In this note the velocity field and the adequate shear stress corresponding to the unsteady flow of a frac- tional Maxwell fluid due to a constantly accelerating circular cylinder have been determined by means of the ...In this note the velocity field and the adequate shear stress corresponding to the unsteady flow of a frac- tional Maxwell fluid due to a constantly accelerating circular cylinder have been determined by means of the Laplace and finite Hankel transforms. The obtained solutions satisfy all imposed initial and boundary conditions. They can easily be reduced to give similar solutions for ordinary Maxwell and Newtonian fluids. Finally, the influence of pertinent param- eters on the fluid motion, as well as a comparison between models, is underlined by graphical illustrations.展开更多
The problem of hydromagnetic free convection flow over a moving infinite vertical plate with Newtonian heating, mass diffusion and chemical reaction in the presence of a heat source is completely solved. Radiative and...The problem of hydromagnetic free convection flow over a moving infinite vertical plate with Newtonian heating, mass diffusion and chemical reaction in the presence of a heat source is completely solved. Radiative and porous effects are not taken into consideration but they can be immediately included by a simple rescaling of Prandtl number and magnetic parameter. Exact general solutions for the dimensionless velocity and concentration fields and the corresponding Sherwood number and skin friction coefficient are determined under integral form in terms of error function or complementary error function of Gauss. They satisfy all imposed initial and boundary conditions and can generate exact solutions for any problem with technical relevance of this type. As an interesting completion, uncommon in the literature, the differential equations which describe the thermal, concentration and momentum boundary layer, as well as the exact expressions for the thicknesses of thermal, concentration or velocity boundary layers were determined.Numerical results have shown that the thermal boundary layer thickness decreases for increasing values of Prandtl number and the concentration boundary layer thickness is decreasing with Schmidt number. Finally, for illustration,three special cases are considered and the influence of physical parameters on some fundamental motions is graphically underlined and discussed. The required time to reach the flow according with post-transient solution(the steady-state),for cosine/sine oscillating concentrations on the boundary is graphically determined. It is found that, the presence of destructive chemical reaction improves this time for increasing values of chemical reaction parameter.展开更多
The associated primes of an arbitrary lexsegment ideal I C S = K[x1,..., xn] are determined. As application it is shown that S/I is a pretty clean module, therefore S/I is sequentially Cohen-Mazaulay and satisfies Sta...The associated primes of an arbitrary lexsegment ideal I C S = K[x1,..., xn] are determined. As application it is shown that S/I is a pretty clean module, therefore S/I is sequentially Cohen-Mazaulay and satisfies Stanley＇s conjecture.展开更多
In this paper we consider Hibi rings and Rees rings attached to a poset. We classify the ideal lattices of posets whose Hibi relations are indispensable and the ideal lattices of posets whose Hibi relations form a qua...In this paper we consider Hibi rings and Rees rings attached to a poset. We classify the ideal lattices of posets whose Hibi relations are indispensable and the ideal lattices of posets whose Hibi relations form a quadratic Grobner basis with respect to the rank lexicographic order. Similar classifications are obtained for Rees rings of Hibi ideals.展开更多
文摘In this note the velocity field and the adequate shear stress corresponding to the unsteady flow of a frac- tional Maxwell fluid due to a constantly accelerating circular cylinder have been determined by means of the Laplace and finite Hankel transforms. The obtained solutions satisfy all imposed initial and boundary conditions. They can easily be reduced to give similar solutions for ordinary Maxwell and Newtonian fluids. Finally, the influence of pertinent param- eters on the fluid motion, as well as a comparison between models, is underlined by graphical illustrations.
基金Abdus Salam School of Mathematical Sciences, GC University, Lahore, PakistanHigher Education Commission of Pakistan, for generous supporting and facilitating this research work
文摘The problem of hydromagnetic free convection flow over a moving infinite vertical plate with Newtonian heating, mass diffusion and chemical reaction in the presence of a heat source is completely solved. Radiative and porous effects are not taken into consideration but they can be immediately included by a simple rescaling of Prandtl number and magnetic parameter. Exact general solutions for the dimensionless velocity and concentration fields and the corresponding Sherwood number and skin friction coefficient are determined under integral form in terms of error function or complementary error function of Gauss. They satisfy all imposed initial and boundary conditions and can generate exact solutions for any problem with technical relevance of this type. As an interesting completion, uncommon in the literature, the differential equations which describe the thermal, concentration and momentum boundary layer, as well as the exact expressions for the thicknesses of thermal, concentration or velocity boundary layers were determined.Numerical results have shown that the thermal boundary layer thickness decreases for increasing values of Prandtl number and the concentration boundary layer thickness is decreasing with Schmidt number. Finally, for illustration,three special cases are considered and the influence of physical parameters on some fundamental motions is graphically underlined and discussed. The required time to reach the flow according with post-transient solution(the steady-state),for cosine/sine oscillating concentrations on the boundary is graphically determined. It is found that, the presence of destructive chemical reaction improves this time for increasing values of chemical reaction parameter.
文摘The associated primes of an arbitrary lexsegment ideal I C S = K[x1,..., xn] are determined. As application it is shown that S/I is a pretty clean module, therefore S/I is sequentially Cohen-Mazaulay and satisfies Stanley＇s conjecture.
文摘In this paper we consider Hibi rings and Rees rings attached to a poset. We classify the ideal lattices of posets whose Hibi relations are indispensable and the ideal lattices of posets whose Hibi relations form a quadratic Grobner basis with respect to the rank lexicographic order. Similar classifications are obtained for Rees rings of Hibi ideals.
