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Zirconium phytate-based proton conductors for high-temperature fuel cell applications
No full textA Master of Science thesis in Chemical Engineering by Wessam Ahmed Mohamed Nimir entitled, “Zirconium phytate-based proton conductors for high-temperature fuel cell applications”, submitted in April 2023. Thesis advisor is Dr. Amani Al-Othman and thesis co-advisor is Dr. Muhammad Tawalbeh. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).Hydrogen fuel cells are regarded among clean power sources. They yield almost zero emissions with water being the only product. A functional membrane is the heart of the proton exchange membrane (PEM) fuel cell. This thesis describes the development of novel composite membranes for high-temperature PEM fuel cells (HT-PEMFCs) in particular. PEM fuel cells usually operate around 80°C. HT-PEMFCs operating above water’s boiling point are preferred due to their improved kinetics, heat recovery, superior water management, and enhanced tolerance to hydrogen fuel impurities. Nafion, the current conventional membrane in PEMFCs, cannot be used above 100°C, as its proton conductivity decreases dramatically. In this thesis, high-temperature and Nafion-free membranes are reported. These membranes are based on zirconium phytate (ZrPA), Silicotungstic acid (STA), and ionic liquids (ILs). Porous polytetrafluoroethylene (PTFE) polymer was used as a support. Various mass percentages of STA, and ILs were utilized and investigated. The membranes were characterized by electrochemical spectroscopy (EIS) and showed promising proton conductivity upon the addition of ILs. The unmodified ZrPA membrane had a proton conductivity of 6.65×10⁻⁴ S/cm. The inclusion of STA resulted in a ten-fold increase, raising it to 2.23×10⁻³ S/cm. This work investigated the effect of adding a plasticizer agent, polyethylene glycol (PEG). Further modification with PEG raised the proton conductivity to 3.81×10⁻² S/cm. The maximum proton conductivity (0.1 S/cm), similar to Nafion's conductivity, was obtained with 5.86 wt% of the IL ([HMIM][C₄N₃⁻]). A high-temperature test up to 150°C showed a decrease in conductivity by two orders of magnitude (10⁻ᵌ S/cm) but, promising conductivity. Water uptake analysis revealed that the modified ZrPA/STA/PEG/ILs membranes could hold more than 60 wt% of water. The modified membranes were further characterized by TGA, SEM, EDX, and XRD. The TGA results showed a decrease of 34 wt% at 600°C. FTIR and XRD analysis indicated a change in their crystalline and revealed substantial changes in particle diameter and morphology. The previous results showed that the synthesized membranes in this thesis are of great potential for HT-PEMFC applications.College of EngineeringDepartment of Chemical EngineeringMaster of Science in Chemical Engineering (MSChE
Decision Support Model for Selecting the Project Delivery Method for Sustainable Construction Projects
No full textA Doctor of Philosophy Dissertation in Engineering Systems Management by Salma Nasser Korany Megahed Ahmed entitled, “Decision Support Model for Selecting the Project Delivery Method for Sustainable Construction Projects”, submitted in March 2023. Dissertation advisor is Dr. Sameh El-Sayegh. Soft copy is available (Dissertation, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).As the demand for sustainable construction increases, the need to update project management practices in order to satisfy the objectives of sustainability becomes more significant. Project delivery method is a crucial decision in project management that impacts the success of construction projects. The extensive literature review conducted identified several gaps such as the lack of a comprehensive criteria list to select project delivery methods in sustainable construction projects and a lack of selection model that comprises that comprehensive criteria list. This research bridges the gaps in literature by developing a comprehensive decision support model that will provide decision-makers with a justified rationale for choosing the most appropriate delivery method for their sustainable construction projects. In order to achieve this, the underlying challenges of sustainable construction delivery were first categorized using factor analysed. These were then used to derive relevant sustainability -specific criteria which consisted of five groups: level of integration, green liability, green team, green criteria, and technology and innovation. Structural Equation Modelling was then used to predict the significance of these sustainability-specific selection criteria to the achievement of project success criteria such as efficiency, impact on client, team effectiveness and sustainability. Moreover, Analytical Hierarchy Process was used to calculate the relative weights of the traditional and sustainability-specific criteria as well as the effectiveness values of the three most common delivery methods in achieving the comprehensive criteria. The outputs of all these statistical procedures were then used to develop two decision support models that incorporate a comprehensive selection criteria list of both traditional and sustainability-specific criteria and the three most common delivery methods. Moreover, a customizable prototype software of the decision model was developed where the unfamiliar operations required in the adopted technique would be transparent to the end-users. A case-study that was administered in the end clearly indicates that DBB is outmatched by the unique requirements of sustainable construction. While, CMR and DB are both potentially competitive candidates that can enhance the success rate of sustainable construction projects.College of EngineeringDepartment of Industrial EngineeringPhD in Engineering - Engineering Systems Management (PhD-ESM
A mixed finite element method for nonlinear radiation–conduction equations in optically thick anisotropic media
No full textWe propose a new mixed finite element formulation for solving radiation–conduction heat transfer in optically thick anisotropic media. At this optical regime, the integro-differential equations for radiative transfer can be replaced by the simplified PN approximations using an asymptotic analysis. The conductivity is assumed to be nonlinear depending on the temperature along with anisotropic absorption and scattering depending on both the direction and location variables. The simplified PN approximations are enhanced by considering a diffusion tensor capable of describing anisotropic radiative heat transfer. In the present study, we investigate the performance of the unified and mixed formulations combining cubic P3, quadratic P2, and linear P1 finite elements to approximate the temperature in the simplified P3 model. To demonstrate the performance of the proposed methodology, three-dimensional examples of nonlinear radiation–conduction equations in optically thick anisotropic media are presented. The obtained numerical results demonstrate the accuracy and efficiency of the proposed mixed finite element formulation over the conventional unified finite element formulation to accurately solve the simplified P3 equations in anisotropic media.Royal Society, United KingdomAmerican University of Sharja
Maintenance and Sustainability: Decision Support Tools and Role of Maintenance Digital Transformation
No full textA Doctor of Philosophy Dissertation in Engineering Systems Management by Afef Saihi entitled, “Maintenance and Sustainability: Decision Support Tools and Role of Maintenance Digital Transformation”, submitted in March 2023. Dissertation advisor is Dr. Mohamed Ben-Daya and dissertation co-advisor is Dr. Rami As’ad. Soft copy is available (Dissertation, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).Maintenance is a crucial activity conducted throughout the use phase of the engineered object life cycle, which has tremendous impact on all three pillars of sustainability. While economic and technical impacts of maintenance activities are well-studied and vastly addressed in the literature, the associated impacts on environmental and social pillars are not sufficiently tackled. As such, maintenance-related decisions, in all its facets, have been mostly driven by these economic and technical measures. Full integration of sustainability considerations into maintenance practices requires close monitoring and assessment of maintenance impact on the triple-bottom-line through relevant key performance indicators (KPIs) and appropriate decision-support tools that take into account pertinent sustainability issues. To that end, there is a need for further research concerning the integration of all sustainability aspects into maintenance practices along various directions, including (1) developing adequate and relevant KPIs, (2) proposing models for accurate maintenance sustainability performance evaluation, (3) exploring the role of technology in enabling this integration, and (4) devising sound decision-making tools. Therefore, this research addresses the existing gaps and aims to develop effective tools for integrating sustainability aspects into maintenance decisions practices, and to explore the challenges that hinder this integration and the potential role of technology in overcoming them. First, a comprehensive and hierarchical framework of sustainable maintenance performance indicators is developed and validated by experts in the field. Using this framework as a guide, a fourth-order Partial Least Square-Structural Equation Modeling (PLS-SEM) based higher component model for measuring sustainable maintenance performance is proposed and validated in the Oil and Gas industry. Furthermore, given that digital transformation (DT) of maintenance can play a pivotal role in facilitating the integration of sustainability issues in maintenance decision-making, it is crucial to identify the key ingredients and the most influencing factors, beyond purely technological aspects, that drive the success of digitalization efforts. Then, a hybrid reactive Delphi approach is adopted to identify and validate the key factors driving the success of maintenance DT and aiding its implementation. Finally, a first-step is taken towards proposing planning models that integrate sustainability in the decision-making process.College of EngineeringDepartment of Industrial EngineeringPhD in Engineering - Engineering Systems Management (PhD-ESM
A Formal Assisted Approach for Modeling and Testing Security Attacks in IoT Edge Devices
No full textA Master of Science thesis in Computer Engineering by Alifiya Bhanpurawala entitled, “A Formal Assisted Approach for Modeling and Testing Security Attacks in IoT Edge Devices”, submitted in November 2023. Thesis advisor is Dr. Khaled El-Fakih. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).With the rapid growth in the number of IoT devices being added to the network, a major concern that arises is the security of these systems. As these devices are resource constrained, safety measures are difficult to implement on the edge. We propose a novel approach for the detection of IoT device attacks based on the use of formal modelling and mutation testing. Namely, we model the behaviour of small IoT devices such as motion sensors and RFID card reader as state machines with timeouts. We also model basic IoT attacks; namely, battery draining, sleep deprivation, data falsification, replay, and man in the middle attacks, as special mutants of these specifications. We also consider tests for detecting actual physical device manipulation. Mutation testing is then used to derive tests that distinguish these attacks from the original specifications. The behaviour of these mutants is tested in real environment by running the tests on the data collected while the edge device is still running. Our experiments show that derived number of attack mutants and tests is small and thus these tests can be executed many times with limited overhead on the physical device. Consequently, our approach is not deterred by related high costs of traditional mutation testing. Furthermore, we demonstrate that the tests generated by our method, encompassing the considered IoT attacks, do not adequately cover mutants derived through conventional mutation code-based operators. This highlights the necessity of employing our method. A framework that implements our approach is presented along with some other relevant case studies.College of EngineeringDepartment of Computer Science and EngineeringMaster of Science in Computer Engineering (MSCoE
Flexural Response of Reinforced Concrete One-Way Slabs Embedded with Pet Bottles
No full textA Master of Science thesis in Civil Engineering by Chahed Abdulsatir Alhomsi entitled, “Flexural Response of Reinforced Concrete One-Way Slabs Embedded with Pet Bottles”, submitted in May 2023. Thesis advisor is Dr. Sami Tabsh. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).The feasibility of a cost-effective and eco-friendly slab system to be used in developing regions is investigated. The system consists of a thin reinforced concrete slab that is embedded with polyethylene terephthalate (PET) bottles as void creators. The voids will reduce the amount of concrete that could have been used in an equivalent solid slab without compromising the capacity. The main objective of this proposal is to investigate the flexural behavior of one-way reinforced concrete slabs embedded with PET bottles using laboratory experiments and numerical studies. To do so, 11 reinforced concrete slabs of 2200 mm length and 600 mm width were constructed and instrumented with strain gauges and LVDT’s and tested by a 4-point loading scheme under a displacement-controlled loading rate. The study considered the effect of the slab thickness (180 mm and 230 mm) concrete compressive strength (30 MPa and 50 MPa), steel reinforcement ratio (0.291% and 0.418%), percentage of the void (29% 22% and 17%) as well as top reinforcement ratio (0% and 0.192%). The results addressed stiffness, elastic behavior, yielding, post yield performance, ductility and ultimate strength. The behavior of tested voided slabs were compared with that of corresponding solid slabs. ACI-318 code equations were used to predict the moment capacities of the tested specimens. In addition, nonlinear finite element models were created using ANSYS and load-deflection curves from those models were compared with the experimental curves of the corresponding specimens. In general, findings of the study demonstrated that voided slabs exhibit on average a 5.1% decrease in moment capacity, 6.5% decrease in ductility, 12% increase in residual capacity factor and 4.29% decrease in stiffness. The ACI-318 code equations were found too conservative when used to predict the moment capacities of voided and solid specimens as on average, the experimental results yielded a 22.5% increase in moment capacity. However, in general finite element models created by ANSYS accurately predicted the flexural behavior of the specimens.College of EngineeringDepartment of Civil EngineeringMaster of Science in Civil Engineering (MSCE
Bulk passivation of perovskite films utilizing halide anion ionic liquids
No full textChemical additives to perovskite precursors constitute a predominant route to passivate defects in perovskite films and improve carrier charge dynamics. In this work, ionic liquids (ILs) with chloride and iodide anions are used as additives for bulk passivation of perovskite films. The ionic liquids in the form of 1‑butyl‑4-methylpyradinium iodide (IL-I) and 1-ethylimidazolium chloride (IL-Cl) are mixed individually with a precursor of Cesium Formamidinium Lead Triiodide and Methylammonium Chloride (CsFAPbI3−MACl). The decay of charge carriers within the perovskite film before and after passivation with ILs was measured by Time Resolved Photoluminescence Spectroscopy (TRPL). The effect of added ILs on the recombination rate of the photocarriers was investigated by analyzing the decay of the TRPL signal in all samples. The average lifetimes obtained within one day of preparations were 79 ns, 73 ns and 275 ns for pristine perovskite, IL-I passivated perovskite and IL-Cl passivated perovskite films, respectively. These values show that the presence of the IL with chloride anion greatly improves the average lifetime of the charge carrier by around 250%, while IL with iodide anion decreased the lifetime by 32% as compared with the pristine perovskite sample. This finding renders the IL-Cl passivated perovskite films as a valuable resource in applications ranging from photoelectric to hydrogen generation devices
Suspicious Behavior Detection with Temporal Feature Extraction and Time-Series Classification for Shoplifting Crime Prevention
No full textThe rise in crime rates in many parts of the world, coupled with advancements in computer vision, has increased the need for automated crime detection services. To address this issue, we propose a new approach for detecting suspicious behavior as a means of preventing shoplifting. Existing methods are based on the use of convolutional neural networks that rely on extracting spatial features from pixel values. In contrast, our proposed method employs object detection based on YOLOv5 with Deep Sort to track people through a video, using the resulting bounding box coordinates as temporal features. The extracted temporal features are then modeled as a time-series classification problem. The proposed method was tested on the popular UCF Crime dataset, and benchmarked against the current state-of-the-art robust temporal feature magnitude (RTFM) method, which relies on the Inflated 3D ConvNet (I3D) preprocessing method. Our results demonstrate an impressive 8.45-fold increase in detection inference speed compared to the state-of-the-art RTFM, along with an F1 score of 92%,outperforming RTFM by 3%. Furthermore, our method achieved these results without requiring expensive data augmentation or image feature extraction.American University of SharjahZayed Universit
Cardiovascular health research priorities in the United Arab Emirates
No full textBackground: Cardiovascular diseases (CVDs) are a leading cause of morbidity and mortality in the United Arab Emirates (UAE) and have been prioritized for intervention by healthcare authorities and clinicians. Aim: To identify clinically relevant research priorities for the treatment and prevention of CVDs in the UAE. Methods: This study used the nominal group technique to identify CVD-related research priorities. Participants were 37 experts from UAE hospitals, academic and research institutions, CVD associations, and paramedical organizations. Results: Initially, 138 research topics were suggested by participating experts. These topics were then refined to identify the most important research priorities related to CVD prevention and treatment. The top research priority areas were: development of evidence-based, customized algorithms for CVD prevention and in-hospital emergency interventions; the availability, accessibility, and affordability of CVD treatment and rehabilitation; identification of relationships between CVDs, lifestyle factors, and mental health; efficacy and constraints in the management of cardiac emergencies; and epidemiological studies that trace CVD in the UAE. Conclusion: The identified research priorities will guide a more informed research program for CVD treatment and prevention in the UAE. Funding opportunities and support for researchers should be prioritized for these identified research areas
INScription: Department of International Studies (INS) Issue #11 (January 26, 2023, Issue 1)
No full textCollege of Arts and SciencesDepartment of International Studie