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Recent progress and challenges of adsorptive membranes for the removal of pollutants from wastewater. Part II: Environmental applications
No full textAdsorptive membranes have attracted attention recently and have been employed to remove variety of pollutants from wastewater. Part I of this work was devoted to provide an overview on the latest progress in their fabrication techniques. This part is devoted to review the studies performed towards environmental applications. Adsorptive membranes were used to remove pollutants such as dyes, heavy metals, and pharmaceuticals. The major findings of this review include presenting the various benefits associated with the use of adsorptive membranes in micro-pollutants removal from water samples and discussing the potential utilization of bio-adsorbents such as chitosan. While adsorptive membranes proved their effectiveness in removing several pollutants, they still however, suffer from various drawbacks and challenges on a large scale implementation. These drawbacks include the low adsorption capacity, the cost, reusability and fouling. Finally, the paper concludes that exploiting adsorptive membranes in the removal of emerging pharmaceutical compounds in particular have not yet been researched extensively in the literature and more efforts should be focused in this direction.American University of Sharja
Finite Element Analysis of Machining Lightweight Syntactic Foams
No full textA Master of Science thesis in Mechanical Engineering by Kevin Koshy Thomas entitled, “Finite Element Analysis of Machining Lightweight Syntactic Foams”, submitted in April 2021. Thesis advisor is Dr. Sathish Kannan. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).Aluminium alloys reinforced with hollow alumina microsphere syntactic foams possess superior physical and mechanical properties such as improved stiffness, peak compressive strength and total specific energy absorption. However, due to the inherent abrasive and brittle nature of the hollow alumina microspheres, syntactic foams bring two key machining issues in the form of poor machinability and surface integrity. This research focuses on understanding the physics behind chip formation during machining metal syntactic foams through development of a 2D finite element (FE) model which will enable to predict cutting forces using AdvantEdge FE software. To elucidate and explain the failure mechanisms in the form of hollow ceramic microsphere fracture and plastic deformation of the aluminium matrix which contributes to generation of cutting forces, a 2D ABAQUS/Explicit FE model is developed. Cutting tests were conducted on the aluminium syntactic foam with varying cutting velocity and undeformed chip thickness. Two different volume fractions (10% and 20%) with varying average hollow microsphere sizes were used in the validation trials. From the FE results, it is shown that the increase in cutting speed results in reduction of cutting force due to thermal softening of matrix alloy. However, the measured cutting force increase with increasing undeformed chip thickness is primarily due to increasing chip load. Increase in shear strength of the material is noticed with increasing volume fraction and finer hollow microsphere size which contributes to a higher magnitude of cutting force. A greater number of fractured hollow microspheres were involved in two-body and three-body tool abrasion on the rake face thereby increasing the cutting force. The finite element cutting force simulations is compared with the measured values for different cutting conditions. The AdvantEdge FE model shows comparable results with the validation experiments within an error of 15%.College of EngineeringDepartment of Mechanical EngineeringMaster of Science in Mechanical Engineering (MSME
Effects of Autonomous Vehicles on the Signalized Intersections’ Performance
No full textA Master of Science thesis in Civil Engineering by Mahmoud Atef Noaman entitled, “Effects of Autonomous Vehicles on the Signalized Intersections’ Performance”, submitted in July 2021. Thesis advisor is Dr. Akmal Abdelfatah. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).Traffic congestion is one of the main problems facing major urban cities around the world. Traffic delays at traffic signals are causing significant loss of productive time. The introduction of Autonomous Vehicles (AVs) has opened the door for possible advancements in the area of transportation engineering. One of the major challenges facing the implementation of such technology is undoubtedly the interaction between AVs and Human Driven Vehicles (HDVs). In this thesis, the impacts of AVs as well as HDVs on traffic signals were examined in a mixed system. The evaluation considers different traffic congestion levels, different distribution of the total traffic on the intersection approaches, different turning percentages on each approach, and different percentages of AVs in the traffic flow. Hence the impact of AVs will be studied at 0%, 20%, 40%, 60%, 80% and 100% market penetration rate (i.e. the percentage of AVs out of the total traffic). The total traffic on intersections was considered at values of 5000, 6000, and 7000 veh/hr. The distribution of traffic on the approaches considers equal distribution on all the approaches or the dominant traffic to be on two opposing directions. The left turn percentage on the main approach is considered as 15%, 30%, and 45%. The traffic signal optimization software Synchro is used to optimize signal timing for each traffic condition when considering 0% AVs. The well-known microsimulation package Vissim is used to simulate different traffic scenarios under different AVs penetration rates. It is concluded that AVs could reduce intersection delay proportionally with increase in market penetration rates. The maximum average delay reduction was 60%, which occurred at 7000 vph and 30% left turn at a penetration rate of 100% AVs. The magnitude of the delay improvement depends mainly on the traffic condition and the percentage of AVs used. The benefits from AVs are lowered significantly at oversaturated conditions and where left turn movement is beyond the left turn lane capacity. The combination between high left turn movement, imbalance distribution of traffic and high total traffic volume resulted in the lowest improvement rate with values of about 1% only in some cases.College of EngineeringDepartment of Civil EngineeringMaster of Science in Civil Engineering (MSCE
Sliding Resistance of Serrated-Base Quay Walls
No full textA Master of Science thesis in Civil Engineering by Maryam Omran Jaroor entitled, “Sliding Resistance of Serrated-Base Quay Walls”, submitted in November 2021. Thesis advisor is Dr. Magdi El-Emam. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).Waterfront retaining structures, such as quay walls, play important roles in the safety and operation of ports and harbours. Designing waterfront structures under critical loads and conditions is one of the important topics of geotechnical research and coastal engineering. Block type gravity quay walls are the mostly used type, which consists of massive concrete blocks stacked on top of each other and setting on a foundation layer of gravel or crushed stone. While extensive studies are conducted on quay wall design, both numerically and experimentally, there is a gap on the design criteria adopted of serrated bases quay wall. The current design standard assumes a coefficient of friction µ=tan(soil friction angle) for serrated base wall instead of µ=tan(soil friction angle/2) in case of non-serrated base. This assumption is not supported by neither theoretical nor experimental analysis. Therefore, adopting this assumption for walls with serrated base might lead to a conservative or unsafe stability analysis of quay walls. The current research work attempts to tackle this gap, through analytical analysis and numerical modelling. The main objective of this research is to study and analyse the behaviour of concrete block type quay wall with different base configurations (serrated vs. non-serrated). To achieve this purpose, analytical and numerical models have been developed to investigate the sensitivity of the normalized equivalent base friction angle to different serration design parameters. The analytical model is driven based on the Coulomb’s passive earth pressure theory for cohesionless soil. However, the numerical model is developed using PLAXIS commercial software. The numerical and analytical models was used to conduct parametric study to investigate the effect of different variables such as serration height, number, and inclination, on quay wall sliding resistance. A combination of analytical and numerical results indicates that the design values of serrated base friction, used currently, are highly conservative. In addition, the sliding resistance of serrated-base quay walls can be significantly improved by using specific combination of serration design parameters (height, angle and number per meter). Results of this research is useful for design codes, municipalities and other agencies dealing with gravity type blocks quay walls.College of EngineeringDepartment of Civil EngineeringMaster of Science in Civil Engineering (MSCE
Recent progress and challenges on adsorptive membranes for the removal of pollutants from wastewater. Part I: Fundamentals and classification of membranes
No full textThe development of novel wastewater reuse technologies appears to be a thriving area of research. Adsorptive membranes are considered among the promising technologies that exhibited efficiency and competence in water reuse. They have the potential of removing different types of emerging pollutants from wastewater that cannot be removed via conventional methods. These membranes are attractive because of the dual advantage of adsorption/filtration mechanisms and by virtue of their various types and configurations. The use of adsorptive membranes tackles several issues including fouling, process cost, adsorbent regeneration, adsorption capacity, membrane permeability, rejection rates, and selectivity. This review is devoted to discussing adsorptive membranes and their fabrication techniques, as well as presenting their various types and classifications. The challenges associated with their application are also reviewed. Their classifications can be established based on either the type of the adsorbent used or their polymers matrix. The major challenges are fouling and identifying the right filling materials. The review also identified the great potential of using these membranes in removing emerging pollutants.American University of Sharja
Maximum principles and overdetermined problems for Hessian equations
No full textIn this article we investigate some Hessian type equations. Our main aim is to derive new maximum principles for some suitable P-functions, in the sense of L.E. Payne, that is for some appropriate functional combinations of u(x) and its derivatives, where u(x) is a solution of the given Hessian type equations. To find the most suitable P-functions, we first investigate the special case of a ball, where the solution of our Hessian equations is radial, since this case gives good hints on the best functional to be considered later, for general domains. Next, we construct some elliptic inequalities for the well-chosen P-functions and make use of the classical maximum principles to get our new maximum principles. Finally, we consider some overdetermined problems and show that they have solutions when the underlying domain has a certain shape (spherical or ellipsoidal).American University of Sharja
An economic analysis of gas pipeline trade cooperation in the GCC
No full textNatural gas plays an important role in the global energy system. Thus, optimizing trade in natural gas is a key concern for many countries. This study investigates the value of expanding the Gulf Cooperation Council's (GCC) natural gas grid. We consider the documented successes and failures of the regional gas trade in Europe and Asia and weigh them against a GCC case study. The case study uses a partial equilibrium model of energy production, trade and demand calibrated to 2018 conditions to assess regional pipeline gas trade opportunities. The model incorporates parameters that are relevant to energy policy issues, including fuel allocation and energy price reforms. We also incorporate the regional liquified natural gas (LNG) trade strategy of Qatar, a regional and global leader in LNG production and exports. We find that pipeline gas trade cooperation in the GCC can contribute up to $3.1 billion to the regional economy by reducing transportation costs. More accessible gas offers a substitute for liquid fuel consumption and can offset the opportunity costs of using domestic oil to meet domestic energy demands. We also investigate the influence of an integrated gas market and price reforms on the power trade along the GCC interconnector
Data-Driven Detection of Electricity Theft Cyberattacks in PV Generation
No full textMost of the existing research focuses on electricity theft cyber-attacks in the consumption domain. On the contrary, a high penetration level of distributed generators (DGs) may result in increased electricity theft cyber-attacks in the distributed generation domain, which is the focus of this paper. In these attacks, malicious customers can hack into the smart meters monitoring their DG units, which are usually photovoltaic (PV), and manipulate their readings to report higher injected energy to the grid and claim more profit under feed-in tariff programs. This paper proposes a data-driven approach based on machine learning to detect such thefts. We adopt an anomaly detection approach where a theft detection unit (TDU) based on a regression tree model is designed to detect suspicious data. Historical records of solar irradiance, temperature, and smart meter readings are utilized in the training stage of the detector. The probability density function of the error between the actual readings from DG meters and the predicted generation by the regression model is utilized as a metric to detect suspicious data. Several theft scenarios are used to assess the performance of the TDU. Furthermore, a comparison study with other detectors is presented to demonstrate the superiority of the proposed TDU.American University of SharjahDubai Electricity and Water Authorit
Maximum-Service Channel Assignment in Vehicular Radar-Communication
Get PDFSpectrum sharing between different technologies has become a necessity as the RF spectrum has become more congested than ever due to the increasing number of connected devices and applications all wishing to access the spectrum simultaneously. Vehicular networks are one of many scenarios of spectrum sharing as vehicles are expected to share the same spectrum for radar sensing and communication purposes. Channel assignment among radar sensors and communication transceivers in automotive systems is crucial for the success of future vehicular networks. This paper proposes an optimization framework for the channel assignment to multiple automotive radars and communication transceivers aiming at maximizing the number of served vehicles under hard quality of service requirements. The channel assignment problem is formulated as an integer linear optimization with binary variables. A heuristic solution that is based on ordered sequential channel assignment (OSCA) is proposed and is shown to achieve at least 92% of the solution obtained from branch-and-cut based techniques with much less computational complexity and run-time; at most 2% of the run-time of branch-and-cut.American University of SharjahNational Science Foundatio
Cultural Tourism through the Lens of the Stereoscope: Underwood & Underwood’s Egypt, a 1905 Stereoview Boxed Set, Considered
No full textUsing the framework of the tourist gaze to investigate Underwood & Underwood’s Egypt, a 1905 stereoview boxed set with an accompanying book by James Henry Breasted, which is part of a larger collection of stereoview boxed sets by the same company, this paper will define the tourist gaze, provide a brief overview of Underwood & Underwood’s stereoview boxed sets, and examine how Egypt and its cultural heritage are perceived through an outsider’s orientation and set of values as well as the ramifications of this perception. This will be accomplished by focusing on Breasted’s textual depictions of the contemporary Egyptian at the beginning of the twentieth century in the set’s accompanying book, Egypt through the Stereoscope, and included on some of the back sides of the stereoviews in the Egypt set