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PostPosted: Sat Jul 21, 2012 1:52 am 
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R.Nkolo wrote:
MSimon wrote:
...
That is too bad because other than understanding the meaning of the symbols algebra is more than adequate for understanding physics ...


Newton did need calculus for his laws of motions.
Einstein had to understand newtonian Physics in order to take the laws of motion to another level.
Quantum mechanics uses differential equations and is relativistic(need Einstein).


Einstein also needed a deep conceptual -- and rigorous -- understanding of calculus to realize that newtons laws of motion alone are sufficient to explain gravity if the value of pi changes near a point of mass.

(and by value of pi I mean the ratio of circumference to diameter, ofcourse, not the constant pi which is defined in a Cartesian space)

( and by that I mean the rate of change in circumference relative to the rate of change in radius. Like I said, deep and rigorous. Also, Einstein flunked algebra... )


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PostPosted: Sat Jul 21, 2012 3:00 pm 
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happyjack27 wrote:

Einstein also needed a deep conceptual -- and rigorous -- understanding of calculus to realize that newtons laws of motion alone are sufficient to explain gravity if the value of pi changes near a point of mass.

(and by value of pi I mean the ratio of circumference to diameter, ofcourse, not the constant pi which is defined in a Cartesian space)

( and by that I mean the rate of change in circumference relative to the rate of change in radius. Like I said, deep and rigorous. Also, Einstein flunked algebra... )

When he was very young, Einstein's parents worried that he had a learning disability because he was very slow to learn to talk. (He also avoided other children and had extraordinary temper tantrums.) When he started school, he did very well-he was a creative and persistent problem-solver-but he hated the rote, disciplined style of the teachers at his Munich school, and he dropped out when he was 15. Then, when he took the entrance examination for a polytechnic school in Zurich, he flunked. (He passed the math part, but failed the botany, zoology and language sections.) Einstein kept studying and was admitted to the polytechnic institute the following year, but even then he continued to struggle: His professors thought that he was smart but much too pleased with himself, and some doubted that he would graduate. He did, but not by much-which is how the young physicist found himself working in the Swiss Patent Office instead of at a school or university. but he wasvery good at"math"


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PostPosted: Sat Jul 28, 2012 6:47 am 
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Jim did a last data dump before the JPC on Monday. This last week they had their highest thrusts to date, 20uN, and with much less power of the last highest thrusts at 10uN--just 100W. All this was with S/N >10.

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PostPosted: Sat Jul 28, 2012 9:09 am 
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That's comparable to the power-to-thrust ratio of a DFP engine.


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PostPosted: Sat Jul 28, 2012 9:43 am 
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Yup, Jim's making strong progress. I'm curious to see how much thrust He can generate out of his latest rig.


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PostPosted: Sat Jul 28, 2012 4:18 pm 
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How does the latest results compare with theory?

I have to say, the implications of success on humanity are difficult to overstate. I am watching with great interest.[/quote]

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PostPosted: Sat Jul 28, 2012 7:20 pm 
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My mistake. I should have noted there was 100W running but only about 1W dissipated. They were using a laser IR thermometer to monitor and there was only a degree or so heating.

I haven't seen a comparison to theory. Jim has been preparing for AIAA's JPC this last week and hasn't been doing so much lab work. Heidi is the one who generated these results by manually tuning a variable inductor. Unfortunately she smoked the amp she was using so only got the stated 7 runs done.

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PostPosted: Sat Jul 28, 2012 8:56 pm 
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93143 wrote:
That's comparable to the power-to-thrust ratio of a DFP engine.


dilluted fusion propulsion???


so... so whats the impediment exactly to increase the power and get higher thrust?

what is the roadmap right now for Mach Effect to get a visible "frick all skeptics" demonstrator?


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PostPosted: Sat Jul 28, 2012 9:12 pm 
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Jim has only said that the focus right now is to match the electrical and mechanical resonances in order to promote higher thrust. He and Heidi only just begun this and Heidi generated thrusts twice as high as any Jim has in all these years. Note too, Jim is on vacation until late September, so we normally don't see activity this time of year at all.

There is a little skuttlebutt that better ceramics are on the table. IIRC, the PZT Jim is using has a k value just below 1,000 and the PMN-PT they're considering has a k value up around 25,000. I believe M-E production scales quadratically with k so all else the same, we're looking at commercial grade thrusts expected from such a device. Of course, all else is not the same when you make such changes. PZT is a piezo-active material and PMN-PT is electrostrictive. To the best of my knowledge they can't even use the same design thruster.

Sorry that's not an intellectually satisfying answer but it is after all summertime and these two PhD's are both educators. And, Jim hasn't been writing much this last week. He's presenting to AIAA on Monday.

If anyone here is going to JPC, I'd sure love a vid of the presentation. . .

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PostPosted: Sat Aug 04, 2012 8:37 am 
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Woodward made his deadline so his book will be published by Springer in November. If anyone here fails to immediately order a copy, it will rain frogs on his house for a month.

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PostPosted: Sat Aug 04, 2012 11:08 am 
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GIThruster wrote:
Woodward made his deadline so his book will be published by Springer in November. If anyone here fails to immediately order a copy, it will rain frogs on his house for a month.


... perhaps not the best tactic... like so many other places we could *really* use some rain around here... and frogs have a high moisture content...


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PostPosted: Sun Aug 05, 2012 3:08 pm 
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ltgbrown wrote:
How does the latest results compare with theory?

I have to say, the implications of success on humanity are difficult to overstate. I am watching with great interest.
[/quote]

Per an e-mail from Dr. Woodward's July 01, 2012 weekly report we have the following from Jim on this topic:

"Why would I say that it's the real deal when this signal is orders of magnitude smaller than the predictions suggest it should be? Because we've found these past two weeks that those predictions are wrong. Heidi and I have been working now for a while on the JPC paper that will go with the presentation I'll do at that conference in about a month. While working on the theory section of that paper, I decided to include a section on explicit acceleration dependence of Mach effects. While writing that out, I decided to derive the prediction based on full acceleration dependence -- rather than doing the prediction the way it's been done for years. It turns out that this calculation is not difficult at all. A bit tedious for an old duffer like me; but not difficult.

SI units are really scary. Completely unintuitive for me. So catching some arithmetic errors took longer than it should have. But the end result is a prediction of 10 uN for the present system -- whereas observation is ~ 3 uN.
And that with the assumption that the electrostrictive constant is the same as the piezoelectric constant. It is surely smaller (by 3-orders of magnitude, P.M.). But without allowance for mechanical resonance amplification -- which is surely present (To the tune of 100 in this case, P.M.). These two considerations will be largely offsetting I expect. And the resulting prediction will likely be in the uN range."

And from a follow up corespondance between Dr. Wooward and myself:

"... We're talking a (thust) prediction that corresponds to observation to better than order of magnitude. And the observation has an SNR >= 10. That's a large improvement over the earlier predictions which were off by five orders of magnitude. :-)"

BTW, The title of Dr. Woodward's AIAA 2012 JPC paper is: "Recent Experimental Developments with Mach Effects" by Fearn & Woodward.

Best,

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PostPosted: Sun Aug 05, 2012 9:11 pm 
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GIThruster wrote:
My mistake. I should have noted there was 100W running but only about 1W dissipated. They were using a laser IR thermometer to monitor and there was only a degree or so heating.

I haven't seen a comparison to theory. Jim has been preparing for AIAA's JPC this last week and hasn't been doing so much lab work. Heidi is the one who generated these results by manually tuning a variable inductor. Unfortunately she smoked the amp she was using so only got the stated 7 runs done.



Resonance conditions can produce massive voltage spikes if the Q is high. Probably overloaded the breakdown voltage of the output semiconductors.

Might be worthwhile putting varistors on the output stage rated at less than the breakdown voltage ratings of the output Amp finals.

You could also incorporate some fusing in the output leads so as to replace cheap quick-blow fuses rather than output stages in your amp.

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PostPosted: Mon Aug 13, 2012 8:21 pm 
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If someone can explain a way for me to UL a pdf I'll be happy to post the paper Jim delivered to AIAA last week. In the meantime, here's an excerpt summarizing the kinds of protocols he uses:

When experiments with PZT stacks were first designed over a dozen years ago, two procedures were used in collecting data. Sweeps of chosen ranges of frequencies were done, chiefly to identify the presence and locations of resonant behaviors. Once found, the frequency of the applied signal(s) was adjusted to the resonant frequencies (one at a time) and sustained pulses of power with a half second to several seconds duration were administered. In addition to the applied voltage and thrust response, several other data channels were recorded – including the response of an accelerometer embedded in the PZT stack and the temperature measured with a thermistor embedded in the aluminum cap that clamps the stack to the brass reaction disk. The cycles of data were computer controlled so as to be identical to each other, simplifying the task of signal averaging with multiple cycles to suppress random noise in the data.

Data were acquired at a rate of 100 Hz per channel, and each channel was provided with a 50 Hz low pass anti- aliasing filter. In the present work, started a year and a half ago, data cycles of 20 seconds were initially used, and recently the interval was extended to 32 seconds. Instead of doing frequency sweeps and pulses separately, they were combined. Each cycle consisted of a few seconds of quiescent initial data, followed by a power pulse at the center frequency of the sweep to follow with a duration of a half second to several seconds, followed by the frequency sweep of a predetermined range, followed by another center frequency pulse like the initial one, followed by several seconds of quiescent data. Usually, but not always, the center frequencies for the sweeps were chosen to be resonant frequencies of the devices. Typically, between one and two dozen cycles of data taken under the same circumstances (durations and center frequencies, but not things like temperature) were needed for signal averaging that would reduce the noise in the thrust traces to a few tenths of a micronewton or less. After the resonance frequency of a particular PZT stack was established, runs were sometimes done without frequency sweeps. In one case, in the normally swept part of each cycle the device was simply turned off. In another case, the normally swept part of the cycle was replaced with constant center frequence power on, resulting in a power pulse of 10 seconds duration. Since the settling time of the balance beam was about 5 seconds, these 10 second power pulses allowed the demonstration of the stationary nature of the thrusts produced by the Mach effect in these devices.

The resonant frequencies for the PZT stacks were found to lie in the range of 35 to 40 KHz. Though it was not appreciated at the outset, the electrical and mechanical resonant frequencies in this range did not necessarily coincide, depending on detailed circumstances differing by as much as a kilohertz or two. When, by chance, they did coincide, unusually good behavior was obtained. One device, in which the two resonances coincided by chance for a while, produced thrusts on the order of 10 μN for several weeks, the amplitude of the voltage across the device at resonance being in the range of 350 to 400 volts. The “just so” conditions were eventually lost. But this and another device like it continued to produce thrusts up to a couple of μN, and those devices were used to carry out a series of tests to establish whether the thrust signals spurious, or evidence for a real Mach effect.

Those tests included checking to see whether the thrusts seen depended on the pressure of the residual air in the vacuum chamber by comparing data obtained with the chamber pressure less than 10 mT with data for a chamber pressure of 10 T. No significant difference was found. Mechanical thrust signals were generated using the calibration system so that mechanical signals, which are affected by the inertia of the balance beam, could be consistently discriminated from, for example, electrical signals. Another test involved replacing the device with a capacitor with roughly the same capacitance (41 nf versus 39 nf) as the devices and running to see what effect the currents and voltages present had on the thrust circuit. The simple answer is, none. Another test involved removing part of the Faraday cage and carrying out thrust tests with the device in various orientations to see if there was any electromagnetic coupling to insulators or conductors in the environment. None was detected.

One routine test and two potential spurious sources of signals deserve special mention. The routine test was reversal of the direction of the device on the balance beam; that is, “forward” and “reversed”. Essentially all data was acquired with roughly equal numbers of cycles of forward and reversed orientations. The reason for following this protocol is simple. When the difference of the forward and reversed averages is taken, all signals that do not reverse sign with the direction reversal are cancelled as common mode “noise”. For example, should a small torque be introduced by the currents and/or voltages present in the galinstan contacts or their leads, they will not change when the direction of the device is reversed. Consequently, they will be cancelled by this protocol. Likewise for all other non-reversing signals. And one can have confidence that any thrust that survives this protocol is produced in the device and/or its mount and Faraday cage, for they are the only things that change with direction reversal.

The two sources of potential spurious signals are thermal effects and “Dean drive” effects. Operation of the devices causes them to heat up. That in turn causes thermal expansion of the parts of the device and its mount. And the thermally driven motion of the parts of the device and mount, if they are changing in time, will produce thrusts that are communicated to the balance beam. In the case of Dean drive effects, vibration – and inevitable accompaniment to the operation of the devices – if it is communicated to a part of the balance where static and dynamic friction can act periodically to cause motion in one direction (but not the other), can produce behavior that looks like a thrust acting on the balance beam. This may take place, for example, with an object experiencing eccentric motion sitting on a rough surface, or located in a fluid with non-vanishing viscosity. In the case of this apparatus, the test that excludes residual air in the vacuum chamber eliminates the fluid variety of Dean drive effect. The only other place where such an effect might operate is in the bearings that support the balance beam in the central column. A careful investigation of both of these effects was carried out by one of us (JFW), and the results are reported in detail in the forthcoming book: Making Starships and Stargates: the Science of Traversable Absurdly Benign Wormholes.5 Here we report subsequent work that encompasses data that speaks to the issue of thermal effects in a different way than than previously reported.

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PostPosted: Mon Aug 13, 2012 11:09 pm 
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I've uploaded it for you:

http://www.sendspace.com/file/ypye96


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