International Journal of Applied Operational Research

A Monte Carlo simulation to identify the effect of delays in construction project scheduling

M. Abolghasemian

Construction projects are inherently complex and subject to various uncertainties and delays that can significantly impact their schedule and overall success. Delays in construction projects can arise from a multitude of factors such as weather conditions, material shortages, labor issues, or unexpected design changes. These delays not only disrupt the planned timeline but can also lead to cost overruns and conflicts among project stakeholders. An efficient construction industry is a prerequisite for the development of the construction process. In this regard, this paper aims to identify the most common, severe, and important causes of schedule delay and its effect on construction projects. Therefore, the main contribution of current study offers a systematic approach to assessing and managing risks associated with delays in construction projects. By quantifying the likelihood of different delay scenarios, project managers can make informed decisions to mitigate risks and optimize scheduling strategies. The main objective during the construction phases is to complete the project on time and within the budget and meet the set quality requirements and other specifications simultaneously. For this purpose, a framework to identify and prioritize delays and critical activities is proposed in current study and an attempt is made to implement it using the framework introduced in a real case study on the freeway projects of Iran. Accordingly, first, several delays known in free construction projects were considered using the available theoretical resources, they were then subjected to the judgment of experts employing the Delphi technique so 14 delays were identified in the first round of implementing the Delphi technique. Subsequently, a schedule was designed for freeway projects consisting of 13 activities. In the continuation of this research, a questionnaire was prepared to collect information, and 48 answer sheets were carefully completed and received by experts. Then, by running the second round of Delphi, five critical delays were selected among the identified delays, and the statistical delay functions of each of them were estimated using Decision Tools software. Then, by designing 19 scenarios, the effect of each of the critical delays in the activities was reported based on the designed scenarios. Also, for further analysis, nine and five scenarios were designed based on the most important delay factors on critical activities and two important activities, respectively; and using the PERT technique, the certain value of increase in activity time was calculated based on different probabilities. According to the reported PERT, the scenarios were prioritized in each step.

A numerical method for solving distributed order time fractional COVID-19 virus model based on Legendre wavelets optimization approach

A. H. Refahi Sheikhani

In this paper, we introduced a distributed order time fractional Coronavirus-19 disease transmission involving Caputo-Prabhakar fractional derivative of α order in time t. The coronavirus 19 disease model has 8 inger dients leading to system of 8 nonlinear ordinary differential equations in this sense. To solve these types of equations, we proposed a numerical method based on the upon Legendre wavelets optimization approximations. In the first stage, by applying the Legendre wavelets optimization functions and Laplace transform an exact formula for the Prabhakar fractional integral operator is derived. Then, we apply this exact formula and the properties of Legendre wavelets optimization functions to change the given equation into a system of algebraic equations. We calculated the approximation optimal solutions of our system applying the Newton’s iterative method. The optimal approximate solutions obtained by using the proposed method are considered as the best solutions for the proposed equation. Error analysis is examined to verify the practical efficiency of the proposed method. In the end, for the efficiency and performance of the proposed method, the numerical results are shown in the figure.

A novel attitude of robust optimization and risk management for network designing of closed-loop green supply chain

A. Taherinezhad

A very important factor which needs to be considered in the process of designing an efficient supply chain is cost reduction. Meanwhile, to tackle climate change and to fight the increase in environmental pollution, the managers of organizations as well as scholars active in the field of designing supply chains, have started to adopt measures, which, on top of economic optimization, are also focused on environmental factors aimed at reducing pollutants in all sectors of the economy. Apart from the mentioned two variables, another factor influencing the supply chain is the delivery time. In the present paper, an integrated forward/reverse logistics network has been studied considering three objective functions including "minimizing environmental effects", "minimizing costs", and "minimizing delivery time", which are in fact the innovations of this research study. Model uncertainty has been dealt with through robustness of solutions. Scenario-based risk assessment methods have been applied to identifying and assessing potential risks. Then, taking into consideration the uncertain parameters, the robust scenario-based model of the problem has been submitted. Replacing the outputs of risk analysis (normalized risk priority number (RPN)) in the model for scenario occurrence, the authors have completed the model. Meanwhile, using the General Algebraic Modeling System (GAMS) software and the LP metric method, the model is transformed into a single-objective model and the problem is solved. The findings indicate that with the combination of risk assessment and robust optimization techniques, an efficient supply chain design will be realized, which is the study's another innovative aspect.

Measuring ICT-opportunity index using generalized data envelopment analysis

G. H. Askarirobati

Information and Communication Technology (ICT) is an important structural part of modern society. This is why countries strive for constant progress in ICT. Information Technology Development Index (IDI) ranks countries’ performance in terms of ICT infrastructure and uptake. It aims to provide an objective international performance evaluation based on quantitative indicators and benchmarks. The results for this metric help policymakers monitor trends, identify areas for policy action, and compare their ICT developments. Bearing this in mind, the main purpose of this paper is to introduce a generalized DEA method that incorporates decision makers' preferences and offers a new perspective on measuring the ICT development index. In addition, preferred solutions are introduced depending on preferential information and improvement axis. Since the opinions of the decision-makers have been applied to reach the preferred solution, more realistic results are obtained. The results show that these solutions are a subset of efficient solutions. A total of 11 IDI indicators are identified based on International Telecommunication Union data. Assessments and rankings were performed using the DEA output-oriented model without input and the cross-efficiency model. In addition, for low-level countries, using preferred solutions, realistic targets are set following the preferential information of decision-makers to reach higher levels.

The process and infrastructures of the implementation of the model of documenting the experiences of employees

M. Kheirandish

In today's rapidly evolving business environment, organizations are increasingly recognizing the importance of capturing and leveraging the experiences of their employees. Documenting employee experiences can provide valuable insights into best practices, lessons learned, and innovative ideas that can drive organizational growth and success. The importance of knowledge and experience as the most important intangible asset in gaining a competitive advantage in organizations is not hidden from anyone and organizations are looking for the optimal use and management of knowledge and experiences in the form of documentation projects, for the correct and effective implementation of these projects, it is necessary to design a suitable implementation model. Based on this, in this research, the design of the effective implementation model of documenting the experiences of the employees of the General Administration of Social Security Treatment has been discussed. This research aims to contribute to the existing literature by providing practical insights into the process and infrastructures required for the successful implementation of a model for documenting the experiences of employees. The results can guide organizations in developing effective strategies to capture, store, and utilize employee knowledge for enhanced organizational performance and competitiveness. In this research, the exploratory mixed method - thematic analysis and survey strategy - was used. The statistical community of the qualitative section includes 15 experts from the general administration and the quantitative section includes 180 working managers. Collecting data in the qualitative part with in-depth semi-structured interviews and reviewing the theoretical foundations of the research and the background of the research and in the quantitative part with the researcher's questionnaire, the validity, and reliability of each part were confirmed. The data in the qualitative part were analyzed using three-step coding and in the quantitative part with descriptive statistics (demographic characteristics) and inferential statistics (structural equation modeling) tests. Based on the analysis of the research data, the implementation model of documenting the experiences of employees included 32 basic themes, 5 organizing themes (the executive process of documentation, human resource requirements, technological requirements, cultural requirements, and legal requirements), and an overarching theme in the form of implementation. Also, the quantitative data analysis of the research indicated the appropriateness of the model of documenting the experiences of employees. Any effective implementation process regarding experience documentation patterns requires infrastructure in the form of appropriate dimensions and components. This importance has been identified in the final model of the research. Based on this, implementing and carrying out the required measures based on vulnerability will provide the basis for institutionalization and greater acceptance of this project.

Optimization of active microarchitecture design

A. Sedaghat

A complementary follow-on tool is required to optimize the geometric parameters of the topology solutions once the flexure design topology of an active micro-architected material has been synthesized. This will enable the production of final designs that not only meet the desired DOFs for the constituent materials but also best meet the desired performance requirements. This paper introduces a computational tool to identify the boundaries of the performance capabilities achieved by general flexure system topologies, provided that their geometric parameters are allowed to vary from their smallest allowable feature sizes to their largest geometrically compatible feature sizes for given constituent materials. The boundaries fully define flexure systems' design spaces and allow designers to visually identify which geometric versions of their synthesized topologies best achieve desired combinations of performance capabilities.