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Tracking Control of Autonomous Vehicles
Get PDFThis thesis intends to design new tracking schemes to enhance the performance and stability of general autonomous vehicles (AVs). Three main types of controllers used for tracking control are investigated.
The geometric controller cannot meet high tracking requirements, and control parameters significantly affect its performance. Therefore, an observer-based nonlinear control combined with a particle swarm optimization (PSO) algorithm is developed for low-speed vehicles to track the pre-determined trajectory accurately. A control law featured with self-tuning gains is designed using the backstepping control technique, for which global asymptotic stability is validated. The PSO evaluates tracking performance through the proposed fitness function and generates optimized tuning parameters with fewer iterations, reducing tuning efforts. Velocity and steering tracking could also be rapidly realized by modifying the error weights of the performance evaluation criterion. Based on the proposed yaw error observer (YEO), the problem of the angle measurements being temporarily inaccurate or unavailable is tackled effectively with the given information.
Further, existing methods can suffer from complex control algorithms and a lack of tracking stability at high speed. The vehicle's motion is decoupled by considering the Frenet frame. A lateral control law based on the linear-quadratic-regulator (LQR) imposes the tracking errors to converge to zero stably and quickly, providing the optimal solution in real-time due to adaptive gains. Regarding the steady-state errors, they are eliminated through the correction of the feedforward term. Besides, the designed double proportional-integral-derivative (PID) controller realizes not only the longitudinal control but also the velocity tracking
Development of Inverse Modeling Method for Emission Source Identification in River Pollution Incidents
Get PDFAccidental spills and illegal chemical discharges have occurred worldwide, causing adverse effects on human health and the ecosystem. Inverse models play an essential role in source identification based on limited concentration data observed at monitoring sites. However, most studies have been conducted on the inverse inference of pollution sources in atmospheric and groundwater environments. Few studies have focused on identifying pollution sources in rivers. In addition, multiple source identification, uncertainty quantification and sensitivity analysis of inverse models are rarely considered. An integrated inverse modeling system is developed in this thesis for source identification in river pollution incidents, including three independent inverse modeling approaches for an instantaneous point source (IPS), a continuous point source (CPS), and multi-point sources (MPS), respectively. The inverse modeling approach estimates source parameters with uncertainty concerns by combining a water quality model and a probabilistic inverse method based on observed pollutant concentrations.
First, the IPS inverse modeling approach is developed based on the Metropolis-Hastings (MH) method. Then the developed MH-based IPS approach is tested and compared with a genetic algorithm (GA)-based IPS approach for a hypothetical case and a real case study. Results confirm that the MH-based IPS approach performs better than the GA-based IPS approach in terms of accuracy and stability for IPS source identification. According to the sensitivity analysis, the emission mass of the pollution source positively correlates with the dispersion coefficient and the river cross-sectional area, whereas the flow velocity significantly affects the identified values of release location and release time. Second, the CPS inverse modeling approach employed the up-to-date DiffeRential Evolution Adaptive Metropolis (DREAM) algorithm to estimate source parameters. The DREAM-based CPS inverse modeling approach accurately performs in a hypothetical case and a field tracer case. Moreover, compared to the MH-based and GA-based CPS approaches for CPS identification, the DREAM-based CPS approach has an advantage in accuracy, computation time, and reconstructing the time series of pollutant concentrations. The accuracy of the approach can be improved by decreasing observation errors, increasing the monitoring number, and deciding monitoring locations closer to the spill site. Third, the MPS inverse modeling approach is developed based on the DREAM algorithm. The one-point, two-point, and three-point source problems are considered in case studies to validate the feasibility and accuracy of the DREAM-based MPS approach. Among the three identified source parameters, the identification error of the release time tends to rise obviously in response to the increase in pollution sources. Subsequently, an integrated inverse modeling system with a graphical user interface is established based on the three developed inverse modeling approaches, and its efficiency is tested through case studies. In conclusion, the integrated system can serve as a helpful tool for source identification, model validation, and pollution prediction in the assessment and management of emergency pollution incidents
“They are not our secretaries”: Wonder, Women and Superhero Cinema An ethnography of moviegoers in Brazil
Get PDFSuperhero cinema requires the engagement of the audience to be successful and to ensure its continuation. It contributes the establishment of the public pedagogy of our societies, informing what ideologies are intrinsic to the understanding of our common realities and normalizing patterns of conduct. Movie posters from superhero films depicting women have, however, been changed from representations based on the accommodation of male fantasies – thus generally sexualizing the female body – to depictions more attuned to female audiences’ expectations. This research aims to investigate the way these movie posters have been received by a group of nine women from Fortaleza, Brazil, trying to answer the question: how much representation have these women felt from these movie posters over the past few years? It brings about several points of tension since Brazil is a society where patterns of beauty are exported throughout the world. Being consumers of popular culture, and having their everyday lives impacted by these cultural products, the research participants discuss how superhero cinema in the last decade or so has been transformed by the advent of the release of Wonder Woman (2017), with results that defend the movie as a turning point in superhero cinema, but also open unexpected discussions about other products as somewhat responsible for such change. In order to do so, they have been invited to take part in a private conversation while discussing movie posters curated in a virtual exhibit with over sixty images positioned chronologically, with the goal of assessing their relationality with those posters, their take on each of them and how they understood the studios’ decision in promoting each movie the way it came to be. As an interdisciplinary endeavor, the research was the result of a conversation that includes visual anthropology, public pedagogy, sociology, women studies, feminist cinema and media studies
The Political Struggle Behind the Delgamuukw Case: The 1994-1996 Trilateral Treaty Negotiations with the Gitxsan and Wet’suwet’en
Get PDFThis thesis examines the political struggle behind the Delgamuukw court case, particularly the 1994-1996 trilateral treaty negotiations with the Gitxsan and Wet’suwet’en.
The Gitxsan and Wet’suwet’en’s quests to have their Aboriginal rights and title recognized, and to prevent resource depletion in their hereditary territories, were intricately connected and multi-faceted. The Delgamuukw court case, which is often treated as a distinct issue, should be examined in the context of all significant events, both those which took place in the Gitxsan and Wet’suwet’en territories, as well as those at the negotiating tables. Although Aboriginal peoples’ struggle to preserve their cultural identity dates back to their early contact with the newcomers, colonial governance changed significantly in the 1980s. The neo-liberal governments of Canada and British Columbia moved from the paternalistic policies of the Indian Act to supporting industrial encroachment on a large scale. Neo-liberal governments tend to show benevolence. In fact, their policies may be as harmful as the colonial policies from the first half of the 20th century. In 1990, British Columbia joined the treaty negotiations and commissioned the establishment of the B.C. treaty negotiations process. The Gitxsan and Wet’suwet’en were among those First Nations who undertook negotiations with the provincial government soon after the process had been established. Therefore, their experience provides valuable insight into how this new process started in the 1990s. Since that time, the B.C. treaty process has been extremely unproductive, and the Gitxsan and Wet’suwet’en trilateral treaty negotiations are among the many examples of its failure
Pediatric Bone Age Analysis and Brain Disease Prediction for Computer-Aided Diagnosis
Get PDFRecent advances in 3D scanning technology have led to a widespread use of 3D shapes in a multitude
of fields, including computer vision and medical imaging. These shapes are, however, often
contaminated by noise, which needs to be removed or attenuated in order to ensure high-quality
3D shapes for subsequent use in downstream tasks. On the other hand, the availability of largescale
pediatric hand radiographs and brain imaging benchmarks has sparked a surge of interest
in designing efficient techniques for bone age assessment and brain disease prediction, which are
fundamental problems in computer-aided diagnosis. Bone age is an effective metric for assessing
the skeletal and biological maturity of children, while understanding how the brain develops is
crucial for designing prediction models for the classification of brain disorders.
In this thesis, we present a feature-preserving framework for carpal bone surface denoising in the
graph signal processing setting. The proposed denoising framework is formulated as a constrained
optimization problem with an objective function comprised of a fidelity term specified by a noise
model and a regularization term associated with data prior. We show through experimental results
that our approach can remove noise effectively while preserving the nonlinear features of surfaces,
such as curved surface regions and fine details. Moreover, recovering high quality surfaces from
noisy carpal bone surfaces is of paramount importance to the diagnosis of wrist pathologies, such
as arthritis and carpal tunnel syndrome. We also introduce a deep learning approach to pediatric
bone age assessment using instance segmentation and ridge regression. This approach is comprised
of two intertwined stages. In the first stage, we employ an image annotation and instance
segmentation model to extract and separate different regions of interests in an image. In the second
stage, we leverage the power of transfer learning by designing a deep neural network with
a ridge regression output layer. For the classification of brain disorders, we propose an aggregator
normalization graph convolutional network by exploiting aggregation in graph sampling, skip
connections and identity mapping. We also integrate both imaging and non-imaging features into
the graph nodes and edges, respectively, with the aim of augmenting predictive capabilities. We
validate our proposed approaches through extensive experiments on various benchmark datasets,
demonstrating competitive performance in comparison with strong baseline methods
Modeling and Indirect Force/Position Control of Slender Continuum Robots
Get PDFIn this thesis, a novel semi-analytical method is proposed for the pseudo-rigid body (PRB) modeling of highly flexible slender continuum robots (CRs) with no constraint on the number of degrees of freedom of the PRB model. The proposed method has a simple formulation and high precision. Furthermore, it can describe initially-curved variable-length CRs having a variable stiffness along the length. The versatility of the method is investigated for the PRB modeling of the slender CRs, such as steerable catheters and concentric tubes. A new analytical formulation is also introduced for the Cartesian stiffness of the CRs using the proposed PRB model. The existing formulations for the Cartesian stiffness in the literature, such as enhanced stiffness and constant stiffness models, fail to properly describe CRs force/deflection behavior with large nonlinear deformation. However, it is shown that the proposed method gives a high precision estimation of the applied force at the CR tip. Additionally, the proposed Cartesian stiffness is a function of deflection and allows indirect force estimation using the knowledge of only the tip point deflection, which makes it ideal for concentric tube robots (CTR) in vitreoretinal surgeries. The formulation of the stiffness is then used for the simultaneous force/position control of the CTRs interacting with a soft environment. The governing equation is a boundary value problem, and the existing control architectures for the simultaneous force/position control in rigid robotics cannot be directly used. Furthermore, in CTRs, the distributed friction force among the tubes and also at the entry port in vitreoretinal surgeries is beyond the desired force at the robot tip. Thus, the conventional method to map the task space forces to that of the joint space, which is fundamental in the existing force control methods, cannot be used. Therefore, a new control architecture is devised for the indirect hybrid force/position control of a variable-length initially-curved CTR. The proposed method uses displacement as the control input to the robot and proves effective for environments with a wide range of stiffness
From Fandom to Future Representation: Sapphic and Alternative Media as Creation
Get PDFFor my research creation project, I wrote and produced a web series script and pilot centring 2SLGBTQIA+ Jewish women and their daily lives. I made an original narrative through the web series, as a device to explore fan production and subversion of the text Wicked. I did this by creat- ing my own “Fan” production— a script featuring positive representation of queer women in fan- dom, with the novel as a back drop and story catalyst, titled Mazel. The project was created in three stages: three interviews with members of the Canadian sapphic community pertaining to what they would like to see from sapphic representation, the completion of a script for a web se- ries written with inspiration from said interviews, and the filming of a short pilot webisode. I was then privileged to host a community talk-back in coordination with the Museum of Jewish Mont- real, wherein we discussed what sapphic folks considers good representation and negative repre- sentation. The project’s aim is to provide an invitation to fellow sapphic creators to explore how they want their stories told, on their own terms
Assessment of greenhouse gas emissions from soybean cropping system: A case study of Ontario in Canada
Get PDFSoybean (Glycine max L.) is the fourth largest Canadian field crop covering around 2×106 hectares of land. Soybean crops take up more than 50% of Canada’s cultivated areas and contribute significantly to greenhouse gas (GHG) emissions in cropping system. The present study assesses GHG emissions from Ontario soybean fields. In this study, the crop districts of Ontario were divided into five categories: southern Ontario, western Ontario, central Ontario, eastern Ontario, and northern Ontario, and a general model for assessing emissions was developed. Emissions from the manufacturing and transportation of nitrogen/phosphorus (N/P) fertilizer, emissions from field operations, emissions from herbicide usage, and both direct and indirect emissions from agricultural lands were considered the major sources of GHGs. The results showed that total GHG emissions were around 7×105 Mg CO2-eq in 2018. The largest emission contributor was agricultural land, with emissions of 5.3×105 Mg CO2-eq, accounting for 77% of the total emissions. Moreover, GHG emissions were significantly influenced by environmental conditions. As precipitation/evapotranspiration (Pr/PE) decreased, total GHG emissions declined from southern Ontario to central Ontario. In southern Ontario (high Pr/PE), GHG emissions based on crop yield were 492 kg CO2-eq per hectare of seeding area, which was 46% greater than those in northern Ontario (low Pr/PE). GHG emissions from agricultural lands were the highest contributor to total GHG emissions among the four emission sources in all crop districts. Fertilizer N inputs accounted for the largest portion of agricultural land emissions in southern and central Ontario, while in other regions, crop residue N input was the largest source. A multivariate factorial analysis was also used to estimate the effect of uncertain parameters on system performance, and the main impacts, and their interactions were identified. The resutls demonstrated that farming practices had the most significant impact on total GHG emissions. Understanding the detailed impacts of these elements and their interactions can help determine major factors that influence total GHG emissions and allow us to implement appropriate strategies to mitigate agricultural GHG emissions
Effect of the Acetylcholinesterase Inhibitor Donepezil on Human Immune Cells in Peripheral Blood Mononuclear Cells
No full textDonepezil is an acetylcholine esterase inhibitor that improves symptoms in Alzheimer’s Disease. It is known to stimulate cholinergic receptors on helper T cells and can change the pro and anti-inflammatory cytokines which is important in autoimmune diseases as well as neurodegenerative diseases. The effect of donepezil on modulating helper T cell differentiation the immune system is not clearly understood. To begin to address this question, peripheral blood mononuclear cells were studied from healthy participants' venous blood. The experiments were done using cell culture methods. The cytokines that were measured include anti-inflammatory IL-4, and pro-inflammatory IFNγ and IL-17A. Cell viability was determined with trypan blue after four days of incubation with activation, and different dosages of donepezil (0.8, 4, 20, and 100 ng/mL). Aggregate data illustrated the amount of IL-17A was lower after being treated with 20 ng/mL in comparison with 0.8 and 4 ng/mL. There was no significant change in the amount of IL-4, IFNγ, or cell viability after four days. In conclusion, T cells can be regulated by cholinergic drugs and receptors but the mechanism of action is not fully understood
Experiencing Leisure Kits in Relation to Art Education: A Research Creation Project
Get PDFArtistic leisure kits, such as paint by numbers, became a popular item in demand throughout the pandemic. As I was dealing with the anxiety of uncertainty and the overwhelming amount of information, I decided to investigate the popularity of leisure kits and their possible incorporation as a transitional strategy within an art classroom. People writing about these kits claimed they might fulfill the newly acquired leisure time that appeared due to the mandatory isolation, while simultaneously releasing tension and dissipating overthinking. Due to their increasing popularity, I wanted to find out what people experience when working with leisure kits, and if they might help lead to creativity. My research question was, does completing leisure kits provide any learning outcomes, and if so, what are those outcomes? Using research-creation methodology and heuristics, I discovered the potential of leisure kits for the increase of confidence and motivation, the experience of flow, and the decrease of art anxiety that support the creative process. I immersed myself in the process by completing three different types of kits to gather information through the discovery phases. In parallel, I interviewed the people who inspired me to explore this avenue, specifically, those who tried kits for similar reasons I did. The interviews allowed me to gather additional information about their thinking process through making, their potential learning experience, and the results achieved. Learning outcomes also emerged, such as problem-solving skills, motor stills, and the questioning of pre-conceived notions of art practice and the necessary skills to achieve them