Follow Slashdot stories on Twitter


Forgot your password?

Comment Re:Efficiency (Score 1) 869 869

It is known that hydrocarbon powered cars typically turn chemical energy into mechanical motion at about 35% efficiency (45% for Diesels). It is known that large power plants generate electricity from fuel at about 50% efficiency. The process of charging a battery is about 75% efficient, turning electrical energy into chemical energy. The reverse is also true, for battery discharge (75%), and the electric motors of an electric car are about 95% efficient. We multiply these numbers to get the overall efficiency of conversion of original fuel energy into mechanical motion for the car: about 27%. Even allowing for regenerative braking energy-recovery, it looks like ordinary cars win the efficiency thing here. We need better than that!

Traditional cars and power plants don't use the same inputs. Even if electric cars are less efficient, they can potentially be powered by renewable energy sources rather than hydrocarbons.

Comment Re:When they get rude (Score 1) 217 217

When people hear that I can program apps I often get hassled by someone who of course has the next multi million dollar idea. I'm not interested but they rarely take no for an answer.

The variant I love is when they want you to evaluate their idea, but they're so cagey about actually _telling_ you the idea that there's no plausible statement you could make about it. I suspect this is all very highly correlated - if you don't know what you're doing and have never seen how hard it is to actually make working products, you don't know whether other people could run with your idea or not. But if you know how hard it is to accomplish something, you know that telling someone else about your idea doesn't matter, they won't be able to accomplish it either.

Comment Precalculate your dependencies and parallelism. (Score 1) 119 119

Init systems seem to model themselves on Makefiles, reading everything at startup and detecting dependencies on the fly then deriving ordering and parallelism. This should all be invariant stuff, instead model things on ninja, where you calculate a giant wad of info and mechanically grind through it at startup.

Comment Re:Systemd and Gnome3 == no thanks (Score -1) 300 300

>As far as I can tell, there is no root account I could log into directly


$ sudo passwd
$ sudo passwd -u root

There, now you can log into root directly and have all the security issues you want. Thanks for playing the "I don't know how to use linux" game

So what you're basically saying is that by default, there is no root account to log into directly? Thanks for spending your (surely very valuable) time verifying this trivial aspect of that post, even though it was irrelevant to the poster's overall point.

Comment This should be the common case, though. (Score 5, Insightful) 140 140

Big deal. If you are running a program which costs money or time, you should be considering whether it is worth running periodically regardless of whether it's a program to collect phone data or bringing donuts to the office. If you aren't revisiting that decision, you're doing your job badly.

Don't get me wrong, I'm not saying they're doing a good job. Just that "Oh, yeah, we considered cancelling that program" is a stupid comment which doesn't excuse anything. Most likely they kept the program more because you don't give up power and money once you have it, and they really didn't care about efficacy.

Comment Re:Heisenberg compensator ... (Score 1) 83 83

You think you have problems? I'm still trying to get my head around "It's both a particle... AND a wave!". How the f--- does that work? It doesn't even make any sense! It's insane! Wave things are not particles, and particle things are not waves!

Don't misunderstand our ability to comprehend something for the reality of the thing. We have tools for particles, we have tools for waves, so we see a thing and think "It's a particle! No, wait, it's a wave! That's weird, it's both!" In reality, it is what it is, regardless of our ability to comprehend it. In some sense there is no human-scale reality to these things, they are mathematical constructs of a certain sort, with interpretations that happen to simplify things in certain cases.

[When I say "human-scale reality" I mean that an electron is not like a tiny tiny baseball, with well-defined boundaries and position and speed.]

Comment man rm (Score 4, Interesting) 329 329

From the rm(1) man page on most Linux distros:
              --no-preserve-root do not treat '/' specially (the default)

                    fail to operate recursively on '/'

Why --preserve-root isn't the default is beyond me, since it would be generally faster to re-create the filesystem if that's what you _really_ wanted.

Comment Re:To be fair (Score 1) 200 200

It's simply not realistically possible to always perfectly plan multiple complex multi-year projects, when every your budget gets cut a little further, and you never know -- it's a roll of the dice -- if or how much it's going to get cut by -- then there is the secondary knock-on effect that of the small budget that remains*, the managers need to very carefully decide where to constantly try shift things around to try keep remaining projects going. The rocket program canceled in 2010 was probably canceled due to budget cuts. NASA's budget has consistently been cut, what, every year for the past 15 years? You can't entirely blame NASA - nobody can plan properly under those circumstances. Nobody, not you, or me, could end up not wasting any of it as a result of the constant shunting around.

If NASA had that same attitude in the 60's, the U.S. would still be trying to put its first man in space.

I think the point is that it isn't NASA's attitude which makes these things happen, it's the attitude of Congress.

Comment Re:No, school should not be year-round. (Score 4, Insightful) 421 421

Kids should have at least a couple of months out of the year when they can just not worry about their studies and have fun and BE KIDS.

The root problem is that school is a stultifying experience in the first place, arguing about whether you're going to somehow improve kids lives by varying the length of vacations isn't really going to change that at all.

One of the reasons we moved our kids to a year-round Montessori school was because of the incredible amount of emphasis public schools have on attendance, at all costs, even at the elementary level. You want to take your kids to Washington, DC to visit the Smithsonian? Fuck that, it's more important for their butts to be in seats at school than to actually engage their minds on something new and challenging. Since we now pay out-of-pocket directly, the main rule on attendance is basically not to be disruptive. Got a chance to take them to the state capitol for a visit on Friday? That's great, go for it!

Comment Re:Cry Me A River (Score 5, Insightful) 608 608

No, he has a point. Back in the day, we had few tools and we learned how to use them.

now, we have a tool for every hour of the week, and as soon as you've mastered one, someone comes along and says "your skills are sooo obsolete, you must learn now or fall behind", so you get to grips with it and start top master it, and then realise its a pile of poop and hunt around for a new, cooler tech to use instead.

Apologies, but we still have all those old tools. We just don't use them any longer. Because you can't use Turbo Pascal to make web pages, but you can use jQuery. If you were working on the same problems today as you were working on 20 years ago, you probably would be using many of the same tools. The only reason you're using the new tools is because you'd rather spend 20 hours throwing something together versus 20 weeks writing it from scratch.

Honestly, if you think this is different than it was in the 90s and 80s, then you weren't paying attention in the 90s and 80s. The technical periodicals were FULL of the new stuff that was going to change everything. The only real difference is that it's easier to find stuff and get distracted these days, simply because the industry is much larger. I assume it was similar as you go back further, I just am not old enough to remember it first hand.

Comment Re:Rewarding the bullies... (Score 3, Insightful) 798 798

Here's the thing: Everyone has been bullied at some point in their life. Not all children are prone to it, but there is always a bigger kid prone to intimidation tactics when growing up.

Getting bullied that once, for a few minutes, is kind of different from being frightened of school itself because you keep getting slammed into lockers, etc. In one case, a thing happened to you and you move on. In the other case it becomes a formative epoch in your life which you spend decades dealing with, if you ever manage it.

How can you do 'New Math' problems with an 'Old Math' mind? -- Charles Schulz