Impact - A Modelica Package Manager

As mentioned previously, Xogeny collaborated on the development of an open source package manager for Modelica. This package manager, called impact, allows Modelica developers to easily fetch versions of their favorite libraries whether they are developed by the Modelica Association or third parties.

The latest version of the impact package manager is now available from PyPI and GitHub. Version 0.5.8 introduces, for the first time, full compatibility with both Python 2 and Python 3.

These improvements are due to the hard work of Dietmar Winkler and Matthis Thorade.

NAFEMS Americas 2014


I spoke recently at the NAFEMS Americas Conference. This group tends to focus on CAD, FEM and CFD stuff, historically at least. But I was really pleasantly surprised to see a tremendous amount of interest around two themes from my talk.

System Simulation

The first was system simulation. There seems to be a growing interest in the NAFEMS community about system simulation. Obviously, this is an area I'm really interested in. One topic many people were discussing was how to connect system simulation and other types of analysis that incorporated geometry. Since my Ph.D. was in FEM, this is a topic I've thought about quite a bit myself. Coincidentally, I just produced a series of webinars for Dassault Systemes and one of them is on this very topic! If this is a topic you are interested, I encourage you to fill out the form to get access to the video.

Reaching Non-Experts

One of my big goals is to try and extend the reach of simulation to non-expert users. As someone who worked on building complex mathematical models for a long time, I was always frustrated by the lack of "reach" these models had. This was another theme of my talk that seemed to be getting a lot of attention at the conference.

My Presentation

Since I work primarily on web-based applications, I chose to make a presentation that was web-based (using a tool I developed called cadeau, BTW). That means no PowerPoint, no PDF. This presentation was dynamic and included interactive web-applications embedded in it. As such, it wasn't really possible to include it on the USB handed out at the conference. But, because it seemed to be well received and several people asked me about getting a copy, I produced this video that covers all the topics I covered at the conference and a few more:

Video: Web-based Engineering Analysis at NAFEMS Americas 2014

(A lower-resolution version is available on YouTube as well or at least will be once they are done processing it)

Remember - If you want to keep up on what is going on at Xogeny (blog posts, book updates, etc), don't forget to sign up for the Xogeny mailing list.

The Importance of Standards

I recently sat down with Jeff Waters from Modelon to discuss the importance of standards. I feel there are many lessons that we, as engineers, can learn from the world of software. This is a recurring theme in my work and on the blog. That same thread comes through in this discussion on standards in modeling, simulation and engineering.

Check out the Modelon site for this and other interviews recorded during the Modelica'2014 discussion.

Announcing Modelica by Example

Free Interactive Book: Modelica by Example

During Modelica'2014, I unveiled the very first public release of my new book, "Modelica by Example". Since then, the book has been available on a special site.


"Modelica by Example" started off as a Kickstarter project. As a result of the generous contributions, that project was funded. At the recent Modelica'2014 conference an "Early Access" version of the book was released.

This was a great example of a community driven project to make Modelica more accessible.

Creative Commons License

The book is distributed under a creative commons license. This means that the contents of the book an be freely redistributed (as long as it is done on a non-commercial basis and the contents of the book are not changed).

I'm also pleased to announce that there are plans for translations of the book into Spanish, Chinese and Italian (and hopefully more languages in the future).

Free HTML Version

A free HTML version of the book is available at This book can be used by anyone interested in learning Modelica.

Electronic Formats

I am also producing ePub and PDF versions of the book. These are available for download to those who have purchased a copy of the book. Pricing of the electronic formats is "Pay what you can". The idea here is to make the book affordable for students by allowing them to set their own price. My hope is that other people using the book for professional purposes will pay what they think the book is worth to them.

Integrated Browser Simulation

The free HTML version of the book features "Integrated Browser Simulation". In practice, what this means is that example models from the book can be simulated directly in the browser. This allows readers to adjust parameter values given in the example models to see how the response of the example will change for different parameter values.

We will be using this same technologies in some new products we are currently working on. To learn more, sign up for the Xogeny mailing list and we'll keep you up to date on all the things we are working on.

Early Access Version

This version is an "Early Access" version. The book is mostly complete. There are a few unfinished sections that I hope to wrap up soon. But the core material is there so anybody interested in learning Modelica can start now.

The goal of the "Early Access" version is to get this material into the hands of people who can use it as quickly as possible and to collect feedback on the book before publishing a print version of the book.

But today I'm releasing v0.3.0 of the book with the following changes since the initial public beta release (v0.2.0):


  • Moved the site to with redirects from beta site.
  • Lots of cleanup of annotations by @tbeu and @dietmarw
  • Switched back to using MathJax (looks nicer, but requires JS)
  • Updated the README to help orient people who want to contribute.
  • Incorporated a bunch of excellent fixes and improvements from @mrtiller related to #42.

Bug Fixes

  • Merged a the following pull requests from @tbeu: #143, #142, #141, #139, #137, #117 and #93
  • Merged a change from @tbeu regarding a heat transfer example in the discussion on packages.
  • Merged a bunch of changes from @tbeu that improve the external function examples and clean up a few other things.
  • Fixed an error in the source code for the 1D heat conduction equation examples and fixed a recurring error (see issue #53) in the equations presented along with the source code.
  • Fixed issue #61 which involved a misplaced annotation.
  • Fixed an error in one of the Lotka-Volterra equations raised in issue #50.
  • Corrected the explanation on the unit attribute raised in #59


The source material is available on GitHub. If you find an issue with the book, you can report it on the GitHub issue tracker or, even better, submit a pull request with a suggested fix.


My goal is to provide a definitive reference for Modelica that is widely accessible and affordable. Today marks release 0.3.0 and I'll be working toward a 1.0 release that we can publish in print form.

At the book site, you can sign up to be included in the book's mailing list. If you sign up, you'll receive updates whenever new versions of the book are released. You can also purchase the electronic versions of the book as well.

Modelica 2014

Xogeny at Modelica'2014

Xogeny was formed just before the last Modelica Conference. At Modelica'2014 we will be presenting lots of stuff we've been working on since then.

Here is some of the stuff we'll be presenting...

Modelica Conference App

Modelica events always have lots of quality presentations. I'm sure this year's event will be no different. At Xogeny, we were so excited about the conference program, we made a web app to help attendees organize their time.

Free Book: Modelica by Example

Another big thing we'll be talking about is the upcoming book Modelica by Example written by Dr. Michael Tiller. This was initiated as a Kickstarter project with the explicit goal of making an HTML version of the book available for free.

We'll have a big announcement to make with regards to the book. We aren't ready to spill the beans just yet, but if you want to keep up on the latest news regarding the book, sign up for the book's mailing list.


We'll be presenting our work with Oak Ridge National Labs building a web-based user interface Small Modular Nuclear Reactor design. This work was a collaboration between ORNL, Modelon and Xogeny.


At Xogeny we love open source. In fact, since the last conference, we've started a few of our own open source projects. The first is the impact project. Impact is a package manager for Modelica to make downloading libraries as easy as possible.


Another open source project initiated by Xogeny is the recon project. The recon project defines a new set of file formats for storing simulation results. These new formats provide greater flexibility than traditional formats and are optimized to minimize network and disk access for individual signals. See the recon documentation for more complete details.

Keeping in Touch

If you are interested in hearing about Xogeny related news, you can sign up for our mailing list. If you sign up, you can unsubscribe at any time.