Mathematics VS? Agent Based Modeling

[Parks, Raymond]

Robert Holmes wrote:
> And that got me thinking: has there been any (and I do mean any) real-world
> examples of using an ABM in a closed-loop control system (i.e. one that
> doesn't just produce some estimates of a control paramter but actually
> enacts them)? Such control systems are all around us and - as far as I can
> make out - they are all examples of EBMs (even the analogue ones).

   I don't have the web-site URL off-hand, but I believe that a German
control system company specializing in oil and gas pipelines mentioned
that their simulator uses an ABM.  The simulator's practical purpose is
to estimate when different substances pumped through the pipeline reach
the various egress points.  Different "loads" are separated by slugs,
but they move through the pipeline according the individual physics of
each load.  Fuel oil moves slower than avgas, for instance, and the
pressures vary.  There are other simulators in use in that industry for
leak detection, but I believe those are EBM.

--
Ray Parks                   [hidden email]
IDART Project Lead          Voice:505-844-4024
IORTA Department            Fax:[phone]
http://www.sandia.gov/idart Pager:800-690-5288

[Robert Holmes]

The distinction between open and close loop systems reminds me of the
distinction between asking forgiveness and asking permission. An open-loop
system produces some recommended set of parameter settings that a third
party (usually human) can choose to implement or not. A closed-loop system
calculates the parameter settings then goes ahead and applies them anyway.
When I use an ABM to predict the bottlenecks in a supply chain and I then
present the results to the client, that's an open-loop system. When the EBM
in my car's engine management system detects that I've done something dumb
and turns on the ABS, that's a closed-loop system.

(Simulators fall in an interesting grey area: is a simulator an example of
control system or an example of a simulation of a control system? These are
different, especially when things go pear-shaped.)

So my contention is that while ABMs may be great for advisory, open-loop
systems they just aren't robust enough to form the core of a closed-loop
system. How would you feel if the automatic control systems in your car
(plane, nuclear reactor etc.) where all written in NetLogo? ;)

Robert

> -----Original Message-----
> From: Raymond Parks [mailto:[hidden email]]
> Sent: Friday, March 11, 2005 10:47 AM
> To: The Friday Morning Applied Complexity Coffee Group
> Subject: Re: [FRIAM] Mathematics VS? Agent Based Modeling
>
> Robert Holmes wrote:
> > And that got me thinking: has there been any (and I do mean any)
> > real-world examples of using an ABM in a closed-loop control system
> > (i.e. one that doesn't just produce some estimates of a control
> > paramter but actually enacts them)? Such control systems are all
> > around us and - as far as I can make out - they are all
> examples of EBMs (even the analogue ones).
>
>    I don't have the web-site URL off-hand, but I believe that
> a German control system company specializing in oil and gas
> pipelines mentioned that their simulator uses an ABM.  The
> simulator's practical purpose is to estimate when different
> substances pumped through the pipeline reach the various
> egress points.  Different "loads" are separated by slugs, but
> they move through the pipeline according the individual
> physics of each load.  Fuel oil moves slower than avgas, for
> instance, and the pressures vary.  There are other simulators
> in use in that industry for leak detection, but I believe
> those are EBM.
>
> --
> Ray Parks                   [hidden email]
> IDART Project Lead          Voice:505-844-4024
> IORTA Department            Fax:[phone]
> http://www.sandia.gov/idart Pager:800-690-5288
>
>
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