Thank you for an excellent post. I'm disappointed how few electrical engineers appear to be on slashdot anymore . . . radios and transmission lines aren't magic, people!
Umm, I'm not sure if you stopped following computers in the early 1980's, but modern computers due indeed use 32-bit wide "words" (new ones are even using 64-bit wide words!). If you went ahead and just made it so you could only access 32-bit "chunks" at a time (i.e. no "byte_enable" lines), you would still only have 4 giga-words of memory.
It would make things much slower, however, in that if you only wanted to modify 8-bits of a word, say, to just make the red channel of a 32-bit pixel = 135, you would have to do the following operations:
1) read the entire 32-bit word
2) perform an AND_immediate to blank out just that 8 bit section (say, ANDI 0xFFFFFF00)
3) perform an OR_immediate to load in just the new data (ORI 0x000000_data)
4) write the 32-bit word back
vs.
1) write the immediate value to that location with only that byte enabled
If you were to go ahead and make it addressable in 8-bit chunks, to avoid that mess above, you would be back where we are today =)
I actually worked on developing a printer for heavy-duty rubberized coatings (weird project)... Long story short, inkjet printers use piezo-jet technology to print which has a few limitations: 1) You can't actually print anything with a viscosity higher than (roughly) water, or it will instantly clog the jets. I would imagine clay platelets, even nano-sized, would not enjoy being shoved through a piezo-jet. Also, 2) the volumes they "print" are incredibly tiny . . . like nano-liter sized. To build up thickness on an industrial scale (like say a few mils thick, minimum) takes a prohibitively long time (maybe faster than their repeated-dipping technique, but still too slow to be useful). Maybe an "inkjet-like" system (we wound up using some miniature solenoids about ~.18" diameter).
You are making the assumption that all power is generated by coal, and that consumers typically pay in the 2-3c/kwh range. Generators that use natural gas and oil, at least here in California, drive the price during peak hours (i.e. when it's sunny) up to around 10-13c/kwh I believe. No one power source will be the solution to our problems, but using solar as a "peaking" generator, and then using something like nuclear as the base load would likely work okay without being unbearably expensive.
Combine this and one of the new E-ink ebook readers, make it pretty rugged, slap a solar panel on the back and man. . . you have something really close to a genuine hitchhiker's guide to the galaxy. Ah, I love where technology is heading =)
Re:Yes but what makes his little project special??
on
DIY Laptop
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· Score: 1
I would say it's probably because you didn't take pictures of your work and write it up, and then post it to a bunch of websites during what happened to be a lull in the news. It sounds like you did an amazing amount of work, but as one of my EE prof's told me, "It doesn't count unless you tell other people." That counts double if a lot of your neat features are still in the "idea" phase (an RTG?) This is certainly a silly project (I know, i'm the one who built it!), and it's not even done yet, but it was definitely a fun project and one in which most people can understand how it works.
On a separate note, about the autonomous submarine: Although it sounds like yours is really interesting, it probably generates less interest because nearly all big schools with engineering programs have autonomous submarine clubs. Here is my school's for instance:
http://www.uscrobotics.org/
In fact, the Association for Unmanned Vehicle Systems International (http://www.auvsi.org/) puts on a contest every year (I think they're in their 16th year or so) for unmanned submarines. I'm going to go out on a limb and assume that this is what your project is for? Anyway, best of luck with it!
As far as I understand it, it doesn't work nearly as well for heavier particles (I assume you are thinking protons?). Especially ones with a positive charge. The heavy mass of the protons compared to the electrons in the plasma cloud are what allows the "wakefield" to be created in the first place. When we model this stuff, the ions move so slowly compared to the electrons that we generally just assume that they are static for the duration of the beam passing through the oven (pico-femto second range). As I mentioned earlier, this will most likely always show up as an "afterburner" that goes at the end of a traditional linac.
I actually do some work on this with the PWFA group at USC (i'm an undergrad research assistant). It really is amazing! We can reach acceleration gradients of around 60 GeV/m, compared to something like 40 MeV/m for a normal accelerator. It works like this: 1. The electrons travel down the main linac in carefully spaced "bunches", and get accelerated to around 43 GeV over a course of ~3KM (this is at the main beam at SLAC). 2. A (in the last experiment) 1.2m long Lithium plasma "oven" is at the end of the beam, which the electrons are directed into. 3. The first, or "driving," bunch goes through the plasma, and repels all of the electrons it gets near, leaving an "empty" wake behind it, where only the positively charged ions are. 4. The positive charge behind the driving beam pulls it backwards, causing it to lose energy. At the same time, a "witness" bunch placed strategically within the wakefield gets pulled forward by the positively charged ions. The witness gains energy while the driver loses energy. 5. Voila! One bunch now has twice the energy, and one bunch now has none . ..or at least something close to that!
The main caveat is that you're upward-limited by your entering energy, so you still need a huge Linac to accelerate the bunches to begin with. This will likely get tacked on in the form of a "plasma afterburner" to a normal linac, such as in the setup at SLAC.
This is basically what the Picaxe microcontroller series was made for. Their website is at http://www.picaxe.co.uk/ and a reseller for them in the united states is located at www.phanderson.com. It is basically a PIC microcontroller (they use various models, from 8-pins to 40, so the scalability factor is there), with a custom ROM flashed onto them that has a BASIC interpreter. Think of a Parallax BASIC-STAMP, only all in one chip, and the chips range from $3-10 for most of them, so its almost as cheap as you can get it. Additionally, the BASIC software development environment is free to download, has no limitations, and is geared towards an academic setting (it even includes the ability to draw out simple logic circuits and have it convert them to basic code). Also, THEY DO NOT REQUIRE A SEPARATE PROGRAMMER. To program a PIC normally, you would need a ~$50-100 programmer for each student, but these hook directly up to the serial port (a cable is just 3 wires coming out of a DB9 connector), so each student can easily reprogram their own, or even do it from home. They're incredibly versatile (check out the forum at their main site), and perfectly suited to academic use, for both younger and older students
I'm a junior in Electrical Engineering, and I have a 49G+ and love it! For the first 2 years I had it, it had horrible problems, but they were all fixed by subsequent firmware updates and it's been absolutely awesome for the last 3 years I've had it. The HP-50G is completely backwards compatible with the 49G+, only it has a more traditional, rugged black case, and I hear the keyboard is a little better. The calculator has a 75 MHZ ARM processor (that you can program in C!), like 1.5MB of RAM, and an SD card slot for basically infinite storage. Additionally, it has built in libraries of constants (with units and everything) and a fairly large library of scientific and engineering applications for it.
I also have an original model TI-83 from 1996 that has been dropped and kicked and abused more than a soccer ball (complete with an embarrasingly large Pocket Monsters sticker on it from 7th grade), and it is still going strong.
Oh, and for those who don't know, at least on the newer HP calculators (like the 49G+ and 50G), you can switch between RPN (Reverse Polish notation) and Algebra mode (TI-83 style).
So your argument boils down to: "Women complain about being treated unfairly, and think they deserve to be treated fairly. Well if they are treating themselves so fairly, what is the problem?"
I'm sure the idea of genuine gender equality bothers you to no end, but it's so incredibly intellectually disingenius to say "If you're so equal, then quit bitching about us discriminating against you." As an electrical engineering student, the amount of shit most female engineering students have to put up with is almost staggering. We shouldn't pretend like there are suddenly no more problems just because a bunch of women took note of the situation and started complaining.
Using a plasma "afterburner" at SLAC, we were able to increase the energy of part of our beam from 43 GeV to ~100 GeV in the space of 1.2 meters. The main problem with all of this (plasma-wakefield particle accelerators as well) is getting high enough "current" to be useful. It is not that difficult to accelerate an electron or 2 up to that point, but to make a useful current is HARD. The absurdly short pulse durations necessary to create any kind of wakefield in the first place mean that 1) this is definitely beyond the reach of an undergrad (believe me, I am one, and I've looked into it), and 2) you still need a fairly large space and some fairly expensive equipment. We might get there someday, but we're not there yet.
I actually do some research in this area (Plasma-wakefield particle acceleration, really really similar), and one of the biggest problems is getting the pulse-width incredibly small. They have to use something called Chirp Pulse Amplification and I think the beam length is somewhere on the order of 1-2 picoseconds. From the article, the power delivered by this beam is about 40 TeraWatts, which gives you some sort of idea. The acceleration gradient might be really high, but that doesnt mean youre going to get a desktop version any time soon. The equipment necessary to get the timing (pulse-length and power) right is incredibly difficult and expensive at the moment.
Hey, at least in your comment about weight vs. volume in shipping costs, I would argue that you're fairly wrong. One of the largest "costs" is just the truck transporting itself, so if you can increase the density if goods on the truck, it saves money/resources/fossil fuels, etc. Try the following example: Moving 1000 ipods from a packaging center to a store. Using large packaging: say, 200 ipods can go per truck Using smaller packaging: 500 ipods per truck, but the truck's weight is also increased somewhat => large package=5 trips, not to mention the trucks are transporting more weight total (1000 ipods, plus more packaging)
smaller package= 2 trips, and less overall weight (though higher density)
The individual journey of the truck might burn more fuel, but there would be way fewer shipments and significantly less fuel burnt overall
I find it odd that many people have a knee-jerk reaction to defending any suggestion of government wrongdoing (most likely about as many as have a knee-jerk reaction to assume government wrongdoing). Why is it necessary to have an infallible government? No, not EVERYTHING the government does is evil or nefarious, but a lot of it is still wrong or misguided. The government is just made up of people, like everything else, and people tend to do lots of stupid and illegal stuff (especially Americans! Look at our incarceration rates!). Saying, "Well, the government wouldn't do anyting bad, so everyone should just shut up already" is a terrible attitude to take.
What, pray tell, is the difference between a "suspected terrorist" and an otherwise innocent citizen, if the courts have not decided they have done something wrong?
If they DO have enough probably cause to monitor them, why would it be difficult to get court approval?
There is actually a lot of active research going on in this field right now. It is called "Processor-in-memory" architecture, and it's best for handling things like array-based calculations, where you need to make a number of off-chip memory calls to complete. Staying completely on-chip makes it much faster, and it allows the embedded proc to take advantage of the internally wide (~256-bit) data path of modern memory. Look up Project DIVA and Project MONARCH, it is all DARPA-sponsored research, but the university I attend (USC) has a number of researchers involved with it.
I was under the impression that opening up the design of the UltraSPARC T1 was partly just to bolster interest in it (and it really is an incredible design from a hardware perspective) and partly just to allow people like EE and computer architecture students, along with hobbyists and engineers, to understand how it actually works at its most basic level. Although I realize i'm in the vast minority, as someone that actually DOES do microprocessor design in their spare time (I just completed my first working CPU design!), this is a really cool thing for them to do. I'm still learning verilog, but I would definitely like to look over some of their design docs and source sometime! I hardly think their goal is to get other people to build their own T1 processors though.
In a word: no. Wavelength*Frequency=Speed of wave. Propagation speed of a wave in a given medium is constant and solely dependant on the properties of that medium (in this case, Temperature and Pressure). Since speed of sound at STP is around 343 m/s, at 30 Hz, the wavelength will be much longer than it will be at 2975 Hz (2975/30 times faster, to be exact). As one goes up, the other goes down, but the speed is constant. If the speed was able to change, that simple relation would no longer mean anything...
Re:What if it's a "rush?"
on
The New Boom
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· Score: 1
They are probably just unemployed Unix sysadmins =)
http://www.ebookwise.com/ebookwise/ebookwise1150.h tm
I recently got one of these things and it's a great deal. It cost me around $100 (I think it's gone back up to $130 now), so it's not terribly expensive, and it only weighs about a pound or so. You can import your own texts to it (i.e. project gutenberg texts), it can use Smartmedia cards (up to 128mb), so you can store a LOT of books, and the batteries last for about 25 hours and can just be charged off of 12V dc. Hook up a small 12V solar panel to trickle-charge it and you've got yourself around 300+ books for ~$150 or so!
Slashdot Mirror
People like you are free to go live in a Libertarian Utopia like Somalia, where you'll promptly be robbed and killed, with no one to defend you =)
Thank you for an excellent post. I'm disappointed how few electrical engineers appear to be on slashdot anymore . . . radios and transmission lines aren't magic, people!
Umm, I'm not sure if you stopped following computers in the early 1980's, but modern computers due indeed use 32-bit wide "words" (new ones are even using 64-bit wide words!). If you went ahead and just made it so you could only access 32-bit "chunks" at a time (i.e. no "byte_enable" lines), you would still only have 4 giga-words of memory. It would make things much slower, however, in that if you only wanted to modify 8-bits of a word, say, to just make the red channel of a 32-bit pixel = 135, you would have to do the following operations: 1) read the entire 32-bit word 2) perform an AND_immediate to blank out just that 8 bit section (say, ANDI 0xFFFFFF00) 3) perform an OR_immediate to load in just the new data (ORI 0x000000_data) 4) write the 32-bit word back vs. 1) write the immediate value to that location with only that byte enabled If you were to go ahead and make it addressable in 8-bit chunks, to avoid that mess above, you would be back where we are today =)
I actually worked on developing a printer for heavy-duty rubberized coatings (weird project)... Long story short, inkjet printers use piezo-jet technology to print which has a few limitations: 1) You can't actually print anything with a viscosity higher than (roughly) water, or it will instantly clog the jets. I would imagine clay platelets, even nano-sized, would not enjoy being shoved through a piezo-jet. Also, 2) the volumes they "print" are incredibly tiny . . . like nano-liter sized. To build up thickness on an industrial scale (like say a few mils thick, minimum) takes a prohibitively long time (maybe faster than their repeated-dipping technique, but still too slow to be useful). Maybe an "inkjet-like" system (we wound up using some miniature solenoids about ~.18" diameter).
You are making the assumption that all power is generated by coal, and that consumers typically pay in the 2-3c/kwh range. Generators that use natural gas and oil, at least here in California, drive the price during peak hours (i.e. when it's sunny) up to around 10-13c/kwh I believe. No one power source will be the solution to our problems, but using solar as a "peaking" generator, and then using something like nuclear as the base load would likely work okay without being unbearably expensive.
Combine this and one of the new E-ink ebook readers, make it pretty rugged, slap a solar panel on the back and man. . . you have something really close to a genuine hitchhiker's guide to the galaxy. Ah, I love where technology is heading =)
I would say it's probably because you didn't take pictures of your work and write it up, and then post it to a bunch of websites during what happened to be a lull in the news. It sounds like you did an amazing amount of work, but as one of my EE prof's told me, "It doesn't count unless you tell other people." That counts double if a lot of your neat features are still in the "idea" phase (an RTG?) This is certainly a silly project (I know, i'm the one who built it!), and it's not even done yet, but it was definitely a fun project and one in which most people can understand how it works. On a separate note, about the autonomous submarine: Although it sounds like yours is really interesting, it probably generates less interest because nearly all big schools with engineering programs have autonomous submarine clubs. Here is my school's for instance: http://www.uscrobotics.org/ In fact, the Association for Unmanned Vehicle Systems International (http://www.auvsi.org/) puts on a contest every year (I think they're in their 16th year or so) for unmanned submarines. I'm going to go out on a limb and assume that this is what your project is for? Anyway, best of luck with it!
As far as I understand it, it doesn't work nearly as well for heavier particles (I assume you are thinking protons?). Especially ones with a positive charge. The heavy mass of the protons compared to the electrons in the plasma cloud are what allows the "wakefield" to be created in the first place. When we model this stuff, the ions move so slowly compared to the electrons that we generally just assume that they are static for the duration of the beam passing through the oven (pico-femto second range). As I mentioned earlier, this will most likely always show up as an "afterburner" that goes at the end of a traditional linac.
I actually do some work on this with the PWFA group at USC (i'm an undergrad research assistant). It really is amazing! We can reach acceleration gradients of around 60 GeV/m, compared to something like 40 MeV/m for a normal accelerator. It works like this: .or at least something close to that!
1. The electrons travel down the main linac in carefully spaced "bunches", and get accelerated to around 43 GeV over a course of ~3KM (this is at the main beam at SLAC).
2. A (in the last experiment) 1.2m long Lithium plasma "oven" is at the end of the beam, which the electrons are directed into.
3. The first, or "driving," bunch goes through the plasma, and repels all of the electrons it gets near, leaving an "empty" wake behind it, where only the positively charged ions are.
4. The positive charge behind the driving beam pulls it backwards, causing it to lose energy. At the same time, a "witness" bunch placed strategically within the wakefield gets pulled forward by the positively charged ions. The witness gains energy while the driver loses energy.
5. Voila! One bunch now has twice the energy, and one bunch now has none . .
The main caveat is that you're upward-limited by your entering energy, so you still need a huge Linac to accelerate the bunches to begin with. This will likely get tacked on in the form of a "plasma afterburner" to a normal linac, such as in the setup at SLAC.
This is basically what the Picaxe microcontroller series was made for. Their website is at http://www.picaxe.co.uk/ and a reseller for them in the united states is located at www.phanderson.com. It is basically a PIC microcontroller (they use various models, from 8-pins to 40, so the scalability factor is there), with a custom ROM flashed onto them that has a BASIC interpreter. Think of a Parallax BASIC-STAMP, only all in one chip, and the chips range from $3-10 for most of them, so its almost as cheap as you can get it. Additionally, the BASIC software development environment is free to download, has no limitations, and is geared towards an academic setting (it even includes the ability to draw out simple logic circuits and have it convert them to basic code). Also, THEY DO NOT REQUIRE A SEPARATE PROGRAMMER. To program a PIC normally, you would need a ~$50-100 programmer for each student, but these hook directly up to the serial port (a cable is just 3 wires coming out of a DB9 connector), so each student can easily reprogram their own, or even do it from home. They're incredibly versatile (check out the forum at their main site), and perfectly suited to academic use, for both younger and older students
I'm a junior in Electrical Engineering, and I have a 49G+ and love it! For the first 2 years I had it, it had horrible problems, but they were all fixed by subsequent firmware updates and it's been absolutely awesome for the last 3 years I've had it. The HP-50G is completely backwards compatible with the 49G+, only it has a more traditional, rugged black case, and I hear the keyboard is a little better. The calculator has a 75 MHZ ARM processor (that you can program in C!), like 1.5MB of RAM, and an SD card slot for basically infinite storage. Additionally, it has built in libraries of constants (with units and everything) and a fairly large library of scientific and engineering applications for it. I also have an original model TI-83 from 1996 that has been dropped and kicked and abused more than a soccer ball (complete with an embarrasingly large Pocket Monsters sticker on it from 7th grade), and it is still going strong. Oh, and for those who don't know, at least on the newer HP calculators (like the 49G+ and 50G), you can switch between RPN (Reverse Polish notation) and Algebra mode (TI-83 style).
So your argument boils down to: "Women complain about being treated unfairly, and think they deserve to be treated fairly. Well if they are treating themselves so fairly, what is the problem?" I'm sure the idea of genuine gender equality bothers you to no end, but it's so incredibly intellectually disingenius to say "If you're so equal, then quit bitching about us discriminating against you." As an electrical engineering student, the amount of shit most female engineering students have to put up with is almost staggering. We shouldn't pretend like there are suddenly no more problems just because a bunch of women took note of the situation and started complaining.
Using a plasma "afterburner" at SLAC, we were able to increase the energy of part of our beam from 43 GeV to ~100 GeV in the space of 1.2 meters. The main problem with all of this (plasma-wakefield particle accelerators as well) is getting high enough "current" to be useful. It is not that difficult to accelerate an electron or 2 up to that point, but to make a useful current is HARD. The absurdly short pulse durations necessary to create any kind of wakefield in the first place mean that 1) this is definitely beyond the reach of an undergrad (believe me, I am one, and I've looked into it), and 2) you still need a fairly large space and some fairly expensive equipment. We might get there someday, but we're not there yet.
I actually do some research in this area (Plasma-wakefield particle acceleration, really really similar), and one of the biggest problems is getting the pulse-width incredibly small. They have to use something called Chirp Pulse Amplification and I think the beam length is somewhere on the order of 1-2 picoseconds. From the article, the power delivered by this beam is about 40 TeraWatts, which gives you some sort of idea. The acceleration gradient might be really high, but that doesnt mean youre going to get a desktop version any time soon. The equipment necessary to get the timing (pulse-length and power) right is incredibly difficult and expensive at the moment.
Hey, at least in your comment about weight vs. volume in shipping costs, I would argue that you're fairly wrong. One of the largest "costs" is just the truck transporting itself, so if you can increase the density if goods on the truck, it saves money/resources/fossil fuels, etc. Try the following example:
Moving 1000 ipods from a packaging center to a store.
Using large packaging: say, 200 ipods can go per truck
Using smaller packaging: 500 ipods per truck, but the truck's weight is also increased somewhat
=> large package=5 trips, not to mention the trucks are transporting more weight total (1000 ipods, plus more packaging)
smaller package= 2 trips, and less overall weight (though higher density)
The individual journey of the truck might burn more fuel, but there would be way fewer shipments and significantly less fuel burnt overall
Ask and you shall receive . . .just made it =)
http://www-scf.usc.edu/~cfenton/flyingchairs.zip
I find it odd that many people have a knee-jerk reaction to defending any suggestion of government wrongdoing (most likely about as many as have a knee-jerk reaction to assume government wrongdoing). Why is it necessary to have an infallible government? No, not EVERYTHING the government does is evil or nefarious, but a lot of it is still wrong or misguided. The government is just made up of people, like everything else, and people tend to do lots of stupid and illegal stuff (especially Americans! Look at our incarceration rates!). Saying, "Well, the government wouldn't do anyting bad, so everyone should just shut up already" is a terrible attitude to take.
What, pray tell, is the difference between a "suspected terrorist" and an otherwise innocent citizen, if the courts have not decided they have done something wrong?
If they DO have enough probably cause to monitor them, why would it be difficult to get court approval?
And the important thing was, I was wearing an onion in my belt, because it was the style at the time. . .
There is actually a lot of active research going on in this field right now. It is called "Processor-in-memory" architecture, and it's best for handling things like array-based calculations, where you need to make a number of off-chip memory calls to complete. Staying completely on-chip makes it much faster, and it allows the embedded proc to take advantage of the internally wide (~256-bit) data path of modern memory. Look up Project DIVA and Project MONARCH, it is all DARPA-sponsored research, but the university I attend (USC) has a number of researchers involved with it.
I was under the impression that opening up the design of the UltraSPARC T1 was partly just to bolster interest in it (and it really is an incredible design from a hardware perspective) and partly just to allow people like EE and computer architecture students, along with hobbyists and engineers, to understand how it actually works at its most basic level. Although I realize i'm in the vast minority, as someone that actually DOES do microprocessor design in their spare time (I just completed my first working CPU design!), this is a really cool thing for them to do. I'm still learning verilog, but I would definitely like to look over some of their design docs and source sometime! I hardly think their goal is to get other people to build their own T1 processors though.
In a word: no. Wavelength*Frequency=Speed of wave. Propagation speed of a wave in a given medium is constant and solely dependant on the properties of that medium (in this case, Temperature and Pressure). Since speed of sound at STP is around 343 m/s, at 30 Hz, the wavelength will be much longer than it will be at 2975 Hz (2975/30 times faster, to be exact). As one goes up, the other goes down, but the speed is constant. If the speed was able to change, that simple relation would no longer mean anything...
They are probably just unemployed Unix sysadmins =)
Honestly, this is why I read slashdot. Bravo.
http://www.ebookwise.com/ebookwise/ebookwise1150.h tm
I recently got one of these things and it's a great deal. It cost me around $100 (I think it's gone back up to $130 now), so it's not terribly expensive, and it only weighs about a pound or so. You can import your own texts to it (i.e. project gutenberg texts), it can use Smartmedia cards (up to 128mb), so you can store a LOT of books, and the batteries last for about 25 hours and can just be charged off of 12V dc. Hook up a small 12V solar panel to trickle-charge it and you've got yourself around 300+ books for ~$150 or so!