Mathematical Model and Simulated Annealing Algorithm for the Two-Dimensional Loading Heterogeneous Fixed Fleet Vehicle Routing Problem

Table 2

Model sets, parameters, and variables.

Indexes/sets
	Set of vertices from the depot () to customers ()
	Set of vehicles
	Set of stages in which a customer can be served by a vehicle
	Set of items demanded by all customers. Each customer demands a set
Parameters
	Number of customers
	Distance from each customer to each customer
	Number of vehicles
	Weight capacity of each vehicle
	Length of the loading surface of each vehicle
	Width of the loading surface of each vehicle
	Fixed cost of each vehicle
	Variable cost of each vehicle
	Number of items demanded by each customer
	Total weight demanded by each customer
	Length of each item
	Width of each item
Variables
	Binary variable that indicates whether vehicle goes directly from vertex to vertex in stage () or not
	Continuous variable that indicates the -coordinate of the front-left corner of item on the vehicle loading surface
	Continuous variable that indicates the -coordinate of the front-left corner of item in the vehicle loading surface
	Binary variable that indicates whether item is loaded into vehicle or not
	Binary variable that indicates whether item is loaded behind item or not
	Binary variable that indicates whether item is loaded in front of item or not
	Binary variable that indicates whether item is loaded on the left side of item or not
	Binary variable that indicates whether item is loaded on the right side of item or not