A Mathematical Model and Two Fuzzy Approaches Based on Credibility and Expected Interval for Project Cost-Quality-Risk Trade-Off Problem in Time-Constrained Conditions

To successfully finalize projects and attain their determined purposes, it is indispensable to control all success criteria of a project. The time–cost trade-off (TCT) is known as a prevalent and efficient approach applied when the planned finish date of a project is not admitted by stakeholders, and consequently, the project duration must be decreased. This paper proposes a new mathematical model under fuzzy uncertainty to deal with the project cost–risk–quality trade-off problem (CRQT) under time constraints. Because of the unique nature of projects and their uncertain circumstances, applying crisp values for some project parameters does not seem appropriate. Hence, this paper employs fuzzy sets to resolve these weaknesses. In this study, two approaches are presented to handle proposed fuzzy multi-objective mathematical model. First, fuzzy credibility theory and then goal attainment method are used. Secondly, the model is solved by a fuzzy method based on expected interval and value and augmented ɛ-constraint method. A project from the literature review is adopted and solved by the presented methodology. The results demonstrate the accuracy and efficiency of the two proposed approaches for the introduced practical problem

An optimization model for energy project scheduling problem with cost-risk-quality-social consideration trade-off under uncertainty: A real-world application

To complete a successful energy project, all aspects and criteria which can influence the project should be considered. Classic time-cost trade-off (TCT) is used when the completion time of project is not acceptable for customers or top managers. This paper proposes a new cost-risk-quality-social consideration trade-off (CRQST) model for energy projects in a time-constrained problem for achieving specified due date under uncertainty. Moreover, a new comprehensive definition of risk criterion is proposed, and a novel approach for the quality criterion of project based on the dependence of the quality of activities with each other is presented. The internal and external environment of the energy project are considered simultaneously and a new criterion in TCT problem, called social consideration criterion, is introduced. A developed fuzzy augmented ε-constraint method is introduced for the presented multi-objective model to generate Pareto-optimal solutions. To depict the accuracy of results, the proposed model is solved by goal attainment method, and the results of two methods are compared. As a case study, a real oil and gas project is presented, and results show that the proposed method enables managers to effectively handle construction projects in real-world uncertain environments

A new analytical methodology to handle time-cost trade-off problem with considering quality loss cost under interval-valued fuzzy uncertainty

This paper proposes a new framework in addressing time-cost trade-off problem (TCTP) under uncertainty. First critical path analysis is carried out based on developing a new interval-valued fuzzy (IVF)-program evaluation and review technique (PERT) approach. Then, non-conformance risks that influence on execution quality of activities are identified and evaluated based on a new approach that considers probability of risk along with impacts on time, cost, and performance. Then, a new mathematical model under IVF uncertainty is presented to decrease project total time while considering time, cost and quality loss cost that is determined in form of rework or modification cost. Finally, the approach categorizes the activities in three groups based on their level of criticality. Outcome of this methodology is a scheduling that addresses time, cost and quality trade-offs in addition to categorizing activities in different groups based on being on the critical path. Therefore, the project manager not only gets a scheduling based on the TCTP with considering quality loss cost but also has a knowledge of activities that require extra attentions. To show the steps of this methodology, an existing application from the literature is adopted and solved

Investigate the level of student\'s interest in their field of study and the effective factors on it, from the viewpoint of students of the Zahedan University of Medical Science in 2018

Background and Aim: Different disciplines of medical science have a close connection with the health of the public. Lack of awareness of the field of study and disinterest to it will have consequences on the educational and health system. While recognizing the field of study and interest in it increases the sense of responsibility and efficiency of individuals in the provision of services. The purpose of this study was to determine the students' interest in their field of study and the factors influencing it from the viewpoint of students of Zahedan University of Medical Sciences. Materials and Methods: &nbsp;In this descriptive-analytical study, 210 students from Zahedan University of Medical Sciences were randomly selected. The method of collecting information was field-based and using a valid questionnaire, including 21 questions (14 items with Likert Triple Scale). Data were entered into SPSS software (Version.20). The confidence level was considered as 0.05. Results: The average interest rate of students in their field of study was 68.3 &plusmn; 27.3. 60.3% of the women were female and the rest were male The mean age of the subjects was 21.2&plusmn;3.3 years. It was found that there was a significant relationship between the level of interest of individuals with marital status (P <0.0001) and previous knowledge of subjects when choosing a course (P <0.0001). Conclusion: &nbsp;The results of this study showed that the students' interest in their field of study was relatively good, but less than half of them had chosen their field of study without prior knowledge. &nbsp

How much should you worry about contaminant neutrons in spatially fractionated grid radiation therapy?

Neutron contamination in radiation therapy is of concern in treatment with high-energy photons (> 10 MV). With the development of new radiotherapy modalities such as spatially fractionated grid radiation therapy (SFGRT) or briefly grid radiotherapy, more studies are required to evaluate the risks associated with neutron contamination. In 15 MV SFGRT, high-Z materials such as lead and cerrobend are used as the block on the tray of linear accelerator (linac) which can probably increase the photoneutron production. On the other hand, the high-dose fractions (10-20 Gy) used in SFGRT can induce high neutron contamination. The current study was devoted to addressing these concerns via compression of neutron fluence (Φn) and ambient dose equivalent ([Formula: see text]) at the patient table and inside the maze between SFGRT and conventional fractionated radiation therapy (CFRT). The main components of the 15 MV Siemens Primus equipped with different grids and located inside a typical radiotherapy bunker were simulated by the MCNPX® Monte Carlo code. Evidence showed that the material used for grid construction does not significantly increase neutron contamination inside the maze. However, at the end of the maze, neutron contamination in SFGRT is significantly higher than in CFRT. In this regard, a delay time of 15 minutes after SFGRT is recommended for all radiotherapy staff before entering the maze. It can be also concluded that [Formula: see text] at the patient table is at least 10 times more pronounced than inside the maze. Therefore, the patient is more at risk of neutrons compared to the staff. The [Formula: see text] at the isocenter in SFGRT with grids made of lead and cerrobend was nearly equal to CFRT. Nevertheless, it was dramatically lower than in CFRT by 30% if the brass grid is used. Accordingly, SFGRT with the brass grid is recommended, from radiation protection aspects