Ventana software support forum

I appreciate all the suggestions and comments and suggested sources of modeling ideas. regarding: > "Try linking the inflow > directly to the outflow > (bypassing the stock) ... It seems that if we link inflow to outflow then the stock becomes meaningless. The actual value of the stock can be a...

Fadil: I am not sure about groundwter use, but reasons leading to various land use patterns are being investigated by a group linked to CIFOR (in Bogor Indonesia). Look for links on CIFORs web page related to "FLORES". Also Meine van Noordwijk at ICRAFs branch office in Bogor is doing mode...

Just a note for those who might have missed it... The various philosophies of SD model validiity is nicely discussed by Barlas in his 1996 paper "Formal aspects of model validity and validation in system dynamics" (SDR 12:3). I found this to be a very interesting paper. -- Richard G. Dudle...

X-UIDL: 10257-938505322 Status: O X-Status: I have a simple model with a simple problem. One of our shrimp species spawns in the ocean, very young shrimp use a lagoon as a nursery area for three months and then emigrates to the ocean and grow to adults. This model has two stocks: shrimp in lagoon an...

I am about to become involved with an effort to use SD modeling to examine the problem of illegal logging in Indonesia (and, in the future, perhaps elsewhere). I would be interested in corresponding with colleagues working on this or similar issues including the modeling of factors affecting legal f...

Peter: A very long time ago (1997) you responded to a posting of mine related to corruption modeling using system dynamics. I finally presented a preliminary paper about this at the SD meeting in Norway this past summer. Would you be interested in looking at the models and giving some "real wor...

CIFOR (Center for International Forestry Research) recently held a model building workshop to develop the first version of FLORES which looks at land use issues in a forested / agroforest environment. This model is very detailed and I believe, still under construction, but it does include components...

You might wish to check the CIFOR Web Page (Center for International Forestry Research) at http://www.cgiar.org/cifor/index.html. I believe that they are doing some work along these lines under a programme called "flores". -- Richard G. Dudley rdudley@indo.net.id http://home.indo.net.id/~r...

As a new-comer to the field I sense that it is sometimes promoted as more than it is. I dont think I would view it as a new field of pure science, or a method of philosophy, but rather as a method of analysis. As statistics is a method for analyzing data and for making inferences about those data, s...

I often read that the best models are built by groups of people working together, but most modelers I know like to work alone. I was wondering what techniques people have successfully used to get the two types of activities (group discussion and at the keyboard modeling) meshed in a productive way? ...

The book "Dynamic Modeling" by Hannon and Ruth has some chemistry examples of the
type you are asking about.

--
Richard G. Dudley

rdudley@indo.net.id
http://home.indo.net.id/~rdudley

I am interested in contacting people who use system dynamics techniques to address fisheries management issues. In particular, I am interested in finding if there is enough interest to warrant putting together a session on "systems dynamics in fisheries" at this years meeting of the Americ...

We are hoping to go ahead with a session on Fisheries and Systems Dynamics at the American Fishery Society meeting in North Carolina which takes place at the end of August. I have already received some proposals for presentations, but there is still room for additional speakers. If you would like to...

Deirdre:

You might want to take a look at madonna which may not create a fortran
file but may produce what you need. Go to:

http://www.kagi.com/authors/madonna/default.html


--
Richard G. Dudley

rdudley@indo.net.id
http://home.indo.net.id/~rdudley

To All: I know this is a bit off the topic, but it seems that "knowledge mapping" and "semantic networks" could be a good precursor to developing a system dynamics model so perhaps someone here is familiar with the subject. I was wondering if anyone could give me some pointers re...

Don: To date I have mostly played, rather than worked, with models (Stella 4) but I usually put in a random plus or minus (or random value drawn from a normal distribution) around key inputs. Sensitivity analysis will tell you how a system will respond to fixed changes in a input variables, but rand...

Although I am a biologist, I have started working on a system dynamics model of corruption. My location makes this an interesting and important topic. I found that there is an abundance of literature on corruption, mostly economic discussions, (but I have only very limited access to libraries). I wa...

Alex Rodrigues wrote (in part): I particularly liked the following statement: "Things today are the things of yesterday plus any changes. The changes are the result of the things of yesterday. Now extend this to tomorrow." From: bonnell@kodak.com I also liked that comment. It reminded me o...

STELLA (at least version 4) comes with at least three economic example models: 2 installed under the directory "appmdls" (asmith1 and asmith2) and 1 installed under the directory "samples" (economics.stm). They are all quite nice and would seem appropriate for what you need. Also...