Search found 63 matches
- Mon Dec 01, 2003 7:34 pm
- Forum: SD Mailing List Archive
- Topic: Discrete vs. continuous (or aggregated) representation
- Replies: 1
- Views: 7250
Discrete vs. continuous (or aggregated) representation
It seems to me that much of the discussion of discrete vs. continuous (or perhaps described as aggregated) representation in a model has been carried on in the abstract without defining the essential context and purpose of the representation. Regarding whether or not detailed information must accomp...
- Tue Nov 18, 2003 7:31 pm
- Forum: SD Mailing List Archive
- Topic: Urban dynamics follow through
- Replies: 2
- Views: 4037
Urban dynamics follow through
In message (SD4480) Peter Sanders gave obsolete publisher information for the following books that are now available from Pegasus Communications, Waltham, MA, USA. >2) Alfeld, Louis E., and Alan K. Graham. 1976. Introduction to Urban Dynamics. > >3) Forrester, Jay W. 1969. Urban Dynamics. > >5) Grah...
- Fri Nov 14, 2003 10:12 am
- Forum: SD Mailing List Archive
- Topic: Manufacturing Control Systems
- Replies: 30
- Views: 52635
Manufacturing Control Systems
Perhaps the information below will be useful. Information on System Dynamics Jay W. Forrester Information revised October 6, 2001 System Dynamics Bibliography: To order the system dynamics bibliography of over 4100 entries, specify IBM type PC, or Macintosh Send $35 in US$ drawn on a US bank to: Sys...
- Tue Sep 16, 2003 10:20 am
- Forum: SD Mailing List Archive
- Topic: Sustainability of Transport
- Replies: 1
- Views: 3279
Sustainability of Transport
Perhaps the information below will be useful. Information on System Dynamics Jay W. Forrester Information revised October 6, 2001 System Dynamics Bibliography: To order the system dynamics bibliography of over 4100 entries, specify IBM type PC, or Macintosh Send $35 in US$ drawn on a US bank to: Sys...
- Sun Sep 08, 2002 3:50 pm
- Forum: SD Mailing List Archive
- Topic: Using Systems Thinking to Teach Basic Math
- Replies: 6
- Views: 7846
Using Systems Thinking to Teach Basic Math
You should obtain: Fisher, D. M. (2001). Lessons in High School Mathematics: A Dynamic Approach. Hanover, NH, High Performance Systems, Inc. From a system dynamics viewpoint, Fisher treats Algebra I, Algebra II, Pre-calculus, and Calculus. -- ---------------------------------------------------------...
- Mon Aug 05, 2002 10:24 am
- Forum: SD Mailing List Archive
- Topic: Barry Richmond
- Replies: 0
- Views: 3173
Barry Richmond
Unfortunate news to all: Yesterday, Sunday, August 4, I received a sad and distressing phone call from Nancy Maville, vice president of High Performance. She said that Barry Richmond suffered a heart attack and did not survive. I assume it was Saturday. She said he had gone running with his daughter...
- Wed Jul 17, 2002 9:14 pm
- Forum: SD Mailing List Archive
- Topic: Differential equations
- Replies: 25
- Views: 40623
Differential equations
Several writers have recently implied that differential equations are a more fundamentally correct way of representing dynamic systems than the integrations in a system dynamics formulation. As examples, Christopher Barker wrote: > Standard SD approaches use stock formulae that attempt to >approxima...
- Tue Apr 16, 2002 9:55 pm
- Forum: SD Mailing List Archive
- Topic: Modeling Anticipation
- Replies: 8
- Views: 14248
Modeling Anticipation
Bill Braun asks how forecasts of he future can be incorporated in a model: >Can forecasts of the future be dynamically modeled, with information from >stocks (that represent a future state) feeding back into current decisions? > On must start by realizing that there is no information truly coming to...
- Sun Mar 17, 2002 9:05 pm
- Forum: SD Mailing List Archive
- Topic: SD Models from Written Text???
- Replies: 2
- Views: 3226
SD Models from Written Text???
There has been an interesting discussion exchange on formal methods to derive models from written text. The effort is probably worth pursuing for the insights it will yield about process. However, in any rather complicated modeling project, only a very minor fraction of the relevant information is t...
- Fri Mar 15, 2002 8:34 pm
- Forum: SD Mailing List Archive
- Topic: On information quality and appropriateness
- Replies: 3
- Views: 7735
On information quality and appropriateness
On June 23, 2001, in (SD2234), Elaine Lovitt asked about modeling the "effects of data quality on the work we perform.... if any work has been done on value of information or data quality modelling" I regret being so late in responding. There are two issues here--first, the appropriateness...
- Thu Nov 22, 2001 9:46 am
- Forum: SD Mailing List Archive
- Topic: models for urban systems
- Replies: 2
- Views: 7292
models for urban systems
The information below may be useful. =============================================== =============================================== Information on System Dynamics Jay W. Forrester Information revised October 6, 2001 System Dynamics Bibliography: To order the system dynamics bibliography of over 410...
- Sat Nov 17, 2001 10:14 am
- Forum: SD Mailing List Archive
- Topic: Attractiveness Multiplier, does it matter?
- Replies: 0
- Views: 5632
Attractiveness Multiplier, does it matter?
George Richardson wrote, regarding the formulation of multipliers in "Urban Dynamics." >My bet would be the more multipliers in the formulation, the LESS >volatile it (the value of the product) becomes. There would be >myriad feedback effects that would actively compensate for extreme >val...
- Sat Nov 10, 2001 8:14 pm
- Forum: SD Mailing List Archive
- Topic: Attractiveness Multiplier
- Replies: 12
- Views: 33287
Attractiveness Multiplier
In Attractiveness Multiplier (SD3448), Bill Braun wrote: >With three variables, if each produces a value of 0.9 (through their >respective table functions), overall attractiveness is 0.729. ...... >This suggests that the greater the >number of variables determining attractiveness, the more "con...
- Mon Oct 15, 2001 8:48 pm
- Forum: SD Mailing List Archive
- Topic: Is it possible to omit soft variables?
- Replies: 8
- Views: 17027
Is it possible to omit soft variables?
At various times in this discussion forum, people have suggested that one should not include in models soft variables that lack quantitatively measured values. I suggest that such omission of soft variables is not possible. If one "omits" a variable, it has a very specific assumed value in...
- Fri Aug 10, 2001 9:51 am
- Forum: SD Mailing List Archive
- Topic: Inventory Management System
- Replies: 1
- Views: 3843
Inventory Management System
You do not indicate how much study and experience that you have had with system dynamics. However, perhaps the material below will be useful. If you have not already studied it carefully, I suggest that you start with my "Industrial Dynamics" book that is available as given below; especial...
- Wed Aug 01, 2001 9:43 pm
- Forum: SD Mailing List Archive
- Topic: Thoughts for future conferences
- Replies: 5
- Views: 5798
Thoughts for future conferences
I agree with George Richardson when when he wrote: >I am convinced we are strongest when we realize we are four or five >constituencies which need each other: academics, consultants, >practitioners in public and private sector employ, and k-12 >teachers. Each group grows in numbers and sophisticatio...
- Wed Jul 18, 2001 9:08 pm
- Forum: SD Mailing List Archive
- Topic: Human Behavior in System Dynamics Models
- Replies: 9
- Views: 11208
Human Behavior in System Dynamics Models
Are there any management or social system models that do not at least implicitly include human behavior? "Jack Ring" <jring@amug.org> in SD3313 wrote >Although the Sterman model to which you refer is quite interesting it is >largely an economics model and includes no obvious variables for ...
- Wed Jul 18, 2001 10:11 am
- Forum: SD Mailing List Archive
- Topic: The order of a system
- Replies: 16
- Views: 10829
The order of a system
I believe that the "order" of a system is determined by the number of integrations (stocks or levels). An exponential decay or growth system with one stock is a first order system. The system with two stocks in a single loop, which generates a sine wave, is a second order system. The order...
- Tue May 29, 2001 2:45 pm
- Forum: SD Mailing List Archive
- Topic: ST & SD in real life
- Replies: 13
- Views: 13314
ST & SD in real life
In (SD3256), Eric Melse wrote: > >Is ST/SD a product that can be sold/implemented/used by business people >for make (operational?) decisions? > Such comments, which have run through much of this discussion about using system dynamics, focuses on decisions and seems to miss the real power of system d...
- Tue Mar 20, 2001 10:41 am
- Forum: SD Mailing List Archive
- Topic: Scaling Up & Modelling Human Decision-Making
- Replies: 1
- Views: 2946
Scaling Up & Modelling Human Decision-Making
The information below may be useful. =============================================== =============================================== Information on System Dynamics Jay W. Forrester Information revised March 18, 2001 System Dynamics Bibliography: To order the system dynamics bibliography of over 4100...
- Sun Feb 18, 2001 11:48 am
- Forum: SD Mailing List Archive
- Topic: The time scale regarding when to use system dynamics
- Replies: 8
- Views: 6561
The time scale regarding when to use system dynamics
Two recent communications on this email list have suggested that system dynamics is useful when the time scale of interest in months or years, but that discrete simulation should be used if the time scale of interest is in the range of hours or days. I believe that the time scale of interest is not ...
- Tue Jan 02, 2001 10:59 am
- Forum: SD Mailing List Archive
- Topic: Diabetics SD models
- Replies: 3
- Views: 12705
Diabetics SD models
Jack Fisher wrote: >I am interested in reviewing any models that refer to the regulation of >blood-sugar in normal and diabetic conditions. The following may be useful: Foster, R. O. (1970). The Dynamics of Blood-Sugar Regulation, M. I. T. M.Sc. Thesis, Electrical Engineering department, For a repro...
- Sun Dec 03, 2000 1:58 pm
- Forum: SD Mailing List Archive
- Topic: Sampling Theory -
- Replies: 0
- Views: 5530
Sampling Theory -
>Im currently modeling organisational behaviour and Im looking for the >connection of sampling time (delta T) and systems stability. >What is the impact of increasing delta T on the systems stability. Im >using Routh Stability test but Im afraid it would not work in my case >because my delta T can b...
- Wed Nov 29, 2000 3:53 pm
- Forum: SD Mailing List Archive
- Topic: Building your own models
- Replies: 18
- Views: 60923
Building your own models
>... (there is an article by JF somewhere to >the effect "Counter Intuitive Behavior of social systems" in this regard). I >agree. The Counterintuitive paper is available at: http://sysdyn.mit.edu oad-maps m-toc.html --------------------------------------------------------- Jay W. Forreste...
- Fri Sep 22, 2000 3:40 pm
- Forum: SD Mailing List Archive
- Topic: Limitations of SD!
- Replies: 2
- Views: 6972
Limitations of SD!
Perhaps the information below will be useful. =============================================== =============================================== Information on System Dynamics Jay W. Forrester August 25, 1999 System Dynamics Bibliography: To order the system dynamics bibliography of over 4100 entries, ...