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The micropolar fluid model for blood flow through a tapered artery with a stenosis

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Acta.m.chanica Sinica 2008年第6期24卷 637-644页

作者： Kh.S.mekheimer m.A.el Kot Department of mathematics Faculty of ScienceAl-Azhar UniversityNasr CityCairo 11884Egypt Department of mathematics Faculty of EducationSuez Canal UniversitySuezEgypt

a.m.cropolar model for axisymmetric blood flow through an axially nonsymmetreic but radially symmetric mild stenosis tapered artery is presented. To estimate the effect of the stenosis shape, a suitable geometry has been considered such that the axial shape of the stenosis can be changed easily just by varying a parameter （referred to as the shape parameter）. The model is also used to study the effect of the taper angle Ф. Flow parameters such as the velocity, the resistance to flow （the resistance impedance）, the wall shear stress distribution in the stenotic region and its magnitude at the maximum height of the stenosis （stenosis throat） have been computed for different values of the shape parameter n, the taper angle Ф, the coupling number N and the micropolar parameter m. It is shown that the resistance to flow decreases with increasing the shape parameter n and the micropolar parameter m while it increases with increasing the coupling number N. So, the magnitude of the resistance impedance is higher for a.m.cropolar fluid than that for a Newtonian fluid model. Finally, the velocity profile, the wall shear stress distribution in the stenotic region and its magnitude at the maximum height of the stenosis are discussed for different values of the parameters involved on the problem.

关键词： micropolar fluid Blood flow Tapered artery

First-principles prediction of the magnetism of 4f rare-earth-metal-doped wurtzite zinc oxide

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Journal of rare Earths 2014年第8期32卷 715-721页

作者： A.G.el Hachimi H.Zaari A.Benyoussef m.el Yadari A.el Kenz Laboratoire de magnétisme et Physique des Hautes Energies LMPHE (URAC 12) Département de Physique B.P.1014 Faculté des SciencesUniversité Mohammed V-Agdal Institut of Nanomaterials and Nanotechnology Hassan II Academy of Science and Technology Department of Science Moulay Ismail University Faculté Polydisciplinaire

electronic structure and magnetic properties of wurtzite ZnO semiconductor doped with rare earth （rE=La, Ce, Pr, Pm, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb） atoms were studied using spin-polarized density functional theory based on the full-potential linear augmented plane wave （FP-LAPW） method as implemented in the Wien2k code. In this approach the generalized gradient approximation （GGA） was used for the exchange-correlation （XC） potential. Our results showed that the substitution of rE ions in ZnO induced spins polarized localized states in the band gap. moreover, the studied DmSs compounds retained half metallicity at dopant concentration x=0.625%for most of the studied elements, with 100%spin polarization at the Fermi level （EF）. The total magnetic moments of these compounds existed due to rE 4f states present at EF, while small induced magnetic moments existed on other non-magnetic atoms as well. Finally, the energy difference between far and near configurations was investigated. It was found that the room temperature ferromagnetism was possible for rE-doped ZnO at near configuration. Since the rE-rE separation was long enough （far configuration） for magnetic coupling, the system became paramagnetic or antiferromagnetic ground state.

关键词： ZnO rare earths ferromagnetism DmS electronic structure magnetic properties half-metallic rE-doped ZnO FP-LAPW method density functional theory

Transport Properties of Bi_2S_3 Single Crystals

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Journal of materials Science & Technology 2008年第5期24卷 757-760页

作者： H.T.Shaban m.m.Nassary m.S.el-Sadek Physics Department Faculty of ScienceSouth Valley Univ.QenaEgypt.

Bi2S3 single crystals were grown by using a.m.dification of Bridgman method. measurements of the electrical conductivity, Hall effect and thermoelectric power （TEP） were preformed in two crystallographic directions （parallel and perpendicular to the c-axis）. The measurements showed that the electrical conductivity, Hall mobility, and Seebeck coefficient have anisotropic nature. From these measurements some physical parameters were estimated and the crystals showed n-type of conduction mechanism. Also, values of the energy gap were found to be different in the two directions.

关键词： Bi2S3 Hall effect Thermoelectric power electrical conductivity

Origin and geochemical characteristics of beryllium mineralization in the Zabara-Wadi el Gemal region,South Eastern Desert,Egypt

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Acta Geochimica 2024年第6期43卷 1105-1122页

作者： Gehad m.Saleh Farrage m.Khaleal moha.m.d Z.el-Bialy mohamed S.kamar mokhles K.Azer mohamed m.Omar mohamed N.el Dawy a.m.d Abdelaal el Saeed r.Lasheen Nuclear materials Authority El-MaadiP.O.Box 530CairoEgypt 2 Geology DepartmentFaculty of SciencePort Said UniversityPort Said 42522Egypt 3 Geological Sciences DepartmentNational Research CentreCairoEgypt 4 Environmental Sciences DepartmentFaculty of SciencePort Said UniversityPort Said 42522Egypt 5 Geology DepartmentFaculty of ScienceAl-Azhar UniversityP.O.Box 11884CairoEgypt

Beryl is the commercial source of beryllium and several varieties of it are valued as a *** contribute to understanding the mechanism of beryl formation,we carried out detailed geological,petrographical,and geochemical investigations on beryl mineralization occurrences in the Zabara-Wadi el Gemal(Z-WG)*** region is an NW-SE trending tract that includes six berylhosting *** green gem variety of beryl(emerald)is restricted to phlogopite schist,pegmatite,and quartz *** hexagonal emerald crystals are well-developed in phlogopite schist and *** gem variety emerald examined is sodic and *** contains high concentrations of chromophore transition elements ordering Cr(up to 1511 ppm)>V(up to 242 ppm)>Sc(up to 245 ppm),giving rise to its vivid green color,refl ecting mafic-ultramafic source *** the investigated emeralds,the Sikait area contains the highest BeO(av.10.76wt.%)*** compositional variability of emeralds is most likely attributed to the contribution from the host *** is revealed by the examined emerald mineralization,for instance;the Abu rusheid area(one of the best areas exposing rare metal-bearing granitoids)possesses the highest average of trace and rEEs *** contrast,Um kabu emerald has the highest contents of Co(av.20 ppm),Ni(av.299 ppm),mgO(av.8.2wt.%),Fe_(2)O_(3)(av.3.12wt.%),and CaO(avg.3.4wt.%)relative to other areas,which may be linked to contribution of ultramafic rocks exposed *** proposed mechanism we suggest for emerald genesis is metasomatic interaction between felsic intrusions,that are enriched with K,Na,Be,Li,and B,with mafic-ultramafic rocks that are enriched in Cr,V,mg,Fe,and *** interaction is marked by the formation of phlogopite schist,the growth of emerald crystals,and desilicated pegmatite.

关键词： Beryl chemistry Emerald genesis Phlogopite schist Pegmatite Eastern Desert

Separation axioms under crossover operator and its generalized

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International Journal of Biomathematics 2016年第4期9卷 169-191页

作者： m. m. el-Sharkasy m. Shokry Department of mathematics Faculty of Science Tanta University Tanta Egypt Department of Physics and Engineering mathematicsFaculty of Engineering Tanta University Tanta Egypt

The purpose of this work is to construct a new crossover operator using the properties of DNA and rNA by using topological concepts in constructing flexible mathematical models in the field of biomathematics. Also, we investigate and study topological prop- erties of the constructed operators and the associated topological spaces of DNA and rNA. Finally we use the process of exchange for sequence of genotypes structures to construct new types of topological concepts to investigate and discuss several examples and some of their properties.

关键词： DNA and rNA genotypes topology (To, T1, T2)-crossover space.

Vibration suppression in multi-tool ultrasonic machining to multi-external and parametric excitations

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Acta.m.chanica Sinica 2009年第3期25卷 403-415页

作者： m.m.kamel W.A.A.el-Ganaini Y.S.Hamed Department of Engineering mathematics Faculty of Electronic EngineeringMenoufiya University

Ultrasonic machining （USm） is of particular interest for the machining of non-conductive, brittle materials such as engineering ceramics. In this paper, a.m.lti-tool technique is used in USm to reduce the vibration in the tool holder and have reasonable amplitude for the tools. This can be done via dynamic absorbers. The coupling of four nonlinear oscillators of the tool holder and tools representing ultrasonic cutting process are investigated. This leads to a four-degree-of-freedom system subjected to multi-external and multi-parametric excitation forces. The a.m.of this work is to control the tool holder behavior at simultaneous primary, sub-ha.m.nic and internal resonance condition. multiple scale perturbation method is used to obtain the solution up to the second order approximations. The different resonance cases are reported and studied numerically. The stability of the system is investigated by using both phase-plane and frequency response techniques. The effects of the different parameters of the tools on the system behavior are studied numerically. Comparison with the available published work is reported.

关键词： Control Stability Ultrasonic machining (USm)

Vaccination effect on a stochastic epidemic model with healing and relapse

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International Journal of Biomathematics 2024年第1期17卷 29-59页

作者： m.m.Abdeslami L.Basri m.el Fatini I.Sekkak r.Taki Laboratory of Partial Differential Equations Spectral Algebra and Geometry Department of mathematics Faculty of Sciences Ibn Tofail UniversityBP 133KénitraMorocco Centre de recherche en Sante Publique montréal(Québec)H3N 1X9 Canada Departement de Medecine Sociale et Preventive Ecole de SantéPublique de I'Universitéde Montreal 101Avenue du ParcMontréal(Quebec)H3N 1X9Canada EST Sidi Bennour Chouaib Doukkali UniversityEl JadidaMorocco

In this work,we consider a stochastic epidemic model with vaccination,healing and *** prove the existence and the uniqueness of the positive *** establish sufficient conditions for the extinction and the persistence in mean of the stochastic ***,we also establish sufficient conditions for the existence of ergodic stationary distribution to the model,which reveals that the infectious disease will *** graphical illustrations of the approximate solutions of the stochastic epidemic model have been performed.

关键词： Stochastic epidemic model with relapse and healing vaccination extinction persistence in mean markov semigroup stationary distribution

Physio-biochemical and nutrient constituents of peanut plants under bentazone herbicide for broad-leaved weed control and water regimes in dry land areas

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Journal of Arid Land 2020年第4期12卷 630-639页

作者： Hani S SAUDY Ibrahim m el–mETWALLY Goma A ABD el–SAmAD Agronomy Department Faculty of AgricultureAin Shams University68–Hadayek Shoubra 11241CairoEgypt Botany Departments National Research CentreEl–Behos St.Dokki 12622CairoEgypt

The abundance of broad-leaved weeds in peanut fields represents the handicap in weed management programs, since limited specific herbicides can be recommended to control them. moreover, the physio-biochemical constituents and nutritional status in peanut plants as affected by available herbicides, i.e., bentazone under water stress conditions are not well known. Therefore, field trials were conducted during the growing seasons in 2016 and 2017 to investigate the interactional impact of irrigation levels(I_(50), I_(75) and I_(100), representing irrigation by 50%, 75% and 100% of crop evapotranspiration, respectively) and weed control practices(bentazone, bentazone+hoeing once, hoeing twice and weedy check as control) on dominant broad-leaved weeds as well as peanut physiological and agronomic traits. result indicated that the efficiency of weed control for each weeded trea.m.nt under I_(50) significantly equaled with its counterpart under I_(75) or I_(100). Bentazone+hoeing once diminished weed biomass by 89.3% and enhanced chlorophyll content of peanut plants by 51.2%. Bentazone relatively caused a reduction in carotenoides. Hoeing twice and bentazone+hoeing once under I_(100) in both growing seasons as well as hoeing twice under I_(75) in 2017 were the superior combinations for boosting pod yield of peanut plants. Trea.m.nt of bentazone+hoeing once and I_(75) recorded the lowest reduction in N utilization percentage and the highest increase in potassium utilization percentage of peanut plants. eliminating weeds enhanced water use efficiency by 37.8%, 49.6% and 34.7% under I_(50), I_(75) and I_(100), respectively. In conclusion, peanut seems to be tolerant to bentazone at moderate water supply, thus it can be safely used in controlling the associated broad-leaved weeds.

关键词： biochemical traits drought nutritional status peanut productivity weed growth

Isotherm and kinetic studies on the adsorption of humic acid molecular size fractions onto clay minerals

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Acta Geochimica 2019年第6期38卷 863-871页

作者： mohamed E.A.el-Sayed moustafa.m.r.Khalaf James A.rice Department of Chemistry and Biochemistry South Dakota State UniversityBrookingsSD 57007USA Soils Waterand Environmental Research InstituteAgriculture Research CenterEl-GizaEgypt Chemistry Department Faculty of ScienceMinia UniversityEl-Minia 61519Egypt

Humic acid(HA)can adsorb onto mineral surfaces,modifying the physicochemical properties of the ***,understanding the sorption behavior of HA onto mineral surfaces is of particular interest,since the fate and transport of many organic and inorganic contaminants are highly correlated to HA adsorbed onto clay *** to the extreme heterogeneity of HA,the extracted IHSS Leonardite humic acid(LHA)used in this work was fractionated using an ultrafiltration technique(UF)into different molecular size fractions(Fr1,>0.2μm;Fr2,0.2 pm-300,000 daltons;Fr3,300,000-50,000 daltons;Fr4,50,000-10,000 daltons;Fr5,10,000-1000 daltons).Equilibrium and the kinetics of LHA and fraction adsorption onto kaolinite and montmorillonite were *** results demonstrated that the maximum adsorption capacity of LHA,Frl,Fr2,Fr3,Fr4,and Fr5 was 5.99,13.69,10.29,7.02,5.9&and 5.09 on kaolinite while it was 8.29,22.62,13.17,8.91,8.62,and 5.69 on montmorillonite,*** adsorption equilibrium data showed that the adsorption behavior of LHA and its fractions could be described more practically by the Langmuir model than the Freundlich *** rate of humic acid fraction adsorption onto clays increased with decreasing molecular size fraction and increasing carboxylic group ***-first-and second-order models were used to assess the kinetic data and the rate *** results explained that LHA and its fractions adsorption on clay minerals conformed more to pseudosecondo rder.

关键词： kaolinite montmorillonite Leonardite humic acid Humic acid fractions Kinetics Equilibrium