Optimal sizing of hybrid renewable energy systems: an application for real demand in Qatar remote area

Renewable energy (RE) sources are becoming popular for power generations due to advances in renewable energy technologies and their ability to reduce the problem of global warming. However, their supply varies in availability (as sun and wind) and the required load demand fluctuates. Thus, to overcome the uncertainty issues of RE power sources, they can be combined with storage devices and conventional energy sources in a Hybrid Power Systems (HPS) to satisfy the demand load at any time. Recently, RE systems received high interest to take advantage of their positive benefits such as renewable availability and CO2 emissions reductions. The optimal design of a hybrid renewable energy system is mostly defined by economic criteria, but there are also technical and environmental criteria to be considered to improve decision making. In this study three main renewable sources of the system: photovoltaic arrays (PV), wind turbine generators (WG) and waste boilers (WB) are integrated with diesel generators and batteries to design a hybrid system that supplies the required demand of a remote area in Qatar using heuristic approach. The method utilizes typical year data to calculate hourly output power of PV, WG and WB throughout the year. Then, different combinations of renewable energy sources with battery storage are proposed to match hourly demand during the year. The design which satisfies the desired level of loss of power supply, CO2 emissions and minimum costs is considered as best design

Capillary trapping and oil recovery in altered-wettability carbonate rock

Understanding the displacement and trapping of a displaced phase in porous media is important for applications in improved oil recovery (IOR) and carbon capture and storage (CCS). In IOR, we design the process to leave as little residual oil behind as possible, while for CCS, we do the opposite: we wish to maximise the amount of CO2 trapped by the host brine. Reservoir rocks display a range of wettability, from being preferentially water-wet–they spontaneously imbibe water–to oil-wet, or water repellent. Many rocks are mixed-wet, with both water-wet and oil-wet pores. The other wettability state is more intermediate-wet where, as we show, the rock appears to be largely non-wetting to both oil and water. Carbonate reservoirs, which house the majority of the world’s remaining conventional oil, and which offer potential storage locations for carbon dioxide, have an altered wettability after contact with crude oil. In this thesis we study spontaneous displacement and trapping in carbonate rocks for different wettability conditions. The rate of spontaneous imbibition governs the rate with which oil, or carbon dioxide is trapped, while the residual saturation quantifies how much trapped. This is particularly important in carbonate reservoirs, which are almost extensively fractured. In these reservoirs, the principal mechanism for displacement is spontaneous imbibition of water to displace oil (or carbon dioxide) in the water-wet portions of the pore space. Pore structure and wettability are two of the main factors affecting displacement and capillary trapping. Experimental and pore-scale modelling studies have found a monotonic increase of residual non-wetting phase saturation, Snwr, with the initial non-wetting phase saturation, Snwi in a water-wet medium. However, altered-wettability systems have received relatively little attention, particularly those which are intermediate-wet. We first present the three carbonates we study in this thesis: Estaillades, Ketton and Portland. These are three quarry limestones that have very different pore structures and span a wide range of permeability. We present standard core analysis results including mercury injection capillary pressure and nuclear magnetic resonance response. We also study three-dimensional X-ray images of these samples, obtained at a resolution of a few microns. We use these experiments to assess the pore size distribution; we show that all the samples have micro-porosity and use the results to interpret the trapping and displacement experiments performed later. We then perform spontaneous imbibition experiments in these three carbonates under strongly water-wet conditions. We use scaling equations and recently published analytical solutions to assess the recovery of these rocks. We perform two sets of experiments. In the first, we measure the mass of water imbibed as a function of time. We show that the amount imbibed scales as the square root of time. In the second series of experiments, we measure saturation profiles as a function of distance and time using X-ray CT scanning. We demonstrate that the saturation profiles are functions of distance divided by the square root of time. We also demonstrate that the profiles are consistent with the analytical theory and, using reasonable estimates of relative permeability and capillary pressure, we can match the experimental results with the analytical solutions. We discuss how, in combination with conventional measurements of relative permeability (steady-state or using Buckley-Leverett theory in an unsteady-state experiment) these measurements could be used to measure capillary pressure and relative permeability. In the next phase of the study, we use organic acid (cyclohexanepentanoic acid) to alter the wettability of our samples and observe the relationship between the initial oil saturation and the residual saturation. We take cores containing oil and a specified initial water saturation and waterflood until 10 pore volumes have been injected. We record the remaining oil saturation as a function of the amount of water injected. In the water-wet case, with no wettability alteration, we observe, as expected, a monotonic increase between the initial and the remaining oil saturation. However, when the wettability is altered, we observe an increase, then a decrease, and finally an increase in the trapping curve for Estaillades limestone with a small, but continued, decrease in the remaining saturation as more water is injected. This behaviour is indicative of mixed-wet or intermediate-wet conditions as there is no spontaneous imbibition of oil and water. However, Ketton did not show indications of a significant wettability alteration with a similar observed trapping profile to that observed in the water-wet case. Portland limestone also showed a monotonic increasing trend in residual saturation with initial saturation but with a higher recovery, less trapping, than the water-wet case. Again, this is intermediate-wet behaviour with no spontaneous imbibition of either oil or water, and slow production of oil after water breakthrough. Finally, we repeat the same experiments but instead we age the three carbonates with a high asphaltenic content and high viscosity crude oil at 70C mimicking reservoir conditions. The results show a monotonic increase in residual saturation as a function of initial saturation but with higher recovery than the water-wet cases for Estaillades and Portland, with again no indication of wettability alteration for Ketton. We discuss the results in terms of pore-scale recovery process and contact angle hysteresis. We observe recovery behaviour that lies between the water-wet and mixed-wet conditions previously studied in the literature. Overall, the thesis demonstrates that recovery rate and the amount of trapping are sensitive to pore structure and wettability. Very different recovery trends were observed for three rocks with similar chemical composition. The work serves as a benchmark for further modelling and experimental studies. The recommendation is to reproduce, in the laboratory, conditions close to those observed in the reservoir, and to use imbibition and displacement measurements to quantify and constrain multiphase flow properties.Open Acces

Science Teachers’ Beliefs about Teaching and Learning Implementing Inquiry-based learning – a Case in Qatar Government Primary Schools

The current study investigates the beliefs held by science teachers’ on constructivism and a traditional approach in Qatar government primary schools. More specifically, it aims to investigate the challenges that science teachers experience during inquiry-based learning implementation. A web-based survey was conducted in order to collect data from Grades 4, 5, and 6 science teachers. The survey consisted of three sections: Demographic Data, Teachers Beliefs, and Challenges. A total of 112 science teachers responded and completed the survey on a voluntary basis. The results indicate that science teachers hold a higher beliefs in constructivism than traditional approach. A T-test and ANOVA analysis have showed that there is no significant differences between the beliefs of science teachers’ and their gender, level of education, and years of teaching experience. In addition, Science teachers faced challenges in lesson planning, assessment, and teacher support

Mental illness and help-seeking behaviours among Middle Eastern cultures: A systematic review and meta-synthesis of qualitative data

Background: Western literature has long explored help-seeking behaviours related to mental health issues. However, this has been relatively neglected in the Middle East despite an increase in mental health needs in the region. The purpose of this review was to conduct a systematic review and qualitative meta-synthesis exploring help-seeking behaviours related to mental health issues in the Middle East. // Methods: We conducted a systematic review and meta-synthesis to gain a comprehensive overview of what is known about mental health and help-seeking behaviours in the Middle East from published qualitative research in the Middle Eastern region. A search of electronic databases (MEDLINE, Embase, CINAHL, PsycINFO and QScience) was carried out from inception to July 2022. The quality of the included studies was assessed using the Critical Appraisal Skills Programme tool, and the review protocol was pre-registered with PROSPERO (Ref: CRD42022311494). // Results: We identified 16 qualitative studies exploring mental health-seeking behaviours in Middle East countries. Facilitators and barriers to help-seeking were captured under six overarching themes. Across all studies, we identified negative attitudes towards seeking help for mental health issues, economic and structural barriers to accessing mental healthcare, and misconceptions surrounding religious beliefs, all of which had a critical role in impacting decisions to seek mental healthcare services. Many sought help from alternative sources, such as traditional healers or family members before consulting a healthcare professional. The role of the family and cultural norms was also identified as key contributors to people’s help-seeking behaviours. // Conclusions: This meta-synthesis indicates the existence of many challenges surrounding mental health-seeking in the Middle East, including public and internalizing stigmas. This suggests an urgent need for an increase in psychoeducation and mental health awareness in the region

Understanding experiences of mental health help-seeking in Arab populations around the world: a systematic review and narrative synthesis

BACKGROUND: Racial and ethnic disparities in mental health service utilisation and access is well established. Mental illness is common among Arab populations globally, but most individuals display negative attitudes towards mental health and do not seek professional help. The aim of this systematic review was to determine 1) help-seeking behaviours 2) help-seeking attitudes and 3) help-seeking barriers and facilitators, related to mental health services among Arab adults. METHOD: A pre-defined search strategy and eligibility criteria allowed for database searching using terms related to: mental health, Arabs, help-seeking, as well as experiences and behaviours. Seventy-four articles were included and analysed through narrative synthesis. Results were reported using the PRISMA guidelines. The review protocol was registered prospectively on PROSPERO (CRD42022319889). RESULTS: Arabs across the world have negative attitudes towards formal help-seeking and are reluctant to seek help, despite the presence of psychological distress. There is little information on factors that influence help-seeking behaviours and rates of service use. Preference for informal help sources such as family and friends were expressed and considered more acceptable. Low mental health literacy, stigma, gender, age, education, religion, acculturation, and immigrant status were the most common factors influencing help-seeking attitudes. Barriers to help-seeking included stigma, privacy and confidentiality, trust, mental health literacy, language, logistics, and culture related barriers. Increasing societal and family awareness, external support and encouragement, shared culture between the client and therapist, quality of doctor patient relationship, and feelings of connectedness with the host country among refugees were mentioned facilitators. Mixed findings for the role of religion, and family and community, in relation to facilitating or hindering help-seeking were reported. CONCLUSIONS: There is an increased likelihood and preference to seek informal sources of psychological support among Arabs. Contextual and cultural factors impeding help-seeking for Arabs are common across the world. Future research should address actual utilisation rates of services to better understand factors that influence help-seeking behaviours and facilitators to help-seeking. Increasing mental health literacy and developing anti stigma campaigns is necessary. Developing culturally informed interventions should inform future efforts to promote help-seeking among this population

Science Teachers' Beliefs About Teaching And Learning Implementing Inquiery-Based Learning - A Case In Qatar Government Primary Schools

The current study investigates the beliefs held by science teachers' on constructivism and a traditional approach in Qatar government primary schools. More specifically, it aims to investigate the challenges that science teachers experience during inquiry-based learning implementation. A web-based survey was conducted in order to collect data from Grades 4 to 6 science teachers. A total of 112 science teachers responded and completed the survey on a voluntary basis. The results indicate that science teachers hold a higher beliefs in constructivism than traditional approach. A T-test and ANOVA analysis have showed that there is no significant differences between the beliefs of science teachers' and their gender, level of education, and years of teaching experience. In addition, Science teachers faced challenges in lesson planning, assessment, and teacher support

Herpes simplex virus type 1 epidemiology in Latin America and the Caribbean: Systematic review and meta-analytics

Objectives To investigate the epidemiology of herpes simplex virus type 1 (HSV-1) in Latin America and the Caribbean. Methods Systematic review and meta-analytics guided by the Cochrane Collaboration Handbook and reported following the PRISMA guidelines. Results Thirty-three relevant reports were identified including 35 overall (and 95 stratified) seroprevalence measures, and five and nine proportions of virus isolation in genital ulcer disease (GUD) and in genital herpes, respectively. Pooled mean seroprevalence was 57.2% (95% CI: 49.7-64.6%) among children and 88.4% (95% CI: 85.2-91.2%) among adults. Pooled mean seroprevalence was lowest at 49.7% (95% CI: 42.8-56.6%) in those aged ?10, followed by 77.8% (95% CI: 67.9-84.8%) in those aged 10-20, 82.8% (95% CI: 73.1-90.8%) in those aged 20-30, 92.5% (95% CI: 89.4-95.1%) in those aged 30-40, and 94.2% (95% CI: 92.7-95.5%) in those aged ?40. Age was the strongest source of heterogeneity in seroprevalence, explaining 54% of variation. Evidence was found for seroprevalence decline over time. Pooled mean proportion of HSV-1 isolation was 0.9% (95% CI: 0.0-3.6%) in GUD and 10.9% (95% CI: 4.4-19.4%) in genital herpes. Conclusions HSV-1 is a widely prevalent infection in this region, but its epidemiology may be slowly transitioning, with still limited contribution for HSV-1 in genital herpes

The Experiences of People From Arab Countries in Coping with Trauma Resulting From War and Conflict in the Middle East: A Systematic Review and Meta-synthesis of Qualitative Studies

The Middle East region has been an area of war and political conflict for several decades. There is currently limited research on the experiences of war and conflict among the individuals from Arab countries in the Middle East. The aim of this review was to systematically review and meta-synthesize qualitative literature on the experiences of individuals from Arab countries in the Middle East of going through and coping with war and political conflict. We systematically searched for relevant literature through MEDLINE, PsycINFO, CINAHL, Google Scholar, EThOS, OpenGrey, and The Arab Journal of Psychiatry. Studies selected needed to have a qualitative design reporting on the war and conflict experiences of participants aged 18 years or older from Arab countries in the Middle East. The review protocol was preregistered with PROSPERO (Ref: CRD42022314108). We identified 27 studies to be included in the final review. Four overarching themes were included in the meta-synthesis: War and conflict as life-defining experiences, experiences of hardship, coping with war and conflict, and positives out of a painful experience. Participants in the included studies reported significant distress and losing their sense of self, as well as resilience and positive growth. This review and meta-synthesis revealed the particular culturally informed experiences of individuals from Arab countries in the Middle East in processing their conflict experiences. These experiences highlight the need for culturally sensitive interventions for a population that has been under significant war-related stressors

Tribo-Mechanical, Biocompatibility, and Corrosion Properties Investigation of Zirconium and SST 304 by Application of Hydroxyapatite/Reduced Graphene Oxide/Palladium-Platinium Nanocomposite Coatings

This thesis describes the synthesis of HA/rGO/Pd and HA/rGO/Pt nanocomposite thin film coatings on stainless steel 304 and pure zirconium applied via an electrodeposition method. The corrosion and biocompatibility characteristics of HA/rGO/Pd and HA/rGO/Pt nanocomposite thin films are investigated here. Biocompatibility tests were carried out on uncoated, HA-coated, HA/rGO-coated, HA/rGO/Pd-coated, and HA/rGO/Pt-coated substrates using the human cell line MDA-MB-231, which had a green fluorescent protein to report the presence of living cells. Experiments revealed that the biocompatibility of the SST 304 surface showed the best cell spreading and proliferation when coated with the HA/rGO/Pd nanocomposite. The zirconium substrate coated with HA/rGO/Pt showed decreased cell proliferation and adhesion compared with HA/rGO, showing that Pt did not improve the biocompatibility. A synthetic medium was used to conduct corrosion tests, which confirmed that the HA/rGO/Pd-coated SST 304 had a significantly higher corrosion resistance than the uncoated, HA-coated, and HA/rGO-coated SST 304 samples. In addition, the HA/rGO/Pd-coated SST 304 and the HA/rGO/Pt-coated zirconium substrates were annealed at different temperatures (200, 300, 400, and 600 oC) to investigate their corrosion and wear behaviors. The HA/rGO/Pd-coated substrate annealed at 600 °C showed better wear resistance compared with the other samples. The wear tests result of bare and electrodeposited specimens before and after heat treatment for the HA/rGO/Pt showed that the coated samples heated at 300 °C had superior resistance against wear compared with bare and electrodeposited substrates at other annealing temperatures