The Concorde was an engineering marvel, but it was more than just increasingly cheap transatlantic fares that did it in. Noise regulations prevented it from flying over the Continental US. Maintenance became increasingly expensive as the fleet aged. (The technical problems with its air intakes and tires caused safety issues, too.)
It's easy to say it's an entirely economic issue, but it isn't. The 2000 crash of Air France Flight 4590 shattered passenger confidence, the post-bubble recession meant fewer people had the disposable income to buy tickets, and the post-9/11 slump in air travel further reduced ticket sales.
The article really only convincingly explains why we don't have a replacement Concorde, not why the Concorde went out of service. Jet fuel is expensive. Today, airlines and aircraft manufacturers spend trillions of dollars to improve fuel efficiency to keep up with rising fuel prices.
It's not that we're too cheap, it's that the the industry was more interested in advances in conventional jet efficiency so that airlines could reap the benefit across a much, much larger fleet.
There's always a desire to wrap up complex and multifaceted decisions in a neat little package. I don't think it's possible to point to a single issue (economic or otherwise) that made supersonic transport unviable.
By my understanding, yes and yes. The third-party service caches the public key (with timestamp) and the browser caches the signed certificate (with timestamp). The timestamp gives the credentials a relatively short TTL to prevent a stolen cert from being used indefinitely.
A friend of the author of QLB here, and I brought up the idea of a visual interpreter to parse the square kufic calligraphy. My understanding (limited as it is by my almost complete ignorance of Arabic) is that certain stackings of adjacent words would be ambiguous to the parser.
That's exactly what's happening in some places in Vermont. (I know, not the first place you think of when you hear 'solar.') People can buy shares of a solar co-op and get credited on their power bill for their portion of any electricity generated. It will be interesting to see how that model works in the long run.
Turing should be pardoned as a human victim of an unjust law, and his genius should have nothing to do with it. That said, there are more important fights for equality that affect living people right now than whether the British government officially pardons a dead man.
I would love to see a LUA scripting framework built into this. I built an iOS app with an embedded web server, and dealing with dynamic text generation in Objective-C is a pain.
ConEd shut of power to the Financial District at approximately 7PM, but there were a number of explosions at substations including the one at 14th Street. There are over 1 million New Yorkers without power; ConEd reports most places below Midtown are dark.
They evacuated NYU Langone Hospital when its backup generator failed, so yes, consider yourself very lucky.
Most of Manhattan is without power. While some people may think it's badass to hack through the storm oblivious, the situation out here is pretty intense. I would encourage some leniency with the deadline, especially since as far as I know for NYC, things won't be back to normal for quite a few days.
I've heard (but can't find a link ATM) that it's not uncommon for people in developing countries have multiple phones or multiple SIM cards and will call on one or the other depending on that provider's current rates.
I'd like to second this sentiment. Instead of tearing down someone's significant effort to build something cool, the community should constructively communicate their issues with the project and offer suggestions for improvement.
I was personally impressed that drag actions were supported, because that's a frequently overlooked aspect when people roll their own slider toggles. Without looking at the source, I would guess that implementing mobile touch events would go a long way towards making this library cross-browser.
Could you enlighten us? I've read about fiber optic gyros, but I assume they haven't gotten small enough to fit in a mobile device. (Since they require kilometers of fiber.) I really don't know enough about how the solid state (?) gyros work.
Yeah, I kind of glossed over the vacuum aspect of the attitude indicator because I don't understand all its intricacies. The video pretty much confirms my understanding of how the gyro is kept spinning. The original author's description of air puffs sounds a lot like how the filtered air is ducted in to the housing and vented off in quadrants. I suspect that has more to do with maintaining the gyroscopes precession (http://en.wikipedia.org/wiki/Precession) than leveling the gyro in mid-flight.
I've heard that during prolonged banks or pitches, the AI can eventually find a different "level" than the true horizon. I'm trying to find more info into that phenomenon though.
In the mean time, I've found this article that seems to be talking about the same accuracy and drift issues as the original post, but explains the issues with more clarity and also includes sensor graphs and code samples: http://myahrs.wordpress.com/2012/04/24/turning-errors-contin...
OK. I'm no expert on this myself, but for someone who claims to have just figured out how an attitude indicator works, the author certainly doesn't explain it very well. I was left with the impression that the author is uncertain of the distinction between an accelerometer and a gyroscope. An accelerometer, like he says, can be likened to a hanging weight or pendulum. Accelerometers can measure the direction of gravity of a stationary object because the only force acting on the pendulum is acceleration due to gravity. However, as soon as the object is moved, other acceleration vectors are added to the already-present gravity vector.
(Imagine an accelerometer hanging from a rope. If you swing that rope in a circle around your head, the accelerometer will report that the force vector points to its bottom, away from your head, and not down to your feet as gravity alone would indicate.)
Which gets me to the OP. Because the article does not make a single mention of angular momentum (among other reasons), I would guess that the author doesn't understand how gyroscopes work. A gyroscope is essentially a spinning disc-shaped mass that resists change to its axis of rotation. If you built a housing that allowed it freedom of motion in three dimensions (called a gimbal (http://en.wikipedia.org/wiki/Gimbal)), it would remain on its original axis no matter how you tilted its enclosure (barring the inevitable energy loss due to friction, etc.)
So, in the case of an airplane, you would set the disc spinning on level ground. Then, while you're flying, any changes to your pitch or roll would be around the gyroscope (which, remember, is allowed to move freely relative to the cabin). The gyroscope wants to preserve its angular momentum, so it will still be spinning on the same axis relative to level ground. Any difference between the gyro and the cabin therefore indicates the orientation of the plane relative to the ground.
It was totally a lobbying effort to get the legislation passed. First by the tobacco industry because of fires started by smokers falling asleep with lit cigarettes, then by the chemical industry (by courting state fire marshals) to boost sales of their flame retardants. The Chicago Tribune has a multi-part series on it here: http://media.apps.chicagotribune.com/flames/index.html
No, both authentication factors are required, so either losing your phone or forgetting your password would be sufficient to lock you out. However, the Google authenticator PAM plugin provides emergency access codes to use in the case that the one-time password generator is not available.
It's easy to say it's an entirely economic issue, but it isn't. The 2000 crash of Air France Flight 4590 shattered passenger confidence, the post-bubble recession meant fewer people had the disposable income to buy tickets, and the post-9/11 slump in air travel further reduced ticket sales.
The article really only convincingly explains why we don't have a replacement Concorde, not why the Concorde went out of service. Jet fuel is expensive. Today, airlines and aircraft manufacturers spend trillions of dollars to improve fuel efficiency to keep up with rising fuel prices.
It's not that we're too cheap, it's that the the industry was more interested in advances in conventional jet efficiency so that airlines could reap the benefit across a much, much larger fleet.
There's always a desire to wrap up complex and multifaceted decisions in a neat little package. I don't think it's possible to point to a single issue (economic or otherwise) that made supersonic transport unviable.