Why upgrade to ASCEND Version 9?

The ASCEND Project has released a substantially improved version of the ASCEND IV mathematical modeling software for Linux, other UNIX, and Windows operating systems.

This software is available free at
http://ascend.cheme.cmu.edu

The downloadables are also mirrored at a site in Norway, as explained on the web page.

ASCEND is an ongoing project in the Department of Chemical Engineering and ICES/EDRC at Carnegie Mellon.

If you have no interest in equation-based modeling or dynamic simulation in any domain, and if you have no interest in chemical engineering modeling, you should probably stop reading here. If you are still interested, please continue to find out why you should upgrade. If you want to know some of the reasons you might want to get ASCEND for the first time, see our announcement for release 0.8

Thank you.

Ben Allan, Duncan Coffey, Vicente Rico-Ramirez, Mark Thomas, Ken Tyner, and Art Westerberg

ASCEND Project, Carnegie Mellon University
http://www.cs.cmu.edu/~ascend
ascend+www@cs.cmu.edu

Reasons for upgrading

Many reported and unreported performance bugs have been repaired.

Very substantial improvements have been made with release 0.9 in the following areas:

  • Documentation and modeling methodology
  • Steady-state and dynamic unit operations and thermodynamics libraries
  • User interfaces
  • Communication with external tools such as Matlab and spreadsheets
  • Computational performance

Documentation

  • An extensive batch of HowTos explain modeling with ASCEND and our best practices for obtaining reusable models. See http://ascend.cheme.cmu.edu/pdfhelp.htm
  • Literate programming (literate modeling) support with the new language construct 'NOTES' and simple in-line comments. Both types of comments can be browsed and searched interactively.

Libraries

  • New libraries for dynamic tanks, flashes, reactors, and distillation courtesy of Duncan Coffey and Chad Farschman, students of Erik Ydstie.
  • Fully redesigned object interfaces for the unit, stream, and thermodynamics packages make using existing libraries a snap. Creating new unit operations or adding correlations in the thermodynamics is extremely easy. (If 'easy' and 'thermodynamics' can be properly used in the same sentence, that is.)
  • Steady-state and dynamic libraries follow the same design and use the same thermodynamics, for easy transition when you become ambitious :-).
  • A horde of documented, simple examples that introduce equation-based modeling is now available.

User interfaces

  • A simple tool for generating large case studies has been created. Demos and documentation of its use are included.
  • A number of powerful user-controlled filters have been added to the GUI to tame the information explosion that characterizes equation-based modeling. When these are activated, only the desired information is displayed.
  • Many new tools have been added to quickly answer common queries (e.g., how are models related to each other, what variable types would be expressible using the following units, which variables have values far from their scaling values?)
  • The ability to create a MODEL definition from an interactively defined string rather than an input file is provided.
  • Substantial effort has gone into creating a more unified look and feel to the GUI and to allow appearance customization.
  • Easy access to many features via the other (normally right) mouse button is provided.

Communication tools

  • Easy to use translators to convert output from ASCEND dynamic models into portable text formats for tools such as Matlab or a spreadsheet are included. This allows for advanced graphics, analyses, and other post-processing.
  • As with the previous release, Tcl8.0 provides tools that enable ASCEND to act as a client or a server for other processes on the same computer or (with sockets) across the network.

Performance

  • Algorithmic improvements in the ASCEND compiler have enabled us to save as much as 66% of the memory needed for large simulations. These same improvements build simulations at the rate of 120,000 equations/minute on a Windows PPro 200 - handling large models becomes an interactive process. Even better performance is available with Linux.
  • Dynamically generated binaries boost solution speed. In physically based mathematical models, there are typically only 100 to 1000 unique equations. These equations will repeat over and over, often in surprising ways. We now find this small 'stencil' of equations automatically. Given this list we generate small, dynamically compiled and loaded C code for evaluating residual functions. You must have an ANSI C or C++ compiler to use this feature. Works with both UNIX and Windows compilers.

Thank you for your time,

ASCEND Project
Institute for Complex Engineered Systems/Engineering Design Research Center
Carnegie Mellon University
ascend+www@edrc.cmu.edu
http://www.cs.cmu.edu/~ascend/



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