Merged Discussion of femr's video data analysis

[Dave Rogers]

However, I'm also affirming that additional detail is being shown than was previously available (that being the green NIST curve)...

Or that you've removed less noise, and that therefore the general trends are less clearly visible. Pot-ay-to, pot-ah-to.

Do you have anything to say about the Savitzky-Golay smoothed profile ?

Yes. I have to say that it appears to offer no significant additional insight into the mechanism of the collapse. We see an initial increase in acceleration as support columns buckle, a period of near-freefall as the height of the initial multi-storey buckle is traversed, and a reduction in acceleration as significant resistance is encountered from the structure below the initial buckle.

Your insistence that your more detailed / more noisy representation of the data is a valuable contribution is, to my mind, comparable with Donald Trump's insistence that he has performed a valuable service by persuading President Obama to release his long form birth certificate. You've wasted an enormous amount of your own, and a thankfully negligible amount of everyone else's, time, trying to confirm by a more roundabout means a conclusion that's obvious to anyone from a very simple analysis, and now you're asking us to thank you for it.

Dave

 

[femr2]

Yes. I have to say that it appears to offer no significant additional insight into the mechanism of the collapse. We see an initial increase in acceleration as support columns buckle, a period of near-freefall as the height of the initial multi-storey buckle is traversed, and a reduction in acceleration as significant resistance is encountered from the structure below the initial buckle.

Interesting. Noted.

you're asking us to thank you for it

Nope, you don't have to thank me at all.

 

[Oystein]

They serve to filter out noise, and clearly reveal the underlying trend, as can be seen by comparison with simple symmetric difference derivation of acceleration which shows the same general profile but with much higher noise...
[qimg]http://femr2.ucoz.com/_ph/7/2/82136974.jpg[/qimg]


They reveal more detail in the profile than the NIST model, which is their purpose. They do indeed smooth the profile, yes.


Wordplay.

No, they are incapable of differentiating between signal and noise. At best, and in theory only, they compress noise to the same degree that they compress signal. In practice, As WDC comprehensively proved, they add noise (compression artefact) while reducing the signal.

My intent is clear, and the results a significant improvement upon pre-existing similar information.

It is precisely your intention that remains unclear. As Myriad so elegantly explained, you provide no insight into anything, at any level, beyond the raw data.

Alternatively, if your intention is to provide insight, your method is incapable on first mathematical principles of achieving this, and consequently you are bound to fail.

 

[Oystein]

I'm clearly affirming that information is being smoothed. Some will be noise, some will be signal. Can't see the wood for the trees without some smoothing

However, I'm also affirming that additional detail is being shown than was previously available (that being the green NIST curve)...
[qimg]http://femr2.ucoz.com/_ph/7/2/819970289.jpg[/qimg]

If you don't trust that additional detail, or you're fine with the (remarkably smooth ) detail contained in the green NIST curve, that's your lookout. Fine by me.

Do you have anything to say about the Savitzky-Golay smoothed profile ?

No-one here doubts (or at least not very much) that your trace data is an improvement over NIST's trace data, and thus an improvement over NIST's smoothed graph. However, while the NIST curve is described by a formula that has physics in mind and is thus capable of providing insight, your method simply puts nice round curves around good data (and around the noise which, if I understand correctly some of the criticism raised much earlier in this thread, you have not quantitatively estimated). We cannot know if these fine wiggles represent signal or noise. Smoothing that data only adds noise and subtracts signal. None of the 11 or 51 numerical parameters serve any reasonable purpose with a view to figuring out how and why WTC7 collapsed. The curves look nice, but they are, in their finer details, garbage in, garbage out, minus some.

 

[Major_Tom]

No-one here doubts (or at least not very much) that your trace data is an improvement over NIST's trace data, and thus an improvement over NIST's smoothed graph. However, while the NIST curve is described by a formula that has physics in mind and is thus capable of providing insight, your method simply puts nice round curves around good data (and around the noise which, if I understand correctly some of the criticism raised much earlier in this thread, you have not quantitatively estimated. We cannot know of thos fine wiggles represent signal or noise. Smoothing that data only adds noise. It looks nice, but it is, in its fine details, garbage in, garbage out, minus some.

You have no basis to say the equation chosen by the NIST has physics in mind.

What insight? A physicist gains zero special insight by looking at that equation.

There is no special physical meaning in their form of equation. It is an equation. I have never seen conversations about physics on this level before the 9-11-01 internet debate. All this internet talk introduced me to a new level of analysis and it is very unsettling to witness it.

I have never experienced people making physics up like this outside of internet forums. 9-11-01 is unique in that sense, introducing really bad physics as something that I find a bit scary. I have never been exposed to just how illiterate people can be about physics principles but think they know what they are talking about. Whole new world for me. Yipes!

Like Jabberwocky, you say things that seem to feel good at the time.

Can anyone support that claim with argument? Show me another physical system that behaves according to those equations.


WIthin a few days of the NIST releasing their equation it was analyzed by Frank Greening [url='http://the911forum.freeforums.org/it-s-official-it-s-faster-than-free-fall-t91.html#p1212"]here[/url] . Note the date in 2008.

Note how the absence of physical meaning and t=o problems were spotted within days of it being released.



A few year later you make up anything you want about the physical meaning of the equation with no other poster calling your bluff. This is not physics. It is a self serving circle of ego stroking.

 

[carlitos]

Major_Tom, are you reading this thread?

There is no special physical meaning in their form of equation. It is an equation.

er...

Glad you asked.

The argument of the exp function will range from zero, at t = 0, to a very large negative number at very large values of t.

exp(0) = 1, and
exp(a very large negative number) -> 0

and the function remains inside that interval for all values in between.

So, {1 - the exponential part} is 0 at t = 0, and 1 at a large t.

This makes it obvious right away what that first parameter 379.62 represents: the maximum displacement the model can generate, while the rest represents the fraction of that maximum displacement that has occurred as a function of time t. In other words, the displacement scale. We can regard the displacement units as being attached to that coefficient.

Now consider the .18562. We can see right away that it's multiplied by t. So if the number were doubled, it would have the same effect as doubling all values of t in the data. So that parameter establishes our time scale. Changing it would be like stretching or squeezing the x (time) axis of the resulting graph.

But what does the value actually mean? One to any power is one, so when (.18652 * t) = 1, the exponential is exp(-1), regardless of the value of the third parameter. Exp(-1) is 1/e or 0.3679. So after 1/.18652 = 5.36 seconds, the displacement will have reached about (1 - 0.3679) = .6321 of the maximum. This establishes the time it takes the model to displace to 63% of the maximum (a standard benchmark, closely related to the "time constant" of decay functions): in this case about 5 seconds.

Since those two parameters establish the x and y (time and displacement) scales of the model, only the third remains to refine the shape of the curve. The higher that value, the slower the displacement increases initially and the faster it increases near and after that 63% benchmark. That value is dimensionless (time and displacement already being accounted for in the other two parameters) but is proportional to the slope of the curve where t = the "time constant." If it were zero, the whole displacement curve would be a horizontal line at 63% of maximum displacement (never dropping off at all); if it were a large positive value, the displacement would stay very close to 0 up until t reached the "time constant" and then increase suddenly to the maximum.

So to sum up, the model's three parameters represent displacement scale, time scale, and the general distribution of movement over the time period.

Of course, their linear model is better, for the time period for which it was derived, because it represents not only the characteristics of the displacement curve but the main physical mechanism causing it.

 

[femr2]

No-one here doubts (or at least not very much) that your trace data is an improvement over NIST's trace data, and thus an improvement over NIST's smoothed graph.

Splendid.

However, while the NIST curve is described by a formula that has physics in mind and is thus capable of providing insight

Dave Rogers above seems to think that the S-G curve provides similar insight. What folk here are repeatedly losing sight of is that, as has been agreed, the polynomial fits serve simply to enable the improvement in the smoothed graph you allude to above. The formula was never intended to be a model in the slightest. The polynmial fits are simply a container for variation in the displacement profile. A totally different approach to NIST, and so not directly comparable at that level. Again, I'm not building a collapse model, I'm using various techniques to reveal as accurate trend information as possible.

We cannot know if these fine wiggles represent signal or noise.

Within which curve ? Undoubtedly the very fine *wiggles* in the S-G profile cannot be treated as either signal nor noise, but a mixture of the two. Of course there are limits, with, again, the intent being to reveal as much trend information as possible.

As you said...

"your trace data is an improvement over NIST's trace data, and thus an improvement over NIST's smoothed graph."

 

[Dave Rogers]

Dave Rogers above seems to think that the S-G curve provides similar insight.

Only from the fact that the general trends clearly visible in the NIST curve are still visible above the noise level in the S-G curve. I would say, therefore, that the NIST expression provides a clear insight into the collapse mechanism, whereas the S-G curve provides no clear view of the mechanism but may be understood in the light of the analysis NIST has already done. I wouldn't say your analysis tells us anything worthwhile that we don't already know.

What folk here are repeatedly losing sight of is that, as has been agreed, the polynomial fits serve simply to enable the improvement in the smoothed graph you allude to above. The formula was never intended to be a model in the slightest.

And what you're steadfastly refusing to acknowledge is that your failure to relate your smoothed data to any physical model precludes its revealing any new insights into the collapse mechanism, and essentially renders all your work irrelevant.

Dave

 

[Oystein]

You have no basis to say the equation chosen by the NIST has physics in mind.

What insight? A physicist gains zero special insight by looking at that equation.

Myriad explained the physical meaning and interpretation of NIST's 3 parameters in post 1321, and explained in post 1312 why femr2's 11 parameters have no meaningful interpretation outside perhaps quasi-religious sagas.

There is no special physical meaning in their form of equation. It is an equation. I have never seen conversations about physics on this level before the 9-11-01 internet debate. All this internet talk introduced me to a new level of analysis and it is very unsettling to witness it.

Incorrect. There is. Maybe you never had your heureka moment in physics before when contemplating on a mathematical formula. I had a couple of these years ago, and I can attest that the form of an equation can spark profound insights. Poly(10) do not, Poly(50) even less.

Your personal qualms with math cannot serve as an argument here.

I have never experienced people making physics up like this outside of internet forums.

9-11-01 is unique in that sense, introducing really bad physics as something that I find a bit scary. I have never been exposed to just how illiterate people can be about physics principles but think they know what they are talking about. Whole new world for me. Yipes!

Oh the irony.

Like Jabberwocky, you say things that seem to feel good at the time.

Oh the irony.

Can anyone support that claim with argument? Show me another physical system that behaves according to those equations.

Myriad did, some pages ago.

WIthin a few days of the NIST releasing their equation it was analyzed by Frank Greening [url='http://the911forum.freeforums.org/it-s-official-it-s-faster-than-free-fall-t91.html#p1212"]here[/url] . Note the date in 2008.

Note how the absence of physical meaning and t=o problems were spotted within days of it being released.

I note how one poster on the internet failed to see the physical meaning. That doesn't mean there isn't any.

A few year later you make up anything you want about the physical meaning of the equation with no other poster calling your bluff. This is not physics. It is a self serving circle of ego stroking.

Oh the irony.

 

[Major_Tom]

Dave, on this forum you tend to dismiss data before you have it. You also tend to make it up and believe any old thing you are told as the collective misunderatanding of early WTC1 movement demonstrates clearly.

Why be hostile to real data considering your own major blunders with the WTC1 column failure sequence?

In that case we have shown that real data is much better to work with than fake data.

Perhaps femr just wants real data instead of fake data? You need the real stuff before drawing conclusions. You should try it.

 

[Oystein]

Splendid.

Dave Rogers above seems to think that the S-G curve provides similar insight. What folk here are repeatedly losing sight of is that, as has been agreed, the polynomial fits serve simply to enable the improvement in the smoothed graph you allude to above.

Something is an improvement only in a given frame of reference. Improvement is determined by comparing two points along a scale. What is that scale? Where does it lead you in the end? Not toward insight about the physical processes, I declare.

The formula was never intended to be a model in the slightest. The polynmial fits are simply a container for variation in the displacement profile. A totally different approach to NIST, and so not directly comparable at that level. Again, I'm not building a collapse model, I'm using various techniques to reveal as accurate trend information as possible.


Within which curve ? Undoubtedly the very fine *wiggles* in the S-G profile cannot be treated as either signal nor noise, but a mixture of the two. Of course there are limits, with, again, the intent being to reveal as much trend information as possible.

As you said...

"your trace data is an improvement over NIST's trace data, and thus an improvement over NIST's smoothed graph."

And maybe you should have left it at that. Unsmoothed data. Next step should not be some smooth, fitting curve (compression of data), but an analysis of error margins. Error margins in the data might lead to error margins on the parameters of whatever smoothing curve you might want to try. However, Poly(10) and Poly(50) will never give you any insightful parameters. You will find that you can fit an infinite number of Poly curves through the error margins, and none is any more insightful than the next. I think you will find that the parameters will vary wildly within the data error margins, giving you all kinds of different wild behaviours on either ends and in between.

 

[femr2]

Only from the fact that the general trends clearly visible in the NIST curve are still visible above the noise level in the S-G curve.

We obviously view images in a different way.

NIST:
1.75s to reach *freefall*
2.25s of *freefall* (without mentioning the >g period in their own data)

S-G:
0.75s to reach *freefall*
1.75s at or above *freefall*

You see the same trend. Interesting.

And what you're steadfastly refusing to acknowledge is that your failure to relate your smoothed data to any physical model precludes its revealing any new insights into the collapse mechanism

Behaviour of descent is the focus. From clearer details of behaviour over time, clearer details of mechanism can be determined...such as the implications for the significant over-g period.

If you see no value in revealing the very short period of time to reach g, and exceed it for a while, that's entirely up to you.

 

[Oystein]

Dave, on this forum you tend to dismiss data before you have it.

No-one here, including Dave, dismisses femr2's data.
What we dismiss is his arbitrary messing with the data (reducing the signal, generating compression artefacts, ignoring to analyse noise).

You also tend to make it up and believe any old thing you are told as the collective misunderatanding of early WTC1 movement demonstrates clearly.

Why be hostile to real data considering your own major blunders with the WTC1 column failure sequence?

In that case we have shown that real data is much better to work with than fake data.

Perhaps femr just wants real data instead of fake data? You need the real stuff before drawing conclusions. You should try it.

femr's data is good.
Every step beyond that is irrelevant and detrimental as long as there is no physics in mind.

 

[Major_Tom]

Oystien and Myriad declare the physics behind the equation.

From experience I am confident that logic will sell with the other regular posters.

And nobody will step up cast a single doubt from the JREF side. That is what you seek, that type of understanding.

 

[Major_Tom]

Oystien, Femr has made many good measurements of WTC1 early movement. They were basically ignored. They were presented about a year ago. People have been ignoring the real WTC1 early movement data for a long time. If you did not, you would have realized some gaping contradictions by now.

I have to basically repeat the real measurements over and over to have any chance of countering the propaganda posters here have spread about WTC1.

If you didn't ignore data our "debate" would be very different. Without false data basically everything you thought you believed about WTC1 would implode. False data is the hot air that keeps this balloon afloat.

This is why good data is so important.

>>>>>>>>>>>>>>>>.
>>>>>>>>>>>>>>

You say you do not ignore real data, so why do I repeatedly request people agree to real tilt and movement data and are constantly ignored? I have been requesting that you clean up your own propaganda and use real data for many months..

Post after post it is ignored. I am accused of "spamming" for insisting you correct your mistakes. You are ignoring data, have been for a long time.

 

[alienentity]

Compared to the S-G curves the Poly(10) and Poly(50) both introduce distortions at various points.
I'd hate to see someone try to claim much precision out of the Poly curves, frankly. I don't think that's possible.

But in terms of indicating general trends, I much prefer the S-G, because it represents the data better than all the others.

Relating back to building mechanics and engineering, I agree with the other commenters who see column buckling up to about the 12.5s mark, then the ensuing rapid acceleration from about 12.5s to about 14.5s, then a period of diminishing acceleration.

The interval of most rapid acceleration does appear to be approximately in the region of 32m/s2, I can certainly accept that some might find that to be a reasonable benchmark to compare with.
I also accept Femr2's view that acceleration might have exceeded 32m/s2 briefly.

The problem is that the particular group of 9/11 Truthers doesn't understand the mechanics behind the collapse, so this additional detail is not meaningful to them....yet. It would be interesting to come up with a method which could explain the approximate nature of this data, and the futility of trying to assign some absolute value to it.

Note: In my view, the suggestion of >freefall interval is actually helpful in that it could only occur if the 'core' collapse were pulling on the exterior structure - again, precisely what the NIST analysis states, but contrary to what 9/11 Truthers think. That truthers (David Chandler would be the primary culprit) erroneously see 'instantaneous' acceleration to freefall across what they erroneously believe is the whole structure which is of relevance to this whole silly question of controlled demolition, after all.

 

[alienentity]

Oystien and Myriad declare the physics behind the equation.

From experience I am confident that logic will sell with the other regular posters.

And nobody will step up cast a single doubt from the JREF side. That is what you seek, that type of understanding.

The physics of the collapse, to be more accurate. The data generated from the videos is only useful when compared to a physical model, such as the one created by NIST.

I don't think you yet see how the two need to be reconciled very carefully, considering the approximations and imprecision inherent in the process. Nobody will ever know exactly what went on inside WTC 7 - that's not possible.

What we do know is that there is no requirement for explosive controlled demolition for the collapse of WTC 7, nor is there any direct evidence of it. The totality of the engineering studies, video and photographic evidence, and eyewitness testimony confirms this.

 

[femr2]

Something is an improvement only in a given frame of reference.

Your personal frame of reference is entirely up to you.

And maybe you should have left it at that.

Your opinion is noted. You shouldn't have wasted any of your time at all discussing 9/11. Easy eh ?

femr's data is good.

Splendid.

Every step beyond that is irrelevant and detrimental as long as there is no physics in mind.

In your opinion. I disagree. Physics is certainly in mind, just not embedded within Poly(10) equation which is, as has been suggested a number of times, a form of compression only. Just doesn't need to be anything more, and by definition the low parameter count of the NIST function could not possibly reveal and subtle variation in trend. All basically a repeat of #1324.

Numerous methods reveal the same underlying trend. The Savitzky-Golay curve is simply smoothed data. Differentiating between low level noise and low level signal is impractical and pointless. The data contains some low level noise. The derived profiles contain some noise, or are distorted to some extent by some noise. Just deal with it It's clear that the resultant profile is as accurate as has yet been presented.

The trend the S-G profile reveals is in close correlation to the Poly(10) and Poly(50) curves generated by a completley different method.

If you want to provide a more accurate and detailed profile, by all means. Until you do, it's the best available.

 

[alienentity]

Oystien, Femr has made many good measurements of WTC1 early movement.

OT. You're just ranting.

 

[Major_Tom]

AE, anyone who believes that accelerations close to or exceeding g are normal doesn't know anything about the mechanics behind any collapse, including intentional demolitions.

I posted earlier to the first analysis of Frank Greening days after the release of the NIST function. He is a debunker and was probably the best poster on this forum.

He could see the problems with near g acceleration and the greater than g hump from his very first post in 2008.


In a different universe it is considered normal. He understood more in the first couple of days than you have understood in 3 years. Where in your universe do buildings collapse with this acceleration range?