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Identifying the Factors Impacting Bridge Deterioration in the Gulf Cooperation Council
No full textThe deterioration module (DM) is one of the four major modules necessary for any bridge management system (BMS). Environmental conditions, structural systems, bridge configuration, geographic location, and traffic data are some of the major factors that affect the development of deterioration modules. This emphasizes the need for the development of deterioration models that reflect the local conditions. In this article, some of the most important factors that could help in developing deterioration models in the Gulf Cooperation Council (GCC) were identified. The research was conducted in three phases; in the first phase, an extensive literature search was conducted to identify factors adopted in different deterioration models, and in phase two, the most relevant factors to the GCC environment were selected and these factors were further reduced based on input from local bridge experts. The result from the second phase is a list of factors identified by the experts. The identified list was utilized in phase three, which was focused on conducting a survey targeting bridge engineers to help identify the final selection and rank the factors according to their importance level. The results indicate that steel reinforcement protection, design load, chloride attack, type of defect, and age are the most important factors impacting bridge deterioration in the GCC. In addition, the time of rehabilitation; average daily truck traffic, ADTT; and average daily traffic, ADT, are the second most important factors. Factors with medium importance level are deck protection, services under the bridge, and inspection gap. The least important set of factors include temperature and wind load
Remaining Shelf-Life Estimation of Fresh Fruits and Vegetables During Transportation
No full textDuring transportation, prediction of the Remaining Shelf-Life (RSL) of Fresh Fruits and Vegetables (FFVs) is critical for planning and quality cost estimation. The Internet of Things (IoT) enables measured environmental variables to be processed in real-time. However, there is a need for a validated, real-time computational method that translates environmental measurements to dynamic RSL estimates. Most existing generic RSL models for FFVs are qualitative, invasive, or static. This study establishes a generic RSL model for FFVs under dynamic and unplanned logistic conditions. The model is based on estimating the current rate of general decay based on the expected respiration rate of the product, and integrating the decay rate with respect to time. Its implementation is non-destructive, non-invasive, and does not require accelerated shelf-life experiments before deployment. In addition, since the original model is rather computationally intensive, a surrogate model was proposed to allow the model to be implemented in fast, real-time applications for ‘Edge IoT.’ Experimental validation of the model using three fresh products (strawberries, apricots, and spinach) in a domestic refrigerator resulted in a maximum deviation of 1.3 days in prediction error using the original model and 2.95 days using the surrogate model. Nonetheless, the predictions made using either the original or surrogate models were statistically sound and not significantly different from the observed shelf lives of the samples, even at the 0.01 significance level.American University of Sharjah Smart City Research Institute Grant SRC-1
Numerical modelling of hyperbolic phase change problems: Application to continuous casting
No full textHeat diffusion processes are generally modeled based on Fourier’s law to estimate how the temperature propagates inside a body. This type of modeling leads to a parabolic partial differential equation, which predicts an infinite thermal wave speed of propagation. However, experimental evidence shows that diffusive processes occur with a finite velocity of thermal propagation in many applications. In this paper, we develop a mathematical formulation to predict the finite speed of heat propagation in multidimensional phase change problems. The model generalizes the enthalpy formulation by adding a hyperbolic term. The governing equations are simulated by the finite element method. The proposed model is first verified by comparing numerical and experimental results illustrating the difference between the infinite and finite propagation velocity for heat inside biological tissues. Then, the results of the two and three-dimensional numerical solution of the continuous steel casting process are presented. We will illustrate that the effects of the initial conditions vanish faster when using the parabolic equation, while they persist in the hyperbolic modeling approach. The results demonstrate significant differences in the initial thermal dynamics and at the solid-liquid interface position when adding the hyperbolic term. The changes are more noticeable in the regions of the steel beam where rapid heat loss and, consequently, faster phase change occur.American University of SharjahNatural Sciences and Engineering Research Council of Canada (NSERC
Biodegradable Magnesium Alloys for Biomedical Implants: Properties, Challenges, and Surface Modifications with a Focus on Orthopedic Fixation Repair
No full textBiomedical devices made from high-modulus and hardness materials play a critical role in enhancing the quality of life for people with bone-related ailments. While these materials have been successfully used in orthopedic applications, concerns including stress-shielding have necessitated the exploration of alternative solutions. An ideal biomedical implant requires a delicate balance of mechanical performance, corrosion resistance, tissue biocompatibility, and other properties such as tribological performance and osseointegration. This review explores the suitability of biodegradable magnesium (Mg) alloys as a promising material for biomedical implants. It delves into the essential properties of biomedical implants, emphasizing the importance of matching mechanical characteristics with human bone properties to mitigate stress shielding. The corrosion properties of implant materials are discussed, highlighting the need for controlled degradation to ensure the safety and longevity of implants. The focus then shifts to the potential of magnesium alloys as biomedical implants, examining their benefits, limitations, and the challenges associated with their high degradation rates and less-than-satisfactory mechanical properties. Alloying with elements such as aluminum, zinc, and others is explored to improve magnesium alloys’ mechanical performance and corrosion resistance. Furthermore, this review discusses surface modification techniques, including chemical conversion coatings and biomimetic deposition, as effective strategies to enhance the corrosion resistance and biocompatibility of magnesium and its alloys. These modifications offer opportunities to improve the long-term performance of magnesium-based biomedical implants. This review provides a comprehensive overview of the properties, challenges, and potential solutions associated with biodegradable magnesium alloys as a promising material for biomedical implants. It underscores the importance of addressing problems related to mechanical performance, corrosion resistance, and biocompatibility to advance the development of safe and effective biomedical implant materials.Dana Gas Endowed Chair for Chemical EngineeringAmerican University of SharjahSheikh Hamdan Award for Medical SciencesFriends of Cancer Patients (FoCP
The Impact of Digital Technology on Creating Virtual Environment in the AEC Industry
No full textA Master of Science thesis in Construction Management by Omar Hesham Elrefaey entitled, “The Impact of Digital Technology on Creating Virtual Environment in the AEC Industry”, submitted in April 2023. Thesis advisor is Dr. Sameh El-Sayegh. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).The construction industry has been incorporating technology over the last two decades, albeit gradually, as ‘technology-push’ continues to overcome traditional passivity typical in the sector. Advanced technological tools are crucial to generate a simulated virtual environment that allows for better collaboration, communication and data processing which ultimately leads to less errors and more successful outcomes. The objective of this thesis research is to investigate how digital technology is making headway in the construction industry because of COVID-19. Particularly, the study aims to investigate the extent of use of technology in three periods – pre-COVID, during-COVID and post-COVID. The second objective of this thesis is to examine which digital technology tools impact the virtual environment within an Architecture, Engineering, Construction (AEC) firm the most. For this research, digital technology tools are divided into three groups: data acquisition, processing, and communication. The methodology involved conducting two questionnaire surveys among the construction professionals in the UAE. The first survey’s results show the increasing level of usage of digital technology in the AEC industry from pre-COVID, to during COVID and post-COVID periods. Among the three categories, communication technology indicated a higher extent of use as compared to the other two. It was also noticed that there was a slight drop in the use of communication technology from during COVID to post-COVID time, apparently as some of the functions and operations are expected to return to normalcy after the pandemic. In relation to the contribution of digital technologies to the virtual environment, the second survey’s results were analyzed using AHP and found that the most significant digital technology level with the highest impact on enhancing the virtual environment is BIM level 3. While the digital technology level that was the least significant was data collection level 1 (manual/paper-based). Furthermore, the results also revealed that 23% of the companies studied in this research displayed a low virtual environment level (10-40%). While 50% of the companies included in this research displayed a medium virtual environment level (40-70%) and 27% of the companies displayed a high virtual environment level in their construction projects (70-100%).College of EngineeringMultidisciplinary ProgramsMaster of Science in Construction Management (MSCM
Evaluation of Administrator and Teacher Perspectives on Intercultural Competence Across UAE Schools
No full textA Master of Arts thesis in Teaching English to Speakers of Other Languages (TESOL) by Aisha Ali Alowais entitled, “Evaluation of Administrator and Teacher Perspectives on Intercultural Competence Across UAE Schools", submitted in April 2023. Thesis advisor is Dr. Rachel Hall Buck. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).This study explored the concept of Intercultural Competence (IC) and teacher training programs across private schools in the UAE within the emirates of Sharjah and Ajman. The data collection methods consisted of surveys and semi-structured interviews directed towards a wide range of teaching professionals. The methods were utilized to explore the different perspectives and experiences to determine the existing pedagogical challenges in multicultural classrooms and suggest areas for improvement. The evidence from this study suggests that although many schools conduct teacher training programs for faculty, they must begin to shift the focus of their professional development to more global issues such as building IC skills and learning about the different cultures within their respective communities. It is recommended for both administrators and teachers to connect with parents and form joint collaborations in order to increase cultural sensitivity. It is also recommended for non-Emirati staff to be provided with sufficient training and orientation about the UAE culture. Overall, promoting IC in a diverse school community would promote a sense of openness and respect amongst students.College of Arts and SciencesDepartment of EnglishMaster of Arts in Teaching English to Speakers of Other Languages (MA TESOL
Design-Construction Interface Problems in Sustainable Construction Projects in the UAE
No full textA Master of Science thesis in Construction Management by Dana Al Qasem entitled, “Design-Construction Interface Problems in Sustainable Construction Projects in the UAE”, submitted in November 2023. Thesis advisor is Dr. Sameh El-Sayegh. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).unique demands of sustainable construction projects, necessitating distinct management techniques, specialized materials, and novel building practices, present challenges in efficiently navigating project scope, time, and cost. High cooperation among key stakeholders of sustainable construction projects is considered critical for project success, which is often hindered by design-construction interface problems. These problems arise due to the increased complexity in the design stage and the diversity of requirements, activities, agents, and tools related to sustainability. In this research, interface is defined as the relationship between two interdependent project phases carried out by two different organizations. While several research studies have examined the problems related to the design-construction interface, none has specifically focused on sustainable construction projects. Therefore, this research aims to identify and assess design-construction interface problems in sustainable construction projects in the United Arab Emirates (UAE). Twenty-five design-construction interface problems were identified through extensive literature review. To assess these design-construction interface problems, a survey was distributed among the UAE sustainable construction stakeholders, where sixty-three responses were collected. The survey data was then analyzed using the Relative Importance Index (RII). Additionally, the Spearman’s rank correlation coefficient was applied to evaluate the strength of relationships amongst the different stakeholders and between local and international companies. The results of the study indicate that the most significant interface problems in sustainable construction projects of the UAE include “change orders” (RII of 16.65), “lack of proper coordination between various disciplines of the design team” (RII of 15.94), “extensive and slow decision-making process” (RII of 15.02), “material changes during the construction phase” (RII of 14.56), and “poorly written contracts” (RII of 14.38). Among the provided recommendations, the enhancement of communication and collaboration among the construction parties through the shift towards the integrated project delivery method is emphasized. This research fills the identified research gap and provides the UAE sustainable construction practitioners with the most significant design-construction interface problems.College of EngineeringMultidisciplinary ProgramsMaster of Science in Construction Management (MSCM
Design and evaluation of a sustainable solar based combined cycle for multi-output generation in UAE
No full textA Master of Science thesis in Mechanical Engineering by Hamda Ali Alkhadar entitled, “Design and evaluation of a sustainable solar based combined cycle for multi-output generation in UAE”, submitted in April 2023. Thesis advisor is Dr. Mohammad O. Hamdan and thesis co-advisor is Dr. Sameer Al-Asheh. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).This thesis aims to design a sustainable solar-based combined power cycle integrated with subsystems to produce multiple outputs, such as potable water, power output, and hydrogen gas for the UAE. For this purpose, a thermo-economic comparative analysis involving two proposed integrated systems is performed. The thermo-economics comparative analysis is employed to determine the best proposed system with the highest performance while it is economically competitive. In this thesis, solar tower (ST) technology is selected since it has been well developed as compared with other concentrated solar power (CSP) technologies. The study offers integrated systems that are capable of producing the required power and water outputs that satisfies the country needs and are aligned with the 2050 UAE energy strategy. The main target of this strategy is to increase the solar energy share to reach 44% of power generation in the UAE. The first proposed system consists of SOFC with a combined cycle, and two water desalination technologies (reverse osmosis (RO) and multi-effect desalination (MED)). The second proposed system consists of ST with combined cycle, solid oxide fuel cell (SOFC), and two water desalination technologies (RO and MED). The main outcome of this thesis is to produce a reliable detailed thermo-economics analysis that allows selecting the optimum system as well as modes of operation. The expected power capacity for the first proposed system exceeds 380 MW, while water production is around 18000 ᵌ/day. Whereas the expected power capacity for second proposal exceeds 420 MW, while water production is around 15000 ᵌ/day. The levelized costs of electricity and water are determined using the life-cycle assessment. The levelized cost of electricity (LCOE), water by RO (LCOW/RO), and water by MED (LCOW/MED for the first system without integrating solar energy are 0.383/ ᵌ and 0.135/kwh, 0.14/ᵌ.College of EngineeringDepartment of Mechanical EngineeringMaster of Science in Mechanical Engineering (MSME
Development and performance analysis of substrates coated with metal-organic framework for gas sensing applications
No full textA Master of Science thesis in Mechanical Engineering by Shamma Saqer Ibrahim Al Abdulla entitled, “Development and performance analysis of substrates coated with metal-organic framework for gas sensing applications”, submitted in April 2023. Thesis advisor is Dr. Mehdi Ghommem and thesis co-advisor is Dr. Rana Sabouni. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).This thesis investigates the potential use of Zeolitic Imidazolate Frameworks (ZIF-8) as a sensing material for CO2 detection. Three synthesis techniques namely room temperature, microwave-assisted, and ball milling were explored for the preparation of ZIF-8. The latter is a green and facile alternative for synthesis with its solvent-free, room temperature operation. In addition, ZIF-8 samples produced through ball milling exhibited excellent CO2 adsorption and detection characteristics, as confirmed by fluorescence measurements. To understand the structural morphology, the thermal stability, and elements content of the different ZIF-8 samples, a range of characterization tests including XRD, FTIR, TGA, FE-SEM and EDS were conducted The characterization tests revealed the formation of a new phase of ZIF-8 (ZIF-L) when deploying the ball milling technique with different structure, morphology, response to CO2 exposure and thermal stability compared to its counterparts. The ZIF-8 samples obtained from the different ZIF-8 samples were evaluated in terms of limit of detection (LOD), selectivity, and recyclability using fluorescence measurements. The ZIF-8 sample synthesized based on ball milling had a LOD of 815.2 ppm, while the LODs of samples obtained from microwave and room temperature-based synthesis techniques were 1780.6 ppm and 723.8 ppm, respectively. This shows that the room temperature and ball milling produced MOFs with comparable LODs. However, the room temperature procedure requires the use of methanol, a harmful solvent. The range of LOD demonstrates the suitable use of ZIF-8 for indoor air quality monitoring and other industrial applications. Finally, the ZIF-8 obtained from ball milling was coated on a substrate using ball milling at different milling speeds 100 rpm, 300 rpm and 500 rpm. The 300 rpm sample resulted in a favorable coating and CO2 adsorption, thus, making it suitable to be deployed as a sensing layer for a miniature gas sensor.College of EngineeringDepartment of Mechanical EngineeringMaster of Science in Mechanical Engineering (MSME
A user experience perspective on heritage tourism in the metaverse: Empirical evidence and design dilemmas for VR
No full textThe tourism industry will be shaped by the growth and development of the metaverse in the coming decades. Virtual reality (VR) will enable the creation of virtual worlds, avatars, digital twins, and new social networks. These technologies can be utilized in tourism to enable travelers to preview real-world experiences, to enhance experiences while on-site, to relive experiences after travel, or in some cases to even substitute for travel. Given the metaverse’s transformative potential, empirical investigation of VR is clearly warranted. Studies of VR tourism typically choose a single specific VR application and investigate its impact on adoption or user satisfaction. This application-level focus is a significant limitation. We therefore evaluate multiple heritage tourism applications as well as VR hardware in a comprehensive and structured analysis from the user experience (UX) perspective. Our content analysis of user interviews reveals 13 factors that shape users’ overall perceptions about VR. These factors are grouped into categories related to presentation of the VR content, the content itself, and the functionality of the hardware and software. Our analysis also reveals three design dilemmas for creators of VR heritage tourism content for the metaverse. Implications and an agenda for future research are included.American University of Sharja