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Wyszukujesz frazę "Elsayed, M. A." wg kryterium: Autor

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    Wyświetlanie 1-9 z 9
    Tytuł:
    A Simulation for Detecting Nonlinear Echoes from Microbubbles Packets
    Autorzy:
    Ali, M. G. S.
    Elsayed, N. Z.
    Eid, E. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/177697.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    microbubbles packets
    harmonic component
    acoustic
    radial dynamic
    pressure spectrum
    Opis:
    This work presents a simulation of the response of packets of microbubbles in an ultrasonic pulse-echo scan line. Rayleigh-Plesset equation has been used to predict the echo from numerically obtained radial dynamics of microbubbles. Varying the number of scattering microbubbles on the pulse wave form has been discussed. To improve microbubble-specific imaging at high frequencies, the subharmonic and second harmonic signals from individual microbubbles as well as microbubbles packets were simulated as a function of size and pressure. Two different modes of harmonic generation have been distinguished. The strength and bandwidth of the subharmonic component in the scattering spectrum of microbubbles is greater than that of the second harmonic. The pressure spectra provide quantitative and detailed information on the dynamic behaviour of ultrasound contrast agent microbubbles packet.
    Źródło:
    Archives of Acoustics; 2015, 40, 2; 151-157
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An Approach to Design Broadband Air Backed Piezoelectric Sensor
    Autorzy:
    Ali, M. G. S.
    Elsayed, N. Z.
    Eid, E. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/176360.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    piezoelectric
    equivalent circuits
    impulse response
    frequency response
    matching layers
    z-transform
    Opis:
    In this work, an approach to the design of broadband thickness-mode piezoelectric transducer is presented. In this approach, simulation of discrete time model of the impulse response of matched and backed piezoelectric transducer is used to design high sensitivity, broad bandwidth, and short-duration impulse response transducers. The effect of matching the performance of transmitting and receiving air backed PZT-5A transducer working into water load is studied. The optimum acoustical characteristics of the quarter wavelength matching layers are determined by a compromise between sensitivity and pulse duration. The thickness of bonding layers is smaller than that of the quarter wavelength matching layers so that they do not change the resonance peak significantly. Our calculations show that the −3 dB air backed transducer bandwidth can be improved considerably by using quarter wavelength matching layers. The computer model developed in this work to predict the behavior of multilayer structures driven by a transient waveform agrees well with measured results. Furthermore, the advantage of this this model over other approaches is that the time signal for optimum set of matching layers can be predicted rapidly.
    Źródło:
    Archives of Acoustics; 2015, 40, 1; 3-10
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of environmental and nutritional parameters on the extracellular lipase production by Aspergillus niger
    Autorzy:
    El-Batal, A.I.
    Farrag, A.A.
    Elsayed, M.A.
    El-Khawaga, A.M.
    Powiązania:
    https://bibliotekanauki.pl/articles/11584.pdf
    Data publikacji:
    2016
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Źródło:
    International Letters of Natural Sciences; 2016, 60
    2300-9675
    Pojawia się w:
    International Letters of Natural Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Factors Affecting of Porous Properties of Carbon Gel Microsphere
    Autorzy:
    Elsayed, M. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1194052.pdf
    Data publikacji:
    2015
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    base catalysts
    carbon microsphere
    nitrogen adsorption
    sol-gel polycondensation
    Opis:
    Carbon microsphere with high porosity and surface area were synthesized via the sol-gel polycondensation of resorcinol with formaldehyde in a slightly basic medium and followed by drying and pyrolysis. The effects of different parameters during synthesis were investigated. The porous properties of carbon microsphere were evaluated by nitrogen adsorption method and scanning electron microscopy (SEM). By changing both the catalyst species and resorcinol to catalyst ratio (R/C), it was possible to prepare ultramicroporous carbon sphere with pore size about 1.8 nm. The samples evolve from micro-mesoporous solid (RF-Na2CO3: combination of types I and IV isotherms) with 24.2% micropore to an exclusively microporous material (RF-NH4HCO3: type I isotherm) with 98.7% micropore. The results show that it is possible to tailor the morphology of these materials by varying the initial pH of the precursor’s solution in a narrow range and that the micropore surface area and micropore volume are independent from the initial pH, while the BET surface area vary from 582 m2/g (pH = 3.2) to 680 m2/g (pH = 6). However, as the pH increases over pH = 6 the surface area is decreases. These materials can be used as packing for separation columns or as catalysts supports.
    Źródło:
    World Scientific News; 2015, 13; 80-94
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Proper selection of thermal insulation materials
    Autorzy:
    El-Shiekh, T. M.
    Elsayed, A.A.
    Powiązania:
    https://bibliotekanauki.pl/articles/385057.pdf
    Data publikacji:
    2009
    Wydawca:
    Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
    Tematy:
    thermal insulation
    insulation material
    economic selection
    Opis:
    Thermal insulation plays a key role in the overall energy management picture. It is interesting to consider that by using the insulation, the entire energy requirements of a system are reduced. Since, the main function of insulation is to reduce the heat transfer, the insulation material must have the appropriate characteristic to retard the transport of heat occurred by conduction, convection and radiation. The proper selection and application of various insulation materials are very important in the domain of heat transfer. This paper discusses how to select thermal insulation material and on what basis a decision is made for application, concerning material selection and costs, through brief discussion about major insulation materials, properties, steps for economic selection, applications, economics of insulation and thickness, location, case study and conclusion.
    Źródło:
    Journal of Automation Mobile Robotics and Intelligent Systems; 2009, 3, 2; 42-46
    1897-8649
    2080-2145
    Pojawia się w:
    Journal of Automation Mobile Robotics and Intelligent Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Refined multi-phase-lags theory and Thomson effect on a micropolar thermoelastic medium with voids
    Autorzy:
    Alharbi, Amnah M.
    Abd-Elaziz, Elsayed M.
    Othman, Mohamed I.A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1955005.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    micropolar
    voids
    refined-phase-lags theory
    thomson effect
    normal mode
    analysis
    Opis:
    The problem considered is that of an isotropic, micropolar thermoelastic medium with voids subjected to the Thomson effect. The solution to the problem is presented in the context of the refined multiphase-lags theory of thermoelasticity. The normal mode analysis was used to obtain the analytical expressions of the considered variables. The nondimensional displacement, temperature, microrotation, the change in the volume fraction field and stress of the material are obtained and illustrated graphically. The variations of these quantities have been depicted graphically in the refined-phase-lag theory, Green and Naghdi theory of type II, Lord and Shulman theory and a coupled theory. The effects of the Thomson parameter and phase lag parameters on a homogeneous, isotropic, micropolar thermoelastic material with voids are revealed and discussed. Some particular cases of interest are deduced from the present investigation.
    Źródło:
    Archives of Thermodynamics; 2021, 42, 3; 279--309
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sources of uncertainty for the Determination of Chlorpyrifos by Gas Chromatography Equipped with Flame Photometric Detector
    Autorzy:
    Zalat, O. A.
    Elsayed, M. A.
    Fayed, M. S.
    Abd El Megid, M. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/411973.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    sensitivity
    Minimum detectability
    Chlorpyrifos
    injection
    Opis:
    Analysts are increasingly being required to evaluate the uncertainty associated with methods. Estimating the uncertainty of an analytical result is an essential part of quantitative analysis. This paper discusses the sources of uncertainty of chlorpyrifos determination by gas chromatography equipped with flame photometric detector (GC-FPD). The analysis was performed on HP-5 MS, 30 m x 0.32 mm capillary column with a 0.25 μm stationary film thickness using ultra pure nitrogen (99.9999 %) as a carrier gas at 25 psi constant pressure. The method has been optimized. Factors affecting quantization of chlorpyrifos such as injector temperature, carrier gas inlet pressure, air to hydrogen ratios and initial temperature program have been studied to get the best sensitivity, minimum delectability. The liner range of the detector was from 0.15 ng/ml to 1200 ppm, the minimum detection limit was 0.15 ng/ml and the relative standard deviation was 0.839.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 6; 8-55
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study of the Effect of Air to Fuel ratio Parameter on the Organophosphorus – Pesticide Analysis by GC-FPD
    Autorzy:
    Kilany, A. Y.
    Elsayed, M. A.
    Abd Elmegid, M. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/412130.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    sensitivity
    minimum detectability
    dynamic range
    linear range
    organophosphorus pesticides
    malathion
    dimethoate
    GC/FPD
    Opis:
    In the present contribution, sensitive and precise method for the quantification of Organophosphorus / Pesticides (Malathion and Dimethoate) in nanograms range has been developed. The performance of flame photometric detector (FPD), a selective detector (P&S-mode) that can be used in the analysis of organophosphorus compound, is evaluated in terms of sensitivity, selectivity and reproducibility. The performance of flame photometric detector was strongly depending on the absolute and relative flow rate of air and hydrogen gases. The optimum air-to-fuel ratio for detection of Malathion and Dimethoate was 0.4 and 0.3 (FPD-P mode). At this ratio, low picogram amounts of phosphor can be detected accurately (0.18 pgP) with a wide linear dynamic range of 0.18 pgP to 298 ngP. While, the optimum air-to-fuel ratio, for detection of Malathion and Dimethoate was 0.6 (FPD-S mode). In addition to, the method is precise with 4.5 % relative standard deviation (RSD). In conclusion, it could be proposed that this procedure can be recommended as a suitable method for the quantification of Malathion and Dimethoate in cases of acute poisoning.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 17, 3; 236-248
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Validation of UV Spectrophotometric and HPLC Methods for Quantitative determination of chlorpyrifos
    Autorzy:
    Zalat, O. A.
    Elsayed, M. A.
    Fayed, M. S.
    Abd El Megid, M. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/412092.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    chlorpyrifos
    HPLC
    UV-spectrophotometric
    liner range
    Opis:
    A specific and sensitive HPLC and UV spectrophotometric methodwere developed for determination and analysis of chlorpyrifos. Chromatographic separation was achieved on a 150 mm x 10 mm I.D. reversed phase column Zorbax SB C-18. usingdeionizedwater: acetonitrile in the ratio of 10:90 v/v respectively as mobile phase. The effluent was monitored at 290 and 230 nm. Two sharp peaks were obtained for the solvent and chlorpyrifos at 2.7 and 3.45 min respectively. UV spectrophotometric method was performed at 290 nm using Isopropanol as the solvent. Linear range was 0.025-3500 ppm (r2 = 0.9986 ±0.0009) for HPLC method and 2.229 to 200 ppm (r2 = 0.9988) for UV spectrophotometric method. Validation guidelines and statistical analysis showed that both the methods were precise, accurate, sensitive, and can be used for the routine quality control of chlorpyrifos in waste discharges.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 2; 58-63
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-9 z 9

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