title: Electrohydrodynamic (EHD) Droplet Formation, Dispersion and Mass Transfer in a Vicous Dielectric Liquid

contributor:
Baird, Malcolm H.I.
Chang, Jen-Shih
Chemical Engineering

subject:
Chemical Engineering
Engineering
Chemical Engineering

abstract:
Electrohydrodynamics (EHD) is an interdisciplinary engineering science which has been known for more than a century and has been more intensively developed in the last two decades with the concern of the interaction between electric fields and fluids. The investigations of EHD droplet formation, dispersion and mass transfer in a viscous dielectric liquid are the main subjects of study for mass transfer enhancement in liquid-liquid extraction operations by an imposed DC electric field.

The droplet formation and dispersion of water in a high viscosity mineral oil have been studied at the conditions of low droplet Reynolds numbers with and without the presence of an electric field. The droplets formed at a hollow electrode with uniform size and spherical shape have been observed; the droplet size reduction and mutual repulsion can be controlled by the applied voltages. The droplet velocity near the hollow electrode is also significantly enhanced in the presence of the non-uniform DC electric field. The model for EHD droplet formation has been derived with the inclusion of electric force component based on the force balance upon droplet detachment from the hollow electrode.

Mass transfer of benzoic acid from droplets in this two-phase liquid-liquid system has been studied with and without the presence of an imposed DC non-uniform electric field. Total mass transfer efficiency can be significantly enhanced in the presence of the applied electric field. The results obtained from droplet mass transfer investigation indicate that the mass transfer mechanisms of these electrically charged droplets during the droplet formation and its subsequent free fall are similar to those of droplets in the absence of the electric field and these results can be correlated using the existing mass transfer models. The increased specific interfacial area and the accelerated drop initial velocity in the presence of electric field are the main contribution to the enhanced efficiency of mass transfer in the present investigation.

In parallel to the experimental investigations, the numerical modelling of electric field profiles inside the experimental cell has been performed based on the axial symmetric approximation and with the appropriate coordinate transformations. A finite difference algorithm with the control volume approach has been used to conduct numerical calculations. The numerical results obtained from the electric field profiles and predictions of the EHD force components on the droplet can provide much useful information to support the results obtained from the experimental investigation.

The mechanisms of electric field induced current flow and electrification of droplets during EHD droplet formation and dispersion have been postulated and discussed based on the observed current-voltage characteristics of the system, the electric charge acquired by the droplet and the results from numerical electric field modelling.

The mechanism of EHD droplet formation and dispersion from hollow electrode is proposed based on the modified Vonnegut & Neubauer model where an effective dielectric constant of a liquid-liquid two phase system has been defined. The electrically charged droplets formed at hollow electrode under high electric field intensity would all reach their maximum charge limit which determines and controls the uniform size of dispersed multi-droplets. Then the EHD force generated at high electric field intensity would contribute to the dispersion and acceleration of these electrically charged droplets. Thus the initial velocities of these droplets are significantly enhanced.

abstract: Doctor of Philosophy (PhD)


title: The Artist as Critic: Bi-Textuality in Fin-De-Siècle Illustrated Books

contributor:
King, James
English

subject:
English Language and Literature
English Language and Literature

abstract:
The thesis is an interdisciplinary study of first edition illustrated books produced in England at the fin de siècle, and offers new approaches both to illustration theory and to critical interpretation of late Victorian representations. The focus on first editions ensures that the illustrator is the first reader of the text, and that the artist and writer produce their work within a common context. I examine the ways in which the artist as first reader of the author's words provides a critical text for the verbal, and also the ways in which the reader of this bi-textual product is affected by, and participates in, this dialogue between texts. Taking as my premise that all art is discourse-specific, I examine the image/text/reader dialogue as it engages in the larger cultural conversation in which it is embedded. My examination of the bi-textual relationship of the female-coded image and the male-coded word offers a new point of entry into the fin de siècle. Working with a Bakhtinian dialogic model, I develop a rhetoric of illustration for five different image/text relations: Quotation, impression, parody, answering, and cross-dressing.

Three prevailing discourses which motivated the production of the nineties' illustrated book, and the ideologies underlying each, are examined for their contribution to the image/text dialogue: the languages of journalism, aestheticism, and socialism. Each language is found to have a model for the illustrated book, a model underwritten by social relationships and expressed in specific artistic forms and literary styles. The "quotational" model for the illustrated book, as represented by The Memoirs of Sherlock Holmes, is ideologically-driven by the discourse of journalism, and expressed in the interart forms of the representational picture and the realistic adventure story. The "impression" and "parody" models for illustrated books, as represented by The Sphinx and Salone, are produced by the individualistic discourse of aestheticism, and their dialogic relationship is constituted by the interaction of art-nouveau decorations and poetry or poetic drama. The "answering" model, as represented by The Well at the World's End, is produced by the communal aesthetic of socialism, and its interart form is expressed in the medieval-inspired arts-and-crafts design as it interacts with the folkart revival of the romance, the legend and the ballad. "Cross-dressing" constitutes a unique category in which image and text are produced by the same poet/artist, as represented by All-Fellows: Seven Legends of Lower Redemption; its underlying desire for "organic wholeness" illuminates the fin-de-siècle crisis of gender identity, social relations, and authority.

abstract: Doctor of Philosophy (PhD)


title: X-ray Scattering Study of the Spin-Peierls Phase Transition

contributor:
Gaulin, B. D.
Physics

subject: Physics Physics

abstract: Scattering techniques are an essential tool in the experimental study of properties in the vicinity of a critical phase transition. Such techniques have been aplied to the study of the spin-Peierls transition in pure and doped samples of CuGeO₃ and in the organic compound MEM(TCNQ)₂. The spin-Peierls phase transition occurs in one-dimensional S-1/2 Heisenberg spin chains with short-range, antiferromangetic interactions. Such a system is unstable against a dimerization of the chains with the subsequent appearance of a gap in the magnetic excitation spectrum. Such a gap acts to lower the magnetic energy in the system and, in the presence of coupling with the lattice, causes phase transition to a dimerized, spin-Peierls, state. High temperature stability measurement of the order parameter associated with this transition in the inorganic compound CuGeO₃ indicate a continuous phase transition at a temperature of 14.05 K with a corresponding critical exponent β of 0.345±0.03. This value is in agreement with conventional 3D univerality and in closest agreement with 3D XY behaviour. We also observe a narrow as asymptotic critical region which is largely responsible for the inconsistency in previously reported results. High resolution measurements of relative lattice constant changes, performed using a novel approach, indicate spontaneous strains which scale with the square of the order parameter expect near the transition temperature where differences are observed. Similar order parameter measurements were performed on samples of CuGeO₃ doped with Zn, Si, and Cd. For the case of Zn and Si doping, we obtain and exponent β consistent with that for the pure material. Measurements on two Cd doped samples indicate results which clearly deviate from that observed in pure CuGeO₃ with an exponent β of about 0.5 consistent with mean field behaviour. We explain this change in behaviour as resulting from local strains induced by the presence of the much larger Cd²⁺ dopant ion. Relative lattice constant measurements indicate spontaneous strains which scale with the square of the order parameter for the doped samples as was the case for pure CuGeO₃. X-ray scattering measurements of both the order parameter and critical scattering in the vicinity of the transition temperature have been performed for the organic spin-Peierls compound MEM(TCNQ)₂. Order parameter measurements indicate a value of the exponent β 0.35±0.06 consistent with 3D universality, as was observed in the inorganic spin-Peierls material CuGeO₃, and inconsistent with previous measurements which suggested mean-field behaviour. Critical scattering measurements suggest a lineshape not described by a traditional Ornstein-Zernike, Lorentzian, form but well described by a Lorentzian with a varying power or a Lorentzian + Lorentzian². The latter form is reminiscent of recent x-ray scattering measurements of critical phenomena associated with structural phase transitions in perovskites or with magnetic x-ray scattering measurerments on Ho, Tb, and some U-based compounds. Differences between this and previous measurements are discussed.

abstract: Doctor of Philosophy (PhD)


title: A Methodology for Investigating the Energy Use of Proposed Residential Development

contributor:
Burghardt, A. F.
Geography

subject: Geography Geography

abstract:
This thesis tests the feasibility of developing a methodology for investigating the energy use of proposed residential development. Recent experiences with energy impact assessment are examined, methods for predicting energy use and energy savings are identified, and applicable principles from environmental impact assessment are examined. It is determined that current energy evaluation procedures could be improved, based upon principles for developing assessment methodologies that have arisen from environmental impact assessment experience. Predictive methods are deemed necessary for forecasting the energy use of the proposed development and for predicting energy savings and greater energy efficiences that could be achieved through various measures. An examination of predictive methods and energy saving measures indicates that not all supposed energy saving methods can be substantiated.

A new methodology is proposed which incorporates the principles of accuracy and objectivity and the need to quantify energy use and energy savings before changes to the development are required. This test reveals that, although there are currently limitations to data, the methodology could highlight means for potential energy savings, as well as illustrate some changes to conventional development practices that could be lead to changes in spatial relationships and built form.

abstract: Master of Arts (MA)


title: Use of Expresser Cell Lines to Functionally Characterize the Herpes Simplex Virus Transcription-Activating Protein ICP4

contributor:
Bacchetti, Silvia
Medical Sciences

subject:
Medical Sciences
Herpes Simplex Virus

abstract: During Herpes Simplex Virus type 1 (HSV-1) infections, many viral proteins are synthesized and several have proven or suspected roles in regulating viral gene expression. To facilitate the study of the individual activity of one such protein, ICP4, the ICP4 gene was cloned in a plasmid vector, and expresser cell lines containing 5-30% of infected cell levels of ICP4 were established. The ICP4 is functional, correctly processed, and located in the cell nuclei. The endogenous ICP4 gene retained its capacity to respond to viral trans-acting factors, since its expression after superinfection with HSV-2 mimicked that of the viral gene. Although cells infected with lCP4 mutant viruses overproduce ICP4 and other immediate-early proteins, cell lines synthesizing a mutant form of ICP4 did not overproduce this protein, suggesting that autoregulation of the lCP4 gene requires more than 30% of the infected cell level of ICP4 or, alternatively, requires the presence of other viral proteins. After superinfection in the presence of an inhibitor of protein synthesis, the endogenous ICP4 is capable of transactivating viral early genes encoding thymidine kinase, lCP6, ICP8, gB, gD, and gE. In contrast, the early gene for the viral alkaline exonuclease, the early-late gene for VP5 and the late genes for p40 and gC, respond poorly or not at all. This demonstrates that most early genes can be induced by ICP4 in the absence of other viral immediate-early proteins, but that early-late and late genes require supplementary factors.

abstract: Doctor of Philosophy (PhD)


title: Strain-dependent phenotype of p130- and p107-deficient mice

contributor:
Rudnicki, Michael A.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: For the development of many cell types, terminal differentiation and continued cell cycle progression are incompatible processes. Rb, p107 and p130 comprise a gene family encoding transcriptional regulators that act within a complex network to control exit from, and progression through the cell cycle. The distinct requirements for p130 and p107 were assessed in vivo using homologous recombination in embryonic stem (ES) cells. p130 expression is ubiquitous, although the level of expression varies between tissues. As well, its induction during neuronal cell differentiation is consistent with p130 function accompanying terminal differentiation. p130 deficiency was incompatible with embryo survival in the hybrid 129Sv;Balb/c genetic background. The mutant embryos died between E11-13 and exhibited striking delays in growth and development at 10.5 dpc with specific deficits in neurogenesis, somitogenesis and cardiogenesis. p130 appears to be required for the maintenance and survival of specific cell types, most notably neuronal cells. The data indicate that the p130 gene is essential for normal development, but in a strain-specific manner. On a hybrid 129Sv;C57B1/6 background, the p130 mutants exhibited no phenotype. The p107 mutants were viable and fertile, indicating that p107 function was adequately compensated by other proteins during development, potentially Rb and p130. The p107-/- mice did however exhibit a postnatal growth deficit and a diathetic myeloid proliferative disorder. The accelerated proliferation and cell-cycle kinetics of p107-/- EF indicated that p107 functions, in part, to regulate cyclin expression and cell cycle progression. p107-/- myoblasts also exhibited accelerated prliferation and aberrant in vitro differentiation. Lastly, the p107-/- phenotype was also dependent on the genetic strain, indicating the presence of modifying genes. The mice produced in these studies can be assessed for genes that modify the phenotypes in these different strains, potentially revealing epistatic relations to p107 and p130. Although both striking and subtle cell-specific phenotypes were exhibited, these experiments strongly reconfirm that functional overlap and compensation exist within the Rb family. The overlapping expression patterns and apparent functional relations indicate that p130, p107 and Rb regulate transitions in a concerted manner during cell proliferation, and cell cycle exit and entrance.

abstract: Doctor of Philosophy (PhD)


title: Metaphor, Ritual, and Expression: The Person in Rauto Discourse and Ritual Practice

contributor:
Cooper, Matthew
Anthropology

subject: Anthropology Anthropology

abstract: This thesis discusses the relationship between religious phenomenology and the understanding of speech, and of person which is held by the Rauto, a tribal group of Southwest New Britain, Papua New Guinea. The first two ethnographic chapters of the thesis consist of an analysis of Rauto understanding of (1) the "structures of the person"; and (2) a formal genre of speech called amala wauluke which constitutes an extended commentary on notions of person, language and human agency. In the chapters I establish the notion that, in Rauto understanding, speech and song shape experience by both expressing and shaping the nature of the person. The next two chapters discuss a category of ritual and of song which Rauto call aurang. Aurang is performed during female and male initiation, and during the collective planting of large gardens of taro. The rituals and songs are said to prompt the growth of young men and women, as well as to enhance the growth of the taro crop. During these ritual events the notion that speech and song both express and effect the physical and moral nature of human beings is literally performed. I conclude the thesis by discussing how concepts of human agency and of person color aspects of the Rauto experience of time, place and the life of society. The thesis reflects a general change in interpretive anthropology's understanding of culture. It is shaped by the view that culture is composed of many different forms of discourse, rather than by many different systems of symbols. In the course of the work I suggest that the view of culture as discourse can make it easier to explain the seeming paradoxes and ambiguities of belief, most especially about order and disorder. The particular contribution of the thesis is to suggest a particular way of looking at the relationship between a people's understanding of the nature of language, and its moral imagination. I argue that Rauto views of language represent ways of interpreting the moral nature and capabilities of people.

abstract: Doctor of Philosophy (PhD)


title: Far-Infrared Fourier Transform Spectroscopy of NTD Ge and GeᵪSi₍₁_ᵪ₎/Si Heterostructures

contributor:
Timusk, T.
Berezin, A.A.
Physics

subject: Physics

abstract:
Far-infrared Fourier transform spectroscopy is used to investigate the excited states of impurities in semiconductors. Two different research projects are presented. The first involves an investigation of the far-infrared absorption of compensated p-type Ge at a temperature of 3 K. The abosorption mechanism which is of interest is due to photon-induced hopping transitions of charge carriers between impurity centers. The samples were prepared by neutron transmutation doping (NTD). It is found that the absorption spectra for samples with carrier concentrations (Na - Nd) ranging from 2.3x10¹⁵ to 2.6x10¹⁶ cmˉ³ show a broad absorption with the maximum occuring at a frequency between 10 and 24 cmˉ¹. The absorption coefficient of this maximum ranges between 2 and 87 cmˉ¹. The dynamical change of absorption due to the evolution of the Ga impurity is also presented. The absorption and the frequency of its maximum increase asymptotically with respect to time. It is found that at low frequencies, the absorption coefficient is proportional to frequency. The overall behavior of the absorption spectra is found to be consistent with a theory based on the localized pair model. E. Kaczmarek and Z. W. Gortel have theoretically predicted a sharp peak at 20.4 cmˉ¹ on the absorption curve. Its position is independent of the compensation or the impurity concentration of the sample. However, this peak has not been observed in the experimental absorption spectra.

The second project involves the investigation of shallow impurities in selectively boron-doped GeᵪSi₍₁_ᵪ₎/Si strained-layer heterostructures using far-infrared photothermal ionization spectroscopy (PTIS). The spectra are obtained under various experimental conditions: with and without band-edge light and by varying the temperature of, and voltage applied to, the sample. The transport properties: resistivity, sheet charge density and Hall hole mobility of these samples are presented. It is found that a sample with a two-dimensional hole gas (2-DHG) behavior at the GeᵪSi₍₁_ᵪ₎/Si interface has a weak photoresponse. This is due to the small number of photogenerated carriers in comparison with the residual hole carriers. For samples which do not show 2-DHG behavior, the photoresponse from the substrate plays the dominant role for low applied voltages. At higher voltages, the response from the epitaxial layers becomes evident. The majority impurity was identified as the intentional dopant boron and the dominant minority impurity was found to be phosphorus. It is concluded that although the free carriers are generated in the heavily B-doped layer, those carriers conducted through the low energy, high mobility GeᵪSi₍₁_ᵪ₎/Si interface layer, will dominate the photoresponse.

abstract: Doctor of Philosophy (PhD)


title: Establishing the role of Pea3, an ETS family transcription factor, during mouse embryonic development

contributor:
Hassell, J.A.
Biology

subject: Biology Biology

abstract: PEA3 is an ETS family transcription factor and the founding member of the PEA3 group which consists of two other PEA3 related proteins, ERM and ER81. They share ~95% amino acid identity within their DNA binding domains and ~50% a.a. identity outside of this region. The goal of this study was to identify the role of PEA3 during mouse embryogenesis. In order to achieve this objective, two complementary approaches were employed. Firstly, the embryonic expression pattern of PEA3 was determined by the whole mount in-situ hybridization from mid-gastrulation through early organogenesis. The Pea3 mRNA was detected in tissues derived from all three germ layers. The sites of expression correlated with regions of embryonic induction, a process governing tissue differentiation, morphogenesis and organogenesis. This study revealed that PEA3 was expressed during gastrulation, patterning of the CNS, neural differentiation, craniofacial development, muscle development, kidney development and limb development. Secondly, we employed a gene knock-out strategy to define the essential functions of PEA3 either during embryogenesis and within the adult mouse. Pea3 proved dispensable for embyogenesis. Expression analysis of both ERM and ER81 revealed that ERM may have provided redundant functions in Pea3 null embryos. However, the male null mice were infertile. Furthermore, female null mice exhibited vastly reduced arbortization of the ductal tree within the developing mammary gland. Hence, this study revealed that PEA3 was required for male fertility and ductal morphogenesis of the mammary gland.

abstract: Doctor of Philosophy (PhD)


title: The Optical Properties of Tissues and Light Dosimetry at 633 Nanometers

contributor:
Wilson, Brian C.
Physics

subject: Physics Physics

abstract:
The goal of the research presented in this thesis is to improve the state of light dosimetry in tissue. Dosimetry with light at and near a wavelength of 632.8 nanometers will be of primary concern as such light is commonly used in photodynamic therapy, which is an experimental form of cancer treatment.

The research described in this thesis was done in three steps. Firstly, in order to determine the regime of optical interaction coefficients appropriate to the problem, the coefficients of representative tissues at 632.8 nm were measured directly: in other words, without using a model of radiation transport in the data analysis. Secondly, in order to ascertain the strengths and weaknesses of two models of radiation transport, calculations from diffusion theory and Monte Carlo theory, of several bulk optical features of tissue-like media, were compared. Finally, the appropriateness of the Monte Carlo method for modelling the propagation of light in tissue was shown by comparing theoretical predictions of fluence and diffuse reflectance in tissue-like phantom media with experimental results.

abstract: Doctor of Philosophy (PhD)


title: Boolean Techniques in Discrete Optimization and Expert Systems

contributor:
Siddall, J.N.
Mechanical Engineering

subject:
Mechanical Engineering
Mechanical Engineering

abstract:
This thesis is devoted to applying Boolean methods to investigate more efficient methodologies for discrete optimization and expert systems; both are based on "binary decision".

An efficient nonlinear 0-1 programming algorithm is proposed, which relies mainly on logic analysis applied to the prime implicants generated iteratively from the constraint system. A general method for design optimization with discrete variables is also developed, for which the basis is an accurate neighborhood search procedure based on Boolean operation.

A new methodology for designing and implementing rule based expert systems using Boolean methods is proposed. This consists of a consensus based algorithm for converting a set of rules to a minimal Boolean form, together with a new control algorithm for rapidly minimizing the evidence set required for a solution. These algorithms have considerable potential for simplifying systems, and speeding up the execution, which would be highly desirable for real time systems where high speed is vital.

A procedure for building an expert system on a VLSI chip has been presented. An Erasable Programmable Logic Device (EPLD) is used to "hard wire" the logic rules represented by Boolean expressions on a microchip. The result is an extremely fast system with considerable promise for control applications, and also in other systems where size and speed are important performance characteristics.

abstract: Doctor of Philosophy (PhD)


title: Coping with Grief: Survivors of Murder Victims

contributor:
Miall, Charlene E.
Sociology

subject: Sociology Sociology

abstract: The following study investigates the coping strategies of individuals bereaved by homicide. In contrast to the traditional medical and stage models of grief, which typically inculcate the bereaved into passive roles, and legal institutions, which cast them into the role of "victim," this research conceptualizes these "survivors" as active agents having choices and abilities that can help them cope. Following a review and critique of survivors' traditional position according to legal and medical professionals, a theoretical model was developed that conceptualized bereavement as a loss of the self. However, the part of the self remaining contains gender role prescriptions that, along with survivors' subsequent social interactions and choices in various social and institutional contexts, reconstitute their self identities in active or passive coping forms. By reviewing qualitative data comprised of 32 interviews, 22 surveys, and 108 homicide files from the Ontario Criminal Injuries Compensation Board, the various dimensions of survivors' loss of self were elaborated, and various situations reviewed that not only reportedly helped or hindered their gried, but interactionally reconstructed their identities in passive or active forms. Significantly, survivors' coping strategies were reviewed in these various contexts, and often observed to vary considerably by gender. In the end, survivors who reportedly fared worse were observed to become involved, through a combination of adherence to traditional gender role prescriptions, upsetting social interactions, and various coping choices, in gender-specific grief cycles that not only impeded their coping for often extended periods of time, but often recast their identities as "victims." On the other hand, survivors reportedly faring better did not exhibit behaviors indicative of traditional gender roles, engaged in and experienced helpful social interactions, and chose to balance not only their focus on their selves and others, but to alternate their grieving with distracting activities enabling them to work through their pain gradually and cope under the circumstances as "survivors." The results of this effort not only extend the sociological study of bereavement to a new substantive context, but have implications for the literature on gender, agency, self, and deviance.

abstract: Doctor of Philosophy (PhD)


title: Development and Individual Differences in Children's Reading Comprehension

contributor:
Levy, B.A.
Psychology

subject: Psychology Psychology

abstract:
This thesis research focused on the contributions of word decoding from print and of reliance on story organization to children's story comprehension. Two experiments were conducted, whose findings contribute to our understanding of developmental and individual differences in reading comprehension. In Experiment 1, children in Grades 3 to 6 read silently, read orally, or listened to well-organized and poorly organized stories. Both amount recalled and reliance on text organization increased with grade. Listening, which required no analysis of print, yielded equivalent comprehension to silent reading, demonstrating that differences in reading comprehension cannot be attributed only to differences in word-decoding skills. Furthermore, oral reading which required the decoding of each word in text, improved the comprehension and recall of good stories, especially for the poorest comprehenders. At each grade level a group of poor readers was identified who showed little sensitivity to story organization, in either silent reading or listening.

In the second experiment, the nature of the oraI-reading benefit was examined by having Grade 6 poor readers read well-organized and poorly organized stories silently and aloud. The experiment showed that oral reading increased recall for well-organized, but not for poorly organized text. This finding suggests that oral reading served to increase text organization, rather than to direct attention to the word level. The poorest comprehenders also gained from an advance organizer that stressed the problem structure of the stories.

The first experiment identified children in each grade, up to Grade 6, who did not spontaneously rely on story organization in reading and remembering stories. The second experiment showed, however, that when story organization was made available and salient, such children were able to use it to help them read and remember stories. Finally, the results of Experiment 2 demonstrated the importance of specific diagnosis prior to developing treatment programs for poor readers.

abstract: Doctor of Philosophy (PhD)


title: Study of Gas-Liquid Two-Phase Flow Pattern Transitions in Horizontal Pipe, Annulus and Nuclear Fuel Type Rod Bundle Flow Systems

contributor:
Chang, J.S.
Nuclear Engineering

subject:
Nuclear Engineering
Nuclear Engineering

abstract:
The ability to predict the flow patterns and flow pattern transitions in a two-phase flow process is useful for an accurate prediction of the pressure drop, heat and mass transfer rates, and also for the choice of appropriate two-phase flow design parameters for the system. During a loss of coolant accident (LOCA) in a nuclear reactor, two-phase flow may exist in the primary heat transport loop, and a knowledge of the flow patterns that are occurring at the various flow conditions is needed to accurately model the accident scenario.

Horizontal gas-liquid two-phase flow patterns and flow pattern transitions have been investigated both theoretically and experimentally for a pipe of 5.08 cm i.d., annulus geometries of outer tube diameter 5.08 cm i.d. and inner-to-outer diameter ratios from 0.375 to 0.625, and for a 37-rod nuclear fuel type bundle flow system having an outer tube diameter of 10.16 cm i.d. and rods of diameter, 1.27 cm. The 28-rod bundle flow geometry was also studied theoretically. The flow conditions were at inlet pressures of about 1 to 2 bar and at near room temperature.

In this study, the time averaged void fraction and pressure drop measurements were also successfully obtained. The instantaneous and time averaged void fraction measurements were achieved by the ring type capacitance transducers based on the differences in the dielectric constants of the liquid and gas phases. The various flow patterns occurring in the pipe, annulus and rod bundle flow systems were successfully characterized by direct visual observation through the transparent test sections and also from the signal waveforms of the instantaneous fluctuations in the void fraction, the pressure drop measurements and the ultrasonic transmission waveforms. Flow pattern transitions were determined from both the results of the measured void fraction and direct visual observation.

The experimental results show that the flow pattern structures occurring in horizontal annulus and rod bundle geometries are similar to those observed for the pipe flow case, except the annulus flow system where we characterized two additional flow patterns, namely, "Annulus-Slug" and "Annulus-Plug". These flow patterns are similar to the Slug and Plug flow structures observed for the pipe geometry, but are restricted to the lower annulus channel gap below the annulus rod. These occur at the flow conditions that would otherwise lead to Stratified flow patterns for pipe flow cases.

The results show that the flow pattern transitions for the annulus and rod bundle flow geometries are significantly different from those of the normal pipe flow. The flow pattern transitions for the annulus flow geometries were observed to be significantly influenced by different inner-to-outer diameter ratios, except the Stratified Smooth to Stratified Wavy transition. The Stratified to Intermittent and the Intermittent to Dispersed Bubble transitions occur at lower superficial liquid velocities, while the Intermittent to Annular transition occurs at higher superficial gas velocities for larger inner-to-outer diameter ratios. In the rod bundle geometries, the flow pattern transitions were observed to vary slightly with the particular angle of orientation of the bundle within the enclosing tubeshell. The various influences on the flow pattern transitions observed in the present study are mainly due to the differences in geometries and force distributions.

From direct visual observation results, we also observed that interfacial waves in the rod bundle flow geometry were generated and dissipated at the rod bundle end plates. No significant effect of the rod bundle end plates on the other flow patterns was observed, except a slight effect on the regularity of these intermittent flow patterns, usually becoming more apparent at higher flow rates.

abstract: Doctor of Philosophy (PhD)


title: Peroxide Degradation of Polypropylene during Reactive Extrusion

contributor:
Vlachopoulos, J.
Hamielec, A. E.
Chemical Engineering

subject:
Chemical Engineering
Chemical Engineering

abstract:
The production of controlled-rheology polypropylene polymers by means of peroxide initiated degradation during reactive extrusion has been studied experimentally and numerically. Experiments were carried out using various amounts of a peroxide to promote chain scission reactions for the purpose of modifying the molecular weight distribution of commercial isotactic polypropylene resins. Experimental runs were carried out in a single screw plasticating extruder and in glass ampoules. The polymers produced were evaluated in terms of their molecular, rheological and mechanical properties. During the extruder runs the residence time distribution in the extruder screw channel was measured by using a radioactive tracer technique in order to study the effects of peroxide concentration, barrel temperature and screw speed.

A fully-predictive mathematical model was developed for the peroxide degradation of polypropylene in a single-screw plasticating extruder. The model was developed using conventional plasticating extrusion theory and a simple set of chemical reactions which caused chain scission. The interactions of the flow and reaction phenomena were taken into account via residence time distribution and the chemorheology of the reactive melt. The model includes several submodels for the flow of solids in a feed hopper, flow in the solids conveying zone of the extruder, melting of the polymer, flow and reaction in the melt pumping zone and in the die region. Given the operating conditions and the geometrical configuration of the screw, the model can predict: the mass flow rate of the polymer, the pressure, temperature and molecular weight profiles along the screw channel and in the die, extrudate swell at the die exit and the residence time distribution of the material in the extruder channel. Model predictions are in good agreement with measurements on a 38 mm diameter extruder.

abstract: Doctor of Philosophy (PhD)


title: Sense of Place-Defense of Place: A Case-Study of the Toronto Island

contributor:
Andrews, H.
Geography

subject: Geography Geography

abstract:
This thesis investigates the dialectical relationship between sense of place (i.e., feeling of belonging in and having a deep emotional attachment to a place of personal significance and meaning) and defense of place (i.e., specific political, legal and other actions taken to protect a place that is threatened). This is to say, when a place to which a person or a group of people is strongly attached is threatened in some way, the sense of place may lead to and condition the nature of the defence of place; and, when a place is threatened and defended, that defense of place, in turn, conditions and influences the nature of sense of place. In this dialectical relationship between sense of place and defense of place, the concept of threat occupies a position of central importance as a catalyst to action and a continuing influence.

The phenomenon of sense of place may exist in the absence of a severe threat or any defense of place. But when defense of place is evident, sense of place is the foundation upon which that defense of place is built. Sense of place, therefore, is given a position of primary importance in this investigation. It is argued that sense of place is a subjective phenomenon and, based on the information collected for this study, that it is composed of six, inter-related major components which have been termed: sense of history, sense of identity, sense of community, sense of environment, sense of control and sense of change.

Because of the nature of sense of place, this study adopts, as much as possible, an experiential perspective - i.e., attempts to understand the phenomena of sense of place and defense of place from the perspective of the experiencing individuals, using their own words and actions as clues to how they relate to their particular place. In addition, in order to explore the complex, holistic, multi-faceted nature of sense of place and its relation to defense of place, this study presents a detailed, case study of a particular group of individuals (Toronto Islanders) and how they have related to a particular place (Toronto Island), which has been subjected to a variety of threats over a long period of time. In order to accomplish these ends, a variety of data sources and techniques were employed, most notably a length period of participant observation (which involved living on the Island for approximately four months and extensive visiting over a period of six years) and interviewing of both Islanders (over eighty hours of taped interviews) and politicians (over twenty hours of taped interviews). In addition, analysis of the voluminous documentary records was conducted.

Evidence is presented that Toronto Islanders have experienced a sense of place and have repeatedly defended their special place against outside threats to radically alter or destroy it. By devoting one chapter to each of the six major components of sense of place, this study defines each component, provides copious evidence that Toronto Islanders have experienced each component, analyzes the dialectical links between each component and defense of place. This study, therefore, also demonstrates (by constant reference to detailed observations and comments from individual Islanders) how each general component of sense of place may be applied and analyzed in a particular place and may serve as a guide to future studies.

abstract: Doctor of Philosophy (PhD)


title: Functional Analysis of the Ninth Subunit of Yeast RNA Polymerase II, RPB9

contributor:
Edwards, Aled M.
Biochemistry

subject: Biochemistry Biochemistry

abstract: RNA polymerase II is the eukaryotic enzyme that synthesizes mRNA. It is a complex enzyme that is highly regulated by many protein factors throughout transcription. RNA polymerase II comprises twelve subunits, each of which likely plays a specific role in the function of the enzyme. The ninth subunit, RPB9, is involved in the initiation and elongation stages of transcription. In yeast, deletion of RPB9 results in sensitivity to high and low temperatures, as well as to the drug 6-aza-uracil. RPB9-deficient strains exhibit an alteration in the selection of transcript start sites, with an upstream shift of the start site window. The RNA polymerase II isolated from RPB9-null strains is unable to recognize intrinsic pause sites during elongation. The polymerase molecules that do arrest cannot resume transcribing upon stimulation by the elongation factor TFIIS. RPB9 is a small polypeptide, containing two zinc-binding regions (Zn 1 and Zn2) connected by an intervening sequence (linker region). This study presents the results of a mutational analysis designed to assisn th various functions of RPB9 to regions within the subunit. The Zn1 region was shown to be required for the start site selection activity of RPB9. When expressed in an RPB9-null yeast strain, the Zn1 region was found to be sufficient to restore start site selections to the wildtype pattern. Using a gel shift assay and purified proteins, an RNA polymerase II binding region was located to a conserved sequence (D---DPTLPR) within the linker region. The elongation activity of RPB9 was ascribed to the Zn2 region. Conserved charged residues within Zn2 were essential for the ability of RPB9 to mediate the reactivation of RNA polymerase II upon stimulation by TFIIS. This region of Zn2 is analogous to a charged flexible loop within the zinc ribbon domain of TFIIS. These observations provide the basis for a preliminary model of RPB9 interactions with RNA polymerase II.

abstract: Doctor of Philosophy (PhD)


title: On Schopenhauer's Ethics in View of his Conception of Compassion

contributor:
Ajzenstat, S.
Philosophy

subject: Philosophy Philosophy

abstract: This paper is first a criticism of Schopenhauer's ethics (specifically of his explanation of compassion), and secondly, an attempt to remove the inadequacies which were found in his theory by substituting an alternate explanation for compassion. I begin by pointing out what Schopenhauer's idea of an ethical theory is, i.e., what he thins an ethical theory is supposed to achieve. THen, by criticizing various aspects of his theory I indicate that his own theory has failed to achieve this ideal. Finally, I attempt to alter Schopenhauer's theory in such a way that its shortcomings are removed, and it comes closer to doing what Schopenhauer meant it to do.

abstract: Master of Arts (MA)


title: OPTIMIZATION BY BOUNDARY CONTROL OF REACTORS WITH DECAYING CATALYST

abstract: Doctor of Philosophy (PhD)


title: The Work of Adele Wiseman

contributor:
Coldwell, Joan
English

abstract: This thesis is a study of the work of Adele Wiseman, with particular emphasis on the analysis of her novels, The Sacrifice and Crackpot. The Eastern European Jewish background of the writer, with which she identifies strongly, as well as her Winnipeg roots, are a focus of special attention for the purpose of interpreting her work within its appropriate cultural context. The development of similar themes and symbols, and apparent differences in perspective and style in the two novels are examined. Adele Wiseman's continuing social, political, and moral concerns are analyzed, and her ideas and observations about the creative process are noted. An attempt has been made to demonstrate the integral relationship of these concerns and ideas to her literary creativity.

abstract: Master of Arts (MA)


title: Relationships between MAS NMR and Mineral Structure

contributor:
Grundy, H.D.
Geology

subject: Geology Geology

abstract:
²⁹Si magic angle spinning nuclear magnetic resonance (MAS nmr) has been used extensively to study the structure, properties, and reactions of silicate minerals, ceramics and glasses. Despite many attempts to relate chemical shift with crystal structure the factors governing ²⁹Si chemical shift are not weII understood.

This study investigates the effect of local structural environment of the silicate tetrahedron on ²⁹Si chemical shift. A simple relationship is found between the atomic positions of the cations bonded to the terminal oxygens of the tetrahedron and ²⁹Si chemical shift, which can be used to calculate chemical shift from atomic positions. A plot of calculated against experimental chemical shift has a correlation coefficient of 0.986 for 124 sets of date from all groups of silicates.

²⁹Si chemical shifts calculated from diffraction data, are used to interpret MAS nmr spectra of scapolite, a partially disordered mineral system. Models are devised for cation ordering throughout the solid solution series, in which the charge on the cavities are balanced locally by the requisite number of AlO₄ tetrahedra.

²⁹Si, ²⁷AI, ²³Na, ⁷Li and ⁹Be MAS nmr spectroscopy is used to investigate the difference in atomic sites between beryls with slightly different compositions. ⁹Be and ²⁹Si MAS nmr results agree with the presence of domains in the Li-Cs beryls with the structure of low-alkali beryls. Lack of a tetrahedral peak in the ²⁷Al spectra of Li-Cs beryls eliminates the coupled substitution of Li for Al and Al for Be. Peaks in the ²³Na spectra of Li-Cs beryls from NaCI in solution in fluid inclusions show the potential of nmr to study fluid inclusions.

Models of theoretical structures based on a symmetrical SiO₄ tetrahedron with AI or Si ligands show that chemical shift is linearly proportional to cation-oxygen distance (r) and exponentially proportional to silicon-oxygen-cation angle (α). The possible ranges of chemical shift for each type of silicate are more extensive than those of Lippmaa et al. (1980).

abstract: Doctor of Philosophy (PhD)


title: From Organometallic Cations to Carbenes: An NMR, Structural and Reactivity Study.

contributor:
McGlinchey, M. J.
Chemistry

subject: Chemistry Chemistry

abstract: The electronic requirements of the short-lived 4n π anti-aromatic fluorenyl indenyl and cyclopentadienyl cations have been studied by investigating the dynamic processes exhibited by their dicobalt hexacarbonyl alkynyl clusters in solution. It is suggested that the 12π fluorenyl complex requires the least amount of electronic assistance from a neighbouring Co(CO)₃ moiety (and consequently the cyclopentadienyl ligand requires the most). That is, the experimental evidence indicates the following cationic stability trend: fluorenyl (12π electrons) > indenyl (8π electrons) > cyclopentadienyl (4π electrons). However, these cationic clusters did not yield single crystals suitable for an X-ray crystallographic study and efforts were focused on synthesizing neutral models for these complexes. Isobal replacement of a formal Co(CO)₃⁺ vertex with a Fe(CO)₃ moiety, in the fluorenyl and indenyl systems yields neutral iron-cobalt clusters, (Me₃Si-C=C=C₉H₈)FeCo(CO)₆ and (1-trimethylsilylethynyl-2,3-diphenylindenyl)FeCo(CO)₆, the structures of which were determined by X-ray diffraction. This work provided insight into the mechanism for the formation of these iron-cobalt complexes. Conclusions about the electron requirements that these 4n π anti-aromatic cations impose on the neighboring metal center have been drawn. In contrast to anti-aromatic species, aromatic ligands such as C₇H₇⁺ do not require electronic assistance from neighboring organometallic moieties. However, if these species bulky substituents, then a compromise between π delocalization and steric strain occurs. The attempt to monitor the electronic requirements of a C₇Cl₆R⁺ moiety led to an investigation of the chemistry of the polychlorinated cyclic system, C₇Cl₈. Treatment of C₇Cl₈ with various organometallic reagents yielded syn-C₁₄Cl₁₂, presumably via coupling of intermediate C₇Cl₆carbenes. The reactions of dimethoxycarbene [(MeO)₂C:)], generated by the thermal decomposition of 2,2-dimethoxy-5,5-dimethyl-∆³1,3,4-oxadiazoline with polychlorinated olefins and ketones were investigated. Treatment of [(MeO)₂C:] with octachlorocycloheptatriene or octachlorobicyclo[3.2.0]hepta-3,6-diene yielded dimethoxy(hexachloro)heptafulvene and dodecachloroheptafulvene. It is proposed that an initial displacement of a chloride ion (Sɴ2') by dimethoxycarbene occurs resulting in cationic intermediates which can then undergo further reaction to yield the observed products. Reaction of hexachlorotropone and dimethoxycarbene was also investigated and methyl-2-pentachlorophenyl-2-oxo-ethanoate was observed. Mechanisms to account for the observed products were proposed, and the structures of some of these products were determined using X-ray crystallography.

abstract: Doctor of Philosophy (PhD)


title: Images of the Self: Chastity Figures in the Faerie Queene

contributor:
Graziani, R.I.C.
English

abstract: Since chastity, which as Spenser presents it seems to involve perception in an especially intense way, is one of the most complex virtues delineated in The Faerie Queene, the techniques which Spenser develops to define it are of particular interest. Partly because 'Diana' figures like Belphoebe and Britomart are surrounded by an aura of visual taboo, how they are seen and what they are able to see become aspects of the virtue which they represent. Since visually intense moments tend 'to stop the action' of the narrative, chastity becomes associated with images of static perfection; yet at the same time Spenser's heroines, embodying as they do almost masculine energy, seem to endow sheer forward momentum with moral significance. When Shakespeare deals with aspects of chastity in Venus and Adonis and The Rape of Lucrece, he too presents it in terms of paradoxes of stasis and development, insight and blindness: in the latter poem especialIy, the compulsion to define and project the self in the rhetoric of language and gesture issues in that thrust toward the iconic which I see as an important characteristic of Spenser's chastity figures. The 'iconic moment' is exemplified in The Faerie Queene in the first appearance of Belphoebe, whose virtue makes itself felt as a visual phenomenon and whose power is suggested by the way her image 'freezes' the narrative; as her story continues, however; the precise nature of the chastity which she represents is defined by a tension between stillness and development, isolation and involvement. Britomart, a more complex figure, comes to be defined in relation to the stasis associated specifically with art, the rhythm of her own story, with its headlong forward momentum, emerging in contrast to that of the narrative insets (like the myth of Venus and Adonis) which 'run down' into stillness and death. Her special strength, an intuitive ability to cut through complexities of erotic illusion which she never fully understands, is associated throughout Book III with her obliviousness to metaphorical language, which becomes linked with the erotic self-deception of other characters. Britomart's role in Book IV is discussed in relation to the major rhythm of that book, where the difficulty of social union is suggested by the way characters drift together and pull apart. In this context Britomart's power to unite becomes an important aspect of the virtue which she represents. Book V, where justice is seen to involve repression land oblivion is the appropriate context for the climax of Britomart'ls love-quest, which has raised from the beginning the questions of perception and of wholeness; the dream in Isis Church is analyzed in terms of the tension between involvement and detachment, image and process, insight and blindness, which have been important in her story from the beginning. In Book VI, Tristram, whose youthful purity is defined in the context of the tale of adult sexuality into which he intrudes and who like Belphoebe is a hunter whose glamorous image freezes narrative into icon, is discussed as a chastity figure whose treatment exemplifies some of the paradoxes which have been developed; in particular, the intensity of his visual presence initiates the tension between eye and ear which is significant throughout Book VI. Spenser's treatment of his chastity figures tends to involve the perceptions of the other characters and of the narrator and reader in a way which may well be called dramatic; the power of these characters to evoke some of the most effective narrative in the Faerie Queene derives from the nature of the virtue as Spenser conceives it.

abstract: Doctor of Philosophy (PhD)


title: Reconstructing Population History from Past Peoples Using Ancient DNA and Historic Records Analysis: The Upper Canadian Pioneers and Land Resources

contributor:
Saunders, Shelley R.
Anthropology

subject: Anthropology Anthropology

abstract: It has been argued that the real anthropological potential of ancient DNA has yet to be realized (Stoneking 1995). Ancient DNA Research can only become truly anthropological when it is integrated holistically through a multidisciplinary approach within the bio-cultural framework. Reconstructions of past societies by definition necessitates the synthesis of other sources of culturally relevant information. Attempts to interpret Upper Canadian pioneer population history from the ancient DNA recovered from two historic cemeteries (the nineteenth-century St Thomas' Anglican Church cemetery, Belleville, Ontario, and the Farewell Family Cemetery on Harmony Road, Oshawa, Ontario) revealed that there were a number of possible evolutionary explanations for the observed pattern in both nuclear and mitochondrial DNA data. The reconstruction of past sociocultural variables to facilitate further interpretation relied on the collection of scholarly historic research, primary records analysis, and archaeological theory and observations. Through this analysis it was shown that conclusions regarding past population history could not be drawn from any single source of information. It was possible to observe the intragenerational and intergenerational kinship alliances influenced by a land resource stress through the establishment of a social context and an interment chronology. This finding provides strong empirical evidence in support of the Saxe (1970) and Goldstein (1976) theory which predicts the presence of a vital resource pressure when kinship structure is hypothesized inarchaeological mortuary practice. While this theory may have use in broader archaeological contexts, it is maintained that its application can only be evaluated through a multidisciplinary approach involving ancient DNA and other relevant cultural evidence.

abstract: Doctor of Philosophy (PhD)


title: Finite Element Studies in Injection Mold Filling

contributor:
Hrymak, A.N.
Vlachopoulos, J.
Chemical Engineering

abstract:
Flow phenomena associated with the injection mold filling process have a significant impact on the microstructure development and hence on the final properties of molded articles. The present work is concerned with the mathematical modeling and numerical simulation of the mold filling process. The aim is to provide in-depth understanding of the flow phenomena involved and investigate their impact on the microstructure of the molded polymer article.

The mold filling process takes place as a rolling-type advancement of the flow front over the mold walls. The flow field behind the advancing flow front is known as fountain flow, and it is the salient feature of mold filling. The fountain flow phenomenon is examined extensively with finite element techniques, both in the steady-state and in the time domain. The u-v-p-h-δ formulation described in the present work is a powerful numerical technique for the simulation of free surface flows, and determines simultaneously the flow field and the free surface shape. Steady-state and transient simulations with Newtonian and shear-shinning fluids in planar and axisymmetric geometries are presented. Various features of fountain flow are described with the aid of velocity vector, pressure, free surface shape, and streamline plots. The general problem of fountain and reverse fountain flow (immiscible liquid displacement) and the collision of two flow fronts to form a weldline are also investigated.

The deformation history experienced by the fluid due to fountain flow is examined on the basis of the numerically computed flow field, by tracking material elements as they move through the flow domain. It is found that material elements from the centerline migrate towards the mold walls, extend in the flow direction and form characteristic V-shapes, fully in agreement with available visualization experiments.

A viscoelastic constitutive equation (multi-mode Leonov model) is introduced in order to investigate the effect of fountain flow on the molecular orientation of injection molded parts, as reflected in available birefringence measurements. A finite element algorithm for the numerical simulation of viscoelastic free surface flows is described. Fountain flow simulations are performed for material properties and processing conditions corresponding to available experiments. Finite element solutions are obtained at high levels of fluid elasticity and they converge with mesh refinement, provided that a slip boundary condition is applied at the wall to alleviate the stress singularities. The finite element results are combined with a simple theory to predict frozen-in stress and birefringence distributions. Computational results are compared to, and agree favorably with, available experimental data. It is demonstrated quantitatively that fountain flow is responsible for the molecular orientation pattern of the surface layer of injection molded parts. A viscoel~stic constitl1tive eq~ation (multi-mode Leonov model) is introduced in , order to investig'ate the effect of fountain flow on the molecular orientation of injectio~ molded parts, a~ refl~cted in available birefringence measurements. A finite element algorithm for the numerical simulation of viscoelastic fre~ surface flows 'is described. Fountain flow simulations are performed for material properties and processing conditions corresponding to available' experiments. Finite element ~olutionsare obtained at high levels of fluid elasticity and they converge with mesh refinement, provided that a slip boundary ..... condition is applied at the wall to alleviate the stress singularities. The finite element results are combined with a simple theory to predict frozen-in stress and birefringence d!stributions. Computational results are compared to, and agree favorably with, available experimental data. It is demonstrated quantitatively that fountain flow is responsible for the molecular orientation pattern of the surface layer ofinjection molded parts.

abstract: Doctor of Philosophy (PhD)


title: A Structural Basis for the Genesis of Hypertension in the Spontaneously Hypertensive Rat

contributor:
Lee, R.M.K.W.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: The spontaneously hypertensive rat (SHR) was used as a model of human essential hypertension. The overall hypothesis was that hypertrophy of the smooth muscle layer of small muscular arteries in essential hypertension results in greater contractility of these vessels that then results in elevated total peripheral resistance and higher blood pressures. Elevated total peripheral resistance and small artery hypertrophy are well documented in the SHR, however, it remains unknown if these changes are the cause of result of elevated blood pressure. For this reason, we have focused our studies on young SHR during the initiation of hypertension to attempt to separate cause from effect. Studies were done to determine when SHR's blood pressure begins to differ from its normotensive control the Wistar-Kyoto rat (WKY). We found that blood pressure began to diverge between SHR and WKY at four weeks of age. Structural and functional differences between small muscular arteries from the mesenteric vascular bed of 4-week old SHR and age matched WKY controls were studied using a new morphometric protcol involving confocal microscopy and a pressurized artery myograph. Arteries from SHR had a larger medial volume, increased number of smooth muscle cell layers, but similar lumen size when compared with WKY in the maximally relaxed condition. Functional studies showed that SHR arteries contracted more in response to stimulation by KC1 and norepinephrine, resulting in significantly smaller lumen size in these vessels as compared to WKY. We concluded that structural and functional differences in SHR arteries were primary changes which may contribute to the development of hypertension. Further studies were conducted to determine if a differential incidence of apoptosis during the development of SHR and WKY arteries contributes to the structural differences. One to two week old animals were used for these studies since at this time the structure was similar between the strains. To measure the incidence of apoptosis, we used both DNA laddering and end labeling. It was found that SHR had a significantly decreased incidence of apoptosis over WKY. The cellular nature of the medial layer hypertrophy in SHR at 4-weeks was also assessed. Numerical density of smooth muscle cell nuclei in the medial layer was measured with a three dimensional disector method under confocal microscopy. We found that the numerical density of medial smooth muscle cells was significantly less in SHR than WKY, and the number of smooth muscle cells was significantly less in SHR than WKY, and the number of smooth muscle cells was similar between the strains. The smooth muscle cell length from SHR was significantly longer than WKY. We concluded that increased smooth muscle cell length in prehypertensive SHR is responsible for their increased medial volume. These studies have shown that medial layer hypertrophy due to smooth muscle cell lengthening in the small muscular arteries of SHR which increases their contractile ability, occurs at the initiation of hypertension. This evidence demonstrates that structural and functional changes in these SHR arteries can not be the result of increased blood pressure but may be a factor causing hypertension by increasing the total peripheral resistance in these animals.

abstract: Doctor of Philosophy (PhD)


title: COD Balances in Biological Nutrient (Nitrogen and Phosphorus) Removal Activated Sludge Systems

contributor:
Dold, P. L.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract: This research set out to investigate reported anomalies in the calculation of COD balances in biological nutrient (nitrogen and phosphorus) removal (BNR) activated sludge systems. For non-BNR systems, accurate COD balances are consistently attainable from experimental measurements. That is, influent COD can be accounted for in the effluent flow, waste sludge stream, and mass of oxygen utilised for carbonaceous oxidation. For BNR systems, in a number of instances where COD balances have been performed, the balances do not close. That is, the sum of the COD leaving the system is as much as 20% less than the COD entering the system, and thus there is an apparent COD 'loss'. In attempting to explain the problem, a laboratory based experimental program was developed which isolated specific areas of interest within BNR systems. The study involved two main experimental phases. In the first experimental phase, a closed denitrification assay technique was developed. This assay technique allowed specific aspects which have relevance to be evaluated: the nitrate-to-oxygen conversion factor, and the yield of activated sludge organisms under anoxic conditions. The advantages of the closed assay were that all of the needed COD balance terms were independently measurable, and the denitrification system was sealed which isolated the assay environment from the surrounding environment and minimised the effects of external inputs (i.e. oxygen transfer from the air to the liquid). In the second experimental phase, an excess biological phosphorus removal (EBPR) system was operated to investigate the influence of the influent COD to phosphorus ratio on EBPR biological activity and COD balance calculations. The EBPR system was a laboratory - scale sequenching batch reactor (SBR) which was extensively monitored over an eight month period. This allowed for the investigation of several factors such as, the rate of anaerobic phosphorus release and COD uptake, the ratio of anaerobic phosphorus released to COD taken up, and the rate of aerobic phosphorus uptake. The system also allowed for the calculation of COD balances. The main body of this thesis is presented as a series of five papers. The first aper (Chapter 3) presents a study on the nitrate-to-oxygen conversion factor for denitrification which theoretically is 2.86 gO₂/gNO₃-N. That is, when nitrate replaces oxygen as electron acceptor, the mass of nitrate reduced can be converted to oxygen equivalence - for purposes of COD balancing - through the use of this conversion factor. Calculations from a series of denitrifying experiments resulted in an observed conversion factor of 2.96 gO₂/gNO₃-N. However, the observed factor could not be distinguised statistically from the theoretical value, hence confirming the theoretical factor. The second paper presents a study of sludge production under anoxic (denitrifying) and aerobic conditions. Decreased sludge production and COD 'losses' are confounded in nutrient removal activated sludge systems. Hence this portion of the investigation was initiated to separate these two influences. Batch tests were performed under anoxic (denitrifying) and aerobic conditions using various organisms. The results show that COD balances were achieved, but differences in sludge production under the two conditions indicate a difference in true yield between the environments. An anoxic yield of 0.402 mg particulate COD/mg consumed COD was determined and compared with an observed aerobic yield of 0.645 mg particulate COD/mg consumed COD. These results dispel the assertion that less sludge production results because of COD 'losses'. That is, decreased sludge production in BNR systems can at least in part be explained by a lower yield during unaerated periods. The third and fourth papers (Chapters 5 & 6) present the results from the EBPR system. The third paper conccentrates on the results from the SBR and the influence of the various influent COD to phosphorus ratios. Five different influent ratios were investigated ranging from 8 to 98 (mgCOD/mgP) using a synthetic feed with acetate as the sole carbon source. The phosphorus content of the waste sludge increased from 4 to 17 per cent of the total solids as the influent COD:P ratio decreased. However, complete anaerobic COD uptake was observed irrespective of the phosphorus content of the sludge. Also, COD balances on the reactor averaged 1.04 indicating no apparent COD 'loss' in the system. The fourth paper presents the results of batch tests performed on the waste sludge from the SBR. Anaerobic batch tests were designed to determine the influence of the SBR steady state influent COD to phosphorus ratio on the kinetics and stoichiometry of the system's microbial community. In particular, the rate of substrate uptake increased from 104 to 211 mgCOD/gVSS/hr as the influent ratio decreased. Similarly, the rate of phosphorus release increased from 17 to 166 mgP/gVSS/hr as the influent ratio decreased. The batch test results showed that the ratio of COD taken up to phosphorus released under anaerobic conditions varies with the phosphorus content of the sludge. The observed release ratio increased from 0.17 to 0.79 mgP/mgCOD as the phosphorus content increased. The final paper (Chapter 7) presents a theoretical biochemical model for EBPR systems. The proposed model makes a distinction between glycogen accumulating organisms (GAOs) and polyphosphate accumulating organisms (PAOs) but suggests that significant populations of both types of organisms exist in most EBPR systems. That is, it is proposed that only in systems that are stressed does one type of organism dominate the mixed community. The biochemical models of Comeau et al. (1986) and Wentzel et al. (1986) were merged with the biochemical model of Satoh et al. (1994) to form a comprehensive model for EBPR system activity. The two-organism model provides several advantages over single organism models including the ability to predict variable rates of reaction and a variable anaerobic COD uptake to phosphorus release ratio.

abstract: Doctor of Philosophy (PhD)


title: Kindling and Activation-Induced Hippocampal Plasticity

contributor:
Racine, R.J.
Psychology

subject: Psychology Psychology

abstract: In the adult nervous system, neuroplasticity can be described as all modifications in neuronal structure or function in response to alterations in input. The kindling model of temporal lobe epilepsy represents one of the most widely studied models of neuroplasticity in the mature nervous system. Kindling can be defined as a progressive increase in evoked behavioural and electrographic seizure activity following electrical stimulation of forebrain structures. Recent research has shown that kindling produces a number of plastic changes in the brain, particularly in the hippocampal region. These changes include sprouting of axons, an increase in the size of the hilar area of the dentate gyrus, and reactive gliosis. To date, the relationship between kindling and kindling-induced hippocampal plasticity is not clear. The major emphasis of this thesis is to investigate whether kindling-induced plasticity can be induced by activation. In Study 1, the neurotrophin nerve growth factor (NGF) was used as a tool to dissociate kindling-induced cell loss and kindling-induced mossy fiber sprouting. Intravetricular administration of NGF accelerated seizure development, enhanced mossy fiber sprouting and attentuated seizure-induced decreases in hilar cell density. These findings appear to dissociate kindling-induced mossy fiber sprouting is due to the co-involvement of growth factors and activation. Study 2 showed that NGF may mediate kindling-induced mossy fiber sprouting via the cholinergic system, providing the first evidence that the cholinergic system plays a role in mossy fiber sprouting. Study 3 showed that mossy fiber sprouting can be induced by non-epileptogenic stimulation, providing further evidence that mossy fiber sprouting can occur in the absence of neuronal damage. Study 4 showed that kindling-induced changes in hilar area and kindling-induced changes in hilar area and kindling-induced reactive gliosis follow a similar time course.

abstract: Doctor of Philosophy (PhD)


title: Like Eden in Her Summer Dress : Gentry, Economy, and Society: Upper Canada, 1812-1840

contributor:
Craig, G.M.
Cross, M.
History

subject: History History

abstract:
The purpose of this thesis is to examine the origins of a provincial strategy for economic development in Upper Canada between 1812 and 1840. The first serious treatment of this topic was by Donald Creighton in 1937. Since then historians and political economists have seized upon the relationship between the so-called "Family Compact" and economic development as an example of nascent nationalism, outright commercial interest, or the corporatist roots of the Canadian economy.

The genesis of provincial development policies deferred between 1818 and 1825. The men responsible for marshalling pubic opinion, setting out the broad framework for policies, and implementing legislation in the House of Assembly were pre-eminent figures in the Compact. John Beverly Robinson, John Stracham, John Macaulay, and Jonas Jones. To a lesser extent Christopher Hagerman and George Markland were also involved. The thesis accepts the legitimacy of the well-established historiographical connection between the Compact and development. It sets out the assumptions which underlay the economic programme of the self-proclaimed gentry but is not a history of economic development during the period or an analysis of development legislation. Rather it is an attempt to delineate the theoretical prerequisites of the idea of the development in Upper Canada and its relation to society.

The War of 1812 set the stage for the first discussion by Robinson of the need for a prosperous society. The military vulnerability of the province and the experience of widespread disaffection during the war prompted the suggestion in 1816 that the colony's first line of defence was prosperity. The most important assumption which endowed the development of the 1820s with its characteristic flavour was the Edenic myth of the gentry -- the belief that Upper Canada had been providentially-endowed with a lush natural bounty, comparable to any spot in the world. This faith was the foundation for the gentry's enthusiam for development on the grand scale, at great cost, with little regard for profit, or how to pay the enormous debt which eventually resulted. The exaggerated sense of provincial capability was ground in providential belief. Moreover this myth accorded with generally-held assumptions that the resource base of the province was fundamentally agricultural.

The immediate spur to development came from American initiatives with canals in New York State in 1817, the discontent about improvement evident during the agitation of Robert Gourlay in 1818, and most important, the depression which held the province between 1819 and 1821. In 1821 a committee of the House of Assembly reported its findings on the internal resources of the province. The thrust of its recommendations was overwhelmingly agricultural. Timber received short shrift and manufacturing was all but dismissed. The committee's conclusions were that stable markers in Great Britain and the improvement of internal navigation would ensure long-term prosperity. The subsequent Committee on Internal Navigation and the parliamentary committee reporting on its findings were dominated by the gentry. In 1825 through the efforts of Robinson, the province committed itself to the gentry's programme for canals with an enormous loan to the Welland Canal raised by debenture financing. Development itself was a limited matter: canals to get the rich products of the soil to markets and preferential entry of wheat, flour, and timber to British markets. In American trade the gentry strove mightily to maintain a just balance between free trade on certain goods and protective tariffs on others.

The core of the gentry's beliefs was an agrarian image of society in its myriad forms: political, economic, and social. This was the pre-capitalist society of independent commodity producers. The gentry's political beliefs were rooted in the hierarchical ordering of an agrarian society. Their political language and their concept of moral character and virtue were based on the maintenance of an agrarian society with only limited urban centres and commerce. They believed that canals were a public trust and should be undertaken by the province and superintended by those who had only the general interest at heart - gentlemen. They rejected the egalitarian image of society held by radical agrarians and the capitalist image of society advocated by merchants such as William Allan. The issue which bought these contending images together was the question of legislation union with Lower Canada. h Lower' Canada. Throughout the 1820s and the 1830s the gentry rejected a society in which considerations of finance and commerce were pre-eminent.

The thesis concludes that the limited strategy for development which originated between 1818 and 1825 was directly attributable to the agrarian assumptions, Edenic myth, and political beliefs of the Upper Canadian gentry.

abstract: Doctor of Philosophy (PhD)


title: Characteristics of Seismic Floor Motions

contributor:
Heidebrecht, A.C.
Tso, W.K.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract: The overall objective of this study is to obtain characteristics of seismic floor motions in a nuclear reactor structure in order to examine current procedures used in seismic qualification of nuclear power plant equipment. The study incorporates seismic data from real earthquake events and uses these records as inputs to a mathematical model of a CANDU nuclear reactor building. Seismic floor responses at typical equipment locations are calculated by standard techniques of structural dynamic analysis. Six mathematical techniques are applied to develop characterizations of each seismic floor response record. From this data a set of parameters are evolved to qualitatively and quantitatively describe the characteristics of the ensemble of floor motions. Results of a theoretical study on sine beat, limited-duration sine, and decaying sinusoidal motions are compared to the characteristics of the seismic floor motions to evaluate the realism afforded by current single frequency seismic qualification test procedures. It is concluded that single frequency test motions have a valid application in seismic qualification test programs and can realistically simulate many seismic floor motion characteristics provided that the specific type of test motion and the test procedures are well defined. Recommendations are presented for the selection of single frequency test motions and for developing the test procedures.

abstract: Master of Engineering (ME)


title: Transepithelial Transport of Antigen: Novel Mechanisms in Food Allergy

contributor:
Perdue, Mary H.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: Food allergies are a significant clinical problem, with symptoms including diarrhea, vomiting, or systemic anaphylaxis. To elicit allergic reactions, antigens must first cross the intestinal epithelium. The purpose of my studies was to examine macromolecular transport across intestinal epithelium, and the effect of sensitization and immune activation on transepithelial antigen transport. Rats were sensitized to a model protein antigen, horseradish peroxidase (HRP) by injection with adjuvants. Intestinal segments were removed and mounted in Ussing chambers for the study for transepithelial movement of HRP. Electon microscopy analysis of HRP transport showed that specifically sensitized rats transported HRP across the epithelium in greater amounts, and more rapidly, than naive controls or rats sensitized to an irrelevant antigen. After the hypersensitivity response, there was a significant increase in HR flux across the intestinal epithelium in HRP sensitized, but not control rats. This was accompanied by an opening of the epithelial tight junctions to allow paracellular flow of antigen. Sensitized mast cell deficient rats also had an enhanced initial uptake of antigen, but did not develop a non-specific decrease in epithelial barrier function. The role of interleukin-4 (IL-4) in the regulation of transepithelial antigen transport was examined. Treatment of human epithelial monolayers with IL-4, or with serum from atopic patients, caused a significant increase in transepithelial transport of HRP. Antibodies against IL-4 abolished the effect of atopic serum on transepithelial HRP transport. Electron microscopy analysis showed an increase in both transcellular and paracellular HRP transport. These studies show that transepithelial transport of antigen is profoundly altered by sensitization, and that mast cells and interleukin-4 enhance the delivery of antigen across the intestinal epithelium.

abstract: Doctor of Philosophy (PhD)


title: Finding our Way: Paths to Justice Reform in an Aboriginal Community

contributor:
Warry, Wayne
Anthropology

subject: Anthropology Anthropology

abstract: This applied, participatory action research explores the context for community-based justice and conflict resolution mechanisms in Sagamok Anishnawbek First Nation. Within the pluralistic Canadian context, Aboriginals ways of law and social control are being reasserted by some First Nations both as a basic right, and as a means of "healing" their communities of the debilitating effects of colonization. This research shows a community in flux, where jural values are divergent and changing, but one in which a distinctive approach to some aspects of social disruption and its resolution is apparent. Like a number of other Aboriginal communities, Sagamok experiences a high level of interpersonal violence, and "mischief" committed by youths in need of improved life opportunities. Community members indicated through this research that they eschew incarceration for most offences in favour of a communicative, rehabilitative response to crimes. They want to strengthen communicative ties to young offenders, and use local resources to address their behaviours. In this and other basic jural values, Sagamok Anishnawbek have shown a preference for restorative justice whereby restitution and reparation take place within a personally relevant social context. In doing so, they model recent "innovations" in criminal case processing. Restoring justice goes far beyond dealing with crime, however, to addressing intracommunal conflicts and tensions. At present, the values and norms relating to conflict and its resolution revealed through this research are manifest chiefly at the individual level. If a justice model is to be developed, such basics need to be discussed and debated at the community level, through communicative process such as community consultations. If Sagamok residents are to discuss and debate these building blocks of a justice system and develop locally appropriate model, they will need to address some fundamental community development needs, one of which is the need for processes of conflict resolution within and between family groups.

abstract: Doctor of Philosophy (PhD)


title: Molecular Aspects of Differentiation in the HL-60 Human Promyelocytic Leukemia Cell Line: Signal Transduction, Gene Regulation and Cloning of the Major Protein Kinase C Substrate of Platelets (P47)

contributor:
Harley, C.B.
Biochemistry

subject: Biochemistry Biochemistry

abstract:
Biologically active phorbol esters cause HL-60 promyelocytic leukemia cells, to differentiate into cells resembling normal macrophages. Elevation of intracellular Ca²⁺ by ionophores and activation of protein kinase C (PKC) by phorbol esters often cooperate in a synergistic manner to elicit a full biological response; hence, a similar effect was sought in HL-60 cell differentiation. Assessment by a number of criteria conclusively demonstrated that treatment of HL-60 cells with subthreshold concentrations of phorbol esters in the presence Ca²⁺ ionophores caused macrophage-like differentiation. Synergistic HL-60 cell differentiation was phenotypicaly similar to the TPA-induced response yet was associated with a distinct pattern of gene regulation. In particular, induction of the proto-oncogene c-fos did not correlate with synergistic differentiation. This precluded a number of possible mechanisms which might underlie the observed cooperativity and suggested that Ca²⁺ may independently trigger essential components of the HL-60 differentiation program.

In an immunological survey of various tissues and cell lines, the major PKC substrate of platelets (P47) was detected in HL-60 cells. P47 abundane in HL-60 cells was increased 4.0 ± 0.5 fold upon differentiation with retinoic acid (RA), apparently because of a parallel induction of P47 mRNA. RA-differentiated cells were therefore chosen as an mRNA source from which to clone P47. Immunological screening of a lambda gt11 library yielded positive recombinamts expressing an open reading frame that matched peptide sequences obtained from purified platelet P47. Expression of P47 sequences in vitro and in E. coli showed the the P47 cDNA encoded a protein of Mr 40,087. The P47 sequence was not similar to any other known sequence but did contain a putative Ca²⁺ binding EF-hand and a strong candidate region for phosphorylation by PKC. The 3.0 kb P47 mRNA had some unusual structural features and was restricted to differentiated white blood cells. Analysis of the P47 gene suggested it has been conserved through vertebrate evolution and that in humans it has a complex 5' end. A Msp I polymorphism detected in HL-60 cells by sequencing of cDNA clones was confirmed in the normal human population. Preliminary characterization of human P47 genomic clones confirmed the gene structure deduced from Southern analysis. The P47 sequence refuted two candidate functions for this protein in the platelet.

abstract: Doctor of Philosophy (PhD)


title: Gender Differentials in Labor Market Outcomes

contributor:
Kuhn, Peter J.
Economics / Economic Policy

subject: Economics Economics

abstract: In this dissertation, I study three aspects of gender differentials in labor market outcomes. The first essay examines why there is inter-ethnic variation in the gender wage among the first generation, and among second-and-higher generation immigrants to the United States. Using the 1990 U.S. Census I contrast the role of human capital factors and "cultural" factors, i.e. differences in preferences regarding family structure and women's role in market versus home work. While human capital factors do play an important role, especially among second and higher generation immigrants, controlling for these factors does not eliminate inter-ethnic variation in the gender wage gap. In fact, for first generation immigrants, I find that even after controlling for all observable characteristics in the United States, a one percentage point increase in the home country gender wage gap is associated with a 0.9 percentage point increase in the gender wage gap across these ethnic origin groups in the United States. I argue that this positive correlation suggests the importance of cultural factors. Although I am unable to detect the effect of home country factors for second-and-higher generation immigrants, there appears to be a role for "tastes" regarding work and family, in addition to the more commonly-analyzed human capital and institutional factors, in explaining why some women earn more relative to men than others. The second essay attempts to measure the effect of employment equity laws on job search outcomes, and on perceptions of discrimination by both men and women in a sample of Canadian job seekers. I find some evidence that employment equity coverage in a preseparation job reduces the relative amount of time it takes women, versus men, to become re-employed. This effect operates largely through highly significant differences in the rate at which women and men are recalled to the preseparation employer. Finally, I find that employment equity coverage reduces the gender gap in the extent to which workers feel harmed by gender discrimination. Perhaps unfortunately, this effect primarily occurs via an increase in men's perceptions of being harmed, rather than a reduction in women's. The final chapter seeks to explain why, compared to older women, young female job seekers are more than three time as likely to report that their ability to find a good new job is compromised by the simple fact that they are female. Using the same sample of job seekers as in Chapter 2, I show, first, that young women's more frequent reports of gender-induced harm cannot be statistically attributed to any observed personal or job characteristics, or to any "objective" measure of discrimination computable in my data. Second, using new questions asked in the aforementioned survey, I note that women's reports of gender-induced advantage, as well as men's reports of gender-induced harm, are also more prevalent among the young. Using a formal model of the reporting decision, I conclude that the most likely cause of all these phenomena is a particular kind of age difference in reporting behavior: young people of both sexes are more likely than older people to interpret departures in either direction from gender-neutral treatment as casually affected by their gender. This may have important implications for future public support of anti-discrimination policies, and for the design of those policies.

abstract: Doctor of Philosophy (PhD)


title: Photosolvolysis of N-Benzoyl-5-bromo-7-nitroindoline (A Mechanistic Study)

contributor:
Childs, R.F.
Chemistry

subject: Chemistry Chemistry

abstract:
This thesis describes a study of the photosolvolysis of N-benzoyl-5-bromo-7-nitroindoline. The investigation was instigated because N-acyl-5-bromo-7-nitroindolines have been considered as potential photoprotecting groups for the photolithographic formation of charge-mosaic membranes. However, no kinetic data, and only scant mechanistic information, has been reported for the photofragmentation process.

Both absorption and emission spectra of N-benzoyl-5-bromo-7-nitroindoline were obtained. Based on the electronic spectra, it would seem that the two lowest energy singlet excited states are nearly isoenergetic and their relative energies are a function of the solvent medium.

The distribution of photoproducts obtained from irradiation of N-benzoyl-5-bromo-7-nitroindoline in various solvent systems was investigated. It was shown that the photosolvolysis reaction is a function of the solvent properties. Thus 5-bromo-7-nitroindoline and benzoic acid were the only photoproducts formed in acetonitrile. In acetonitrile-water, 5-bromo-7-nitrosoindole as well as 5-bromo-7-nitroindoline and benzoic acid were identified. A correlation between solvent polarity, Eᴛ(30), and 5-bromo-7-nitrosoindole formation was observed.

The mechanism of the fragmentation mode was examined. The presence of a free radical intermediate is suggested from the photoproduct distribution in tetrahydrofuran (THF). Observation of an electron spin resonance (e.s.r.) spectrum during irradiation of N-benzoyl-5-bromo-7-nitroindoline in an e.s.r. spectrometer cavity, 180 incorporation into benzoic acid, and a linear free energy relationship with sigma dot (δ·) corroborated the intermediacy of a free radical in the fragmentation process.

Quantum yields of N-benzoyl-S-bromo-7-nitroindoline disappearance in different solvents and quenchers were measured in order to establish the reactive excited state and the effect of the medium on the efficiency of the transformation process. A solvent dependency on both the excited state lifetime and photosolvolysis reaction efficiency was noted. The results were indicative of a change in mechanism with a variation in solvent polarity and/or hydrogen bonding ability.

A mechanism compatible with experimental results and applicable to previously reported N-acyl-2-nitroaniline photofragmentations is proposed.

abstract: Doctor of Philosophy (PhD)


title: Modelling and Advanced Multivariable Control Strategies For a Pilot Scale Extractive Distillation Column

contributor:
Taylor, P.A.
Wright, J.D.
Chemical Engineering

abstract:
A pilot scale distillation column was built jointly with other students to study the separation of an azeotropic mixture of acetone and methanol. An extractive distillation process is used to break the azeotrope using water as a solvent. This is a nonideal, nonlinear, multicomponent system. A VAX 11/750 computer with DPM-23 industrial front-end system was used in a distributed control configuration for control and data archiving of the column. An on-line Varian-6000 gas chromatograph (G.C.) is used for the top and bottoms product analysis.

A complete tray to tray steady state and dynamic mass and energy balance models were developed. The validity of these models has been explored using experimental data over a wide operating region. The simulated behaviour from the dynamic model was compared with the experimental column behaviour for various open loop steps in the reflux flow rate, feed flow rate, feed composition and reboiler duty. The nonlinear behaviour of the system was simulated by the models. A simple model for vapour liquid equilibrium (VLE) calculations was developed and its validity was proven.

The grouping of several trays together as a compartment has a thermodynamic basis and reduces the total number of model equations to be solved. Models with 3, 4 and 5 compartments showed good agreement with the experimental data and with a tray to tray model. A saving of 70% in the computation time was achieved over the tray to tray model. The 5 compartment model was used to develop a reduced order bilinear model of the system using the reflux flow rate and the reboiler duty as manipulated variables. The dynamics of the column were investigated for steps in steam pressure, reflux flow rate and feed flow rate. The system behaviour using the bilinear model and a complete tray to tray model were similar to the actual plant data.

PI control strategies were simulated for single and dual composition control for four different kinds of disturbances. From the simulation studies it was found that for the control strategy with two single loop the conventional pairing of the reflux flow rate and reboiler duty is suitable for only certain kinds of disturbances. Selection of the water flow rate and reboiler duty (steam pressure) as a manipulated variable pairing showed better performance. This was also shown experimentally.

A bilinear optimal controller design was developed which would result in an asymptotically stable system. The optimal controller for a bilinear system is nonlinear in nature, but the control law depends upon the objective function selected. The proof of optimality is given. It was also shown that an optimal controller based on a bilinear equation has a larger region of application than a controller designed from a linearized model. The optimal controller, along with a reduced order bilinear model, was applied to a simulation and on the pilot plant for dual composition control. Reflux flow rate and reboiler duty were used as the manipulated variable pair. The weighting matrices from the objective function and the constant system matrices from the model were used to solve a Liapunov equation to obtained the matrix used in the control law. The tray temperatures were used to predict compositions for the experimental control studies. A recursive least squares (RLS) method was used to update the predictor parameters when the G.C. analyses were available. An optimal controller with the composition predictor was implemented successfully on the pilot scale extractive distillation column for the servo control problem. A bilinear controller was also applied to the regulatory problem of a feed flow disturbance. It is found that even a multivariable controller based on the reflux flow rate and reboiler duty did not perform well. Subsequently, a bilinear model for the extractive distillation was changed to use water flow rate and reboiler duty as manipulated variables. The controller resulting from this model was implemented successfully on the simulation for 20% feed flow disturbance. It should be noted that the system performance depends upon the performance index used in the design of the bilinear controller.

abstract: Doctor of Philosophy (PhD)


title: Multi-Axis Milling of Flexible Parts

contributor:
Elbestawi, M. A.
Spence, A.D.
Mechanical Engineering

abstract: Multi-axis milling simulation of flexible parts is a highly interdisciplinary topic. It includes theories and methods in milling mechanics, structural mechanics and geometric simulation. In order to determine the acceptable cutting conditions, process planners faced with the flexible tools and thin walled structures either use very conservative cutting conditions, or in the case of high volume productions, trial and error methods. In either case, a final air cut is usually required to bring the machined surface within the tolerance. Although practicala, the above approach results in low productivity. Development of an analysis software capable of predicting the cutting forces deflections and surface errors in multi-axis milling of the thin wall structures is therefore highly desirable. By eliminating the need for trial and error methods a dynamic multi-axis process simulator can assist process planners to optimize the cutting condition and tool path for the least geometrical errors. This thesis describes such a simulator, implemented as an integrated CAD/CAM architecture consisting of both geometric and physical simulators. A static cutting force model is introduced which accounts for the rotation of the a and b axes in multi-axis side milling operations. The proposed formulation is based on a vectorial approach which reduced to a conventional formulation if a three-axis tool path is used. A dynamic multi-axis force model is also developed which is capable of modeling the tool/workpiece structural interaction. The dynamic response of the workpiece to the instantaneous cutting forces is modeled using a special finite element code. In conjunction with the finite element code, a solid based automatic mesh generation algorithm is also developed. The automatic mesh generator frequently updates the finite element mesh as the workpiece geometry changes. The dynamic parameters of the tool, experimentally found at its tip, are extrapolated for the rest of the cutter elements along the tool axis. The tool elemental parameters are then used to model the dynamic response of the cutter. Using the effective deflection of the tool/workpiece system, profile of the machined surface is simulated and its geometric deviation from the design surface is computed. This is highly desirable for side milling of ruled surfaces, where the value added is very high. For the experimental verification of the developed models, a twisted ruled surface was machined using a four-axis milling operation. The thickness of the twisted blade was reduced to 2.0 mm for the case of the dynamic cutting tests. The profile left on the machined surface was compared with the simulation result. In all comparisons a good agreement is seen between the experimental data and simulation results, which verifies the validity of the developed models and techniques.

abstract: Doctor of Philosophy (PhD)