Whether or not it's worthwhile depends on how much energy you need to make the desired fuel, and if you can use that energy more effectively or not... that's the key difference between "possible" and "practical." =Smidge=
We already produce 2700 calories per person per day. That's plenty to feed everyone a healthy diet. The reason so many people don't have enough food has nothing to do with the amount of food available and everything to do with logistics, politics, and inequity: The food simply isn't getting to where it's needed. Growing even more food is not going to solve that problem.
Similarly, biofuel production need not make use of land that is suitable for growing common food crops. Even though I advocate biofuels, even I'm against using food crops to do so. =Smidge=
An modern auto plant turns out a vehicle approximately once every minute.
A car might roll off the line every 60 seconds, but each individual car takes ~20 hours to make. And that only works because they are all the same with only superficial differences.
So in short, this is about using 3D printing to prototype something before going to full production. Haven't we been doing that since the 1970s?
No, because 3D printers weren't developed until the 80s.:) =Smidge=
Sorry, nobody has the right to endanger other people through irresponsibility.
You're free to do what you wish with your body, but if your job is interacting with thousands of people every day - especially children - then you should get vaccinated so you do not become a vector of disease. It doesn't matter one bit if YOU get sick or not. This isn't about you. It's about protecting the people you come into contact with.
It's basically the same level of common sense as employees washing hands and wearing gloves when handling food. It's not about keeping the employee's hands clean. =Smidge=
At which point you know about it, and can therefore be upset about it. Being aware of something is a necessary precondition to having any emotional response to it.
This is why I've been pushing to argue in favor of reducing fossil fuel use not from an environmental point of view, but from an economic one. People can bury their heads in the sand when it comes to science, but people always listen when money is involved.
Even though the US imports about a third of our petroleum, that's still equivalent to hundreds of billions of dollars per year leaving our economy. If we transition to renewable energies, that money stays around a bit longer.
Renewable energies might have a larger up-front capital cost (but not by much, and it's getting better every day), but the long term costs are overwhelmingly favorable.
With the current crash in oil prices it should be clear that our economy is in the hands of foreign interests. We are hostages to international petroleum markets. Let's develop domestic sources to free ourselves from foreign influence. Remember: There's no reason why oil couldn't have been this cheap all along, and the price only went down right when we were posed to start reducing imports in favor of domestic natural gas production. We're being played!
(Oh, and if we happen to mitigate the environmental damage we're doing in the process and avoid global catastrophe, I guess that'll be a bonus...) =Smidge=
Well, no. The Shuttle's SRBs were a lot more than just a tube full of explosives.
They had thrust vector control; hydraulic power units, gimbal nozzles, control hardware. Electrical subsystems. Self contained navigation hardware. Range safety hardware. And of course everything was triple or quadruple redundant for reliability. =Smidge=
I think you're misconstruing what is actually meant when physicists talk about the universe possibly being a hologram.
They don't mean the contemporary "Star Trek Holodeck" type of hologram. They mean that all of the information about the 3D volume of the universe can be contained and encoded within a 2D boundary.
This is not a mathematically rigorous concept of the universe, but if they can nail it down it might have some application in explaining how gravity works and the ultimate granularity of the universe (e.g. how small the smallest possible fundamental particles can be). But in no sense would this prove, or even really be evidence supporting, the notion that our universe is a simulation within some "larger reality." =Smidge=
I will bet your chances of being killed in a mall go way up if there are specific threats against that mall.
No, it doesn't. The mall could have been attacked at any time with no announcement at all. The only difference is now you know somebody out there has an axe to grind.
Knowing the odds does not change the odds.
In fact, I'd argue that you might actually have a slightly LOWER chance of being killed or injured if the the intent to attack is announced. They could be bluffing. Increased security could ward off or apprehend the attackers. Law enforcement might be able to intervene and prevent the attack.
The most realistic outcome of this scenario? The mall would be closed and your appointment canceled... but assuming for the sake of argument that doesn't happen, you might as well go because your odds are certainly no worse than at any other time. =Smidge=
2. See that guy in the cubicle next to yours? Prove that he is "self-aware".
The guy in the cubicle next to mine spends his lunch hour browsing Fox News, Drudge Report and Townhall. I can make a very solid case that he's not. =Smidge=
150Nm is about what a typical small car engine might be capable of at peak, but torque at the wheels would typically be greater due to gear reductions. Not really relevant, though - the torque of the engine applied to the wheels is not applied to the lug nuts on the wheels as a torque, but applied to the lugs themselves as a shear.
Maybe imperial units will help?
15 Newton-meters is roughly 11 foot-pounds. Most people can comfortably apply that kind of torque with a normal wrench, and that's about twice what a strong person could do with a screwdriver.
Torque specifications for lug nuts are typically in the 80 to 120 foot-pound range, though practically nobody outside of a reputable auto shop will bother with that (and even most reputable shops will gloss over it...). Most people, including myself, either use an impact gun or step on the lug wrench, which results in slight over-tightening. Figure a 150-lb person standing on a 12" long wrench and that's 150 ft-lbs... slightly over but not too bad.
For gasoline car engines, torque (ft-lbs) seems to always be fairly close to horsepower... so 120 ft-lbs is about right for a 120hp engine, plus or minus. It boils down to the fact that most gasoline engines are designed to run at a certain RPM, which makes the math turn out that these two metrics are often within maybe 10% of each other. =Smidge=
As the AC said, for a very limited torque; 15 Newton-Meters. For a sense of scale, the recommended torque on a lug nut for a car tire is typically around 8-10 times that.
It's also under cryogenic conditions, intended for space applications, which is a rather special case (ultra-reliable under extreme environments) where it makes makes more sense to use something exotic.
And having said that, the more I learn about it the less I'm impressed with it. Magnetic bearings are pretty old hat technologically speaking, and the harmonic drive aspect is only novel in that it uses magnetic repulsion to flex the spline cup rather than physical contact. Meh. Even their "through-wall transmission" thing is a glorified magnetic stirrer. =Smidge=
Your argument basically boils down to "since electric motors can produce high torque, then permanent magnet couplings can also provide high torque"
My contention is you make it sound way, way simpler than it is. Also, you'll find that the really big motors are not the permanent magnet type exactly because producing a high-torque motor with permanent magnets is more difficult and expensive. It's an issue of flux density.
I'm sure you COULD design a permanent magnet coupling for any particular purpose, but that doesn't mean it makes sense to do so. =Smidge=
If you couldn't move high forces with a transmission like this, then you also couldn't generate them with an electric motor, because you couldn't hope for the magnetic fields to turn the stator against high loads.
Electric motors can stall, and when they do so they draw a terrifyingly huge amount of power compared to when they're operating properly. Providing that static torque is very expensive and often dangerous unless the motor and controls were designed for it.
It's not that magnetic fields can't be strong enough, it's getting fields that are strong enough without additional energy input. =Smidge=
Slashdot Mirror
It's not at all clear what you're trying to prove or argue....
The process produces isopropyl alcohol, not gasoline.
The published article abstract clearly states that the overall efficiency for the process is "up to" 3.2% efficient.
No claim was made as to the rate of production.
Basically, while your math is correct it's completely irrelevant and inapplicable here. Thanks for sharing, I guess?
=Smidge=
You're just jealous because I have a username. :)
=Smidge=
Unless your ship has a nuclear reactor on board
Fun fact: The US Navy operates 86 nuclear powered ships (mostly submarines). They seem pretty comfortable with it.
=Smidge=
Sure. But you ask "Can you (practically) make LPG from bio sources?"
And the answer is "It depends." How desperate are you for LPG? :)
=Smidge=
Sure.
You can even make straight-up gasoline.
Whether or not it's worthwhile depends on how much energy you need to make the desired fuel, and if you can use that energy more effectively or not... that's the key difference between "possible" and "practical."
=Smidge=
Food production is not a valid argument, IMHO.
We already produce 2700 calories per person per day. That's plenty to feed everyone a healthy diet. The reason so many people don't have enough food has nothing to do with the amount of food available and everything to do with logistics, politics, and inequity: The food simply isn't getting to where it's needed. Growing even more food is not going to solve that problem.
Similarly, biofuel production need not make use of land that is suitable for growing common food crops. Even though I advocate biofuels, even I'm against using food crops to do so.
=Smidge=
An modern auto plant turns out a vehicle approximately once every minute.
A car might roll off the line every 60 seconds, but each individual car takes ~20 hours to make. And that only works because they are all the same with only superficial differences.
So in short, this is about using 3D printing to prototype something before going to full production. Haven't we been doing that since the 1970s?
No, because 3D printers weren't developed until the 80s. :)
=Smidge=
well, what is "reasonable"?? the flu generally wont kill you, as such IMO should not be mandated.
So is DEATH the only level of harm you can think of that should be avoided? Is that really the threshold below which you don't care anymore?
Going back to the food service employee analogy: It probably won't kill anyone if an employee doesn't wash their hands or use gloves...
=Smidge=
Not all vaccinations last your whole life.
=Smidge=
Any disease that they could reasonably be expected to come into contact with and communicate to others.
So yes, that includes flu shots. That also includes MMR, Diphtheria, shingles (if you're over 60), pertussis, and pneumo/meningococcal vaccines.
Again, it's not about risk to YOU, but risk to others. Taking steps to protect others is what "personal responsibility" is all about.
=Smidge=
Sorry, nobody has the right to endanger other people through irresponsibility.
You're free to do what you wish with your body, but if your job is interacting with thousands of people every day - especially children - then you should get vaccinated so you do not become a vector of disease. It doesn't matter one bit if YOU get sick or not. This isn't about you. It's about protecting the people you come into contact with.
It's basically the same level of common sense as employees washing hands and wearing gloves when handling food. It's not about keeping the employee's hands clean.
=Smidge=
Until you get hate mail
At which point you know about it, and can therefore be upset about it. Being aware of something is a necessary precondition to having any emotional response to it.
Otherwise it's called paranoia.
=Smidge=
It's very, very difficult to get upset over things you don't know about.
Doesn't stop some people from trying, though...
=Smidge=
Wait, if he's not up for re-election... could that mean he's genuinely interested in engaging younger audiences?
The implications boggle the mind!
=Smidge=
This is why I've been pushing to argue in favor of reducing fossil fuel use not from an environmental point of view, but from an economic one. People can bury their heads in the sand when it comes to science, but people always listen when money is involved.
Even though the US imports about a third of our petroleum, that's still equivalent to hundreds of billions of dollars per year leaving our economy. If we transition to renewable energies, that money stays around a bit longer.
Renewable energies might have a larger up-front capital cost (but not by much, and it's getting better every day), but the long term costs are overwhelmingly favorable.
With the current crash in oil prices it should be clear that our economy is in the hands of foreign interests. We are hostages to international petroleum markets. Let's develop domestic sources to free ourselves from foreign influence. Remember: There's no reason why oil couldn't have been this cheap all along, and the price only went down right when we were posed to start reducing imports in favor of domestic natural gas production. We're being played!
(Oh, and if we happen to mitigate the environmental damage we're doing in the process and avoid global catastrophe, I guess that'll be a bonus...)
=Smidge=
Well, no. The Shuttle's SRBs were a lot more than just a tube full of explosives.
They had thrust vector control; hydraulic power units, gimbal nozzles, control hardware. Electrical subsystems. Self contained navigation hardware. Range safety hardware. And of course everything was triple or quadruple redundant for reliability.
=Smidge=
Except that the solid rocket boosters and fuel tanks were not reusable. Only the engines were re-used and that after expensive overhauls.
The Shuttle's SRBs were reusable, and they reused them (or at least parts of them) pretty much every launch.
The big orange liquid fuel tank was not reused, though.
=Smidge=
I think you're misconstruing what is actually meant when physicists talk about the universe possibly being a hologram.
They don't mean the contemporary "Star Trek Holodeck" type of hologram. They mean that all of the information about the 3D volume of the universe can be contained and encoded within a 2D boundary.
This is not a mathematically rigorous concept of the universe, but if they can nail it down it might have some application in explaining how gravity works and the ultimate granularity of the universe (e.g. how small the smallest possible fundamental particles can be). But in no sense would this prove, or even really be evidence supporting, the notion that our universe is a simulation within some "larger reality."
=Smidge=
I will bet your chances of being killed in a mall go way up if there are specific threats against that mall.
No, it doesn't. The mall could have been attacked at any time with no announcement at all. The only difference is now you know somebody out there has an axe to grind.
Knowing the odds does not change the odds.
In fact, I'd argue that you might actually have a slightly LOWER chance of being killed or injured if the the intent to attack is announced. They could be bluffing. Increased security could ward off or apprehend the attackers. Law enforcement might be able to intervene and prevent the attack.
The most realistic outcome of this scenario? The mall would be closed and your appointment canceled... but assuming for the sake of argument that doesn't happen, you might as well go because your odds are certainly no worse than at any other time.
=Smidge=
2. See that guy in the cubicle next to yours? Prove that he is "self-aware".
The guy in the cubicle next to mine spends his lunch hour browsing Fox News, Drudge Report and Townhall. I can make a very solid case that he's not.
=Smidge=
150Nm is about what a typical small car engine might be capable of at peak, but torque at the wheels would typically be greater due to gear reductions. Not really relevant, though - the torque of the engine applied to the wheels is not applied to the lug nuts on the wheels as a torque, but applied to the lugs themselves as a shear.
Maybe imperial units will help?
15 Newton-meters is roughly 11 foot-pounds. Most people can comfortably apply that kind of torque with a normal wrench, and that's about twice what a strong person could do with a screwdriver.
Torque specifications for lug nuts are typically in the 80 to 120 foot-pound range, though practically nobody outside of a reputable auto shop will bother with that (and even most reputable shops will gloss over it...). Most people, including myself, either use an impact gun or step on the lug wrench, which results in slight over-tightening. Figure a 150-lb person standing on a 12" long wrench and that's 150 ft-lbs... slightly over but not too bad.
For gasoline car engines, torque (ft-lbs) seems to always be fairly close to horsepower... so 120 ft-lbs is about right for a 120hp engine, plus or minus. It boils down to the fact that most gasoline engines are designed to run at a certain RPM, which makes the math turn out that these two metrics are often within maybe 10% of each other.
=Smidge=
As the AC said, for a very limited torque; 15 Newton-Meters. For a sense of scale, the recommended torque on a lug nut for a car tire is typically around 8-10 times that.
It's also under cryogenic conditions, intended for space applications, which is a rather special case (ultra-reliable under extreme environments) where it makes makes more sense to use something exotic.
And having said that, the more I learn about it the less I'm impressed with it. Magnetic bearings are pretty old hat technologically speaking, and the harmonic drive aspect is only novel in that it uses magnetic repulsion to flex the spline cup rather than physical contact. Meh. Even their "through-wall transmission" thing is a glorified magnetic stirrer.
=Smidge=
Your argument basically boils down to "since electric motors can produce high torque, then permanent magnet couplings can also provide high torque"
My contention is you make it sound way, way simpler than it is. Also, you'll find that the really big motors are not the permanent magnet type exactly because producing a high-torque motor with permanent magnets is more difficult and expensive. It's an issue of flux density.
I'm sure you COULD design a permanent magnet coupling for any particular purpose, but that doesn't mean it makes sense to do so.
=Smidge=
If you couldn't move high forces with a transmission like this, then you also couldn't generate them with an electric motor, because you couldn't hope for the magnetic fields to turn the stator against high loads.
Electric motors can stall, and when they do so they draw a terrifyingly huge amount of power compared to when they're operating properly. Providing that static torque is very expensive and often dangerous unless the motor and controls were designed for it.
It's not that magnetic fields can't be strong enough, it's getting fields that are strong enough without additional energy input.
=Smidge=
So basically "Project 2501" then?
=Smidge=