Saudi Cultural Missions Theses & Dissertations
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Item Restricted Development of a Patient-Specific Streamlined Workflow for a Predictive Tool for Coronary Artery Bypass Graft Outcomes(University College London, 2024-12-01) Alsaleh, Abdullah; Torii, RyoCoronary artery disease is one of the leading causes of mortality worldwide and is treatable by only a few procedures, such as coronary artery bypass grafting (CABG). However, predicting the long-term success of CABG, particularly in terms of graft patency and disease progression, remains a challenge. This thesis aims to develop a patient-specific streamlined workflow for a predictive tool that integrates peri-operative Coronary Computed Tomography Angiography (CCTA) with Computational Fluid Dynamics (CFD) simulations to predict post-CABG outcomes. The patient-specific streamlined workflow for a predictive tool for CABG outcomes is designed to simulate hemodynamic conditions within grafts, providing personalized predictions to guide surgical decisions and improve patient outcomes. The methodology includes creating anatomically accurate 3D models, simulating hemodynamic conditions, and validating the results against clinical data. While the patient-specific streamlined workflow for the predictive tool shows promise, significant challenges remain in terms of boundary condition setup, data integration, and discrepancies between simulation results and hospital data. The overestimation of flow rates and high wall shear stress observed in the simulations indicate the need for refinements in model assumptions, including incorporating non-Newtonian blood properties, vessel wall compliance, and pulsatile blood flow. Despite these limitations, this study demonstrates the potential of a patient-specific streamlined workflow for a predictive tool for CABG outcomes and offers a path forward for personalized cardiovascular treatment. Future work will focus on refining the model to enhance its accuracy, and clinical applicability, and commercializing the method.30 0Item Restricted Computational Design Optimisation of the Thermal Performance of an Opaque Ventilated Façade in Hot Desert Climate Based on Biomimetic Inspiration(Cardiff University, 2024-07) Alyahya, Ahmed Abdullatif; Lannon, Simon; Jabi, WassimThis research investigated opaque ventilated façades, which have been proven to reduce heat transfer through the building envelope. Although their effectiveness in different climates has been evaluated by numerous studies, there is a notable lack of research on their application in a hot desert climate, and there are currently no computationally optimised designs for such façades in the current state of the art or studies on the biomimetic opaque ventilated façades. As a result, this thesis presents a comprehensive investigation into the optimisation of opaque ventilated façades tailored for a hot desert climate, utilising biomimetic principles. The research begins with an extensive review of existing literature and precedent studies to establish a theoretical foundation encompassing biomimicry, opaque ventilated façade design, and computational design optimisation. Building upon this theoretical groundwork, a baseline opaque ventilated façade was developed specifically for hot desert climates, with a prototype constructed to explore influential design parameters affecting its performance. Through systematic exploration of design parameters, it was identified that increasing airflow velocity within the cavity and maximising the shaded area of the façade are critical in reducing inner skin surface temperature, presenting significant technical challenges. The study then investigated biological solutions, drawing inspiration from rodent burrows and barrel cactus characteristics, to address these challenges. During concept and sensitivity analysis, rodent burrows and barrel cactus features were examined for their potential to increase airflow velocity, maximise façade shade, and reduce inner skin surface temperature. Twenty-four bio-inspired solutions are individually tested in the concept and sensitivity analysis phase, with computational fluid dynamics (CFD) simulations employed to evaluate their thermal performance. Among these solutions, two funnel-shaped louvres and the wide mound solutions exhibited superior performance in reducing inner skin surface temperature. The identified wide mound solution and the two funnel-shaped louvres solution undergo further refinement through parametric optimisation, utilising an advanced optimisation solver to generate a range of design options to determine the most effective configurations for reducing inner skin surface temperature and decreasing total surface area. Two options for wide mound and funnel-shaped designs were considered for reducing either inner skin surface temperature or minimising total surface area. Simulations show the larger wide mound solution as the best choice overall. Finally, this optimal design was applied to a three-floor commercial building in Riyadh, Saudi Arabia. The simulation results of this application demonstrated that this design can be successfully implemented in lowrise buildings with multiple floors in hot desert climates, lowering the façade surface temperature and enhancing thermal performance. In addition, the design application stage demonstrated that this optimal solution could be constructed similarly to other conventional opaque ventilated façades and could be customised to suit the architectural façade design of the majority of buildings. This research underscores the potential of biomimetic approaches to enhance the thermal performance of opaque ventilated façades in hot desert regions, offering a pathway towards sustainable building design solutions.15 0Item Restricted Comprehensive assessment of myocardial ischaemia: from vessel to patient.(Saudi Digital Library, 2023-10-12) Albaraikan, Abdulaziz Mohammed; Gunn, JulianChronic coronary syndrome (CCS) is accompanied by angina and limitation to the patient’s life. The significance of coronary blood flow reduction is currently best assessed by fractional flow reserve (FFR) as a guide to intervention. The beneficial effect of percutaneous coronary intervention (PCI) in these patients has been challenged, and therefore fresh evaluation of the changes in response to PCI is needed. Using real-world data from 40 patients, detailed examination of coronary anatomy and physiology, using FFR and computational fluid dynamics (CFD) to assess absolute coronary flow, was conducted. Patients not undergoing PCI due to FFR negative lesions comprised the ‘control’ group. A novel method to assess the myocardial ischemic burden and address the global flow reduction named ‘cumulative FFR’ (FFRCUM) was developed. Fitness trackers monitored everyday physical activity, and six-minute walk tests were performed, before and three months after the procedure. Questionnaires were used to evaluate the change as reported by the patients. I found a clear and significant physiological improvement following PCI in FFR, hyperaemic stenosis resistance (HSR), microvascular resistance (MVR), absolute flow (which increased 80%) and FFRcum (which increased from 0.72 to 0.83). The change in FFRcum was a predictor of the change in quality of life at follow up. Improvement in spontaneous and observed physical activity, which was highly variable between patients, was minimal, with similar findings in PCI and ‘control' patients. This was also observed with questionnaires in all domains except angina frequency. Taken together, this work shows that physiological improvement (FFR and FFRcum), and absolute flow restoration, are achieved with FFR-guided PCI. However, that does not necessarily result in measured improvement in everyday physical activity, or self-reported general health status, but it does result in improved angina status, at three months. Overall, these findings indicate that physiological improvements in myocardial perfusion produced by PCI tend not to lead to a major change in objective measures of activity or wellbeing in everyday life, but are worth pursuing in terms of angina, specifically14 0