Proposing an Optimum Model for Time Estimation of Construction Projects in Iranian Gas Refineries

Time management can be effective in a project when the project schedule is based on comprehensive time scheduling. In the industries with complicated processes, many uncertainties and risks affect the timing of projects. Considering the very low reliability of the project planning in certainty-based approach, using more secure models for control and interact with uncertainty should be placed on the agenda. Iranian Gas Company has been using risk management to manage probable uncertainties in construction projects but in the field of possible uncertainties, actions are very scarce. This article aims to propose an optimum model based on the integrated risk management and fuzzy expert systems in order to provide comprehensive project time estimation and in this regard, reviews the results of the implementation of this model in construction projects of Iranian gas refineries. The results show that the proposed model increases the accuracy of time estimation about 8 to 24 percent.Time management can be effective in a project when the project schedule is based on comprehensive time scheduling. In the industries with complicated processes, many uncertainties and risks affect the timing of projects. Considering the very low reliability of the project planning in certainty-based approach, using more secure models for control and interact with uncertainty should be placed on the agenda. Iranian Gas Company has been using risk management to manage probable uncertainties in construction projects but in the field of possible uncertainties, actions are very scarce. This article aims to propose an optimum model based on the integrated risk management and fuzzy expert systems in order to provide comprehensive project time estimation and in this regard, reviews the results of the implementation of this model in construction projects of Iranian gas refineries. The results show that the proposed model increases the accuracy of time estimation about 8 to 24 percent

Exact Optimal Solution of Fuzzy Critical Path Problems

In this paper, a fuzzy critical path problem is chosen to show that the results, obtained by using the existing method [Liu, S.T.: Fuzzy activity times in critical path and project crashing problems. Cybernetics and Systems 34 (2), 161-172 (2003)], could be improved to reflect, more appropriate real life situations. To obtain more accurate results of fuzzy critical path problems, a new method that modifies the existing one is proposed here. To demonstrate the advantages of the proposed method it is used to solve a specific fuzzy critical path problem

Application of Fuzzy Expert Systems to Manage the Projects Time in Iranian Gas Refineries

The National Iranian Gas Company (NIGC) is one of the top ten gas companies in the gas industry in the Middle East and is comprised of 7 gas refineries. So this company needs to apply the most optimum time management methods to achieve its goals. Custom scheduling calculation of project planning uses the Critical Path Method (CPM) as a tool for Planning Projects activities. CPM is now widely used in planning and managing projects but in spite of its wide application, this method has a critical weak point of not taking into account the uncertainties in scheduling calculation. This article aims to present a precise method based on the application of Fuzzy Expert Systems in order to improve the Time Estimation Method in construction projects and in this regard, reviews the results of the implementation of this method in construction projects of Iranian Gas Refineries. The results show that the proposed method increases the accuracy of time estimation about 7 to 22 percent

A New Method for Fuzzy Critical Path Analysis in Project Networks with a New Representation of Triangular Fuzzy Numbers

The method for finding fuzzy optimal solution of fully fuzzy critical path (FFCP) problems i.e., critical path problems in which all the parameters are represented by fuzzy numbers, is at best scant; possibly non-existent. In this paper, a method is proposed to find the fuzzy optimal solution of FFCP problems, together with a new representation of triangular fuzzy numbers. This paper will show the advantages of using, the proposed representation over the existing representations of triangular fuzzy numbers and will present with great clarity the proposed method and illustrate its application to FFCP problems occurring in real life situations

A new method for critical path method with fuzzy processing time

Critical path method plays an important role on managing medium to large-scale problems. It is often difficult to determine the critical path for different reasons such as the existing uncertainties in processing tasks. One alternative to handle the uncertainty associated with the processing time is to use fuzzy techniques. We present a new method to calculate the critical path method when the processing times follow trapezoidal fuzzy numbers. The proposed model of this paper does not use any defuzzification technique to find the final processing time. The implementation of the proposed model is compared with other techniques using a well-known example from the literature

Trapezoidal Fuzzy Shortest Path (TFSP) Selection for Green Routing and Scheduling Problems

The routing of vehicles represents an important component of many distribution and transportation systems. Finding the shortest path is one of the fundamental and popular problems. In real life applications, like vehicle green routing and scheduling, transportation, etc. which are related to environmental issues the arc lengths could be uncertain due to the fluctuation with traffic conditions or weather conditions. Therefore finding the exact optimal path in such networks could be challenging. In this paper, we discuss and analyze different approaches for finding the Fuzzy Shortest Path. The shortest path is computed using the ranking methods based on i)Degree of Similarity ii) Acceptable Index, where the arc lengths are expressed as trapezoidal fuzzy numbers. The Decision makers can choose the best path among the various alternatives from the list of rankings by prioritizing the scheduling which facilitates Green Routing

Contractors ranking in construction projects based on a fuzzy decision-making method: A case study in the National Iranian Oil Company

Prepared platforms and infrastructures are required for all companies' improvement to carry out their assigned missions. In this regard, construction contractors play their role as one of the main managers’ levers and are responsible for building the infrastructures. Quantity and quality of contractors’ services can have a quite direct impact on corporate strategies and their life trend, and outbreak as an advantage in competitive markets. Having a contractor that is the closest match with the project is intended to be among the principal tasks of the managers in project performance department. The contractor must have talents which effectively meet project requirements. A decision support system is obtained by prioritizing the determining and influential criteria in decision making, contractor selection, performing and defining the documents. Therefore, considering most of these numerous quality based indicators, Fuzzy multi-criteria decision-making methods can be used for contractor pre-qualification and selection to meet this objective. Accordingly, in this paper, a method based on FUZZY TOPSIS approach is presented to evaluate and rank the development of the National Iranian Oil Company Contractors

Contractors ranking in construction projects based on a fuzzy decision-making method: A case study in the National Iranian Oil Company

Prepared platforms and infrastructures are required for all companies' improvement to carry out their assigned missions. In this regard, construction contractors play their role as one of the main managers’ levers and are responsible for building the infrastructures. Quantity and quality of contractors’ services can have a quite direct impact on corporate strategies and their life trend, and outbreak as an advantage in competitive markets. Having a contractor that is the closest match with the project is intended to be among the principal tasks of the managers in project performance department. The contractor must have talents which effectively meet project requirements. A decision support system is obtained by prioritizing the determining and influential criteria in decision making, contractor selection, performing and defining the documents. Therefore, considering most of these numerous quality based indicators, Fuzzy multi-criteria decision-making methods can be used for contractor pre-qualification and selection to meet this objective. Accordingly, in this paper, a method based on FUZZY TOPSIS approach is presented to evaluate and rank the development of the National Iranian Oil Company Contractors

Contractors ranking in construction projects based on a fuzzy decision-making method: A case study in the National Iranian Oil Company

Prepared platforms and infrastructures are required for all companies' improvement to carry out their assigned missions. In this regard, construction contractors play their role as one of the main managers’ levers and are responsible for building the infrastructures. Quantity and quality of contractors’ services can have a quite direct impact on corporate strategies and their life trend, and outbreak as an advantage in competitive markets. Having a contractor that is the closest match with the project is intended to be among the principal tasks of the managers in project performance department. The contractor must have talents which effectively meet project requirements. A decision support system is obtained by prioritizing the determining and influential criteria in decision making, contractor selection, performing and defining the documents. Therefore, considering most of these numerous quality based indicators, Fuzzy multi-criteria decision-making methods can be used for contractor pre-qualification and selection to meet this objective. Accordingly, in this paper, a method based on FUZZY TOPSIS approach is presented to evaluate and rank the development of the National Iranian Oil Company Contractors