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Comment: Re:Preferable to Rarer, Larger Quakes (Score 4, Insightful) 65

by dtmos (#48348989) Attached to: Nevada Earthquake Swarm Increases Chance of Larger Quake

Having been in all three (well, I wasn't exactly inside the tornado, but it was much too close for comfort), I agree that the earthquake is the choice of the lot -- if one has to be in one of the three.

However, if the question is, "Which would you rather live in -- an earthquake-, tornado-, or hurricane-prone area?", my answer would be the hurricane-prone area, because these days they're by far the most predictable and, therefore, escapable. I'm comforted by the fact that should one appear, I will have enough warning to be elsewhere when it hits. It's a lot harder to say that about tornadoes and earthquakes.

Comment: Unlocked? (Score 1) 150

by dtmos (#48300611) Attached to: SpaceShipTwo's Rocket Engine Did Not Cause Fatal Crash

The part I don't get is why one would unlock the feathering system at the start of the burn, well before it is expected to be used -- something that the in-flight videos apparently show. I can see that keeping the feathering system locked would be a safe thing to do before the release, but was the feathering system designed to be used while SpaceShipTwo was in powered flight? I was under the impression that it was not, so it would seem prudent to keep it locked until the burn was complete. Am I missing something?

I confess that I am reminded of Evel Knievel's abortive jump of the Snake River in his Skycycle X-2, which failed when his recovery mechanism (in this case, a drogue parachute) deployed during the first few seconds of powered flight. The design of recovery systems is a difficult problem.

Comment: Re:Microwaves and 2.4 GHz (Score 1) 122

by dtmos (#47937203) Attached to: Scientists Twist Radio Beams To Send Data At 32 Gigabits Per Second

I think the special part is that 2.4 GHz is a convenient frequency where there is a balance between a larger amount of energy being absorbed by water and a smaller amount of energy being absorbed by glass and plastic.

No, 2.4 GHz was just one of seven convenient open frequency bands when, in 1947, the FCC assigned frequencies for the industrial heating, diathermy, and other RF sources that were causing interference on communication systems. These bands were scattered from 25 MHz to 20 GHz. See p. 8 and p. 50-51 of the Thirteenth Annual Report of the FCC, and the 1947 US Frequency Allocation Proposal to the Atlantic City International Radio Conference (see pdf page 464 of this pdf file). They were collectively called the "ISM bands", because the FCC aggregated Industrial heating, Scientific uses, and Medical heating (diathermy) equipment into bands that would minimize interference to communication systems. The microwave oven (called an "electronic cooker" in the FCC report) was so new that it was explicitly mentioned, and lumped in with other "industrial" heating systems.

Comment: Re:Spiral filter, and a Tardis (Score 1) 122

by dtmos (#47934759) Attached to: Scientists Twist Radio Beams To Send Data At 32 Gigabits Per Second

So let me ask: If the multiplexing is due to "the phase relationship between the oscillations of the field at different positions", may I assume that these systems would be very sensitive to multipath interference -- especially varying multipath interference, as in mobile devices? Is that why the only demonstrations I have seen involve point-to-point links in free space (where multipath would be minimized)?

Comment: Microwaves and 2.4 GHz (Score 4, Informative) 122

by dtmos (#47934723) Attached to: Scientists Twist Radio Beams To Send Data At 32 Gigabits Per Second

2.4GHz is perfect for heating anything with a high water content, like tissue. That's why microwave ovens use it.

This is a myth. There is nothing special about 2.4 GHz as far as water is concerned. There is a mild absorption peak at 24 GHz, but nothing at 2.4.

Comment: Incredibly wise advice (Score 2, Insightful) 120

by dtmos (#47760277) Attached to: The Grumpy Programmer has Advice for Young Computer Workers (Video)

Robin Miller: But age discrimination in employment, have you encountered?

Bob Pendleton: Oh, absolutely. I got laid off on my 49th birthday and haven’t been able to find a full time job since.

One piece of advice I always give younger engineers and programmers is to be increasingly vigilant about your career as you age. In the last decade or so before retirement one is very vulnerable to layoffs, because one's salary is high and one's formal education was a long time ago.

Comment: Re:Spherical Torus (Score 4, Informative) 147

by dtmos (#47746961) Attached to: Princeton Nuclear Fusion Reactor Will Run Again

Spherical Torus?

I wondered the same thing. However, the National Spherical Torus Experiment web site has this explanation:

The magnetic field in NSTX forms a plasma that is a torus since there is a hole through the center, but where the outer boundary of the plasma is almost spherical in shape, hence the name “spherical torus” or “ST”.

There are also some links to more detailed descriptions.

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