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Numerical simulation of mHD natural convection flow in a wavy cavity filled by a hybrid Cu-Al2O3-water nanofluid with discrete heating

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Applied mathematics and mechanics(English Edition) 2020年第9期41卷 1345-1358页

作者： C.REVNiC T.GROSAN m.SHEREmET i.POP Faculty of Pharmacy University of Medicine and PharmacyCluj-Napoca 400012Romania Department of mathematics Babes-Bolyai UniversityCluj-Napoca 400084Romania Department of Theoretical mechanics Tomsk State UniversityTomsk 634050Russia

We consider the combined effect of the magnetic field and heat transfer inside a square cavity containing a hybrid nanofluid(Cu-Al2O3-water).The upper and bottom walls of the cavity have a wavy *** temperature of the vertical walls is lower,the third part in the middle of the bottom wall is kept at a constant higher temperature,and the remaining parts of the bottom wall and the upper wall are thermally *** magnetic field is applied under the angleγ,an opposite clockwise *** the numerical simulation,the finite element technique is *** ranges of the characteristics are as follows:the Rayleigh number(10^3≤Ra≤10^5),the Hartmann number(0≤Ha≤100),the nanoparticle hybrid concentration(ϕAl2O3,ϕCu=0,0.025,0.05),the magnetic field orientation(0≤γ≤2π),and the Prandtl number Pr,the amplitude of wavy cavity A,and the number of waviness n are fixed at Pr=7,A=0.1,and n=3,*** comparison with a reported finding in the open literature is done,and the data are observed to be in very good *** effects of the governing parameters on the energy transport and fluid flow parameters are *** results prove that the increment of the magnetic influence determines the decrease of the energy transference because the conduction motion dominates the fluid *** the Rayleigh number is raised,the Nusselt number is increased,*** moderate Rayleigh numbers,the maximum ratio of the heat transfer takes place for the hybrid nanofluid and then the Cu-nanofluid,followed by the *** nature of motion and energy transport parameters has been scrutinized.

关键词： magnetohydrodynamics natural convection hybrid nanofluid heat transfer bottom heater wavy top and bottom enclosure

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Giant mineral deposits：introduction

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Geoscience Frontiers 2016年第3期7卷 299-301页

作者： m.Santosh David i.Groves China University of Geosciences Beijing 100083 China Department of Earth Sciences University of Adelaide SA 5005 Australia Centre for Exploration Targeting UWA Crawley WA 6009 Australia

Giant,and to a lesser extent world-class,mineral deposits are the ultimate exploration targets,with discovery changing the financial bottom line of junior exploration companies and providing long-term resources and re... 详细信息

关键词： REE

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Valorization of AZ91 by the hydrolysis reaction for hydrogen production(Electrochemical approach)

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Journal of magnesium and Alloys 2021年第6期9卷 1942-1953页

作者： S.Al Bacha i.Aubert m.Zakhour m.Nakhl J.L.Bobet LCPm/PR2N(EDST) Lebanese UniversityFaculty of Science II90656 Jdeidet El MetnLebanon Universitéde Bordeaux ICMCBCNRSUMR 5026F-33600 PessacFrance University of Bordeaux CNRSArts et MétiersInstitute of technologyBordeaux INPINRAEI2M BordeauxF-33400 TalenceFrance

The hydrolysis of mg-based materials appears to be an ideal solution for clean energy *** hydrogen was produced by the hydrolysis reaction of a"standard"AZ91 alloy(called AZ91 in the following)in"model"seawater *** milling speeds(i.e.250 rpm and 350 rpm)were tested to enhance the reactivity of *** and AlCl_(3)were used as ball milling *** at higher rotational speed is more energetic,hence it ameliorates the most the hydrolysis performance of *** both milling additives,AlCl_(3)enhances the most the hydrolysis of AZ91 with a generation of 65%of its theoretical H_(2)generation *** best material was obtained by milling AZ91 at 350 rpm with graphite for 2 h followed by a further milling with AlCl_(3)for 2h-a yield of 75%of its theoretical H_(2)generation capacity was reached within a few *** corrosion behavior of milled AZ91 was investigated by anodic polarization and electrochemical impedance spectroscopy(EiS).The calculated electrochemical parameters from EiS fitting of two materials milled under different conditions but with the same milling additive are approximately the *** suggests that,in order to fully evaluate the reactivity of AZ91,hydrolysis,anodic polarization and EiS must be considered.

关键词： Ball milling AZ91 mg_(17)Al_(12) Corrosion Hydrogen Electrochemical impedance spectroscopy

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Ferrofluid nucleus phase transitions in an external uniform magnetic field

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Chinese Physics B 2015年第10期24卷 322-330页

作者： B.m.Tanygin S.i.Shulyma V.F.Kovalenko m.V.Petrychuk Faculty of Radiophysics Taras Shevchenko National University of Kyiv

The phase transition between a massive dense phase and a diluted superparamagnetic phase has been studied by means of a direct molecular dynamics simulation. The equilibrium structures of the ferrofluid aggregate nucleus are obtained for different values of a temperature and an external magnetic field magnitude. An approximate match of experiment and simulation has been shown for the ferrofluid phase diagram coordinates ＂field-temperature＂. The provided phase coexistence curve has an opposite trend comparing to some of known theoretical results. This contradiction has been discussed. For given experimental parameters, it has been concluded that the present results describe more precisely the transition from linear chains to a dense globes phase. The theoretical concepts which provide the opposite binodal curve dependency trend match other experimental conditions： a diluted ferrofluid, a high particle coating rate, a high temperature,and/or a less particles coupling constant value.

关键词： ferrofluid aggregate phase diagram molecular dynamics

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Characterization of some Egyptian serpentinites used as ornamental stones

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Chinese Journal Of Geochemistry 2008年第2期27卷 140-149页

作者： i.S. ismael m.S. Hassan Faculty of Education Suez Canal UniversitySuezEgypt Central Metallurgical Research & Development InstituteP.O. Box 87 HelwanCairoEgypt Faculty of Education Suez Canal UniversitySuez Egypt Central Metallurgical Research&Development InstituteP.O. Box 87 HelwanCairoEgypt

Egypt is characterized by wide occurrence of serpentinites, particularly in the central and southern parts of Eastern Desert. There are several cooperate factors that affect the serpentinites used as ornamental stones. These factors involve mineralogical characteristics (including mineral composition and microstructure parameter), physical properties and mechanical properties. Antigorite is an essential serpentinite mineral, with a minor amount of chrysotile. Talc, carbonates (magnesite and dolomite) and tremolite are the main associated minerals. Quality and quantity of associated minerals such as talc and carbonates (dolomite and magnesite) affect the properties of serpentinites used as ornamental stones. Carbonates are resistant to weathering but suffer from acidic cleaning agents in interior use, whereas serpentinites with a high content of talc used on external faces undergo an increase in volume and a consequent rapid degradation. Studied serpentinites are characterized by relatively small grain size with foliated texture, low water absorption, low porosity, and high abrasion resistance. in the samples studied the uniaxial compressive strength (UCS) varies between 89 and 189 mPa, with an average of 152 mPa. According to the classification of Bell (1992), sample No. B8 is very high in strength while the rest high in strength.

关键词：蛇纹岩装饰材料水分吸收颗粒尺寸

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FRACTiONAL-STEP FiNiTE ELEmENT mETHOD FOR CALCULATiON OF 3-D FREE SURFACE PROBLEm USiNG LEVEL SET mETHOD

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Journal of Hydrodynamics 2006年第6期18卷 742-747页

作者： ZHAO Lan-hao Li Tong-chun WANG Ling HERREROS m. i. PASTOR m. College of Water Conservancy and Hydropower Engineering Hohai University Naniing 210098 China Anhui Survey and Design institute of Water Conservancy and Hydropower Hefei 230022 China CEDEX and E.T.S. de Caminos Madrid Spain

A two-step Taylor-Galerkin fractional-step finite element method, which is of second order accuracy in space and time, was proposed for the three-dimensional free surface problem. With this method, the intermediate velocity was explicitly obtained by neglecting pressure gradient term, and then the velocity was corrected by adding the effects of pressure once the pressure field had been obtained from the pressure Poisson equation. The level set approach was applied to track implicitly the free surface. in order to track the free surface, the transport equation of the level set function was solved at each time step and the level set function is reinitialized through iteration to maintain it as a distance function. The governing equations of the system were discretized by the two- step Taylor-Galerkin method, which is of high-order accuracy and easy to be used. The validity and reliability of this method in this article were proved by two numerical examples.

关键词： level set free surface two steps Taylor-Galerkin fractional step FEm

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Brittle deformation in the Afikpo Basin (Southeast Nigeria): Evidence for a terminal Cretaceous extensional regime in the Lower Benue Trough, Nigeria

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Chinese Journal Of Geochemistry 2009年第4期28卷 369-376页

作者： Odigi m.i. Levi C. Amajor Department of Geology University of Port HarcourtPort Harcourt Nigeria

This paper deals with the regional and structural framework of the Cretaceous rocks in the Afikpo Basin located in the southeastern part of the Lower Benue Trough. Results from regional tectonics are presented together with those of the microtectonic analysis of microfaults in the Owutu-Afikpo-Adadama area in the basin. The Owutu-Afikpo-Adadama ridge at the north-central part of the basin marks the boundary between the Late Cenomanian-Turonian-Conianian sediments and the Campanian-maastrichtian sandstones. This ridge trends N45oE on average and is faulted in three main directions, namely: (1) N-S normal faults; (2) NE-SW strike-slip faults; and (3) NW-SE strike-slip faults. The faulted rocks along these brittle discontinuities are mainly cataclastics with internal fracture cleavage and sigmoidal quartz mosaics that are reminiscent of extensional deformation. The cataclasites often bear slickenside striations. The NE-SW and NW-SE strike-slip faults are the results of the youngest brittle events on the Owutu-Afikpo-Adadama ridge. These faults were reactivated after deposition of the Campanian-maastrichtain sediments (post-depositional faults) and, therefore, are post-maastrichtain. microfault analysis of these fault trends suggests an extensional regime that prevailed in the Lower Benue Trough. These results are of significance because this event is least poorly understood and less documented in contrast to the Cenomanian and Santonian events that affected the older Cretaceous strata in this region.

关键词：白垩纪末期伸展变形尼日利亚盆地海槽脆性变形菲证据

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Hydromagnetic Nanofluid Film Flow over a Stretching Sheet with Prescribed Heat Flux and Viscous Dissipation

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Fluid Dynamics & materials Processing 2022年第5期18卷 1373-1388页

作者： Nourhan i.Ghoneim Ahmed m.megahed international maritime College Oman(imCO) Suhar322Sultanate of Oman Department of mathematics Faculty of ScienceBenha UniversityBenha13518Egypt

Thermal radiative heat transfer through a thin horizontal liquid film of a Newtonian nanofluid subjected to a magnetic field is *** physical boundary conditions are a variable surface heat flux and a uniform concentration along the ***,viscous dissipation is present and concentration is assumed to be influenced by both thermophoresis and Brownian motion *** a similarity method to turn the underlying Partial differential equations into a set of ordinary differential equations(ODEs)and a shooting technique to solve these equations,the skin-friction coefficient,the Nusselt number,and the Sherwood number are *** other things,it is shown that large values of the thermal radiation heat transfer rate,thermal conductivity parameter,and the Brownian motion parameter can enhance the cooling of the sheet.

关键词： Nanofluid thin film variable heat flux viscous dissipation unsteady stretching sheet thermal radiation

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Geochemical characterization of Cretaceous sandstones from the Southern Benue Trough, Nigeria

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Chinese Journal Of Geochemistry 2009年第1期28卷 44-54页

作者： Odigi m.i. Amajor L.C. Department of Geology University of Port Harcourt Port Harcourt Nigeria

Geochemical studies of sandstones from the three lithostratigraphic successions in the southern Benue Trough of Nigeria were undertaken for a geochemical characterization of the sandstones, and to assess their strati-graphic and source evolution. major and trace elements data were obtained from outcrop sandstone samples. The SiO2/Al2O3, Fe2O3/K2O ratios and CaO contents have been used to characterize the Cretaceous sandstones into Al-rich and high and low Fe2O3/K2O ratio sandstones. Results indicate that there are geochemical features that display stratigraphic trends across the succession from the Asu River Group, Eze-Aku Group to the proto-Niger Delta succession which may imply a discontinuous evolution from different source terrains of Precambrian and mesozoic ages that supplied the sediments. The Asu River Group sandstones have lower SiO2, Al2O3, Fe2O3 and higher mgO; the Eze-Aku sandstones have higher TiO2, CaO, alkalis and lower mgO while the proto-Niger Delta sandstones have higher SiO2, Al2O3, Fe2O3 and lower alkalis and CaO. These discontinuities signify the influence of tectonic impulses that af- fected the southern Benue Trough during the Cretaceous time. Changes in ratios of TiO2/Al2O3, Fe2O3, Cr and Zr suggest an increasingly mafic contribution to the depositional basin with time. The chemical index of alteration increases with time, possibly suggesting that a more intense weathering regime in the hinterland developed with time.

关键词：地球化学特征储层沥青烃源岩对比

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Polyurethane Composites Synthesized Using Natural Oil-Based Polyols and Sisal Fibe

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Journal of Renewable materials 2018年第4期6卷 426-437页

作者： S.michalowski m.A.mosiewicki m.Kuran´ska m.i.Aranguren A.Prociak Department of Chemistry and Technology of Polymers Faculty of Chemical Engineering and TechnologyCracow University of TechnologyWarszawska 2431-155CracowPoland instituto de investigaciones en Ciencia y Tecnología de materiales-Universidad Nacional de mar del Plata Consejo Nacional de Investigaciones Científicas y TécnicasAv.J.B.Justo 43027600Mar del PlataArgentina

Elastomeric polyurethanes were prepared from a reference polyurethane system modified with biobased polyols synthesized using rapeseed or palm *** reference material was modified by replacement of the commercial polyol by 10%of biopolyols and also by addition of sisal fibers up to 5 wt%.The higher functionality of the biopolyols increased the crosslinking density of the networks and this was reflected by an increase in hardness and a decrease in water *** effect of the sisal fibers mainly improved the mechanical and thermomechanical properties of the system with rapeseed oil because of good dispersion and strong fiber-matrix *** system containing palm oil polyol corresponded to an initial formulation of high viscosity and,consequently,the resulting composites presented lower densities than the theoretically expected *** results are associated with fiber dispersion problems in the initial reactive mixture.

关键词： Biopolyols palm oil rapeseed oil polyurethane composites

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