Correct. Someday it would be cool to try convection , for example, or a conducting inner core (right now ours is hollow stainless and we're using differential rotation to drive the flow.)
And actually, a solid iron core at 100C temperature is probably not a good model of the Earth's inner core. I'm certainly not an expert on the particular state of iron at Earth's core temperatures and pressures but it's very likely to be non-ferromagnetic. It's certainly above the Curie temperature of iron at ordinary pressures!
A solid conducting core that wasn't ferromagnetic would be more appropriate. We thought about using copper clad aluminum (may seem odd, but it was for weight reasons) but it just wasn't practical, at least not at first.
Take a tour of DuPont's plant in Niagara Falls NY sometime if they'll let you.
Giant vats of molten salt bubbling chlorine off the top into big fume hoods (they pipe it next door, I think Olin bottles it?) Whole place caked in salt and sodium oxide.
I'm fairly certain NaK is a significant autoignition risk compared to Sodium. Sodium at the temperatures we run the experiments at just slowly forms a white oxide crust as it freezes. I think NaK might just catch fire.
As far as gallium goes, if you've got $100 million dollars to spare and maybe another $5 million to upgrade our floor to take an extra 80 tons of load or so, we can talk;-) Looks like we'd also have to coat the sphere with something to prevent corrosion, but honestly, we never considered gallium so I didn't even know that;-)
It's used in a few smaller MHD experiments (as is the eutectic Galinstan); it's convenient (you can build the experiments out of acrylic) and some labs consider it worth the price, but it really doesn't scale well. Sodium is the way to go for large volume MHD experiments.
Oh, I'm not correcting for anything, I'm just not quite right about the number. I was talking about their dimensional electrical conductivities, mhos/meter or whatever, but it's not an order of magnitude.
Looks like it's just a factor of three different.
Maybe it's the magnetic Prandtl number that's different by a factor of 10 I guess. That's the ratio of the viscosity to the magnetic diffusivity.
But of course if we're going to split orders of magnitude I'm going to have to look things up carefully;-) Suffice it to say that Sodium doesn't have to be driven as hard to achieve the same Magnetic Reynolds number.
1)Price. Like others have said, it's a kilobuck a kilogram. Sodium is cheap, they just electrolyze salt in a plant in Niagara Falls where they can get cheap hydro power.
2) Density. I think a Gallium filled sphere would weigh 95 tons. Our campus structural engineer already had us shore up the floor for this one.
3) Electrical conductivity. Sodium is a factor of 10 more electrically conductive than Gallium.
"I'm no geophysicist, but I have a hunch gravity has a huge impact on the equation when it comes to the generation of the Earth's magnetic field."
Only in that the earth's core's flow is driven by convection (both/either thermal and compositional)
The static pressure field in a fluid cancels out gravitational effects, so in our experiment (I'm one of the graduate students who's been building the thing) there's just a slight increase in pressure as you go deeper in the sodium that doesn't change its electrical or hydrodynamic properties at all.
In the earth, buoyancy forces are important to stir up the core. In our experiment, we use differential rotation between a pair of spheres to drive the flow. That aspect is not particularly earthlike, but easier to put a lot of energy in.
I'm arguing that fat vs. non-fat is not the issue; that is, first of all, you can be skinny and be a resource glutton or be fat and be very conscientious of your impact on the world's resources, or anywhere in between.
You can even be fat and a *food* glutton, or at least an 18% extra consumer of food calories and still do better than breaking even in terms of actual energy consumption.
In fact, check this out:
Let's say 2000 Calories daily is a "base" for an active male. Maybe it's more or less, but it's coming in in the ballpark of the amount that males in the USA are fortunate enough to eat.
18% extra is an additional 360 Calories per day. As a power consumption (Calories/24 hours), that's about 17W.
So if you, on average, unnecessarily leave a 100W light bulb on somewhere for 4 hours a day... or 4 lightbulbs for an hour... whatever, you've done as much damage to the global energy budget as a fattie has.
Basically, my argument comes down to this: even if fat people do actually consume 18% more Calories on average (which I'm not sure I believe, by the way. A lot of fat girls are fat because they screwed up their metabolism with dieting), whether or not you leave your computer on 24/7 and the type of insulation you have in your house is going to swamp what you eat.
Fat people are just an easy scapegoat because we're allowed to hate them.
"I try to promote bike riding, and green house issues. But what can I say to an obese person, who can't face their own petty problems let alone the worlds and couldn't ride a bike if they wanted to"
Soo.. what do you say to a fat guy that has been riding a bike to work every day for the past eight years?
So, it's the fraction of the developed world's population that uses 18% more resources and not the developed world's 320% relative per-capita consumption that's the problem?
I'm a 300lb dude who rides a bike to work. I live in a metro area where 110lb women and 150lb guys drive their finely toned asses in two hours from their West Virginia, 5kW-power-use-when-no-one's-home McMansions in their big SUVs. I call bullshit.
I'm not interested in arguing whether or not fat people eat more, because no one bothers to look at the real facts about obesity anyway. Let's just assume I consume 18% more food resources than someone whose body fits the societal ideal.
That means I consume 377% of the food resources as someone in, say Kenya, as opposed to the thin, virtuous person's 320%.
I also consume 5% of the gasoline and a tiny fraction of the natural gas (small house) that my skinny, far-flung "suburb" counterparts use, but that wouldn't possibly factor in. Of course it doesn't factor in because the "obese" are always lying when they say they ride a bike or walk to work. That couldn't possibly be true. They're too disgusting for that to be true.
Hell, I'm a fattie... so I *produce* copious amounts of natural gas, don't I?
No one is proposing taking the networks away from the cell companies. They still get your money when you use Skype over their network.
What they would be taking away from the cell companies is the stranglehold they have on the data services you can get. I think Skype has a good case.
The advancement of wireless communication is not well served by the current crop of cellular providers. They want to use the data capacity they've built to charge you $3 for the latest Justin Timberlake video, and to let you get your email at exorbitant rates. They really don't want to be in the network business, they want to be in the gouging-for-fancy-things-you-don't-need business.
They built their networks believing (correctly, so far) that they'd have this stranglehold. That may have been an incentive for them at the beginning, and I'm sure that someone will say that the nationwide cellular networks wouldn't have been built without that incentive, and maybe they're right, but it's about time for there to be some regulation. The radio spectrum is a public, limited resource.
Purchasing exclusive rights to public property with expectation that you'd be able to hold and abuse those rights forever is a bad business plan. It would be different story, and would not require regulatory intervention if Skype could just go ahead and build their own cell towers and set up their own wireless data network to deliver wireless Skype to their customers. They can't do that. Neither can anyone else who might want to try to bring new services to customers over wireless. The cell phone companies have little incentive to innovate outside of getting people their ringtones and music videos faster. There will eventually be intervention here. I think the precedent referred to in the article is very strongly applicable here.
WCB, just get on the air when the rule change goes through.
You're automatically going to have general-level CW privileges on 80,40,15, and 10m as soon as the rule change happens, with no tests.
Make the most of it, and make your "exam" your first HF CW QSO instead!
Trust me, it will be scarier and more challenging than the test.
All the present no code technicians will automatically get privileges on HF when this thing goes through, and almost all those allocations will be Morse-only! I think it's really clever. You can easily upgrade to General or higher by taking more written tests, but current Tech licensees are going to get an instant upgrade when the new rules go into effect. Good incentive to learn the code anyway.
Morse communication by on-off keyed CW is hardly going to die. It requires only the most basic equipment and allows a very high signal-to-noise ratio while still being decodable by the human ear. Its narrow bandwidth makes very good use of transmitted RF power when what you're interested in is passing a small amount of information reliably under adverse conditions.
There are good narrowband digital modes being developed that can give Morse over CW a run for its money as far as getting through in low signal-to-noise situations, but some of them still fall apart in certain propagation situations.
A couple of nights ago, I heard Indiana and Maine on 144 MHz from here near Washington DC. The signals were propagated by scatter off of ionospheric ionization related to the strong auroral activity that was going on at the time. This mode of radio scatter causes any radio signal to break up into a severely buzzy, doppler-broadened hash of its former self. Morse can still be copied easily under these conditions; I'm not sure much else can.
As far as morons getting their licenses, listen to the entire range of 3600-4000kHz sometime before this rule goes through and ask yourself if the Morse exams are really keeping morons from getting their licenses.
Materials needed: Fans. Flexible duct. Duct tape (of course).
Procedure: Place fans in datacenter. Tape duct to fans. Route duct to office spaces.
Results: Save money on heating and cooling bills.....
Probably a good idea to fill up your gas tank before a storm that would kill the power... you can pull a lot of juice off of a running car. (This is what I would do with my HF radio right now, but I should really have a dedicated emergency power solution for it.)
You should get one of the hand-cranked radios anyway, to make sure you don't run out of power.
$50 and it even has a built in cellphone charger, which could likely be easily adapted to charge your handheld.
I think most of the HT's out there accept a pretty wide range of voltages for charging purposes.
Having the recieve capability is useful too, and it seems that you've got most of it covered in your handheld, but it doesn't hurt to have a backup. Someone on the ham emergency net needs to keep up with whatever (if anything) is coming over broadcast.
Incidentally, I have three 7 amp-hour gel-cell batteries I keep on float charge all the time. I can run my HT for a week, probably. I can even run the HF radio for short periods of time on these batteries (probably only low power CW operation though, my old Kenwood TS440s is not very good at converting DC to RF, efficiency-wise).
Need an excercise bike with a 12V 10-20A generator on it for battery charging, I think...
I don't know if it's no news... if this technology really works as advertised, it's substantial.
It appears that once you get the plant going, you just dump in catalyst and organic material, and you get diesel out. It runs on the fuel it produces, requiring about 10% of its output to keep the plant running.
***$1.13/gallon diesel***
Of course, how long it would take each shiny stainless plant as shown on alphakat.de to pay for itself, who knows, but if you were selling the product at prices competitive with today's fuel prices, you'd be making a tidy profit per gallon.
Slashdot Mirror
http://science.slashdot.org/article.pl?sid=08/06/28/1148245
You can shave 10 seconds off if the computer knows someone's going to walk up and boot it soon...
Correct. Someday it would be cool to try convection , for example, or a conducting inner core (right now ours is hollow stainless and we're using differential rotation to drive the flow.)
And actually, a solid iron core at 100C temperature is probably not a good model of the Earth's inner core. I'm certainly not an expert on the particular state of iron at Earth's core temperatures and pressures but it's very likely to be non-ferromagnetic. It's certainly above the Curie temperature of iron at ordinary pressures!
A solid conducting core that wasn't ferromagnetic would be more appropriate. We thought about using copper clad aluminum (may seem odd, but it was for weight reasons) but it just wasn't practical, at least not at first.
We try not to react it with anything at all !
Take a tour of DuPont's plant in Niagara Falls NY sometime if they'll let you.
Giant vats of molten salt bubbling chlorine off the top into big fume hoods (they pipe it next door, I think Olin bottles it?) Whole place caked in salt and sodium oxide.
I'm fairly certain NaK is a significant autoignition risk compared to Sodium. Sodium at the temperatures we run the experiments at just slowly forms a white oxide crust as it freezes. I think NaK might just catch fire.
;-) Looks like we'd also have to coat the sphere with something to prevent corrosion, but honestly, we never considered gallium so I didn't even know that ;-)
As far as gallium goes, if you've got $100 million dollars to spare and maybe another $5 million to upgrade our floor to take an extra 80 tons of load or so, we can talk
It's used in a few smaller MHD experiments (as is the eutectic Galinstan); it's convenient (you can build the experiments out of acrylic) and some labs consider it worth the price, but it really doesn't scale well. Sodium is the way to go for large volume MHD experiments.
Oh, I'm not correcting for anything, I'm just not quite right about the number. I was talking about their dimensional electrical conductivities, mhos/meter or whatever, but it's not an order of magnitude.
;-) Suffice it to say that Sodium doesn't have to be driven as hard to achieve the same Magnetic Reynolds number.
Looks like it's just a factor of three different.
Maybe it's the magnetic Prandtl number that's different by a factor of 10 I guess. That's the ratio of the viscosity to the magnetic diffusivity.
But of course if we're going to split orders of magnitude I'm going to have to look things up carefully
Three major reasons:
1)Price. Like others have said, it's a kilobuck a kilogram. Sodium is cheap, they just electrolyze salt in a plant in Niagara Falls where they can get cheap hydro power.
2) Density. I think a Gallium filled sphere would weigh 95 tons. Our campus structural engineer already had us shore up the floor for this one.
3) Electrical conductivity. Sodium is a factor of 10 more electrically conductive than Gallium.
We can heat the whole thing up to a temperature as high as 200C after we've drained most of the water. Easy to dry it out.
Don't worry, Ph.D. doesn't do me much good if I die...
"I'm no geophysicist, but I have a hunch gravity has a huge impact on the equation when it comes to the generation of the Earth's magnetic field."
Only in that the earth's core's flow is driven by convection (both/either thermal and compositional)
The static pressure field in a fluid cancels out gravitational effects, so in our experiment (I'm one of the graduate students who's been building the thing) there's just a slight increase in pressure as you go deeper in the sodium that doesn't change its electrical or hydrodynamic properties at all.
In the earth, buoyancy forces are important to stir up the core. In our experiment, we use differential rotation between a pair of spheres to drive the flow. That aspect is not particularly earthlike, but easier to put a lot of energy in.
Boy, you're totally right. Factor of ten off... oops. So there you go. 3200%
I'm arguing that fat vs. non-fat is not the issue; that is, first of all, you can be skinny and be a resource glutton or be fat and be very conscientious of your impact on the world's resources, or anywhere in between.
You can even be fat and a *food* glutton, or at least an 18% extra consumer of food calories and still do better than breaking even in terms of actual energy consumption.
In fact, check this out:
Let's say 2000 Calories daily is a "base" for an active male. Maybe it's more or less, but it's coming in in the ballpark of the amount that males in the USA are fortunate enough to eat.
18% extra is an additional 360 Calories per day. As a power consumption (Calories/24 hours), that's about 17W.
So if you, on average, unnecessarily leave a 100W light bulb on somewhere for 4 hours a day... or 4 lightbulbs for an hour... whatever, you've done as much damage to the global energy budget as a fattie has.
Basically, my argument comes down to this: even if fat people do actually consume 18% more Calories on average (which I'm not sure I believe, by the way. A lot of fat girls are fat because they screwed up their metabolism with dieting), whether or not you leave your computer on 24/7 and the type of insulation you have in your house is going to swamp what you eat.
Fat people are just an easy scapegoat because we're allowed to hate them.
"I try to promote bike riding, and green house issues. But what can I say to an obese person, who can't face their own petty problems let alone the worlds and couldn't ride a bike if they wanted to"
Soo.. what do you say to a fat guy that has been riding a bike to work every day for the past eight years?
Asshole.
So, it's the fraction of the developed world's population that uses 18% more resources and not the developed world's 320% relative per-capita consumption that's the problem?
I'm a 300lb dude who rides a bike to work. I live in a metro area where 110lb women and 150lb guys drive their finely toned asses in two hours from their West Virginia, 5kW-power-use-when-no-one's-home McMansions in their big SUVs. I call bullshit.
I'm not interested in arguing whether or not fat people eat more, because no one bothers to look at the real facts about obesity anyway. Let's just assume I consume 18% more food resources than someone whose body fits the societal ideal.
That means I consume 377% of the food resources as someone in, say Kenya, as opposed to the thin, virtuous person's 320%.
I also consume 5% of the gasoline and a tiny fraction of the natural gas (small house) that my skinny, far-flung "suburb" counterparts use, but that wouldn't possibly factor in. Of course it doesn't factor in because the "obese" are always lying when they say they ride a bike or walk to work. That couldn't possibly be true. They're too disgusting for that to be true.
Hell, I'm a fattie... so I *produce* copious amounts of natural gas, don't I?
*fart*
Whoops. Excuse me. I should bottle that.
If you really want to be pedantic about this "Gigabytes per month" is a unit of bandwidth. From good 'ol Google Calculator:
;-)
250 (gigabytes per month) = 0.77878308 megabits per second.
Not bandwidth?
OK... maps&atlases music = cool. maps&atlases website = difficult.
No one is proposing taking the networks away from the cell companies. They still get your money when you use Skype over their network.
What they would be taking away from the cell companies is the stranglehold they have on the data services you can get. I think Skype has a good case.
The advancement of wireless communication is not well served by the current crop of cellular providers. They want to use the data capacity they've built to charge you $3 for the latest Justin Timberlake video, and to let you get your email at exorbitant rates. They really don't want to be in the network business, they want to be in the gouging-for-fancy-things-you-don't-need business.
They built their networks believing (correctly, so far) that they'd have this stranglehold. That may have been an incentive for them at the beginning, and I'm sure that someone will say that the nationwide cellular networks wouldn't have been built without that incentive, and maybe they're right, but it's about time for there to be some regulation. The radio spectrum is a public, limited resource.
Purchasing exclusive rights to public property with expectation that you'd be able to hold and abuse those rights forever is a bad business plan. It would be different story, and would not require regulatory intervention if Skype could just go ahead and build their own cell towers and set up their own wireless data network to deliver wireless Skype to their customers. They can't do that. Neither can anyone else who might want to try to bring new services to customers over wireless. The cell phone companies have little incentive to innovate outside of getting people their ringtones and music videos faster. There will eventually be intervention here. I think the precedent referred to in the article is very strongly applicable here.
"Let's see what happens when a nuke war EMP knocks out all our IC-based systems and we have no tube radios for commo."
Uhhh... no, let's not. I'd like to avoid the whole nuke-war thing.
plus I'd rather have an Elecraft K2 stored in a Faraday cage if it were to happen.
Tube rigs are great at surviving EMP, but you're not going to run one off your car battery for too long!
That said, i'm 27, ham for 11 years, and about 80% CW op.
Dan, N3OX
WCB, just get on the air when the rule change goes through.
You're automatically going to have general-level CW privileges on 80,40,15, and 10m as soon as the rule change happens, with no tests. Make the most of it, and make your "exam" your first HF CW QSO instead!
Trust me, it will be scarier and more challenging than the test.
Dan, N3OX
All the present no code technicians will automatically get privileges on HF when this thing goes through, and almost all those allocations will be Morse-only! I think it's really clever. You can easily upgrade to General or higher by taking more written tests, but current Tech licensees are going to get an instant upgrade when the new rules go into effect. Good incentive to learn the code anyway.
Morse communication by on-off keyed CW is hardly going to die. It requires only the most basic equipment and allows a very high signal-to-noise ratio while still being decodable by the human ear. Its narrow bandwidth makes very good use of transmitted RF power when what you're interested in is passing a small amount of information reliably under adverse conditions.
There are good narrowband digital modes being developed that can give Morse over CW a run for its money as far as getting through in low signal-to-noise situations, but some of them still fall apart in certain propagation situations. A couple of nights ago, I heard Indiana and Maine on 144 MHz from here near Washington DC. The signals were propagated by scatter off of ionospheric ionization related to the strong auroral activity that was going on at the time. This mode of radio scatter causes any radio signal to break up into a severely buzzy, doppler-broadened hash of its former self. Morse can still be copied easily under these conditions; I'm not sure much else can. As far as morons getting their licenses, listen to the entire range of 3600-4000kHz sometime before this rule goes through and ask yourself if the Morse exams are really keeping morons from getting their licenses.
73,
Dan
N3OX, formerly N3UMH
Materials needed: Fans. Flexible duct. Duct tape (of course).
Procedure: Place fans in datacenter. Tape duct to fans. Route duct to office spaces.
Results: Save money on heating and cooling bills.....
Probably a good idea to fill up your gas tank before a storm that would kill the power... you can pull a lot of juice off of a running car. (This is what I would do with my HF radio right now, but I should really have a dedicated emergency power solution for it.)
You should get one of the hand-cranked radios anyway, to make sure you don't run out of power.
$50 and it even has a built in cellphone charger, which could likely be easily adapted to charge your handheld.
I think most of the HT's out there accept a pretty wide range of voltages for charging purposes.
Having the recieve capability is useful too, and it seems that you've got most of it covered in your handheld, but it doesn't hurt to have a backup. Someone on the ham emergency net needs to keep up with whatever (if anything) is coming over broadcast.
Incidentally, I have three 7 amp-hour gel-cell batteries I keep on float charge all the time. I can run my HT for a week, probably. I can even run the HF radio for short periods of time on these batteries (probably only low power CW operation though, my old Kenwood TS440s is not very good at converting DC to RF, efficiency-wise).
Need an excercise bike with a 12V 10-20A generator on it for battery charging, I think...
I don't know if it's no news... if this technology really works as advertised, it's substantial.
It appears that once you get the plant going, you just dump in catalyst and organic material, and you get diesel out. It runs on the fuel it produces, requiring about 10% of its output to keep the plant running.
***$1.13/gallon diesel***
Of course, how long it would take each shiny stainless plant as shown on alphakat.de to pay for itself, who knows, but if you were selling the product at prices competitive with today's fuel prices, you'd be making a tidy profit per gallon.