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sethoflagos last won the day on April 2

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About sethoflagos

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  • Birthday 10/10/1958

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  • Location
    Lagos, Nigeria
  • Interests
    Classical Music, Natural Science, Food Preservation, Games Theory, Laughing, Ladies, the Geological Record, Deep Time, Beer and species Rhododendron.
  • College Major/Degree
    Chemical Engineering - UMIST
  • Favorite Area of Science
  • Biography
    As far as I remember, I got very drunk in all sorts of different places.
  • Occupation
    Government Advisor

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  1. Nearly. But it isn't the properties of the medium that are changing: it is whether or not the medium is flowing away from you toward the trains, which would delay your detection of the whistles; or flowing toward you from the trains, which would advance the detection. If you had no information on airspeed, say for instance you were observing via a remote video camera and microphone, your measurements of the (apparent) speed of sound would vary according to wind speed and direction wouldn't they? This is an example of Galilean non-invariance. Now substitute 'speed of light' &am
  2. In what circumstance would a medium be not at rest with respect to itself? Perhaps you intended "... at rest with respect to the observer", ie. a restatement of our 'still air' constraint. Could another restatement of this constraint be that observer and medium must be in the same Galilean reference frame? If so, then if the constraint was a necessary precondition, wouldn't this imply that the apparent speed of sound was not invariant under a Galilean transformation? I stress the word 'apparent' to distinguish between transmission over a measured distance in a measured tim
  3. Meteorites survive passage through the atmosphere, so perhaps you intend 'audible fireballs'. Even so, these propagate, initially at least, as supersonic bow shocks (sudden pressure discontinuities) rather than sound waves - at velocities dependent on their initial trajectories, and independent (for a while at least) of atmospheric properties. If one bolide were travelling towards the observer, and one away, they would be experienced as two blast wave fronts, the first perhaps considerably more powerful than the second. 'Pitch' is meaningless here. There may be some reflected afte
  4. 'Robotic skin' is a highly active area of current research, and your OP seems to require a relatively low resolution, planar version of the same thing. I'm puzzled why you pick impedance as the sensed property for this. Most work in this field has been focused on traditional resistance strain gauges, piezoresistance, and capacitance methods though Fibre Bragg Gratings (FBGs) seem to have received a lot of attention recently. The EU Roboskin Project is funded to the tune of about 5 million Euros: details at https://cordis.europa.eu/project/id/231500
  5. I clearly remember my grandmother starting the fire like that as the family gathered for christmas dinner. The sudden updraught caught her pet budgie by surprise and... it didn't end well.
  6. Natural draught is used extensively as a power source, but not in an obvious way. It doesn't provide enough power to pull combustion air through a commercial power station, but it contributes significantly in reducing the power requirement of the forced- & induced-draught fans. Similarly, natural draught cooling towers (and domestic coal fires for those old enough to remember them) don't need forced ventilation in order to maintain air flow.
  7. Would I be reasonably correct in thinking that the product of mean particle momentum and mean particle separation would need to be oto Planck's constant?
  8. That's actually quite interesting. Thank you +1 Maybe pointing to the rarest naturally occurring element in the universe is stretching the limits of "commercially available" a tad though.
  9. Very few materials we commonly encounter have a structure that is stable under a pressure of 1 GPa. Most, much less. We do not have presses capable of exceeding 100GPa by a huge amount, because we do not have the commercially available materials to construct such presses. Give or take the odd colliding celestial body. And they are a one shot deal.
  10. Sorry, but I don't buy this explanation. Take this example from a previous post: If there was "no heat whatsoever" flowing into your cold sink, that would imply that the thermal efficiency of your machine was 100% (it can't be, but we'll let that pass for now). In other words, you were extracting every last milliJoule of work allowed by the 2nd Law of Thermodynamics. However, if your heat engine did indeed "utilize ALL the heat fed into it" from say 1 kg of hot cocoa, then you would not only have your 100% thermal efficiency, but you would also have attained 100% Carnot eff
  11. You're confusing Carnot efficiency, 1 - TC/TH ... with thermal efficiency, 1 - QC/QH It is entirely consistent with both classical thermodynamic theory, and centuries of detailed empirical observation by the most gifted of experimentalists, for a machine to have a low Carnot efficiency (the fraction of energy in an input stream that is available for conversion to work) and a high thermal efficiency (the fraction of that available work you manage to convert to actual work) The following demonstrates most clearly that you are totally unaware of this distinction: With an in
  12. Please give me a credible mechanism for the creation of a slush (suspension of ice particles in water) in the system I have described. I currently regard the idea as a deus ex machina, but would be delighted to be shown otherwise.
  13. Average low night temperatures on mars are below 200 K throughout the year. There is next to no atmospheric blanketing and the (blackened) pipes are shielded from the ground by mirror finish parabolic troughs. They are in thermal communication with nothing but the empty vacuum of space. You may have noticed that I switched from an initial single 48" ND pipe to multiple 8" ND pipes. This was specifically directed at providing the necessary 'A' in sigma.A.T^4 to meet the night side heat shedding load. You may also have noticed that I've switched to extracting the 18 m^3/s via multiple
  14. ... So... Well you expressed disbelief that the interface pressures could be controlled by the operator. My second to last post sort of covered that, but maybe I could flesh out some details for you. It is relatively easy to set the pressure of a ringmain. A very simple example would be to fit it with an open header tank set at the appropriate elevation and sized to accommodate any expansion/contraction or temporary fluctuations in inventory. Something a little more sophisticated would be called for here. Maybe an underground reservoir with a substantial gas blanket to absorb the flu
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