There are nine engines in a cluster. Burn time for the cluster is 178 seconds. All engines run at full throttle. At t+160s, they shut down a pair of engines to reduce the g loading slightly, but otherwise it's constant thrust. Remember, though, that liftoff acceleration is very mild -- about 1.2g, iirc. For a given engine thrust, you usually improve payload mass by adding tankage until it can just barely leave the pad.
You seem to be misunderstanding the halting problem. All it says is that you cannot write a program that is *guaranteed* to always return a correct answer for every input program in bounded time. It is trivial to write a program that returns a correct answer for some programs and fails to return an answer for others (either by returning "maybe" or by never halting).
It is also trivial to prove that humans can't return a correct answer for every program. We have limited space in our brains, and limited time in which to read the program (let alone think about it), so there is an upper bound to the size program we can examine. In practice, it's even worse than that -- there are turing machines started on an empty tape for which we don't know the answer with only 2 symbols and 5 states (see here for refs).
Not really the same thing. Einstein derived it for non-quantum objects (ie large ones, or ones for which we can otherwise ignore quantum effects). This team verified it for quantum objects. This is interesting because the two theories don't mesh well -- one works at small scales and the other at large scales. It's not a theory of everything, because it doesn't touch gravity, but it's important to know where precisely the region the two are in conflict is. This calculation helps map that border.
To be fair, the government does attempt to prevent that usage. How successful they are, and whether it's a remotely good thing, is an entirely different question. However, you'd be hard pressed to say that the government ignores reports of drug trafficking. It's not a very good analogy.
What? Yes, it is. Technically. But remember, this is/., so we're all being pedants. Bismuth is so minutely radioactive that it was predicted before it was measured. For any practical purpose, it's not radioactive, but if you want to get precise about it, it is. (Also, there's far more to worry about from the potassium in your body than any quantity of bismuth you could conceivably eat.)
It depends on the type of radiation you're shielding against. For lower energy but penetrating stuff -- x-rays and gamma rays -- it really only matters how much mass you have. Lead is nice because it makes the shielding thinner, but it doesn't change the weight. In space, you care about mass far more than volume (normally).
For other sorts of radiation (high energy cosmic rays in particular), lead can actually be very bad shielding. Cosmic rays mostly pass through, but if they hit a nucleus then you get a huge shower of mid-energy secondaries -- which cause far more damage than the original particle would have. So, a small or moderate amount of lead shielding makes the total dose go *up*. For those sorts of particles, you need lightweight nuclei: hydrogen is good, carbon and oxygen aren't bad; water and plastics work well. You also need some distance, to give the secondaries time to interact. So, the low density means you need less mass, and the lighter nuclei are more effective, making the lightweight stuff far better.
But, this is all fairly irrelevant, as they're talking about replacing lead-based crystals in piezo actuators and sensors, not lead that's being used for its bulk properties or even being used as solder.
Heh, I have a breadboard with an... unusual, shall we say... scar on it. I had a prototype load cell amplifier built on it, connected to a PIC logging the data. The application? Thrust measurement on a small solid-propellant rocket test stand. Well, the forward closure on the casing wasn't as sturdy as it needed to be. It let go, the rest of the casing launched skyward (testing aft end up), and the propellant grains came flying out the back. One of them landed on the breadboard. It didn't take too long to get there with the fire extinguisher, but it was long enough to get the breadboard rather toasty. Impressively, the breadboard and both ICs are still functional (though the IA shows signs of corrosion). It still gets pressed into service occasionally when I'm short one...
Vigilante justice is always morally wrong. Of course punishing the bad guys is a public service; that's not the issue. The issue is that vigilante justice has very low standards of proof and no opportunity for the accused to defend themselves.
In which case you're not using spring terminals either...
And yeah, I don't much like trying to prototype with SMT either. Fortunately, prototype PCBs aren't too expensive. I've recently been looking into Stencils Unlimited for their prototype SMT products. I especially like the idea of their toaster oven reflow controller. I haven't tried it yet, but I intend to soon.
Yeah... good discipline is important. The subtle failures are even more annoying. For example, the base-emitter junction of a normal NPN transistor (2N3904, 2N2222, etc) makes a fine zener diode for voltage regulation circuits. But, as soon as you do that, you've permanently degraded the hfe of the transistor. Debugging that is a right pain.
I can't get circuits right the first time, even when I'm being paid to build them. That's what breadboards are for. You build it on the breadboard, go "huh, that's not right," fix it, and then transfer it to soldered perf board. You don't build with solder the first time. If you need it right the first time (because you're fabbing a PCB, for example) then there's hours worth of design review and double checking involved.
If you're worried about letting the magic smoke out... well, you can do that just as easily on a breadboard or spring terminals. Besides, being overly paranoid about the magic smoke is bad for learning. Go buy 100 transistors from digikey ($6 for 2N3904 / 2N3906), a dozen op amps, a couple hundred assorted resistors, etc. Obviously you don't want to teach carelessness, but paranoia about $0.05 components isn't warranted either.
Seriously. The most interesting thing isn't the gadgets, it's the parts with which to make gadgets. You canget a couple hundred resistors and transistors, some op amps, a few buttons, LEDs, a microcontroller or five, and a breadboard and not go much over the $50 budget.
A very long time. How on earth is this "interesting?" Is crazed paranoia on/. really the most interesting thing you've seen all day? I think some of the mods need to get out more.
Today is actually a good time to be an electronics hobbyist. Digikey will get you anything and everything you could want for far less than Radio Shack ever charged. Between eBay and the low-end USB ones, you can actually get a scope for a sane price. There is an amazing wealth of schematics to work from available online if you're trying to figure out how to build something. Wikipedia will explain all the basic building blocks and how they're used in lots of detail.
Sterling engines in theory approach the Carnot limit. In practice, they do very very well compared to other engines, especially on a weight basis. However, they also have problems that normally make them inappropriate for cars. They don't do well with variable outputs, and they don't start up rapidly. Over the normal operating range of a car engine, diesels do much better. If, however, you could run it at a fixed speed and not care about startup time, then the Sterling engine starts to look good. And, of course, a series hybrid with large batteries (or an electric car with a battery charger, depending how you look at it) is exactly that.
Of course, there are other problems with Sterling engines -- unknown long-term reliability, for example -- that are likely far more relevant. But efficiency is decidedly not the reason to avoid them.
They provide pens; you're not supposed to erase things. If you make a mistake, you go get a new ballot and they destroy the incorrectly marked one. You feed the ballot into the scanner (no one else touches it between marking and scanning), so you know that it didn't jam or cause an error. There's a poll worker watching you do it, of course. This doesn't help with marks not registering or registering for the wrong candidate, of course, but errors due to damaged ballots or (I assume) double marking are noticed immediately and can be fixed.
Electronic machine and paper record makes perfect sense to me. As long as there's a voter-verified paper trail that is the official record, I'm not too picky.
That sounds like how I voted. In North Carolina, we use paper ballots, a pen, and an optical scanner (for speed; the paper trail is what's used for a recount). Remember that in the US, most of the details of how the election is run are decided at the state level (and sometimes at the local level). Why some states feel a need to change, I don't know, but NC at least seems to get this right. Many other states do it similarly.
But if you are going to legalize prostitution, how are you going to keep 'survival sex' illegal? Because I don't believe society should put people into a position where they only consent to sex to survive.
What makes you think making it illegal helps? The way to stop people having sex for money to survive is to make it so they don't need to. If they need to, they will, and making it illegal just makes it riskier for them. As you say, society shouldn't put them in that position; it certainly shouldn't put them in a position where they need to have illegal sex to survive.
People having sex to survive, and that sex being illegal, are two different problems. Solving either one while ignoring the other is better than doing nothing, though obviously solving both is better.
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There are nine engines in a cluster. Burn time for the cluster is 178 seconds. All engines run at full throttle. At t+160s, they shut down a pair of engines to reduce the g loading slightly, but otherwise it's constant thrust. Remember, though, that liftoff acceleration is very mild -- about 1.2g, iirc. For a given engine thrust, you usually improve payload mass by adding tankage until it can just barely leave the pad.
You seem to be misunderstanding the halting problem. All it says is that you cannot write a program that is *guaranteed* to always return a correct answer for every input program in bounded time. It is trivial to write a program that returns a correct answer for some programs and fails to return an answer for others (either by returning "maybe" or by never halting).
It is also trivial to prove that humans can't return a correct answer for every program. We have limited space in our brains, and limited time in which to read the program (let alone think about it), so there is an upper bound to the size program we can examine. In practice, it's even worse than that -- there are turing machines started on an empty tape for which we don't know the answer with only 2 symbols and 5 states (see here for refs).
Not really the same thing. Einstein derived it for non-quantum objects (ie large ones, or ones for which we can otherwise ignore quantum effects). This team verified it for quantum objects. This is interesting because the two theories don't mesh well -- one works at small scales and the other at large scales. It's not a theory of everything, because it doesn't touch gravity, but it's important to know where precisely the region the two are in conflict is. This calculation helps map that border.
To be fair, the government does attempt to prevent that usage. How successful they are, and whether it's a remotely good thing, is an entirely different question. However, you'd be hard pressed to say that the government ignores reports of drug trafficking. It's not a very good analogy.
What? Yes, it is. Technically. But remember, this is /., so we're all being pedants. Bismuth is so minutely radioactive that it was predicted before it was measured. For any practical purpose, it's not radioactive, but if you want to get precise about it, it is. (Also, there's far more to worry about from the potassium in your body than any quantity of bismuth you could conceivably eat.)
It depends on the type of radiation you're shielding against. For lower energy but penetrating stuff -- x-rays and gamma rays -- it really only matters how much mass you have. Lead is nice because it makes the shielding thinner, but it doesn't change the weight. In space, you care about mass far more than volume (normally).
For other sorts of radiation (high energy cosmic rays in particular), lead can actually be very bad shielding. Cosmic rays mostly pass through, but if they hit a nucleus then you get a huge shower of mid-energy secondaries -- which cause far more damage than the original particle would have. So, a small or moderate amount of lead shielding makes the total dose go *up*. For those sorts of particles, you need lightweight nuclei: hydrogen is good, carbon and oxygen aren't bad; water and plastics work well. You also need some distance, to give the secondaries time to interact. So, the low density means you need less mass, and the lighter nuclei are more effective, making the lightweight stuff far better.
But, this is all fairly irrelevant, as they're talking about replacing lead-based crystals in piezo actuators and sensors, not lead that's being used for its bulk properties or even being used as solder.
So, if I shoot in raw mode, and then postprocess in software to get a jpeg, the demosaicing signature should merely identify the software, right?
Of course, I wouldn't be surprised to learn that the distortion uniquely identifies the lens used...
Stupid, but otherwise intelligent, is still stupid.
But that's the first place they'd hide the cameras!
Reality is that which, when you stop believing in it, does not go away.
Heh, I have a breadboard with an... unusual, shall we say... scar on it. I had a prototype load cell amplifier built on it, connected to a PIC logging the data. The application? Thrust measurement on a small solid-propellant rocket test stand. Well, the forward closure on the casing wasn't as sturdy as it needed to be. It let go, the rest of the casing launched skyward (testing aft end up), and the propellant grains came flying out the back. One of them landed on the breadboard. It didn't take too long to get there with the fire extinguisher, but it was long enough to get the breadboard rather toasty. Impressively, the breadboard and both ICs are still functional (though the IA shows signs of corrosion). It still gets pressed into service occasionally when I'm short one...
Well, yeah. But I was replying to the parent post, not the article.
Vigilante justice is always morally wrong. Of course punishing the bad guys is a public service; that's not the issue. The issue is that vigilante justice has very low standards of proof and no opportunity for the accused to defend themselves.
In which case you're not using spring terminals either...
And yeah, I don't much like trying to prototype with SMT either. Fortunately, prototype PCBs aren't too expensive. I've recently been looking into Stencils Unlimited for their prototype SMT products. I especially like the idea of their toaster oven reflow controller. I haven't tried it yet, but I intend to soon.
Yeah... good discipline is important. The subtle failures are even more annoying. For example, the base-emitter junction of a normal NPN transistor (2N3904, 2N2222, etc) makes a fine zener diode for voltage regulation circuits. But, as soon as you do that, you've permanently degraded the hfe of the transistor. Debugging that is a right pain.
I can't get circuits right the first time, even when I'm being paid to build them. That's what breadboards are for. You build it on the breadboard, go "huh, that's not right," fix it, and then transfer it to soldered perf board. You don't build with solder the first time. If you need it right the first time (because you're fabbing a PCB, for example) then there's hours worth of design review and double checking involved.
If you're worried about letting the magic smoke out... well, you can do that just as easily on a breadboard or spring terminals. Besides, being overly paranoid about the magic smoke is bad for learning. Go buy 100 transistors from digikey ($6 for 2N3904 / 2N3906), a dozen op amps, a couple hundred assorted resistors, etc. Obviously you don't want to teach carelessness, but paranoia about $0.05 components isn't warranted either.
Eh, we already know the zombies are most likely to come from Hierakonpolis.
Seriously. The most interesting thing isn't the gadgets, it's the parts with which to make gadgets. You canget a couple hundred resistors and transistors, some op amps, a few buttons, LEDs, a microcontroller or five, and a breadboard and not go much over the $50 budget.
A very long time. How on earth is this "interesting?" Is crazed paranoia on /. really the most interesting thing you've seen all day? I think some of the mods need to get out more.
He won't be interested in us; we're made of meat, after all.
Today is actually a good time to be an electronics hobbyist. Digikey will get you anything and everything you could want for far less than Radio Shack ever charged. Between eBay and the low-end USB ones, you can actually get a scope for a sane price. There is an amazing wealth of schematics to work from available online if you're trying to figure out how to build something. Wikipedia will explain all the basic building blocks and how they're used in lots of detail.
Sterling engines in theory approach the Carnot limit. In practice, they do very very well compared to other engines, especially on a weight basis. However, they also have problems that normally make them inappropriate for cars. They don't do well with variable outputs, and they don't start up rapidly. Over the normal operating range of a car engine, diesels do much better. If, however, you could run it at a fixed speed and not care about startup time, then the Sterling engine starts to look good. And, of course, a series hybrid with large batteries (or an electric car with a battery charger, depending how you look at it) is exactly that.
Of course, there are other problems with Sterling engines -- unknown long-term reliability, for example -- that are likely far more relevant. But efficiency is decidedly not the reason to avoid them.
They provide pens; you're not supposed to erase things. If you make a mistake, you go get a new ballot and they destroy the incorrectly marked one. You feed the ballot into the scanner (no one else touches it between marking and scanning), so you know that it didn't jam or cause an error. There's a poll worker watching you do it, of course. This doesn't help with marks not registering or registering for the wrong candidate, of course, but errors due to damaged ballots or (I assume) double marking are noticed immediately and can be fixed.
Electronic machine and paper record makes perfect sense to me. As long as there's a voter-verified paper trail that is the official record, I'm not too picky.
That sounds like how I voted. In North Carolina, we use paper ballots, a pen, and an optical scanner (for speed; the paper trail is what's used for a recount). Remember that in the US, most of the details of how the election is run are decided at the state level (and sometimes at the local level). Why some states feel a need to change, I don't know, but NC at least seems to get this right. Many other states do it similarly.
Here is the (sample) ballot I voted on (pdf).
But if you are going to legalize prostitution, how are you going to keep 'survival sex' illegal? Because I don't believe society should put people into a position where they only consent to sex to survive.
What makes you think making it illegal helps? The way to stop people having sex for money to survive is to make it so they don't need to. If they need to, they will, and making it illegal just makes it riskier for them. As you say, society shouldn't put them in that position; it certainly shouldn't put them in a position where they need to have illegal sex to survive.
People having sex to survive, and that sex being illegal, are two different problems. Solving either one while ignoring the other is better than doing nothing, though obviously solving both is better.