the existing works considering the flow-based discount factor in the hub and spoke problems, assume that increasing the amount of flow passing through each edge of network continuously decreases the unit flow transportation cost. although a higher volume of flow allows for using wider links and consequently cheaper transportation, but the unit of flow enjoys more discounts, quite like replacing...

HLP (hub location problem) tries to find locations of hub facilities and assignment of nodes to extended facilities. Hubs are facilities to collect, arrange, and distribute commodities in telecommunication networks, cargo delivery systems, etc. Hubs are very crucial and their inaccessibility impresses on network whole levels. In this paper, first, total reliability of the network is defined bas...

The existing works considering the flow-based discount factor in the hub and spoke problems, assume that increasing the amount of flow passing through each edge of network continuously decreases the unit flow transportation cost. Although a higher volume of flow allows for using wider links and consequently cheaper transportation, but the unit of flow enjoys more discounts, quite like replacing...

the hub location decision is a long term investment and any changes in it take considerable time and money. in real situations, some parameters are uncertain hence, deterministic models cannot be more efficient. the ability of two-stage stochastic programming is to make a long-term decision by considering effects of it in short term decisions simultaneously. in the two-stage stochastic programm...

Introduction The Airline Deregulation Act (ADA) of 1978 caused many changes in the industry. For the first time in 40 years, new airlines were permitted to enter the industry, and all airlines could choose the routes they would serve and the fares they would charge. Airlines were also free to exit the industry (go bankrupt), if they made poor choices in these matters. Naturally, this has led to...

Functional hubs are brain regions that play a crucial role in facilitating communication among parallel, distributed brain networks. The developmental emergence and stability of hubs, however, is not well understood. The current study used measures of network topology drawn from graph theory to investigate the development of functional hubs in 99 participants, 10-20 years of age. We found that ...

BACKGROUND The healthcare industry is characterized by intensive, never-ending change occurring on a multitude of fronts. Success in such tumultuous environments requires healthcare providers to be proficient in myriad areas, including the manner in which they organize and deliver services. Less efficient designs drain precious resources and hamper efforts to deliver the best care possible to p...

This note explores the extent to which airlines operating large hub-and-spoke networks secure a competitive advantage. More speci®cally, this paper explores the intricate relationship which arises among productive eciencies and pro®tability when the size of the hub-and-spoke network expands. To this end, Brueckner and Spiller (1991, International Journal of Industrial Organization 9, 323±342) ...

Transportation networks frequently employ hub-and-spoke network architectures to route flows between many origin and destination pairs. In this paper, we deal with a problem, called the single allocation hub-and-spoke network design problem. In the single allocation hub-andspoke network design problem, the goal is to allocate each non-hub node to exactly one of given hub nodes so as to minimize...