Hybrid nuclear-solar power

Nuclear and solar power, in the form of concentrated solar power (CSP), play a significant role in achieving the ambitious global targets of reducing greenhouse emissions and guaranteeing security of energy supply. However, both power generation technologies still require further development to realise their full potential, especially in terms of attaining economic load following operations and higher thermal efficiencies. Therefore, the aim of this research is to investigate and thermo-economically evaluate the available options of upgrading the flexibility and enhancing the thermal efficiency of nuclear and solar power generation technologies (i.e., through the integration with thermal energy storage (TES) and by hybridising both power generation technologies) while providing reasonable economic returns. The thesis starts with describing the development and validation of several thermodynamic and economic computational models and the formulation of the whole-energy system model. The formulated models are utilised to perform several thermo-economic studies in the field of flexible nuclear and solar power, and to quantify the economic benefits that could result from enhancing the flexibility of nuclear power plants from the whole-energy system perspective. The studies conducted in this research are: (i) a thermo-economic assessment of extending the conventional TES system in direct steam generation (DSG) CSP plants; (ii) a thermo-economic evaluation of upgrading the flexibility of nuclear power plants by the integration with TES and secondary power generation systems; (iii) an investigation of the role of added flexibility in future low-carbon electricity systems; and (iv) a design and operation analysis of a hybrid nuclear-solar power plant. The most common TES option in DSC CSP plants is steam accumulation. This conventional option is constrained by temperature and pressure limits, leading to lower efficiency operations during TES discharging mode. Therefore, the option of integrating steam accumulators with sensible-heat storage in concrete to provide higher-temperature superheated steam is thermo-economically investigated in this research, taking an operational DSG CSP plant as a case study. The results show that the integrated concrete-steam TES (extended) option delivers 58% more electricity with a 13% enhancement in thermal efficiency during TES discharging mode, compared to the conventional steam accumulation (existing) configuration. With an estimated additional investment of $4.2M, the projected levelised cost of electricity (LCOE) and the net present value (NPV) for the considered DSG CSP plant with the extended TES option are respectively 6The option of upgrading the flexibility of nuclear power plants through the integration with TES and secondary power generation systems is investigated for two conventional nuclear reactors, a 670-MWel advanced gas-cooled reactor (AGR) and a 1610-MWel European pressurised reactor (EPR). In both investigated case studies, the reactors are assumed to continuously operate at full rated thermal power, while load following operations are conducted through the integrated TES tanks and secondary power generators. Based on the designed TES and secondary power generation systems, the AGR-based configuration can modulate the power output between 406 MWel and 822 MWel, while the EPR-based configuration can operate flexibly between 806 MWel and 2130 MWel. The economic analysis results demonstrate that the economics of added flexibility are highly dependent on: (i) the size of the TES and the secondary power generation systems; (ii) the number of TES charge/discharge cycles per day; and (iii) the ratio and difference between off-peak and peak electricity prices. Replacing conventional EPR-based nuclear power plants with added flexibility ones is found to generate whole-system cost savings between$30.4M/yr and $111M/yr. At an estimated cost of added flexibility of$53.4M/yr, the proposed flexibility upgrades appear to be economically justified with net system economic benefits ranging from $5.0M/yr and$39.5M/yr for the examined low-carbon scenarios, provided that the number of flexible nuclear plants in the system is small. The concept of hybridising a small modular reactor (SMR) with a solar-tower CSP integrated with two-tank molten salt TES system, with the aim of achieving economically enhanced load following operations and higher thermal efficiency levels, is also thermo-economically investigated in this research. The integration of both technologies is achieved by adding a solar-powered superheater and a reheater to a standalone SMR. The obtained results demonstrate that hybridising nuclear and solar can offer a great amount of flexibility (i.e., between 50% and 100% of nominal load of 131 MWel) with the SMR continuously operated at full rated thermal power output. Furthermore, the designed hybrid power plant is able to operate at higher temperatures due to the addition of the solar superheater, resulting in a 15% increase of thermal efficiency compared to nuclear-only power plant. Moreover, the calculated specific investment cost and the LCOE of the designed hybrid power plant are respectively 5410 $/kWel and 77$/MWhel, which are 2% and 4% lower than those calculated for the nuclear-only power plant.Open Acces

A Cerebellar High-Grade Neuroepithelial Tumour with BCOR Alteration in a five-year-old Child: A case report.

New groups of high-grade neuroepithelial tumours (HGNET) have emerged from the reclassification of central nervous system (CNS) embryonal tumours that have recognised CNS HGNET with BCOR alteration (CNS HGNET-BCOR). We report a two-year, nine-month-old Omani boy who presented to the Royal Hospital, Muscat, Oman, in 2015 with subacute head tilting and neck pain. A well-defined cerebellar lesion was found and he was treated with standard chemoradiotherapy. After a relapse at the age of five years, molecular testing revealed a BCOR alteration. He was treated with further surgery and high-dose chemotherapy; unfortunately, he relapsed and died three years after he was diagnosed

Giant Mediastinal Myxoid Pleomorphic Liposarcoma

NON

Assessment of groundwater recharge from the dam of Wadi Al-Jizzi, Sultanate of Oman

Water is the most precious resource in arid and semi-arid countries including the Sultanate of Oman. In such countries, groundwater is regarded a major source of water. However, the long-term yield of aquifers should be evaluated. Annual recharge of groundwater resources, in such areas, is generally small but groundwater levels may also recover dramatically during wet years. Due to the increase in population and the associated increase in agricultural and industrial activities groundwater abstraction from the different aquifers in Oman has increased tremendously since the mid-1970s. This over exploitation of the groundwater resources has led to a considerable decline in the subsurface water levels and hence affected the water balance in the interrelated hydrogeological systems. Although surface water is not always a major source of water it is sometimes feasible to build dams across the main Wadis to provide water for domestic and/or irrigation purposes. The collected surface water at dams can also be used to recharge the depleted aquifers. This is quite true in arid and semi-arid regions. The Sultanate of Oman is no exception. Efficient management of groundwater resources is not only needed but also necessary to provide a sustainable groundwater supply. Artificial recharge of aquifers, application of water conservation plans, water and wastewater reuse, and improved irrigation methods are some of the techniques which could be used to increase the availability and sustainability of water resources. To that end, eighteen dams have been built in the Sultanate of Oman since the mid-1986. These dams are mainly built to recharge the groundwater systems and minimize the seawater intrusion in the coastal areas. The basic idea of any recharge dam is to hold the surface water runoff that might develop from heavy rainfall events in a particular Wadi at a location where the recharge to the groundwater is desired. The water is either infiltrated from the reservoir in the upstream side of the dam to the underlying aquifer or released through culverts to infiltrate downstream through the Wadi channel. The efficiency and the performance of the constructed dams as an effective tool for groundwater recharge needs to be investigated and reassessed. The main objective of this research is to study the efficiency of the recharge dam and simulate the groundwater conditions at Wadi Al-Jizzi. The same methodology can thus be considered in the assessment of the performance of the other dams of similar hydrogeological and physical setting. To that end, all previous studies and reports related to Wadi Al-Jizzi have been reviewed. Physical, geological, hydrological and hydrogeological settings of the area have been identified. All available records for groundwater levels and quality have been assessed and presented in different forms of analysis. The trends of groundwater levels during the last two decades have also been identified. The USGS finite difference groundwater model “MODFLOW” has been employed to simulate the groundwater conditions in Wadi Al-Jizzi. The study domain (30x30 km) was discretized into a total number of 22500 regular cells. Each cells have dimensions of 200x200 meters. Various types of boundary conditions were applied to accurately simulate the field conditions. Several assumptions were made. The aquifer was assumed homogeneous, the hydrodynamic dispersion effects were neglected, the flow in the aquifer was assumed fully horizontal, the flow in the aquitard was assumed vertical and the saline groundwater was assumed at rest. The model parameters were calibrated for the period 1985 to 1994 until a good match between the simulated and observed groundwater levels was obtained. The model was then validated, without changing the calibrated parameters, for the period 1995 to 2002. Predictions were made for the groundwater levels till the year 2020 assuming no change in groundwater abstractions and same climatic conditions. Pumping of groundwater resources in Wadi Al-Jizzi area should be reduced and controlled as much as possible. A database regarding the geological and hydrogeological setting should be established. Further development of the present numerical model might be essential to better simulate the groundwater levels and study various scenarios for groundwater pumping and management. This would help achieve the conservation of groundwater resources in Wadi Al-Jizzi catchment. The proposed scenarios should take into account the political, economic and social impacts. The Water Resources National Master Plan for integrated management of all available water resources should be updated and implemented. This master plan should account for dry and wet conditions

THE IMPACT OF STRATEGIC ALLIANCES ON CORPORATE PERFORMANCE: EXPLORING MECHANISMS AND CONDITIONS IN THE CONTEXT OF OIL AND GAS INDUSTRY IN THE UAE

Strategic Alliances are fast gaining traction in the oil and gas Drilling Industry in the World and the UAE in particular, in contrast to the challenges that arise in the markets as a result of globalization and as a business strategy to enhance the corporate performance of the firms involved in the alliances. The alliances are also in the focus of academic and business researchers and interest in Strategic Alliances has significantly increased over the past decades. This research aims to study to what extent do strategic alliances impact the corporate performance of the firms involved in these alliances in the oil and gas Industry of UAE. It also aims at identifying the factors determining the success of the strategic alliances in the UAE oil and gas industry. A thorough literature review was carried out through which three overarching factors determining SA success have been identified: SA success Strategic Factors, Operational Factors, and Tactical Factors. To address the research questions a structured questionnaire was developed using a 5-point Likert scale and 275 questionnaires were collected from key informants working in the firms involved in the strategic alliance in the Abu Dhabi oil and gas industry. Multidimensional data analysis methods have been applied to test the a priori model of Strategic alliance success factors impacting corporate performance. Particularly, Structural Equation Modeling was applied, in addition to correlations analysis exploratory factor analysis, as well as reliability, validity, and adequacy tests. In general, the research findings were consistent with the literature indicating that engagement in Strategic Alliances positively impacts the corporate performance of the firms involved. The results suggest that Strategic Alliance success operational factors are critically important which include establishing a formalized mechanism that supports alliance operations and daily management. Strategic Alliance success is not preconditioned to the existence or absence of dominance by one partner or dominance in resources controlled, but rather depends on the appropriateness of the form of cooperation for alliance and the degree of commitment between the partners. Furthermore, the research suggests that though disparities in management style and culture between the companies are important factors of SA success, operational control and coordination play a more important role and when properly implemented may mitigate the negative impact of existiig organizational disparities between the partners. Finally, Strategic Alliance success factors positively impact Corporate Performance and improves engagement in firms as well as quality of marketing, access to new markets, and usage of information technologies. This research provides quantified evidence that Strategic Alliance does add value to the firms concerned. Among the practical implications of this research are that the identified list of the SA success factors may be used by the companies involved in the strategic alliances during SA performance and implementation monitoring and evaluation process. Furthermore, the research provides policymakers in GCC countries with adequate information on the significance of the strategic alliances in the diversification of their economies. Based on research outputs recommendations for the corporations intending to engage in SA or currently involved in SAs are as follows: the companies are recommended to pay remarkable attention to the operational factors of SA operations ensuring that formalized mechanisms supporting alliance operation and daily management are properly established and maintained, e.g., ensuring that clear rules, policies, and procedures that guide cooperation procedures are in place, roles and responsibilities within the alliance are properly distributed, etc. Last but not least, the companies are recommended to ensure proper operational control and coordination, as well as ensure that the form of the alliance is appropriate and the degree of commitment between the partners is sufficient

Press Freedom and Corruption in the GCC: Are There Better Future Horizons? An Analytical-Critical Study

This study seeks to provide a critical analysis of press freedom and corruption scores in the six Arab countries under the Gulf Cooperation Council (GCC), as reported by two international nongovernmental organizations 2013–2017: (1) Freedom House (FH) and (2) Transparency International (TI). The researcher noted how some of the reports by these organizations continually connect between press freedom and corruption. The reading might help to improve the GCC states’ future performances both in press freedom and fighting against corruption. Readings on press freedom and corruption are now more widely available in many international reports of a number of international organizations. Although standards for measuring the degree of both of them vary in these reports, they often agree on one outcome. Some of these reports have gradually gained prominence in good segments of public opinion and have become the subject of debate among intellectuals and journalists. Governments refrain from commenting on such reports particularly negative ones. However, the impact of such reports on the relevant governmental entities cannot be ignored when it comes to calibrating their practices and activities internationally and comparing them with other institutions in other regional and global countries

Vitamin D Status in Healthy Omani Women of Childbearing Age : Study of female staff at the Royal Hospital, Muscat, Oman

Objectives: Sunlight exposure has a vital role in vitamin D synthesis. Although vitamin D deficiency has been well documented in temperate zones, studies have been scarce in tropical countries where the population is well covered and for various reasons avoids sun exposure. The objective of this study was to investigate serum 25-hydroxyvitamin D [25(OH)D] levels and its relationship to biochemical bone profile, exposure to sunlight and vitamin D intake amongst Omani women of childbearing age. Methods: 41 apparently healthy women working at the Royal Hospital, Muscat, Oman and aged 18–45 years, with mean ± SD of 29 ± 6 years, were included in this study conducted in December 2006. They completed a questionnaire regarding the duration of sun exposure, food intake and type of clothing worn. Blood samples were collected from them and analysed for serum 25(OH)D, calcium, phosphate, alkaline phosphatise and parathyroid hormone levels. Results: All the women had a 25(OH)D level <50 nmol/L as the cut-off for deficiency. 25(OH)D levels were strongly correlated with the lack of sun exposure (r = 0.672, P < 0.001) and a significant correlation was also found between 25(OH) D level and food intake (r = 0.482, P < 0.01). Conclusion: Subclinical 25(OH)D deficiency may be prevalent amongst Omani women. Risk factors such as poor sunlight exposure should be addressed in women of childbearing age and, if increased sunlight exposure is not possible, oral supplementation should be considered to avoid all the consequence and complications of vitamin D deficiency

The Sinus Venosus Veno-Venous Bridge Not a septal defect

\ua9 2023, Sultan Qaboos University. All rights reserved.This review provides an update on the morphology of the sinus venosus defect. It was earlier believed that a \u27common wall\u27 separated the right pulmonary veins from the superior caval vein. In the sinus venosus defects, this wall was absent. Current evidence shows that the superior rim of the oval fossa, rather than forming a second septum or representing a common wall, is an infolding between the walls of the caval veins and the right pulmonary veins. The sinus venosus defect is caused by the anomalous connection of one or more pulmonary veins to a systemic vein. However, the pulmonary vein(s) retain their left atrial connections, leading to a veno-venous bridge that allows interatrial shunting outside the oval fossa. True atrial septal defects are located within the oval fossa or in the anteo-inferior buttress, while sinus venosus defects, ostium defects and coronary sinus defects are morphologically distinct from them