Follow Slashdot stories on Twitter

 



Forgot your password?
typodupeerror
For the out-of-band Slashdot experience (mostly headlines), follow us on Twitter, or Facebook. ×

Comment: Re: Isaac facepalming himself in the grave (Score 1) 27 27

Maybe Isaac Asimov was unhappy with his novelization of the movie, bit I like it. It is the one example I have ever read where the novelization of a movie improved on the movie.

There is a bunch of stuff in the movie that is just there, not explained. Why will the submarine stay tiny for only 60 minutes? Where does the sub go at the end? Asimov came up with reasonable explanations.

There was one bit from the movie that was just too stupid, so Asimov just omitted it. Someone brought a little box onboard the sub, and dialog explained that it contained an atomic particle to power the nuclear reactor. "We are going to be so small that all we will need is one particle..."

Hmm, now I kind of want to watch the movie again.

Late in his life, Asimov wrote a sequel. Since I loved the first one, I tried to read the sequel, but it bored me and I never finished it.

Comment: Re:Harder: self-stabilizing parachute, or balance (Score 1) 496 496

by steveha (#49741407) Attached to: The Brainteaser Elon Musk Asks New SpaceX Engineers

I'd argue you are going to need a heck of a lot more rocket fuel for deceleration than the mass a parachute system would require.

I'm not so sure of that. But I'm not an expert. Most of what I (think I) know about space I learned by reading through long discussions on the Internet.

In this case I am thinking back to discussions of SSTO craft and whether or not wings make sense; the experts all agreed that it would be better to land as a rocket than add extra mass to the system. And the key is that the thing lands almost empty... when it's taking off it's boosting itself full of fuel plus whatever upper stage(s) are in use; when it's landing it's just decelerating its own empty weight.

Comment: Re:Harder: self-stabilizing parachute, or balance (Score 1, Informative) 496 496

by steveha (#49740453) Attached to: The Brainteaser Elon Musk Asks New SpaceX Engineers

Which of these strategies do you choose:
a) Attach a parachute to the nose and let basic physics work.
b) Try to balance it atop rocket engines firing from the bottom.

I realize you were going for humor (and got it; congratulations on being moderated +5 Funny). But here's a serious answer.

It depends on what you are trying to accomplish:

If your top priority is to save the rocket stage, then you pursue an engineering strategy that has the best chance of saving the rocket booster. Maybe that means a parachute system; I don't know.

But a parachute system adds mass and complexity. It becomes another critical system ("if the parachute fails, we lose the rocket stage"). The rocket stage needs functioning rocket engines, so landing on the rocket engines is another use for those engines rather than a new system with a single purpose. All else being equal, the simpler design with fewer systems is more likely to succeed in its tasks.

If you add a few hundred kilograms of parachute system mass, that's going to mean the booster can push less mass to orbit. I'd guess that the loss factor is higher than 1... that each additional kilogram of non-fuel mass on the booster reduces the to-orbit capacity by more than one kilogram. But ask a physics expert for the actual numbers.

Note that new software to make the booster land on its engines does not add mass to the booster.

So I'd say that if your top priority is to efficiently deliver stuff to orbit, the parachute system is right out and the clear engineering decision is (b).

Comment: Re:My god you people need to think about economics (Score 1) 1094 1094

by steveha (#49733571) Attached to: Los Angeles Raises Minimum Wage To $15 an Hour

pays their full-time workers so little that they can't afford food or a place to live without welfare and foodstamps?

Could you please provide a source for this claim? In 2014, the Wal-Mart blog fisked a hit piece that was claiming things similar to what you just claimed, and pointed out that the average hourly wage at Wal-Mart was $12.91 per hour (and that is specifically not including highly-paid management).

http://blog.walmart.com/fact-check-the-new-york-times-the-corporate-daddy

How does it help me that my tax dollars have to subsidize Walmart employees

http://www.forbes.com/sites/timworstall/2013/11/13/apologies-but-welfare-payments-to-employees-are-not-subsidies-to-walmart-and-mcdonalds/

Wal-Mart makes about 3% profit. In comparison, Apple Computer makes about 24% profit. Additionally, Wal-Mart has a more ethnically diverse set of employees than Apple Computer has. You seem to hate Wal-Mart; do you hate Apple Computer even more?

https://www.aei.org/publication/every-month-walmart-gets-one-profit-day-from-its-sales-while-apple-gets-7-5/

Also, low-income people like to shop at Wal-Mart because the low prices are a benefit. Some economists have written papers attempting to estimate the impact.

http://www.forbes.com/sites/timworstall/2013/08/11/walmart-destroys-jobs-yes-but-the-benefits-go-to-consumers-not-the-top/
http://www.nber.org/papers/w11809

So, to summarize: Wal-Mart pays a lot of taxes, employs a lot of people at an average hourly rate 78% over the US federal minimum wage, and benefits the poor by helping them spend less on the things they need.

I just don't understand all the Wal-Mart hate.

Comment: Re:Daily carry (Score 1) 278 278

by steveha (#49704007) Attached to: Ask Slashdot: What's On Your Keychain?

What I have in mind for the "companion tool" is the sawblade, the metal file/metal saw, magnifying glass, and possibly pliers. Plus whatever else they can fit without making it any wider.

The problem is that they sell a knife that has everything my knife has on it, plus some or all of the above list. (Example: the Craftsman) I don't want the weight or bulk of a single tool with all of that stuff.

Comment: Re:Daily carry (Score 1) 278 278

by steveha (#49703877) Attached to: Ask Slashdot: What's On Your Keychain?

Brother, you better hope you never fall off a pier, or you're gonna sink like a stone.

According to my kitchen scale, everything I listed (other than the cargo pants and the extra money in the wallet) together weighs 360 grams. That's 12.7 ounces or a little over three-quarters of a pound, and it's spread across two pockets.

When I wear dress pants, like for a suit, I don't carry all that stuff but it's more because the pockets would visibly bulge and not because it's a lot of weight.

Comment: Daily carry (Score 3, Interesting) 278 278

by steveha (#49701709) Attached to: Ask Slashdot: What's On Your Keychain?

Almost all the time, I wear cargo pants because I want pockets.

On my keychain, I have a simple tool for poking reset buttons that are inside small access holes; I made it from a paperclip. I also have a SwissTech folding pliers tool, which I mostly use for its screwdrivers.

I also try to never be without a paper towel or at least napkin in a pocket. If someone spills coffee or something I have the fastest response time, and sometimes I want to dry my hands in a bathroom that is out of towels.

I carry a Swiss Army knife, one that isn't as thick as my forearm so it doesn't have pliers or a saw. It does have both scissors and a corkscrew. I used to carry one with a Phillips screwdriver, but the SwissTech on my keychain covers that now, and once when someone really needed a corkscrew I didn't have one. Never again! Not on my watch!

(By the way, I have always wished that the Swiss Army knife companies would make a "companion" tool, that doesn't have the basic knife blades and screwdrivers but has the saw, the file, and the other more exotic tools. I'd sooner carry two slim tools than one thing as thick as my forearm.)

I carry a Fenix E11 pocket flashlight. It runs for many hours on a single AA cell, with plenty of light, and it has a high-power mode. It claims 8 hours for the 35 Lumens mode, and less than 2 hours for the 100 Lumens mode. I haven't verified those numbers. I love this thing: it uses a Cree LED to produce a really bright white light. It's 21st Century technology; nobody could make such a thing in the 20th Century.

I carry a Spyderco "Delica" folding knife. It's just the thing for opening packages from Amazon or whatever. It locks open for safety, and I love the thumb hole for one-handed opening. (I'm amazed that they were able to patent that. Once that patent expires I reckon most lock-back knives will have a thumb hole for opening.)

I also carry a Spyderco "Rescue Jr." folding knife. It's specifically designed for tasks like cutting a seat belt when rescuing someone from a crashed car. I've never needed it for this purpose, so its other purpose is that I keep it clean, and if someone needs a clean and sharp knife for food, I offer that one. The Delica usually has little slivers of packing tape or other crud on it from opening delivery boxes.

I carry an "unbreakable" pocket comb. Not only do I use it to comb my hair, but I usually use it to prop a door open when I want to make sure the door doesn't lock closed behind me.

I carry a Fisher "space pen" in black ink, and a cheap disposable pen in blue ink. I can easily tell which is which, and if someone wants to borrow a pen I usually loan them the cheap one and don't get upset if I don't get it back. (If I loan the Fisher, I keep the cap; this reminds people that they need to give it back.)

I carry enough cash for cab fare or a meal, buried in my wallet. I try never to use this as I want it to be there if I ever need it.

I also have a backpack that has a whole bunch of stuff in it (USB charger and USB cables kit, mini first aid kit, etc.) but the above is what I carry all the time.

Comment: Enough with the Keurig hate (Score 1) 270 270

by steveha (#49700097) Attached to: Here Comes the Keurig of Everything

I'll state up front that I agree: Keurig coffee isn't great. The beans were ground months ago, the amount of coffee isn't a lot, and it's pretty easy to do better.

Yet these machines fill a niche. There is a reason why they are popular, and that reason isn't "everyone but you is an idiot".

Several places the Keurig works:

A small office, where a conventional coffee maker would result in throwing away half-full pots of unused coffee. The Keurig contains the mess, so the office won't have coffee grounds everywhere. (If you work at an office where nobody ever makes a mess and leaves it for others to clean up, great! Get a real coffee grinder and something better than a Keurig!)

A small restaurant like a burger shack, where sometimes people order coffee but it's not that common. The Keurig is fast and the coffee will be better than most ways a burger shack could make coffee.

At home, for someone who values convenience more highly than saving money or having tasty coffee. Or, as a way someone who doesn't drink coffee can offer coffee to guests. (The K-cup capsules have a longer shelf life than fresh coffee beans.) Also a way for someone who normally doesn't drink decaf to keep a little bit of decaf around.

I don't own a Keurig and I don't want one. But I don't sneer too much at those who choose to own one.

P.S. If you run a burger shack and you want to serve coffee, look into the AeroPress. Not as convenient as a Keurig but convenient enough, and makes better coffee.

Comment: Re:Snowball effect (Score 1) 469 469

by steveha (#49635289) Attached to: Why Was Linux the Kernel That Succeeded?

I think perhaps my original post doesn't give enough credit to Linus himself. I'll correct that here: not only was he diligent in rolling up contributed code, he was skillful at managing the project. Like Steve Jobs, he gave "unity of command" and made many more correct decisions than incorrect decisions.

Not only that, but he was able to adapt as the project evolved. I imagine that what he does these days is very different from what he was doing in the earliest days, but he has grown and learned and he's still doing a fantastic job.

So add that to the list: another reason why Linux became the kernel that succeeded: because it had Linus Torvalds managing it, and Linus managed brilliantly.

Comment: Re:Cuz Minix Dude Was A Old Guy (Score 5, Informative) 469 469

by steveha (#49632797) Attached to: Why Was Linux the Kernel That Succeeded?

Linux is not a copy of Minix, the code is quite different.

Yes. Linux and MINIX are both *NIX-style kernels. But MINIX uses a microkernel design while Linux is a monokernel.

Professor Tanenbaum famously told Linus "Be thankful you are not my student. You would not get a high grade for such a design :-)"

https://groups.google.com/forum/?fromgroups=#!topic/comp.os.minix/wlhw16QWltI%5B1-25%5D

So anyone who claims that Linux is a "copy" of MINIX really doesn't know what they are talking about.

Comment: Re:Snowball effect (Score 4, Informative) 469 469

by steveha (#49632407) Attached to: Why Was Linux the Kernel That Succeeded?

A few more comments to expand on the above.

A project like Linux would not have been possible without the GNU project, most particularly the GCC C compiler. Commercial UNIX releases charged something like $2000 for a C compiler, but thanks to Richard Stallman there was a free C compiler for Linus to use, and Bash and everything else.

Before Linux was released, MINIX was a popular choice for a free *NIX. But licensing issues tangled up MINIX: to build MINIX you needed to buy Tanenbaum's book, get the source code that came with it, and then apply all the community patches (which had to be kept separate purely for licensing reasons). If Professor Tanenbaum could have released the source to MINIX under GPLv2, and he or someone else had worked as hard as Linus did to collect and apply patches to improve it, maybe MINIX could have gotten the snowball effect going. (Note that MINIX was what Linus was running when he wrote Linux!)

As others have noted, there was at least one BSD available around the time Linux got going, but there was the dark shadow of a lawsuit and the future of BSD looked uncertain. Linux had the advantage of being all-new code with no legal uncertainty. Absent the lawsuit, maybe BSD could have gotten the snowball going.

Comment: Snowball effect (Score 5, Insightful) 469 469

by steveha (#49631957) Attached to: Why Was Linux the Kernel That Succeeded?

It's not a big mystery. Linus released a primitive kernel that worked, at the right time, with the right license, and then diligently kept rolling up contributions and releasing the result.

Expanding a bit:

While the first release of Linux was primitive, it worked. People hungry for a free *NIX were able to grab it and run it. At the same time, HURD was a big research project; if you just wanted to run *NIX on your own computer, HURD was not at all ready.

Linus released it at the right time. It was just becoming possible for large numbers of people to get the kernel from him, and to send contributions back to him. Something like Linux might not have worked at all before the Internet and/or BBSs; it would have been too difficult to send releases out and collect contributions of code.

Linus used the right license. He has said that the choice of releasing under GPLv2 was the best decision he ever made. Arguably a BSD license could have worked as well, but many people have a fear that if they contribute to BSD projects, that evil companies might benefit from their work; with GPL they are comfortable contributing. Also, IBM contributed some code that uses IBM patents; because of the GPL, IBM knew that commercial entities wanting to use the patents would still need to license the patents from IBM. So Linux got the largest possible pool of contributors.

And then there is the fact that Linus worked hard managing Linux. He collected patches sent by people and rolled them in. These days he writes very little code himself; almost all he does is manage patches. I'm not sure how much code he wrote in the early days, but I think his diligent application of patches sent to him helped Linux to become stable and useful.

Given all of the above, Linux was a success, and success bred more success (the "Snowball effect"). People who just wanted something that worked could grab Linux as it worked better and better all the time; people who wanted to join an active project joined it as it was the most active project.

If Linus hadn't released when he did, another project might have gotten the snowball momentum thing going and become the big popular project. But he did, and he worked hard to keep it going, and the result is the kernel that changed the world.

Comment: Re:Apple may not keep that port forever (Score 1) 113 113

Dude, are you seriously this worked-up about a throwaway joke?

In any event, as the other AC noted, I was suggesting that this shipped port would never be official as it is not patented, and that a future watch would have a different and patented port.

My little bit of snark is somewhat founded on fact: Apple really does like to patent their connectors. MagSafe power connector: patented. Lightning: patented. So it is possible that Apple is going to keep this connector unofficial and undocumented, and later release a documented and patented connector. But really I was just having a bit of fun there.

Comment: Apple may not keep that port forever (Score 4, Insightful) 113 113

I remember the first model of iMac had an undocumented card slot. People speculated that Apple used the card slot for factory diagnostics on the iMacs; third-party companies took advantage of the slot to add 3D accelerators; and then Apple revised the iMac design and left that port out.

http://www.macworld.com/article/1014902/imacboards.html

If Apple hasn't announced the port, the port may be gone from the next iWatch release.

Likely the problem is that there aren't enough patents on the port. Perhaps Apple will add a documented expansion port once they find some patents to encumber it.

The rate at which a disease spreads through a corn field is a precise measurement of the speed of blight.

Working...