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Comment Halting Problem (Score 1) 51

Is the smart thermostat we see today the same one that was there yesterday?

I bet this can be demonstrated to be equivalent to the halting problem. The question should be really: here are the spcifications of a certain device (whether dictated by the manufacturer, or determined empirically): does the present device match them? With every query from here to eternity? Under all circumstances? That smells like the halting problem.

So, in other words, you can never be completely certain of the answer, only confident up to specific bounds. Maybe that's good enough, but $50K for that kind of work is not, and the amount of effort involved for the general case, is not. A good solution for the problem is going to be the sort of thing that would take a startup into a medium-to-large corporation.

But there are really much better ways to avoid the problem in the first place. I mean, to paraphrase a processor of mine, we don't need a microprocessor in every doorknob. Just don't use the damned things. Your fridge does not need to be on the net. Nor do your chairs. Nor each door in your house. Your washing machine works perfectly well without being on the net. So does your garage door. The risks of putting highly insecure interfaces on such items just does not justify the potential benefit.

Comment Re: Only makes sense for niches (Score 1) 104

it takes less time for an equivalent C program to compile and run

No kidding. I have a pretty sophisticated self-specializing application that we rely on in my lab. It occasionally needs to create a semi-custom C program to run a particular computation with new parameter settings. It's so fast to generate the few thousand lines of C code and compile them that you barely notice the times when it needs to spin a new specialization of the code versus running an already-compiled version.

Comment Re:Already happing in NYC (Score 1) 239

All over the place, actually. This isn't really news as Amazon has planes and lots of trucks. They split from an exclusive deal with UPS nearly a year ago. It makes sense: they are as good at efficient operations management as any of the big players, and don't need to pay the profit to someone else when they can keep it in-house.

Comment Re:So how is it supposed to communicate? (Score 1) 96

The key is that it means a recent connection between the depths and the surface, and that would be huge for simplifying exploration.

I know what I'm about to write is armchair science, and I do look forward to reading the full peer-reviewed article, but it's a pretty tall assumption that the plumes have the same composition as the subsurface ocean. We have now seen plumes all over the place, even from the surface of comets. It seems a little too much like assuming what we want to hear is true to state that the plumes are coming directly from the oceans. Furthermore, even if they are, whatever process creates the plumes is unlikely to maintain the chemical composition in unaltered form. While it will certainly be important to study the plumes for their own sake, without evidence of the mechanism driving them, it's going to be a hard sell to say that such study would allow us to examine the subsurface oceans in anything but an indirect way.

Comment Re:More silent? (Score 1) 135

Why do you think they won't be as loud as a helicopter? Fewer smaller rotors are louder than a single larger rotor pushing the same amount of air. The amount of weight is going to be approximately the same (or are these air taxis relying on a technological breakthrough that the helicopter industry hasn't yet found?), so the amount of lift required is going to be the same, thus the amount of displaced air per unit time will be the same. Many smaller rotors will need to spin faster and be louder than a single rotor that provides the same thrust.

Think 80 mm PC fans versus 120 mm fans.

Comment Re:Not, "Can this work?" It's, "WHERE can this wor (Score 2) 135

Through a number of phases of the modern age, different airlines have attempted to offer air-taxi services from the three main airports around NYC to Manhattan. The economics would seem to make sense at first blush. The relative distances, potential market demand and locations make sense. And, yet none of the big airlines still offer these ad-ons to their mainline service, while, at the same time, they have offered significant incentives to attract big-money customers. The natural conclusion is that the devil is in the details and there must not be sufficient demand or market support for the routes to make financial sense. Not the least of which is that the fraction of the population who feels comfortable riding in a helicopter is small (consider how many people intensely dislike propeller planes, and then understand that helicopters are worse in nearly every way for ride experience when compared to jet flight).

Comment More silent? (Score 2) 135

More silent? How can they be more silent? Silent means they make no noise.

That said, VTOL aircraft are far, far from quiet. Even if you made them battery powered (good luck with that, as the power densities required are really pretty serious) to eliminate most of the power plant noise, they would still be damned loud due to the massive amount of air that needs to be thrust downward in order to move the craft upward. How much air? Equivalent to the weight of the craft. All the time. More, if you want to move up. Given that air is substantially less dense that most flying crafts, this means heaploads of noise. No matter how you cut it, aircraft are loud, close up, as long as you are depending on displacing air to provide thrust.

Comment Re:Better be careful, people (Score 4, Informative) 327

A few small air bubbles, while not ideal, are not as bad as you might think. An important reason that you use the Hollywood-style flick-flick-flick to get air bubbles to the top of a syringe and then press them out is to make sure that you've filled the syringe with the appropriate amount of drug. Whereas 0.2 cc of air probably won't do much to you if injected (and that's a pretty big bubble in a syringe), if you're injecting 1 cc of drug, that 20% difference with versus without bubble can make a big difference in the mount of drug that actually gets delivered.

Comment Re:HP Printer Issues (Score 1) 387

We are beginning to think HP is having some major issues with their company.

I believe the issues you are finding would stem from Carly Fiorina. She did a world of bad for HP, a once great company. I used HP equipment starting many decades ago. It used to be that when you bought an HP instrument, it was indestructible. I quipped to a fellow student of mine when in graduate school that if the high-powered HP power supply we had just bought on the used market worked, it would work for ever. And, I was right.

For equipment from a specific era, it's hard to beat HP.

But, regrettably, that era has passed, and Carly Fiorina put the last dozen nails in the coffin.

Comment Re:Cause (Score 4, Interesting) 266

If you look at the published video on YouTube of the explosion and go frame by frame, there are two events. The first is a bright flash that lasts a few frames and appears much larger than it actually is because it is both saturating the camera and illuminating the condensation clouds. You can see the illumination effect clearly in the first frame the flash appears as there are distinct shadows in the clouds. It's unclear to me whether this triggering event is electrical or chemical in nature, but I'm not an expert. Three observations can be made, however: (1) it is bright enough to cause lens flare in the camera which allows pinpointing its source despite the saturation (look for the X, carefully find its center -- you can do that very accurately -- and then back up a handful of frames; see that triangle thingy with a thin tail? That's what failed.) Then, (2) the initial flash is small and is followed almost immediately by a medium sized flash, and in turn that releases the fireball. Then, (3) the condensation clouds aren't moved by the explosion for about 12 frames until the fireball really starts to form, suggesting that the earlier flashes marked the release of lots of energy that may have been primarily radiation (light) rather than heat because they didn't expand the air enough for me to think of them as explosions. The video is 60 FPS, and the initial flash forms within one frame, so that's only 17 ms. The consdensation clouds don't start moving for 200 ms from the main explosion.

So we have one event that's exceedingly hot that triggers a second that's also exceedingly hot, that releases enough LOX to start the fireball. I'm thinking static discharge from the LOX filling.

One thing I don't understand, though, is that if you watch the fireball in slow motion, as the lower front heads toward the ground, there are seemingly waves passing through it. What are those? Additional shock fronts from tertiary explosions?

Comment Re:TVS Diode. (Score 1) 308

Except that a rock would be a lot more obvious, and if you wanted to socially engineer a company into self-destruction of property, just leave one of these USB-killer things disguised as a normal flash drive in the parking lot.

Now why you would want to destroy the USB port and possibly the computer it is part of rather than deliver malware if you have nefarious intent, well, that beats me. Destroying the computer causes limited damage. Malware, in contrast, can propagate.

Nevertheless, if vandalism is the goal, rocks will do, but gum, half-chewed soft candy, or a squirt of glue will still disable the port and require a visit from a field tech. One might imagine that gum is a far more pervasive nuisance to public-facing USB ports than rocks.

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