Fluorescents are perhaps 30% efficient. If reflectors can nearly double the light output of LEDs by using light that would otherwise have been absorbed by the back, the LEDs could beat the efficiency of fluorescents.
This is not as difficult as it sounds. Fluorescent lights have two conversion stages (electricity to UV in the mercury vapor, UV to visible light in the phosphors) and each conversion has losses. LEDs have only one, which gives the LED an inherent advantage.
What I'm getting at is, how much of this waste is comparable (in terms of which specific materials, and in what volumes) to what a nuclear powerplant would produce?
Not at all comparable. Fresh PWR fuel is pellets of uranium dioxide (a very hard, refractory ceramic) in zirconium tubes; the spent fuel is largely the same with about 3% of the uranium removed and fission products and plutonium added. Swelling of the pellets due to displacement of nuclei from their neat crystal lattices can damage the Zr cladding.
The Hanford wastes are composed of the byproducts of reprocessing, including organic solvents which were used to do solvent separations of U, Pu and fission products. The concentration of these products is very low vis a vis ceramic fuel pellets so the volumes are comparatively huge, and the solubility/mobility is immensely greater.
The usual drop on a red LED is about 1.7 volts, so a string of 24 would have a working voltage of about 41 volts (yellow and green have higher forward voltages IIRC). You are going to need a power supply to run this, and it is going to be much easier to generate 41 volts @ 200 mA for a single series string than 6.8 volts @ 1.2 A to run 6 parallel strings of 4. For the hypothetical traffic light the "supply" could be as simple as a diode bridge and a current-limiting resistor; that resistor would run mighty warm but it would generate less heat than the bulb it replaces.
One goes out - they all go out. Set them up in parallel and you get to see exactly which one died.
Repair is so expensive compared to replacement that it doesn't matter. The repaired unit would not be sealed as well as the original, plus it would have been stressed mechanically and thermally as part of the repair process. Why would you pay more for a unit that is less reliable than a new one? You wouldn't.
Feed chopped AC into a small transformer which changes it from the filter output voltage to the voltage required by the diode string.
Run this at ~20 KHz so that flicker is invisible.
If you run the switcher to get a specified level of current through the LED string, you can both vary the brightness to spec and run at any voltage within the capability of the switcher. I don't see a big market for internationalized light bulbs, but it would be possible.
You haven't commented on my figures- 50m high wave, 100m wavelength, 45kph speed- what kind of wave can you ride at this speed? Note that if the slope was 45 degrees, you would actually have to travel down the face at 45*sqrt(2) = 65kph in order to move forwards at 45kph. The steeper the wave the faster this would need be.
I couldn't ride any of those, because I can barely get up on a windsurfer. But that doesn't change the facts.
A bicyclist travelling down a much shallower slope can hit speeds upward of 100 kph. A human being in much bulkier clothing will hit a terminal velocity of ~200 kph falling straight down; given that air drag scales as speed squared you would expect a terminal velocity of about 85% of that for a person sliding down a frictionless 45 degree slope. 170 kph is more than twice your figure of 65 kph.
You can say that the slope isn't frictionless, but it's up to you to show that hydrofoils and the like cannot reduce drag sufficiently to allow such a wave to be surfed. Given that it's easy to fly down such a slope in air and the density of water allows the same lift to be generated with much less induced drag, I don't think you'll be able to make your case.
There is no point making a bright LED if the total system cost is still ten to twenty times that of an incandescent source.
As a counterexample, consider the compact-fluorescent bulb. Most cost around ten times as much as an incandescent of equivalent brightness, but the savings in replacement costs and power will pay back the difference in as little as a few months.
LED technology has the advantage of longer life than fluorescent. With the increase in efficiency from reflectors, they could cut power costs below fluorescent and become the TCO winners.
The difference is that the rubber tire is expected to slip in some circumstances, and it has a tread. This would allow it to clear off the leaf matter as a byproduct of wheelspin and eventually fix the problem during normal operation.
Slippage of steel wheels is a problem because each re-contact means extra wear for the rails. This is avoided with rubber drive tires, which are normal wear items and will probably wear less while slipping on steel than they do while cornering on pavement.
I wonder if wheels with hard-rubber tires could achieve some of the same traction advantages for regular locomotives and allow a smaller, lighter loco to move freight around or increase their grade capability?
It wouldn't look much like a conventional train, and given that you could add, delete or change half the "cars" in the time it takes to run them through what amounts to a weigh station it would completely change the economics of train assembly. Short-haul operations which would be prohibitively expensive to do using conventional trains would be the killer app.
The final benefit is that you could possibly get rid of diesel fuel by adding overhead power lines and running the trucks on electricity; the availability of rails as ground conductors and the positive alignment provided by the flanged wheels makes feasible a change that would be far more expensive for vehicles on roads.
Not every road/rail crossing is a bridge
on
By Road and Rail?
·
· Score: 1
I don't know how railroads are built over there, but where I come from you don't have roads going immediatly on the side of tracks.
In the USA we have these things called "grade crossings", where the rails cross the roadway at the same level. If the roadway is wide enough it would be feasible for an intermodal truck to enter or leave the railway at one of these crossings; just the thing you want for emergencies.
Tell them, they'll love it.
on
By Road and Rail?
·
· Score: 2, Interesting
I think you've missed the market niche for this idea.
The last thing the railroads want is a bunch of small vehicles cluttering up the system.
So don't clutter their long-haul system (except maybe with a bunch of these things following another train like ducklings after their mama). If you had RTFA you'd know that the idea is to help revive the short lines, where there isn't enough traffic for big trains in the first place. This could lead to more traffic for the big lines, because warehouses would be able to locate at junctions between the main lines and the short lines and handle both their incoming and outgoing freight by rail. Right now such a warehouse requires excellent road access like a freeway interchange, and real estate which has good rail access but poor road access just isn't desirable. If the rail companies own some of that real estate, they could really clean up on the deal.
There are all kinds of ways it can work
on
By Road and Rail?
·
· Score: 1
This will never work for several reasons. One who will drive the vehicle on the last leg? It would be too expensive to have a driver waiting to meet the train to drive that last leg and way too expensive to have alot of drivers riding along the way to make the last leg.
How does this make it more expensive than a truck, which not only requires a driver at all times but also gets stuck in traffic?
One huge advantage I can see for the B.R. concept is that vehicles could be lined up into "convoys" (like trains, only with no physical links) and only the lead vehicle would need active supervision. A sufficiently trustworthy cruise control would let most drivers sleep while their vehicles were under way on rails. This would allow the trucks to earn money overnight, and the drivers to earn partial pay while in bed.
And don't underestimate the benefits of reduced traffic. Removing trucks from the roads until just before their ultimate destinations would reduce both congestion and wear, saving billions in maintenance while making more money for carriers using both modes.
Finding the people with potato-snack antennae may be difficult, but enough prosecutions would make it less attractive to most people (deliberate outlaws/nonconformists excepted). The availability of certified antennas would remove the necessity.
Lots of people fail to survive past their 80's even without asbestos exposure (or smoking). I agree that pointlessly adding risks to live is stupid, but we should be thinking of these things like prostate cancer: if intervention will create more harm than waiting for the moment, we should not intervene.
The analogy is not perfect, because we do have substitutes for asbestos for most purposes. Yet we should look at the harm prevented by asbestos as well as the harm it causes, and not create worse harm from non-asbestos risks just to avoid the boogieman of the day.
In this case the speed is not related to the wave height at all, only water depth.
No, the water depth has little to do it (except by setting limits on the maximum wavelength; when a long-wavelength wave hits shallow water it slows down, piles up and breaks). In deep-water waves the speed is proportional to the square root of the wavelength (for the same reason that both pendulum periods and displacement-hull "hull speeds" are proportional to the square root of the length). You will find the equation for wave speed here.
A short-wavelength wave will move slowly in any depth of water; the speed of rogue waves is determined by the same factors as those of other wind-driven waves. The distinguishing feature of "rogue waves" is that they are tall and steep, and the same factors which allow them to do damage make them theoretically amenable to surfing.
First, if those waves were moving that fast, they would not be so tall (tsunamis are only inches high as they cross the oceans). Second, the waves would not be dangerous to ships if they were not steep. Third, you could keep up with almost any wave if you used something like a hydrofoil board.
The real problems are that you have to take a boat or aircraft from wave to wave (IF you can forecast them well enough), there is no beach to camp on between waves and no vantage point for spectators. The high costs and difficulty of milking spectators for money makes it unlikely that a sport would develop.
There is speculation that there are rocks on Mars which originated on Earth, but I've heard nothing about suspected Venus meteorites. Earth and Venus have roughly the same escape velocity, but that's not the problem so much as the atmosphere; it would take a much larger rock hitting Venus to deliver the same energy to the surface, and ejecta would have their energy drained by the CO2 soup and be far less likely to escape.
If you take in the accounts of people who have gone to Antarctica to hunt meteorites (which they do every southern summer), you'll get an idea of how relatively easy it is to find them there.
It's so easy, researchers have actually done it by robot.
A long time ago (in a galaxy fa...) MSFT said: "Hey we have this great idea to make software to sell to computer users, and we need money to do it. Rather than take out a bank loan, how about you guys (Mr and Mrs Mutual Fund Owner) shoulder some of the risk?
The partnership model (essentially, a corporation without the legal features of limited liability and tradable shares) has a far longer history than banks.
Yes, a company could theoretically own itself. Much like a million and one Mom-and-Pop corner stores own themselves.
No they don't. Every one of those stores is owned by people. A corporation can own shares in other corporations, but there are limits to the depth you can nest "holding companies"; ultimately the ownership devolves to individuals, trusts (under the control of individuals), and the like.
If MSFT buys back shares, then some people who once had shares have cash instead and the remaining people own a bigger fraction of the company. It's like some of the owners of a partnership allowing another partner to cash out, paying her off from the assets of the business.
The value of the company is the same after this announcement as it was before, but ex-dividend it goes down by three bucks a share. The only reason to bid up the price is if you expect the stream of dividends to continue, which it may well fail to do.
Lots of companies which faced competition from disruptive technologies have failed to acknowledge that their markets were under pressure. Microsoft is even trying to respond, within the constraints (handicaps) imposed by their business model.
Slashdot Mirror
This is not as difficult as it sounds. Fluorescent lights have two conversion stages (electricity to UV in the mercury vapor, UV to visible light in the phosphors) and each conversion has losses. LEDs have only one, which gives the LED an inherent advantage.
The Hanford wastes are composed of the byproducts of reprocessing, including organic solvents which were used to do solvent separations of U, Pu and fission products. The concentration of these products is very low vis a vis ceramic fuel pellets so the volumes are comparatively huge, and the solubility/mobility is immensely greater.
- Rectify, filter and chop the incoming AC.
- Feed chopped AC into a small transformer which changes it from the filter output voltage to the voltage required by the diode string.
- Run this at ~20 KHz so that flicker is invisible.
If you run the switcher to get a specified level of current through the LED string, you can both vary the brightness to spec and run at any voltage within the capability of the switcher. I don't see a big market for internationalized light bulbs, but it would be possible.A bicyclist travelling down a much shallower slope can hit speeds upward of 100 kph. A human being in much bulkier clothing will hit a terminal velocity of ~200 kph falling straight down; given that air drag scales as speed squared you would expect a terminal velocity of about 85% of that for a person sliding down a frictionless 45 degree slope. 170 kph is more than twice your figure of 65 kph.
You can say that the slope isn't frictionless, but it's up to you to show that hydrofoils and the like cannot reduce drag sufficiently to allow such a wave to be surfed. Given that it's easy to fly down such a slope in air and the density of water allows the same lift to be generated with much less induced drag, I don't think you'll be able to make your case.
LED technology has the advantage of longer life than fluorescent. With the increase in efficiency from reflectors, they could cut power costs below fluorescent and become the TCO winners.
Slippage of steel wheels is a problem because each re-contact means extra wear for the rails. This is avoided with rubber drive tires, which are normal wear items and will probably wear less while slipping on steel than they do while cornering on pavement.
I wonder if wheels with hard-rubber tires could achieve some of the same traction advantages for regular locomotives and allow a smaller, lighter loco to move freight around or increase their grade capability?
The final benefit is that you could possibly get rid of diesel fuel by adding overhead power lines and running the trucks on electricity; the availability of rails as ground conductors and the positive alignment provided by the flanged wheels makes feasible a change that would be far more expensive for vehicles on roads.
One huge advantage I can see for the B.R. concept is that vehicles could be lined up into "convoys" (like trains, only with no physical links) and only the lead vehicle would need active supervision. A sufficiently trustworthy cruise control would let most drivers sleep while their vehicles were under way on rails. This would allow the trucks to earn money overnight, and the drivers to earn partial pay while in bed.
And don't underestimate the benefits of reduced traffic. Removing trucks from the roads until just before their ultimate destinations would reduce both congestion and wear, saving billions in maintenance while making more money for carriers using both modes.
n/t
Finding the people with potato-snack antennae may be difficult, but enough prosecutions would make it less attractive to most people (deliberate outlaws/nonconformists excepted). The availability of certified antennas would remove the necessity.
The analogy is not perfect, because we do have substitutes for asbestos for most purposes. Yet we should look at the harm prevented by asbestos as well as the harm it causes, and not create worse harm from non-asbestos risks just to avoid the boogieman of the day.
A short-wavelength wave will move slowly in any depth of water; the speed of rogue waves is determined by the same factors as those of other wind-driven waves. The distinguishing feature of "rogue waves" is that they are tall and steep, and the same factors which allow them to do damage make them theoretically amenable to surfing.
The real problems are that you have to take a boat or aircraft from wave to wave (IF you can forecast them well enough), there is no beach to camp on between waves and no vantage point for spectators. The high costs and difficulty of milking spectators for money makes it unlikely that a sport would develop.
I scanned Google for all of those URLs and came up with nothing. So much for the poor man's high-bandwidth cache.
I prefer to look at more majestic things on my monitor, like a visible demonstration of gravity bending space-time.
There is speculation that there are rocks on Mars which originated on Earth, but I've heard nothing about suspected Venus meteorites. Earth and Venus have roughly the same escape velocity, but that's not the problem so much as the atmosphere; it would take a much larger rock hitting Venus to deliver the same energy to the surface, and ejecta would have their energy drained by the CO2 soup and be far less likely to escape.
It's so easy, researchers have actually done it by robot.
You could accomplish secure data destruction and give yourself a protein supplement... at the same time!
If MSFT buys back shares, then some people who once had shares have cash instead and the remaining people own a bigger fraction of the company. It's like some of the owners of a partnership allowing another partner to cash out, paying her off from the assets of the business.
The value of the company is the same after this announcement as it was before, but ex-dividend it goes down by three bucks a share. The only reason to bid up the price is if you expect the stream of dividends to continue, which it may well fail to do.
Lots of companies which faced competition from disruptive technologies have failed to acknowledge that their markets were under pressure. Microsoft is even trying to respond, within the constraints (handicaps) imposed by their business model.