United Arab Emirates University
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THE SIMULATION OF HYPERSPECTRAL OBSERVATIONS BY THE UPCOMING SPACECRAFT “ARAB SATELLITE 813”, WITH THE RADIATIVE TRANSFER MODEL SCIATRAN
No full textThe space mission “813 Satellite” has been awarded by the UAE Space Agency to the National Space Science and Technology Center (NSSTC) in the UAEU as prime contractor. The 813 satellite is an Arab satellite scheduled for launch in the year 2025. The spacecraft is designed to monitor Earth and climate change dynamics specifically over the MENA (Middle East and North Africa) region. The outcomes of the 813 Satellite are anticipated to support evidence-based decision-making processes and facilitate the implementation of sustainable environmental management strategies in the MENA region. Consistent with that, the proposed MSc project seeks to contribute to the advancement of knowledge in Earth observation and climate monitoring over the MENA region. The radiative transfer model Sciatran was developed by the University of Bremen, Germany, for data production from the spacecraft spectrometer Sciamachy, onboard of the European Environmental Satellite (Envisat, 2002-2012). The proposed Msc project will use Sciatran for the simulation of hyperspectral observations by payload instruments of the forthcoming 813 satellite. That will take into account atmospheric, surface, and environmental conditions, such as aerosols, clouds, surface features, and others within the MENA region. The goal is to build technical know-how, in preparation for hyperspectral data production and exploration of the 813 satellite
A NOVEL DRUG-LOADED INJECTABLE HYDROGEL SYSTEM USING OXIDIZED INULIN AND PLURONIC F-127 WITH Β-CYCLODEXTRIN NANOCRYSTALS FOR OCULAR DEFECT TREATMENT
No full textThe human eyes have the most complex and advanced defence mechanisms. Due to this barrier, efficient treatment of ocular disorders is always a crucial issue, especially while treating the posterior segment of the eyes. Most of the diseases occurring in the posterior segment of the eyes include age-related macular degeneration, retinitis, diabetic retinopathy and uveitis. Topical and systemic administration of drugs, intravitreal injection, and insertion of non-biodegradable implants are several different approaches employed to treat ocular diseases. These methods have shown promising results in treating age-related macular degeneration but require higher dosage and multiple administration of the drug to the diseased eye or it requires a second surgery to be performed to remove the implant. Recently, hydrogels have gained enormous interest. In this study a novel drug-loaded injectable hydrogel system using oxidized inulin and Pluronic f-127 with β-cyclodextrin nanocrystals will be used to deliver drug to the eye posterior segment. Developed regel ability to release the drug in a controlled manner will be investigated. The fabricated biomaterial, with varying ratios of polymers and drugs, would undergo numerous physical, chemical, thermal and biological characterizations to evaluate their performance as ocular implants. This research presents the design, fabrication, and in-depth characterization of a novel injectable hydrogel system composed of oxidized inulin and Pluronic F-127, integrated with β-cyclodextrin-based nanocrystals for the targeted treatment of ocular defects. The hydrogel is engineered to offer minimally invasive administration, sustained therapeutic delivery, and structural support within the delicate ocular environment. The system’s injectability, swelling ratio, and degradation profile were evaluated to confirm its suitability for intraocular applications. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX) were used to examine the topography and elemental distribution of the composite matrix, while nanoparticle tracking analysis (NTA) assessed the size and dispersion of the embedded nanocrystals. Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD) confirmed the chemical interactions and crystallinity of the hydrogel components. Thermal properties were determined using Thermogravimetric Analysis (TGA) to evaluate formulation stability. In vitro drug release studies demonstrated a sustained and controlled release profile, suitable for long-term ocular therapy. The hydrogel also exhibited significant antioxidant activity, effective antibacterial properties against common ocular pathogens blood test. Biocompatibility was extensively evaluated using retinal pigment epithelial (RPE) cells, through live/dead cell staining, DAPI nuclear staining, and ELISA for inflammatory cytokine expression. Ex vivo ocular tissue studies further confirmed the hydrogel’s adhesive properties, biodegradation behaviour, and tissue compatibility
ROBUST CONTROL OF LCL-FILTERED THREE-PHASE GRID-TIED INVERTERS USING H∞ SYNTHESIS: DESIGN, ANALYSIS, AND EXPERIMENTAL VALIDATION
No full textThis thesis presents the design, development, and practical implementation of various robust current control strategies for LCL-filtered gridtied inverters, with the aim of maintaining robust stability over a range of plant perturbations, while ensuring high-quality current delivery to the utility grid. Chapter One presents the literature review, while Chapter Two focuses on the modeling of the system under study. In the third Chapter, the system dynamics are augmented with an appropriate servo-compensator to ensure that, at steady-state, the grid current accurately tracks its sinusoidal reference with zero steady-state error, even in the presence of model uncertainties. This augmented system serves as the basis for designing a simple state-feedback controller using the linear quadratic regulator (LQR) approach. Notably, the LQR technique is formulated to achieve robust stability across a range of plant perturbations. The performance of the closed-loop system under the LQR approach depends primarily on the elements of the weighting matrices, whose dimensions are dictated by those of the controlled system. However, the inclusion of the servo-compensator increases the number of plant states from the original three (associated with the LCL filter) to five, thereby complicating the selection of appropriate weighting matrices for the augmented system. Thus, selecting appropriate weighting matrices remains the primary challenge for applying this LQR approach to robustly stabilize the system under study. To overcome this challenge, a disturbance observer-based control (DOBC) scheme is proposed in the second part of this chapter. This approach combines a disturbance observer (DO) with the LQR controller. Acting as a servo-compensator, the DO estimates and compensates for unknown disturbances using the measured states of the LCL filter system. Meanwhile, the LQR approach, serving as the stabilizing component, is designed to maintain closed-loop stability across a range of model uncertainties. Unlike the previous approach, the LQR design here is based only on the original plant dynamics, which have an order of three. This significantly reduces the complexity associated with selecting appropriate weighting matrices for LQR control design. The main limitation of the LQR approach lies in the difficulty of explicitly specifying the desired transient response of the closed-loop system. In the third part of Chapter three, the LQR-based state-feedback controller is replaced by a design approach using linear matrix inequalities (LMIs). This method ensures stability of the closed-loop system by constraining the eigenvalues to lie within predefined regions of the complex plane despite a range of model uncertainties. As a result, not only does this method ensure robust closed-loop stability, but it can also meet certain requirements regarding the transient response such as limits on overshoot and settling time. As in the second part of the chapter, DO observer is employed to achieve zero steady-state error, provided that the closed-loop system is stable under the LMI-based state-feedback controller.
Chapter four employs the H∞ loop-shaping procedure to design a robust current controller for LCL-filtered grid-tied inverters. Specifically, an H∞ controller is synthesized by solving an algebraic Riccati equation, with the objective of enhancing the stability margin of a composite control structure that combines a conventional proportional-resonant (PR) controller with an active damping component. The PR controller is designed based on nominal system parameters to ensure zero steady-state error in the presence of model uncertainties. Similarly, the active damping component, also based on nominal parameters, employs capacitor current feedback to attenuate the resonance effects inherent to LCL filters, thereby ensuring the overall stability of the closed-loop system. However, the inherent mismatch between the actual and nominal system parameters can negatively impact the closed-loop stability. To address this issue, an H∞ controller is designed in this chapter to maximize the stability margin of the overall control system. Towards this end, the coprime factorization approach is applied to the open-loop system, comprising the nominal plant and the composite controller, to derive a perturbed model that captures system uncertainties. Then, H∞ loop-shaping procedure is employed on this perturbed model to synthesize a controller capable of maximizing the closed-loop stability margin with respect to model uncertainties.
Finally, Chapter five explores H∞ approach to design a robust current controller for LCL-filtered grid-tied inverters. Two controllers are proposed in this chapter: the first uses both the grid current and the converter current, while the second relies only on the converter current to regulate the grid current. Specifically, the first control structure is the same as that used in Chapter four to implement the PR controller with active damping. However, compared with Chapter four, the context in this chapter is different in that the PR controller and the active damping component are replaced by H∞ controllers. In other words, H∞ design procedure is used to develop a servo-compensator that guarantees asymptotic tracking of the grid current, along with a stabilizing controller that effectively attenuates the resonance associated with the LCL filter. H∞ design procedure relies on minimizing an H∞ performance objective, which in turn requires selecting appropriate weighting functions to achieve specific control objectives. The first key contribution of this chapter is the incorporation of a weighting function that accounts for the effect of measurement noise during the control design process. The second contribution of this chapter lies in using the H∞ design procedure to synthesize a current controller for grid current regulation based only on the converter current, thereby reducing the number of required current sensors. All controllers developed in Chapter three are validated through simulation tests, while those presented in Chapters four and five are validated through both simulation and experimental tests considering balanced voltages, unbalanced voltages, and 50% modeling errors. The results demonstrate strong robustness to parameter variations, accurate tracking of the current reference, and high-quality grid currents
IMPACT OF THE INCLINATION ANGLE OF CORRUGATED ENERGY ABSORBERS ON THE CRASHWORTHINESS PERFORMANCE: NUMERICAL STUDY
No full textIn the present study, cylindrical energy absorbers with various corrugation inclination angles were numerically analysed to evaluate their crashworthiness under quasi-static axial loading. Simulations were performed using ANSYS/Explicit Dynamics, operated in a quasi-static regime by applying a sufficiently slow loading rate to suppress inertial effects. Seven designs were evaluated: a smooth tube (no corrugation) and corrugated tubes with inclination angles of 0°, 15°, 30°, 45°, 60°, and 90°, measured from the horizontal axis.The total absorbed energy (TAE), mean crushing load (MCL), stroke efficiency (SE), specific energy absorption (SEA), initial peak force (IPF), and crushing force efficiency (CFE) were computed for each inclination case. TAE was calculated by exporting the force–displacement data from ANSYS as tabulated results, importing them into Excel sheet, and applying the trapezoidal rule to estimate the area under the curve. The case of 90° recorded the highest TAE (8,382.55 J), followed by the smooth (non-corrugated) tube (6,049.32 J). The lowest TAE value was the case of 30° (4,278.42 J) for 30°, indicating that mid-range inclination angles (30° and 45°) may lead to early instability and reduced plastic fold development. The 60° and 90° configurations showed improved performance, likely due to the formation of diagonal or shear-assisted folding paths that spread deformation more uniformly and delayed densification. The initial peak force (IPF) is lowest for the 0° corrugated case (27,555 N) and highest for the 90° case (102,570 N). This trend aligns with shell structure mechanics and plastic collapse theory, which suggest that as the corrugation angle increases, the structure develops more transverse stiffness and localized geometric resistance. These features delay the onset of plastic deformation and require a higher initial load to initiate global collapse. As a result, the load path shifts from a mostly axial mode to a combined axial-transverse response. This transition leads to higher initial resistance and explains the rise in peak force with steeper corrugation angles.This study provides an insight into the impact of corrugations and corrugation angle on the energy absorber performance, and crashworthiness systems in different applications (e.g. automotive and aerospace engineering, structural)
EVALUATING THE EFFECTS OF CO₂ AND UV-B ON SPOROBOLUS VIRGINICUS (L.) KUNTH GROWTH UNDER OPEN TOP CHAMBER: A COMPARISON OF SILICON NANOPARTICLE-TREATED AND UNTREATED PLANTS
No full textThe study focused at how silicon nanoparticles (SiNPs; 50 mg/L) affected the growth, photosynthetic efficiency, and biochemical responses of the salt-tolerant halophyte Sporobolus virginicus in four different environments. They are control, high CO₂, UV-B radiation, and a mix of high CO₂ and UV-B. Plants that were treated with SiNPs showed big changes in their shape, such as more biomass, bigger leaf area, and better root systems in all conditions. The use of combined stress treatments caused a big increase in the levels of chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids. As a result, that the plants were better at making food from sunlight and keeping themselves safe from it.
Biochemical experiments indicated that over time, plants that were treated with SiNP had higher amount of total phenols and proline, especially when they were under more stress conditions. At Scale 7 (1.843 absorbance), the phenolic content was greatest. This suggests that there were more antioxidative secondary metabolites that assist protect against abiotic stress. Proline, which is an important Osmo protectant, also progressively increased, reaching 0.642 mg/g at Scale 7. This illustrates how it helps maintain cells\u27 osmotic balance and keeps them safe from damage induced by stress.
In Stage 1 of Treatment 3, pigment analysis showed that the levels of chlorophyll a (0.0209 mg/mL), chlorophyll b (0.0074 mg/mL), total chlorophyll (0.0283 mg/mL), and carotenoid content (1.9677 mg/g FW) were the highest. This was connected to being exposed to UV-B and high levels of CO₂. In Stage 2, the amounts of chlorophyll were generally lower, but the levels of carotenoids were greatest in Treatments 7 and 8, which showed that the protective response was still going on
Raising Riyadh’s Readiness To Host Expo 2030 And World Cup 2034 Visitors
No full textRiyadh is the focus of attention of many local and expatriate tourists, and is witnessing a qualitative shift and rapid development in preparation for hosting Expo Riyadh 2030 and the FIFA World Cup 2034. This research sheds light on an important topic, which is the need to provide sufficient inventory in the hospitality sector to meet the expected needs for these two years. The research followed the methodology of studying and analysing data and statistics collected from the annual reports of the Ministry of Tourism and the General Authority for Statistics (Second data resource); to try to predict the reality and future of the hospitality sector in Riyadh. The research also followed an analysis of the readiness of the hospitality sector in Dubai when it hosts Expo 2020, and an analysis of the hospitality sector in Doha when it hosts the World Cup 2022. The research concluded that although Riyadh is working hard to provide the necessary infrastructure to host visitors to the two major global events in 2030 and 2034, visitors to each of the two events have different age characteristics, housing requirements, and periods of stay. The study also concluded that there is an expected deficit estimated at two hundred thousand hotel rooms, and the government is striving to provide 50% of it by 2030, and that there are opportunities to enhance the housing stock of Riyadh, such as shared housing in the private sector for individuals, which in turn constitutes a solution to the hospitality stock of Riyadh, given its size, in addition to the fact that it constitutes an additional income for individuals
أثر الحكم الصادر عن المحكمة الاتحادية العليا بعدم الدستورية
No full textThe Effect of The Judgment Rendered by the Federal Supreme Court Declaring Unconstitutionality
Constitutional judiciary represents the primary guarantee for the supremacy of the Constitution and the protection of rights and freedoms, as it exercises subsequent review over legislative texts to ensure their compliance with constitutional provisions. The judgments it issues are objective in nature, directed at the legislative text itself rather than the parties involved, which grants them absolute authority that binds all branches of government—legislative, executive, and judicial—as well as individuals. These judgments are final and cannot be appealed by any means, as confirmed by both the UAE Constitution and the Federal Supreme Court Law.
The importance of a judgment declaring a legislative text unconstitutional lies in its far-reaching consequences, particularly when such a text has been applied for many years. This requires careful regulation of its effects to avoid disrupting legal relations or creating legislative gaps. Accordingly, the UAE legislator has introduced a special legal framework to balance the protection of constitutional rights and freedoms on one hand, and the preservation of legal stability and public order on the other.
In the field of tax legislation, a judgment of unconstitutionality directly affects individuals’ financial rights and the state’s public treasury. For this reason, the UAE legislator has adopted a specific approach to regulating the effects of such judgments to balance the interests of individuals with the protection of public revenue. In the criminal law context, due to the serious impact of such provisions on personal liberty and the right to life, the default position is that the judgment declaring unconstitutionality should have retroactive effect, allowing all those previously convicted under the unconstitutional text to benefit from the ruling—thus ensuring equality and fairness in the criminal justice system.
Regarding the temporal scope of unconstitutionality judgments, legal systems differ between adopting retroactive effect, immediate and prospective effect, or postponing the enforcement of the ruling to allow the legislature time to amend the unconstitutional provisions and avoid legal vacuums. In all cases, constitutional court rulings maintain absolute authority and bind everyone, reinforcing the principle of constitutional supremacy and safeguarding the stability of the legal system
AN EXPLORATION OF THE USE OF SUPPLEMENTARY MATERIALS BY ENGLISH TEACHERS IN THE UAE
Get PDFThis study explores the use of supplementary materials in English classrooms in the United Arab Emirates (UAE), exploring their types, how teachers integrate them, and the challenges they encounter when implementing them in their English language classrooms. Using materials in language teaching and learning is important and widely recognized. Understanding these materials and their use is crucial as educational institutions evolve in teaching English, particularly in multicultural-speaking countries like the UAE.The study employed a qualitative case study approach, collecting data through triangulation, which comprised classroom observations, semi-structured interviews, and artifacts. Thematic analysis revealed patterns in the types of supplementary materials used, the teaching practices employed, and teachers\u27 methods to integrate them effectively. The findings indicated that digital tools, such as PowerPoint, YouTube videos, and interactive platforms, were the most commonly used supplementary materials, alongside printed worksheets. In contrast, authentic materials were used sparingly. As for results pertaining to challenges, teachers encountered time constraints, concerns about cultural appropriateness, and technical issues in integrating these materials.This study improves our understanding of English teaching practices in the UAE by offering insights into how educators address pedagogical challenges and make the most of available materials. The study highlights the importance of institutional support for developing materials and training teachers to enhance the effectiveness of integrating supplementary materials in English classrooms across the UAE
FROM MICROPLASTIC IMPACTS TO BIODEGRADATION SOLUTIONS: INVESTIGATING MICROPLASTIC CONTAMINATION, MICROBIAL RESPONSES, AND EFFICACY OF SYNTHETIC MICROBIAL CONSORTIA IN PLASTIC DEGRADATION
Get PDFPlastics, including microplastics, pose significant environmental threats due to their widespread presence and harmful ecological effects. This dissertation present three distinct, yet interconnected studies. First, a study on microplastic contamination in urban recreational parks was conducted in Al Ain, UAE. Results showed that low-density microplastics were present in 87% of soil samples, with FTIR analysis identifying synthetic polymers such as PE and PP. Additionally, these microplastics were found to negatively affect soil pH and moisture levels, emphasizing the need for enhanced monitoring and management strategies. Second, the effects of ground microplastics on Photobacterium leiognathi spp., a marine luminous bacterium, were examined. Findings revealed that microplastic exposure altered bioluminescence, cell viability, and influenced biofilm formation. Moreover, strain-specific responses indicated that ground microplastics disrupted quorum sensing, suggesting that these plastic particles act as environmental stressors on marine microorganisms. Lastly, to address polyethylene terephthalate persistence, synthetic microbial consortia or microbial communities (SynComs) were developed. These consortia demonstrated potentially for enhance PET degradation via synergistic microbial interactions, biofilm formation, and enzymatic activity. The study also conducted whole genome sequencing of two bacterial strains, Bacillus safensis F18 and Escherichia coli 9SH, that have potential application in plastic biodegradation. The B. safensis F18 possessed known plastic-degrading enzyme called hydrolase. Therefore, these findings offer promising strategies for mitigating plastic pollution through microbial degradation. Overall, this dissertation contributes to the understanding of microplastic pollution impacts and offer promising bioremediation approaches, with potential applications in industrial-scale waste management
THE DEVELOPMENT OF YEAR ONE STUDENTS\u27 READING ABILITY IN A CURRICULUM USING MONSTER PHONICS SCHEME IN THE UAE
Get PDFThis study explores the impact of the Monster Phonics program on the reading development of Year 1 students in Al Ain, UAE. Reading proficiency is a fundamental skill in early education, and phonics instruction plays a crucial role in literacy acquisition. Monster Phonics, a color-coded synthetic phonics program, has been increasingly adopted in classrooms, yet its effectiveness in multilingual settings remains underexplored. This research aims to investigate how students\u27 reading ability develops in the context of a curriculum using the Monster Phonics scheme. A mixed-methods approach was employed, combining quantitative assessments pre- and post-tests on grapheme recognition, word reading, and reading comprehension with qualitative data collected through teacher interviews and classroom observations. The study involved 25 Year 1 students from diverse linguistic backgrounds and four teachers familiar with Monster Phonics. Statistical analysis of test scores revealed significant improvements in students\u27 ability to recognize graphemes, blend sounds, and comprehend texts. Qualitative findings highlighted high engagement levels, with teachers noting the program’s effectiveness in reinforcing phonics rules, though additional scaffolding was recommended for struggling learners. The study provides empirical evidence supporting the effectiveness of Monster Phonics in multilingual classrooms, demonstrating its potential to enhance phonics instruction and early literacy skills. By evaluating Monster Phonics within a diverse learning environment, this research contributes to the broader discourse on phonics instruction, offering practical insights for educators and policymakers aiming to optimize early reading strategies