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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Non-Academic Institutional Variables Related to Degree Completion of Non-Traditional Age Undergraduate Students

Walts, Rebecca Ann. 08 1900 (has links)
A study was conducted at The University of Texas at Arlington to obtain measurements of non-traditional age undergraduate students using the Mattering Scales for Adult Students in Higher Education (MHE). The MHE is designed to assess the perceptions of adult students on how much they matter to the institution they are attending. The study also sought to determine if "mattering" and other selected nonacademic variables associated with the university environment are perceived by nontraditional age students to effect their likelihood of completing their baccalaureate degree. Of the five subscales surveyed by the MHE, significant statistical differences were found to exist in the Administration, Interaction With Peers, Multiple Roles, and Faculty subscales denoting an interaction between gender and minority status. Significant statistical differences were also found by gender on the Advising subscale and by minority status on the Faculty subscale.
12

Algoritmy odhadu stavových veličin elektrických pohonů / Algorithms of Electrical Drives State Estimation

Herman, Ivo January 2012 (has links)
This thesis deals with state estimation methods for AC drives sensorless control and with possibilities of the estimation. Conditions for observability for a synchronous drive were derived, as well as conditions for the moment of inertia and the load torque observability for both drive types - synchronous and asynchronous. The possibilities of the estimation were confirmed by experimental results. The covariance matrices for all filters were found using an EM algorithm. Both drives were also identified. The algoritms used for state estimation are Extended Kalman Filter, Unscented Kalman Filter, Particle Filters and Moving Horizon Estimator.
13

Le rôle du stress oxydatif/nitrosatif dans la pathogénèse de l’encéphalopathie hépatique chronique

Yang, Xiaoling 07 1900 (has links)
L'encéphalopathie hépatique (EH) est un syndrome neuropsychiatrique dû à une dysfonction hépatique où l'ammoniaque est un facteur central. Il a déjà été rapporté que l’intoxication aiguë d'ammoniaque induise le stress oxydatif/nitrosatif. La présente étude cible à évaluer le rôle du stress oxydatif/nitrosatif dans 2 modèles de l’EH chronique : (1) l’anastomose portocave (PCA) et (2) la ligation de la voie biliaire (BDL). Ces 2 modèles sont caractérisés par une hyperammoniémie et une augmentation d’ammoniaque centrale, cependant l’œdème cérébral est trouvé seulement chez les rats BDL. Des marqueurs du stress oxydatif/nitrosatif ont été évaluées dans le plasma et cortex frontal. Un stress nitrosatif central a été observé chez les rats PCA; tandis qu’un stress oxydatif/nitrosatif systémique a été démontré seulement chez les rats BDL. Ces résultats suggèrent (1) que l’hyperammoniémie chronique n’induise pas le stress oxydatif/nitrosatif systémique et (2) qu’un synergisme existe entre l’ammoniaque et le stress oxydatif/nitrosatif, en association avec l’œdème cérébral. / Hepatic encephalopathy (HE) is a neuropsychiatric complication due to liver failure where ammonia is believed to be central in the pathogenesis. Acute ammonia intoxication has demonstrated to induce oxidative/nitrosative stress in both in vivo and in vitro models. The present study was aimed to assess the role of oxidative/nitrosative stress in 2 models of chronic liver failure/HE; 1. portacaval anastomosis (PCA) and 2. bile duct ligation (BDL). Both models are characterised with hyperammonemia and increased brain ammonia however cerebral edema is only found in BDL rats. Oxidative/nitrosative stress markers were evaluated in plasma and frontal cortex of both animal models. Central nitrosative stress was observed in PCA rats, but systemic oxidative/ntrosative stress was demonstrated only in BDL rats. The results of our study suggest i) chronic hyperammonemia does not induce oxidative stress and ii) a synergistic effect between ammonia and systemic oxidative/nitrosative stress is associated with cerebral edema.
14

Le rôle du stress oxydatif/nitrosatif dans la pathogénèse de l’encéphalopathie hépatique chronique

Yang, Xiaoling 07 1900 (has links)
L'encéphalopathie hépatique (EH) est un syndrome neuropsychiatrique dû à une dysfonction hépatique où l'ammoniaque est un facteur central. Il a déjà été rapporté que l’intoxication aiguë d'ammoniaque induise le stress oxydatif/nitrosatif. La présente étude cible à évaluer le rôle du stress oxydatif/nitrosatif dans 2 modèles de l’EH chronique : (1) l’anastomose portocave (PCA) et (2) la ligation de la voie biliaire (BDL). Ces 2 modèles sont caractérisés par une hyperammoniémie et une augmentation d’ammoniaque centrale, cependant l’œdème cérébral est trouvé seulement chez les rats BDL. Des marqueurs du stress oxydatif/nitrosatif ont été évaluées dans le plasma et cortex frontal. Un stress nitrosatif central a été observé chez les rats PCA; tandis qu’un stress oxydatif/nitrosatif systémique a été démontré seulement chez les rats BDL. Ces résultats suggèrent (1) que l’hyperammoniémie chronique n’induise pas le stress oxydatif/nitrosatif systémique et (2) qu’un synergisme existe entre l’ammoniaque et le stress oxydatif/nitrosatif, en association avec l’œdème cérébral. / Hepatic encephalopathy (HE) is a neuropsychiatric complication due to liver failure where ammonia is believed to be central in the pathogenesis. Acute ammonia intoxication has demonstrated to induce oxidative/nitrosative stress in both in vivo and in vitro models. The present study was aimed to assess the role of oxidative/nitrosative stress in 2 models of chronic liver failure/HE; 1. portacaval anastomosis (PCA) and 2. bile duct ligation (BDL). Both models are characterised with hyperammonemia and increased brain ammonia however cerebral edema is only found in BDL rats. Oxidative/nitrosative stress markers were evaluated in plasma and frontal cortex of both animal models. Central nitrosative stress was observed in PCA rats, but systemic oxidative/ntrosative stress was demonstrated only in BDL rats. The results of our study suggest i) chronic hyperammonemia does not induce oxidative stress and ii) a synergistic effect between ammonia and systemic oxidative/nitrosative stress is associated with cerebral edema.
15

Enabling Autonomous Operation of Micro Aerial Vehicles Through GPS to GPS-Denied Transitions

Jackson, James Scott 11 November 2019 (has links)
Micro aerial vehicles and other autonomous systems have the potential to truly transform life as we know it, however much of the potential of autonomous systems remains unrealized because reliable navigation is still an unsolved problem with significant challenges. This dissertation presents solutions to many aspects of autonomous navigation. First, it presents ROSflight, a software and hardware architure that allows for rapid prototyping and experimentation of autonomy algorithms on MAVs with lightweight, efficient flight control. Next, this dissertation presents improvments to the state-of-the-art in optimal control of quadrotors by utilizing the error-state formulation frequently utilized in state estimation. It is shown that performing optimal control directly over the error-state results in a vastly more computationally efficient system than competing methods while also dealing with the non-vector rotation components of the state in a principled way. In addition, real-time robust flight planning is considered with a method to navigate cluttered, potentially unknown scenarios with real-time obstacle avoidance. Robust state estimation is a critical component to reliable operation, and this dissertation focuses on improving the robustness of visual-inertial state estimation in a filtering framework by extending the state-of-the-art to include better modeling and sensor fusion. Further, this dissertation takes concepts from the visual-inertial estimation community and applies it to tightly-coupled GNSS, visual-inertial state estimation. This method is shown to demonstrate significantly more reliable state estimation than visual-inertial or GNSS-inertial state estimation alone in a hardware experiment through a GNSS-GNSS denied transition flying under a building and back out into open sky. Finally, this dissertation explores a novel method to combine measurements from multiple agents into a coherent map. Traditional approaches to this problem attempt to solve for the position of multiple agents at specific times in their trajectories. This dissertation instead attempts to solve this problem in a relative context, resulting in a much more robust approach that is able to handle much greater intial error than traditional approaches.
16

Digital Twin Development and Advanced Process Control for Continuous Pharmaceutical Manufacturing

Yan-Shu Huang (9175667) 25 July 2023 (has links)
<p>To apply Industry 4.0 technologies and accelerate the modernization of continuous pharmaceutical manufacturing, digital twin (DT) and advanced process control (APC) strategies are indispensable. The DT serves as a virtual representation that mirrors the behavior of the physical process system, enabling real-time monitoring and predictive capabilities. Consequently, this facilitates the feasibility of real-time release testing (RTRT) and enhances drug product development and manufacturing efficiency by reducing the need for extensive sampling and testing. Moreover, APC strategies are required to address variations in raw material properties and process uncertainties while ensuring that desired critical quality attributes (CQAs) of in-process materials and final products are maintained. When deviations from quality targets are detected, APC must provide optimal real-time corrective actions, offering better control performance than the traditional open loop-control method. The progress in DT and APC is beneficial in shifting from the paradigm of Quality-by-Test (QbT) to that of Quality-by-Design (QbD) and Quality-by-Control (QbC), which emphasize the importance of process knowledge and real-time information to ensure product quality.</p> <p><br></p> <p>This study focuses on four key elements and their applications in a continuous dry granulation tableting process, including feeding, blending, roll compaction, ribbon milling and tableting unit operations. Firstly, the necessity of a digital infrastructure for data collection and integration is emphasized. An ISA-95-based hierarchical automation framework is implemented for continuous pharmaceutical manufacturing, with each level serving specific purposes related to production, sensing, process control, manufacturing operations, and business planning. Secondly, investigation of process analytical technology (PAT) tools for real-time measurements is highlighted as a prerequisite for effective real-time process management. For instance, the measurement of mass flow rate, a critical process parameter (CPP) in continuous manufacturing, was previously limited to loss-in-weight (LIW) feeders. To overcome this limitation, a novel capacitance-based mass flow sensor, the ECVT sensor, has been integrated into the continuous direct compaction process to capture real-time powder flow rates downstream of the LIW feeders. Additionally, the use of near-infrared (NIR)-based sensor for real-time measurement of ribbon solid fraction in dry granulation processes is explored. Proper spectra selection and pre-processing techniques are employed to transform the spectra into useful real-time information. Thirdly, the development of quantitative models that establish a link between CPPs and CQAs is addressed, enabling effective product design and process control. Mechanistic models and hybrid models are employed to describe the continuous direct compaction (DC) and dry granulation (DG) processes. Finally, applying APC strategies becomes feasible with the aid of real-time measurements and model predictions. Real-time optimization techniques are used to combine measurements and model predictions to infer unmeasured states or mitigate the impact of measurement noise. In this work, the moving horizon estimation-based nonlinear model predictive control (MHE-NMPC) framework is utilized. It leverages the capabilities of MHE for parameter updates and state estimation to enable adaptive models using data from the past time window. Simultaneously, NMPC ensures satisfactory setpoint tracking and disturbance rejection by minimizing the error between the model predictions and setpoint in the future time window. The MHE-NMPC framework has been implemented in the tableting process and demonstrated satisfactory control performance even when plant model mismatch exists. In addition, the application of MHE enables the sensor fusion framework, where at-line measurements and online measurements can be integrated if the past time window length is sufficient. The sensor fusion framework proves to be beneficial in extending the at-line measurement application from just validation to real-time decision-making.</p>

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