Rank: 75 based on 812 downloads (last 30 days) and 8 files submitted
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Mark Mikofski

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SunPower
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22 Sep 2014 Screenshot IAPWS_IF97 functional form with no slip Water and steam properties and derivatives based on the IAPWS IF97. Functional form. No slip. Author: Mark Mikofski control design, simulation, chemistry, modeling, hydrodynamics, thermodynamics 125 12
  • 4.85714
4.9 | 7 ratings
19 Feb 2014 Screenshot polyfitZero Fit polynomial to data, forcing y-intercept to zero or arb. value and slope to zero or arb. value Author: Mark Mikofski mathematics, modeling, data exploration, interpolation, polyfit, polyval 101 8
  • 4.66667
4.7 | 6 ratings
27 Jan 2014 Screenshot Newton-Raphson solver Yet another solver that uses the backslash function to solve a set of non-linear equations. Author: Mark Mikofski mathematics, optimization, data exploration, interpolation, fsolve, lsqnonlin 471 17
  • 4.5
4.5 | 4 ratings
14 Oct 2013 Screenshot JGit4MATLAB JGit4MATLAB is a wrapper for JGit in MATLAB. It is meant to be used from the MATLAB command window. Author: Mark Mikofski git, scm, dvcs, version control, source control manage..., distributed version c... 28 12
  • 4.0
4.0 | 2 ratings
03 May 2013 Screenshot Spline2D or Piecewise Continuous 2D Polynomials Fit a 2D function with piecewise continuous polynomials Author: Mark Mikofski data exploration, interpolation, mathematics, modeling, optimization 16 0
  • 5.0
5.0 | 1 rating
Comments and Ratings by Mark View all
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06 Oct 2014 JGit4MATLAB JGit4MATLAB is a wrapper for JGit in MATLAB. It is meant to be used from the MATLAB command window. Author: Mark Mikofski

**Quick Tip:** Use `>> jgit update` to download the latest version of JGit. The older version is archived in the folder called `older-versions/` and the file `version` is updated with the latest version number. Then restart MATLAB for the update to take effect.

19 Sep 2014 IAPWS_IF97 functional form with no slip Water and steam properties and derivatives based on the IAPWS IF97. Functional form. No slip. Author: Mark Mikofski

ok Nahla, I found the bugs and fixed them enough so that you should get the correct derivatives for specific volume along the saturated liquid and vapor lines, but you will need to use the new dvLdp_p and dvVdp_p functions. There are 2 new tests included which will plot the derivatives together with finite difference approximations. For more details please see IAPWS "Revised Advisory Note #3, Thermodynamic Derivatives from IAPWS Formulations" (http://www.iapws.org/relguide/Advise3.pdf) which details how derivatives are found. To get the derivatives on the liquid and vapor lines, since the specific volume and enthalpy are functions of p or T only then a Taylor expansion, dhL/dp = (dh/dp)_T + (dh/dT)_p * dT_sat/dp_sat is used where the partial derivatives (dh/dp)_T and (dh/dT)_p are found using the advisory note separately for regions 1, 2 and 3. Ditto for specific volume. I made some silly sign errors, and I also switched cv accidentally for cv+p*v*alphap - I think my eyes wandered to internal energy, u, in the table instead of enthalpy, h, which is right below it. Sorry for the inconvenience! Thanks for noticing the error!

19 Sep 2014 IAPWS_IF97 functional form with no slip Water and steam properties and derivatives based on the IAPWS IF97. Functional form. No slip. Author: Mark Mikofski

Nahla, I think you may have discovered a typo in IAPWS_IF97. If I change the signs of the region 4b terms in dhLdp on line 914 to ...

dhLdp(valid4b) = (v3L - Tsat4b.*alphap3L./betap3_rhoT(rho3L,Tsat4b).*(1 - p4b.*alphap3L.*dTsatdpsat4b))/conversion_factor + cv3_rhoT(rho3L,Tsat4b).*dTsatdpsat4b;

I get a curve that matches a finite difference approximation of dhLdp. This function is also used in dvdp_ph(). Can you please post an issue on Github, and try to correct the error and validate it versus the IAPWS_IF97 documentation. Thanks!

15 Aug 2014 X Steam, Thermodynamic properties of water and steam. Water properties A complete IAPWS IF-97 standard. Author: Magnus Holmgren

If you are looking for an alternative to XSteam, please consider - http://www.mathworks.com/matlabcentral/fileexchange/35710-iapws-if97-functional-form-with-no-slip - it is vectorized, more current, and documented here: http://mikofski.github.io/IAPWS_IF97/

04 Feb 2014 Newton-Raphson solver Yet another solver that uses the backslash function to solve a set of non-linear equations. Author: Mark Mikofski

@Regan Dhakshnamurthy, the latest changes to newtonraphson now allow sparse matrices, and will also quit if your jacobian is singular, but there is no preconditioning. You could hack in to lines: 98-99 where it says "% TODO: let user set weights
weight = ones(numel(FUN(x0)),1);" and change the weights to something different, it's not really the same, but this is the matrix used to scale the Jacobian as you can see on line: 112, "Jstar = J./J0; % scale Jacobian" Good luck and let me know if it works and I will make the weights argument callable

Comments and Ratings on Mark's Files View all
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06 Oct 2014 JGit4MATLAB JGit4MATLAB is a wrapper for JGit in MATLAB. It is meant to be used from the MATLAB command window. Author: Mark Mikofski Mikofski, Mark

**Quick Tip:** Use `>> jgit update` to download the latest version of JGit. The older version is archived in the folder called `older-versions/` and the file `version` is updated with the latest version number. Then restart MATLAB for the update to take effect.

26 Sep 2014 Newton-Raphson solver Yet another solver that uses the backslash function to solve a set of non-linear equations. Author: Mark Mikofski ali

niceone

20 Sep 2014 IAPWS_IF97 functional form with no slip Water and steam properties and derivatives based on the IAPWS IF97. Functional form. No slip. Author: Mark Mikofski Nahla

Thank you Mark, it is working now. I appreciate it.

20 Sep 2014 IAPWS_IF97 functional form with no slip Water and steam properties and derivatives based on the IAPWS IF97. Functional form. No slip. Author: Mark Mikofski hgghh

https://www.drupal.org/u/hd.-clemson.-vs.-florida.-state.-live.-stream.

19 Sep 2014 IAPWS_IF97 functional form with no slip Water and steam properties and derivatives based on the IAPWS IF97. Functional form. No slip. Author: Mark Mikofski Mikofski, Mark

ok Nahla, I found the bugs and fixed them enough so that you should get the correct derivatives for specific volume along the saturated liquid and vapor lines, but you will need to use the new dvLdp_p and dvVdp_p functions. There are 2 new tests included which will plot the derivatives together with finite difference approximations. For more details please see IAPWS "Revised Advisory Note #3, Thermodynamic Derivatives from IAPWS Formulations" (http://www.iapws.org/relguide/Advise3.pdf) which details how derivatives are found. To get the derivatives on the liquid and vapor lines, since the specific volume and enthalpy are functions of p or T only then a Taylor expansion, dhL/dp = (dh/dp)_T + (dh/dT)_p * dT_sat/dp_sat is used where the partial derivatives (dh/dp)_T and (dh/dT)_p are found using the advisory note separately for regions 1, 2 and 3. Ditto for specific volume. I made some silly sign errors, and I also switched cv accidentally for cv+p*v*alphap - I think my eyes wandered to internal energy, u, in the table instead of enthalpy, h, which is right below it. Sorry for the inconvenience! Thanks for noticing the error!

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