Increasing wind penetration adds to the importance of enhancing the reliability of wind, to mitigate the magnitude and frequency of changes in electricity generation. This work addresses how improvements can be made to reliability through the geographic dispersal of wind farms in Ontario, Canada, using modeled North American Regional Reanalysis data. Optimal configurations of wind farm locations are determined according to two criteria. The first selects combinations of wind farms that follow temporal demand patterns, by maximizing the difference between the energy price and the cost of electricity. The second attempts to select combinations of wind farms that minimize the coefficient of variation in the aggregate output. It is found that there are no wind regimes in Ontario that match demand sufficiently for a viable development strategy, but that combinations of as few as three locations can reduce the coefficient of variation by over 30%, compared to a single region.

Increasing wind penetration adds to the importance of enhancing the reliability of wind, to mitigate the magnitude and frequency of changes in electricity generation. This work addresses how improvements can be made to reliability through the geographic dispersal of wind farms in Ontario, Canada, using modeled North American Regional Reanalysis data. Optimal configurations of wind farm locations are determined according to two criteria. The first selects combinations of wind farms that follow temporal demand patterns, by maximizing the difference between the energy price and the cost of electricity. The second attempts to select combinations of wind farms that minimize the coefficient of variation in the aggregate output. It is found that there are no wind regimes in Ontario that match demand sufficiently for a viable development strategy, but that combinations of as few as three locations can reduce the coefficient of variation by over 30%, compared to a single region.

A study is made of the problem of metamaterial homogenization, which is the attempt to represent an artificially fabricated inhomogeneous periodic structure as a homogeneous medium with an electromagnetic response described by a number of constitutive parameters (permittivity, permability, etc.) In particular, the importance of spatial dispersion in metamaterials and the need to characterize metamaterials with wavevector dependent constitutive parameters is explained an examined. A brief survey of important previous attempts at metamaterial homogenization is presented. This is followed by a discussion of spatial dispersion in metamaterial crystals. The importance of spatial dispersion in metamaterials is justified and some manifestations of spatial dispersion described. In particular the little known phenomenon of bianisotropy in centrosymmetric crystals due to spatial dispersion is explained. Also, the effects of spatial dispersion on physical quantities such as energy flux and dissipation are identified. We then describe a new method for solving for the free eigenmodes of a metamaterial crystal with a complex wavevector eigenvalue simulation. Next, two different theoretical attempts by the author at metamaterial homogenization are described, both accompanied by tests of the calculated constitutive parameters and critical examination of the strengths and weaknesses of each approach. Finally, strong evidence of the presence and importance of spatial dispersion in metamaterials is presented. / text

Aflatoxin is a carcinogen produced by the fungus Aspergillus flavus that causes millions of dollars in agriculture losses in the southeastern US. This thesis examines the dispersal of A. flavus on two corn inbred lines, resistant (Mp313E) and susceptible (B73), which differ in total aflatoxin accumulation after infection with A. flavus. After inoculating corn kernels with the fungus an RNA analysis was used to determine the location (number of kernels away from inoculation site) and abundance of A. flavus at weekly intervals. A. flavus started its spread at 7 days after inoculation (DAI) on both corn lines. The B73 corn line showed a constant spread of 3.4mm per day until the entire ear was infected at 21 DAI. The spread on Mp313E did not proceed beyond 3 kernels away from the inoculation site following 7 DAI. The results are significant because they show a faster rate of spread than previously reported and they help quantify the ability of Mp313E to mitigate infection.

<p> This thesis presents a study of diagnostics of pulsed laser systems. Two simple and cost effective devices are constructed that measure common spatio-temporal distortions. The first is a spectrally-resolved knife-edge (SRKE) for spatially and spectrally resolving a laser beam, which enables spatio-temporal distortions to be measured. The second is an interferometric autocorrelation taken with a 2-photon diode. A lens is used to focus light from the entire cross section of the beam onto the diode. By scanning the diode through the focus, the effects of pulse-front-tilt on focused beam pulse durations can be measured. These techniques are compared with current theoretical models, and with each other, to establish their reliability and practicality, as well as the reliability of the commercial techniques. SRKE is found to be highly sensitive to spatial and angular dispersion, and also able to measure the frequency gradient, although not as precisely. Interferometric autocorrelation is only able to resolve effects on duration. It can detect the presence of significant spatio-temporal distortion, but several scans must be taken as a function of distance from the lens, through the focus.</p> <p> A commercially built GRENOUILLE was also tested on pulses compressed with a hollow-capillary-prism pulse compressor. Compression of 800 nm, 50 fs pulses to less than 19 fs was achieved with an overall transmission efficiency of 33%. With further work, efficiency could be increased, and pulse duration decreased.</p> / Thesis / Master of Science (MSc)

Background: The persistent Covid-19 pandemic tremendously challenged existing work teams as it drove spatial dispersion among colleagues and greater dependence on virtual communication tools. Consequently, teams were required to adapt proven communication practices that mediate the exchange of social information and the perception of proximity to teammates. Aim: We aim to broaden team studies’ theoretical understanding of communication behavior and proximity in the light of contextual changes by developing an empathic understanding of the contemporary phenomena. This entails identifying arisen communication behavior patterns and assessing the impact of behavioral changes on team members’ perception of proximity. Methodology: By conducting a qualitative case study, we investigated three teams of a medium-sized German fashion corporation. The iterative data collection entailed six semi-structured interviews with individuals and focus groups and complementary quantitative surveys. Findings: We posit that sudden spatial dispersion of familiar teams does not inevitable lead to greater perceived distance, but that a team’s ability to appropriate technology, so social needs are met, is decisive. Further, the new communication practices of all teams were found to maintain high levels of synchronicity and social informational value. Yet, communication quality and social exchange was partially hampered by reduced spontaneity, greater passiveness, and a loss of humor. This was found to be strongly influenced by team members’ attitudes towards used technology.

Composite metamaterials are periodic metal-dielectric structures operating at wavelengths larger than the structure period. If properly designed these structures behave as homogeneous media described by effective permittivity and permeability parameters. These effective parameters can be designed to take values in domains that are not available in naturally occurring media; notably it is possible to design composite metamaterials with simultaneously negative permittivity and permeability, or, in other words, with a negative refractive index. However, in many experimental or numerical studies it is far from obvious that the use of a homogeneous model is justified for a given structure at a given wavelength. This issue is often glossed over in the literature. <br />In this work I take a detailed look at the fundamental assumptions on which effective medium models rely and put forward a method for determining frequency domains where a given structure may or may not be accurately described by homogeneous effective medium parameters. This work opens the door to a more detailed understanding of the transition between homogeneous and inhomogeneous behavior in composite metamaterials, in particular by introducing the novel notions of custom made effective medium model, and of meta-photonic crystal.

Ce travail présente et valide une théorie nonlocale nouvelle et généralisée, de la propagation acoustique dans les milieux poreux à structure rigide, saturés par un fluide viscothermique. Cette théorie linéaire permet de dépasser les limites de la théorie classique basée sur la théorie de l'homogénéisation. Elle prend en compte non seulement les phénomènes de dispersion temporelle, mais aussi ceux de dispersion spatiale. Dans le cadre de la nouvelle approche, une nouvelle procédure d'homogénéisation est proposée, qui permet de trouver les propriétés acoustiques à l'échelle macroscopique, en résolvant deux problèmes d'action-réponse indépendants, posés à l'échelle microscopique de Navier-Stokes-Fourier. Contrairement à la méthode classique d'homogénéisation, aucune contrainte de séparation d'échelle n'est introduite. En l'absence de structure solide, la procédure redonne l'équation de dispersion de Kirchhoff-Langevin, qui décrit la propagation des ondes longitudinales dans les fluides viscothermiques. La nouvelle théorie et procédure d'homogénéisation nonlocale sont validées dans trois cas, portant sur des microgéométries significativement différentes. Dans le cas simple d'un tube circulaire rempli par un fluide viscothermique, on montre que les nombres d'ondes et les impédances prédits par la théorie nonlocale, coïncident avec ceux de la solution exacte de Kirchhoff, connue depuis longtemps. Au contraire, les résultats issus de la théorie locale (celle de Zwikker et Kosten, découlant de la théorie classique d'homogénéisation) ne donnent que le mode le plus attenué, et encore, seulement avec le petit désaccord existant entre la solution simplifiée de Zwikker et Kosten et celle exacte de Kirchhoff. Dans le cas où le milieu poreux est constitué d'un réseau carré de cylindres rigides parallèles, plongés dans le fluide, la propagation étant regardée dans une direction transverse, la vitesse de phase du mode le plus atténué peut être calculée en fonction de la fréquence en suivant les approches locale et nonlocale, résolues au moyen de simulations numériques par la méthode des Eléments Finis. Elle peut être calculée d'autre part par une méthode complètement différente et quasi-exacte, de diffusion multiple prenant en compte les effets viscothermiques. Ce dernier résultat quasi-exact montre un accord remarquable avec celui obtenu par la théorie nonlocale, sans restriction de longueur d'onde. Avec celui de la théorie locale, l'accord ne se produit que tant que la longueur d'onde reste assez grande.

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The widespread adoption of photonic circuits requires the economics of volume manufacturing offered by integration technology. A Complementary Metal-Oxide Semiconductor compatible silicon material platform is particularly attractive because it leverages the huge investment that has been made in silicon electronics and its high index contrast enables tight confinement of light which decreases component footprint and energy consumption. Nevertheless, there remain challenges to the development of photonic integrated circuits. Although the density of integration is advancing steady and the integration of the principal components – waveguides, optical sources and amplifiers, modulators, and photodetectors – have all been demonstrated, the integration density is low and the device library far from complete. The integration density is low primarily because of the difficulty of confining light in structures small compared to the wavelength which measured in micrometers. The device library is incomplete because of the immaturity of hybridisation on silicon of other materials required by active devices such as III-V semiconductor alloys and ferroelectric oxides and the difficulty of controlling the coupling of light between disparate material platforms. Metamaterials are nanocomposite materials which have optical properties not readily found in Nature that are defined as much by their geometry as their constituent materials. This offers the prospect of the engineering of materials to achieve integrated components with enhanced functionality. Metamaterials are a class of photonic crystals includes subwavelength grating waveguides, which have already provided breakthroughs in component performance yet require a simpler fabrication process compatible with current minimum feature size limitations. The research reported in this PhD thesis advances our understanding of the structure-property relations of key planar light circuit components and the metamaterial engineering of these properties. The analysis and simulation of components featuring structures that are only just subwavelength is complicated and consumes large computer resources especially when a three dimensional analysis of components structured over a scale larger than the wavelength is desired. This obstructs the iterative design-simulate cycle. An abstraction is required that summarises the properties of the metamaterial pertinent to the larger scale while neglecting the microscopic detail. That abstraction is known as homogenisation. It is possible to extend homogenisation from the long-wavelength limit up to the Bragg resonance (band edge). It is found that a metamaterial waveguide is accurately modeled as a continuous medium waveguide provided proper account is taken of the emergent properties of the homogenised metamaterial. A homogenised subwavelength grating waveguide structure behaves as a strongly anisotropic and spatially dispersive material with a c-axis normal to the layers of a one dimensional multi-layer structure (Kronig-Penney) or along the axis of uniformity for a two dimensional photonic crystal in three dimensional structure. Issues with boundary effects in the near Bragg resonance subwavelength are avoided either by ensuring the averaging is over an extensive path parallel to boundary or the sharp boundary is removed by graded structures. A procedure is described that enables the local homogenised index of a graded structure to be determined. These finding are confirmed by simulations and experiments on test circuits composed of Mach-Zehnder interferometers and individual components composed of regular nanostructured waveguide segments with different lengths and widths; and graded adiabatic waveguide tapers. The test chip included Lüneburg micro-lenses, which have application to Fourier optics on a chip. The measured loss of each lens is 0.72 dB. Photonic integrated circuits featuring a network of waveguides, modulators and couplers are important to applications in RF photonics, optical communications and quantum optics. Modal phase error is one of the significant limitations to the scaling of multimode interference coupler port dimension. Multimode interference couplers rely on the Talbot effect and offer the best in-class performance. Anisotropy helps reduce the Talbot length but temporal and spatial dispersion is necessary to control the modal phase error and wavelength dependence of the Talbot length. The Talbot effect in a Kronig-Penny metamaterial is analysed. It is shown that the metamaterial may be engineered to provide a close approximation to the parabolic dispersion relation required by the Talbot effect for perfect imaging. These findings are then applied to the multimode region and access waveguide tapers of a multi-slotted waveguide multimode interference coupler with slots either in the transverse direction or longitudinal direction. A novel polarisation beam splitter exploiting the anisotropy provided by a longitudinally slotted structure is demonstrated by simulation. The thesis describes the design, verification by simulation and layout of a photonic integrated circuit containing metamaterial waveguide test structures. The test and measurement of the fabricated chip and the analysis of the data is described in detail. The experimental results show good agreement with the theory, with the expected errors due to fabrication process limitations. From the Scanning Electron Microscope images and the measurements, it is clear that at the boundary of the minimum feature size limit, the error increases but still the devices can function.