Adding more ram for a disk cache is a simpler (and often lower power) solution to speed up disk activity. Not if your hard drive is switched off (remember this is laptops we are talking about). It takes quite a while and a lot of power for a hard drive to spin up. You can get data from a flash chip within micro secs of switching it on.
Writing to flash takes power, leaving the flash on [so you can access it] takes power. The whole point with flash is that you do not need to leave it on. Once the data is written to it, you can switch it off until the data is needed. RAM needs to have some power (though not much when in standby) to keep the data in it active.
Why is this news? I would have thought every large cold store would be doing this already due to the difference in price of electricity. You would have thought somebody would have thought of this before. Its exactly the same principle as night storage heaters (though with cooling rather than heating) so its not exactly a major idea.
Most of the sensors have a plastic "light guide" in front of them that breaks the sensed area into zones.
Its not a light guide its a plastic fresnel lens with multiple elements which focuses light (actually heat) from various "zones" onto the sensor.
It is the changing difference between the zones that triggers the sensor.
Nope. The sensor is made from two seperate pyroelectric elements which are mounted side by side. It is differences between these two elements which triggers the device. This could be from the same zone or different zones. Sun light and other ambient light (heat) changes will affect both elements equally (you hope) so that they don't trigger the device.
Try taking one of them apart and you'll see either variations in the lens plastic, or even a set of physical baffles between the outer filter and the sensor itself.
(You can actually walk by most IR sensors without setting them off if you move VERY slowly, which is why better quality alarm systems use radar or specific thermal level monitoring rather than just a change).
Which brings us to aiming. Most of the time the zones are arranged to be more sensitive to side-to-side motion than up/down.
The are all like this due to them being two element devices.
So if you have one oriented 90deg out of "true" then it'll be rather insensitive except in a narrow band. (This is a good way to limit the area of coverage of a sensor without having to break out the masking tape).
True.
Speaking of which, the height and angle of the sensor makes a big difference for the same reason.
So I would recommend taking one apart, figuring out the zone layout and adjusting accordingly. (Heck, you can even just set one on a table and see what area it "sees" and how sensitive it is to motion in that area, then turn it 90deg and try again).
The biggest difference between the systems you can buy is the shape of the fresnel lens. You can have just one main zone or lots of sub zones or a combination of both. Most good systems will give you a diagram of the size and position of the zones which you can use to choose and position them.
100 microsecond switch speed is very very slow for modern transistors (mentioned in article). What am I missing here? Is there a mistake in the article?
They are a lot more clever than you think they are. The qualification event was all about avoiding obstacles that were in the way and had sections with no GPS coverage.
A couple of teams are using stereo cameras to find there way around but the vast majority are using SICK scanning laser range finders. They show you where things are over short distances which enables you to avoid obstacles at low speeds. Red Team are also using radar to be able to detect obstacles at greater distances to enable higher speeds. Unfortunately, it doesn't pick up everything. However data fusing everything together (GPS, INS, Radar, Lidar + others) allows you to move at modist speeds using current tech. Luck is always useful but technology is what is being used today.
I think someone whos website ends with freeserve.co.uk should not be throwing stones.
If you are a company that has a common enough name that the.com and.co.uk had already been snapped up (in 1996) then a.uk.com address is the best alternative.
Redirecting *.uk.com is not a good idea though. Hopefully they will reconsider.
Slashdot Mirror
Exactly. If you're taking the trouble to memorize six digits why not "3 1 4 1 5 9".
Because 113355 is a lot easier to remember than 3.14159 and because it is more accurate.
355/113 is 3.14159292 where as pi is 3.141592654 an error of 0.000000266
If you want a good approximation to pi then try 355/113. (remember it as 113355)
AVG throws a wobbly on synchroplastikum stating that there is a Trojan in it.
Only 42 installed so far. They are looking for donations to complete the array.
Older story on this here: http://hardware.slashdot.org/article.pl?sid=06/09/ 26/1937237
Sure would be nice to have a play with it once they have worked out how to program it...
Not very exciting but the Beeb has a video here
First google link: Published Monday, October 31, 2005 6:41 PM by astebner
Second google link: Posted February 14th, 2006
Third google link: Last Review : August 17, 2006
Fourth google link: Friday, January 28, 2005 1:00 AM PST
Fifth google link: June 2nd, 2006
You get the idea....
Adding more ram for a disk cache is a simpler (and often lower power) solution to speed up disk activity.
Not if your hard drive is switched off (remember this is laptops we are talking about). It takes quite a while and a lot of power for a hard drive to spin up. You can get data from a flash chip within micro secs of switching it on.
Writing to flash takes power, leaving the flash on [so you can access it] takes power.
The whole point with flash is that you do not need to leave it on. Once the data is written to it, you can switch it off until the data is needed. RAM needs to have some power (though not much when in standby) to keep the data in it active.
Why is this news? I would have thought every large cold store would be doing this already due to the difference in price of electricity. You would have thought somebody would have thought of this before. Its exactly the same principle as night storage heaters (though with cooling rather than heating) so its not exactly a major idea.
2000 ((cubic meters) per day) = 117409.801 hogshead per fortnight
According to Google that is.
I do love Googles conversion function though. I didn't think it would work that one out OK but it did.
Most of the sensors have a plastic "light guide" in front of them that breaks the sensed area into zones.
Its not a light guide its a plastic fresnel lens with multiple elements which focuses light (actually heat) from various "zones" onto the sensor.
It is the changing difference between the zones that triggers the sensor.
Nope. The sensor is made from two seperate pyroelectric elements which are mounted side by side. It is differences between these two elements which triggers the device. This could be from the same zone or different zones. Sun light and other ambient light (heat) changes will affect both elements equally (you hope) so that they don't trigger the device.
Try taking one of them apart and you'll see either variations in the lens plastic, or even a set of physical baffles between the outer filter and the sensor itself.
(You can actually walk by most IR sensors without setting them off if you move VERY slowly, which is why better quality alarm systems use radar or specific thermal level monitoring rather than just a change).
Which brings us to aiming. Most of the time the zones are arranged to be more sensitive to side-to-side motion than up/down.
The are all like this due to them being two element devices.
So if you have one oriented 90deg out of "true" then it'll be rather insensitive except in a narrow band. (This is a good way to limit the area of coverage of a sensor without having to break out the masking tape).
True.
Speaking of which, the height and angle of the sensor makes a big difference for the same reason.
So I would recommend taking one apart, figuring out the zone layout and adjusting accordingly. (Heck, you can even just set one on a table and see what area it "sees" and how sensitive it is to motion in that area, then turn it 90deg and try again).
The biggest difference between the systems you can buy is the shape of the fresnel lens. You can have just one main zone or lots of sub zones or a combination of both. Most good systems will give you a diagram of the size and position of the zones which you can use to choose and position them.
Just Google it
Its not all that difficult...
100 microsecond switch speed is very very slow for modern transistors (mentioned in article). What am I missing here? Is there a mistake in the article?
If you want something hard then try a 20x20x20 cube
http://www.speedcubing.com/chris/20cube.html
Dev kits for the 6" display can be pre ordered for $3000. I guess they will come down once production starts.
Having actually seen an e-ink display some years ago, I was very impressed. Can't wait to actually be able to buy one for a sensible price.
Well cool. Thanks.
There was a 10 mile error in the data from the start. Darpa corrected it which made it jump back as you noted. It is believed that the current data is more accurate read the thread here: https://dtsn.darpa.mil/grandc/forum/topic.asp?topi c_id=1652&forum_id=30&Topic_Title=Post+Time!&forum _title=Grand+Challenge+Event&M=False&S=
They are a lot more clever than you think they are. The qualification event was all about avoiding obstacles that were in the way and had sections with no GPS coverage.
A couple of teams are using stereo cameras to find there way around but the vast majority are using SICK scanning laser range finders. They show you where things are over short distances which enables you to avoid obstacles at low speeds. Red Team are also using radar to be able to detect obstacles at greater distances to enable higher speeds. Unfortunately, it doesn't pick up everything. However data fusing everything together (GPS, INS, Radar, Lidar + others) allows you to move at modist speeds using current tech. Luck is always useful but technology is what is being used today.
Route information is available here: http://redteamracing.org/index.cfm?method=page.dis play&page=Gc05.route&skin=popup
Can someone combine Google Maps with the XML here: http://www.grandchallenge.org/data/location.xml
I think someone whos website ends with freeserve.co.uk should not be throwing stones.
.com and .co.uk had already been snapped up (in 1996) then a .uk.com address is the best alternative.
If you are a company that has a common enough name that the
Redirecting *.uk.com is not a good idea though. Hopefully they will reconsider.
Hmm, thanks. Might give that a go. £1.50 is a great price.
My bad. i850 not i860. Great printer though, I've produced some great A4 prints from it.
Do you know what make the 3rd party cartridges were? The i860 at home is old enough now to risk putting in some ink which screws it up.