Collaborative Vehicle Routing Problem in the Urban Ring Logistics Network under the COVID-19 Epidemic

Table 1

Notations for model.

Symbol	Description
Sets
C	Set of customer points
H	Set of DC points
V	Set of all points
Parameters
	Distance from to
	Travel time from to
	Unit distance cost of distribution vehicles
	Transfer cost per unit distance per unit volume of goods
F	Fixed cost of vehicles
Q	Maximum vehicle load
	Initial cargo volume of distribution center
	Demand for goods of customer in distribution center
	0-1 indicator variable, indicates whether the distribution center is directly connected
li	Earliest service time of customer
ei	Latest service time of customer
	Service time of customer
Decision variables
	Volume of goods on edge
	Value = 1 means that vehicle coming out from passes by edge , or value = 0
	Time that vehicle starts to serve customer