Friday, March 21, 2014
That got me thinking again about how important it is that ExtendSim has an internal relational database capability for storing and managing data. An internal database serves as a bridge between the simulation model and external data repositories, both to supply data to the model and to report model outputs. It also helps that ExtendSim has robust tools to facilitate the exchange of data with external sources. For example, its ADO (ActiveX Data Objects) capability allows ExtendSim to perform high speed data exchanges with external databases such as Microsoft Access and SQL Server. And the ExtendSim DB Add-In for Excel allows analysts to fully specify an ExtendSim database in Excel, including parent/child relationships, formatting, and data validation, and then retrieve useful information from the model without having to learn anything about simulation or even how to use ExtendSim.
But the storage, management, and transfer of data is only one part of the story. What is even more important is that the data gets used in a meaningful manner. And that is where simulation comes in. Simulation is a low cost, high reward method that allows you to analyze existing processes and explore the effect of changes. Likewise you can get assurance when designing completely new systems and processes since you've simulated their behavior or performance in advance. An intelligent way to do business.
Monday, February 10, 2014
- Multiple Notebooks
- Docking tool palettes
- Tear-off tabs in dialogs and worksheets
- Multiple undo
- Improved zoom
- Scaled text – editable while scaled
- Object grouping
- Object free rotation
- Object transparency/translucency
- Polygon – add/remove points (alt click on a segment.)
- Improved dialog editor
- Code completion improvements
- Graphics objects on the dialog box
- Thermometer column tag
- Multiple animation objects moving at the same time
- Improved Help system
- Ability to run on all current Windows and Macintosh operating systems.
- And many more improvements.
Tuesday, December 24, 2013
Friday, March 9, 2012
“We’re trying to understand the traffic patterns along this route to Half Dome.”, she answered. "Participants show their time cards to officials stationed at various waypoints along the way. The officials will mark your time of arrival at each waypoint. Would you like to participate?”
“Perhaps.”, I said. “This sounds like you’re collecting data for a simulation study. Is that true?”
“What simulation tool are you using?”, I asked.
“Umm….I think it’s called ExtendSim. Yeah. That’s it. It’s called ExtendSim.”
I smiled and said, “Well, in that case we’d be very happy to participate in your study.” ;-)
So the next time someone asks you, “Where is ExtendSim used?”, maybe the most appropriate response is, “Where is it not used?”
Monday, April 18, 2011
Wednesday, November 3, 2010
The gold standard for a comparison is Tom Schriber and Dan Brunner’s perennial “Inside Simulation Software: How it Works and Why it Matters”. This paper does not attempt to recommend one software product over another, but it does give insight into the inner workings of a variety of simulation packages. When Tom and Dan were including ExtendSim (Extend) into their paper, we exchanged nearly 100 emails detailing the precise behavior of our software. The authors have taken care to update the paper as new versions of ExtendSim have come out. There are other good reviews as well. I have not always agreed with their conclusions, but I do respect their methodology.
I won’t reference the paper on the other end of the spectrum. However, I did find 14 obvious technical errors in a little more than a page of text describing ExtendSim. These included the wrong web site, incorrectly stating that there were limitations on the number of levels of hierarchy, and even the product name was incorrect. The author never contacted us or asked us to comment on his review.
So, if you are looking at simulation software reviews, take the following steps to make sure that you are getting a thoughtful, accurate commentary:
- Contact the author and ask them if the paper was reviewed by the simulation software vendors before publication.
- Look for obvious technical errors. Generally, this is an indication that the author did not do their homework.
- Did they use the latest version of the software?
- Does the author have any connection with a simulation software vendor, currently or in the past?
- If you can, contact modelers who use the software in the paper. Ask if they agree with the conclusions.
As software developers, you can expect us to be biased towards our own creations. Unfortunately, you cannot always find that even in neutral third party evaluations. Caveat emptor.
Friday, October 1, 2010
I feel the bias block does not get the use it deserves and would like to make a case for it.
If you do not use the Rate library, there may be no point trying to understand the Bias block…However, lack of familiarity rather than true functionality might be the reason you’re not using Rate. The ExtendSim manual has a good discussion of ExtendSim AT’s discrete rate capabilities; you may want to read up on it a bit. For now let focus on this little block called the Bias block.
The block is small and simple but carries a powerful concept. The bias block allows the rate of flow through particular model sections to be maximized. In other words, after defining where the flow should “preferably” go, the model optimizes the direction of the flow.
To illustrate my point lets give a practical example:
-Goal: The model purpose is to properly allocate power supply so that each customer gets what they need at the lowest possible cost.
-Setting: 3 different sources of power, 4 pools of users and a distribution network.
-Logic: Each source of power has an associated cost and is linked to the distribution network. Each pool of users needs a certain amount of power and is connected to the distribution network.
Cost per Megawatt
-Implementation: The modeler will construct the distribution system, the suppliers and the consumers… When all of that is done, the modeler can position a bias block next to each power supply; the lowest cost producer will be given the highest priority and so on…. And that’s it; the model is done and will distribute energy at the lowest cost.
The concept of bias block allows a modeler to look at his model as a global system. What is flowing through the system will follow the preferences provided by the bias block.
If the Bias block gets used more, I have in mind some fun upgrades to make the block even more powerful. Right now, the Bias parameter only authorized priorities between different parts of the model. It would be a fun new development to allow a full “objective function” to be defined which would be either maximized or minimized.