Author Topic: Hydro in the Gutters  (Read 21841 times)

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rossw

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Re: Hydro in the Gutters
« Reply #33 on: June 15, 2008, 01:58:23 AM »
I think "someone" has a fundamental oopsee in thinking.


We're not dropping a given mass of water 100 feet.


We've got a continuous column of water, 100 feet high.


The PRESSURE at the bottom of a 100' column of water, times the flow, not the kinetic energy of a unit of water dropped 100' and being allowed to accelerate.


Yes, I started out tongue-in-cheek, just like the OP.

« Last Edit: June 15, 2008, 01:58:23 AM by rossw »

BruceDownunder

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Re: Hydro in the Gutters
« Reply #34 on: June 15, 2008, 02:04:48 AM »
How many times have I told you before,,,,


 If you don't stop that ,,you'll go blind


Bruce

« Last Edit: June 15, 2008, 02:04:48 AM by BruceDownunder »

joestue

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Re: Hydro in the Gutters
« Reply #35 on: June 15, 2008, 02:08:08 AM »
Velocity does not matter.


Furthermore, you calculated average velocity, a worthless number, the RMS velocity would be a better number.


force x distance/time = power.

mass x gravitational acceleration x distance[height] / time = power


state your math

« Last Edit: June 15, 2008, 02:08:08 AM by joestue »
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joestue

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Re: Hydro in the Gutters
« Reply #36 on: June 15, 2008, 02:11:53 AM »
I was using kinetic energy as a way of explaining it, but you are absolutely right
« Last Edit: June 15, 2008, 02:11:53 AM by joestue »
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ruddycrazy

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Re: Hydro in the Gutters
« Reply #37 on: June 15, 2008, 02:20:43 AM »
Ron You've done it again mate, raise a simple discussion then all ya get da gutter talk... Well done mate this thread might even beat the Global Climate Change thread.
« Last Edit: June 15, 2008, 02:20:43 AM by ruddycrazy »

joestue

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Re: Hydro in the Gutters
« Reply #38 on: June 15, 2008, 02:27:11 AM »
"Now we need to figure the average velocity for the object in order to figure out the force it will have at the 10 feet mark."


lets not invent new math here.

« Last Edit: June 15, 2008, 02:27:11 AM by joestue »
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jacquesm

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Re: Hydro in the Gutters
« Reply #39 on: June 15, 2008, 04:25:04 AM »
some grade school kid actually won a prize for this 'original idea' and implementation about 5 years ago.


It was just about enough to light a small bicycle lamp during a downpour.

« Last Edit: June 15, 2008, 04:25:04 AM by jacquesm »

wdyasq

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Re: Hydro in the Gutters
« Reply #40 on: June 15, 2008, 07:48:50 AM »
The point is/was it is absurd to do this, even at 100 foot drop, it is still a stupid idea. No amount of R squaring pie and cubing the inverse will change that fact.


The minuscule amount of energy in even a torrential rain over a small area is the reason I started this mess. Even though we perceive our energy bills high, purchased energy is really a substitute for labor. I would not care to pay a person for the work a band saw will do in just a few minutes.


This cheap supply of 'help' has lead to a lot of waste. It has also allowed the mechanized farmer to feed multiple times what the farmer could do only a century ago. It allows the metropolitan lifestyle, suburbia, factory farming, the internet and cheap personal transportation.


I like the lifestyle it affords. I think we are all in for a great change in the ways we purchase and treat energy. I believe the religion of global warming is just a way for politicians to gain more control.


Before we endorse any policies, or install gutter turbines, we should take a good look  at the project.


Ron

« Last Edit: June 15, 2008, 07:48:50 AM by wdyasq »
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DamonHD

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Re: Hydro in the Gutters
« Reply #41 on: June 15, 2008, 07:54:41 AM »
I predict that fewer combines will get airborne when energy gets more expensive.  B^>


Rgds


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« Last Edit: June 15, 2008, 07:54:41 AM by DamonHD »
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wdyasq

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Re: Hydro in the Gutters
« Reply #42 on: June 15, 2008, 08:36:46 AM »
That is a 'plug-in Hybrid' Combine Damon......


geeze ... don't they teach anything in schools anymore ....


Ron

« Last Edit: June 15, 2008, 08:36:46 AM by wdyasq »
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thirteen

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Re: Hydro in the Gutters
« Reply #43 on: June 15, 2008, 08:37:52 AM »
where does the pipe restriction work into this varying water supply problem?
« Last Edit: June 15, 2008, 08:37:52 AM by thirteen »
MntMnROY 13

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Re: Hydro in the Gutters
« Reply #44 on: June 15, 2008, 09:58:10 AM »
Don't know: I'll ask my daughter when she goes!  B^> B^>


Rgds


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DrDave

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Re: Hydro in the Gutters
« Reply #45 on: June 15, 2008, 03:24:30 PM »
What if instead of catching the rain, you catch just one lightning bolt?

Put that in a battery.  How many watts is that?
« Last Edit: June 15, 2008, 03:24:30 PM by DrDave »

ghurd

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Re: Hydro in the Gutters
« Reply #46 on: June 15, 2008, 05:39:33 PM »
My calculator says exactly 10x12.667^Boo-Koo.

G-
« Last Edit: June 15, 2008, 05:39:33 PM by ghurd »
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MattM

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Re: Hydro in the Gutters
« Reply #47 on: June 15, 2008, 06:28:03 PM »
That would make sense if your home could support 62400 pounds of water on a rooftop.  Otherwise you better be draining off at the same rate the water is collecting.  If you are draining at the same rate you are collecting then your water is in freefall.  Once your restrict the flow until its backed up all the way down that 100' drop then you now lose energy from the pressure of going through a pipe.  Now you just added in atmospheric pressure into the equation.  This is all going to get a lot more complicated then a simple 100' drop.
« Last Edit: June 15, 2008, 06:28:03 PM by MattM »

joestue

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Re: Hydro in the Gutters
« Reply #48 on: June 15, 2008, 08:00:34 PM »
10,000 amps x 100Mv = About one TeraWatt.
« Last Edit: June 15, 2008, 08:00:34 PM by joestue »
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TomW

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Re: Hydro in the Gutters
« Reply #49 on: June 16, 2008, 10:37:38 AM »
I say direct the bolt to a small pressure vessel with water in it super heat the water flash to steam drive a weight upwards on a ratchet system


Actually think this is doable but at what cost I don't know.


Lets see, flash 1 cup [8 ounces] water into steam creates X cubic inches / feet of steam?


Tom

« Last Edit: June 16, 2008, 10:37:38 AM by TomW »

joestue

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Re: Hydro in the Gutters
« Reply #50 on: June 16, 2008, 05:26:31 PM »
TomW, the details are numerous.


Electrically, it is possible to store the energy, basically make a gigantic tapped tank circuit, a lightning spike will charge it, then over the next few minutes rectify it slowly.

The energy available is proportional to the height of the antenna. so when we say 10 kiloamps, at 100 mega volts, that's for the 5 mile long strike.

To be practical, this needs to to be in the middle of a well insulated sky scraper.


There is a thread on sciencemadness about using a glass tube full of carbon powder in order to make a sh*t ton of diamond powder, but no one is sure if that will even work, buckyballs, nanotubes and graphite more likely...


only one small issue: containment... a glass carbon thermal bomb...


Same issue applies to the water, and the added effect of water breaking down at 500v/mm into a relatively low resistance short circuit, not something we want.


basically it will take just as much effort to extract any energy out of the water as it would be to store it electrically, also, supposing you are able to match the water at 2000K/10,000Psi for a normal lighting strike, what happens when a lightning bolt makes this pressure/temperature 10 times higher than normal?

electrically the voltage would be 3.2 times higher...

if your response to this is to design it for 800K at 1,000 psi... well, not much usable energy there...


It is an absolute waste to even think about recovering energy from lighting bolts, because the materials invested could be used to make thousands of times more energy somewhere else.


I grew up in a lighting devoid area, but i have always been interested in testing lighting's effect on things, and certainly if you could find a lighting attractor, you have at least one buyer.

« Last Edit: June 16, 2008, 05:26:31 PM by joestue »
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wdyasq

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Re: Hydro in the Gutters
« Reply #51 on: June 16, 2008, 07:16:31 PM »
I can't believe a moderator just steered this thread further off topic!


If you folks want to start your own thread on absurd ideas, the posting button is on the right near the top of the page..... THIS absurd idea is my post...


Ron

« Last Edit: June 16, 2008, 07:16:31 PM by wdyasq »
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MattM

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Re: Hydro in the Gutters
« Reply #52 on: June 16, 2008, 07:53:42 PM »
You're right, I was calculating the velocity delta not the average velocity.  Once again you point my grammar out to be wrong but totally ignore the reality of the proof.  The grammar was wrong but the result was still correct.
« Last Edit: June 16, 2008, 07:53:42 PM by MattM »

joestue

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Re: Hydro in the Gutters
« Reply #53 on: June 16, 2008, 11:12:59 PM »
omg, no, the result is not correct, average velocity is of no interest to anyone here.and i did not correct your grammer, it is perfectly  understandable at the moment.


furthermore, if the energy and power are as you suggest, then we can get more out by cascading n systems. this is obviously not true. do you know what this means?


_________________________


MATTM said "17.333 pounds per second times 12.68266 feet per second is equal to approximately 220 foot-pounds per second, which is also .4 horsepower."


I see what you are doing, and i'm trying to explain it to you without re-proving newton's laws, you evidently don't understand them.


calculate the kinetic energy: no, i'm not going to derive it for you, but i did in physics class...



  1. 33 pounds/second x (12.7 ft/sec)^2 x .5 = you figure this out and tell me what you get in imperial units, then compare to mks...
  2. 87 kg/s * 3.87m/s^2 x .5 = 58.99 watts.
  3. foot pounds/s = 298 watts.


answer this question: how much power does it take to lift 17.33 pounds of water 10 feet per second?


DEFFINITION: work is done then a force acts over a distance. one horse power is lifting 550 pounds one foot off the ground in one second

lifting 33000 pounds one foot off the ground in one minute

lifting 55 pounds of water 10 feet off the ground in one second,

do you see where this is going?

pushing a car down the road at 15 miles per hour. ~approx~

pushing a train at a few inches per second...~approx~


pounds is a unit of force, i ignored the kinetic energy still in the water, after it got lifted off the ground..

it's a squared function of speed , so we can ignore it for relatively slow moving objects.


OVERUNITY  [10 feet, 220 out, 173.33 in], [40.3% at 100, 700 out, 1733 in], what do you get for 10,000 feet?


using you math,

ttf 10,000 feet is 24.99 seconds[i agree, this is elementary]

average speed is 400 feet/second [i agree, this is also elementary]

400 feet/second x 17.33 pounds/second is 6932 foot pound/sec or 12 horsepower

speed at bottom [800ft/sec conveniently always twice the average speed for acc.= constant and V_i = zero] x 17.33 pounds/sec is 24 horsepower.


power needed to lift 17.33 pounds of water per second to 10,000 feet: 173,300 foot pounds/sec or 315 horsepower!


your math results in a 3.8 % out using average speed, and 7.6 % out using peak speed


in fact, if we cascade one thousand of your ten foot drops, and drop 17.33 pounds of water out of an air plane... we get 2.2 million foot pounds out of the system, and we put 173 thousand in.


whereas if we dropped it all the way at the bottom we'd get 13.86 thousand foot pounds by your 'math'


__________________________


  17. 333 gallons per second times 0.001818 horsepower is 0.031512 horsepower


Now this is for one foot displacement per pound without the effects of gravity.  Let's factor in gravity...  Using math we can figure the time necessary for the water to fall 10 feet by using the equation for the distance that the object falls in a given time. This equation is d = gtĀ²/2

_
_________________________


you invented more math!


assuming you meant 17.33 pounds/sec


17.33 pounds/sec is a flow rate, a unit of force exerted by the earth, on the water, not mass.

in theory, it would take NO energy to move 17.33 pounds of water per second.

in practice, it takes almost no energy. (joules or less, we don't have to move it again, after it's moving
_ Newtons first law__)


multiply this by height to get work.


divide by time to get power, but since we already did that (pounds/sec), we DO NOT do it again.

« Last Edit: June 16, 2008, 11:12:59 PM by joestue »
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MattM

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Re: Hydro in the Gutters
« Reply #54 on: June 17, 2008, 05:58:45 AM »
Once again you brought up the "average velocity" comment which I already said was not correct.  The water settles on the roof in the form of rain.  According to the op you have 62,400 pounds of water over the course of an hour, which is 17.33333333333333 pounds/second.  If your home can support 62,400 pounds then great, store it all at once.  Otherwise you have to drain it as it comes, which is what a gutter system does.  So you are starting with a velocity of zero and end up with a change after 10 feet, 75 feet, 100 feet, etc.


Now you're perverting the whole argument when you know that air resistance and terminal velocity were not part of the original equation for a reason; I kept it simple.  Perhaps now you want to get more granular to make a point that originally was only to show the amount of energy in the venture is still trivial even if you lived next to a 75' cliff to generate power from the rainwater.


But whoa is me because somehow I proclaimed over-unity.....

« Last Edit: June 17, 2008, 05:58:45 AM by MattM »

joestue

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Re: Hydro in the Gutters
« Reply #55 on: June 17, 2008, 02:27:05 PM »
You did achieve over unity!!! you got 220 foot pounds out when it only took 173 to lift the water back up the 10 foot drop!


not only that, you obviously didn't read this:


furthermore, if the energy and power are as you suggest, then we can get more out by cascading n systems. this is obviously not true. do you know what this means?


or this:

DEFFINITION: work is done then a force acts over a distance. one horse power is lifting 550 pounds one foot off the ground in one second

lifting 33000 pounds one foot off the ground in one minute

lifting 55 pounds of water 10 feet off the ground in one second,

do you see where this is going?

pushing a car down the road at 15 miles per hour. ~approx~

pushing a train at a few inches per second...~approx~


pounds is a unit of force!!!!


You were the one who added terminal velocity, this is what you wrote:


"Now we need to figure the average velocity for the object in order to figure out the force it will have at the 10 feet mark.  We know the distance and the time travelled, therefore we can calculate the distance over the time.  At the .78847795 seconds mark the water is travelling at 12.68266 feet/second."


"17.333 pounds per second times 12.68266 feet per second is equal to approximately 220 foot-pounds per second, which is also .4 horsepower."


and i proved it is incorrect:


lifting 17.33 pounds of water 10 feet per second required only 173 foot pounds per second

« Last Edit: June 17, 2008, 02:27:05 PM by joestue »
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TomW

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Re: Hydro in the Gutters
« Reply #56 on: June 17, 2008, 03:44:45 PM »
Geeze, guys. Give it up.


Nobody is gaining anything by this constant math exercise. Anyone with half a brain gets that there is very little power from your roof. Period. End Quote.


Why argue it beyond that?


Take it to a physics forum if you must decide who is cracked and who is merely arrogant about their math skills. The feedback I am getting off board is that its just a dead end waste of board space.


Then, again, I have no interest in wannabe armchair arguing from the academics. We are here for builders, you know.


Just my opinion.


Tom

« Last Edit: June 17, 2008, 03:44:45 PM by TomW »

joestue

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Re: Hydro in the Gutters
« Reply #57 on: June 17, 2008, 04:16:51 PM »
I was about to email my high school physics teacher with the statement:


"(force/time) times velocity equals energy"


and Then I though the better of it.


peace Matt.., please post this on www.physicsforums.com

« Last Edit: June 17, 2008, 04:16:51 PM by joestue »
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MattM

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Re: Hydro in the Gutters
« Reply #58 on: June 17, 2008, 10:54:20 PM »
Not a problem, Tom.  I think that Joe was just stuck on the 10 foot drop being over a 1 second time frame and doesn't realize gravity pulls it down in a fraction of a second, making the power required for lifting and the power generated by dropping different although the actual energy in both exercises is the same.  The differences between energy (W or F) and power (W/t or F/t) are ideas people confuse.
« Last Edit: June 17, 2008, 10:54:20 PM by MattM »

joestue

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Re: Hydro in the Gutters
« Reply #59 on: June 18, 2008, 03:47:21 PM »
everything i said was correct for a constant flow of water. post your math on a physics forum and you will be forced to explain things in concepts, not specific examples.


"making the power required for lifting and the power generated by dropping different although the actual energy in both exercises is the same"


constant flow of water = constant power out MattM


further more we have a simple concept known as conservation of energy....

« Last Edit: June 18, 2008, 03:47:21 PM by joestue »
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MattM

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Re: Hydro in the Gutters
« Reply #60 on: June 18, 2008, 04:54:32 PM »
Unfortunately, joe, it still would not convince you even when the people in the physics forum agreed with me.  You are not understanding that the power to lift 17.333 pounds of water 10 feet in 1 second is NOT the same amount of power you generate in dropping 17.333 pounds of water 10 feet in .78847795 seconds.  (Thus you do not understand where I came from saying 173.33 pounds/second is less than 220 pounds/second.)  Power is simply an amount of energy exerted over a time frame and if that time frame is less than 1 second then the relative units for power will grow accordingly (i.e. 220 pounds/second in that 10 foot, .78847795 seconds drop) although the amount of energy (173.333 foot-pounds) does not change.


If you simply cannot grasp these points then arguing with you is pointless.

« Last Edit: June 18, 2008, 04:54:32 PM by MattM »

TomW

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Re: Hydro in the Gutters
« Reply #61 on: June 18, 2008, 05:11:37 PM »
What part of "give it up" don't you get?


Tom

« Last Edit: June 18, 2008, 05:11:37 PM by TomW »

joestue

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Re: Hydro in the Gutters
« Reply #62 on: June 18, 2008, 05:25:44 PM »
I completely understand that Matt!


but that wasn't your original claim.


when you originally replied to Rossw's post that ten times the head would give 10 times the energy and i said power as well. you said more like 3 times the power


Both he and I assumed we aren't quantifying packets of water free falling, and capturing bursts of energy at the bottom, but rather a steady stream of water measured in pounds per second. also a common error, water is measured in mass/second.


the same flow of water at 10 times the pressure, head etc gives ten times the energy, and therefore power, because time is relative to the rate of falling water.


the irony here is my statement "(force/time) times velocity equals energy" was correct, and a typo, i intended to quote your statement:

"Z pounds per second times Y feet per second is equal to approximately W foot-pounds per second:


producing the following: FV/s^2 = power


a simple concept, but you got the physics all wrong


FV=power

1/2mV^2 = energy

and 1/2mV^2/s = power.

mgh= gravitational potential energy and divide by time to get power.


don't even try arguing with those concepts, derived from newton's three laws.


if you have 17.33 pounds of water falling at 12.68266 feet per second. and you attain 220 foot pounds/sec , the obviously the flow of water isn't continuous, and this is a point you failed to explain in the beginning.

« Last Edit: June 18, 2008, 05:25:44 PM by joestue »
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joestue

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Re: Hydro in the Gutters
« Reply #63 on: June 18, 2008, 05:32:32 PM »
please delete the thread
« Last Edit: June 18, 2008, 05:32:32 PM by joestue »
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MattM

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Re: Hydro in the Gutters
« Reply #64 on: June 19, 2008, 05:31:37 AM »
You want to argue mass flow rate with a sheet metal guy?  Seriously.  You aren't even filling in the right factors.
« Last Edit: June 19, 2008, 05:31:37 AM by MattM »

DamonHD

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Re: Hydro in the Gutters
« Reply #65 on: June 19, 2008, 06:29:18 AM »
Hi Guys,


Absolutely none of my business not being a mod (thank goodness for us all!) but could you both drop it?


I have a fairly firm view of which one of you is right but that's by-the-by.


The "miss-miss-miss-he-said-it-wrong" tone is quite tiresome.


The point is it's pointless anyway, so why burn all this mental energy and goodwill in willy-waving for the rest of us?  You may be confusing your audience with PeopleWhoGiveAMoneysCuss(TM).  Please.


Rgds


Damon

« Last Edit: June 19, 2008, 06:29:18 AM by DamonHD »
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