Search found 21 matches

by "William Steinhurst"
Fri Feb 23, 2001 10:57 am
Forum: SD Mailing List Archive
Topic: Dana Meadows
Replies: 1
Views: 2931

Dana Meadows

Danas "Global Citizen" columns were carried by several Vermont newspapers and widely cited in policy discussions here. The an editorial about her can be seen at www.burlingtonfreepress.com/editorial/thursday/1000h.htm It appeared Thursday, along with a cheery photo of her that doesnt appea...
by "William Steinhurst"
Thu Apr 29, 1999 1:26 pm
Forum: SD Mailing List Archive
Topic: System Dynamics Societys Priorities
Replies: 21
Views: 12943

System Dynamics Societys Priorities

Jack raises a good, tough question--one that has the power to surface unquestioned assumptions. I hope serious debate will be triggered about new concepts and opportunities for action. Here at the beginning of that discussion, Id like to understand more clearly one point. Jack wrote: > Initially, ou...
by "William Steinhurst"
Sat Apr 03, 1999 10:13 am
Forum: SD Mailing List Archive
Topic: Does feedback need to involve levels
Replies: 5
Views: 5971

Does feedback need to involve levels

One needs to distinguish between the types of models being solved. In many dynamic systems (those involving a time variable), it is posited that the state of the system evolves in accordance with a system of differential equations. In such systems of equations, typically, the partial derivatives of ...
by "William Steinhurst"
Fri Apr 24, 1998 10:25 am
Forum: SD Mailing List Archive
Topic: The Tragedy of the Commons in business
Replies: 6
Views: 5967

The Tragedy of the Commons in business

Someone comes up with an idea that costs depart- > ment A $10 per unit, and saves the department B $50 per unit, re- > ducing the companys overall cost $40 per unit. As manager wont > agree, because that would raise As costs and make the manager > look bad. > ----------------------------------------...
by "William Steinhurst"
Mon Apr 13, 1998 9:29 am
Forum: SD Mailing List Archive
Topic: Professional Accreditation
Replies: 15
Views: 30004

Professional Accreditation

> Khalid Saeed wrote: > > > Perhaps we should discuss an accreditation process for the teaching > > programs rather than for the individuals. Could list readers tell us what accreditations SD programs have to begin with? Many are housed in business or engineering departments that presumably have the...
by "William Steinhurst"
Wed Apr 30, 1997 11:48 am
Forum: SD Mailing List Archive
Topic: Optimisation in System Dynamics
Replies: 21
Views: 9859

Optimisation in System Dynamics

<snip> > 3) In the formulation of model equations where there are issues > requiring allocation or another type of choice. In this settings Linear > Programs will often be used to run an optimization at each time a Im not quite sure whether this is a fourth application of optimisation or a restateme...
by "William Steinhurst"
Mon Apr 28, 1997 9:11 am
Forum: SD Mailing List Archive
Topic: modelling survival - how?
Replies: 2
Views: 2157

modelling survival - how?

Its not clear from your message what your modeling problem is. Empirical data from each of the situations you describe can be analyzed using standard survival statistics methods to either estimate the parameters of the survival distribution (or a non-parametric survival distribution estimate) or to ...
by "William Steinhurst"
Sun Apr 20, 1997 9:49 am
Forum: SD Mailing List Archive
Topic: perennial crop modelling
Replies: 7
Views: 4633

perennial crop modelling

Does the term "perennial" in your question simply relate to the fact that being a tree, cocoa is biologically a perennial, or do you have in mind a model for sustainable yield, or is there something else intended? Bill Steinhurst From: "William Steinhurst" <wsteinhu@psd.state.vt....
by "William Steinhurst"
Thu Apr 10, 1997 2:29 pm
Forum: SD Mailing List Archive
Topic: Foreign Policy Models
Replies: 1
Views: 1649

Foreign Policy Models

Robert Glitz wrote: > I think it would be kind of neat if they could build a management flight > simulator of potential conflict and use it to convince lawmakers of > systemic approaches to policy. This is exactly the correct approach. Modeling and model use seem to work best when there is a specifi...
by "William Steinhurst"
Sun Apr 06, 1997 11:24 am
Forum: SD Mailing List Archive
Topic: Optimisation in System Dynamics
Replies: 21
Views: 9859

Optimisation in System Dynamics

Lets remember that there are situations where the global behavior of a system is qualitatively altered by small shifts in the value of a parameter. Aside from transitions to chaos, there are qualitative differences that can be of great significance in some settings between, for instance, a damped sy...
by "William Steinhurst"
Thu Apr 03, 1997 6:58 pm
Forum: SD Mailing List Archive
Topic: Recent queries on graduate projects
Replies: 10
Views: 7030

Recent queries on graduate projects

<snip>
It is not like word processing -- one can not
> just buy the software and read a few pages of the manual and begin to
> compose.

Absolutely. Owning a copy of AutoCad does not make one an architect.

Bill Steinhurst
wsteinhu@psd.state.vt.us
by "William Steinhurst"
Thu Apr 03, 1997 1:55 pm
Forum: SD Mailing List Archive
Topic: Differential equations
Replies: 25
Views: 39532

Differential equations

Jay Forrester wrote:

<snip>
> Differential equations are difficult, confusing, weak, and
> unrealistic.

Difficult and confusing, certainly. Unrealistic, often. But weak?
Could you clarify?

Bill Steinhurst
wsteinhu@psd.state.vt.us
by "William Steinhurst"
Tue Apr 01, 1997 4:07 pm
Forum: SD Mailing List Archive
Topic: leverage points
Replies: 29
Views: 64771

leverage points

The list looks like a very good way to focus thinking, and the purpose of opening the discussion with an audience works, but I dont feel that the ranking can be so fixed. For instance, the time scale of intervention will make a difference as to the effectiveness of the "levers." This shoul...
by "William Steinhurst"
Mon Apr 29, 1996 9:38 am
Forum: SD Mailing List Archive
Topic: Feedback -forward?
Replies: 16
Views: 9442

Feedback -forward?

George Richardson <gr383@cnsvax.albany.edu> wrote: > We need a term for the circularities that are so crucial to an > endogenous view of a systems dynamics. Forrester wrote "<snip> A feedback control systems exists > whenever the environment causes a decision which in turn affects the > origina...
by "William Steinhurst"
Sun Apr 28, 1996 8:42 am
Forum: SD Mailing List Archive
Topic: compost-powered hot tub
Replies: 0
Views: 1495

compost-powered hot tub

Sounds like a natural for SD modeling. Anyone out there modeled this system already? How about developing some reference modes this summer in Cambridge? ------- Forwarded Message Follows ------- From: Hans William Kramer <lucidity@leland.Stanford.EDU> im theorizing as to the design of a compost-heat...
by "William Steinhurst"
Sat Apr 27, 1996 9:51 am
Forum: SD Mailing List Archive
Topic: Generic Structures: Hunting the Snark?
Replies: 6
Views: 4561

Generic Structures: Hunting the Snark?

Jim Hines wrote: > As David Lane suggested, molecules seem to refer to a class of generic structures slightly below his > Abstracted Micro Structures. Abstracted Microstructures are intended to generate a mode of behavior. > Behavior is not really the central point for molecules, structural represen...
by "William Steinhurst"
Fri Apr 26, 1996 12:41 pm
Forum: SD Mailing List Archive
Topic: Generic Structures: Hunting the Snark?
Replies: 6
Views: 4561

Generic Structures: Hunting the Snark?

D.C.Lane wrote: > However, in Boston, as part of my presentation, I will also be launching > an attempt to record and document the known generic structures I enjoyed your presentation at the Conference and hope the menagerie is rapidly collected, carefully labeled and skillfully presented to the pub...
by "William Steinhurst"
Fri Apr 19, 1996 9:40 am
Forum: SD Mailing List Archive
Topic: electric utility market deregulation
Replies: 3
Views: 2618

electric utility market deregulation

Check out "The Dynamics of U.S. Electric Utility Deregulation,"
George Backus and Susan Baylis, US DOE, Office of Utility Technology.

Also, Systematic Solutions Inc., of Ohio has an electric industry
deregulation simulation game thats a lot of fun.

Bill Steinhurst
wsteinhu@psd.state.vt.us
by "William Steinhurst"
Thu Apr 18, 1996 1:09 pm
Forum: SD Mailing List Archive
Topic: Modelling Criminal Behaviours
Replies: 4
Views: 3075

Modelling Criminal Behaviours

> models > which deal with criminal behaviour in society or other such sociological > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The Multnomah County (Oregon) Criminal Justice Department did a lot of work in that area in the early to mid-70s. I think they mostly used stochastic queing mod...
by "William Steinhurst"
Wed Apr 17, 1996 8:19 am
Forum: SD Mailing List Archive
Topic: Definition of Feedback
Replies: 5
Views: 3649

Definition of Feedback

ON Wed, 15 May 1996 11:58:04 -0400 (EDT) George Richardson <gr383@cnsvax.albany.edu> said: > One can find definitions of feedback loops and the feedback perspective > in various system dynamics writings, notably the early writings of > Forrester. Youll also find much discussion of this in Feedback >...
by "William Steinhurst"
Fri Apr 12, 1996 1:56 pm
Forum: SD Mailing List Archive
Topic: oil and gas prices and reserves
Replies: 7
Views: 4512

oil and gas prices and reserves

Thomas Fiddaman wrote: > > To replace 1990 oil consumption with horses, youd need about 6 billion of them: > snip of course, as the Romans understood, the fuel efficiency of a horse and human laborer are not that different, so much of the work done by fossil fuels (e.g., moving people or packages sh...