Páginas

viernes, 5 de septiembre de 2014

Robustness of airline alliance route networks

Citation

Lordan, O., Sallan, J. M., Simo, P., Gonzalez-Prieto, D. (2014). Robustness of airline alliance route networks. Communications in Nonlinear Science and Numerical Simulation, 22, 587-595.
http://dx.doi.org/10.1016/j.cnsns.2014.07.019

Abstract

The aim of this study is to analyze the robustness of the three major airline alliances’ (i.e., Star Alliance, oneworld and SkyTeam) route networks. Firstly, the normalization of a multi-scale measure of vulnerability is proposed in order to perform the analysis in networks with different sizes, i.e., number of nodes. An alternative node selection criterion is also proposed in order to study robustness and vulnerability of such complex networks, based on network efficiency. And lastly, a new procedure – the inverted adaptive strategy – is presented to sort the nodes in order to anticipate network breakdown. Finally, the robustness of the three alliance networks are analyzed with (1) a normalized multi-scale measure of vulnerability, (2) an adaptive strategy based on four different criteria and (3) an inverted adaptive strategy based on the efficiency criterion. The results show that Star Alliance has the most resilient route network, followed by SkyTeam and then oneworld. It was also shown that the inverted adaptive strategy based on the efficiency criterion – inverted efficiency – shows a great success in quickly breaking networks similar to that found with betweenness criterion but with even better results.



viernes, 1 de agosto de 2014

Study of the robustness of the European air routes network

Citation

Lordan, O., Fernandez, V., Sallan, J.M. and Simo, P. (2014). Study of the robustness of the European air routes network. 4th International Conference on Logistics, Informatics and Service Science (LISS 2014). University of California – Berkeley (USA).

Abstract

The aim of this study is to analyze the robustness of the European civil European air transportation network from the perspective of the theory of complex networks. This study is based on analyzing the behavior of the network when its nodes (airports) are removed either by random errors or by deliberate attacks. The calculation of network statistical indicators as degree and betweenness distribution reveals that the flight flow network has the small-world characteristics and scale-free property. The selection of nodes on deliberate attacks is based on four centrality criteria: degree, betweenness, pagerank and eigenvector. This study aims to contribute to the understanding of the logistics network of European commercial flights, analyzing its strengths and weaknesses.

Conference presentation

This post of the Vicenc Fernandez website contains a video of the presentation at the LISS conference

sábado, 14 de junio de 2014

Robustness of the air transport network

Citation

Lordan, O.; Sallan, J. M.; Simo, P.; Gonzalez-Prieto, D. (2014). Robustness of the air transport network. Transportation research part E: Logistics and transportation review, 68:155-163
http://dx.doi.org/10.1016/j.tre.2014.05.011

Abstract

This paper presents a methodology for the detection of critical airports (those whose isolation would cause the largest losses in network connectivity) in the global air transport network (ATN), based on simulating an attack on selected ATN airports using different adaptive selection criteria. The performances of several node selection criteria are compared, together with a new criterion based on Bonacich power centrality. The results show that most critical airports can be detected with an adaptive strategy based on betweenness centrality. The detection of such airports may help the development of contingency plans to develop an appropriate response to any airport closure.

jueves, 22 de mayo de 2014

Antecedentes de enviar un manuscrito a una revista científica

Citación

Sunyer, Silvia; Sallan, Jose M; Simo, Pep; Trullas, Irene (2014). Antecedentes de enviar un manuscrito a una revista científica. Ponencia presentada en la 4ª Conferencia internacional sobre calidad de revistas en ciencias sociales y humanidades (CRECS 2014). Madrid, 8-9 de mayo.

Abstract

Enlace al abstract de la ponencia

Presentación

Enlace a la presentación de la ponencia

jueves, 15 de mayo de 2014

Study of the topology and robustness of airline route networks from the complex network approach: a survey and research agenda

Citation

Lordan, O., Sallan, J. M., Simo, P. (2014). Study of the topology and robustness of airline route networks from the complex network approach: a survey and research agenda. Journal of Transport Geography, 37:112-120.
http://dx.doi.org/10.1016/j.jtrangeo.2014.04.015

Abstract

Communication via air routes is an important issue in a world organized around a web city network. In this context, the robustness of network infrastructures, e.g. air transport networks, are a central issue in transport geography. Disruption of communication links by intentional causes (e.g., terrorist attack on an airport) or unintentional (e.g., weather inclemency) could be crucial for countries, regions and even the airlines affected themselves. Policymakers and the management of airlines and alliances should be able to reduce the effects of such interruptions in order to ensure good communication through air transport (i.e., maximize the robustness of their network at a reasonable cost). The literature review of the study of air transport route networks through an analysis of complex networks has highlighted a lack of contributions to the study of the topology and the robustness of such networks which contrasts, with advances undertaken for other transport networks or communication systems. This survey suggests areas in which research should be undertaken, based on the existing literature in other areas and from three different perspectives: global route networks, airline alliances, airlines and airports so as to help towards a better understanding of air traffic and, therefore, to be able to assess the potential damage of any airport being inoperative for a continent, country or airline.

lunes, 28 de abril de 2014

Equacions estructurals amb lavaan

Resum

L'anàlisi d'equacions estructurals és una tècnica per avaluar models amb relacions complexes entre variables (path analysis), amb variables observables i variables latents. Un cas especialment interessant d'aplicació és l'anàlisi factorial confirmatòria, que permet avaluar la validesa de constructe d'escales de mesura. En aquest article es presenta el paquet de R lavaan, que permet avaluar amb facilitat models d'equacions estructurals. Es reporta informació sobre la sintaxi del model, així com de les possibilitats del paquet.

Enllaç a UPCommons

http://hdl.handle.net/2117/22726

lunes, 14 de abril de 2014

Airline route networks: A complex network approach

Author

Oriol Lordan

Supervisors

Jose M Sallan, Pep Simo

Defense date

14th April, 2014

Abstract

Communication via air routes is an important issue in a world organized around a web-like city network. In this context, the robustness of network infrastructures, e.g. air transport networks, is a central issue in transport geography. Disruption of communication links by intentional causes (e.g., terrorist attack on an airport) or unintentional (e.g., weather inclemency) could be a serious drawback for countries, regions or airlines. Policymakers and the management of airlines and alliances should be able to reduce the effects of such interruptions in order to ensure good communication through air transport, that is, to maximize the robustness of their network at a reasonable cost. The literature review of the study of air transport route networks through complex networks has highlighted a lack of contributions to the study of the topology and the robustness of such networks, which contrasts with advances undertaken for other transport networks or communication systems. The literature survey suggests areas in which research should be undertaken, based on the existing literature in other areas and from three different perspectives: global route networks, airline alliances and airlines. The aim of this research is to develop a better understanding of air traffic and, in particular, to be able to assess the potential damage of any airport being inoperative for a continent, country or airline. This thesis analyzes the topology and robustness of three proposed levels of study characterized by different units of analysis: global route network, airline alliances route network and airlines route network. The different levels do not only represent networks of different magnitudes in number of nodes (airports) and links (routes), but also represent different approaches. In Chapter 2 robustness of the global air transport network (L1) has been analyzed and criteria based on Bonacich power centrality has been presented in order to assess attack vulnerability of complex networks. One of the outcomes of this study will be a list of the most critical airports for the vulnerability of the entire air transport network. In Chapter 3 robustness of alliances route network (L2) will be assessed comparing the robustness of the three major airline alliances (Star Alliance, oneworld and SkyTeam). To perform this analysis, one new node selection criterion based on the efficiency of networks and one new method of assessing vulnerability will be presented. This analysis will lead also to a comparison of the robustness of the three alliances. Finally, in Chapter 4 robustness of 10 FSCs and 3 LCCs route network (L2) will be analyzed. The studied FSCs belong to the different airline alliances showed in Chapter 3 thus allowing the comparison among levels. This chapter outlines a comparison of the differences in robustness between FSCs and LCCs. In Chapter 5 a summary and discussion of conclusions obtained for each level will be carried out.

Thesis contents

The complete text of this thesis can be dowloaded at the TDR repository in the following link: http://www.tdx.cat/handle/10803/144526