this paper presents a mathematical model for a flow shop scheduling problem consisting of m machine and n jobs with fuzzy processing times that can be estimated as independent stochastic or fuzzy numbers. in the traditional flow shop scheduling problem, the typical objective is to minimize the makespan). however,, two significant criteria for each schedule in stochastic models are: expectable m...

This paper presents a mathematical model for an inventory control system in which customers’ demands and suppliers’ service time are considered as stochastic parameters. The proposed problem is solved through queuing theory for a single item. In this case, transitional probabilities are calculated in steady state. Afterward, the model is extended to the case of multi-item inventory systems. The...

substitution management planning, as one of the important issues in manpower planning, is referred to as a process of filling the gaps and fulfilling the needs of very crutial and key elements of organization in managerial levels. meeting the needs by means of using external and internal manpower of the organization seems to be rational. however, it has some advantages and disadvantages. this p...

The urban waste collection is one of the major municipal activities that involves large expenditures and difficult operational problems. Also, waste collection and disposal have high expenses such as investment cost (i.e. vehicles fleet) and high operational cost (i.e. fuel, maintenance). In fact, making slight improvements in this issue lead to a huge saving in municipal consumption. Some inci...

The time - cost tradeoff problem is one of the most critical issues in the project scheduling field and so far, a lot of research has been done with a variety of quantitative and qualitative approaches on this subject. In this research, we intend to provide a two - objective mathematical model which balances crash and delay for activities. So that it provides the right tools for decision makers...

The facility location problem is a strategic decision-making for a supply chain, which determines the profitability and sustainability of its components. This paper deals with a scenario where two supply chains, consisting of a producer, a number of distribution centers and several retailers provided with similar products, compete to maintain their market shares by opening new distribution cent...

A mathematical multi objective model for the selection of a portfolio of investment is presented and its application in the Mexican Stock Exchange (BMV). The multi objective model proposed is based on our mathematical model of linear programming recently published. Our multi object model is developed whereas the e-constrains method, with which the model remains linear and each iteration the SIM...

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...

conclusions the results indicated that the model, compared with other models, was user-friendly and the desired results were obtained by a minimal data. materials and methods the current paper developed a process model. first, a sketch of nitrate and ammonia storage, their specifications and parameters were set out and created on a page, and then, mathematical relations of each process were set...

surat is a highly developed, thickly populated cosmopolitan character city with full of various activities going on day and night. any natural calamity which causes loss of lives to property and infrastructure along with effects on industrial processes going on has serious impact on economy of the state. therefore, it becomes highly necessary that flood events are studied and analyzed properly ...