With a typical brushed DC motor connected directly to a battery, you would be right - the braking torque provided by drawing current out of the motor will decrease with wheel speed.
I guess that you mean DC motor connected via power electronics to the battery, as it is impossible to make a drivable vehicle that would have directly attached motor to the battery.
With some intelligence built into the powertrain (i.e., computing power, algorithms, control laws), you can adjust the gearbox setting (by shifting gears) and the power electronics (by modulating frequency or duty cycle) such that braking torque can be constant throughout deceleration. The deceleration power in the mechanical and electrical subsystems won't be a constant, though.
Yes, you are right, I did not take into account that Prius is not a typical electric vehicle - EVs usually do not have gearbox. If you have a vehicle with a gearbox, esp. one with variable ratio, you can select any ratio of current comparing to the speed of the rotor that will give you maximal energy flow toward the battery.
My understanding is that the main reason the Prius has to use its mechanical brakes at all is that the components in the regenerative powertrain have maximum power ratings.
I firmly believe that this is due to slow speed conditions. In such conditions (when inducted voltage inside the motor is too low), most of the power inside the motor is used on the internal resistance. Even worse, if the car is still but on some angled surface, it would be wasteful to use the motor to keep the vehicle motionless - it's better choice to use mechanical brakes in such case.
For instance, the batteries have some maximum charging current limit. So the computer has to augment the regenerative braking (which is power-limited) with the mechanical brakes (which don't have that limit in normal usage).
Larger vehicles do not do this kind of trade. If there is too much energy that cannot be recuperated, they dump it to specially mounted resistors. But I don't know if Prius has such resistors, I guess that it doesn't have them.
My Prius [...] has ordinary mechanical brakes in case the regenerative braking cannot recharge the battery fast enough to slow down the car, but they rarely engage and the car has never needed a brake job because the battery (plus friction) is already pretty good at absorbing the energy.
Actually, recuperative braking cannot stop the car efficiently. So you can use impractical but energy efficient recuperative braking + mechanical braking, or to use pure engine breaking.
These two processes are essentially the same thing - invert the current inside the electric machine and it will brake the vehicle. The only problem is how to do this. If you want to do that in a manner that every single joule finds it way to the battery, breaking torque will decrease as the speed decreases and you will have to apply mechanical brakes in one moment.
If you do this by forcing the same braking torque all the time strictly by the engine, which is quite simple to do, in one moment energy flow will not be toward the battery, but from the battery. This is due to internal resistance of the electric motor.
In general, electric vehicle must have mechanical brakes simply as a safety measure. But electric vehicles are essentially more safe that IC-based ones, as they always have two truly independent braking systems.
Yes, they are tech savvy but they don't have a clue how the hell is the damn thing working. I expect that very soon people will talk about "ghosts inside the cell phone", although they won't call then ghosts. The only good thing is that they won't be afraid of those 'ghosts'.
I agree that Google will have to fight an uphill battle. Apple has a lot of people well experienced in design of the consumer electronics. But Google has some very good designers as well. I think that UI of GMail is really good; this was the first web mail I really wanted to use. Also, GTalk seem like "oh, dear, finally some simple messenger", or even better "look, it works from browser now". Google's home page, which seems normal now to us, was 100% opposite to what we were learned to see before (we used monster pages like Yahoo!, MSN).
Also, there is one big reason why I think that in long term Google will do better (although I believe they take more risky approach). They have more open-minded business model. In mentioned GMail, they gave me everything I wanted. For free. I used their system as my spam filter. No revenue for them. But in the long term, that payed off (I use their web interface regularly now). They are not greedy in that short-sighted manner like Apple is. They seem feature friendly to the user.
Apple is old business done right. Google is new business (note that I did not say that this is necessarily "done right").
Any perceived difference is in the listeners head. If someone gives $7000 just for cables, there is certainly some difference in his head comparing to the head of someone who is not crazy and/or mentally challenged.
I'm not a real expert, but I had some experience in systems that are not "hard real-time".
I can't recall exact definitions, but there are "soft" and "hard" real-time systems. In soft systems you can miss some deadlines. Like in video game, where you don't want to skip the frame, but from time to time that happens and its not a big deal.
Some very expensive systems are soft real-time. For instance, AGC - which is basically fine-tuning of power system's frequency (to keep it 50 or 60 Hz) is not hard real time. In our system, we issued commands in every 4 seconds. It was not big deal it we were late with our command for even a whole second. System would accumulate the error and it would be corrected the next time.
If the sailing is a process that is slow enough and if its actuators do not require precise timing, you can live with Matlab quite well. Simply, some processes are very 'forgiving', i.e. they are real-time in very vague terms. Even the most unpredictable systems (like Windows + Java interpreter + + Matlab + system coded in Matlab) can be used in such situations.
body is making an effort to tackle the problem of Yugoslavia's.yu outliving the country by over a decade
Country typically known as Yugoslavia fell apart in 1991-1992, but new country consisting only of Serbia and Montenegro continued to call itself Yugoslavia (Federal Republic of) until 2003. In 2003, it finally changed its name to far more suitable "Serbia and Montenegro".
Hence, we may say that.yu outlived Yugoslavia for only 4 years (at the moment).
From American point of view, things look a bit different. USA did not recognize name Yugoslavia for union of Serbia and Montenegro. But in 2000, after FRY reapplied for the membership in the United Nations, USA accepted that name.
When FR Yugoslavia changed its name to Serbia and Montenegro,.yu was to be replaced to.cs. It was made from Serbian name for Crna Gora and Serbia, as all posible combinations from.s* were already taken. But after only three years, "Serbia and Montenegro" disintegrated to (guess what) Serbia and Montenegro, with respective.rs and.me TLDs. These TLDs will be in use in couple of months.
Old.yu should be removed in three years period, so.yu will outlive the country for 7 years in total.
We tried to do this in southern England. Worked great till October. Then we had to send our technician every couple of days to replace the accumulator.
Strange thing that accumulator seemed to be 100% full all the time during the summer, so we thought that it would be able to survive at least the fall if not the winter.
I had their laptop. After some time, its transformer stopped working. I live in Serbia, and it is a bit tricky to get decent technical support/service here, but Sony has huge store in Belgrade downtown.
I went there, but no luck. They do not sell laptops in Serbia (mine was brought from UK), so they gave me the telephone of one repair shop, but they were not sure if they could help me. Repair shop sent me to another repair shop, and so on... After three hops, they explained me what's the issue. Sony has very rigid standards for their repair shops. To be their certified repairmen, you have to guarantee that you'll solve all problems in 24 hours. They were not able to find anyone capable of that in Serbia, so they don't have any repair shop in Serbia.
That's very interesting policy. Instead to give second class service to your customers, you give them - none.
I have never really understood the idea behind the automatic counting or automated voting system.
Here in Serbia, where we had a lot of problems with the elections, the voting itself and counting are the least problem. We had exactly the same problem as USA (i.e. corrupted legal system) but the voting procedure itself was never an issue.
Manual counting takes only couple of hours even for the largest poll stations. Summing the results takes exactly the same time everywhere. Time for summing the results is so larger than the process of counting, so it is plain stupid to try to reduce the time spent on counting. It takes couple of hours to get estimated results, and you have to wait till morning if you have close elections. No voting machine will solve this issue.
Manual counting has a lot of advantages - since you get paper trail by the very definition of the process. (I speak about process where you take you pen and then you circle the name of the wanted candidate/party.)
I live in the country (Serbia) that used to have rampant percentage of illegal software.
Before the democracy arrived here in October 2000, there was about 99.9% of illegal software. There was no official distributors of the software; nobody was interested in suing the violators... Some companies tried to legalize their server software when they created Internet sites.
What was the result: * There was no locally created mass software (like text processor or something alike), only software that required maintenance could be developed in such situations * There was no diversity (take into account that Serbia the population of only 8.000,000). In late 80's, everyone used Novel netware (even the smallest companies) with Clipper for database work * Similarly, now everyone uses MS Windows and its networking "capabilities"
Linux won its battle here in early Internet days, because there was fear that publicly exposed MS Windows web server will create MS's attention. UNIX boxes were too expensive - so typical solution in our ISP's was Linux, and it still is.
Meanwhile, software tools for programming are far more diverse now, because there is strong outsourcing industry here. Still, for local web sites, PHP is some kind of standard.
Just couple of typical uses: for sending someone's phone number or address or driving instructions; for various confirmations (like "i did exam ok", "i'l b l8 10min"); to pay car parking; to send non-urgent messages to someone who's at the office; to send urgent message someone (faster than email); to send message and to be sure if he has received it; to see how much money you have on your banking account; to cheat in school; to call someone to turn skype on (esp. useful if that person lives abroad); to contact friends while commuting using public transportation...
It is reasonable to assume that solar won't match 100% of our needs for electricity any time soon. Maximal power consumption is during the day (i.e. not night). You have to have enough resources for your peak consumption; ideal case from the grid's point of view would be to have constant flow of energy 24h a day.
Since solar cells can (in theory) cover that day-time increase in power demand, and even better, they produce energy exactly where it is consumed, it is a perfect way to keep load on high voltage lines and transformers constant.
And even even better, max demand in USA is for air conditioning, which is highest during the sunny days.
1) Write "200 000 000 000 USD" on the paper. 2) Type what's on the paper into a.txt file 3) Save the file 4) Delete the file 5) Empty the recycle bin 6) Recreate file by retyping data from the paper 7) Post the story on the/. how big financial disaster you've made, and how you've saved your ass
If I want to go to some site which is not in my bookmarks, story goes like this. I launch Firefox. I get Google page. Focus is already in the Google instead to be at URL field. If I type name there, I dont have to move to URL field and I can simply hit Enter. If I mistype the name, Google will correct me. If I decide to type in URL field, I would have to change the focus, if I miss the name I will have to try again etc... It's much simpler to let Google to take care of the correct name and TLD.
If you speak about limeses, then it depends how you go toward some value (toward 0 in this case).
For instance, both functions f1(x)=sin(x) and f2(x)=x are 0 for x = 0, but
lim x->0 (sin(x)/x) = 1, as we know.
If you take function like f1(x) = x*sin(x) and other one f2(x) = x then
lim x-> f1(x)/f2(x) = 0.
In these two cases, "0/0" have different values.
When you use division in limeses, the path you take is important, i.e. functions that describe in which way you go toward 0. That's why other posters mentioned continuity and other stuff related to functions, and not related to numbers.
Big breakthrough would be to solve lim x->0 f1(x)/f2(x) for f1(x) = 0, f2(x) = 0.
In Serbian, Pluto is called "Pluton" (just like Plato is called "Platon") and this is because it really ends with an "n" in original Greek, so this name will create additional problems.
Amount of money spent on war in Iraq would probably lead to some significant breaktroughs in alteranative fuel. Ironically, that war even increased the price of oil.
I've spent two months in Michigan this year, and I find the state of highways in USA disastrous. I've heard that Eisenhower saw that German roads after the war, and they made US system after them... I guess that state of USA highways system would be much better if their model was German autobahn system *before* the war and all the bombing...
As far as I know, it usually goes this way: You ask engineering companies to apply for the job. You set some criteria, so you take best ranked company to do the job. Then you hire second ranked company to supervise them. Since they are pissed cause they lost the contract, you can imagine how they tend to look at the actual contractor...
So it fits to "trust is good, control is better" scheme.
IIRC, the evidence is visible by the naked eye with a telescope.
There was once discussion about Moon landing here on/., and I asked if we could see Apolo equipment with a telescope. Answer was no, even with Hubble we cannot see the equipment - resolution of existing telescopes is not good enough. Still, there was a picture that seemed to catch shadows of the Apolo eqipment (Sun was almost on horizon, so shadows were loooong).
Refractors, of course, could be easily spotted from the Earth with appropriate equipment (laser and mid-size telescope).
Slashdot Mirror
These two processes are essentially the same thing - invert the current inside the electric machine and it will brake the vehicle. The only problem is how to do this. If you want to do that in a manner that every single joule finds it way to the battery, breaking torque will decrease as the speed decreases and you will have to apply mechanical brakes in one moment.
If you do this by forcing the same braking torque all the time strictly by the engine, which is quite simple to do, in one moment energy flow will not be toward the battery, but from the battery. This is due to internal resistance of the electric motor.
In general, electric vehicle must have mechanical brakes simply as a safety measure. But electric vehicles are essentially more safe that IC-based ones, as they always have two truly independent braking systems.
Yes, they are tech savvy but they don't have a clue how the hell is the damn thing working. I expect that very soon people will talk about "ghosts inside the cell phone", although they won't call then ghosts. The only good thing is that they won't be afraid of those 'ghosts'.
I agree that Google will have to fight an uphill battle. Apple has a lot of people well experienced in design of the consumer electronics. But Google has some very good designers as well. I think that UI of GMail is really good; this was the first web mail I really wanted to use. Also, GTalk seem like "oh, dear, finally some simple messenger", or even better "look, it works from browser now". Google's home page, which seems normal now to us, was 100% opposite to what we were learned to see before (we used monster pages like Yahoo!, MSN).
Also, there is one big reason why I think that in long term Google will do better (although I believe they take more risky approach). They have more open-minded business model. In mentioned GMail, they gave me everything I wanted. For free. I used their system as my spam filter. No revenue for them. But in the long term, that payed off (I use their web interface regularly now). They are not greedy in that short-sighted manner like Apple is. They seem feature friendly to the user.
Apple is old business done right. Google is new business (note that I did not say that this is necessarily "done right").
I'm not a real expert, but I had some experience in systems that are not "hard real-time".
I can't recall exact definitions, but there are "soft" and "hard" real-time systems. In soft systems you can miss some deadlines. Like in video game, where you don't want to skip the frame, but from time to time that happens and its not a big deal.
Some very expensive systems are soft real-time. For instance, AGC - which is basically fine-tuning of power system's frequency (to keep it 50 or 60 Hz) is not hard real time. In our system, we issued commands in every 4 seconds. It was not big deal it we were late with our command for even a whole second. System would accumulate the error and it would be corrected the next time.
If the sailing is a process that is slow enough and if its actuators do not require precise timing, you can live with Matlab quite well. Simply, some processes are very 'forgiving', i.e. they are real-time in very vague terms. Even the most unpredictable systems (like Windows + Java interpreter + + Matlab + system coded in Matlab) can be used in such situations.
Country typically known as Yugoslavia fell apart in 1991-1992, but new country consisting only of Serbia and Montenegro continued to call itself Yugoslavia (Federal Republic of) until 2003. In 2003, it finally changed its name to far more suitable "Serbia and Montenegro".
Hence, we may say that
From American point of view, things look a bit different. USA did not recognize name Yugoslavia for union of Serbia and Montenegro. But in 2000, after FRY reapplied for the membership in the United Nations, USA accepted that name.
When FR Yugoslavia changed its name to Serbia and Montenegro,
Old
We tried to do this in southern England. Worked great till October. Then we had to send our technician every couple of days to replace the accumulator.
Strange thing that accumulator seemed to be 100% full all the time during the summer, so we thought that it would be able to survive at least the fall if not the winter.
I had their laptop. After some time, its transformer stopped working. I live in Serbia, and it is a bit tricky to get decent technical support/service here, but Sony has huge store in Belgrade downtown.
I went there, but no luck. They do not sell laptops in Serbia (mine was brought from UK), so they gave me the telephone of one repair shop, but they were not sure if they could help me. Repair shop sent me to another repair shop, and so on... After three hops, they explained me what's the issue. Sony has very rigid standards for their repair shops. To be their certified repairmen, you have to guarantee that you'll solve all problems in 24 hours. They were not able to find anyone capable of that in Serbia, so they don't have any repair shop in Serbia.
That's very interesting policy. Instead to give second class service to your customers, you give them - none.
I have never really understood the idea behind the automatic counting or automated voting system.
Here in Serbia, where we had a lot of problems with the elections, the voting itself and counting are the least problem. We had exactly the same problem as USA (i.e. corrupted legal system) but the voting procedure itself was never an issue.
Manual counting takes only couple of hours even for the largest poll stations. Summing the results takes exactly the same time everywhere. Time for summing the results is so larger than the process of counting, so it is plain stupid to try to reduce the time spent on counting. It takes couple of hours to get estimated results, and you have to wait till morning if you have close elections. No voting machine will solve this issue.
Manual counting has a lot of advantages - since you get paper trail by the very definition of the process. (I speak about process where you take you pen and then you circle the name of the wanted candidate/party.)
I live in the country (Serbia) that used to have rampant percentage of illegal software.
Before the democracy arrived here in October 2000, there was about 99.9% of illegal software. There was no official distributors of the software; nobody was interested in suing the violators... Some companies tried to legalize their server software when they created Internet sites.
What was the result:
* There was no locally created mass software (like text processor or something alike), only software that required maintenance could be developed in such situations
* There was no diversity (take into account that Serbia the population of only 8.000,000). In late 80's, everyone used Novel netware (even the smallest companies) with Clipper for database work
* Similarly, now everyone uses MS Windows and its networking "capabilities"
Linux won its battle here in early Internet days, because there was fear that publicly exposed MS Windows web server will create MS's attention. UNIX boxes were too expensive - so typical solution in our ISP's was Linux, and it still is.
Meanwhile, software tools for programming are far more diverse now, because there is strong outsourcing industry here. Still, for local web sites, PHP is some kind of standard.
Just couple of typical uses: for sending someone's phone number or address or driving instructions; for various confirmations (like "i did exam ok", "i'l b l8 10min"); to pay car parking; to send non-urgent messages to someone who's at the office; to send urgent message someone (faster than email); to send message and to be sure if he has received it; to see how much money you have on your banking account; to cheat in school; to call someone to turn skype on (esp. useful if that person lives abroad); to contact friends while commuting using public transportation...
Actually, solar is very good for the grid.
It is reasonable to assume that solar won't match 100% of our needs for electricity any time soon. Maximal power consumption is during the day (i.e. not night). You have to have enough resources for your peak consumption; ideal case from the grid's point of view would be to have constant flow of energy 24h a day.
Since solar cells can (in theory) cover that day-time increase in power demand, and even better, they produce energy exactly where it is consumed, it is a perfect way to keep load on high voltage lines and transformers constant.
And even even better, max demand in USA is for air conditioning, which is highest during the sunny days.
1) Write "200 000 000 000 USD" on the paper. .txt file /. how big financial disaster you've made, and how you've saved your ass
2) Type what's on the paper into a
3) Save the file
4) Delete the file
5) Empty the recycle bin
6) Recreate file by retyping data from the paper
7) Post the story on the
I do something very similar.
If I want to go to some site which is not in my bookmarks, story goes like this. I launch Firefox. I get Google page. Focus is already in the Google instead to be at URL field. If I type name there, I dont have to move to URL field and I can simply hit Enter. If I mistype the name, Google will correct me. If I decide to type in URL field, I would have to change the focus, if I miss the name I will have to try again etc... It's much simpler to let Google to take care of the correct name and TLD.
In the original book they are aliens, not man-made robots.
If you speak about limeses, then it depends how you go toward some value (toward 0 in this case).
For instance, both functions f1(x)=sin(x) and f2(x)=x are 0 for x = 0, but
lim x->0 (sin(x)/x) = 1, as we know.
If you take function like f1(x) = x*sin(x) and other one f2(x) = x then
lim x-> f1(x)/f2(x) = 0.
In these two cases, "0/0" have different values.
When you use division in limeses, the path you take is important, i.e. functions that describe in which way you go toward 0. That's why other posters mentioned continuity and other stuff related to functions, and not related to numbers.
Big breakthrough would be to solve lim x->0 f1(x)/f2(x) for f1(x) = 0, f2(x) = 0.
In Serbian, Pluto is called "Pluton" (just like Plato is called "Platon") and this is because it really ends with an "n" in original Greek, so this name will create additional problems.
Amount of money spent on war in Iraq would probably lead to some significant breaktroughs in alteranative fuel. Ironically, that war even increased the price of oil.
Russian adjectives do not end with -an, like they do in Serbian. They have to end on -oy or -iy.
I've spent two months in Michigan this year, and I find the state of highways in USA disastrous. I've heard that Eisenhower saw that German roads after the war, and they made US system after them... I guess that state of USA highways system would be much better if their model was German autobahn system *before* the war and all the bombing...
So it fits to "trust is good, control is better" scheme.
Refractors, of course, could be easily spotted from the Earth with appropriate equipment (laser and mid-size telescope).
Wait a minute, you know that these are from ASP, and you don't know that they are used in JSP... What tool you might be using then?