Enthalpy

I've just read that sodium and potassium can be obtained by electrolysis of the chloride dissolved in propylene carbonate. http://en.wikipedia.org/wiki/Propylene_carbonate It's a mass-produced compound (Huntsman has a doc) used in lithium batteries.

In any dispersive matter, photons have a non-zero mass. Photons interacting with an other in matter (which means this matter is nonlinear) does not mean that light is matter. For instance the spin distinguishes them. So a theory would better not predict such a thing. I have my doubts that photon interaction in matter were never observed before...

Europa is a big Jovian moon; prevalent models imagine beneath its thick ice crust a water ocean where wild scenarios put life. http://en.wikipedia.org/wiki/Jupiter http://en.wikipedia.org/wiki/Moons_of_Jupiter http://en.wikipedia.org/wiki/Europa_(moon) The Galileo probe passed by repeatedly; a special mission carrying recent instruments just to Europa has strong support. http://en.wikipedia.org/wiki/Galileo_spacecraft Europa's location (go to Jupiter, plunge to the 13739m/s circular orbit) challenges chemical rockets. A mission with fission reactor and ion thruster was abandoned. The Solar thermal engine achieves the performance naturally. A Falcon-9 shall put 3414kg at 2945m/s above Earth's gravity, using an added escape stage: http://saposjoint.net/Forum/viewtopic.php?f=66&t=2272&p=41436#p41436 after which nine D=4.572m Solar thermal engines add 5848m/s in eight days so 2132kg reach Jupiter in 33 months. Europa's orbit inclination opens two wide launch windows in 11.86 years. A bigger rocket achieves more; so do slingshots by Venus, Venus and Earth, which smarter people can evaluate. ---------- If believing my spreadsheet, a capture sequence with weak braking should pass as low as possible by the celestial body, to match the periapsis of the capture orbit and the final orbit. The benefit is real even with 400µm/s2. It needs a pass but higher than the targeted periapsis, at least when braking always against the speed; pushing forward or downward at apoapsis may change the optimum. EuropaWeakBrakeAtJupiter.zip 5.204AU to Sun let each engine consume 0.67kg/day and brake by 98mN, or together 414µm/s2 when arriving at Jupiter with 5643m/s, increasing as the craft lightens. According to my spreadsheet, they decelerate to 18535m/s at 712Mm from Jupiter's center in 97 days; 7.4 days more braking inject the craft on a 671Mm/13344Mm orbit with 120 days period. This uses 4020+306m/s. At the next periapsis, a long kick of 306+306m/s brings the period to 57 days and the apoapsis to 4287Mm. Combined, they consume 4938m/s or 699kg hydrogen, leaving 1433kg on the 671Mm/4287Mm Jupiter orbit. ---------- To target Europa and its circular 671Mm Jupiter orbit, multiple "short" kicks at periapsis cost 4934m/s or 470kg hydrogen, leaving 963kg. If pushing over 20% of the orbit's duration, it takes 390 days, not quite pleasant. Smarter people would probably brake by many successive slingshots at Europa, whose period is only 3.5512 days, or at the heavier Ganymede. This should save propellants AND time. ---------- Capture by Europa isn't obvious, because weak braking leaves a high apoapsis, but Europa's influence extends only 15Mm on the Jupiter-Europa line. The apoapsis takes time to lower, and meanwhile Europa moves much around Jupiter, so the still high apoapsis can become aligned with Jupiter, bye-bye. We can increase the engines' thrust so the apoapsis lowers quickly enough, but my estimates tell that the lower engine performance makes this option less good. The better option I've seen puts the capture apoapsis over a pole, where Jupiter won't eject the craft. This permits the polar orbit preferred for an exploration probe. The small needed North-South speed before capture, like 100m/s, results from a slightly tilted 671Mm Jupiter orbit. The approach would leave no relative East-West speed, hence waive its favourable interaction with the capture, but this looks globally favourable. EuropaWeakBrake.zip Braking 4.4 days before to 0.1day after the pass at 1.83Mm and 1821m/s injects on a 1.8Mm/29Mm polar Europa orbit. Few weeks suffice to the circular 1.8Mm (1800km) Europa polar orbit - little over Europa's 1561km radius. The sequence costs 855m/s or 64kg hydrogen, leaving 899kg. The engines weigh around 270kg; some could be jettisoned while lowering the Jupiter orbit. The tank for 2515kg hydrogen can be split; as a single D=4.1m suspended balloon, it could weigh 115kg and its surrounding truss ~120kg. ---------- 899kg, obtained from a medium launcher, is a nice mass for an orbiter with cameras and deep-view radar. Slingshots at Venus, Earth and Europa would increase that, enabling additional lander and diver. ---------- Encelade is also a Moon with an ice crust and supposedly liquid water beneath, this one at Saturn. A similar mission there looks feasible, with comparable speed requirements, but is more difficult due to the fainter Sunlight. Concentrators lighter than 1kg/m2 would help even more. Marc Schaefer, aka Enthalpy

Hello everyone! An idea of uncertain value... Full reproduction through seeds is random. For some species (cherry and others), individual trees must be carefully selected to obtain acceptable fruits, and then reproduction by seeds fails. For these, one good individual tree is reproduced identically, by grafting only its branches, or by cutting or layering to get a full tree http://en.wikipedia.org/wiki/Grafting http://en.wikipedia.org/wiki/Cutting_(plant) http://en.wikipedia.org/wiki/Layering though, the last two are impossible for some species, and grafting introduces weaknesses in the composed tree. In some cases - if any possible, which I ignore - cloning the good individual may make a complete tree when other methods can't. The economics of the process are highly doubtful in 2013... But in the future, cloning may begin with the special trees owned by producers to provide branches for grafting. Comments welcome! Opinion of more knowledgeable people is desired! Marc Schaefer, aka Enthalpy

Such vapour pressures in the cited paper make more sense to me than the ones in Wiki. Thanks!

Q1: I too believe it's not a matter of conservation of quantum numbers. Photons just don't interact among themselves in vacuum. Something like: vacuum behaves linearly for E and H. Though, in nonlinear matter, they do. Two or three photons combine to make one in optical frequency doublers and triplers. Or they can add or subtract their frequency, just like a heterodyne. Don't add and subtract quantum numbers there, because of the many electrons involved. Not very easy, because light uses to make an electric field much smaller than atom nuclei do. It needs special crystals (asymmetric ones for frequency doublers, that's uncommon) AND very intense light, which means concentrated spatially from a pulsed laser, typically Yag. If the doubler is within the cavity of the laser, better: stronger field, and the filters that pass the harmonics can feed the rejected fundamental back in the amplifier. The crystal must also be long enough to act, but the phases of the fundamental and harmonic must match over this length, which is difficult. First fun: people make nice nonlinear (quadratic, for a tripler cubic) equations to show the cos(w1*t)*cos(w2*t) term which gives cos[(w1-w2)*t] and cos[(w1+w2)*t]... and carefully forget the existence of photons for that hattrick. Shush! Second fun: if the field intensity suffices, light can ionize atoms despite the photon energy is too low. It happens with concentrated pulsed lasers and air's nitrogen. Called "multi-photon ionization". I like to imagine it that way: if light's field is smaller than the nucleus' one, light must use the atom's resonance and take time to eject an electron, while strong light does not need the resonance. Third fun: the energy of cosmic rays is allegedly limited by some mechanism where a too strong cosmic ray gives energy to a photon from the 3K background. Forgotten the details - some particle pair in between? This would indeed be an indirect photon-photon interaction, though not at technological energies. The very existence of cosmic rays must put a limit to any nonlinearity of vacuum regarding the electromagnetic field - a limit possibly much stronger than human experiments do. Q2 bis: electrons' spin interacts faintly with the EM field. It makes no electric field by itself, only a magnetic dipole, whose interaction with the nucleus' magnetic dipole is faint, making the hyperfine structure. For an isolated hydrogen atom, the interaction takes typically 10 million years http://en.wikipedia.org/wiki/21cm_radiation

For a wide wing and a small angle of attack, this coefficient departs little from its theoretical value as theorized by Joukowski, that is pi*angle (in radian, measured from zero lift angle). If the wing isn't much wider than long, the coefficient drops slowly. Most importantly, there is a maximum value; if the angle still increases, lift drops brutally. The maximum value depends much on the profile design and on added gear, typically landing flaps. Slightly less than 1 for wing profiles optimized for other uses, it reaches 1.3 and little more for thick asymmetric profiles. Beware that many landing flaps also increase the lifting area a lot, but the lift coefficient uses to still multiply the area of the wing with the flaps retracted, in which case the lift coefficient can exceed 1.3 a lot. Beware also that in some books or languages, the lift coefficient does not include the angle of attack.

Centrifugal, distance squared, mass of the planet times the mass of the sun times G...

One has to distinguish between - a pressure and velocity wave within water - a wave at the surface of water Waves at a free surface are quite a bit more complicated; for instance, they cannot depend only on t and x; the formula you give, with t, x, z, h, corresponds to them. In the free-surface case even more than usually, finding a solution (here for the velocity potential) results from no general method. It takes one genius in history to find it from the differential equation, and then people learn it from course or encyclopaediae. http://en.wikipedia.org/wiki/Airy_wave_theory What students learn is how to reproduce the derivation of the solution, how to prove it fits the equation... but not how to find (invent, I'd say) the solution of an even so little different problem, because what professors and book teach are methods, but there is no method for inventing. You know, Euler gave the general method to compute beam buckling, but 1.5 century later all books give still the same five examples as he did... Green and Fourier found general methods to solve the diffusion equation, but books give still the solutions to the same problems the ancestors found.

Simple answer: no. Though, a few physicists try to detect a super-tiny effect in a mega-magnetic field. To my knowledge, no effect seen at all. If light propagates in matter, the picture changes. Magnetic or electric fields can hae a strong influence on some material, including their optical properties. Banal observation at LCD screens. Some Solar sails want to use a magnetic field, by a current loop that materializes only the edge of a disk hence is light. Though, these sails try only to catch the charged particles of the Solar wind, which provide a pressure 2 or 3 magnitudes fainter than the already tiny pressure by Sunlight. Is that any less difficult?

Do you quench in water after induction heating? I thought the surface was quenched by the underlying material, which stays cold with induction heating.

Metals will heat very little (except by sparks...) and resonance will worsen sparks, which appear so readily in a microwave oven. Also, all these ovens have between the cavity and the power source an absorber for the reflected wave, which may prevent efficient resonance of the target. Metals with bigger losses at microwaves: - Allied titanium, for the higher resistivity... small improvement - Magnetic material, to worsen the skin effect. Especially nickel layer, iron... Can be very thin. Or cover the metal with a lossy material, say a proper ceramic, or if the temperature allows, a graphite-loaded polymer like silicone or polyimide.

The static stack can use liquids as the electrocaloric material if useful. For instance, the liquid can impregnate a possibly thin insulating fabric or felt that holds the electrodes apart and the liquid in place; the electrodes can still be printed on a film, or be a conductive sheet, or be a possibly thin fabric or felt of conductive wires - easier to connect. Propylene carbonate and similar seem to conduce too much for this use, but other liquids may fit. Oligomers of vinyl difluoride, if isotactic? Cetones, ethers? Oligomers of propylene-1,3-diol, especially methyl terminated? I imagine a stiff molecule whose dipolar moment orientation in the working electric field makes about kT is more efficient. This needs more alkylene carbonates' 5 Debye, which brings some 0.03*kT. Marc Schaefer, aka Enthalpy

Do you belong to the 21st century? We have images of atoms since the tunnel effect microscope, around 1985. Meanwhile, even scanning electron microscopes show atoms. Very much is known about atoms. Considerable progress has been made since Volta.

Optical computing was a fashionable research topic two decades ago. Seems out of fashion now. What computers absolutely need right now are better INTERCONNECTS, not computing elements and gates. I don't care that little bit whether electric, optic, magnetosomething or magic, but we NEED to transfer massive throughputs with minimum delay through one chip - between many chips wouldn't be bad neither. As processes shrink, gates are faster and numerous, but interconnects get slower for the same distance (more latency) and their combined throughput (with more lines per chip) stays constant. This alone explains why clock speeds stay at 3GHz since the pentium 4, and why Cpu make no progress since the Core 2. Processing power would already be available in huge amounts with present processes; graphics chips exploit it less badly than Cpu. Better gates with the same interconnects bring zero, nothing. Better interconnects with present plain standard silicon MOS would bring everything. ----- If abandoning in-chip interconnects with small lantency, you could develop more flexible inter-chip interconnections that offer full-matrix connectivity. Check before whether it's done; it is easy with serial links. http://saposjoint.net/Forum/viewtopic.php?f=66&t=2454#p28231 (on Wed Aug 11, 2010) without optical connections nor electron beams, just with silicon gates. Any route from 1000+ to 1000+ nodes allowed by one chip (put more a needed), no interlock, no limitation by the network architecture like a hypercube or hypertorus, more cumulated throughput. But the usual latency of a serial communication.

No effect on quenching efficiency at all, with 1000ppm. Scale: I'd say little difference. Seawater makes a big difference, with 35,000ppm.

http://en.wikipedia.org/wiki/Tartaric_acid they know dextro, levo and meso forms, plus mixes and... is that the proper sense? http://en.wikipedia.org/wiki/Anticaking_agent Ammonium sodium tartrate is one of the few compounds that separate into dextro and levo forms when crystallizing. I suppose tartaric acid is then used to separate L and R forms of synthesized amines. The tratrate is one cadidate for my suggested Czochralski separation: http://www.chemicalforums.com/index.php?topic=65386.0

Caffeine can be isolated, possibly synthesized. Some cheap supermarket drugs contain it, associated with vitamin A for instance. So it looks pretty cheap to obtain pure. As its vapour pressure seems to suffice, sniffing it should be possible.

"Complementary variables are Fourier transforms of each other" Always? p and x yes, E and t yes... but the total angular momentum and its component along one axis?

Electricity being moving electrons: in the past, the question was so little obvious that the ancestors didn't know the answer and chose the wrong sign convention for electric charges, alas - we must presently live with negative electrons. Their first hint was when they observed charges transported through vacuum, and these were only negative. Select only protons for a beam: particles feel a lateral force when moving in a magnetic field, to which light particles respond much and heavy ones little. Pass the particles through a first hole, deviate them with a magnetic field, and a second hole lets only pass those with the desired mass. Starting from normal matter, one won't get positrons or neutrons by chance - only electrons and ions, easily distinguished by their charge - and +. Then, ions (= atoms with fewer electrons) can be separated by the magnetic field, which is then called a "mass spectrograph". If the initial matter is normal hydrogen, one gets as ions: protons, a few deuterons, and more ions resulting from impure hydrogen and pollution by the apparatus. Most ions are thus protons. Neutrons can't be accelerated nor channeled by a collider, because they lack the electric charge required to accelerate them and deviate them. Though, collisions are possible if the accelerator uses heavier ions that contains said neutrons and protons, whose charge makes them suitable. The LHC does it with lead ions, when it doesn't collide just protons.

Known processes to stack ceramic and metal layers produce capacitors that are cheap if small. Here's instead a process to stack metallized polymer sheets. The sheets are stacked in several iterations, as each may be 10µm thin or less but the module several mm thick (no scale at all in the sketches!). Four electrodes make one period on the sketches, and just one period makes the smallest stack, but these figures can vary. The electrodes are patterned, by evaporation and deposition through a stencil, or by etching. This provides insulation creep distances and brings contacts to the sides. Stacked electrodes come from different long coils, so their positions must be adjusted by the film's tension - or pattern the electrodes at the last moment, between uncoiling and stacking. On the sketches, the sheet is folded to make a selective contact among all electrodes driven simultaneously, improved by the deposition of thicker metal once the modules are stacked. Offsetting the folds linders their overthickness; lamination thereafter seems necessary. A good alternative would offset slightly the consecutive sheets and let the metal layers reach the edges where the deposition od thicker metal finally contacts them. Electric fields are strong, suggesting to impregnate the sheets before stacking, and even to do it in vacuum. Could the film be folded as a zigzag, so a few rolls make many plies in the stack? Probably. Then I'd interleave several films in varied directions, like 0° 90° or 0° 60° 120°, to ease the folding thickness and offer more access locations for the electrodes. The films can be narrower at the electrodes. If the cooling modules (or heat pumps) can be slightly cylindrical, an interesting alternative lets make all successive sheets by winding from a single coil - with electrodes either adequately patterned to compensate by their length the evolving coil radius, or by patterning the electrodes between uncoiling the sheet and winding the stack. Marc Schaefer, aka Enthalpy

The frequency is kept everywhere as soon as there is no relative motion. The wavelength relates to the frequency, up to a property of the local material called refractive index. So if the light propagated in the fibre comes from air and goes to air, the same frequency means the same wavelength - though the wave is shorter in between, in the fibre's silica. If light comes from GaInAs and goes to Si, the wavelegnth will differ a bit between both semiconductors. If you mean: keep the same wavelength in the fibre as at the transmitter... - Yes if the transmitter is made of the same material! Especially, some amplifiers are just Er-doped fibres that lase. - Same wavelength as in air, not with a usual fibre. The index must be bigger than the surroundings in order to channel light. - More recently, fibres are made of vacuum, with a cladding of so-called "metamaterial" whose index is <1 over a narrow frequency band. These would allow a fast propagation with a wavelength similar to air. Probably what "standard fiber optic cable" excludes. By the way, laser light is the easy one to inject in a fibre. Incoherent light is difficult to focus to a small area, which needs a steep convergence angle that a fibre doesn't channel.

Mamma mia! Conversion to 2's complement means: do nothing. Except if a number was in 1's complement exceptionally, but you don't need microcode for that.

Radiation pressure gets really negligible, even on the huge area of a Solar sail, well before midway to the next star. They're excellent candidates to Venus, Mercury, Sun-near missions, to the asteroids, possibly up to Saturn but that's harsh. Any mission beyond involves accelerating close to the Sun and sailing thereafter on the acquired velocity. Sun-escape missions with Solar sails are perfectly possible, sensible and advantageous. It's easier than stopping at an outer planet. All scenarios involve to pass close to the Sun and accelerate there. The most advanced scenarios first go farther from the Sun, plunge from there in a close Sun pass, to get the maximum kick. Several true Solar sails have already worked. They were all disapppointingly small: a few dam2, while we need a few hm2 to get good performance just for a 100kg probe. 1t would rather mean 1km2, especially if a sail shall outperform my Solar thermal engine. I'm not quite sure unfolding was tested on Earth... Even for the small sails up to now, I read mostly about testing in orbit. My objective is to test the few hm2 on Earth. I'll put more thoughts when I find time. Beyond this area, testing on Earth becomes more difficult.

It's called biodiesel or diester, under which names you find much information. "Natural fatty acid" is slightly broader and would include animal fats as the acid source. The most common must be methyl palmitate, obtained from palm oil. The simple transformation keeps three acids and replace a glycerine by three methanols - one viscous oil becomes three molecules of lighter ester.