الفهرس 
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Abstract
Uncertainty is an inherent characteristic of construction projects. Neglecting uncertainties associated with different input parameters could lead to misleading project schedules in the planning stage. Many tools and techniques were presented to facilitate modelling in the past to account for uncertainty during planning for construction projects. In constrained resource allocation (resource scheduling) problem, the activities of a project are rearranged such that it achieves the constraint on the resource units. One of the best methods for expressing uncertainty in dealing with cash flow is expressing cash flow as fuzzy numbers. In this research, the uncertainty of planned cash flows is taken into account by expressing the planned cash flows as fuzzy numbers. However, net present value is maximized when positive net cash flow is as close as possible to the start of the project. Many researchers have proposed fuzzy ranking methods that can be used to compare fuzzy numbers. These methods divided into four main categories: preference relation methods, fuzzy mean and spread methods, fuzzy scoring methods and linguistic methods. Methods using centroid index, which is a subclass of a fuzzy scoring, are the most common methods. Thus, some of the ranking methods under this subclass will be applied in the current research. Each method gives a rank for each activity’s cash flow. If we used these ranks as priorities for scheduling activities, thus each method will give different cash flow pattern and in turn different fuzzy net present value. There is a lack of integration of steps in previous models for maximizing fuzzy net present value. Also the shortcomings of these models in dealing with large projects and fuzzifying the direct cost values. Therefore, the first objective is to develop a technique to maximize fuzzy net present value of the project using cash flow weight technique. A new equation is developed for calculating cash flow weight for activities when dealing with real projects with large number of activities. The equation is programed to calculate cash flow weight automatically. Developed technique calculates fuzzy net present value for construction projects if the direct cost for each activity is available even if it is given in a crisp value, because the technique uses a random function to calculate fuzzy numbers. Two scenarios of neglecting and considering inflation rate are adopted. The procedure is applied to an example to show how the technique performs. The second objective of this research is to discover which fuzzy ranking method is the best for maximizing fuzzy net present value for construction project. To focus the scope of the research, ten fuzzy ranking methods are used to find the importance of the activities with respect to fuzzy net present value of the project. Also, triangular normal fuzzy numbers have been only dealt with. Accordingly, three case studies are adopted. Depending on the results of the example project and the three case studies, the best fuzzy ranking method for maximizing fuzzy net present value is discovered. Analysis of the results for the example and the three case studies revealed that: Chu and Tsao (2002) is the best ranking method for maximizing fuzzy net present value in case of neglecting and considering inflation. Thorani et al. (2012) method comes after Chu and Tsao (2002) for the two adopted scenarios. The worst methods are Chen and Chen (2007) and Chen and Chen (2009) in case of neglecting and considering inflation, respectively.