theory. The first hypothesis states that satisfaction with bonus plans increases the level of affective organizational commitment of workers. The second hypothesis is that satisfaction with profit-sharing plans increases the level of affective organizational commitment of workers. The third hypothesis states that satisfaction with stock ownership plans increases the level of affective organizational commitment of workers. We used a database from a wider survey on "the links between compensation, training and skills development and attracting and retaining key employees." The company where the data was collected is in the field of information technology and communications. New employees hired in this company based in Montreal were interviewed. Our results allow us to confirm two of our hypotheses. Our results indicate that individuals satisfied with variable pay plans, more precisely towards the bonus plans and stock ownership plans, have higher levels of organizational commitment. Perceived organizational support is also an important factor in the development of organizational commitment. Finally, this study concludes with the implication of our results for the different actors in industrial relations.

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This thesis describes work that has been carried out to develop a scaled down laboratory test bed for use in the optimisation of fan driven air ventilation systems found at the various Anglo Coal South African mines. The present system involved in the movement of air underground comprises a fixed speed centrifugal fan driven damper controlled system. National Power Contractors (NPC) together with the University of KwaZulu-Natal (UKZN) proposed a variable speed automated controlled system, but the costs of installing Variable Speed Drives (VSD) and their impact on the energy consumption of a system prior to being installed are important. In addition deliverables required by the industrial partner NPC was to develop a calibrated simulation model where any fan system could be simulated showing potential energy savings. A test bed was therefore constructed to evaluate the power usage of a VSD while driving a simulated fan. The test bed comprised of two Field Oriented Controlled induction machines. A ventilation system at Anglo Coal’s Vlaklaagte colliery was proposed to be simulated by the test bed to develop the Measurement and Verification (M&V) methodology required to represent a business case, but since data from this fan system was not available two other fan systems were studied. One fan system was built at the UKZN whilst the other industrial fan system was at Anglo Coal’s Greenside colliery. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.

Storing the history of objects in a program is a common task. Web browsers remember which websites we have visited, drawing programs maintain a list of the images we have modified recently and the undo button in a wordprocessor allows us to go back to a previous state of a document. Maintaining the history of an object in a program has traditionally required programmers either to write specific code for handling the historical data, or to use a library which supports history logging. We propose that maintaining the history of objects in a program could be simplified by providing support at the language level for storing and manipulating the past versions of objects. History variables are variables in a programming language which store not only their current value, but also the values they have contained in the past. Some existing languages do provide support for history variables. However these languages typically have many limits and restrictions on use of history variables. In this thesis we discuss a complete implementation of history variables in an imperative programming language. We discuss the semantics of history variables for scalar types, arrays, pointers, strings, and user defined types. We also introduce an additional construct called an 'atomic block' which allows us to temporarily suspend the logging of a history variable. Using the mathematical system of Hoare logic we formally prove the correctness of our informal semantics for atomic blocks and each of the history variable types we introduce. Finally, we develop an experimental language and compiler with support for history variables. The language and compiler allow us to investigate the practical aspects of implementing history variables and to compare the performance of history variables with their non- history counterparts.

There is no abstract available for this thesis. / Department of Physics and Astronomy

Cataclysmic variable stars (CVs) are interacting binary systems. One of the stars (referred to as the primary) is a white dwarf, the other (referred to as the secondary) is usually a late main sequence star such as a red dwarf. Due to the closeness of the two stars, the white dwarf accretes gasses from the secondary. If the white dwarf does not possess a strong magnetic field, these gasses go into orbit, forming an accretion disk around the primary. If the white dwarf does possess a strong magnetic field, the gasses cannot form an accretion disk because they are entrained by the magnetic field lines. Cataclysmic variable stars in which the magnetic field is strong enough to prevent the formation of the accretion disk are called AM Herculis-type systems, after their prototype. In this study, the time-resolved spectroscopy of two AM Herculis-type binary systems, QQ Vul and EF Eri, are analyzed. In addition, Doppler Tomography, an analysis technique previously applied primarily to cataclysmic variable stars with accretion disks, is applied to these systems. / Department of Physics and Astronomy