Search found 20 matches

by Mohammad Jalali
Sun Mar 30, 2014 2:43 pm
Forum: Vensim
Topic: Tutorials (Video + text)
Replies: 16
Views: 17780

Re: Tutorials (Video + text)

Good news!
We have a couple of new videos. I'm going to upload them to the website this week. Will keep you updated!

Best,
M.J.
by Mohammad Jalali
Fri Nov 23, 2012 6:42 am
Forum: Vensim
Topic: Tutorials (Video + text)
Replies: 16
Views: 17780

Re: Tutorials (Video + text)

I just added a comment section in the tutorial page. We welcome your feedback on our tutorials, including ideas for future tutorials, suggested updates to the reporting guidelines, and other topics that can be included. Please use the comment section to share your thoughts at: http://www.sdl.ise.vt....
by Mohammad Jalali
Wed Jun 06, 2012 9:59 pm
Forum: Vensim
Topic: Tutorials (Video + text)
Replies: 16
Views: 17780

Re: Tutorials (Video + text)

Three tutorials including PDF and Vensim files are up in the website: 1) Subscripts, 2) Coflows, and 3) Table Functions.

Best,
M.J.
by Mohammad Jalali
Fri May 25, 2012 4:01 am
Forum: Vensim
Topic: Historical Data in Simulation Output
Replies: 9
Views: 2374

Re: Historical Data in Simulation Output

Simone wrote:
I am not %100 sure that the model works correctly... Maybe I should check it again. I will post the results :)

Thanks
Cool! Good luck! :wink:

M.J.
by Mohammad Jalali
Fri May 25, 2012 1:10 am
Forum: Vensim
Topic: Historical Data in Simulation Output
Replies: 9
Views: 2374

Re: Historical Data in Simulation Output

Can you post your model and dataset? Hi MJ, Thank you for your response, but unfortunately it is a very big and complicated model, and also because of some privacy issues I can not post it here. It there any chance that you can help me without taking a look to the model? I see. That's ok. Are you s...
by Mohammad Jalali
Thu May 24, 2012 11:48 pm
Forum: Vensim
Topic: Historical Data in Simulation Output
Replies: 9
Views: 2374

Re: Historical Data in Simulation Output

Simone wrote: Should I calibrate the model, although I am not optimizing?
I really appreciate if you can help.
Hi Simone,

Can you post your model and dataset?

Best,
MJ
by Mohammad Jalali
Mon May 21, 2012 5:01 pm
Forum: Vensim
Topic: Tutorials (Video + text)
Replies: 16
Views: 17780

Re: Tutorials (Video + text)

Two new videos have been uploaded. (1) Linear Regression in Vensim and (2) Subscripts in Vensim.

Regards,
M.J.
by Mohammad Jalali
Thu Apr 12, 2012 3:44 am
Forum: System Dynamics Discussion
Topic: Guidelines on how to publish your simulation-based research!
Replies: 0
Views: 3114

Guidelines on how to publish your simulation-based research!

Please check this new paper (by Hazhir Rahmandad of Virginia Tech and John Sterman of MIT) which includes the following set of guidelines for simulation-based research with a focus on common scenarios in system dynamics research: - Guidelines for reporting models, reporting simulation experiments, a...
by Mohammad Jalali
Thu Apr 05, 2012 5:30 am
Forum: Vensim
Topic: Tutorials (Video + text)
Replies: 16
Views: 17780

Re: Tutorials (Video + text)

A new video has been uploaded: Using command script in Vensim.

Best,
M.J.
by Mohammad Jalali
Mon Apr 02, 2012 3:03 pm
Forum: Vensim
Topic: How to input a time series function
Replies: 3
Views: 1294

Re: How to input a time series function

If you go to Model > Check Model, you can see what the problem is that your model cannot be run. The "Food price equal" is used as, but not defined as, a lookup. It is defined as an Auxiliary. And in autoregressive or AR(1), a(t) is random with zero mean and variance of sigma squared, so you can sim...
by Mohammad Jalali
Sun Apr 01, 2012 11:51 pm
Forum: Vensim
Topic: How to input a time series function
Replies: 3
Views: 1294

Re: How to input a time series function

Hi Mehdi,

Please check the attached file. It calculates P(t)=a+b*P(t-1), where t is Time. Is that what you were looking for?
Please feel free to ask me if you need some explanation.

Best,
M.J.
by Mohammad Jalali
Sun Apr 01, 2012 7:10 pm
Forum: Vensim
Topic: Tutorials (Video + text)
Replies: 16
Views: 17780

Tutorials (Video + text)

I have created a page to share tutorials developed by students of Dr. Hazhir Rahmandad in Advanced Dynamic Modeling class and System Dynamics Lab. Two videos have been uploaded and more videos are coming soon! Please check them out here: http://www.sdl.ise.vt.edu/tutorials.html Should you have any c...
by Mohammad Jalali
Sat Mar 24, 2012 7:49 pm
Forum: System Dynamics Discussion
Topic: System dynamics of terrorism
Replies: 2
Views: 4824

Re: System dynamics of terrorism

Hi Alessandro, I think the following studies can help you: - A System Dynamics (SD) Approach to Modeling and Understanding Terrorist Networks, http://web.mit.edu/smadnick/www/Projects/PAINT/PAINT%20Proposal.pdf - Understanding Terrorist Organizationswith a Dynamic Model, http://www.cam.cornell.edu/~...
by Mohammad Jalali
Wed Mar 21, 2012 1:42 am
Forum: Vensim
Topic: ODBC Problems (Connecting Vensim to MS Access)
Replies: 8
Views: 4220

Connecting Vensim to MS Access with ODBC (Tutorial video)

I have recorded a video about connecting Vensim to MS Access with ODBC. Examples presented in this video are: 1) How to read variables, constants, lookups, and subscripts from a database, and 2) How to write simulation output into a database. I have tried to use very simple examples and explained al...
by Mohammad Jalali
Fri Mar 09, 2012 12:42 am
Forum: Vensim
Topic: ODBC Problems (Connecting Vensim to MS Access)
Replies: 8
Views: 4220

Re: ODBC Problems (Connecting Vensim to MS Access)

Thank you! My DSS is version 5.11A for Windows. Isn't it the last one?

M.J.
by Mohammad Jalali
Thu Mar 08, 2012 4:25 am
Forum: System Dynamics Discussion
Topic: causal loop
Replies: 2
Views: 2324

Re: causal loop

I have attached a CLD here related to your topic. However it has the same problem, but it might be helpful to give you some ideas on variables and relationships. (I don't confirm all relationships in this CLD.)

Best,
M.J.
by Mohammad Jalali
Thu Mar 08, 2012 3:51 am
Forum: System Dynamics Discussion
Topic: causal loop
Replies: 2
Views: 2324

Re: causal loop

I didn't go through all details, but what is obvious to me is a lack of a clear purpose in this CLd. What is the main purpose of this CDL? You should be careful about modeling the entire system, because if you go into that level there are many important variables which are currently missing in your ...
by Mohammad Jalali
Wed Mar 07, 2012 10:57 pm
Forum: Vensim
Topic: ODBC Problems (Connecting Vensim to MS Access)
Replies: 8
Views: 4220

Re: ODBC Problems (Connecting Vensim to MS Access)

I just found out what was missing in the model! I only set the input file ( vdi ) as "Pre Processing..." in Simulation Control ("Simulation control" > "Pre/Post" tab), while to get a constant value into the Vensim model, I should have gone to "Simulation Control" > "Changes" tab and loaded the vdi f...
by Mohammad Jalali
Wed Mar 07, 2012 10:52 pm
Forum: Vensim
Topic: ODBC Problems (Connecting Vensim to MS Access)
Replies: 8
Views: 4220

ODBC Problems (Connecting Vensim to MS Access)

I am using a vdi file to read data from an Access database. I can get variables but constants. My ":CONSTANTS" keyword includes the followings: :CONSTANTS :VARNAME ConstantName :VALUE ConsVal :SELECT Constant_Val ! "Constant_Val" is a table in my database where I define value for each constant. The ...