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Influence of gas environment on the dynamics of wetting transition of laser-textured stainless steel meshes
No full textWe analyze the role of surrounding gas and aging in ambient air in the wettability behavior of laser-processed stainless steel meshes. Laser texturing of meshes was carried out in the presence of different gases (N₂, O₂, CO₂, Ar, and SF₆) in ambient atmospheric air and under different vacuum conditions. The influence of each gas on the evolution of the wettability properties after aging in ambient air is analyzed. The effects of low-pressure and vacuum aging allowed transforming the initial superhydrophilic characteristics of the laser-structured meshes to an almost superhydrophobic state.American University of SharjahEuropean Regional Development Fun
Metal Organic Frameworks Electrodes for Microbial Fuel Cell Applications and Hydrogen Production
No full textA Master of Science thesis in Chemical Engineering by Mohammed Abdullah Taher Mohammed Al Murisi entitled, “Metal Organic Frameworks Electrodes for Microbial Fuel Cell Applications and Hydrogen Production”, submitted in November 2021. Thesis advisor is Dr. Sameer Al-Asheh and thesis co-advisor is Dr. Ahmad Aidan. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).Microbial Fuel Cell is an innovative technology that offers production of clean electricity while treating the wastewater. One of the most important challenges affecting power generation is the overpotential losses at the cathode due to lower reaction rates occurring on the active sites of the electrode. This overpotential causes a voltage drop due to limitation of electrons transfer to the electrodes. Oxygen reduction reaction (ORR) is considered an important factor affecting the overall performance. Increasing the surface area of the electrode and using more effective catalyst can be considered as two of the most effective methods to overcome these problems. In this thesis, a novel in situ-growth of a 2D shell nanowires of ZIF-67 as template for N-doped carbon (Co/NC) via carbonization route was developed to enhance the ORR performance. The effects of different reaction time, different annealing temperature along with the effect of sulphur and selenium doping were studied for better oxygen reduction reaction (ORR) activity. The growth of the metal-organic framework (MOF) template on the carbon cloth was confirmed using SEM, XRD, and FTIR. The CoS/NC exhibited an enhancement on the ORR activity as evidenced by an onset potential and half wave potential of 0.0 vs VAg/AgCl and -0.1 vs VAg/AgC, respectively, with a limited current density exceeding the commercial Pt/C. Operating CoS/NC on MFC revealed a maximum power density of 30 ± 2.5 mW/m² , a maximum current density of 180 ± 2.5 mA/m² and a constant current discharge of 28 ± 2.5 mA/m²; such values are comparable to the commercial Pt/C. The enhancement of the ORR activity was mainly due to the 2D shell nano wire structure, conductivity of the ZIF-67 and the sulphur doping. Optimization study using real wastewater provided form Al Aweer treatment plant was conducted for the purpose of enhancing hydrogen production. The maximum power and current densities were 250 ± 2.5 mW/m² and 1100 ± 2.5 mA/ m², respectively, using a ratio 45:55% of anaerobic sludge to 3 g acetate buffer solution. A maximum biohydrogen of 0.5 ml/d was achieved using microbial electrolysis cell at an applied voltage of 1.4 V.College of EngineeringDepartment of Chemical EngineeringMaster of Science in Chemical Engineering (MSChE
Removal of Heavy Metals from Industrial Wastewater Using Microbial Fuel Cell
No full textA Master of Science thesis in Chemical Engineering by Marzieh Bagheri entitled, “Removal of Heavy Metals from Industrial Wastewater Using Microbial Fuel Cell”, submitted in December 2021. Thesis advisor is Dr. Sameer Al-Asheh and thesis co-advisor is Dr. Ahmad Aidan. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).The development in science and technology has resulted in a steady increase in the growth rate of several industries, thereby resulting in an increased demand of precious metals as well, such as gold and platinum. This also results in the selling prices for these metals to increase. Hence, recovery of such metals from low grade ores and scraps plays an important role. Conventional methods of recovery of gold can result in the pollution of environment. Additionally, despite low concentrations of gold being released into the environment, the recovery of this metal can provide additional profit and help to reduce operating costs. The objective of this work is to use Microbial Fuel Cells (MFC) as an alternative green technology to simultaneously remove heavy metals and recover remaining gold found in the effluent samples taken from one of the gold refinery industries in the UAE. Removal efficiency of pure tetrachloroaurate ions was investigated first to ensure the feasibility of MFC in terms of removing gold ions and determining the optimum conditions for removal efficiency in terms of catholyte solution, as well as initial gold concentrations. Next, the effect of copper ions on the removal efficiency of the gold ions was investigated due to their high presence in the actual wastewater samples. Later, the gold removal efficiency was evaluated from the industrial effluent. The effect of pH and initial biomass concentration on the gold removal efficiency was also determined. Based on the successful results, after 5 hours, 95% of gold removal efficiency from the wastewater containing 250 ppm of initial gold ions at ambient temperature with the 80g/L yeast concentration was achieved. After 48 hours of the cell’s operation under the same condition, 98.86% of AuCl₄ˉ ions were successfully removed from the solution. Based on the investigation of the effect of different factors, 100% removal efficiency of the gold was achieved at a pH of 2, initial yeast concentration of 80 g/L and the initial gold concentration in the waste solution being 250 ppm. On the other hand, the most suitable condition in terms of copper removal was found at a pH of 5.2 where 53% removal efficiency from the waste solution was accomplished.College of EngineeringDepartment of Chemical EngineeringMaster of Science in Chemical Engineering (MSChE
Forced vibration characteristics of embedded graphene oxide powder reinforced metal foam nanocomposite plate in thermal environment
No full textDynamic behavior of a new class of nanocomposites consisted of metal foam as matrix and graphene oxide powders as reinforcement is presented in this study in the framework of forced vibration. Graphene oxide powders are dispersed through the thickness of a plate made from metal foam material according to four various functionally graded patterns on the basis of the Halpin-Tsai micromechanical homogenization method. Also, three kinds of porosity distributions including two symmetric and one uniform patterns are considered for the metal foam matrix. As external effects, the plate is rested on the Winkler-Pasternak substrate and under uniform thermal and transverse dynamic loadings. By an incorporation of the refined higher order plate theory and Hamilton’s principle, the governing equations of the dynamically loaded graphene oxide powder reinforced metal foam nanocomposite plate are derived and then solved with Galerkin exact solution method to achieve the resonance frequencies and dynamic deflections of the structure. Moreover, the influence of different boundary conditions is taken into account. The results indicate that the forced vibrational response of the graphene oxide powder strengthened metal foam nanocomposite plate is dramatically dependent on various parameters such as graphene oxide powders’ weight fraction, different boundary conditions, various porosity distributions, foundation parameters and temperature change of uniform thermal loading.Ministry of Science and Technology of ChinaNational Science Foundation of ChinaShan Dong ProvinceEducation Department of Shandong ProvinceQatar National Librar
Computational Fluid Dynamics of Energy Separation in Vortex Tube
No full textA Master of Science thesis in Mechanical Engineering by Ahmad Mohammad Al Saghir entitled, “Computational Fluid Dynamics of Energy Separation in Vortex Tube”, submitted in May 2021. Thesis advisor is Dr. Mehmet Orhan and thesis co-advisor Dr. Mohammad Hamdan. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).Devil’s Tube is the name that some researchers chose for Ranque-Hilsch vortex tube because of the ambiguity of its working mechanism. In an attempt to unveil the principle of energy separations in this tube, this study uses the shear stress transport − turbulence model with viscous heating to investigate the flow structure inside the fluid domain and to examine the impact of the fluid’s properties on the performance of the temperature separation. Firstly, the flow parameters such as velocity, temperature, pressure, and density are plotted at various locations inside the tube. Thereafter, the energy separation performance is tested using five different gases, namely helium, air, oxygen, nitrogen, and carbon dioxide. In this regard, the effect of the gas properties, such as molecular weight, heat capacity, thermal conductivity, and dynamic viscosity are also examined. The study shows that the minimum cold temperature and the maximum hot temperature are achieved at different mass fractions and that the flow inside Ranque-Hilsch vortex tube consists of a forced vortex from r/R=0 to 0.9 and a free vortex from r/R=0.9 to 1. Furthermore, a comparison analysis is carried out to observe that helium yields the maximum separation while carbon dioxide yields the lowest; besides, one must account for viscous dissipation in modelling the energy separation in vortex tube. Moreover, energy separation performance improves with lower molecular weight and heat capacity, and higher dynamic viscosity of the working fluids, while no impact of the thermal conductivity is observed. Finally, it is concluded that the energy separation in vortex tube is due to the density gradient along the radial direction.College of EngineeringDepartment of Mechanical EngineeringMaster of Science in Mechanical Engineering (MSME
Cognitive Vigilance Enhancement using Audio Stimulation of Pure Tone at 250 Hz
No full textIn this paper, we propose a novel vigilance enhancement method based on audio stimulation of pure tone at 250 Hz. We induced two different levels of vigilance state; vigilance decrement (VD) and vigilance enhancement (VE). The VD state was induced by performing a modified version of the Stroop Color-Word Task (SCWT) for approximately 45 minutes. Likewise, the VE state was induced by incorporating audio stimulation of 250 Hz into the SCWT for 45 minutes. We assessed the levels of vigilance on 20 healthy subjects by utilizing Electroencephalogram (EEG) signals and machine learning. The EEG signals were analyzed using four types of entropies; Approximate Entropy (AE), Sample Entropy (SE), Fuzzy Entropy (FE), and Differential Entropy (DE). We then quantified vigilance levels using statistical analysis and support vector machines (SVM) classifier. We found that the proposed VE method has significantly reduced the reaction time (RT) by 44% and improved the accuracy of target detection by 25%, (p < 0.001) compared to VD state. Besides, we found that 30 min of audio stimulation has reduced the RT by 32% from the beginning to the end of VE phase of the experiment. The entropy measures show that the temporal profile of the EEG signals has significantly increased with VE. The classification results showed that SVM technique with DE features across all frequency bands can detect VE levels with accuracy varying between (92.10±02.24)% to (98.32±01.14)%, sensitivity of (92.50±02.33)% to (98.66±01.00)%, and specificity of (91.70±02.32)% to (97.99±01.05)%. Results also showed that the classification performance using DE has outperformed the other entropy measures by an average of +8.07%. Our results demonstrate the effectiveness of the proposed 250 Hz audio stimulation method in improving vigilance level and suggest using it for future cognitive enhancement studies.American University of Sharja
Polarimetric SAR Image Filtering by Infinite Number of Looks Prediction Technique
No full textSpeckle filtering in synthetic aperture radar (SAR) and polarimetric SAR (PolSAR) images is indispensable before the extraction of the useful information. The minimum mean square error estimate of the filtered pixels conducted to the definition of a linear rule between the values of the filtered pixels and their variances. Hence, the filtered pixel for infinite number of looks (INL) is predicted by a linear regression of means and variances for various window sizes. In this article, the infinite number of looks prediction (INLP) filter is explored in details to emphasize its ability to reduce speckle and preserve the spatial details. Then, the linear regression rule has been adapted to PolSAR context in order to preserve the polarimetric information. The number of the processed pixels used in the linear regression is adjusted to the variability of the scene. This effort increased the filtering performances. The reduction of the correlation between the pixels which constitutes an additional filtering criterion is discussed. Compared to the initially applied filter, the results showed that the improved INLP filter increased in speckle reduction level, augmented the preservation of the spatial details, increased the spatial resolution, reduced the correlation between the pixels and better preserved the polarimetric information. Simulated, one-look and multilook real PolSAR data were used for validation.American University of SharjahSmart City Research Institut
Portfolio Value Optimization Model for Sustainable Construction Projects
No full textA Doctor of Philosophy Dissertation in Engineering Systems Management by Taha Anjamrooz entitled, “Portfolio Value Optimization Model for Sustainable Construction Projects”, submitted in May 2021. Dissertation advisor is Dr. Sameh El-Sayegh. Soft copy is available (Thesis, Completion Certificate, and AUS Archives Consent Form).The continuous growth and development threaten the world’s natural resources and lead to several adverse effects. The construction industry is widely blamed for its negative impact on the environment. Yet, developers/clients do not consider sustainability criteria when selecting their portfolio of projects. Instead, they rely on traditional criteria that maximize their profit. Based on the review of related literature, there is a lack of portfolio selection methods that incorporate sustainability as key criteria. This research aims at developing a new portfolio value optimization model that integrates sustainability, organization benefit realization, and project success criteria. Twenty-six selection criteria were identified based on the literature review. These criteria were classified into two groups: sustainability group and organization benefit realization, and project success group. The sustainability group consists of three pillars: environmental, social, and economical. The second group consists of two subgroups: organization benefit realization and project success. A questionnaire was then developed and distributed to key developers/clients in the United Arab Emirates (UAE) construction industry. The Analytic Hierarchy Process (AHP) was used to determine the weight of the identified selection criteria based on 34 responses. The results show that the sustainability group is more important with a weight of 0.537 compared to the organization benefits and project success criteria with a weight of 0.463. The top six selection criteria include energy use, material use, health and safety, strategic fit, profitability and organizational risk. Three portfolio value optimization models are then developed. Model A combines Project Screening Matrix (PSM) with AHP. Model B is an integrated AHP and Linear Programming (LP) model, while Model C uses Genetic Algorithms (GA). The proposed models can be used to determine the optimum solution based on the organization’s constraints. A real case study is presented to demonstrate the application of the proposed models. The research is valuable as it encourages developers to consider sustainability as key criteria in their portfolio selection, and that, in turn, results in more sustainable construction industry. The research fills an identified gap in the literature and proposes new selection criteria and models.College of EngineeringMultidisciplinary ProgramsPhD in Engineering - Engineering Systems Management (PhD-ESM
Translation as Intercultural Communication: Translation and Commentary
No full textA Master of Arts thesis in English/Arabic/English Translation and Interpreting (MATI) by Isra Al Saabri entitled, “Translation as Intercultural Communication: Translation and Commentary”, submitted in March 2021. Thesis advisor is Dr. Sattar Izwaini. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).This thesis is a translation of “Translation as Intercultural Communication” by David Katan, which comprises chapter five of The Routledge Companion to Translation Studies, edited by Jeremy Munday (2009). The translation is from English to Arabic, followed by a commentary that addresses challenges faced in the process of translating the chapter in terms of register and genre, with a focus on terminology. Newmark’s (1987) translation methods (such as literal and semantic translation procedures, and textual level) were followed as a guideline in the translation to deal with a scholarly/academic-type text. Sixteen terms were identified, arranged according to terms and their Arabic meanings/translations were looked up the Al Mawrid dictionary (2003). The translations of the terms were compared against those that would result following the methods of Newmark (1987), Baker (1992), Munday (2009) and other translation scholars and their strategies. Since the chapter chosen for translation in this thesis is a specialized scholarly/academic text, among the major challenges were factors such as finding appropriate equivalents and standardized terms in Arabic. The analysis of the translations of the sixteen terms showed that recording, studying and analyzing terms during the translation process enhances the quality of the translation.College of Arts and SciencesDepartment of Arabic and Translation StudiesMaster of Arts in English/Arabic/English Translation and Interpreting (MATI
Vigilance Assessment Using EEG and Eye Tracking Data Fusion
No full textA Master of Science thesis in Biomedical Engineering by Nadia Khalil Mohammad Abu Farha entitled, “Vigilance Assessment Using EEG and Eye Tracking Data Fusion”, submitted in April 2021. Thesis advisor is Dr. Hasan Al-Nashash and thesis co-advisors are Dr. Fares Yahya and Dr. Usman Tariq. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).Vigilance describes the ability to maintain alertness while performing a task for a prolonged time. Maintaining vigilance is one of the requirements in many workplaces, especially those that rely on monitoring, such as: surveillance tasks, security monitoring, and air traffic control. These tasks necessitate a specific level of arousal, to provide an acceptable level of cognitive efficiency. Vigilance decrement could result in fatal consequences like accidents, loss of life, and system failure. In this thesis, we investigated the possibility of assessing the vigilance levels using a fusion of Electroencephalography (EEG) and eye tracking data. Vigilance levels are induced by performing a modified version of Stroop Color-Word Task (SCWT) for 30 minutes. Feature-level fusion based on the canonical correlation analysis (CCA) has been employed to enhance the classification accuracy for vigilance level assessment. In the feature level fusion, EEG and eye tracking features are concatenated into a single vector-feature-space and then fed as an input to the Support Vector Machine classifier. The results of the fusion showed that both modalities’ accuracies have been enhanced. The highest accuracy for the fusion was using the EEG Delta band of 96.8± 0.6%, which is higher than using the EEG Delta band without the fusion (88.18±8.5%) or the eye tracking date alone (76.8 ± 8.4 %).College of EngineeringMultidisciplinary ProgramsMaster of Science in Biomedical Engineering (MSBME