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## Comment Re:Unplug (Score 1)327

Whether something feels hot or cool isn't a good indicator. That varies greatly depending on venting, and size of the housing. So your tiny little cell phone charger might *feel* just as warm as an old, *large* transformer, while consuming several times as much power.

Well duh, of course I'm not comparing an old-style wall wart in front of a fan to a modern wall wart in a closed box. Anyway, you would have to compare temperature difference (relative to environment) multiplied by surface area. Since most switched-mode wall warts are much smaller than iron-core transformers with the same power, the evidence that switched-mode wall warts waste very little electricity only becomes stronger: small area cool to the touch versus large hot area.

## Comment Re:Unplug (Score 3, Informative)327

Modern switched-mode wall warts use negligible power in stand-by. You can feel it: they stay cool when not in use, unlike the old ones with iron-core transformers.

Bigger hidden consumers over here are the pump of the hot water system (100 W while running) and the airconditioner in standby. I use the ac only a few days per year, but I found out that it sips 15 kWh per month waiting for a signal from the remote control.

## Comment Re:Why a first calculator anyway? (Score 1)328

I can quickly test an idea in the time it takes someone to open their laptop and wait for it to come out of suspend.

I take it that I'm not that much into electronics, but when I'm at work and not in a meeting, I usually have a computer nearby, usually with Gnuplot running in some window, which I use both as a symbolic calculator and as a quick way to plot mathematically expression. (Gnuplot can also handle complex-number arithmetic, which may be relevant for analog electronics). Could you give an example of something that would be easier to do in a calculator?

## Comment Re:what cost (Score 2)363

My huge power draw is the heater and the hot water heater. No problem. We have these things called Batteries...

Huh? From sunlight to electricity to battery storage to hot water sounds like a rather inefficient and expensive roundtrip. Why don't you use a solar water heater and/or store hot water in a well insulated tank?

## Comment Why a first calculator anyway? (Score 1)328

It's not really an answer to the Ask Slashdot question, but I don't see why one would want to use a non-approved programmed calculator.

The point of a calculator during exams is that you have a single tool with well defined capabilities, so as not to get an unfair advantage above students using a different brand of tool. For actual (professional) engineering calculations you will use a computer with decent programming tools (matlab, python, C/C++, or whatever your favorite is). In my 22 years of university (physics), scientific research, and industrial engineering, I have never felt the need for a fancy calculator. Nowadays I have RealCalc (Android app, clone of the decades-old Casio FX-8x line of non-programmable calculators) if I need a quick calculation during a meeting and a computer (combined with pen and paper) for everything else.

If your exams require that you have a graphing calculator, you'll probably need one. But I've never seen them used around me (R&D department counting a few thousand mechanical engineers).

## Comment Re:Stupid idiot messages (Score 4, Insightful)526

"'Car needs service. Car may not restart.' WTF? "

I'd say this is exactly the amount of detail that you need while driving. Really, what would be the added practical value of "Battery bank 7 temperature exceeded threshold level 1 based on mean power over last 15 minutes, click here to see a plot" for your decision to stop now, drive home, or drive directly to the service station?

I wouldn't be surprised if more details can be found somewhere under "advanced status" or something.

People are not going to suddenly spend half their day on a bus driving back and forth because suddenly it's free

Actually, I think that that is exactly what will happen. See the other comment about loitering (sitting on the bus/train forever to keep warm). Other example: some 20 years ago, Netherlands introduced unlimited "free" public transport (bus and nation-wide trains) for students (age 18-24 years). It created a huge surge in passenger numbers, much more than what could be covered by the reduction in monthly allowances. So much that in the next few years, they restricted the hours of usage *and* increased the fees. I also recall that several courier services popped up, operated by students using their unlimited subscription to deliver packages on the other side of the country.

how about make public transport free and just pay for it through a flat levy?

I'm all for subsidizing this kind of public infrastructure if only because the alternative is using tax money to deal with all the extra traffic. However, I don't believe that making it free is a good idea. Transportation, public or not, still costs money; with free public transport, all financial incentives for people to reduce unnecessary movements disappear, as do financial incentives for the operators to increase efficiency. This is asking for ever increasing costs of the public transport system.

## Comment Re:How close? Within WiFi range? (Score 1)285

"cargo capacity of around 2100lbs which is within a couple hundred pounds of 10,000 kg."

Off by a factor 10. It's 22,000 lbs. you'll need 10 of those cars.

## Comment Re:Geo-fencing, nothing more. (Score 2)188

"If stuff is bought with a stolen credit card then the credit card company or the bank bears the risk."

I highly doubt that; the thief could have a friend set up an online merchant, make \$2000 purchases of virtual goods and split the profit.

The reason merchants are so careful is that the merchants will have to eat the loss in case of a fraudulent transaction.

## Comment Re:proven wood gas technology since 1839 (Score 1)228

It works. During the WWII there were around 700,000 wood gas powered automobiles

But those combusted all of the wood and did not leave carbon behind as charcoal.

## Comment Re:I only go... (Score 1)415

... very painful death by lockjaw unless you vaccinate against it roughly every 10 years, aren't you? A tiny little scratch suffices, especially when you're in contact with earth or rusty metal. Even an old razorblade can kill you ...

From https://en.wikipedia.org/wiki/Tetanus : Objects that accumulate rust are often found outdoors, or in places that harbour anaerobic bacteria, but the rust itself does not cause tetanus nor does it contain more C. tetani bacteria. ... Hence, stepping on a nail (rusty or not) may result in a tetanus infection, as the low-oxygen (anaerobic) environment is caused by the oxidization of the same object that causes a puncture wound, delivering endospores to a suitable environment for growth.

it is unlikely that a little scratch would create the necessary anaerobic conditions. And unless you keep razorblades buried in soil, those are not likely to carry the spores either.

## Comment From the .... department (Score 3, Informative)82

Slashdot added "from the .... dept." to the article. The lameness filter prevents me from pasting the morse code here, but it seems to translate into: "R T L L S - S E N D - I N V E R T E D - T E S S A N E". But now I am none the wiser, what does that mean?

## Comment Re:Bad idea. (Score 1)189

Did you remember to factor the cost of life in?

No, only the gut feeling that 1e-7 per year is a very low risk compared to e.g. the risk of getting killed in traffic (1e-4 per year). What I read is that F3 tornadoes can usually be survived by staying in an interior room; for F4 and F5 you need an underground shelter or reinforced room. The question is more whether it makes sense financially to build the entire house tornado-resistant or even spend \$10,000 on a storm shelter.

telling them that those lives are only worth as much as the insurance.

It is cold, but the value of life is estimated to be around 7 M\$, based on how much people want to be paid to take risks, and on what (government) measures to prevent loss of life cost. Based on that, a measure that increases the survival probability for an F4/F5 tornado would be allowed to cost about \$1 per person per year.

Disclosure: Tornadoes don't affect me as I live in Netherlands. I should be more worried about flooding...

## Comment Re:Bad idea. (Score 4, Informative)189

People who decided not to live in plywood boxes in tornado country, or in wildfire area or below the sea level between a lake and the sea, or below the river level etc should not be asked to shoulder the burden

For hurricanes and floodings, which could devastate large areas in a single event, I see your point. However, a single tornado usually impacts only a small area. The probability of an individual house in Tornado Alley being struck by an F4 or F5 tornado seems to be 10^(-7) per year. Economically, it makes more sense to insure the risk than to build an F4-tornado-proof house. I couldn't find probabilities for F3 tornadoes, but I could imagine that a similar argument holds there.

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