Apparently the laws of physics don't apply to your vehicle.
Why... he might just be powering a big honkin' AC and a big honkin' stereo with the engine. Of course his mileage will go up when he goes faster, since that means the engine spends more of its power actually moving the vehicle.
A mist of water sprayed into the cylinder makes the combustion engines run much cooler (higher efficiency, shhh)
And here I thought efficiency was related to the ratio of source temperature to sink temperature, and all this seems to do is reduce source temperature.
The water is instantly flash-heated by the fuel explosion into steam for an instant expansion of 1:800 => making all your combustion engines be a partial Steam Engine by piping some H2O mist in through a vacuum tube port.
It's flash-heated, meaning that it reduces source temperature. Bad for the efficiency. And how's the steam generated from this contraption different from the steam that burning hydrocarbons produces?
Interesting thing about putting real-time steam into a running engine is that the inside of the cylinder ~spark plug electrodes and everything~ is being STEAM CLEANED as the car runs.
How again is this steam different from the steam that results from burning hydrocarbons?
The problem with driving in the highest gear is the engine is lugging at 55-65 mph, which means the fuel isn't being fully burned, which means carbon buildup in the cylinders and on the piston head. This is nothing but premature aging of the engine.
How again does drawing heat out of the combustion reaction help with making it more complete?
isentropic compression/expansion and isobaric heating and cooling, vs. adiabatic compression/expansion and isovolumetric heating/cooling in the Otto cycle)
Whoops, that should be isentropic compression/expansion, isobaric heating and isovolumetric cooling for the Diesel cycle, and isentropic compression/expansion and isovolumetric heating&cooling for the Otto cycle. I know why I hate thermodynamics.
I don't know if it's some special feature in some exclusive modern fuel-injected petrol systems, but it's certainly not a standard one across the board.
Today, it pretty much is.
Petrol fuel-injected systems need to continue to inject fuel into the engine to keep the 4-stroke pattern working properly. It needs to continue that cycle of intake, compression, ignition, exhaust, and so on.
Why? Why can you not leave out injecting fuel and ignition, as long as the engine is cranked externally? All it does it turn the engine into an air pump.
Diesel's are different. Since diesel's simply combust due to compression, fuel can probably be halted or started any time. I confess I'm not too familiar to the inner workings of diesel.
Usual diesel engines are four-stroke engines with the same phases as a gasoline engine, except for compressing air instead of an air-fuel mixture and "igniting" by actually injecting fuel after the compression has taken place. This results in a thermodynamically different cycle (isentropic compression/expansion and isobaric heating and cooling, vs. adiabatic compression/expansion and isovolumetric heating/cooling in the Otto cycle), but technically it's still intake (of air), compression, combustion and exhaust.
Do a test. Jump into a manual petrol car - not a diesel one. Rev up nice and high. Now, let go of the throttle.
No need to do this test. Since the car is not moving, there's no external source cranking the engine, so the ECU will continue to inject fuel.
You need to do the test while you're going downhill (or at least on a level road, above a certain speed). Leave the clutch engaged, take your foot off the accelerator. The ECU will cut off the fuel to the engine as long as the engine rpm are kept above a minimum level by the car moving forward. If you disengage the clutch, the ECU will again start injecting fuel, as the external power source is gone.
They work completely different to petrol engines and yes, do stop fuel injection during zero throttle.
The feature is the same on modern, fuel-injected gasoline engines. It's just that you can't hear it all that well, since gasoline engines shouldn't knock.
You should have mentioned that before, and also be aware that diesel engines work on completely different theory to petrol engines. At the most fundamental level even - working on combustion under compression as opposed to combustion caused by spark plugs.
Err... if the engine is not fueled, none of this should matter. There's no compression, no need for ignition, all that happens is that the pistons are being moved back and forth and the engine is reduced to being an air pump.
Yes, but when teh car is being turned from the wheels (momentum, as you said), the engine is at idle throttle and low fuel air ratios. It doesn't stop fuel intake completely.
Yes, it does. Until you've got an old and/or crappy car.
If it wasn't, you wouldn't hear your engine running at all. Just the sound of the road, which of course, is not the case.
Yes, this is the case. It's a very, very audible difference. I'm driving a car with a diesel engine, and when I take my foot off the accelerator when going downhill the engine is silent (no diesel knock). If I touch the accelerator, I hear the typical diesel engine sound.
But of course you still hear the crankshaft (and everything that connects to it) being _turned_. The only sound that stops is that of the actual combustion, which isn't all that prominent in a gasoline-powered car, so you'll probably not notice the difference there.
Unless I'm missing something, engines will never turn off. If fuel stops going into the engine, it'll stall!
Yes, you're missing the fact that the crankshaft could be turned by an external source of torque (such as the momentum of the car, transferred up the powertrain instead of down). Of course, if there's no such source (i.e. the car is stopped, going too slow, or the clutch is not engaged), then the engine needs to consume some fuel to keep running.
You're wrong here, too: Even with no fuel flowing to the engine, you've got the extra drag of the engine on the drive train. Putting the tranny in neutral removes that extra drag from the system, enabling a better coast.
Err... but if you put the tranny in neutral, then the engine needs to consume some fuel just to keep running (and drive various things connected to the crankshaft, like water pump, oil pump, alternator, AC, etc).
Please, please, please use your brakes when coming to a stop and NOT your engine.
What if I don't want to come to a stop and just want to stop accelerating when going downhill?
Brakes are balanced to work at every tyre whereas engine braking has the potential to make only half your vehicles tyres rotate at a different speed to the road surface which could cause a spin.
Err... yikes. If that happens, your vehicle wasn't roadworthy to begin with, or the road conditions were so bad that applying the brakes wouldn't have been that much better.
Also, what you're basically saying here is that accelerating could cause a spin (since it also changes the vehicles speed by using the engine).
Look up any advanced driver training material if you need to know more.
The key is to drive a manual transmission and to hold in the clutch whenever you can(especially downhill) so that the car coasts(runs at idle) as much as possible.
To you (and whoever modded you informative): Welcome to the age of fuel-injected cars. Once you get rid of that old carbureted clunker of yours, you'll find that your ages-old wisdom has suddenly become obsolete and counter-productive, thanks to automated fuel-cutoff technologies.
Car designers seem to have caught on this decades ago. Have you seen any recent Audis or BMWs and compared them to earlier models? That's clearly a trend toward looking mean and aggressive already. This study just confirms what car designers have known for a long time.
Which, do you imagine, is cheaper to replace if you break it? Brakes, or engine?
As long as you don't over-revv the engine, using it to brake shouldn't have any significant effect on its lifetime. No one's saying that you should shift into first gear when you're going 65 mph.
And your brakes not working when you need them can be even more expensive.
So, by "engine braking", you mean "leaving the transmission in gear"?
Err... yes?
That's what basically everyone (except for truck drivers and -mechanics) means when they say "engine braking". Most people don't even know what an exhaust brake is, and the only people who would equate "engine brake" with "exhaust brake" would be the ones actually driving or servicing vehicles that are fitted with one (i.e. trucks and such).
So, yes, "engine braking" is equal to "take your foot off the accelerator (and maybe shift down early, without over-revving the engine)" for most drivers.
Injectors don't turn off, since the engine needs to keep running, even at idle.
Err... that's what the GP said. If you let the engine idle, it needs to consume fuel to keep running. If you use the internal friction of the engine to brake, then the engine consumes the cars kinetic energy to keep running, without consuming fuel.
"Engine Braking" needs the engine to be fitted with an Engine Brake ("Jake Brake"), and only diesel engines have this.
You're confusing "engine brake" and "exhaust brake". Engine braking uses the internal friction of the engine (and the power consumed by all the stuff driven by the engine - water pump, oil pump, alternator, AC and whatnot) to slow the car down, an exhaust brake additionally turns even more kinetic energy into heat by just compressing the exhaust gasses.
This sounds like something that, if it works, would apply to many forms of cancer. Is it just because breast cancer research is popular in funding circles or is there something specific to breast cancer to limit the applicability of the technique to breast cancer tumours?
Yes: Breast cancer occurs in tissue that is easily accessible from the outside and that is not vital for the patient.
This means you can stick a needle in it and try to thermally destroy the cancer. The same technique could not be applied, to say, brain tumors or bone/pancreas/colon/liver/kidney/lung/esophagal/stomach/bladder cancers, since they are either not easily accessible by probe or will react very badly if the tumor is destroyed too aggressively (i.e. with too much loss of healthy tissue), or will require additional surgery after the tumor has been removed since you can't simply wait for the "hole" to fix itself.
Drafting does not work that way. Contrary to popular belief, it does not increase the fuel use of the car in front of you.
There is no pulling effect, you just avoid spending fuel at pushing air out of the way because the car in front of you has already done it.
In fact, the opposite happens - it _decreases_ the fuel use of the car in front of you, even though by a smaller amount than what you save. This is due to wind resistance not only happening by overpressure in front of the car, but also by the lower pressure behind the car, and if there's someone drafting behind you, they're essentially taking some of lower pressure off your car.
Hey, I buy your arguments, but it is the ECG makers design decition ($$$) if they choose to not handle mobile phone noise.
There's no meaningful way to distinguish between a mobile phone packet and a pacemaker pulse in the few ms that you have available for this task, if you're not willing to accept more false negatives (and you are not).
And these things are already shielded against lots of interference (for example defibrillator pulses and HF surgery devices, both of which surpass mobile phone emissions by a few orders of magnitude), but those are transient and it's not expected that the device considers measuring while the interference it active.
I think that today it is unacceptable if critical equipment breaks if a mobile phone is closeby.
That's a bit like saying "It's unacceptable that an operating room becomes unsterile if you herd a bunch of preschoolers through it."
In an ECG, you're dealing with signals in the sub-millivolt range, coming from an amazingly good antenna (the human body). EEG would be even worse, there you're looking a microvolts.
If you have important data, drop it to a DVD. Put that in a separate place. Carry lots of them. Don't look like a terrorist or mad scientist as you go through customs and immigration.
Don't worry, if you carry lots of DVDs, you'll look more like some kind of perv than anything else.
You'll be happy to know that this magic is very much about the frequency and not so much about the 'watt'.
In case of interference, pulsed HF/RF can count as "any frequency you want". If making an ECG immune to cellphone signals would just involve filtering out any frequency above, say, 1 MHz (ECG bandwidth is typically 0-150 Hz, 0-several kHz if you want to observe specific phenomena like crotchetages and pacemaker pulses), then it would already be done, because that's easy.
And for the record, I have a M.Sc. in biomedical engineering and am also working on ECG machines.
So if somebody gets on a plane in Pakistan to go to the USA, the DHS officers in Islamabad check the no fly list?
No. The airline or travel agent selling them the ticket has to send their data to the DHS. Then the DHS says "No.". If that plane still goes anywhere near the US, it will be forced either to turn back or to land somewhere else and the person on the list will be singled out and sent back. You didn't hear what happened to Yussuf Islam (Cat Stevens)?
In other words, they've sent their no fly list to almost every airport in the world?
No, they're just getting the names of anyone who's flying to the US, long before the plane actually takes off.
Wouldn't that mean that Osama bin Laden could maybe get a copy, and check what names are on it?
No.
How's that going to work?
I've just given you a rough outline of how it works. I'm sure the website of the DHS contains more information, feel free to research it on your own.
The point is, our law does not require us to apply the constitution to non-citizens,
Citation needed.
No article of the bill of rights mentions "citizens". Instead, they either mention "person", "no one shall..." or are worded in passive ("Excessive bail shall not...").
Also, I am pretty sure there is some sort of accepted international law on how to treat foreign citizens.
There's something along those lines, but in this case, the SCOTUS has decided that unless there are actual laws that require foreign nationals to be treated according to these treaties, they are not binding even if they were signed by the US.
If you stop and think about it, the principle of innocent before proven guilty is violated on a regular basis in the US. How about DUI checkpoints?
Err... do you actually get your license taken away, fined ot stuck in jail at DUI checkpoints before they actually check your BAC, or regardless of the result of such a test?
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Why ... he might just be powering a big honkin' AC and a big honkin' stereo with the engine. Of course his mileage will go up when he goes faster, since that means the engine spends more of its power actually moving the vehicle.
And here I thought efficiency was related to the ratio of source temperature to sink temperature, and all this seems to do is reduce source temperature.
The water is instantly flash-heated by the fuel explosion into steam for an instant expansion of 1:800 => making all your combustion engines be a partial Steam Engine by piping some H2O mist in through a vacuum tube port.
It's flash-heated, meaning that it reduces source temperature. Bad for the efficiency. And how's the steam generated from this contraption different from the steam that burning hydrocarbons produces?
Interesting thing about putting real-time steam into a running engine is that the inside of the cylinder ~spark plug electrodes and everything~ is being STEAM CLEANED as the car runs.
How again is this steam different from the steam that results from burning hydrocarbons?
The problem with driving in the highest gear is the engine is lugging at 55-65 mph, which means the fuel isn't being fully burned, which means carbon buildup in the cylinders and on the piston head. This is nothing but premature aging of the engine.
How again does drawing heat out of the combustion reaction help with making it more complete?
Whoops, that should be isentropic compression/expansion, isobaric heating and isovolumetric cooling for the Diesel cycle, and isentropic compression/expansion and isovolumetric heating&cooling for the Otto cycle. I know why I hate thermodynamics.
Today, it pretty much is.
Petrol fuel-injected systems need to continue to inject fuel into the engine to keep the 4-stroke pattern working properly. It needs to continue that cycle of intake, compression, ignition, exhaust, and so on.
Why? Why can you not leave out injecting fuel and ignition, as long as the engine is cranked externally? All it does it turn the engine into an air pump.
Diesel's are different. Since diesel's simply combust due to compression, fuel can probably be halted or started any time. I confess I'm not too familiar to the inner workings of diesel.
Usual diesel engines are four-stroke engines with the same phases as a gasoline engine, except for compressing air instead of an air-fuel mixture and "igniting" by actually injecting fuel after the compression has taken place. This results in a thermodynamically different cycle (isentropic compression/expansion and isobaric heating and cooling, vs. adiabatic compression/expansion and isovolumetric heating/cooling in the Otto cycle), but technically it's still intake (of air), compression, combustion and exhaust.
Do a test. Jump into a manual petrol car - not a diesel one. Rev up nice and high. Now, let go of the throttle.
No need to do this test. Since the car is not moving, there's no external source cranking the engine, so the ECU will continue to inject fuel.
You need to do the test while you're going downhill (or at least on a level road, above a certain speed). Leave the clutch engaged, take your foot off the accelerator. The ECU will cut off the fuel to the engine as long as the engine rpm are kept above a minimum level by the car moving forward. If you disengage the clutch, the ECU will again start injecting fuel, as the external power source is gone.
The feature is the same on modern, fuel-injected gasoline engines. It's just that you can't hear it all that well, since gasoline engines shouldn't knock.
You should have mentioned that before, and also be aware that diesel engines work on completely different theory to petrol engines. At the most fundamental level even - working on combustion under compression as opposed to combustion caused by spark plugs.
Err ... if the engine is not fueled, none of this should matter. There's no compression, no need for ignition, all that happens is that the pistons are being moved back and forth and the engine is reduced to being an air pump.
Yes, it does. Until you've got an old and/or crappy car.
If it wasn't, you wouldn't hear your engine running at all. Just the sound of the road, which of course, is not the case.
Yes, this is the case. It's a very, very audible difference. I'm driving a car with a diesel engine, and when I take my foot off the accelerator when going downhill the engine is silent (no diesel knock). If I touch the accelerator, I hear the typical diesel engine sound.
But of course you still hear the crankshaft (and everything that connects to it) being _turned_. The only sound that stops is that of the actual combustion, which isn't all that prominent in a gasoline-powered car, so you'll probably not notice the difference there.
Yes, you're missing the fact that the crankshaft could be turned by an external source of torque (such as the momentum of the car, transferred up the powertrain instead of down). Of course, if there's no such source (i.e. the car is stopped, going too slow, or the clutch is not engaged), then the engine needs to consume some fuel to keep running.
Err ... but if you put the tranny in neutral, then the engine needs to consume some fuel just to keep running (and drive various things connected to the crankshaft, like water pump, oil pump, alternator, AC, etc).
Please, please, please use your brakes when coming to a stop and NOT your engine.
What if I don't want to come to a stop and just want to stop accelerating when going downhill?
Brakes are balanced to work at every tyre whereas engine braking has the potential to make only half your vehicles tyres rotate at a different speed to the road surface which could cause a spin.
Err ... yikes. If that happens, your vehicle wasn't roadworthy to begin with, or the road conditions were so bad that applying the brakes wouldn't have been that much better.
Also, what you're basically saying here is that accelerating could cause a spin (since it also changes the vehicles speed by using the engine).
Look up any advanced driver training material if you need to know more.
Got any concrete citations for that?
To you (and whoever modded you informative): Welcome to the age of fuel-injected cars. Once you get rid of that old carbureted clunker of yours, you'll find that your ages-old wisdom has suddenly become obsolete and counter-productive, thanks to automated fuel-cutoff technologies.
Car designers seem to have caught on this decades ago. Have you seen any recent Audis or BMWs and compared them to earlier models? That's clearly a trend toward looking mean and aggressive already. This study just confirms what car designers have known for a long time.
Which, do you imagine, is cheaper to replace if you break it? Brakes, or engine?
As long as you don't over-revv the engine, using it to brake shouldn't have any significant effect on its lifetime. No one's saying that you should shift into first gear when you're going 65 mph.
And your brakes not working when you need them can be even more expensive.
Err ... yes?
That's what basically everyone (except for truck drivers and -mechanics) means when they say "engine braking". Most people don't even know what an exhaust brake is, and the only people who would equate "engine brake" with "exhaust brake" would be the ones actually driving or servicing vehicles that are fitted with one (i.e. trucks and such).
So, yes, "engine braking" is equal to "take your foot off the accelerator (and maybe shift down early, without over-revving the engine)" for most drivers.
Err ... that's what the GP said. If you let the engine idle, it needs to consume fuel to keep running. If you use the internal friction of the engine to brake, then the engine consumes the cars kinetic energy to keep running, without consuming fuel.
"Engine Braking" needs the engine to be fitted with an Engine Brake ("Jake Brake"), and only diesel engines have this.
You're confusing "engine brake" and "exhaust brake". Engine braking uses the internal friction of the engine (and the power consumed by all the stuff driven by the engine - water pump, oil pump, alternator, AC and whatnot) to slow the car down, an exhaust brake additionally turns even more kinetic energy into heat by just compressing the exhaust gasses.
This sounds like something that, if it works, would apply to many forms of cancer. Is it just because breast cancer research is popular in funding circles or is there something specific to breast cancer to limit the applicability of the technique to breast cancer tumours?
Yes: Breast cancer occurs in tissue that is easily accessible from the outside and that is not vital for the patient.
This means you can stick a needle in it and try to thermally destroy the cancer. The same technique could not be applied, to say, brain tumors or bone/pancreas/colon/liver/kidney/lung/esophagal/stomach/bladder cancers, since they are either not easily accessible by probe or will react very badly if the tumor is destroyed too aggressively (i.e. with too much loss of healthy tissue), or will require additional surgery after the tumor has been removed since you can't simply wait for the "hole" to fix itself.
There is no pulling effect, you just avoid spending fuel at pushing air out of the way because the car in front of you has already done it.
In fact, the opposite happens - it _decreases_ the fuel use of the car in front of you, even though by a smaller amount than what you save. This is due to wind resistance not only happening by overpressure in front of the car, but also by the lower pressure behind the car, and if there's someone drafting behind you, they're essentially taking some of lower pressure off your car.
... that in the future, we'll be owned by computers, I thought they means "pwnd", and not literally "owned", as in "property".
Hey, I buy your arguments, but it is the ECG makers design decition ($$$) if they choose to not handle mobile phone noise.
There's no meaningful way to distinguish between a mobile phone packet and a pacemaker pulse in the few ms that you have available for this task, if you're not willing to accept more false negatives (and you are not).
And these things are already shielded against lots of interference (for example defibrillator pulses and HF surgery devices, both of which surpass mobile phone emissions by a few orders of magnitude), but those are transient and it's not expected that the device considers measuring while the interference it active.
I think that today it is unacceptable if critical equipment breaks if a mobile phone is closeby.
That's a bit like saying "It's unacceptable that an operating room becomes unsterile if you herd a bunch of preschoolers through it."
In an ECG, you're dealing with signals in the sub-millivolt range, coming from an amazingly good antenna (the human body). EEG would be even worse, there you're looking a microvolts.
If you have important data, drop it to a DVD. Put that in a separate place. Carry lots of them. Don't look like a terrorist or mad scientist as you go through customs and immigration.
Don't worry, if you carry lots of DVDs, you'll look more like some kind of perv than anything else.
You'll be happy to know that this magic is very much about the frequency and not so much about the 'watt'.
In case of interference, pulsed HF/RF can count as "any frequency you want". If making an ECG immune to cellphone signals would just involve filtering out any frequency above, say, 1 MHz (ECG bandwidth is typically 0-150 Hz, 0-several kHz if you want to observe specific phenomena like crotchetages and pacemaker pulses), then it would already be done, because that's easy.
And for the record, I have a M.Sc. in biomedical engineering and am also working on ECG machines.
Human evolution hasn't stopped, it just happens at a pace that is hard for humans to observe.
Yes. You didn't know that?
So if somebody gets on a plane in Pakistan to go to the USA, the DHS officers in Islamabad check the no fly list?
No. The airline or travel agent selling them the ticket has to send their data to the DHS. Then the DHS says "No.". If that plane still goes anywhere near the US, it will be forced either to turn back or to land somewhere else and the person on the list will be singled out and sent back. You didn't hear what happened to Yussuf Islam (Cat Stevens)?
In other words, they've sent their no fly list to almost every airport in the world?
No, they're just getting the names of anyone who's flying to the US, long before the plane actually takes off.
Wouldn't that mean that Osama bin Laden could maybe get a copy, and check what names are on it?
No.
How's that going to work?
I've just given you a rough outline of how it works. I'm sure the website of the DHS contains more information, feel free to research it on your own.
The point is, our law does not require us to apply the constitution to non-citizens,
Citation needed.
No article of the bill of rights mentions "citizens". Instead, they either mention "person", "no one shall ..." or are worded in passive ("Excessive bail shall not ...").
Also, I am pretty sure there is some sort of accepted international law on how to treat foreign citizens.
There's something along those lines, but in this case, the SCOTUS has decided that unless there are actual laws that require foreign nationals to be treated according to these treaties, they are not binding even if they were signed by the US.
http://en.wikipedia.org/wiki/Vienna_Convention_on_Consular_Relations
http://en.wikipedia.org/wiki/Medellin_v._Texas
Err ... do you actually get your license taken away, fined ot stuck in jail at DUI checkpoints before they actually check your BAC, or regardless of the result of such a test?
But he's on the no-fly list, so they don't let him on the plane.
If he's on the no-fly list, then he doesn't get on a flight to the USA in the first place. Victory of the DHS certain.