Search found 112 matches

by nikvyas
Tue Oct 22, 2019 1:18 pm
Forum: Vensim
Topic: Subscript Subrange
Replies: 5
Views: 158

Re: Subscript Subrange

That's great, many thanks!
by nikvyas
Tue Oct 22, 2019 12:30 pm
Forum: Vensim
Topic: Subscript Subrange
Replies: 5
Views: 158

Re: Subscript Subrange

Many thanks Tom. I've tried your suggestion, but I think I am doing something fundamentally wrong. I have created 4 subranges as follows: variant1 : (v1-v25) variant2 : (v26-v50) variant3 : (v51-v75) variant4: (v76-v100) Then: aircraft: (variant1, variant2, variant3, variant4) I have then created 4 ...
by nikvyas
Thu Oct 17, 2019 8:50 am
Forum: Vensim
Topic: Subscript Subrange
Replies: 5
Views: 158

Subscript Subrange

Good morning/evening/afternoon. It has been a while since I last posted here. But myself (and the Company I work for) are slowly but surely getting back into the use of Vensim. I have a model that generates an aircraft flying programme. There are 100 aircraft (so I have a subscript called [aircraft]...
by nikvyas
Thu Jul 18, 2013 12:42 pm
Forum: Vensim
Topic: Waiting times in a doctor's surgery
Replies: 21
Views: 4597

Re: Waiting times in a doctor's surgery

I've had a look at the model you attached Tom. The model I would want to use is the one with Poisson arrivals. However, "patients waiting 1" is behaving in a peculiar way (i.e. it never decreases). Do I need to change: QUEUE FIFO(admitting 0+arriving 0, admitting 0, flat, 0, 0 ) to QUEUE FIFO(arrivi...
by nikvyas
Fri Jul 12, 2013 9:42 pm
Forum: Vensim
Topic: Waiting times in a doctor's surgery
Replies: 21
Views: 4597

Re: Waiting times in a doctor's surgery

Yes WITNESS is a discrete simulator developed by Lanner. It is getting a lot of traction within the Company for which I work largely because their salesman are very convincing and very persistent. That is something Ventana can't be accused of (rightly or wrongly). I suspect that, in general, I don't...
by nikvyas
Fri Jul 12, 2013 7:31 pm
Forum: Vensim
Topic: Waiting times in a doctor's surgery
Replies: 21
Views: 4597

Re: Waiting times in a doctor's surgery

Just a reminder about the model modification, when you get a chance Tom.

I have spent the last four days on a WITNESS course and although it seems to me that WITNESS is more suited to the simulation of queues etc, I'm a little reluctant to use it because I much prefer the "feel" of Vensim.
by nikvyas
Tue Jul 09, 2013 5:47 pm
Forum: Vensim
Topic: Waiting times in a doctor's surgery
Replies: 21
Views: 4597

Re: Waiting times in a doctor's surgery

Many thanks Tom.
by nikvyas
Mon Jul 08, 2013 8:49 pm
Forum: Vensim
Topic: Waiting times in a doctor's surgery
Replies: 21
Views: 4597

Re: Waiting times in a doctor's surgery

Thanks Guido, Tom. My problem is this. You've already specified that max patients seen = 0.4 because the number of doctors is 4 and the length of an appointment 10 minutes. So what this implies to me is that, every time step (a maximum of ) 0.4 of "patients waiting" will be cleared, which makes perf...
by nikvyas
Sat Jul 06, 2013 9:17 pm
Forum: Vensim
Topic: Waiting times in a doctor's surgery
Replies: 21
Views: 4597

Re: Waiting times in a doctor's surgery

No, you'll find you're wrong.

Don't just look at the units, look at the outputs.
by nikvyas
Sat Jul 06, 2013 9:06 am
Forum: Vensim
Topic: Waiting times in a doctor's surgery
Replies: 21
Views: 4597

Re: Waiting times in a doctor's surgery

Many thanks Tom.

Note that there is a slight error in your model.

patients seen = MIN(max patients seen,patients waiting)

and not

patients seen = MIN(max patients seen,patients waiting/average length of appointment)

Many thanks

Nik
by nikvyas
Mon Jul 01, 2013 2:52 pm
Forum: Vensim
Topic: Waiting times in a doctor's surgery
Replies: 21
Views: 4597

Re: Waiting times in a doctor's surgery

I guess the easiest thing to do (and I know I'm talking to myself a bit here) is to set the number of doctors to: number of doctors / length of appointment = 0.4 This way only 0.4 of a patient can be seen in a minute. Not particularly elegant .......... and will it give a correct answer, particularl...
by nikvyas
Mon Jul 01, 2013 2:37 pm
Forum: Vensim
Topic: Waiting times in a doctor's surgery
Replies: 21
Views: 4597

Re: Waiting times in a doctor's surgery

The attached doesn't work because at the moment it does the following....... Once the average length of appointment is reached, patients are "seen" every minute depending on the number of doctors. i.e., in the attached, the number of doctors is 4. So, after the "average length of appointments" is re...
by nikvyas
Sun Jun 30, 2013 12:22 pm
Forum: Vensim
Topic: Waiting times in a doctor's surgery
Replies: 21
Views: 4597

Waiting times in a doctor's surgery

Good day everyone. I've built models in Vensim for a number of years now, but have never used Queues. The problem I have at the moment however, probably lends itself to Queues. I want to model the maximum waiting time for each patient who comes in and waits to be seen at a doctor's surgery. The pati...
by nikvyas
Thu Jan 27, 2011 1:01 pm
Forum: Vensim
Topic: Maximum of a variable
Replies: 2
Views: 892

Re: Maximum of a variable

Perfect! Thanks very much.

Nik
by nikvyas
Wed Jan 26, 2011 4:15 pm
Forum: Vensim
Topic: Maximum of a variable
Replies: 2
Views: 892

Maximum of a variable

Hello all. I realise that there is a GET DATA MAX that produces the maximum of a data range. However, I want to get a continuous account of the maximum of a variable. For instance, if a variable were to output the following sequence: 12,7,13,1,0,23,2,12,2,34 I would want another variable to give: 12...
by nikvyas
Mon Jan 24, 2011 2:54 pm
Forum: Vensim
Topic: Assigning data to subscript elements
Replies: 14
Views: 3323

Re: Assigning data to subscript elements

Thanks very much tom.
by nikvyas
Mon Jan 24, 2011 9:59 am
Forum: Vensim
Topic: Assigning data to subscript elements
Replies: 14
Views: 3323

Re: Assigning data to subscript elements

The allocation is done highest to lowest subscript. Is it possible to do it lowest to highest instead, so that subscript 1 gets allocated first as opposed to subscript 50 (assuming 50 subscripts)?

Thanks
by nikvyas
Thu Jan 20, 2011 4:29 pm
Forum: Vensim
Topic: Assigning data to subscript elements
Replies: 14
Views: 3323

Re: Assigning data to subscript elements

Apologies Lee and Tom.

Yes - you're right............it does work :lol:

I made the mistake of looking at the graphs rather than looking at the tables.

Thanks again.

Nik
by nikvyas
Thu Jan 20, 2011 3:21 pm
Forum: Vensim
Topic: Assigning data to subscript elements
Replies: 14
Views: 3323

Re: Assigning data to subscript elements

Thanks Tom - unfortunately I need to track individual aircraft (and their progress through maintenance). Your model would be perfect - if I could get my version to work :? The Flying Programme does have pulses - but they are a long time in the future! For instance, there are pulses at 12381, 12386, ...
by nikvyas
Thu Jan 20, 2011 1:45 pm
Forum: Vensim
Topic: Assigning data to subscript elements
Replies: 14
Views: 3323

Re: Assigning data to subscript elements

No, still doesn't work for some reason. Irrespective of whether or not the dimensions are set (and I admit that they should be, but the model is by no means in its finished state yet), I don't understand why the "Mission Starts" function doesn't work. Any help more than gratefully recieved.
by nikvyas
Thu Jan 20, 2011 1:24 pm
Forum: Vensim
Topic: Assigning data to subscript elements
Replies: 14
Views: 3323

Re: Assigning data to subscript elements

The attached model is a part view of a much larger model. The p1 is a legacy subcript and I should have removed it. I'll remove and see if it clears the errors.
by nikvyas
Thu Jan 20, 2011 10:18 am
Forum: Vensim
Topic: Assigning data to subscript elements
Replies: 14
Views: 3323

Re: Assigning data to subscript elements

Thaks very much guys. Much appreciated. However - I'm obviously doing something silly, because my model doesn't run. You couldn't have a look could you please? "Mission Starts" is probably the culprit.

Nik
by nikvyas
Wed Jan 19, 2011 4:30 pm
Forum: Vensim
Topic: Assigning data to subscript elements
Replies: 14
Views: 3323

Assigning data to subscript elements

Hello all. I'm struggling to come up with a neat algorithm that does the following: I have a subscript with 20 elements (call them 20 planes). I have a flying programme made up of a series of pulses. The heights of the pulses are multiples of 1. 1 is the length of each flight, so if there is a pulse...
by nikvyas
Thu Dec 16, 2010 11:35 am
Forum: Vensim
Topic: Vensim versus Simul8
Replies: 3
Views: 1778

Re: Vensim versus Simul8

Thanks Lee - I was hoping you'd read my message, because you are well aware of the type of product/service I am talking about. I ended up going on a two day Simul8 course yesterday and Tuesday and I agree with everything you posted. Vensim is more suited to a higher level type of analysis when you a...
by nikvyas
Mon Dec 13, 2010 3:02 pm
Forum: Vensim
Topic: Vensim versus Simul8
Replies: 3
Views: 1778

Vensim versus Simul8

Hello all.

My company is currently in the process of deciding upon a standard through-life modelling tool.

The choice has basically boiled down to two. Vensim or Simul8.

Could the learned members please give an idea of what advantages/disadvantages Simul8 has over Vensim?

Thanks very much

Nik