United Arab Emirates University
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ASSESSING ASSET MANAGEMENT IN AEC/FM: UNVEILING LIMITATIONS AND ADVANCING SOLUTIONS WITH DIGITAL TWIN
Get PDFIn recent years, the concept of Digital Twins (DTs) has emerged as a transformative technological innovation with the potential to revolutionize asset management practices. A Digital Twin is a digital representation closely linked to a physical entity, enabling bidirectional information exchange and data-driven decision-making. Within the realm of Architecture, Engineering, and Construction/Facilities Management (AEC/FM), DTs offer a diverse array of applications for enhancing asset management.This thesis aims to demystify the concept of DTs and explore their existing applications in asset management, particularly within the AEC/FM industry. To achieve this, the research employs a twofold approach: a systematic review of existing literature followed by structured interviews with FM professionals.The systematic literature review revealed that the construction processes of DTs are still in their nascent stages. However, it unveiled a multitude of potential applications for DTs across the entire lifecycle of assets. These applications encompass sustainable retrofitting, predictive maintenance, and the preservation of heritage assets.The interviews conducted with FM experts provided valuable insights into the current state of facility management, the challenges faced by FM personnel, and a glimpse into the future of the industry. Moreover, these discussions led to recommendations for further research in this evolving domain.In summary, this thesis advances our understanding of DT and sheds light on its multifaceted applications in asset management, with a particular focus on the dynamic landscape of the AEC/FM industry. It underscores the transformative potential of DT as a tool for optimizing asset performance and decision-making throughout the asset lifecycle
DESIGN AND MODELLING OF FEM BASED MEMS CAPACITIVE ACCELEROMETER AND GYROSCOPE FOR THE QUADCOPTER/UAV APPLICATIONS
Get PDFThis study presents the design, simulation, and analysis of Micro Electromechanical Systems (MEMS) sensors, constituting the principal components of MEMS-based Inertial Measurement Units (IMUs). The main objective of the study is to design, simulate and analyze 3-axis capacitive accelerometer and 3-axis gyroscope. The MEMS-based capacitive accelerometers and gyroscope are analyzed using Ansys Workbench. Modal, Static Structural and harmonic analysis are used to obtain resonant frequencies, deformation/stress and profile of amplitude over a wide range of frequencies. Mechanical sensitivity analysis of the designed accelerometer and gyroscope is performed using the Finite Element Method (FEM). Analytical equations are developed to calculate mechanical sensitivity and capacitance sensitivity and a comparison is performed between the FEM analysis and the analytical calculations. A simulation study is performed in MATLAB/Simulink for the designed MEMS accelerometer and gyroscope to analyze the performance of the designed accelerometer and gyroscope sensors. Kalman filter is employed in the Simulink model to investigate the effects of measurement noise. The main findings of the study demonstrated that under typical loads of 10 g accelerations and 34.9 rad/s angular rate, the structures of the two sensors can withstand such loading and exhibit little deformations. The IMU sensor can be used in various applications in unmanned aerial vehicles (UAVs) and drones
The System of Civil Liability Standard for Injuries Resulting from Driverless Vehicles: A Comparative Study under UAE and Comparative Laws
Get PDFThe development of vehicle automation systems has reached very high levels, it is expected that this new generation of our vehicles will invade our markets, more than ever before. Even if the goal of this Driverless car is to achieve the highest levels of safety, comfort and sustainability, and to reduce human errors that find their source in human mistakes, the safety of using this vehicle on our roads still raises doubts. This contribution started from the fact that today\u27s driverless vehicles are still in need of a civil liability rules, and compensation system that would effectively address the problem of attribution of damages to these vehicles, especially with the anticipated retreat of drivers in their traditional sense, and even withdrawal with the emergence of fully automated vehicles. Through this research, we will present the new features of the Liability and Insurance Law, which must be prepared, to face traffic accident scenarios that occur between autonomous vehicles between them or with ordinary vehicles, this system will take a standard dimension by taking into account the levels of automation employed in the vehicle, and the distribution of the risks of unsafe use of this modern technology, to its users and the players of this promising industry, from drivers and owners of autonomous vehicles, as well as professionals of this industry who are producers, designers of smart programs, with the multiplicity of its brokers.
The study concluded that it is necessary to review the system of support for traffic accidents victims in the UAE legislation, by updating the special system to accommodate new data for smart vehicles, and to ensure safe access to this technology in our contexts in the future
CANAGLIFLOZIN AMELIORATES AUTISTIC-LIKE FEATURES AND MITIGATES BRAIN OXIDATIVE STRESS LEVELS IN VALPROIC ACID-INDUCED AUTISM IN RATS
Get PDFAutism spectrum disorder (ASD) is a neurodevelopmental disease with a substantially increasing incidence rate. It is mainly characterized by repetitive behavior, intellectual difficulties, social communication and interactions deficits. Many medications, dietary supplements, and behavioral treatments have been recommended for ASD management, however, there is no cure yet. Recent studies have examined the therapeutic potential of the sodium-glucose cotransporter 2 (SGLT2) inhibitors in neurodevelopmental diseases, based on their proved anti-inflammatory and antioxidant effects. The main objective of this study is to assess the ability of canagliflozin in improving the behavioural characteristics of autistic rats and investigate the efficacy of canagliflozin in reducing oxidative stress and acetylcholinesterase activity (AChE) in VPA-exposed rats. Moreover, compare male and female autistic wistar rats with regard to treatment response. ASD was induced by prenatal exposure to 500 mg/kg of Intraperitoneal (i.p.) valproic acid (VPA) at 12.5 gestational day (GD), then autistic rats were treated with 20, 50, or 100 mg/kg of (i.p.) canagliflozin for 29 days. Additionally, rats with VPA-induced ASD were subjected to behavioral assessment at post-natal day 51 (PND) including open field, marble burying, and nestlet shredding tests to examine their repetitive-compulsory behavior and anxiety. After behavioral assessment, rats went through perfusion, and then hippocampus, prefrontal cortex, and cerebellum were extracted to undergo biochemical assays. Canagliflozin achieved substantial ameliorating effects on ASD-like behaviors at various doses. Also, 20, 50, and 100 mg/kg of canagliflozin significantly increased antioxidants levels including GSH, SOD, CAT in different brain regions, as well as decreased MDA and AChE activity in the brain of autistic rats. This study, for the first time, proposed repurposing the use of canagliflozin in ASD management. Moreover, the results stated promising therapeutic effects, that were noticeable in both genders
AERODYNAMIC & AEROACOUSTIC PERFORMANCE OF WIND TURBINE BLADES FEATURING ENHANCED FLOW-CONTROL
Get PDFWind energy, being one of the cleanest and most sustainable sources, has undergone remarkable growth in recent years due to advancements in aerodynamics and increased power output. The research community is actively pursuing the development of cutting-edge solutions to further optimize wind turbine technology, ensuring its maximum efficiency and revolutionizing the landscape of wind power.This research aims to design and develop flow-control devices for wind turbine blades, employing both active and passive control mechanisms, namely morphing trailing-edge and slot-profile, respectively. The objective is to enhance wind turbine performance across a wide range of wind speeds. The morphing trailing-edge mechanism focuses on adjusting the local mean-camber through trailing-edge morphing, resulting in augmented blade lift and torque, consequently reducing the wind turbine\u27s cut-in speed. Conversely, the slot-profile mechanism manages boundary layers by suppressing flow separation and delaying stall, harnessing greater lift and torque, and effectively reducing the rated wind speed.Numerical investigations form the core of the research methodology, providing insights into various flow parameters such as pressure and velocity fields, surface flow, skin friction, boundary layers, flow separation, and wake profiles to analyze the influence of developed flow-control mechanisms. These flow-control devices will eventually be integrated into the National Renewable Energy Laboratory (NREL) Phase-VI research wind turbine for performance analysis. The research promises to deliver significant power augmentation and increased productivity of wind turbines, particularly during off-design operating conditions, a critical advantage for regions characterized by low average wind speeds, such as the Middle East and South-East Asia.Furthermore, the research outcomes hold potential for broader applications in the field of rotorcraft and unmanned aerial vehicles. These flow control techniques can be implemented on rotors and/or propellers, generating greater lift at relatively lower RPM, thereby resulting in substantial fuel/power savings and increased flight endurance
INTEGRATED EXPERIMENTAL AND DFT STUDY OF PALLADIUM AND NICKEL METALS SUPPORTED ON REDUCIBLE METALLIC OXIDES FOR SELECTIVE HYDROGENATION OF ALKYNES AND DIENES BONDS
Get PDFThis dissertation investigates the capacity of ceria (CeO2) to serve as a stand-alone reactive catalyst, and to act as catalyst support for different catalyst configurations. Experimental and density functional theory (DFT) approach were used to critically predict and to design ceria-containing catalysts. Ceria owes the catalytic propensity to the ability to undergo switch in the oxidation state from the +4 to +3 states. Motivated by experimental studies involving CeO2 catalysts, defects CeO2 surface with an oxygen vacancy (CeO2(111)_Vo) was used to explore the decomposition chemistry of methanethiol based on DFT. The potential formation pathways revealed that the initial uptake of CH3SH takes place via either C-S or S-H bond fissions through modest activation barriers. In the initial decomposition pathways, Vo spots represent strong acidic sites, and thus facilitating rupture of C-S and S-H fissions. Adjacent HS* and HO* sites undergo a hydrogen diffusion reaction to ultimately produce H2S rather than water. The outcome of this study necessitated the actual formation of vacancies on ceria surface via the inclusion of dopants into the ceria lattice from experimental and DFT perspectives. Niobium materials are evolving and their use in catalysis is being widely investigated. Thus, this dissertation reported the structural and electronic properties of various configurations of mixed Ce-Nb oxides. Tetrahedral O atoms demonstrate an increase in electronegativity and this in turn facilitates catalytic propensity of the material because the O atoms will exhibit higher affinity for adsorbed reactants. CeO2 after Nb doping displays a noticeable band gap narrowing, confirming the improvement in the catalytic behavior. The 4 d states of the Nb2O5 is found to fill up the 4f states of CeO2 around the Fermi energy level promoting electrons excitations of the CeO2. Pertinent industrial reactions that involves the selective hydrogenation of alkynes and dienes bonds were tested on either CeO2 or Nb2O5-CeO2 supports. The presence of phenylacetylene (PA) in the styrene (ST) stream poisons the catalyst during polymerization reaction, increasing the operational cost. Different loadings of nickel and niobium metals supported on cerium (IV) oxide were prepared and characterized. H2-TPR reveals that Nb offers high interaction with the CeO2 support that promoted O vacancies necessary to induce facile switch in the Ce oxidation states from +4 to +3. Gas phase PA Hydrogenation shows steady increase in the conversion with rise in temperature (150-300°C). The Nb catalysts display highest conversion at the optimum value of 5% Nb content. The catalysts selectivity towards ST was highest on the Nb catalysts reaching 96% and 91% on the Ni-5%NbCe and Ni-10%NbCe catalysts, respectively. Desorption of ST from the catalyst surface requires a mere energy value of 15 kJ/mol. This easy desorption of ST from the catalysts surface enhances the selectivity due to the electron transfer effect of Nb atoms to CeO2 support. Selective hydrogenation of 1,3-butadiene to more valuable butenes products was investigated on supported palladium and nickel-palladium catalysts on ceria. H2 pretreatment of the samples confer slight increase in the lattice constants and the crystallite sizes, which is associated with the formation of oxygen vacancies. The Ce3+ concentration determined by XPS shows that the palladium catalysts is more decorated with the reduced Ce state than the palladium-nickel catalysts owing to the PdO and NiO species that demands reduction. Butadiene conversion shows steady rise with temperature (40-120°C) until the full conversion was reached on all the catalysts. The products distribution reveals that 4% Pd content directs the products toward butane when 40°C is exceeded. Lowering the Pd content and the simultaneous inclusion of Ni into the catalysts preserve the activity. Constructed mechanisms by DFT calculations feature low reaction barriers for involved surface hydrogenation steps; and thus, accounts for the observed low temperature of the surface hydrogenation activity. Selective formation of 1-butene partially stems from its relatively weaker binding to Ni sites in reference to Pd sites. The mapped out mechanisms entail higher reaction barrier for the formation of 2-butene; in an agreement with experimental observation pertinent to its formation at higher temperatures when compared with that of 1-butene. Finally, the selective hydrogenation of 1,3-butadiene was tested between 50-300°C on Ni catalysts supported on Nb2O5-CeO2. XRD results reveal the formations of nickel oxide and nickel metals for the calcined and reduced sample, respectively. The catalysts exhibit total conversion even at lower Ni loading, suggesting the high activity of the catalysts as confirmed from the measurement of the turn over frequency (TOF). The selectivity potential of the catalysts assumes a rather different configuration not previously reported for pure butadiene stream. The catalysts show selectivity to the expected butenes but rather than forming butane, propene and propane were formed at higher reaction temperature
UNRAVELING THE ORIGINS OF GRB190114C: AN INVESTIGATION OF PROGENITOR MODELS THROUGH OBSERVATIONAL ANALYSIS
Get PDFGamma-ray bursts (GRBs) are among the most energetic and violent events in the universe, characterized by sudden and intense emission of gamma rays lasting from a fraction of a second to several minutes. The primary focus of this thesis is to study gamma-ray bursts (GRBs), with a specific emphasis on GRB190114C. GRB190114C is a long-duration GRB that was detected on January 14, 2019, by the Fermi Gamma-ray Burst Monitor (GBM) and the Swift Burst Alert Telescope (BAT). It had a T90 duration of 116 s and a redshift of z = 0.4245, which corresponds to a luminosity distance of about 2.9 billion light-years. The first part of this thesis presents the results of a 140-day observational campaign of the GRB190114C radio afterglow using the Australian Telescope Compact Array (ATCA). The study aimed to determine the dynamical and microphysical radio afterglow parameters and model the multifrequency radio data using variations of interstellar medium (ISM) and wind models. The obtained data allowed for the identification of the most plausible model that explains the evolution of the GRB190114C radio afterglow. Furthermore, the analysis helped to derive various microphysical parameters to better understand the properties and characteristics of this GRB. The second part of the work investigates the suitable progenitor model for GRB190114C. The widely accepted progenitor model for long-duration GRBs is the collapsar model, which involves a black hole-accretion disk (BHAD) system. In the context of the collapsar model, the BHAD system is formed from the remnants of the massive star’s core that has collapsed into a black hole. Under the same model, there could be a possible binary system, where a helium core has a compact companion. Furthermore, the work discusses the two mechanisms that could cause these systems to produce highly energetic jets: neutrino annihilation and magnetohydrodynamics (MHD), which uses the Blandford-Znajek mechanism. These mechanisms were compared based on the observational results to further narrow down the plausibility of the progenitor models. To investigate the plausibility of these progenitor models, we derived prompt emission parameters such as isotropic energy Eiso and luminosity Liso and used the multi-wavelength afterglow data from X-ray to radio to fit the light curves and spectral energy distribution, and derive the microphysical parameters. To further assess the likelihood of the proposed progenitor models, we compared these models and mechanisms based on the observational results obtained from the analysis of the afterglow data.Overall, this thesis contributes to a better understanding of the nature and properties of GRBs and their progenitor models. The detailed analysis of GRB190114C, including the modeling of its radio afterglow and investigation of its progenitor model, provides new insights into the most energetic phenomena in the universe. The findings of this study can inform future studies of similar events and improve our understanding of these fascinating phenomena
SELECTIVE PRODUCTION OF LEVOGLUCOSAN (LG) FROM PYROLYSIS OF DATE PITS AND ITS CATALYTIC TRANSFORMATION INTO TRANSPORTATION FUELS
Get PDFLevoglucosan (LG) or (1,6-anhydro-β-D-glucopyranose) signifies important sugar derivatives produces in appreciable quantities from thermochemical and biochemical degradation of biomass. It is often regarded as an important platform chemical for the synthesis of value-added products, most notably styrene and furans. The work in this thesis entails two broad aims; to produce LG from pyrolysis of date pits; and then convert the LG into transportation fuels through a hydrodeoxygenation (HDO) reaction. The particular choice of date pits stems from its local relative abundance as a waste biomass. Aiming to further improve the yield of levoglucosan yields from pyrolysis of date pits, pre-treatment methods were carried out via washing the biomass with different concentrations of selected acids (sulfuric acid: 1M /3M, nitric acid: 1M / 3M), also well as with hot water. Chemical and elemental compositions of the five considered samples were thoroughly analyzed and characterized by a wide array of techniques such as Neutral Detergent Fiber (NDF%), ASH content and organic Matter (%) and Mineral Nutrients Profile (ppm). By utilizing Py-GC/MS system, the products distribution from pyrolysis of raw and treated date pits were obtained at a range of temperatures between 300-500°C. Compared to the raw date pits, pyrolysis of treated date pits by 1 M H2SO4 acid exhibited a dramatic increase in the concentration of levoglucosan due to the profound removal of the various categories of minerals in date pits and increasing the NDF%. Results show that the highest yield of (~ 72%) was attained after pre-treatment with 1 M H2SO4 solution at a temperature 300°C. A positive correlation prevails between the removal efficiency of alkali/alkaline earth metals (AAEMs) and the yield of LG. The former catalyzes ring opening reaction that results in the destruction of sugar derivatives. Similarly, the water pretreatment increases the yield of LG compared to the raw date pits. Outcomes demonstrated herein convey a practical method to enhance the production of commodity chemicals from waste biomass. The second part of the thesis presents a viable gaseous hydrodeoxygenation (HDO) route for Levoglucosan (LG) that leads to the formation of non-oxygenated hydrocarbon cuts that make commercial transportation fuels, namely gasoline, diesel, and jet fuels. The outlined process encompasses HDO of an evaporated stream of dissolved LG over 5% Ni-CeO2 catalysts between 100°C–500°C. It is found that the load of the aliphatic compounds attains values between 68.1% and 75.3% across the investigated temperature window. Similarly, fractions of aromatic compounds remain within 8.1%–13.9%. Major observed aliphatic compounds include tetradecane, dodecane, octane, and decane. Alkylated benzenes appear in appreciable quantities. Governing HDO’s mechanisms were mapped out by density functional theory (DFT) calculations. Utilizing a 10% load of Ni has slightly reduced the relative area of aliphatic compounds. The combined area of the oxygenated compounds remains less than 10% at all temperatures. This finding entails a profound HDO’s capacity of the deployed catalyst and opens a direct venue for the effective utilization of LG in fuel production. Overall, this research underscores the utilization of lignocellulosic biomass, specifically date pits, as a valuable carbon source in the biorefinery concept
The Challenges of the Current and Retrospective Digital Archiving of Doctoral Dissertations: Toward Integration of Several University Collections at the University Library “Svetozar Marković” in Belgrade
Get PDFThe University library “Svetozar Marković” possesses the most extensive and most valuable collection of doctoral dissertations defended at the University of Belgrade and other universities in Serbia or abroad, but this corpus is not unique. It can be divided into several sub-collections: current doctoral dissertations, which include mandatory archiving since 2012; a collection of doctoral dissertations digitized retrospectively by users’ demand; and, finally, a collection of old Serbian dissertations, which includes those defended by Serbian scientists at foreign universities and defended at the University of Belgrade at the beginning of the 20th century. In this paper, these sub-collections are described, analyzed, and observed through several criteria (completeness, existing support, location, availability, and copyright issues). The importance of a straightforward procedure was revealed, and copyright issues were identified as predominant. Legal regulations at the national or university level, together with library institutions that perform digitization services, can achieve desirable results
Trends of Mathematics Education Research Studies Published in Journal of Mathematics Education from 2017 to 2021
Get PDFThe study aimed to analyze the trends of mathematics education research published in the Journal of Mathematics Education in the last five years and to propose a future map for mathematics education research in the light of the analysis results, professors’ and experts’ views, and the contemporary international trends. The study used a simplified model to classify research in seven domains. Also, the researcher used a questionnaire for professors and experts to determine a future map for mathematics education research. The results showed the research trends in the Journal of Mathematics Education were most of the articles were single authored (79.5%), the use of the experimental methodology (63%), the dominance of teaching strategies research (37%), the number of primary school students (27%) followed by the middle school students (26%), the category of normal students (89.7%), and the experimental research using one independent variable (62.5%). For the dependent variables, the articles used two dependent variables (30.7%). Achievement was the most frequent at 17%. The interaction of one independent variable with two dependents variables was the most frequent and the research co-authored by professors was 11%. The study suggested a future map for future mathematics education research. Recommendations and suggestions were presented.
Keywords: Research trends, research priorities, mathematics education, educational researc