This still was just after the bumping of the camera.
I tried to upload it as a bmp but it looks like photobucket converts everything to jpg.
http://i134.photobucket.com/albums/q91/sha...24afterbump.jpg
.
Thanks so much. That's beautiful. The one einsteen and I have been working with has been resized and or cropped. Now, I'll know by how much.
QUOTE (einsteen+Nov 4 2007, 01:33 PM)
E1/MassWTC=1.5 J/kg
The mass specific energy for WTC 1 is about 224 J/kg for the first three seconds using a constant force parameter estimation with a constant stretch = 0.14.
Kindly try that and post what you discover. But by the end of crush-down the force was probably much higher. So try cranking it up to 1000 J/kg as well, will you?
The mass specific energy for WTC 1 is about 224 J/kg for the first three seconds using a constant force parameter estimation with a constant stretch = 0.14.
Kindly try that and post what you discover. But by the end of crush-down the force was probably much higher. So try cranking it up to 1000 J/kg as well, will you?
From quick examination, it appears the video we've been working with is simply cropped and not resized at all. I'm surprised by this somewhat but need to revisit the issue of two-axis scaling. Thanks again, shagster, it's a big help.
There are some images of the sub-levels that are in the Lera plans that surfaced on the web. This one was for the B-4 level. The drawing is dated 2-9-1984. I cropped the pic to show the two towers. This would give some idea of the tower spacing but not highly accurate.
Someone else here may have exact numbers.
http://i134.photobucket.com/albums/q91/sha...e/SKA11-84b.jpg
Someone else here may have exact numbers.
http://i134.photobucket.com/albums/q91/sha...e/SKA11-84b.jpg
QUOTE (shagster+Nov 4 2007, 09:58 PM)
There are some images of the sub-levels that are in the Lera plans that surfaced on the web. This one was for the B-4 level. The drawing is dated 2-9-1984. I cropped the part showing the two towers. This would give some idea of the tower spacing but not highly accurate.
Someone else here may have exact numbers.
http://i134.photobucket.com/albums/q91/sha...e/SKA11-84b.jpg
Thanks yet again. This would be the best info I've run across yet.
Someone else here may have exact numbers.
http://i134.photobucket.com/albums/q91/sha...e/SKA11-84b.jpg
Thanks yet again. This would be the best info I've run across yet.
Or, you can ask Philip Petit how much rope he used between the two nearest corners of the towers when he did his famous illegal tightwire act in the early 70s.
QUOTE (shagster+Nov 4 2007, 10:03 PM)
Or, you can ask Philip Petit how much rope he used between the two nearest corners of the towers when he did his famous illegal tightwire act in the early 70s.
Haha, then I'd have to correct for catenary action.
Haha, then I'd have to correct for catenary action.
There is no resize, only crop. This is a cropped version of the frame shagster just posted and one from the internet video, 50-50 blend:
http://i22.tinypic.com/2r3l7p0.png
Only differs by smoke... didn't bother to try to find the exact frame to match.
http://i22.tinypic.com/2r3l7p0.png
Only differs by smoke... didn't bother to try to find the exact frame to match.
The B & V crush-up equation is
(1-s)YY" + Y = F(Y)
where Y" is the second derivative (normalized form, with g = H = M = 1) and s is the stretch, taken as constant for simplicity.
We can rewrite this equation as
(1+(1-s)Y")Y = F(Y)
to posit a solution of
Y = Y0 - kt^2 (until kt^2 = Y0 and then 0 thereafter)
so that Y' = -2kt and Y" = -2k, a constant. For this to be a solution, the resisting force has to then be
F(Y) = (1-2k(1-s))(Y0-kt^2),
that is a constant less the decrease in kinetic energy as the collapse slows, the kinetic energy being proportional to (Y')^2 = 4k^2t^2. Reasonable or not, this form of resistance enables the possibility of an extremely long collapse time for very small constant k.
Note that Y is the normalized height of the portion undergoing crush-up, not the displacement. Thus Y' starts at 0.
Edited to add: But after a crush-down phase, Y'(0) is non-zero. Let us try again, where for simplicity Y0=1. Assume a force of
F(Y,Y') = kYY'
to rewrite the crush-up equation as
(1-s)Y" + 1 = kY'
by dividing through by Y. Rearrange the equation as
((1-s)/k)(Y"/Y') = -1
to note that a solution of the form
Y(t) = exp(-bt)
exists, since
Y' = -b*exp(-bt) and Y" = b^2*exp(-bt)
so that ((1-s)/k) = -1/b; k = -(1-s)b where b = -Y'(0).
As B & V point out in their own fashion, crush-up never ends with Y = 0. Once again, by suitable choice of the constant b, crush-up can take an arbitrarily long time to approach Y = 0.
(1-s)YY" + Y = F(Y)
where Y" is the second derivative (normalized form, with g = H = M = 1) and s is the stretch, taken as constant for simplicity.
We can rewrite this equation as
(1+(1-s)Y")Y = F(Y)
to posit a solution of
Y = Y0 - kt^2 (until kt^2 = Y0 and then 0 thereafter)
so that Y' = -2kt and Y" = -2k, a constant. For this to be a solution, the resisting force has to then be
F(Y) = (1-2k(1-s))(Y0-kt^2),
that is a constant less the decrease in kinetic energy as the collapse slows, the kinetic energy being proportional to (Y')^2 = 4k^2t^2. Reasonable or not, this form of resistance enables the possibility of an extremely long collapse time for very small constant k.
Note that Y is the normalized height of the portion undergoing crush-up, not the displacement. Thus Y' starts at 0.
Edited to add: But after a crush-down phase, Y'(0) is non-zero. Let us try again, where for simplicity Y0=1. Assume a force of
F(Y,Y') = kYY'
to rewrite the crush-up equation as
(1-s)Y" + 1 = kY'
by dividing through by Y. Rearrange the equation as
((1-s)/k)(Y"/Y') = -1
to note that a solution of the form
Y(t) = exp(-bt)
exists, since
Y' = -b*exp(-bt) and Y" = b^2*exp(-bt)
so that ((1-s)/k) = -1/b; k = -(1-s)b where b = -Y'(0).
As B & V point out in their own fashion, crush-up never ends with Y = 0. Once again, by suitable choice of the constant b, crush-up can take an arbitrarily long time to approach Y = 0.
That value of 1.5 J/kg that Einsteen used is E1 divided by the entire mass of the 110-story tower.
The model he posted assumes an E1 that is the same throughout a tower that has a constant mass density. So, the ratio of E1/m changes as the collapse progresses. m is the total mass above the collapse front at any given time.
E1/m is 1.5 J/kg at the bottom of the tower and increases toward the top of the tower. That's why the collapse slows near the end of the crush-up in Einsteen's algebraic model.
1.5 J/kg is a reasonable value for 110 stories. For 14 stories, E1/m is:
E1/m = 1.5 J/kg * 110/14 = 11.8 J/kg
Assume a total tower mass of 300E6 kg. E1 is then:
1.5 J/kg *300E6 kg = 0.45 GJ
E1 is 0.45 GJ for every story in his model when the total tower mass is 300E6 kg.
Greening was using a constant E1 of about 0.6 GJ per story for WTC1 to make the observed collape rate match what his model predicted.
E1/m at the bottom of the tower for Greening's model is:
0.6 GJ / 510E6 kg = 1.2 J/kg
That's close to the value of 1.5 J/kg that Einsteen used in his example.
The model he posted assumes an E1 that is the same throughout a tower that has a constant mass density. So, the ratio of E1/m changes as the collapse progresses. m is the total mass above the collapse front at any given time.
E1/m is 1.5 J/kg at the bottom of the tower and increases toward the top of the tower. That's why the collapse slows near the end of the crush-up in Einsteen's algebraic model.
1.5 J/kg is a reasonable value for 110 stories. For 14 stories, E1/m is:
E1/m = 1.5 J/kg * 110/14 = 11.8 J/kg
Assume a total tower mass of 300E6 kg. E1 is then:
1.5 J/kg *300E6 kg = 0.45 GJ
E1 is 0.45 GJ for every story in his model when the total tower mass is 300E6 kg.
Greening was using a constant E1 of about 0.6 GJ per story for WTC1 to make the observed collape rate match what his model predicted.
E1/m at the bottom of the tower for Greening's model is:
0.6 GJ / 510E6 kg = 1.2 J/kg
That's close to the value of 1.5 J/kg that Einsteen used in his example.
QUOTE (David B. Benson+Nov 5 2007, 12:10 AM)
Edited to add: But after a crush-down phase, Y'(0) is non-zero. Let us try again, where for simplicity Y0=1. Assume a force of
F(Y,Y') = kYY'
to rewrite the crush-up equation as
(1-s)Y" + 1 = kY'
by dividing through by Y. Rearrange the equation as
((1-s)/k)(Y"/Y') = -1
to note that a solution of the form
Y(t) = exp(-bt)
exists, since
Y' = -b*exp(-bt) and Y" = b^2*exp(-bt)
so that ((1-s)/k) = -1/b; k = -(1-s)b where b = -Y'(0).
As B & V point out in their own fashion, crush-up never ends with Y = 0. Once again, by suitable choice of the constant b, crush-up can take an arbitrarily long time to approach Y = 0.
If I'm following this correctly, for a crush-down followed by crush-up, the constant b cannot be suitably selected to achieve a long crush-up duration since b is the velocity at the start of crush-up in this type of solution, which is dictated by the velocity at the end of the crush-down phase. If the starting velocity is large, say, 50 m/s, then b is large. That means the exponential will decay quickly and the collapse front will reach the top of the upper block quickly, although it make take a very long time to go a very small sub-story distance as it approaches the very top of the upper block for an exponential type of solution in a continuum model.
The building in the left of the shot from WTC: First 24 Hours was identified as 101 Avenue of the Americas in a reference shagster gave. This appears to be correct. Compare the contrast-enhanced slice from the video with photos of the building http://www.emporis.com/en/il/im/?id=112407 and http://www.emporis.com/en/il/im/?id=252582.
http://i24.tinypic.com/2hrlctz.png
There was speculation the shot might be from somewhere on Varick Street but it doesn't look like this can be so. The two buildings in the frame image, along with the sky between them, define rays to the camera which can be traced roughly on a map. The vertex of the rays at the camera should be behind 101 Ave of the Americas such that the northwest corner of the building intrudes about 27% into field of view, which we note is centered on the northeast corner of WTC1, which itself occupies just over 30% of the horizontal field of view.
When putting this on a map (ignoring the arc, working only with the tangent line for simplicity), the rays come to a point as depicted below:
http://i24.tinypic.com/2zobyqg.png
http://i24.tinypic.com/1zoujyd.png
Brute force and very approximate but, as you move the vertex around, you see that the geometry is fairly well contrained to a narrow region which extends away in basically the same radial direction from the tower. A camera location on Verick Street can only include both buildings if it's a wide-angle shot, which clearly it isn't. In the direction of the rays, street level is not expected to afford much of a view until you get pretty far back; it's possible that the individual was on a roof or otherwise up in a building. The frame from the original video also shows a dark border, cropped from the internet copy, likely to be other building edges.
http://i24.tinypic.com/2hrlctz.png
There was speculation the shot might be from somewhere on Varick Street but it doesn't look like this can be so. The two buildings in the frame image, along with the sky between them, define rays to the camera which can be traced roughly on a map. The vertex of the rays at the camera should be behind 101 Ave of the Americas such that the northwest corner of the building intrudes about 27% into field of view, which we note is centered on the northeast corner of WTC1, which itself occupies just over 30% of the horizontal field of view.
When putting this on a map (ignoring the arc, working only with the tangent line for simplicity), the rays come to a point as depicted below:
http://i24.tinypic.com/2zobyqg.png
http://i24.tinypic.com/1zoujyd.png
Brute force and very approximate but, as you move the vertex around, you see that the geometry is fairly well contrained to a narrow region which extends away in basically the same radial direction from the tower. A camera location on Verick Street can only include both buildings if it's a wide-angle shot, which clearly it isn't. In the direction of the rays, street level is not expected to afford much of a view until you get pretty far back; it's possible that the individual was on a roof or otherwise up in a building. The frame from the original video also shows a dark border, cropped from the internet copy, likely to be other building edges.
Using rays in a different fashion, a 2D image of a 3D scene can be rendered to see the geometry. With the camera in the tentative location found above and target line of sight chosen suitably, I rendered a scene with a block of the approximate size and location of the high rise part of 101 Ave of the Americas. After a little position and view angle tweaking, the result comes pretty close to the image in the video. The four pictures below show a transition from the video image to the rendered image.
Frame 800 from video alone
Blend of video image and rendered image - 50%
Blend of video image and rendered image - 83%
Rendered image alone
Not yet exactly right, but literally within a ballpark.
Frame 800 from video alone
Blend of video image and rendered image - 50%
Blend of video image and rendered image - 83%
Rendered image alone
Not yet exactly right, but literally within a ballpark.
Swapping camera and target locations allows us to look back from the tower area to the camera location, here shown by a sphere. No building texture made for the block yet, so 101 Ave looks like agate. A band radiates away on the line of sight.
http://i22.tinypic.com/qqd6o1.png
Now let's move up from that spot and zoom out:
http://i24.tinypic.com/15yiuch.gif
It's only a matter of time before the radial distance, camera elevation, LOS elevation angle and azimuthal angle are known to a reasonable precision. Perspective effects can then be transformed away. Antenna tilt away from the camera can be derived from decrease in pixel spacing of dishes (from the real video, of course!) as collapse progresses.
I expect this eventually to be only a marginal improvement over the calculation of elevation angle done by David B. Benson, but worthwhile all the same.
http://i22.tinypic.com/qqd6o1.png
Now let's move up from that spot and zoom out:
http://i24.tinypic.com/15yiuch.gif
It's only a matter of time before the radial distance, camera elevation, LOS elevation angle and azimuthal angle are known to a reasonable precision. Perspective effects can then be transformed away. Antenna tilt away from the camera can be derived from decrease in pixel spacing of dishes (from the real video, of course!) as collapse progresses.
I expect this eventually to be only a marginal improvement over the calculation of elevation angle done by David B. Benson, but worthwhile all the same.
(1-s)YY" + Y = F(Y)
I used s=0 which gives
YY''+Y=F(Y), or
Y''=F(Y)/Y-1
the g=0 solution then is in fact solving Y''=F(Y)/Y which gave 1.068 seconds
the other one is solving Y''=0 giving the 1 second. The real solution must be
between those values.
I'm also not sure if I understand why Y=0 will never be reached ? It's no
asymptotic limit is it ? I always put my math glasses off and put the physics glasses on
cases like this. Of course when layers are formed we should not integrate
to zero but to the thickness of the pile to exclude non-physical solutions.
Shagster,
Yes, I had to say that more explicitly, I used E1_per-story/TotalMassbuilding, posted that before, derived from the (2/3)g initial acceleration. But that was 100s of pages ago, if I remember the old Greening values it was 0.63*10^9/(5.1*10^8)=1.24, 1.2 is indeed better than 1.5, that will decrement the crush-up time even more.
I used s=0 which gives
YY''+Y=F(Y), or
Y''=F(Y)/Y-1
the g=0 solution then is in fact solving Y''=F(Y)/Y which gave 1.068 seconds
the other one is solving Y''=0 giving the 1 second. The real solution must be
between those values.
I'm also not sure if I understand why Y=0 will never be reached ? It's no
asymptotic limit is it ? I always put my math glasses off and put the physics glasses on
cases like this. Of course when layers are formed we should not integrate
to zero but to the thickness of the pile to exclude non-physical solutions.
Shagster,
Yes, I had to say that more explicitly, I used E1_per-story/TotalMassbuilding, posted that before, derived from the (2/3)g initial acceleration. But that was 100s of pages ago, if I remember the old Greening values it was 0.63*10^9/(5.1*10^8)=1.24, 1.2 is indeed better than 1.5, that will decrement the crush-up time even more.
OWE, great work although I can't say if I understand it all at the moment:-)
QUOTE (einsteen+Nov 5 2007, 09:32 AM)
OWE, great work although I can't say if I understand it all at the moment:-)
Thanks. Right back at ya. Eventually I'll figure out what you're doing up there, too. Then we'll integrate the work!
Thanks. Right back at ya. Eventually I'll figure out what you're doing up there, too. Then we'll integrate the work!
QUOTE (einsteen+Nov 5 2007, 09:17 AM)
I'm also not sure if I understand why Y=0 will never be reached ? It's no
asymptotic limit is it ? I always put my math glasses off and put the physics glasses on
cases like this. Of course when layers are formed we should not integrate
to zero but to the thickness of the pile to exclude non-physical solutions.
In theory the crush-up doesn't go to completion if the resistive force is non-zero in a continuum model. In theory the front can stop a micrometer below the very top of the block. In the real world, there is a discreteness due to the stories. The top story would get destroyed in a case where the continuum theory predicts that only the last micrometer at the top doesn't get destroyed.
If E1 is large enough, the crush-up can stop more than one story below the top of the block. If you put a high enough E1 in your algebraic crush-up model, you'll find that the front not only slows down near the end but that it halts at some story below the top. This has some relevance in the real world, whereas the last micrometer at the top doesn't. In the real world, one could estimate E1 if a crush-up didn't go to completion by measuring the height of the portion of the upper block that remained intact sitting on top of the rubble pile.
There are a couple instances where a crush-up goes to completion. That occurs if the resisting force is zero. It also occurs if E1/mh is a constant throughout the whole block. In that case, E1 goes to zero as the mass above the front m goes to zero. When E1/mh is constant, the acceleration is constant and less than g.
Yeah, I understand what you mean, but isn't that a matter of the initial energy conditions ?
If I use the results of my plane paper and apply it for a block that crushes on a infinitely strong wall, and ignore gravity, i.e. g=0 then
the kinetic energy is E_kin=0.5Mv^2, the crushing energy =LF_crush
I introduced an alpha:=Ekin/E_crush=M_block v^2/2LF_crush
#1) if alpha<1 then it will stop, at a certain moment v will be zero and then become negative mathematically but physically stop.
#2) if alpha=1 it will exactly crush the complete block,
#3) if alpha>1 then it will completely crush the block and there is even energy left.
For the wtc1 top block that would be the ratio
M_block v^2/(2*E1*13)
This is roughly a factor 10 !! It will never stop. And here even the gravity is ignored.
I created a 3d plot, in fact
t=t(v,alpha), if alpha>=1 and v_init=52 m/s then the function is bound by a maximum value not much larger than 1 second. The limit exists.
If I use the results of my plane paper and apply it for a block that crushes on a infinitely strong wall, and ignore gravity, i.e. g=0 then
the kinetic energy is E_kin=0.5Mv^2, the crushing energy =LF_crush
I introduced an alpha:=Ekin/E_crush=M_block v^2/2LF_crush
#1) if alpha<1 then it will stop, at a certain moment v will be zero and then become negative mathematically but physically stop.
#2) if alpha=1 it will exactly crush the complete block,
#3) if alpha>1 then it will completely crush the block and there is even energy left.
For the wtc1 top block that would be the ratio
M_block v^2/(2*E1*13)
This is roughly a factor 10 !! It will never stop. And here even the gravity is ignored.
I created a 3d plot, in fact
t=t(v,alpha), if alpha>=1 and v_init=52 m/s then the function is bound by a maximum value not much larger than 1 second. The limit exists.
QUOTE (shagster+Nov 4 2007, 07:51 PM)
If I'm following this correctly, for a crush-down followed by crush-up, the constant b cannot be suitably selected to achieve a long crush-up duration since b is the velocity at the start of crush-up in this type of solution, which is dictated by the velocity at the end of the crush-down phase. If the starting velocity is large, say, 50 m/s, then b is large. That means the exponential will decay quickly and the collapse front will reach the top of the upper block quickly, although it make take a very long time to go a very small sub-story distance as it approaches the very top of the upper block for an exponential type of solution in a continuum model.
Yes. Plugging in 52 m/s for the top block of WTC 1 results in 1.483 seconds to crush-up 95% of the top block.
So I suppose the rumblings heard in the Heath video are from sections of the north wall striking WTC 6, etc.
Yes. Plugging in 52 m/s for the top block of WTC 1 results in 1.483 seconds to crush-up 95% of the top block.
So I suppose the rumblings heard in the Heath video are from sections of the north wall striking WTC 6, etc.
QUOTE (David B. Benson+Nov 5 2007, 06:33 PM)
Yes. Plugging in 52 m/s for the top block of WTC 1 results in 67 milliseconds to crush 95% of the top block.
So I suppose now that the rumbling at near the end of the Heath video is from north wall sections striking WTC 6, etc.
Do you have a plot of the magnitude of E1 as a function of block height for that type of solution? In other words, how E1 varies with distance through the upper block. Just curious.
So I suppose now that the rumbling at near the end of the Heath video is from north wall sections striking WTC 6, etc.
Do you have a plot of the magnitude of E1 as a function of block height for that type of solution? In other words, how E1 varies with distance through the upper block. Just curious.
QUOTE (einsteen+Nov 5 2007, 11:34 AM)
Yeah, I understand what you mean, but isn't that a matter of the initial energy conditions ?
If I use the results of my plane paper and apply it for a block that crushes on a infinitely strong wall, and ignore gravity, i.e. g=0 then
the kinetic energy is E_kin=0.5Mv^2, the crushing energy =LF_crush
I introduced an alpha:=Ekin/E_crush=M_block v^2/2LF_crush
#1) if alpha<1 then it will stop, at a certain moment v will be zero and then become negative mathematically but physically stop.
#2) if alpha=1 it will exactly crush the complete block,
#3) if alpha>1 then it will completely crush the block and there is even energy left.
For the wtc1 top block that would be the ratio
M_block v^2/(2*E1*13)
This is roughly a factor 10 !! It will never stop. And here even the gravity is ignored.
I created a 3d plot, in fact
t=t(v,alpha), if alpha>=1 and v_init=52 m/s then the function is bound by a maximum value not much larger than 1 second. The limit exists.
Yes, I agree with all of that.
Figure 7 of the BV paper shows the tails in the collapse curves for a crush-up with an initial velocity of zero. The tail on the collapse curves and the number of intact stories at the end become significant as E1 becomes larger. This is essentially what your model is saying when alpha is less than one.
If I use the results of my plane paper and apply it for a block that crushes on a infinitely strong wall, and ignore gravity, i.e. g=0 then
the kinetic energy is E_kin=0.5Mv^2, the crushing energy =LF_crush
I introduced an alpha:=Ekin/E_crush=M_block v^2/2LF_crush
#1) if alpha<1 then it will stop, at a certain moment v will be zero and then become negative mathematically but physically stop.
#2) if alpha=1 it will exactly crush the complete block,
#3) if alpha>1 then it will completely crush the block and there is even energy left.
For the wtc1 top block that would be the ratio
M_block v^2/(2*E1*13)
This is roughly a factor 10 !! It will never stop. And here even the gravity is ignored.
I created a 3d plot, in fact
t=t(v,alpha), if alpha>=1 and v_init=52 m/s then the function is bound by a maximum value not much larger than 1 second. The limit exists.
Yes, I agree with all of that.
Figure 7 of the BV paper shows the tails in the collapse curves for a crush-up with an initial velocity of zero. The tail on the collapse curves and the number of intact stories at the end become significant as E1 becomes larger. This is essentially what your model is saying when alpha is less than one.
QUOTE (shagster+Nov 5 2007, 11:43 AM)
Do you have a plot of the magnitude of E1 as a function of block height for that type of solution? In other words, how E1 varies with distance through the upper block. Just curious.
Note that I edited the post to correct the value to 1.483 seconds.
The energy consumed at time t over a short time dt is
FY'(t)dt = kY(t)(Y'(t))^2dt
where b = 4.449 and so k depends upon the assumed stretch. But the functional form is a decaying exponential with the exponential part being exp(-3bt). The block thickness varies as Y(t), also exponential, so dividing the energy consumed by the thickness gives an exponential of the form exp(-2bt), if that's what you meant.
Note that I edited the post to correct the value to 1.483 seconds.
The energy consumed at time t over a short time dt is
FY'(t)dt = kY(t)(Y'(t))^2dt
where b = 4.449 and so k depends upon the assumed stretch. But the functional form is a decaying exponential with the exponential part being exp(-3bt). The block thickness varies as Y(t), also exponential, so dividing the energy consumed by the thickness gives an exponential of the form exp(-2bt), if that's what you meant.
QUOTE (David B. Benson+Nov 5 2007, 06:33 PM)
Yes. Plugging in 52 m/s for the top block of WTC 1 results in 1.483 seconds to crush-up 95% of the top block.
So I suppose the rumblings heard in the Heath video are from sections of the north wall striking WTC 6, etc.
It's possible for the collapse front to be moving slower later in the collapse than what would be expected based on data from only the first 3 or 4 seconds of collapse. I managed to get a couple data points of the front position of WTC2 well after 4 seconds from the ground video which wasn't blocked by the dust shroud. The front was moving more slowly than what would be expected based on the first 4 seconds of collapse. A possible explanation is that the percentage of shedding increased as the collapsed progressed, which would have a slowing effect on the collapse. Another is that part of the upper block may have toppled outside the footprint. There may be other factors that we haven't considered that could slow the front and increase the crush-down duration.
So I suppose the rumblings heard in the Heath video are from sections of the north wall striking WTC 6, etc.
It's possible for the collapse front to be moving slower later in the collapse than what would be expected based on data from only the first 3 or 4 seconds of collapse. I managed to get a couple data points of the front position of WTC2 well after 4 seconds from the ground video which wasn't blocked by the dust shroud. The front was moving more slowly than what would be expected based on the first 4 seconds of collapse. A possible explanation is that the percentage of shedding increased as the collapsed progressed, which would have a slowing effect on the collapse. Another is that part of the upper block may have toppled outside the footprint. There may be other factors that we haven't considered that could slow the front and increase the crush-down duration.
QUOTE (shagster+Nov 5 2007, 12:02 PM)
It's possible for the collapse front to be moving slower later in the collapse than what would be expected based on data from only the first 3 or 4 seconds of collapse.
Yes, but the 52 m/s is essentially the value from the BLGB paper, wherein structural resistance, concrete comminution and moving air out are all taken into account. This gives a crush-down time of about 13 seconds for WTC 1, in good agreement with the seismograph data.
However, an even better agreement can be obtained, I am quite sure, by assuming some significant, intact mass, such as the top block, falling free to impact the ground slightly earlier. This would agree with the seismograph data even better, as well, of course, as slightly slowing down the main crush-down. However, it is unlikely to slow it by the entire 5 seconds required, nor would such agree with the seismograph trace and other evidence.
Edited to add: From your observations regarding WTC 2 I am reasonably convinced that the top block fell apart, the pieces falling off to proceed on their own. There seem too many plausible scenarios to be able to say much more that just that, IMO.
Yes, but the 52 m/s is essentially the value from the BLGB paper, wherein structural resistance, concrete comminution and moving air out are all taken into account. This gives a crush-down time of about 13 seconds for WTC 1, in good agreement with the seismograph data.
However, an even better agreement can be obtained, I am quite sure, by assuming some significant, intact mass, such as the top block, falling free to impact the ground slightly earlier. This would agree with the seismograph data even better, as well, of course, as slightly slowing down the main crush-down. However, it is unlikely to slow it by the entire 5 seconds required, nor would such agree with the seismograph trace and other evidence.
Edited to add: From your observations regarding WTC 2 I am reasonably convinced that the top block fell apart, the pieces falling off to proceed on their own. There seem too many plausible scenarios to be able to say much more that just that, IMO.
wcelliot:
=============
"DC" is commonly used as the term referring to the spectral component at zero frequency.
=============
I would be embarrased about the DC faux pas if I had made it, wcelliot.
But I wouldn't turn around and generate yet another lie about esoteric terminology that can't be substantiated by any facts.
Hence, you can't reference your whacky claim.
Oh what a tangled web we weave when first we practice to deceive.
Have you ever been burnt by a drum blast, you noisy little liar?
PS - STILL WAITING FOR YOUR REFERENCE FOR A 10 MICROSECOND PULSE - you know the claim you have made several dozen times without a supporting reference?
You did quote this irrelevant diversion:
But no 10 microseconds non-acoustic pulse here....
Where's the 10 microsecond reference, pal?
Wheres' your DAPRA microphone reference, pal?
Why should anyone here believe a single world of your unreferenced authoritarian dogma?
addendum:
http://history-bytes.blogspot.com/2007/10/collapse.html
(press play, or use the frame advance buttons - or use both)
note for OneWhiteEye - this efficient animation is 1/8th the size of that 284 frame 100x100 animated gif of nothinG that you embedded on page 510 within a collection of meaningless images totalling 2.5 megabytes.
The number of posts you generate each 24 hours on this one topic is quite astonishing, btw.
=============
"DC" is commonly used as the term referring to the spectral component at zero frequency.
=============
I would be embarrased about the DC faux pas if I had made it, wcelliot.
But I wouldn't turn around and generate yet another lie about esoteric terminology that can't be substantiated by any facts.
Hence, you can't reference your whacky claim.
Oh what a tangled web we weave when first we practice to deceive.
Have you ever been burnt by a drum blast, you noisy little liar?
PS - STILL WAITING FOR YOUR REFERENCE FOR A 10 MICROSECOND PULSE - you know the claim you have made several dozen times without a supporting reference?
You did quote this irrelevant diversion:
QUOTE
http://www.bravecannons.org/the_gun/glossary.html
"C4: A military grade plastic explosive equivalent to 118% of TNT. A rubbery, fully plasticised mass, which can be kneaded and formed into any shape. It is insensitive to impact and friction and was often burned to heat food and water. It has a detonation rate of 26,400 fps and requires detonation cord (Det Cord), primers or blasting caps to set it off. "
"C4: A military grade plastic explosive equivalent to 118% of TNT. A rubbery, fully plasticised mass, which can be kneaded and formed into any shape. It is insensitive to impact and friction and was often burned to heat food and water. It has a detonation rate of 26,400 fps and requires detonation cord (Det Cord), primers or blasting caps to set it off. "
But no 10 microseconds non-acoustic pulse here....
Where's the 10 microsecond reference, pal?
Wheres' your DAPRA microphone reference, pal?
Why should anyone here believe a single world of your unreferenced authoritarian dogma?
addendum:
http://history-bytes.blogspot.com/2007/10/collapse.html
(press play, or use the frame advance buttons - or use both)
note for OneWhiteEye - this efficient animation is 1/8th the size of that 284 frame 100x100 animated gif of nothinG that you embedded on page 510 within a collection of meaningless images totalling 2.5 megabytes.
The number of posts you generate each 24 hours on this one topic is quite astonishing, btw.
QUOTE (Al Khwarizmi - step-by-step+Nov 6 2007, 04:56 AM)
note for OneWhiteEye - this efficient animation is 1/8th the size of that 284 frame 100x100 animated gif...
So? I'm posting GIFs so some of the people here can see animations. I don't care why they can't see movies, they say they can't. But they can see GIFs. Since you don't like what I post it should be of little concern to you, unless you're on dial-up, in which case too bad. SWF; big deal.
Sorry you feel that way. I used to enjoy you back when you posted bloody images, but less so now. Whatever.
So? I'm posting GIFs so some of the people here can see animations. I don't care why they can't see movies, they say they can't. But they can see GIFs. Since you don't like what I post it should be of little concern to you, unless you're on dial-up, in which case too bad. SWF; big deal.
QUOTE
...of nothinG that you embedded on page 510 within a collection of meaningless images totalling 2.5 megabytes.
The number of posts you generate each 24 hours on this one topic is quite astonishing, btw.
The number of posts you generate each 24 hours on this one topic is quite astonishing, btw.
Sorry you feel that way. I used to enjoy you back when you posted bloody images, but less so now. Whatever.
QUOTE (OneWhiteEye+Nov 6 2007, 06:23 AM)
Since you don't like what I post it should be of little concern to you, unless you're on dial-up, in which case too bad.
An unnecessarily p***y reply. My apologies. In deference to Al Khwarizmi - step-by-step and others not wanting to wade through my blather, I'll only post links to images and animations. (He had a lot to say. He had a lot of nothing to say.)
An unnecessarily p***y reply. My apologies. In deference to Al Khwarizmi - step-by-step and others not wanting to wade through my blather, I'll only post links to images and animations. (He had a lot to say. He had a lot of nothing to say.)
QUOTE (Al Khwarizmi - step-by-step+Nov 6 2007, 04:56 AM)
The number of posts you generate each 24 hours on this one topic is quite astonishing, btw.
That's because I am legion.
That's because I am legion.
QUOTE (Al Khwarizmi - step-by-step+Nov 6 2007, 05:56 PM)
wcelliot:
=============
"DC" is commonly used as the term referring to the spectral component at zero frequency.
=============
I would be embarrased about the DC faux pas if I had made it, wcelliot.
But I wouldn't turn around and generate yet another lie about esoteric terminology that can't be substantiated by any facts.
Hence, you can't reference your whacky claim.
Oh what a tangled web we weave when first we practice to deceive.
Have you ever been burnt by a drum blast, you noisy little liar?
PS - STILL WAITING FOR YOUR REFERENCE FOR A 10 MICROSECOND PULSE - you know the claim you have made several dozen times without a supporting reference?
You did quote this irrelevant diversion:
But no 10 microseconds non-acoustic pulse here....
Where's the 10 microsecond reference, pal?
Wheres' your DAPRA microphone reference, pal?
Why should anyone here believe a single world of your unreferenced authoritarian dogma?
addendum:
http://history-bytes.blogspot.com/2007/10/collapse.html
(press play, or use the frame advance buttons - or use both)
note for OneWhiteEye - this efficient animation is 1/8th the size of that 284 frame 100x100 animated gif of nothinG that you embedded on page 510 within a collection of meaningless images totalling 2.5 megabytes.
The number of posts you generate each 24 hours on this one topic is quite astonishing, btw.
I provided WCelliot with teh detonation velocity of Composition 4.
From this data it is possible to surmise that a block of C-4 6 inches long detonates completely in about 10 Microseconds.
This means that the shockwave created by the C-4 can last no more then 10 micro seconds (close to it's source anyway).
The information for the detonation velocity for C-4 is freely available on the web, if you know where to look for the SDS.
Oh, and we're all STILL waiting for you to adress the sonograph that I posted, the one with the wave forms on it that share the same features marked on the WTC sonographs, that according to you (and other conspiracy theorists) mean that the WTC could ONLY have been bought down by controled demolition.
=============
"DC" is commonly used as the term referring to the spectral component at zero frequency.
=============
I would be embarrased about the DC faux pas if I had made it, wcelliot.
But I wouldn't turn around and generate yet another lie about esoteric terminology that can't be substantiated by any facts.
Hence, you can't reference your whacky claim.
Oh what a tangled web we weave when first we practice to deceive.
Have you ever been burnt by a drum blast, you noisy little liar?
PS - STILL WAITING FOR YOUR REFERENCE FOR A 10 MICROSECOND PULSE - you know the claim you have made several dozen times without a supporting reference?
You did quote this irrelevant diversion:
But no 10 microseconds non-acoustic pulse here....
Where's the 10 microsecond reference, pal?
Wheres' your DAPRA microphone reference, pal?
Why should anyone here believe a single world of your unreferenced authoritarian dogma?
addendum:
http://history-bytes.blogspot.com/2007/10/collapse.html
(press play, or use the frame advance buttons - or use both)
note for OneWhiteEye - this efficient animation is 1/8th the size of that 284 frame 100x100 animated gif of nothinG that you embedded on page 510 within a collection of meaningless images totalling 2.5 megabytes.
The number of posts you generate each 24 hours on this one topic is quite astonishing, btw.
I provided WCelliot with teh detonation velocity of Composition 4.
From this data it is possible to surmise that a block of C-4 6 inches long detonates completely in about 10 Microseconds.
This means that the shockwave created by the C-4 can last no more then 10 micro seconds (close to it's source anyway).
The information for the detonation velocity for C-4 is freely available on the web, if you know where to look for the SDS.
Oh, and we're all STILL waiting for you to adress the sonograph that I posted, the one with the wave forms on it that share the same features marked on the WTC sonographs, that according to you (and other conspiracy theorists) mean that the WTC could ONLY have been bought down by controled demolition.
OK, Al, I posted this: "It has a detonation rate of 26,400 fps" from one of many sites providing similar data, and told you to do the math, and you didn't, but you did call me a liar. (You've been reported for that insult, and I hope you get kicked-off this site sooner rather than later.)
Since you can't do math, here's an example:
If it detonates at 26,400 feet-per-second, and the detonator is midway in a four-inch block of C-4, then the maximum distance the detonation can go before it runs out of C-4 is about three inches. Three inches at 26,400 feet/second takes 0.25feet/(26,400 feet/second) or about 10microseconds.
Is that clear enough for you?
Whatever "characteristic waveform" that a block of C-4 detonating might have, you'd better sample at twice the highest frequency-of-interest, or you'll lose that information, which is called the "Nyquist Sampling Rate" (look it up). If you're sampling an event that's over in 10 microseconds at a rate of 40kHz, then each sample is AVERAGED over 25microseconds - you get ONE SAMPLE, ONE NUMBER, JUST ONE, to "characterize" that "waveform". Here's your digital audio file that characterizes a detonation - "0, 0, 0, MAXVAL, 0, 0, 0,...".
Plotted, it looks like "_____|_____".
That "N-shaped curve" is what you get from that ____|____ reflecting off the environment. Each reflection is less than the original pulse, and delayed due to the extra pathlength it has to travel, and if the environment is contiguous, then the spikes all overlap, diminishing in size with time, and that's where that downward "N" slope comes from, reflections from the environment.
And that is therefore an ARTIFACT of the ENVIRONMENT, not a CHARACTERISTIC of the DETONATION.
LEARN SOMETHING OR CONTINUE TO LIVE YOUR LIFE IN TOTAL IGNORANCE.
It's your call, and I frankly don't care which choice you make.
Since you can't do math, here's an example:
If it detonates at 26,400 feet-per-second, and the detonator is midway in a four-inch block of C-4, then the maximum distance the detonation can go before it runs out of C-4 is about three inches. Three inches at 26,400 feet/second takes 0.25feet/(26,400 feet/second) or about 10microseconds.
Is that clear enough for you?
Whatever "characteristic waveform" that a block of C-4 detonating might have, you'd better sample at twice the highest frequency-of-interest, or you'll lose that information, which is called the "Nyquist Sampling Rate" (look it up). If you're sampling an event that's over in 10 microseconds at a rate of 40kHz, then each sample is AVERAGED over 25microseconds - you get ONE SAMPLE, ONE NUMBER, JUST ONE, to "characterize" that "waveform". Here's your digital audio file that characterizes a detonation - "0, 0, 0, MAXVAL, 0, 0, 0,...".
Plotted, it looks like "_____|_____".
That "N-shaped curve" is what you get from that ____|____ reflecting off the environment. Each reflection is less than the original pulse, and delayed due to the extra pathlength it has to travel, and if the environment is contiguous, then the spikes all overlap, diminishing in size with time, and that's where that downward "N" slope comes from, reflections from the environment.
And that is therefore an ARTIFACT of the ENVIRONMENT, not a CHARACTERISTIC of the DETONATION.
LEARN SOMETHING OR CONTINUE TO LIVE YOUR LIFE IN TOTAL IGNORANCE.
It's your call, and I frankly don't care which choice you make.
QUOTE (OneWhiteEye+Nov 5 2007, 02:03 AM)
http://i24.tinypic.com/2zobyqg.png
http://i24.tinypic.com/1zoujyd.png
Does this alter the distance estimate of 1600 meters?
http://i24.tinypic.com/1zoujyd.png
Does this alter the distance estimate of 1600 meters?
QUOTE (David B. Benson+Nov 6 2007, 10:48 PM)
Does this alter the distance estimate of 1600 meters?
Not necessarily. I don't know how that estimate was obtained; the page it was from may tell. Varick Street is the wrong location, but 101 AofA is the right building and they were pretty close on the distance.
Taking data FROM a raytrace scene is a little backward but, given the level of corroboration from the map, it already has to be pretty close. I don't know yet whether it's a better estimate than the other, though I think it will be so after further work to refine the scene geometry and fix a couple of known problems.
The origin in the scene is ground level at the vertical axis of the tower. The camera is at ground level (one and a half feet up but call it ground).
If my calculations are correct:
- radial distance along ground to the camera location is 1545m
- azimuthal angle of camera location is 3.57 degrees, relative to plane of north wall
- elevation angle of center line of sight is 14.0 degrees
- azimuthal angle of center line of sight is 4.89 degrees
- angle between line of sight and antenna base position (assumed 1368 ft roof height) is 1.65 degrees
EDIT: if I make the camera height 4 feet instead of 1.5, the distance between the camera and the base of the antenna comes out as... 1600 meters.
Not necessarily. I don't know how that estimate was obtained; the page it was from may tell. Varick Street is the wrong location, but 101 AofA is the right building and they were pretty close on the distance.
Taking data FROM a raytrace scene is a little backward but, given the level of corroboration from the map, it already has to be pretty close. I don't know yet whether it's a better estimate than the other, though I think it will be so after further work to refine the scene geometry and fix a couple of known problems.
The origin in the scene is ground level at the vertical axis of the tower. The camera is at ground level (one and a half feet up but call it ground).
If my calculations are correct:
- radial distance along ground to the camera location is 1545m
- azimuthal angle of camera location is 3.57 degrees, relative to plane of north wall
- elevation angle of center line of sight is 14.0 degrees
- azimuthal angle of center line of sight is 4.89 degrees
- angle between line of sight and antenna base position (assumed 1368 ft roof height) is 1.65 degrees
EDIT: if I make the camera height 4 feet instead of 1.5, the distance between the camera and the base of the antenna comes out as... 1600 meters.
1600 meter.. The strange thing is that there is almost no sound no that video, also not with a few seconds delay, only a few people screaming in the neighborhood, however I found an other one from a slightly different position and that was from a Penn & Teller show, it contained a tremendous sound although it was damped and overdubbed with a narrator. Some people think that audio is fake.
QUOTE (David B. Benson+Nov 5 2007, 07:16 PM)
Yes, but the 52 m/s is essentially the value from the BLGB paper, wherein structural resistance, concrete comminution and moving air out are all taken into account. This gives a crush-down time of about 13 seconds for WTC 1, in good agreement with the seismograph data.
Did they consider mass shedding?
Did they consider mass shedding?
QUOTE (shagster+Nov 7 2007, 08:02 AM)
Did they consider mass shedding?
Yes.
Yes.
QUOTE (David B. Benson+Nov 7 2007, 06:40 PM)
Yes.
What percentage of mass shedding was used?
What percentage of mass shedding was used?
QUOTE (shagster+Nov 7 2007, 12:43 PM)
What percentage of mass shedding was used?
20%
20%
QUOTE (metamars+Oct 23 2007, 04:30 AM)
I've taken a look, in the last couple of days, at a paper called Experimental and Theoretical Studies of Columns Under Axial Impact by Ari-Gur, Weller and Singer (pub. in Int. J. Solids Structures Vol. 18 No. 7 pp619-641 1982)
A 'Dynamic Load Amplification Factor' (DLF) is defined, as the ratio of the dynamic buckling strain divided by the static buckling strain.
Sorry, this is incorrect. DLF is the critical dynamic buckling strain divided by the critical static buckling strain.
These are the areas where the strain vs. stress curves turn sharply upwards.
A 'Dynamic Load Amplification Factor' (DLF) is defined, as the ratio of the dynamic buckling strain divided by the static buckling strain.
Sorry, this is incorrect. DLF is the critical dynamic buckling strain divided by the critical static buckling strain.
These are the areas where the strain vs. stress curves turn sharply upwards.
QUOTE (metamars+Nov 7 2007, 02:18 PM)
These are the areas where the strain vs. stress curves turn sharply upwards.
Typically strain is the abscissa and stress is the ordinate in stress-strain diagrams. Presented in that fashion, as strain increases, so does stress to the yield point, after which stress declines with increased strain until a minimum is reached and after that stress increases to the maximum inelastic stress with increased strain. For steel, still further increased strain is associated with declining stress until tensile failure.
Typically strain is the abscissa and stress is the ordinate in stress-strain diagrams. Presented in that fashion, as strain increases, so does stress to the yield point, after which stress declines with increased strain until a minimum is reached and after that stress increases to the maximum inelastic stress with increased strain. For steel, still further increased strain is associated with declining stress until tensile failure.
Trippy - Never during my professional audio career did I meet the word "sonogram," yet the term is parroted around here as if it is some kind of specialist vernacular.
It is not.
Also, since you refused to provide a much needed contextual reference for the first graph you posted (the one mapping amplitude of an infrasonic pulse over time) I must refuse to submit to your distractions.
This policy must also apply to wcelliot, who refuses to reference (1) his 10 microsecond blast pulse assertion that contradicts the 3.3 millisecond pulse posted by Arthur, (2) DARPAs request for development of a microphone for recording explosions, and (3) propogation of sound in air as direct current bias offset.(!)
When you have both demonstrated a willingness to reference your unusual claims and participate in a fair and scientific manner, I will reconsider.
Arthur:
================
No, being burnt and thrown to the ground by the collapse of a flaming building...
================
So -- let me get this right -- people who were running from the tower while it collapsed were burnt by flames that shot out of the tower at street level - is that what you are saying?
Or was it the burning upper levels that errupted in flames on collision with the ground?
Given that so many people reported blasts of warm or hot air following collapse, what does the word "pyroclastic" mean?
=========
What I would be surprised is for these people to have survived blasts created by actual HIGH EXPLOSIVES.
=========
Here's a surprise for you then:
======================
As OCT'ers have been pointing out for years, the RATE of fall of the towers was much slower than free fall
======================
Within the last dozen pages I have reminded you again of Kausel's near free fall computation on behalf of the OCT camp. Perhaps you are in need of another reminder.
Yet you feel the need to respond to my posts!
Yet you feel the need to respond to my posts!
The facts are that a Plane carrying many THOUSANDS of gallons of JET FUEL crashed into the building that had ELEVATOR SHAFTS that went all the way to the BASEMENT.
It is not.
Also, since you refused to provide a much needed contextual reference for the first graph you posted (the one mapping amplitude of an infrasonic pulse over time) I must refuse to submit to your distractions.
This policy must also apply to wcelliot, who refuses to reference (1) his 10 microsecond blast pulse assertion that contradicts the 3.3 millisecond pulse posted by Arthur, (2) DARPAs request for development of a microphone for recording explosions, and (3) propogation of sound in air as direct current bias offset.(!)
When you have both demonstrated a willingness to reference your unusual claims and participate in a fair and scientific manner, I will reconsider.
Arthur:
================
No, being burnt and thrown to the ground by the collapse of a flaming building...
================
So -- let me get this right -- people who were running from the tower while it collapsed were burnt by flames that shot out of the tower at street level - is that what you are saying?
Or was it the burning upper levels that errupted in flames on collision with the ground?
Given that so many people reported blasts of warm or hot air following collapse, what does the word "pyroclastic" mean?
=========
What I would be surprised is for these people to have survived blasts created by actual HIGH EXPLOSIVES.
=========
Here's a surprise for you then:
QUOTE
SPC. JOSE MARTINEZ, 20, 101st Airborne, was injured April 5, 2003 in Karbala when the humvee he was driving hit a land mine. Martinez was trapped in the explosion and suffered massive burns to his face, head and body.
Disposable Heroes, Peter Howe
Visit the Walter Reed Army Medical Center for more big surprises.Disposable Heroes, Peter Howe
======================
As OCT'ers have been pointing out for years, the RATE of fall of the towers was much slower than free fall
======================
Within the last dozen pages I have reminded you again of Kausel's near free fall computation on behalf of the OCT camp. Perhaps you are in need of another reminder.
QUOTE (->
| QUOTE |
| SPC. JOSE MARTINEZ, 20, 101st Airborne, was injured April 5, 2003 in Karbala when the humvee he was driving hit a land mine. Martinez was trapped in the explosion and suffered massive burns to his face, head and body. Disposable Heroes, Peter Howe |
Visit the Walter Reed Army Medical Center for more big surprises.
======================
As OCT'ers have been pointing out for years, the RATE of fall of the towers was much slower than free fall
======================
Within the last dozen pages I have reminded you again of Kausel's near free fall computation on behalf of the OCT camp. Perhaps you are in need of another reminder.
Eduardo Kausel proposed an alternative failure explanation that he acknowledged was independently developed by Zdenek Bazant*, a professor at Northwestern University. "I believe that the intense heat softened or melted the structural elements—floor trusses and columns— so that they became like chewing gum, and that was enough to trigger the collapse," he said.
- Steven Ashley, When the Twin Towers Fell, Scientific American, October 09, 2001
As people on both sides of the debate have been pointing out for years, the rate at which the towers fell was, quote, "nearly the speed of free-falling objects."
============================
Flashback:
common sense:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Yet none of you can explain your thermite nonsense. How did the thermite burn SIDEWAYS through the steel?
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Linear_Thermite.jpg
======================
As OCT'ers have been pointing out for years, the RATE of fall of the towers was much slower than free fall
======================
Within the last dozen pages I have reminded you again of Kausel's near free fall computation on behalf of the OCT camp. Perhaps you are in need of another reminder.
Eduardo Kausel proposed an alternative failure explanation that he acknowledged was independently developed by Zdenek Bazant*, a professor at Northwestern University. "I believe that the intense heat softened or melted the structural elements—floor trusses and columns— so that they became like chewing gum, and that was enough to trigger the collapse," he said.
- Steven Ashley, When the Twin Towers Fell, Scientific American, October 09, 2001
QUOTE
[Kausel] also performed some computer simulations that indicate the building material fell almost unrestricted at nearly the speed of free-falling objects.
"The towers' resistive systems played no role. Otherwise the elapsed time of the fall would have been extended," he noted. As it was, the debris took about nine seconds to reach the ground from the top.
- Steven Ashley, When the Twin Towers Fell, Scientific American, October 09, 2001
"The towers' resistive systems played no role. Otherwise the elapsed time of the fall would have been extended," he noted. As it was, the debris took about nine seconds to reach the ground from the top.
- Steven Ashley, When the Twin Towers Fell, Scientific American, October 09, 2001
As people on both sides of the debate have been pointing out for years, the rate at which the towers fell was, quote, "nearly the speed of free-falling objects."
============================
Flashback:
common sense:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Yet none of you can explain your thermite nonsense. How did the thermite burn SIDEWAYS through the steel?
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Linear_Thermite.jpg
Al -
Are you having trouble reading? I posted the speed of detonation for C-4 once (after telling you that it'd already been posted here) telling YOU to do the math and see if YOU come up with something other than 10 microseconds, and you asserted that the 10 microsecond figure was unsupported, so *I* posted a reference for the detonation rate and *I* did the math, which supported the 10microsecond figure, and AGAIN you claim that the 10microsecond figure is unsupported.
You apparently CAN'T READ.
And the "DC component" of a spectrum is routine language of the art, everyone (except you) understand it to refer to the zeroth-order component of a spectrum. Given the choice of "DC" or "zeroth-order component of a spectrum", I'll continue to use "DC" for the spectral component at zero frequency.
You're still apparently unfamiliar with "undersampling" and "clipping", which are common terms in the audio world, so maybe your claims of being someone with special expertise in acoustics are BS.
Like everything else you say.
Are you having trouble reading? I posted the speed of detonation for C-4 once (after telling you that it'd already been posted here) telling YOU to do the math and see if YOU come up with something other than 10 microseconds, and you asserted that the 10 microsecond figure was unsupported, so *I* posted a reference for the detonation rate and *I* did the math, which supported the 10microsecond figure, and AGAIN you claim that the 10microsecond figure is unsupported.
You apparently CAN'T READ.
And the "DC component" of a spectrum is routine language of the art, everyone (except you) understand it to refer to the zeroth-order component of a spectrum. Given the choice of "DC" or "zeroth-order component of a spectrum", I'll continue to use "DC" for the spectral component at zero frequency.
You're still apparently unfamiliar with "undersampling" and "clipping", which are common terms in the audio world, so maybe your claims of being someone with special expertise in acoustics are BS.
Like everything else you say.
QUOTE (Al Khwarizmi - step-by-step+Nov 8 2007, 04:12 AM)
Arthur:
================
No, being burnt and thrown to the ground by the collapse of a flaming building...
================
So -- let me get this right -- people who were running from the tower while it collapsed were burnt by flames that shot out of the tower at street level - is that what you are saying?
Or was it the burning upper levels that errupted in flames on collision with the ground?
Given that so many people reported blasts of warm or hot air following collapse, what does the word "pyroclastic" mean?
=========
What I would be surprised is for these people to have survived blasts created by actual HIGH EXPLOSIVES.
=========
Here's a surprise for you then: Visit the Walter Reed Army Medical Center for more big surprises.
Yes, there were many more than 5 floors on fire in each tower.
So its no surprise that given the many shafts that ran all the way to the ground floor coupled with the rapid rate of collapse, that the air, at times, as it got expelled would have been very hot, to capable of creating burns.
We saw ground level fires start around the WTC, but we also saw lots of paper, so NO, it clearly wasn't a pyroclastic flow, but that doesn't mean that some people wouldn't get burned.
What is NOT supported is EXPLOSIVES at ground level since its clear the collapse began AT the impact zone and propogated downward.
As to your reference to the war victims, of course since Humvees have GASOLINE tanks, so YES one can get burnt
It does NOT say, he was burnt BY the explosion.
Arthur
================
No, being burnt and thrown to the ground by the collapse of a flaming building...
================
So -- let me get this right -- people who were running from the tower while it collapsed were burnt by flames that shot out of the tower at street level - is that what you are saying?
Or was it the burning upper levels that errupted in flames on collision with the ground?
Given that so many people reported blasts of warm or hot air following collapse, what does the word "pyroclastic" mean?
=========
What I would be surprised is for these people to have survived blasts created by actual HIGH EXPLOSIVES.
=========
Here's a surprise for you then: Visit the Walter Reed Army Medical Center for more big surprises.
Yes, there were many more than 5 floors on fire in each tower.
So its no surprise that given the many shafts that ran all the way to the ground floor coupled with the rapid rate of collapse, that the air, at times, as it got expelled would have been very hot, to capable of creating burns.
We saw ground level fires start around the WTC, but we also saw lots of paper, so NO, it clearly wasn't a pyroclastic flow, but that doesn't mean that some people wouldn't get burned.
What is NOT supported is EXPLOSIVES at ground level since its clear the collapse began AT the impact zone and propogated downward.
As to your reference to the war victims, of course since Humvees have GASOLINE tanks, so YES one can get burnt
QUOTE
when the humvee he was driving hit a land mine. Martinez was trapped in the explosion
It does NOT say, he was burnt BY the explosion.
Arthur
QUOTE (Al Khwarizmi - step-by-step+Nov 8 2007, 04:12 AM)
======================
As OCT'ers have been pointing out for years, the RATE of fall of the towers was much slower than free fall
======================
Within the last dozen pages I have reminded you again of Kausel's near free fall computation on behalf of the OCT camp. Perhaps you are in need of another reminder.
QUOTE
Eduardo Kausel proposed an alternative failure explanation that he acknowledged was independently developed by Zdenek Bazant*, a professor at Northwestern University. "I believe that the intense heat softened or melted the structural elements—floor trusses and columns— so that they became like chewing gum, and that was enough to trigger the collapse," he said.
- Steven Ashley, When the Twin Towers Fell, Scientific American, October 09, 2001
QUOTE
[Kausel] also performed some computer simulations that indicate the building material fell almost unrestricted at nearly the speed of free-falling objects.
"The towers' resistive systems played no role. Otherwise the elapsed time of the fall would have been extended," he noted. As it was, the debris took about nine seconds to reach the ground from the top.
- Steven Ashley, When the Twin Towers Fell, Scientific American, October 09, 2001
As people on both sides of the debate have been pointing out for years, the rate at which the towers fell was, quote, "nearly the speed of free-falling objects."
============================
Who cares what Kausel wrote in Oct of 2001?
Kausel was WRONG.
Since this time we have developed much better estimates of collapse time and clearly the RATE of fall of the towers was much slower than free fall.
But go on Al, keep beating this dead horse.
Arthur
As OCT'ers have been pointing out for years, the RATE of fall of the towers was much slower than free fall
======================
Within the last dozen pages I have reminded you again of Kausel's near free fall computation on behalf of the OCT camp. Perhaps you are in need of another reminder.
QUOTE
Eduardo Kausel proposed an alternative failure explanation that he acknowledged was independently developed by Zdenek Bazant*, a professor at Northwestern University. "I believe that the intense heat softened or melted the structural elements—floor trusses and columns— so that they became like chewing gum, and that was enough to trigger the collapse," he said.
- Steven Ashley, When the Twin Towers Fell, Scientific American, October 09, 2001
QUOTE
[Kausel] also performed some computer simulations that indicate the building material fell almost unrestricted at nearly the speed of free-falling objects.
"The towers' resistive systems played no role. Otherwise the elapsed time of the fall would have been extended," he noted. As it was, the debris took about nine seconds to reach the ground from the top.
- Steven Ashley, When the Twin Towers Fell, Scientific American, October 09, 2001
As people on both sides of the debate have been pointing out for years, the rate at which the towers fell was, quote, "nearly the speed of free-falling objects."
============================
Who cares what Kausel wrote in Oct of 2001?
Kausel was WRONG.
Since this time we have developed much better estimates of collapse time and clearly the RATE of fall of the towers was much slower than free fall.
But go on Al, keep beating this dead horse.
Arthur
QUOTE (Al Khwarizmi - step-by-step+Nov 8 2007, 04:12 AM)
============================
Flashback:
common sense:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Yet none of you can explain your thermite nonsense. How did the thermite burn SIDEWAYS through the steel?
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Linear_Thermite.jpg
EXCEPT what is pictured there is MOSTLY the UNIT that contains the Thermite.
That line on the side is where the hot jet of molten steel comes out to do the cutting.
So, had THESE been used to cut a sufficient number of columns, sufficient enough to MAKE A DIFFERENCE to the towers, than its HIGHLY LIKELY that at least one would have survived the collapse. (not to mention the extreme difficulty of installing a sufficient number of these in each of the towers without being detected)
But, alas Al, none were found.
Arthur
Flashback:
common sense:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Yet none of you can explain your thermite nonsense. How did the thermite burn SIDEWAYS through the steel?
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Linear_Thermite.jpg
EXCEPT what is pictured there is MOSTLY the UNIT that contains the Thermite.
That line on the side is where the hot jet of molten steel comes out to do the cutting.
So, had THESE been used to cut a sufficient number of columns, sufficient enough to MAKE A DIFFERENCE to the towers, than its HIGHLY LIKELY that at least one would have survived the collapse. (not to mention the extreme difficulty of installing a sufficient number of these in each of the towers without being detected)
But, alas Al, none were found.
Arthur
QUOTE (Al Khwarizmi - step-by-step+Nov 8 2007, 09:12 PM)
Trippy - Never during my professional audio career did I meet the word "sonogram," yet the term is parroted around here as if it is some kind of specialist vernacular.
It is not.
Also, since you refused to provide a much needed contextual reference for the first graph you posted (the one mapping amplitude of an infrasonic pulse over time) I must refuse to submit to your distractions.
You claim to be a professional, and yet you do not know this simple piece of information.
The term 'Sonogram' is used interchangeably with the term 'Spectrogram' and the instrument that provides the spectrogram is a 'Sonograph'. I think that the most ridiculous and ironic part of this particular conversation is that, IIRC, it was one of your fellow conspirators that first broached the subject.
But I'll bite.
Here's the wiki reference on Spectrogram which is accessable from the Sonogram disambiguation page.
Here and here are two pieces of software for creating and analyzing sonograms that refer to them as such.
Here's a bunch of references to spectrograms in general, seeing as how your "Feild of expertese" apparently doesn't include them:
http://www.visualizationsoftware.com/gram.html
http://cslu.cse.ogi.edu/tutordemos/Spectro...pectrogram.html
http://www.skysweep.com/spectrogram.htm
http://www.baudline.com/
http://home.cc.umanitoba.ca/~robh/howto.html
http://www.exploratorium.com/xref/exhibits...pectrogram.html
As for your false accusations of avoiding answering your questions, I have already answered your questions to the best of my ability. The (first) spectrogram that I posted was recorded from the detonation of a significant amount of (unexploded) ordanance, and the spectrogram was recorded from a distance of a couple of kilometers. That is all the information I can remember, and I do not have the original site bookmarked (as I stated the first time round).
I have answered your questions to the best of my abilities (for a second time), now, be so kind as to return the favour and address the second spetrogram/sonogram that I posted. Continued failure to do so can only be construed as an admission that you are wrong, we will be forced to interpret your unwillingness to do so as an admission that all single impulse sounds share the same features, irrespective of whether you're talking about a drum beat, or the detonation of C4, thusly claiming that a sonogram is evidence of controled demolition because they "look the same" is significantly in error.
Oh, and for the billionth time, it was me that provided WCElliot with the information about the ten microsecond pulse. And as I have previously stated, that paticular piece of information is freely available on the net.
It is not.
Also, since you refused to provide a much needed contextual reference for the first graph you posted (the one mapping amplitude of an infrasonic pulse over time) I must refuse to submit to your distractions.
You claim to be a professional, and yet you do not know this simple piece of information.
The term 'Sonogram' is used interchangeably with the term 'Spectrogram' and the instrument that provides the spectrogram is a 'Sonograph'. I think that the most ridiculous and ironic part of this particular conversation is that, IIRC, it was one of your fellow conspirators that first broached the subject.
But I'll bite.
Here's the wiki reference on Spectrogram which is accessable from the Sonogram disambiguation page.
Here and here are two pieces of software for creating and analyzing sonograms that refer to them as such.
Here's a bunch of references to spectrograms in general, seeing as how your "Feild of expertese" apparently doesn't include them:
http://www.visualizationsoftware.com/gram.html
http://cslu.cse.ogi.edu/tutordemos/Spectro...pectrogram.html
http://www.skysweep.com/spectrogram.htm
http://www.baudline.com/
http://home.cc.umanitoba.ca/~robh/howto.html
http://www.exploratorium.com/xref/exhibits...pectrogram.html
As for your false accusations of avoiding answering your questions, I have already answered your questions to the best of my ability. The (first) spectrogram that I posted was recorded from the detonation of a significant amount of (unexploded) ordanance, and the spectrogram was recorded from a distance of a couple of kilometers. That is all the information I can remember, and I do not have the original site bookmarked (as I stated the first time round).
I have answered your questions to the best of my abilities (for a second time), now, be so kind as to return the favour and address the second spetrogram/sonogram that I posted. Continued failure to do so can only be construed as an admission that you are wrong, we will be forced to interpret your unwillingness to do so as an admission that all single impulse sounds share the same features, irrespective of whether you're talking about a drum beat, or the detonation of C4, thusly claiming that a sonogram is evidence of controled demolition because they "look the same" is significantly in error.
Oh, and for the billionth time, it was me that provided WCElliot with the information about the ten microsecond pulse. And as I have previously stated, that paticular piece of information is freely available on the net.
QUOTE (Al Khwarizmi - step-by-step+Nov 8 2007, 01:12 AM)
======================
As OCT'ers have been pointing out for years, the RATE of fall of the towers was much slower than free fall
======================
As people on both sides of the debate have been pointing out for years, the rate at which the towers fell was, quote, "nearly the speed of free-falling objects."
An object falling under the influence of gravity alone does not have a single rate of fall. The acceleration is constant (for an object near the surface of the earth) and the speed grows proportional to the time of free-fall. Light objects, in air, often quickly reach a terminal speed at which air resistance exactly matches the force of gravity. For an old-fashioned cannon ball that is about 110 m/s.
A good approximation for the first 3 seconds of the collapse of WTC 1 is a constant acceleration of (2/3)g, where g is the acceleration due to gravity. This indicates a substantial resistance to the fall, hence not nearly free-fall.
As OCT'ers have been pointing out for years, the RATE of fall of the towers was much slower than free fall
======================
As people on both sides of the debate have been pointing out for years, the rate at which the towers fell was, quote, "nearly the speed of free-falling objects."
An object falling under the influence of gravity alone does not have a single rate of fall. The acceleration is constant (for an object near the surface of the earth) and the speed grows proportional to the time of free-fall. Light objects, in air, often quickly reach a terminal speed at which air resistance exactly matches the force of gravity. For an old-fashioned cannon ball that is about 110 m/s.
A good approximation for the first 3 seconds of the collapse of WTC 1 is a constant acceleration of (2/3)g, where g is the acceleration due to gravity. This indicates a substantial resistance to the fall, hence not nearly free-fall.
The first time that I heard about the conspiracy theories I also used the free-fall argument, because there are a lot of lies on the internet mentioning free-fall, I even made a youtube animation about it. Afterwards I couldn't believe that people came to that conclusion because the initial acceleration is absolutely not g. And even if a shadow team was able to put explosives in a building they wouldn't be stupid and detonate it with g.
QUOTE (Al Khwarizmi - step-by-step+Nov 8 2007, 09:12 PM)
============================
Flashback:
common sense:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Yet none of you can explain your thermite nonsense. How did the thermite burn SIDEWAYS through the steel?
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Linear_Thermite.jpg
I find this part of the post especially amusing, because it was not that long ago that Al was trying to convince me that devices such as this did not exist, and were not used in the transport of materials out of ground zero.
Flashback:
common sense:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Yet none of you can explain your thermite nonsense. How did the thermite burn SIDEWAYS through the steel?
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Linear_Thermite.jpg
I find this part of the post especially amusing, because it was not that long ago that Al was trying to convince me that devices such as this did not exist, and were not used in the transport of materials out of ground zero.
Computer Program for simulation of WTC collapses available here:
http://math.uni-graz.at/keeling/wtc.html
Math behind the software here:
http://math.uni-graz.at/keeling/wtc2.html
Web pages by:
Stephen Keeling
Institute for Mathematics and Scientific Computing
Karl-Franzens University of Graz
A-8010 Graz, Austria
I've only glanced at this.
http://math.uni-graz.at/keeling/wtc.html
Math behind the software here:
http://math.uni-graz.at/keeling/wtc2.html
Web pages by:
Stephen Keeling
Institute for Mathematics and Scientific Computing
Karl-Franzens University of Graz
A-8010 Graz, Austria
I've only glanced at this.
QUOTE (metamars+Nov 8 2007, 10:18 PM)
Computer Program for simulation of WTC collapses available here
"It remains for the user to decide whether the pancake collapse theory agrees with the recorded free fall times."
He needs to bring himself up to date.
He needs to bring himself up to date.
QUOTE (shagster+Nov 8 2007, 04:34 PM)
"It remains for the user to decide whether the pancake collapse theory agrees with the recorded free fall times."
He needs to bring himself up to date.
Hiss e-mail address is listed on his site. You might want to inform him.
He needs to bring himself up to date.
Hiss e-mail address is listed on his site. You might want to inform him.
QUOTE
Sorry Stundie, my life work is not to answer your questions.
Yet you feel the need to respond to my posts!
QUOTE (->
| QUOTE |
| Sorry Stundie, my life work is not to answer your questions. |
Yet you feel the need to respond to my posts!
The facts are that a Plane carrying many THOUSANDS of gallons of JET FUEL crashed into the building that had ELEVATOR SHAFTS that went all the way to the BASEMENT.
This is not a fact then is it. Its YOUR ASSUMPTION!!Let me explain it too you Arthur as you are struggling here....
If it was a fact, then you would be able to provide the proof...You do not, so it's an assumption on your behalf....its what you believe!
If it was a fact, then you would be able to provide the proof...You do not, so it's an assumption on your behalf....its what you believe!
QUOTE
The crash caused damage to the CENTRAL CORE which included the ELEVATOR SHAFTS.
How much damage?QUOTE (->
| QUOTE |
| The crash caused damage to the CENTRAL CORE which included the ELEVATOR SHAFTS. |
How much damage?
The fuel entered the building at HIGH RATE OF SPEED and was thus mixed/distributed with great force.
Yes and most of it burned off in the initial impact fireball. So please tell us how much was left and where and how it traveled according to your crackpot theory??
The fuel entered the building at HIGH RATE OF SPEED and was thus mixed/distributed with great force.
Yes and most of it burned off in the initial impact fireball. So please tell us how much was left and where and how it traveled according to your crackpot theory??
QUOTE
There were fires seen near a number of Elevator doors (see NIST report)
And this proves what...there were fires near a number of elevator doors...nothing else?QUOTE (->
| QUOTE |
| There were fires seen near a number of Elevator doors (see NIST report) |
And this proves what...there were fires near a number of elevator doors...nothing else?
There were fires seen coming out of Elevator shafts (see NUMEROUS reports)
There were fires seen coming out of Elevator shafts (see NUMEROUS reports)
Again, you should be able to source reports but for some reason, you cannot. I'm sure if you could, you would take the time to make me look stupid and prove me wrong.
QUOTE
There were people burnt by Elevator doors (see numerous reports).
People burnt by elevator doors?? That's a new one!! I though they were burnt by fire. QUOTE (->
| QUOTE |
| There were people burnt by Elevator doors (see numerous reports). |
People burnt by elevator doors?? That's a new one!! I though they were burnt by fire.
We KNOW that fuel would be forced down the shafts and we know that fuel/air can be EXPLOSIVE.
Who is "We" which you are referring too when you says "We KNOW" ?? Where is your EVIDENCE again?? Lets face it, you assume this happened and yes we all know that fuel/air can explode, but you haven't a single piece of scientific evidence to prove this....and yet you BELIEVE it. Hilarious stuff!! hahahahahaha!!!
Maybe you should try backing it up with this thing called EVIDENCE, which you tend to ignore when supporting your own loony theories but demand it for ANY other theories. Even if it's only to dismiss it when presented.
We KNOW that fuel would be forced down the shafts and we know that fuel/air can be EXPLOSIVE.
Who is "We" which you are referring too when you says "We KNOW" ?? Where is your EVIDENCE again?? Lets face it, you assume this happened and yes we all know that fuel/air can explode, but you haven't a single piece of scientific evidence to prove this....and yet you BELIEVE it. Hilarious stuff!! hahahahahaha!!!
QUOTE
These FIRE related events all happened CONCURRENT with the plane's impact and ONLY in the tower where the impact intersected the Elevator Shafts.
Your statements are too funny!!Maybe you should try backing it up with this thing called EVIDENCE, which you tend to ignore when supporting your own loony theories but demand it for ANY other theories. Even if it's only to dismiss it when presented.
QUOTE (->
| QUOTE |
| These FIRE related events all happened CONCURRENT with the plane's impact and ONLY in the tower where the impact intersected the Elevator Shafts. |
Your statements are too funny!!
Maybe you should try backing it up with this thing called EVIDENCE, which you tend to ignore when supporting your own loony theories but demand it for ANY other theories. Even if it's only to dismiss it when presented.
What we DON'T have any evidence for is any OTHER source of explosions.
NONE
ZERO
NADA
ZIP
ZILCH
Maybe you should try backing it up with this thing called EVIDENCE, which you tend to ignore when supporting your own loony theories but demand it for ANY other theories. Even if it's only to dismiss it when presented.
What we DON'T have any evidence for is any OTHER source of explosions.
NONE
ZERO
NADA
ZIP
ZILCH
So you admit (Finally!) that you do not have any evidence for the source of the explosions?? So how does this then disprove the explosives theory then?? hahahahahaha!!!
I have posted Sonograms which show similar spikes in the frequency to that of other Demolitions but you ignored it!!
I have posted video of explosions at GZ after the collapses of WTC 1 & 2 but before WTC 7 but you ignored it.
So if I post this video which shows plumes of smoke coming from the ground before the collapse of the WTC you will ignore it.
If I show you evidence that squibs can be seen detonating during the collapse and these are associated with controlled demolitions, you will ignore it.
If I post this video of WTC 7 in which you can hear 2 explosions before it collapses(Goto 4:28) you will ignore it.
You say the explosions could be anything, so when I ask for proof/evidence to support your claims, you ignore it.
What did George Orwell have to say about ignorance?? Please tell us Arthur, is it bliss??
QUOTE
If you want to claim there were explosions then simply provide EVIDENCE to support your claims.
I have posted Sonograms which show similar spikes in the frequency to that of other Demolitions but you ignored it!!
I have posted video of explosions at GZ after the collapses of WTC 1 & 2 but before WTC 7 but you ignored it.
So if I post this video which shows plumes of smoke coming from the ground before the collapse of the WTC you will ignore it.
If I show you evidence that squibs can be seen detonating during the collapse and these are associated with controlled demolitions, you will ignore it.
If I post this video of WTC 7 in which you can hear 2 explosions before it collapses(Goto 4:28) you will ignore it.
You say the explosions could be anything, so when I ask for proof/evidence to support your claims, you ignore it.
What did George Orwell have to say about ignorance?? Please tell us Arthur, is it bliss??
It was me that mentioned the Sonograms in regards to a post that Arthur made and I agree with what you have said with the exception of this little nugget which I have major problems with. Trippy you say this...?
QUOTE (Trippy+)
Continued failure to do so can only be construed as an admission that you are wrong, we will be forced to interpret your unwillingness to do so as an admission that all single impulse sounds share the same features, irrespective of whether you're talking about a drum beat, or the detonation of C4, thusly claiming that a sonogram is evidence of controlled demolition because they "look the same" is significantly in error.
Would you agree a sonogram looks at the amplitude, frequency and time parameters?? A Yes or No answer will do.
If you are answering Yes, then for that statement to be correct, you are suggesting that a drum beat & detonation of C4 share the same frequency and amplitude?? Hence the sonogram can't detect the difference?? lol
If you are answering No, then please explain what a sonogram consists off and why it can't detect the difference between a drum beat and C4 exploding.
Because to be honest Trippy, I'm calling BS on you....again.
Another thing which makes your statement look EVEN more ridiculous is the wikipedia entry which states:-
So it can be used for all these things, but according to you, it can't be used to detect the difference between a drum beat and C4 exploding?? hahahahahahaha!! lol
You should speak with Wcelliot too, according to him, he was working on a sonogram program which would be able to identify small aircraft by the engine/prop noise. http://forum.physorg.com/index.php?showtop...ndpost&p=275207
So it can be used for all these things, but according to you, it can't be used to detect the difference between a drum beat and C4 exploding?? hahahahahahaha!! lol
You should speak with Wcelliot too, according to him, he was working on a sonogram program which would be able to identify small aircraft by the engine/prop noise. http://forum.physorg.com/index.php?showtop...ndpost&p=275207
I was PROGRAMMING sonogram software for IDENTIFYING small aircraft by their engine/prop-noises back in 1985.
How the hell does a sonogram detect the difference between engine/prop noises, yet according to you Trippy, it can't detect the difference between a wire snapping, a drum beat and C4 going off??
That must mean they share the same frequency, amplitude etc etc.....lol
You are just a terrible liar aren't you Trippy??
Would you agree a sonogram looks at the amplitude, frequency and time parameters?? A Yes or No answer will do.
If you are answering Yes, then for that statement to be correct, you are suggesting that a drum beat & detonation of C4 share the same frequency and amplitude??
Hence the sonogram can't detect the difference?? lolIf you are answering No, then please explain what a sonogram consists off and why it can't detect the difference between a drum beat and C4 exploding.
Because to be honest Trippy, I'm calling BS on you....again.
Another thing which makes your statement look EVEN more ridiculous is the wikipedia entry which states:-
QUOTE
http://en.wikipedia.org/wiki/Spectrogram
Spectrogram's are used to identify phonetic sounds, to analyse the cries of animals, and in the fields of music, sonar/radar, speech processing, etc
Spectrogram's are used to identify phonetic sounds, to analyse the cries of animals, and in the fields of music, sonar/radar, speech processing, etc
So it can be used for all these things, but according to you, it can't be used to detect the difference between a drum beat and C4 exploding?? hahahahahahaha!! lol
You should speak with Wcelliot too, according to him, he was working on a sonogram program which would be able to identify small aircraft by the engine/prop noise. http://forum.physorg.com/index.php?showtop...ndpost&p=275207
QUOTE (->
| QUOTE |
| http://en.wikipedia.org/wiki/Spectrogram Spectrogram's are used to identify phonetic sounds, to analyse the cries of animals, and in the fields of music, sonar/radar, speech processing, etc |
So it can be used for all these things, but according to you, it can't be used to detect the difference between a drum beat and C4 exploding?? hahahahahahaha!! lol
You should speak with Wcelliot too, according to him, he was working on a sonogram program which would be able to identify small aircraft by the engine/prop noise. http://forum.physorg.com/index.php?showtop...ndpost&p=275207
I was PROGRAMMING sonogram software for IDENTIFYING small aircraft by their engine/prop-noises back in 1985.
How the hell does a sonogram detect the difference between engine/prop noises, yet according to you Trippy, it can't detect the difference between a wire snapping, a drum beat and C4 going off??
That must mean they share the same frequency, amplitude etc etc.....lol
You are just a terrible liar aren't you Trippy??
QUOTE (Stundie+)
QUOTE (Arthur+)
The facts are that a Plane carrying many THOUSANDS of gallons of JET FUEL crashed into the building that had ELEVATOR SHAFTS that went all the way to the BASEMENT.
This is not a fact then is it. Its YOUR ASSUMPTION!!Let me explain it too you Arthur as you are struggling here....
If it was a fact, then you would be able to provide the proof...You do not, so it's an assumption on your behalf....its what you believe!
Stundie, considering the above statement, I just have to ask: Are you a "NO PLANE" CTer or a "It wasn't really AA11 that hit WTC 1" CTer????
My answer below assumes you aren't THAT dumb:
I recently provided a 3d layout of the Elevator shafts that showed shafts going from the impact floor all the way to the basement.
The layout of the elevators is well known (and I've in fact documented their layout in this thread (by elevator number, by floors served)
Live video from multiple sources showed the plane hitting the towers.
The amount of fuel the plane was carrying when it hit is well documented.
The amount of fuel burnt outside (~1/3) was calculated by NIST based on their impact analysis and visual analysis and I've seen no serious refutation of their estimates.
The amount of damage done to the core was derived from NIST analysis but is inline with other independent analysis done by the group at Purdue, MIT etc.
I gave links to stories of people burnt by the elevator shafts in the lobby of WTC 1, but others are easily found and have also been covered IN THESE THREADS.
Well, Stundie, nobody can make you look as stupid as you can, yourself.
Trippy's statement is basically correct, impulse events all share the same basic characteristics visible in sonograms, and that is a simultaneous vertical stripe of energy across all frequencies from the zeroth-order all the way up. As I've explained to AlK ad nauseum, explosives detonate really quickly, a lot faster than any audio recorder can fully characterize. C-4 detonates at over 26,000feet/second, so a four-inch block (enough to transect a steel beam) would start-to-finish, detonate in 10 MICROSECONDS.
Maybe you can do the arithmetic that AlK hasn't been able to do, yet, and tell me what the sampling interval associated with a 40kHz sampling rate? (Hint: 1/sampling rate = sampling interval) So how many samples do you expect to have for a 10 MICROSECOND event?
Hint: ___________|_______________
That's what an explosive detonation looks like in the time domain, absent any reflections of the explosion off the local environment. Reflections will be attenuated by several factors, and will always be delayed, so that same ____|____ will bounce around off walls, floors, ceilings, etc., and each reflection will be delayed and smaller, and they'll all add up to that "characteristic N-shape".
The vertical spike is the detonation, the downward "\" slope is just the reflections off the environment, which means that it's ARTIFACT, not an intrinsic CHARACTERISTIC of the detonation itself.
All impulse-driven events have that _______|________ shape in time, and any impulse that reflects around inside a building will sound like an impulse reflecting around inside a building.
As I've explained to AlK a dozen times.
BTW, Prop aircraft have specific numbers of prop-beats/rotation of the engine, and engines in aircraft are either piston or jets, and each sound different. You can count the number of piston-engine exhausts per prop rotation, which will be characteristic for each type of aircraft manufactured, and jet engines have a characteristic frequency associated with the engine rpms and compressor blades/"exhaust buckets", and some planes have jet engines driving props, so there's that characteristic, and different planes have different numbers of engines. All of those sounds reflect off their airframes, which is aspect-dependent. That's how aircraft can be identified (mostly, some planes' characteristics overlap).
And the software that Trippy provided links to were pretty similar, basically, to the software that I'd written way back in 1985 when you were probably still in diapers (when I was a Senior Staff Scientist for Science Applications International Corporation). That was about the same time I designed a digital signal processor to do acoustic beamforming. From scratch, with adder-chips. Under a million-dollar contract based on a ten-page white-paper I wrote.
LOL!!!
This is not a fact then is it. Its YOUR ASSUMPTION!!Let me explain it too you Arthur as you are struggling here....
If it was a fact, then you would be able to provide the proof...You do not, so it's an assumption on your behalf....its what you believe!
Stundie, considering the above statement, I just have to ask: Are you a "NO PLANE" CTer or a "It wasn't really AA11 that hit WTC 1" CTer????
My answer below assumes you aren't THAT dumb:
I recently provided a 3d layout of the Elevator shafts that showed shafts going from the impact floor all the way to the basement.
The layout of the elevators is well known (and I've in fact documented their layout in this thread (by elevator number, by floors served)
Live video from multiple sources showed the plane hitting the towers.
The amount of fuel the plane was carrying when it hit is well documented.
The amount of fuel burnt outside (~1/3) was calculated by NIST based on their impact analysis and visual analysis and I've seen no serious refutation of their estimates.
The amount of damage done to the core was derived from NIST analysis but is inline with other independent analysis done by the group at Purdue, MIT etc.
I gave links to stories of people burnt by the elevator shafts in the lobby of WTC 1, but others are easily found and have also been covered IN THESE THREADS.
QUOTE (Stundie+)
I'm sure if you could, you would take the time to make me look stupid
Why bother? You're doing a GREAT job all by yourself.
Arthur
Why bother? You're doing a GREAT job all by yourself.
Arthur
QUOTE
So it can be used for all these things, but according to you, it can't be used to detect the difference between a drum beat and C4 exploding?? hahahahahahaha!! lol
You should speak with Wcelliot too, according to him, he was working on a sonogram program which would be able to identify small aircraft by the engine/prop noise. http://forum.physorg.com/index.php?showtop...ndpost&p=275207
QUOTE ("Wcelliot")
I was PROGRAMMING sonogram software for IDENTIFYING small aircraft by their engine/prop-noises back in 1985.
How the hell does a sonogram detect the difference between engine/prop noises, yet according to you Trippy, it can't detect the difference between a wire snapping, a drum beat and C4 going off??
That must mean they share the same frequency, amplitude etc etc.....lol
You should speak with Wcelliot too, according to him, he was working on a sonogram program which would be able to identify small aircraft by the engine/prop noise. http://forum.physorg.com/index.php?showtop...ndpost&p=275207
QUOTE ("Wcelliot")
I was PROGRAMMING sonogram software for IDENTIFYING small aircraft by their engine/prop-noises back in 1985.
How the hell does a sonogram detect the difference between engine/prop noises, yet according to you Trippy, it can't detect the difference between a wire snapping, a drum beat and C4 going off??
That must mean they share the same frequency, amplitude etc etc.....lol
Well, Stundie, nobody can make you look as stupid as you can, yourself.
Trippy's statement is basically correct, impulse events all share the same basic characteristics visible in sonograms, and that is a simultaneous vertical stripe of energy across all frequencies from the zeroth-order all the way up. As I've explained to AlK ad nauseum, explosives detonate really quickly, a lot faster than any audio recorder can fully characterize. C-4 detonates at over 26,000feet/second, so a four-inch block (enough to transect a steel beam) would start-to-finish, detonate in 10 MICROSECONDS.
Maybe you can do the arithmetic that AlK hasn't been able to do, yet, and tell me what the sampling interval associated with a 40kHz sampling rate? (Hint: 1/sampling rate = sampling interval) So how many samples do you expect to have for a 10 MICROSECOND event?
Hint: ___________|_______________
That's what an explosive detonation looks like in the time domain, absent any reflections of the explosion off the local environment. Reflections will be attenuated by several factors, and will always be delayed, so that same ____|____ will bounce around off walls, floors, ceilings, etc., and each reflection will be delayed and smaller, and they'll all add up to that "characteristic N-shape".
The vertical spike is the detonation, the downward "\" slope is just the reflections off the environment, which means that it's ARTIFACT, not an intrinsic CHARACTERISTIC of the detonation itself.
All impulse-driven events have that _______|________ shape in time, and any impulse that reflects around inside a building will sound like an impulse reflecting around inside a building.
As I've explained to AlK a dozen times.
BTW, Prop aircraft have specific numbers of prop-beats/rotation of the engine, and engines in aircraft are either piston or jets, and each sound different. You can count the number of piston-engine exhausts per prop rotation, which will be characteristic for each type of aircraft manufactured, and jet engines have a characteristic frequency associated with the engine rpms and compressor blades/"exhaust buckets", and some planes have jet engines driving props, so there's that characteristic, and different planes have different numbers of engines. All of those sounds reflect off their airframes, which is aspect-dependent. That's how aircraft can be identified (mostly, some planes' characteristics overlap).
And the software that Trippy provided links to were pretty similar, basically, to the software that I'd written way back in 1985 when you were probably still in diapers (when I was a Senior Staff Scientist for Science Applications International Corporation). That was about the same time I designed a digital signal processor to do acoustic beamforming. From scratch, with adder-chips. Under a million-dollar contract based on a ten-page white-paper I wrote.
There seems to be someone at the LC forum who went deep into the fuel and elevator shafts theory. It was also posted at the JREF, but due to insults etc it became closed. I'm not the kind of detective to read and go through this, but if anyone is interested
http://z10.invisionfree.com/Loose_Change_F...showtopic=18745
http://z10.invisionfree.com/Loose_Change_F...showtopic=18745
I've read it, but there is nothing new.
He apparently coined a new phrase "a Secret Controlled Demoltion"
Here's his conclusion
If one concedes that the Twin Towers were demolished, than it's safe to say that it wasn't a Controlled Demolition (CD) in the common manner. It was a Secret Controlled Demolition (SCD). A SCD requires a cover legend to make it not look like a demolition. This legend is that the impact damage of the planes and the subsequent fires brought down the towers.
This legend made it necessary to bring down the building from the top (impact zone) to the bottom - unlike most other, non-secret, Controlled Demolitions. To carry out this SCD successfully, it was also necessary that the fires could not have been exstinguished. Exstinguished fires would have destroyed the cover for the Secret Controlled Demolition. The explosions in the basement levels and on floor 22 secured the cover for the whole operation. And therefore were a necessary part of the SCD.
But it turns out, its all a long FAIRY TALE.
Like assuming that an elevator that is out of service IS IN THE BASEMENT.
Arthur
He apparently coined a new phrase "a Secret Controlled Demoltion"
Here's his conclusion
If one concedes that the Twin Towers were demolished, than it's safe to say that it wasn't a Controlled Demolition (CD) in the common manner. It was a Secret Controlled Demolition (SCD). A SCD requires a cover legend to make it not look like a demolition. This legend is that the impact damage of the planes and the subsequent fires brought down the towers.
This legend made it necessary to bring down the building from the top (impact zone) to the bottom - unlike most other, non-secret, Controlled Demolitions. To carry out this SCD successfully, it was also necessary that the fires could not have been exstinguished. Exstinguished fires would have destroyed the cover for the Secret Controlled Demolition. The explosions in the basement levels and on floor 22 secured the cover for the whole operation. And therefore were a necessary part of the SCD.
But it turns out, its all a long FAIRY TALE.
Like assuming that an elevator that is out of service IS IN THE BASEMENT.
Arthur
QUOTE (adoucette+Nov 9 2007, 09:49 AM)
... its all a long FAIRY TALE.
Please do not insult fairy tales.
Please do not insult fairy tales.
I've not read it but I disagree that such a SCD didn't look like a CD. Wtc7's collapse looked exactly like a CD. For the twin towers there is nothing to compare them.
QUOTE
Please do not insult fairy tales.
LOL!!!
QUOTE (stundie+Nov 10 2007, 01:53 AM)
It was me that mentioned the Sonograms in regards to a post that Arthur made and I agree with what you have said with the exception of this little nugget which I have major problems with. Trippy you say this...?
Would you agree a sonogram looks at the amplitude, frequency and time parameters?? A Yes or No answer will do.
If you are answering Yes, then for that statement to be correct, you are suggesting that a drum beat & detonation of C4 share the same frequency and amplitude?? Hence the sonogram can't detect the difference?? lol
If you are answering No, then please explain what a sonogram consists off and why it can't detect the difference between a drum beat and C4 exploding.
Because to be honest Trippy, I'm calling BS on you....again.
Another thing which makes your statement look EVEN more ridiculous is the wikipedia entry which states:-
So it can be used for all these things, but according to you, it can't be used to detect the difference between a drum beat and C4 exploding?? hahahahahahaha!! lol
You should speak with Wcelliot too, according to him, he was working on a sonogram program which would be able to identify small aircraft by the engine/prop noise. http://forum.physorg.com/index.php?showtop...ndpost&p=275207
Would you agree a sonogram looks at the amplitude, frequency and time parameters?? A Yes or No answer will do.
If you are answering Yes, then for that statement to be correct, you are suggesting that a drum beat & detonation of C4 share the same frequency and amplitude??
Hence the sonogram can't detect the difference?? lolIf you are answering No, then please explain what a sonogram consists off and why it can't detect the difference between a drum beat and C4 exploding.
Because to be honest Trippy, I'm calling BS on you....again.
Another thing which makes your statement look EVEN more ridiculous is the wikipedia entry which states:-
So it can be used for all these things, but according to you, it can't be used to detect the difference between a drum beat and C4 exploding?? hahahahahahaha!! lol
You should speak with Wcelliot too, according to him, he was working on a sonogram program which would be able to identify small aircraft by the engine/prop noise. http://forum.physorg.com/index.php?showtop...ndpost&p=275207
QUOTE ("Wcelliot"+)
I was PROGRAMMING sonogram software for IDENTIFYING small aircraft by their engine/prop-noises back in 1985.
How the hell does a sonogram detect the difference between engine/prop noises, yet according to you Trippy, it can't detect the difference between a wire snapping, a drum beat and C4 going off??
That must mean they share the same frequency, amplitude etc etc.....lol
You are just a terrible liar aren't you Trippy??
This post almost completely lacks substance - except perhaps to serve as evidence of the depths of Stundies delusions.
Nowhere did I claim that a Sonogram couldn't tell the difference between a drum beat and C-4 going off.
What I did say was that there were similarities, because they were both single impulse sounds. I didn't, and have never claimed that they were identical. The only other thing I have claimed is that any other single impulse sound will share the same features that the website you linked to at one stage - including the single impulse sound that I posted an image of earlier.
So, I would appreciate it, and think it would be best if you would apologize for your baseless accusations, and kept your delusional ramblings to yourself.
How the hell does a sonogram detect the difference between engine/prop noises, yet according to you Trippy, it can't detect the difference between a wire snapping, a drum beat and C4 going off??
That must mean they share the same frequency, amplitude etc etc.....lol
You are just a terrible liar aren't you Trippy??
This post almost completely lacks substance - except perhaps to serve as evidence of the depths of Stundies delusions.
Nowhere did I claim that a Sonogram couldn't tell the difference between a drum beat and C-4 going off.
What I did say was that there were similarities, because they were both single impulse sounds. I didn't, and have never claimed that they were identical. The only other thing I have claimed is that any other single impulse sound will share the same features that the website you linked to at one stage - including the single impulse sound that I posted an image of earlier.
So, I would appreciate it, and think it would be best if you would apologize for your baseless accusations, and kept your delusional ramblings to yourself.
QUOTE (einsteen+Nov 9 2007, 03:59 PM)
I've not read it but I disagree that such a SCD didn't look like a CD. Wtc7's collapse looked exactly like a CD. For the twin towers there is nothing to compare them.
Well one can't PRESUME its a SCD.
One needs EVIDENCE.
The fact that a building's collapse APPEARS to look somewhat like a CD is NOT evidence that it was a CD.
The FACT is though that WTC 7 only SUPERFICIALLY looks like a CD.
What it clearly does not look like is any CD I've ever seen (and over the last several years we've looked at a lot of CDs)
If you think it does then simply show us a CD of another large building where the building first BURNS out of control for ~ 7 hours before undergoing a multi-stage collapse that takes ~ 18 seconds, and includes structural failures on both sides of the building, evidenced by the rooftop penthouse mechanical sections falling into the building, followed by a kink developing 1/3 way across one side, all the while at least two curtainwall sides of the building show little apparent motion, before they collapse onto the pile created by the rest of the building.
Can't wait.
Arthur
Well one can't PRESUME its a SCD.
One needs EVIDENCE.
The fact that a building's collapse APPEARS to look somewhat like a CD is NOT evidence that it was a CD.
The FACT is though that WTC 7 only SUPERFICIALLY looks like a CD.
What it clearly does not look like is any CD I've ever seen (and over the last several years we've looked at a lot of CDs)
If you think it does then simply show us a CD of another large building where the building first BURNS out of control for ~ 7 hours before undergoing a multi-stage collapse that takes ~ 18 seconds, and includes structural failures on both sides of the building, evidenced by the rooftop penthouse mechanical sections falling into the building, followed by a kink developing 1/3 way across one side, all the while at least two curtainwall sides of the building show little apparent motion, before they collapse onto the pile created by the rest of the building.
Can't wait.
Arthur
Those mechanical penthouses dropped right before the rest of the collapse. There has been
posted a new show somewhere where they told that probably fireproofing had been removed because
of the debris of the collapsing towers.
But if we look at differences between the collapse of wtc7 and a CD, I can help you, check this
flash video that Jowenko has on his page (an expert who you can always call, his phone number is on the website)
http://www.jowenko.com/gfx/intro/intro.flv , or
http://www.jowenko.com/
In this controlled demolition
- there are no fires on the floors where no charges are placed
- the building is completely stripped
- there is no damage from collapsing towers
- probably there is even a siren going off before the collapse
- there is no smoke because there is no fire
- there is no equipment
- there are even no windows that break
...how long do you want to have the list...
hence wtc7 was no CD.
posted a new show somewhere where they told that probably fireproofing had been removed because
of the debris of the collapsing towers.
But if we look at differences between the collapse of wtc7 and a CD, I can help you, check this
flash video that Jowenko has on his page (an expert who you can always call, his phone number is on the website)
http://www.jowenko.com/gfx/intro/intro.flv , or
http://www.jowenko.com/
In this controlled demolition
- there are no fires on the floors where no charges are placed
- the building is completely stripped
- there is no damage from collapsing towers
- probably there is even a siren going off before the collapse
- there is no smoke because there is no fire
- there is no equipment
- there are even no windows that break
...how long do you want to have the list...
hence wtc7 was no CD.
QUOTE (einsteen+Nov 9 2007, 05:42 PM)
Those mechanical penthouses dropped right before the rest of the collapse.
Right before?
See http://www.911research.com/wtc/evidence/vi...s/wtc_7_cbs.mpg
Watch the penthouse on the right collapse ~ 7 seconds before the penthouse on the left collapses followed by the rest of the curtain wall.
Arthur
Right before?
See http://www.911research.com/wtc/evidence/vi...s/wtc_7_cbs.mpg
Watch the penthouse on the right collapse ~ 7 seconds before the penthouse on the left collapses followed by the rest of the curtain wall.
Arthur
QUOTE (einsteen+Nov 9 2007, 09:42 PM)
...how long do you want to have the list...
Hahahaha! Please, einsteen, surely you know that all you need to do is draw a breath and think of a reason, and it is sufficient to conclude:
Hahahaha! Please, einsteen, surely you know that all you need to do is draw a breath and think of a reason, and it is sufficient to conclude:
QUOTE
hence wtc7 was no CD.
QUOTE (stundie to adoucette+Nov 9 2007, 11:48 AM)
.....
QUOTE (adoucette+)
The fuel entered the building at HIGH RATE OF SPEED and was thus mixed/distributed with great force.
Yes and most of it burned off in the initial impact fireball. So please tell us how much was left and where and how it traveled according to your crackpot theory??
....
Hi stundie!
Bleary-eyed and nearly half-blind as I still am from my illness, even I can 'see' that you're becoming too 'attached' to the subject and therefore 'emotionally clouded and otherwise too 'subjective' in your analysis of the situation.
If you stop and think about it, you will realise that even if the fuel load was a fraction of what the planes were supposed to tak on for the planned trip distance, THERE WAS PNLY a FRACTION of the air mass within the affected floors (or the immediate air movements throughout that space) necessary to combust ONLY a FRACTION of the kerosene fuel.
Consider. The liquid would NOT have been able to toatally vapourise given the immediately available heat/friction energy; and even THEN, the temp. and the proportions with air of what small proportion HAS vapourised have to be right for ignition THROUGHOUT.
You can easily EXTINGUISH A BURNING CIGARETTE (or candle flame) if you put liquid kero on it OR even a TOO RICH kero-air mixture!
So your common knowledge and common sense should tell you that you are grasping at 'misleading straws' in your over-emotionally attempts at 'debate'.
Step back and rethink how you may be being 'blinded' by whatever it IS that is causing you to lose toush with even such self-evident knowledge/sense as in the above example.
Perhaps your arguments would THEN carry more weight if 'stripped' of such obvious, desperately self-deceiving, 'straws'?
Good luck, good thinking and cheers, everyone!
RC.
.
Sorry, I switched subjects mid-post. The equation I was referring to was the one describing the descent-vs.-time from impact to collapse, which people were curve-fitting linear and exponentials with varying degrees of success. I'm thinking that an equation describing a broomstick falling over would be a more-likely fit, with an even better fit (probably) being two broomsticks connected with a hinge with friction, buckling. This would be mostly trig functions, so far as I can guess.
That's 6.86 inches per story. Call it 7 inches.
... via the connection of that steel under stress to a large diaphragm, which acts like the diaphragm of a speaker.
(just to clarify, Chainsaw, I'm not upset with you...)
There were lots of steel members connected to large diaphragms in the WTC that failed suddenly under stress during the collapse. Look at your woofer's speaker cone, and figure out how much air it moves when it's playing back the sound of an explosive detonation. How many square inches area of the cone times how many inches displacement? As big and as loud as your woofer gets, that number is in cubic inches, and the power driving it is in Watts, not kilowatts.
Now do a similar calculation for a floor of a WTC tower. How many square inches in that "speaker cone" floor area? From calculations already provided here, a column suddenly transected would shoot upward at 30gs over a distance of about an inch, not raising the whole floor, but it would raise the floor locally (unless it merely sheared the floor bracket outright) by, say, a half-inch or so. How much energy is stored in a steel truss? It's half the load the truss is carrying times the net displacement (compression or stretch) of the beam. The stretch/compression factor of 0.002 was cited earlier, IIRC, for structural steel under a working load. So take your pick of trusses, calculate how many thousands of pounds, and multiply its length by the 0.002 and there's your energy in inch-pounds. I trust anyone interested in the answer should be capable of doing the rest of the math, or they shouldn't be posting here.
Incidentally, let's not get the supersonic shockwave generated by the initial blast confused with the ultrasonic frequency components of a 10microsecond-duration detonation event. If you want to "characterize" what a block of C-4 sounds like, you'll need to sample it at a rate that's high enough to detect the C-4 going off, the initial rise-time (the "attack"), the central portion of the blast propagating through the block (the "sustain"), and the trailing edge of the waveform (the "decay"), but all of those events take place in 10 microseconds or so, so your sampling rate had better be close to a MHz, otherwise all aspects of the event have taken place in one sample interval, and all information about the "chracteristic waveform" will have been lost in the undersampling process.
How much information is there in this stack of numbers?
0000 0000 0000
0000 0000 0000
0000 0000 0000
1111 1111 1111 <-- The detonation
0000 0000 0000
0000 0000 0000
0000 0000 0000
...
This is what a 12-bit digital recording of a block of C-4 looks like when the sampling rate is 40kHz. (It's also what it looks like at anything up to 100kHz.)
Not much "characteristic" there to use to identify an event, is there?
If that top set of zeroes aren't zeroes, then that's background noise, not detonation, and if the bottom set aren't zeroes, they're background + reflections of the detonation off the local environment, attenuated by the reflection and delayed by the longer, less-direct route (due to the reflection) delayed by the speed of sound.
And it *is* sound that your microphone records, so please drop the "distinction between sound and shockwaves" bs.
(Aimed at AlK, not you, Chainsaw.)
Yes and most of it burned off in the initial impact fireball. So please tell us how much was left and where and how it traveled according to your crackpot theory??
....
Hi stundie!
Bleary-eyed and nearly half-blind as I still am from my illness, even I can 'see' that you're becoming too 'attached' to the subject and therefore 'emotionally clouded and otherwise too 'subjective' in your analysis of the situation.
If you stop and think about it, you will realise that even if the fuel load was a fraction of what the planes were supposed to tak on for the planned trip distance, THERE WAS PNLY a FRACTION of the air mass within the affected floors (or the immediate air movements throughout that space) necessary to combust ONLY a FRACTION of the kerosene fuel.
Consider. The liquid would NOT have been able to toatally vapourise given the immediately available heat/friction energy; and even THEN, the temp. and the proportions with air of what small proportion HAS vapourised have to be right for ignition THROUGHOUT.
You can easily EXTINGUISH A BURNING CIGARETTE (or candle flame) if you put liquid kero on it OR even a TOO RICH kero-air mixture!
So your common knowledge and common sense should tell you that you are grasping at 'misleading straws' in your over-emotionally attempts at 'debate'.
Step back and rethink how you may be being 'blinded' by whatever it IS that is causing you to lose toush with even such self-evident knowledge/sense as in the above example.
Perhaps your arguments would THEN carry more weight if 'stripped' of such obvious, desperately self-deceiving, 'straws'?
Good luck, good thinking and cheers, everyone!
RC.
.
Using the data provided by poster OneWhiteEye with a constant acceleration and no stretch model gives
a = 0.648 g
which is consistent with the figure of (2/3)g obtained with a stretch of 0.14 using the data provided by poster NEU-FONZE.
a = 0.648 g
which is consistent with the figure of (2/3)g obtained with a stretch of 0.14 using the data provided by poster NEU-FONZE.
QUOTE (einsteen+Nov 9 2007, 07:59 PM)
I've not read it but I disagree that such a SCD didn't look like a CD. Wtc7's collapse looked exactly like a CD. For the twin towers there is nothing to compare them.
exactly like a CD.
exactly like a CD.
K.A. Seffen's (apparently a structural engineer) paper entitled "Progressive Collapse of the World Trade Centre: a Simple Analysis" is available at http://winterpatriot.pbwiki.com/f/seffen_simple_analysis.pdf
I haven't read most of the paper, but I appreciate the fact that he's trying to account for the effects of propagating instability. OTOH, he claims "The resulting impingement produced peak forces correctly identified by Bazant and Zhou (2002) to be far in excess of the design capactiy of these columns and hence, above the expected value of "Pmax" that could be reasonably carried by them, even if perfect and undamaged".
Which tells me that he is swallowing BZ's implicit assumptions of fixed lower column ends (without which calculations of quasistatic buckling equations make no sense), and ignoring the literature on impacts, just like BZ.
An initial strike of 8 m/s should be close to the elastic limit, so perhaps one can ignore plastic waves. Also, energy dissipated in overcoming lateral inertia is probably neglible.
However, other ignoring of dynamic effects suggests to me that this paper probably is useless for correcting the BZ scenario, per se. However, it seems a step in the right direction ito more realistic papers (which assume collapse initiation), that don't depend on axial symmetry.
I haven't read most of the paper, but I appreciate the fact that he's trying to account for the effects of propagating instability. OTOH, he claims "The resulting impingement produced peak forces correctly identified by Bazant and Zhou (2002) to be far in excess of the design capactiy of these columns and hence, above the expected value of "Pmax" that could be reasonably carried by them, even if perfect and undamaged".
Which tells me that he is swallowing BZ's implicit assumptions of fixed lower column ends (without which calculations of quasistatic buckling equations make no sense), and ignoring the literature on impacts, just like BZ.
An initial strike of 8 m/s should be close to the elastic limit, so perhaps one can ignore plastic waves. Also, energy dissipated in overcoming lateral inertia is probably neglible.
However, other ignoring of dynamic effects suggests to me that this paper probably is useless for correcting the BZ scenario, per se. However, it seems a step in the right direction ito more realistic papers (which assume collapse initiation), that don't depend on axial symmetry.
QUOTE (metamars+Nov 10 2007, 08:46 AM)
K.A. Seffen's (apparently a structural engineer) paper entitled "Progressive Collapse of the World Trade Centre: a Simple Analysis" is available at http://winterpatriot.pbwiki.com/f/seffen_simple_analysis.pdf
Thank you for posting this reference. I will shortly study this paper.
Dr. Seffen is a lecturer (Assistant Professor equivalent) at Cambridge. In the U.S., at least, he cannot call himself a structural engineer until he can put P.E., S.E. after his name. So he is a academic researcher, specializing in structures, just as is Professor Bazant.
As for your 8 m/s, from my older calculations, this did not occur until 1.2 seconds into the collapse, at which time the drop of the top was 4.87 meters at the center (using the B&V crush-down equation with a constant force and a constant stretch of 0.14). All elastic effects were gone in less than 0.2 seconds.
Thank you for posting this reference. I will shortly study this paper.
Dr. Seffen is a lecturer (Assistant Professor equivalent) at Cambridge. In the U.S., at least, he cannot call himself a structural engineer until he can put P.E., S.E. after his name. So he is a academic researcher, specializing in structures, just as is Professor Bazant.
As for your 8 m/s, from my older calculations, this did not occur until 1.2 seconds into the collapse, at which time the drop of the top was 4.87 meters at the center (using the B&V crush-down equation with a constant force and a constant stretch of 0.14). All elastic effects were gone in less than 0.2 seconds.
einsteen -- your PM inbox has been full for a while. I know - diapers.
cheers.
cheers.
David B. Benson: though it may not seem so, I've payed attention to your various posts regarding data fit but I'm still putting it together inside that feeble knot at the end of my spine. The Bayesian reasoning is quite interesting and I get that OK. I was already familiar with Bayes networks and classifiers (which I will probably end up using in conjunction with various clustering techniques to implement true pattern recognition in my code).
One thing you might be able to help me with is the stretch factor. Can you give me a quick explanation of the underlying physical meaning and derivation of this term? I'm sure it's already written in multiple places but, if you can, it would certainly save me time digging around. Thanks.
One thing you might be able to help me with is the stretch factor. Can you give me a quick explanation of the underlying physical meaning and derivation of this term? I'm sure it's already written in multiple places but, if you can, it would certainly save me time digging around. Thanks.
QUOTE (OneWhiteEye+Nov 10 2007, 01:19 PM)
... the stretch factor.
Of the entire floor height h = 12 feet, about half is just air. Gently setting a floor down upon the office furnishings and computer terminals below would produce about half that height; the stretch is s = 0.5 and the resulted 'crushed' mass is s*h = 6 feet high. When the collapse proceeds faster, the office furnishings are thoroughly crushed and the trusses are somewhat crushed,; the stretch is smaller, maybe s = 0.18. At the very end of the collapse it is possible to observe the 'pancaked' floors; the stretch is about s = 0.05.
Of the entire floor height h = 12 feet, about half is just air. Gently setting a floor down upon the office furnishings and computer terminals below would produce about half that height; the stretch is s = 0.5 and the resulted 'crushed' mass is s*h = 6 feet high. When the collapse proceeds faster, the office furnishings are thoroughly crushed and the trusses are somewhat crushed,; the stretch is smaller, maybe s = 0.18. At the very end of the collapse it is possible to observe the 'pancaked' floors; the stretch is about s = 0.05.
QUOTE (David B. Benson+Nov 10 2007, 08:41 PM)
Of the entire floor height h = 12 feet, about half is just air. Gently setting a floor down upon the office furnishings and computer terminals below would produce about half that height; the stretch is s = 0.5 and the resulted 'crushed' mass is s*h = 6 feet high. When the collapse proceeds faster, the office furnishings are thoroughly crushed and the trusses are somewhat crushed,; the stretch is smaller, maybe s = 0.18. At the very end of the collapse it is possible to observe the 'pancaked' floors; the stretch is about s = 0.05.
Excellent! Thank you.
Edit: is the stretch applied to each floor successively during motion or does it also account for stretch of accumulated mass at the front?
Excellent! Thank you.
Edit: is the stretch applied to each floor successively during motion or does it also account for stretch of accumulated mass at the front?
OneWhiteEye,
I'm sorry but my Inbox was completely full which I didn't notice, I've posted and logged in a couple of times, did you not get a bounced message ? I hope it is still in your SendBox so that you can resend.
Arthur,
You're right, I was confused and thinking about the other half of the penthouses that collapsed right before the rest of the building.
But if we look at those 7 seconds on a scale of 7 hours fire... that is 99.97% of the time no single movement.
All,
fyi, I've mailed Charles M. Beck if he liked to discuss here, but still no reply, holiday probably.
I'm sorry but my Inbox was completely full which I didn't notice, I've posted and logged in a couple of times, did you not get a bounced message ? I hope it is still in your SendBox so that you can resend.
Arthur,
You're right, I was confused and thinking about the other half of the penthouses that collapsed right before the rest of the building.
But if we look at those 7 seconds on a scale of 7 hours fire... that is 99.97% of the time no single movement.
All,
fyi, I've mailed Charles M. Beck if he liked to discuss here, but still no reply, holiday probably.
QUOTE (OneWhiteEye+Nov 10 2007, 01:47 PM)
... does it also account for stretch of accumulated mass at the front?
In the equation there is a single number to account for the average stretch of the entire crushed mass, obviously a simplification. It is, I am strongly convinced, a completely harmless simplification.
In the equation there is a single number to account for the average stretch of the entire crushed mass, obviously a simplification. It is, I am strongly convinced, a completely harmless simplification.
QUOTE (einsteen+Nov 10 2007, 05:33 PM)
Arthur,
You're right, I was confused and thinking about the other half of the penthouses that collapsed right before the rest of the building.
But if we look at those 7 seconds on a scale of 7 hours fire... that is 99.97% of the time no single movement.
Only from the distance those videos were shot from.
The fact that the building was failing was more obvious to those at the scene.
And it was obvious HOURS before the building finally fell.
Arthur
You're right, I was confused and thinking about the other half of the penthouses that collapsed right before the rest of the building.
But if we look at those 7 seconds on a scale of 7 hours fire... that is 99.97% of the time no single movement.
Only from the distance those videos were shot from.
The fact that the building was failing was more obvious to those at the scene.
And it was obvious HOURS before the building finally fell.
Arthur
Figure 5 of Seffen's paper agrees with the values produced by my older simulation program: From the program, the acceleration starts at 0.83g and drops to 0.55g by 3.0 seconds.
I e-mailed Dr. Seffen ~ a month ago about his paper ............ still no reply.........
Anyway, his paper is good applied math, but he really has nothing to say about collapse initiation except the usual "the uppermost parts of the WTC towers were falling freely due to the absence of column resistance...."
Where has anyone proved the truth of this statement?
I thought the tower's collapse started with a tipping motion...
Anyway, his paper is good applied math, but he really has nothing to say about collapse initiation except the usual "the uppermost parts of the WTC towers were falling freely due to the absence of column resistance...."
Where has anyone proved the truth of this statement?
I thought the tower's collapse started with a tipping motion...
QUOTE (NEU-FONZE+Nov 10 2007, 06:36 PM)
... except the usual "the uppermost parts of the WTC towers were falling freely due to the absence of column resistance...."
Where has anyone proved the truth of this statement?
I thought the tower's collapse started with a tipping motion...
Yup.
Isn't true. The data shows that there was resistance at all times.
Yup.
=====================================================
Back to an equation for the stretch. I get good results using a equation for the stretch of the form
s(Z,S) = k*exp(-b*Z*S*S)
(Z is the drop, starting at some Z0 and growing; S is the speed) where the exponent then depends upon the energy available to do the crushing, but the idea is that the stretch can never become non-positive.
Nonetheless, this might not be the best physically motivated form. I would appreciate comments.
Where has anyone proved the truth of this statement?
I thought the tower's collapse started with a tipping motion...
Yup.
Isn't true. The data shows that there was resistance at all times.
Yup.
=====================================================
Back to an equation for the stretch. I get good results using a equation for the stretch of the form
s(Z,S) = k*exp(-b*Z*S*S)
(Z is the drop, starting at some Z0 and growing; S is the speed) where the exponent then depends upon the energy available to do the crushing, but the idea is that the stretch can never become non-positive.
Nonetheless, this might not be the best physically motivated form. I would appreciate comments.
DBB:
About the stretch. (And by the way, I dislike the term stretch .... "squash" would be more appropriate!) I prefer the term compaction ratio.
I am not sure that a stretch of 0.05 was physically possible for the WTC collapse. That would mean a floor was crushed to a height of 7 inches!
Large commercial trash compactors typically deliver a maximum compaction ratio of 9:1 and operate at pressures up to 3000 psi. It requires 3000 psi to crush a car to a height of about 8 inches. If we take a typical car height as 4 feet we have a compaction ratio of 6:1.
My guess is that the typical compaction ratio in the WTC was also about 6:1, or 12 feet -> 2 feet, giving a stretch of 0.167.
Remember too there was a lot of "void" space in the rubble pile.
0.05 would really be s-t-r-e-t-c-h-i-n-g it!
About the stretch. (And by the way, I dislike the term stretch .... "squash" would be more appropriate!) I prefer the term compaction ratio.
I am not sure that a stretch of 0.05 was physically possible for the WTC collapse. That would mean a floor was crushed to a height of 7 inches!
Large commercial trash compactors typically deliver a maximum compaction ratio of 9:1 and operate at pressures up to 3000 psi. It requires 3000 psi to crush a car to a height of about 8 inches. If we take a typical car height as 4 feet we have a compaction ratio of 6:1.
My guess is that the typical compaction ratio in the WTC was also about 6:1, or 12 feet -> 2 feet, giving a stretch of 0.167.
Remember too there was a lot of "void" space in the rubble pile.
0.05 would really be s-t-r-e-t-c-h-i-n-g it!
But Neu, in a typical office floor, probably about 1/2 that 12 foot space is probably empty to start with (or has things like a suspended cieling which is almost all air), so comparing it to the ratios of a trash compactor seems like a bad starting point for comparison.
I agree with you though, compaction ratio is a much better choice for the variable.
Stretch is counter-intuitive.
Arthur
I agree with you though, compaction ratio is a much better choice for the variable.
Stretch is counter-intuitive.
Arthur
I kinda like "squash", myself, but...
Another point should be considered, and that's that those thin floors aren't exactly like the pistons in trash compactors, either. At the time that the floors started collapsing, it's my belief that they were already broken up into random-sized slabs by the differential thrusts associated with the various columns either still intact (and compressed) or transected (and no longer compressed by >30 floors' weight, so those columns' compression was released suddenly).
Sorry for the dense syntax, it's early for me, but you get the idea. Floors start out flat, supported by hundreds of columns, each loaded equally, so compressed equally. Then, some of those columns get unloaded, and therefore uncompressed, and the floors are rigid, but their supports are no longer in a plane, so the floor snaps into hundreds of individual slabs, even prior to the collapse.
During the collapse, those broken slabs land on irregular objects, some higher, some more resistant to "squash", plus lots of mostly-unoccupied floorspace, and they further snap into smaller slabs. Eventually, the debris from the upper floors adds to the total weight, and eventually, it all gets squashed flat, but not at prior to the floor releasing from its supports. The floor supports would be subject to "unzipping" (shearing one after another) from the shock of the impact of the upper floors' material. You'd get some of the squash happening as the floor releases, some more as the kinematics of the higher-velocity falling material accelerates the just-released material to the same speed, and the final "squash" happening when the falling material encounters the rubble-pile and the lower stuff stops even though the upper stuff is still falling.
DBB - WRT to "other form of the equation", did you ever consider the form I suggested describing the balanced broomstick tipping-over? (Or the same basic idea of a column buckling?) Either/both seem more physical to me, given the circumstances, and both have the features we're looking for - a long period where there's almost no perceptible descent, followed by a noticeable descent rate that increases with time, transitioning to an almost-pure fractional-g descent. I'm not proposing this as a literal interpretation, but you can appreciate how an equation that describes one column failing under load might also describe a floor being supported by hundreds of columns, each failing under load...
Another point should be considered, and that's that those thin floors aren't exactly like the pistons in trash compactors, either. At the time that the floors started collapsing, it's my belief that they were already broken up into random-sized slabs by the differential thrusts associated with the various columns either still intact (and compressed) or transected (and no longer compressed by >30 floors' weight, so those columns' compression was released suddenly).
Sorry for the dense syntax, it's early for me, but you get the idea. Floors start out flat, supported by hundreds of columns, each loaded equally, so compressed equally. Then, some of those columns get unloaded, and therefore uncompressed, and the floors are rigid, but their supports are no longer in a plane, so the floor snaps into hundreds of individual slabs, even prior to the collapse.
During the collapse, those broken slabs land on irregular objects, some higher, some more resistant to "squash", plus lots of mostly-unoccupied floorspace, and they further snap into smaller slabs. Eventually, the debris from the upper floors adds to the total weight, and eventually, it all gets squashed flat, but not at prior to the floor releasing from its supports. The floor supports would be subject to "unzipping" (shearing one after another) from the shock of the impact of the upper floors' material. You'd get some of the squash happening as the floor releases, some more as the kinematics of the higher-velocity falling material accelerates the just-released material to the same speed, and the final "squash" happening when the falling material encounters the rubble-pile and the lower stuff stops even though the upper stuff is still falling.
DBB - WRT to "other form of the equation", did you ever consider the form I suggested describing the balanced broomstick tipping-over? (Or the same basic idea of a column buckling?) Either/both seem more physical to me, given the circumstances, and both have the features we're looking for - a long period where there's almost no perceptible descent, followed by a noticeable descent rate that increases with time, transitioning to an almost-pure fractional-g descent. I'm not proposing this as a literal interpretation, but you can appreciate how an equation that describes one column failing under load might also describe a floor being supported by hundreds of columns, each failing under load...
QUOTE (wcelliott+Nov 11 2007, 09:23 AM)
I kinda like "squash", myself, but...
DBB - WRT to "other form of the equation", did you ever consider the form I suggested describing the balanced broomstick tipping-over?
I agree that stretch is not the most intuitive term, but it is what B & V use for the compaction ratio.
I fail to see how this could apply to determining the instantaneous value of the stretch.
In principle, the stretch starts at about 0.5, maybe 0.55, given that the floors contained office furnishings, but otherwise vertically were about half just air. So 0.05 is only maybe 10:1 and indeed from the photographic evidence, that about how tall some of the pancaked floors at Ground Zero were. Except of course for the 'meteorite' stored in Hanger 17, where the stretch is much, much less. The voids might not be important in such a reckoning. In any case parameter estimation chooses an initial stretch of s = 0.42 from which value the exponential decay reduces the stretch somewhat as the speed of the collapse increases.
Edited to add: Some of the floor pans observed 'pancaked' in Ground Zero had essentially no concrete in sight. It may well be that not all parts of the actual trusses were present between those floor pans.
DBB - WRT to "other form of the equation", did you ever consider the form I suggested describing the balanced broomstick tipping-over?
I agree that stretch is not the most intuitive term, but it is what B & V use for the compaction ratio.
I fail to see how this could apply to determining the instantaneous value of the stretch.
In principle, the stretch starts at about 0.5, maybe 0.55, given that the floors contained office furnishings, but otherwise vertically were about half just air. So 0.05 is only maybe 10:1 and indeed from the photographic evidence, that about how tall some of the pancaked floors at Ground Zero were. Except of course for the 'meteorite' stored in Hanger 17, where the stretch is much, much less. The voids might not be important in such a reckoning. In any case parameter estimation chooses an initial stretch of s = 0.42 from which value the exponential decay reduces the stretch somewhat as the speed of the collapse increases.
Edited to add: Some of the floor pans observed 'pancaked' in Ground Zero had essentially no concrete in sight. It may well be that not all parts of the actual trusses were present between those floor pans.
QUOTE
I fail to see how this could apply to determining the instantaneous value of the stretch.
Sorry, I switched subjects mid-post. The equation I was referring to was the one describing the descent-vs.-time from impact to collapse, which people were curve-fitting linear and exponentials with varying degrees of success. I'm thinking that an equation describing a broomstick falling over would be a more-likely fit, with an even better fit (probably) being two broomsticks connected with a hinge with friction, buckling. This would be mostly trig functions, so far as I can guess.
QUOTE (wcelliott+Nov 11 2007, 11:49 AM)
The equation I was referring to was the one describing the descent-vs.-time from impact to collapse, which people were curve-fitting linear and exponentials with varying degrees of success.
Ah. The equation is the B & V crush-down equation
(1-s(Z,Z'))(ZZ" + (Z')^2) - Z = F(Z,Z')
where Z is the location of the crushing front, normalized to start at some Z0 and proceed towards one, Z' is the speed,Z" is the acceleration, s(Z,Z') is the stretch and F(Z,Z') is the resisting force.
The issue is not this equation, per se, but rather appropriate functional forms for the stretch function and the force function.
The conclusion, so far, is that non-constant functional forms for the stretch or force provides a strongly better fit to the data than using constant functions for both stretch and force.
Ah. The equation is the B & V crush-down equation
(1-s(Z,Z'))(ZZ" + (Z')^2) - Z = F(Z,Z')
where Z is the location of the crushing front, normalized to start at some Z0 and proceed towards one, Z' is the speed,Z" is the acceleration, s(Z,Z') is the stretch and F(Z,Z') is the resisting force.
The issue is not this equation, per se, but rather appropriate functional forms for the stretch function and the force function.
The conclusion, so far, is that non-constant functional forms for the stretch or force provides a strongly better fit to the data than using constant functions for both stretch and force.
The problem of a rod fixed at one end and struck longitudinally on the other end is solved in A Treatise on the Mathematical Theory of Elasticity by A.E.H. Love (p. 431 - 435). Further details to the theory are contained in references dated 1916 and 1919. This purely elastic theory assumes that all elastic wave energy is reflected back into the rod when the waves hit the fixed end.
Maximum compression occurs at the fixed point.
While not exactly applicable to a WTC scenario (since the rod is uniform, while a WTC 'rod' would vary in width by a factor of 16), it's still interesting to calculate 'as-if'.
max compression = MC = (1 + sqrt(m)) * V / a
where m is the ratio of the impacting mass to the mass of the rod
V is the velocity of the impacting mass (~ 8 m/s in BZ scenario)
a is the velocity of longitudinal waves in the rod (~ 5,000 m/s for steel)
The following is very rough.
Using Gurich's figures, which give
* total mass (above grade) 240 Ktons
* structural steel (above grade) 89 Ktons
percentage of structural steel = 89 / 240 = 37%
call it 18.5%, since our WTC base 'rod' is only comprised of part of the structural steel, viz., the columns
mass per floor ~ 240 ktons/ 111 floors = 2.16 KTON/floor
mass(top) = (16 floors of WTC top) * 2.16 kton/fl = 34.56 KTON
mass(bottom "rod") = (111 - 16 floors) * (18.5% guesstimated column weight %) * (2.16 kton/fl) = 37.96
Plugging in to :
max compression = MC = (1 + sqrt(m)) * V / a
we get
MC = ( 1 + sqrt(34.56 / 37.96)) * (8 / 5,000)
= 0.0031
Since the lowest column segments were something like 5x the cross sectional area of the impact column segments, I would guess that the elastic limit would not be surpassed. Unfortunately, I'm not clear on what the compression profile is like in the upper part of the lower WTC block. (I still need to study this more.)
This theory assumes that the impacting mass is rigid, an assumption which favors collapse.
Maximum compression occurs at the fixed point.
While not exactly applicable to a WTC scenario (since the rod is uniform, while a WTC 'rod' would vary in width by a factor of 16), it's still interesting to calculate 'as-if'.
max compression = MC = (1 + sqrt(m)) * V / a
where m is the ratio of the impacting mass to the mass of the rod
V is the velocity of the impacting mass (~ 8 m/s in BZ scenario)
a is the velocity of longitudinal waves in the rod (~ 5,000 m/s for steel)
The following is very rough.
Using Gurich's figures, which give
* total mass (above grade) 240 Ktons
* structural steel (above grade) 89 Ktons
percentage of structural steel = 89 / 240 = 37%
call it 18.5%, since our WTC base 'rod' is only comprised of part of the structural steel, viz., the columns
mass per floor ~ 240 ktons/ 111 floors = 2.16 KTON/floor
mass(top) = (16 floors of WTC top) * 2.16 kton/fl = 34.56 KTON
mass(bottom "rod") = (111 - 16 floors) * (18.5% guesstimated column weight %) * (2.16 kton/fl) = 37.96
Plugging in to :
max compression = MC = (1 + sqrt(m)) * V / a
we get
MC = ( 1 + sqrt(34.56 / 37.96)) * (8 / 5,000)
= 0.0031
Since the lowest column segments were something like 5x the cross sectional area of the impact column segments, I would guess that the elastic limit would not be surpassed. Unfortunately, I'm not clear on what the compression profile is like in the upper part of the lower WTC block. (I still need to study this more.)
This theory assumes that the impacting mass is rigid, an assumption which favors collapse.
QUOTE (Al Khwarizmi - step-by-step+Oct 31 2007, 04:39 AM)
Trippy:
====================
Having dealt with UV-VIS and NIR spectroscopy, I'm well aware of the distinction between Infra- and Ultra.
====================
Your spelling is marginally better than your comprehension skills: neither are particularly good.
My comment regarding the embarrasing inability to distinguish between sub and super sonic was directed at wcelliot, not at yourself.
Check the record.
chainsaw
you directed abuse at me for a whacky guitar string analogy that was actually produced by wcelliot - hence, I cannot consider your unreferenced and unsubstantiated arguments to be sound.
Learn to use a url.
The analogy was Wcelliot's that is true however your comments were to put it gently Ludicrous.
Sound waves in air can be generated by snapping metal and have almost identical signature to explosives dependent on how and when they are generated.
Any one who has done any work with heavy equipment can tell you that try setting on top of a D7 Caterpillar when the final drive shears you would think a bomb went of under your rear end.
Try a sidewinder bush hog on a large pipe like an oil well hidden in weeds, or an inch cable on an oil rig holding up about 800- 1000 feet of drill stem.
Wcelliot's point was that energy could be stored in metal structures and released as sound waves in air, the energy in the waves depends on the energy transfered to the air by the breakage of the metals, Larger pieces of metals store more energy.
It is a simple concept, the only way to tell an explosion from a super sonic sound wave generated by another source is to look in the sound trace for the detonation delay the small bang before the large bang.
The detonator goes off and then triggers the larger explosive, often that is the only way to tell that Super sonic sound waves are from an explosion.
As for your opinion of my arguments that does not really matter as you have no argument to begin with so your opinion is mute anyway.
====================
Having dealt with UV-VIS and NIR spectroscopy, I'm well aware of the distinction between Infra- and Ultra.
====================
Your spelling is marginally better than your comprehension skills: neither are particularly good.
My comment regarding the embarrasing inability to distinguish between sub and super sonic was directed at wcelliot, not at yourself.
Check the record.
chainsaw
you directed abuse at me for a whacky guitar string analogy that was actually produced by wcelliot - hence, I cannot consider your unreferenced and unsubstantiated arguments to be sound.
Learn to use a url.
The analogy was Wcelliot's that is true however your comments were to put it gently Ludicrous.
Sound waves in air can be generated by snapping metal and have almost identical signature to explosives dependent on how and when they are generated.
Any one who has done any work with heavy equipment can tell you that try setting on top of a D7 Caterpillar when the final drive shears you would think a bomb went of under your rear end.
Try a sidewinder bush hog on a large pipe like an oil well hidden in weeds, or an inch cable on an oil rig holding up about 800- 1000 feet of drill stem.
Wcelliot's point was that energy could be stored in metal structures and released as sound waves in air, the energy in the waves depends on the energy transfered to the air by the breakage of the metals, Larger pieces of metals store more energy.
It is a simple concept, the only way to tell an explosion from a super sonic sound wave generated by another source is to look in the sound trace for the detonation delay the small bang before the large bang.
The detonator goes off and then triggers the larger explosive, often that is the only way to tell that Super sonic sound waves are from an explosion.
As for your opinion of my arguments that does not really matter as you have no argument to begin with so your opinion is mute anyway.
QUOTE (metamars+Nov 11 2007, 01:01 PM)
The problem of a rod fixed at one end and struck longitudinally on the other end is solved ...
Is the rod horizontal or vertical?
This appears to have very little, indeed almost nothing, to do with the collapse initiation of the towers. I've already given you the references to two books by Simitses. These contain work which is relevant.
Is the rod horizontal or vertical?
This appears to have very little, indeed almost nothing, to do with the collapse initiation of the towers. I've already given you the references to two books by Simitses. These contain work which is relevant.
QUOTE
One worker said they saw 14 stories in 8 feet.
That's 6.86 inches per story. Call it 7 inches.
QUOTE (NEU-FONZE+Nov 11 2007, 02:44 PM)
DBB:
About the stretch. (And by the way, I dislike the term stretch .... "squash" would be more appropriate!) I prefer the term compaction ratio.
I am not sure that a stretch of 0.05 was physically possible for the WTC collapse. That would mean a floor was crushed to a height of 7 inches!
Large commercial trash compactors typically deliver a maximum compaction ratio of 9:1 and operate at pressures up to 3000 psi. It requires 3000 psi to crush a car to a height of about 8 inches. If we take a typical car height as 4 feet we have a compaction ratio of 6:1.
My guess is that the typical compaction ratio in the WTC was also about 6:1, or 12 feet -> 2 feet, giving a stretch of 0.167.
Remember too there was a lot of "void" space in the rubble pile.
0.05 would really be s-t-r-e-t-c-h-i-n-g it!
I have to agree with that from drop tests the squash would have been between 2-1.5 feet. Greater than that and a dieseling effect causes an increase in oxidation leading to expansion of the air in the structure from heat energy increasing the energy needed for compression-squash.
I would like to also point out that other reactions can greatly effect the squash so that an average for it may be hard to determine.
I do not do much on 9/11 any more but I still like to look in once and a while to see how the work is progressing. Basically I have run out of explosives to test and things to blow up!
About the stretch. (And by the way, I dislike the term stretch .... "squash" would be more appropriate!) I prefer the term compaction ratio.
I am not sure that a stretch of 0.05 was physically possible for the WTC collapse. That would mean a floor was crushed to a height of 7 inches!
Large commercial trash compactors typically deliver a maximum compaction ratio of 9:1 and operate at pressures up to 3000 psi. It requires 3000 psi to crush a car to a height of about 8 inches. If we take a typical car height as 4 feet we have a compaction ratio of 6:1.
My guess is that the typical compaction ratio in the WTC was also about 6:1, or 12 feet -> 2 feet, giving a stretch of 0.167.
Remember too there was a lot of "void" space in the rubble pile.
0.05 would really be s-t-r-e-t-c-h-i-n-g it!
I have to agree with that from drop tests the squash would have been between 2-1.5 feet. Greater than that and a dieseling effect causes an increase in oxidation leading to expansion of the air in the structure from heat energy increasing the energy needed for compression-squash.
I would like to also point out that other reactions can greatly effect the squash so that an average for it may be hard to determine.
I do not do much on 9/11 any more but I still like to look in once and a while to see how the work is progressing. Basically I have run out of explosives to test and things to blow up!
DBB-
Once again, my-bad for not making my point clearer.
Remember the smear-o-grams? The height of the WTC tower descended too-slowly to measure from impact to the point where it was 20cm lower than it was prior to impact, and then the smear-o-grams provided a curve and you and others tried curve-fitting various equations looking for a good fit, and finding none that seemed linked to the mechanics of the collapse?
*That's* the equation I was suggesting you try the balanced-broomstick model for. And failing that, a more-likely dual-broomstick-with-a-hinge (with friction). When the broomstick is almost perfectly balanced, the descent is microscopic, at a snail's pace, but its angular rate increases as a function of the net angular displacement due to the increasing moment arm of the Cg as it gets farther from the balanced position. That would explain the long, flat part of the curve that eventually ends up 20cm below the original height. The farther that Cg gets from being directly over the point of support, the more torque it exerts and the faster the broomstick rotates.
The "two-broomsticks-with-a-hinge" is more sophisticated, but explains Marie Osmond's collapse rate as a function of time even better than the "Silent Covert Explosives" conspiracy theory.
Please note that I'm not saying it's a literal instance of anything "falling over", I'm just saying that the equations are probably more mechanically-related to trig functions than to exponentials.
Once again, my-bad for not making my point clearer.
Remember the smear-o-grams? The height of the WTC tower descended too-slowly to measure from impact to the point where it was 20cm lower than it was prior to impact, and then the smear-o-grams provided a curve and you and others tried curve-fitting various equations looking for a good fit, and finding none that seemed linked to the mechanics of the collapse?
*That's* the equation I was suggesting you try the balanced-broomstick model for. And failing that, a more-likely dual-broomstick-with-a-hinge (with friction). When the broomstick is almost perfectly balanced, the descent is microscopic, at a snail's pace, but its angular rate increases as a function of the net angular displacement due to the increasing moment arm of the Cg as it gets farther from the balanced position. That would explain the long, flat part of the curve that eventually ends up 20cm below the original height. The farther that Cg gets from being directly over the point of support, the more torque it exerts and the faster the broomstick rotates.
The "two-broomsticks-with-a-hinge" is more sophisticated, but explains Marie Osmond's collapse rate as a function of time even better than the "Silent Covert Explosives" conspiracy theory.
Please note that I'm not saying it's a literal instance of anything "falling over", I'm just saying that the equations are probably more mechanically-related to trig functions than to exponentials.
QUOTE (wcelliott+Nov 11 2007, 09:31 PM)
Marie Osmond's collapse rate as a function of time...
I believe that would be meatbag mechanics; think chicken cannon.
I believe that would be meatbag mechanics; think chicken cannon.
QUOTE (wcelliott+Nov 11 2007, 02:31 PM)
The height of the WTC tower descended too-slowly to measure from impact to the point where it was 20cm lower than it was prior to impact, and then the smear-o-grams provided a curve and you and others tried curve-fitting various equations looking for a good fit, and finding none that seemed linked to the mechanics of the collapse?
... than to exponentials.
AFAIK I am the only one how attempted to fit functions for the collapse initiation phase. NEU-FONZE has a theory about this, which he said a bit about in an earlier posting. By that theory, one certainly expects to fit a exponential force in the crush-down equation. However, a linearly declining force is statistically indistinguishable from his model.
The problem is that, as of yet, there simply is not enough data. Adding another possible model won't change that fact.
Edited to add: Upon reflection, I currently believe your model would lead to essentially NEU-FONZE's formulation.
... than to exponentials.
AFAIK I am the only one how attempted to fit functions for the collapse initiation phase. NEU-FONZE has a theory about this, which he said a bit about in an earlier posting. By that theory, one certainly expects to fit a exponential force in the crush-down equation. However, a linearly declining force is statistically indistinguishable from his model.
The problem is that, as of yet, there simply is not enough data. Adding another possible model won't change that fact.
Edited to add: Upon reflection, I currently believe your model would lead to essentially NEU-FONZE's formulation.
QUOTE (David B. Benson+Nov 11 2007, 08:17 PM)
Is the rod horizontal or vertical?
This appears to have very little, indeed almost nothing, to do with the collapse initiation of the towers. I've already given you the references to two books by Simitses. These contain work which is relevant.
Oops, no mention of gravity, so "horizontal".
This appears to have very little, indeed almost nothing, to do with the collapse initiation of the towers. I've already given you the references to two books by Simitses. These contain work which is relevant.
Oops, no mention of gravity, so "horizontal".
Rather to my surprise, despite the fact that at the chosen t0 WTC 1 had dropped almost 20 cm, the data indicates that the speed was zero at that time. While this might be because I didn't smooth the data first, it indicates that the speed was very small. Eventually I'll print out some tables for drop and speed from t0-0.2 seconds to t0+0.6 seconds.
Also, NEU-FONZE choose t0 extremely well. The program only wants to adjust it by a small fraction of a millisecond.
Also, NEU-FONZE choose t0 extremely well. The program only wants to adjust it by a small fraction of a millisecond.
QUOTE
Wcelliot's point was that energy could be stored in metal structures and released as sound waves in air
... via the connection of that steel under stress to a large diaphragm, which acts like the diaphragm of a speaker.
(just to clarify, Chainsaw, I'm not upset with you...)
There were lots of steel members connected to large diaphragms in the WTC that failed suddenly under stress during the collapse. Look at your woofer's speaker cone, and figure out how much air it moves when it's playing back the sound of an explosive detonation. How many square inches area of the cone times how many inches displacement? As big and as loud as your woofer gets, that number is in cubic inches, and the power driving it is in Watts, not kilowatts.
Now do a similar calculation for a floor of a WTC tower. How many square inches in that "speaker cone" floor area? From calculations already provided here, a column suddenly transected would shoot upward at 30gs over a distance of about an inch, not raising the whole floor, but it would raise the floor locally (unless it merely sheared the floor bracket outright) by, say, a half-inch or so. How much energy is stored in a steel truss? It's half the load the truss is carrying times the net displacement (compression or stretch) of the beam. The stretch/compression factor of 0.002 was cited earlier, IIRC, for structural steel under a working load. So take your pick of trusses, calculate how many thousands of pounds, and multiply its length by the 0.002 and there's your energy in inch-pounds. I trust anyone interested in the answer should be capable of doing the rest of the math, or they shouldn't be posting here.
Incidentally, let's not get the supersonic shockwave generated by the initial blast confused with the ultrasonic frequency components of a 10microsecond-duration detonation event. If you want to "characterize" what a block of C-4 sounds like, you'll need to sample it at a rate that's high enough to detect the C-4 going off, the initial rise-time (the "attack"), the central portion of the blast propagating through the block (the "sustain"), and the trailing edge of the waveform (the "decay"), but all of those events take place in 10 microseconds or so, so your sampling rate had better be close to a MHz, otherwise all aspects of the event have taken place in one sample interval, and all information about the "chracteristic waveform" will have been lost in the undersampling process.
How much information is there in this stack of numbers?
0000 0000 0000
0000 0000 0000
0000 0000 0000
1111 1111 1111 <-- The detonation
0000 0000 0000
0000 0000 0000
0000 0000 0000
...
This is what a 12-bit digital recording of a block of C-4 looks like when the sampling rate is 40kHz. (It's also what it looks like at anything up to 100kHz.)
Not much "characteristic" there to use to identify an event, is there?
If that top set of zeroes aren't zeroes, then that's background noise, not detonation, and if the bottom set aren't zeroes, they're background + reflections of the detonation off the local environment, attenuated by the reflection and delayed by the longer, less-direct route (due to the reflection) delayed by the speed of sound.
And it *is* sound that your microphone records, so please drop the "distinction between sound and shockwaves" bs.
(Aimed at AlK, not you, Chainsaw.)
QUOTE (Chainsaw+,Nov 11 2007, 09:09 PM)
I have to agree with that from drop tests the squash would have been between 2-1.5 feet. Greater than that and a dieseling effect causes an increase in oxidation leading to expansion of the air in the structure from heat energy increasing the energy needed for compression-squash.
I would like to also point out that other reactions can greatly effect the squash so that an average for it may be hard to determine.
I do not do much on 9/11 any more but I still like to look in once and a while to see how the work is progressing. Basically I have run out of explosives to test and things to blow up!
Hi Chainsaw! How's things? Still in one piece I hope, considering your 'hands-on' work into potentially 'nastilly noisy' processes! hehehe.
And I too don't visit often since my latest bout of serious illness. I hope you and yours are well!
Cheers and good work, mate!
RC.
.
I would like to also point out that other reactions can greatly effect the squash so that an average for it may be hard to determine.
I do not do much on 9/11 any more but I still like to look in once and a while to see how the work is progressing. Basically I have run out of explosives to test and things to blow up!
Hi Chainsaw! How's things? Still in one piece I hope, considering your 'hands-on' work into potentially 'nastilly noisy' processes! hehehe.
And I too don't visit often since my latest bout of serious illness. I hope you and yours are well!
Cheers and good work, mate!
RC.
.
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