Ventana software support forum

Hi JJ, I had a look on the first model and I got your point of keeping things simple at first by choosing a static approach. Unfortunately, I would like to calculate costs of a production facility depencent of the utilization rate, so I have to make it at least in part dynamic. Your optimization is ...

Hi JBH, the basic test for deciding if a variable is a stock, as far as I know, is the so called snapshot test (see e.g. Sterman's "Business Dynamics"). Just image time is freezed then what will you see? These are stocks. All the parameters changing stocks are flows. The rest is auxiliary ...

Hello JJ Your point to try simple things first is fine, but if you have a static model, what exactly can you learn from it? The causal loops can be made clearer, but I thought that it's just the dynamics in the system we are interested in. And how do you aggregate time? Do you consider only snapshot...

Hi JJ, you are totally right. I'm in my first stage of SD modelling and I find it really hard to consider all the information I have and the techniques I read about. Actually I am trying to minimize my model to avoid "overhead" and confusion. But stocks and flows thinking is rather new for...

Hi JJ, well, good SD-style seems to be using feedback loops. The FIFO queue actually includes no real loop. Concerning the flat lookup: You are right, I included the wrong one. Originally it was really flat. Calculating the maximum capacity as product of maximum outflow and min processing time seems...

Hello JJ, Sorry for my late answer. I visited my family on the weekend and have not started to work again until today. I see I made some mistakes with naming. What I intended to model concerning the demand was the expected demand of a whole year and a probability density function for the distributio...

Good evening JJ! Take as much time as you like. I am very happy that there is someone at all I can discuss my problems with :-) My model is an almost exact copy of Mr. Sterman's one (by the way, it is page 554 in the book). Actually I have already tested a structure with backlog and work in progress...

Thank you for your quick answer! Please have a look at the attached file. I was wondering why the utilization never gets very high. But I had the idea that the reason is that I have not implemented a minimum process time. So it is possible that an order could fly through the stock (Backlog), isn't i...

Hello everybody! Having read "Business Dynamics" by Mr. Sterman I face a little problem with a structure he calls "capacitated delay" (page 557 or so in the book). Did I get that right that it behaves slightly lethargical? I tested several demand patterns, changed the lookup funk...