this paper proposes a new mathematical model for designing and planning postal parcels carriage and postal networks. the objective of postal network designing is to determine the location, size and connection between the postal stations in a city, province or country. in this paper, a kind of multiple locations-allocations hub problem with limited capacity in collecting, distributing and broadc...

In this paper, we consider the design of large-scale hub-and-spoke transportation networks in a competitive environment. We adopt the hub arc location model that locates arcs with discounted transport costs connecting pairs of hub facilities. Two firms compete for passengers in a Stackelberg framework where the leader firm locates hub arcs to maximize its revenue, given that the follower firm w...

We consider the hub location problem, where p hubs are chosen from a given set of nodes, each nonhub node is connected to exactly one hub and each hub is connected to a central hub. Links are installed on the arcs of the resulting network to route the traffic. The aim is to find the hub locations and the connections to minimize the link installation cost. We propose two formulations and a heuri...

The airlines reorganization will accelerate the switch of the Chinese mainland civil aviation system from a former point-to-point (PP) structure to a hub-and-spoke (HS) network. In such a context, the major efforts of our paper are put into identifying hub airports in mainland China. We first analyze the HS network’s competitive advantages and find four desirable hub characteristics. A three-le...

INTRODUCTION Sci-Hub is a useful web portal for people working in science as it provides access to millions of free scientific articles. Satisfaction and usage should be explored in the Latino student population. The objective of this study was to evaluate the use, knowledge, and perception of the scientific contribution of Sci-Hub in medical students from Latin America. METHODOLOGY A multice...

INTRODUCTION Worldwide use of intravascular catheters (IVC) has been associated with both local and systemic infections. No studies have been done in the sub-Saharan region on IVC related infections. OBJECTIVE To determine the prevalence, causative organisms and their antimicrobial susceptibility pattern and the factors associated with infections related to short term peripheral venous cathet...

AIM To identify factors associated with severe femoral vein (FV) damage among groin injectors (GIs) on oral opioid substitution treatment. DESIGN A cohort study. SETTING Drug treatment centres in South East England. PARTICIPANTS GIs attending an ultrasound 'health-check' clinic. MEASURES Femoral ultrasonography and clinical grading of venous disease in each leg. METHOD Comparison of 6...

The hub location problem appears in a variety of applications including airline systems, cargo delivery systems, and telecommunication network design. When we analyze an application separately, we observe that each area has its own characteristics. Hub location problems deal with finding the location of hub facilities and with the allocation of demand nodes to these located hub facilities. This...