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Showing content with the highest reputation on 09/30/18 in all areas

  1. Ice has more value in air conditioners than molten at a tap. It might also supply +5°C to fridges, but uneasily -10°C to freezers. The former iceberg is too big for that use, and the main cost is to cross the last km to the customer, not the Southern Ocean. de.wikipedia metric, en.wikipedia exotic Every 1000kg=1.09m3 provides 334MJ cold at 0°C, and I neglect the cold liquid's 30MJ. To provide the same, a 350% efficient air conditioner would consume 26kWh costing 5.3€ at 0.2€/kWh. A 40% efficient generator would consume 5.4kg fuel to make the 26kWh - compare with 0.12kg fuel per ton to transport the iceberg from the South. The previous iceberg arriving with 60 000 000 t would be worth 318M€ electricity at retail price and make routine transport very profitable, but it's slightly too big. A rich hot city with 1M inhabitants may have 300 000 buildings with air conditioners that provide each mean 2kWth for 8h a day, 150 days a year: the city consumes 2.6PJth/year. 7 800 000 t ice suffice and save 41M€ electricity. That's an 80m thick, 400m long and 270m wide berg yearly. Bringing net cold to a hot city is more rasonable than dumping net heat to cool the buildings. Over 40km2 at mean 250W/m2, the city receives 130PJth from the Sun over the 150 days. 2K difference? I suppose that a floating bucket wheel can exploit the iceberg anchored at the cost and coveyor belts bring the ice blocks to land storage. Unclear to me. This hardware can serve for several cities and years. Storage would be on the ground, within 2m sand between geotextiles: 1000m long, 90m high, 190m base expose 0.45km2. <1W/m/K and 25K leak <5.6MW. Over 150 days, 220 000 t melt, or 3%. This would apply also if using the iceberg as sweetwater. Every day, a house with air conditioners using mean 2kWth needs 58MJth from 173kg ice. Storage for a week means 1200kg that occupy <3m3 and are only 6.4€ worth of electricity. Carrying 14.4t in the city, a truck should make a rotation for <<77€, not easy. The storage must be accessible from the truck, not by foot over a lift. A D=1.5m H=1.7m tank insulated by 0.2m foam leaks 43W, that's 78kg lost in a week, or 7%. Bigger buildings don't ease much, since trucks have a limited size. A heat exhanger at the tank and few air pipes and fans replace the expensive air conditioner. Marc Schaefer, aka Enthalpy ========== Hi everybody, nice to see that the topic catches the imagination!
    1 point
  2. Your choice of type face, your use of brackets and the whole idea.
    1 point
  3. You mother's name is Eva?
    1 point
  4. In different languages momentum has different name, velocity has different name, energy has different name. And they won't match your "numerology" mom=eva anymore.. German momentum is "Impuls", velocity is "Geschwindigkeit". Common symbol of momentum is not Mom, but p. You altered it to match your hypothesis.
    1 point
  5. So you are asking about the shape of an alpha particle? Have you tried Google? https://www.google.co.uk/search?source=hp&ei=dACwW4mHEbDjsAeqs6uQBg&q=shape+of+alpha+particle&oq=shape+of+alpha+particle&gs_l=psy-ab.3..33i22i29i30k1l9.1106.6636.0.6978.23.17.0.0.0.0.258.2536.0j8j5.13.0....0...1c.1.64.psy-ab..10.13.2522...0j0i131k1j0i22i30k1.0.5dp2kSUXfxs
    1 point
  6. Thank you for posting this itoero. +1 I didn't see the video first time. Did you see the BBC Attenborough series Blue Planet 2? You could compare his deep sea shots with these.
    1 point
  7. Performance of what? It would vary depending on what physical activity you were doing. Lifting weights, running a marathon, having sex, and playing racquetball all require different muscles and abilities. Also, I'm not sure your question will get you any meaningful answers. Your body develops as you age, and each part for each person progresses differently. There really is no peak or prime. Your body will be better at certain activities at different times in your life.
    1 point
  8. One of the main problems with proving riemann in either way is that modern computers do not reliably compute floating point numbers to any degree of accuracy. If you wanted to really prove it you have to do the calculations by hand.
    -1 points
  9. I think she did at least as well in the softball game as he did in the hardball one. They certainly were not on the same field. She ran circles around no one, much to her credit, but he wasn't even allowed in the room at her request. He certainly evaded some of the questions, many of which were loaded with implications. You can blame him for that...or not...depending on your bias.
    -1 points
  10. study & discuss their (great?) work, energy WE=m*a*d using linear_acceleration a (=v/t, =2*((vi/t)+(d/(t*t)), =F/m) & the force(d) distance d (=va*t) of a mass m (=F/a). That (linear accelerated) force is F=m*a, where the average (accelerated) speed (velocity) va (=(vi+vf)/2), & speed (velocity, difference) is v=vf-vi, for final_speed vf, minus initial_speed vi. ((Even) although it would also be possible to use factoring (an initial unit_speed of 1 m/s), instead). The (moving) kinetic_energy is KE=m*v*va, (pronounced key), or KE=m*((v^2)/2)+v*vi) using initial_speed vi, or KE=m*((v^2)/2)-v*vf) with (respect to) final_speed vf. The potential_energy PE=m*g*h (pronounced pea, as in pee) is a mass m g accelerated (fallen, multiplied by) height h=d distance. PE=Wt*h is (the force F=) weight Wt (=m*g) multiplied by height h. (No distance fallen_able, is no potential_energy.) Equating (both energies) PE=KE (pronounced peek) m*g*h=m*v*va without mass (divided from both sides) is g*h=v*va is only linear_acceleration a*d=v*va a*d=(vf-vi)*((vi+vf)/2) of the distance d, a*d=((vf^2)-(vi^2))/2, *2 a*d*2=(vf^2)-(vi^2), (pronounced add too). That's standard mechanics. (Anything wrong there?) Swapped sides (vf^2)-(vi^2)=a*d*2, +(vi^2) (vf^2)=(vi^2)+a*d*2, ^0.5 vf=((vi^2)+a*d*2)^0.5 is the final_speed (velocity) (of linear_acceleration). The speed difference (velocity) v=vf-vi, vf=((a*d*2+(vi^2))^0.5) v=((a*d*2+(vi^2))^0.5)-vi is final_speed (velocity) vf, minus the initial_speed (velocity) vi. Momentum('s impulse) mom=m*v is mass m multiplied by (the accelerated) speed difference (velocity) v. mom=m*(((a*d*2+(vi^2))^0.5)-vi) mom=m*((a*d*2+(vi^2))^0.5)-m*vi is the final_momentum momf=m*vf (pronounced mumf, as in eating fast), minus the the initial_momentum momi=m*vi (pronounced mommy). The average momentum moma=m*va (pronounced mama) is the mass m multiplied by the average (accelerated) speed (velocity) va=(vi+va)/2. Any questions? Since KE & mom only use mass & speeds, & all energy can be equated to KE, then it seems imaginable to equate all energies into impulse(s) of mom=F*t. Mom=E/va. Mother nature (pronounce Eva (the German Eve); or else Elva from James Cameron's Avatar).
    -5 points
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