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New Program for Modeling and Simulation
by Tom Abel
At the last emergy conference I had a poster on a simulation
environment that I had developed with the assistance of two student
programmers at my university. A few people took copies of it (although
it was missing the final version of the Help file). I now have it available
on my website here:
http://www.tabel.tcu.edu.tw/SystemsModeling-V1.rar
You can read the abstract and features that I copied from my poster
below. Hopefully it will be useful. I’m interested in any feedback from
people. Don’t forget to read the ReadMe file.
This brings up a general question-do people still use systems modeling in
their teaching (yes)? In their research (no)?
My apologies to Mac users, it only runs on PCs. The history is that I
originally intended to make this a web-based application, executed from
your browser and therefore platform free. For that reason the
programmers used a language called C#. Unfortunately we encountered
a few difficulties in addition to time limits. It runs well now as a stand-
alone C# application, but it can only run on PCs. Also, on your PC you
will need to install the Microsoft .NET Framework (an environment that
runs in the background and allows the execution of stand-alone C#, J#,
VB.NET and others). Sorry for the inconvenience - heck, it’s free!
ABSTRACT: A number of simulation environments have been utilized
for systems modeling (Odum and Odum 2000). These include Extend,
Stella, Excel Spreadsheets, and Basic. There are advantages and
disadvantages of each. Extend and Stella are object oriented simulation
environments that permit the user to apply predefined objects
representing storages, sources, etc., and link them with flows. The
simulation produces graphs of flow and storage values as selected by the
user. Shortcomings of these environments include (in the case of
Extend) poor graphics for representing systems models, and modeling
that is limited to the objects previously defined by others (or requiring
difficult programming of new objects), or (in the case of Stella) no
recognizable systems model, and complicated procedures for ‘adapting’
systems modeling to the Stella language. The greatest shortcoming,
however, is the loss of pedagogical value in the systems modeling
exercise. By using predefined objects!
For example, the student is not required to write the relatively simple
difference equations that are the heart of the systems modeling exercise.
Excel and Basic systems modeling environments do not suffer this
shortcoming. In both cases, it is necessary to manually write the
difference equations, and in addition to calculate flow coefficients.
These two exercises create a deeper understanding of the simulation
process. However, both environments require tedious coding for much
of the overhead needed to generate simulation graphs, and calculate
coefficients. Further, in the Excel case, the difference equations are
buried in cells and review and modification are difficult. In the Basic
case, finding a desirable Basic programming environment is nearly a lost
cause. For these reasons, a new simulation environment has been
produced. The program is written in C#, and will be available free as a
compiled runtime application that can run on any PC (it requires the .
NET environment!
It includes an extensive HELP. The application was written by two
student programmers under the guidance of Thomas Abel, all of Tzu Chi
University.
Features
The user will program every flow equation and difference equation; the
software assists the user with some automated inputs
The environment allows the user to initialize all flows, storages, R’s, and
sources; with that data and the flow equations the user calculates
coefficients via an automated function. The environment uses a powerful
graphing module called NEVRON Chart, which can produce publication
quality jpg files from simulation runs
Graphic displays can be the customary 2D curves, or alternately 3D with
multiple starting values for sensitivity testing and simulation exploration.
Systems diagrams are easily linked and stored with each model
Thomas Abel
Tzu Chi University
Hualien, Taiwan
Phone: 857-2677 Ext. 2416
http://www.tabel.tcu.edu.tw/
New Program for Modeling and Simulation
by Tom Abel
At the last emergy conference I had a poster on a simulation
environment that I had developed with the assistance of two student
programmers at my university. A few people took copies of it (although
it was missing the final version of the Help file). I now have it available
on my website here:
http://www.tabel.tcu.edu.tw/SystemsModeling-V1.rar
You can read the abstract and features that I copied from my poster
below. Hopefully it will be useful. I’m interested in any feedback from
people. Don’t forget to read the ReadMe file.
This brings up a general question-do people still use systems modeling in
their teaching (yes)? In their research (no)?
My apologies to Mac users, it only runs on PCs. The history is that I
originally intended to make this a web-based application, executed from
your browser and therefore platform free. For that reason the
programmers used a language called C#. Unfortunately we encountered
a few difficulties in addition to time limits. It runs well now as a stand-
alone C# application, but it can only run on PCs. Also, on your PC you
will need to install the Microsoft .NET Framework (an environment that
runs in the background and allows the execution of stand-alone C#, J#,
VB.NET and others). Sorry for the inconvenience - heck, it’s free!
ABSTRACT: A number of simulation environments have been utilized
for systems modeling (Odum and Odum 2000). These include Extend,
Stella, Excel Spreadsheets, and Basic. There are advantages and
disadvantages of each. Extend and Stella are object oriented simulation
environments that permit the user to apply predefined objects
representing storages, sources, etc., and link them with flows. The
simulation produces graphs of flow and storage values as selected by the
user. Shortcomings of these environments include (in the case of
Extend) poor graphics for representing systems models, and modeling
that is limited to the objects previously defined by others (or requiring
difficult programming of new objects), or (in the case of Stella) no
recognizable systems model, and complicated procedures for ‘adapting’
systems modeling to the Stella language. The greatest shortcoming,
however, is the loss of pedagogical value in the systems modeling
exercise. By using predefined objects!
For example, the student is not required to write the relatively simple
difference equations that are the heart of the systems modeling exercise.
Excel and Basic systems modeling environments do not suffer this
shortcoming. In both cases, it is necessary to manually write the
difference equations, and in addition to calculate flow coefficients.
These two exercises create a deeper understanding of the simulation
process. However, both environments require tedious coding for much
of the overhead needed to generate simulation graphs, and calculate
coefficients. Further, in the Excel case, the difference equations are
buried in cells and review and modification are difficult. In the Basic
case, finding a desirable Basic programming environment is nearly a lost
cause. For these reasons, a new simulation environment has been
produced. The program is written in C#, and will be available free as a
compiled runtime application that can run on any PC (it requires the .
NET environment!
It includes an extensive HELP. The application was written by two
student programmers under the guidance of Thomas Abel, all of Tzu Chi
University.
Features
The user will program every flow equation and difference equation; the
software assists the user with some automated inputs
The environment allows the user to initialize all flows, storages, R’s, and
sources; with that data and the flow equations the user calculates
coefficients via an automated function. The environment uses a powerful
graphing module called NEVRON Chart, which can produce publication
quality jpg files from simulation runs
Graphic displays can be the customary 2D curves, or alternately 3D with
multiple starting values for sensitivity testing and simulation exploration.
Systems diagrams are easily linked and stored with each model
Thomas Abel
Tzu Chi University
Hualien, Taiwan
Phone: 857-2677 Ext. 2416
http://www.tabel.tcu.edu.tw/
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