Right now, the big Aluminum companies site their plants near hydro power, but could there be a wind farm with an aluminum plant in the middle of it? They might vary the rate of production as the wind rises and falls, but if that is taken into account during the design of the plant it shouldn't be a devastating problem.
No, they can't. Aluminum smelters are near hydroelectric dams for a reason: enormous amounts of consistent, inexpensive energy. Wind generators can not provide this.
You can't easily stop or slowdown a smelt in the middle of performing it, we are dealing with enormous amounts of energy and molten metal salts. If there are huge inconsistencies in the power then the process can be very inefficient and possibly even dangerous.
Wind power is extremely variable and can only be used to supplement the base load of a power generation system. You can do some tricks like storing over-generation in the form of air pressure, capacitors, gravity systems, or flywheels but those can be expensive and complicated.
The better answer is nuclear. There are tons of designs for small-scale nuclear power generators, they can easily be built close to the site of power consumption, many of the designs are low-maintenence, it has a very favorable power-to-price ratio, and the power output is extremely consistent. This is the reason that aluminum smelters are also often located next to nuclear power plants.
make wind power super cheap to build out of trash or common materials, easy to build yourself....
And horribly inefficient with lots of downtime and high maintenance costs.
The problems with wind power are manifold:
They are under variable loads and have lots of moving parts so they need to be precisely engineered and maintained.
They often need to be placed in inconvenient areas in order to capture enough wind, which makes them difficult to service.
The power output of wind generation is unpredictable and can't be used for base power.
Because the generators are put in out-of-way areas you have significant power transmission losses.
They disturb local weather patterns by lowering wind velocity and introducing eddies, which may or may not cause problems down the road if wind power becomes widespread.
It's horribly expensive, the only reason it might seem to be economical right now is because it is heavily subsidized by your tax dollars.
Wind power is not the slam-dunk that a lot of people think it is.
If you were going to test a fishing lure, would you use a "control group" consisting of trout, bass, pike, baleen whales, and tiger sharks? Would you then apply the results to all "fish", despite the fact that some of those weren't fish at all? I would hope not.
You can still use that data as a control, you just need to properly categorize the data before you use it. Coming back to cloud formations and controls what you'd need to do is classify each cloud, control or not, and then use the data appropriately.
Observe the type of cloud, the meteorologic conditions, and other pertinent data such as season, phase of the moon, natives chanting on the ground, whatever. You then compare your clouds that have been seeded against appropriate control clouds. Yes, this means you will need to either get a lot more data or just limit the clouds you pick to certain conditions and types. Meteorological research is slow, painstaking, and time-consuming because your laboratory doesn't fit into a building and you have to do a lot more work to properly isolate all variables.a
I'm not deep into the AGW/anti-AGW arguments (and not trying to start a flame war), but I thought that one of the anti-AGW arguments was that in general humans can't affect climate.
First off, there are morons on both sides. Some people loudly exclaim that humans have ruined everything and some roar that humans have no effect on their environment. Both points of view are ridiculous.
The more reasonable proponents of climate change assert that mankind has had a measurable, long-term effect on the environment that will be difficult to reverse and requires drastic and immediate measures to prevent a catastrophe. Opponents of this point of view argue that the environment has gone through many similar changes in the past and that there is no clear evidence that mankind is the cause of current short-term trends that have been observed.
Of course mankind can affect climate on a local, short-term scale, that's been established and shown many times. The question is whether or not there are any large-scale, long-term, potentially difficult to reverse or control changes. It's a tough question to answer because we really don't have a great understanding of this extremely complex system known as Earth. The fact that aircraft can effect cloud formations has been known for some time and new data is a good thing but it doesn't really give either side much real evidence either way.
I assume you are talking about captive portal systems. The are a way of having encryption without having to distribute a password. Certain captive portals allow individual device encryption and it's also device independent (meaning your device does not need to support WPA2 or other encryption).
They are also completely unnecessary. All they are doing is associating your device's MAC address with a profile, something they could do completely without a web page.
I believe the true purpose of the login web pages are to advertise who is providing the access, provide them with plausible deniability in case you do something unlawful because they have a link to their terms of service on the landing page, and to make a little cash by advertising more services. All of these are good reasons for having a login page but it doesn't make it any less annoying.
Please tell us you don't use the/. editor to compose posts.
Lol, I do actually. It's ok though, I do a select all and copy before I submit. That way if something goes wonky I still have my post and can do a quick re-submit. I've gotten into the habit of doing that with anything web-based.
Yes, it was a joke. I don't go to Starbucks because I don't like their coffee and I don't like their prices. I hit a local chain that has 24oz coffee (regular, flavored, any way you want it) for $2.13 including tax.
That's actually about the same price you'll pay for coffee at Starbucks, the flavored syrups are free if you use their cash card. "De gustibus non est disputandum" on the coffee, personally I'm more of a tea person but I'm not a huge fan of their coffee either.
My main point on the joke is that it's a standard complaint and it usually comes from people not comparing apples to apples. People look at the Starbucks menu and see drinks costing 4 or 5 bucks so they say to themselves "Starbucks is expensive". What they're doing is comparing expensive speciality drinks to what they think a plain cup of coffee should cost. Compare the Starbucks plain coffee to what you expect a plain coffee should cost and they are in the same ballpark.
Of course the process is still working here on Slashdot and you're free to make any joke or comment you want. It just doesn't seem fair to perpetuate stereotypes of any sort, even if it is a faceless corporate entity.
screaming bloody murder against MS for making it so hard to port their OS.
Also, it's not hard at all to run Mac OS X on non-Apple hardware. The main problem is that there aren't a ton of drivers out there for non-Apple hardware. All it takes is for people to write some drivers and making a "hackintosh" would be a lot easier.
It's less a matter of Apple making life difficult to install Mac OS X on other manufacturers hardware and more a matter of Apple only writes drivers for their hardware. Of course that's good business for Apple because why would they want to support other manufacturer's hardware sales over their own?
Oddly enough, if the situation were reversed, you'd (you meaning most of/.) probably be screaming bloody murder against MS for making it so hard to port their OS.
For years now Windows hasn't been able to run (directly) on Apple's hardware and I don't think most people even cared, including the ubiquitous "you" here on Slashdot.
If a company wants their software to only run on one platform then that's up to them, I've never had any problem with it. It's all a matter of what set of hardware the company supports. There will always be a small group of people who will try to beat those restrictions and as long as they don't do it in such a way that seriously undermines the original developer of the software then I don't have a problem with that either.
Hell if I know why people like these things though, all of the Apple kids look so uncomfortable trying to prop their ipads up with one arm while "1 finger pecking" at a software keyboard with the other.
The software keyboard isn't too bad for short entries. I wouldn't use it to write long papers or anything. If I was going to do that I'd get the keyboard/stand attachment which basically turns the iPad into something similar to a netbook.
The iPad is mostly meant to be a content consumption device that can do some extra stuff. It excels at that purpose but if you need a device to create content I'd recommend a real netbook or laptop.
I use a 15" Macbook Pro and it's easy to carry, has great battery life, and it's easy to code on. Plus it can run Windows if I ever need that. That's the real selling point for a Mac for me: the ability to easily run just about any modern operating system, even simultaneously with virtualization. Nothing beats being able to code and test Macintosh, Windows, and Linux applications on one machine.
Yeah, there are some non-Apple machines out there that you can get to run Mac OS X but I really don't feel like keeping on top of compatible drivers and operating system updates.
Now I can get a small cup of coffee and free WiFI for only $7!
Yeah, that's mildy funny and you scored some points with the moderators. Grats for finding the low-hanging fruit!
Honestly though, as long as you aren't getting all of those espresso shots, flavored syrups, and other strange add-ons the price of a plain coffee at Starbucks is about the same as the stuff at their competitors. A coffee the same size at Dunkin Donuts is about the same price as one at Starbucks.
If you really want to save money you can go to a diner or a local mom-and-pop place and get coffee for about 1/2 the price of any of the large chains. Of course, the quality of the coffee might wildly vary between one place and another so when visiting somewhere unfamiliar you are usually best off just paying the extra money for a sure thing.
As part of this commitment, Schultz recognized customers' desire for a better in store Wi-Fi experience and announced that on July 1, Starbucks will turn on one-click, free Wi-Fi through AT&T in all U.S. company operated stores.
Building on the Wi-Fi update, Schultz also revealed plans for a new online customer experience called the Starbucks Digital Network, in partnership with Yahoo!, which will debut later this fall. This online experience - available only in U.S. company operated Starbucks stores - will be unique in its content offerings, allowing customers free unrestricted access to various paid sites and services such as wsj.com, exclusive content and previews, free downloads, local community news and activities, on their laptops, tablets or smart phones.
So it's both free access to the entire internet and free, unrestricted access to sites that you might normally pay for such as wsj.com.
It's not "free unlimited access." It's "free unlimited access to select Starbucks-chosen sites, most of them you have to pay for."
You already get free, unrestricted access to any site if you use a Starbucks card. You get the card for free, throw a few bucks on it, and use it for purchases. As long as you make 1 purchase a month (of any amount) you get free access for the month. They also give you other perks like free addons (flavored syrup and such), free refills, and every so often they send you a card for a free drink of any kind you want.
I'm not big on using cards like this but they do compensate you pretty well for using it.
My big quibble with all of these "click to log on" types of systems is they are a pain in the butt. Say I just want to check my e-mail or do something else that's not HTTP, I can't do it unless I load up my web browser, visit any web site, get redirected to their landing page, and do their login dance. It's a huge waste of time, there should be some way for them to build their login directly into the wifi login to avoid HTTP if we aren't currently using it.
Not to mention that they all have some odd reasons for timing out the login and I'll be in the middle of doing something (like a Slashdot post!) and it fails because I have to re-login. What a pain in the ass!
Yes, there's a reason that it does nearly the same thing. Apple's Reader uses code from Readability. Apple credits them in their license agreement and the developers over at Arc90 are happy that Apple is using their code:
As we've already mentioned, we couldn't be happier that Apple has chosen to leverage our own Readability as a native feature in the Safari browser. As the debate around Safari Reader heats up, we thought we'd chime in and share some of our thoughts, motivations and aspirations for what reading can become on the Web.
You have to apply a sinc() function to each point in order to reconstruct the original waveform. The full formula is here: Whittaker-Shannon interpolation formula
Since you don't have an infinite future and past you need to choose a finite number of points to sum over and you will have a bit of error, especially at the beginning and end of the data. There are ways to suppress this sort of error which are beyond the scope of this discussion.
If you want to discuss it further you could e-mail that spreadsheet to colxgraff yat ftml dotz net - remove the xyz, yadda yadda. It's been a while since I've had to do this sort of thing by hand since, for the post part, the instrumentation has the filters and algorithms built-in and you just tune parameters to the application but once upon a time I had to build these sort of systems by hand.
Regardless of anyones personal opinion of computer OS's, Windows still rules in both the personal and business OS level.
I agree, that's why the Macbook is best. You can run Windows, Mac OS, Linux, BSD, and a whole host of other operating systems on it. Best of all worlds!
one assumes 44.1KHz is ok to reproduce 20KHz audio... This is WAY too simplistic. Take a ~15KHz sine wave and apply a phase shift to it. Sample it at 44.1KHz. Look at the amplitude modulation you get on the output. 44.1Khz is terrible for audio.
This is a fallacy. You can accurately sample any frequency by attenuating all the higher frequencies and sampling at a rate of double the signal frequency. When you reconstruct the samples properly you will get back the exact same signal as you sampled.
You should use a bit of overhead because it is difficult to construct an ideal low-pass filter. Because of this you will usually have some non-ideal attenuation of the signal near the cutoff frequency. 10% (40 kHz + 4.1 kHz = 44.1 kHz) is more than enough to cover this.
The main problems arise when a low-pass filter is improperly (or not) applied, the filter is not well-designed, or the Wittaker-Shannon Interpolation Formula is not applied at signal reconstruction. If a low-pass filter of 20 kHz is not used then when you sample at 40 kHz (or 44.1 kHz) then you will indeed get phase effects, especially with something that has a ton of higher order harmonics like a symbol.
In your example that I quoted what you didn't do is apply the interpolation formula. If you are looking at the raw samples then it will indeed look anti-aliased. The interpolation formula takes that anti-aliased sample and reconstructs the original waveform faithfully if you have followed all the steps of the Nyquist-Shannon Sampling Theorem.
(By the way, I'm an instrumental chemist and this is a very serious subject for instrument design. When you are running instrumentation to sample spectra you need to be extremely aware of your sampling methodology to avoid introducing artifacts into your data.)
Ahh yeah, it's been a while since I've encountered this problem and I was remembering it incorrectly. Once I ran through the calculations again I see what you are getting at. The sum of the force vectors always cancel each other out no matter where you are in a hollow object so there is no attraction to the shell once you are inside of it.
That center-of-mass assumption (point-source of force simplification) you are using doesnt work from inside the hollow sphere.
I wasn't thinking of the point-source simplification, I was thinking of the inverse square law. I was assuming that the closest spot would have a slightly greater attraction but I wasn't taking into account the fact that more of the force vectors would be opposing each other on that side than on the other, counterbalancing the inverse square law. The neat thing is that the two effects do exactly balance each other out, a fact I just didn't remember from when I was a physics major years ago.
You would be completely weightless inside a hollow earth.
Only if you were at the exact center of mass. If you were a bit outside that then you would be attracted to the nearest concentration of matter. The center of mass of a hollow object is akin to being a ball at the top of a hill, if you are a little off to one side you will roll down it. It's not a stable point at all.
Now, until you actually hit something, you will experience weightlessness. Once you come to rest you will have weight (and it may be spread all over the place if you had enough velocity).
Years and years of wondering why we've got 16, 32, 48 and crazily 44.1kHz, solved in a Slashdot post.
Yeah there's a lot of "black magic" involved in signal theory that doesn't make sense on the face of it but once you dig deeper you develop a great respect for the engineers who have developed these solutions. I'm constantly amazed at the innovation and clever tricks that have been developed over the years.
The old graphics cards that did less than 8 bits per color channel would use more bits for green and the fewest for blue - which is because the eye is least sensitive to blue. Most sensitive to green so it needed more bits.
Which is exactly why they use double the green pixels. Now instead of one element out of every three pixels it's now one out of every two.
This means that the green pixels are not only more frequent in the pixel array, they also can show more levels of green in a single group. Both of these factors work with the eye's increased sensitivity to green to produce better images.
Slashdot Mirror
Right now, the big Aluminum companies site their plants near hydro power, but could there be a wind farm with an aluminum plant in the middle of it? They might vary the rate of production as the wind rises and falls, but if that is taken into account during the design of the plant it shouldn't be a devastating problem.
No, they can't. Aluminum smelters are near hydroelectric dams for a reason: enormous amounts of consistent, inexpensive energy. Wind generators can not provide this.
You can't easily stop or slowdown a smelt in the middle of performing it, we are dealing with enormous amounts of energy and molten metal salts. If there are huge inconsistencies in the power then the process can be very inefficient and possibly even dangerous.
Wind power is extremely variable and can only be used to supplement the base load of a power generation system. You can do some tricks like storing over-generation in the form of air pressure, capacitors, gravity systems, or flywheels but those can be expensive and complicated.
The better answer is nuclear. There are tons of designs for small-scale nuclear power generators, they can easily be built close to the site of power consumption, many of the designs are low-maintenence, it has a very favorable power-to-price ratio, and the power output is extremely consistent. This is the reason that aluminum smelters are also often located next to nuclear power plants.
make wind power super cheap to build out of trash or common materials, easy to build yourself....
And horribly inefficient with lots of downtime and high maintenance costs.
The problems with wind power are manifold:
Wind power is not the slam-dunk that a lot of people think it is.
...but if I remember correctly, the same A4 chip in the iPad is supposed to be showing up in the new iPhone. Can someone confirm?
Apple does list the processor in the new iPhone 4G as being an A4:
iPhone Design
If you were going to test a fishing lure, would you use a "control group" consisting of trout, bass, pike, baleen whales, and tiger sharks? Would you then apply the results to all "fish", despite the fact that some of those weren't fish at all? I would hope not.
You can still use that data as a control, you just need to properly categorize the data before you use it. Coming back to cloud formations and controls what you'd need to do is classify each cloud, control or not, and then use the data appropriately.
Observe the type of cloud, the meteorologic conditions, and other pertinent data such as season, phase of the moon, natives chanting on the ground, whatever. You then compare your clouds that have been seeded against appropriate control clouds. Yes, this means you will need to either get a lot more data or just limit the clouds you pick to certain conditions and types. Meteorological research is slow, painstaking, and time-consuming because your laboratory doesn't fit into a building and you have to do a lot more work to properly isolate all variables.a
I'm not deep into the AGW/anti-AGW arguments (and not trying to start a flame war), but I thought that one of the anti-AGW arguments was that in general humans can't affect climate.
First off, there are morons on both sides. Some people loudly exclaim that humans have ruined everything and some roar that humans have no effect on their environment. Both points of view are ridiculous.
The more reasonable proponents of climate change assert that mankind has had a measurable, long-term effect on the environment that will be difficult to reverse and requires drastic and immediate measures to prevent a catastrophe. Opponents of this point of view argue that the environment has gone through many similar changes in the past and that there is no clear evidence that mankind is the cause of current short-term trends that have been observed.
Of course mankind can affect climate on a local, short-term scale, that's been established and shown many times. The question is whether or not there are any large-scale, long-term, potentially difficult to reverse or control changes. It's a tough question to answer because we really don't have a great understanding of this extremely complex system known as Earth. The fact that aircraft can effect cloud formations has been known for some time and new data is a good thing but it doesn't really give either side much real evidence either way.
Mmm, yeah, that's a good idea actually. Safari kinda sorta has it but only for common web forms - stuff like name, address, etc.
Definitely a feature to suggest for your favorite browser.
SBC is Starbucks, they were bought out nearly 10 years ago.
I assume you are talking about captive portal systems. The are a way of having encryption without having to distribute a password. Certain captive portals allow individual device encryption and it's also device independent (meaning your device does not need to support WPA2 or other encryption).
They are also completely unnecessary. All they are doing is associating your device's MAC address with a profile, something they could do completely without a web page.
I believe the true purpose of the login web pages are to advertise who is providing the access, provide them with plausible deniability in case you do something unlawful because they have a link to their terms of service on the landing page, and to make a little cash by advertising more services. All of these are good reasons for having a login page but it doesn't make it any less annoying.
Please tell us you don't use the /. editor to compose posts.
Lol, I do actually. It's ok though, I do a select all and copy before I submit. That way if something goes wonky I still have my post and can do a quick re-submit. I've gotten into the habit of doing that with anything web-based.
Yes, it was a joke. I don't go to Starbucks because I don't like their coffee and I don't like their prices. I hit a local chain that has 24oz coffee (regular, flavored, any way you want it) for $2.13 including tax.
That's actually about the same price you'll pay for coffee at Starbucks, the flavored syrups are free if you use their cash card. "De gustibus non est disputandum" on the coffee, personally I'm more of a tea person but I'm not a huge fan of their coffee either.
My main point on the joke is that it's a standard complaint and it usually comes from people not comparing apples to apples. People look at the Starbucks menu and see drinks costing 4 or 5 bucks so they say to themselves "Starbucks is expensive". What they're doing is comparing expensive speciality drinks to what they think a plain cup of coffee should cost. Compare the Starbucks plain coffee to what you expect a plain coffee should cost and they are in the same ballpark.
Of course the process is still working here on Slashdot and you're free to make any joke or comment you want. It just doesn't seem fair to perpetuate stereotypes of any sort, even if it is a faceless corporate entity.
screaming bloody murder against MS for making it so hard to port their OS.
Also, it's not hard at all to run Mac OS X on non-Apple hardware. The main problem is that there aren't a ton of drivers out there for non-Apple hardware. All it takes is for people to write some drivers and making a "hackintosh" would be a lot easier.
It's less a matter of Apple making life difficult to install Mac OS X on other manufacturers hardware and more a matter of Apple only writes drivers for their hardware. Of course that's good business for Apple because why would they want to support other manufacturer's hardware sales over their own?
Oddly enough, if the situation were reversed, you'd (you meaning most of /.) probably be screaming bloody murder against MS for making it so hard to port their OS.
For years now Windows hasn't been able to run (directly) on Apple's hardware and I don't think most people even cared, including the ubiquitous "you" here on Slashdot.
If a company wants their software to only run on one platform then that's up to them, I've never had any problem with it. It's all a matter of what set of hardware the company supports. There will always be a small group of people who will try to beat those restrictions and as long as they don't do it in such a way that seriously undermines the original developer of the software then I don't have a problem with that either.
Hell if I know why people like these things though, all of the Apple kids look so uncomfortable trying to prop their ipads up with one arm while "1 finger pecking" at a software keyboard with the other.
The software keyboard isn't too bad for short entries. I wouldn't use it to write long papers or anything. If I was going to do that I'd get the keyboard/stand attachment which basically turns the iPad into something similar to a netbook.
The iPad is mostly meant to be a content consumption device that can do some extra stuff. It excels at that purpose but if you need a device to create content I'd recommend a real netbook or laptop.
I use a 15" Macbook Pro and it's easy to carry, has great battery life, and it's easy to code on. Plus it can run Windows if I ever need that. That's the real selling point for a Mac for me: the ability to easily run just about any modern operating system, even simultaneously with virtualization. Nothing beats being able to code and test Macintosh, Windows, and Linux applications on one machine.
Yeah, there are some non-Apple machines out there that you can get to run Mac OS X but I really don't feel like keeping on top of compatible drivers and operating system updates.
Starbucks is sure to burn the shit out of their beans.
Yeah, I agree that Starbucks coffee is usually heavily-roasted. I guess some people go for that kind of flavor.
I'll admit that it's not my thing but it's ok once in a while as an iced coffee with cream and sugar.
Now I can get a small cup of coffee and free WiFI for only $7!
Yeah, that's mildy funny and you scored some points with the moderators. Grats for finding the low-hanging fruit!
Honestly though, as long as you aren't getting all of those espresso shots, flavored syrups, and other strange add-ons the price of a plain coffee at Starbucks is about the same as the stuff at their competitors. A coffee the same size at Dunkin Donuts is about the same price as one at Starbucks.
If you really want to save money you can go to a diner or a local mom-and-pop place and get coffee for about 1/2 the price of any of the large chains. Of course, the quality of the coffee might wildly vary between one place and another so when visiting somewhere unfamiliar you are usually best off just paying the extra money for a sure thing.
It's not "free unlimited access." It's "free unlimited access to select Starbucks-chosen sites, most of them you have to pay for."
Oh, and if you go directly to the Starbucks press release linked in the article:
As part of this commitment, Schultz recognized customers' desire for a better in store Wi-Fi experience and announced that on July 1, Starbucks will turn on one-click, free Wi-Fi through AT&T in all U.S. company operated stores.
Building on the Wi-Fi update, Schultz also revealed plans for a new online customer experience called the Starbucks Digital Network, in partnership with Yahoo!, which will debut later this fall. This online experience - available only in U.S. company operated Starbucks stores - will be unique in its content offerings, allowing customers free unrestricted access to various paid sites and services such as wsj.com, exclusive content and previews, free downloads, local community news and activities, on their laptops, tablets or smart phones.
So it's both free access to the entire internet and free, unrestricted access to sites that you might normally pay for such as wsj.com.
It's not "free unlimited access." It's "free unlimited access to select Starbucks-chosen sites, most of them you have to pay for."
You already get free, unrestricted access to any site if you use a Starbucks card. You get the card for free, throw a few bucks on it, and use it for purchases. As long as you make 1 purchase a month (of any amount) you get free access for the month. They also give you other perks like free addons (flavored syrup and such), free refills, and every so often they send you a card for a free drink of any kind you want.
I'm not big on using cards like this but they do compensate you pretty well for using it.
My big quibble with all of these "click to log on" types of systems is they are a pain in the butt. Say I just want to check my e-mail or do something else that's not HTTP, I can't do it unless I load up my web browser, visit any web site, get redirected to their landing page, and do their login dance. It's a huge waste of time, there should be some way for them to build their login directly into the wifi login to avoid HTTP if we aren't currently using it.
Not to mention that they all have some odd reasons for timing out the login and I'll be in the middle of doing something (like a Slashdot post!) and it fails because I have to re-login. What a pain in the ass!
Yes, there's a reason that it does nearly the same thing. Apple's Reader uses code from Readability. Apple credits them in their license agreement and the developers over at Arc90 are happy that Apple is using their code:
Why We Built Readability
By Rich Ziade
As we've already mentioned, we couldn't be happier that Apple has chosen to leverage our own Readability as a native feature in the Safari browser. As the debate around Safari Reader heats up, we thought we'd chime in and share some of our thoughts, motivations and aspirations for what reading can become on the Web.
You have to apply a sinc() function to each point in order to reconstruct the original waveform. The full formula is here: Whittaker-Shannon interpolation formula
Since you don't have an infinite future and past you need to choose a finite number of points to sum over and you will have a bit of error, especially at the beginning and end of the data. There are ways to suppress this sort of error which are beyond the scope of this discussion.
If you want to discuss it further you could e-mail that spreadsheet to colxgraff yat ftml dotz net - remove the xyz, yadda yadda. It's been a while since I've had to do this sort of thing by hand since, for the post part, the instrumentation has the filters and algorithms built-in and you just tune parameters to the application but once upon a time I had to build these sort of systems by hand.
Regardless of anyones personal opinion of computer OS's, Windows still rules in both the personal and business OS level.
I agree, that's why the Macbook is best. You can run Windows, Mac OS, Linux, BSD, and a whole host of other operating systems on it. Best of all worlds!
one assumes 44.1KHz is ok to reproduce 20KHz audio... This is WAY too simplistic. Take a ~15KHz sine wave and apply a phase shift to it. Sample it at 44.1KHz. Look at the amplitude modulation you get on the output. 44.1Khz is terrible for audio.
This is a fallacy. You can accurately sample any frequency by attenuating all the higher frequencies and sampling at a rate of double the signal frequency. When you reconstruct the samples properly you will get back the exact same signal as you sampled.
You should use a bit of overhead because it is difficult to construct an ideal low-pass filter. Because of this you will usually have some non-ideal attenuation of the signal near the cutoff frequency. 10% (40 kHz + 4.1 kHz = 44.1 kHz) is more than enough to cover this.
The main problems arise when a low-pass filter is improperly (or not) applied, the filter is not well-designed, or the Wittaker-Shannon Interpolation Formula is not applied at signal reconstruction. If a low-pass filter of 20 kHz is not used then when you sample at 40 kHz (or 44.1 kHz) then you will indeed get phase effects, especially with something that has a ton of higher order harmonics like a symbol.
In your example that I quoted what you didn't do is apply the interpolation formula. If you are looking at the raw samples then it will indeed look anti-aliased. The interpolation formula takes that anti-aliased sample and reconstructs the original waveform faithfully if you have followed all the steps of the Nyquist-Shannon Sampling Theorem.
(By the way, I'm an instrumental chemist and this is a very serious subject for instrument design. When you are running instrumentation to sample spectra you need to be extremely aware of your sampling methodology to avoid introducing artifacts into your data.)
Ahh yeah, it's been a while since I've encountered this problem and I was remembering it incorrectly. Once I ran through the calculations again I see what you are getting at. The sum of the force vectors always cancel each other out no matter where you are in a hollow object so there is no attraction to the shell once you are inside of it.
That center-of-mass assumption (point-source of force simplification) you are using doesnt work from inside the hollow sphere.
I wasn't thinking of the point-source simplification, I was thinking of the inverse square law. I was assuming that the closest spot would have a slightly greater attraction but I wasn't taking into account the fact that more of the force vectors would be opposing each other on that side than on the other, counterbalancing the inverse square law. The neat thing is that the two effects do exactly balance each other out, a fact I just didn't remember from when I was a physics major years ago.
You would be completely weightless inside a hollow earth.
Only if you were at the exact center of mass. If you were a bit outside that then you would be attracted to the nearest concentration of matter. The center of mass of a hollow object is akin to being a ball at the top of a hill, if you are a little off to one side you will roll down it. It's not a stable point at all.
Now, until you actually hit something, you will experience weightlessness. Once you come to rest you will have weight (and it may be spread all over the place if you had enough velocity).
Years and years of wondering why we've got 16, 32, 48 and crazily 44.1kHz, solved in a Slashdot post.
Yeah there's a lot of "black magic" involved in signal theory that doesn't make sense on the face of it but once you dig deeper you develop a great respect for the engineers who have developed these solutions. I'm constantly amazed at the innovation and clever tricks that have been developed over the years.
The old graphics cards that did less than 8 bits per color channel would use more bits for green and the fewest for blue - which is because the eye is least sensitive to blue. Most sensitive to green so it needed more bits.
Which is exactly why they use double the green pixels. Now instead of one element out of every three pixels it's now one out of every two.
This means that the green pixels are not only more frequent in the pixel array, they also can show more levels of green in a single group. Both of these factors work with the eye's increased sensitivity to green to produce better images.