مجله بین المللی محاسبات و مدل سازی ریاضی
سال یکم شماره 3 (Summer 2011)

Chancroid is a highly infectious and curable sexually transmitted disease caused by the bacterium Haemophilus Ducreyl (also known as H. Ducreyl). A deterministic mathematical model for investigating the role of treatment on controlling chancroid epidemic is formulated and rigorously analyzed. A threshold quantity known as the productive number, which measures the number of secondary infections produced by a single chancroid infective when introduced in a population of susceptible in the presence of treatment has been derived. Equilibria for the model are determined and their stability are examined. Latin hypercube sampling has been used to perform the sensitivity analysis of the reproductive number.

The aim of this research note is to prove the following new transformation formula \begin{equation*} (1-x)^{-2a}\,_{3}F_{2}\left[\begin{array}{ccccc} a, & a+\frac{1}{2}, & d+1 & & \\ & & &; & -\frac{4x}{(1-x)^{2}} \\ & c+1, & d & & \end{array}\right] \\ =\,_{4}F_{3}\left[\begin{array}{cccccc} 2a, & 2a-c, & a-A+1, & a+A+1 & & \\ & & & &; & -x \\ & c+1, & a-A, & a+A & & \end{array} \right], \end{equation*} where $A^2=a^2-2ad+cd$ after the equation. For d=c, we get a known quadratic transformations due to Gauss. The result is derived with the help of the generalized Gauss's summation theorem available in the literature.

In this paper we present a new kind of B-splines, called hyperbolic B-splines generated over the space spanned by hyperbolic functions and we use it to interpolate an arbitrary function on a set of points. Numerical tests for illustrating hyperbolic B-spline are presented.

A. Noor et al. [7] analyze a technique by combining the variational iteration method and the homotopy perturbation method which is called the variational homotopy perturbation method (VHPM) for solving higher dimensional initial boundary value problems. In this paper, we consider the VHPM to obtain exact solution to Gas Dynamics equation.

In the present work, failure of a snow slab is analyzed by accounting Normal mode criteria. The analysis has been extended to include residual stress into the model (in addition to body forces). Intensity of crack energy release rate, and displacement components have been derived and their values have been estimated. The obtained results have been compared with the existing snow slab failure models [Perla and La chappelle (1970), Perla (1980), Sigrist (2006), Schweizer (1999)]. The criteria of snow slab failure have been critically examined.The maximum stress in the snow pack and critical intensity factor of crack development has also been studied in the model. The results of the present model can be used for the avalanche release information.

In this paper we investigate Multi-Objective Integer Linear Programming (MOILP) problems with unbounded feasible region and introduce recession direction for MOILP problems. Then we present necessary and sufficient conditions to have unbounded feasible region and infinite optimal values for objective functions of MOILP problems. Finally we present some examples with unbounded feasible region and finite and infinite efficient solution.

Fuzzy liner systems of equations, play a major role in several applications in various area such as engineering, physics and economics. In this paper, we investigate the existence of a minimal solution of inconsistent fuzzy matrix equation. Also some numerical examples are considered.

Spurred by intensifying competition in global markets, most companies have been increasingly implementing supply chain management (SCM) and information systems (IS) practices. As well, globalization policies have created a more intensive competition amongst manufacturers; in additional the priority of supply over demand, market competition and importance of some factor such as quality, accountability has encouraged companies to integrate their activities using SCM. Performance measurement of supply chain management reflects the need for improvement in operational areas which are found wanton in performance measures. In addition to the results obtained from the evaluation of supply chain performance based on inner changed data can help the integration of supply chain activities and their inner changed data through improving the chain relations and it satisfies customers. In addition, Supply chain (SC) performance evaluation problems cover a wide range from evaluating the performance of independent organizations among supply chains to evaluating the performance of a whole supply chain system. Therefore, in this paper, as regards, performance evaluation is of great importance for effective supply chain management, it has been tried to evaluate supply chain performance by both exact and interval data. This model is illustrated by a numerical example.