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41.
On Solutions of Some Non-Linear Differential Equations Arising in Newtonian and Non-Newtonian Fluids
Mohyuddin M. R. Hayat T. Mahomed F. M. Asghar S. Siddiqui A. M. 《Nonlinear dynamics》2004,35(3):229-248
Some steady as well as unsteady solutions of the equations of motion for an incompressible Newtonian and non-Newtonian (second-grade)
fluids are obtained by applying different methods including the Lie symmetry group method. The flows considered are axially
symmetric with the swirling motion, and the governing equations for second-grade fluid flow have been modeled. Expressions
for streamlines, velocity and vorticity components are constructed explicitly in each case. Exact analytical solutions in
second-grade fluid are obtained and compared with the corresponding viscous solutions. 相似文献
42.
S. Nasir G. Asghar Muhammad Ali Malik M. Anis-ur-Rehman 《Journal of Sol-Gel Science and Technology》2011,59(1):111-116
Zinc doped nickel ferrite nanoparticles having the general formula Ni1−xZnxFe2O4 (x = 0.1, 0.2, 0.3, 0.4, 0.5) were prepared with simplified sol–gel method. The structural and dielectric properties of these
samples sintered at 750 ± 5 °C were studied. X-ray diffraction patterns confirm the single phase spinel structure for prepared
samples. The scanning electron microscope images indicated that the particle size of the samples lies in the nanometer regime.
The dielectric constant (εr) and dielectric loss tangent (tan δ) of nanocrystalline nickel ferrites were investigated as a function of frequency and
Zn concentration. The dependence of εr and tan δ on the frequency of the alternating applied electric field is in accordance with the Maxwell–Wagner model. The
prepared samples have a lowest dielectric constant compared to the already reported samples of the same composition to the
best of our knowledge. The effect of Zn doping on the dielectric properties of nickel ferrites is explained on the basis of
cations distribution in the crystal structure. 相似文献
43.
A series of 1,3,5-triaryl-2-pyrazolines was synthesized by dissolving the corresponding 4-alkoxychalcones in glacial acetic acid containing a few drops of concentrated hydrochloric acid. This step was followed by the addition of (3,4-dimethylphenyl) hydrazaine hydrochloride. Finally the target compounds were precipitated by pouring the reaction mixture onto crushed ice. The structures of the synthesized compounds were established by physicochemical and spectroscopic methods. The 1,3,5-triaryl-2-pyrazolines bearing homologous alkoxy groups were found to possess fluorescence properties in the blue region of the visible spectrum when irradiated with ultraviolet radiation. The fluorescent behavior of these compounds was studied by UV-Vis and emission spectroscopy, performed at room temperature. 相似文献
44.
Lie??s linearizability criteria for scalar second-order ordinary differential equations had been extended to systems of second-order ordinary differential equations by using geometric methods. These methods not only yield the linearizing transformations but also the solutions of the nonlinear equations. Here, complex methods for a scalar ordinary differential equation are used for linearizing systems of two second-order ordinary and partial differential equations, which can use the power of the geometric method for writing the solutions. Illustrative examples of mechanical systems including the Lane?CEmden type equations which have roots in the study of stellar structures are presented and discussed. 相似文献
45.
M. Pakdemirli T. Hayat M. Yürüsoy S. Abbasbandy S. Asghar 《Nonlinear Analysis: Real World Applications》2011,12(3):1774-1785
A modified second grade non-Newtonian fluid model is considered. The model is a combination of power-law and second grade fluids in which the fluid may exhibit normal stresses, shear thinning or shear thickening behaviors. The flow of this fluid is considered over a porous plate. Equations of motion in dimensionless form are derived. When the power-law effects are small compared to second grade effects, a regular perturbation problem arises which is solved. The validity criterion for the solution is derived. When second grade effects are small compared to power-law effects, or when both effects are small, the problem becomes a boundary layer problem for which the solutions are also obtained. Perturbation solutions are contrasted with the numerical solutions. For the regular perturbation problem of small power-law effects, an excellent match is observed between the solutions if the validity criterion is met. For the boundary layer solution of vanishing second grade effects however, the agreement with the numerical data is not good. When both effects are considered small, the boundary layer solution leads to the same solution given in the case of a regular perturbation problem. 相似文献
46.
The solution for the flow of a third grade fluid bounded by two parallel porous plates is given using homotopy analysis method (HAM). A comparison is made with the exact numerical solution for the various values of the physical parameters. It is found that a proper choice of the auxiliary parameter occurring in HAM solution gives very close results. 相似文献
47.
48.
Fission-fragment mass and kinetic energy distributions and their correlations have been measured for 232U and 233U. The results on these uranium isotopes and 235U are compared. The mass peak/valley ratio of 785 ± 68 for 232U is the highest of the three isotopes. The 〈EK〉(μH) distributions show significant differences. The dip ΔEK at symmetry is , . In the yields for high-kinetic-energy-selected events, the mass 134 dominates for 233U and 235U, but for 232U it is μH≈144, which dominates. This complete reversal of profiles can be understood in terms of fragment shells. 相似文献
49.
John A. Chenery Asghar Fakhr Malcolm I. Wood C.J.S.M. Simpson 《Chemical physics letters》1983,96(2):143-147
The thermal decomposition of CO2 and OCS has been studied using a shock tube and cw CO probe laser. The energies of activation are in good agreement with the values of other workers. It has been shown that the CO formed from OCS has an initial non-thermal vibrational distribution with a large excess in ν = 0. 相似文献
50.
G. Barreau A. Sicre F. Caïtucoli M. Asghar T.P. Doan B. Leroux G. Martinez T. Benfoughal 《Nuclear Physics A》1985,432(2):411-420
Fragment-mass and kinetic-energy distribution measurements for 252Cf(sf) have been extended to the far-out asymmetric low-yield fission region of MH = 190 compared with the existing data that go up to MH ≈ 168. The mass yield Y(m) shows a shoulder for MH ≈ 163 and an important enhancement for MH ? 176. The 〈EK〉(m), σEK(m) and, to a lesser extent, Y(m) distributions show strong and correlated amplitude fluctuations for MH ? 170. These data indicate strong and rapid changes in deformation of the nascent fragments and the coexistence of more than one deformed-shell stabilized scission configuration for the same mass splits. These structures and those present in the relatively high-yield regions are discussed in terms of the static macro-microscopic potential-energy calculations. 相似文献