Journal of the Nigerian Mathematical Society最新文献

In this paper, we employ perturbation procedures in asymptotic expansions of the various variables to determine the dynamic buckling load of a lightly damped elastic quadratic model structure modulated by a dynamic periodic load. We finally relate the dynamic buckling load to its static equivalent and show that given any one of them, the other can automatically be obtained.

We consider a manpower system with finite discrete non-overlapping states where recruitment is done to replace wastage and to achieve the desired growth. The states of the system are defined in terms of the ranks. Data for the evolution of manpower structure in the system may be obtained at any choice of time instants. The empirical stochastic matrix resulting from the evolution of the system at each time instant is sparse. We propose a transition model for the system where the multi-step empirical stochastic matrix is expressed as the exponential of a Markov generator. We give illustrations using academic staff data in a university setting.

In this paper, an incompressible viscous fluid flow and heat transfer in a collapsible tube with heat source or sink is examined. The nonlinear equation arising from the model was solved using perturbation series. An increasing or decreasing in the Prandtl number leads to increasing or decreasing in the rate of heat transfer across the wall.

In this paper, the generalization of the Lanczos–Ortiz’s Recursive formulation of the tau method for general non-overdetermined ordinary differential equations is presented. The generalization of the canonical polynomials and their derivatives for both overdetermined and non-overdetermined cases were reported in the earlier works of these authors, thus the emphasis here is on the error and the error estimate procedures. The accuracy of the results were established using some numerical examples and the induction principle.

In this research, we consider the consequence of trade credit on optimal quantity. The annualized cost which is the uniform net present value over infinite time is derived and the optimal quantity and optimal time are obtained. This work is a modification of the model formulated by Chand and Ward (1987). The computation and graphical illustration based on the data collected from Lift Above Poverty Organisation (LAPO) show that the optimal quantity is time varying with a linear trend. This means that as the delay time increases the optimal quantity increases. It also implies that the optimal quantity is an increasing function of delay time.

This present study focuses on the effects of thermophoresis, Dufour, temperature dependent thermal conductivity and viscosity of an incompressible electrically conducting Casson fluid flow along a vertical porous plate in the presence of viscous dissipation, $n^{th}$ order chemical reaction and suction. It is assumed that the relationship between the flow rate and pressure drop as the fluid flows through a porous medium is non-linear. Similarity transformations are used to convert the governing equations to a system of nonlinear ordinary coupled differential equations and the numerical solutions for the velocity, temperature and concentration profiles are obtained using shooting method along with Runge-Kutta Gill and Quadratic interpolation (Muller’s scheme). The behaviour of dimensionless velocity, temperature and concentration within the boundary layer has been studied using different values of Prandtl number, Casson parameter, thermophoretic parameter, temperature dependent viscosity, temperature dependent thermal conductivity, Magnetic parameter, local Forchheimer parameter, and local Darcy parameter. The flow controlling parameters are found to have a profound effect on the resulting flow profiles except in some few cases i.e. effect of thermophoretic parameter $\tau$ over velocity and temperature profiles of fluids with constant viscosity and thermal conductivity ($\xi =\epsilon =0$). The local skin friction, Nusselt number and Sherwood number for some cases are also presented.

In this paper we designed Rational Interpolation Method for solving Ordinary Differential Equations (ODES) and Stiff initial value problems (IVPs).

This was achieved by considering the Rational Interpolation Formula. $y_{\left(x\right)}=U_{\left(x\right)}=\frac{P_0+P_{1}x+P_2{x}^2+P^3{x}^3+p_4{x}^4+P_5{x}^5}{1+q_{1}x+q_2{x}^2+q_3{x}^3+q_4{x}^4+q_5{x}^5+q_6{x}^6}\text{,}$ satisfying $U\left(X_{n+i}\right)=y_{n+i},i=0,1,2,3,4,5,6$.

We also implemented $k=6$ in Aashikpelokhai (1991) class of rational integration formulas given by $y_{n+1}=\frac{\sum _{i=0}^5{p}_i{X}_{n+1}^i}{1+\sum _{i=1}^{}}$