Mathematical Problems in Engineering / 2015 / Article / Tab 2

Research Article

A Hybrid Approach to the Optimization of Multiechelon Systems

Table 2

Summary indices, parameters, and decision variables.



Number of satellites
Number of customers
Set of satellites
Set of customers


Number of the 1st-level vehicles
Number of the 2nd-level vehicles
Capacity of the vehicles for the 1st level
Capacity of the vehicles for the 2nd level
Demand required by customer
Cost of the arc()
Cost of loading/unloading operations of a unit of freight in satellite

Decision variables

An integer variable of the 1st-level routing is equal to the number of 1st-level vehicles using arc()
A binary variable of the 2nd-level routing is equal to 1 if a 2nd-level vehicle makes a route start from satellite and go from node to node and 0 otherwise
The freight flow arc() for the first level
The freight arc() where represents the satellite where the freight is passing through.
A binary variable that is equal to 1 if the freight to be delivered to customer is consolidated in satellite and 0 otherwise