From Logistic Networks to Social Networks

2Modeling Discrete Flow Networks

2.1. Introduction

In the diversity of network services and infrastructures, invariants appear: any network is a distributed system resulting from the interconnection of nodal components that interact by exchanging physical objects, information, fluids or energies. These exchanges form the flows (material, information, continuous or discrete¹) circulating within the network. The ability of a network to handle flows is a determining factor in performance, both for the quality of the service offered to users and for the productivity of the logistics operators.

On the basis of flow movements, we can distinguish different transmission methods, all of which set into motion physical effects and their associated management methods.

In the case of material flows, we distinguish the following:

• – Transmission via a physical infrastructure (fluid distribution networks, electrical distribution networks). In this case, the contributions into the network are shared and the flows result from the withdrawal of the fluid or the energy consumed by the users. Billing of services is certainly carried out on the basis of consumption readings, but the transmission of flows from production sources to consumers is essentially a physical effect, and there is no need to manage the routing of these flows. The control tasks incumbent on operators therefore boils down to the regulation of physical parameters (pressure within the gas or water distribution networks, voltage, ...