We explored the B-C-O system at pressures in the range 0-50 GPa by ab initio variable-composition evolutionary simulations in the hope of discovering new stable superhard materials. A new tetragonal thermodynamically stable phase B4CO4, space group I4[combining macron], and two low-enthalpy metastable compounds (B6C2O5, B2CO2) have been discovered. Computed phonons and elastic constants show th...

In the present study, heat transfer characteristics, namely, coefficient, Nusselt number, pressure drop, friction factor and performance evaluation criteria are evaluated for water, Al2O3 Al2O3/Cu nanofluids. The effects of Reynolds volume fraction composition nanoparticles in hybrid nanofluid analyzed all characteristics. single particle nanofluids flowing through a plain straight tube which i...

Wettability alteration is one of the most important methods for oil recovery from sandstone and carbonate reservoirs. The effects of salinity, pH, temperature, and chemicals such as surfactants and fatty acids on the alteration of the wettability were described in previous studies. In recent years, attention has been directed to nanoparticles as a wettability alteration agent. The effect of som...

A first-principles study of the vibrational modes of PbTiO3 in the ferroelectric tetragonal phase has been performed at all the main symmetry points of the Brillouin zone ~BZ!. The calculations use the local-density approximation and ultrasoft pseudopotentials with a plane-wave basis, and reproduce well the available experimental information on the modes at the G point, including the LO-TO spli...

In the present study, Computational Fluid Dynamics (CFD) techniques and Artificial Neural Networks (ANN) are used to predict the pressure drop value (Δp ) of Al2O3-water nanofluid in flat tubes. Δp  is predicted taking into account five input variables: tube flattening (H), inlet volumetric flow rate (Qi  ), wall heat flux (qnw  ), nanoparticle volume fraction (Φ) and nanoparticle diameter (dp ...

In this study, novel SiO2- and Al2O3-supported Cu-Fe catalysts are developed for selective hydrogenation of 2-methyl-3-butyne-2-ol to 2-methyl-3-butene-2-ol under mild reaction conditions. TEM, XRD, FTIR studies adsorbed CO TPR-H2 performed characterize the morphology, nanoparticle size, particle distribution, as well electronic state deposited metals in prepared catalysts. The deposition Fe Cu...

This research investigates the effects of addition Fe2O3 and Al2O3 nanoparticles (30, 60 90 ppm) Fe2O3–Al2O3 hybrid to pure diesel fuel on combustion, performance emission characteristics a engine. The results indicated that blends improved combustion (in-cylinder pressure heat release rate), (power, consumption thermal exergy efficiency) showed peak increased by 4% rate was 15% in comparison w...

The purpose of this study was to use a tape casting technique to develop an Al2O3 fiber-reinforced Al2O3-based ceramic material (Al2O3-fiber/Al2O3 composite) into a new type of dental ceramic. The Al2O3-based ceramic used a matrix consisting of 60 wt% Al2O3 powder and 40 wt% SiO2-B2O3 powder. The prepreg sheets of Al2O3-fiber/Al2O3 composite (in which uniaxially aligned Al2O3 fibers were infilt...

The impact of gyrotactic microorganisms in the mixed convection stagnation point flow Cu-Al2O3/water hybrid nanofluid towards an immovable plate is numerically examined. boundary layer equation coupled with energy, nanoparticle volume fraction and conservation equations for are simplified into a set ordinary differential by adopting similarity transformation. validation results good agreement p...

The purpose of this paper is to study the effects use boron nitride (BN) and other conventional nanoparticles (Al2O3, CuO TiO2) on pressure drop heat transfer in a microchannel. governing equations for forced fluid flow were worked out by using fluent computational dynamics (CFD) code. Computational results collected from CFD code Al2O3 as nano-particle compared with numerical values used liter...