مجله بین المللی محاسبات و مدل سازی ریاضی
سال دوم شماره 2 (Spring 2012)

In this paper, we unify, extend and generalize some results on coupled fixed point theorems of generalized φ- mappings with some applications to fixed points of integral type mappings in cone metric spaces.

In this paper, a production inventory model is developed for the business enterprise which consists of three wings. The first wing is for manufacturing new items, the second wing is for collecting the returned items, while third wing is for remanufacturing the returned item. In this model we consider the fact that the storage item is deteriorated during storage periods and salvage value is incorporated to the deteriorated items. The demand, deterioration, production, remanufacturing and return rates are time dependent. The shortages are allowed and fully backlogged. The model is solved analytically by minimizing the total inventory cost. The model can be applied for optimizing the total inventory cost of deteriorating items inventory under reverse logistic for a business enterprise where demand and deterioration both is function of time.

The Fibonacci lengths of the finite p-groups have been studied by R. Dikici and co-authors since 1992. All of the considered groups are of exponent p, and the lengths depend on the celebrated Wall number k(p). The study of p-groups of nilpotency class 3 and exponent p has been done in 2004 by R. Dikici as well. In this paper we study all of the p-groups of nilpotency class 3 and exponent p2. This completes the study of Fibonacci length of all $p$-groups of order p4, proving that the Fibonacci length is k(p2).

In this paper we investigate the behavior of solutions, stable and unstable of the solutions a second-order rational difference equation. Also we will discuss about the behavior of solutions a the rational system, we show these solutions may be stable or unstable.

In this paper, we propose a method to approximate the solution of a linear Fredholm integro-differential equation by using the Chebyshev wavelet of the first kind as basis. For this purpose, we introduce the first Chebyshev operational matrix of integration. Chebyshev wavelet approximating method is then utilized to reduce the integro-differential equation to a system of algebraic equations. Illustrative examples are included to demonstrate the advantages and applicability of the technique.

In this study, Stability analysis of snow slab which is under detonation has developed in the present model. The model has been studied by using the basic concepts of non-detonation model and concepts of underwater explosions with appropriate modifications to the present studies. The studies have also been extended to account the effect of critical length variations at the time of detonation and its effects on various material parameters through the concepts of fracture mechanics. The results indicate that the stability and critical length values are lower for the detonation (present) values in comparison with the non-detonated values. The importance of the studies in Avalanche forecasting has been highlighted.

This paper proposes an Integer Programming model to obtain the Least Common Multiply (LCM) for some integer numbers. The proposed method is illustrated by a numerical example.

The aim of this paper is the evaluation overall performance of buyer-supplier relationships.In some situations the cost of inputs in a buyer-supplier chain are available, on the other hand, achieving a low cost position is necessary for most businesses. And, in a buyer-supplier chain wants to know how assign inputs with the least cost. This paper introduces cost efficiency with same and dierent costs of inputs. Moreover, cost efficiency not only does it improve protability, but businesses with a low cost position are better able to drive growth through higher investment in sales, marketing, improve customer service and new product development, as well as more competitive pricing in buyer-supplier. Moreover, in this paper we introduce allocative and technical eciency of buyer-supplier that based on the Data envel-opment analysis (DEA). And show how far the buyer-supplier is from the point of maximum protability given the existing market prices for inputs and products, and also is achieved when the value consumers place on a good or service equals the cost of the resources used up in production. Finally, we illustrate the proposed models by an example.