So does water/lithium bromide, depending on what you are trying to cool (the poster did not say).
I have seen a number of articles on systems which used ammonia refrigerant, calcium chloride (ice melter - CHEAP!) as the absorbent, and the rest of the pressure system was standard sizes of steel pipe and fittings. The concentrator was a parabolic cylinder, which works very well for putting energy onto a target which is a ten foot long pipe. You might have some hassles getting the ammonia (you need anhydrous, not the weak solutions sold for cleannig) to charge the thing - too many people make methamphetamine from it.
Break the circuit when you don't need the cooling. (Any EEs want to comment on if this can damage the solar cells?)
Depends exactly how you do it. Solar cells are just enormous, forward-biased silicon diodes with the junctions hanging out where photons can generate new electron-hole pairs. If you don't drain the pairs as they're created, they charge the diode up to the point where they recombine at the junction.
For a typical panel you will not have any trouble if you just leave it out in the sun open-circuited. However, if you parallel several of them and don't use anti-backflow diodes, you can dump the power of one or more back through the one with the lowest voltage (typically the hottest). This can lead to thermal runaway (voltage drops with temperature) and fire. Ergo, anti-backflow diodes are one of the most basic elements of a properly designed solar system using parallel panels.
because you need economies of scale to make anything like that work, and unless you can get an old MRI machine as scrap and one of your in-laws is a liquid helium vendor, you're just not going to be able to get the hardware and keep it anywhere near running condition by your lonesome.
If you're trying to store cold, do what they did 200 years ago: put ice inside something insulated. Back then they used barns with walls full of sawdust, but we can do a lot better today.
You'll get few from that article, unfortunately. For instance, the muons come from the collision of cosmic rays with nuclei high in the atmosphere; some of the resulting particles are pions, which decay to muons on the way down. But the author (or editor, in some idiotic attempt to make the article more "accessible") completely misled his readers by writing nonsense such as
Remnants of space dust that constantly showers the world....
when "space dust" has nothing to do with it, and
Since there are fewer muons in an empty space than in solid rock or earth...
which has no relation to reality that I can see.
The system works a lot like a CAT scanner, where the absorption of penetrating radiation is measured over a variety of different paths through the object to be scanned. The only real difference is that the radiation is muons rather than X-rays (less easily absorbed, thus able to provide detectable signals through a hundred meters of rock - you should see what Fermilab uses to absorb muons so they can do neutrino experiments) and the source is natural. If you had enough money you could make your own muon source and scan the thing yourself, but when nature has been so obliging there's really no great need.
I don't know what you're paying for new batteries (presumably the same gray rectangular things with the tab connectors which are so common in other hardware such as emergency exit lamps), but you may be able to get cheaper.
Trolling/deep cycle batteries are available retail for rather reasonable sums. Some of them are sealed, but some are not; a non-sealed battery allows you to check it for water level and state of charge (via the specific gravity of the electrolyte). Plus, they usually offer several times the AH rating of the little gray things (good if outages may be extended). The UPS will feed quite nicely from most any 12-volt DC source.
If you decide to hook up something like this, you'll have three issues:
Cabling and connectors will have to be anti-chafed, fused, and otherwise protected in ways that the monolithic UPS box takes care of for you. Did I mention that you get to build this?
The battery chemistry is similar but the actual charging requirements may differ; you are going to have to watch the battery state of charge yourself. (On the plus side, if the batteries are external to the UPSs you can just rotate batteries out every so often.)
Most significant: a UPS modified to use external batteries is no longer UL certified, and may not be legal to use in your situation.
It's up for you to research and present to your boss for a decision. I have a little UPS which had dead batteries and the honkin' hunka lead that I hooked up in their place carried me nicely through last August's blackout, but your results may differ.
Remember that deep-discharging is very hard on lead-acid.
So is chronic over-charging, which depletes the electrolyte. The UPS mfgr has no real motive to optimize the charging systems (hey, if they sell more UPSs when people only need new batteries, they make more money) and it is contrary to the purpose of a UPS to cycle the battery at intervals to determine capacity.
What you might want for this is external batteries. More on this in another post, maybe.
Even the firestorms in Germany created by incendiary bombs and the atomic bomb in Japan left charred remains.
Yes they did... to some degree. To what degree can that be true and still be consistent with the (possibly overblown) description of the fire marshal?
So, while there are definately, some things that can be explained by radiation, it is by no means the whole story.... Something different is going on here.
You've just asserted a positive. You're implying that, of all the known phenomena (direct contact by flame, radiation, embers, flashover from combustible gases - were there underground tunnel networks in pre-fire Chicago?) nothing accounts for the fire "burning everything" and igniting buildings to the windward in a gale.
Is there any physical evidence remaining to qualify or quantify the elements of the fire marshal's account? If not, you're drawing conclusions from zero data.
Radiation does indeed account for rubbish being burned (radiant heat would ignite it) and for a fire burning upwind (radiation is not affected by the wind, and the leeward side of a windowed building could be ignited just as easily by radiation as the windward side). Once ignited, the building could flash over inside and begin radiating heat on its own windward side, continuing the process. This might be easier after the winds from a firestorm have had some time to dry out buildings.
Radiation isn't the whole story. Embers falling out of the smoke cloud have their own chance to do their thing.
Brick and stone buildings are usually supported by internal timbers and have plenty of combustibles inside. Once those ignite (especially all at once, and supported by radiant heat from the environs) they could weaken quickly and bring the whole structure down. Buckling of masonry from radiant heat could account for more of this; typical fires do not involve whole blocks and wouldn't exhibit this phenomenon enough to be familiar.
You get interesting colors in fires when you add metallic salts. Copper salts in particular burn green, and copper roofs used to be much more common than they are now.
I think that one would need to account as completely as possible for known phenomena before asserting that unknown phenomena were at work in the Chicago fire.
Buildings burned on a timescale of minutes, it was reported. Unlike your normal everyday fire, nothing was left half-burned. It also burned INTO the wind, which is contrary for usual fires. A guy in the New York Evening Post wrote, "buildings far beyond the line of fire, and in no contact with it, burst into flames from the interior". The other facts I noted may be referenced in The Annual Record of Science and Industry for1876, pg. 84 and History of the Great Conflagration Sheahan & Upton, Chicago, Illinois, 1871
If you have a large and hot enough fire, heat radiation will be able to raise material to its ignition temperature some distance away. (This can be observed in forest fires; trees will burst into flame when the fire has not yet reached them. I understand that houses in the path of forest fires often burn when radiant heat ignites things like drapes.) This would also explain why a building would burn in minutes: when every room facing the front of the fire is ignited more or less at once, and the subsequent flashover ignites the far side a short time later, the building is going to burn much faster than if the blaze started at a single point.
In other words, is there any way to conceive of a black hole at the center of a neutron star?
I don't believe so. IANAastrophysicist, but I can repeat the popular treatment that I read once without too many errors (I hope).
As the pressure on the matter in the neutron star increases, the velocity of the various particles (electrons, quarks) inside has to increase to resist it.
The increase in velocity also increases the mass-energy.
At some point the relativistic increase in the mass of the matter due to its greater velocity causes self-gravitation to equal the increased pressure. At this stage there is no possibility of pushing back any harder, and the core begins to collapse further.
This collapse never ends; it becomes a black hole.
There is not much of a burst of radiation. The matter falling into the BH is already at neutron-star densities and higher, and the free electrons and other charged particles scatter photons around the infalling matter rather than letting them travel in straight lines. The random-walk of photons carries them right into the BH along with the matter.
If the pilot puts on a parachute for the first flights... I don't see what could go so badly wrong.
If you are not high enough to get clear of the aircraft and open the 'chute before the ground riseth up and smiteth thee, it's no help at all. (Some military aircraft have zero/zero ejection seats which can throw you high enough even if you have an incident in taxi on the runway, but this little flying wing ain't one of 'em.)
There are lots of people who've died by stalling an aircraft at low altitude, such as on approach to landing. If you've got enough altitude this is no problem, but down low you may run into the ground before you can get the airplane back under control. This is one reason why you do not do steep turns in the landing pattern.
I'm curious as to how they distinguish between a "normal" dust cloud and one that's due to an Earth sized planet.
The article states "The size of the largest objects in the disk determines the dust production rate. The amount of dust peaks when 600-mile protoplanets have formed." The dust forms in roughly the same orbit as the planet, so presumably you could detect a protoplanet forming at an Earth-like distance by watching for dust at a temperature of ~250 K; if there was the amount of dust you'd expect from an 8000-mile planet (well down from the peak at the 600-mile planetoid size), you might well have something like the prototypical Earth in that orbit.
I'm not sure how useful this is going to be in locating habitable planets; getting to them long before the intense bombardment phase has stopped isn't going to make for good colonization prospects. On the other hand, as a way of calculating the prevalence of Earth-like planets this is a huge breakthrough.
With an attitude like that, it's a wonder how Wright brothers managed to create a successful "flying machine". I mean, when you think about it, what they did was by far more dangerous!!!
You're exactly right. Which is why we should not be repeating deadly mistakes for the sake of cartoon fans.
It would be much worse than riding a fast motorcycle, because most'cycles (even fast ones) have enough stablility to be ridden hands-off.
That flying wing sure isn't going to. Just the pendulum instability from the offset between CG and CL (that's center of gravity and center of lift for you 'dotters who never study anything but web engines and FPS technique) is going to drive you bats, and each change in thrust or drag is going to result in pitch moments. If designed badly, these can be fatal; if you have any doubts about this, you should look into the history of "interesting" airplanes like the original Mignet HM-14 Flying Flea.
There is a very real possibility of any such craft having serious PIOs (pilot-induced oscillations). Have them in a situation where you have no time to recover, and you can lose the airframe along with the crew.
While I am a firm believer in the value of Darwin Awards, I thnk that such a machine should not be flown with a human aboard. No matter how utterly fucking kewl all those anime fans would think it was, their refusal to recognize the distinction between cartoon physics and reality is not worth someone else's life, or undamaged brain, or functional spinal cord. It's appropriate that such a machine fly with only a dummy aboard; if it cracks up, you've got a hilarious photo-op rather than a tragedy.
So much commentary on that sig of mine (yours being the latest). All offer clarification of a process that is only postulated via inaccurate models (which the authors of those models will hasten to admit).
And what is wrong with inaccurate (meaning, imperfect) models? To be perfect, a model would have to be the thing that it models. This is impossible, or nearly so. Less than perfect models are still very useful in many cases.
" One of the projected effects of global warming..." indeed! The mind reels at the blind faith that motivates such comments.
"One of the projected effects of the frontal system which will be passing through here today is dangerous hail." That's one projection you'd be a fool to ignore whether or not it actually comes to pass.
explain the link between the warm water corals and the malarial mosquitoes. Explain what in their environment is causing such a migration and explain why that environment is changing.
The "what" appears to have been pinned down by climatologists already, probably using things like oxygen isotope ratios. The why is the matter under dispute. The link is that warm waters mean milder winters, which in turn mean the range of the malarial species moves northward.
What will be interesting is at what point you draw in "science by consensus" a la global warming, as in, "it is generally believed". You are quite
close with "it appears likely" i.e. "we guess".
Any time you are dealing with a first-time or non-repeatable phenomenon you are going to use a certain amount of guesswork. What you ignore is that the amount of guesswork is steadily going down, and the projections are not converging on the status quo ante.
Show the science. Explain. Give proof.
There is no PROOF of most scientific principles, only a body of evidence of varying size and precision without obvious contradictory evidence. If you really want the science, you are asking in the wrong forum - it's in a lot of places if you care enough to look. Failing to look isn't going to do much for your bona fides either.
If you don't have that, then its just another religious belief.
Oh, a variant of the argument from ignorance. "We can't be certain, so all guesses are equally good." Sorry, I'm smarter than that - pity everyone isn't!
One of the projected effects of global warming is to increase the variability of weather. This means a greater probability of cold snaps in winter, as well as heat waves in summer, cycles such as El Nino driven harder, in addition to generally hotter conditions averaged over the earth.
Warm-water corals are moving northward along the Atlantic coast of Florida, and (getting slightly back on-topic) it appears likely that malarial mosquitoes will be able to move north right along with them. Move over, West Nile; the really BIG killers are coming to major population centers near you!
Malaria has numerous animal reservoirs (like flu), so a vaccine is not going to wipe it out (unlike smallpox or polio). This leaves the organism the opportunity to evolve to better infect humans despite vaccination. Malaria has evolved to be resistant to drugs such as chloroquine, so it would not surprise me to watch it evolve to suppress or alter the antigens which make it recognizable by the vaccine-primed immune system.
Vaccines would be a good component of a defense-in-depth; the downside is that the wild reservoirs would have to be monitored and the vaccine updated (and people re-vaccinated) when it mutated.
One item of interest is that this new technique converts ethanol to hydrogen at a 60% efficiency rate, compared to the 20% efficiency rate with current technology.
The press release states
"Ethanol made from corn has already been used to power some car engines, but the process is only 20% efficient. Moreover, all traces of water must be removed before the ethanol can be used as a fuel, which adds to processing costs. Now, the Minnesota-Patras team says that if ethanol was used to make hydrogen for fuel cells, the process would be 60% efficient and the ethanol would not need to be pure."
This is an apples-oranges comparison; the engine is converting fuel to work, not fuel to another fuel. To directly compare against the other pathway you need to take other factors into account:
Ethanol to hydrogen conversion: 60%
Hydrogen fuel cell efficiency: 80%
Electric motor efficiency: 90%
Overall efficiency: 43.2%
So you're a bit better than twice as efficient, if you do not take full advantage of the high octane of ethanol to raise compression and improve the thermal efficiency of the IC engine. If you can get up to diesel levels you can achieve ~40%, and the efficiency advantage of the hydrogen pathway becomes very small.
Yes it takes a lot of energy to make - a lot of solar energy and water in a method commonly known as 'growing'.
And more than 0.8 BTU of fossil inputs for fertilizer, chemicals and distillation to get 1 BTU of fuel out given current best practices.
You might claim it could be made lots better. SO FREAKING WHAT? That is how it is done, and nobody is pushing to make the ethanol tax abatement contingent on the use of non-fossil-derived fertilizers and solar distillation. Maybe if you could get your solar hydrogen plant (making clean but really-hard-to-squeeze-into-tanks hydrogen) to make ammonia without any fossil CO2 emissions, you'd have something. You could use hydrogen in a Sabatier reactor to process the CO2 from the fermentation into methane (a far more useful fuel than H2) and the byproduct heat from the Sabatier reactor to help distill the ethanol. But you'll notice that nobody, but nobody, is doing this.
Chippewa Valley installed a 1500 HP boiler to generate steam for their distillation. However, they are not even co-generating electricity to offset their consumption; the investigation of this was left to the state.
It's probably like a lot of reactions that are favored by energy balances but have picky requirements; it proceeds all by itself, but v-e-e-r-y s-l-o-o-w-l-y.
Why is the titanium catalyst required? How does that work?
You might find that in a paper in Science. I seem to recall seeing other things about TiO2 being a photoactive catalyst for various reactions (bacteriocidal effects?). It seems to be be able to perform a number of useful reactions. And the really cool thing is that it's already used in lots and lots of paint.
According to the article, the NOx-conversion still works after the CaCO3 is exhausted; it just does not neutralize the resulting HNO3. I still think it would be clever to use the acid to remove the spent paint.
If we get smart and change most of our transport energy from internal combustion to electric, we'll also get rid of much of the nitrogen oxides we generate. At that point the lifespan of the paint might increase to 10 years or more, long enough that surfaces will be repainted because of weathering before the buffering wears out.
Bottom layer is an acid-sensitive primer, top layer is Ecopaint. When the buffering capacity of the Ecopaint is exhausted, the acid works its way down to the primer, which de-bonds. When the Ecopaint is peeling, it's time to power-wash and put on a new coat.
When the carbonate has been exhausted, the titanium dioxide will continue to break down NOx, but the acid this produces will discolour the paint.
One would expect the acid to etch concrete and other alkaline building materials, but given the rate at which concrete deteriorates from freeze-thaw and other assaults it might not be a big maintenance problem.
Clever. Very clever. It reminds me of the concept of the catalytic-converter car radiator coating which would eat atmospheric ozone; this one consumes ozone precursors, but WTF?
Slashdot Mirror
I have seen a number of articles on systems which used ammonia refrigerant, calcium chloride (ice melter - CHEAP!) as the absorbent, and the rest of the pressure system was standard sizes of steel pipe and fittings. The concentrator was a parabolic cylinder, which works very well for putting energy onto a target which is a ten foot long pipe. You might have some hassles getting the ammonia (you need anhydrous, not the weak solutions sold for cleannig) to charge the thing - too many people make methamphetamine from it.
For a typical panel you will not have any trouble if you just leave it out in the sun open-circuited. However, if you parallel several of them and don't use anti-backflow diodes, you can dump the power of one or more back through the one with the lowest voltage (typically the hottest). This can lead to thermal runaway (voltage drops with temperature) and fire. Ergo, anti-backflow diodes are one of the most basic elements of a properly designed solar system using parallel panels.
Read Home Power and you'll know this too.
If you're trying to store cold, do what they did 200 years ago: put ice inside something insulated. Back then they used barns with walls full of sawdust, but we can do a lot better today.
The system works a lot like a CAT scanner, where the absorption of penetrating radiation is measured over a variety of different paths through the object to be scanned. The only real difference is that the radiation is muons rather than X-rays (less easily absorbed, thus able to provide detectable signals through a hundred meters of rock - you should see what Fermilab uses to absorb muons so they can do neutrino experiments) and the source is natural. If you had enough money you could make your own muon source and scan the thing yourself, but when nature has been so obliging there's really no great need.
Trolling/deep cycle batteries are available retail for rather reasonable sums. Some of them are sealed, but some are not; a non-sealed battery allows you to check it for water level and state of charge (via the specific gravity of the electrolyte). Plus, they usually offer several times the AH rating of the little gray things (good if outages may be extended). The UPS will feed quite nicely from most any 12-volt DC source.
If you decide to hook up something like this, you'll have three issues:
It's up for you to research and present to your boss for a decision. I have a little UPS which had dead batteries and the honkin' hunka lead that I hooked up in their place carried me nicely through last August's blackout, but your results may differ.
What you might want for this is external batteries. More on this in another post, maybe.
- Is there any physical evidence remaining to qualify or quantify the elements of the fire marshal's account? If not, you're drawing conclusions from zero data.
- Radiation does indeed account for rubbish being burned (radiant heat would ignite it) and for a fire burning upwind (radiation is not affected by the wind, and the leeward side of a windowed building could be ignited just as easily by radiation as the windward side). Once ignited, the building could flash over inside and begin radiating heat on its own windward side, continuing the process. This might be easier after the winds from a firestorm have had some time to dry out buildings.
- Radiation isn't the whole story. Embers falling out of the smoke cloud have their own chance to do their thing.
- Brick and stone buildings are usually supported by internal timbers and have plenty of combustibles inside. Once those ignite (especially all at once, and supported by radiant heat from the environs) they could weaken quickly and bring the whole structure down. Buckling of masonry from radiant heat could account for more of this; typical fires do not involve whole blocks and wouldn't exhibit this phenomenon enough to be familiar.
- You get interesting colors in fires when you add metallic salts. Copper salts in particular burn green, and copper roofs used to be much more common than they are now.
I think that one would need to account as completely as possible for known phenomena before asserting that unknown phenomena were at work in the Chicago fire.- As the pressure on the matter in the neutron star increases, the velocity of the various particles (electrons, quarks) inside has to increase to resist it.
- The increase in velocity also increases the mass-energy.
- At some point the relativistic increase in the mass of the matter due to its greater velocity causes self-gravitation to equal the increased pressure. At this stage there is no possibility of pushing back any harder, and the core begins to collapse further.
- This collapse never ends; it becomes a black hole.
- There is not much of a burst of radiation. The matter falling into the BH is already at neutron-star densities and higher, and the free electrons and other charged particles scatter photons around the infalling matter rather than letting them travel in straight lines. The random-walk of photons carries them right into the BH along with the matter.
And I hope that wasn't too far off the mark.The NEAR spacecraft landed on the asteroid Eros over 3 years ago. Eros is rather eccentric, spinning, and small by our usual standards.
There are lots of people who've died by stalling an aircraft at low altitude, such as on approach to landing. If you've got enough altitude this is no problem, but down low you may run into the ground before you can get the airplane back under control. This is one reason why you do not do steep turns in the landing pattern.
I'm not sure how useful this is going to be in locating habitable planets; getting to them long before the intense bombardment phase has stopped isn't going to make for good colonization prospects. On the other hand, as a way of calculating the prevalence of Earth-like planets this is a huge breakthrough.
That flying wing sure isn't going to. Just the pendulum instability from the offset between CG and CL (that's center of gravity and center of lift for you 'dotters who never study anything but web engines and FPS technique) is going to drive you bats, and each change in thrust or drag is going to result in pitch moments. If designed badly, these can be fatal; if you have any doubts about this, you should look into the history of "interesting" airplanes like the original Mignet HM-14 Flying Flea.
There is a very real possibility of any such craft having serious PIOs (pilot-induced oscillations). Have them in a situation where you have no time to recover, and you can lose the airframe along with the crew.
While I am a firm believer in the value of Darwin Awards, I thnk that such a machine should not be flown with a human aboard. No matter how utterly fucking kewl all those anime fans would think it was, their refusal to recognize the distinction between cartoon physics and reality is not worth someone else's life, or undamaged brain, or functional spinal cord. It's appropriate that such a machine fly with only a dummy aboard; if it cracks up, you've got a hilarious photo-op rather than a tragedy.
Warm-water corals are moving northward along the Atlantic coast of Florida, and (getting slightly back on-topic) it appears likely that malarial mosquitoes will be able to move north right along with them. Move over, West Nile; the really BIG killers are coming to major population centers near you!
Vaccines would be a good component of a defense-in-depth; the downside is that the wild reservoirs would have to be monitored and the vaccine updated (and people re-vaccinated) when it mutated.
You might claim it could be made lots better. SO FREAKING WHAT? That is how it is done, and nobody is pushing to make the ethanol tax abatement contingent on the use of non-fossil-derived fertilizers and solar distillation. Maybe if you could get your solar hydrogen plant (making clean but really-hard-to-squeeze-into-tanks hydrogen) to make ammonia without any fossil CO2 emissions, you'd have something. You could use hydrogen in a Sabatier reactor to process the CO2 from the fermentation into methane (a far more useful fuel than H2) and the byproduct heat from the Sabatier reactor to help distill the ethanol. But you'll notice that nobody, but nobody, is doing this.
Chippewa Valley installed a 1500 HP boiler to generate steam for their distillation. However, they are not even co-generating electricity to offset their consumption; the investigation of this was left to the state.
If we get smart and change most of our transport energy from internal combustion to electric, we'll also get rid of much of the nitrogen oxides we generate. At that point the lifespan of the paint might increase to 10 years or more, long enough that surfaces will be repainted because of weathering before the buffering wears out.
Bottom layer is an acid-sensitive primer, top layer is Ecopaint. When the buffering capacity of the Ecopaint is exhausted, the acid works its way down to the primer, which de-bonds. When the Ecopaint is peeling, it's time to power-wash and put on a new coat.
Clever. Very clever. It reminds me of the concept of the catalytic-converter car radiator coating which would eat atmospheric ozone; this one consumes ozone precursors, but WTF?