3) Any old technician with a brain in their head can run DC power feeds to equipment relatively safely due to the low voltages involved. AC power work of any kind should have a qualified electrician involved.
I have to disagree here the lower voltage does mean the risk of electric shock is (mostly) removed but it also increases the current involved and hence increases the risk of fire. DC is also far more prone to arcing than AC. Lead acid batteries can be especially nasty things due to high short circuit currents.
It may be that in some jurisdictions there is less regulatory overhead to working on a DC system due to the fact that less people are doing it (regulations are generally created as a result of people fucking up) but I wouldn't really say it is safer to work on.
That is true but while accidental connection (either through miswiring or damaged wiring) of a 120V appliance to a 240V supply may destroy the appliance it is unlikely to cause serious injury.
OTOH connection of a 12V DC system (where noone cares about stopping people touching the live parts of the connectors) to a 120V or 240V system could be a lot more dangerous.
But I don't think that is the biggest issue, you would just have to treat 12V wiring like data/telecoms wiring and keep it seperate from mains wiring.
The real issues with running 12V arround the home are resitive losses (remember these are much worse in lower voltage systems unless you use massive cables), and losses from the extra conversions steps (you have to convert from mains to 12V to whatever the devices want) and the fact that it would cost a lot of money to do for no real benefit.
Wall warts have improved a LOT in recent years, I just looked up a cheap wall wart on rapid and saw "no load current less than 0.5W" as an advertised feature.
For those of us with a modest knowledge of electrical devices, what is it that *prevents* these devices from running DC?
induction motors are cheap and reliable but they need AC to run. Conventional DC motors are less reliable because they have brush wear.
Of course the high end stuff uses inverter drives anyway because that allows greater efficiency over a range of operating speeds (especially as the inverter output can be three phase whereas in most domestic situations a direct mains fed motor would have to be single phase) so they could probablly be designed for either AC or DC incoming.
AC was chosen over DC so many years ago based off of long distance transmission requirements.
AC was chosen over DC because it was much easier to perform voltage conversion on it. Back in the day the only way to convert DC voltages was motor-generator sets which were expensive and inefficient. Nowadays we tend to use switched mode power supplies anyway for small conversion requirements within the home because small transformers are not particually efficient but still for larger requirements and higher voltages transformers are hard to beat on efficiency, cost and reliability.
When they talk about losses, usually it's over long distance over a few miles or between substations
Losses can be quite significant even within a building, especially at lower voltages.
The problem is (assuming single phase AC or single ended DC here for simplicity, other systems are a little more complex but the main principle holds) for a given cable size and power consumption power losses go as the square of the (RMS) supply voltage. Conversely for a given power consumption and acceptable level of power loss the cable size required goes as the inverse square of voltage.
So a 48V system ends up needing 25 times as much copper as a 240V system to achieve the same losses. A 12V system would need 400 times as much copper as a 240V system to achieve the same losses. Of course using that much copper isn't very p
Also with 12V there may be a lot less cost in terms of replacing the server PSU's as it's already closer to what you already need
I doubt it's significant, you are going to want isolating PSUs in the servers to make sure DC return currents don't accidently go where they shouldn't.
*running a rackful of high end servers off 12V you could be talking THOUSANDS of amps per rack. So unless you want signal connectors welded in their sockets you need to keep VERY careful control of where that current goes.
It probably depends on how the bean counters decide to account for the cost of the wafer run.
Afaict what happens is a wafer run is ordered. Between binning and potentially having a mixture of designs on a wafer (masks can be pretty expensive) that wafer run will produce a variety of parts of differing performance.
So to determine a margin for an individual part you have to divide the cost of the wafer run between the different parts produced, how this division is done will determine how the profit margins for the individual parts look on the books. At one extreme you could apportion an equal part of the wafer run's cost to each part, at the other extreme you could assume that the high end chips are the main product and the lower end parts you get are just nice extras at no added cost.
Afaict in canada (and possiblly parts of the US too) it is common to reffer to power from the electricity grid as "hydro". I believe this is because those places historically got most of their electricity from hydroelectric dams.
It's not just about being used often, it's also about the pattern of use. A favorite video may be accessed pretty often but it's always read sequentially from beginning to end and the speed of reading is limited by the playback speed not the hard drive. So there is little point in putting it on a SSD. Program files (and associated program data files) otoh are read in a non-sequential pattern while the user is waiting for a program to start do something so you do want them on a SSD.
Are the caching algorithms smart enough to detect these different usage patterns and optimise accordingly? and is 8GB of solding state storage really sufficiant in a world where a typical windows install is larger than that?
I'd rather have all my apps (with the possible exception of larger games) on a SSD and have a HDD for media and possibly larger games. Yes in a laptop that would mean giving up the optical drive but IMO that is a sacrifice worth making.
Most laptops have space for two drives (by default HDD and optical). It's just for some reason few vendors seem to offer combinations out of the box that don't involve an internal optical drive.
The assumption that humans are biologically related to other animinals is pretty important to modern medicine. Based on that assumption we use animals as test beds for new treatmenets (a variety of animals are used which provide different compromises between cost and similarity to humans) before we try using them on humans.
More specifically the source to most versions of the stock version of the core of andriod is open. The remaining versions is probably burried in the VCS history somewhere but afaict you are on your own as regards finding them since they aren't tagged. Apps that form a key part of the user experiance are not open and neither are any customisations made for individual phones (other than bits that the GPL forces them to release).
It's certainly better than no source at all but I wouldn't describe it as an "open source project".
IMO this isn't so much about protecting consumers from restaurants as it is about protecting both restaurants and consumers from corruption further back in the supply chain. It only takes one corrupt guy in the supply chain to introduce fake produce and if he is far enough back in the supply chain he can probablly dissapear before his actions are traced back to him.
releases into groundwater can be even worse than releases into the air. so to really gain from burying it you would want to bury it below an impermeable layer of rock which in turn is below any local aquifers. Not impossible but bloody expensive.
Further nuclear power stations are fundamentally heat engines. Heat engines need a place to dump the waste heat and that place needs to be as cool as possible (heat engine efficiency is related to the ratio of Thot and Tcold). Realistically that means either a sea water heat exchanger or a cooling tower. Either has the pontential to cause releases of radioactive material if the shit really hits the fan (yes you try to have multiple loops but heat exchangers can melt).
What concerns me though is how will changes be managed? will it be possible to look at older versions? will an instructor be able to set a "default version" for his class to avoid unexpected changes?
That is just a pricing issue though. Netflix have taken those lumps already
And if netflix survives at the current pricing level what is stopping the content owners for cranking up the price again at the next renegotiation to force them back into losing money?
postage is no longer a flat rate for envelopes but is based on the size as well as the weight of the envelope
Postage was never a flat rate for envelopes, it was always based on weight. They just added dimensions to the critera as well making items that were the weight of a letter but larger in size and/or awkward in shape more expensive to send, presumably because they were a pain to handle (you can't put an awkward shaped package through an automatic sorting machine and if it won't go through the letter box the postman has to ring the doorbell and wait).
One thing it does do is make places think about not overpacking stuff. You can send a DVD in it's case in a thin padded envelope (which given the tough flexible plastic DVD cases are made out of is plenty of protected) as a "large letter" whereas if you just shove it in some huge box you will probablly end up paying "package" rates.
As more retail business moves online I predict we'll see more of this - partly to deal with increased costs (fuel, primarily I guess) but also as more retail stores move their business online the people who deliver the packages have a strong hold on a potentially lucrative sector.
Afaict the biggest problem for post offices is that they have large fixed costs (sending a postman down a street costs about the same regardless of how much he delivers to each address) so as mail volumes go down (and afaict the increase in packages from on-line sales is not enough to make up for the decrease in letters) either the price per item has to go up, the frequency of service has to go down or the government has to make up the difference. Worse increasing the price or decreasing the service can drive mail volume down further.
Note that the royal mail do not have a monopoly on delivering packages.
I think in the not too distant future the era of a postman travelling down pretty much every street every day will be gone replaced by some combination of commercial mail services in areas where they make financial sense (business areas), an occasional mail service for non-urgent stuff that has to be sent in paper form and courier services for the rest (and yes sending a letter by courior will be expensive so you will only do it when it absoloutely has to be both fast and on paper).
The problem as I understand it is copyright. In the US at least (dunno about other places) copyright only limits copying. So there is no way for the copyright owners to stop kiosk operators buying DVDs/blu-rays and renting them out.
Whereas a kiosk that burns disk would be at the mercy of copyright holders (just like netflix streaming is).
The whole printer drivers system really seems like a relic of a bygone era at least for network printers. Why should I have to install a special driver just on every machine (an action that requires admin privileges) just to be able to send print jobs to a printer?
Also while I don't personally like relying on cloud based services I can see that for normal users having a destination in the cloud they can send their print jobs to when away from home is rather useful. Like it or not most peoples networks are behind NAT or stateful fir walling so just accepting print jobs direct from the internet is not really practical.
Have you ever been to London, Paris or Copenhagen?
Have you ever been to the UK outside of the very center of a major city?
Yes there are places in the UK where public transport is quick and convinient, I'm pretty sure there are such places in america. However if you think that is the norm over here you have no idea what you are talking about.
I live near manchester in the UK and don't own a car. I take the train to uni (i'm a PHD student) every day. This works well for me but only because I chose a place to live right next to a rail station. If I want to pop out to the DIY store I have to catch a bus into town then walk out to the diy store (a fairly considerable walk) and if I want to buy anything big and heavy I have to arrange with my family to transport it, take time off from uni so I can get it delivered or pay extortionate prices (if the service is lost at all) to have it delivered out of hours. If I had a car I could just drive to the DIY shop and come back with some bits of wood to fix whatever it is that needs fixing.
Even in the london conurbation things aren't all that rosy for public transport once you start trying to do anything other than go to/from the city center. Try going from say watford to hertford. Either you take a slow bus or you go into london and back out again on the train/tube. Most of the east/west railway lines in the area north of were closed decades ago.
Sccording to transport-direct it takes more than twice as long to go from watford junction rail station to hertford north rail station (I also tried hertford east and that was even worse) by public transport as it takes by car add in some time for counting getting to/from the station at the end and waiting for the first train and you are looking at arround triple the time to do it by public transport as to do it by car.
In a car I see the freedom to go where I want when I want. Not where the public transport happens to go when the public transport happens to be running (public transport reduces considerablly in the evening and almost completely shuts down at night). I just can't justify the cost of learning to drive and getting a car right now.
Slashdot Mirror
3) Any old technician with a brain in their head can run DC power feeds to equipment relatively safely due to the low voltages involved. AC power work of any kind should have a qualified electrician involved.
I have to disagree here the lower voltage does mean the risk of electric shock is (mostly) removed but it also increases the current involved and hence increases the risk of fire. DC is also far more prone to arcing than AC. Lead acid batteries can be especially nasty things due to high short circuit currents.
It may be that in some jurisdictions there is less regulatory overhead to working on a DC system due to the fact that less people are doing it (regulations are generally created as a result of people fucking up) but I wouldn't really say it is safer to work on.
That is true but while accidental connection (either through miswiring or damaged wiring) of a 120V appliance to a 240V supply may destroy the appliance it is unlikely to cause serious injury.
OTOH connection of a 12V DC system (where noone cares about stopping people touching the live parts of the connectors) to a 120V or 240V system could be a lot more dangerous.
But I don't think that is the biggest issue, you would just have to treat 12V wiring like data/telecoms wiring and keep it seperate from mains wiring.
The real issues with running 12V arround the home are resitive losses (remember these are much worse in lower voltage systems unless you use massive cables), and losses from the extra conversions steps (you have to convert from mains to 12V to whatever the devices want) and the fact that it would cost a lot of money to do for no real benefit.
Wall warts have improved a LOT in recent years, I just looked up a cheap wall wart on rapid and saw "no load current less than 0.5W" as an advertised feature.
For those of us with a modest knowledge of electrical devices, what is it that *prevents* these devices from running DC?
induction motors are cheap and reliable but they need AC to run. Conventional DC motors are less reliable because they have brush wear.
Of course the high end stuff uses inverter drives anyway because that allows greater efficiency over a range of operating speeds (especially as the inverter output can be three phase whereas in most domestic situations a direct mains fed motor would have to be single phase) so they could probablly be designed for either AC or DC incoming.
AC was chosen over DC so many years ago based off of long distance transmission requirements.
AC was chosen over DC because it was much easier to perform voltage conversion on it. Back in the day the only way to convert DC voltages was motor-generator sets which were expensive and inefficient. Nowadays we tend to use switched mode power supplies anyway for small conversion requirements within the home because small transformers are not particually efficient but still for larger requirements and higher voltages transformers are hard to beat on efficiency, cost and reliability.
When they talk about losses, usually it's over long distance over a few miles or between substations
Losses can be quite significant even within a building, especially at lower voltages.
The problem is (assuming single phase AC or single ended DC here for simplicity, other systems are a little more complex but the main principle holds) for a given cable size and power consumption power losses go as the square of the (RMS) supply voltage. Conversely for a given power consumption and acceptable level of power loss the cable size required goes as the inverse square of voltage.
So a 48V system ends up needing 25 times as much copper as a 240V system to achieve the same losses. A 12V system would need 400 times as much copper as a 240V system to achieve the same losses. Of course using that much copper isn't very p
Also with 12V there may be a lot less cost in terms of replacing the server PSU's as it's already closer to what you already need
I doubt it's significant, you are going to want isolating PSUs in the servers to make sure DC return currents don't accidently go where they shouldn't.
*running a rackful of high end servers off 12V you could be talking THOUSANDS of amps per rack. So unless you want signal connectors welded in their sockets you need to keep VERY careful control of where that current goes.
It probably depends on how the bean counters decide to account for the cost of the wafer run.
Afaict what happens is a wafer run is ordered. Between binning and potentially having a mixture of designs on a wafer (masks can be pretty expensive) that wafer run will produce a variety of parts of differing performance.
So to determine a margin for an individual part you have to divide the cost of the wafer run between the different parts produced, how this division is done will determine how the profit margins for the individual parts look on the books. At one extreme you could apportion an equal part of the wafer run's cost to each part, at the other extreme you could assume that the high end chips are the main product and the lower end parts you get are just nice extras at no added cost.
Afaict in canada (and possiblly parts of the US too) it is common to reffer to power from the electricity grid as "hydro". I believe this is because those places historically got most of their electricity from hydroelectric dams.
place things that are used most often
It's not just about being used often, it's also about the pattern of use. A favorite video may be accessed pretty often but it's always read sequentially from beginning to end and the speed of reading is limited by the playback speed not the hard drive. So there is little point in putting it on a SSD. Program files (and associated program data files) otoh are read in a non-sequential pattern while the user is waiting for a program to start do something so you do want them on a SSD.
Are the caching algorithms smart enough to detect these different usage patterns and optimise accordingly? and is 8GB of solding state storage really sufficiant in a world where a typical windows install is larger than that?
I'd rather have all my apps (with the possible exception of larger games) on a SSD and have a HDD for media and possibly larger games. Yes in a laptop that would mean giving up the optical drive but IMO that is a sacrifice worth making.
Most laptops have space for two drives (by default HDD and optical). It's just for some reason few vendors seem to offer combinations out of the box that don't involve an internal optical drive.
that Humans are evolution from something else
The assumption that humans are biologically related to other animinals is pretty important to modern medicine. Based on that assumption we use animals as test beds for new treatmenets (a variety of animals are used which provide different compromises between cost and similarity to humans) before we try using them on humans.
The source is open.
More specifically the source to most versions of the stock version of the core of andriod is open. The remaining versions is probably burried in the VCS history somewhere but afaict you are on your own as regards finding them since they aren't tagged. Apps that form a key part of the user experiance are not open and neither are any customisations made for individual phones (other than bits that the GPL forces them to release).
It's certainly better than no source at all but I wouldn't describe it as an "open source project".
IMO this isn't so much about protecting consumers from restaurants as it is about protecting both restaurants and consumers from corruption further back in the supply chain. It only takes one corrupt guy in the supply chain to introduce fake produce and if he is far enough back in the supply chain he can probablly dissapear before his actions are traced back to him.
releases into groundwater can be even worse than releases into the air. so to really gain from burying it you would want to bury it below an impermeable layer of rock which in turn is below any local aquifers. Not impossible but bloody expensive.
Further nuclear power stations are fundamentally heat engines. Heat engines need a place to dump the waste heat and that place needs to be as cool as possible (heat engine efficiency is related to the ratio of Thot and Tcold). Realistically that means either a sea water heat exchanger or a cooling tower. Either has the pontential to cause releases of radioactive material if the shit really hits the fan (yes you try to have multiple loops but heat exchangers can melt).
I'll belive they are serious about truth in advertising when they stop virgin media from advertising cable modem service as fiber optic.
MP is member of parliment (reffering to a national parliment). MEP is member of european parliment.
Not that I think dell is in the right here but dell 30 inch monitors do exist.
Or they turned off optimisation because the code didnt work properly with them turned on.
What concerns me though is how will changes be managed? will it be possible to look at older versions? will an instructor be able to set a "default version" for his class to avoid unexpected changes?
That is just a pricing issue though. Netflix have taken those lumps already
And if netflix survives at the current pricing level what is stopping the content owners for cranking up the price again at the next renegotiation to force them back into losing money?
postage is no longer a flat rate for envelopes but is based on the size as well as the weight of the envelope
Postage was never a flat rate for envelopes, it was always based on weight. They just added dimensions to the critera as well making items that were the weight of a letter but larger in size and/or awkward in shape more expensive to send, presumably because they were a pain to handle (you can't put an awkward shaped package through an automatic sorting machine and if it won't go through the letter box the postman has to ring the doorbell and wait).
One thing it does do is make places think about not overpacking stuff. You can send a DVD in it's case in a thin padded envelope (which given the tough flexible plastic DVD cases are made out of is plenty of protected) as a "large letter" whereas if you just shove it in some huge box you will probablly end up paying "package" rates.
As more retail business moves online I predict we'll see more of this - partly to deal with increased costs (fuel, primarily I guess) but also as more retail stores move their business online the people who deliver the packages have a strong hold on a potentially lucrative sector.
Afaict the biggest problem for post offices is that they have large fixed costs (sending a postman down a street costs about the same regardless of how much he delivers to each address) so as mail volumes go down (and afaict the increase in packages from on-line sales is not enough to make up for the decrease in letters) either the price per item has to go up, the frequency of service has to go down or the government has to make up the difference. Worse increasing the price or decreasing the service can drive mail volume down further.
Note that the royal mail do not have a monopoly on delivering packages.
I think in the not too distant future the era of a postman travelling down pretty much every street every day will be gone replaced by some combination of commercial mail services in areas where they make financial sense (business areas), an occasional mail service for non-urgent stuff that has to be sent in paper form and courier services for the rest (and yes sending a letter by courior will be expensive so you will only do it when it absoloutely has to be both fast and on paper).
The problem as I understand it is copyright. In the US at least (dunno about other places) copyright only limits copying. So there is no way for the copyright owners to stop kiosk operators buying DVDs/blu-rays and renting them out.
Whereas a kiosk that burns disk would be at the mercy of copyright holders (just like netflix streaming is).
There was a flurry of news articles on /. and similar sites about it at the time. Turning them up now seems rather tricky though.
http://games.slashdot.org/story/04/10/23/0812224/half-life-2-retail-to-require-steam-activation is one example.
The whole printer drivers system really seems like a relic of a bygone era at least for network printers. Why should I have to install a special driver just on every machine (an action that requires admin privileges) just to be able to send print jobs to a printer?
Also while I don't personally like relying on cloud based services I can see that for normal users having a destination in the cloud they can send their print jobs to when away from home is rather useful. Like it or not most peoples networks are behind NAT or stateful fir walling so just accepting print jobs direct from the internet is not really practical.
Have you ever been to London, Paris or Copenhagen?
Have you ever been to the UK outside of the very center of a major city?
Yes there are places in the UK where public transport is quick and convinient, I'm pretty sure there are such places in america. However if you think that is the norm over here you have no idea what you are talking about.
I live near manchester in the UK and don't own a car. I take the train to uni (i'm a PHD student) every day. This works well for me but only because I chose a place to live right next to a rail station. If I want to pop out to the DIY store I have to catch a bus into town then walk out to the diy store (a fairly considerable walk) and if I want to buy anything big and heavy I have to arrange with my family to transport it, take time off from uni so I can get it delivered or pay extortionate prices (if the service is lost at all) to have it delivered out of hours. If I had a car I could just drive to the DIY shop and come back with some bits of wood to fix whatever it is that needs fixing.
Even in the london conurbation things aren't all that rosy for public transport once you start trying to do anything other than go to/from the city center. Try going from say watford to hertford. Either you take a slow bus or you go into london and back out again on the train/tube. Most of the east/west railway lines in the area north of were closed decades ago.
Sccording to transport-direct it takes more than twice as long to go from watford junction rail station to hertford north rail station (I also tried hertford east and that was even worse) by public transport as it takes by car add in some time for counting getting to/from the station at the end and waiting for the first train and you are looking at arround triple the time to do it by public transport as to do it by car.
In a car I see the freedom to go where I want when I want. Not where the public transport happens to go when the public transport happens to be running (public transport reduces considerablly in the evening and almost completely shuts down at night). I just can't justify the cost of learning to drive and getting a car right now.
Something to consider is that people in the UK vote based on where they live, not where they work.
So someone who lives under one council but works under another has no representation in the council they work under.
Does that actually exist?!
yes. £1.09 each
http://www.waitrose.com/shop/ProductView-10317-10001-110438-Cherry+%26+geranium+cupcake