Well, obviously I'm not trying to promote a variation of playing chicken. Sure, in situations as you describe one has to break or change to a lower gear to keep the speed of the car in check. The good thing about a car capable of charging its batteries when breaking is, however, that break energy goes to the batteries and can be re-used fairly efficiently, whereas in regular petrol cars you're heating the air and go for early replacement of the brake pads. My main point is merely that the way one drives is of effect on how much one spends on gas, and the second point is that while some aspects of the energy-saving driving style lowers the average speed, others increase the average speed.
The Dutch government has promoted "the new way of driving", so at least motorists have knowledge about it. When taking driving exams, students should use the new style of driving (after that, however.....).
As to ending up between the trucks, there was such a nasty and deadly accident a while ago here. Shit happens. On the other hand, truck drivers are much less likely to perform stupid manoeuvres compared to regular car drivers, so that compensates for the risk. I'll usually leave my leading truck when I end up between two trucks, or I increase the distance to the leading truck.
Well, on the way up, the fuel efficiency drops. But you build up potential energy, so you hardly use any energy when the car goes down. Any braking power is passed to the batteries. Driving with my dad's petrol car in mountainous regions in France and Italy, I was always surprised that I managed to get a mileage better than regular (probably helped by the fact that the average speed was lower). The first rule of fuel efficiency is: BREAKING IS FOR LOSERS. If you have to brake, you're not good at anticipating very well. Cross-road or round-about coming up: lift you foot from the peddle. Second rule: KEEP ROLLING. You must make sure you keep on roling. If a traffic light is coming up, I may brake well before the traffic light, then roll along. In all likelihood, the light is green when I reach it, and I may have left a speed of 15 miles per hour. If I had stopped, I would have been slower too, because I'd have to start from zero. It is one of those things people fail to understand (just like: the fastest way to overtake another car is to keep a distance from him (much safer too), instead of tailgating. You can see the opportunity for taking over earlier, you can start making speed, if it doesn't work you break, if it does work you're having a first speed difference in comparison to a tail gater). Lastly, I may drive behind a truck (we have laws here that forbid them to pollute too much so it is OK). Saves up to 10% (more if I were closer, but as long as we don't have a connection between braking and distance control, that is out).
Given that Apple's 30" now comes at E1800, which equals about L 1216, I don't think your cost comparison is accurate.
Some files are best viewed large (A4 pdf's, for example), for which reason I'm hoping that the Mac mini will support 30", in which case I'll buy my secretary a 30" monitor. This would save scrolling and looking for text.
Bert Who personally thinks that a two monitor set up including a 30" is better a compromise we should be able to reach
Perfectly valid reasoning, assuming that all of these couple of hundreds of million computer users visited his website and assuming that everyone feels like writing a letter to the author.
First off, I'm very happy that you revisited the thread (and hope you do it again). I'll do some further studying on what you wrote this.
Two things: Firstly, I'm an old geezer and when learning about thermodynamics at the university I used a book by Gordon M. Barrow (Physical chemistry, fourth edition), which derives the Second law using the gas laws, as indicated in my previous post. I admit that things like the gas constant drop out of the equation, which could - but not necessarily - imply that the formula is valid for gasses only, as Th could be the high T of a gas etc. Being trained as a scientist, I wouldn't take his derivatation of the Second law further than his premisses without further proof. That is not to say that it doesn't go beyond that, but Mr. Barrow's book doesn't offer this proof.
The second thing (which I came up with only after mulling further on it after my last post): Would you suggest that it is is not possible to use a system involving the freezing and thawing of ice (you'll know that this system remains at zero degrees Celcius; and that 1 kg of ice has a significantly larger volume) would be impossible to use for converting thermal energy into electricity? Afterall, here Th and Tl are the same (zero degrees). Somehow I find this hard to believe (but it is just a gut feeling). This specific system might actually be feasible to do calculations on. Another one I thought up, but is already a bit harder to do calculations on, is the expansion of a rod of metal.
As to why I'm interested in this is. I'm interested in the conversion of (low grade) heat (like solar heat) into electricity using liquid as a medium. There was a guy in the 1930's, Malone, who got amazing efficiencies (for his time) using water as a medium. Now, water isn't the best of media. Parafins show a much larger coefficient of expansion within a short range (which can be something like 12% over a 30 degrees range). Nevertheless, it is very hard to harvest the work of such relatively small volumes of expansions, but for parafins things look much better than for water. Having said that, a guy I know that is involved in trying to develop a system relying on parafins as the medium has indeed found a raise in temperature if parafin is compressed (and as you know it is pretty hard to compress a liquid). We are only talking a couple of degrees here, which would suggest that high conversion would be possible (a high percentage where the amount of energy to raise the parafin from RT to 80 degrees C is 100%).
If one looks at how the Second Law is derived, one sees symbols like V1, V2, and R, the GAS constant in there. I wouldn't think it is very scientific to generalize it without proof. So I'd rephrase your sentence as "the Second Law Of Thermodynamics is indeed a universal law of physics that applies to any closed physical GAS-BASED system where at least some form of weak coupling exists between the possible states of the system"
Try to derive the Second Law in the same way as done for gasses, but now based on the formulas for liquids. If it ends up with such a simple formula, it will be a cinch. Believe me, it is not. Or rather, please don't believe me, do it and write an article about it. I haven't seen it, although I'd love to. Don't forget to include some calculations for liquids that don't show linear behaviour with respect to T and energy content (such as paraffins). Isn't such non-linear behaviour not an indicator that the efficiency can't be the Th-Tl/Th as derived using gas formulas? Even if I'm wrong, you'd have an article that would qualify for Nature.
When I said that 100% is the max, and now I know you are a physicist I know it for certain, was that I assumed you were not a perpetuum mobile nut and to convey I'm not one either. This (almost) 100% is for a thermonuclear bomb in absolute outer space (near zero K).
You are correct in stating that the max efficiency, as calculated with the formula, gives values of much less than 100%, which is why I proposed to calculate real world efficiency differently, because that gives a better idea of how close to the maximum (of say 25%) you really are.
Even while this discussion old, I hope you'll be back for a response.
"Unfortunately, thermoelectric converters based on the Seebeck effect are not going to help with efficiency by a large amount.
Firstly, there is a theoretical limit (Carnot Cycle [wikipedia.org]) to the efficiency of any pure heat engine based on the Second Law of Thermodynamics."
I wish I didn't have to waste so much energy on (would be) physicists that don't realise that the second law was derived for GASSES. For other systems there are/will be other laws. E.g., mechanical energy can be converted into electricity near 100% vice versa.
We will both agree agree that 100% is the max. But never ever come up with the Second Law again unless you're talking about a conversion involving gasses and unless you don't fail to realise that this theoretical limit is what can be achieved in 1 single step. Do more steps, and you'll convert more heat into electricity (e.g. with an organic Rankine cycle).
As to the 100% max of the Second Law, I think it doesn't properly represent the efficiency in the real world. The Second Law doesn't appear to say much more than that for a gas the energy content is linear with the temperature. I believe that the 100% should be defined for no heat released in the environment (your T1 of about 300 K). If we were to calculate the efficiency of engines etc. in this way, we would have a much better idea of how much we can improve and whether that is useful.
Bert Who realises that he's not going to cough up the money to invest the money to do all these additional steps
Could you care to comment on the rather ambiguous expression "share a cell"?
Bert
Re:Becuase People don't know what they want!
on
Why Software is Hard
·
· Score: 1
On the contrary. There is lots of standardisation. The programmer says "I've an API here, and I can give you as many doors as you want, in 10 minutes, but there is no API for the DeLorean door you request and it will take me 2-6 month to program it. Yes, I know Mr. User that you just want to drive your car, but I want you to give me the specs for every millimeter of that DeLorean door, or it won't get done". Then he starts complaining if the customer suggest a Ferrari door; that the customer changes his mind all the time.
"I work for mobile phone operator. We have tried to push people to use data services on their mobile devices for years now. Why? Because we charge enormous amounts of money for data and it makes us a lot of money."
And for exactly that reason I refuse to use it. Voice is data, like internet stuff. I don't see any reason to pay tens of times more for one byte than for the other. (and it seems to me that the transfer requirements for voice are higher than for internet data). If you're bosses really want me to use it, give me a $40 per month deal like I have for voice. You'll make up in volume (more users) than what you're earning now.
First of all, thanks for the reply. I was really curious about it. I'm also pleased to hear that the current period is long in your view.
I appreciate your point about bit torrent. Personally I do buy all my music and movies (but get very angry about being forced to watch the copyright notices, something copyright infringers don't have to endure). But the opposite is also lamentable: There currently is a push to create a broadcast right. Take a non-copyrighted creation, broadcast it, and you're the new copyright owner! Things like software patents blurr the vision of many about the clever workings and usefulness of a good patent law. Similarly, things like silly copyright terms, underpayment of creators by megacorps and said silly broadcast proposal will not help creators as people will start losing faith/will readily grab the excuse not to abide by it. That is neither to your advantage, nor to that of the society.
I'm a patent attorney and no stranger to IP. Having said that, any IP law is, or at least should be, a balance to on the one hand freedom to operate (both for IP users and for IP creators) and on the other hand a means for compensation for IP creators. For patents, that balance is not there for patents on software. Also for patents, at least they last for 20 years max. For copyright, that balance is not there. And I'm curious to hear whether you think it is a good thing that whatever you create is still under copyright more than 40 years after you die.
The refractive index is the ratio between the speed of light/speed of light in medium. Because c is the top speed, refractive index of air is close to 1, and from there it is only up.
Now, with a negative breaking index, light isn't just refracted (bent) at an interface (transition from one refractive index to the other), but actually makes a U-turn (V-turn might be a better term). But we don't expect the light to go faster than c, do we? (Now that would make a couple of things possible!).
Perhaps people don't care, perhaps they do. I don't know. I do know I DO. I want all my stuff legal. But my Mac allows me to run my own region only (yeah, I can change a couple of times, but then he ends up with the one that refuses to play my other DVDs). I want to have a movie (Tucker, the man and his dream). I have ordered it at a store, but can't buy it here in Europe. In the US it is available, but then I have the DVD region problem. The only solution, which I don't want to consider, is to pirate. I welcome anything that leads to competition, and hopefully the end of DRM, because it only bothers honest people.
Slashdot Mirror
PHB: So, OpenXML is ten times better.
Bert
Well, obviously I'm not trying to promote a variation of playing chicken. Sure, in situations as you describe one has to break or change to a lower gear to keep the speed of the car in check. The good thing about a car capable of charging its batteries when breaking is, however, that break energy goes to the batteries and can be re-used fairly efficiently, whereas in regular petrol cars you're heating the air and go for early replacement of the brake pads. My main point is merely that the way one drives is of effect on how much one spends on gas, and the second point is that while some aspects of the energy-saving driving style lowers the average speed, others increase the average speed.
Bert
The Dutch government has promoted "the new way of driving", so at least motorists have knowledge about it. When taking driving exams, students should use the new style of driving (after that, however.....).
As to ending up between the trucks, there was such a nasty and deadly accident a while ago here. Shit happens. On the other hand, truck drivers are much less likely to perform stupid manoeuvres compared to regular car drivers, so that compensates for the risk. I'll usually leave my leading truck when I end up between two trucks, or I increase the distance to the leading truck.
Bert
Well, on the way up, the fuel efficiency drops. But you build up potential energy, so you hardly use any energy when the car goes down. Any braking power is passed to the batteries. Driving with my dad's petrol car in mountainous regions in France and Italy, I was always surprised that I managed to get a mileage better than regular (probably helped by the fact that the average speed was lower). The first rule of fuel efficiency is: BREAKING IS FOR LOSERS. If you have to brake, you're not good at anticipating very well. Cross-road or round-about coming up: lift you foot from the peddle. Second rule: KEEP ROLLING. You must make sure you keep on roling. If a traffic light is coming up, I may brake well before the traffic light, then roll along. In all likelihood, the light is green when I reach it, and I may have left a speed of 15 miles per hour. If I had stopped, I would have been slower too, because I'd have to start from zero. It is one of those things people fail to understand (just like: the fastest way to overtake another car is to keep a distance from him (much safer too), instead of tailgating. You can see the opportunity for taking over earlier, you can start making speed, if it doesn't work you break, if it does work you're having a first speed difference in comparison to a tail gater). Lastly, I may drive behind a truck (we have laws here that forbid them to pollute too much so it is OK). Saves up to 10% (more if I were closer, but as long as we don't have a connection between braking and distance control, that is out).
Bert
Given that Apple's 30" now comes at E1800, which equals about L 1216, I don't think your cost comparison is accurate.
Some files are best viewed large (A4 pdf's, for example), for which reason I'm hoping that the Mac mini will support 30", in which case I'll buy my secretary a 30" monitor. This would save scrolling and looking for text.
Bert
Who personally thinks that a two monitor set up including a 30" is better a compromise we should be able to reach
Winning would help to get rid of the competition. Like another thread says, there should be prizes for being second, third etc.
Bert
Because it is fun.
Bert
Perfectly valid reasoning, assuming that all of these couple of hundreds of million computer users visited his website and assuming that everyone feels like writing a letter to the author.
Bert
you can use a wokkie-tokkie
Bert
I'm about to sit the European patent examination (that's next week), and as far as I can see your parent sees things correctly.
Bert
First off, I'm very happy that you revisited the thread (and hope you do it again). I'll do some further studying on what you wrote this.
Two things:
Firstly, I'm an old geezer and when learning about thermodynamics at the university I used a book by Gordon M. Barrow (Physical chemistry, fourth edition), which derives the Second law using the gas laws, as indicated in my previous post. I admit that things like the gas constant drop out of the equation, which could - but not necessarily - imply that the formula is valid for gasses only, as Th could be the high T of a gas etc. Being trained as a scientist, I wouldn't take his derivatation of the Second law further than his premisses without further proof. That is not to say that it doesn't go beyond that, but Mr. Barrow's book doesn't offer this proof.
The second thing (which I came up with only after mulling further on it after my last post): Would you suggest that it is is not possible to use a system involving the freezing and thawing of ice (you'll know that this system remains at zero degrees Celcius; and that 1 kg of ice has a significantly larger volume) would be impossible to use for converting thermal energy into electricity? Afterall, here Th and Tl are the same (zero degrees). Somehow I find this hard to believe (but it is just a gut feeling). This specific system might actually be feasible to do calculations on. Another one I thought up, but is already a bit harder to do calculations on, is the expansion of a rod of metal.
As to why I'm interested in this is. I'm interested in the conversion of (low grade) heat (like solar heat) into electricity using liquid as a medium. There was a guy in the 1930's, Malone, who got amazing efficiencies (for his time) using water as a medium. Now, water isn't the best of media. Parafins show a much larger coefficient of expansion within a short range (which can be something like 12% over a 30 degrees range). Nevertheless, it is very hard to harvest the work of such relatively small volumes of expansions, but for parafins things look much better than for water. Having said that, a guy I know that is involved in trying to develop a system relying on parafins as the medium has indeed found a raise in temperature if parafin is compressed (and as you know it is pretty hard to compress a liquid). We are only talking a couple of degrees here, which would suggest that high conversion would be possible (a high percentage where the amount of energy to raise the parafin from RT to 80 degrees C is 100%).
Bert
No, I'm quite serious.
If one looks at how the Second Law is derived, one sees symbols like V1, V2, and R, the GAS constant in there. I wouldn't think it is very scientific to generalize it without proof. So I'd rephrase your sentence as
"the Second Law Of Thermodynamics is indeed a universal law of physics that applies to any closed physical GAS-BASED system where at least some form of weak coupling exists between the possible states of the system"
Try to derive the Second Law in the same way as done for gasses, but now based on the formulas for liquids. If it ends up with such a simple formula, it will be a cinch. Believe me, it is not. Or rather, please don't believe me, do it and write an article about it. I haven't seen it, although I'd love to. Don't forget to include some calculations for liquids that don't show linear behaviour with respect to T and energy content (such as paraffins). Isn't such non-linear behaviour not an indicator that the efficiency can't be the Th-Tl/Th as derived using gas formulas? Even if I'm wrong, you'd have an article that would qualify for Nature.
When I said that 100% is the max, and now I know you are a physicist I know it for certain, was that I assumed you were not a perpetuum mobile nut and to convey I'm not one either. This (almost) 100% is for a thermonuclear bomb in absolute outer space (near zero K).
You are correct in stating that the max efficiency, as calculated with the formula, gives values of much less than 100%, which is why I proposed to calculate real world efficiency differently, because that gives a better idea of how close to the maximum (of say 25%) you really are.
Even while this discussion old, I hope you'll be back for a response.
Bert
Sorry, twice the brain size makes them just twice as stupid. In that, they don't differ from regular people from, say, [state suppressed].
Bert
"Unfortunately, thermoelectric converters based on the Seebeck effect are not going to help with efficiency by a large amount.
Firstly, there is a theoretical limit (Carnot Cycle [wikipedia.org]) to the efficiency of any pure heat engine based on the Second Law of Thermodynamics."
I wish I didn't have to waste so much energy on (would be) physicists that don't realise that the second law was derived for GASSES. For other systems there are/will be other laws. E.g., mechanical energy can be converted into electricity near 100% vice versa.
We will both agree agree that 100% is the max. But never ever come up with the Second Law again unless you're talking about a conversion involving gasses and unless you don't fail to realise that this theoretical limit is what can be achieved in 1 single step. Do more steps, and you'll convert more heat into electricity (e.g. with an organic Rankine cycle).
As to the 100% max of the Second Law, I think it doesn't properly represent the efficiency in the real world. The Second Law doesn't appear to say much more than that for a gas the energy content is linear with the temperature. I believe that the 100% should be defined for no heat released in the environment (your T1 of about 300 K). If we were to calculate the efficiency of engines etc. in this way, we would have a much better idea of how much we can improve and whether that is useful.
Bert
Who realises that he's not going to cough up the money to invest the money to do all these additional steps
Viva la revolucion!
Could you care to comment on the rather ambiguous expression "share a cell"?
Bert
On the contrary. There is lots of standardisation. The programmer says "I've an API here, and I can give you as many doors as you want, in 10 minutes, but there is no API for the DeLorean door you request and it will take me 2-6 month to program it. Yes, I know Mr. User that you just want to drive your car, but I want you to give me the specs for every millimeter of that DeLorean door, or it won't get done". Then he starts complaining if the customer suggest a Ferrari door; that the customer changes his mind all the time.
Bert
Although you've got to factor in that he still has to pay for that cable.
Bert
In other news scientits have revealed the first fossil of humping dino's
Bert
Is that because they have a big stockpile of unsold zunes?
Bert
"I work for mobile phone operator. We have tried to push people to use data services on their mobile devices for years now. Why? Because we charge enormous amounts of money for data and it makes us a lot of money."
And for exactly that reason I refuse to use it. Voice is data, like internet stuff. I don't see any reason to pay tens of times more for one byte than for the other. (and it seems to me that the transfer requirements for voice are higher than for internet data). If you're bosses really want me to use it, give me a $40 per month deal like I have for voice. You'll make up in volume (more users) than what you're earning now.
BFN
Bert
First of all, thanks for the reply. I was really curious about it. I'm also pleased to hear that the current period is long in your view.
I appreciate your point about bit torrent. Personally I do buy all my music and movies (but get very angry about being forced to watch the copyright notices, something copyright infringers don't have to endure). But the opposite is also lamentable: There currently is a push to create a broadcast right. Take a non-copyrighted creation, broadcast it, and you're the new copyright owner! Things like software patents blurr the vision of many about the clever workings and usefulness of a good patent law. Similarly, things like silly copyright terms, underpayment of creators by megacorps and said silly broadcast proposal will not help creators as people will start losing faith/will readily grab the excuse not to abide by it. That is neither to your advantage, nor to that of the society.
Bert
I'm a patent attorney and no stranger to IP. Having said that, any IP law is, or at least should be, a balance to on the one hand freedom to operate (both for IP users and for IP creators) and on the other hand a means for compensation for IP creators. For patents, that balance is not there for patents on software. Also for patents, at least they last for 20 years max. For copyright, that balance is not there. And I'm curious to hear whether you think it is a good thing that whatever you create is still under copyright more than 40 years after you die.
Bert
The refractive index is the ratio between the speed of light/speed of light in medium. Because c is the top speed, refractive index of air is close to 1, and from there it is only up.
Now, with a negative breaking index, light isn't just refracted (bent) at an interface (transition from one refractive index to the other), but actually makes a U-turn (V-turn might be a better term). But we don't expect the light to go faster than c, do we? (Now that would make a couple of things possible!).
So, what's up with the reported value of -0.6?
Bert
Perhaps people don't care, perhaps they do. I don't know. I do know I DO. I want all my stuff legal. But my Mac allows me to run my own region only (yeah, I can change a couple of times, but then he ends up with the one that refuses to play my other DVDs). I want to have a movie (Tucker, the man and his dream). I have ordered it at a store, but can't buy it here in Europe. In the US it is available, but then I have the DVD region problem. The only solution, which I don't want to consider, is to pirate. I welcome anything that leads to competition, and hopefully the end of DRM, because it only bothers honest people.
Bert