Quote from: deltaMass on 07/20/2015 05:01 pmSome time back I sent EW a paper on maintaining active tune resonance using a microwave PLL. I don't imagine anyone here has the resources for that, though. Which is why using very high Q is going to be problematic.Which is why I will be using active frequency control based on monitoring the real time VSWR from my Rf amp and constantly adjusting frequency (in +-1kHz steps) for lowest VSWR, which will keep my frequency right in the middle of the cavity sweet spot, even if it heats up and moves around a bit.
Some time back I sent EW a paper on maintaining active tune resonance using a microwave PLL. I don't imagine anyone here has the resources for that, though. Which is why using very high Q is going to be problematic.
I have a further suggestion: make all files public-domain. Specially all .ctl files.That way anyone can benefit from the work without any kind of bureaucracy.Public-domain helps the advancement of science.
Quote from: leomillert on 07/20/2015 07:31 pmI have a further suggestion: make all files public-domain. Specially all .ctl files.That way anyone can benefit from the work without any kind of bureaucracy.Public-domain helps the advancement of science.Hi all - been watching for 6 mos - I'm a former Aero CFD developer / researcher with a background in MechE / Aero Astro and Big Data / Data Science.+1 for putting the Meep ctls and results on Git with open read access and moderated commits.I plan to work on a GPU port of Meep to get it running 10x faster and have a cluster of machines on which I can / will run experiments as requested or available to help with the parameter studies and fundamentals.To help people like me contribute, perhaps this list can develop a set of parameter study requests that you can post on the wiki and people can register that they are running some parts of it and post results into the Git repo?
@notargetGPU Meep sounds excellent in the general case, but I'm not sure how much our particular use case of meep can be parallelized. It's already hitting the limits of Amdahl's Law - going from eight CPU threads to twelve CPU threads only saves about ten minutes on my machine. This is somewhat expected since it's modeling the behavior of a system over time - every step depends on the output of the step before it.
...We're all missing something WRT understanding the behavior IMO - ISTM that Traveller's theories of dissipative behavior [sic] can be studied using numerical experiments...
I wonder if a space launch platform lifted by EmDrives could be powered by microwaves emitted from the ground. Instead of converting the microwaves to electric power onboard through lossy rectennas, the microwaves would be directed into the cavities. No electric conversion!
I plan to work on a GPU port of Meep to get it running 10x faster and have a cluster of machines on which I can / will run experiments as requested or available to help with the parameter studies and fundamentals.
At this point, I think that the transient problem can be much better handled with an unconditionally stable FD time-domain operator rather than the conditionally-stable central difference FD time-domain operator used by Meep that constraints the solution to extremely small time steps and hence huge running times. If I get the time I may write a code to do that. I'll wait to see what happens with rfmwguy and SeeShell's experiments to dedicate the time to do that.
Quote from: Rodal on 07/20/2015 09:45 pmAt this point, I think that the transient problem can be much better handled with an unconditionally stable FD time-domain operator rather than the conditionally-stable central difference FD time-domain operator used by Meep that constraints the solution to extremely small time steps and hence huge running times. If I get the time I may write a code to do that. I'll wait to see what happens with rfmwguy and SeeShell's experiments to dedicate the time to do that. I looked briefly at the recent history of CEM FDTD stuff post-Taflove and see that people have done some work with implicit formulations, but I'm not sure how effective they are at really increasing CFL. As you know with CFD, the implicit methods don't improve things much for transient analysis when linearized and the fuller matrix solvers are too expensive for the benefit.For this case are we suffering from not enough time for evolution of the behavior? How much time do we need to get a meaningful qualitative view?One thing I'd like to do is just walk through the E/B fields with Fieldview or another decent viz tool (wish I still had access to AVS or Ames' FAST) and get a feeling for the cycles and interactions and also a quality assessment of the simulation. Any suggestion for a good OSS 4D capable visualization tool?
http://home.penglab.com/proj/vaa3d/home/index.htmlSupposedly this can do 4D and 5D visualizations of data. Is this what you were looking for, notarget?
The equations being solved (Maxwell's equations) are much simpler than the (nonlinear) Navier Stokes equations. Maxwell's equations are linear. The behavior is much, much simpler than in fluid dynamics.
Any way, at present aero has run about 6500 time steps to about 0.013 microseconds. It expect that it will take 1 to 10 microseconds to reach steady state.
Also what is most needed is:1) People to write an RF Source routine for Meep to model a magnetron, and much simpler than that just to turn -off the source: something that Todd Desiato (WarpTech) asked some time ago, but remains to be done2) People to write a pre-processing routine to model perforated end-plates with different patterns of perforation, and/or the whole fustrum perforated as presently being tested by rfmwguy and SeeShells.
Quote from: leomillert on 07/20/2015 07:43 pmQuote from: saucyjack on 07/20/2015 07:39 pmQuote from: leomillert on 07/20/2015 07:31 pmI have a further suggestion: make all files public-domain. Specially all .ctl files.That way anyone can benefit from the work without any kind of bureaucracy.Public-domain helps the advancement of science.Completely agree - repo should be publicly browseable, with accounts only needed for people committing. And ignore my "Men In Black" bad joke...If you want me to set this up on the wiki server, let me know; would just take a few minutes.tidux will do most heavy computing, so I think it would be better to have it set up on his emdrive.science. (but let's wait to see his opinion).Maybe we could use the wiki to detail the structure of the repository (its folders and files), how someone can commit, etc. What do you think?I concur on git, and suggest a clone on two sites is a good idea. Time I learned git.I'd still like to see a file/directory/test-run naming convention. The hierarchy proposed is a good start down that direction, but a uniform naming convention makes sense when there are multiple providers as well as multiple consumers.One question I have - who is expecting whom to hack on control files? How will the modifications be validated / verified against test objectives? I don't feel qualified, at either the lisp, the scheme, the meep script, nor scientific or engineering basis to make ANY sort of valid judgments as to how things should be coded.
Quote from: saucyjack on 07/20/2015 07:39 pmQuote from: leomillert on 07/20/2015 07:31 pmI have a further suggestion: make all files public-domain. Specially all .ctl files.That way anyone can benefit from the work without any kind of bureaucracy.Public-domain helps the advancement of science.Completely agree - repo should be publicly browseable, with accounts only needed for people committing. And ignore my "Men In Black" bad joke...If you want me to set this up on the wiki server, let me know; would just take a few minutes.tidux will do most heavy computing, so I think it would be better to have it set up on his emdrive.science. (but let's wait to see his opinion).Maybe we could use the wiki to detail the structure of the repository (its folders and files), how someone can commit, etc. What do you think?
Quote from: leomillert on 07/20/2015 07:31 pmI have a further suggestion: make all files public-domain. Specially all .ctl files.That way anyone can benefit from the work without any kind of bureaucracy.Public-domain helps the advancement of science.Completely agree - repo should be publicly browseable, with accounts only needed for people committing. And ignore my "Men In Black" bad joke...If you want me to set this up on the wiki server, let me know; would just take a few minutes.
This should also help a bit.http://ab-initio.mit.edu/wiki/index.php/Meep_Tutorial#Output_tips_and_tricksI also remember: when in doubt, ask the MEEP mailing list. http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss
...Quote from: Rodal on 07/21/2015 12:20 amAlso what is most needed is:1) People to write an RF Source routine for Meep to model a magnetron, and much simpler than that just to turn -off the source: something that Todd Desiato (WarpTech) asked some time ago, but remains to be done2) People to write a pre-processing routine to model perforated end-plates with different patterns of perforation, and/or the whole fustrum perforated as presently being tested by rfmwguy and SeeShells.I could possibly tackle (1) WRT turning off the source - I don't know what a magnetron does exactly, though I could find out.(2) sounds like it modifies the boundary conditions in an interesting manner - my lack of experience with CEM would be stretched here...