Beta
×

Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!

Comments

top

San Onofre Nuclear Power Plant Dismantling Will Cost $4.4 Billion, Take 20 Years

calidoscope Not surprising (343 comments)

Decommissioning costs are still a lot less than it would cost to build the plant now. Letting the plant cool down for a few years makes the process simpler and safer, though the reactor vessel is going to be a challenge.

about a month ago
top

Perlan II Project Aims To Fly a Glider To the Edge of Space

calidoscope Re: 100km (44 comments)

Something on the order of 97% of the atmosphere's mass is below 90,000'. 100km is an arbitrary value for the start of space, as the air at 100km is too thick to orbit and too thin to fly in (except dynamic soaring?). In imperial units, 100,000' seems to be the upper limit for flying and 100 miles is about the lower limit for orbiting.

The Perlan II sounds like it will handle like an unpowered U2 - where the planes ceiling will be defined by the "coffin corner" were the low speed stall (classic stall) approaches the high speed stall (Mach tuck from transonic airflow). Perhaps they will be using a more refined airfoil than the U2 to increase the Mach number for high speed stall.

IIRC, the pre-Perlan I sailplane altitude record of approx 47,000 feet was set sometime in the 1960's, surprising it took that long for someone to break that.

about a month ago
top

The Truth About Solar Storms

calidoscope Re:The failure mode is transformer core saturation (91 comments)

I first heard about use of series capacitors in an electric power systems class, 1H 1975, so they have been around for quite a while. It would seem to me that the caps should be able to withstand the DC potential set up by a Carrington event.

about a month ago
top

The Truth About Solar Storms

calidoscope Re:The failure mode is transformer core saturation (91 comments)

Any component for a high voltage transmission line is going to be gigantic. Google term "power transmission line series capacitors" should get you started.

about a month ago
top

The Truth About Solar Storms

calidoscope Re:The failure mode is transformer core saturation (91 comments)

An alternative way of minimizing the effects of a severe solar storm on the grid would be placing series capacitors on the long AC transmission lines. This is done already to increase power transfer capacity of some lines.

Since the solar flare is visible many hours before CME hits, the utilities should have time to configure the grid for the storm. The oerative word here is "should".

about a month ago
top

One Trillion Bq Released By Nuclear Debris Removal At Fukushima So Far

calidoscope Re:Is that a lot? (190 comments)

Not that much. A typical Tc99m scan involves injection a bit over a billion (10E9) bq per person, albeit half life is only 6 hours. Reminds me of a "warning sticker" for a CB radio - "Danger 5,000 milliwatts".

about a month ago
top

Rocket Scientist Designs "Flare" Pot That Cooks Food 40% Faster

calidoscope Re:Wow. (204 comments)

I agree wholeheartedly that the pot is more similar to the Jetboil in principle than different. There is a difference in details in that the Jetboil is designed for lighter weight and better heat transfer efficiency than the pot at the expense of a more fragile design.

about a month and a half ago
top

Today In Year-based Computer Errors: Draft Notices Sent To Men Born In the 1800s

calidoscope Re:dmv (205 comments)

I don't there is anyone in the US who was born in 1897 or earlier.

about 2 months ago
top

New Chemical Process Could Make Ammonia a Practical Car Fuel

calidoscope Mid 1960's Army research (380 comments)

There was an article or two in the likes of Mechanix Illustrated or related magazine about the US Army experimenting with ammonia fueled engines. Reports indiacted that engines would function, but had not been developed to the point of practicality. Shudder to think what kind of NOx levels are present in the exhaust.

about 2 months ago
top

Scientists Measure Magnetic Interaction Between Two Bound Electrons

calidoscope Newton's ???? inverse cube law (26 comments)

I remember Newton's inverse square law, but magnetic dipoles were more than two centuries after his time.

about 2 months ago
top

Astronomers Solve Puzzle of Mysterious Streaks In Radio Images of the Sky

calidoscope Re:Cyclotron Radiation? (66 comments)

That sounds like a reasonable guess as to what is going on. The hot plasma is conductive and the Johnson noise may produce enough current to emit detectable radiation. My recollection was that the sky noise temp at 50 MHz was on the order of 3,000K, and the plasma from the meteor trail is likely to be considerably hotter than that.

about 3 months ago
top

The Major Theoretical Blunders That Held Back Progress In Modern Astronomy

calidoscope Error in first example (129 comments)

TFA had the 200 inch Hale telescope on a fictional geogrphical location, Mt. Palomar. The real name is Palomar Mountain. A minor detail, and very common error, but it is the same kind of error the author was complaining about.

about 3 months ago
top

New Semiconductor Could Improve Vehicle Fuel Economy By 10 Percent

calidoscope Re:Fuel economy? (119 comments)

The benefits in the modest increase in efficiency are not so much from reduced energy usage, but the higher efficiency reduces the amount of waste heat that has to be removed from the PCU. The higher junction temperatures allowable with SiC makes the cooling task even easier. What has Toyota excited is that the PCU with SiC is much smaller than the PCU with standard silicon power devices.

about 3 months ago
top

The World's Worst Planes: Aircraft Designs That Failed

calidoscope Re:Stupid (209 comments)

Except that Boeing, Convair, Douglas and Lockheed figured out how to put windows on pressurized airliners before the Comet flew.

about 3 months ago
top

Toyota Describes Combustion Engine That Generates Electricity Directly

calidoscope Re:Efficiency? (234 comments)

The transmissions on current GE and EMD diesel electric locomotives are about 94% efficient from the output of the prime mover to the driving wheels. I would expect electric car motors to be on the order of 90 to 95% efficient, so this should compare favorably with a mechanical tranny.

Speaking of locomotives, the free piston gasifier was being heavily researched in the 1950's as a more efficient realization of a gas turbine and something that could compete with diesel engines as prime movers.

about 4 months ago
top

The Problem With Congress's Scientific Illiterates

calidoscope Re:Holdren isn't as literate as one might think (509 comments)

Back in the 1970's, Holdren was also going around saying that clean coal was safer and better for the environment than nuclear. His "analysis" showed that the largest number of deaths would come from grade crossing accidents with coal trains. After hearing that, I never took him seriously as he is more of activist pretending to be a scientist.

about 5 months ago
top

Utilities Fight Back Against Solar Energy

calidoscope Informative parent post (579 comments)

Parent post makes a great deal of sense. With PV generation reaching 100% of minimum circuit load for some circuits, HECO is justifiably concerned about how to safely handle the generation.

about 8 months ago
top

Utilities Fight Back Against Solar Energy

calidoscope Safety issues with grid tie-ins (579 comments)

One huge difference between attaching something to the phone network and direct back-feed connections to the grid is that the back feed can be deadly if there's an issue with the local distribution network. This is usually taken care of by the anti-islanding circuitry in an inverter designed for grid tie use, and the utility has both the right and duty to make sure that circuitry is present and working in any grid tied installation.

about 8 months ago
top

Utilities Fight Back Against Solar Energy

calidoscope Peak demand time (579 comments)

FWIW, the peak demand in California typically occurs about 6PM, well after most PV installations fall off the grid (peak production from solar occurs at 12noon and solar output is largely gone after 3PM). This data is from the California ISO website. This implies that grid tied PV solar without some sort of power storage is NOT an effective source of peak shaving.

about 8 months ago
top

Should the US Copy Switzerland and Consider a 'Maximum Wage' Ratio?

calidoscope No account for company size? (1216 comments)

Seems to me that a cap on CEO to average pay take company size into account, the ratio should be smaller for a company with 100 employees than it would be for a company with 100,000 employees.

about 9 months ago

Submissions

calidoscope hasn't submitted any stories.

Journals

calidoscope has no journal entries.

Slashdot Login

Need an Account?

Forgot your password?

Submission Text Formatting Tips

We support a small subset of HTML, namely these tags:

  • b
  • i
  • p
  • br
  • a
  • ol
  • ul
  • li
  • dl
  • dt
  • dd
  • em
  • strong
  • tt
  • blockquote
  • div
  • quote
  • ecode

"ecode" can be used for code snippets, for example:

<ecode>    while(1) { do_something(); } </ecode>