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Supercomputing Hardware

Three-Mile-High Supercomputer Poses Unique Challenges 80

Posted by Soulskill
from the hamsters-have-trouble-at-that-altitude dept.
Nerval's Lobster writes "Building and operating a supercomputer at more than three miles above sea level poses some unique problems, the designers of the recently installed Atacama Large Millimeter/submillimeter Array (ALMA) Correlator discovered. The ALMA computer serves as the brains behind the ALMA astronomical telescope, a partnership between Europe, North American, and South American agencies. It's the largest such project in existence. Based high in the Andes mountains in northern Chile, the telescope includes an array of 66 dish-shaped antennas in two groups. The telescope correlator's 134 million processors continually combine and compare faint celestial signals received by the antennas in the ALMA array, which are separated by up to 16 kilometers, enabling the antennas to work together as a single, enormous telescope, according to Space Daily. The extreme high altitude makes it nearly impossible to maintain on-site support staff for significant lengths of time, with ALMA reporting that human intervention will be kept to an absolute minimum. Data acquired via the array is archived at a lower-altitude support site. The altitude also limited the construction crew's ability to actually build the thing, requiring 20 weeks of human effort just to unpack and install it."
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Three-Mile-High Supercomputer Poses Unique Challenges

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  • by tibit (1762298) on Friday January 04, 2013 @01:10PM (#42477711)

    I think you misunderstand how it really works.

    Modern cars have air mass sensors -- they sense exactly how much air is coming into the engine, no matter what the pressure of the air is. This control is instantaneous, there's no adjustment period. The amount of fuel injected into the air is based only one the air mass and some slowly adapted tuning constants. The "lesser volume of air, same amount of fuel" assertion is completely untrue!

    So, you may ask, what if the relative partial pressure of oxygen in the air dropped with altitude -- that would be a problem, as the car only senses the air mass, not oxygen mass. It has to adapt the fuel amount relative to amount of air only based on the readings from the exaust oxygen sensor. This is not instantaneous -- the oxygen sensor readings are in effect low-pass filtered and affect the air-fuel mix very slowly, with time constants, I'd guess, on the order of an hour. Here's the good news: the relative partial pressure of oxygen stays pretty much constant at altitudes where there are roads. So it's not a problem.

    Your car has a problem of some sort, what you describe is not normal behavior.

    I was driving in a turbocharged car in the Alps and there were no performance problems related to altitude changes -- the absolute boost pressure was maintained by the ECU per throttle commands and load factor, as desired, delivering apparently same mass of air to the engine, at given load, as at sea level. This worked even on some of the highest paved roads out there. Even if there was no compressor in the intake, the engine would simply lose performance with altitude, but recover it without any undue effects when driving down.

If the facts don't fit the theory, change the facts. -- Albert Einstein

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