That threshold is very low, about $5k I believe for a single worker with no dependents. Even at $5/hour you'll make $10.4k/year working standard full time.
An interesting anecdote to add to this which is found in Anthony Bourdain's "Kitchen Confidential", he says he prefers the South American workers in his kitchens above US-born workers because the former will work hard, show up on time, and follow directions while the latter are entitled and needy. And these are in restaurants, not just fast food.
I'm not sure if this was part of their reasoning, but it could be that there is more noise in the infrared region. There is quite a bit in visible as well to be sure, but just somebody walking around is emitting some infrared. Indoors if you control the lights you might control most of the visible spectrum.
There might also be issues scaling up the transmit power for high signal to noise ratios in the low bandgap materials needed for IR LEDs. Quite a bit of effort has already gone into scaling up power levels for high bandgap materials for lighting applications. Material issues also may limit the modulation speed of IR LEDs.
Of course it could just be that a research group is just trying to capitalize on existing LED developments to get more research funding in spite of it being a suboptimal solution.
As a result, the plant produces one kilowatt-hour -- or 1,000 watt-hours -- of electricity for each 870 watts consumed the previous night.
Not to mention they have made the classic mistake of confusing Power and Energy. Watt-hours is an energy because it has units of Joules. Watts are in the form of Joules/second which simply represents how quickly you are transferring energy from one place or form to another.
LED's are made from various III-V semiconductors. Depending on the material choice du jour, there can be gallium, indium, arsenic, and more making up the semiconductor die.
Ah yes, the fable of the fable of Dvorak being superior. All I know for sure scientifically is that there is flawed data and personal bias supporting and refuting the superiority of the Dvorak keyboard. Read about some of it here: http://dvorak.mwbrooks.com/dissent.html
Ultimately I don't care what the conclusions of these studies are though. As an experienced Dvorak and Qwerty typist, I can say confidently that I find it more comfortable to type in Dvorak, since the letters I need are more frequently on the home row of the keyboard. I have heard many Dvorak typists agree with that assertion. Scientific? No. But possibly compelling.
I don't really care whether or not I'm slightly faster in Dvorak than if I'd invested the same time training in Qwerty because I can put out 80WPM on either, and I don't need to type stuff that quickly very often.
Proper touch-typing training in either keyboard will obviously improve your speed and ergonomic comfort.
I completely agree. I can switch back to QWERTY easily enough on the rare occasions where it's necessary, but I always end up feeling uncomfortable from all stretching into far corners of the keyboard that I have to do.
When it came to the insurance companies, the sticker price meant little since they had negotiated their own deals with the hospital. Neither the hospital nor the insurance companies would elaborate. The entire medical bill for seven years, in fact, was steeply discounted. The $618,616 was lowered to $254,176 when the insurers paid their share and imposed their discounts. The portion of the charges that were not covered for the most part vaporized. Terence and I were responsible for and paid $9,468--less than 4%.
Ironically if they were uninsured, they would be on the hook for the entire $618,616 instead of what the insurance companies paid.
Water absorbs pretty strongly from microwave, millimeter wave, terahertz, and through much of infrared. The 2.45GHz frequency for microwave ovens was chosen because of surplus radar magnetrons, or at least magnetron designs, at the end of WW2. Industrial microwave heaters also use 900MHz, the other ISM band.
I think the lowest cell phone band is 600MHz which may have the least water absorption, but there will still be significant absorption.
Nope. Your head is largely made of water with ionic compounds in it. Water is highly polar so it absorbs a lot of power through dielectric effects (how a microwave oven works). It's also a poor conductor, so it absorbs power through conduction effects. Perfect conductors and perfect insulators absorb no power, it's the poor conductors that you have to worry about.
We do know the actual RF wattage that can be produced, it's not some big mystery it takes 2 seconds of googling. See WHO, it is between 10 and 100W, with newer towers being smaller power levels.
It should be obvious that cell towers don't use parabolic antennas. They are typically going for wide coverage, which directly translates into a low-gain antenna. You will notice that most cell antenna masts have three antennas pointing 120 degrees apart, which suggests probably about 6dB gain per antenna, maybe a bit less. The vertical pattern is narrowed, so call it another 2dB, so call it 8dB gain. The max equivalent isotropically radiated power (EIRP) will thus be 100W*10^0.8 = 630W.
630W / (4*pi*(6m)^2) gives 1.4W/m^2 at a 6 meter (20foot) distance.
The ANSI standard at 300MHz in uncontrolled environments is 2W/m^2. So it is under the gov. mandated safety limit. It could be much less if the base station is not an old high power one, or could be a bit higher if my antenna gain estimate is off. Standing wave effects (if reflection and incident wave are in phase at your location) could push it higher, but the 2W/m^2 is actually 20% the exposure level for controlled environments (10W/m^2), so there is already a generous safety margin to account for that. And cell phones operate over 300MHz where the limits are actually higher.
If in doubt, call the phone company and get details, or do as others say and shield your apartment.
I'd also be very interested to know whether this can be mass produced, and for how much money. They say they are currently working on cells one square centimeter in size.
They're currently working on scaling it up, but arranging these nanowires in a large array, making the electrical connections, and filling with the polymer and scatterers sounds like it will be hard to mass-produce, even if the materials cost is not as high.
Wow, so you just assume that the ice skating rinks in general only have a single team as their only customer?
I'm just basing this on the rink in the town I grew up in, but there were multiple teams of different levels from kids leagues on up who used the rinks. It was open to the public almost all week because inside the building there were multiple rinks, and more than once I've been skating there while a game was in progress. They may not resurface quite as often as when a hockey game is in progress, but based on my observations it is at least a few times per day, times the number of rinks in a facility when only being used for light public skating, more frequent resurfacing for everything else.
A rink has high capital expenses and certain minimum operational expenses, so they need to be open as much as possible to make the money to meet those expenses. Even pro stadiums will get rented for use by other teams or for classes, though they might not be open to the public.
Graphene is still very much a lab technology which isn't anywhere near ready for commercial production of devices. It may turn out to replace Silicon one day, but guess what, people keep doing amazing shit with silicon because it's still the cheapest material system for fabrication.
There are always applications where we can do better systems with more expensive materials like GaAs, GaN, InP, Graphene, etc... but silicon is cheap and easily mass-produced, so lots of engineers work on pushing it to incredible performance.
Since you didn't cite anything, I will do so from the first Google result. From IntelSuperfundCleanup.com
Low levels (less than 1 part per million [ppm] or 1,000 parts per billion [ppb]) of VOCs were detected in ground water at two Intel facilities (Santa Clara 3 and Magnetics) and more significant levels were detected at a third facility (Mountain View "Lot 3"). Since these discoveries, Intel has very aggressively cleaned up these sites. By early 1986, all site source areas had been removed and ground water extraction and treatment systems (GWETS) had been installed and were operating to cleanup and contain residual VOCs in ground water.
Your inflammatory rhetoric does not seem to be backed up, as the pollution sounds small (though extant), and Intel has actively participated in the cleanup. Did you have any actual information to support your assertion?
Modern radars these days use a spread spectrum CDMA type modulation because of the immense advantages that it offers against things like out of range objects (too close or too far), spurious signals, and multipath.
They way it works is you modulate your carrier with an orthogonal code like an M Sequence, which will autocorrelate nearly to zero unless it lines up exactly with itself. Then you keep correlating your received bit stream with your code, and when they line up correctly you get a peak corresponding to an object at a range. If you get more peaks at different points, they correspond to objects at different ranges.
No. When the spin of the first particle is "measured", the spin of the second particle will be the same. But you have no control whatsoever over the outcome of the first spin measurement, and no way to control the second particle. The entanglement only depends on the two particles starting out with the same quantum state. If you change the state of particle 1 to have some control on the outcome of the spin measurement, then the particles no longer have the same state, and are no longer "entangled".
It's like I seal the same secret message in two envelopes and hand them off to two people. When they open the envelopes they will both read the same message. But if one person writes something down on their message, the second person will not receive it.
The key difference from other imaging technologies is that this is completely passive, it directly measures magnetic fields created by activity in your brain. To get accurate results with such tiny fields, it must be done in a magnetically shielded room with a large number of sensitive sensors.
I have been a TA for several engineering classes, and I now always ask my students to send me their lab reports in PDF format when they can't turn in a paper copy. I can use that on any of my computers, I don't have to mess around with the office 2007 formats, and I know that the files won't have weird issues like moving pictures around, or not displaying some, or not printing equations, all of which have happened to me with student work. And it's dead simple to make a PDF file, whether you use Word, Open Office, LaTeX, etc. I think even Word now has a direct export option, and there's always the PDF printer drivers.
At 20kHz two chunks of aluminum makes for a pretty nice cable. With 50GHz coax you need tiny precision machined connectors (2.4mm), and a very narrow cable with a low permittivity dielectric. Such a cable costs about $2,000.
The reason for the precision, size, and expense at those frequencies (as you know but others probably don't) is that if you have a large cable, there are multiple different wave equation solutions (modes) which allow power of a particular frequency to travel down a cable, and they will propagate at different speeds in the cable (and different attenuations), so what you get out of the cable is a distorted version of the input. So you must make the cable with size on the order of the smallest wavelength you intend to transmit. And it has to be precisely made because imperfections, scratches, and so on need to be even smaller or they will cause an impedance shift which reflects some signal back at the source.
At 50Ghz a wavelength is 6mm. At 20kHz it is 15km. This is why it is easy to make very nice audio cables, and hard to make nice HF cables.
Clock skew, when clock is sent on a separate connection from data, can definitely be fixed, it's just a question of whether or not it was included in the design. It's not too hard to step a received clock up or down in frequency with a PLL, and shift it forward or backward in time, in the digital or analog domain, relative to data. Then typically there would be some kind of control or calibration code sent on startup, or periodically, to calibrate the clock. But who knows whether it exists in I2S chips, I sure don't.
S/PDIF of course does not have a separate clock, it is sent inside the data stream, so there is a separate clock recovery circuit which is set up by recurring bit patterns in the data stream. If I recall, for ethernet, each packet is prefixed and suffixed with a certain length of 01010101... to get the receiver clock sync'd. The length of cable does not change with time, so you can have the length whatever you want and fix it in clock recovery. If you have multiple data channels (different speakers?), the time delay difference is insignificant compared to the sound, but it could be fixed by similar methods if it was critical. Again, just depends how they design it.
All of the issues that you mention, distortion (presumably frequency dispersion), S/N, and frequency response, will all play a significant role in digital communication. Poor performance in any of these three "analog" factors will limit the maximum speed of digital communication on the cable. After all, a digital signal is just a way of interpreting an analog waveform.
If a "highly directional antenna" is all it takes for this to work, then I wouldn't call it so fake. Wouldn't it be easy to track the position of a few target objects (cellphones, iPods, etc.) lying around the house and direct a "beam" of charge at each of them?
It would be quite possible to make a tracking CW transmitter either using a gimbaled antenna (unlikely) or phased array (better, but quite pricey), the problem is that it will be incredibly expensive, even if it reaches mass production, especially if you want it to have anything approaching a useful range. This thing would also be be extremely inefficient.
Then the next problem is that if you have a useful amount of charging RF power incident on the device, you have to make sure that it doesn't interfere with normal cell-phone operation. Obviously it can't be done at a cell-phone frequency, and there will be additional challenging (i.e. expensive, space-consuming, and range-reducing) filter component requirements necessary to prevent saturating the cell phone's receiver.
Your point of view is not unreasonable, but I see it as just being business and capitalism in action.
If organizers of any trade show or convention want to ensure that ALL vendors in the hotel purchase the pricey booths in the convention hall, then it would be perfectly reasonable for them to ask a hotel to make that their policy during the show. It would then be written into the contract that both parties sign. Then the hotel could make it a POLICY which they DISCLOSE to guests before they pay for their room.
Because this would be a restrictive policy which would realistically inconvenience many hotel guests and the hotel staff, the hotel will be able to command a higher price from trade show customers who want such a clause enforced. And while this may also be seen as an unpopular move by small companies and some convention go-ers who like having the small companies around as well as large ones, it would at least be fair.
Note that in this particular case, according to the article, the hotel specifically told guests who inquired ahead of time that meeting with customers and showcasing products in hotel rooms would be allowed, within normal room occupancy restrictions. This is the key point. Based solely on the DailyTech article, and IANAL, it has some of the makings of Bait and Switch, which is fraud, because the vendor mentioned was able to stay in the hotel only after paying an additional $10,000 to a third party (CEA).
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That threshold is very low, about $5k I believe for a single worker with no dependents. Even at $5/hour you'll make $10.4k/year working standard full time.
An interesting anecdote to add to this which is found in Anthony Bourdain's "Kitchen Confidential", he says he prefers the South American workers in his kitchens above US-born workers because the former will work hard, show up on time, and follow directions while the latter are entitled and needy. And these are in restaurants, not just fast food.
I'm not sure if this was part of their reasoning, but it could be that there is more noise in the infrared region. There is quite a bit in visible as well to be sure, but just somebody walking around is emitting some infrared. Indoors if you control the lights you might control most of the visible spectrum.
There might also be issues scaling up the transmit power for high signal to noise ratios in the low bandgap materials needed for IR LEDs. Quite a bit of effort has already gone into scaling up power levels for high bandgap materials for lighting applications. Material issues also may limit the modulation speed of IR LEDs.
Of course it could just be that a research group is just trying to capitalize on existing LED developments to get more research funding in spite of it being a suboptimal solution.
Not to mention they have made the classic mistake of confusing Power and Energy. Watt-hours is an energy because it has units of Joules. Watts are in the form of Joules/second which simply represents how quickly you are transferring energy from one place or form to another.
LED's are made from various III-V semiconductors. Depending on the material choice du jour, there can be gallium, indium, arsenic, and more making up the semiconductor die.
Ah yes, the fable of the fable of Dvorak being superior. All I know for sure scientifically is that there is flawed data and personal bias supporting and refuting the superiority of the Dvorak keyboard. Read about some of it here: http://dvorak.mwbrooks.com/dissent.html
Ultimately I don't care what the conclusions of these studies are though. As an experienced Dvorak and Qwerty typist, I can say confidently that I find it more comfortable to type in Dvorak, since the letters I need are more frequently on the home row of the keyboard. I have heard many Dvorak typists agree with that assertion. Scientific? No. But possibly compelling.
I don't really care whether or not I'm slightly faster in Dvorak than if I'd invested the same time training in Qwerty because I can put out 80WPM on either, and I don't need to type stuff that quickly very often.
Proper touch-typing training in either keyboard will obviously improve your speed and ergonomic comfort.
I completely agree. I can switch back to QWERTY easily enough on the rare occasions where it's necessary, but I always end up feeling uncomfortable from all stretching into far corners of the keyboard that I have to do.
RTFA.
Ironically if they were uninsured, they would be on the hook for the entire $618,616 instead of what the insurance companies paid.
So it's very much a "sink or swim" approach to inventing :)
Water absorbs pretty strongly from microwave, millimeter wave, terahertz, and through much of infrared. The 2.45GHz frequency for microwave ovens was chosen because of surplus radar magnetrons, or at least magnetron designs, at the end of WW2. Industrial microwave heaters also use 900MHz, the other ISM band.
I think the lowest cell phone band is 600MHz which may have the least water absorption, but there will still be significant absorption.
Nope. Your head is largely made of water with ionic compounds in it. Water is highly polar so it absorbs a lot of power through dielectric effects (how a microwave oven works). It's also a poor conductor, so it absorbs power through conduction effects. Perfect conductors and perfect insulators absorb no power, it's the poor conductors that you have to worry about.
To put numbers to your comments:
We do know the actual RF wattage that can be produced, it's not some big mystery it takes 2 seconds of googling. See WHO, it is between 10 and 100W, with newer towers being smaller power levels.
It should be obvious that cell towers don't use parabolic antennas. They are typically going for wide coverage, which directly translates into a low-gain antenna. You will notice that most cell antenna masts have three antennas pointing 120 degrees apart, which suggests probably about 6dB gain per antenna, maybe a bit less. The vertical pattern is narrowed, so call it another 2dB, so call it 8dB gain. The max equivalent isotropically radiated power (EIRP) will thus be 100W*10^0.8 = 630W.
630W / (4*pi*(6m)^2) gives 1.4W/m^2 at a 6 meter (20foot) distance.
The ANSI standard at 300MHz in uncontrolled environments is 2W/m^2. So it is under the gov. mandated safety limit. It could be much less if the base station is not an old high power one, or could be a bit higher if my antenna gain estimate is off. Standing wave effects (if reflection and incident wave are in phase at your location) could push it higher, but the 2W/m^2 is actually 20% the exposure level for controlled environments (10W/m^2), so there is already a generous safety margin to account for that. And cell phones operate over 300MHz where the limits are actually higher.
If in doubt, call the phone company and get details, or do as others say and shield your apartment.
I'd also be very interested to know whether this can be mass produced, and for how much money. They say they are currently working on cells one square centimeter in size.
They're currently working on scaling it up, but arranging these nanowires in a large array, making the electrical connections, and filling with the polymer and scatterers sounds like it will be hard to mass-produce, even if the materials cost is not as high.
Still, good for them.
Wow, so you just assume that the ice skating rinks in general only have a single team as their only customer?
I'm just basing this on the rink in the town I grew up in, but there were multiple teams of different levels from kids leagues on up who used the rinks. It was open to the public almost all week because inside the building there were multiple rinks, and more than once I've been skating there while a game was in progress. They may not resurface quite as often as when a hockey game is in progress, but based on my observations it is at least a few times per day, times the number of rinks in a facility when only being used for light public skating, more frequent resurfacing for everything else.
A rink has high capital expenses and certain minimum operational expenses, so they need to be open as much as possible to make the money to meet those expenses. Even pro stadiums will get rented for use by other teams or for classes, though they might not be open to the public.
Graphene is still very much a lab technology which isn't anywhere near ready for commercial production of devices. It may turn out to replace Silicon one day, but guess what, people keep doing amazing shit with silicon because it's still the cheapest material system for fabrication.
Apologies to those without IEEE access, but here is a paper discussing a recent 150GHz Silicon CMOS amplifier: A 1.1V 150GHz amplifier with 8dB gain and +6dBm saturated output power in standard digital 65nm CMOS using dummy-prefilled microstrip lines. That's pretty awesome in my book. It's pushing the amplifier very close to fmax of the actual transistors, but it works and it's in a commercial silicon process.
There are always applications where we can do better systems with more expensive materials like GaAs, GaN, InP, Graphene, etc... but silicon is cheap and easily mass-produced, so lots of engineers work on pushing it to incredible performance.
Since you didn't cite anything, I will do so from the first Google result. From IntelSuperfundCleanup.com
Your inflammatory rhetoric does not seem to be backed up, as the pollution sounds small (though extant), and Intel has actively participated in the cleanup. Did you have any actual information to support your assertion?
Modern radars these days use a spread spectrum CDMA type modulation because of the immense advantages that it offers against things like out of range objects (too close or too far), spurious signals, and multipath.
They way it works is you modulate your carrier with an orthogonal code like an M Sequence, which will autocorrelate nearly to zero unless it lines up exactly with itself. Then you keep correlating your received bit stream with your code, and when they line up correctly you get a peak corresponding to an object at a range. If you get more peaks at different points, they correspond to objects at different ranges.
No. When the spin of the first particle is "measured", the spin of the second particle will be the same. But you have no control whatsoever over the outcome of the first spin measurement, and no way to control the second particle. The entanglement only depends on the two particles starting out with the same quantum state. If you change the state of particle 1 to have some control on the outcome of the spin measurement, then the particles no longer have the same state, and are no longer "entangled".
It's like I seal the same secret message in two envelopes and hand them off to two people. When they open the envelopes they will both read the same message. But if one person writes something down on their message, the second person will not receive it.
http://en.wikipedia.org/wiki/Magnetoencephalography
The key difference from other imaging technologies is that this is completely passive, it directly measures magnetic fields created by activity in your brain. To get accurate results with such tiny fields, it must be done in a magnetically shielded room with a large number of sensitive sensors.
I have been a TA for several engineering classes, and I now always ask my students to send me their lab reports in PDF format when they can't turn in a paper copy. I can use that on any of my computers, I don't have to mess around with the office 2007 formats, and I know that the files won't have weird issues like moving pictures around, or not displaying some, or not printing equations, all of which have happened to me with student work. And it's dead simple to make a PDF file, whether you use Word, Open Office, LaTeX, etc. I think even Word now has a direct export option, and there's always the PDF printer drivers.
At 20kHz two chunks of aluminum makes for a pretty nice cable. With 50GHz coax you need tiny precision machined connectors (2.4mm), and a very narrow cable with a low permittivity dielectric. Such a cable costs about $2,000.
The reason for the precision, size, and expense at those frequencies (as you know but others probably don't) is that if you have a large cable, there are multiple different wave equation solutions (modes) which allow power of a particular frequency to travel down a cable, and they will propagate at different speeds in the cable (and different attenuations), so what you get out of the cable is a distorted version of the input. So you must make the cable with size on the order of the smallest wavelength you intend to transmit. And it has to be precisely made because imperfections, scratches, and so on need to be even smaller or they will cause an impedance shift which reflects some signal back at the source.
At 50Ghz a wavelength is 6mm. At 20kHz it is 15km. This is why it is easy to make very nice audio cables, and hard to make nice HF cables.
Clock skew, when clock is sent on a separate connection from data, can definitely be fixed, it's just a question of whether or not it was included in the design. It's not too hard to step a received clock up or down in frequency with a PLL, and shift it forward or backward in time, in the digital or analog domain, relative to data. Then typically there would be some kind of control or calibration code sent on startup, or periodically, to calibrate the clock. But who knows whether it exists in I2S chips, I sure don't.
S/PDIF of course does not have a separate clock, it is sent inside the data stream, so there is a separate clock recovery circuit which is set up by recurring bit patterns in the data stream. If I recall, for ethernet, each packet is prefixed and suffixed with a certain length of 01010101... to get the receiver clock sync'd. The length of cable does not change with time, so you can have the length whatever you want and fix it in clock recovery. If you have multiple data channels (different speakers?), the time delay difference is insignificant compared to the sound, but it could be fixed by similar methods if it was critical. Again, just depends how they design it.
All of the issues that you mention, distortion (presumably frequency dispersion), S/N, and frequency response, will all play a significant role in digital communication. Poor performance in any of these three "analog" factors will limit the maximum speed of digital communication on the cable. After all, a digital signal is just a way of interpreting an analog waveform.
It would be quite possible to make a tracking CW transmitter either using a gimbaled antenna (unlikely) or phased array (better, but quite pricey), the problem is that it will be incredibly expensive, even if it reaches mass production, especially if you want it to have anything approaching a useful range. This thing would also be be extremely inefficient.
Then the next problem is that if you have a useful amount of charging RF power incident on the device, you have to make sure that it doesn't interfere with normal cell-phone operation. Obviously it can't be done at a cell-phone frequency, and there will be additional challenging (i.e. expensive, space-consuming, and range-reducing) filter component requirements necessary to prevent saturating the cell phone's receiver.
Your point of view is not unreasonable, but I see it as just being business and capitalism in action.
If organizers of any trade show or convention want to ensure that ALL vendors in the hotel purchase the pricey booths in the convention hall, then it would be perfectly reasonable for them to ask a hotel to make that their policy during the show. It would then be written into the contract that both parties sign. Then the hotel could make it a POLICY which they DISCLOSE to guests before they pay for their room.
Because this would be a restrictive policy which would realistically inconvenience many hotel guests and the hotel staff, the hotel will be able to command a higher price from trade show customers who want such a clause enforced. And while this may also be seen as an unpopular move by small companies and some convention go-ers who like having the small companies around as well as large ones, it would at least be fair.
Note that in this particular case, according to the article, the hotel specifically told guests who inquired ahead of time that meeting with customers and showcasing products in hotel rooms would be allowed, within normal room occupancy restrictions. This is the key point. Based solely on the DailyTech article, and IANAL, it has some of the makings of Bait and Switch, which is fraud, because the vendor mentioned was able to stay in the hotel only after paying an additional $10,000 to a third party (CEA).