Simulation
Fig. 1
Table 1
Table 2
Average Demand Standard Deviation
Demand
DC1 70 35
DC XXXXXXXXXX
DC XXXXXXXXXX
DC4 46 45
A discrete-event simulation model is to be constructed to capture the product flow depicted
in Fig. 1 that will allow for disruptions at each of the nodes. All inputs were set independently
and were fixed for each simulation scenario run. The risk profiles are one set of inputs, as well as
First Echelon
M1 S1
S2 S5
XXXXXXXXXXS4
S XXXXXXXXXXM XXXXXXXXXXDC1
DC4
PKG2
PKG1
DC3
DC2
Second Echelon
Fourth Echelon
Third Echelon
https:
www.sciencedirect.com/science/article/pii/S XXXXXXXXXX?via%3Dihub#f0005
the recovery data: for each site that could be disrupted, a back-up (or mitigation) was built into
the model to provide additional capacity.
Risk profiles for the locations and connections in the supply chain of figure 1 are developed using
Monte Carlo simulation, and the flow of material and network interactions are modeled using discrete-
event simulation. Capturing both the risk profiles and material flow with simulation allows for a clear
view of the impact of disruptions on the system.
For the disruption simulation, the selected nodes are S3, S5,M2, PKG2. The disruption parameters are
duration of disruption, supply disruption, demand disruption, and presence of mitigation.
Demand values at DC1, DC2, Dc3, and DC4 under a steady state is computed in terms of average
demand and standard deviation demand, and these are shown in table 2. The demand values follow a
uniform distribution. .
The response variable total service level was measured in a two-step process. First, the entire supply
chain’s daily service level was measured by using the percentage of orders fulfilled on time for all
demand nodes. Second, the total service level response variable was calculated by taking the average of
the daily service level over the given measurement period. The total service level response variable was
measured as the aggregate of all the demand nodes as the supply chain is assumed to be operated by a
single entity. The base service level is 95%
The service level response variable values were collected in three distinct measurement periods (i.e.,
pre-, during- and post-disruption) over the course of a single simulation replication. The pre-disruption
period lasted for a total of 100 days, starting on day 100 and ending on day 200. Day 0 through day 100
was used to accommodate the warm-up period. The length of the disruption period varied from 60 to
180 days depending on the treatment combination being tested. Finally, the length of the post-
disruption period was fixed at 200 days.
Events
Each simulation run started on day 0 with the inventory levels of each node set to the calculated base
stock level (see Table 2). At the beginning of each day, each node calculated its inventory level and
placed an order to ensure that the base level value is maintained. Inventory was then received, queued
for production, and delivered where applicable. Finally, demand was realized and inventory holding
costs and stockouts were calculated. Stockout costs were only calculated for unmet external demand,
which was realized daily at the four demand nodes (i.e., DC1-DC4) according to a normal distribution
with parameter values equal to those shown in Table 2. The simulated supply chain operated in a steady
state following the conclusion of the warm-up period through day 200. On day 200, the disruption
parameters for the given treatment combination were activated. The specified disruption node had its
production capacity reduced, and all demand nodes (i.e., D1- D4) began to receive increased demand
according to the demand disruption factor level. In the presence of a capacity recovery mitigation
strategy, the capacity of the disrupted node began to increase. The disruption persisted for the specified
duration of 60, 120, or 180 days. At the conclusion of the disruption period, the demand nodes returned
to their original parameters and the disrupted node returned to 100% production capacity.
Summary of What I want to Do
(1) I would like the simulation to be done in such a manner that there would be a period of
pre-disruption when evrything about the supply chain was okay, a period of disruption
at the mentioned specific nodes when the demand rose to 40% and 100% with these
two factors: presence of mitigation and absence of mitigation. Also, the disruption is
simulated to have 75% supply disruption, and 50% supply disruption. This is defined as
S XXXXXXXXXXN for node S5 for instance.
At the end of the disruption, I would like to see when the supply chain would return back to the
initial performance status before the disruption.
Here is an example of how I would like the graph to look like:
Fig. 2
The graph shows the combination of S XXXXXXXXXXN and S XXXXXXXXXXM factors. The
meaning of this is S XXXXXXXXXXN is Supplier S3 experienced disruption for 180 days which led
to 100% increase in demand and 75% disruption in supply without mitigation. The ‘N’ stands for
No Mitigation, while ‘M’ stands for mitigation. So, basically, I will like to do for the following
combinations with respect to service level:
(1)S XXXXXXXXXXN vs S XXXXXXXXXXM
(2) S XXXXXXXXXXN vs S XXXXXXXXXXM
(3) S XXXXXXXXXXN vs S XXXXXXXXXXM
(4) S XXXXXXXXXXN vs S XXXXXXXXXXM
(5) PKG XXXXXXXXXXN vs PKG XXXXXXXXXXM
(6) PKG XXXXXXXXXXN vs PKG XXXXXXXXXXM
The graph is expected to look like what is in figure 2