@Rodal - I'm not sure where you are getting the data indicating that Q varies by 3 orders of magnitude, perhaps a miscommunication somewhere. If your source is meep Harminv data, then the correct values as I recorded them at the time of the runs are: Q 87,830,861 Q 87,830,729 Q 5,068,251 Q 59,477,392where the first two were using, I believe, a shorter dipole antenna (29 mm) and driving with the previously determined resonance frequency to hone in on the actual cavity resonance frequency as model. It is very consistently 2.46316012E+009 Hz within kHz. The final two were from the model with drive frequency = 2.45 GHz and antenna length = 58 mm as used to generate the 2 Yang-Shell data sets uploaded to Google drive.
Quote from: Rodal on 07/23/2015 12:27 amQuote from: aero on 07/22/2015 11:50 pm...I wondered why that went quicker last night. Not quick but a little quicker. I guess you found out. Check it again, they are there now.I'm looking at the Yang/Shell Axial Antenna at Big Base case now: very unusual: the stress, and hence the force at the small base is practically zero. The stress at the big base is a central point stress from the antenna. Close inspection of this mode looks like another TM11 transverse magnetic mode but with drastically different amplitude.QUESTION1: was the mesh kept the same as in the previous csv Yang/Shell case, and you are sure this is the stress at the small base and not outside it?Most important: QUESTION2: did Meep give you a Q value for this case ?ThanksEverything about the run was identical except the antenna. The csv files are the same size aren't they? If something were changed likely they would change size. And really, the bases should be in the same place they were previously. I looked at this data set with HDFview. But note that the row numbers I gave you I had 1 added, to start at 1 like the csv matrices, instead of 0 as HDFview uses. If you also added 1, that would be the problem. The model skin is three matrix rows thick, adding an extra 1 would make the small base row be inside the skin.It was also the same 58 mm antenna centered quarter wavelength from the inside face of the big base but rotated 90 degrees to an axial orentation. Note that 1/4 wave length is only slightly more than half of 58 mm, so the end of the antenna near the big base was about 1.5 mm away from the base, and excited with ez component although hy would have been more natural.Q? Yea, Q was ridiculously high, like 60 million and the resonant frequency was like 2.463 GHz, which I ignored and made the run at 2.45 GHz.
Quote from: aero on 07/22/2015 11:50 pm...I wondered why that went quicker last night. Not quick but a little quicker. I guess you found out. Check it again, they are there now.I'm looking at the Yang/Shell Axial Antenna at Big Base case now: very unusual: the stress, and hence the force at the small base is practically zero. The stress at the big base is a central point stress from the antenna. Close inspection of this mode looks like another TM11 transverse magnetic mode but with drastically different amplitude.QUESTION1: was the mesh kept the same as in the previous csv Yang/Shell case, and you are sure this is the stress at the small base and not outside it?Most important: QUESTION2: did Meep give you a Q value for this case ?Thanks
...I wondered why that went quicker last night. Not quick but a little quicker. I guess you found out. Check it again, they are there now.
Quote from: aero on 07/23/2015 06:37 pm@Rodal - I'm not sure where you are getting the data indicating that Q varies by 3 orders of magnitude, perhaps a miscommunication somewhere. If your source is meep Harminv data, then the correct values as I recorded them at the time of the runs are: Q 87,830,861 Q 87,830,729 Q 5,068,251 Q 59,477,392where the first two were using, I believe, a shorter dipole antenna (29 mm) and driving with the previously determined resonance frequency to hone in on the actual cavity resonance frequency as model. It is very consistently 2.46316012E+009 Hz within kHz. The final two were from the model with drive frequency = 2.45 GHz and antenna length = 58 mm as used to generate the 2 Yang-Shell data sets uploaded to Google drive.aero, the information comes from your message quoted again below:Quote from: aero on 07/23/2015 01:18 amQuote from: Rodal on 07/23/2015 12:27 amQuote from: aero on 07/22/2015 11:50 pm...I wondered why that went quicker last night. Not quick but a little quicker. I guess you found out. Check it again, they are there now.I'm looking at the Yang/Shell Axial Antenna at Big Base case now: very unusual: the stress, and hence the force at the small base is practically zero. The stress at the big base is a central point stress from the antenna. Close inspection of this mode looks like another TM11 transverse magnetic mode but with drastically different amplitude.QUESTION1: was the mesh kept the same as in the previous csv Yang/Shell case, and you are sure this is the stress at the small base and not outside it?Most important: QUESTION2: did Meep give you a Q value for this case ?ThanksEverything about the run was identical except the antenna. The csv files are the same size aren't they? If something were changed likely they would change size. And really, the bases should be in the same place they were previously. I looked at this data set with HDFview. But note that the row numbers I gave you I had 1 added, to start at 1 like the csv matrices, instead of 0 as HDFview uses. If you also added 1, that would be the problem. The model skin is three matrix rows thick, adding an extra 1 would make the small base row be inside the skin.It was also the same 58 mm antenna centered quarter wavelength from the inside face of the big base but rotated 90 degrees to an axial orentation. Note that 1/4 wave length is only slightly more than half of 58 mm, so the end of the antenna near the big base was about 1.5 mm away from the base, and excited with ez component although hy would have been more natural.Q? Yea, Q was ridiculously high, like 60 million and the resonant frequency was like 2.463 GHz, which I ignored and made the run at 2.45 GHz.Again, in my post I was discussing your statement <<Q? Yea, Q was ridiculously high, like 60 million >>referring to the last run for Yang/Shell with the antenna oriented along the longitudinal x axisQ=60 million is 1,000 times greater than Q=60,000
If unable to model a loop antenna to excite TE modes, what could be done as the next step is to place the dipole antenna in the transverse direction near the small end, to be able to compare the two runs made for Yang/Shell with the dipole antenna at the big end.
Quote from: frobnicat on 07/23/2015 04:40 pmThis was discussed in thread 2, thing is for a "propulsive effect" of constant thrust it relies on a non stationary ever increasing current :http://forum.nasaspaceflight.com/index.php?topic=36313.msg1350655#msg1350655They also have a more recent paper called "Relativistic Engine Based on a Permanent Magnet" (from July 13, 2015). The link is: http://lib-arxiv-008.serverfarm.cornell.edu/pdf/1507.02897v1.pdf
This was discussed in thread 2, thing is for a "propulsive effect" of constant thrust it relies on a non stationary ever increasing current :http://forum.nasaspaceflight.com/index.php?topic=36313.msg1350655#msg1350655
...what do people think about reporting NULL results of experimenters ? ...
Remarkable paper. Does this paper suggest a new kind of thruster we could build in practice? or is this un-physical due to it assuming things like Terawatts or input power or some such?Because it sounds mechanically simple. So, where's the catch?
I just calculated Yang/Shell TM113 with my program:Q =45,039 Yang/Shell (copper) natural frequency for TM113 = 2.4941 GHzQ =50,175 rfmwguy/NSF-1701(copper) Used the following material properties:epsilon0 = 8.854187817*10^-12); mu0 = 0.999991(*copper*)*4*Pi*10^(-7);resistivity = 1.678*10^(-8)(*copper*);For using same material constants, I get If I use brass or bronze I will get a lower Q. For example, for:resistivity = 1.437*10^(-7) high strength brassgiving:Q= 15,391 (Yang/Shell) high strength brassQ= 17,146 (rfmwguy/NSF1701) high strength brass what material model are you using to get Q's in the millions? are you using the Drude model ?
____________PS: I edited my prior message, eliminating reference to the 60 million Q, as it appears that all the Q's from Meep runs are suspect.
Quote from: Rodal on 07/23/2015 02:36 pm...what do people think about reporting NULL results of experimenters ? ...I'm just a random person following this thread, but I have been waiting for kml's null tests to appear on the experimental results section of the wiki ever since kml reported his findings. It has been bothering me that nobody else seems to think kml's test is notable. I learned something new. We can alter the reading of a digital scale without touching it.
...Of course they are. There are no losses, not because of the material model, but because of the sampling resolution, (node separation). They are a valid indication of whether or not the cavity model will resonate but more than that it is hard to say. I use them for that purpose, interpreting high Q's as strong resonance of the model and low or no Q's to indicate low or no resonance at that frequency/antenna configuration as modelled. We have known for a long time that Q's in the millions are not realistic for room temperature cavities.
Of course they are. There are no losses, not because of the material model, but because of the sampling resolution, (node separation). They are a valid indication of whether or not the cavity model will resonate but more than that it is hard to say. I use them for that purpose, interpreting high Q's as strong resonance of the model and low or no Q's to indicate low or no resonance at that frequency/antenna configuration as modelled. We have known for a long time that Q's in the millions are not realistic for room temperature cavities.
{snip}I've found it interesting and keep coming back to the red flags in the tests. Air pressure=thrust vs Vacuum=small thrustThis is the 800 pound gorilla sitting in the middle of the lab and nobody wants to poke it. {snip}
Number of time steps, 6527 and total meep time = 13.054 time units.
Quote from: Rodal on 07/23/2015 06:15 pmNumber of time steps, 6527 and total meep time = 13.054 time units.Wow - got it - so we're showing an exponential growth of force on the large base for the Yang model, but we need to run a lot further in time to get where we want to be. Are these the forces output by meep or calculated by you afterward? Can you please summarize what you need for the force calculation / output?
3) aero has been outputting this information for the last 14 time slices (of the total of 320 time slices), the 6 fields for the Small Base and for the Big Base.
Quote from: b0nafide on 07/23/2015 08:10 pmQuote from: Rodal on 07/23/2015 02:36 pm...what do people think about reporting NULL results of experimenters ? ...I'm just a random person following this thread, but I have been waiting for kml's null tests to appear on the experimental results section of the wiki ever since kml reported his findings. It has been bothering me that nobody else seems to think kml's test is notable. I learned something new. We can alter the reading of a digital scale without touching it.Those early test results were confirmed to be the result of RFI affecting the scale, so they should be disregarded.The original design with an adjustable copper covered plunger on one end was not very RF tight. The current design with copper gaskets at each end is much better and most of the RFI issues since that change have been with the remote control transmitter and not the test unit.I am continuing to run test and collect data. I have been holding off on posting more test results until I am absolutely sure that the data is clean and not affected by RFI. I can say the vast majority of the test runs have shown no deviation from the thermal slope while RF is on. The few that did have either been confirmed or suspected as RFI related. Early indications are that a dielectric alone is not able to produce the effect.Here is an updated picture of the test rig with the 30W PA driven by an alinco DJ-G7T transciever in crossband repeat mode. The fan on the PA is not used during test runs. The new sample port location is on the left side.
2 questions:1) Should we document your present results as NULL in the Wiki or do you want us to wait?2) Have you "motivated" the EM Drive by tapping it or vibrating it? ==> Recall TheTraveller/Shawyer's conjecture that for EM Drive to register a force, it needs to be motivated by tapping it or vibrating it