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Impedance spectroscopy and DFT/TD-DFT studies of diyttrium trioxide for optoelectronic fields

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Journal of Rare earths 2023年第4期41卷 605-612页

作者： Ali A.Alkathiri A.A.Atta Moamen S.Refat Sonam Shakya A.M.hassanien Saud A.Algarni emad M.A.ahmed Sultan e.Alomariy Mohammed Alsawat Norah Algethami Department of Physics College of ScienceTaif UniversityP.O.Box 11099Taif21944Saudi Arabia Department of Chemistry College of ScienceTaif UniversityP.O.Box 11099Taif21944Saudi Arabia Department of Chemistry Aligarh Muslim UniversityAligarh202002India Department of Physics Faculty of Science and Humanity Studies at Al-QuwayiyahShaqra UniversityAl-Quwayiyah11971Saudi Arabia

Yttrium(Ⅲ)oxide or so-called diyttrium trioxide(Y_2O_3)is an excellent candidate ceramic material for optoelectronic ***,electrical conductivity,and dielectric relaxation properties of bulk yttrium(Ⅲ)oxide were studied.X-ray diffraction(XRD)results indicate that the yttrium(Ⅲ)oxide compound has a crystalline cubic *** transform infrared(FTIR)technique was used to ascertain the chemical structure of the yttrium(Ⅲ)oxide *** spectroscopy was used to analyze frequency-dependent electrical properties as a function of temperature in the range of 303-423 K and frequency range of 0.1 Hz-2 *** spectroscopy parameters such as dielectric constant,dielectric loss,loss factor,electric modulus,and complex impedance of the yttrium(Ⅲ)oxide compound were *** Nyquist plot describes the complex impedance of the yttrium(Ⅲ)oxide for different *** universal Jonscher's power law was used for the analysis of the complex electrical conductivity of the yttrium(Ⅲ)oxide *** is found that the real(σ')and imaginary(σ")parts of the complex conductivity increase with increasing *** exponent frequency(s)equals unity,which confirms that the predominant conduction mechanism is a nearly constant loss(NCL)***/TD-DFT studies using B3LYP/LanL2DZ level of theory were used to provide comparable theoretical data and electronic energy gap of HOMO→LUMO.

关键词： Yttrium(Ⅲ)oxidel Impedance spectroscopy DFT/TD-DFT Rare earths

Modeling natural convection boundary layer flow of micropolar nanofluid over vertical permeable cone with variable wall temperature

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Applied Mathematics and Mechanics(english edition) 2017年第8期38卷 1171-1180页

作者： S.e.ahmed Department of Mathematics Faculty of ScienceSouth Valley UniversityQena 83523Egypt

This paper discusses the natural convection boundary layer flow of a micropo- lax nanofluid over a vertical permeable cone with variable wall temperatures. Non-similax solutions are obtained. The nonlineaxly coupled differential equations under the boundary layer approximations governing the flow axe solved numerically using an efficient, itera- tive, tri-diagonal, implicit finite difference method. Different experimental correlations for both nanofluid effective viscosity and nanofluid thermal conductivity are considered. It is found that as the vortex-viscosity parameter increases, both the velocity profiles and the local Nusselt number decrease. Also, among all the nanoparticles considered in this investigation, Cu gives a good convection.

关键词： micropolar nanofluid non-similar solution cone finite difference method,non-uniform heating

Multifunctional transition and temperature-responsive contact lenses

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Light(Science & Applications) 2023年第12期12卷 2624-2635页

作者： ahmed e.Salih Haider Butt Department of Mechanical engineering Khalifa UniversityAbu DhabiUAE

Smart contact lenses have recently gained traction due to their functionalization as noninvasive diagnostic and therapeutic wearables that can address several ocular ***,multifunctional contact lenses exhibiting UV-transition and temperature-responsive capabilities were developed utilizing chromogenic materials that were integrated simultaneously into poly(2-hydroxyethyl methacrylate)(pHeMA)contact *** functionalities of the contact lenses were optically evaluated in both their activated and non-activated *** contact lenses offered excellent UV and blue light blocking capabilities(~45%)at their inactive *** activated via UV exposure,the transparent lenses darkened instantaneously and absorbed portions of the visible light *** absorption intensity and transient discoloration of the transition lenses relied primarily on the utilized photochromic ***,the temperature-responsive contact lenses exhibited distinct colorimetric variations in response to temperature changes within the physiological range(33-38℃).The maximum sensitivity of the thermochromic lens was 8%transmitted light per Celsius degree *** and morphological analysis indicated the adequacy of the contact ***,the multifunctional contact lenses can be deployed as smart wearables to manage ophthalmic deficiencies that are deterred by UV radiations and variations in ocular surface temperature.

关键词： temperature spectrum material

Laminar MHD natural convection of nanofluid containing gyrotactic microorganisms over vertical wavy surface saturated non-Darcian porous media

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Applied Mathematics and Mechanics(english edition) 2016年第4期37卷 471-484页

作者： S.e.ahmed A.MAHDY Department of Mathematics Faculty of Sciences South Valley University

Magnetohydrodynamic （MHD） bioconvection of an incompressible electrically conducting nanofluid near a vertical wavy surface saturated porous medium containing both nanoparticle and gyrotactic microorganisms is investigated. The nanofluid is represented by a model that includes both Brownian motion and thermophoresis effects. A suitable set of non-dimensional variables are used to transform the governing boundary layer equations into a dimensionless form. The resulting nonlinear system is mapped to the vertical flat plate domain, and a non-similar solution is used to the obtained equations. The obtained non-similar system is then solved numerically using the fourth-order Runge-Kutta method. The influence of various physical parameters on the local Nusselt number, the local Sherwood number, the local density number of the motile microorganisms, the dimensionless velocity, the dimensionless temperature, and the rescaled density of motile microorganisms is studied. It is found that the local Nusselt number, the local Sherwood number, and the local density number of the motile microorganisms decrease by increasing either the Grashof number or the magnetic field parameter.

关键词： wavy surface nanofluid non-Darcy bioconvection boundary layer gyrotactic microorganism porous media

Finite element modeling assumptions impact on seismic response demands of MRF-buildings

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earthquake engineering and engineering Vibration 2018年第4期17卷 821-834页

作者： Shehata e Abdel Raheem ahmed K Abdel Zaher ahmed MA Taha Civil engineering Department Engineering College Taibah University Civil engineering Department Faculty of Engineering Assiut University

Recent seismic events have raised concerns over the safety and vulnerability of reinforced concrete moment resisting frame ＂RC-MRF＂ buildings. The seismic response of such buildings is greatly dependent on the computational tools used and the inherent assumptions in the modelling process. Thus, it is essential to investigate the sensitivity of the response demands to the corresponding modelling assumption. Many parameters and assumptions are justified to generate effective structural finite element（Fe） models of buildings to simulate lateral behaviour and evaluate seismic design demands. As such, the present study focuses on the development of reliable Fe models with various levels of refinement. The effects of the Fe modelling assumptions on the seismic response demands on the design of buildings are investigated. the predictive ability of a Fe model is tied to the accuracy of numerical analysis; a numerical analysis is performed for a series of symmetric buildings in active seismic zones. The results of the seismic response demands are presented in a comparative format to confirm drift and strength limits requirements. A proposed model is formulated based on a simplified modeling approach, where the most refined model is used to calibrate the simplified model.

关键词： RC-MRF buildings design codes provisions seismic design finite element modeling modeling assumptions response demands

Machine learning and data-driven prediction of pore pressure from geophysical logs:A case study for the Mangahewa gas field,New Zealand

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Journal of Rock Mechanics and Geotechnical engineering 2022年第6期14卷 1799-1809页

作者： ahmed e.Radwan David A.Wood ahmed A.Radwan Faculty of Geography and Geology Institute of Geological SciencesJagiellonian UniversityKraków30-387Poland exploration Department Gulf of Suez Petroleum CompanyCairoEgypt DWA energy Limited LincolnUK Department of Geology Faculty of ScienceAl-Azhar UniversityAssiut BranchAssiut71524Egypt

Pore pressure is an essential parameter for establishing reservoir conditions,geological interpretation and drilling *** pressure prediction depends on information from various geophysical logs,seismic,and direct down-hole pressure ***,a level of uncertainty accompanies the prediction of pore pressure because insufficient information is usually recorded in many *** machine learning(ML)algorithms can decrease the level of uncertainty of pore pressure prediction uncertainty in cases where available information is *** this research,several ML techniques are applied to predict pore pressure through the over-pressured eocene reservoir section penetrated by four wells in the Mangahewa gas field,New *** predictions substantially outperform,in terms of prediction performance,those generated using a multiple linear regression(MLR)*** geophysical logs used as input variables are sonic,temperature and density logs,and some direct pore pressure measurements were available at the reservoir level to calibrate the predictions.A total of 25,935 data records involving six well-log input variables were evaluated across the four *** ML methods achieved credible levels of pore pressure prediction *** most accurate models for predicting pore pressure in individual wells on a supervised basis are decision tree(DT),adaboost(ADA),random forest(RF)and transparent open box(TOB).The DT achieved root mean square error(RMSe)ranging from 0.25 psi to 14.71 psi for the four *** trained models were less accurate when deployed on a semi-supervised basis to predict pore pressure in the other *** two wells(Mangahewa-03 and Mangahewa-06),semi-supervised prediction achieved acceptable prediction performance of RMSe of 130—140 psi;while for the other wells,semi-supervised prediction performance was reduced to RMSe>300 *** results suggest that these models can be used to predict pore pressure in nearby locat

关键词： Machine learning(ML) Pore pressure Overburden Well-log derived predictions Overpressure

exploring tree diversity and stand structure of savanna woodlands in southeastern Sudan

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Journal of Arid Land 2020年第4期12卷 609-617页

作者： ahmed M M HASOBA ahmed A H SIDDIG Yousif e YAGOUB Faculty of Forest Sciences and Technology University of GeziraMadani 22212Sudan Faculty of Forestry University of KhartoumKhartoum North 13314Sudan Department of environmental Conservation University of Massachusetts AmherstAmherst 01003USA

Savanna woodlands in Sudan host great biodiversity, provide a plethora of ecosystem goods and services to local communities, and sustain numerous ecological functions. Although the importance of the Acacia trees in these areas is well known, up-to-date information about these woodlands' diversity is limited and changes in their woody vegetation composition, density, diversity and relative frequency are not monitored over time. This study explored tree diversity and stand stage structure in Nuara Reserved Forest, a typical savanna woodland ecosystem in southeastern Sudan. A total of 638 circular sample plots(1000 m^2 for each) were established using a systematic sampling grid method. The distance between plots was 200 m. In each plot, all living trees with diameter at breast height(DBH) ≥5.00 cm were identified and counted, and their DBH values were recorded. From these data, tree composition, diversity, density and stage structure were assessed. There were 12,259 individual trees representing four species(Acacia seyal, Balanites aegyptiaca, Acacia Senegal and Acacia mellifera) that belong to two families. The dominant species was Acacia seyal. Average tree density was 191 trees/hm^2 and the Shannon-Weiner index for trees diversity was 0.204. Overall, young trees comprised 86.30% of the forest. The state of tree richness and density in the study area was low compared to other similar environments in the region and around the world. We recommended adoption of a proper management system that includes monitoring of woody vegetation diversity in this forest, and management actions to enhance tree diversity and sustain ecosystem services to local communities. In addition to care for the dominant Acacia seyal stands, more attention and conservation should be devoted to reestablishing Acacia senegal and Acacia mellifera trees because of their high ecological and economic values for local communities.

关键词： species diversity stand structure savanna woodland ecosystem forest monitoring forest management ecosystem services Nuara Reserved Forest

Glycerol use in dairy diets:A systemic review

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Animal Nutrition 2019年第3期5卷 209-216页

作者： ahmed e.Kholif Dairy Science Department National Research Centre

There is an increasing interest in the production of biodiesel as bio-renewable fuel source,with numerous biofuel byproducts becoming *** annual productions of biodiesel and crude glycerol were 34.5 and 3.8 billion liters,respectively,in 2016 and that of biodiesel is expected to reach 41 billion liters in *** is a sugar alcohol without a color or odor,but with a sweet taste and high solubility index in *** support the use of glycerol at low levels ranging from 5% to 8% of the diet dry matter as a transition cow *** of glycerol increases serum glucose and decreases ketone *** is very rapidly fermented in the rumen to propionate and butyrate,at the expense of acetate,resulting in a decreased milk *** glycerol is highly fermented in the rumen,it requires an adaptation period at the beginning of *** of glycerol in the diet of lactating animals was paralleled with a decreased or an unaffected feed intake in most *** ruminal environment to enhance nutrient digestibility was observed in many experiments;however,others observed reduced digestion of dietary fiber with feeding ***,lowered,or unaffected milk production and composition were observed with the administration of glycerol in lactating animal diets;however,in most cases,glycerol decreased milk fat *** inconsistencies between results of experiments are due to the level and the purity of glycerol,diets,production stage of the animals,and other ***,further research should be conducted to establish the efficacy of different levels,purity and administration periods of glycerol,and production stage of dairy animals fed glycerol-based or supplemented diets.

关键词： Biodiesel byproducts Feed utilization Glycerol Milk production and composition Ruminal fermentation

The Reflection of Magneto-Thermoelastic P and SV Waves at a Solid Half Space Using Dual-Phase-Lag Model

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Advances in Applied Mathematics and Mechanics 2011年第6期3卷 745-758页

作者： ahmed e.Abouelregal Mathematics Department Faculty of ScienceMansoura UniversityMansoura 35516Egypt

The dual-phase-lag heat transfer model is employed to study the reflection phenomena of P and SV waves from a surface of a semi-infinite magnetothermoelastic *** ratios of reflection coefficients to that of incident coefficients are obtained for P-and SV-wave *** results for partition of the energy for various values of the angle of incidence are computed numerically under the stress-free and rigidly fixed thermally insulated *** reflection coefficients are depending on the angle of incidence,magnetic field,phase lags and other material *** show that the sum of energy ratios is unity at the *** results are discussed and depicted graphically.

关键词： Reflection dual-phase-lag model thermoelastici waves partition of energy magneto-thermoelasticity