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Comment: Re:Don't Worry! (Score 1) 487

by Alioth (#47768897) Attached to: Climate Damage 'Irreversible' According Leaked Climate Report

If the US and Europe were to reduce carbon output to post civil war levels (i.e. effectively go back to some sort of agrarian lifestyle), China and India certainly wouldn't be using more coal and oil. It is the US and Europe which is driving the demand for fuel in China. It's not Chinese peasants buying all the stuff China puts out, it's generally the West that's fuelling China's increasing demand.

Comment: Re:Correlation Does Not Imply Causation (Score 1) 281

by Alioth (#47763833) Attached to: The Evolution of Diet

Try a bicycle. It's a marvellous machine, probably the most efficient machine that anyone can go out and buy. When you ride a bicycle for utility you're not just riding to get exercise for the sake of exercise, you're getting useful transport out of it, too. In many urban settings, riding a bicycle for transportation is no slower than any other method of transport and is considerably less expensive and considerably less dangerous once you consider the risks of chronic diseases brought on by lack of exercise you'll avoid.

Even where I live (which is very uncongested traffic wise) where cycling has a time cost, I effectively get two minutes exercise for the price of one minute for every two minutes I ride since driving to work still takes half as long as cycling to work, and not only do I get great health benefits from it, I spend far less on my car by not using it all the time.

Comment: Re:Is this at least user-selectable? (Score 1) 475

by Alioth (#47730973) Attached to: Google's Driverless Cars Capable of Exceeding Speed Limit

Speeding up by a given amount and slowing down by the same amount takes exactly the same amount of energy! Also, it doesn't matter where you stop if you're trying to avoid the errant driver who blew a red light, what matters is that the change you make prevents you from trying to occupy the same piece of space at the same time as him. Also if you brake then if the collision does occur, there is significantly less energy to dissipate afterwards than if you try to accelerate and the collision occurs.

You *want* the ABS to kick in. Unless you're super driver then ABS will stop you quicker, it's what it's there for. Even a reasonably high performance car will decelerate twice as quickly as it can accelerate.

A summary of some calculations given in a reply to someone else, in the case of both cars approaching at 40mph (18 m/s) with a best case time decision for when you can say the other vehicle is going to just blow on through the red light: with the best case acceleration in a reasonably high performance car (say, a Focus ST with a sub 7 second 0-60 time) will mean you miss the collision by about 1 meter. Mashing the brakes and letting the ABS do the work will mean you miss the collision by around 16 meters. Even in the pouring rain and halving braking performance, if you brake you'll avoid the collision by nearly 10m. In a normal car, for instance a normal Honda Civic, accelerating will not avoid the collision but instead worsen it as you now have more energy to dissipate after the offending red light runner clips the rear corner of the car. Accelerating to avoid colliding with a red light jumper only makes sense if you're in a Bugatti Veyron or a Lambo or a Ferrari, or a performance motorcycle. But even so braking will be safer since these vehicles have very good brakes and tires.

Comment: Re:Is this at least user-selectable? (Score 1) 475

by Alioth (#47728881) Attached to: Google's Driverless Cars Capable of Exceeding Speed Limit

I just did some back of the envelope calculating on this. In a typical car with decent performance, you can accelerate at about 4 meters/sec sq (about 0-60 in a little under 7 sec). Working in meters because it's a lot easier: imagine this, an intersection with good visibility. At 40 mph approach speed, the earliest you can tell that the other driver is going to blow through the intersection (at right angles to you) will be 2 seconds. Before that he's still got time to stop. But let's say you're suspicious of the other driver so at 2 seconds out you are instantly ready to take action (and not taking action will result in the front corner of your car making the initial collision with the front corner of his car). Your cars are Ford Focus length, 4.5 meters long. You are both doing 40 mph (18 meters/sec).

So where are you at time = 2 if you decide to accelerate? The reference point is the leading edge of your car. The distance you travel will be determined by in this case the function d(t)=18t + 2t^2. At 2 seconds no part of your car must be between 36 meters and 37.8 meters from the position where you decided to hit the gas (so the leading edge of your car must not be at the position 36m to the position 37.8m + length of your car, which is 4.5m, so 42.3m). If you hit the gas the leading edge of your car would be at 44m, so you only just miss and you need to have a high performance car to do that (Focus ST or Focus RS). If you're in a more normal car, or an older car that's a little bit worn out, and have a 0-60 time of 9 seconds (3 m/s squared), the formula would be 18t + 1.5t^2, and the leading edge of your car will be at 42m, in other words the other vehicle will clip the rear of your vehicle and you will now have the additional speed to some how get rid of during the ensuing crash.

What about braking? A typical car will decelerate at 8.2m/s^2 if you slam on the brakes. ( http://www.michigan.gov/docume... ) So the distance formula for braking will be 18t - 4.1t^2. If you were to slam on the brakes, at the critical time the leading edge of your car would be 19.6m from your starting point - you'd miss the collision by a very comfortable 16.4 meters. Even if it were lashing with rain, and your braking performance were halved, you would miss the collision by almost 10 meters.

The conclusion here is that the margins are much much tighter (in the best case, you only get away with it by just over a meter) if you try to accelerate than if you try to brake (where you miss the collision in the worst case by better than 9m). Acceleration in reality would probably be worse than calculated if you're in an automatic transmission car because you won't really start accelerating much until the transmission sorts itself out. In a manual you'll only be better off if at the decision point you're already in the ideal gear for accelerating. Acceleration may be a valid path to take if you are in a Bugatti Veryron or a Lamborghini Countach or on a motorcycle, but even so the margins are going to be much more comfortable if you mash the brakes instead (given a super car has very good brakes, and a performance motorbike has sticky tires and very good brakes). And if the collision does occur, if you've braked there's a great deal less energy in the system so the outcome is likely to be much less severe.

Comment: Re:Is this at least user-selectable? (Score 1) 475

by Alioth (#47728023) Attached to: Google's Driverless Cars Capable of Exceeding Speed Limit

Accelerating through the intersection won't work at all if you're already going 40 (most normal cars don't accelerate that well at that speed, certainly in the US where automatics are the norm you'll have to wait for the transmission to kick down). If you have enough warning of an impending impact that acceleration would make any difference at all, likely maximum braking would prevent the impact altogether.

Comment: Re:Windows 8 (Score 1) 726

by Alioth (#47728001) Attached to: Linus Torvalds: 'I Still Want the Desktop'

I run gnome 3 on a dual monitor setup. It is a development machine, mostly used for Java, C and scripting, but also documentation, web browsing, email (i.e. usual office tasks), system administration of servers etc. I don't have any complaints about it. The only customization I really care about is focus follows mouse, and Gnome 3 supports that without any difficulty.

What's wrong with alt-tab to switch applications? It's what I use and works awesomely well under gnome 3.

Comment: Re:Farce (Score 2) 375

by Alioth (#47727977) Attached to: Would Scottish Independence Mean the End of UK's Nuclear Arsenal?

20 minutes faster journey up north is infinitely more useful to me and millions of others than nuclear annihilation. The HS2 infrastructure is something (well, barring the aforementioned nuclear annihilation) that will be around in a century's time. Trident won't be useful at all and won't have that long of a service life.

Comment: Farce (Score 1) 375

by Alioth (#47727527) Attached to: Would Scottish Independence Mean the End of UK's Nuclear Arsenal?

The whole UK nuclear deterrent is a colossal waste of money anyway. It would be far better to get rid of them (who do they deter? who would we use them against? And in the case of a global thermonuclear war it wouldn't even make a difference anyway) and spend the money on conventional forces that we can actually use and probably are more of a deterrent to potential enemies.

Comment: Re:Stopping staring at your navals (Score 1) 726

by Alioth (#47727199) Attached to: Linus Torvalds: 'I Still Want the Desktop'

The same thing is true of WIndows if you have to install it from scratch, and it doesn't come pre-installed. It can take several hours to get a fully functional Windows build including much searching for drivers unless you have hardware that is completely supported by what MS ships on the installation CD.

If you're complaining about "grep" (which is not an invention of Linux, it's a standard unix tool that has existed since the 70s), try to guess what the "cacls" command is supposed to do in Windows without looking it up.

Comment: Re:Windows 8 (Score 1) 726

by Alioth (#47727177) Attached to: Linus Torvalds: 'I Still Want the Desktop'

I don't know what all the hate of Gnome 3 is other than basic resistance to change. When Debian 7 came out, it had upgraded to gnome 3. Of course being a Debian user I don't get the early and possibly unstable versions - but it took me all of 15 minutes to figure out gnome 3 and I never looked back. It seems perfectly easy to use and does what I want it to do and it doesn't get in my way. This is on my main work system, and I do all tasks on it, use it 8 hours a day, it's not a machine for limited uses. Never felt the desire to go back to Gnome 2 or anything that looks like it.

Two is not equal to three, even for large values of two.

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