Currently I have a stock of Grade 1 learners. The stock is arrayed so that Gr1_learners[..] = {10,10} means that there are 10 high performing learners and 10 low performing learners in this stock. These learners progress to Grade 2 so that Gr2_learners[..] = {20,0} are the first graders having progressed after one year and some intervention improved all the learners to high performing.
My idea is to create learners as agents and place them in the stocks. Then Gr1_learners = 20 is a stock with 20 agents, half in state high_performing, and half in state low_performing. They progress, a state change is triggered so that Gr2_learners = 20 is then a stock with 20 agents, all in state high_performing and none in state low_performing.
Is this possible?
Yes, by not using stocks at all. You are probably familiar with SD modelling and now see the benefit of agent-based modelling.
Go all in and model your agents. Instead of stocks, you use agent populations and make your agents change states.
See the agent example models, especially the SIR one (there is an SD version and an ABM version, great to see how you can model any SD model with agents)
But you cannot have agents inside SD stocks, they are not actual stocks but just mathematical equations :)
Related
I'm working on a family practitioner model, my goal is to model the population of a city and all of the family practitioners in that given city by taking into account the distribution of the treatment time and the arrival schedule of patients etc... So far i've managed to create an agent that contains a bloc diagram to model the whole process
With a source and a delay bloc to generate patients according to a fixed schedule, a service bloc and two sinks.
Now i've put a population of this agent "process" in the main and i've simulated the model for 3 months.
Lets say i've started with a population of 10 process which represents the number of practitioners. My goal now to to collect some Mean statistics, like the Mean number of treated patients (treated patients goes to the sink "Served") of the 10 practitioners, the Mean waiting time of patients at the service bloc, the mean utilization ratio of the resource of the service bloc...
I want to also know if is it possible to limit the total number of Patients (or to at least count them), for exemple, instead of simulating the model for 3 months, i wanna limit the total number of patients that goes to the 10 process to 10k and i want to know how much time does it take to serve all of them. (is it possible with this architecture of the model or do i have to make major changes)
Thank you
I'm working on a family practitioner model, my goal is to model the population of a city and all of the family practitioners in that given city by taking into account the distribution of the treatment time and the arrival schedule of patients etc... I've started with a basic model with two practitioners and a small population.
Basic Model
Now if im going to model all of the 10k practitioners by duplicating the same blocks its gonna be like undoable, the other solution is to add more units in the resourcepool which does not model the real situation because basicly every family practitioner have his own queue and increasing the resourcepool is like modelling 'n' family practitioner in the same clinic with the same shared queue of patients. Is there any other solution? (first time using anylogic so im basicly a newbie)
thanks
You need to change your model architecture fundamentally. Practitioners become a custom agent type, you create a population of them and provide a flow chart in that agent type. Then, you can have 10k of them each with their own flow chart.
Strongly recommend you do all the tutorials in the help first to get a better understanding of the capabilities of AnyLogic. Having some blocks on Main is really just 0.1% of what the tool is capable of :)
I'm an undergrad student in the Philippines and were currently using Anylogic Software for our thesis. May I ask how to put a chart/time plot that consists the traffic flow (vehicle per hour) so that we can justify that our study area is congested? Thank you and have a good day.
The are a number of options you can use but the simplest option is to count the total number of cars in the system.
For this simply add a Road Network Descriptor and select the road network you want it to represent
Then you add a time plot, and set the value that needs to be plotted as roadNetworkDescriptor.size() and set the update time to hour
I am currently working on a simple simulation that consists of 4 manufacturing workstations with different processing times and I would like to measure the WIP inside the system. The model is PennyFab2 in case anybody knows it.
So far, I have measured throughput and cycle time and I am calculating WIP using Little's law, however the results don't match he expectations. The cycle time is measured by using the time measure start and time measure end agents and the throughput by simply counting how many pieces flow through the end of the simulation.
Any ideas on how to directly measure WIP without using Little's law?
Thank you!
For little's law you count the arrivals, not the exits... but maybe it doesn't make a difference...
Otherwise.. There are so many ways
you can count the number of agents inside your system using a RestrictedAreaStart block and use the entitiesInside() function
You can just have a variable that adds +1 if something enters and -1 if something exits
No matter what, you need to add the information into a dataset or a statistics object and you get the mean of agents in your system
Little's Law defines the relationship between:
Work in Process =(WIP)
Throughput (or Flow rate)
Lead Time (or Flow Time)
This means that if you have 2 of the three you can calculate the third.
Since you have a simulation model you can record all three items explicitly and this would be my advice.
Little's Law should then be used to validate if you are recording the 3 values correctly.
You can record them as follows.
WIP = Record the average number of items in your system
Simplest way would be to count the number of items that entered the system and subtract the number of items that left the system. You simply do this calculation every time unit that makes sense for the resolution of your model (hourly, daily, weekly etc) and save the values to a DataSet or Statistics Object
Lead Time = The time a unit takes from entering the system to leaving the system
If you are using the Process Modelling Library (PML) simply use the timeMeasureStart and timeMeasureEnd Blocks, see the example model in the help file.
Throughput = the number of units out of the system per time unit
If you run the model and your average WIP is 10 units and on average a unit takes 5 days to exit the system, your throughput will be 10 units/5 days = 2 units/day
You can validate this by taking the total units that exited your system at the end of the simulation and dividing it by the number of time units your model ran
if you run a model with the above characteristics for 10 days you would expect 20 units to have exited the system.
I am desperately searching for an efficient way - if there is one - to solve some kind of a recursive task in T-SQL (I could successfully model it in excel and on paper with an iterative solution - as many CMAs would for a small example, re-allocating shares of cost between pairs of support units serving each other in iterations and minimising the balancing unit's unallocated cost leftover to a reasonably small number to stop iterations/recursion).
Now I am trying to find a good scalable solution (or at least a feasible approach to it) how to achieve the same in T-SQL for this typical computational task in the managerial accounting area: when some internal support units service each other (and incur periodic costs, like salary etc) to produce at the end let's say 2 or 3 final products together as a firm, and as a result their respective shares of internally generated support overheads need to be reasonably (according to some physical base distribution, lets say - man hrs spent in each) allocated to these products' cost at the end of the costing exercise.
It would be quite simple if there was no reciprocal services: one support unit providing some service to other support units during the period (and a need to allocate respective costs too alongside this service qty flow) and the second and third support units doing the same thing to other support peers, before all their costs get properly berried into production costs and spread between respective products they jointly serviced (not equally for all support units, I'm using activity-based-costing approach here)... And in a real case there could be many more than just 2-3 units one could manually solve in excel or on paper. So, it really needs some dynamic parameters algorithm (X number of support units servicing X-1 peers and Y products in the period serviced based on some qty-measure/% square matrix allocation table) to spread their periodic cost to one unit of each product at the end. Preferably, somehow natively in SQL without using external .NET or other assembly references.
Some numeric example:
each of 3 support units A,B,C incurred $100, $200, $300 of expenses in the period and worked 50 man hrs each, respectively
A-unit serviced B-unit for 10 hrs and C-unit for 5 hrs, B-unit serviced A-unit for 5 hrs, C-unit serviced A-unit for 3 hrs and B-unit for 10 hrs
The rest of the support units' work time (A-unit 35 hrs: 30% for P1 and 70% for P2, B-unit 45 hrs: 35% for P1 and 65% for P2, C-unit 37 hrs for P2 for 100%) they spent servicing the output of two products (P1 and P2); this portion of their direct time/effort easily allocates to products - but due to reciprocal services to each other some share of support units' cost needs to be shifted to a respective product cost pool unequal to their direct time to product allocation (needs an adjusted mix coefficient for step 2 effects).
I could solve this in excel with iterating algorithm and use of VBA arrays:
(a) vector of period costs by each support unit (to finally reallocate to products and leave 0),
(b) 2dim array/matrix of coefficients of self-service between support units (based on man hrs - one to another),
(c) 2dim array/matrix of direct hrs service for each product by support units,
(d) minimal tolerable error of $1 (leftover of unallocated cost in a unit to stop iteration)
For just 2 or 3 elements (while still manually provable on paper) it is a feasible approach, but this becomes impossible to manually prove for a correct solution once I have 10-20+ support units and many products in a matrix; and I want to switch from excel and VBA to MS SQL server and t-sql for other reasons.
Since this business case as such is not new at all, I was hoping more experienced colleagues could throw an advise how to best solve this - I believed there must have been a solution to this task before (not in pure programming environment/external code).
I am thinking to combine CTE(recursive), table variables and aggregate window functions - but hesitate/struggle how to best/exactly put all puzzle elements together so it is truly scalable for my potentially growing unit/product matrix dimensions.
For my current level it's a little mind blowing, so I'd be grateful for an advice.