short-selling prohibition has been one of the primary assumptions of markowitz mean-variance model. solving markowitz quadratic model creates investment efficient frontier by considering only two return and budget constraints. in order to develop a more realistic portfolio selection model, in this paper, a new mathematical model is developed to allow short-selling under some practical constrain...

in this paper, a new stage structured prey-predator model with linear functional response is proposed and studied. the stages for prey have been considered. the proposed mathematical model consists of three nonlinear ordinary differential equations to describe the interaction among juvenile prey, adult prey and predator populations. the model is analyzed by using linear stability analysis to ob...

this paper presents a new mathematical model for a bi-objective job shop scheduling problem with sequence-dependent setup times that minimizes the weighted mean completion time and the weighted mean tardiness time. for solving this multi-objective model, we develop a fuzzy multi-objective linear programming (fmolp) model. in this problem, a proposed fmolp method is applied with respect to the o...

this paper proposes a new mathematical model for the integrated procurement-production-distribution problem of a fuzzy mixed integer linear programming (fmilp) type. considering the uncertainty in real problems, a number of parameters such as demand, capacity, and cost where their values are not available or known precisely, have been considered as trapezoidal fuzzy numbers. to solve fuzzy mixe...

In this paper, an purchasing inventory model for deteriorating items is developed with a linear, positive trend in demand, allowing inventory shortages and backlogging. It is assumed that the goods in the inventory deteriorate over time at a constant rate . Two models are developed for two operational policies. The first policy covers the case that the inventory model with linear demand for det...

Decentralized supply chain management is found to be significantly relevant in today’s competitive markets. Production and distribution planning is posed as an important optimization problem in supply chain networks. Here, we propose a multi-period decentralized supply chain network model with uncertainty. The imprecision related to uncertain parameters like demand and price of the final produc...

fuzzy linear regression models are used to obtain an appropriate linear relation between a dependent variable and several independent variables in a fuzzy environment. several methods for evaluating fuzzy coefficients in linear regression models have been proposed. the first attempts at estimating the parameters of a fuzzy regression model used mathematical programming methods. in this the...

The proposed fuzzy adaptive PI control algorithm is designed for non-linear level process to improve the control performance better than the conventional PI controller. The conventional PI controller works well only if the mathematical model of the system could be computed. Hence it is difficult to implement the conventional PI controller for variable as well as complicated systems. But fuzzy l...