Homer: All you can eat - hah! Hutz: Mr. Simpson, this is the most blatant case of fraudulent advertising since my case against the film, Neverending Story.
130V bulbs last dramatically longer because their filaments run much cooler than 120V bulbs (they have larger and thicker filaments, hence a greater surface area to dissipate heat). This is great for longevity, but it comes at a heavy price in efficiency. The lower filament temperature shifts the bulbs emission spectrum towards the infrared (Planck's Law) reducing the amount of visible light produced. This reduction in efficiency will require more electricity to produce a given amount of light. When all is said and done it takes far fewer resources to make higher temperature bulbs that are more efficient than to keep one long life bulb chugging along. Of course, if resource/energy efficiency is a concern halogen and fluourescent bulbs are far better than any conventional incandescent.
There are also other techniques to increase the longevity of regular bulbs. Since the most likely time for bulb failure occurs at switch on, using a switch that only activates at a zero-crossing of the voltage waveform minimizes the turn-on stress. The inrush current to a cold bulb can be on the order of 10x the running current (an incandescent filament is an extremely non-ohmic load because its resistance varies dramatically with temperature). It's this high current that causes high stress on the filament (the motor effect can cause the filament to twist violently). From what I've read, this technique is often used on navigational beacon lights (these lights also use over-rated bulbs to gain lifetime at the expense of efficiency).
Another technique to minimize turn-on stress is keep the bulb running 'warm', that is to pass enough current to keep the filament at a temperature just below that needed to produce visible light. The relatively high temperature raises the resistance of filament, thus dramatically reducing inrush current. According to some theatre techs that I know, this technique is extensively used in theatre and television where a light failure could ruin a show.
Motorola made most of their microcontrollers for the automotive sector where massive volumes ruled. One unfortunate consequence of this was their absolute minimum of support for anyone designing lower volume applications, which I feel has really hurt them in getting mindshare of engineers working for smaller companies and expanding their market. Good tools were horribly expensive and most of their documentation was even worse (I still have nightmares about the horribly inconsistent Dragonball documentation). The only decent document I've seen from them is for the HC11, which is really a shame because they have some great chips. Companies like Atmel and Microchip are absolutely killing Motorola in the 8 bit market amongst smaller shops because of their readily available tools, decent documentation and support.
The US Navy also launched a system named NOSS (Naval Ocean Surveilance System), which used a formation of satellites to determine positions of naval vessels through radio triangulation and time difference of arrival techniques.
Umm, I don't know how you get 6500 kWh from a 190 Watt panel over a year.
0.190kW x (24 x 365)hr = 1664 kWh
That's assuming a panel receives full insolation 24 hours a day, 365 days a year. LA isn't that sunny:-)
That being said, the parents point that PV cells pay for themselves in energy production terms still stands. All of the figures I've seen in the past few years point to energy payback times on the order of a few years.
Actually, water turbines and pumps are extremely efficient (90%+). The round trip efficiency for pumped storage is thus in the range of 80% or so, much better than any fuel cell. You're also not taking into account the inefficiency of electrolysis, which is generally about 70% efficient.
I'm a big fan of nuclear power myself, but you miss a few issues with being overly dependent on nuke power for your electricity. The first issue is that nuke plants, while being fantastic for providing baseline supply, have a pretty lousy response time to changes in demand. Being thermal plants, they don't care to be throttled back and forth too much. Excessive power changes also have a tendency to reduce efficieny by poisoning the fuel with unwanted isotopes from partial load operation, hence they are almost always run full-out. The best sources for providing non-baseline power are hydro and gas-turbine plants because they aren't subject to the same thermal inertia problems as nuclear plants and to a lesser extent, coal plants.
The second issue is that nuclear plants aren't generally cold startable; that is they need the grid to be up for startup because they require a great deal of power for pumps, control, etc. Gas-turbine and hydro plants are generally cold startable.
Taking all this into account, a reliable grid needs a mix of plant types for reliability. It would be impractical to have a completely nuclear power system; doing so would require power storage of one type or another to cope with demand changes, much as you would in system a large proportion of renewable sources. And before you rebut by saying 75% of France's generation capacity is nuclear, take into account that they trade a great deal of power with Germany, who use mostly thermal sources. It's the boundaries of the electrical grid that matter, not the political ones.
For the most part the 12V line is probably running things like fans, drive motors, and other non-logic related equipment. In other words, it isn't supplying anything that is especially sensitive to ripple or slightly out of spec voltage. The power supply is probably regulating on the 5 or 3.3V power output, leaving the others to wander according to their applied loads (they're simply tapped off different windings of the output transformer, they have no regulation of their own).
, and the speed of core-voltage drop does not keep up with frequency bumps (heat is square of frequency for CMOS gates).
Power in CMOS gates is linearly proportional to the frequency and the square of the *voltage*.
Since the majority of power dissipation in CMOS devices comes from charging and discharging their parasitic capacitance this is fairly obvious when taking into account the formula for energy in a capacitor 1/2*C*V^2. There is also the small in comparison power dissipation due to the ohmic resistance of the gates, which is more or less constant, no matter the frequency.
Calling it the Iron Ring ceremony is more accurate than calling it "The Kipling". However when I went through the ceremony, I believe the formal name for it was "The Ritual of the Calling of the Engineer".
That's probably not a typo, although it is an incomplete specification; there should be a value for the current ripple that the lifetime is specified at. The greater the ripple current, the lower the life-expectancy.
It's up to the designers who use the components to ensure that the ripple is low enough to give the lifespan required. As I recall, there also tends to be knee in the ripple voltage vs lifetime curve, for a minor change in ripple voltage there could be a drastic reduction in longevity.
I didn't notice that I wrote tongue-in-tongue, which makes no sense whatsoever:-) That should read clevis-in-clevis, I guess I was thinking tongue-in-groove construction.
Here's another linkdetailing the booster improvements.
Actually, there were innumerable changes and improvements to the shuttle design made after the Challenger disaster, especially to the solid boosters. The old booster joint was a simple tongue-in-groove construction that depended entirely on its two O-rings to contain the products of combustion. The new design is tongue-in-tongue with, as I recall three O-rings. In addition there is a flexible "flap" that covers the joint internally so the hot combustion gases don't impinge on the O-rings. As for the cold problem, there are now heaters in the SRB joints, precisely to ward off freeze damage.
Here's a link to some SRB technical documentation, very good reading for the engineer types.
There is much more documentation available at this site pertaining to all of the shuttle's systems for the those interested.
It is entirely possible for devices like an MD player to interfere with radio equipment. I once encountered a problem where a Sony CD player interfered with a ham radio receiver in the 2M band (144-148 Mhz), you could even hear the music work it's way through the demodulator of the receiver. This was probably due to harmonics from the delta-sigma DAC extending into the VHF range. Since the aircraft voice communication band is in the low VHF range as well (108-136MHz), I find it entirely plausible that an obstensibly non-transmitting device can interfere with radio communications.
This interference often happened with old, simple garage door openers because they often operated on the military air communications band of 225-400 MHz. An over passing aircraft simply had to key up their radios to interfere with these old systems because they didn't have the digital security coding features of their modern equivalents. Air force one has many communications systems that operate in this band, but that isn't really peculiar to AF1, most if not all military aircraft have radios that operate in this frequency range.
Nowadays, most of Air force one's communications take place over satellite links, but they still use the standard military/civilian aircraft frequencies, since they need to communicate with the air-traffic control system. Here's a link with information on AF1's older communication systems that operate in the UHF band.
Thermoelectric generators have already seen extensive service in remote areas where reliability is the main concern. One of the most common examples is for cathodic protection of oil and gas pipelines. Obviously in this type of application the fuel supply is a non-issue, which helps overcome the disadvantage of the TEG's low efficiency.
Global Thermoelectric has had a wide range of these systems available for quite some time.
While the Mars rover itself didn't generate electricity from a nuclear source, there were some small radioisotope pieces onboard acting as heaters to provide thermal regulation. It's been awhile, but I recall that they produced on the order of a few watts of heat.
As an electrical engineer I have to chip in and say that the parent to this post is more correct. The majority of the losses in your average wall-wart are from the hysterisis (eddy-current) losses in the the transformer core and resistance in the windings. The capacitors are pretty much a non-issue; even the cheapest varieties are about the most efficient parts you're going to find in a 60Hz power supply. Capacitor efficiency typically only becomes an issue in high frequency switching supply design, then the ESR (Equivalent Series Resistance) takes on relevance.
It is usually discouraged to use X-10 for loads like heaters and motors because the standard protocol doesn't acknowledge sent commands. If a command didn't make it through, the sender is unaware of this and could leave the controlled device operating in an unsafe way. Even worse, if a glitch turns on a module, your heater or motor could fire up for no apparent reason.
Not necessarily. Only asynchronous protocols (RS-232 and the like) need the extra stop and start bits. Cable modems use modulation schemes where the clock can be derived from the signal, making the start/stop bits unnecessary.
The Orbcomm corporation operates a system that uses text and data transmission for use like you describe. Their transceivers are a little larger than a Blackberry, but are still quite portable. The system also seems to be used extensively for remote telemetry purposes, to which it is especially suited.
I recall reading about the development of ceramic based engines a few years back. The ceramics had the the potential of allowing higher combustion temperatures while using using leaner fuel mixtures. While these higher temperatures allow for higher thermodynamic efficiencies they also promote the creation of nitrogen oxides, to the point of making the engines too dirty to pass emissions standards. No real conspiracies of suppressed technology here, just real technical/regulatory issues.
Slashdot Mirror
Homer: All you can eat - hah!
Hutz: Mr. Simpson, this is the most blatant case of fraudulent advertising since my case against the film, Neverending Story.
130V bulbs last dramatically longer because their filaments run much cooler than 120V bulbs (they have larger and thicker filaments, hence a greater surface area to dissipate heat). This is great for longevity, but it comes at a heavy price in efficiency. The lower filament temperature shifts the bulbs emission spectrum towards the infrared (Planck's Law) reducing the amount of visible light produced. This reduction in efficiency will require more electricity to produce a given amount of light. When all is said and done it takes far fewer resources to make higher temperature bulbs that are more efficient than to keep one long life bulb chugging along. Of course, if resource/energy efficiency is a concern halogen and fluourescent bulbs are far better than any conventional incandescent.
There are also other techniques to increase the longevity of regular bulbs. Since the most likely time for bulb failure occurs at switch on, using a switch that only activates at a zero-crossing of the voltage waveform minimizes the turn-on stress. The inrush current to a cold bulb can be on the order of 10x the running current (an incandescent filament is an extremely non-ohmic load because its resistance varies dramatically with temperature). It's this high current that causes high stress on the filament (the motor effect can cause the filament to twist violently). From what I've read, this technique is often used on navigational beacon lights (these lights also use over-rated bulbs to gain lifetime at the expense of efficiency).
Another technique to minimize turn-on stress is keep the bulb running 'warm', that is to pass enough current to keep the filament at a temperature just below that needed to produce visible light. The relatively high temperature raises the resistance of filament, thus dramatically reducing inrush current. According to some theatre techs that I know, this technique is extensively used in theatre and television where a light failure could ruin a show.
Motorola made most of their microcontrollers for the automotive sector where massive volumes ruled. One unfortunate consequence of this was their absolute minimum of support for anyone designing lower volume applications, which I feel has really hurt them in getting mindshare of engineers working for smaller companies and expanding their market. Good tools were horribly expensive and most of their documentation was even worse (I still have nightmares about the horribly inconsistent Dragonball documentation). The only decent document I've seen from them is for the HC11, which is really a shame because they have some great chips. Companies like Atmel and Microchip are absolutely killing Motorola in the 8 bit market amongst smaller shops because of their readily available tools, decent documentation and support.
A small blurb on the system can be found here.
Umm, I don't know how you get 6500 kWh from a 190 Watt panel over a year.
0.190kW x (24 x 365)hr = 1664 kWh
That's assuming a panel receives full insolation 24 hours a day, 365 days a year. LA isn't that sunny:-)
That being said, the parents point that PV cells pay for themselves in energy production terms still stands. All of the figures I've seen in the past few years point to energy payback times on the order of a few years.
Actually, water turbines and pumps are extremely efficient (90%+). The round trip efficiency for pumped storage is thus in the range of 80% or so, much better than any fuel cell. You're also not taking into account the inefficiency of electrolysis, which is generally about 70% efficient.
I'm a big fan of nuclear power myself, but you miss a few issues with being overly dependent on nuke power for your electricity. The first issue is that nuke plants, while being fantastic for providing baseline supply, have a pretty lousy response time to changes in demand. Being thermal plants, they don't care to be throttled back and forth too much. Excessive power changes also have a tendency to reduce efficieny by poisoning the fuel with unwanted isotopes from partial load operation, hence they are almost always run full-out. The best sources for providing non-baseline power are hydro and gas-turbine plants because they aren't subject to the same thermal inertia problems as nuclear plants and to a lesser extent, coal plants.
The second issue is that nuclear plants aren't generally cold startable; that is they need the grid to be up for startup because they require a great deal of power for pumps, control, etc. Gas-turbine and hydro plants are generally cold startable.
Taking all this into account, a reliable grid needs a mix of plant types for reliability. It would be impractical to have a completely nuclear power system; doing so would require power storage of one type or another to cope with demand changes, much as you would in system a large proportion of renewable sources. And before you rebut by saying 75% of France's generation capacity is nuclear, take into account that they trade a great deal of power with Germany, who use mostly thermal sources. It's the boundaries of the electrical grid that matter, not the political ones.
For the most part the 12V line is probably running things like fans, drive motors, and other non-logic related equipment. In other words, it isn't supplying anything that is especially sensitive to ripple or slightly out of spec voltage. The power supply is probably regulating on the 5 or 3.3V power output, leaving the others to wander according to their applied loads (they're simply tapped off different windings of the output transformer, they have no regulation of their own).
, and the speed of core-voltage drop does not keep up with frequency bumps (heat is square of frequency for CMOS gates).
Power in CMOS gates is linearly proportional to the frequency and the square of the *voltage*.
Since the majority of power dissipation in CMOS devices comes from charging and discharging their parasitic capacitance this is fairly obvious when taking into account the formula for energy in a capacitor 1/2*C*V^2. There is also the small in comparison power dissipation due to the ohmic resistance of the gates, which is more or less constant, no matter the frequency.
Calling it the Iron Ring ceremony is more accurate than calling it "The Kipling". However when I went through the ceremony, I believe the formal name for it was "The Ritual of the Calling of the Engineer".
That's probably not a typo, although it is an incomplete specification; there should be a value for the current ripple that the lifetime is specified at. The greater the ripple current, the lower the life-expectancy.
It's up to the designers who use the components to ensure that the ripple is low enough to give the lifespan required. As I recall, there also tends to be knee in the ripple voltage vs lifetime curve, for a minor change in ripple voltage there could be a drastic reduction in longevity.
Here's another linkdetailing the booster improvements.
Here's a link to some SRB technical documentation, very good reading for the engineer types.
There is much more documentation available at this site pertaining to all of the shuttle's systems for the those interested.
It is entirely possible for devices like an MD player to interfere with radio equipment. I once encountered a problem where a Sony CD player interfered with a ham radio receiver in the 2M band (144-148 Mhz), you could even hear the music work it's way through the demodulator of the receiver. This was probably due to harmonics from the delta-sigma DAC extending into the VHF range. Since the aircraft voice communication band is in the low VHF range as well (108-136MHz), I find it entirely plausible that an obstensibly non-transmitting device can interfere with radio communications.
Yes, but can they be trained to sort tiny screws in space?
Nowadays, most of Air force one's communications take place over satellite links, but they still use the standard military/civilian aircraft frequencies, since they need to communicate with the air-traffic control system. Here's a link with information on AF1's older communication systems that operate in the UHF band.
Global Thermoelectric has had a wide range of these systems available for quite some time.
While the Mars rover itself didn't generate electricity from a nuclear source, there were some small radioisotope pieces onboard acting as heaters to provide thermal regulation. It's been awhile, but I recall that they produced on the order of a few watts of heat.
As an electrical engineer I have to chip in and say that the parent to this post is more correct. The majority of the losses in your average wall-wart are from the hysterisis (eddy-current) losses in the the transformer core and resistance in the windings. The capacitors are pretty much a non-issue; even the cheapest varieties are about the most efficient parts you're going to find in a 60Hz power supply. Capacitor efficiency typically only becomes an issue in high frequency switching supply design, then the ESR (Equivalent Series Resistance) takes on relevance.
It is usually discouraged to use X-10 for loads like heaters and motors because the standard protocol doesn't acknowledge sent commands. If a command didn't make it through, the sender is unaware of this and could leave the controlled device operating in an unsafe way. Even worse, if a glitch turns on a module, your heater or motor could fire up for no apparent reason.
Not necessarily. Only asynchronous protocols (RS-232 and the like) need the extra stop and start bits. Cable modems use modulation schemes where the clock can be derived from the signal, making the start/stop bits unnecessary.
The Orbcomm corporation operates a system that uses text and data transmission for use like you describe. Their transceivers are a little larger than a Blackberry, but are still quite portable. The system also seems to be used extensively for remote telemetry purposes, to which it is especially suited.
I recall reading about the development of ceramic based engines a few years back. The ceramics had the the potential of allowing higher combustion temperatures while using using leaner fuel mixtures. While these higher temperatures allow for higher thermodynamic efficiencies they also promote the creation of nitrogen oxides, to the point of making the engines too dirty to pass emissions standards. No real conspiracies of suppressed technology here, just real technical/regulatory issues.