1,721,333 research outputs found
2° Mosquée d'as-Sayed Ahmad al-Bagam
No full textFarnall Harry, Shafik Muhammad, Simaïka Marcus H., Sayed Metoualli, Omar Ahmad, 'Amrusi Ahmad Fahmi al-, Sayyed Ahmad el-. 2° Mosquée d'as-Sayed Ahmad al-Bagam. In: Comité de Conservation des Monuments de l'Art Arabe. Fascicule 34, exercice 1925-1926, 1933. pp. 63-64
Minimizing cogging torque in permanent magnet synchronous generators for small wind turbine applications
No full textPermanent magnet synchronous generators have a wide usage among electric machines, especially in small wind turbine systems. However permanent magnet synchronous generators suffer from cogging torque due to the magnetic interaction between the poles of the rotor’s permanent magnets and the steel laminations of the stator’s teeth. The cogging torque drawback is a major problem in this kind of generators that affects its functionality negatively. In the literature many different approaches for reducing the cogging torque are proposed and each different approach achieves different amount of reduction in the cogging torque. In this study 6 different cogging torque reduction techniques are considered and with finite element simulations using the JMAG simulation software, they are compared with each other in terms of percent reduction in the cogging torque. Present simulations show that among the considered different approaches, continuous skewing technique reduces the cogging torque the most with respect to the each other techniques considered. Also using the step skewing of the rotor or stator, changing the slot opening width and having dummy slots techniques can decrease the cogging torque more or less the same amount in magnitude. Present results indicate that changing the radial shoe depth technique has almost no effect in reducing the cogging torque
Assessment of firm capacity in hybrid systems: A Dubai case study on ess sizing
No full textAiming for carbon-free power systems for future grids has challenges in providing the necessary firm capacity from a power engineering perspective. During capacity planning studies, the variability of renewables can lead to periods of zero firmness, necessitating nonrenewable generation technologies to be added to the candidate list to ensure firmness. However, hybrid systems can provide limited firmness and lower the need for nonrenewable resources. This paper investigates the temporal firmness of the various sizes of energy storage systems combined with a 1MWp photovoltaic system. Using real-Time data from a site in Dubai, the framework simulates system performance hourly and monthly over an entire year. The analysis reveals that hybrid system firmness is affected by seasonal variations in PV output and is highly sensitive to the storage capacity. The study further demonstrates how different storage capacities affect the system's ability to maintain firm capacity. © 2025 IEEE
Presidentialism in a Divided Society : Afghanistan 2004 – 2009
No full textapplication/pdfapplication/pdfapplication/pdf1879904 bytes87480 bytes94642 bytes学位論文(Thesis
Human Resource Development Corporation / Syed Muhammad Fitri Sayed Ahmad Fauzi
Get PDFDuring my internship at a company, I had a valuable learning experience. This executive summary provides a brief overview of my journey as an intern. Throughout my internship, I actively participated in various tasks and projects, gaining practical insights into the company's operations. It was a hands-on experience that allowed me to apply my knowledge and contribute to the company's objectives. I had the opportunity to learn about the company's strengths and weaknesses through observation and analysis. This understanding helped me identify potential areas for improvement. The company provided a supportive environment for my growth as an intern. The objectives and goals of the company were clear, focusing on its vision for success. Based on my experiences and observations, I have some recommendations to enhance the company's performance. These suggestions aim to address specific areas that could benefit from improvement. In conclusion, my internship journey was a valuable learning experience that allowed me to actively contribute to the company's goals. The insights gained and the recommendations provided are aimed at further enhancing the company's success
Prediction algorithm & learner selection for European day-ahead electricity prices
No full textThe prediction of day-ahead electricity prices with higher accuracy is always helpful for the market players of the power exchange. This study was intended in the first place to find out the best time series prediction method for the selected 14 European countries. The test results of four time-series methods show that the next day prices were more in line with the previous day prices in 87% of the selected countries; Later, a classification approach is followed by 33 different features of each country to answer the question of which method would be the best for the other countries, that were not studied in this paper, would be? As a result, the support vector machine algorithm results in 57% accuracy in classifying an unknown European country to determine the best prediction method. Therefore, this paper focuses now on two correlated studies to find out the best time series prediction methods and a classification approach for selected countries
Analysis of Grid Performance with Diversified Distributed Resources and Storage Integration: A Bilevel Approach with Network-Oriented PSO
No full textThe growing deployment of distributed resources significantly affects the distribution grid performance in most countries. The optimal sizing and placement of these resources have become increasingly crucial to mitigating grid issues and reducing costs. Particle Swarm Optimization (PSO) is widely used to address such problems but faces computational inefficiency due to its numerical convergence behavior. This limits its effectiveness, especially for power system problems, because the numerical distance between two nodes in power systems might be different from the actual electrical distance. In this paper, a scalable bilevel optimization problem with two novel algorithms enhances PSO’s computational efficiency. While the resistivity-driven algorithm strategically targets low-resistivity regions and guides PSO toward areas with lower losses, the connectivity-driven algorithm aligns solution spaces with the grid’s physical topology. It prioritizes actual physical neighbors during the search to prevent local optima traps. The tests of the algorithms on the IEEE 33-bus and the 69-bus and Norwegian networks show significant reductions in power losses (up to 74% for PV, wind, and storage) and improved voltage stability (a 21% reduction in mean voltage deviation index) with respect to the results of classical PSO. The proposed network-oriented PSO outperforms classical PSO by achieving a 2.84% reduction in the average fitness value for the IEEE 69-bus case with PV, wind, and storage deployment. The Norwegian case study affirms the effectiveness of the proposed approach in real-world applications through significant improvements in loss reduction and voltage stability
Multi-criteria Decision Model for the Assessment of Offshore Wind Energy Potential of Tunisia
No full textThis paper investigates the potential for the development of offshore wind power plants in Tunisia. The goal of this research is to increase the possibility of using renewable energy available in the country and reduce the dependence on fossil fuels. The data used for the analysis is obtained from remote sensing satellites and weather stations located across the country's coastal regions. A multi-criteria decision model is built to perform geographic and technical analysis of the study area. This research reveals locations suitable for wind turbine installations. The results of this study aid the transition to wind energy with its optimal adaptation in Tunisia. Only 7% of Tunisian offshore territory is found fit for the deployment of fixed-bottom wind farms. Six locations, in particular, were chosen in the Gulf of Tunisia, Gabes, Sousse, Sfax, Bizerte, and Djerba. The GIS-based methodology proposed in this paper can be applied to other offshore wind farm allocation investigations. The environmental impact of proposed wind farms on GHG reduction and employment opportunities are investigated. The suggested wind farms will reduce the GHG emissions and the energy price in Tunisia as well as create new jobs for society
An integrated framework for techno-enviro-economic assessment in nanogrids
No full textThis paper presents an integrated framework designed for capacity planning of grid -connected nanogrid, a small solar and energy storage system that can provide kilowatt -level services to individual buildings. This framework comprehensively evaluates nanogrid cost-effectiveness, sustainability, and reliability, employing a multi -faceted techno-enviro-economic assessment approach. Traditional nanogrid capacity planning often prioritizes peak load requirements, which may lack optimality owing to occasional peak load occurrences. Conversely, optimizing solely for base load requirements might also fall short of effectiveness, compromising reliability and sustainability objectives. The proposed framework employs a threestep, integrated process for nanogrid (NG) capacity planning. Firstly, the Planner module identifies optimal asset sizing considering a two-day lookahead logic. Then, the Operator module serves as a digital twin for the system, conducting hourly calculations over a short-term horizon. Lastly, the Evaluator module evaluates technical, environmental, and economic metrics for each solution, assessing the effectiveness of asset -sizing decisions. A simulated case study has demonstrated the effectiveness of the proposed framework. The technical assessment revealed that a PV size of 24 kW and a storage capacity of 91 kWh led to the most reliable solution, with a probability of local sufficiency of 95 percent. Furthermore, the environmental assessment showcased a renewable fraction of 94% with a PV size of 26 kW and a storage of 85 kWh. Economically, the analysis identified that a PV size of 12 kW and a storage size of 24 kWh led to the minimum total cost. In contrast, a PV size of 26 kW and a storage size of 85 kWh yielded a total operating savings of $4,801.Publisher versio
Capacity planning for forming sustainable and cost-effective nanogrids
No full textThis paper proposes a new strategy for nanogrid capacity planning as a bilevel programming mathematical model with look-ahead logic. The first program, the Planner, is a linear program that solves for the optimal size of the Nano-grid comprising a PV solar system and a battery energy storage system. The second program, the Operator, is a mixed integer linear program that uses resultant sizes from the Planner and other data and then solves for the optimal asset dispatch on an hourly basis throughout the whole horizon. 24-hours is used as the main optimization window, to be consistent with real case operations of day-ahead scheduling but longer windows were also tested with the Lookahead (LA) logic. A sensitivity to LA logic was applied for an analysis conducted on cost-effectiveness, system sustainability, and local energy sufficiency. It was shown that implementing two days of LA logic reduces the import cost by 44%. Nano-grid was considered in this study to test the capacity planning strategy, but the methodology is also applicable to larger schemes
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