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Danijel Gorupec

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  1. If anyone interested... I went to a store and bought a torch - spent more than I expected (cca 70EUR; 75USD - one fuel bottle included). I took the most powerful torch of this type they had. It proved very capable, so maybe I could choose a cheaper one. They call the fuel the "MAPP gas". I understand this is some propylene - butane mixture. Hotter than butane, they say. So, I filled a shallow steel pot with dried crushed stones (angular rock 5-10mm), because I didn't have anything better. Placed steel pieces onto the rock and heated it with the torch. Btw, while heating, the surrounding rock also becomes red-hot (at surface). Interestingly, some gray (granite-like color) rock pieces turned white after this heat treatment. I kept the metal dark-red-hot for about one minute, and then using pliers transferred it into different pot full of wood-ash (I didn't have anything else, but I read that wood-ash is a good choice). Buried inside the ash the metal cooled slowly enough, I hope. I annealed following items: a small nail, M5 screw with a nut, a short bright-drawn steel rod, few pieces of transformer lamination (silicon steel) Results: To check if I am doing anything good, I compared the annealed nail (sample A1) with an identical non-annealed nail (sample A2). I was surprised how much easier it is to bend the annealed nail. I could bend it with fingers (the smaller bend on the A1 sample is done with fingers only; the larger bends on both samples are made with a help of a vise). Must be I am doing something right. To check dimensional stability, I annealed a screw with a nut on it (sample D). Unwisely, I choose a coated screw (a bright coating - is this nickel or what?). This coating turned green during heat treatment, so it was less easy to monitor the temperature of the sample. The nut, being smaller, become dark-red-hot much faster than the screw (obviously, there was not that much heat transfer between the nut and the screw).... After the cooling, it was equally easy to turn the nut as before annealing - so I suppose, the dimensional stability is good enough. The nut did not weld itself to the screw. The bright-drawn mild-steel bar sample (B1) - fi 8mm x 36mm - turned dark (after cooling). It looked more like a hot-drawn or hot-rolled steel. You can see it in comparison with the non-annealed sample B2. Electrical steel lamination (sample C1) has large surface - so I was afraid it might cool to fast. The sample C2 is not annealed. Not much difference between the two. Magnetic measurements: I broke the core of a small transformer (old one, low-quality one - there is no insulation between lamination layers) - I arranged it so that I can place metal samples to close magnetic circuit. Look at the picture: the sample B2 is placed into the measurement position (I would also place a weight of non-magnetic material onto the sample during actual measurement). I am pushing sine-wave current, of constant amplitude, into one coil and then measuring voltage in the other coil. The setup has very bad sensitivity because there is large magnetic reluctance in the gap between sample and transformer core (I guess, larger than the reluctance of the sample itself). Therefore I couldn't measure anything precisely. The results I obtained, are not entirely clear. With electrical steel, I measure no obvious difference. If there is any difference, the non-annealed electrical steel is better than annealed one. The non-annealed electrical steel sample gives about 5% more measured voltage than annealed sample (but measurement error might be larger than that). In addition, annealed electrical steel does not seem any easier to bend. So, no benefit from annealing electrical steel (or I don't know how to do it properly). I did however see some improvements with bright-drawn mild steel. The sample B1 produces higher measured voltage than the sample B2. The difference is larger at smaller flux densities (I don't know why - I don't think my sample reached saturation in any case). What surprised me even more is that that the difference is larger at higher frequencies (I would expect otherwise - puzzling). Excitation current 90mA, 20Hz: Sample B1 -> 7.5V; Sample B2 -> 6V (cca 25% difference in measurement) Excitation current 90mA, 80Hz: Sample B1 -> 27.5V; Sample B2 -> 20.5V (cca 34% difference in measurement)) Excitation current 300mA, 20Hz: Sample B1 -> 25.5V; Sample B2 -> 23.5V (cca 9% difference in measurement)) Excitation current 300mA, 80Hz, Sample B1 -> 90V, Sample B2 -> 77V (cca 17% difference in measurement))
  2. But isn't processed food invented to decrease food waste?
  3. Mostly for fun, I would like to try annealing some small steel pieces (say, half inch size or less). Tips? What would be most easily obtainable tools to do it? What kind of torch should be enough - or should I build a wire heater? They say: soak it at correct (red-heat?) temperature for some time (seconds, minutes?) and then slowly (how slowly?) cool it down. I guess such small peaces would cool to quickly in air? Some internet guys also say that you should not heat it too much (orange). I don't understand how can this be a problem?
  4. This points out why I think that our Universe is unlikely a simulation - my argument is similar to why the Universe is unlikely a fluctuation. A rational programmer makes a minimal simulation, not a 'maximal' one.
  5. Beautiful (expressing the g-factor as a ratio of two frequencies where frequencies can be measured very accurately). It does however seem to me that the method assumes certain confidence in equations - that is, that Larmor and cyclotron frequency formulas are both very linear in respect to B. It seems that spin angular momentum of electron is usually obtained indirectly by measuring magnetic moment and assuming that formulas are right. Still, I did find one example where spin seems to be measured more directly - wikipedia calls it Einstein-de Haas effect: https://en.wikipedia.org/wiki/Einstein–de_Haas_effect
  6. But this again measures the magnetic moment, no? I don't know how to obtain the g-factor from this data - to obtain the g-factor, shouldn't I also have a direct measurement of the angular momentum?
  7. When I ask google how is the spin angular momentum of an electron measured, it points me to the Stern-Gerlach experiment. Yet, I figure, it cannot be the only way... As I understand it, the Stern-Gerlach experiment actually measures spin magnetic moment, but I guess there is some other way to measure the spin more directly - how else would we know the 'g' factor of an electron?
  8. Hmm, there are also irrational hopes. I was always worried how could science compete with those guys that promise eternal life. Another thing is spite (or whatever you would call this: "Fu** you and your fu**ing math! Yes, I don't understand it, so what?! I'm not a lesser person! So, fu** you and your damn physics!"? )
  9. This is the part that I don't understand... If they asked me, I would tell them exactly the same. You have two sensors, so compare them. Don't make electronics bossy, but assisting.... How come they didn't think of it? I am sure they did - I bet somebody intentionally decided otherwise, and this somebody did not act as an engineer when making the decision. (That said, I think regulatory bodies share the same responsibility in this case as the Boeing.)
  10. This is what I actually wonder - does a quantity obtained that way has any known meaning? For the momentum I obtain imaginary results which suggest it does not have a meaning. For kinetic energy I obtain real result. It might have a meaning. I used this to derive something that seems to me as the 'kinetic energy density' function. But I never heard of such thing before.
  11. Must every boson mean a force? (Higgs boson too?)
  12. Difficult one, but someone might know: At what moment in history are magnitudes of units of electric field (volts per meter) and of magnetic field (tesla) adjusted just right so that we don't need ugly constants in laws like Lorentz law or Faradays law of induction? Was this also the case in dark times before SI units?
  13. It might make sense... If the fluid velocity at about 10 meters per second (22mph) and if the magnetic field is 1 tesla (quite strong) then you can have 0.1V per each centimeter of the width of the fluid flow. So I guess if the flow and the magnetic field is wide enough (20-30 centimeters or more) and if other conditions are just right, you can have some electrochemical effect. I however am not very good at chemistry and maybe someone else wants to comment how much voltage is actually needed to start electrolysis (or whatever).
  14. If the system is stationary, then no. If the alloy sheet moves relative to magnets, then still probably no. (Any voltage difference that you might achieve with this simple settings seems unlikely to reach some electrolysis threshold - although my knowledge about electrolysis is low.)
  15. I heard some amateur astronomers complaining more about bluish light than about reddish light when making observations (I guess, blue disperses more causing more light pollution). I also heard somewhere, but I cannot remember how much was this reliable, that night animals might get disturbed more by bluish light than by reddish light. Anyone heard about this? For me, the ideal street lighting would adjust its intensity during the night - decreasing its power and shifting more red after 23:00h... I guess it might also adjust to foggy conditions somehow... or even to moonlight intensity.
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