The module building process in Section 3 includes the integration
process. This is a process for establishing the interface relationship
between modules. Based on this, the integrated model should set the same
number of ships, mechanics, maintenance policy, etc. The method is the
same as the add process in section 3, but the model becomes visually
complex as shown in Fig. 8. The simulation result of the integrated
model should be able to simulate the real result as it is. Therefore,
validation through robustness or sensitivity tests in DT is more
important.
The implementation of the functions included in the modules of Section 3
utilized the lookup function of the system dynamics tool (Vensim). The
purpose of this study is to show that multi-physics and multi-scale
problems can be solved by using system dynamics. In the DT building
process, these lookup functions can be designed to be continuously
updated during the simulation process. This is because the latest tools
support data calibration using MCMC (Markov chain monte carlo) and link
with programming languages (python, R, etc.) or other analysis methods
(analysis tools). For details, see Richardson (2015), Sücüllü, C., &
Yücel (2014).
The integrated model is shown in Fig. 8. Compared to the model in
Section 3.3, it is visually more complex, but the model operation
process is the same. The items additionally reflected in the model are
as follows. The number of ships increased from 1 to 6. A virtual waiting
space was applied because a queue may occur in the movement of the ship
between the battle field and the repair shop. It was modified to handle
normal failure and critical failure separately. And the night additional
work of the mechanics was set to be possible up to 4 hours a day. The
ages of the 6 ships are all different, and the ages of the actual naval
fleet ships are applied.
In the work of increasing the number of ships to 6, it is necessary to
make sure that the priorities of entering the repair shop do not
conflict, but it is not difficult. It should be noted that multi-physics
support is possible. Although tangible and intangible physics such as
ships, number of people, and manpower have their own scales, they
interact with each other through causal relationships.
Validation of some variables included in the DT model is shown in Fig.
9. All reflected variables must be checked one by one. All variables of
the model reflected reality well.