Multi-tier cross-department scheduling model for order processing operations
A multi-tier cross-department scheduling model for order processing operations. A scheduling model for planning assignment of discrete jobs to multiple departments for shipment, wherein selected jobs are assignable to respective selected departments and the departments share finite capacity resources, includes a programmable computer system having loaded therein an objective function, and the computer system being operable to minimize a value of the objective function; and wherein the objective function comprises a sum of cost to ship containers in at least one of consolidated and unconsolidated forms, cost for each of a container equivalent not completed in a selected scheduling horizon, cost to process each job in each department, and cost for setup due to at least one of shift crossing and job splitting.
1. A scheduling model system for planning assignment of discrete jobs to multiple departments for shipment, wherein selected jobs are assignable to respective selected departments, and the departments share finite capacity resources, the model comprising:
a programmable computer system having loaded therein an objective function, and the computer system minimizes a value of the objective function; and
wherein the objective function comprises a sum of cost to ship containers in at least one of consolidated and unconsolidated forms, cost for each of a container equivalent that is not completed in a selected scheduling horizon, cost to process each job in each department, and cost for setup due to at least one of shift crossing and job splitting,
wherein the cost for each of a container equivalent that is not completed in a selected scheduling horizon is represented in the objective function by the expression
∑
k
=
1
n
P
2
C
k
B
k
(
B
k
-
∑
j
∈
R
∑
i
=
1
r
Y
ikj
)
wherein P 2 is a cost of shipping by an alternative mode of transportation, i is a shift index number from 1 to r, j is a department index number from 1 to m, k is a job index number from 1 to n, C k is a number of containers to be generated by job k, B k is a number of pieces to be shipped in job k, Y ikj is a number of pieces of job k shipped during shift i in department j, and R is a set of picking and processing departments other than merging or sorting departments.
2. The scheduling model system of claim 1 , wherein the cost to ship containers in at least one of consolidated and unconsolidated forms is represented in the objective function by the expression
P
1
∑
k
=
1
n
∑
i
=
1
r
X
i
,
k
,
j
1
+
P
1
∑
k
=
1
n
∑
i
=
1
r
∑
j
∈
j
2
X
_
i
,
k
,
j
wherein P 1 is a shipping cost per container, i is a shift index number from 1 to r, j is a department index number from 1 to m, k is a job index number from 1 to n, X i,k,j1 is a number of containers of job k processed in a selected merge department j 1 during shift i, X i,k,j is a number of containers of job k diverted direct to shipping from department j during shift i, and j 2 is a subset of departments including the selected departments.
3. The scheduling model system of claim 1 , wherein the cost to process each job in each department is represented in the objective function by the expression
∑
j
∈
R
∑
k
=
1
n
∑
i
=
1
r
(
d
kj
Y
ikj
)
.
wherein i is a shift index number from 1 to r, j is a department index number from 1 to m, k is a job index number from 1 to n, Y ikj is a number of pieces of job k shipped during shift i in department j, d kj is a unit cost to process job k in department j, and R is a set of picking and processing departments other than merging or sorting departments.
4. The scheduling model system of claim 1 , wherein the cost for setup due to at least one of shift crossing and job splitting is represented in the objective function by the expression
P
3
∑
k
=
1
n
∑
i
=
1
r
M
ik
wherein P 3 is a setup cost accounting for labor needed to switch between jobs or shifts, i is a shift index number from 1 to r, k is a job index number from 1 to n, and M ik is equal to 1 if job k is processed in shift i, and is equal to 0 if job k is not processed in shift i.
5. A method of scheduling discrete jobs for shipment from multiple departments which share finite capacity resources, the method comprising the steps of:
constructing an objective function which comprises a sum of cost to ship containers in at least one of consolidated and unconsolidated forms, cost for each of a container equivalent that is not completed in a selected scheduling horizon, cost to process each job in each department, and cost for setup due to at least one of shift crossing and job splitting;
loading the objective function into a programmable computer system; and
programming the computer system to minimize a value of the objective function, and then the computer system minimizing the value of the objective function,
wherein the objective function constructing step includes representing the cost for each of a container equivalent that is not completed in a selected scheduling horizon by the expression
∑
k
=
1
n
P
2
C
k
B
k
(
B
k
-
∑
j
∈
R
∑
i
=
1
r
Y
ikj
)
wherein P 2 is a cost of shipping by an alternative mode of transportation, i is a shift index number from 1 to r, j is a department index number from 1 to m, k is a job index number from 1 to n, C k is a number of containers to be generated by job k, B k is a number of pieces to be shipped in job k, Y ikj is a number of pieces of job k shipped during shift i in department j, and R is a set of picking and processing departments other than merging or sorting departments.
6. The method of claim 5 , wherein the objective function constructing step includes representing the cost to ship containers in at least one of consolidated and unconsolidated forms by the expression
P
1
∑
k
=
1
n
∑
i
=
1
r
X
i
,
k
,
j
1
+
P
1
∑
k
=
1
n
∑
i
=
1
r
∑
j
∈
j
2
X
_
i
,
k
,
j
wherein P 1 is a shipping cost per container, i is a shift index number from 1 to r, j is a department index number from 1 to m, k is a job index number from 1 to n, X i,k,j1 is a number of containers of job k processed in a selected merge department j 1 during shift i, X i,k,j is a number of containers of job k diverted direct to shipping from department j during shift i, and j 2 is a subset of departments including the selected departments.
7. The method of claim 5 , wherein the objective function constructing step includes representing the cost to process each job in each department by the expression
∑
j
∈
R
∑
k
=
1
n
∑
i
=
1
r
(
d
kj
Y
ikj
)
wherein i is a shift index number from 1 to r, j is a department index number from 1 to m, k is a job index number from 1 to n, Y ikj is a number of pieces of job k shipped during shift i in department j, d kj is a unit cost to process job k in department j, and R is a set of picking and processing departments other than merging or sorting departments.
8. The method of claim 5 , wherein the objective function constructing step includes representing the cost for setup due to at least one of shift crossing and job splitting by the expression
P
3
∑
k
=
1
n
∑
i
=
1
r
M
ik
wherein P 3 is a setup cost accounting for labor needed to switch between jobs or shifts, i is a shift index number from 1 to r, k is a job index number from 1 to n, and M ik is equal to 1 if job k is processed in shift i, and is equal to 0 if job k is not processed in shift i.