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Embedding Ionic Hydrogel in 3D Printed Human-Centric Devices for Mechanical Sensing
Get PDFFlexible sensor applications have increasingly focused on ionically conductive hydrogels due to their notable deformability and easily tunable properties compared to rigid materials. These hydrogels are conductive thanks to their high water content and porous structure, enabling effective ion transfer. Despite their attractive features, hydrogels have limited water retention and shape fidelity, and they are more typically inspected as two-dimensional films and patches. Here, 3D printed thermoplastic polyurethane (TPU) frames with various geometries were injected with ionic conductive hydrogels to create durable, robust soft mechanical sensors for detecting mechanical stimuli through changes in their electrical resistance. After the TPU encasement was shown to maintain the hydrogel water content, hydrogel-embedded frames with varying geometries were designed. Their response to mechanical loading was investigated in relation to their dimensions and geometric shape. Finally, glove-shaped frames were fabricated and injected with ionic hydrogel for sensing abilities. The wearable sensors accommodated free movement of the fingers in multiple directions and were able to detect simultaneous and independent bending and stretching of the fingers. Through comprehensive observation of the electrical behavior of the ionic sensors in response to different kinds of mechanical stimuli, it was concluded that the resistance change following mechanical loading was dependent on the geometric features of each hybrid sensor. Thus, hydrogel-embedded TPU encasement could be designed with targeted geometry to dictate the type and direction of mechanical sensing. This work presents a facile approach to fabricating multi-component soft geometric sensors with potential to be used for wearable electronics and human-machine interactions
Target Valuation and its Effect on Acquirer Acquisition Behavior
Get PDFA long-standing theory in mergers and acquisitions is that overvalued firms can create value by using stock payment as an acquisition option. This study challenges the notion that firm overvaluation is a driver of stock acquisitions. These acquisitions do not lead to major synergy gains. Additionally, we examine the reason why firms opt for stock acquisitions by examining acquisition completion time, synergies, premiums and returns. We find that stock overvaluation is not a significant motive for stock acquisitions as the benefit from overvalued acquisitions is offset by negative synergy, returns and high premiums
Habitat suitability, space use, and human-wildlife coexistence for wild river otters (Lontra canadensis)
Get PDFLand use change and urban sprawl increase the likelihood of encounters between humans and wildlife. River otters (Lontra canadensis) are a species that coexists, but also conflicts, with humans over the use of space on Protection Island, British Columbia. River otters are sensitive to human-induced disturbances yet also inhabit environments with relatively high densities of humans and anthropogenic structures. I investigated the effect of human activity and disturbance on river otter use of space and behaviour to elucidate implications for habitat suitability and wildlife management in anthropogenic landscapes. I drew on 23 semi-structured core interviews and 18 surveys to discuss the human-otter dynamics on the island and perceptions of river otter behavior among residents. I then investigated the relative importance of anthropogenic (e.g., distance to buildings and roads, level of human use of docks), environmental (e.g., land cover type), biological (distance to dens), and topographic (elevation) variables for habitat suitability in wild river otters sharing their environment with humans. I used maximum entropy (MaxEnt) species distribution models to identify the most important factors for river otter habitat suitability and space use in anthropogenic landscapes. Two scenarios were modeled with MaxEnt using 660 and 207 occurrence points respectively. I found that the most suitable habitats for North American river otters in this study were areas of low elevation, with exposed land as the dominant land cover type, near water or wetlands, and that river otters and humans are able to coexist quite well, at least in some urban contexts. Finally, I performed Pearson’s Chi-squared tests on 594 observations from 178 behavioural samples to evaluate three hypotheses focusing on behavioural differences among river otters associated with the use of an anthropogenic habitat feature (i.e docks), and land. The results indicated that river otters used docks more than would be expected by chance and, disproportionately for individual and social activities and they used docks more than expected during the overnight period. Overall, this suggests docks may act as an anthropogenic habitat attractant for river otters. This study helps clarify relationships between river otter behaviour and space use in landscapes they share with humans and in environments where anthropogenic structures are present, which can inform the development of targeted conservation initiatives and enhance human-wildlife coexistence
Investigation of Turbulent Flow in Transitions by Large Eddy Simulation
Get PDFIn hydraulic engineering, a transition facilitates a change in the direction, slope or cross-section of an open channel or pipeline. This thesis focuses on expanding flows in open-channel expansions and hydraulic jumps. This thesis uses wall-resolved Large Eddy Simulation (LES) to study the two-phase turbulent flows in several three-dimensional (3-D) geometries, including non-prismatic open channels and sloping pipes. The LES predictions compare well with corresponding experimental results and benchmark solutions.
First, for a turbulent bistable flow approaching a straight-wall channel expansion, either of two stable flow states can occur, depending on the flow history. The thesis aims to reveal the ensemble-average flow characteristics and explore effective ways to control bistability. Turbulent eddies initiated by shear instability dominate those associated with sidewall-friction force, which is responsible for the occurrence of bistability. Fitting a simple hump at a flat-bottom expansion is an effective way to suppress bistability.
Next, hydraulic jumps in sloping pipes are investigated to achieve an improved understanding of jump behaviours driven by different discharges and slopes. Flow behaviours such as free-surface fluctuations and jump-toe oscillations resemble the classical hydraulic jump on horizontal floors. Depending on the discharge and slope, the resulting jump can be a complete or an incomplete jump. The latter causes flow choking downstream, which has severe consequences on drainage conditions in sewer pipes. The Okubo-Weiss parameter is a new way to subtly delineate the region of hydraulic jump.
Last, to study turbulent flows in a non-prismatic warped expansion using LES, the thesis discusses rigorous strategies for model setup, parameter selection and parametric value assignment. Mapping mean-velocity distributions from experimental data, combined with the spectral synthesiser approach for velocity fluctuations, gives a satisfactory inlet condition; alternatively, a 1/7th power-law for the mean-velocity, combined with the vortex method for the fluctuations, is acceptable.
Compared to a prismatic channel, a non-prismatic channel exhibits more complicated eddy motions and turbulence interactions. This thesis contributes to a systematic assessment of computational strategies, result visualisation, and analysis, all relevant to practical applications
Drawing the Curtain: Feminism and Female Artists of the 1970s Polish People's Republic
Get PDFThis thesis analyzes 1970s photographs and photomontages created by Ewa Partum and Natalia LL (Lach-Lachowicz) that respond to concurrent political and cultural conditions in the Polish People’s Republic (PPR). Through photographic representations of the naked female body, Ewa Partum and Natalia LL activate a Polish feminist praxis that is adjacent to, but distinct from, Western feminism. The body becomes a tool that subverts static gender identities and provokes an embodied subjectivity. This thesis argues that Poland’s historical specificity informs how Partum and Natalia LL use their body, which in turn reflects Polish feminism. This position rejects contemporary claims by the Polish Roman Catholic Church and right-wing groups in Poland, while anchoring Partum and Natalia LL within the lineage of Polish feminists.
This thesis begins with an historical overview of the 1970s in socialist Poland to better understand the social and political context during which Partum and Natalia LL developed their artistic careers. With a specific focus on the artists’ early careers and select photographs from Partum’s Self-Identification (1980) series and Natalia LL’s Artificial Photography (1976) series, this thesis then considers two dimensions in the analysis of these works. The first dimension refers to feminist scholar Elizabeth Grosz’s theories of the body to understand how Partum and Natalia LL use their bodies from a philosophical position. The second dimension uses Polish feminist theorist Sławomira Walczewska’s discussion of 18th-20th century Polish feminist history and Agnieszka Graff’s reflections on the gendered implications of post-1989 Poland. Together, this approach creates a composite perspective that links the artists’ works with the body, feminism, conceptual art, and Polish modern history
Overall Performance Evaluation of Building Integrated Photovoltaics (BIPV) as Active Building Envelope Systems
Get PDFThe application of photovoltaics in buildings for solar energy power generation in urban areas is developing quickly. As a result, building-integrated photovoltaic (BIPV) systems have emerged as multi-functional systems that not only produce electricity on-site but also replace conventional building envelope components and integrate with mechanical systems. Although characterization of the electrical performance in the photovoltaics used in these systems is provided by manufacturers, without clear evaluations of the building envelope and mechanical performance parameters of these systems for comparison to traditional building system components, it is challenging for architects, engineers, and building owners to make informed decisions regarding their implementation in building design.
This thesis aims to evaluate the characteristics of building integrated photovoltaic systems as components of the building envelope and mechanical systems. Different types of building integrated photovoltaic systems in different implementation scenarios are studied, including opaque building integrated photovoltaic/thermal (BIPV/T) systems coupled with a heat recovery ventilator (HRV) in a curtain wall construction (where the photovoltaic panels form the external cladding of the building envelope and the heat captured by the airflow behind the cladding is used in preheating the HRV), BIPV cladding integrated with wood-frame construction, and semitransparent photovoltaic (STPV) glazing units (double pane insulated glazing units forming the exterior glazing of the building envelope). The key parameters evaluated are thermal efficiency, energy generation, sensible recovery efficiency (SRE) and supply air outlet temperature increase ΔT_(SA,HRV) when coupled with HRV, the moisture content in wood frame construction for opaque BIPV building envelopes, and solar heat gain coefficient (SHGC) for STPV glazing units. Field measurements were performed for these implementation scenarios to characterize their performance and were compared to simulations. Although the simplified approaches used in this thesis to model their performance through simulation have limitations in their ability to reflect field operating conditions, the field measurements and hygrothermal modeling results show that BIPV systems in these scenarios can perform better than conventional building components
Computer Vision-Based Guidance Tool for Correct Radiographic Hand Positioning
Get PDFHand X-Rays are used for tasks such as detecting fractures and investigating joint pain. The choice of the X-Ray view plays a crucial role in a medical expert's ability to make an accurate diagnosis. In particular, this choice is essential for the hand, where small and overlapping bones of the carpals can make it challenging to view structures even with correct positioning. In this study, we develop a prototype that uses deep learning models, iterative methods and a depth sensor to estimate hand and X-Ray machine parameters. We then use these parameters to generate feedback that ensures proper positioning according to radiographic positioning standards.
The method of this study consists of five steps: detector plane parameter estimation, 2D hand keypoint prediction, landmark depth estimation, positioning parameter extraction, and protocol constraint verification. Detector plane parameter estimation is achieved by fitting a plane to randomly queried depth points using RANSAC. Google's MediaPipe HandPose model is used for 2D hand keypoint estimation, and depth coordinates are determined using the OAK-D Pro's depth sensor. Finally, hand positioning parameters are extracted and evaluated with respect to the selected viewing protocol. We focus on three commonly used hand positioning protocols: posterior-anterior, oblique, and lateral view. The prototype also has a user interface and a feedback system designed for practical use in the X-Ray room.
Two evaluations are undertaken to validate our prototype. First, with the help of a radiology technician, we rate the quality of the suggested positioning by the device. Second, using a bespoke left-hand X-ray phantom and an X-Ray machine, we generate images with and without the prototype guidance for a double-blind study rated by a radiologist
Choreographic Phenomena: Negotiations Between Body, Material, and Site as Invisible Agencies
Get PDFThis hybrid thesis situated between choreography and design investigates the relational dialogue between the body and the environment to reveal spatio-temporal choreographic parameters that operate in the way the body encounters the built environment. Part of the “corporeal turn” (Sheets Johnstone 2009) this research aims to consider the body as an agent and site of experience, to better understand how it is affected, conditioned, and implicated in its relations and interactions with the built environment? Through an embodied analysis the work proposes the active posture of negotiation, as a possible way of interacting with our environments that accounts for the potentials, possibilities and expressions of an individual body’s point of view. Choreography here is framed as an organization of movement in action (Forsythe, 2014) that occurs in the body, through the material medium across elements of time and space. Thus a choreographic conversation between body and environment, that goes beyond purposive and goal-oriented approaches (Herbert, 1999) embedded within material objects, to better understand the way we inhabit our bodies and how we are shaped by our environment. Aiming to subvert traditional choreographic practice while affirming the potential of practitioner situated knowledge, the research utilizes embodied practices through a hybrid assemblage of text-images-notes-analysis, that reveal the hidden parameters through four multi-sited bodily studies created between 2017-2019. The research centers the body as the site of analysis to explore four parameters of bodily negotiation as: micro-macro scale, negative space, repetition and harmony, which operate on the body through the environment’s characteristic constraints, and thus shape bodily experience and expression. If we were more aware of our bodily relationship to the built environment, and if we brought embodied awareness further to the forefront of our phenomenological experience, would this shift our embodied consciousness and the way we inhabit our bodies through the world
"I Am the Wild Machinist ... Reconstructing the Present": The Flâneur-Cruiser in Samuel R. Delany’s Dhalgren
Get PDFThis thesis aims to better understand queer theories of time and space in relation to the experiences of those who loiter, who lounge, who fuck against the rush of straight time and space. The project does so via an investigation of the related figures of the flâneur and the cruiser, considering what latent potentials they hold for queer futurity. This research examines these themes in the science fiction novel Dhalgren by Samuel R. Delany, as well as Delany’s autobiographical writings. I posit that, through a total rejection of straight and capitalist time, Dhalgren’s fictional city of Bellona and its residents effectively put into practice a queer world that theorists such as José Esteban Muñoz conceive as impossible in our own here and now. Moreover, by way of this imaginative turn, Delany crystalizes a clear image of the world that cruisers and flâneurs alike are striving towards – a world where all are free to wander idly and to desire publicly without legal or moral consequence
Calibration and Evaluation of Building Energy Models to Assess and Mitigate Canadian Building Overheating Risks in Current and Future Climates
Get PDFClimate change continues to impact weather conditions globally, requiring cities to adapt to new environments. In Canada, indoor summer overheating in buildings is problematic due to their primary design for cold winters, making them susceptible to extreme heatwave events. This research focuses on calibrating building models and employing model calibration methodologies to evaluate and address overheating risks in various building types across Canada using current and future weather data. The study's objectives are to accurately assess summertime overheating risks in selected buildings in Montreal, Quebec, and evaluate effective mitigation strategies. Bayesian calibration and multi-objective genetic algorithms are used as calibration methods, with the latter showing superiority in producing highly accurate calibrated models based on five performance criteria. By incorporating field measurements and novel methodologies, the research ensures precise assessment and mitigation of summertime overheating risks. After calibrating several buildings, including schools, a hospital, and a residential building, which demonstrates the reliability and repeatability of the calibration process, the assessment of overheating is conducted on calibrated models to determine the number of overheating hours during the summer. In conclusion, this thesis demonstrates the repeatability of the calibration methods on a variety of existing Canadian buildings and the effective use of passive cooling techniques, such as external shading, night cooling, and high albedo surfaces, that are implemented in the building models, to mitigate overheating based on current and future weather data