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247 Beacon of Hope


About Enthalpy

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  1. Hello everyone and everybody! Sars-Cov2 allegedly propagates through air as an aerosol. I propose to flow air between many sheets that catch the droplets falling on them. A liquid wetting the sheets shall destroy the viruses and evacuate the residues as the slowly rotating sheets dive in a tank. The liquid's flamability, toxicity, odour, vapour pressure, foam... matter. Maybe some soap or nonvolatile alcohol fit. The sketched example lets air flow radially to the hollow centre where a non-displayed fan extracts it. The sheets should remove most dust before it reaches the fan, and the
  2. Fun: bone powder is sometimes included in clay to make ceramic. fr.wikipedia (in French, sorry) More generally, organic materials strengthen ceramics fired at too low temperature. Please double-check, I know zilch about pottery. ========== Hi Mark Gregson, thanks for your interest!
  3. The researchers saw fire traces on the construction in the Bruniquel cave. As cave explorers, they naturally suggest "light" as the reason to make fire, just as, as a backpacker, I naturally suggest "drinking water" as a reason for the construction. The location is near a rain zone, not where I'd put lighting fires. The fires are also about knee-high, which is a drawback as a light source. This leaves many dark zones in the cave, and it dazzles the users. Light sources sit better above our heads, as in our houses, to illuminate the ground where we walk. The planners and builder of the con
  4. Ramblings by a non-expert here. I just wonder how many Sapiens sapiens groups lived in Europe unnoticed from present science. Remains from about 300 Neanderthalensis have been found in Europe. If 1 Homo in 300 was a Sapiens sapiens, chances are fair that none has been discovered up to now. And if one is discovered some day, maybe archaeologists will re-attribute some remains that comprise a single phalanx. How many Neanderthalensis populated Europe is unknown. Experts cite figures like 70 000. If the subspecies inhabited Europe for 200ky and individuals lived for 20y as a mean, then
  5. Floats down to 2000-3000m sometimes use a "syntactic foam" made of microballoons in a polymer matrix. Microballoons are small hollow glass spheres, the polymer is often epoxy. The density varies between 400 and 600kg/m3 depending on the maximum depth. I propose to mix microballoons of very different sizes to reduce the density. Usual slurries must contain 40-50%vol liquid to flow and prevent voids, but concrete mixes particles of very different sizes to use less water+cement. Similarly here, smaller microballoons would fill much of the volume between the bigger ones so the polymer matrix
  6. A liner of corrosion-resisting metal, for instance nickel, tin... would protect lithium against water. Maybe a simple displacement reaction deposits the noble metal on lithium. The process would drop and turn the lithium part in a solution of the noble metal salt. Water won't fit, but polar solvents without O-H bonds serve in lithium batteries. "Lithium metal" batteries (search words) are a fashionable research topic. Carbonates seem less favoured, but dimethylsulfoxide (DMSO) and dimethylacetamide (DMA) are considered among many more. Both nickel chloride and lithium chloride are we
  7. Ahum. (1) Write (2) Read (3) Update. Ta and Nb are not electrodeposited from aqueous electrolytes. Alas, aqueous is the usual choice for Ni, Co, Mo, etc. W is not deposited alone, but its alloys are. Re is deposited. With close metallic atomic radius, Re could be an alternative. Mn is commonly electrodeposited.
  8. Many more elements and alloys can be deposited than I had guessed. Here are composition examples from one paper: Fe base material in that paper Ni 80% Co 6% and 95% CoNi 65%+12% V 1% from ammonium metavanadate Cr 10% from banal salts B 8% from KBH4 basic solution If I extrapolate boldly from Fe-based to Ni+Co and Ni-based alloys: Cr may be possible and it lets Ni superalloys resist corrosion better. 20% Fe is feasible and serves in some Ni superalloys. 1% V is a useful hardener in Ni too. But the hardener B uses here a basic solution uncommon wi
  9. Some prospective thoughts about electroformed hard nickel alloys and conductive hard copper alloys (for combustion chambers) there: scienceforums
  10. Some prospective thoughts about electroformed hard nickel alloys (for keys, body parts) there: scienceforums
  11. Bassoon players, and oboe players supposedly too, use a reed reamer to fit the bore on the end of the conical bocal. My bocal's end diverges by 1:50 or 1.15°. Reamers sold for that purpose (with a handle on the photo) diverge much more strongly, to fit varied bocal diameters I guess. Consequently, the reed fits only the bocal's tip and is wobbly. I bought for 22€ a used conical reamer for mechanical workshops. 1:50 is a standard, but 1.5° did the job: the difference is 50µm over 8mm fitting length, which the cane absorbs. The reed doesn't wobble any more. A handle isn't mandatory, bu
  12. I understand photovoltaics as the conversion to electricity first which is a waster of money and efficiency if heating is the goal. In that case, battery. Tesla claim >94% on a cycle and guarantee (by replacing for free) 10 years operation. But if sunlight shall heat a storage medium, I prefer this over a battery, sure. The only decision is whether the heat storage medium shall be hot, then smaller but with an oriented sunlight concentrator, or warm, then bulky but with a static collector, say on the roof's slope.
  13. Everything degrades in a laser diode, including the metal conductors and their contacts with the semiconductor, the drift of varied species (including the metal) into the semiconductor, and so on. Expect the laser diode to fail completely soon after it begins to degrade. Not every laser diode has a factor-of-four between threshold and normal operating point, but even then, if you half the current, you half the efficiency too, already through the non-lasing recombinations. Plus some other effects, like the natural emission not matching well the resonator.
  14. If the figure-of-merit really is the energy stored at identical volume, and electricity must be involved, a battery is better than heat storage. But I'd no go through electricity, as the conversion from sunlight is expensive and inefficient.
  15. I was the project leader for Sara, at the club Esieespace space.skyrocket - digitalcommons.usu.edu Microsats are defined by their mass, but this relates loosely with the capabilities of a satellite, as electronics gets smaller. You need area, which converts indirectly to mass, for instance to broadcast TV from geosynchronous orbit. Big antenna, big solar arrays for power. Unless many satellites can do the job from a low orbit, with little power and less directional antennas, this needs a big heavy satellite. Or for radar imagery. Where you want only sensors, signal conditionin
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