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Everything posted by Carrock

  1. Gets worse than that. Sometimes in the same system work done in e.g. charging a capacitor is regarded as positive, while work done discharging a capacitor is, er, positive. You can then say (e.g. from https://www.allaboutcircuits.com/textbook/alternating-current/chpt-6/q-and-bandwidth-resonant-circuit/ ) You can actually buy a power buildup cavity using the same general idea. From Wiki It seems like you could put in 10mW and get 1 MW out. Apparently the concept of imaginary power or reactive power (which is not available for continuous work) is not used here; 'stored power' is just power. It's rather like saying torque is energy because the units are dimensionally the same. There's a simple definition of Q to avoid this confusion* Q(omega)= omega*(maximum energy stored/power loss) *My confusion anyway - there must be some rationale to the "stored power is not energy" concept.
  2. Could the same amount of power as is in the (I presume resonant) cavity be continuously removed from it and it still be a buildup cavity? If not, some of the power is no more available than the power of a swinging pendulum as it converts kinetic energy to potential energy and back to kinetic energy again. I might try to convince a keen equestrian non-scientist that going for a walk to warm up is more eco friendly than sitting in front of a four horsepower heater. He might disregard my suggestion as horsepower is not electrical.
  3. Maybe misleading? I think you're referring to what engineers call reactive or imaginary power, which is related to stored energy and is measured in volt-amperes, not watts.
  4. Croatia went in for extreme lockdown but it also seems to be doing a lot of testing and presumably contact tracing etc. IMO the most important thing NZ and Croatia have in common is they first treated Covid as a serious problem less than a month after their index case. So many other countries seem to have decided to wait and see if the predictions by WHO etc of a major epidemic were correct before doing anything. (CharonY's comment also relevant and helpful.)
  5. I chose NZ because it was well documented (see the length of the wiki article). I don't believe any country could pretty much eliminate cv without "establish effective work procedures, organize tracking teams, educate population." No need for a major expansion of hospital capacity in NZ though. Cynically, there's one very good reason it's unlikely NZ leaders will allow a resurgence. From 13th April:
  6. Time for a mention of New Zealand and its coronavirus on this forum... After 21 deaths and with 65 still active cases it is down to level2 lockdown i.e. just maintain social distancing. The country was put into full lockdown less than a month after the index case. https://en.wikipedia.org/wiki/2020_coronavirus_pandemic_in_New_Zealand https://www.cnbc.com/2020/05/05/how-new-zealand-brought-new-coronavirus-cases-down-to-zero.html
  7. I suppose the real problem is not knowing in advance if the research is utilitarian. e.g. what practical use could anyone around 1900 expect from investigating black body radiation? My favourite example is Faraday's apocryphal responses to Gladstone's question "What use is electricity?" "What use is a new born baby?" or "I don't know, but some day you will tax it."
  8. Yep. In 1988, against orders, the captain of the USS Vincennes was in Iranian waters when an aircraft approached the vessel. The untrained crew mistook the Airbus A300 for a military aircraft. An easy mistake to make and it didn't damage his career. From https://en.wikipedia.org/wiki/William_C._Rogers_III X-post with Migl.
  9. +1 for longest link I've ever seen. I should stay in more. 😀
  10. Well.... From Wikipedia while from Azo materials
  11. From https://www.bbc.co.uk/news/science-environment-52297058 This seems to be the first evidence for neutrino CP violation. I don't know how significant the results might be. The original paper is free to read in Nature.
  12. Really? The only relevantly rated high spec starter lead-acid car battery I've seen was 40AH 160 amp crank current for 2 minutes at -20deg C i.e. about about 5AH before the battery needs to depolarise and cool; before another 2minutes of cranking. Your jump starter is 8AH; the 800 amp crank current is not needed here but makes the battery sound better. X-posted with Ghideon.
  13. Factcheck alert: From Grauniad tabloid: size matters, but not as much as content: Philippa Clarke said
  14. Diamond is best but beryllium oxide is excellent for this. It is extremely toxic but it seems it is being replaced by aluminum nitride. There are various other solutions - provide more information or look for how a problem similar to yours has been solved.
  15. This idea that e.g. some entities e.g. electrons can be/are in a superposition of states while others e.g. grains of salt can't be has been popular from time to time; sufficiently for experiment to rule it out. (I recall this but can't yet find a reference.) The basic problem is you would need some sort of physics to kick in as small QFT regime waves or whatever accrete and somehow become classical particles. https://en.wikipedia.org/wiki/Quantum_decoherence is interesting e.g.
  16. Nice if it was that unambiguous. From https://ghr.nlm.nih.gov/primer/testing/genepatents It's likely a vaccine or a weakened virus would contain some patentable DNA according to the above. Interesting question whether a COVID-19 virus mutation found in an infected human is classed as natural or a DNA sequence altered by a human and not found in nature. Monsanto has informally stated it won't sue while less than 1% of a crop is copyright Monsanto weeds... Rich pickings for lawyers. Some people know the cost of everything and the value of nothing...
  17. Somewhat too simplistic to be helpful? Perhaps I'm being a hypochondriac, but I'm rather concerned that every time I run for a bus in inclement weather I come down with all the symptoms of coronavirus.
  18. After London tapwater is bottled, the water is "premium tasting water accessible to everyone." How could premium tasting water not be worth a premium price? It's also "purified and enhanced with minerals" for designer limescale in my kettle rather than the plebeian limescale I get from tapwater. Importing a bottle from America is on my bucket list. Strangely, it's not on sale in London. [Later] Seems it's not bottled in Sidcup any more. https://en.wikipedia.org/wiki/Dasani Perhaps it should be the very last item on my bucket list.
  19. You could distill the water to make it very pure. The only downside is it doesn't taste very good. Coca-Cola used to sell excellent bottled London tapwater which tastes rather better than distilled water and was safe to drink. Fortunately all I have to do is turn on a tap... If I thought a source of water unsafe to drink without filtration, I wouldn't trust it after filtration either unless I knew exactly what was wrong with it.
  20. Not clear what the cosmic neutrino background has to do with anything in this context. In particular matter even at relativistic speed is very different from the massless CMBR. The CNB dropped out of equilibrium at about BB +1sec; it has been largely undetectable since then. Its temperature is about 1.95K, another important difference from the CMBR at 2.72K.
  21. Sounds good, but The cables themselves do not need to be brought up to non ice temperatures, particular the inner ones. If the sheaths completely surround the cables, it's impossible (without a refrigerator) to avoid the cables being brought up to non ice temperatures. (Ignoring end effects.) If heating the cables, the heat flux is independent of the heat transfer coefficient (for constant power). Whether the heat transfer coefficient is high enough, in near freezing conditions, to make the heated cable(s) hotter than they get in summer (At least 27C*) is a matter of engineering. £200 million retrofit? ......... The delayed thermal response will be more noticeable if heating e.g. the central cable but how would more heat be required without breaking energy conservation? Re part of your post I edited out without reading properly..... After the above I noticed you were implicitly comparing a sheath with heater wires (direct sheath heating) to a sheath with no heater wires (cable heating). If the sheath has good thermal conductivity no significant difference; if not, adding the wiring (but not the power) to the sheath would give similar results from the thermally conductive wires. Getting a bit picky, if heating the sheath on the outside, the wires will be somewhat hotter than the sheath; some heat will be radiated from these wires and never heat the sheath while with cable heating, all the heat is radiated from the sheath. Which is more 'efficient' isn't obvious..... * Personal experience - I am not employed by the Scottish Tourist Board.
  22. If you want symmetric heating at 100% efficiency, use the central strand or all strands.... Or ... You don't have to heat the sheaths, you can heat the cables, whichever is more convenient. If you're zapping the cables with say 10MW, all that heat leaves the cables via the sheaths. Typical advert at https://www.eheat.com/envi-high-efficiency-whole-room-120v-hardwired-electric-panel-wall-heater-2nd-generation-hw3012t/ : I'd like to see the comparison heater which produces less heat with the same input....
  23. Do the math: Pre-WW II farming was essentially "organic"-- the best yields were 50bu/ac for corn. Today, corn belt farmers get 200bu/ac-- ain't enough cow dung and Rhizobium to produce that. US population before WW II ~130M; today it's 330M....We've been swimming hard against the current all these yrs and can't stop now or we'll get swept away. To go organic on a large scale would result in a large change in the carrying capacity necessitating a commensurate die-off. ...Any volunteers? Total irrelevance. I didn't suggest going organic. You should read my posts rather than guessing. I did look at your earlier posts. All your refs to premodern ag were unsustainable e.g. Destroy the land's fertility then move on. That is not even intended to be sustainable farming. Maintaining the pasture's nitrate content etc by crop rotation or otherwise would have somewhat reduced the short term yield. If you meant 'not using inorganic N fixed by the Haber-Bosch Process produces a lower yield' you should have said that, not claimed that sustainable farming was impossible before Haber-Bosch How about the Atlantic northwest cod fishery? Cod was still cheap enough to continue fishing at 1%. Despite occasional subsequent (over)fishing there are signs cod is at last recovering. e.g.
  24. You seem to be saying technology should be used to save us, and it won't save us.... Cannibal humans couldn't be a problem for long. Trump has adopted the 'more is better' approach in some ways, such as encouraging the use of fossil fuels while building barriers to protect his golf courses from rising sea level. From https://www.usnews.com/news/world/articles/2017-12-22/trump-resort-in-ireland-will-build-seawalls-to-protect-against-climate-change And a not very high tech fix to make nuclear weapons much safer to use.... From https://www.theguardian.com/world/2020/jan/29/us-submarine-trident-nuclear-warhead-patrols-atlantic-ocean Perhaps they learned from 'Doctor Strangelove' that secret deterrence was unwise. Potential targets might also learn from 'Doctor Strangelove' and decide to add cobalt jackets to their nuclear weapons and create fail-deadly devices. Things have got more complex since 'Doctor Srangelove' and it would be unfortunate if that military officer attacked a country with fail deadly devices because the president thought they were bluffing. No doubt reviving Reagan's star wars initiative would again make the world safer.... Exactly. Never heard of crop rotation? Worked fine in Britain from the last ice age until artificial fertilisers were invented. Britain ran out of West long before America did.
  25. Can't resist.... It's arguably more significant that LIGO with VIRGO provide strong evidence that there's no such thing as gravitiferous aether.
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