The advantage of high voltage is that the current is lower leading to lower transmission losses for a given resistance or size of wire.
The advantage of AC is the ability to use a simple transformer to change the ratio between the voltage and the current as well as it's generation and use in polyphase alternators and motors.
You still share 50% of your genes with your full siblings because 25% is through your mother and 25% is through your father. From a genetic standpoint you should be just as related to your full siblings as your children.
The Supreme Court case Bailey v. Drexel Furniture Company, 259 U.S. 20 (1922) is worth reading when politicians propose this type of law. Basically, a law may not use punitive taxation for the purpose of regulation of an item or activity that would not otherwise be within the scope of regulation. For instance, if violent video games are protected speech, you may not regulate them by using punitive taxation. The same would apply to abortion or to firearms to the extent that they are protected. The power to tax is indeed the power to destroy.
Cas 4 spends more time compaired to what at what clock frequency?
Is not Cas 4 at 200 MHz ( 4 x 5 nS ) exactly the same amount of time as Cas 2 at 100 MHz ( 2 x 10 nS )? There may be something about DDR2 that makes it slower then DDR but having twice the Cas at twice the frequency does not appear to be the cause.
The latency issues between DDR and DDR2 have never been clear to me so maybe someone can explain it.
If you check http://www.lostcircuits.com/memory/ddrii/2.shtml and http://www.lostcircuits.com/memory/ddrii/6.shtml they show DDR2 using an I/O clock at twice the frequency of the DDR I/O clock and both using same core clock. The objective here is to double the I/O bandwidth using twice the I/O clock and doubling the width of the core. Given identical core timing, DDR2 would have twice the latency IN CLOCKS as DDR but this would actually equate to the same amount of time.
So excluding the differences in command timing and using the same core clock, would not the CaS latency in both technologies be the same in nanoseconds? CaS 4 in DDR2 looks like it should be equivalent to CaS 2 in DDR in the timing diagram.
I use m0n0wall as well but my DSL is in a different class at 768/768 and with a service level agreement. Using inbound and outbound traffic shaping with a throughput of 640/640 yields about a 20mS ping time into my ISP's network when the inbound and outbound traffic is saturated.
As you point out, it is not immediately obvious that inbound traffic shaping can work unless you have access to the other end of your DSL line but it is possible to do in a more limited way then outbound traffic shaping.
I suspect what is needed here is a way for you to continuously monitor your network latency to some point into your ISP's network and dynamically adjust your traffic shaper throughput so you can best take advantage of available network capacity.
It used to be possible to do what you describe however once track pitch became high enough they had to switch to using embedded servo data because head alignment was not longer consistent between platters. Not only is there platter to platter variation in track alignment but the tracks themselves are eccentric. The only way you can keep more then one head in alignment is to have more then one servo actuator.
The last drive I had with dedicated servo tracks was a Micropolis 8760E 5.25 inch full height drive. Note that these types of drives actually can be low level formatted since the servo data is not involved.
Re:Won't work well with significant others...
on
Barenaked USB Drive
·
· Score: 1
I have to second this. Anderson Powerpoles come in different sizes with the large ones being suitable for multi-hundred amp starter motor loads and such. I still use 0.068 molex connectors for my small stuff though with the smaller Anderson Powerpoles for loads above 1 or 2 amps.
1. The ohmic losses are equal to R(I^2) so you want the current to be as low as possible. This is why transmission lines are high voltage.
2. I am a little fuzzy on the specifics but the radiative losses go up with higher voltage when using AC. I suspect this could be modeled based on the impedance. At some point, the voltage is high enough that the cost of doing AC to DC and DC to AC conversion is less then the radiative losses. DC transmission lines do not suffer radiative losses.
3. DC to AC and AC to DC conversion is expensive in terms of complexity, cost, and efficiency compared to using transformers for step up and step down.
The result is that the transmission line between Sylmar and The Dalles is both DC and runs at a much higher voltage then an AC transmission line would.
The speed of propagation in a conductor depends on it's dielectric (the insulation surrounding it). In a vacuum this will be c but for insulators like polyethelyne used in RG-58 it will be 0.66 c. RG-62 uses air surrounded by polyethelyne and has a propagation speed of 0.86 c.
The use of silicon dioxide as a dielectric in integrated circuits leads to a speed of propagation of about 0.5 c which is why high performance processes replace it with other materials.
I do not particularly disagree with you on these points but do have some comments.
There is nothing the U.S. can do to stop these Countries/Unions just using there own alternate servers/protocols . ..
If this is the case, why do they need permission? If they believe that they should be maintaining their own DNS servers then maybe they should start doing so. They could even make the use of their servers manditory by their citizens. To me, it sounds more like they want excersize direct control over how U.S. citizens use the internet.
Just like other international treaties, internet control should therefor be handed to the U.N. so that no country can shout 'Foul play' at the U.S. and try and split the internet up which is surely the most likely scenario (over the distant future) with the current setup.
How does handing control over to the U.N. prevent this problem?
Efficiency is the advantage. One of the new advances that has helped to miniaturize "wall-wart" type AC power supplies is they use a "chopper" transistor to chop the 60 Hz AC into a much higher frequency. That higher frequency AC can be run through a much smaller transformer to get the required voltage out of it, with less waste heat generated.
The advantage is power density. For the same reason, aircraft power systems are 400 Hz instead of the 50 or 60 Hz used on land. Transformer, capacitor, and inductor size are inversely proportional to frequency for a given power level. If you have a weight or space constrained application, it can be well worth giving up some efficiency for increased power density. For space applications where waste heat has to be handled, all three criteria need to be considered.
Switching losses are proportional to frequency so in the best case doubling the frequency halves the mass of your converter while increasing the switching losses which are only a part of the total power conversion losses. Depending on the technology and topology of a switching power supply, there will be a sweet spot for switching frequency that yields the best efficiency. You can always sacrifice efficiency for power density.
I would have expected a high frequency distribution system to be just above 20 KHz. 100 KHz seems a little high to me but it is quite possible that the added cost of handling the higher frequency was more then worth the weight savings. DC has the advantage of being less complicated with fewer frequency compensation issues which sounds like what happened in the described test failure.
In general, each voltage conversion introduces it's own losses so if you can do it all in one jump you tend to be better off from an efficiency standpoint. For standard PC power supplies, the manufacturing volume leads to an advantage in per unit cost that is very difficult to compete against using a different architecture.
48 Volts DC is the obvious alternative standard because of the telecommunications infrastructure but the newer automobile DC standard which is lower is a possibility also.
The best bet for something to replace all of those external adaptors is probably the USB or Firewire connector. The problem is that USB is limited to 5 volts at 2.5 watts and Firewire has a wide range of 12 to 36 volts which complicates the internal design of anything using it. One reason manufacturers use external adaptors is that they can be used to get around UL certification because their product then only uses a low voltage supply.
Support what? Ridley's book has an entire chapter aptly named "Politics" discussing the various genes and proteins involved as well as the demographics of susceptible groups and transmission methods. I think the parent post was a gross oversimplification of what Ridley wrote so I suggest reading Ridley's book even if only for this one chapter.
There is an extensive bibliography but he lists three works in particular:
1. Rosalind Ridley and Harry Baker, Fatal Protein (Oxford University Press, 1998) 2. Richard Rhodes, Deadly Feasts (Simon and Schuster, 1997) 3. Robert Klitzman, The Trembling Mountain (Plenum, 1998)
Usually that is the case but the prion in question is VERY inert which is what led to contamination of surgical instruments and transmission of the disease. Standard autoclaving was not sufficient to destroy it. This is also what leads to the disease since the body can not break it down and it accumulates in the cell bodies eventually poisoning them.
The prion has to come into contact with the normal protien to replicate and it's effectiveness depends on the specific structure of both. Since different spieces have slightly different versions of the gene and protien, cross spieces transmission varies a great deal. Cows can relatively easily catch it from other cows but transmission between species has so far been much more difficult.
Just eating a high fat diet which hamburgers and milk would certainly contribute to can account for the earlier maturation of girls. The digestive system is very good about breaking down what you eat so any effect from the trace amounts of hormones in beef or milk would be very difficult to distinguish from a rich diet.
You can see this effect in reverse with women athletes in reverse where if their body fat level is low enough they cease menstruation.
Specifically, a lot of hormones are derivatives of cholesterol and it's level affects their production.
The problem with this scenerio is that if the amature radio bands are useless during non emergency times, the operators have no incentive or ability to maintain their operating skills and equipment.
It probably does not help that because of routing restrictions on BTX motherboards, they can not be used for Athlon 64 systems. AMD is not a majority of the market but given the choice of having 2 different motherboard form factors and staying with ATX, a lot of manufacturers may forgo BTX.
I probably should have been more clear. What I was getting at was because of various other concerns, the engines were poorly engineered and safety issues were deliberately ignored. Why would things have changed since then?
NASA promised the sky with the shuttle (fast turn around, high reliablity, and high throughput come to mind) and when they could not deliver what they had promised, systematically covered it up and ignored good engineering practices. Has this aspect of NASA changed in 20 years?
It may have been there intention to make the SSMEs reusable but from what I read in the original Feynman report they were designed so close or past the engineering of the time that they had to be completely rebuilt after every flight anyway. His description of how they redefined what a "failure" was when estimating how long the each engine could safely run still gives me the creeps.
I have actually dealt with the diode problem before but in a different way. I swamped the reverse recovery characteristics with 100pF of capacitance which still seems like a better solution then going to controlled recovery rectifiers on a 60Hz bridge. Doing this got rid of an annoying although faint background buzz that proved nearly impossible to filter out.
The op-amp change could depend on the circuit itself. If you bias the output to one side you can force an op-amp to run in class A mode instead of class AB or B and get good results without a premium op-amp. Any of the OPA627 generation including the LT1007 and LT1124 should work fine without bias although there are versions of these amplifiers which are characterized and designed specifically for audio.
If there are problems in the audio output, I would suspect poor circuit design instead of poor parts selection. Changing the bulk capacitors in the switching power supply would be the last step I would take trying to make improvements. Those capacitors have a limited lifetime and I would just end up replacing them again later.
Usually in states that permit using deadly force to stop a crime you either have to believe your life is in danger or someone else's life is in danger. This would include using deadly force to stop first degree arson (setting fire to an inhabited building) but not necessarily other felonies. Enforcement varies depending on the local district attorney and law enforcement so depending on the location, you could find yourself in a lot of legal trouble even if what you did was expressly permitted under the law.
A majority of the time spent in CCW classes is for studying the laws that apply in these situations.
The ones who understand the situation learn fast that the nail that sticks up is the one to get hammered. It is a prisoners dilemma in large. Most citizens stand to benefit from rational government but only those who attempt to change it will pay the price.
As I have posted before, a lot of this is the result of plurality in U.S. elections. Only Republicans or Democrats can realistically be elected and if you disagree with both you are not represented. One party would lead us down the road of religious fundamentalism and the other of socialism. The compromise we have now is worse then a lot of the alternatives but at least we are traveling more slowly because of it.
Imagine a different experiment though that is now or shortly to become feasible:
The FOXP2 gene on chromosome 7 is associated with speech and language impairment in humans. This gene in almost identical in all mammals so it alone is not responsible for brain development leading to language however in all the generations of mice, monkeys, orangutans, gorillas, and chimpanzees since they had a common ancestor it has only had 2 changes. One change was in the ancestor of mice and one was in the ancestor of orangutans. Since the split between chimpanzees and humans however, this gene has already had 2 changes and those changes look to have happened sometime after 200,000 years ago and all alternate versions of the gene in humans are now gone.
I am not going to address the ethics of this experiment but would not it be interesting to introduce this specifically human gene into other mammals to see exactly what effect it has? Even more interesting would be it's effect on chimpanzees.
Slashdot Mirror
The advantage of high voltage is that the current is lower leading to lower transmission losses for a given resistance or size of wire.
The advantage of AC is the ability to use a simple transformer to change the ratio between the voltage and the current as well as it's generation and use in polyphase alternators and motors.
You still share 50% of your genes with your full siblings because 25% is through your mother and 25% is through your father. From a genetic standpoint you should be just as related to your full siblings as your children.
The Supreme Court case Bailey v. Drexel Furniture Company, 259 U.S. 20 (1922) is worth reading when politicians propose this type of law. Basically, a law may not use punitive taxation for the purpose of regulation of an item or activity that would not otherwise be within the scope of regulation. For instance, if violent video games are protected speech, you may not regulate them by using punitive taxation. The same would apply to abortion or to firearms to the extent that they are protected. The power to tax is indeed the power to destroy.
c ourt=us&vol=259&invol=20/ USSC_CR_0259_0020_ZO.html
http://caselaw.lp.findlaw.com/cgi-bin/getcase.pl?
http://supct.law.cornell.edu/supct/html/historics
Cas 4 spends more time compaired to what at what clock frequency?
Is not Cas 4 at 200 MHz ( 4 x 5 nS ) exactly the same amount of time as Cas 2 at 100 MHz ( 2 x 10 nS )? There may be something about DDR2 that makes it slower then DDR but having twice the Cas at twice the frequency does not appear to be the cause.
The latency issues between DDR and DDR2 have never been clear to me so maybe someone can explain it.
If you check http://www.lostcircuits.com/memory/ddrii/2.shtml and http://www.lostcircuits.com/memory/ddrii/6.shtml they show DDR2 using an I/O clock at twice the frequency of the DDR I/O clock and both using same core clock. The objective here is to double the I/O bandwidth using twice the I/O clock and doubling the width of the core. Given identical core timing, DDR2 would have twice the latency IN CLOCKS as DDR but this would actually equate to the same amount of time.
So excluding the differences in command timing and using the same core clock, would not the CaS latency in both technologies be the same in nanoseconds? CaS 4 in DDR2 looks like it should be equivalent to CaS 2 in DDR in the timing diagram.
I use m0n0wall as well but my DSL is in a different class at 768/768 and with a service level agreement. Using inbound and outbound traffic shaping with a throughput of 640/640 yields about a 20mS ping time into my ISP's network when the inbound and outbound traffic is saturated.
As you point out, it is not immediately obvious that inbound traffic shaping can work unless you have access to the other end of your DSL line but it is possible to do in a more limited way then outbound traffic shaping.
I suspect what is needed here is a way for you to continuously monitor your network latency to some point into your ISP's network and dynamically adjust your traffic shaper throughput so you can best take advantage of available network capacity.
It used to be possible to do what you describe however once track pitch became high enough they had to switch to using embedded servo data because head alignment was not longer consistent between platters. Not only is there platter to platter variation in track alignment but the tracks themselves are eccentric. The only way you can keep more then one head in alignment is to have more then one servo actuator.
The last drive I had with dedicated servo tracks was a Micropolis 8760E 5.25 inch full height drive. Note that these types of drives actually can be low level formatted since the servo data is not involved.
Showing my age here but . . .
ECL (Emotional Chick Logic)
I have to second this. Anderson Powerpoles come in different sizes with the large ones being suitable for multi-hundred amp starter motor loads and such. I still use 0.068 molex connectors for my small stuff though with the smaller Anderson Powerpoles for loads above 1 or 2 amps.
There are few different issues:
1. The ohmic losses are equal to R(I^2) so you want the current to be as low as possible. This is why transmission lines are high voltage.
2. I am a little fuzzy on the specifics but the radiative losses go up with higher voltage when using AC. I suspect this could be modeled based on the impedance. At some point, the voltage is high enough that the cost of doing AC to DC and DC to AC conversion is less then the radiative losses. DC transmission lines do not suffer radiative losses.
3. DC to AC and AC to DC conversion is expensive in terms of complexity, cost, and efficiency compared to using transformers for step up and step down.
The result is that the transmission line between Sylmar and The Dalles is both DC and runs at a much higher voltage then an AC transmission line would.
The speed of propagation in a conductor depends on it's dielectric (the insulation surrounding it). In a vacuum this will be c but for insulators like polyethelyne used in RG-58 it will be 0.66 c. RG-62 uses air surrounded by polyethelyne and has a propagation speed of 0.86 c.
The use of silicon dioxide as a dielectric in integrated circuits leads to a speed of propagation of about 0.5 c which is why high performance processes replace it with other materials.
I do not particularly disagree with you on these points but do have some comments.
.
There is nothing the U.S. can do to stop these Countries/Unions just using there own alternate servers/protocols . .
If this is the case, why do they need permission? If they believe that they should be maintaining their own DNS servers then maybe they should start doing so. They could even make the use of their servers manditory by their citizens. To me, it sounds more like they want excersize direct control over how U.S. citizens use the internet.
Just like other international treaties, internet control should therefor be handed to the U.N. so that no country can shout 'Foul play' at the U.S. and try and split the internet up which is surely the most likely scenario (over the distant future) with the current setup.
How does handing control over to the U.N. prevent this problem?
Efficiency is the advantage. One of the new advances that has helped to miniaturize "wall-wart" type AC power supplies is they use a "chopper" transistor to chop the 60 Hz AC into a much higher frequency. That higher frequency AC can be run through a much smaller transformer to get the required voltage out of it, with less waste heat generated.
The advantage is power density. For the same reason, aircraft power systems are 400 Hz instead of the 50 or 60 Hz used on land. Transformer, capacitor, and inductor size are inversely proportional to frequency for a given power level. If you have a weight or space constrained application, it can be well worth giving up some efficiency for increased power density. For space applications where waste heat has to be handled, all three criteria need to be considered.
Switching losses are proportional to frequency so in the best case doubling the frequency halves the mass of your converter while increasing the switching losses which are only a part of the total power conversion losses. Depending on the technology and topology of a switching power supply, there will be a sweet spot for switching frequency that yields the best efficiency. You can always sacrifice efficiency for power density.
I would have expected a high frequency distribution system to be just above 20 KHz. 100 KHz seems a little high to me but it is quite possible that the added cost of handling the higher frequency was more then worth the weight savings. DC has the advantage of being less complicated with fewer frequency compensation issues which sounds like what happened in the described test failure.
In general, each voltage conversion introduces it's own losses so if you can do it all in one jump you tend to be better off from an efficiency standpoint. For standard PC power supplies, the manufacturing volume leads to an advantage in per unit cost that is very difficult to compete against using a different architecture.
48 Volts DC is the obvious alternative standard because of the telecommunications infrastructure but the newer automobile DC standard which is lower is a possibility also.
The best bet for something to replace all of those external adaptors is probably the USB or Firewire connector. The problem is that USB is limited to 5 volts at 2.5 watts and Firewire has a wide range of 12 to 36 volts which complicates the internal design of anything using it. One reason manufacturers use external adaptors is that they can be used to get around UL certification because their product then only uses a low voltage supply.
Support what? Ridley's book has an entire chapter aptly named "Politics" discussing the various genes and proteins involved as well as the demographics of susceptible groups and transmission methods. I think the parent post was a gross oversimplification of what Ridley wrote so I suggest reading Ridley's book even if only for this one chapter.
There is an extensive bibliography but he lists three works in particular:
1. Rosalind Ridley and Harry Baker, Fatal Protein (Oxford University Press, 1998)
2. Richard Rhodes, Deadly Feasts (Simon and Schuster, 1997)
3. Robert Klitzman, The Trembling Mountain (Plenum, 1998)
Usually that is the case but the prion in question is VERY inert which is what led to contamination of surgical instruments and transmission of the disease. Standard autoclaving was not sufficient to destroy it. This is also what leads to the disease since the body can not break it down and it accumulates in the cell bodies eventually poisoning them.
The prion has to come into contact with the normal protien to replicate and it's effectiveness depends on the specific structure of both. Since different spieces have slightly different versions of the gene and protien, cross spieces transmission varies a great deal. Cows can relatively easily catch it from other cows but transmission between species has so far been much more difficult.
Just eating a high fat diet which hamburgers and milk would certainly contribute to can account for the earlier maturation of girls. The digestive system is very good about breaking down what you eat so any effect from the trace amounts of hormones in beef or milk would be very difficult to distinguish from a rich diet.
You can see this effect in reverse with women athletes in reverse where if their body fat level is low enough they cease menstruation.
Specifically, a lot of hormones are derivatives of cholesterol and it's level affects their production.
The problem with this scenerio is that if the amature radio bands are useless during non emergency times, the operators have no incentive or ability to maintain their operating skills and equipment.
It probably does not help that because of routing restrictions on BTX motherboards, they can not be used for Athlon 64 systems. AMD is not a majority of the market but given the choice of having 2 different motherboard form factors and staying with ATX, a lot of manufacturers may forgo BTX.
I probably should have been more clear. What I was getting at was because of various other concerns, the engines were poorly engineered and safety issues were deliberately ignored. Why would things have changed since then?
NASA promised the sky with the shuttle (fast turn around, high reliablity, and high throughput come to mind) and when they could not deliver what they had promised, systematically covered it up and ignored good engineering practices. Has this aspect of NASA changed in 20 years?
It may have been there intention to make the SSMEs reusable but from what I read in the original Feynman report they were designed so close or past the engineering of the time that they had to be completely rebuilt after every flight anyway. His description of how they redefined what a "failure" was when estimating how long the each engine could safely run still gives me the creeps.
I have actually dealt with the diode problem before but in a different way. I swamped the reverse recovery characteristics with 100pF of capacitance which still seems like a better solution then going to controlled recovery rectifiers on a 60Hz bridge. Doing this got rid of an annoying although faint background buzz that proved nearly impossible to filter out.
The op-amp change could depend on the circuit itself. If you bias the output to one side you can force an op-amp to run in class A mode instead of class AB or B and get good results without a premium op-amp. Any of the OPA627 generation including the LT1007 and LT1124 should work fine without bias although there are versions of these amplifiers which are characterized and designed specifically for audio.
If there are problems in the audio output, I would suspect poor circuit design instead of poor parts selection. Changing the bulk capacitors in the switching power supply would be the last step I would take trying to make improvements. Those capacitors have a limited lifetime and I would just end up replacing them again later.
Usually in states that permit using deadly force to stop a crime you either have to believe your life is in danger or someone else's life is in danger. This would include using deadly force to stop first degree arson (setting fire to an inhabited building) but not necessarily other felonies. Enforcement varies depending on the local district attorney and law enforcement so depending on the location, you could find yourself in a lot of legal trouble even if what you did was expressly permitted under the law.
A majority of the time spent in CCW classes is for studying the laws that apply in these situations.
If only it were so easy.
The ones who understand the situation learn fast that the nail that sticks up is the one to get hammered. It is a prisoners dilemma in large. Most citizens stand to benefit from rational government but only those who attempt to change it will pay the price.
As I have posted before, a lot of this is the result of plurality in U.S. elections. Only Republicans or Democrats can realistically be elected and if you disagree with both you are not represented. One party would lead us down the road of religious fundamentalism and the other of socialism. The compromise we have now is worse then a lot of the alternatives but at least we are traveling more slowly because of it.
Imagine a different experiment though that is now or shortly to become feasible:
The FOXP2 gene on chromosome 7 is associated with speech and language impairment in humans. This gene in almost identical in all mammals so it alone is not responsible for brain development leading to language however in all the generations of mice, monkeys, orangutans, gorillas, and chimpanzees since they had a common ancestor it has only had 2 changes. One change was in the ancestor of mice and one was in the ancestor of orangutans. Since the split between chimpanzees and humans however, this gene has already had 2 changes and those changes look to have happened sometime after 200,000 years ago and all alternate versions of the gene in humans are now gone.
I am not going to address the ethics of this experiment but would not it be interesting to introduce this specifically human gene into other mammals to see exactly what effect it has? Even more interesting would be it's effect on chimpanzees.
For those who like references: Richard Dawkins, Nature Via Nurture, Chapter 8 and also http://www.evolutionpages.com/FOXP2_language.htm