Follow Slashdot stories on Twitter

 



Forgot your password?
typodupeerror

Comment: Apples Power Management is very good. (Score 1) 63

by Qbertino (#48686623) Attached to: My laptop lasts on battery for ...

Aside from building the hardware and the OS and making it fit, Apple also builds their own batteries, which, truth be told, are almost second to none. On top of that, Apple was first to dare build a non-replaceable battery into their MB Air. On top of that they put serious custom built power-management into their notebooks. I've got an MB Air myself and after 4 years of usage the battery life still is impressive. Note: I'm not an Apple fanboy either, although I do own the mbair and a 2007 Macmini.

Comment: Re:Developing Story (Score 1) 258

by jbwolfe (#48685631) Attached to: AirAsia Flight Goes Missing Between Indonesia and SIngapore
I stand corrected. Perhaps it would have been better to say almost no modern transport category aircraft come equipped to display AOA anymore. While this may be an option that Boeing have begun offering (that article I believe dates from 2012), I have never seen one in use. Do you work for a US certificated carrier- BizJet contract maybe? After looking through our flight manuals for the 787, I see that we do not have AOA display on that type. We are the only US part 121 carrier to operate 787s. I have flown 737,747,757,767,777 and A320 types, but none have AOA and I have not encountered them while jumpseating. I still find AOA irrelevant to modern cockpits- at least transport category cockpits. What's your opinion of AOA presented as part of PFD, useful or not? Target AOA might have some relevance but not when max L/D can be calculated and displayed on speed tape or FMC.

Comment: Re:Coffin Corner? (Score 2) 258

by jbwolfe (#48685481) Attached to: AirAsia Flight Goes Missing Between Indonesia and SIngapore

The moment you stall, you lose altitude, and you're no longer in the coffin corner.

The moment you stall, you are outside the flight envelope which includes that corner. You remain outside until you recover from stall. Losing altitude is not a stall recovery technique. Restoring laminar flow over the wing is. That may involve sacrificing altitude for airspeed, assuming you still have enough elevator authority to reduce AOA. Another method is to use excess thrust, assuming it is available at that altitude (the higher you are the, less available.)

A simple stall recovery, and you're back in normal flight.

Stall recovery in large swept-wing aircraft at cruise altitude is anything but simple. It requires a great deal of patience and energy management to avoid secondary stalls. Once recovered, you remain in alternate or direct law- no more normal law until on the ground and reset.

The A320 in particular is designed so the computer will automatically recover from stalls if the pilots simply release all controls.

Untrue. When you stall an A320, you revert to alternate law (hopefully with speed stability), as normal law will not let you stall. If you stalled, something went wrong. The flight control computers are saying essentially that "I cant fly the plane anymore- you the pilot must do it." It will not recover without pilot intervention.

...one of the pilots on AF447 kept directing the plane to pitch up without telling the other pilot what he was doing, as the other pilot was trying to pitch it down to recover from the stall

This did happen, and they were disoriented but not stupid, just poorly trained. The aircraft also gave them a "dual input" aural warning and averaged their inputs. The first sense to disappear when under stress is hearing. They were under stress and poor training in stall recovery left them unable to prevent secondary stalls. This was one of many other factors to this particular accident as well as all accidents in general.

Comment: Re:Developing Story (Score 1) 258

by jbwolfe (#48685161) Attached to: AirAsia Flight Goes Missing Between Indonesia and SIngapore

Because Airbus makes shitty Angle Of Attack probes

It was iced pitot tubes that caused problems for AF447. Thales was the manufacturer of the pitot tubes, not Airbus. No modern transport category aircraft come equipped to display AOA anymore. It is no longer relevant in digital flight displays as the quality of flight parameters and method of display is so much better for pilots. However, AOA is still measured and provided to flight control computers.

...controlled by a computer that can't be overridden when it suffers from bad data input.

Completely incrrect. When the computers suffer from lack of information or "bad data" they revert to a fail safe mode; alternate law first then direct law. Basically they get out of the way, not "can't be overridden".

Comment: Re:Don't take airplanes piloted by the Malays (Score 2, Informative) 258

by jbwolfe (#48684467) Attached to: AirAsia Flight Goes Missing Between Indonesia and SIngapore

The airline should have re-routed it, but that's not entirely the pilot's call.

The route and safety of flight are shared responsibilities between the dispatcher and pilot. The final authority rests with the Captain per regulation. Were the captain to feel deviation or complete re-route was necessary, he had full authority and responsibility to do so. Where ATC is not accommodating, he can exercise emergency authority to preserve safety of flight.

...it was the one the owners of the plane he was flying told him to take.

Point of information: The "owners" explicitly do not have that authority.

Comment: Re:this report is inconsistent (Score 1) 133

by radtea (#48682039) Attached to: New Paper Claims Neutrino Is Likely a Faster-Than-Light Particle

This is a scientific paper being written for the author's peers, none of whom would ever misinterpret it. I've seen this issue come up in a couple of places where laypeople are confused by the language of physics.

This is not a problem with the language of physics: it is a problem with laypeople.

I'm all for clear scientific communication, but at the end of the day, communication is hard and worrying about how some random person on the 'Net might misinterpret a term you use every day in your professional work is just not a good use of anyone's precious attention.

When I write poetry I do so in a pretty technical way. If people don't appreciate that, sucks to be them, because they are not my audience. I'm the same way in scientific communication: I write for my peers, and everyone else does the same. Let the popular science authors do the translation. They need the work.

Comment: Re:Difficult to reconcile with SN 1987A (Score 2) 133

by radtea (#48682025) Attached to: New Paper Claims Neutrino Is Likely a Faster-Than-Light Particle

The primary difficulty here is going to be the same data that was really tought to reconcile with in the OPERA experiment, namely the data from SN 1987A.

I had the same thought, but it turns out not to be the case. Given the model he's working with, the neutrinos will be as much above the speed of light as they would have been below it if they had the same real mass (0.3 eV or something like that.)

For ~10 MeV neutrinos this gives gamma absurdly close to unity, and it's as impossible to distinguish neutrinos traveling just over c from ones traveling at c from ones traveling just under c.

The paper actually mentions SN1987A and talks a bit about the time resolution required.

Comment: Re:Ooh, I Have An Idea! (Score 1) 192

by IamTheRealMike (#48679929) Attached to: MIT Unifies Web Development In Single, Speedy New Language

Speak for yourself. Hating on HTML and web tech because you're bad at it is the lamest of the lame excuses. My users much prefer our HTML GUI over our shitty old desktop apps

Sounds like you're hating on desktop apps because you're bad at them .... though certainly that's a common problem.

Comment: Re:LENR is not fusion (Score 1) 183

by radtea (#48677161) Attached to: Bill Gates Sponsoring Palladium-Based LENR Technology

the best theory so far is that of Widom-Larsen

Widom-Larsen requires an implausible mix of scales. The effective mass of heavy electrons in the solid state is a collective phenomenon happening over distances and time-scales that are large relative to the nucleus and nuclear time-scales and affect the dynamics of the electron's interaction with the lattice, on those scales. To impute to these large-scale effects efficacy at the nuclear scale is very unlikely to be correct.

Consider a car analogy: a car moving along a freeway in dense traffic interacts with all the cars around it. If the driver accelerates, they will pull up close to the care behind and that driver may speed up a bit too, sending a diminishing wave of acceleration through the traffic, so compared to the same car alone on the road the car in dense traffic appears to have a much higher effective mass. Alone, you hit the gas and speed up a lot. In traffic, you hit the gas and speed up a little bit. That's what the electron in the surface looks like: a car in traffic.

But on the scale of car-car interactions, the "bare" mass of the car is what matters. If two cars collide you get an energy of 0.5*m*v^2, not 0.5*Meff*v^2.

Yeah, there are multi-car pileups that muddy the analogy, but they add up to nothing like the effective mass of the whole traffic block, so there. And the difference in scales between "cars and traffic" is tiny compared to the difference in scales between "nuclei and the lattice", so the effect that analogy hopefully makes obvious will be that much larger in the latter case.

Comment: Re:didn't go didn't download, don't care (Score 4, Insightful) 147

by ScentCone (#48676319) Attached to: Crowds (and Pirates) Flock To 'The Interview'

Because not believing, with little evidence, NK is competent enough to pull this off makes you a B357 K0r34n 1337 h4xx0r.

What on earth makes you think that NK has to have the native talent? The didn't figure out how to make nukes on their own either. They didn't home-grow their substantial currency counterfeiting operation, either. They likewise don't design and build their own military equipment. But that doesn't stop them from having nukes, from doing big business in phony currency, and sinking other people's ships.

The first time, it's a KLUDGE! The second, a trick. Later, it's a well-established technique! -- Mike Broido, Intermetrics

Working...