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Comment: Mods on crack? (Score 3, Insightful) 880

by orzetto (#48598979) Attached to: Apparent Islamic Terrorism Strikes Sydney

Crusades are easy, that would be a response to 100 years of Muslim rape, slaughter, and forced conversion in Spain.

Aside from the fact that Christians did exactly the same when they reconquered the Iberian peninsula, and aside from the fact that in that time Muslim societies were far more liberal than any Christian society (Jews usually fled to Muslim countries from Christian countries), would you mind explaining why no bloody crusade ever went west to Spain, but all East to Jerusalem?

The crusades were the product of a fanatical Christian society, with the motivation of paradise for the soldiers and spoils of war for the commanders. They sacked, plundered, raped anything between Europe and Jerusalem, and that includes Costantinople that at the time was Christian. Which was expected of any serious army at that time. The pretext for war was the "liberation" of Jerusalem, and the real drive was a combination of poverty, ignorance, greed and religion. So the crusades were pretty much the ISIS of the second millenium.

Do read up some history lest you spout more of such nonsense.

Comment: Re:Electricity vs. oil (Score 1) 194

by orzetto (#48473147) Attached to: Jackie Chan Discs Help Boost Solar Panel Efficiency

It would take a lot of progress to get electricity to be the most economic solution for heating.

This depends a lot on where you live, especially for gas. For house heating, a heat pump is quite efficient, especially if you have a water reservoir available. For cooking, gas looks very cost-efficient since you simply have to burn it under a pot to extract all its heat, but a lot of the heat gets lost as hot air that bypasses the pot. Induction heating uses electromagnetism to generate heat inside the pot's metal, so even though the cost per kWh is higher, you end up using less energy, so it may very well be competitive.

However, you are forgetting the one source I have in my house, district heating. Industries generate enormous amounts of waste heat that could be used for district heating, I remember one air cooler in a refinery that dissipated over 16 megawatts of heat. If you hook up factories, offices and homes with district heating, you can provide heat without any other external source.

Comment: Re:I don't think hydrogen makes sense (Score 1) 293

(My own disclaimer: I am researcher in hydrogen & fuel cells)

Containing hydrogen is no longer much of a problem, though compressing it in the first place is still expensive. Still, you don't really need a distribution network: the trend is to use electrolysers and produce the hydrogen locally. With the increased share of non-programmable renewables like wind and solar, hydrogen stations can produce their hydrogen when there is an excess of available power.

It's not just the price of batteries, which may very well come down: it's their weight. There is only so much that can be done now to increase Li-ion energy density; Elon Musk was dreaming of using graphene for superbatteries, but that's a very long shot. Sure, hydrogen cannot compete in the short range with batteries, but it is much better in the long range. And yes, batteries are much heavier than the tanks containing hydrogen.

The energy density of Li-ion batteries is about 100 Wh/kg, hydrogen is 32500 Wh/kg. Even accounting for 50% conversion efficiency and a hydrogen tank 10 times as heavy as the hydrogen, you still get over 1600 Wh/kg, well over 15 times Li-ion! Then of course you need to add the fuel cell system, which is dimensioned by power (not by energy as the tank is), and its weight is why FC cars are better in the long range, where this weight is a smaller fraction of the total FC system weight.

Running fuel cells on hydrocarbons directly is not an option (slow chemistry), but they can be reformed on-the-fly to hydrogen; in fact you can do that with diesel. The only problem is, the system gets so much complicated it is soon not worth the bother when you have a highly dynamic load as is the case for a car.

Comment: Re:I don't think hydrogen makes sense (Score 1) 293

Holy bad data, batman! You have so many numbers wrong my head is spinning. Try this:

  • needs to be compressed to 1000+ atmospheres Standard H2 pressure in most modern tanks is 700 bars, not 1000. 350 bar is also quite ok since it contains 2/3 of the hydrogen you get at 700 (hint: no ideal gas at those pressures). Very little to be gained by going to 1000 bars.
  • [to generate H2] first you need to generate the electricity. That's usually from a coal plant operating at 45% efficiency at best Or it could be wind farm, or a solar plant, or any of those pesky renewables that do not want to produce power exactly when we need it. So instead of dumping it, you make hydrogen with that extra zero-emission power. That, and combined-cycle gas plants can be 60% efficient.
  • the electrolysis is about 65% efficient at best That's a number for alkaline electrolysis, PEM electrolysis can go much higher. Some cheat and define efficiency with enthalpy instead of Gibbs free energy, which gives them efficiencies close to 100%, but somewhere between 80-90% is realistic.
  • put the hydrogen through a fuel cell which can be 90% efficient in the lab, but peaks at about 70% efficient in commercial applications Actually no, no one has ever seen 90%, not even in the lab, but a common efficiency in usage is about 60%.
  • And by the way you did not mention the significant losses for hydrogen compression, which are not a showstopper but do motivate research in e.g. hydride compressors for hydrogens running on waste heat instead of mechanical power.
  • gasoline ICEs, which are currently about 25%-30% efficient That's your main mistake. This value holds only at their maximum efficiency, which is almost never where they operate. You also fail to account that gasoline does not grow on trees, it needs to be extracted as oil, refined and distributed. The whole Well-to-Wheel efficiency of gasoline is about 10% on a good day.

Comment: Re:MatLab is not really a good programming languag (Score 1) 205

by orzetto (#48203683) Attached to: The One App You Need On Your Resume If You Want a Job At Google

You might have noted I wrote, "OO support as C++", where I meant "well thought-out OO support". There is OO in Matlab, but it's just like claiming Fortran has OO support. Technically true, but added as an afterthought, and most code out there does not use it.

you somehow missed that semi-colons are not statement terminators

Why yes you could write without them, but then you would get an echo on every assignment on the prompt. No sane person would do that in production code. In practice, all statements in M-files need to be semicolon-terminated.

You should have known this if you had actually worked with even a modicum of MatLab script.

FYI I was on Matlab/Simulink several years (before moving to Scilab, Octave and C++), and I actually held a course in Matlab for undergrads at a Max Planck Institute when I worked in Germany.

Comment: Re:About CVS Only! Not SVN! (Score 1) 245

by orzetto (#48193895) Attached to: Help ESR Stamp Out CVS and SVN In Our Lifetime

[...] because those files are binary and very large

No VCS is meant to do this, neither Git, SVN and certainly not CVS. Those files don't belong in a VCS because you cannot make a diff between them. Small binary files (e.g. icons in a website) are a small nuisance, but there is no point in storing large binary blobs in a VCS regularly. What you need is a backup system, not a version-control system.

(2) permanently delete those files that I know I will no longer need

SVN allows to do this with svndumpfilter (and I was unaware CVS had any way to do this). And no it should not be made any easier, no one should be allowed to monkey around with the repository history with any less than admin rights. If you find yourself regularly removing files from a VCS, it means you have been adding too many useless files. Again, you want backup for this, not VCS.

Comment: MatLab is not really a good programming language (Score 5, Interesting) 205

by orzetto (#48175477) Attached to: The One App You Need On Your Resume If You Want a Job At Google

MatLab is an old, crufty, feature-creeped script engine that I try to hold myself away from as much as I can. As a researcher and academic (got up to post-doc), Matlab is indeed ubiquitous in academia, but it's mostly due to entrenched positions. I see fewer and fewer people using Matlab these days, and that's a good thing.

Matlab is by all means not a fourth-generation programming language: it is procedural just like Fortran, which it supplanted in academia, but it does not have type-checking as C, it does not have OO support as C++, it does not do away with semicolons as end-of-line markers like Python; true, it has some advance features like OO and some functional programming, but (almost) nobody uses them, and most Matlab code is a horrible cruft made by self-not-so-well-taught academics. There is nothing in Matlab you cannot do better in Python with scipy, numpy, matplotlib and pandas. Or with declarative PLs like Modelica.

Matlab is also known for outrageous prices, leveraging on the fact their customer base are universities with big pockets and small administrative brains, and large corporations: they split their code base in many small chunks, and for each you need to pay more and more: as the saying goes, In Matlab you cannot do shit unless you buy a licence for the Toilet Paper toolbox.

Long story short: Matlab is the Perl of academia.

Comment: Original link has more data (Score 3, Informative) 403

by orzetto (#48091253) Attached to: Fuel Efficiency Numbers Overstate MPG More For Cars With Small Engines

The study is by Emission Analytics, and here is the original link (as opposed to TFA from The Telegraph).

Note some misleading elements from TFA: they show only the three smaller classes for UK cars, seemingly indicating that small cars are the worst gas guzzlers, whereas cars with higher engine sizes are actually much worse according to the original study (see the graph). So the lesson is: still buy a small car, just not a very small one for best fuel efficiency.

Another interesting bit that is not in TFA is that the data for US cars is different: there, cars between 1 and 3 liters in volume (I assume this is the large majority of the car pool) have less than half the mileage. Also, the smallest US cars are actually the most efficient of any class, even though their efficiency is below UK average.

Comment: Re:Simple answer (Score 1) 942

by orzetto (#48036199) Attached to: David Cameron Says Brits Should Be Taught Imperial Measures

Water freezes at zero and boils at one hundred. What could be simpler?

0 is a cold winter day, and 100 is a hot summer day.

Yeah right, with your system you need to wait at least six months to calibrate a thermometer.

Besides, different places on Earth have different extreme temperatures. The same place on Earth has different extreme temperatures from year to year.

Water is a good reference because it freezes and boils at the same temperature everywhere, with minimal deviation for atmospheric pressure (that can in any case be easily compensated for), and the test can be arranged with the simplest tools; any kitchen can marshal ice and boiling water within minutes.

And in any case, the right temperature unit is the kelvin. Why is anyone even considering negative temperatures? Molecules cannot move with negative velocity!

Comment: Re:In other news... (Score 2) 216

Think of [Hambach Tagebau] as an anti-nuclear exclusion zone, like Fukushima but getting bigger instead of being cleaned up..

Quite ridiculous proposition: you cannot get cancer by entering the mine, nor is it incompatible with human life, and once depleted the mine reverts to normal soil on which you can grow crops. See the map of open-pit mines near Cologne that you mentioned, and compare the satellite images of the same area. Notice how the areas of previous development (Frechen, Zukunft-West, Bergheim) have been re-converted to agriculture.

Try doing that in Chernobyl, smartass.

Also: I know Muricans have issues with proper units of measure, but the size of the Fukushima exclusion zone is a semi-circle with a 20 km radius. That gives 3.14*20*20/2 or 625 square kilometres, 13 times the size of Garzweiler.

Comment: Re:article summary is wrong (Score 3) 51

by orzetto (#47746163) Attached to: Aussie Airlines To Allow Uninterrupted Mobile Use During Flights

That is correct, but other companies do offer mobile coverage on board: I have flown with SAS planes with on-board GSM, and whereas I did not try it (waaay too expensive rates, it's the new iteration of the airplane phone) I got signal on my device.

You still have to put the device in flight mode for take-off and landing, I assume because a few hundred mobile phones moving at several hundred km/h can overload or confuse ground stations.

WiFi is also made available only when cruising over 3000 metres, I assume because the Internet connection travels over the same data channel the GSM. You can't really play Youtube over the slow connection, but checking mail and reading newspaper is OK.

Comment: Re:Safety margins (Score 2) 299

by orzetto (#47375029) Attached to: Site of 1976 "Atomic Man" Accident To Be Cleaned

Of course you can be exposed for a short period of time to 500 times the legal concentration of most chemicals. The "legal limit" is usually designed so that regular, 8-hour daily exposure has no long-term health effects, just like the legal radiation limits. Granted, legal limits back then were less conservative.

Then of course it depends how you are exposed. ingestion is not the same as having skin contact. Methanol has a legal limit of 200 ppm, but I can put my hand in liquid methanol (by definition 1 million ppm, 5000 times the legal limit) for a short time and suffer no consequences.

Computers can figure out all kinds of problems, except the things in the world that just don't add up.