This thesis presents research on the feasibility of applying compliant-ortho-planar springs (COPS) to rotational applications. The primary motivation of this research is the application of COPS to a continuously variable transmission (CVT). The design space limitations, loading conditions, stresses, stress concentrations, and limitations of current design tools, such as pseudo-rigid-body models (PRBM) for COPS, are discussed. A new 3D PRBM is presented along with a discussion on the possible applications of such to a rotating COPS. Stress stiffening and lateral stability are two major phenomena occurring in a rotating COPS. Both phenomena are a direct result of the inertial loads a COPS would be subjected to in a rotational environment. The results show how stress stiffening and lateral buckling in the legs are influenced by design parameters. Conclusions and recommendations for further research are recommended.

Yes / The antenna presented in this study is a compact wideband monopole with wideband circular polarization that can be used across the whole antenna bandwidth. A rectangular C-shaped patch is partially covered by a ground plane in the proposed planar monopole antenna. Inserting a rectangular stub to the ground plane, etching a slit at the antenna patch, and adding a semicircular stub at the top of the antenna feed line increase the antenna impedance bandwidth (BW) and axial ratio bandwidth (ARBW). An FR4 substrate with overall dimensions of 25 mm×25 mm×1.6 mm is used to create the antenna. The antenna's observed impedance BW is 70% (4.55 GHz in the 4.3-8.85 GHz band), while the measured broadside ARBW is improved to a value of 82.2 percent (5.3 GHz along the range 3.8-9.1 GHz). The impedance BW is perfectly covered by the ARBW; hence the antenna can be considered circularly polarized throughout its operational spectrum. Within the antenna BW, the measured gain is greater than 1.5 dB.

<p> Determination of boiling heat transfer rate during liquid jet impingement cooling (LJIC) depends on the intensity of bubble generation that is dependent on many flow and surface conditions such as jet velocity, liquid temperature, and surface superheat. Many empirical correlations have been developed previously to determine the total wall heat flux under various LJIC flow velocity, subcooling and surface superheat. However, only few studies have been able to model the governing heat transfer mechanisms associated with LJIC. In many industrial applications, there is a need to determine the effect of any changes in processing parameters on the total rate of heat transfer. Mechanistic heat transfer models can fulfill such need and allow for efficient model modifications at minimum cost and time.</p> <p> Three models have been developed in this study that address the underlying physics associated with jet impingement heat transfer in both single phase and nucleate boiling regimes. The first model accounts for the effect of bubble generation on the overall heat transfer rate at the jet stagnation by introducing a bubble-induced diffusivity (BID). The BID is added to molecular diffusivities in the momentum and energy Equations. The BID model adopts an analogous approach to the eddy diffusivity concept used in turbulence flow modeling. The BID model has been developed to provide a cost effective simulation tool of boiling heat transfer during LJIC by considering bubble generation effect on the overall heat transfer rate while avoiding the need to simulate extremely small time and length scales associated with phase change.</p> <p> The second model is a scenario identification procedure (SIP) that has been developed to predict the bubble growth termination (BGT) scenario. Considering the effect of jet velocity, water subcooling and surface superheat, the SIP identifies whether a bubble would locally collapse or slide by identifying the most probable equilibrium condition (thermal or dynamic) that the bubble would reach first. The main objective of the SIP is to avoid any inaccurate assumption of the probable BGT scenario. In this case, such procedure could improve the predictions of a more comprehensive wall heat flux model of the areas affected by various heat transfer mechanisms.</p> <p> The third model is a mechanistic wall flux partitioning (WFP) model that has been developed to predict the local wall heat transfer rate over the distance between jet stagnation and ten times the jet width. The WFP model assumes that primary heat transfer is due to sensible heating of liquid by forced convection and transient conduction. The WFP model incorporates a unified single-phase heat transfer model that is capable of capturing the observed secondary peaks downstream of stagnation. The WFP model also incorporates a sub-model that predicts abrupt changes in the liquid film thickness due to the formation of hydraulic jumps.</p> <p> The development of these three models have been carried out using experimental data obtained from a set of experiments that has been conducted to investigate the variation of the heat transfer rate and bubble dynamics under a planar free liquid jet. Investigation of bubble dynamics has been conducted using both intrusive optical probe and non-intrusive high speed imaging of the flow filed. The experiments have been conducted at atmospheric pressure, considering jet velocity of 0.4 to 1.7 m/s, degree of water subcooling of 10 to 28 °C, degree of wall superheat of -25 to 30 °C. Such variations have been studied along a heated surface between stagnation and ten times the jet width. Experiments were conducted using a 1 mm x 8 mm planar jet impinging on a heated horizontal flat copper surface. The distance between the jet and the heated surface was 10 mm. The experimental data have been used to develop a group of sub-models for single-phase heat transfer, bubble diameter, bubble population density, bubble release frequency, and bubble growth time. These sub-models have been used in the closure of the aforementioned models.</p> <p> The three models have been validated using independent experimental data. The BID model is capable of predicting stagnation heat flux within -15% and +30%. The SIP model was able to predict the right bubble growth termination scenario of 80% of the investigated cases. The WFP model is capable of predicting the local total wall heat flux within± 30%.</p> / Thesis / Doctor of Philosophy (PhD)

<p> 1-by-N optical power splitters are primary components in the field of integrated optics and optical transmission systems. Planar waveguide optical power splitters are key devices to realize low-cost optical transmission systems through photonic integration. The goal of this thesis is to design, model and simulate a novel planar waveguide optical power splitter for optical transmission systems and Fiber to the Home (FTTH) networks.</p> <p> The first chapter is an introduction. This chapter gives the background of power splitter, reviews the existing devices and explains why our novel design is needed.</p> <p> The idea of this novel power splitter is presented in Chapter 2, including analytical formulations, theoretical calculations and designs. This serves as a theoretical foundation for the development and verification of different parts presented in Chapter 3. The novel power splitter design is composed of a series of waveguide lenses and waveguide phase shifts. The analytical formulations are derived and intensive numerical simulations are performed to verify and investigate this new power splitter. Also the conventional Beam Propagation Method (BPM) is studied in this chapter, which provides a numerical preparation for the device simulation and design in the subsequent chapter.</p> <p> The design results are shown in Chapter 4. The novel power splitter design predicts good performance with more compact device size, better output and smaller wavelength dependence. This chapter demonstrated the possibility of new power splitter working as a better approach to the existing MMI or other structures.</p> <p> Finally, Chapter 5 gives a conclusion to this thesis. The limitations of this work are presented and the future works are proposed.</p> / Thesis / Master of Applied Science (MASc)

Manipulating the flow of light is critical in the design and fabrication of light-based devices ranging from solar cells, smart cameras, liquid crystal display (LCD) screens, projectors and light emitting diodes (LEDs). Thin films configured with spatial patterns or modulations in refractive index exhibit strong and richly varied interactions with light beams. In this thesis, we show that embedding planar films with specific geometries of waveguide lattices allows precise control over the inflow and outflow of light. Specifically, we demonstrate the fabrication of a new class of waveguide-encoded polymer films that are generated through a single-step, room temperature technique. Here, waveguide encoded lattices with a range of symmetries are spontaneously inscribed in photopolymerizable resins by self-trapped beams of incandescent light. We describe the generation of lattices consisting of five intersecting arrays of waveguides, which confer a range of unprecedented properties including a large, panoramic field of view (FOV) infinite depth of field and multiple imaging functionalities including focusing and inversion. We have also fabricated lattices inspired by natural arthropodal compound eyes, which comprise a radial distribution of waveguide and in turn impart a continuous, enhanced FOV. We demonstrate the application of these films in controlling the beam profiles of LEDs including their divergence and convergence. Finally, we show that thin films patterned with a periodic array of planar waveguides serve as effective beam steering coatings, which deflect light away from the metallic front contacts of commercially available solar cells and in this way, increase their efficiency. / Thesis / Doctor of Philosophy (PhD)

Design of magnetic component is a key factor in achieving high frequency, high power-density converters. Planar magnetics are widely used in bias power supplies for the benefits of low profile and their compatibility with printed-circuit boards (PCB). The coupled inductors with winding layers sandwiched between two core plates are studied in this dissertation in order to model the self-inductance, winding loss, and core loss. The most challenging task for the plate-core inductor is to model the magnetic field with finite core dimensions, very non-uniform flux pattern, and large fringing flux. The winding is placed near the edge of the core to maximize the energy within the limited footprint and the amount of energy stored outside the core volume is not negligible. The proportional-reluctance, equal-flux (PREF) model is developed to build the contours with equal amount of flux by governing the reluctance of the flux path. The shapes of the flux lines are modeled by different functions that guided by the finite-element simulation (FES). The field from the flux lines enables calculation of inductance, winding loss, and core loss, etc. The inductance matrix including self-inductance and mutual inductance of a coupled inductor is important for circuit simulation and evaluation. The derivation of the inductance matrix of inductors with plate-core structure is described in Chapter 2. Two conditions are defined as common-mode (CM) field and differential-mode (DM) field in order to compute the matrix parameters. The proportional-reluctance, equal-flux (PREF) model introduced is employed to find the CM field distribution, and the DM field distribution is found from functions analogous to that of a solenoid's field. The inductance calculated are verified by flex-circuit prototypes with various dimensions, and the application of the inductance model is presented at the last with normalized parameters to cover structures within a wide-range. In circuit where coupled inductors are used instead of transformers, the phase shift between the primary and secondary side is not always 180 degrees. Therefore, it is important to model the winding loss for a coupled inductor accurately. The winding loss can be calculated from the resistance matrix, which is independent of excitations but only relates to the frequency and geometry. The methodology to derive the resistance matrix from winding losses of coupled inductors is discussed. Winding loss model with 2D magnetic field is improved by including the additional eddy current loss for better accuracy for the plate-core structures. The resistance matrix calculated from the model is verified by both measurement results and finite-element simulation (FES) of coupled-inductor prototypes. Accurate core loss model is required for designing magnetic components in power converters. Most existing core loss models are based on frequency domain calculation and they cannot be implemented in SPICE simulations. The core loss model in the time domain is discussed in Chapter 5 for arbitrary current excitations. An effective ac flux density is derived to simplify the core loss calculation with non-uniform field distribution. A sub-circuit for core loss simulation is established in LTSPICE that is capable of being integrated to the power stage simulation. Transient behavior and accurate simulation results from the LTSPICE matches very well with the FES results. An equivalent circuit for coupled windings is developed for inductors with significant fringing effect. The equivalent circuit is derived from a physical model that captures the flux paths by having a leakage inductor and two mutual inductors on the primary and secondary side. A mutual resistor is added to each side in parallel with one mutual inductor to model the winding loss with open circuit and phase-shift impact. Two time-varying resistors are employed to represent the core loss in the time-domain. The equivalent circuit is verified by both finite-element simulation (FES) and prototypes fabricated with flexible circuit. / Ph. D.

This thesis details the investigation into the Whirling Planar Pendulum system. The WPP is a pendulum that is spun around a vertical spin axis at a controllable horizontal offset. This dynamical system exhibits both local and global bifurcations. The local pitchfork bifurcation leads to the splitting of a single stable equilibrium point into three (two stable and one unstable), as the spin rate is increased. The global bifurcations lead to two independent types of chaotic oscillations which are induced by sinusoidal excitations. The types of chaos are each associated with one of two homoclinic orbits in the system's phase portraits. The onset of each type of chaos is investigated through Melnikov's Method applied to the system's Hamiltonian, to find parameters at which the stable and unstable manifolds intersect transversely, indicating the onset of chaotic motion. These results are compared to simulation results, which suggest chaotic motion through the appearance of strange attractors in the Poincaré maps. Additionally, evidence of the WPP system experiencing both types of chaos simultaneously was found, resulting in a merger of two distinct types of strange attractor. / Master of Science / This report details the investigation into the Whirling Planar Pendulum system. The WPP is a pendulum that is spun around a vertical spin axis at a controllable horizontal offset. This system can be used to investigate what are known as local and global bifurcations. A local bifurcation occurs when the single equilibrium state (corresponding to the pendulum hanging straight down) when spun at low speeds, bifurcates into three equilibria when the spin rate is increased beyond a certain value. The global bifurcations occur when the system experiences sinusoidal forcing near certain equilibrium conditions. The resulting chaotic oscillations are investigated using Melnikov’s method, which determines when the sinusoidal forcing results in chaotic motion. This chaotic motion comes in two types, which cause the system to behave in different ways. Melnikov’s method, and results from a simulation were used to determine the parameter values in which the pendulum experiences each type of chaos. It was seen that at certain parameter values, the WPP experiences both types of chaos, supporting the observation that these types of chaos are not necessarily independent of each other, but can merge and interact.

Hardy space scalar theory on the disk is now classical. Some extensions have been done, one of them is the approach done by Donald Sarason using Laurent series. We present the more complicated function theory, without the use of either power series or Laurent series, for finitely-connected planar domains. / Master of Science

Dans l'aéronautique, l'alimentation d'un système embarqué contribue largement à augmenter le coût récurrent, l'efficacité globale et le volume de l'équipement. De plus, les alimentations sont installées dans un environnement sévère avec une large plage de tension d'entrée et un milieu confiné. Dans ces conditions, les pertes du convertisseur influent fortement sur le volume et le poids du système qui doit s'efforcer de limiter les échauffements. Ainsi, la réduction des pertes du convertisseur est l'un des leviers les plus efficaces pour augmenter la densité de puissance des convertisseurs. Parmi les techniques connues, la commutation douce peut être une solution pour réduire les pertes du convertisseur tout en augmentant sa fréquence de découpage. La sélection d'une topologie à commutation douce se fait selon 3 critères; un faible nombre de composants, une fonction de transfert et des commutations douces qui couvrent toute la plage de fonctionnement. En prenant tout cela en considération, la meilleure candidate semble être la topologie Flyback active-clamp. Avec seulement une capacité et un transistor supplémentaires, cette topologie possède une fonction abaisseuse et élévatrice et réalise des commutations en ZVS au primaire.Un travail technologique doit également être réalisé afin d'améliorer davantage l'efficacité du convertisseur. Les technologies qui ont été sélectionnées sont les transistors GaN pour leurs performances en commutation et le transformateur planar pour son intégration dans le PCB. Par ailleurs, une intégration verticale du convertisseur qui est à présent sur deux cartes superposées, une pour les fonctions BF et l'autre pour les fonctions HF, a permis de minimiser l'empreinte du convertisseur.Les technologies émergentes vont faire un important saut technologique, en particulier dans les systèmes où l'alimentation représente une part significative de l'équipement. Le succès des transistors GaN met clairement en lumière que l'électronique de puissance devient plus performante. Dans ce contexte, réduire les éléments parasites est une priorité. En se projetant dans le futur, l'intérêt porté aux alimentations intégrées va accélérer le développement des techniques de packaging telles que l'enfouissement des composants dans le PCB et les modules sur céramique / The power supply system in an onboard aeronautical application represents an important contribution to the recurring cost, global efficiency and the volume of the system. Moreover, power supplies are installed in a harsh environment with a wide input voltage range and a confined area. In these conditions, power supply losses impact the converter volume and weight to prevent the system from overheating. Therefore, a gain in efficiency is the main purposes, since it has a significant impact on the reduction of weight and volume of the equipment.Soft-switching is a reasonable technique to increase the switching frequency and limit the power losses. The selection of the topology should take into account 3 considerations: a low number of components, an efficient control, which allows to cover the wide input voltage range and a soft-switching validity over a large input voltage range. Regarding all the considerations, the Flyback active-Clamp topology seems to be the best candidate which has a step-up and down transfer function and ZVS at the primary with only ones additional capacitor and transistor.A technological work is also done to further increase the power supply efficiency. The technologies which have been selected are the GaN transistors for its good switching performances and a planar transformer for its integration into the PCB. Also, the vertical integration of the converter which is actually on two stackable boards, one for the low frequency functions and the other one for the high frequency functions, minimizes the footprint of the converter. The new technologies will make a huge technological leap, especially in the systems where the power supply represents a significant proportion of the equipment. The success of GaN transistor highlights that the power electronics is currently driving by the performance and reducing the parasitic elements is becoming the priority. Looking forward into the future, the interest in 3D packaging and PCB integration will grow rapidly to provide a fully embedded power supply

Propõe-se, com este trabalho, estudar numericamente se a redundância cinemática e a redundância de atuação podem ser boas alternativas para que manipuladores planares de cinemática paralela atinjam altas acelerações. Sabe-se que estes tipos de redundância promovem uma redução de singularidades do sistema robótico entre outros benefícios. No entanto, a avaliação comparativa do desempenho dinâmico de manipuladores redundantes ainda é pouco estudada. Este estudo não é trivial pois a redundância significa não somente o aumento do torque disponível, mas também que a inércia do sistema foi aumentada. A avaliação numérica deste trabalho se dará por meio do desenvolvimento de modelos cinemáticos e dinâmicos das possíveis configurações de manipuladores paralelos planares com redundância cinemática e redundância de atuação. Esta avaliação pode ser feita pela comparação entre os manipuladores redundantes e o não-redundante para desenvolver uma mesma trajetória do end-effector. Entretanto, esta avaliação é dependente da trajetória, logo esse trabalho também propõe uma avaliação através de um índice dinâmico em toda a área de trabalho dos manipuladores. / The aim of this work is to study numerically if the kinematic redundancy and the actuation redundancy can be good alternatives for parallel planar manipulators to achieve high accelerations. It is known that types of redundancy promote, among other benefits, a significant reduction in the singularities. However, the evaluation of the redundancy as a good solution to increase the dynamic performance was not studied. This study is not trivial because the redundancy means not only that there is more torque available, but also that the inertia of the system has been considerably increased. Different configurations of the redundant manipulator will be evaluated numerically through kinematic and dynamic models. This evaluation can be performed by the comparison among the non redundant manipulator and the redundant manipulators to execute the same task. This evaluation is task dependent, so this work proposes a dynamic index to desing dynamic maps over the workspace.