Mass attenuation coefficient Puns

I understand that when X-rays pass through matter they interact in various ways, photoelectric, Compton, etc, which attenuate the beam. I am just slightly confused when it comes to coherent and incoherent scatter and exactly how they relate to the beam's attenuation, and when I should use one or the other or the total attenuation to model an X-ray beam.

For instance, I am working with an X-ray beam which I pass through a filter. The filter is a considerable distance away from the object, so I imagine I am really only interested in the X-rays that aren't scattered, as the scattered X-rays probably won't hit the target. In front of the target I have a buildup material which is in contact with the target, so I imagine, that both coherent and incoherent are important. The beam then hits the target, and I am interested in the beam attenuation vs depth, and in this case, I am definitely interested in both the photons which get scattered inside the target and the photons that penetrate deeper to determine the number of interactions vs depth. My confusion comes in because I have heard people tell me 'model without coherent scatter at this part' or 'model with coherent scatter'. I guess does anyone have experience in this on what coefficients I should be using in the scenario I described? Thanks!

Does anyone know a good source for finding attenuation coefficients in aluminium, lead and steel (or soft iron) . I am looking for attenuation coefficients at energies 511keV and 1275 keV.

Thank you!!

Hello guys,
I'm doing a lab experiment regarding the Attenuation Coefficient in Gamma Rays. I should conclude that the coefficient is dependant to the Z of the absorbent material and it is dependant of the energy of the beam for a certain material. Can someone help me explain this, or, point me where I can get some information about this subject? Thanks in advance.

Is anyone aware of any research or proposals on increasing HVL via metamaterials for, say, reducing cosmic radiation?

The original problem

My work up until I get stuck

From what I was taught, I can't find mass without diving net force by acceleration, and I can't find net force without subtracting force of friction from applied force, and I can't find force of friction given what I have without normal force, which I can't find without mass, which is what I'm solving for. Any help would be greatly appreciated. The answer is 38kg.

Hello all,

I am reading a paper and I am confused about a couple of images they have plotted.

This paper wants to show the relationship between the theory of how mass is transferred in laminar conditions and the experimental results. Air is blown over a pan which holds water. The flux is specifically the evaporated water.

I see two plots whose units dont make much sense to me.

First we have Mass flux vs. velocity. Mass flux has units of of kg/m2s

then they plot Mass Transfer Coefficient vs. velocity. Mass Transfer Coefficient also has units of kg/m2s

How is this possible? The only way I can see is this way:

N_A = k_c(x_As - x_Ainfinity)

Here N_A and k_c would have the same units.

But Ive never seen mass flux equation like this.. Is it still correct?

Thanks a bunch

Hello,

I have some data I'm trying to analyze so that I can come up with a mass transfer coefficient for an experiment I ran.

Heres what I did. I ran varying speeds of air over a plate of water. I collected the values for the mass of water evaporated. We were given a modified version of the Antoine equation. We were able to measure temperatures of each run and also measured the relative humidity of the room and the exhaust air. We also knew the dimensions of the water pan.

Here is my attempt at finding the M.T. coeff.

First I plot my Mass of Water evaporation vs. air speed velocity. I get the slope of this which can then be divided by the area of water so then I can arrive at Mass flux (kg/m2s).

I am now stumped on how to go about finding the M.T. coeff.

I know that N_A = k_c(deltaC)

deltaC is the difference in concentration at the surface and concentration at an infinite distance away from the fluid.

Like stated earlier, we are given the equilibrium water-vapor mole fraction in air equation through antoines. We have everything to solve this. What I dont understand is what to do with this after I get it? I have some X_H2O which represents a mole fraction, but a mole fraction of what? The relative humidity? If this is correct then how would I turn it back into C_H2O? we would be taking a mole fraction of a percent? I am confused here.

Once I understand how to get the concentrations both at surface and far away I think I can move forward... I would then plot M.T. coeff vs. velocity to find the power law fit which should agree somewhat with theorey, v^0.5

Let me know what ya'll think!

I'm doing physics homework and I have no idea how to solve a problem that involves finding the coefficient of kinetic friction of an object sliding down an incline without being given mass or friction force. The variables given are acceleration and the angle of the incline. Can someone walk me through this? I'm not sure if I gave enough details to solve the problem.

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Edit: I've also got a micro pog up for trade

Flint

Rc5

Dd8

Obne sunlight

Megabyte

Maybe a drum trap?

Weird stuff?

In an ideal world I would trade the draume for a flint and some cash or something else.

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Thanks

I mean, will there be a difference between the result CFD gives me and the result I would get testing it ?

In other words, is CFD good enough to count as a empirical testing ?

*I'm using Autodesk CFD 2019

I need to give a mass transfer coefficient from literature for my model to work but I can't seem to find any. It's specifically the transfer of Itaconic Acid between water and propyl acetate, but I'll take anything close in chemical properties.

So I have been trying to find where to obtain the penetration formula that accounts for the explosive mass of the shell in War Thunder, and I finally found it:

https://warthunder.com/en/news/6023-qa-ballistic-update-questions-and-answers-from-the-developers-en

But for some reason the links at the very bottom for the explosive mass coefficients are not accessible, at least by me. Is this happening just to me, or are other people experiencing it? Also, can someone send me pictures of the contents inside that spreadsheet? I'd appreciate it greatly, since this is for a school project.

Title

I recently touched on the Q/V backhaul (v-band feeder link below) in two posts, as the onboard antenna for this link was disclosed in the recent video. This writeup will take a closer look into one aspect of that link. Attenuation.

DISCLAIMER NOTE: I am NOT an RF engineer. What I write here is just to the best of my understanding of the matter. I would very much appreciate people that work with these things to contribute with their thoughts. And please correct me if I got anything of this wrong.

Attenuation means the gradual loss of intensity through a medium.

It is a very common bear case to come across that the fairly new concept AST SpaceMobile uses of extremely high throughput Q/V-band links in the backhaul is:

"Impossible at that distance because of high attenuation in Q/V band."

Impossible. Strong word, and always delivered with no data to back that up.

Let's hear Wernher on that:

A few words from the father of the US Space program.

>“I have learned to use the word 'impossible' with the greatest caution.”
>
>Wernher Magnus Maximilian, Freiherr von Braun

The Bluewalker3 test satellite network architecture. Similar to SpaceMobile constellation, but uses smaller terrestrial satellite dish (2.4 m) as it has lower orbit. Q/V-band links in red. SpaceMobile has 5m+ dish antennas in the ground segment.

Fun fact. The main purpose of Bluewalker3 in space tests are to test the backhaul link and integration to terrestrial networks, the left part of the image above. Fronthaul, the right part, is very much tested and set already, just in the other direction using Bluewalker1&2.

Why Q/V band? The good.

Spectrum is scarce and these higher band have not been put to extensive use, yet, and because of this broad bandwidths can be found and put to use. A broad band is what makes high throughput possible.

Attenuation in Q/V - band. The bad, but not that bad imo.

Attenuation. I added approximate numbers for cellular 2 GHz bands and the relevant Q/V-bands.

Recap, attenuation is: **the gradual loss

Hello. One of our homework questions involves finding the acceleration of a car given velocity, and the coefficients of static and kinetic force. Here's the question:

A car without ABS (antilock brake system) was moving at 15.0 m/s when the driver slammed on the brakes to make a sudden stop. The coefficients of static and kinetic friction between the tires and the road are 0.550 and 0.430, respectively. a) What was the acceleration of the car during the interval between braking and stopping?
b) How far did the car travel before it stopped?

I have a feeling that mass doesn't matter, but I can't seem to figure out how to get acceleration without mass. I've tried equating the two friction formulas together(using normal force) but I end up just getting stuck. Any help or pointers would be appreciated. Thanks!

Anyone else gets very high attenuation with nottingham? My usual "house" aleyeast have been s-04 but I tried out nottingham to see how it compares. It took my 1.048 wort to 1.004 now in 4 days. Made me check calibration and pull another sample, tastes good too. Impressed!

This was a overnight mash so a little higher fermentability is normal for me then, 27L (~7gal) and one pack rehydrated to instructions, so the pitch was slightly on the low side as well.

Edit, it's a pretty plain pale ale. 6% carapils and 94 pale malt. Mashed in to 69C and insulated overnight.

What are some pros/cons about beers with low FG? I’ve read they can be drier and sometimes thin but any more description?

I’m brewing a wheat ale, all grain 40%wheat 40%2 row 10% Munich, 10% Vienna and a small amount acidulated. Mash 152 x 60 min with mash out at 165. Intended to brew American wheat ale, LHBS didn’t have any of the intended yeast strains I was hoping for, ended up with Fermentis WB06, German wheat beer dry yeast. (Could have gone us05 and been truer to style but trying to branch out a bit). Fermenting at the colder side ~65F to minimize the ester production. Anyways Brew day comes I decide to only do a 30 min boil without calculating for decreased boil off as with a 60 boil. Expected OG 1.046 actual 1.040. I was worried beer might be on the thinner side but oh well. 10 days of fermenting were at 1.06 with an attenuation of 87%. I recheck yeast info and the expected attenuation is 86-90. Holy cow, not sure how I overlooked that, have never used a yeast with that high attenuation. Will be cold crashing and kegging in a few days.

What are general thoughts on beers that are lower OG and low FG? All grain no sugar or high fermentable additions. Thanks!

Im performing a transient analysis on a motorcycle chassis and i don't know what is the value i should give to these parameters and every paper and article i read about them (Rayleigh damping) is just too complicated to understand

Hello! Im very open to adding cash to whatever needs it. Open to offers but mostly looking for the following:

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• big ear albie

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