Analysis of Logistics Linkage by Digital Twins Technology and Lightweight Deep Learning

Table 2

Parameter symbols.

Symbols	Description
P	Number of production workshops
N	Number of the orders to be processed
	The delivery date of order i
	Product quantity of order i
	Production process
	Number of optional equipment for operation j
P	Workshop number,  = 1, 2, …,
	Order no.
	Number of new orders at time T
	Product quantity of order i in workshop p
	Operation no
	The fixed production cost of workshop p
	Unit processing time of operation j of order i on machine kj in workshop p
kj	Number of processing equipment of operation j
	The variable production cost of workshop P
	Completing time of order i in workshop p
	Production decision variable, the j-th operation of order i on equipment kj
	Processing time of order i on processing equipment in workshop p
K	Vehicle no.
	Fixed cost of vehicle k
	Distribution decision variable, whether the products of customer a are distributed by vehicle k
Sa	Customer a’s service time
	Finishing time of process j of order i in workshop P. Ending time
	Warehousing time of order i in workshop P
	Storage time of order i in the production workshop p. Storage time
C	Number of customers
V	Customer and warehouse collection
ETc	Earliest delivery time allowed by customer c
K	Vehicle assembly
m	Number of vehicles used
	Maximum loading capacity of vehicle
	Unit storage cost
	Distribution decision variables
	Travel time from customer a to customer b
	Customer c’s delivery volume
	Penalty coefficient for vehicles not arriving at the delivery section
	Processing of operation j on order i in workshop p. Producing time
	Delivery time of order i in workshop p
C	Number of customers
	Latest delivery time allowed by customer c
	Delivery time of customer c
	Unit distribution cost of vehicle k
	Distance from customer a to customer b