Discrete Event Simulation vs. System Dynamics

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"Eric Melse"
Junior Member
Posts: 2
Joined: Fri Mar 29, 2002 3:39 am

Discrete Event Simulation vs. System Dynamics

Post by "Eric Melse" »

Dear Mr. Wakeland,

Thank you for your referral to your web. The point raised there:

In discrete event models, the occurrence of events drives the model,
whereas in continuous models, the passing of time drives the model.

Made after the definition:

In continuous models, time advances in regular intervals, and the processes
vary directly with time. Examples: pollution from a factory and the flow of
fluid in a pipe.
Discrete event models deal with events and specific time intervals.
Examples: Processing customers through a line and processing parts through a
production system.

is what I try to discuss (against).
I agree with the objectives defined and the way methods are explained, but,
I disagree with the notion that time undergoes in continuous models
smooth changes, while in discrete models time undergoes changes
instantaneously in discrete steps. In either approaches time is sliced in
discrete steps (regular or irregular steps is irrelevant).

I argue that time is an independent variable in both cases, therefore,
time does not drive the model in continuous models.
At n-time, expressions formulated in continuous models result in a
particular mathematical result, which is very different from what
expressions formulated in discrete models would produce as result. The
differences between the two methods are in the formulations and what they
supposed to achieve, not in the way time is treated or simulated.

With best regards,

Eric Melse
From: "Eric Melse" <emelse@casema.net>

Drs E. Melse MBA
Van Vredenburchweg 30-B
2282SJ RIJSWIJK
The Netherlands

home tel. +31 (0) 70 414 07 67
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