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Various overvoltage mitigation schemes were used in literature in suppression of switching overvoltages in wind farms. However, the evaluation of how the effectiveness of these mitigation techniques would vary with the change of the wind farm topology is still un-explored territory. The main aim of this paper is to study the effectiveness of four mitigation schemes while using SF6 circuit breaker namely; R–L smart choke, R–C snubber circuit, surge capacitor and pre-insertion resistor (PIR) were studied in four different wind farm topologies; radial, single-sided ring, double-sided ring and star topologies. The topologies were based on a real wind farm located in Zaafrana, Egypt. The results showed that R–L choke to be the most effective scheme for all topologies followed by PIR, R–C snubber and surge capacitor schemes respectively. Their percentage of reduction of overvoltage ranged from 62 to 84% for R–L choke, 33–67% for PIR, 8–25% for R–C snubber circuits and 4–15% for surge capacitors. Also, it was shown that the change of the wind farm topology didn't affect the order of effectiveness of the mitigation schemes such that R–L remained the most effective and surge capacitor the least effective for all topologies. [ABSTRACT FROM AUTHOR]

Degradation reduces the capability of solar photovoltaic (PV) production over time. Studies on PV module degradation are typically based on time-consuming and labor-intensive accelerated or field experiments. Understanding the modes and methodologies of degradation is critical to certifying PV module lifetimes of 25 years. Both technological and environmental conditions affect the PV module degradation rate. This paper investigates the degradation of 24 mono-crystalline silicon PV modules mounted on the rooftop of Egypt's electronics research institute (ERI) after 25 years of outdoor operation. Degradation rates were determined using the module's performance ratio, temperature losses, and energy yield. Visual inspection, I–V characteristic measurement, and degradation rate have all been calculated as part of the PV evaluation process. The results demonstrate that the modules' maximum power ( P max ) has decreased in an average manner by 23.3% over time. The degradation rates of short-circuit current ( I sc ) and maximum current ( I m ) are 12.16% and 7.2%, respectively. The open-circuit voltage ( V oc ), maximum voltage ( V m ), and fill factor ( FF ) degradation rates are 2.28%, 12.16%, and 15.3%, respectively. The overall performance ratio obtained for the PV system is 85.9%. After a long time of operation in outdoor conditions, the single diode model's five parameters are used for parameter identification of each module to study the effect of aging on PV module performance. [ABSTRACT FROM AUTHOR]

The principal target of this work is to compute the optimal tilt angle (OTA) for Photovoltaic (PV) panels. To perform this task, comprehensive simulations are done starting from altering the tilt angle (TA) daily, to use one fixed TA for all the year. The mathematical models for extra-terrestrial radiation (ETR) of both horizontal and inclined surfaces are presented firstly. At a later stage, the optimization formulation for the maximizing the solar radiation (SR) is adapted, and then the daily, monthly, seasonally, half-yearly and optimal fixed TAs are obtained. Although, the daily OTA produces the maximum SR, it is costly and impractical. It is found that altering the TA twice a year at optimal values that are computed as 5° and 50° for Suez city, gives the best results that are very near to the daily altering of the OTA. The difference between the two methods is 1.56% which is very small. Also, the two OTAs has SR better than that of the fixed OTA which is 28° by 7.77%. Also, it is found that the yearly fixed OTA (28°) is nearly equal to the latitude angle of Suez city which is 30°. The two OTAs method of this paper is different from the commonly used method that suggests two TAs. The first TA is used for winter months which is obtained by adding 15° to the latitude angle while the second TA is obtained by subtracting 15° from the latitude angle for the summer months. This commonly used method produces lesser SR than the two OTAs method of this paper. The theoretical work has been proved by an experimental work on two PV systems constructed at 25° and 30° TAs. The results of the experimental work agree with the theoretical results. [ABSTRACT FROM AUTHOR]

With the increasing of global awareness of the importance of reducing polluting emissions and maintaining a clean and healthy environment. So, the tendency to generate electric energy from new and renewable sources has become an urgent need to achieve this goal. In this paper an optimal economic cost analysis using hybrid renewable energy sources to generate the electricity needed for long-term evolution mobile phone systems was estimated. The proposed electric system accounts for the reduction of polluting emissions to the environment. The electrical profile of the optimal approaches or the hybrid technology and traditional methods which contain solar photovoltaic', batteries, wind turbines, diesel generator were estimated and provides the electrical power for a Long-Term Evolution mobile network (LTE) as the load at a remote located area. A real time optimal cost analysis of each proposed network is done based on the real load profile, wind speed and solar radiation was placid on from 6 October city in Egypt. Statistical analysis was performed by varying the systems through comparison to determine the optimal approaches based on the Hybrid Optimization Model for Electrical Renewables software (HOMER). [ABSTRACT FROM AUTHOR]

Various overvoltage mitigation schemes were used in literature in suppression of switching overvoltages in wind farms. However, the evaluation of how the effectiveness of these mitigation techniques would vary with the change of the wind farm topology is still un-explored territory. The main aim of this paper is to study the effectiveness of four mitigation schemes while using SF6 circuit breaker namely; R–L smart choke, R–C snubber circuit, surge capacitor and pre-insertion resistor (PIR) were studied in four different wind farm topologies; radial, single-sided ring, double-sided ring and star topologies. The topologies were based on a real wind farm located in Zaafrana, Egypt. The results showed that R–L choke to be the most effective scheme for all topologies followed by PIR, R–C snubber and surge capacitor schemes respectively. Their percentage of reduction of overvoltage ranged from 62 to 84% for R–L choke, 33–67% for PIR, 8–25% for R–C snubber circuits and 4–15% for surge capacitors. Also, it was shown that the change of the wind farm topology didn't affect the order of effectiveness of the mitigation schemes such that R–L remained the most effective and surge capacitor the least effective for all topologies. [ABSTRACT FROM AUTHOR]

Degradation reduces the capability of solar photovoltaic (PV) production over time. Studies on PV module degradation are typically based on time-consuming and labor-intensive accelerated or field experiments. Understanding the modes and methodologies of degradation is critical to certifying PV module lifetimes of 25 years. Both technological and environmental conditions affect the PV module degradation rate. This paper investigates the degradation of 24 mono-crystalline silicon PV modules mounted on the rooftop of Egypt's electronics research institute (ERI) after 25 years of outdoor operation. Degradation rates were determined using the module's performance ratio, temperature losses, and energy yield. Visual inspection, I–V characteristic measurement, and degradation rate have all been calculated as part of the PV evaluation process. The results demonstrate that the modules' maximum power ( P max ) has decreased in an average manner by 23.3% over time. The degradation rates of short-circuit current ( I sc ) and maximum current ( I m ) are 12.16% and 7.2%, respectively. The open-circuit voltage ( V oc ), maximum voltage ( V m ), and fill factor ( FF ) degradation rates are 2.28%, 12.16%, and 15.3%, respectively. The overall performance ratio obtained for the PV system is 85.9%. After a long time of operation in outdoor conditions, the single diode model's five parameters are used for parameter identification of each module to study the effect of aging on PV module performance. [ABSTRACT FROM AUTHOR]

One of the most dangerous snake species is the "Egyptian cobra" which can kill a man in only 15 min. This paper uses deep learning techniques to identify the Egyptian cobra bite in an accurate manner based on an image of the marks of the bites. We build a dataset consisting of 500 images of cobra bites marks and 600 images of marks of other species of snakes that exist in Egypt. We utilize techniques such as multi-task learning, transfer learning and data augmentation to boost the generalization and accuracy of our model. We have achieved 90.9% of accuracy. We must keep the availability and accuracy of our model as much as possible. So, we utilize cloud and edge computing techniques to enhance the availability of our model. We have achieved 90.9% of accuracy, which is considered as an efficient result, not 100%, so it is normal for the system to perform sometimes wrong classifications. So, we suggest to re-train our model with the wrong predictions, whereas the edge computing units, where the classifier task is positioned, resend the wrong predictions to the cloud model, where the training process occurs, to retrain the model. This enhances the accuracy to the best level after a small period and increases the dataset size. We use the quantum particle swarm optimization technique to determine the optimal required number of edge nodes. [ABSTRACT FROM AUTHOR]

Rhyolite rocks extend from southern Egypt to northern Egypt in the Eastern Desert, and no effective economic exploitation of them has been discovered so far. The pozzolanic activities of different volcanic tuffs (VT) supplied from the Eastern Desert located in Egypt have been investigated as natural volcanic pozzolan materials to develop new green cementitious materials for achieving sustainability goals in the construction field. Experimentally in this paper, the pozzolanic activities of seven diverse specimens of Egyptian tuffs taken with standardized proportions of 75:25% (Cement: volcanic tuffs) were investigated. Pozzolanic features of such tuffs are examined comparatively via strength activity index (SAI), TGA, DTA, and the Frattini's test. Chemical composition, petrographic, and XRD analysis were also performed for tuffs samples. The pozzolanic reaction degrees were determined according to the compressive strengths at 7, 28, 60 and 90 days with different replacement ratios (20, 25, 30 and 40%) of tuffs samples. Additionally, the micro-filler effects in mortar and concrete were determined by measuring the heat of hydration in mortar samples and the compressive strength of concrete with different additive ratios for tuffs samples besides, the concrete slump test. The results show that TF6 gives a lower cement heat of hydration value which is less than 270 J/g at 7 days. Also, its performance in concrete is better than silica fume at late strength (28 days) since the concrete index value is 106.2% by compared to the concrete index of silica fume 103.9 and therefore it can be used as an alternative to high price and quality variable silica fume (SF) for producing high-performance green concrete. Due to the good pozzolanic behavior proved by nearly most volcanic tuffs, along with their low cost, this study will be profitable for very auspicious the use of Egyptian volcanic tuffs for developing sustainable and eco‑friendly blended cement. [ABSTRACT FROM AUTHOR]

Because of the COVID-19 outbreak, Mass gathering restrictions were imposed. The lockdown of the Higher Education Institutions was obligatory to save lives. In February 2021 in Egypt, HEIs were allowed to ease the lockdown restrictions on a case-by-case basis gradually. In this paper, we propose a risk evaluation of planned regular mass gathering events during the pandemic, such as students gathering on-campus during indoor exams, by implementing WHO COVID-19 Strategic Preparedness and Response Plan through Intra-Action Review guidance. This one-group posttest-only design study was done on October 6 University campus during indoor students' exams in Giza, Egypt. We conducted IAR to implement the WHO's COVID- 19 SPRP; Country-level coordination; risk communication; surveillance, rapid response teams; points of entry; infection prevention control; laboratories; supply chain; case management; essential health services, and other possible topics. Between February-21, 2021; April-10, 2021, 25,927 students attended the on-campus living exams. Our result suggests that the high level of Readiness–Capacity during mass gatherings will reduce COVID-19 transmission. The most compelling evidence is the significance of synchronization between the ten pillars in preventing COVID-19 transmission. These findings may be used to influence decision-making for continual improvement of the operational planning guidelines during the outbreaks. [ABSTRACT FROM AUTHOR]

This paper presents the earliest evidence for the exploitation of lignite (brown coal) in Europe and sheds new light on the use of combustion fuel sources in the 2nd millennium BCE Eastern Mediterranean. We applied Thermal Desorption/Pyrolysis–Gas Chromatography-Mass Spectrometry and Polarizing Microscopy to the dental calculus of 67 individuals and we identified clear evidence for combustion markers embedded within this calculus. In contrast to the scant evidence for combustion markers within the calculus samples from Egypt, all other individuals show the inhalation of smoke from fires burning wood identified as Pinaceae, in addition to hardwood, such as oak and olive, and/or dung. Importantly, individuals from the Palatial Period at the Mycenaean citadel of Tiryns and the Cretan harbour site of Chania also show the inhalation of fire-smoke from lignite, consistent with the chemical signature of sources in the northwestern Peloponnese and Western Crete respectively. This first evidence for lignite exploitation was likely connected to and at the same time enabled Late Bronze Age Aegean metal and pottery production, significantly by both male and female individuals. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

In this study, a simple method based on non-ionic surfactant polysorbates-80 was used to create mesoporous γ-Al2O3NPs. The properties of the prepared mesoporous alumina nanoparticles (Al2O3NPs) were verified using ATR-FTIR, XRD, SEM, TEM, DLS, and BET surface area analysis. Then, thin-film nanocomposite (TFN) nanofiltration membranes were fabricated by interfacial polymerization of embedded polyamide layers with varied contents (0.01 to 0.15 wt.%) of mesoporous γ-Al2O3NPs. The surface roughness, porosity, pore size, and contact angle parameters of all the prepared membranes were also determined. The performance of the fabricated membranes was investigated under various mesoporous γ-Al2O3NPs loads, time, and pressure conditions. Mesoporous γ-Al2O3NPs revealed an important role in raising both the membrane hydrophilicity and the surface negativity. The addition of 0.03 wt.% mesoporous γ-Al2O3NPs to the TFN membrane increased water flux threefold compared to the TF control (TFC) membrane, with maximum water flux reaching 96.5, 98, 60, and 52 L/(m2.h) for MgSO4, MgCl2, Na2SO4, and NaCl influent solutions, respectively, with the highest salt rejection of 96.5%, 92.2%, 98.4%. The TFN-Al2O3 membrane was also able to soften water and remove polyvalent cations such as Mg2+ with a highly permeable flux. The TFN-Al2O3 membrane successfully removed the hardness of the applied water samples below the WHO limit compared to using merely the TFC membrane. Furthermore, the TFN-Al2O3 nanofiltration membrane unit proved to be a promising candidate for the desalination of real brine like that collected from the Safaga area, Egypt. [ABSTRACT FROM AUTHOR]