Enthalpy

Hall voltage as a consequence of the effective mass sounds reasonable. But as a cause? Do you claim that a Hall voltage is necessary to observe other consequences of the effective mass?

Plastics are usually heated during the manufacturing process, and their pigments designed to keep their colour then. Also, bending a plastic part once produces no big heat as felt by our fingers, certainly less than 100°C or 150°C at injection. So I exclude any effect of heat on the pigments when a plastic part is bent. The density of the pigments in the polymer isn't an explanation, because the polymer's density doesn't change. If bending stretches the polymer, if makes it thinner and if possible narrower too, keeping the polymer volume hence the pigment density. What I could imagine (notice the doubt) is that the polymer needs some transparency so the light can reach the pigments at depth and emerge filtered, and that strectching the polymer increases light diffusion by the polymer so much that the pigments have little chance to receive and scatter light. This is consistent with transparent plastic films that become white and opaque upon stretching. Or possibly that the rearranged polymer molecules create trap states for the electrons which disrupt the electronic equilibrium of the dye. Organic dyes are quite sensitive to lost or gained electrons. Many pH indicators depend on it.

That would be a stupid claim. It is your claim, not mine. I proposed solutions on an internet forum and they were adopted. Which is a more constructive action than denigrating other people. As everyone knows. My contribution was to tell that it didn't happen. But if Sensei doesn't believe it I shall survive it without any sequel, so I better invest my time in more useful activities.

But drilling deeper costs more and the set of wells produces heat for a limited time. Energy is very much a matter of cost, and dirt-cheap coal, gas and oil give renewables a hard time. Electricity is already transported well over 1000km with little loss. In Brazil, Canada, and soon in southern Africa. This isn't even new technology: over three decades old in Itaipú.

It's the good and only reason. But feel free to doubt it: your problem, not mine.

Interesting! Up to now, I imagined balls of 1dm3 for instance, or any shape that makes a tighter pack, hold in a net or a holed reservoir. For sure, I want the bathyscaphe to float even if some elements fail, and the failure of one element have consequences of limited size. Whether the elements' size should be 10L, 0.1L or 1mm3, I have no clear opinion. One remote lower limit is the diffusion of water through a too thin barrier. An upper limit is how much alkali and hydrogen are aceptable on the open deck of a large boat, with prepared passive and active safety. If one size makes coating easier, it's a strong argument. Fun: one bathyscaphe had spheres (hollow) of alumina as floats. Brilliant idea, as alumina has a huge resistance to compression compared with its density, and is also extremely stiff, which is all-important because spheres use to fail by buckling under 114MPa. Alas, it wasn't quite clear whether the spheres would really survive the implosion of a neighbour. This bathyscaphe never emerged from one dive, but some little parts did, so people suppose a chain reaction ended the toy's useful life. On this aspect, lithium gives confidence. So much that I feel its drawbacks would be accepted if reasonably under control.

Here are a few paths to cover the lithium with a primer, after which a barrier against water can be deposited, possibly by aqueous chemistry or electrochemistry. Many metals can be sputtered, including corrosion resistent ones, diffusion-tight, hard or malleable, and their alloys. To cover a lithium ball everywhere, I propose to lay it on three or more motorized rolls that turn it around alternating axes - remove previously any linden leaf. Vacuum O-rings on the rolls can improve the adherence if unreactive. Sets of rolls for one rotation axis can carry the ball while others sink to avoid rubbing. The screen can also carry the ball from time to time, and then one roll, or finger(s) or a shaker can rotate the ball. A magazine would process several balls after pumping the chamber once - or have an airlock rather. Metal evaporation looks less easy than sputtering, as the machines I know need the metal source below the target. A material molten below +180°C can solidify upon contact with colder lithium. This enables more varied shapes. Some metals and known alloys melt easily, here eutectic examples: 43Sn-57Bi at +138°C, 48Sn-52In at +117°C, Sn-Bi-In below. Maybe polyolefins and other polymers don't react with lithium and would then make a watertight shell, possibly without any added layer. Injection, in two steps and preferably under vacuum, would be better than deposition. Some electrolytes aren't too corrosive to lithium, for instance the ethylene and propylene glycol carbonates used in lithium batteries. A metal less soluble than lithium might perhaps deposit at the lithium surface, in a displacement reaction similar to iron that covers with copper in copper sulphate. Marc Schaefer, aka Enthalpy

Well, I'm not in the mood of going through my archives on the topic, so don't believe me if you prefer so. Let me just mention that I've spent all my time, several months long, on the accident, studying the reports from Tepco which are factual, and proposing solutions, among which several where adopted: - The concrete pump lorry to douse the spent fuel pools - The radio-controlled heavy equipment to process the site and make it accessible to humans - Several interpretations of radioactivity analyses, for instance the reported 38Cl. - and more The reports I saw from about every foreign nuclear agency and company were nonsense. Disturbing when considering that they are in charge of the reactors elsewhere, and supposed to react to such an acident.

The geothermal flux is very small. That's something the proponents of geothermal energy often forget to mention. Integrate it over Earth's surface, you get a flux smaller than Mankind's energy consumption. This isn't damning, because the heat stored in the shallow crust is huge as compared with Mankind's needs. In this sense, geothermal energy is limited, but abundent enough, and by far. Much more abundent than the coal, gas and oil equivalent for instance. Where geysers and hot sources are absent, humans can inject water and harvest hot water or vapour - the Hot Dry Rocks process, yes. It's done in the Rhine valley for instance, several Mm from the next geysers. A pipe running in the ground wouldn't receive enough heat power nor harvest heat from enough rocks. HDR injects water and lets it run freely over several hm2, preferibly between two watertight layers. After some time, the heat is depleted, and an other location must be exploited (possibly from the same location at the surface), so a set of wells doesn't provide eternal heat. While the turbines, generators, heat network, barracks... can be moved and reused if needed, the wells can't and cost in the low M€ zone, so rentability isn't guaranteed just by waiting. Corrosion and scaling of the surface equipment is a serious concern too, because the hot water was in contact with rocks. Because of that, and because ridiculously little money has been invested so far, the payoff isn't obvious, and current projects concentrate in areas where the returns are as high as possible. But this doesn't imply geysers. Since geothermal energy is available when we need it and takes little ground area, I'm enthusiastic about it - but its rentability isn't easy to predict. Hot sources in Iceland are known to be money bringers, and the country seeks to exploit them beyond its already covered needs; HDR near population centers is less obvious, but I'd like to see more efforts on it.

Possibly a matter of size of the scratches. Light reflection is affected by scratches well under 1µm width which won't be noticed as individual valleys. With our fingers, we notice rugosity of very few µm.

I've read so much nonsense from IAEA about this accident! And from Areva and most actors, by the way. Blunders as big as "the confinement has withstood it" one day after #1 exploded, as the building was open to the air and fission products spewed outside. Tepco's website is a better place.

The ancient Egyptians, and other people, were as clever as us. They accumulated invention, observation, experience and knowledge over generations. All this knowledge is lost. I feel absolutely normal that a bunch of present-day archeaologists, aided from time to time by a handful of engineers, can't recreate the technology of a culture, nor understand how a particular artfifact was made. Presently, we would be unable to reinvent the technology from the beginning of radio transmissions. Who among the archeaologists and engineers could reinvent the galena detector or the coherer and build one? By the way, we don't even have a theory for the coherer in 2017, as far as I know. Though, this technology is much nearer to us, by its use, its technology, its theory. Claiming to understand technology from such a remote past is extraordinarily presumptuous. Telling "impossible because we don't guess how they did", even more so.

Many plastics can be polished. For instance PMMA, for which it's common practice, with polishing kits available for use after glueing. Most plastics can get a very smooth surface right from injection: PMMA, PC, all materials for O-rings, epoxies (they replicate mirors), silicone (I've seen structures 4µm wide with high definition just from casting over patterned silicon), and so on. Just think of CD and DVD, whose bits are lands <1µm long of different height, obtained by injection in a mould, or lamp reflectors. Plastic polishing seems less easy than just smooth injection and than metal polishing. It is known that the finest paste or cloth deplaces metal atoms from hills to valleys. Maybe the finest paste still scratches polymers, but that's just a hypothesis.

Why do you put: "Center gear turns 2*CW for each crank revolution"? What would make it happen that way?

The Newtonian answer is that the Earth-mass object will accelerate as much as a sand grain does. But then, Earth too accelerates, and more so if the other object is more massive, so while at identical distance the object's acceleration is the same, the speed curve over time differs. The observer has a non-accelerated motion of course, or if you forgot to switch off the Sun's attraction, then at least the observer shall orbit the Sun like Earth does, and near enough and for short enough that tidal effects remain negligible, but far enough to not feel Earth's field, and so on. Or better, he compensates his observation from his own acceleration.

Has any serious information been published about the state of the cores at Fukushima? I haven't followed the situation for several years now, but during several months after the accident, Tepco had published nothing, and many other actors have run their own suppositions, supputations, hypothesis, theories that relied on nothing, nada, niente. I don't even know if the head of the vessel #3 (and of #1) is still in place. I suppose it's blown away, but Tepco has not shown the location, despite it was accessible to cameras. From the little I've read recently, Tepco doesn't know neither where the fuel is, or hasn't published it: still in the vessels or below them. I believed up to recently that the individual fuel pellets were still in the vessels, but the observation of microscopic radiocesium glass beads suggests that the fuel has reacted with concrete or soil. An ongoing imagery by muons may have told it meanwhile. I still want an explanation about what exploded in #4. Hydrogen produced locally doesn't suffice to my numerical opinion, far less so since the building was punched for several days, and a hydrogen leak from #3 to #4 even less, since the building #3 was already destroyed. (Well, I had suggested to open the buildings so the explosions were less bad, which was done at #2, and since people took heroic risks for that, I had proposed that a combat airplane opens the hole instead. If that was done at #4 and the building exploded, I understand that Tepco won't release the video, for fear of wrong interpretations ) Under such circumstances, I don't see how the IRSN - which I consider credible people - can make an explanatory video about the accident. Maybe they have better information. But maybe it's only their best guess, and then diffusing such a video is a bad idea. By the way, I heard several times "unstable" recently, a code referring to this accident, and also "hot", which tells radioactive.

I may have read somewhere - or I read it wrongly, or I misinterpretated - that the interferometer is sensitive to a tidal effect rather than directly to the contraction and expansion. Possibly something like: a portion of the light travels together with the gravitational wave and gets influenced for long, while the interference base experiences the change for a shorter time. Ahum. Take with due mistrust.

My bad. (very very bad). No, very strong accelerations around 20g have been survived, but the total speed difference was small, like 20m/s. No hope with 3km/s. I didn't consider astronauts here. That's what I supposed from your post, but how does the craft thread into the railgun? I did such things at 70km/h, it was already damn difficult. That's unclear to me. First, how to split the acceleration? Bringing the craft back for a second run demands an acceleration too. Then, the length of a coilgun depends on the initial speed if it's not zero. Distances vary as time squared at constant acceleration because of that, so accelerating in three episodes doesn't cut the individual distance by three. If you decide that some craft (not the present day ones, and not inhabited) can resist 50g=500m/s2 and you want to achieve 3200m/s, the coilgun must be 10km long.

The short answer is: no. Comparing the energy of burning H2 with O2 (it achieves about 5km/s gas speed) with escaping Uranus (it needs 21km/s) isn't a definite proof as we could burn much resource at Uranus to bring a lttle part to Earth, but economics give an obvious answer with oil at 50$/200kg while 1kg just in low-Earth orbit costing over 10,000$. Some bozos suggest again and again to mine 3He from the Moon and use it in fusion reactors, except that we don't have working fusion reactors, even with the much easier D-T reaction, nor do we even know how much 3He is available there. But it could be an attempt to synthesize tritium from 3He, as tritium serves for nuclear bombs and disappears over time. 3He looks a better precursor than lithium for that goal.

Concentrating sunlight down to Earth would produce a spot, IF we had the necessary technology, at most as hot as the solar chromosphere, that is 6000K. That wouldn't be as efficient as the lasers used to cut sheets industrially. But it would be a weapon for sure, provided that the sky is clear. A more efficient means is a power laser. You can pump some from sunlight, for instance Yag. Then you must aim at the target, which needs to compensate the atmospheric turbulence, but this is easier from the top than horizontally, and airborne power lasers do it already. Anyway, this still relies on clear weather. It also needs the satellite at the proper position when needed. I find much easier to fry an other satellite than a terrestrial target by such means. Though, in impact is even easier.

My estimates as above suggest a P80 wounded graphite vessel lighter than it is, so I've tweaked the figures. Presently, I get pressure tanks of wounded graphite 0.53* as heavy as Maraging steel. Reoptimization give initial 40bar and 20bar in the chamber of a first and escape stages. ---------- Liquid oxygen and lighter tanks let a pressure-fed first stage bring deltaV=4500m/s naturally, which neither solids nor steel tanks do well. Then, a stage with a single Vinci brings a Soyuz-class payload to Gto or Leo. The simpler make-up and the reused first stage shall make cheaper launches. An alternative pressure-fed second stage brings lighter payloads to Leo from Gnd+4000m/s for less money than the Vinci. Gto in two pressure-fed stages stays unreasonable. An optional pressure-fed third stage goes to Mars transfer, geosynchronous orbit, lunar orbit from Leo-200m/s or Leo. Foam and multilayer insulation on the oxygen ballon held by polymer belts let evaporate few kg per day, needing no active cooling. http://www.scienceforums.net/topic/60359-extruded-rocket-structure/page-2#entry761740 An alternative optional third stage pumps hydrogen and oxygen with 100kW electricity from a 50kg fuel cell. Again, multilayer insulation spares active cooling even to land on the Moon in one stage from Leo+700m/s - the payload mass still needs legs. The stage starts from Leo-500m/s for Gto, especially on top of a pressure-fed second stage. Every launcher should have a liquid oxygen escape stage available, flexible and hugely better than present solids and storables. Stages data: Propell Dry Thrust Thrott Nozzles Chamb Isp kg kg kN d (m) bar s ------------------------------------------------------- 4103 500 15 4* 1.00 60 492 3rd hydrogen 3704 500 8 0.50 4* 1.00 20 398 3rd Pmdeta <23430 2174 171 yes 1* 1.25 443 2nd Vinci 31429 2271 390 0.30 1* 1.60 30 330 2nd Pmdeta 160600 14090 3272 0.39 2* 1.65 40 302 1st Pmdeta @vac 160600 14090 2840 2* 1.65 40 262 1st Pmdeta @1at ------------------------------------------------------- My sunheat engine would bring performance to Gso and the planets here too http://www.scienceforums.net/topic/76627-solar-thermal-rocket/ In the D=5m fairing, Atlas and Delta accommodate D=4572mm payloads, as much as Ariane V does. Marc Schaefer, aka Enthalpy

Everyone understands "rest mass" but you.

I don't know a software for it, but a rather simple (though not instantenously usable) tutorial is available on the Web: "The slingshot effect", R. C. Johnson, University of Durham Energy storage: achieving 4km/s over 400m leaves you 50ms, which is comfortable for aluminium capacitors but not for supercapacitors nor batteries. Have a look at datasheets; aluminium capacitors are comfortable with 350V each. You might try a flywheel with a compulsator, too; I compare the energy density of a flywheel with a pressure vessel there http://www.scienceforums.net/topic/59338-flywheels-store-electricity-cheap-enough/#entry863014 Raising a terrestrial station by lunar slingshot, I have a bad intuition. But you could try to capture a ferry by a lunar (orbital) station and send it back to exploit the Moon's speed without depending on the angles of a slingshot. The ferry would arrive slower than the Moon (as a normal consequence of transfer orbits), the station there get energy from the speed difference, and send the ferry back with an angle less backward than it arrived. I'm not quite sure something is gained, but at least you get some freedom from less coupled speed and angle. Then, the Lunar station will get an elliptic orbit, which can't be summed again and again, but maybe you can annihilate this effect by doing the next operation one-half Lunar orbit later, when the station's apoapsis and periapsis swap their roles. Not very clear to me. Sending the ferry is one difficult task, but do you have a technologically credible script about how to catch it at 3.2km/s?

I understand up to now that the polar component of the gas' or dust's random speed gets lost by unelastic shocks. Is there an other process?

A circuit to measure 10 to 100nA leakage is easy. It takes a banal BiCmos op amp at room temperature (not in the oven) and a handful of components. Only cabling matters. Everything can be cabled on a Veroboard with a ground plane (without sockets of course). After welding, clean the circuit with trichoroethylene and don't put the fingers on the tracks; varnish isn't necessary for such currents. Weld the coax cable or a coax connector on the board. No box is necessary. Check with a scope that moving the cable leaves the output calm; polyethylene cables are better for that (the ones that melt at soldering iron's heat). The ceramic 100nF must be chosen and cabled with low inductance. The circuit's output must be clean on a scope. Decouple the supply - and I like voltage regulators near the op amp. The TLC081's input bias current makes <50pA error, the offset voltage <200pA and it's constant so the measure can zero it. The voltage and current noise of the op amp are negligible, the 10Mohm resistor contributes 0.2pA rms with the 0.01s response time here, and 30nA measured leakage contribute 0.7pA rms noise over 0.01s (without avalanche), so there's no need to integrate over hours.