At WOT, most systems I know of revert to open loop, aim for about 12:1, and run muscle-car rich at WOT. The clean air regs actualy don't apply to WOT (at least in the states), and starting somewhere between 50% and 75% throttle position, the engines go into enrichment mode, and flood the cylinders with fuel.
This is because the compression ratio of the engine, coupled with the timing, would cause the engine to predetonate heavily at WOT if they weren't running rich to cool off the cylinders.
Atomization of the rich load of fuel cools the cylinders considerably.
This is why engines "knock". They get lean, at which there's not enough fuel atomization to cool the cylinders, and that oxygen-rich cylinder gets too hot and explodes instead of a controlled burn initiated by the spark-plug.
Direct injection diesel is so much a better system...
Usually, an engine runs the most efficiently at full throttle. But that's hp/fuel efficiency, not mpg efficiency.
The aerodynamics of the vehicle, the type of tire, and the efficiency of the engine, coupled with the gearing all come into play.
But for practical purposes, lowest rpm in the highest gear is usually the best mpg, but not always.
if you go too low in rpm, the engine may be very inefficient from an hp/fuel standpoint (usually about where it starts "lugging"), and needs to be operated at a higher rpm.
Then turbo vs. non-turbo enters in as well. If you go too low in rpm with a turbo (especially a diesel) you won't be generating enough boost to get efficient engine operation. A little boost is good, a lot is overkill.
But then, with a diesel, you can lean out the engine until you're not putting in any fuel at all, because it can't run too lean. Do that with a gasoline engine, and it'll blow up (cylinder temps get too high without the atomization of the fuel to help cool the cylinder prior to the combustion of the fuel).
No, the HP developed by an engine at a given rpm is dependent on the amount of fuel/air that you're feeding it.
So, while the engine may be able to develop 50hp at 2000rpm and 150hp at 3000rpm, at full throttle, at half throttle, it's developing less.
And the amount it develops at part throttle depends on a great number of factors.
Optimizing a car for highway mileage involves picking the best speed, tire rolling resistance, wind resistance, gear ratios, and part throttle torque curves for various engine configurations.
You actually want the rpm that will provide the greatest efficiency for the hp that you need to use to maintain your speed.
My 285hp Z has it's torque peak somewhere north of 4000 rpm. It gets it's best mileage down around 2000 rpm.
This is because it doesn't take 285 hp to keep it steady at 75mph on the highway. Instead, it probably takes 100hp. And the engine can easily deliver that at part throttle at low rpms.
The torque curve usually given is at wide open throttle, and driving at the torque peak would be correct for maximum efficiency of driving at wot. But you rarely NEED to do that.
Nope, SVN does something similar, but different, with the file-system-based backend.
SVN versions the entire repository with a single version, while CVS versions just a file, and that results is a fairly large fundamental shift in how stuff is stored and tracked.
I recommend you go read the free O'Reiley book on SVN.
Aside from the access mechanism on top, really, what's the difference? I've used both (OODBs heavily), and really, I've always looked at it as a bunch of tables with columns for member variables and rows for objects.
Is it really all that different under the hood? Or is this more marketing hype/spin?
And a large number of people can see it flicker (myself included), which is (one reason) why office buildings now are using high frequency electronic balasts in their flourescant lights (beleive it's an OSHA req).
I can see a monitor redraw at anything 75hz, and even then I sometimes catch it, depending on the phosphors.
It's one of the main reasons I want a digital display. The only advantage I see to an analog display, currently, is the ability to change display modes. Any then, you're still stuck with the limitation of the size/orientation of the phosphor gride for how well the picture is resolved.
My solution is to not go to best buy but to a reputable audio/home theatre store. Maybe cost a bit more, but they usually know what they're talking about.
In the South Bay, I use Bay Area Audio. Carefully setup systems there, with options from "affordable" HDTV through to $50K projector systems.
I grew up in the midwest, and comfortably drive on icey roads. A first-rain-of-the-season (october or so) on fresh blacktop here in Silicone Valley? worse than black ice.
I tend to drive a lot in 4wd in my truck on those occaisions. So slick that 4wd is actually "safe" for the drivetrain.
But it usually clears up after one or two good hard rains.
Many oils (including better ones like Mobil1) will lose as much as 25% of their volume/mass by boiling off when the engine is run hard and hot. Highway driving in modern, lean-burning engines qualifies. Summer driving in the desert more than qualifies.
The boiled off vapor is caught by the PCV system (as well as the blow-by gasses that it captures), and then is burnt by the engine. Usually leading to carbon deposits in the engine.
Re:I'm sticking with 5 1/4 inch floppies
on
Blu-Ray vs. HD-DVD
·
· Score: 1
One of my friend's owns a dvd rental store. He's invested in a DVD polisher, and will polish out the scratches of his customers's disks (as well as reducing the number of DVDs he loses to bad customers).
Works very well. Might want to poke around the various non-chain rental places in your area, and see if anyone offers anything like that.
SATA2 is allowing port multipliers. Which allows a fair number (possibly 15, don't remember) of drives per port on the controller.
But you get the same problem you do with SCSI. Sure, you can hang 15 devices on that 320MBps bus, but you can only push 320MBps of data through it. With SATA (and SAS) you get the full 150MBps per drive, which means that when you saturate your SCSI 320 bus at 3-5 drives or so, a 6- or 8-port controller can keep scaling up in bandwidth.
Add in the new per-port throughput specs for SATA2, and the port multipliers, and you've got a LOT more bandwidth than SCSI has ever had (aside from fibre, which is a whole different beast).
I would really like to see a municipal data grid. Run the fiber to the houses, and then lease the grid space to the ISPs, Telcos etc, which then we purchase the services we want for them. Base the grid on the local needs of the community.
This also would help ensure that rural parts of a county get the same services as the more heavily populated parts of the county. If the county has to provide access for all, then it's going to do so, instead of Comcast or SBC looking at the more remote areas and ignoring them.
I have dial-up. Its my only option (26K or maybe ISDN, if I felt like paying through the nose). I'm 2 miles out from the end of the line for DSL, and while we have digital cable, no cable modems within 20 miles.
Comcast has been dragging their feet heavily on the installation of the upgraded system to bring us cablemodems. Claiming it'll be on next month for almost 2 years now.
Our local water and roads are well maintained, and well serviced, and problems are handled quickly. SBC and PG&E are slow as hell to deal with problems on their poles/wires. SBC is much worse than PG&E, too. It's sad when Caltrans has a faster response time than PG&E...
Unfortuantely, not that I'm aware of. That's the main beef I have with Linux (and the hardware vendors). Drivers are based on what's actually in the device, and that's kinda kept hidden. It took me a while to figure out that I didn't have the prism chipset, but the Atheros chipset.
But once I figured that out, the mad-wifi drivers for the atheros chipset worked great.
the netgear cards are supported via mad-wifi (emerge search mad-wifi). The don't get turboG (2 bonded 802.11g bands), but they do get full g speeds of 54Mbps.
The mad wifi drivers are well supported by the gentoo users' forum, too. Search there for mad-wifi and you should find some good info on setup for multiple environments and the like.
Easiest way to get up and running with manually configuring a kernel is to run genkernel, and then running make menuconfig. Genkernel gives you a basic set of stuff/options, and then notes what modules are loaded in memory and uses to those to ensure that the resultant kernel will boot the box.
Once in menuconfig, you'll find that each kernel option has some descriptive help-text. Well, a lot of them do, and they tend to include statements like "if you don't know, choose Y".
It takes a while to go through it all, especially if you've not done it before (took me about 2 hours the first time to go through it all), but if you sit down and get a feel for the structure of the options in the menu, it's a lot easier later. Especially when you need to turn on some option (although if you know the option name, then 'vi/usr/src/linux/.config' is the best way to do it).
Yes. In the Cell model, you design your code in "cells". A cell is a clump of code and data that's copied to the SPE's local memory. The code then runs, streaming in additional data from memory, and using the local memory as a workspace.
This is, essentially, reconfigurable computing. Something that's never quite made it to market, by because the time that the FPGAs-type hardware was cheap enough to do it, general purpose cpus were faster again.
But this looks like an excellent cross-breed. Instead of flashing an FPGA/DSP and throwing data at it, instead just download some microcode into the instruction ram of the cell, and then tell it where to find the input and output streams, and have at it.
Depending on the size of the stream execution code in the cell, you could really do some amazing things in applcation servers with something like this (like using a series of cells to do SAX and XSLT transforms on data in realtime).
The key to usefullness for this, though, is management interface for the stream processors. Are they I/O entities? Are they managed by the compiler? the OS? How fast do they context switch, and if slow, how do you manage the proper allocation of them?
Watch Windows 2010 or Gnome/KDE use half of them for rendering the UI....
It may surprise you to learn that the genetics of domesticated dogs are nearly indistinguishable from that of wolves
They've supposedly been declared the same species as well (also including coyotes, IIRC).
However, with breeding dogs they have been essentially cloning, and many dog breeders are proud of the fact that they can produce a line of dogs that are almost identical from a genetic point of view. Which scares me to death because instead of cloning, theyre reinforcing recessives, and bad stuff like hip dysplasia is the result. Cloning would be safer.
Balanced signals only require 2 wires, all current passes through each wire, not through ground. the third wire is usually shield/ground, but it's not really necessary.
Unbalanced signals only require 1 wire, the signal, which is referenced to ground. But, ground is never really ground, it's an ugly thing.
If you disconnect the "ground" of an unbalanced RCA jack, you'll still get audio, just much noisier (it has to fall back on the common ground of the mains ground (or neutral, if two-prong plugged).
With a balanced signal, if you remove one of the two signal wires, you don't get anything at all. Nothing is referenced to ground.
Balanced pair A transmission line in which the two conductors are electrically identical and symmetrical with respect to a common reference point, usually earth.
Unbalanced pair A transmission line in which the voltages on the two conductors are unequal with respect to earth.
http://www.wavecor.co.uk/gloss.htm
Twisted pair is used to ensure that all intereference is picked up equally by both wires, thereby making it invisible when the difference between the wires is measured.
Since speakers respond to the voltage difference between the wires, and all current flows through both wires, and isn't reference to ground, they're differential, and balanced.
However, speaker cables aren't unbalanced. They are balanced/differential by nature. You have send and receive on separate wires, but there is no ground.
interconnects, on the other hand, *NEED* good shielding, or need to be balanced/differential. Low current, very high input impedances, and very suceptable to noise.
Slashdot Mirror
Except at WOT.
At WOT, most systems I know of revert to open loop, aim for about 12:1, and run muscle-car rich at WOT. The clean air regs actualy don't apply to WOT (at least in the states), and starting somewhere between 50% and 75% throttle position, the engines go into enrichment mode, and flood the cylinders with fuel.
This is because the compression ratio of the engine, coupled with the timing, would cause the engine to predetonate heavily at WOT if they weren't running rich to cool off the cylinders.
Atomization of the rich load of fuel cools the cylinders considerably.
This is why engines "knock". They get lean, at which there's not enough fuel atomization to cool the cylinders, and that oxygen-rich cylinder gets too hot and explodes instead of a controlled burn initiated by the spark-plug.
Direct injection diesel is so much a better system...
balance between rpms and throttle position.
Usually, an engine runs the most efficiently at full throttle. But that's hp/fuel efficiency, not mpg efficiency.
The aerodynamics of the vehicle, the type of tire, and the efficiency of the engine, coupled with the gearing all come into play.
But for practical purposes, lowest rpm in the highest gear is usually the best mpg, but not always.
if you go too low in rpm, the engine may be very inefficient from an hp/fuel standpoint (usually about where it starts "lugging"), and needs to be operated at a higher rpm.
Then turbo vs. non-turbo enters in as well. If you go too low in rpm with a turbo (especially a diesel) you won't be generating enough boost to get efficient engine operation. A little boost is good, a lot is overkill.
But then, with a diesel, you can lean out the engine until you're not putting in any fuel at all, because it can't run too lean. Do that with a gasoline engine, and it'll blow up (cylinder temps get too high without the atomization of the fuel to help cool the cylinder prior to the combustion of the fuel).
No, the HP developed by an engine at a given rpm is dependent on the amount of fuel/air that you're feeding it.
So, while the engine may be able to develop 50hp at 2000rpm and 150hp at 3000rpm, at full throttle, at half throttle, it's developing less.
And the amount it develops at part throttle depends on a great number of factors.
Optimizing a car for highway mileage involves picking the best speed, tire rolling resistance, wind resistance, gear ratios, and part throttle torque curves for various engine configurations.
Close, but not quite right.
You actually want the rpm that will provide the greatest efficiency for the hp that you need to use to maintain your speed.
My 285hp Z has it's torque peak somewhere north of 4000 rpm. It gets it's best mileage down around 2000 rpm.
This is because it doesn't take 285 hp to keep it steady at 75mph on the highway. Instead, it probably takes 100hp. And the engine can easily deliver that at part throttle at low rpms.
The torque curve usually given is at wide open throttle, and driving at the torque peak would be correct for maximum efficiency of driving at wot. But you rarely NEED to do that.
Price difference. Perforce was simply not an option for my small company. Subversion, on the other hand, is just as easy on the pocket-book as CVS.
Nope, SVN does something similar, but different, with the file-system-based backend.
SVN versions the entire repository with a single version, while CVS versions just a file, and that results is a fairly large fundamental shift in how stuff is stored and tracked.
I recommend you go read the free O'Reiley book on SVN.
(this is serious)
Aside from the access mechanism on top, really, what's the difference? I've used both (OODBs heavily), and really, I've always looked at it as a bunch of tables with columns for member variables and rows for objects.
Is it really all that different under the hood? Or is this more marketing hype/spin?
And a large number of people can see it flicker (myself included), which is (one reason) why office buildings now are using high frequency electronic balasts in their flourescant lights (beleive it's an OSHA req).
I can see a monitor redraw at anything 75hz, and even then I sometimes catch it, depending on the phosphors.
It's one of the main reasons I want a digital display. The only advantage I see to an analog display, currently, is the ability to change display modes. Any then, you're still stuck with the limitation of the size/orientation of the phosphor gride for how well the picture is resolved.
My solution is to not go to best buy but to a reputable audio/home theatre store. Maybe cost a bit more, but they usually know what they're talking about.
In the South Bay, I use Bay Area Audio. Carefully setup systems there, with options from "affordable" HDTV through to $50K projector systems.
I grew up in the midwest, and comfortably drive on icey roads. A first-rain-of-the-season (october or so) on fresh blacktop here in Silicone Valley? worse than black ice.
I tend to drive a lot in 4wd in my truck on those occaisions. So slick that 4wd is actually "safe" for the drivetrain.
But it usually clears up after one or two good hard rains.
THE best monosylabic line/grunt I've ever heard.
Obviously, you don't have a 100+yo house with thick hardwood floors...
Addams Family is my all-time favorite machine. So much fun to play.
Many oils (including better ones like Mobil1) will lose as much as 25% of their volume/mass by boiling off when the engine is run hard and hot. Highway driving in modern, lean-burning engines qualifies. Summer driving in the desert more than qualifies.
The boiled off vapor is caught by the PCV system (as well as the blow-by gasses that it captures), and then is burnt by the engine. Usually leading to carbon deposits in the engine.
One of my friend's owns a dvd rental store. He's invested in a DVD polisher, and will polish out the scratches of his customers's disks (as well as reducing the number of DVDs he loses to bad customers).
Works very well. Might want to poke around the various non-chain rental places in your area, and see if anyone offers anything like that.
If you have an addictive personality, anything can be addictive and ruin your life.
SATA2 is allowing port multipliers. Which allows a fair number (possibly 15, don't remember) of drives per port on the controller.
But you get the same problem you do with SCSI. Sure, you can hang 15 devices on that 320MBps bus, but you can only push 320MBps of data through it. With SATA (and SAS) you get the full 150MBps per drive, which means that when you saturate your SCSI 320 bus at 3-5 drives or so, a 6- or 8-port controller can keep scaling up in bandwidth.
Add in the new per-port throughput specs for SATA2, and the port multipliers, and you've got a LOT more bandwidth than SCSI has ever had (aside from fibre, which is a whole different beast).
I would really like to see a municipal data grid. Run the fiber to the houses, and then lease the grid space to the ISPs, Telcos etc, which then we purchase the services we want for them. Base the grid on the local needs of the community.
This also would help ensure that rural parts of a county get the same services as the more heavily populated parts of the county. If the county has to provide access for all, then it's going to do so, instead of Comcast or SBC looking at the more remote areas and ignoring them.
I have dial-up. Its my only option (26K or maybe ISDN, if I felt like paying through the nose). I'm 2 miles out from the end of the line for DSL, and while we have digital cable, no cable modems within 20 miles.
Comcast has been dragging their feet heavily on the installation of the upgraded system to bring us cablemodems. Claiming it'll be on next month for almost 2 years now.
Our local water and roads are well maintained, and well serviced, and problems are handled quickly. SBC and PG&E are slow as hell to deal with problems on their poles/wires. SBC is much worse than PG&E, too. It's sad when Caltrans has a faster response time than PG&E...
Unfortuantely, not that I'm aware of. That's the main beef I have with Linux (and the hardware vendors). Drivers are based on what's actually in the device, and that's kinda kept hidden. It took me a while to figure out that I didn't have the prism chipset, but the Atheros chipset.
But once I figured that out, the mad-wifi drivers for the atheros chipset worked great.
the netgear cards are supported via mad-wifi (emerge search mad-wifi). The don't get turboG (2 bonded 802.11g bands), but they do get full g speeds of 54Mbps.
/usr/src/linux/.config' is the best way to do it).
The mad wifi drivers are well supported by the gentoo users' forum, too. Search there for mad-wifi and you should find some good info on setup for multiple environments and the like.
Easiest way to get up and running with manually configuring a kernel is to run genkernel, and then running make menuconfig. Genkernel gives you a basic set of stuff/options, and then notes what modules are loaded in memory and uses to those to ensure that the resultant kernel will boot the box.
Once in menuconfig, you'll find that each kernel option has some descriptive help-text. Well, a lot of them do, and they tend to include statements like "if you don't know, choose Y".
It takes a while to go through it all, especially if you've not done it before (took me about 2 hours the first time to go through it all), but if you sit down and get a feel for the structure of the options in the menu, it's a lot easier later. Especially when you need to turn on some option (although if you know the option name, then 'vi
Yes. In the Cell model, you design your code in "cells". A cell is a clump of code and data that's copied to the SPE's local memory. The code then runs, streaming in additional data from memory, and using the local memory as a workspace.
This is, essentially, reconfigurable computing. Something that's never quite made it to market, by because the time that the FPGAs-type hardware was cheap enough to do it, general purpose cpus were faster again.
But this looks like an excellent cross-breed. Instead of flashing an FPGA/DSP and throwing data at it, instead just download some microcode into the instruction ram of the cell, and then tell it where to find the input and output streams, and have at it.
Depending on the size of the stream execution code in the cell, you could really do some amazing things in applcation servers with something like this (like using a series of cells to do SAX and XSLT transforms on data in realtime).
The key to usefullness for this, though, is management interface for the stream processors. Are they I/O entities? Are they managed by the compiler? the OS? How fast do they context switch, and if slow, how do you manage the proper allocation of them?
Watch Windows 2010 or Gnome/KDE use half of them for rendering the UI....
It may surprise you to learn that the genetics of domesticated dogs are nearly indistinguishable from that of wolves
They've supposedly been declared the same species as well (also including coyotes, IIRC).
However, with breeding dogs they have been essentially cloning, and many dog breeders are proud of the fact that they can produce a line of dogs that are almost identical from a genetic point of view. Which scares me to death because instead of cloning, theyre reinforcing recessives, and bad stuff like hip dysplasia is the result. Cloning would be safer.
inline is your friend.
I'm an EE.
Speaker cables are balanced.
Balanced signals only require 2 wires, all current passes through each wire, not through ground. the third wire is usually shield/ground, but it's not really necessary.
Unbalanced signals only require 1 wire, the signal, which is referenced to ground. But, ground is never really ground, it's an ugly thing.
If you disconnect the "ground" of an unbalanced RCA jack, you'll still get audio, just much noisier (it has to fall back on the common ground of the mains ground (or neutral, if two-prong plugged).
With a balanced signal, if you remove one of the two signal wires, you don't get anything at all. Nothing is referenced to ground.
Balanced pair
A transmission line in which the two conductors are electrically identical and symmetrical with respect to a common reference point, usually earth.
Unbalanced pair
A transmission line in which the voltages on the two conductors are unequal with respect to earth.
http://www.wavecor.co.uk/gloss.htm
Twisted pair is used to ensure that all intereference is picked up equally by both wires, thereby making it invisible when the difference between the wires is measured.
Since speakers respond to the voltage difference between the wires, and all current flows through both wires, and isn't reference to ground, they're differential, and balanced.
However, speaker cables aren't unbalanced. They are balanced/differential by nature. You have send and receive on separate wires, but there is no ground.
interconnects, on the other hand, *NEED* good shielding, or need to be balanced/differential. Low current, very high input impedances, and very suceptable to noise.