Modeling the dynamics of complex multibody systems, such as those representing the motion of animals, can be accomplished through well-established geometric methods. In these formulations, motions take values in certain types of smooth manifolds which are coordinate-free and intrinsic. However, the dimension of the full configuration manifold can be large. The first study in this dissertation aims to build low-dimensional models models from motion capture data. This study also expands on the so-called learning problem from statistical learning theory over Euclidean spaces to estimating functions over manifolds. Experimental results are presented for estimating reptilian motion using motion capture data. The second study in this dissertation utilizes reproducing kernel Hilbert space (RKHS) formulations and Koopman theory, to achieve some of the advantages of learning theory for IID discrete systems to estimates generated over dynamical systems. Specifically, rates of convergence are determined for estimates generated via extended dynamic mode decomposition (EDMD) by relating them to estimates generated by distribution-free learning theory. Some analytical examples illustrate the qualitative behavior of the estimates. Additionally, a examination of the numerical stability of the estimates is also provided in this study. The approximation methods are then implemented to estimate forward kinematics using motion capture data of a human running along a treadmill. The final study of this dissertation contains an examination of the continuous time regression problem over subsets and manifolds. Rates of convergence are determined using a new notion of Persistency of Excitation over flows of manifolds. For practical considerations, two approximation methods of the exact solution to the continuous regression problem are introduced. Characteristics of these approximation methods are analyzed using numerical simulations. Implementations of the approximation schemes are also performed on experimentally collected motion capture data. / Doctor of Philosophy / Modeling the dynamics of complex multibody systems, such as those representing the motion of animals, can be accomplished through well-established geometric methods. However, many real-world systems, including those representing animal motion, are difficult to model from first principles. Machine learning, on the other hand, has proven to be extremely powerful in its ability to leverage "big data" to generate estimates from typically independent and identically distributed (IID) data. This dissertation expands on the so-called learning problem from statistical learning theory over Euclidean spaces to those over manifolds. This dissertation consists of three studies, the first of which aims to build low-dimensional models models from motion capture data. Using the distribution-free learning theory, estimates discussed in this dissertation minimize a proxy of the expected error, which cannot be calculated in closed form. This dissertation also includes a study into approximations of the so-called Koopman operator. This study determined that the rate of convergence of the estimate to the true operator depends on the reduced dimensionality of the embedded submanifold in the high-dimensional ambient input space. While most of the current work on machine learning focuses on cases where the samples used for learning or regression are generated from an IID, stochastic, discrete measurement process, this dissertation also contains a study of the regression problem in continuous time over subsets and manifolds. Additionally, two approximation methods of the exact solution to the continuous regression problem are introduced. Each of the aforementioned studies also includes several analytical results to illustrate the qualitative behavior of the approximations and, in each study, implementations of the estimation schemes are performed on experimentally collected motion capture data.

Abstract Background: Osteoarthritis (OA) is a prevalent joint disease causing significant disability, particularly in the knee often treated end-stage with joint replacement surgery. While partial knee arthroplasty (PKA) is noted for quicker recovery and better functionality compared to total knee arthroplasty (TKA), its underutilization highlights a gap in surgical decision-making, driven by a lack of objective data on pre-operative functional differences. Methods: This prospective observational study, conducted from November 2023 to April 2024 at St. Joseph’s Healthcare Hamilton, included 34 end-stage OA patients scheduled for knee arthroplasty. Participants underwent pre-operative functional assessments using markerless motion capture technology to analyze gait and mobility during walking and sit-to-stand tests. Results: The study found no significant differences in basic gait and sit-to-stand metrics between the PKA and TKA groups at a preferred pace. However, at a faster pace, PKA patients demonstrated greater adaptability, showing significant increases in peak stance knee flexion, knee flexion excursions, and stride length, compared to TKA patients whose gait patterns remained consistent across speeds. Conclusion: PKA patients exhibit greater functional adaptability in their pre-operative state, suggesting potential underestimation of their capabilities in current surgical evaluations. Incorporating varied-pace walking tests in pre-operative assessments may provide deeper insights into functional capabilities, influencing more tailored surgical decisions and potentially increasing the application of PKA in suitable candidates. / Thesis / Master of Applied Science (MASc)

Les microorganismes, par leurs fascinantes capacités d’adaptation liées à l’extraordinaire diversité de leurs capacités métaboliques, jouent un rôle fondamental dans les tous les processus biologiques. Ils interviennent notamment au niveau des changements globaux, comme le réchauffement climatique, en partie occasionné par les émissions croissantes de méthane dans l’atmosphère, mais également par les pollutions résultant de la dispersion de molécules comme les Hydrocarbures Aromatiques Polycycliques. Ainsi, les communautés microbiennes vont participer à réduire ou à augmenter les effets délétères de l’anthropisation des écosystèmes. La régulation des changements globaux passe donc par une meilleure connaissance de ces communautés qui doivent être explorées dans leur globalité au sein des environnements. Néanmoins en raison de leur forte complexité, une telle exploration n’est possible qu’en utilisant des outils d’analyse haut-débit. Cependant, l’emploi d’outils moléculaires à haut-débit comme les biopuces à ADN passe par la détermination de sondes combinant à la fois une forte sensibilité, une très bonne spécificité et un caractère exploratoire. Pour concevoir de telles sondes un nouveau logiciel KASpOD a donc été développé. De même, en utilisant des sondes présentant les mêmes caractéristiques, le développement d’une nouvelle approche innovante en écologie microbienne de capture de gènes en solution été entrepris. Cette nouvelle méthode d’enrichissement de gènes d’intérêt couplée à du séquençage haut-débit a été appliquée pour l’exploration des communautés méthanogènes du lac Pavin. Les résultats obtenus montrent la pertinence de l’approche qui assure une meilleure évaluation de diversité de l’écosystème avec notamment l’identification de populations appartenant à la biosphère rare. L’autre ajout majeur de cette approche est qu’elle autorise l’identification de grandes régions d’ADN génomique exploitable pour caractériser de nouveaux gènes ou de nouveaux processus adaptatifs. / Microorganisms play a crucial role in all biological processes related to their huge metabolic potentialities. They are involved in global changes such as global warming partially caused by the growing methane emissions in the atmosphere, but also by the release of pollutants such as Polycyclic Aromatic Hydrocarbons. Thus, microbial communities will contribute to reduce or increase the negative effects of human impacts on ecosystems. The regulation of global changes needs a better knowledge of the microbial communities involved in complex environments functioning. Nevertheless, a complete exploration of such environments requires the use of high-throughput tools, due to the extraordinary diversity of microorganisms within the ecosystems. The use of DNA microarrays requires a probe design step allowing the selection of highly sensitive, specific and explorative oligonucleotides. For this purpose, we have developed KASpOD, a new software, allowing the generation of efficient probes dedicated to environmental applications. Using high quality probe sets, an innovative in solution-based gene capture method combined with Next Generation Sequencing, was developed and applied for the exploration of the methanogen communities in lake Pavin, Results showed the relevance of this approach that allows a better evaluation of the methanogen diversity with an efficient detection of populations belonging to the rare biosphere. The other main advantage of this approach is the identification of large regions of genomic DNA, useful for the characterization of new genes or adaptive processes.

Many reports, scientific papers, patents, and scientific news investigate the feasibility and affordability of direct carbon dioxide capture from the atmospheric air (DAC). Since carbon dioxide (CO2) is extremely diluted in the atmosphere, large volumes of air have to be handled to capture comparable amounts of CO2. Therefore, both the energy consumption and the plant size are expected to be 'prohibitive'. On the other hand, some analyses have shown that DAC is feasible and can become affordable with essential research and development. DAC has been regarded as an optional bridging or a transitional technology for mitigating CO2 emissions in the medium-term. Priorities include investing in renewable and low-carbon technologies, efficiency and integration of energy systems, and realisation of additional environmental benefits. A heavy reliance on negative emission technologies (NETs), and consequently DAC, may be extremely risky as NETs interact with a number of societal challenges, i.e. food, land, water and energy security. Although, "... capturing carbon from thin air may turn out to be our last line of defence, if climate change is as bad as the climate scientists say, and if humanity fails to take the cheaper and more sensible option that may still be available today" MacKay (2009). Certainly, more research is necessary to bring down both cost and energy requirements for DAC. This work firstly predicts the adsorption equilibrium behaviour of a novel temperature swing adsorption process, which captures carbon dioxide directly from the air, concentrates, and purifies it at levels compatible to geological storage. The process consists of an adsorption air contactor, a compression and purification train, which is a series of packed beds reduced in size and connected in-line for the compression and purification purposes, and a final storage bed. The in-line beds undergo subsequent adsorption and desorption states. The final desorbed stream is stored in a storage bed. This cyclic process is repeated for a number of times imposed by the required purity and pressure in the final bed. The process is been thermodynamically verified and optimised. Since, the overall performance of this process does not only depend on the design of the process cycle and operating conditions but also on the chosen adsorbent material, further optimisation of the adsorptive and physical properties of the solid adsorbent is investigated. Thus, the optimal parameters of the potentially used porous materials is identified. Continuing the research on different adsorbent materials, an experimental investigation on the equilibrium properties of two competitive adsorbents is also performed. Besides the thermodynamic analysis, a dynamic model is presented for the investigation of the mass and heat transfer and its influence on the adsorption rate and consequently on the overall process performance. Since the initial stream is very dilute, it is expected that the adsorption rate will be low compared to other temperature swing processes and the capture rate will be affected by the heat transfer. Finally, the design and development of an experimental laboratory-scale apparatus is presented and analysed. Future design improvements are also discussed.

Le but de l’étude est de mettre en question la capture de régulation par les intérêts concentrés de la finance dans les débats sur les mesures à prendre après la crise du crédit partie des États-Unis en 2008. Les décideurs publics de ce pays et de l’Union européenne ont entrepris des efforts de réforme ambitieux pour mieux protéger les consommateurs de services financiers. Les débats au Congrès des États-Unis et au Parlement européen se sont achevés sur des décisions importantes concernant la réglementation du crédit. Fortement politisés, ils avaient suscité un lobbying intense des groupes d’intérêt de la finance et de la société civile, où normalement ces derniers auraient été tenus pour beaucoup plus faibles que leurs adversaires. Paradoxalement, une coalition de la société civile aux moyens modestes a réussi à convaincre les décideurs de la nécessité du changement et à contrecarrer les efforts du lobby financier pour l’empêcher. Qu’est-ce qui explique que des acteurs faibles et périphériques l’ont emporté sur des acteurs riches et puissants ? / The goal of this study is to examine and challenge questions of regulatory capture by concentrated industry interests in the reform debates in response to the credit crisis which originated in the US in 2008. Policymakers in the EU and the US set ambitious reform efforts in motion to better protect consumers of financial services. Decisions to reform credit regulations marked the end of highly politicized reform debates in the US Congress as well as in the European Parliament, involving lobbying from business associations and civil society groups, in which proponents of reforms would normally have been considered to be much weaker than their opponents. Paradoxically, a poorly-resourced civil society coalition successfully lobbied decision-makers and countered industry attempts to prevent regulatory change. What, then, explains that rather weak and peripheral actors prevailed over more resourceful and dominant actors?

Accurate risk assessment tools and methods are necessary to understand the relationship between occupational exposure to physical risk factors and musculoskeletal disorders. Ergonomists typically consider direct measurement methods to be the most objective and accurate of the available tools. However, direct measurement methods are often not used due to cost, practicality, and worker/workplace disruption. Inertial measurement units (IMUs), a relatively new direct measurement technology used to assess worker kinematics, are attractive to ergonomists due to their small size, low cost, and ability to reliably capture information across full working shifts. IMUs are often touted as a field-capable alternative to optical motion capture systems (OMCs). The error magnitudes of IMUs, however, can vary significantly (>15°) both within and across studies. The overall goals of this thesis were to (i) provide knowledge about the capabilities and limitations of IMUs in order to explain the inconsistencies observed in previous studies that assessed IMU accuracy, and (ii) provide guidance for the ergonomics community to leverage this technology. All three studies in this dissertation systematically evaluated IMUs using a repetitive material transfer task performed by thirteen participants with varying movement speeds (15, 30, 45 cycles/minute) and magnetic disturbance (absent, present). An OMC system was used as the reference device. This first study systematically evaluated the effects of motion speed and magnetic disturbance on the spatial orientation accuracy of an inertial measurement unit (IMU) worn on the hand. Root-mean-square differences (RMSD) exceeded 20° when inclination measurements (pitch and roll) were calculated using the IMU’s accelerometer. A linear Kalman filter and a proprietary, embedded Kalman filter reduced inclination RMSD to < 3° across all movement speeds. The RMSD in the heading direction (i.e., about gravity) increased (from < 5° to 17°) under magnetic disturbance. The linear Kalman filter and the embedded Kalman filter reduced heading RMSD to < 12° and < 7°, respectively. This study indicated that the use of IMUs and Kalman filters can improve inclinometer measurement accuracy. However, magnetic disturbances continue to limit the accuracy of three-dimensional IMU motion capture. The goal of the second study was to understand the capability of IMU inclinometers to improve estimates of angular displacements and velocities of the upper arm. RMSD and peak displacement error exceeded 11° and 28° at the fastest transfer rate (45 cycles/min) when upper arm elevation was calculated using the IMU accelerometer. The implementation of a Kalman filter reduced RMS and peak errors to < 1.5° and < 2.3°, respectively. Similarly, the RMS and peak error for accelerometer-derived velocities exceeded 81°/s and 221.3°/s, respectively, at the fastest transfer rate. The Kalman filter reduced RMS and peak errors to < 9.2°/s and < 25.1°/s, respectively. The third study was conducted to evaluate the relationship between magnetic field strength variation and magnetic heading deviation. In this study, the presence of the metal plate increased magnetic heading deviations from < 12° (90th-10th percentile) to approximately 30°. As expected, the magnetic field strength standard deviation increased from 1.0uT to 2.4uT. While this relationship may differ across other sources of magnetic disturbance, the results reinforce the notion that local magnetic field disturbances should be minimized when using IMUs for human motion capture. Overall, the findings from this thesis contribute to the ergonomics community’s understanding of the current capabilities and limitations of IMUs. These studies suggest that while the touted capabilities of the IMUs (full-body motion capture in workplace settings) may be unattainable based on current sensor technology, these sensors are still significantly more accurate than the accelerometer-based inclinometers commonly used by ergonomists to measure motions of the upper arms.

The environment is abundant with visual information. Each moment, this information competes for representation in the brain. From billboards and pop-up ads to smart phones and flat screens, in modern society our attention is constantly drawn from one salient object to the next. Learning how to focus on the objects that are most important for the current task is a major developmental hurdle. Fortunately, rewards help us to learn what is important by providing feedback signals to the brain. Sometimes, in adolescence for example, reward seeking can become the pre-potent response. This can ultimately lead to risky and impulsive behaviors that have devastating consequences. Until recently, little has been known about how rewards operate to influence the focus of attention. In this document, I first demonstrate the robustness of various behavioral paradigms designed to measure reward processing in vision. I found that even mundane rewards, such as images of money, are effective enough to prime the attentional system on the basis of value. Remarkably, this effect extended to images of Monopoly money. This observation suggests that whole classes of visual stimuli, such as food, pornography, commercial logos, corporate brands, or money, each with its own reward salience value, are likely vying for representation in the brain. This work has implications for the growing digital economy as it suggests that novel value systems, such as the digital currency Bitcoin, could eventually become as psychologically relevant as physical currency provided sufficient use and exposure. Likewise, this work has implications for gamification in the industrial setting. Next, I examined the sensitivity of the system to make optimal economic decisions. When faced with an economic choice normative theories of decision-making suggest that the economic actor will choose the response that affords the greatest expected utility. Contrary to this account, I developed a new behavioral paradigm (reward contingent capture) and reveal that the attentional homunculus is a fuzzy mathematician. Specifically, I found that low-level attentional processes conform to the same probability distortions observed in prospect theory. This finding supports a unified value learning mechanism across several domains of cognition and converges with evidence from monkey models. Then, I demonstrate the influence of rewards on high-order search parameters. I found that images of money can implicitly encourage observers to preferentially adopt one of two search strategies – one that values salience versus one that values goals. Together, my results expose two distinct ways in which the very same rewards can affect attentional behavior – by tuning the salience of specific features and by shaping global search mode settings. Lastly, I draw from my empirical results to present a unified model of the manifold role of rewards on visual attention. This model makes clear predictions for clinical applications of rewarded attention paradigms because it incorporates a dimension of complexity upon which learning processes can operate on attention. Thus, future work should acknowledge how individual traits such as developmental trajectory, impulsivity, and risk-seeking factors differentially interact with low- and high-level attentional processes. In sum, this document puts forward the notion that rewards serve a compelling role in visual awareness. The key point however is not that rewards can have an effect on attention but that due to the nature of visual processing, reward signals are likely always tuning attention. In this way we can consider reward salience an attentional currency. This means then that deciding where to attend is a matter of gains and losses.

Post-combustion carbon capture, wherein the CO2 produced as a result of coal combustion is trapped at the power plant exhaust, is seen as a bridging technology to reduce CO2 emissions and combat climate change. This capture process will however impose a parasitic load on the power plant and technologies need to be developed to minimize this energy penalty. This research focuses on a technology which uses solid sorbents fashioned into a hollow fiber form that allows water-moderated thermal cycling as a means of trapping CO2 from flue gas. While hollow fiber technology has intrinsic advantages over competing liquid amine and packed bed technologies, the materials used to fabricate hollow fibers and the fabrication process itself need to be optimized in order to result in competitive, robust hollow fiber sorbents. This dissertation focuses on the material selection process for each component of the hollow fiber platform and discusses ways to optimize the fiber and barrier layer formation. Different materials were evaluated to function as the solid sorbent, the matrix polymer and the barrier layer; and eventually their performance was measured against past work in this area.

Absorption-stripping with aqueous, concentrated piperazine (PZ) is a viable retrofit technology for post-combustion CO2 capture from coal-fired power plants. The rate of thermal degradation and oxidation of PZ was investigated over a range of temperature, CO2 loading, and PZ concentration. At 135 to 175 °C, degradation is first order in PZ with an activation energy of 183.5 kJ/mole. At 150 °C, the first order rate constant, k1, for thermal degradation of 8 m PZ with 0.3 mol CO2/mol alkalinity is 6.12 × 10-9 s-1. After 20 weeks of degradation at 165 °C, 74% and 63%, respectively, of the nitrogen and carbon lost in the form of PZ and CO2 was recovered in quantifiable degradation products. N-formylpiperazine, ammonium, and N-(2-aminoethyl) piperazine account for 57% and 45% of nitrogen and carbon lost, respectively. Thermal degradation of PZ likely proceeds through SN2 substitution reactions. In the suspected first step of the mechanism, 1-[2-[(2-aminoethyl) amino]ethyl] PZ is formed from a ring opening SN2 reaction of PZ with H+PZ. Formate was found to be generated during thermal degradation from CO2 or CO2-containing molecules. An analysis of k1 values was applied to a variety of amines screened for thermal stability in order to predict a maximum recommended stripper temperature. Morpholine, piperidine, PZ, and PZ derivatives were found to be the most stable with an allowable stripper temperature above 160 °C. Long-chain alkyl amines or alkanolamines such as N-(2-hydroxyethyl)ethylenediamine and diethanolamine were found to be the most unstable with an allowable stripper temperature below 120 °C. Iron (Fe2+) and stainless steel metals (Fe2+, Ni2+, and Cr3+) were found to be only weak catalysts for oxidation of PZ, while oxidation was rapidly catalyzed by copper (Cu2+). In a system with Fe2+ or SSM, 5 kPa O2 in the inlet flue gas, a 55 °C absorber, and one-third residence time with O2, the maximum loss rate of PZ is expected to 0.23 mol PZ/kg solvent in one year of operation. Under the same conditions but with Cu2+ present, the loss rate of PZ is predicted to be 1.23 mole PZ/kg solvent in one year of operation. Inhibitor A was found to be effective at decreasing PZ loss catalyzed by Cu2+. Ethylenediamine, carboxylate ions, and amides were the only identified oxidation products. Total organic carbon analysis and overall mass balances indicate a large concentration of unidentified oxidation products. / text

This thesis presents a study on how to create a production pipeline using a markerless motion capture system for the creation of animations in computer games. The questions the authors desire to answer are: Is it possible to create a pipeline that uses markerless motion capture for the creation of animations in computer games? And also: Can a markerless motion capture system fit in an animation pipeline for games? This thesis is based on previous work by Kakee Lau (Lau, 2012), a former student of Gotland University College. He describes a pipeline for working with passive optical motion capture for games. To fit the markerless motion capture system, there must be some changes to Lau’s already established pipeline. The method used in this thesis is based on a pipeline described in Lau’s thesis (Lau, 2012). The authors have made some alterations to this pipeline for it to be more suitable for markerless motion capture. The pipeline that the authors propose covers the setup of two Kinect cameras, the calibration, the recording, the cleaning and the preparation for MotionBuilder. Due to some factors that were not taken into consideration during testing, there cannot be any quantitative conclusion in this thesis to which system is the better one. Based on the findings of this study the authors can conclude that a markerless motion capture system is a viable method for game animation creation, yet not giving the same quality of results as a passive optical motion capture system.