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Wyszukujesz frazę "Ahmed, A." wg kryterium: Autor

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    Wyświetlanie 1-12 z 12
    Tytuł:
    Compact Transverse Electric Silicon-on-Insulator Mode Converter for Mode-Division Multiplexer
    Autorzy:
    Sharaf, Mohamed H.
    El-Mashade, Mohamed B.
    Emran, Ahmed A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2055263.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    integrated optics
    silicon-on-insulator waveguide
    WDM & MDM systems
    perturbation theory
    integrated optical
    devices
    hybrid modes
    guided waves
    Opis:
    On-chip optical-interconnect technology emerges as an attractive approach due to its ultra-large bandwidth and ultra-low power consumption. Silicon-on-insulator (SOI) wire waveguides, on the other hand, have been identified to potentially replace copper wires for intra-chip communication. To take advantage of the wide bandwidth of SOI waveguides, wavelengthdivision multiplexing (WDM) has been implemented. However, WDM have inherent drawbacks. Mode-division multiplexing (MDM) is a viable alternative to WDM in MIMO photonic circuits on SOI as it requires only one carrier wavelength to operate. In this vein, mode converters are key components in on-chip MDM systems. The goal of this paper is to introduce a transverse electric mode converter. The suggested device can convert fundamental transverse electric modes to first-order transverse electric ones and vice versa. It is based on small material perturbation which introduces gradual coupling between different modes. This device is very simple and highly compact; the size of which is 3 μm². Mathematical expressions for both the insertion loss and crosstalk are derived and optimized for best performance. In addition, three-dimensional finite-difference time-domain (3D-FDTD) simulations are performed in order to verify the mathematical model of the device. Our numerical results reveal that the proposed device has an insertion loss of 1.2 dB and a crosstalk of 10.1 dB. The device’s insertion loss can be decreased to 0.95 dB by adding tapers to its material perturbation.
    Źródło:
    International Journal of Electronics and Telecommunications; 2022, 68, 2; 275--280
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimal placement and sizing of FACTS devices based on Autonomous Groups Particle Swarm Optimization technique
    Autorzy:
    Shehata, Ahmed A.
    Refaat, Ahmed
    Ahmed, Mamdouh K.
    Korovkin, Nikolay V.
    Powiązania:
    https://bibliotekanauki.pl/articles/1841330.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    active power losses minimization
    AGPSO
    FACTS
    MFO
    PSO
    SVC
    minimalizacja strat mocy czynnej
    Opis:
    This paper presents the application of Flexible Alternating Current Transmission System (FACTS) devices based on heuristic algorithms in power systems. The work proposes the Autonomous Groups Particle Swarm Optimization (AGPSO) approach fort he optimal placement and sizing of the Static Var Compensator (SVC) to minimize thetotal active power losses in transmission lines. A comparative study is conducted with other heuristic optimization algorithms such as Particle Swarm Optimization (PSO), Time-varying Acceleration Coefficients PSO (TACPSO), Improved PSO (IPSO), Modified PSO(MPSO), and Moth-Flam Optimization (MFO) algorithms to confirm the efficacy of the proposed algorithm. Computer simulations have been carried out on MATLAB with the MATPOWER additional package to evaluate the performance of the AGPSO algorithm on the IEEE 14 and 30 bus systems. The simulation results show that the proposed algorith moffers the best performance among all algorithms with the lowest active power losses and the highest convergence rate.
    Źródło:
    Archives of Electrical Engineering; 2021, 70, 1; 161-172
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Using Diversity for Classifier Ensemble Pruning : an Empirical Investigation
    Autorzy:
    Ahmed, M. A. O.
    Didaci, L.
    Lavi, B.
    Fumera, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/375851.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    multiple classifier systems
    ensemble pruning
    diversity measures
    Opis:
    The concept of `diversity' has been one of the main open issues in the field of multiple classifier systems. In this paper we address a facet of diversity related to its effectiveness for ensemble construction, namely, explicitly using diversity measures for ensemble construction techniques based on the kind of overproduce and choose strategy known as ensemble pruning. Such a strategy consists of selecting the (hopefully) more accurate subset of classifiers out of an original, larger ensemble. Whereas several existing pruning methods use some combination of individual classifiers' accuracy and diversity, it is still unclear whether such an evaluation function is better than the bare estimate of ensemble accuracy. We empirically investigate this issue by comparing two evaluation functions in the context of ensemble pruning: the estimate of ensemble accuracy, and its linear combination with several well-known diversity measures. This can also be viewed as using diversity as a regularizer, as suggested by some authors. To this aim we use a pruning method based on forward selection, since it allows a direct comparison between different evaluation functions. Experiments on thirty-seven benchmark data sets, four diversity measures and three base classifiers provide evidence that using diversity measures for ensemble pruning can be advantageous over using only ensemble accuracy, and that diversity measures can act as regularizers in this context
    Źródło:
    Theoretical and Applied Informatics; 2017, 29, 1-2; 25-39
    1896-5334
    Pojawia się w:
    Theoretical and Applied Informatics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Potential toxicity assessment of novel selected pesticides against sand termite, Psammotermes hypostoma Desneux workers (Isoptera: Rhinotermitidae) under field conditions in Egypt
    Autorzy:
    Ahmed, M.A.I.
    Eraky, E.-S.A.
    Mohamed, M.F.
    Soliman, A.-A.S.
    Powiązania:
    https://bibliotekanauki.pl/articles/66459.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Opis:
    The sand termite, Psammotermes hypostoma Desneux is a major pest in the New Valley Governorate, Egypt. Great efforts have been taken to control the pest. We evaluated the toxicity of four selected neonicotinoids [acetamiprid (20% SP), imidacloprid (20% SL), thiamethoxam (18.6% SC), and thiamethoxam (40% WG)], and one organophosphate pesticide [chlorpyrifos (48% EC)] against P. hypostoma workers. The investigation was done under field conditions, using the palm fronds method. However, the reduction percentages in palm fronds was recorded as the height of the sandy clay formed by termite workers on palm frond surfaces, when the fronds had been treated with a different concentration of each pesticide. The results were recorded after 15, 30, 45, and 60 days. Chlorpyrifos (48% EC) was considered the most potent pesticide among all the pesticides tested, but acetamiprid (20% SP) was considered the most toxic among the neonicotinoid pesticides tested. Moreover, the formulation of thiamethoxam (18.6% SC) was more powerful than thaimethoxam (40% WG). Furthermore, the reduction percentages on palm fronds increased significantly with an increase of the exposure period (from 15 to 60 days), as a result of the surface foraging activity of the sand termite workers. These results are given as unique and encouraging trends in controlling sand termites in Egypt.
    Źródło:
    Journal of Plant Protection Research; 2015, 55, 2
    1427-4345
    Pojawia się w:
    Journal of Plant Protection Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Improvement Optical and Electrical Characteristics of Thin Film Solar Cells Using Nanotechnology Techniques
    Autorzy:
    Thabet, Ahmed
    Abdelhady, Safaa
    Ebnalwaled, A.A.
    Ibrahim, A. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/226062.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    thin film
    nanoparticles
    nanocomposites
    energy conversion
    optical
    plasmonic
    solar cells
    Opis:
    This work presents a theoretical study for the distribution of nanocomposite structure of plasmonic thin-film solar cells through the absorber layers. It can be reduced the material consumption and the cost of solar cell. Adding nanometallic fillers in the absorber layer has been improved optical, electrical characteristics and efficiency of traditional thin film solar cells (ITO /CdS/PbS/Al and SnO2/CdS/CdTe/Cu) models that using sub micro absorber layer. Also, this paper explains analysis of J-V, P-V and external quantum efficiency characteristics for nanocomposites thin film solar cell performance. Also, this paper presents the effect of increasing the concentration of nanofillers on the absorption, energy band gap and electron-hole generation rate of absorber layers and the effect of volume fraction on the energy conversion efficiency, fill factor, space charge region of the nanocomposites solar cells.
    Źródło:
    International Journal of Electronics and Telecommunications; 2019, 65, 4; 625-634
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Microbial degradation of lignocellulosic biomass: discovery of novel natural lignocellulolytic bacteria
    Autorzy:
    Ahmed, S.
    Rahman, S.
    Hasan, M.
    Paul, N.
    Sajib, A.A.
    Powiązania:
    https://bibliotekanauki.pl/articles/81125.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    lignocellulose
    microbial degradation
    biofuel
    cellulose
    lignin
    hemicellulose
    lignocellulolytic bacteria
    Chryseobacterium gleum
    Źródło:
    BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2018, 99, 2
    0860-7796
    Pojawia się w:
    BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of Some Inorganic Anions and Organic Compounds as Corrosion Inhibitors of Cu-Zn Alloys in H2SO4 and HNO3 Solutions
    Autorzy:
    Ahmed, Amal S. I.
    Ghanem, Wafaa A.
    Hussein, Walaa A.
    Gaber, Ghalia A.
    Powiązania:
    https://bibliotekanauki.pl/articles/351226.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Cu-Zn alloys
    oxy-acid solution
    inhibition efficiency
    inorganic anions
    organic compounds
    Opis:
    Evaluation of inorganic and organic compounds as corrosion inhibitors of Cu-Zn alloys in H2 SO4 and HNO3 solutions was studied using potentiodynamic and impedance spectroscopy along with scanning electron microscope (SEM) and energy dispersive X-Ray analyzer (EDX) investigations. The corrosion inhibition of Cu-Zn alloys was investigated in oxy acid solutions using inorganic potassium permanganate and di-hydrogen phosphate, amino acids as environmentally safe materials, commercial cooling water, and green tea extracts. Both potassium permanganate and di-hydrogen phosphate improve the corrosion resistance of Cu-Zn alloys. Phosphate appears more effective as corrosion inhibitor for Cu-Zn alloys than permanganate. The inhibition efficiency (IE%) of the different amino acids such as valine, leucine and lysine was also calculated. The experimental results have shown that amino acid-like lysine can be used as an efficient corrosion inhibitor for the Cu-Zn alloys in oxy acid solutions. This may be due to the presence of two amino groups adsorbed together. For lysine, inhibition efficiency, IE%, of ~87 and ~59 is for H2SO4 and ~96.3 and 54.9 for HNO3 for alloy I and II respectively are observed. Due to the composition of green water have a great effect on the inhibition action on Cu-Zn alloys which reaching 91.8 and 96.5% for Alloy I and 95.4 and 87.1% for Alloy II in 0.5 M H2 SO4 and HNO3 respectively. Although benzotriazole, in cooling water, is an excellent inhibitor suitable for use in a wide variety of environments, it has toxic properties. So, much of the recent researches have focused on formulating new and more environmentally acceptable preservation solutions. The green tea, as plant extract, will be very environmentally friendly. The EDX confirm the formation of a protective layer on the Cu-Zn alloys containing aluminum in Alloy II. This sequence reflects the beneficial effects of Al in Alloy II. The presence of 2.43% Al in Alloy II improves the corrosion resistance due to the formation of thin, transparent, stable and self-healing Al2 O3 layer. This confirmed the results obtained from the potentiodynamic polarization measurements and EIS methods.
    Źródło:
    Archives of Metallurgy and Materials; 2020, 65, 2; 639-651
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Thermodynamic assessment of thermochemical cycle for hydrogen production based on water decomposition with binary copper chlorine couple
    Autorzy:
    Benbrika, Omar
    Bensenouci, Ahmed
    Tegar, Mohamed
    Ismail, Kamal R.A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2204067.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    hydrogen production
    thermochemical process
    copper-chlorine cycle
    water
    dissociate
    exergy
    energy
    analys
    Opis:
    The present study aims at investigating and simulating the hydrogen cycle production at low temperatures using thermochemical reactions. The cycle used in this work is based on the dissociation of water molecules depending on a copper chlorine couple. Furthermore, the proposed method uses mainly thermal energy provided by a solar thermal field. This proposed cycle differs from what is found in the literature. However, most of the thermochemical cycles for hydrogen production work at quite high temperatures which is a technical challenge. Therefore, the maximum temperature used in the present cycle is limited to 500◦C. A thermodynamic analysis based on both the first and second laws is performed to evaluate the energy, exergy and efficiency of each reaction as well as the overall exergetic efficiency of the system. Furthermore, a parametric study is conducted to figure out the impact of the surrounding temperatures on the overall exergetic efficiency using commercial energy simulation software. The results show that the cycle can achieve an exergy efficiency of 30.5%.
    Źródło:
    Archives of Thermodynamics; 2022, 43, 4; 109--133
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Allelopathic efficiency of Eruca sativa in controlling two weeds associated with Pisum sativum plants
    Autorzy:
    El-Wakeel, M.A.
    Ahmed, S.E.-D.A.E.-G.
    El-Desoki, E.R.
    Powiązania:
    https://bibliotekanauki.pl/articles/66437.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Opis:
    Allelopathy is a complex phenomenon which depends on allelochemical concentrations. So, two pot experiments were carried out to investigate the allelopathic effect of alcoholic fresh shoot extract of Eruca sativa (foliar spray) and E. sativa shoot powder (mixed with soil) on Pisum sativum plants and two associated weeds, Phalaris minor and Beta vulgaris. The experiments were conducted in the greenhouse of the National Research Centre, Giza, Egypt during two successive winter seasons (2016–2017 and 2017–2018). Ten treatments were applied in this study. Four treatments were applied before sowing, that E. sativa shoot powder was mixed with the soil at rates of 15, 30, 45 and 60 g ⋅ pot–1. The other four treatments of E. sativa alcoholic fresh shoot extract were sprayed twice on both plants and weeds at 5, 10, 15 and 20% (w/v) concentrations. Additionally, two untreated treatments, healthy (P. sativum only) and unweeded (untreated infested P. sativum plants with weeds) were applied for comparison. The results indicated that both alcoholic extracts and powder reduced growth of both weeds. Moreover, there was a direct relationship between concentration and weed reduction. Eruca sativa alcoholic extracts increased yield parameters of P. sativum plants. The maximum yield attributes were recorded by spraying of E. sativa alcoholic extract at 20%. On the other hand, it was clearly noticed that the high powder rates affected negatively P. sativum yield parameters. But the lowest powder rate (15 g ⋅ pot–1) stimulated P. sativum yield parameters as compared to unweeded treatment. Chemical analysis of E. sativa shoot powder ensured that the abundant amount of glucosinolates (9.6 μmol ⋅ g–1) and phenolic compounds (46.5 mg ⋅ g–1) may be responsible for its allelopathic effect. In conclusion, spraying of alcoholic fresh shoot extract of E. sativa at 20% (w/v) and mixing E. sativa shoot powder at 15 g · pot–1can be applied as natural bioherbicides for controlling weeds.
    Źródło:
    Journal of Plant Protection Research; 2019, 59, 2
    1427-4345
    Pojawia się w:
    Journal of Plant Protection Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A two-stage stochastic programming approach for production planning system with seasonal demand
    Autorzy:
    Mahmoud, Asmaa A.
    Aly, Mohamed F.
    Mohib, Ahmed M.
    Afefy, Islam H.
    Powiązania:
    https://bibliotekanauki.pl/articles/952860.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    process manufacturing system
    two-stage stochastic programming
    sampling average approximation
    Opis:
    Seasonality is a function of a time series in which the data experiences regular and predictable changes that repeat each calendar year. Two-stage stochastic programming model for real industrial systems at the case of a seasonal demand is presented. Sampling average approximation (SAA) method was applied to solve a stochastic model which gave a productive structure for distinguishing and statistically testing a different production plan. Lingo tool is developed to obtain the optimal solution for the proposed model which is validated by Math works Matlab. The actual data of the industrial system; from the General Manufacturing Company, was applied to examine the proposed model. Seasonal future demand is then estimated using the multiplicative seasonal method, the effect of seasonality was presented and discussed. One might say that the proposed model is viewed as a moderately accurate tool for industrial systems in case of seasonal demand. The current research may be considered a significant tool in case of seasonal demand. To illustrate the applicability of the proposed model a numerical example is solved using the proposed technique. ANOVA analysis is applied using MINITAB 17 statistical software to validate the obtained results.
    Źródło:
    Management and Production Engineering Review; 2020, 11, 1; 31--42
    2080-8208
    2082-1344
    Pojawia się w:
    Management and Production Engineering Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Etiology and pathology of epidemic outbreaks of avian influenza H5N1 infection in Egyptian chicken farms
    Autorzy:
    Ali, A.
    Elmowalid, G.
    Abdel-Glili, M.
    Sharafeldin, T.
    Abdallah, F.
    Mansour, F.
    Nagy, A.
    Ahmed, B.
    Abdelmoneim, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/30849.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Opis:
    Epidemic outbreaks of avian influenza (AI) virus H5N1 have been frequently reported in Egypt during the last nine years. Here we investigate the involvement of AI H5N1 in outbreaks of acute respiratory disease that occurred in several commercial chicken farms in Egypt in 2011, and we describe to the pathology caused by the virus in the course of the outbreak. Twenty-one chicken farms with history of acute respiratory symptoms and high mortalities were screened for AI H5N1. Virus identification was based on hemagglutination inhibition test, and PCR detection and sequencing of the hemagglutinin and neuraminidase genes. Virus distribution was determined by immunohistochemical staining of AI antigens in organs of infected birds. Standard H&E staining was performed for histological examination of affected organs. Eighty-one % of the examined birds, representing 100% of the screened farms, were positive for AI H5N1 virus. Phylogenetic analysis of the hemagglutinin and neuraminidase genes of the isolated virus reveals its affiliation to clade 2.2.1. Viral antigens were localized in the endothelial cells of the heart, liver, lungs and skin, where pathological lesions including congestion, hemorrhages, multifocal inflammation and necrosis were concurrently observed. According to the pattern of the viral antigen and lesion distribution in the visceral organs, we suggest cardiovascular and circulatory failures as the probable cause of death during these outbreaks. In conclusion, the present study further confirms the epidemic status of AI H5N1 virus in Egypt and reveals the highly pathogenic nature of the local isolates.
    Źródło:
    Polish Journal of Veterinary Sciences; 2015, 18, 4
    1505-1773
    Pojawia się w:
    Polish Journal of Veterinary Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A review of the importance of synchrophasor technology, smart grid, and applications
    Autorzy:
    Baba, Maveeya
    Nor, Nursyarizal B.M.
    Sheikh, Aman
    Nowakowski, Grzegorz
    Masood, Faisal
    Rehman, Masood
    Irfan, Muhammad
    Arefin, Ahmed Amirul
    Kumar, Rahul
    Baba, A. Momin
    Powiązania:
    https://bibliotekanauki.pl/articles/2173713.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    phasor measurement unit
    PMU
    micro-PMU
    Global Positioning System
    GPS
    optimal PMU placement
    smart grid
    SG
    jednostka pomiaru fazorów
    mikro-PMU
    globalny system pozycjonowania
    optymalne rozmieszczenie PMU
    sieć inteligentna
    Opis:
    The electrical network is a man-made complex network that makes it difficult to monitor and control the power system with traditional monitoring devices. Traditional devices have some limitations in real-time synchronization monitoring which leads to unwanted behavior and causes new challenges in the operation and control of the power systems. A Phasor measurement unit (PMU) is an advanced metering device that provides an accurate real-time and synchronized measurement of the voltage and current waveforms of the buses in which the PMU devices are directly connected in the grid station. The device is connected to the busbars of the power grid in the electrical distribution and transmission systems and provides time-synchronized measurement with the help of the Global Positioning System (GPS). However, the implementation and maintenance cost of the device is not bearable for the electrical utilities. Therefore, in recent work, many optimization approaches have been developed to overcome optimal placement of PMU problems to reduce the overall cost by providing complete electrical network observability with a minimal number of PMUs. This research paper reviews the importance of PMU for the modern electrical power system, the architecture of PMU, the differences between PMU, micro-PMU, SCADA, and smart grid (SG) relation with PMU, the sinusoidal waveform, and its phasor representation, and finally a list of PMU applications. The applications of PMU are widely involved in the operation of power systems ranging from power system control and monitor, distribution grid control, load shedding control and analyses, and state estimation which shows the importance of PMU for the modern world.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 6; art. no. e143826
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-12 z 12

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