According to several studies, the power consumption of the Internet accounts for up to 10% of the worldwide energy consumption, and several initiatives are being put into place to reduce the power consumption of the ICT sector in general. To this goal, we propose a novel approach to switch off network nodes and links while still guaranteeing full connectivity and maximum link utilization. After...

According to several studies, telecom operators account for a not negligible power consumption, and several initiatives are being put into place to reduce the power consumption of the ICT sector in general. To this goal, we propose a novel approach to switch off some portions of the UMTS core network while still guaranteeing full connectivity and maximum link utilization. After showing that the...

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...

We present a branch-and-cut algorithm to solve the single commodity uncapacitated fixed charge network flow problem, which includes the Steiner tree problem, uncapacitated lot-sizing problems, and the fixed charge transportation problem as special cases. The cuts used are simple dicut inequalities and their variants. A crucial problem when separating these inequalities is to find the right cut ...

We propose a static uncapacitated multi-commodity flow model along with a time-based scheduling tool for solving evacuation scheduling problems with capacity constraints. The paper addresses the problem of modeling evacuation scheduling out of an affected area, there are a pre-defined set of exit points out of the target affected area and a set of source points for the evacuees. The proposed ap...

We consider the single-commodity single-origin fixed-charge network flow problem (SSFNP) defined on a directed network G = (V,A), where V is the node set and A is the arc set, with each arc a represented by the ordered pair of head and tail nodes (h(a), t(a)). The node set includes a single origin (with no incoming arc), multiple destinations (with no outgoing arc) and transshipment nodes (with...

We consider a capacitated plant location problem with multi-commodity flow on a two-level network including plants and transshipment points. The objective is to locate plants and determine commodities movement while satisfying customers’ demand and minimizing costs. We present a new and effective hybrid method, composed from Lagrangean Relaxation and UB Creating Method to solve the problem. We ...

in this paper, a novel multi-objective bus stop location model is proposed, which considers not only the coverage of demand and minimization of access time but also the necessities of suitable stops for transit network design phase. three objective functions are considered including minimizing (i) sum of the total access distance (time), (ii) the weighted combination of stops, and (iii) the num...

The multi-commodity network flow problem (MCNF) consists in routing a set of commodities through capacitated at minimum cost and is relevant for containers liner shipping networks. As commodity transit times are often critical factor, the literature has introduced hard limits on times. In practical contexts, however, these may fail to provide sufficient flexibility since routes with even tiny d...