مطالب مرتبط با کلیدواژه

Complex Network


۱.

Analysis of the Iranian Airport Network by a Complex Network Approach(مقاله علمی وزارت علوم)

کلیدواژه‌ها: Complex Network Iranian Airport Network centrality Correlation

تعداد بازدید : ۵۰۹ تعداد دانلود : ۲۵۷
In every country, airports are among the most important air transport systems in that country. When an aircraft flies from one airport to another, it creates a graph that can be completed with information about each flight, such as the number of flights per path, the number of passengers, traffic load, and so on. In the present paper, the airports of Iran and the domestic flights are considered as a network and the structure of the network is analyzed, and then the measures of complex networks such as degree distribution, shortest path length, analysis of centralities, clustering coefficient and their correlation and the way these centralities behave are examined. This analysis shows the Iranian Airport Network (IAN) that has a degree distribution described by the power function. The average path length in this network is 1.9, and the average clustering coefficient is 0.69, which meets the characteristics of a small-world network and is also considered an example of a disassortative network. The purpose of this research is to investigate the network of airports in Iran, which is ultimately important for the expansion of airports, and also to identify the important points of airports.
۲.

The Impact of Iranian Oil Sanctions on The Oil Market Volatility Spillover Network(مقاله علمی وزارت علوم)

کلیدواژه‌ها: Iranian oil Sanction Complex Network oil market Diebold - Yilmaz spillover index

حوزه‌های تخصصی:
تعداد بازدید : ۳۴۷ تعداد دانلود : ۳۴۹
This study examines the effect of Iranian oil sanctions on the International oil market network for the first time with Complex Network Analysis (CAN) with Diebold -Yilmaz and Arch indexes from 1991:01 to 2019:12. The analysis was performed for two periods before and after the sanctions, and the results were compared. Results showed that the Iranian oil market in both networks before and after the sanction is one of the influential nodes in the oil network. The volatility spillover of the Iranian oil market in the oil network market has increased after the sanctions. Also, on Iranian oil, volatility spillover from other oil markets has to Iran increased after the sanction. But overall, the sanction has not had a significant impact on the oil market network. The Iranian oil market volatility was receiver before the sanction in the network, but its role changed after the sanction, and it became a sender node.
۳.

ارائه یک رویکرد حل برای بهینه سازی شبکه زنجیره تامین حلقه بسته با تمرکز بر اقتصاد چرخشی: کاربرد الگوریتم NSGA-II(مقاله علمی وزارت علوم)

کلیدواژه‌ها: Complex Network Supply Chain Circular economy Optimization meta-heuristic

حوزه‌های تخصصی:
تعداد بازدید : ۶ تعداد دانلود : ۱۶
In response to increasing attention to the circular economy, supply chain network design is an effective approach in which firms can integrate and allocate resources and improve their overall performance. This paper presents a multi-objective mathematical model for a multi-echelon multi-product multi-period closed-loop supply chain network, focusing on the circular economy concept. GAMS software is used to find an optimal solution for a small-size problem. However, this problem in large dimensions is included in the class of complex problems known as NP-hard, where obtaining the solution using the exact methods will be very time-consuming and sometimes impossible. Therefore, the specific development of this study is to present an application of the NSGA-II algorithm to solve the proposed model on a large scale. Some examples of small, medium and large problems are solved in 20 and 100 iterations. Then sensitivity analysis and Pareto diagram are presented. A comparison of the results obtained from the NSGA-II algorithm with the exact solution method for small-sized problems confirms the effectiveness of the proposed method for solving large-scale complex problems. Taking environmental and social impacts, as well as economic objectives into account, the results of this paper assist decision-makers in designing their circular supply chain network. Also, the general results of the research are practical for managers who intend to move towards a circular economy, reduce costs, and increase productivity and efficiency.