Assessing transport related social exclusion using a capabilities approach to accessibility framework: A dynamic Bayesian network approach

Accessibility is considered to be a valuable concept that can be used to generate insights on issues related to social exclusion due to limited access to transport options. Recently, researchers have attempted to link accessibility with popular theories of social justice such as Amartya Sen's Capabilities Approach (CA). Such studies have set the theoretical foundations on the way accessibility can be expressed through the CA, however, attempts to operationalise this approach remain fragmented and predominantly qualitative in nature. In this study, a novel framework of expressing accessibility at the level of an individual is proposed, based on the basic elements of the CA. In particular, dynamic Bayesian networks are used to express the causal relationship between capabilities, functionings, personal and environmental characteristics. This is done by introducing informative Dirichlet prior distributions constructed using data from traditional mobility surveys, modelling the transition probabilities with data related to place based characteristics and defining an observation model from unlabelled mobility data and places of interest (POI). We demonstrate the usefulness of the proposed framework by assessing the equality levels and their link to transport related social exclusion of different population groups in London, using unlabelled, service provider generated mobility data.     

A heuristic approach to logistics network design for end-of-lease computer products recovery

This paper discusses the logistics network design for end-of-lease computer products recovery by developing a deterministic programming model for systematically managing forward and reverse logistics flows. Due to the complexity of such network design problem, a two-stage heuristic approach is developed to decompose the integrated design of the distribution networks into a location–allocation problem and a revised network flow problem. The applicability of the proposed method is illustrated in a numerical study. Computational experiments demonstrate that high-quality solutions are obtained while modest computational overheads are incurred.     

Exploring the network structure and nodal centrality of China’s air transport network: A complex network approach

This paper uses a complex network approach to examine the network structure and nodal centrality of individual cities in the air transport network of China (ATNC). Measures for overall network structure include degree distribution, average path length and clustering coefficient. Centrality metrics for individual cities are degree, closeness and betweenness, representing a node’s location advantage as being directly connected to others, being accessible to others, and being the intermediary between others, respectively. Results indicate that the ATNC has a cumulative degree distribution captured by an exponential function, and displays some small-world (SW) network properties with an average path length of 2.23 and a clustering coefficient of 0.69. All three centrality indices are highly correlated with socio-economic indicators of cities such as air passenger volume, population, and gross regional domestic product (GRDP). This confirms that centrality captures a crucial aspect of location advantage in the ATNC and has important implications in shaping the spatial pattern of economic activities. Most small and low-degree airports are directly connected to the largest cities with the best centrality and bypass their regional centers, and therefore sub-networks in the ATNC are less developed except for Kunming in the southwest and Urumchi in the northwest because of their strategic locations for geographic and political reasons. The ANTC is relatively young, and not as efficient and well-developed as that of the US.     

Connectivity of the European airport network: “Self-help hubbing” and business implications

This paper investigates the connectivity of the European air transportation network. A time-dependent minimum path approach is employed to calculate the minimum travel time between each pair of airports in the network, inclusive of flight times and waiting times. The connectivity offered by each alliance's network is compared with that of the overall network. The results show that roughly two-thirds of the fastest indirect connections are not operated by the alliance system; this could be exploited to enable a new passenger strategy of “self-help hubbing”.     

Evolution of the international air transportation country network from 2002 to 2013

In this research, we analyze the evolution of the international air transportation country network from 2002 to 2013 with two perspectives: The network’s physical topology and the functional network with traffic information. Our analysis shows that the network is scale-free and has the small-world property. The evolution of triadic properties suggests that the network gears towards symmetric, transitive closure. We find that United States, Great Britain, and France are critical from both perspectives; Surprisingly, South Africa is particularly critical from topological point of view. Furthermore, topological and functional criticality are highly correlated to the GDP of a country.     

Multimarket contact, alliance membership, and prices in international airline markets

This paper tests the mutual forbearance view in the context of airline alliances in the international air travel market. Using passenger booking and airfare data on transpacific routes, we find consistent evidence for the positive association between multimarket contact and airfares. Our results also suggest that multimarket contact between non-aligned airlines is associated with higher airfares, whereas multimarket contact between airlines in the same alliance has no additional upward impact on airfares. Moreover, it is shown that higher airfares tend to exist when airlines have greater multimarket contact on open-skies routes. In restrictive (non-liberal) international markets, however, multimarket contact may not affect airfare.     

Factors influencing the hub connectivity of Beijing Capital Airport in its international markets

This paper investigates factors influencing the hub connectivity of Beijing Capital Airport (PEK) in its domestic to international markets between 2014 and 2018 based on a random-effect panel data model. The results show that variables representing the temporal and spatial characteristics of connecting flights have significant impacts on the hub connectivity of PEK. In specific, the changeable threshold of maximum connecting time based on different international destination regions has a negative impact. This paper identifies different timetable coordination modes at PEK and shows that the number of indirect connections under adjacent mode is significantly less than that of distant mode. Circuity and directionality are proven to have significant impacts. In addition, factors representing airport characteristics and heterogeneity of international destination regions also affecting the hub connectivity of PEK.     

Stochastic programming approach to re-designing a warehouse network under uncertainty

The warehouse network re-design problem includes integrating or eliminating existing warehouses and establishing new sites. In this paper, we incorporate variability in product demand and operational costs with a two-stage stochastic modeling approach. We use the Sample Average Approximation (SAA) approach together with Benders decomposition to provide a solution method. Our results indicate not only that the stochastic solution is an improvement over the deterministic solution but also that the solutions’ differences grow with increasing uncertainty. The stochastic solutions show more robustness than the deterministic solutions. The computational results show that a change in the type of probability distribution of the stochastic parameters does not significantly affect the value of the stochastic solutions.     

Scheduling issues and network strategies for international airline alliances

An efficient network structure with co-ordinated schedules is necessary to realise the potential of an international airline alliance. This paper considers the scheduling issues that particularly affect alliances including multiple hub operations, other interfaces between routes, airport slot and terminal allocations and the through working of aircraft. Key principles are identified and illustrated with examples from current airline operations. Comparisons are made of the effectiveness of the major alliance groupings in the European arena and strategies to optimise the coverage and connectivity of the combined networks are advanced.     

A dynamic network efficiency measurement of airports performance considering sustainable development concept: A fuzzy dynamic network-DEA approach

In this paper, sustainability of airports is considered through a multi-perspective, multi-system, and multi-process operation. It is explored how an extension of fuzzy dynamic network performance measurement approach helps to determine the efficiency performance of an airport system. In this way, a three-pronged approach is intended which considers the internal functions of an airport, functions affecting the community and functions related to the passengers simultaneously. This novel combination makes it possible to have a comprehensive evaluation of airports' performance. Besides, fuzzy extension of SBM dynamic network approach makes it possible to deal better with the vagueness of variables during analysis. So, this extension is valuable from both technical and conceptual aspects which in turn provide useful information and insights for the future design of holistic strategies connected with sustainable development of airports where ever they are.     

Performance measurement of a transportation network with a downtown space reservation system: A network-DEA approach

We propose an evaluation approach for a novel travel demand management strategy known as the downtown space reservation system (DSRS). This approach takes into account three perspectives, i.e., transportation service provider’s, the user’s, and the community’s and is based on network-Data Envelopment Analysis (DEA) where the perspectives are inter-related through intermediate inputs/outputs. Two types of network-DEA models (radial and slacks-based models) are considered. An example is provided using data propagated from a microscopic traffic simulation model of the DSRS. The results show that individual node performance can drive network DEA performance and that this information can inform future designs of the DSRS.     

A complex network approach towards modeling and analysis of the Australian Airport Network

An airport network forms the backbone of any air transportation system. The relationships among the origins and destinations of flights result in a complex network of routes which can be complemented with information associated with the routes themselves, for instance, traffic load and distance. In this paper, we modeled the Australia's civil domestic airport infrastructure as a network and analyzed the resulting network structure and its features using complex network tool. This case study identifies and investigates complex network measures, such as the degree distribution, characteristics path length, clustering coefficient and centrality measure as well as the correlations among them to understand the topology of an airport network. This analysis of the Australian Airport Network (AAN) indicates that it has a cumulative degree distribution described by the power-law function. As it has an average path length of 2.90, it is considered to have small-world properties. It is also found that it has a clustering coefficient of 0.50 which is higher than that of a random network of the same size which indicates that the transitivity and cohesiveness of AAN is different from a random network. In contrast to the World-wide Airport Network (WAN), the AAN is found to have disassortative mixing similar to the airport networks of China and India.     

A Linear Programming approach for robust network revenue management in the airline industry

The classical revenue management problem consists of allocating a fixed network capacity to different customer classes, so as to maximize revenue. This area has been widely applied in service industries that are characterized by a fixed perishable capacity, such as airlines, cruises, hotels, etc.It is traditionally assumed that demand is uncertain, but can be characterized as a stochastic process (See Talluri and van Ryzin (2005) for a review of the revenue management models). In practice, however, airlines have limited demand information and are unable to fully characterize demand stochastic processes. Robust optimization methods have been proposed to overcome this modeling challenge. Under robust optimization framework, demand is only assumed to lie within a polyhedral uncertainty set (Lan et al. (2008); Perakis and Roels (2010)).In this paper, we consider the multi-fare, network revenue management problem for the case demand information is limited (i.e. the only information available is lower/upper bounds on demand). Under this interval uncertainty, we characterize the robust optimal booking limit policy by use of minimax regret criterion. We present an LP (Linear Programming) solvable mathematical program for the maximum regret so our model is able to solve large-scale problems for practical use. A genetic algorithm is proposed to find the booking limit control to minimize the maximum regret. We provide computational experiments and compare our methods to existing ones. The results demonstrate the effectiveness of our robust approach.     

An integrated performance evaluation approach for the Indian international airports

This paper deals with the applications of best worst method (BWM) and multi-attributive border approximation area comparison (MABAC) method to assess the performance of 32 major Indian international airports based on eight evaluation criteria. The BWM is applied to derive the criteria weights based on the opinions of four decision makers, while MABAC method is employed to rank the considered airports from the best to the worst along with the identification of their relative strengths and weaknesses. The advantages of these methodologies are also enumerated. It is observed that annual revenue is the most important evaluation criterion, followed by the total number of passengers. Based on this integrated analysis, Indira Gandhi International Airport and Surat International Airport respectively emerge out as the best and the worst performing international airports in India.     

A hybrid Tabu Search approach for the design of a paper recycling network

This paper addresses the design of a paper recycling network including external procurement, in-house recycling of paper, technology selection and selling or disposing of co-products. In contrast to the literature, we consider a combined continuous and discrete facility location problem solved by a hybrid Tabu Search approach to enhance candidate facility locations. We provide rules of thumb regarding the length of the tabu list and suggestions regarding runtime boundaries in cases where pre-evaluations are elaborate. The results based on a real-life application case show the potential savings of in-house paper recycling compared to the solely external procurement of recovered paper.     

Collaboration and cooperation in a tourism destination: a network science approach

The extent of collaboration and cooperation is an important determinant for the development of a tourism destination. These features are usually assessed through qualitative investigations. This letter proposes a quantitative approach based on the evaluation of the modularity characteristics of the network of the destination stakeholders. The results of a sample analysis are reported.     

Fare dispersions in airline markets: A quantitative assessment of theoretical explanations

There are substantial fare dispersions in the airline industry. There are various theoretical explanations of this, but they only provide a qualitative justification of the phenomenon. This paper simulates the quantitative outcome of three popular models to evaluate their ability to generate substantial fare dispersions. We find that, in duopoly, the maximum fare dispersion that each model can generate is quite limited; and, even for the most favourable case, it is about one-third of the observed fare variability. Moving to more competitive market structures, however, some models generate better results.