it's entirely adequate for N antennas to synthesize N separate, simultaneous, coverage patterns
By "simultaneous", do you mean that, say, 10 antenna elements can be sending 10 different packets to 10 receivers at once, or do you just mean that no physical repositioning of the antenna elements are necessary to send 10 different packets one after the other? If it's the former, how does that work? If it's the latter, you don't need N antenna elements for N coverage patterns. You need 1.26^[desired gain in dB]=N antenna elements. Just three elements can weakly focus a signal at any angle on a plane if they are organized triangularly. Just two antennas can focus to two points on the plane (similar to how your ears can't tell you whether a sound came from your 2 o'clock vs. your 4 o'clock.)
At UHF and microwave frequencies the beams are about as directional as a telephoto lens when the component antennas at the cell site are separated by several feet.
Specifically, elements a few wavelengths apart are as directional as a telephoto lens which is one or two micrometers across (a few wavelengths of visible light). In any case, no matter how many antenna elements you put in phase to shine your signal only where you want (and whether you do it via smart antennas or an old skool yagi or dish does not matter), you will still have to kowtow to the FCC's EIRP limits.
The comet is only the second repeating, or periodic, comet ever identified
If not wrong, then this is certainly misleading. Encke's Comet was the second periodic comet identified, but sheesh - would you say "Sputnik 2 was only the second satellite ever launched"? There are hundreds of known periodic comets.
Hence, it is a metric only of direct importance to people estimating failure rates for RAID arrays and the like.
Exactly. Which is why any MTBF statistic that is unaccompanied by a service life statistic should be dismissed as handwaving. People don't really believe that the coolant containment on an ESBWR nuke plant (expected to see 3*10^-8 common mode accidents per year) is going to last 33 million years, do they?
why don't the member nations just act and cut out the UN "middleman"? This is, after all, historically the way international action has been carried out. European governments trying to cope with Napoleon, the Kaiser, Hitler or (going further back) the Mongol or Ottoman invaders didn't feel a need to create a standing bureaucracy to validate by inscribing (in five official languages) on parchment what they'd already collectively decided to do. They just acted, forming governing councils and agreements as and where they were needed -- and not otherwise.
The rationale goes back to preventing another World War I. At the turn of the century, most nations in Europe made alliances with each other that if one of them were attacked, their ally would step in to defend them. They grouped themselves into the Entente Powers and the Central Powers. Now, if governments were the only actors, and if these alliances were public knowledge, this might have resulted in a tense, but stable environment. What actually happened was a terrorist group from Serbia (the Black Hand Society) assassinated the heir to the throne of Austria-Hungary. Both sides reacted disproportionately, Austria-Hungary declared war, most of Europe honored their treaty obligations, and millions died.
The League of Nations, the predecessor to the UN (and ineffective even in comparison to the UN) was the response to the perceived causes of World War I.
The article doesn't mention how many watts per square meter this panel will produce.
It did mention efficiency, so you can calculate it. Find an insolation map, find your location on it, find the average kWh/day you get, and multiply by the 11-13% figure mentioned in the article.
Going up a fourth 12 times brings us back to the same note (5 octaves higher) but:
going up 12 fourths (4/3)^12 = 31.56929 while going up 5 octaves:
2^5=32.
So these are the same note arrived at via two different routes and going up in fourths the singer arrives back at the tonic about a quarter semitone flat as compared to the piano.
I've always wondered what people with perfect pitch do in this circumstance.
You sound knowledgeable enough that you might have already considered everything I'm about to say, but here goes anyway:
If the singer with perfect pitch is attuned to the even-tempered chromatic scale, then they will not end up a quarter semitone flat. If they are attuned to a meantone temperament, then one of the fourths will sound really bad.
You seem quite aware that with even temperament, a fourth is not a perfect fourth. It is not a ratio of 1.333333, it is a ratio of 2^(5/12), or 1.334839. Likewise, a fifth is not a ratio of 1.5, it is a ratio of 2^(7/12), or 1.498307. 1.334839^12=31.999754 (32, if it wasn't for cumulative rounding errors.)
I suspect that most (perhaps not all) people with perfect pitch have a better sense of whether the note they are currently singing matches with the pitch they know that note should be than a sense of whether the interval they just sung is 0.15% off.
Other pitches are determined using a certain formula, sort of like centrigrate to farenheite formula, just because one goes up the other doesn't go up by the same amount.
Logarithmically, yes, they do go up and down by the same amount. Each octave is double the frequency of the last. Since there are twelve notes in the chromatic scale, each note is a frequency 2^(1/12) (or 1.05946309436) higher than the last. If A4 is 440Hz, then A# is 466.16Hz, B is 493.88Hz, C is 523.25Hz. If A4 is 435Hz, A#, B, and C are 460.87Hz, 488.27Hz, and 517.31Hz. In the chromatic scale, the frequency ratios between notes are always the same.
This is why we have things like database clusters and distributed queries. Sometimes scaling horizontally makes more sense and is cheaper than trying to scale vertically. Which probably explains why it is so popular.;)
Agreed. But if the app was never created with that in mind, it's rarely an option, and, if poorly/naively implemented, it can cause problems much worse than performance.
I think the only two multi-master database implementations I've seen so far that have been done right are Usenet and Active Directory. Everything else I've had experience with, from PDA syncing software to disaster recovery server software, has been a hackjob.
Unlike copyright the patent concept is easy to defend. The benefit for progress of engineering and technological culture can be logically demonstrated
The patent system was originally an alternative to the guilds, who would keep the important knowledge of their trade a secret from those who wished to compete. Not only was the knowledge at risk of being lost over time, but the guilds actively worked to prevent non-guild members from competing in their trade. So now, we have government-granted temporary monopolies as an incentive to share these secrets.
The problem is, the "secrets" going into the patent system these days are about as useful to someone skilled in the art as a list of ingredients on a box of food is to a chef. They are purposefully written in an obfuscated manner. One never hears of someone poring over prior patents for enlightenment - in fact, company lawyers often recommend to their employees never to research patents because then they would be knowingly infringing on anything they stumbled upon.
I believe there are more powerful mechanisms at work that would prevent the reformation of a guild system today if the patent system disappeared. For starters, employees switch jobs much more regularly. Legal limits to non-compete contracts would be effective in keeping this mechanism in place. The Internet has promoted a worldwide culture of knowledge-sharing. Corporate secrets are regularly and anonymously leaked to the public.
So in my mind the question is not whether patents are necessary to protect knowledge sharing. The question is whether the incentive to innovate would remain, and whether that incentive is truly tied to money. I am increasingly dubious.
I evaluated Arcserve about a year and a half ago, using a leftover tape drive. I started a backup on it and then left for the night. When I got around to checking it a couple days later, the system was extremely unresponsive. "My Computer" would take minutes to open and you just couldn't open C: through Explorer no matter how patient you were.
After letting "dir" run over the weekend, my suspicions were confirmed. Arcserve had created 700,000 temp files in the root of C:. Each one was a small text file asking the operator to insert another tape.
To CA's credit, they did have a patch for that when I called in. But sheesh - if software is creating temp files in the root of C:, what the hell else is broken by design?
We ended up going with Netbackup, which was outrageously expensive and didn't quite work like we wanted it to (why do my weekly tapes have all of the daily incremental backups on top of the weekly full ones?) - but writing a perl script to call bpduplicate fixed that, and we ended up with a pretty hands-off system.
If my hypothesis is that the next time I close my eyes I'll smell tulips, there's no math involved in evaluating this.
"When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind: it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science."
--Lord Kelvin
The guy that funded the prize, had also given money to the company that won (before they won -- meaning for R&D). That's not a real contest. That's a tax write off.
I'd suggest taking a closer look at the guy that funded the prize.
what if it's 2 o'clock in the morning... If I roll right through that light, I might save myself a minute or two.
Those traffic lights should be upgraded so they can be placed on a different cycle at different times of day. At 2 am, a 10-second cycle makes more sense than a 1-minute one.
Efficiency on the A/C units is usually around 2:1 and sometimes approaches 3:1
A/C unit efficiency is expressed as Coefficient of Performance (or COP), or if you feel like converting BTUs to KWh, SEER. The minimum standard in the US for new A/C units is a SEER of 12 - a COP of 3.5:1 - and they wanted to make it 13 (or 3.8:1). That's the legal minimum - not the state of the art.
Now add inefficiencies in the cooling architecture, power for fans in the servers, inefficiency of semiconductors when running hot, etc.
This adds another few percent - certainly not 25%.
You see, the problem is that no VoIP provider gives you five nines availability SLA, but I think this is what government requires from land line phone providers.
No. The five nines thing comes from land line phone providers' demands for the equipment they purchase and use. Since your phone service usually depends on many pieces of equipment working simultaneously (and many wires remaining intact simultaneously), the actual reliability of your land line is much lower. For example, Verizon advertises three nines.
Does anyone happen to know what the pressure would be like on the low pressure side of a good airfoil?:)
A Boeing 777-300 has a maximum takeoff weight of 300000kg and a wing area of 428m^2, giving a wing loading of 700kgf/m^2 (at 1g - the wing must be moving at or faster than stall speed to support this load). Units says "1 atmosphere" = "10332 kgf/m^2". 10332-700=9632. 9632/10332=.932..932*15psi = 13.9psi.
Note that a 777-300 wing is still VERY BIG and even at stall speed is moving VERY FAST. For most general aviation aircraft you can use a figure like 100kgf/m^2, which gives you more like a 0.15 psi pressure drop.
Now, to figure how much wind energy it'll take to create that kind of pressure drop over that much air, look up the fuel consumption of a 777-300.:)
You the business are not in the business of making potential hires excited; your job is to make the best company you can, the best products, the happiest employees, the most loyal customers, etc.
"If you want to build a ship, don't drum up the men to gather wood, divide the work and give orders. Instead, teach them to yearn for the vast and endless sea." -- Antoine de Saint-Exupéry
I know that using gas heat is more efficient than electric heat, but by having incandescent bulbs burning and generating heat, my furnace now has to work just a little less hard, somewhat offsetting the extra electricity usage.
1. Get your gas and electric bills.
2. Take your marginal cost of gas per therm (i.e. if there are multiple rates for multiple tiers of usage, take the rate that you'd pay or save if you use a little bit more or less, which is usually the higher rate). Divide this by 105.4804 to get cost per megajoule.
3. Take your marginal cost of electricity per kWh. Divide this by 3.6 to get cost per megajoule.
4. Compare apples to apples. Maybe add a fudge factor if you know that a fraction of your bulb's heat is going into the attic instead of your living room.
I know you're joking, but if you look at the cross-section in the article, you'll see that they wisely passed over the hemispherical head for a pent-roof head. They also made the engine incredibly undersquare - it has a 0.38 bore-to-stroke ratio. Diesels require very high compression ratios, and it's worth compromising a redneck's sense of aesthetics to get it.
Slashdot Mirror
By "simultaneous", do you mean that, say, 10 antenna elements can be sending 10 different packets to 10 receivers at once, or do you just mean that no physical repositioning of the antenna elements are necessary to send 10 different packets one after the other? If it's the former, how does that work? If it's the latter, you don't need N antenna elements for N coverage patterns. You need 1.26^[desired gain in dB]=N antenna elements. Just three elements can weakly focus a signal at any angle on a plane if they are organized triangularly. Just two antennas can focus to two points on the plane (similar to how your ears can't tell you whether a sound came from your 2 o'clock vs. your 4 o'clock.)
Specifically, elements a few wavelengths apart are as directional as a telephoto lens which is one or two micrometers across (a few wavelengths of visible light). In any case, no matter how many antenna elements you put in phase to shine your signal only where you want (and whether you do it via smart antennas or an old skool yagi or dish does not matter), you will still have to kowtow to the FCC's EIRP limits.
From the article:
If not wrong, then this is certainly misleading. Encke's Comet was the second periodic comet identified, but sheesh - would you say "Sputnik 2 was only the second satellite ever launched"? There are hundreds of known periodic comets.Exactly. Which is why any MTBF statistic that is unaccompanied by a service life statistic should be dismissed as handwaving. People don't really believe that the coolant containment on an ESBWR nuke plant (expected to see 3*10^-8 common mode accidents per year) is going to last 33 million years, do they?
The rationale goes back to preventing another World War I. At the turn of the century, most nations in Europe made alliances with each other that if one of them were attacked, their ally would step in to defend them. They grouped themselves into the Entente Powers and the Central Powers. Now, if governments were the only actors, and if these alliances were public knowledge, this might have resulted in a tense, but stable environment. What actually happened was a terrorist group from Serbia (the Black Hand Society) assassinated the heir to the throne of Austria-Hungary. Both sides reacted disproportionately, Austria-Hungary declared war, most of Europe honored their treaty obligations, and millions died.
The League of Nations, the predecessor to the UN (and ineffective even in comparison to the UN) was the response to the perceived causes of World War I.
It did mention efficiency, so you can calculate it. Find an insolation map, find your location on it, find the average kWh/day you get, and multiply by the 11-13% figure mentioned in the article.
You sound knowledgeable enough that you might have already considered everything I'm about to say, but here goes anyway:
If the singer with perfect pitch is attuned to the even-tempered chromatic scale, then they will not end up a quarter semitone flat. If they are attuned to a meantone temperament, then one of the fourths will sound really bad.
You seem quite aware that with even temperament, a fourth is not a perfect fourth. It is not a ratio of 1.333333, it is a ratio of 2^(5/12), or 1.334839. Likewise, a fifth is not a ratio of 1.5, it is a ratio of 2^(7/12), or 1.498307. 1.334839^12=31.999754 (32, if it wasn't for cumulative rounding errors.)
I suspect that most (perhaps not all) people with perfect pitch have a better sense of whether the note they are currently singing matches with the pitch they know that note should be than a sense of whether the interval they just sung is 0.15% off.
Logarithmically, yes, they do go up and down by the same amount. Each octave is double the frequency of the last. Since there are twelve notes in the chromatic scale, each note is a frequency 2^(1/12) (or 1.05946309436) higher than the last. If A4 is 440Hz, then A# is 466.16Hz, B is 493.88Hz, C is 523.25Hz. If A4 is 435Hz, A#, B, and C are 460.87Hz, 488.27Hz, and 517.31Hz. In the chromatic scale, the frequency ratios between notes are always the same.
I'd imagine C was picked arbitrarily.
Check out the circle of fifths.
Agreed. But if the app was never created with that in mind, it's rarely an option, and, if poorly/naively implemented, it can cause problems much worse than performance.
I think the only two multi-master database implementations I've seen so far that have been done right are Usenet and Active Directory. Everything else I've had experience with, from PDA syncing software to disaster recovery server software, has been a hackjob.
The patent system was originally an alternative to the guilds, who would keep the important knowledge of their trade a secret from those who wished to compete. Not only was the knowledge at risk of being lost over time, but the guilds actively worked to prevent non-guild members from competing in their trade. So now, we have government-granted temporary monopolies as an incentive to share these secrets.
The problem is, the "secrets" going into the patent system these days are about as useful to someone skilled in the art as a list of ingredients on a box of food is to a chef. They are purposefully written in an obfuscated manner. One never hears of someone poring over prior patents for enlightenment - in fact, company lawyers often recommend to their employees never to research patents because then they would be knowingly infringing on anything they stumbled upon.
I believe there are more powerful mechanisms at work that would prevent the reformation of a guild system today if the patent system disappeared. For starters, employees switch jobs much more regularly. Legal limits to non-compete contracts would be effective in keeping this mechanism in place. The Internet has promoted a worldwide culture of knowledge-sharing. Corporate secrets are regularly and anonymously leaked to the public.
So in my mind the question is not whether patents are necessary to protect knowledge sharing. The question is whether the incentive to innovate would remain, and whether that incentive is truly tied to money. I am increasingly dubious.
It's also worth noting that the P-51 Mustang's radiator was so cleanly designed that it actually contributed to the thrust of the airplane.
I evaluated Arcserve about a year and a half ago, using a leftover tape drive. I started a backup on it and then left for the night. When I got around to checking it a couple days later, the system was extremely unresponsive. "My Computer" would take minutes to open and you just couldn't open C: through Explorer no matter how patient you were.
After letting "dir" run over the weekend, my suspicions were confirmed. Arcserve had created 700,000 temp files in the root of C:. Each one was a small text file asking the operator to insert another tape.
To CA's credit, they did have a patch for that when I called in. But sheesh - if software is creating temp files in the root of C:, what the hell else is broken by design?
We ended up going with Netbackup, which was outrageously expensive and didn't quite work like we wanted it to (why do my weekly tapes have all of the daily incremental backups on top of the weekly full ones?) - but writing a perl script to call bpduplicate fixed that, and we ended up with a pretty hands-off system.
Just be glad their hold music isn't this.
http://www.google.com/trends?q=error
http://www.google.com/trends?q=police+state
http://www.google.com/trends?q=nuts
"When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind: it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science."
--Lord Kelvin
I'd suggest taking a closer look at the guy that funded the prize.
"facts bein' stubborn and not easy drove!" -- Mrs Gamp
Those traffic lights should be upgraded so they can be placed on a different cycle at different times of day. At 2 am, a 10-second cycle makes more sense than a 1-minute one.
A/C unit efficiency is expressed as Coefficient of Performance (or COP), or if you feel like converting BTUs to KWh, SEER. The minimum standard in the US for new A/C units is a SEER of 12 - a COP of 3.5:1 - and they wanted to make it 13 (or 3.8:1). That's the legal minimum - not the state of the art.
This adds another few percent - certainly not 25%.
As a kid I started to notice that the big fight at the end was always exactly 52 minutes after the hour.
No. The five nines thing comes from land line phone providers' demands for the equipment they purchase and use. Since your phone service usually depends on many pieces of equipment working simultaneously (and many wires remaining intact simultaneously), the actual reliability of your land line is much lower. For example, Verizon advertises three nines.
A Boeing 777-300 has a maximum takeoff weight of 300000kg and a wing area of 428m^2, giving a wing loading of 700kgf/m^2 (at 1g - the wing must be moving at or faster than stall speed to support this load). Units says "1 atmosphere" = "10332 kgf/m^2". 10332-700=9632. 9632/10332=.932. .932*15psi = 13.9psi.
Note that a 777-300 wing is still VERY BIG and even at stall speed is moving VERY FAST. For most general aviation aircraft you can use a figure like 100kgf/m^2, which gives you more like a 0.15 psi pressure drop.
Now, to figure how much wind energy it'll take to create that kind of pressure drop over that much air, look up the fuel consumption of a 777-300. :)
"If you want to build a ship, don't drum up the men to gather wood, divide the work and give orders. Instead, teach them to yearn for the vast and endless sea." -- Antoine de Saint-Exupéry
1. Get your gas and electric bills.
2. Take your marginal cost of gas per therm (i.e. if there are multiple rates for multiple tiers of usage, take the rate that you'd pay or save if you use a little bit more or less, which is usually the higher rate). Divide this by 105.4804 to get cost per megajoule.
3. Take your marginal cost of electricity per kWh. Divide this by 3.6 to get cost per megajoule.
4. Compare apples to apples. Maybe add a fudge factor if you know that a fraction of your bulb's heat is going into the attic instead of your living room.
I know you're joking, but if you look at the cross-section in the article, you'll see that they wisely passed over the hemispherical head for a pent-roof head. They also made the engine incredibly undersquare - it has a 0.38 bore-to-stroke ratio. Diesels require very high compression ratios, and it's worth compromising a redneck's sense of aesthetics to get it.