Search found 107 matches

by karankhosla
Mon Apr 28, 2014 6:02 am
Forum: Vensim
Topic: Can Lookups deal with variables in the output
Replies: 3
Views: 1362

Can Lookups deal with variables in the output

Is it possible to define a lookup table so that it chooses the output as a variable in the model rather than a number; so for example:

The lookup data set would be some thing like [(1, VarA), (2,VarB), (3, VarC)]
by karankhosla
Fri Apr 18, 2014 10:54 am
Forum: Vensim
Topic: Running a model in hours, keeping track of days....
Replies: 4
Views: 1740

Re: Running a model in hours, keeping track of days....

Thanks Admin (Tony, Tom?! I'm going to try it out and might have to get back to you! JJ, good to hear from you! I have built a high level model which works very well - sometimes, no matter how silly it may seem, it is also important for a good modeller to do what the client wants to make sure his/he...
by karankhosla
Fri Apr 18, 2014 6:39 am
Forum: Vensim
Topic: Running a model in hours, keeping track of days....
Replies: 4
Views: 1740

Running a model in hours, keeping track of days....

Hi Folks! It's been a while! I have an interesting problem to deal with. I'm running a model in hours for a year - this is a client specification. I need to create an electricity load profile for a campus, for which I have data for different buildings over a twenty-four hour period over 3 seasons (s...
by karankhosla
Thu Jul 19, 2012 5:10 am
Forum: Vensim
Topic: Vensim to Excel
Replies: 3
Views: 2039

Re: Vensim to Excel

Thanks Tom! I presume I could try an ODBC connection from Vensim to Excel, on the lines of the Mohammed Jalili's tutorial too?
by karankhosla
Wed Jul 18, 2012 11:32 am
Forum: Vensim
Topic: Vensim to Excel
Replies: 3
Views: 2039

Vensim to Excel

Hi everyone! I hope everything is going well with the Ventana community. I should have asked this a long time ago: St**la has a feature which creates a "persistent" link to an excel file and allows you to drive the excel file from the SD model - no programming required and very useful when making bu...
by karankhosla
Wed Apr 18, 2012 5:52 am
Forum: Vensim
Topic: VensimPLE for Mac - open two models at the same time
Replies: 2
Views: 1449

Re: VensimPLE for Mac - open two models at the same time

You can open multiple instances of an app in OSx via the Terminal window: Go to Applications->Utilities-Terminal: type in the following command "open -n "path/to/file.extension" You can also create a macro for Vensim using Automator: http://lifehacker.com/5668648/automate-just-about-anything-on-your...
by karankhosla
Mon Apr 02, 2012 1:36 pm
Forum: Vensim
Topic: Tutorials (Video + text)
Replies: 16
Views: 17779

Re: Tutorials (Video + text)

What a wonderful tutorial!
by karankhosla
Sun Mar 25, 2012 7:16 am
Forum: Vensim
Topic: how to perform a convolution in vensim
Replies: 17
Views: 6478

Re: how to perform a convolution in vensim

Hi Rolf, this is very interesting; I'm curious, what happens to the results of the outflow with regard to your expectations, if you put the Delay Time value = the mean delay of your pdf?
by karankhosla
Sat Mar 24, 2012 8:58 am
Forum: Vensim
Topic: Vensim Beginner cant solve problems
Replies: 1
Views: 835

Re: Vensim Beginner cant solve problems

Hi! a Units Check (Ctrl U) shows that many formulations don't make sense; I'm not sure what these assumptions are based on, so I can't say that they are wrong; however, for example: Your variable "Birth rate A" should have units "1/Month", so that when it multiplies with the Population of "Plecopter...
by karankhosla
Wed Mar 14, 2012 5:05 am
Forum: Vensim
Topic: Vensim and Digest
Replies: 6
Views: 2095

Re: Vensim and Digest

Thank you both very much!
by karankhosla
Tue Mar 13, 2012 4:35 pm
Forum: Vensim
Topic: Vensim and Digest
Replies: 6
Views: 2095

Re: Vensim and Digest

Hi! Yes, It's a fantastic little tool to analyze SD model behavior and identify influential system structures (loop dominance etc) The application is available on George Richardson's website, so I presume it's open source (scroll to the bottom): http://www.albany.edu/cpr/sdgroup/pad824/schedule.html...
by karankhosla
Tue Mar 13, 2012 12:42 pm
Forum: Vensim
Topic: Vensim and Digest
Replies: 6
Views: 2095

Vensim and Digest

Greetings,

I can't seem to get my Vensim based (Forrester's) market growth model to work in Digest. Any suggestions?

Karan
by karankhosla
Wed Oct 12, 2011 7:07 pm
Forum: Vensim
Topic: selecting sensible variables
Replies: 4
Views: 1418

Re: selecting sensible variables

Hi adjie,

Tom's right and if I have read and understood your post correctly - when you have a model with non-linearities, you can't pre-determine, or categorize which variables based on their sensitivity to inputs.

My Best,

Karan
by karankhosla
Fri Oct 07, 2011 5:32 am
Forum: Welcome and General Information
Topic: RSS Forum Feed
Replies: 8
Views: 7991

Re: RSS Forum Feed

This is sweet. Thank you so much!

Would it be possible to pass on content as well as post data/metadata?

Karan
by karankhosla
Wed Oct 05, 2011 6:03 am
Forum: Welcome and General Information
Topic: RSS Forum Feed
Replies: 8
Views: 7991

RSS Forum Feed

Hi Tony, you mentioned the possibility of activating an RSS feed for the forum a while back - is this still a possibility? It would be very useful!

My Best,

Karan
by karankhosla
Wed Oct 05, 2011 6:01 am
Forum: Vensim
Topic: Optimization Algorithm
Replies: 3
Views: 1155

Re: Optimization Algorithm

Hi Milad, if you do a search for optimization in this forum, you will find plenty of useful information on both the algorithm as well as on how and where to use it effectively.

My Best,

Karan
by karankhosla
Sat Feb 26, 2011 8:16 am
Forum: Vensim
Topic: What improvements would you like to see in Vensim?
Replies: 109
Views: 59034

Re: What improvements would you like to see in Vensim?

Hi JJ, Thanks, but this is still one step removed; would like ghost variables (except stocks) to accept inputs without additional steps.
by karankhosla
Fri Feb 25, 2011 11:12 am
Forum: Vensim
Topic: What improvements would you like to see in Vensim?
Replies: 109
Views: 59034

Re: What improvements would you like to see in Vensim?

It would be nice if Ghost Variables could accept inputs as well, this is particularly useful when you are working across multiple views!
by karankhosla
Fri Feb 11, 2011 9:23 am
Forum: Vensim
Topic: Getting started, and one basic question
Replies: 1
Views: 829

Re: Getting started, and one basic question

Hi Ashish, Principles of Systems by Jay W. Forrester, Business Dynamics by John Sterman, A Practical Approach to SD Modeling by Goeff Coyle are great places to start. As for having a variable increase or decrease 10% year by year, it is best to treat it is a stock with an initial value and let it gr...
by karankhosla
Fri Feb 04, 2011 9:16 am
Forum: Vensim
Topic: Conversion of Stella Models to Vensim and Free vensim models
Replies: 15
Views: 5495

Re: Conversion of Stella Models to Vensim and Free vensim mo

I agree with Tom, building a Stella model from scratch in Vensim is a great way to learn about the software and the system you're studying in general. I have seen a lot of Stella models recently, which have been built without any attention to units or basic modeling fundamentals. Though I enjoy usin...
by karankhosla
Fri Jan 14, 2011 5:41 am
Forum: Vensim
Topic: What improvements would you like to see in Vensim?
Replies: 109
Views: 59034

Re: What improvements would you like to see in Vensim?

Greetings!

I would also like to see a Stock "non-negative" feature, specifically for Vensim PLE; often, in my short introductory workshops and courses, students at this early stage of learning get lost with MIN, MAX, non-linear formulations for flow control.

My Best,

Karan
by karankhosla
Fri Jan 07, 2011 1:00 pm
Forum: Vensim
Topic: What improvements would you like to see in Vensim?
Replies: 109
Views: 59034

Re: What improvements would you like to see in Vensim?

When viewing a graph, it would be helpful to be able to tell the exact value of the variable of concern as one scrolls along the independent axis. This would save an intermediary step of having to open up a table.
by karankhosla
Wed Dec 22, 2010 4:56 am
Forum: Vensim
Topic: Help with Vensim Equations
Replies: 10
Views: 3469

Re: Help with Vensim Equations

Hans, if you haven't already, you may also want to take a look at Business Dynamics Chapters 17 and 18 which deal with instability and oscillations using the example of a manufacturing supply chain.
by karankhosla
Mon Dec 20, 2010 4:41 am
Forum: Vensim
Topic: Help with Vensim Equations
Replies: 10
Views: 3469

Re: Help with Vensim Equations

Hi Han, could you please post your vensim model file?
by karankhosla
Thu Nov 25, 2010 6:21 am
Forum: Vensim
Topic: Need help on stock and flow
Replies: 28
Views: 5438

Hi amatriciana85, Please attach your file, I can take a look.

Karan