Page 251 - DCAP601_SIMULATION_AND_MODELING

Unit 13: Simulation Languages (I)

excess changeovers. Large custom orders may require extra processing at a point where Notes
the system has particularly low capacity. Simulation modeling allows management to
understand what changes ‘on average’ would have the largest impact and greatest return-
on-investment.
4. Lab Test Performance Improvement Ideas: Many systems improvement ideas are build on
sound principles, proven methodologies (Lean, Six Sigma, TQM, etc.) yet fail to improve
the overall system. A simulation model allows the user to understand and test a performance
improvement idea in the context of the overall system.
5. Evaluating Capital Investment Decisions: Simulation modeling is commonly used to
model potential investments. Through modeling investments decision-makers can make
informed decisions and evaluate potential alternatives.

Often these decisions look at altering existing operations. Typically, a model of the current
state is constructed. This ‘current state’ model is tested and validated against historical
data. Once the model is operating correctly, the simulation is altered to reflect the proposed
capital investments. This ‘future state’ model is then stress-tested to ensure the alterations
perform as desired.

Occasionally, organizations take on entirely new operations processes. These could be
new Lean facilities, designed around new products or using new technology. In these
cases only a ‘future state’ model is constructed. The testing and validation may require
more analysis. There are companies and experts that specialize in simulation building
who may be brought in to help.
6. Stress Test a System: Models can be used to understand how a system will be able to
weather extraordinary conditions. A simulation can help management understand: large
increases in orders, significant swings in product mix, new client delivery demands (i.e. 1
week lead times), and economic events (i.e. a multinational with operations in South
America and Asia sees significant swings in currencies).

Visualisation

Visual Interactive Simulation (VIS) has been available since the late 1970’s. Before this simulation
models were simply ‘black boxes’ - data going in and results coming out. In such a scenario
establishing credibility and confidence in the simulation model would not have been easy.
Using on-screen animations in a simulation model enables the status of the model to be viewed
as it progresses e.g. a machine that breaks down may change its color to red. This enables visual
cues to be passed back to the operator of the simulation model, so action could be taken.
Additionally, visualisation is useful in convincing management of the model’s credibility. For
example, in manufacturing if the Directors can see a visualisation of the production line with
widgets travelling down a conveyor belt, it would do more to sell the concept of the model than
a ‘black box’, churning out data.
With VIS the prime motivation is not only portrayal of the running simulation model but also
the interaction with it. For example, in using the above scenario, if the User wanted to see how
the production line would run with an extra machine then he could simply ‘plug in’ a machine,
at the appropriate position, and monitor the effect that this would have on the model.
Visual Interactive Modelling (VIM) takes this concept one stage further by allowing the model
to be created interactively. This allows a model to be constructed by dragging (with a mouse)

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