Arena Newsletter and Blog

Welcome to the Arena Tips and Tricks column! We’ll be using this section of the newsletter to highlight features of Arena that we want to call to your attention – either they may not be as well known, or they’re very valuable and deserve a second glance. For our first column, we’ll be starting with the A() Variable.

There are various methods of reading in data to a model in Arena, one of the more popular methods is the Direct Read feature which allows you to read in data directly to Variables and Expressions.  Variable data can be read in at the beginning of the simulation; replication or prior to the model being compiled (PreCheck).  Expressions only allow you to read in data prior to the model run so the PreCheck option is the only one available and defined by default.

When developing a model of a large system, you may have multiple large two-dimensional variable arrays that describe equipment parameters, facility characteristics, or other aspects of your system. Many times you can streamline your modeling effort by collecting these two-dimensional arrays under one “umbrella” and then pointing to the specific piece of information where needed in your logic. For instance, let’s say your supply chain model needs to define specific information for several different sites. Each site has up to 1000 SKUs and each SKU has a unique activity time for up to 20 activities. For clarity, you want to have each site’s information stored in its own uniquely-named, two-dimensional variable array. Furthermore, you anticipate the logic for the activities at each site will be similar, regardless of the site. Only the actual data values are expected to be different.

According to Wikipedia, skill-based routing (SBR) is a call-assignment strategy used in call centers to assign incoming calls to the most suitable agent, instead of simply choosing the next available agent. However, many types of systems have aspects where skill-based routing should be considered – retail, quick service restaurant, and even manufacturing and maintenance systems can utilize the technique. Skill-based routing occurs anytime an entity needs to be directed to a resource with the most applicable skill sets or capabilities. In this fashion, entities can be processed by resources that can provide better service or faster completion of the task.

As anyone who’s been to an airport recently can attest, queueing is part of the experience. We queue to get through security, we line up to order food or drinks, and last we wait our turn to board the aircraft. Most simulation models revolve around contention for resources or constraints with limited capacity, and the modern flying experience has its fair share of contention.

In Lean manufacturing, one common technique is to sort jobs based on their expected processing time and then to run the shortest ones first. To do this in Arena, there needs to be an attribute on which to sort the queue. For processing jobs where the processing time will be known, the time can be written to the attribute and then used for both the sorting and the processing. 

A mine and its associated ore processing plant are typical environments where simulation provides important benefits.  Simulation is used in these plants to address many important business considerations:

Arena v15 is a native 64-bit product. Which means that Arena utilizes significantly more memory than the 2 GB limit of 32-bit software. 64-bit applications can utilize up to 8 Tb of memory!

To meet demand or satisfy schedules it may be necessary to create a partial batch in your model.  With Arena v15's new Adjustable Batch module you can easily create a partial batch or group of entities.  The adjustable batch may be based on time or a signal.  This video demonstrates how you would create a partial batch if the Maximum waiting time has been met.