Please create an account to participate in the Slashdot moderation system


Forgot your password?
DEAL: For $25 - Add A Second Phone Number To Your Smartphone for life! Use promo code SLASHDOT25. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. Check out the new SourceForge HTML5 internet speed test! ×

Comment Re:module efficiency (Score 4, Informative) 286

Exactly. I ran some back-of-the-envelope calculations on this 3.5 years ago in another Slashdot thread.

And because we're presumably too lazy to click that link, I'll paste it below for your reading pleasure...

This is why: []

There simply isn't enough solar power delivered to the surface of the aircraft, even at 100% conversion efficiency, to move people and luggage using only available sunlight.

Google tells me direct illumination to a surface perpendicular to incoming full intensity sunlight is about 1.4 kW per square meter. Google also tells me that the wing surface area of a 747 is around 5500 square feet. Only half of the 747 wing is directly illuminated by sunlight at any given moment, but the surface of the fuselage could be covered with photocells as well, so 5500 square feet overall is probably a decent estimate for the directly illuminated surface area of the aircraft as a whole. And for hand-wavy purposes lets assume that the entire surface of the 747 is perpendicular to the incoming sunlight (i.e. a planar plane... pun totally intended). And that we have perfectly efficient photocells giving us 100% conversion efficiency. Running the math, this gives us around 715kW under bright direct sunlight, or about 959 horsepower -- the equivalent of 1.5 2012 Ford Shelby GT500's.

Each engine of a 747 generates around 15,000 horsepower at cruise, and around 30,000 at takeoff, and a 747 has four engines. So you need around 125 times the power generated by a perfectly efficient perfectly illuminated solar-powered 747 to get said plane off the ground, and around 65 times the power for cruising. And then you could only fly it in the middle of the day near the equator.

Comment Twin Cities (Score 4, Funny) 464

The Minneapolis/St. Paul area has a relatively high-tech (depending on your area of tech) employment base, with headquarters or significant offices for 3M, Medtronic, Cray, Silicon Graphics, Ceridian, Toro, Thomson Reuters, Target, Best Buy, Wells Fargo, US Bancorp, St. Jude Medical, Polaris, Digi, Imation, CHS, Shutterfly, General Mills, Cargill, Seagate (though I think that operation was purchased by someone else), and Digital River. There's plenty of small tech-oriented business around here as well.

Come for the low unemployment and reasonable standard of living. Stay because your car won't start all winter.

Comment Family, hobbies, and charities, oh my (Score 1) 842

I'd pay off my mortgage, remodel the house a little bit to make it more usable, and look around for a reasonable lightly used car to replace my wife's aging vehicle. Then I'd help my siblings (and my wife's) out by paying off mortgages, school debt, and the like. I'd set up some sort of financial structure to make sure that my wife and, should they come along, my children would live without financial stress for the rest of their lives after I pass away. And a goodly chunk right off the top would go to my church and another religious organization that was very important in my life.

After that, I'd take up a bit of travel. I'd take lots of guitar lessons and buy more music equipment than someone of my skills can reasonably justify. I'd set up an endowed foundation to perpetually help fund the type of charities and other organizations that I think need supporting. And maybe get back to taking dance lessons regularly. I'd go to more concerts, and pay for better seats and the occasional meet-and-greet. And I'd spend time developing an open-source project idea that I've had for several years. And I'd probably pay someone else to mow the lawn, tend to the flower garden, and clear the driveway of snow.

Comment 36 hour bus commute (Score 1) 654

This article caused me to wade through my major metro area's online system to plan a trip between my new house, which is within blocks of a suburb park and ride facility, to my work, in the same town. By car this is a 10 minute trip, maybe, depending on the state of traffic lights.

At first the online system told me the trip was impossible at the time of day I specified. So I dug deep into the site and pieced together what appears to be the only possible set of routes that connects these locations without sending me to the downtown core for connections. After much digging I found that, for all practical purposes, the route is indeed impossible. It appears that, due to one key route only running in the very early morning and late rush hour, it would take me around 36 hours to commute each way.

If I took the bus all the way to the downtown core then back to work I still can't do it, because the morning bus to my work stops running before I arrive downtown.

Yeah. Not happening.

Comment Economics (Score 4, Interesting) 148

Could someone fill me in on the economics of nuclear power generation? I'd like to know what the usual payback period for a plant is, and how much it costs to operate a plant over that period.

Just doing some napkin figuring here, if the plant ran 24/7 at full capacity for a 20 year payback period, and assuming that operational costs are about the same as initial construction costs (i.e. using the $10 billion number from the summary, so $20 billion for construction and operation), that gives me a figure of about 5.7 cents per kilowatt-hour. Obviously the plant wouldn't run at full capacity for 20 years straight, but that does put something of a lower bound on the price of power generation, and it seems like a reasonable number given US electricity prices.

I'd also like to know how this compares to hydro, gas, coal, solar, wind, tidal, and any other generation method currently in use.

Comment Re:Snow Leopard (Score 3, Informative) 96

If I upgrade to 2G of RAM, it looks like I can upgrade to Lion, but not Mountain Lion. I was going to upgrade the RAM anyway because it seems to run a bit sluggish, but the Mini maxes out at 2G, which is the lower limit of Lion. So it may be a wash, performance-wise.

No, it will be a huge step backwards. Do not, under any circumstance, install Lion if you can possibly avoid it. Not only is 2GB not enough to run Lion in any reasonable manner, but even if you have more RAM than that, Lion is a molasses sucking pig. The last OS for any hardware I used that was that bad and that much of a step backwards from what came before it was... umm... Wow, can't think of one. Lion wins. Or, actually, loses.

Installing it was the worst single decision I've made regarding Apple software on my early 2008 MacBook Pro. I even did a clean install from official Apple USB media (i.e. the USB fob you had to pay extra for instead of just downloading it) and upgraded RAM to 4GB on account of Lion. Take it from myself and several of my coworkers who regretted every getting within 100 feet of Lion that it is best avoided. Mountain Lion didn't suck, but only by comparison to Lion. Mavericks is a little bit better yet, but still not nearly as snappy as Snow Leopard.

My gut reaction: Don't worry about Snow Leopard being out of date, even security-wise. A man-in-the-middle is rare in most environments, and Snow Leopard is already quickly diminishing in market share, so it's not terribly likely to be widely exploited. Compared to the every day pain you'll cause yourself by installing Lion or later, the tiny risk profile of running a vulnerable Snow Leopard is worth it, in my opinion.

Comment Re:diagreeing with same sex marriage != hate (Score 3, Interesting) 1746

Your observation jives with one of my own thoughts on the matter.

Many people have something which they incorporate as the center of their identity, be it their race, their ethnicity, their gender, their sexual proclivities, their religion, their choice of operating system, their athletic team, their place of origin, their family, their career, their hobby, and so forth. People who have convinced themselves that their very identity is tied first and foremost to one aspect of life have an incredibly strong, even visceral, reaction to anyone who expresses anything less than complete agreement with them. There is a term for this: zealotry. A zealot is unable to distinguish disagreement with their view from a personal attack or even hatred, as their very identity is melded with that for which they are zealous.

One of the most zealous sets of people we see today (at least in my myopic U.S.-centric personal experience) are homosexuals. Perhaps I'm mistaken, but my observation seems to be that this particular group of people has made homosexuality the defining feature of their life. As such, even minor disagreement with the idea that homosexuality is completely normal results in a strong adverse reaction and accusations of fear and hatred.

Personally I am saddened by this, that people have focused so strongly on one aspect of their identity so intensely that they view themselves first and foremost as that thing, rather than as a person, complete and whole. This is unhealthy, and when widespread (as we see today most strongly in both political zealotry and the zealotry of homosexuality) we end up with a fractious society that struggles to engage in a civil exchange of ideas, and at its worst can lead to quite literal violence and bloodshed.

Comment Re:Is there an end to this? (Score 1) 352

I certainly hope not.

My sister's car was damaged when an SUV rear-ended me as I was stopped at a traffic light. The driver of the SUV did stop, but refused to identify herself and provide insurance information. I could tell by the driver's actions that she was about to flee, and quickly noted her license plate number, and sure enough she fled while I pleaded with her to reconsider what she was about to do.

It took about a month longer than it should have, but eventually the machinery of justice caught up with the driver, and my sister was made whole for her financial loss. If it hadn't been for a clear and visible license plate it is doubtful that any compensation would have ever been recovered.

Comment Re:Liked SC1 better than SC2 (Score 1) 160

While overall I liked SC2 better than SC1, I too missed the strategy game aspect of SC1, for much the same reason -- it was a quick strategy game instead of a long RPG-like adventure. SC2's humor was spot-on, so that was a huge bonus.

I remember not having a code-wheel to use to start up SC1, but my college roommates and I knew that "PARTY" was one of the answers to the startup challenge screen, so whenever we'd want to play it was "cd \games\starcon", "starcon", followed by repetitions of "party", "party", "party", then F3, until the game let us in.

Also, the SC1 music emitted by the old Radio Shack "Game Blaster" was better than that from the Sound Blaster that I replaced it with -- I can still feel the melee music in my bones 23 years later.

Slashdot Top Deals

UFOs are for real: the Air Force doesn't exist.