[ASCEND] help to contribute Re: Ascend-sim-users Digest, Vol 44, Issue 1

[<mar...@di...>]

Hi Arpit and everyone,
how about trying to implement the UNIFAC and PSRK models to Ascend?:
http://ascend4.org/Predictive_Soave-Redlich-Kwong_(PSRK)
http://ascend4.org/Modified_UNIFAC_(Dortmund)

I have a Python script for the modified UNIFAC model which I can send to 
you.

But the first step would be to store all the needed parameters. To quote 
John from Ascend-sim-users Digest, Vol 34, Issue 1 
(https://sourceforge.net/p/ascend-sim/mailman/message/34712639/):

"You may have noticed the 'helmholtz_prepare' and 'pengrob_prepare'
functions. These are for converting the 'filedata' datastructures
(which could in principle be stored in data files rather than C
structs_ and the 'rundata' data structures. These data structures are
deliberately separated by design, so that pre-calculation can be done
if needed. This is what we have done recently with the TTSE code
(which is 90% complete, still needs some tweaks, it's in Sidharth's
branch)."

Take a look at 
http://code.ascend4.org/ascend/branches/sid/models/johnpye/fprops/helmholtz.c?diff_format=h&revision=2982&view=markup&pathrev=2982
and at http://ascend4.org/User:Sidharth

So it would actually be nice to find a general way to store data for 
Ascend, be it as a SQLite database or XML data files with a graphical 
interface for users to add data. Quote from John:

"Regarding the properties database, I should mention that Richard Towers
did a bit of work on implementing XML storage for fluid properties. We
didn't complete the integration work, but there's some interesting stuff
there, including the ability to render the XML to HTML using XSD, for
easy human-readable checking/review of correlation data that has been
entered. Some kind of editable data file is good for people wanting to
add new species, but at the same time, it adds some parsing overhead to
the codebase compared to the current approach of declaring C99 data
structures."

See: http://ascend4.org/User:RichardTowers

So either just convert all the data from appendix B in the following 
publication to C data structs: 
http://dx.doi.org/10.1016/j.fluid.2004.11.002

or try to go for a more elaborate way of storing the data as described 
above.

When the whole database system is set up one could start implementing 
linear algebra routines for property calculations which are needed for 
e.g. UNIFAC and PSRK. ASCEND only has code covering the matrix routines 
needed for solving the system of equations of the model a user has 
implemented:

"I don't think that reusing the ASCEND matrix routines is the 
necessarily
the way to go for property calcs."

So basically convert the Python script I then will send you to C and 
access the database and perform the matrix inversion and matrix 
multiplication with LAPACK/CBLAS.

And finally embed the routine in ASCEND so that users can call 
UNIFAC/PSRK within ASCEND.


Hope this was of any help or inspiration. ;)

Cheers,
mark


On 2018-01-05 13:07, asc...@li... 
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> Date: Fri, 5 Jan 2018 01:12:44 +0530
> From: Arpit Thool <arp...@gm...>
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> how can i contribute ? i am good at maths and am currently pursuing my
> engineering degree in the field of computer science.
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