A hybrid power system uses many wind turbine generators (WTG) and solar photovoltaics (PV) in isolated small areas. However, the output power of these renewable sources is not constant and can ...diverge quickly, which has a serious effect on system frequency and the continuity of demand supply. In order to solve this problem, this paper presents a new frequency control scheme for a hybrid power system to ensure supplying a high-quality power in isolated areas. The proposed power system consists of a WTG, PV, aqua-electrolyzer (AE), fuel cell (FC), battery energy storage system (BESS), flywheel (FW) and diesel engine generator (DEG). Furthermore, plug-in hybrid electric vehicles (EVs) are implemented at the customer side. A full-order observer is utilized to estimate the supply error. Then, the estimated supply error is considered in a frequency domain. The high-frequency component is reduced by BESS and FW; while the low-frequency component of supply error is mitigated using FC, EV and DEG. Two PI controllers are implemented in the proposed system to control the system frequency and reduce the supply error. The epsilon multi-objective genetic algorithm ( ε -MOGA) is applied to optimize the controllers’ parameters. The performance of the proposed control scheme is compared with that of recent well-established techniques, such as a PID controller tuned by the quasi-oppositional harmony search algorithm (QOHSA). The effectiveness and robustness of the hybrid power system are investigated under various operating conditions.
A novel polar fuzzy (PF) control approach for a hybrid power system is proposed in this research. The proposed control scheme remedies the issues of system frequency and the continuity of demand ...supply caused by renewable sources’ uncertainties. The hybrid power system consists of a wind turbine generator (WTG), solar photovoltaics (PV), a solar thermal power generator (STPG), a diesel engine generator (DEG), an aqua-electrolyzer (AE), an ultra-capacitor (UC), a fuel-cell (FC), and a flywheel (FW). Furthermore, due to the high cost of the battery energy storage system (BESS), a new idea of vehicle-to-grid (V2G) control is applied to use the battery of the electric vehicle (EV) as equivalent to large-scale energy storage units instead of small batteries to improve the frequency stability of the system. In addition, EV customers’ convenience is taken into account. A minimal-order observer is used to estimate the supply error. Then, the area control error (ACE) signal is calculated in terms of the estimated supply error and the frequency deviation. ACE is considered in the frequency domain. Two PF approaches are utilized in the intended system. The mission of each controller is to mitigate one frequency component of ACE. The responsibility for ACE compensation is shared among all parts of the system according to their speed of response. The performance of the proposed control scheme is compared to the conventional fuzzy logic control (FLC). The effectiveness and robustness of the proposed control technique are verified by numerical simulations under various scenarios.
Wind is a clean, abundant, and inexhaustible source of energy. However, wind power is not constant, as windmill output is proportional to the cube of wind speed. As a result, the generated power of ...wind turbine generators (WTGs) fluctuates significantly. Power fluctuation leads to frequency deviation and voltage flicker inside the system. This paper presents a new methodology for controlling system frequency and power. Two decentralized fuzzy logic-based control schemes with a high-penetration non-storage wind–diesel system are studied. First, one is implemented in the governor of conventional generators to damp frequency oscillation, while the other is applied to control the pitch angle system of wind turbines to smooth wind output power fluctuations and enhance the power system performance. A genetic algorithm (GA) is employed to tune and optimize the membership function parameters of the fuzzy logic controllers to obtain optimal performance. The effectiveness of the suggested controllers is validated by time domain simulation for the standard IEEE nine-bus three-generator test system, including three wind farms. The robustness of the power system is checked under normal and faulty operating conditions.
Green synthesis of nanoparticles is an eco-friendly treatment technique. Bimetallic nano zero-valent Fe/Cu was successfully prepared by green synthesis by Ficus Benjamina leaves (FB-ZVI/Cu). The ...nanoscale FB-ZVI/Cu was characterized by scanning electron microscope, Fourier transform infrared spectroscopy, and dispersive X-ray spectroscopy. The characterization revealed that synthesis and presence of iron–copper nanoparticles and biomolecules which could help in capping the bimetallic nanoparticles. Subsequently, nanoscale zero-valent Fe/Cu particles were used to remove carbamazepine from the aqueous medium under varying experimental conditions, including pH, initial carbamazepine concentration, Fe/CuNPs dose, stirring rate, and contact time. The removal efficiency of carbamazepine reached 95% under the condition of dose 0.4 g L
−1
, time 20 min, and pH 5. The results were analyzed according to the Freundlich and Langmuir adsorption isotherms. The adsorption data are more appropriate by the Langmuir adsorption model (
R
2
= 0.998) with
q
max
= 26.15 mg g
−1
. Overall, FB-nZVFe/Cu is a promising green substance to remove carbamazepine from aqueous solutions. The effect of different operating parameters was investigated using linear regression analysis, they were found to account for more than 97% of the variables affecting the removal process.
Article Highlights
Bimetallic nZVFe/Cu was synthesized using the Ficus Benjamina leaves’ extracts.
Nanoparticles were characterized by SEM, EDAX, and FTIR.
The green-synthesized FB-nZVFe/Cu nanoparticles can remove carbamazepine from aqueous solutions.
Removing mechanism based on adsorption and reduction is proposed.
A high removal percentage of carbamazepine was 95%.
Lower FB-nZVI/Cu PZC values.
The coronavirus (COVID-19) pandemic required a transformation of medical education in Egypt. Public health measures necessitated a rapid shift from traditional face to face lectures to largely online ...platforms following campus closures. The aim of this study is to characterize medical student use and perception of online medical education in Egypt as well as exploring the efficacy of different e-learning modalities. Additionally, many barriers and opportunities as perceived by students are reviewed to inform future educational improvements.
A 29-item online survey was created on google forms and distributed by social media to medical students across 26 Egyptian medical schools. The survey was administered from August 20th, 2021, to September 5th, 2021. The survey consisted of a mixture of questions style. The medical students were asked about their experiences with online medical education during the COVID-19 pandemic as well as medical students' anxiety, perceived academic performance, and obstacles related to online education.
Of the 4935 responses collected, 43.4% (n = 2140) of respondents were women; 56.6% (n = 2795) were men. Medical students from private medical schools were 13.0% (n = 644), whereas 87.0% (n = 4291) were from public medical schools. 54.6% of students reported that online education is not as effective as face-to-face education. There was a significant rise in hours spent by medical students on online medical education compared to before COVID-19 pandemic. More than half of students (63%) agreed that online recorded video tutorials (e.g., YouTube) were the most effective form of online medical education.
The shift to online education has significantly impacted medical students in Egypt. Medical students reported various limitations and challenges of online medical education, which must be addressed considering the potential benefits of online platforms over traditional face to face learning. The results of this nationwide study provide a framework for potential areas to implement change to improve the accessibility and structure of online medical education in Egypt.
The present research was carried out to study the effect of adding autoclaved non-meat ingredients on the microbial quality and aflatoxin contents in pastrami final product, produced from fresh, ...chilled or frozen meat cuts, during its manufacturing steps. The experiment was carried out on three groups of pastrami. The first group was aimed to study the effect of adding autoclaved non-meat additives on aerobic plate counts and E. coli counts of produced pastrami. The second group was directed to study the effect of each manufacturing steps on artificially inoculated E. coli O157:H7 onto beef cut used for pastrami fabrication. The third group was designed to study the effect of using high quality spices (subjected to HACCP during its fabrication) on the residual contents of aflatoxins in the final pastrami product. The results indicated that using of autoclaved non-meat ingredients significantly reduced the microbial load in pastrami final product. In addition, manufacturing steps of pastrami produced complete inhibition of artificially inoculated E. coli O157:H7 in the final product. Furthermore, the use of sterilized high quality spices resulted in reduction of aflatoxin contents in pastrami bellow the permissible limit in comparison with the use of low quality spices purchased from ordinary shops.
•Using of autoclaved non-meat ingredients has a great effect on the microbial quality of produced pastrami during manufacturing steps.•Using of autoclaved non-meat ingredients has a great effect on E. coli O157:H7 during steps of pastrami manufacturing.•Using of high quality spices has a great effect on the residual contents of mycotoxins in the final pastrami product.
Serum uric acid levels are frequently elevated in patients with chronic kidney disease (CKD). The relatively modest hyperuricaemia in CKD may reflect the reduced efficiency of renal excretion of ...urate. In the past two decades, basic research has shown that hyperuricaemia plays a causal role in the progression of CKD through direct renal injury. However, clinical studies have reported conflicting results, hence there is much controversy about the scope of treating asymptomatic hyperuricaemia to prevent or reduce the rate of CKD progression. In this review, we highlight the most recent guidelines and clinical trials that tested the use of urate-lowering therapy in the management of asymptomatic hyperuricaemia in CKD patients. Keywords: uric acid, hyperuricaemia, chronic kidney disease
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