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#2100 by SeeShells on 21 Jan, 2016 23:33
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Not following too much, just jumped on for a sec. Learning FEKO and also doing some machining. Busy day.Here is a .gif from my first successful run of Tajmar's cavity. Successful? Well, at least the geometry is correct. The time domain images indicate that I need something more so I did not check resonance, nor did I run the copper model.
1) Thank you so much for going through all this trouble
This cavity slant height is 68.6 mm, big and small diameters 108.2 and 77 mm. There are a number of things I could try but the debug runs I've made tell me it is something other than increasing the length. Perhaps my modelled coupler and cavity feed dimensions are wrong. Wave guide is a WR 340 so I know its dimensions. I've attached a profile view of the cavity but note that because the picture of the real cavity includes an adjustable small end plate internal to the frustum cone, the height of the cone looks much shorter in my model than in the photograph. To see that the height is probably modelled correctly, you can compare the height of the cone to the height of the WR 340 waveguide which is 86.36 mm.
Has Tajmar hinted to anyone that he used a z-choke or iris inside his feed, and if so, at what point?
2) Since Tajmar did not provide any other information and unless somebody from the Tajmar team comes to NSF to give the needed information, perhaps SeeShells can provide the choke size she considered to use for her waveguide feed and you could use the smallest size she found. Why the smallest size? Because Tajmar's cavity is so tiny, and we know that in order to feed a cavity the entry hole dimension has to be much smaller than the length of the side wall being entered.
3/4" or 19mm would be the smallest I'd use anymore and you'll start disrupting the mode.
Shell
PS: Interesting paper on mode generation...
http://duepublico.uni-duisburg-essen.de/servlets/DerivateServlet/Derivate-14694/Final_Papers/GM0073-F.pdf
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#2101 by bprager on 22 Jan, 2016 00:15
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If it's not that serious though, by all means stick with PHP.
Go! (Pun intended.)
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#2102 by spupeng7 on 22 Jan, 2016 00:28
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A map :-)
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#2103 by Rodal on 22 Jan, 2016 01:23
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Yang calculated all the forces, including the side forces on the conical walls (see attachment below).
It is incorrect to conclude that Yang calculated a force based on only the forces at each end, since she did include the effect of the forces on the side walls.
That is not "the mistake" that Yang made.
I did not say she only calculated forces on each end plate or end wall. What I said was "each direction". Her mistake was in subtracting two similar big numbers each with numeric error.
PROOF that YANG's CALCULATED NET FORCE IS NOT THE RESULT OF LOSS OF SIGNIFICANCE ERROR DUE TO SUBTRACTING TWO NUMBERS
User TellMeAgain has posted that Prof. Yang's calculation for the EM Drive force is a "mistake in subtracting two similar big numbers each with numeric error."
Such an error is well known as the "Loss of significance" error arising from subtracting two numbers. Loss of significance is an effect in calculations using floating-point arithmetic. It occurs when an operation on two numbers increases relative error substantially more than it increases absolute error, for example in subtracting two nearly equal numbers (known as catastrophic cancellation).
Since TellMeAgain posits that the calculated anomalous force on the EM Drive should be zero (per conservation of momentum in Maxwell's equations), it follows that user TellMeAgain is positing that Prof. Yang's calculated force is an erratic number instead of being a perfect zero.
https://en.wikipedia.org/wiki/Loss_of_significance
It is straightforward to show that Yang's force calculation cannot be the result of loss of significance, because if it would be the result of loss of significance, the resulting force calculated by Yang (which according to TellMeAgain should be a perfect zero if loss of signficance would not be present) should be an erratic number, typically looking like this:
Instead, the thrust force calculated by Prof. Yang behaves smoothly and it is proportional to the Power, as shown in the pictures attached below. Not only does the force calculated by Prof. Yang increase smoothly with power, instead of behaving erratically, but in other of her publications she shows how the force is larger for certain modes like TE012 that have a larger Q and smaller for modes with lower Q, hence the calculated force is also a function of mode shape and Q. All of these characteristics show that the calculated force of Prof. Yang cannot possibly be the result of loss of significance.
Hence it is immediately obvious to those knowledgeable of numerical analysis that Prof. Yang's calculated force cannot be the result of loss of significance.
Reference:
Chin. Phys. B Vol. 22, No. 5 (2013) 050301
Prediction and experimental measurement of the electromagnetic thrust generated by a microwave thruster system
Yang Juan(杨涓)†, Wang Yu-Quan(王与权), Ma Yan-Jie(马艳杰), Li Peng-Fei(李鹏飞), Yang Le(杨乐), Wang Yang(王阳), and He Guo-Qiang(何国强)
__________
(*) In these messages https://forum.nasaspaceflight.com/index.php?topic=39004.msg1481202#msg1481202 and https://forum.nasaspaceflight.com/index.php?topic=39004.msg1481208#msg1481208 I show why Prof. Yang's calculated force is not zero. It is not zero because she calculates exactly what she says she calculates: the Maxwell stress tensor components, and the net force that results from integrating Maxwell's stress tensor over the surface area is not zero, because it must satisfy conservation of momentum, and to satisfy conservation of momentum it has to be balanced by the forces resulting from the time differential of the Poynting vector (which is not zero in the transient regime of the EM Drive, with the magnetron on ) and those resulting from electric surface charges and currents (if present at the metal walls of the EM Drive). It is straigthtforward to show that with the magnetron on, and certainly during the transient regime, the Poynting vector must increase nonlinearly with time and therefore that its derivative with respect to time cannot be zero, therefore the force due to the Poynting vector rate must be balanced by a non-zero net force (from the Maxwell stress tensor), so that all the terms in the conservation of momentum equation balance each other so that momentum is conserved, and such that there is no net self-acceleration in the EM Drive according to Maxwell's laws.
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#2104 by Tellmeagain on 22 Jan, 2016 01:52
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Yang calculated all the forces, including the side forces on the conical walls (see attachment below).
It is incorrect to conclude that Yang calculated a force based on only the forces at each end, since she did include the effect of the forces on the side walls.
That is not "the mistake" that Yang made.
I did not say she only calculated forces on each end plate or end wall. What I said was "each direction". Her mistake was in subtracting two similar big numbers each with numeric error.
PROOF that YANG's CALCULATED NET FORCE IS NOT THE RESULT OF LOSS OF SIGNIFICANCE ERROR DUE TO SUBTRACTING TWO NUMBERS
User TellMeAgain has posted that Prof. Yang's calculation for the EM Drive force is a "mistake in subtracting two similar big numbers each with numeric error."
Such an error is well known as the "Loss of significance" error arising from subtracting two numbers. Loss of significance is an effect in calculations using floating-point arithmetic. It occurs when an operation on two numbers increases relative error substantially more than it increases absolute error, for example in subtracting two nearly equal numbers (known as catastrophic cancellation).
Since TellMeAgain posits that the calculated anomalous force on the EM Drive should be zero (per conservation of momentum in Maxwell's equations), it follows that user TellMeAgain is positing that Prof. Yang's calculated force is an erratic number instead of being a perfect zero.
https://en.wikipedia.org/wiki/Loss_of_significance
It is straightforward to show that Yang's force calculation cannot be the result of loss of significance, because if it would be the result of loss of significance, the resulting force calculated by Yang (which according to TellMeAgain should be a perfect zero if loss of signficance would not be present) should be an erratic number, typically looking like this:
Instead, the thrust force calculated by Prof. Yang behaves smoothly and it is proportional to the Power, as shown in the pictures attached below. Not only does the force calculated by Prof. Yang increase smoothly with power, instead of behaving erratically, but in other of her publications she shows how the force is larger for certain modes like TE012 that have a larger Q and smaller for modes with lower Q, hence the calculated force is also a function of mode shape and Q. All of these characteristics show that the calculated force of Prof. Yang cannot possibly be the result of loss of significance.
Hence it is immediately obvious to those knowledgeable of "catastrophic cancellation due to loss of significance" that Prof. Yang's calculated force cannot be the result of loss of significance.
Reference:
Chin. Phys. B Vol. 22, No. 5 (2013) 050301
Prediction and experimental measurement of the electromagnetic thrust generated by a microwave thruster system
Yang Juan(杨涓)†, Wang Yu-Quan(王与权), Ma Yan-Jie(马艳杰), Li Peng-Fei(李鹏飞), Yang Le(杨乐), Wang Yang(王阳), and He Guo-Qiang(何国强)
__________
(*) In these messages https://forum.nasaspaceflight.com/index.php?topic=39004.msg1481202#msg1481202 and https://forum.nasaspaceflight.com/index.php?topic=39004.msg1481208#msg1481208 I show why Prof. Yang's calculated force is not zero. It is not zero because she calculates exactly what she says she calculates: the Maxwell stress tensor components, and the net force that results from integrating Maxwell's stress tensor over the surface area is not zero, because it must satisfy conservation of momentum, and to satisfy conservation of momentum it has to be balanced by the forces resulting from the time differential of the Poynting vector (which is not zero in the transient regime of the EM Drive, with the magnetron on ) and those resulting from electric surface charges and currents (if present at the metal walls of the EM Drive). It is straigthtforward to show that with the magnetron on, and certainly during the transient regime, the Poynting vector must increase nonlinearly with time and therefore that its derivative with respect to time cannot be zero, therefore the force due to the Poynting vector rate must be balanced by a non-zero net force (from the Maxwell stress tensor), so that all the terms in the conservation of momentum equation balance each other so that momentum is conserved, and such that there is no net self-acceleration in the EM Drive according to Maxwell's laws.
Dr. Rodal,
I do not agree with your analysis. I keep an empty reply here so that I can fill in contents tonight.
[update]
Your white-noise-like picture assumed ergodic property of the erratic number (here we are talking about the erratic number resulted from subtracting two big numbers), which may not be the case of Yang's simulation. Their paper (the [16] reference of the paper you showed, which can be googled with the follow chinese characters, 工质微波推进的推力转换机理与性能计算分析 杨涓 杨乐 未雨 ) stated:
“..., assuming the material was brass, according to the cavity dimensions shown in table 1, under the condition that the cavity is filled with air, with the given boundary conditions, we used three dimensional self-adaptive grid assignment method to divide (the cavity) into 69549 vertex , 50088 units, and we used finite element analysis method to discretize and numerically solve the Maxwell equations...”
This quotation is translated from the red line enclosed text of the shown screen shot of their paper below. It clearly stated the simulation settings. It is very likely that the erratic number is a function of the conditions and the simulation settings (specifically, a function of these 69549 vertex , 50088 units). That said, given that the EM system is linear, it ensured the erratic number is a monotonic function of the input power (it might be linear/square/sqrt or other monotonic functions). To get a white-noise-like erratic number, we need at least try random number of vertex and units. For example, for power=40W, we use 69549 vertex. for power=80W, we use 71345 (I made it) vertex; for power = 120, we use 70187 vertex... etc. Otherwise we can not assume the erratic number process is ergodic.
In summary, It is questionable for you to assume that a linear relationship between predicted force and power ensures it is not caused by erratic number.
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#2105 by Rodal on 22 Jan, 2016 02:11
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..
I look forward to your reply, since it is A) important to understand how can you possibly know, from her work, that Prof. Yang calculated force is a mistake due to subtracting large numbers, B) what is the mathematical justification for your conclusion and C) and it is important to understand Prof. Yang's calculations because she claims the largest experimental measurements and she is just solving Maxwell's equations numerically.
Dr. Rodal,
I do not agree with your analysis. I keep an empty reply here so that I can fill in contents tonight.
I am particularly interested in what you are stating because my specialty is in numerical analysis and the plots of force vs power shown by Prof Yang, don't look like the results of loss of significance, in my experience. -
#2106 by RFPlumber on 22 Jan, 2016 02:12
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This is definitely a NEW (1/21/16) Russian video about EMDrive, nothing other than a chat. Perhaps a Russian language reader can summarize this for us. Part of the video description translates to:
Shestopalov Anatoly Ivanov and Mikhail Y. after the workshop ( discussions and talks on the sidelines )
Report Ivanov MJ , Mamayev VK, Serov YL, Yanovsky LS " Combustion and detonation
<Url skipped>
The guy in the camera is apparently some well-known figure in the field of jet engines / propulsion (this interview is shortly after his presentation about “The physics of burning and detonation of jet chemical and nuclear low energy fuel”). The guy behind the camera is basically making a case for him to take a look at the work of A. Kushelev, who appears to be some Russian solo researcher / DIY-er and who (according to the guy behind the camera) had successfully demonstrated “EmDrive” back in 1992. The discussion starts with the interviewer giving the history of EmDrive-like research beginning with some Russian guy back in 1957 working on these types of engines, then Kushelev demonstrating his experiment in 1992, then Shawyer doing it recently and successfully convincing NASA to take a look (very true
), and whether there is going to be any interest to this kind of propulsion from major players. The guy in the camera then explains how for the next 5-10-20 years the current jet technology is likely to stay basically the same, with possible changes to incorporate low-energy nuclear reactions, and then the next milestone is going to be engines based on micro-leptons (?) produced as a result of fast deceleration of either ions or neutrons, and that there already exist experimental engines running on this principle, which does not contradict any existing physics. As for EmDrive-like technology, he is saying it is too far away and he’s not ready to discuss and basically doesn’t have much to say about it. The interviewer then proceeds to speculate how “ether” must be impacting some geological formations… Then eventually goes back to Kushelev work asking the guy in the camera to take a look.
Kushelev is the one posting the first and only comment to this video, where he thanks the guy behind the camera for this interview which, he suggest, may radically change the course of history.
No comments, but it does look like people started fooling around with microwave oven magnetrons as back as 1992…
EDIT: link to that presumably 1992-dated test removed per this: http://forum.nasaspaceflight.com/index.php?topic=39004.msg1481471#msg1481471
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#2107 by dicefirst on 22 Jan, 2016 02:27
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This is definitely a NEW (1/21/16) Russian video about EMDrive, nothing other than a chat. Perhaps a Russian language reader can summarize this for us. Part of the video description translates to:
Shestopalov Anatoly Ivanov and Mikhail Y. after the workshop ( discussions and talks on the sidelines )
Report Ivanov MJ , Mamayev VK, Serov YL, Yanovsky LS " Combustion and detonation
This video contains zero useful information. I feel dumber just from watching it. The interviewer is alien-believing conspiracy theorist, likely geologist or hydrogeologist by training. The interviewee is a PhD with research focus on propulsion who isn't particularly knowledgeable about emdrive and related theories and doesn't appear to want to be there. His papers: https://translate.google.com/translate?hl=en&sl=ru&tl=en&u=http%3A%2F%2Fwww.mathnet.ru%2Frus%2Fperson33079
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#2108 by dicefirst on 22 Jan, 2016 02:41
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Quote
No comments, but it does look like people started fooling around with microwave oven magnetrons as back as 1992…
Here are the people who started fooling around with magnetrons in 1992 (Kushelev guy mentioned in the video):
http://nanoworld.narod.ru/
click at your own risk
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#2109 by rfmwguy on 22 Jan, 2016 02:58
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Thanks for summary of this video...had no idea other than it was about emdrive. Seems russia has their share of strange personalities as well. I try and track anything new and share it here. Most emdrive chatter is going on outside the usa...find that interesting.
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#2110 by TheTraveller on 22 Jan, 2016 05:51
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Thanks for summary of this video...had no idea other than it was about emdrive. Seems russia has their share of strange personalities as well. I try and track anything new and share it here. Most emdrive chatter is going on outside the usa...find that interesting.
Russian EmDrive forum. Google does a passable job at translation:
http://www.sciteclibrary.ru/cgi-bin/yabb2/YaBB.pl?num=1447076750/0
Member Prtovich_Tot claims to have build an EmDrive and measured thrust. -
#2111 by TheTraveller on 22 Jan, 2016 06:58
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Progress report.
Frustum forming hoops have finally arrived. Not the quality I expected, see the non cleaned up welded joints but they will do.
Also have attached my 1st very manual test setup, which should allow me to explore the frustum resonance, Q, nearby modes, bandwidth and others.
If this simple setup gens thrust, well you will know it here 1st. However that is NOT my objective. I need to get very up close and personal with this frustum, how it behaves and how to obtain a stable (which others have shared is NOT easy to do) high Q TE013 excited mode.
Finger tips and palm still sore from the copper cuts, maybe 1 week or so to be able to try to build the frustum again.
Should add there is no VNA in the drawing as I need to know how the frustum reacts to my amp's output and how the frustum reacts to the 1/2 current loop when serious power is applied. Also when this goes real time best freq tracking and driving the rotary table there will be no VNA involved.
To restate my objective, which is NOT to prove the EmDrive works. Take it as read it works.
To measure the real time relationship, during acceleration, between power supply energy consumed, raw Rf amp energy output, forward Rf amp energy into the frustum, delivered kinetic energy driving rotary table angular acceleration & changes that happen to the frustum during acceleration.
As I stated earlier: 2016 is going to be a very interesting year for EmDrive supporters, skeptics & deniers. It will be interesting to watch as people move from skeptics and deniers to supporters or just disappear as the experimental data destroys any ability to maintain their denial.
Phil
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#2112 by RFPlumber on 22 Jan, 2016 07:08
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This is definitely a NEW (1/21/16) Russian video about EMDrive, nothing other than a chat. Perhaps a Russian language reader can summarize this for us. Part of the video description translates to:
Shestopalov Anatoly Ivanov and Mikhail Y. after the workshop ( discussions and talks on the sidelines )
Report Ivanov MJ , Mamayev VK, Serov YL, Yanovsky LS " Combustion and detonation
<Url skipped>
... The guy behind the camera is basically making a case for him to take a look at the work of A. Kushelev, who appears to be some Russian solo researcher / DIY-er and who (according to the guy behind the camera) had successfully demonstrated “EmDrive” back in 1992 (Btw, this turns out to be true. Here’s the link:
<skip>
No comments, but it does look like people started fooling around with microwave oven magnetrons as back as 1992…
And doing some due diligence / curiosity -driven follow-up search on Mr. A. Kushelev quickly turns out that he is basically a rip-off artist, potentially with some mental issues, albeit a rather unusual one as he is luring his unsavvy "investors" in with ongoing (for at least the last 15 years) promises of new energy sources based on some colorful combinations of gem stones, ancient jewelry, millimeter wave guides, and Q factor values at resonance... It is not clear whether he is making it all up on the fly or he actually believes in his claims.
Hence there is a good chance the link to that presumably 1992 EmDrive test video is actually fake. I will be removing it.
Another important take away is there indeed happen to be some uniquely delusional people out there (who at the same time know very well what the Q factor is and how to use a VNA).
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#2113 by Chrochne on 22 Jan, 2016 08:09
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This is definitely a NEW (1/21/16) Russian video about EMDrive, nothing other than a chat. Perhaps a Russian language reader can summarize this for us. Part of the video description translates to:
Shestopalov Anatoly Ivanov and Mikhail Y. after the workshop ( discussions and talks on the sidelines )
Report Ivanov MJ , Mamayev VK, Serov YL, Yanovsky LS " Combustion and detonation
<Url skipped>
... The guy behind the camera is basically making a case for him to take a look at the work of A. Kushelev, who appears to be some Russian solo researcher / DIY-er and who (according to the guy behind the camera) had successfully demonstrated “EmDrive” back in 1992 (Btw, this turns out to be true. Here’s the link:
<skip>
No comments, but it does look like people started fooling around with microwave oven magnetrons as back as 1992…
And doing some due diligence / curiosity -driven follow-up search on Mr. A. Kushelev quickly turns out that he is basically a rip-off artist, potentially with some mental issues, albeit a rather unusual one as he is luring his unsavvy "investors" in with ongoing (for at least the last 15 years) promises of new energy sources based on some colorful combinations of gem stones, ancient jewelry, millimeter wave guides, and Q factor values at resonance... It is not clear whether he is making it all up on the fly or he actually believes in his claims.
Hence there is a good chance the link to that presumably 1992 EmDrive test video is actually fake. I will be removing it.
Another important take away is there indeed happen to be some uniquely delusional people out there (who at the same time know very well what the Q factor is and how to use a VNA).
Well it is also importnat to mention that you also did not reached necessary levels of the Q in your build. I am no engineer, but from the comments I gathered, and to my suprise very positive response from Dr. Rodal on your test results - even when there are so many flaws in your build - when compared to the other builders.
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#2114 by TheTraveller on 22 Jan, 2016 08:35
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Progress report.
Further test setup and testing goals.
There will be a Faraday Shield around the entire EmDrive plus the double sided copper pcb material on top of the scale and between the shielded EmDrive & the scale.
Will also be using a balance beam setup and compare the direct scale data with the balance beam data.
All this is just precursor to the continual acceleration on the rotary test rig.
So will have thrust data from 3 different test setups. Will be very hard for anyone to deny all 3 test setups.
Also with my test setup, will be able to show thrust varying as Rf forward power is varied and as freq is altered to -3dB cutoff points and beyond.
As far as I know, no one has ever done this or if they have, it has never been published.
Phil -
#2115 by Tellmeagain on 22 Jan, 2016 11:57
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Well it is also importnat to mention that you also did not reached necessary levels of the Q in your build. I am no engineer, but from the comments I gathered, and to my suprise very positive response from Dr. Rodal on your test results - even when there are so many flaws in your build - when compared to the other builders.
I think RFPlumber's experiment is much better than most other experiments. Quality-wise, I would rank the experiments this way, smaller number better, in their current settings,
1. RFPlumber
2. Emmett Brown
3. EW NASA
4. Tajmar
5. RFMWguy
If EW can remove their ground loop, and RFMWguy change to horizontal movement then:
1. EW NASA without ground loop
2. RFPlumber
3. Emmett Brown
4. RFMWguy horizontal
5. Tajmar
If Tajmar remove his ground loop, then
1. EW NASA without ground loop
2. RFPlumber
3. Emmett Brown
4. Tajmar without ground loop
5. RFMWguy horizontal
I have not seen See-shell's settings so did not place her experiment. -
#2116 by Rodal on 22 Jan, 2016 12:39
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...
Dr. Rodal,
I do not agree with your analysis. I keep an empty reply here so that I can fill in contents tonight.
[update]
Your white-noise-like picture assumed ergodic property of the erratic number (here we are talking about the erratic number resulted from subtracting two big numbers), which may not be the case of Yang's simulation. Their paper (the [16] reference of the paper you showed, which can be googled with the follow chinese characters, 工质微波推进的推力转换机理与性能计算分析 杨涓 杨乐 未雨 ) stated:
“..., assuming the material was brass, according to the cavity dimensions shown in table 1, under the condition that the cavity is filled with air, with the given boundary conditions, we used three dimensional self-adaptive grid assignment method to divide (the cavity) into 69549 vertex , 50088 units, and we used finite element analysis method to discretize and numerically solve the Maxwell equations...”
This quotation is translated from the red line enclosed text of the shown screen shot of their paper below. It clearly stated the simulation settings. It is very likely that the erratic number is a function of the conditions and the simulation settings (specifically, a function of these 69549 vertex , 50088 units). That said, given that the EM system is linear, it ensured the erratic number is a monotonic function of the input power (it might be linear/square/sqrt or other monotonic functions). To get a white-noise-like erratic number, we need at least try random number of vertex and units. For example, for power=40W, we use 69549 vertex. for power=80W, we use 71345 (I made it) vertex; for power = 120, we use 70187 vertex... etc. Otherwise we can not assume the erratic number process is ergodic.
In summary, It is questionable for you to assume that a linear relationship between predicted force and power ensures it is not caused by erratic number.
Mr. Li, to recapitulate: you stated that Prof. Yang's calculated force for the EM Drive is the result of she making the mistake of subtracting two similar big numbers, and that her result is numeric error.
You have now stated this in three separate posts, and you have never supported this charge. It is amazing to me that you made this statement as if it would be a fact: others would have instead stated "In my humble opinion I suppose that perhaps Prof. Yang's calculation of force is an error resulting from the subtraction of two numbers". Instead you post this repeatedly as if it would be a fact, instead of what it appears to be: a not-well-thought-out guess on your part, because it is apparent that you have not had access to information as to what is the floating point precision used by Prof. Yang. The situation is even worse because you repeatedly fail to make any coherent argument as to why her calculated force must be the result of subtracting two numbers.
You state "Her mistake was in subtracting two similar big numbers each with numeric error". Why do you state "two big numbers"? What makes her force numbers "big"? Big compared to what? How big are the numbers she is subtracting specifically?
You only advance the idea that her calculated force is the result of numerical error, you never bring up a single fact to support your statement. When faced with having to respond to the fact that her calculated force vs. power shows a well behaved, smooth linear response, instead of bringing up any facts to support your statement against Yang's calculation, instead you shift the conversation to the image I posted as an example of numeric error by stating "Your white-noise-like picture assumed ergodic property of the erratic number (here we are talking about the erratic number resulted from subtracting two big numbers), which may not be the case of Yang's simulation."
You will not be able to support your up-to-now unsupported statement about Yang's calculated force by shifting the conversation to an example of numeric error readily obtained from Wikipedia to show to the readers what loss of signficance errors look like, or by having a discussion about ergodicity (which I never assumed) or whether white-noise is involved (which I did not state either). (In my experience computational errors in Finite Element analysis are more likely to display fractal pink-noise properties). Being an expert in Finite Element analysis, your discussion about vertex and number of nodes, as somehow translating to a well behaved error that will grow linearly with power does not make sense.
Instead it is up to you to defend your own statements that Yang's force is a result ofQuote from: TellMeAgainthe net result is often just numeric error. An easy example is to measure your weight twice. The first time you measure your weight when standing on the scale upright. The second time you measure your weight standing on your hands. Now subtract the two numbers. What is the net weight of 10 or 100 micro Newton or even 0.1 pounds you get? The Yang simulation had this mistake.
Those are your own words. You are the one that states that her calculated force is numeric error, and you give the example of a net resultant weight of subtracting your weight measured two times as resulting in 10 or 100 micro Newton.
Now, it is evident to the reader that the calculated force vs. power presented by Prof. Yang do not at all look like a numeric error, they do not at all look like the result of subtracting the weight two times.
It was careless, on your part to state that "Her (Yang's) mistake was in subtracting two similar big numbers each with numeric error."
Unless you provide proof of your yet-unsupported charge against Prof. Yang's force calculation, it appears to me that you were not careful in the way you attacked her calculation (instead of stating "In my humble opinion I suppose that she may have made an error"), and that when shown that you are unable to support your charges you feel compelled to save face by shifting the conversation elsewhere.
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#2117 by Tellmeagain on 22 Jan, 2016 13:00
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...
Dr. Rodal,
I do not agree with your analysis. I keep an empty reply here so that I can fill in contents tonight.
[update]
Your white-noise-like picture assumed ergodic property of the erratic number (here we are talking about the erratic number resulted from subtracting two big numbers), which may not be the case of Yang's simulation. Their paper (the [16] reference of the paper you showed, which can be googled with the follow chinese characters, 工质微波推进的推力转换机理与性能计算分析 杨涓 杨乐 未雨 ) stated:
“..., assuming the material was brass, according to the cavity dimensions shown in table 1, under the condition that the cavity is filled with air, with the given boundary conditions, we used three dimensional self-adaptive grid assignment method to divide (the cavity) into 69549 vertex , 50088 units, and we used finite element analysis method to discretize and numerically solve the Maxwell equations...”
This quotation is translated from the red line enclosed text of the shown screen shot of their paper below. It clearly stated the simulation settings. It is very likely that the erratic number is a function of the conditions and the simulation settings (specifically, a function of these 69549 vertex , 50088 units). That said, given that the EM system is linear, it ensured the erratic number is a monotonic function of the input power (it might be linear/square/sqrt or other monotonic functions). To get a white-noise-like erratic number, we need at least try random number of vertex and units. For example, for power=40W, we use 69549 vertex. for power=80W, we use 71345 (I made it) vertex; for power = 120, we use 70187 vertex... etc. Otherwise we can not assume the erratic number process is ergodic.
In summary, It is questionable for you to assume that a linear relationship between predicted force and power ensures it is not caused by erratic number.
Mr. Li, to recapitulate: you stated that Prof. Yang's calculated force for the EM Drive is the result of she making the mistake of subtracting two similar big numbers, and that her result is numeric error.
You have now stated this in three separate posts, and you have never supported this charge. It is amazing to me that you made this statement as if it would be a fact: others would have instead stated "In my humble opinion I suppose that perhaps Prof. Yang's calculation of force is an error resulting from the subtraction of two numbers". Instead you post this repeatedly as if it would be a fact, instead of what it appears to be: a wild guess on your part, because it is apparent that you have not had access to information as to what is the level of floating point precision used by Prof. Yang. The situation is even worse because you repeatedly fail to make any coherent argument as to why her calculated force must be the result of subtracting two numbers.
You state "Her mistake was in subtracting two similar big numbers each with numeric error". Why do you state "two big numbers"? What makes her force numbers "big"? Big compared to what? How big are the numbers she is subtracting specifically?
You only advance the idea that her calculated force is the result of numerical error, you never bring up a single fact to support your statement. When faced with having to respond to the fact that her calculated force vs. power shows a well behaved, smooth linear response, instead of bringing up any facts to support your statement against Yang's calculation, instead you shift the conversation to the image I posted as an example of numeric error by stating "Your white-noise-like picture assumed ergodic property of the erratic number (here we are talking about the erratic number resulted from subtracting two big numbers), which may not be the case of Yang's simulation."
You will not be able to support your up-to-now unsupported statement about Yang's calculated force by shifting the conversation to an example of numeric error readily obtained from Wikipedia to show to the readers what loss of signficance errors look like, or by having a discussion about ergodicity (which I never assumed) or whether white-noise is involved (which I did not state either). (In my experience computational errors in Finite Element analysis are more likely to display fractal pink-noise properties). Being an expert in Finite Element analysis, your discussion about vertex and number of nodes, as somehow translating to a well behaved error that will grow linearly with power does not make sense.
Instead it is up to you to defend your own statements that Yang's force is a result ofQuote from: TellMeAgainthe net result is often just numeric error. An easy example is to measure your weight twice. The first time you measure your weight when standing on the scale upright. The second time you measure your weight standing on your hands. Now subtract the two numbers. What is the net weight of 10 or 100 micro Newton or even 0.1 pounds you get? The Yang simulation had this mistake.
Those are your own words. You are the one that states that her calculated force is numeric error, and you give the example of a net resultant weight of subtracting your weight measured two times as resulting in 10 or 100 micro Newton.
Now, it is evident to the reader that the calculated force vs. power presented by Prof. Yang do not at all look like a numeric error, they do not at all look like the result of subtracting the weight two times.
It was careless, bordering on reckless, on your part to state that "Her (Yang's) mistake was in subtracting two similar big numbers each with numeric error."
Unless you provide proof of your yet-unsupported charge against Prof. Yang's force calculation, it appears to me that you were not careful in the way you attacked her calculation (instead of stating "In my humble opinion I suppose that she may have made an error"), and that when shown that you are unable to support your charges you feel compelled to save face by shifting the conversation elsewhere.
Oh, sorry, In my reply #2014 I disagreed with your analysis or "PROOF that YANG's CALCULATED NET FORCE IS NOT THE RESULT OF LOSS OF SIGNIFICANCE ERROR DUE TO SUBTRACTING TWO NUMBERS" (originally capitalized) and was not about my proof that her net force was the result of subtracting two big numbers. For the later, I do not want to muddy the water now.
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#2118 by Rodal on 22 Jan, 2016 13:23
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Progress report.
I don't understand the purpose of making this prediction about <<2016 is going to be a very interesting year for EmDrive supporters, skeptics & deniers. It will be interesting to watch as people move from skeptics and deniers to supporters or just disappear as the experimental data destroys any ability to maintain their denial.>>
...
As I stated earlier: 2016 is going to be a very interesting year for EmDrive supporters, skeptics & deniers. It will be interesting to watch as people move from skeptics and deniers to supporters or just disappear as the experimental data destroys any ability to maintain their denial.
Phil
most people in our 21st century (and certainly technically-sophisticated people at NSF) don't believe in Nostradamus-like people predicting the future
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#2119 by JaimeZX on 22 Jan, 2016 13:33
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Guys, I don't know how helpful this is, but I asked my Chinese (civil) engineer cousin if she could translate the JPG. Here's what she gave me:
In the Microwave Radiation Thruster, as demonstrated in the Figure 1, the direction of the electric field at the wall surface is normal to the wall surface, the direction of the of the magnetic field is perpendicular to the normal of the wall surface. Taking into account of the Formula (2), in the best resonant state, the input microwave energy in to the resonant device would be amplified Q times, as well as the values of the E ^ 2, H ^ 2, both of them would be amplified Q times, respectively, and thus the net axial thrust is:
Formula (13)
Where A1, A2, A3 are large end face area, small end face area, and the side wall surface area, respectively.
), and whether there is going to be any interest to this kind of propulsion from major players. The guy in the camera then explains how for the next 5-10-20 years the current jet technology is likely to stay basically the same, with possible changes to incorporate low-energy nuclear reactions, and then the next milestone is going to be engines based on micro-leptons (?) produced as a result of fast deceleration of either ions or neutrons, and that there already exist experimental engines running on this principle, which does not contradict any existing physics. As for EmDrive-like technology, he is saying it is too far away and he’s not ready to discuss and basically doesn’t have much to say about it. The interviewer then proceeds to speculate how “ether” must be impacting some geological formations… Then eventually goes back to Kushelev work asking the guy in the camera to take a look.