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Analysis and Design of Soft-Switching Current-fed Bi-directional Power Conversion for Multifunctional Plug-in EV Charging
Get PDFThe forefront of EV battery charger research accentuates the imperative of refining power density attributes while concurrently elevating the efficiency standards of power conversion processes. The conventional EV battery chargers are developed with two cascaded power conversion stages. The first stage converts the AC voltage to a DC voltage by employing power factor correction (PFC). The second stage is an isolated DC-DC converter stage. These two-stages are interconnected by DC-link capacitors. This two-stage battery charger suffers from low overall efficiency due to two different power conversion stages. At the same time, the power density is limited due to the inevitable presence of intermediate DC-link capacitors. Generally, high-value electrolytic capacitors are selected for the DC-link. More importantly, the battery charger is placed close to the internal combustion engine under the hood in the case of a plug-in hybrid EV (PHEV), where the ambient temperature is more than 150 °C. The electrolytic capacitors are most susceptible to failure at high ambient temperature, thus the reliability of the conventional two-stage EV battery charger is low in a high-temperature environment. Moreover, the existing research on battery chargers is mainly based on voltage-fed power converter topologies, where the feasibility of current-fed power converter topologies has received very limited attention.
This thesis work proposes and studies a family of novel snubber-less current-fed isolated single-stage bidirectional power converters (AC-DC and DC-DC) for multifunctional EV battery charging (G2V, V2G, and V2V) applications to address the shortcomings of the conventional two-stage battery chargers. The proposed modulation strategy and control technique are demonstrated for promising soft-switching operation of all semiconductor devices with bidirectional power flow capability. These converters enable zero current commutated (ZCC) without any active clamp circuit or passive snubbers, which significantly reduced switching losses, footprints, and cost. The converters steady-state operation and design equations are reported in detail. The simulation results from PSIM 11.04 software and the experimental results from 1.5 kW proof-of-concept laboratory hardware prototypes are provided in order to validate the report analysis, design, and performance
Playing ‘Polly’: The Aesthetic Influence of Eighteenth-Century Actress Lavinia Fenton
Get PDFFor centuries, critics have viewed Polly Peachum as the moral centre of John Gay's The Beggar's Opera (1728). Actress Lavinia Fenton’s (1708-1760) influence on interpretations of Polly’s character may be tracked in eighteenth-century sources and continues to be discussed in contemporary criticism. Common across these discussions is the suggestion that Fenton’s performance embodied an innocent Polly possessed with moral virtue. This thesis argues that the misreading of Polly is largely owing to critics’ projection of aspects of Lavinia Fenton’s offstage experience onto Polly, and that this interweaving has had the effect of limiting our view of the actress, the character she made famous, and the creative agency it took to create the relationship between them. Rather than accepting and reiterating this outdated contextual frame, this thesis rereads several of Polly’s airs in The Beggar’s Opera as well as eighteenth-century accounts of Lavinia Fenton’s stage presence as preserved in reviews, ‘Polly’ fanfictions, and ‘Polly’s’ costume, to argue that it is more critically interesting, and more accurate, to focus on the pragmatic duplicity of these figures. Doing so sheds light on Fenton's significant literary and cultural contributions to The Beggar's Opera by establishing her investments in a campy performance style. This thesis also models a strategy for performance history that entails reading between the lines of historical sources in order to recreate the actions and motives they describe without the bias of sexism
Comparing the Informational Judgements of Autistic and Typically Developing Children: A Pilot Study
Get PDFThe moral judgements we make, and how we make them, have a critical impact on our ability to function in any social groups we are part of. They are informed by a plethora of social factors, but less is known about how the way moral judgements are formed may vary between individuals with Autism Spectrum Disorder (ASD) and their neurotypical peers. Previous research suggests autistic individuals may differ in the way they form and implement moral judgements, however, often the way these studies are implemented do not play to strengths of autistic individuals.
This study gathered qualitative data from four typically developing and four autistic 7–10-year-old children, using a novel task that asked them to consider four scenarios focused on peer altercations in a school context. Each scenario manipulated different information about the victims and the perpetrators, to determine if there was any variation between the two groups in the way this information was interpreted and used toward forming a moral judgement. Many similarities were found between groups, as well as several variations that suggest there may be different underlying assumptions between the two groups about the information given in each scenario. These variations were most salient in the areas of apologizing, the accidental nature of the incident, focusing on specific story details, and focusing on others’ feelings and intentions. These findings indicate that autistic individuals may hold different assumptions about the world around them that influence their interpretation of moral scenarios
Dual-Band Gap Waveguide Structure
Get PDFA new dual-band electromagnetic band gap (DBEBG) periodic printed structure is presented here. Designing the periodic unit cell within the periodic boundaries is sufficient to determine the EBG or DBEBG. The concept of the dual-band unit cell is based on stacking two different periodic textures with different parameters. The upper band texture considers the top of the lower band surface texture as a deformed back. Thus, a form of interaction between them makes designing each band individually challenging. Therefore, a comprehensive parametric study is required to design a DBEBG that controls the stop bands. A unit cell with a period of 1.8 mm is presented, achieving a 13-24 GHz and 34-44 GHz DBEBG with the proper parameters.
The effect of inserting the printed ridge breaking the periodicity creates propagating modes within the EBG bands, guiding the electromagnetic waves between the upper conductor and the ridge and suppressing them elsewhere, named PRGW provides dual-band, 13-24 and 34-44 GHz. A dual-band ridge with two 90-degree bends is demonstrated with simulated results of 13-22 and 32-42 GHz. Bends affect guide's scattering parameters, influencing signal reflection and transmission. Discontinuities are common in microwave systems, necessitating investigation during design them. The dual-band power divider is designed within the DBEBG structure, providing 16-24 and 32.5-42.5 GHz. Two quadrature hybrid couplers within a DBEBG support a lower band 14-26 GHz, 60% fractional bandwidth at 20 GHz and an upper band 33-41 GHz, 21.6% fractional bandwidth at 37 GHz. They maintain a 90° ±10° phase difference between coupled and through ports, with isolation levels below 10 dB. The dual-band design holds potential for millimeter-wave applications and dual-band filter design
Theory of Strategic Autonomy: U.S. Foreign Policy between 1823 and 1921
Get PDFResistance to the established world order and the dominant codes of conduct by a plurality of international actors is a repeated but misunderstood occurrence in the international system. Challengers to the status quo, ostracized states in the international system, neutrals looking for peaceful pathways to prosperity, and pivotal states unwilling to commit to a side have all searched for alternative strategies to gain power or maintain stability while maintaining autonomy of action. The theory of strategic autonomy proposes an approach to understanding such behaviour. Alliances in the international system are not always a possibility or desirable. Rather than perceiving those states as problems, I propose that they perceive and respond differently to the stimuli of the international system. This thesis looks at how and why the United States spent over a hundred years avoiding the commitment to formal alliances in the international system. The particular path of the U.S. foreign policy between 1823 and 1921 offers a complex and interesting test to the theory of strategic autonomy. While the United States disposed of an advantageous geostrategic position, European powers displayed interest in intermingling in its affairs and sphere of influence. To keep the European powers at arm’s length, the American administrations used a variety of strategies to deter the involvement of the European powers in its sphere of influence and most of all to avoid the necessity of an alliance to do so. Strategic autonomy bears increasing importance in the international system with the diminution of the relative power of the United States and the emergence of new hubs of powers including China and India. To understand how the United States achieved the status of great power without a formal commitment to the alliance system between the European powers before the Second World War is crucial to understand how China, India, or any other emerging power might be able to repeat a feat comparable to the rise of the United States power
Replaying the Past: Queer Canadian Documentary as Counter-Archive
Get PDFArchives have traditionally privileged hegemonic and normative histories, often excluding marginalized people and their memories. Emerging after the archival turn of the 1990s, "counter-archival" scholarship appeared in the early 2010s, to expand definitions of "archive" to include a more diverse body of materials and historiographical methods. These alternative processes and repositories, known as a counter-archive, can be a community archival collection, an oral history practice, a curated exhibition, an archival methodology that expresses a non-dominant sensibility, artistic practice, or more. A counter-archive typically speaks to, preserves, or represents non-dominant memories from queer, racialized, diasporic, differently abled, or Indigenous peoples, whose subjectivities may often intersect or overlap. In this thesis, I consider queer Canadian documentary film as a counter-archive, one which is a process to preserve subjective and affective memory, but also as a repository, a living collection which replays these memories. I explore how queer counter-archives use queer cinematic aesthetics, archival artefacts, talking head interviews, voiceover narration and re-enactments to preserve and replay memories of queer subjects who have resisted the pull of heteronormativity, but also how creative preservation practices express the affect, relationality, and subjectivity of queer sensibility. I analyze two queer Canadian documentaries, Forbidden Love: The Unashamed Stories of Lesbian Lives (Dir. Lynne Fernie Aerlynn Weissman, 1992) and Sea in the Blood (Dir. Richard Fung, 2000). Using Muñoz’s queer utopia framework, I explore how counter-archives replay memory to produce queer utopias, visions of a world determined by queer sensibility, a way-finder towards a place charted by self-determined subjectivity
Quantum Magneto-Straintronics Transport in Graphene: A Realistic Model
Get PDFThe main objective of this research project is to develop an applied theoretical model to describe
the quantum transport of a suspended monolayer graphene transistor under the presence of
a magnetic field and unaxial strain. In the literature, we find several theoretical models for studying
monolayer and multilayer graphene under several conditions and considering different physical
properties such as spin. Although those proposed models predict interesting physical phenomena,
such as magnetic confinement of particles, they are unrealistic and often incomplete in terms of experimental
design. Here, we present a sophisticated model using a more applied approach, enabling
future realistic experiments and the extraction of important experimental data regarding physical
phenomena such as quantum magneto transport in strained graphene junctions, bridging theory and
experiment. In order to do so, we develop a set of mathematica codes to calculate conductivity for
monolayer graphene, considering both magnetic field – which contributes to the Hamiltonian as a
vector potential- and the uniaxial mechanical strain ( x direction) – which contributes with strain
induced potentials. Two main new device geometries are introduced in this thesis: a transistor with
a magnetic field applied to its channel and another with both magnetic field and unaxial mechanical
strain. We report that those devices are candidates for quantum electronic components, which
should be of much interest for applications. They have a high on-off ratio and their conductivity is
easily suppressed by the presence of a magnetic field and mechanical strain
Exploring Alternative Pain Management Methods: Challenges and Concerns in Athletes and Women during Labor
Get PDFThis thesis reports the results of a Systematic Review with Meta-Analysis, and a research study. The Systematic Review compared the efficacy of topical versus oral medications to a placebo in athletes. A meta-analysis was conducted calculating Hedges’ g and forest plots with 95% CI were created. There was a significant pooled effect size indicating a reduction in pain for the topical medication compared to the placebo, but not for the oral medication compared to the placebo. The conclusion was that topical medication was more effective for pain reduction than oral medication amongst athletes.
The research study aimed to analyze the correlation between the Pain Catastrophizing Scale (PCS), the Labor Pain Relief Attitude Questionnaire for pregnant women (LPRAQ-p), the Edinburgh Postnatal Depression Scale (EPDS), and pain measured on the Visual Analogue Scale (VAS). Women were asked to fill out the PCS, the LPRAQ-p, and the EPDS in the prenatal period, and the EPDS once again in the postpartum period, along with the VAS regarding labor pain and current pain. The hypotheses were that the PCS would be correlated to pain, the LPRAQ-p, and the EPDS, and that the LPRAQ-p and the EPDS would be correlated. The only significant correlations amongst the questionnaires were the prenatal EPDS being correlated to the postpartum VAS, and the prenatal and postpartum EPDS being correlated. A secondary exploratory analysis showed that EPDS scores were higher amongst nulliparous women compared to multiparous women, and that the LPRAQ-p was higher in women who received analgesia
Sanitation Policies and Public Health Outcomes: What Can be Learned From New York?
Get PDFThis paper looks at how the installation of sewers, food hygiene regulations, and trash reform affected mortality from infectious diseases in Brooklyn and Manhattan from 1867 to 1927 combining data from Historical Urban Ecological dataset, the census and Brooklyn and New York Departments of Health. A linear regression with fixed effects is used to investigate which diseases these policy decisions impacted the most. The results will show that milk sanitation, a food hygiene regulation, had the greatest effect on reducing infectious diseases. Installing sewers had a beneficial effect on Manhattan, but Brooklyn saw an increase in infectious diseases as sewage from Manhattan was dumped upstream of Brooklyn. Similarly, trash reform in Manhattan worsened the health of people living in Brooklyn because trash from Manhattan was burned in Brooklyn. These results may guide policy-makers in developing countries to prioritize food safety regulations as well as sanitation of waste over relocation to minimize negative externalities
The Challenges and Barriers Facing Mature Women Entering Higher Education
Get PDFWhen adult learners decide to return to higher education, whether to seek career opportunities or for personal growth, they often experience challenges. Since the 1970s, mature women who have decided to return to post-secondary education have faced more pronounced obstacles due to the multiplicity of women’s roles, a lack of social support, and the challenges of assimilating into an environment designed for younger, traditional students. This dissertation explores the barriers mature 21st-century women face when returning to post-secondary education. It contributes to the otherwise sparse research on the undervaluing of mature women, providing updated findings on today’s mature female students. The data in this research includes narrative interviews grounded on specific themes and driven by personal conversations with the participants. Due to the recurrent themes described by the participants, a general inductive method was used through a narrative analysis framework. The findings were structured around three main pillars: situational barriers, dispositional barriers, and institutional barriers. The exploration of the situational barriers considered the personal obstacles related to domestic relationships and family obligations. The second pillar’s investigation of the dispositional barriers explicitly focused on the participants’ attitudes and perceptions regarding gender, age, socioeconomic levels, and prior educational experiences. Finally, the consideration of institutional barriers examined the lack of visibility and equity provided by institutions of higher learning to non-traditional, mature female students