I took my time reading the 44 pages. I did not look up references, did not check out whether the equations are proper, and did not do the calculations, so there is that.
I find the paper fairly well done. I was confused a bit in the early part about the percentages of elements - the business of eliminating C and O and normalizing all the rest to 100% and then comparing the results with other studies. On page 8: "
Oxygen, typically ~ 50%, was also excluded from the data and the remaining elements adjusted to 100 %. The resulting percent concentrations are given in Table 1 and are compared to data from Reference [3]."
My problem is that the 10 major elements listed in column 1 of Table 1 add up to to only 37%. It seems that at least O is
not excluded; if it were 50%, the total would be 87% - still too short of 100%. He might even have left C in the mix (Fig. 5 has C between 14% and 27%). The reference samples add up to 27.2% and 75.5%, respecticely - quite a span! Obviously, Greening did NOT normalize the elements other than C and O to 100%, and thus the comparison he draws is flawed.
This is, however, properly done in Tables 2 to 5. I am not sure about Table 6.
I like the part about estimating how different particle size fractions would fall out of the dust cloud as a function of distance to GZ;I particularly like the fact that Greening is aware that hos theoretical work does not allow for making predictions about particle size
distributions as a function of distance, for that would require knowing the distribution at distance = 0 - i.e. the particle size distribution created by the collapse!
What I would suggest for a follow-up paper (and I have little doubt Frank is thinking about this already) is: Analyze the as-found size distribution of samples from known distances, and calculate back to the original size distribution. The latter is an important input to estimating the size of the energy sink that crushing concrete was. I saw a paper the other by Robert Korol at al (Truthers) that
assumed, out of the blue, a particle size distribution and calculated that it would have required 4 times the available Potential Energy to generate such fine dust. (Of course no doubt emanates in that paper that perhaps the assumption was bollocks)
Greening concludes that various particles he finds, and finds to be typical for the dust, are
consistent with, and thus
plausibly explained as originating with concrete aggregate, fly ash, welding and cutting/grinding, all present since construction time, and some modified by HCl during the time the PVC on several floors burned.
I agree that this is
plausible - but of course nothing more.
In terms of methodology, this is only somewhat more solid than what certain Truther "scientists" did (I am looking at you, Steven "Jesus visited America" Jones), when they claim that certain microspheres are consistent with thermite reaction residue.
Greening's paper can thus serve as a useful antidote to such Twoofiness, by showing that very trivial explanations exist, such that the outrageous speculations by Jones are wholely unnecessary and discouraged by Occam. It's a tough sell, though - seeing that it's 44 pages with math, rather than a YouTube video.
You would think that one of the Truth Movement people here would like to comment on this, but Either they have me on ignore, or they are holding their breath waiting on Basile to finnish his study of contaminated dust.
This is miles beyond their level of comprehension or even interest.
