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1.
Lithium-aluminum-cobalt-nickel oxide (LiAlxCoyNi1-x-yO2) particles, generally used as cathode of lithium battery, were prepared by chemical coprecipitation from an aqueous solution of LiOH, AI(NO3)3, Co(NO3)2 and Ni(NO3)2 with NH4OH. XRD, SEM and FTIR were used to examine the effect of nickel content on the product. FHR patterns showed that increase in nickel content decreased the absorption strength of the peak of spinel structure of the product, attributed to the occupation by nickel in the aluminum sites. Particle size and electrical properties of the lithium-aluminum-cobalt-nickel oxide (abbreviated as LACNO) particles were also determined. 相似文献
2.
The electrorheological properties (ER) of some fluids containing particles change extensively under the external electrical
field. This phenomenon is applicable in many industries and equipments, such as clutches and motor driven rotor, which would
transfer the spin to a drive shaft through a thin layer of electrorheological fluid. In this investigation, the effects of
external electrical field on ER properties of non-Newtonian fluids (silicon oil) with the addition of SnO2 and Y2O3 nanoparticles were studied. The ER properties were measured for a wide range of SnO2 and Y2O3 nanoparticle concentrations and DC electrical voltages using concentric cylinder rotary rheometer. Based on the results,
ER properties of nanofluids, e.g., apparent viscosity, shear stress, and yield stress, were enhanced by applying electrical
field and increasing SnO2 and Y2O3 concentrations.
相似文献
S. Gh. EtemadEmail: |
3.
In the present paper, conjugate heat transfer approach has been used to numerically study laminar forced convective heat transfer
characteristics of Al2O3/H2O nanofluid flowing in a silicon microchannel heat sink (MCHS) of rectangular cross-section using thermal dispersion model.
Results are presented in terms of thermal resistance that characterizes MCHS performance. It is observed that use of nanofluid
improves MCHS performance by reducing fin (conductive) thermal resistance. 相似文献
4.
F. Farhadinia A. Sedghi M. T. Nooghani 《Journal of Applied Mechanics and Technical Physics》2017,58(3):454-460
The properties and microstructure of an Al/(Al2O3 + TiB2 + ZrB2) hybrid composite made by using hot pressing of aluminum combined with different amounts of TiB2, ZrB2, and Al2O3 powders are studied. The mechanical properties of the composites are investigated on the basis of microhardness and compression tests. The results show that the microstructure of the composites is uniform and the particles are well distributed in the matrix. 相似文献
5.
This paper presents the numerical study of internal free convection of Al2O3 water nanofluid in vertical annuli. Vertical walls are maintained at constant temperatures and horizontal walls are adiabatic.
Results are validated by experimental data. Effect of nanofluids on natural convection is investigated as a function of geometrical
and physical parameters and particle fractions for aspect ratio of 1 ≤ H/L ≤ 5, Grashof number of 103 ≤ Gr ≤ 105 and concentration of 0 ≤ ϕ ≤ 0.06. More than 330 different numerical cases are investigated to develop a new correlation for the Nusselt number. This
correlation is presented as a function of Nusselt number of base fluid and particle fraction which is a linear decreasing
function of particle fraction. The developed correlation for annuli is also valid for the natural convection of Al2O3 water nanofluid in a square cavity. Furthermore, the effect of the viscosity and conductivity models on the Nusselt number
of nanofluids in cylindrical cavities are discussed. 相似文献
6.
This work is focused on numerical simulations of natural convection heat transfer in Al2O3-water nanofluids using computational fluid dynamics approach. Fluent v6.3 is used to simulate water based nanofluid considering
it as a single phase. Thermo-physical properties of the nanofluids are considered in terms of volume fraction and size of
nanoparticles, size of base fluid molecule and temperature. The numerical values of effective thermal conductivity have also
been compared with the experimental values available in the literature. The numerical result simulated shows decrease in heat
transfer with increase in particle volume fraction. Computed result shows similar trend in increase of Nusselt number with
Relayigh number as depicted by experimental results. Streamlines and temperature profiles are plotted to demonstrate the effect. 相似文献
7.
In this paper, a non-isobaric Marangoni boundary layer flow that can be formed along the interface of immiscible nanofluids
in surface driven flows due to an imposed temperature gradient, is considered. The solution is determined using a similarity
solution for both the momentum and energy equations and assuming developing boundary layer flow along the interface of the
immiscible nanofluids. The resulting system of nonlinear ordinary differential equations is solved numerically using the shooting
method along with the Runge-Kutta-Fehlberg method. Numerical results are obtained for the interface velocity, the surface
temperature gradient as well as the velocity and temperature profiles for some values of the governing parameters, namely
the nanoparticle volume fraction φ (0≤φ≤0.2) and the constant exponent β. Three different types of nanoparticles, namely Cu, Al2O3 and TiO2 are considered by using water-based fluid with Prandtl number Pr =6.2. It was found that nanoparticles with low thermal conductivity,
TiO2, have better enhancement on heat transfer compared to Al2O3 and Cu. The results also indicate that dual solutions exist when β<0.5. The paper complements also the work by Golia and Viviani (Meccanica 21:200–204, 1986) concerning the dual solutions in the case of adverse pressure gradient. 相似文献
8.
V. L. Kovalev A. A. Krupnov M. Yu. Pogosbekyan L. P. Sukhanov 《Moscow University Mechanics Bulletin》2010,65(4):85-89
Several cluster models of oxygen atom adsorption on an Al2O3 surface are constructed on the basis of the density functional method. The performed quantum mechanical computations allow
one to reveal a number of important features of the potential energy surface to describe the heterogeneous catalytic processes
with the use of molecular dynamics methods. The heterogeneous recombination of oxygen atoms is simulated according to the
Eley-Rideal mechanism. It is shown that the potential energy surface should be used with consideration of the internal relaxation
of surface monolayers to correctly describe the process under study. 相似文献
9.
Mohammadhassan Vasheghani Ehsan Marzbanrad Cyrus Zamani Mohamed Aminy Babak Raissi Toraj Ebadzadeh Hadi Barzegar-Bafrooei 《Heat and Mass Transfer》2011,47(11):1401-1405
Thermal conductivity of α-Al2O3 was measured using hot wire method. α-Al2O3 (20 nm in size) was synthesized by microwave method for which, the results were compared with commercially available γ-Al2O3. Thermal conductivity of nanofluids was investigated considering, it is dependency on Al2O3 phase. It was observed that by adding 3 wt% of nano γ-Al2O3 and α-Al2O3 to the engine oil, thermal conductivity increases by 37 and 31%, respectively. The corresponding viscosity increase for the
same amount of nano γ-Al2O3 and α-Al2O3 were 36 and 38%, respectively. It was concluded that the differences in thermal conductivity originate from higher specific
surface area of γ-Al2O3 compared to the α-Al2O3 which is the result of porosity difference, obtained during the synthesis process. 相似文献
10.
Nylon-6 is an important engineering polymer that, in its fully spherulitic (bulk) form, has many applications in gears, rollers,
and other long life cycle components. In 1993, Toyota commercialized a nylon-6/clay nanocomposite out of which it produced
the timing belt cover for the Camry. Although these hybrid nanocomposites show significant improvements in their mechanical
response characteristics, including yield strength and heat distortion temperature, little is known about the degradation
of these properties due to environmental pollutants like NO
x
. Nylon-6 fibers are severely degraded by interaction with NO
x
and other pollutants, showing a strong synergy between applied load and environmental degradation. While the nanocomposites
show a significant reduction in permeability of gases and water due to the incorporation of lamellar clay, their susceptibility
to nondiffusional mechano-chemical degradation is unknown. The fracture toughness of these nylon-6/clay nanocomposites increases,
not as a function of clay content, but as a function of the volume of nylon-6 polymer chains influenced by the clay lamellae
surfaces. Both the clay and the constrained volume offer the nanocomposites some protection from the deleterious effects of
NO
x
. The time-to-failure at a given stress intensity factor as a function of clay content and constrained volume is discussed
along with fracture toughness of the materials. 相似文献
11.
We study the thermal buckling of a simply supported sigmoid functionally graded (SFGM) rectangular plate using first-order shear deformation theory. The S-FGM system consists of ceramic (Al2O3) and metal (Al) phases varying across the plate thickness according to a law described by two power-law functions. The effective properties of the composite are determined by the rule of mixtures, whose implementation is simpler than that of methods of micromechanics. The thermal heating is characterized by a uniform, linear, or sinusoidal temperature distribution across the plate thickness. The effects of the plate aspect ratio, the relative thickness, the gradient index, and the transverse shear on the buckling temperature difference are studied. 相似文献
12.
V. A. Gorelov A. Yu. Kireev S. V. Shilenkov 《Journal of Applied Mechanics and Technical Physics》2005,46(2):160-167
Models of population of some radiating electron-vibrational states of CO, CN, and C2 molecules are developed. The characteristics of radiation in a chemically nonequilibrium flow behind the front of a strong shock wave in a mixture of gases constituting the Martian atmosphere are calculated. The numerical data are compared with experimental results.Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 2, pp. 13–22, March–April, 2005 相似文献
13.
Yu. A. Abzaev V. A. Starenchenko É. V. Kozlov 《Journal of Applied Mechanics and Technical Physics》2005,46(1):94-101
The orientation dependence of the yield stress in Ni3Ge single crystals has been examined both theoretically and experimentally. The positive temperature dependence of the yield stress in the low temperature region is attributed to formation of Kear-Wilsdorf barriers. The forces driving the formation and breakdown of barriers are calculated within the framework of the Hirsch scheme. A distinctive feature of the model proposed is that the barrier is considered on the screw component of the a/2[
01](111) superdislocation in the primary octahedral plane. The major role in barrier formation belongs to anisotropy of elastic moduli, energy of antiphase boundaries in the octahedral plane, shear stresses in the cubic and octahedral planes, and friction-induced stress in the cubic plane. A comparison of predicted values of the driving force of barrier formation and breakdown with experimental values reveals their good agreement. An analysis of the orientation dependence of the driving force of barrier formation in the temperature range T = 77–293 K shows that the dependence
(T) has an extremum for crystals deformed along the [
39] crystallographic direction, which is confirmed experimentally.Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 1, pp. 116–125, January–February, 2005. 相似文献
14.
We study the L
1
stability of multi-dimensional discrete-velocity Boltzmann equations. Under suitable smallness assumption on initial data, we show that bounded mild solutions are L
1
stable. For a stability estimate, we employ Bonys multi-dimensional analysis for total interactions over characteristic planes. 相似文献
15.
Victor Vilarrasa Diogo Bolster Marco Dentz Sebastia Olivella Jesus Carrera 《Transport in Porous Media》2010,85(2):619-639
The injection of supercritical CO2 in deep saline aquifers leads to the formation of a CO2 plume that tends to float above the formation brine. As pressure builds up, CO2 properties, i.e. density and viscosity, can vary significantly. Current analytical solutions do not account for CO2 compressibility. In this article, we investigate numerically and analytically the effect of this variability on the position
of the interface between the CO2-rich phase and the formation brine. We introduce a correction to account for CO2 compressibility (density variations) and viscosity variations in current analytical solutions. We find that the error in
the interface position caused by neglecting CO2 compressibility is relatively small when viscous forces dominate. However, it can become significant when gravity forces
dominate, which is likely to occur at late times of injection. 相似文献
16.
A class of nonlinear elliptic problems driven by p(x)-Laplacian with a nonsmooth locally Lipschitz potential is considered.By applying the version of the nonsmooth three-critical-point theorem,the existence of three solutions to the problems is proved. 相似文献
17.
Yann Brenier 《Archive for Rational Mechanics and Analysis》2009,193(1):1-19
We show that Kruzhkov’s theory of entropy solutions to multidimensional scalar conservation laws (Kruzhkov in Mat Sb (N.S.),
81(123), 228–255, 1970) can be entirely recast in L
2 and fits into the general theory of maximal monotone operators in Hilbert spaces. Our approach is based on a combination
of level-set, kinetic and transport-collapse approximations, in the spirit of previous works by Brenier (in C R Acad Sci Paris
Ser I Math, 292, 563–566, 1981; in J Diff Equ, 50, 375–390, 1983; in SIAM J Numer Anal, 21, 1013–1037; in Methods Appl Anal,
11, 515–532, 2004), Giga and Miyakawa (in Duke Math J, 50, 505–515, 1983), and Tsai et al. (in Math Comp, 72, 159–181, 2003). 相似文献
18.
Dissolution of CO2 into brine is an important and favorable trapping mechanism for geologic storage of CO2. There are scenarios, however, where dissolved CO2 may migrate out of the storage reservoir. Under these conditions, CO2 will exsolve from solution during depressurization of the brine, leading to the formation of separate phase CO2. For example, a CO2 sequestration system with a brine-permeable caprock may be favored to allow for pressure relief in the sequestration reservoir.
In this case, CO2-rich brine may be transported upwards along a pressure gradient caused by CO2 injection. Here we conduct an experimental study of CO2 exsolution to observe the behavior of exsolved gas under a wide range of depressurization. Exsolution experiments in highly
permeable Berea sandstones and low permeability Mount Simon sandstones are presented. Using X-ray CT scanning, the evolution
of gas phase CO2 and its spatial distribution is observed. In addition, we measure relative permeability for exsolved CO2 and water in sandstone rocks based on mass balances and continuous observation of the pressure drop across the core from
12.41 to 2.76 MPa. The results show that the minimum CO2 saturation at which the exsolved CO2 phase mobilization occurs is from 11.7 to 15.5%. Exsolved CO2 is distributed uniformly in homogeneous rock samples with no statistical correlation between porosity and CO2 saturation observed. No gravitational redistribution of exsolved CO2 was observed after depressurization, even in the high permeability core. Significant differences exist between the exsolved
CO2 and water relative permeabilities, compared to relative permeabilities derived from steady-state drainage relative permeability
measurements in the same cores. Specifically, very low CO2 and water relative permeabilities are measured in the exsolution experiments, even when the CO2 saturation is as high as 40%. The large relative permeability reduction in both the water and CO2 phases is hypothesized to result from the presence of disconnected gas bubbles in this two-phase flow system. This feature
is also thought to be favorable for storage security after CO2 injection. 相似文献
19.
We study the L1 stability of classical solutions to the Boltzmann equation for a hard-sphere model, when initial datum is a small perturbation of a vacuum, and tends to zero exponentially fast at infinity in the phase space. For this, we introduce nonlinear functionals measuring potential interactions between particles with different velocities and L1 distance between classical solutions. We use pointwise estimates for a solution and the gain term of a collision operator to control the time-evolution of nonlinear functionals.Dedicated to Marshall Slemrod on the occasion of his 60th birthday 相似文献
20.
Geological storage of anthropogenic CO2 emissions in deep saline aquifers has recently received tremendous attention in the scientific literature. Injected buoyant
CO2 accumulates at the top part of the aquifer under a sealing cap rock. Potential buoyant movement of CO2 has caused some concern that the high-pressure CO2 could breach the seal rock. However, CO2 will diffuse into the brine underneath and generate a slightly denser fluid that may induce instability and convective mixing.
Onset times of instability and convective mixing performance depend on the physical properties of the rock and fluids, such
as permeability and density contrast. We present the novel idea of adding nanoparticles (NPs) to injected CO2 to increase density contrast between the CO2-rich brine and the underlying resident brine and, consequently, decrease onset time of instability and increase convective
mixing. The analyses show that 0.001 volume fraction of NPs added to the CO2 stream shortens onset time of mixing by approximately 80% and increases convective mixing by 50%. If it thus originally takes
5 years for the overlying CO2 to start convective mixing, by adding NPs, onset time of mixing reduces to 1 year, and after initiation of convective mixing,
mixing improves by 50%. A reduction of the CO2 leakage risk ensues. In addition to other metallic NPs, use of processed depleted uranium oxide (DU) as the NPs is also proposed.
DU-NPs are potentially stable and might be safely commingled with CO2 to store in saline aquifers. 相似文献