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- about T+
The reduced temperature T+ is NOT the same as the reduced temperature Tr.
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- converting units
1) the pressure compares favorably up to rho = 0.02 mol/cm3 for both isotherms.
2) there are some negative P for the lower T because there is a vdw loop.
3) remember that the units are reduced, so you have to convert P+. Did I give you values for epsilon and sigma? eps/k = 120K, sigma = 3.4 Angstroms.
Dear Dr. Lira,
For problem 3, I seem to be having difficulty in interpreting the data.
I have gone through the calculations for "part a" and tested the Linux calcs versus PREOS.xlsx that we learned about in ChE 804. I discovered that I am off by about a magnitude of 10- for example I calculate 0.084 MPa at a density of 0.00025 mol/cm^3. Then with PREOS.xlsx, I get something like 0.000042 mol/cm^3. I am unsure why this is happening. Should we expect a better match between the values?
Also, I have used Linux to calculate negative values of pressure (this only happened for the T+ = 0.9 data set). I am unsure how I can get a negative pressure here, and if I should take the absolute value to make the plot.
Any guidance would be appreciated.
Best,
Nick
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- Re: output pressure file
Another suggestion is to look at the script in the 'Block' folder. That may be where the pressure file is created instead of the 'Run' folder. That is were the averages are compiled.
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- output pressure file
The best answer is to do look at the 'run' script to see what file is renamed to pressure.txt.
Then, do a 'grep' command on *.f files looking for a 'write' command to that file. You will find the variables being written to that file. Note that the output files are identified by numbers during the input/output process. Depending on the manner that the code is written, sometimes the file names are given in the code. Otherwise they end up with names according to the numbers and can be renamed using a 'cp' copy or 'mv' move command in a script.
My memory is that one column may be values and the other column may be fluctuations.
Carl Lira
-----Original Message-----
From: jamesch8@egr.msu.edu [mailto:jamesch8@egr.msu.edu]
Sent: Wednesday, November 06, 2013 8:17 AM
To: lira@msu.edu
Subject: ChE 821: Homework Set 9
Dear Dr. Lira,
I have a quick question about homework set 9, problem 3. When we create
the pressure.txt file there are 2 columns for each density and temperature
point. I am not sure why there is two numbers for each pressure? Is the
first column pressure and the second column volume?
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- properties are extensive
recall that U, A, S, Cv are extensive for stat mech.
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- Re: Error in Nucleotide statistics part (d)
The computer answer now shows the corrected answer.
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- Re: Error in 'Groups in a mixture, part (b)'
Sorry, I meant that I forgot to account for the number of 'pairs' not 'groups'.
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- Error in Nucleotide statistics part (d)
Part (d) of this problem had an error in my calculation. I did not account for symmetry correctly when all sites are the same. There is an analogy with my error here and the way that the Maxwell-Boltzmann calculation works. If I divide by two for symmetry, I undercount the cases where all sites are the same because they did not occur twice too often before I divide for symmetry. I will give everyone credit.
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- Error in 'Groups in a mixture, part (b)'
I made an error counting in 'Groups in a mixture part (b)'. I will give everyone credit. I forgot to include the number of groups where both groups are the same. I have changed the correct answer.
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- How to subscribe to RSS feeds in Firefox
Here is a link about how to subscribe to RSS feeds in Firefox. A limitation of RSS feeds from loncapa is that you must be logged in to the relevant course for the links to work properly. The icon will be highlighted when something is new, but for the link to work, log into the course before following the link.
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- clarification
I have clarified wording in this problem. The chain is to be of length 4 for all parts of the problem. I also changed the wording to clarify the difference between part (c) and (d). Please post or send an e-mail if the physical constraints are not clear.
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- distance traveled
Don't get side-tracked with some of the complicated analysis in the above reference for the 1D walk. There is an extremely easy way to get the most likely location after a given number of steps. Use some thought rather than a lot of calculations or a computer program.
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- also percent
Also, I asked for the percent, but I had programed for the probability rather than the percent probability. This has been fixed.
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- tolerance fixed
I forgot to set a tolerance for this problem so students were not getting marked correct. This has been fixed.
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- About (dF/dL)_T
During office hours some students were taking the total transform of dU for the rubber band problem and then working to get (dF/dL)_T.
It was not coming our correct because you had dropped the N-mu term. You cannot drop that term. You must use all n+2 variables.
On a different topic, also, when you choose variables for generic application of Euler's Theorem, you should choose one from each of the conjugate pairs.
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- TM 5.5 (problem 4)
There are multiple ways that you can solve this problem.
1) some of the derivatives in TM section 5.3 can be used.
2) many of the derivatives in TM section 5.3 come from Euler's Theorem in appendix C. Direct use of Euler's theorem may be helpful.
3) There is another indirect method for part (a). You can apply the expansion rule to the Gibbs-Duhem equation and then look for a Maxwell relation to complete the proof.
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Dear Professor Lira,
I am stuck on problem 4 of the homework and was hoping to ask you a
question. For parts a) and b) I think I can use the triple product rule to
prove the equalities however, to do this I need to assume that d(mu) and
dP are zero. Is this correct. am I able to assume they are 0?
Thank you,
Christine
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- How to follow my posts using RSS
Though lon-capa does not provide e-mail notification of a discussion forum, it is possible to subscribe to an RSS feed so that you see when I have posted an answer. (I will do my best to remember to post answers to my RSS feed.)
RSS feeds are updated by your 'browser/e-mail client' when you open your program. They are a little different from e-mail messages that are delivered to you e-mail box. The 'browser/e-mail client' checks for updates to the RSS when it loads. Consult 'help' for your browser or e-mail client.
To subscribe to my RSS, go to the syllabus and click my name.
At the bottom of my profile, click the RSS/podcast link for the feed that you want to follow.
If the wrong RSS reader loads, you can enter the URL manually. Right-click the RSS/podcast link and select 'Copy'. Then paste the url into your RSS reader.
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