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Environmental Footprint and Economics of a Full-Scale 3D-Printed House
No full text3D printing, is a newly adopted technique in the construction sector with the aim to improve the economics and alleviate environmental impacts. This study assesses the eco-efficiency of 3D printing compared to conventional construction methods in large-scale structural fabrication. A single-storey 3D-printed house was selected in the United Arab Emirates to conduct the comparative assessment against traditional concrete construction. The life cycle assessment (LCA) framework is utilized to quantify the environmental loads of raw materials extraction and manufacturing, as well as energy consumption during construction and operation phases. The economics of the selected structural systems were investigated through life cycle costing analysis (LCCA), that included mainly the construction costs and energy savings. An eco-efficiency analysis was employed to aggregate the results of the LCA and LCCA into a single framework to aid in decision making by selecting the optimum and most eco-efficient alternative. The findings revealed that houses built using additive manufacturing and 3D printed materials were more environmentally favourable. The conventional construction method had higher impacts when compared to the 3D printing method with global warming potential of 1154.20 and 608.55 kg CO2 eq, non-carcinogenic toxicity 675.10 and 11.9 kg 1,4-DCB, and water consumption 233.35 and 183.95 m3, respectively. The 3D printed house was also found to be an economically viable option, with 78% reduction in the overall capital costs when compared to conventional construction methods. The combined environmental and economic results revealed that the overall process of the 3D-printed house had higher eco efficiency compared to concrete-based construction. The main results of the sensitivity analysis revealed that up to 90% of the environmental impacts in 3D printing mortars can be mitigated with decreasing cement ratios.American University of Sharja
Critical Review of the Evolution of Project Delivery Methods in the Construction Industry
No full textSelecting the appropriate project delivery method (PDM) is a very significant managerial decision that impacts the success of construction projects. This paper provides a critical review of related literature on the evolution of project delivery methods, selection methods and selection criteria over the years and their suitability in the construction industry of todayβs world. The literature review analysis has concluded that project delivery methods evolve at a slower rate compared to the evolution of the construction industry. The paper also suggests features of an evolved project delivery method that is digitally integrated, people-centered, and sustainability-focused. Moreover, the paper highlights the latest selection criteria such as risk, health and wellbeing, sustainability goals and technological innovations. Furthermore, the paper concluded that advanced artificial intelligence techniques are yet to be exploited to develop a smart decision support model that will assist clients in selecting the most appropriate delivery method for successful project completion. Additionally, the paper presents a framework that illustrates the relationship between the different PDM variables needed to harmonize with the construction industry. Last, but not least, the paper fills a gap in the literature as it covers a different perspective in the field of project delivery methods. The paper also provides recommendations and future research ideas.American University of Sharja
Detecting Double and Triple Compression in HEVC Videos Using the Same Bit Rate
No full textDigital video forensics refers to the process of analysing, examining, evaluating and comparing a video for use in legal matters. In digital video forensics, the main aim is to detect and identify video forgery to ensure a videoβs authenticity. When a video is edited, the original bitstream is first decoded, edited and then re-compressed. Therefore detecting re-compression in videos is a major step in digital video forensics. Video editing can be applied many times leading to multiple compressions. Thus, finding out the compression history of a video becomes an important mean for detecting any manipulation and thereby identifying the legitimacy of a video. In this work, we propose a machine learning approach to detecting double and triple compression in videos coded using the High Efficiency Video Coding (HEVC) format. Feature variables are extracted from Coding Units (CUs) and summarized into picture and Group of Pictures (GoP) feature vectors. Two classifiers are used for classifying videos into single, double and triple compression, namely; Random Forest (RF) and bi-directional Long Short-Term Memory (bi-LSTM). The latter classifier is important in digital video forensics as it exploits the temporal dependencies between feature vectors. In the experimental results, 127 video sequences are used for verifying the accuracy of the proposed solutions. Results are reported in terms of classification accuracy, confusion matrices, precision and recall. The experimental results revealed that both double and triple compression can be accurately detected using the proposed solutions with results superior to existing work
Efficiency of semi-implicit alternating direction implicit methods for solving cardiac monodomain model
No full textIt is well known that numerical simulations of the cardiac monodomain model require fine mesh resolution, which increases the computational resources required. In this paper, we construct three operator-splitting alternating direction implicit (ADI) schemes to efficiently solve the nonlinear cardiac monodomain model. The main objective of the proposed methods is to reduce the computational time and memory consumed for solving electrocardiology models, compared to standard numerical methods. The proposed methods have second-order accuracy in both space and time while evaluating the ionic model only once per time-step. Several examples using regular wave, spiral wave reentry, and nonsymmetrical scroll wave are conducted, and the efficiency of the proposed ADI methods is compared to the standard semi-implicit CrankβNicolson/AdamsβBashforth method. Large-scale two- and three-dimensional simulations are performed.American University of Sharja
Monitoring Bone Density Using Microwave Tomography of Human Legs: A Numerical Feasibility Study
No full textA major cause of bone mass loss worldwide is osteoporosis. X-ray is considered to be the gold-standard technique to diagnose this disease. However, there is currently a need for an alternative modality due to the ionizing radiations used in X-rays. In this vein, we conducted a numerical study herein to investigate the feasibility of using microwave tomography (MWT) to detect bone density variations that are correlated to variations in the complex relative permittivity within the reconstructed images. This study was performed using an in-house finite-element method contrast source inversion algorithm (FEM-CSI). Three anatomically-realistic human leg models based on magnetic resonance imaging reconstructions were created. Each model represents a leg with a distinct fat layer thickness; thus, the three models are for legs with thin, medium, and thick fat layers. In addition to using conventional matching media in the numerical study, the use of commercially available and cheap ultrasound gel was evaluated prior to bone image analysis. The inversion algorithm successfully localized bones in the thin and medium fat scenarios. In addition, bone volume variations were found to be inversely proportional to their relative permittivity in the reconstructed images with the root mean square error as low as 2.54. The observations found in this study suggest MWT as a promising bone imaging modality owing to its safe and non-ionizing radiations used in imaging objects with high qualityAmerican University of Sharja
Building A Passive Thermal Management System Using Phase Change Material Embedded In Porous Media
No full textA Master of Science thesis in Mechanical Engineering by Mohammed H. A. Azzam entitled, βBuilding A Passive Thermal Management System Using Phase Change Material Embedded In Porous Mediaβ, submitted in December 2021. Thesis advisor is Dr. Mohammad O. Hamdan. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).This work aims to investigate the heat transfer effectiveness of different phase change materials (PCMs) when infused in plate-based heatsinks with a fixed volume fraction of thermal conductivity enhancer (TCE). Moreover, this work examines the impact of a metallic wire mesh infused with PCM. The metallic wire mesh is modeled using porous media theory. The study is conducted using numerical simulation via a commercial tool (ANSYS-Fluent). The PCMβs ability to absorb and release large amounts of thermal energy at constant temperature is a desired feature in transient electronics cooling. During electronics operation, large amounts of heat are generated. Improper dissipation of this heat causes electronics to overheat. Overheating causes a decrease in the performance, reliability, and life expectancy of these devices. Heatsinks integrated with PCMs offer a prospective cooling solution for transient high-performance electronics such as aircraft electric switches and computer processors. Peak usage of aircraft electrical switches occurs during aircraft takeoff and landing, which produces large amounts of heat in a short time. This rapid heat release is responsible for most aircraft electrical fires. As the aerospace industry evolves toward fully electric aircraft and electronics become more compact, undesired heat generation is growing dramatically and needs to be thermally mitigated. This study begins by examining 2-D models of heatsinks filled with different PCMs. These models are a heatsink with no fins, a plate-fin heatsink with two fins, and a plate-fin heatsink with four fins. These heatsinks are examined for three PCMs: Salt Hydrate, Paraffin Wax, and RT35. Next, a wire mesh infused with a PCM is examined to understand the impact of wire-mesh porosity and permeability on the transient thermal performance of a PCM heatsink.College of EngineeringDepartment of Mechanical EngineeringMaster of Science in Mechanical Engineering (MSME
Why Immigrant Entrepreneurs are More Prone to Exit than Non-Immigrant Entrepreneurs?
No full textDue to various cultural and social barriers, immigrant entrepreneurs are considered more vulnerable to external shocks than their non-immigrant counterparts. The Covid-19 pandemic has exacerbated the plight and pushed immigrant entrepreneurs into a more precarious situation. This study focuses on immigrant entrepreneurs as a unit of analysis and seeks to explain why and how immigrant entrepreneurs exit their businesses, how they perform differently from non-immigrant entrepreneurs, and what role culture might play in the entrepreneurial exit process. Drawing on a social psychology perspective, the Theory of Planned Behaviour, the concepts of self-construals and extant research, the study develops a research framework to facilitate the understanding of immigrant entrepreneurial exit. The study argues that immigrant entrepreneursβ exit intention and behaviour are primarily determined by their exit attitude, subjective norms, and perceived behavioural control, whereas independent and interdependent self-construals that reflect oneβs cultural orientations play an important moderation role between the three hypothetical determinants and exit intention. Covid-19 impact also plays an important role in influencing exit intentions. The study advances research on this largely underexplored area of immigrant entrepreneurial exit through mapping a research agenda for future research. The study also holds broader implications for public policy development, as discussed in the paper
βWhat Was Meant to Beβ Versus βWhat Might Have Beenβ: Effects of Culture and Control on Counterfactual Thinking
No full textCounterfactual thinking is a ubiquitous feature of daily life with links to causal reasoning. Therefore, we argue that cultures that vary in perceptions of what controls important life outcomes may also vary in counterfactual thought. Investigating White American and United Arab Emirates-based Arab participants' counterfactual potency and spontaneous counterfactual thinking, we found that Arab participants endorsed counterfactual thoughts less than White Americans, and were unaffected by the routine nature of action when negative outcomes were severe. Differences in counterfactual endorsement in response to severe negative outcomes were linked to greater beliefs in divine control and fate in Arab participants, and not to religiosity, reinforcing an important role of perceptions of control in counterfactual thought. However, although reporting less counterfactual endorsement overall, Arabs showed a similar pattern of counterfactual thought to White Americans when negative outcomes were mild, or when reporting spontaneous thought. Arabs likewise showed a similar pattern of regret as White Americans regardless of event severity, reporting more regret when outcomes resulted from unusual action. These patterns suggest a dissociation between affect and cognition, and between what kind of outcomes are subject to counterfactual scrutiny in Arab participants.American University of Sharja
Membrane bioreactor for wastewater treatment: A review
No full textDue to the growth in the human population globally, it is noted that various industries have also grown. The need for an excess supply of water and the generation of high effluent quality upon proper treatment technologies has become a necessity. These two crucial needs can be achieved with the aid of membrane bioreactor (MBR) that has been proven to be effective in removing organic and inorganic matters as a biological unit for wastewater treatment. MBR plants are created by integrating the biological process with membrane filtration which possesses numerous benefits if compared with conventional methods such as activated sludge; MBR is widely used for municipal and industrial wastewater treatment. This review addresses basic concepts of MBRs plants and subsequently provides information on the recent developments of each part related to MBR plants. The characteristics of the bioreactor treatment process is discussed in detail, and then a comprehensive review of the membrane separation process is examined. The fouling phenomena as a main obstacle to widespread MBRs plant is presented in detail with recent fouling mitigation methods. The efforts of a number of novel MBR processes are summarized. In order to tackle the existing limitation of MBRs to be practical on a larger scale, the existing challenges and future research efforts are proposed.American University of Sharja
A Procedure for Optimizing the Location of Electric Vehicle Charging Stations
Get PDFA Master of Science thesis in Civil Engineering by Abdullah Waleed Aljuboori entitled, βA Procedure for Optimizing the Location of Electric Vehicle Charging Stationsβ, submitted in December 2021. Thesis advisor is Dr. Akmal Abdelfatah. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).The emission of harmful gasses is increasing due to the significant increase in the number of vehicles, which poses a problem for public health. To improve environmental conditions, countries must start planning and encouraging the use of electric vehicles (EVs). However, before the widespread adoption of electric vehicles, charging stations need to be planned to meet the charging needs of electric vehicles. These charging stations need to be placed at various locations to serve the maximum number of electric vehicles without significant delays. Such service will encourage the use of electric vehicles to perform daily trips. In this thesis, the simulation software DYNASMART (Dynamic Network Assignment Simulation for Road Telematics) was utilized to simulate different percentages of electric vehicles within the traffic stream. In order to simulate EVs in DYNASMART, different modifications and two main components were coded. The modifications included adding EVs and their parameters to the code, the charging parameters, and modifying the code to track the battery charge level. For the components, a subroutine to select a charging station was coded. Also, a component to consider the process inside the charging station was coded. This component needs to keep track of the number of occupied and unoccupied charging units, charging time, expected waiting time for vehicles arriving at the charging station, etc. Additionally, an optimization model was developed to optimize the number and location of electric vehicle charging stations. The problem considers a predefined number of possible locations of charging stations. The optimization procedure will determine the best location for the minimum number of charging stations to minimize the total cost of constructing the stations and the value of waiting and charging times. The developed optimization model is a complex problem that cannot be solved for the exact solution. Thus, solution procedures were developed and tested under different traffic congestion levels and different EV percentages in the traffic flow. The results showed an average reduction of about 50% to 90% based on the traffic congestion level and the percentage of EVs in the traffic flow.College of EngineeringDepartment of Civil EngineeringMaster of Science in Civil Engineering (MSCE