Enthalpy

Would you have a link or a more complete name? I couldn't find LPS because three letters aren't specific enough for a search.

I can't make a sense from the scientific-looking vocabulary dumped here, sorry. An anti-proton is easily distinguished from a proton because it's a different particle. "Pass through each other" looks like an attempt to use at particle scale the representations of macroscopic scale.

The atom is full. Its electrons fill it completely. The "empty atom" results from misconceptions. Electrons are as much point-like as you try to measure them. But in an atom, electrons have the size of the atom. Orbitals are not circles around the nucleus. They are solid and extend over much volume. By the way, the S orbitals have the maximum probability density right at the nucleus, so these electrons are not "away".

As wrote JC but without his delicate style: forget it. Thunderbolts take a completely negligible portion of a storm's energy. Mixing the Ocean to linger its surface temperature, or evaporating its surface in advance, looks less unfeasible.

If you have cylindrical walls at r1 and r2 rotating at speed W it's easy. If not, it's generally unfeasible.

There is more than correlation in entanglement, and QM gets disturbing here. Entangled particles prove that mixed states are not just a definite state that we don't know precisely. Photons can have linear (say, vertical or horizontal) or circular (right or left) polarization or any elliptic combination. All combinations can be written as the sum of two linear or two circular polarizations, for instance pure circular is vertical+horizontal with a 90° phase shift. Linear is a good base, circular an other, equally good. You can observe the perfect correlation between two entangled photons using linearly polarized detectors. BUT with the same source of photons, you can observe the perfect correlation between two entangled photons using circularly polarized detectors. Here QM is radically different (and disturbing), because the photon pair cannot decide when it's emitted to be vertical, horizontal or anything else: this would explain the correlation with linear detectors, but not with circular detectors. (Nor could they decide to be right or left). That is, vertical photons would be seen by circular detectors, but equally as right or as left photons, and with no correlation between the detectors. Experiments contradict that.

The latent heat of melting-freezing makes a lighter accumulator than the sensible heat of a liquid or solid. Here a nice document: http://www.seas.upen...iewexample2.pdf The usual paraffins, well refined, bring some 240kJ/kg with finely staged melting points. 175kg, instead of 500kg brine, store the 42MJ that bring 200kg buoyancy adjustment. Polyols and salts resist fire better; the best ones can weigh slightly less than paraffins. Alloys are heavier. The accumulator-exchanger must have stages of successive temperatures. To hold the liquid, one might encapsulate the material when solid in a thin layer of catalytic nickel, with a bubble or foam inside to allow for expansion. Many pebbles, wires... would give the heat exchange area. A classical liquid/gas heat exchanger fits as well. Marc Schaefer, aka Enthalpy

Hello everybody! Several methods are used to control an aerostat's lift force: vary the ballast, leave gas escape, heat air, use propellers... Not always satisfactory, for instance if an airship isto transport cargo or serve as a crane. In 1982 I used a water solution of ammonia in a rigid bottle and a gas pump to extract ammonia from the solution in a separate envelope. That way, I could extract some volume without a big pressure change nor the associated power and energy need. But toxic, sure. Following here is a different idea - perhaps new, I didn't check. ==================================== I propose to control the aerostat's buoyancy through the temperature of a gas, but with little heat expense and a short reaction time, by using a heat storer-exchanger about as a Stirling engine does. Such a storer-exchanger has a a warm and a cold side and lets the fluid flow from cold to warm to warm it, and in the reverse direction to cool it. - Heat removed from the fluid gets back in the storer-exchanger for re-use; - The fluid has everywhere nearly the temperature of the storer-exchanger, avoiding losses; - The same fluid gives and receives heat at different times. No need to withstand pressure nor transmit heat through a wall. The exchange surface is easily made huge. By moving a gas through a storer-exchanger in one direction or the other, its temperature and volume hence buoyancy is controlled quickly and reversibly: very nice for the aerostat. Heat is lost only through technological imperfections or if the aerostat delivers cargo higher than it picked it. ----- The gas can be helium (needs less heat for being monoatomic), air, or an other, even heavier than air. The insulating envelope, the storer-exchanger... can be outside or within the aerostat's main hull, and might even be the main hull. If within the main hull, heat leaks through the insulating envelope don't reduce immediately the total buoyancy - but they affect the buoyancy's control range. On the sketch, the storer-exchanger itself moves in a stiff insulating envelope, but this envelope could be deformable, or a separate piston could move the gas - combine several methods if you like worries. Smooth operation, including stability, wants to keep the warm gas at nearly the warmer temperature of the storer-exchanger. The gas can be blown, or rely on natural convection, for instance if it's above the storer-exchanger. A very intimate contact between the gas and the storer-exchanger is compatible with a small pressure drop. It needs finely divided gas channels, suggesting a clean gas. Many narrow and short capillaries, fed in parallel by arteries, arterioles, veinules and veins like for blood, possibly in different directions, make a superior organisation. One example is a porous ceramic with in and out channels on a chessboard pattern, but stapled sheet would achieve it too, as would loose powder, or a metal or ceramic mesh, or thin nickel that separates the gas from a heat storing liquid - and more possibilities. ----- For the storer-exchanger, water possibly mixed with antifreeze, brine (of LiF better than NaCl?), and other materials like liquid or solid paraffins (polyolefins) have a big heat capacity but a limited temperature range - as may the insulating envelope. A liquid, or solid-liquid transitions preferably at successive temperatures, should be immobilized to preserve a warm and a cold side. Take a 2kN (200kg) buoyancy control. 625m3 of helium getting 80K would need ~500kg of brine to lose 20K. A bigger relative temperature variation in the storer-exchanger is acceptable if: - Gas exiting it doesn't mix, so gas' temperature corresponds to the storer-exchanger when it enters again; - Sections of the storer-exchanger are switched so its extreme temperatures correspond to the gas at both sides; or use solid-liquid transitions, with proper regulation. Metal, ceramic... enable a hotter storer-exchanger but offer only some 800W/kg/K. Li, Be, B bring more but have drawbacks. The storer-exchanger can be heated before flight, possibly outside the main envelope, by a combustion, electricity, Sunlight... and be further heated or not during flight. ----- A stiff insulating envelope can consist of foam, or a possibly multilayer honeycomb with organic spacer... They can be filled with a better insulator than helium, like argon or vacuum. Aramide, polyimide have good heat resistance - and a ceramic foam would be welcome. If flexible, the insulating envelope might use a foam as well, or mesh between several films... Roll it like a toothpaste tube? If surrounding the warmer gas mainly by the storer-exchanger, for instance as two big pistons in a short cylinder, then leaks decrease. Marc Schaefer, aka Enthalpy

TiB2 is a strong candidate as well. From Nist: 1800MPa compressive strength @RT, creep data begins with 5*10-12/s @1500°C and flexural 100MPa, or 0.1% in 6 years.

What do you call a mystery? People debated whether who had interpreted it properly, someone made an experiment that was conclusive, case closed. We're talking about basic phenomena here, which probably won't be "explained" through something else like the datestamp by the Post office or the age of the tree. At that level, we can check if our description fits what happens, or which description is best. And: a "purpose"? Does our world have a purpose? This isn't the scope of successful science.

Nuclei masses are measured with great precision in spectrometers. With an electric and a magnetic field, the deflection tells the mass with many places accuracy. Because energy in a nucleus is very concentrated, the variation of mass is significant and spectrometers observe it accurately. As a side remark, energy is always mass. Air blown by wind is heavier, water loses mass as it produces electricity in the dam, a stone is heavier hot than cold... But this variation is tiny, generally impossible to measure, and certainly the faint variation is not convenient for energy computations. Mass default is convenient, and commonly used, only for nuclear reactions like radioactivity.

2) The experiment war really done. By Alain Aspect, at Orsay University, less than three decades ago. The observation is that not only do the states of both particles match: they do it so quickly that even light would not have enough time to propagate from one detector to the other to tell the other detector what it shall do. This was a serious interrogation (Einstein, Podolsky and Rosen called it a "paradox" then), because Relativity supposes that no information can propagate faster than light does. If we could exchange information without delay, compare clocks and rulers instantly, then Relativity couldn't claim "A sees B's clock go slower, and B sees A's clock go slower as well, and this is normal". This situation would become imposible, and Relativity would collapse. The (most common) interpretation of Aspect's observations (repeated many times meanwhile) is that the entangled pair of particles "decides" in which state it is. The rest of the world, and notably the observers, can't decide the state of a detected particle. So entangled particles are not a means to transmit information, hence their too fast behaviour doesn't ruin Relativity.

Plansee's web site doesn't respond, I hope the company is alive and well. Anyway, I had downloaded the doc for my needs. I wouldn't like to upload it here because it's several MB each, but: - Among their Mo alloys, TZM is meant against creeping. At +1100°C the tensile creep resistance is 350 to 400MPa. At 1450°C it's 35MPa for 1% in 100h, 17MPa for 1% in 1000h (and the MLR alloy is better than TZM at 1450°C below 24MPa). - Plansee gives no creep data for Nb nor Ta alloys. Ta's tensile strength is around 120MPa @1200°C, Nb is worse, and creep stress is always much lower. - Plansee gives no creep data for W alloys. Yield and ultimate strength is around 200MPa @1200°C for sheet, rather 280MPa for rods. As it looks, only Mo alloys were developed for serious structural uses. Nasa's technical note TN D-3222 (Web) tells creep behaviour of Nb and Ta, where the alloy T-222 outperforms all others. At 1204°C (2200F) and 55MPa (8000psi) it creeps very little, like 0.5% after 8000h. That's not a different world from TZM. ====================== You get ceramic properties there http://www.ceramics....ry/advmatdb.htm They give a tensile strength, which could be as well a creep strength for ceramics. Alumina (which one?) 140MPa @1200°C, sintered SiC (good in reducing atmosphere) 250MPa @1200°C. My other docs tell a "maximum operation temperature" (at zero stress?) here in reducing atmosphere: From Ceramtec: Al2O3 1000 to 1500°C depending on the mixture and processing, ZrO2 less, SiC 1350 to 1800°C. From CTTC: ZrO2/Y2O3 1500°C, Al2O3 1700°C, MgO 2200°C (must be structurally weak), SiC 1500°C in air http://www.goodfellow.com/ gives still other data. I didn't check Matweb, often a good info source. Pretty much inconsistent, as expected from ceramic, so you'd have to check with individual suppliers. SiC is promising. Ceramic may well be cheaper and more common than molybdenum alloys, and SiC react less with carbonated compounds. My doc is in varied exotic languages, so you'd better search the Web.

What kind of pressure? "Pressing a carbon material" sounds like sintering, and then it looks bad! For sure, all iron, nickel and cobalt-based superalloys are impossible. Among alloys, you might look at molybdenum, niobium, tantalum, and if needed tungsten. You have to check in detail what alloy fits what temperature and stress for how long ("creep"). One company in Austria delivers Mo alloys, of which one alloy might fit 1200°C at limited stress. I have no opinion about reactions with your carbon-based material; the use is difficult enough that you have to split the design constraints and rely on a coating for that. Also beware many refractory alloys gall. http://www.plansee.com/ I hope they still exist Ceramic looks better but they're generally brittle. Alumina, zirconia are candidates; some must be stabilized (with yttria for instance) to withstand thermal cycles.

Hi Emanuel, welcome here! I agree approximately with your computation of Case 1... - 660W sink for useful 174W explain why Peltier elements fit this purpose badly. They serve for sensitive cameras, where vibrations aren't acceptable. Can you get the cold machine from an old fridge? - This design is marginal! 2K could be -2K and anyway, they are too little for the sink. Alone the contacts between the metal and the Peltier will drop more. Accept more than 10min, or put more Peltier, to get margins... - Where does the 13.1A*8.8V+50W come from? The doc of your Peltier element probably gives a voltage that depends on the temperature difference, and this should integrate the heat soaked from the cold face. Check if it gives a resistance as well. - Heat exchange within the liquid is bad unless you mix it. Especially if you cool the bottom, you stop convection. Difficult to compute, but much more important than the metal wall. In case 2, is the 0.1mm wall thickness corrrect? Anyway, heat exchange within the liquid, not wall thickness, will limit the cooling. This is a seriously difficult topic, and alas, a necessary one. Either you experiment, or you take a hard time learning it. The only book I know is in French: "Introduction aux transferts thermiques" by Sacadura, and it's nothing simple. In fact, it's fluid mechanics, but worse. Expect weeks of headaches if you're a physics-oriented engineer, before you give up learning properly and just suppose to understand how to exploit the diagrams. The experimental option means: make internal corrugation in your tube, for instance by drilling many narrow holes in a piece of copper or aluminium as a replacement for the tube; observe and improve if needed. This shape allows you to put more Peltier elements if needed. Remember the heat conductivity of an alloy (especialy stainless steel) is much lower than the pure base element, and remember that corrosion depends on the alloy and most aluminium alloys are very bad against corrosion. As for the size of your cold sink: the heat power you want to remove is similar to a house fridge, and these accept a temperature drop much bigger than 2K, so have a look a their size! I regret to tell the pictures are far off. A fan can improve that.

According to my superficial understanding: - Usual production taps oil and gas from a reservoir, which has accumulated them as they migrated from their initial rock, because the reservoir is tight. - The initial rock has no tight cap. It keeps the oil and gas because the rock has a sufficiently low permeability. So when production fractures the initial rock to make hydrocarbons mobile, these aren't confined in a reservoir nor exclusively to the drilling well. They spread all around. There is more. A single reservoir gives much hydrocarbons from a single well, as the reservoir is porous and extends to many kilometres. Shale oil or gas needs many holes because each hole gives access only to the extension of the fracturation. As boring a hole is traditionally a polluting operation, you get more dirt if producing the same amount of hydrocarbon from shale oil or gas. Anyway, companies involved in these trials have lost heavy amounts of money, so the debate may soon be over.

For such a general question, I suggest to have a look at Wiki first.

Referring more to the beginning of this thread... The quantity is conserved in a atom's electron absorbing a photon is energy, not wavelength. Both are linked in a way for photon, but the relation differs for electrons. Electrons in an atom are trapped, so they don't propagate, and don't have a usual wavelength. One does define a wavenumber or vector but it's a mathematical imaginary number, telling that the probability of observing the electron far from the nucleus vanishes quickly - trapped. The equivalent of the wavelength then is simply the radius of the orbital - I like to say "the radius of the electron" instead of "its orbital". You can call it properly a fading wave, though this term is more common with photons than electrons, and photons are then called "virtual". It boils down to cos(x) versus exp(-x). By telling "the electron is a wave", QM explains this radius, which is the reason why matter has a volume. What happens "when a photon is absorbed" isn't clear tome, but what happens when the atom is illuminated was observed at a Munich university. The probability of observing the electron in the excited states raises over time just as theory predicts, with a sin2(t) that is faster when the field is stronger. After some time, the probability of the excited state decreases again according to sin2(t), and this is called "stimulated emission". If you manage to have >50% atoms in the excited state, which isn't very natural and need "pumping", then the incoming light de-excites more atoms than it excites, and you can harvest a net energy ; this is called the Laser effect. QM describes this with more details. Stationary states are the ones that don't evolve over time, where nothing happens, but are not the only ones. If these states have energies separated enough then temperature doesn't suffice to put the particles in excited states. Provided efficient mechanisms exist for de-excitation (it can take very long for hydrogen atoms emitting the 21cm radio wave, or months for some excited nuclei) then particles group to the lowest available stationary state - knowing that at most two fermions like electrons can share one state. This is the usual state of atoms and molecules. Now if the atoms is illuminated at the proper frequency, some electron(s) can have a state which isn't stationary any more - it evolves. Though, mathematics tell that the wave (the electron) is a weighted sum of stationary states as long as the particle remains trapped. As illumination continues, the electron's evolving state consists of more of the excited state and less of the lower state. This compound state: - Has a probability distribution that moves over time at the frequency of the energy difference. As opposed, it doesn't in a stationary state. - Has an electric polarization that moves at said frequency. That's why the compound state radiates an electromagnetic wave while a stationary state doesn't. - Reciprocally, the illumination at the frequency of the energy difference acts on the compound state thanks to the polarization. It changes the composition of the compound state over time, following sin2(t) and 1-sin2(t). Some pairs of stationary states combine to produce an evolving state able of radiating efficiently and EM field, for instance s and p orbitals. This is when the quantum numbers fit one photon. Then the electron de-excites quickly. Other pairs, for instance s and s states, result in sum with no polarization, and then the "transition is forbidden" and the excited state can last longer, like minutes for singlet oxygen, and more for the 21cm ray. Same for photon absorption, where only the energies corresponding to allowed transitions are absorbed. Usual light intensity takes many periods to excite an electron, hence light frequency must match the transition so its effect cumulates over time - the resonance is sharp. But strong laser light, concentrated over area and time, can for instance ionize air's nitrogen despite its frequency is completely mismatch. People speak of "multi-photon absorption"; I understand it (wrongly?) as needing no resonance to accumulate the effect over time, thanks to the available power. I've seen no description of it (nor of crystals that double or triple light's frequency...) in terms of QM. Similarly for light emission: the shorter light pulses (at the same university) are about half a period short, and use electrons that have less than the energy of an excited state... Also fun: though stationary states have an non-mobile probability envelope (psi squared) the electron does have a phase everywhere because the wave psi is a complex number. This allows the phase to rotate by an integer number along a geometric turn around the nucleus, and this number is the orbital momentum. In that sense, the electron is immobile and doesn't radiate, but its phase rotates over time and explains the orbital magnetic moment. ===================================== Photons disappearing: Particles can appear and disappear. Electrons do it in beta radioactivity for instance. Thousands of particles are created during a collision in a particle accelerator - including fermions, and not just small ones. What is conserved are not individual particles but for instance the total electric charge, the total moment, the total energy+mass, and more numbers. This is not just a rearrangement of sub-particles, as for instance the electron is an elementary particle for any experiment doable to date, and does not pre-exist in a neutron that transforms into proton, electron and neutrino in beta radioactivity. A lonely photon won't disappear since this wouldn't conserve energy, momentum and some more. But it disappears if absorbed by an electron, just as an electron (or some other particles) can create it. ======================= Anti-hydrogen: the most common theories tell its transitions are the same as for hydrogen. Though, the subject is being investigated as it would give clues to chose between new theories. Whether the neutrino is its anti-particle is still an open question, but the photon is not a debate - as far as I know, and I ignore much. ====================== "Photon comes from the empty space" results from a wrong representation of orbitals as circles. The electron is there. Both orbitals occupy this portion of space. Graviton and energy transition... Gravitation waves have not been observed, we have no consistent theory about gravitation quanta... This kind of diagram is highly speculative. Can it result from a single mass, or only a pair at least? And whether it happens: please first make the experiment to determine that, and kindly tell us afterward.

These are electrostatic forces, for which some established models to consider the solvent as a fine-grained (as if it didn't consist of atoms!) dielectric medium. For all other forces, such a model can't be adequate, to my opinion, because their range is smaller than one molecule, so the "fine-grained" trick can't possibly work.

Some ferromagnetic materials are called "soft" as they forget their magnetic history. Desired for transformers cores for instance, where the induction reverses 100 or 120 times in a second. Other ferromagnetic materials are called "hard" and keep a polarization when the cause is removed. Magnets are an extreme case. Ferromagnetic materials - mostly steel - not designed for magnetic uses tend to be rather soft, but not soft enough for magnetic uses. In the described situation, iron would retain a polarization much weaker than the one they get when the magnet is near. Also, this action doesn't cumulate significantly. Even less so because the magnet shows alternating poles to the iron, which, if the field is made to decrease slowly, is a means to erase the magnetizatio of iron. Sound tapes were erased this way. A practical example is an induction cooker, where the pan must be ferromagnetic and not too soft, so losses in the pan heat it when the field reverses. As you remove the pan from the cooker, it retains nearly no magnetization.

I can't easily make a mental picture of this. Van der Waals forces have a range of one atom or less, and the "uniform dielectric matrix" is made of atoms that will pull the nano-particles at least one atom away from each other, meaning the nano-particles don't interact directly any more. It must be possible that the matrix propagates some VdW forces say if a hydrogen bond deforms the orbital of an oxygen or nitrogen, changing its appetite for one hydrogen more, but a dielectric constant must be far too coarse to model that. The dielectric constant is used to model the effect of a solvent on ions, and such a model is already brutal - but at least a ion acts over several molecules distance, and you have half a dozen solvent molecules to apply a macroscopic value (permittivity) to! VdW forces being so more local, I hardly imagine using a macroscopic value for one or two atoms of a molecule. Beware I'm no expert in this field.

More trouble in sight... because if we were to follow similar reasons, gravity should produce a measureable voltage! Here's a setup: This one has D=600mm and can use a bicycle wheel. It rotates at 0.4Hz so gravity exceeds centrifugal force, and this latter cancels out anyway along the conductor path. The conductors are macroscopic wires of metals whose electron "effective" mass differ by 3 vacuum masses. 2*200 wires shall then produce 18nV at 0.4Hz. Yes, it needs shielding. It also needs a uniform temperature that doesn't cycle at 0.4Hz. The amplifier rotates with the wheel. Build an instrumentation amplifier with an LTC6241 for instance: at 70nV/sqrt(Hz) around 0.4Hz for each opamp, an FFT must accumulate data for some 5 min to get 5 sigma signal-to-noise ratio. ----- Trouble... Very probably, this one doesn't work for being a perpetuum mobile. The only possibility would be that the shaft brings power, just like when you rotate a tube with a ball in it, and for a short time, the ball's movement means true work. This is the only reason why I take a CMOS opamp here: it's more noisy but if the total charge of the signal is limited then a CMOS is more likely to pick it. What if the centrifuge produces a signal and gravity doesn't? Uncomfortable... It could be that electrons in a metal respond differently to acceleration and to gravity - something new. And what if neither the centrifuge nor gravity produce a signal? Then maybe the contact electric potential changes with the gravity potential. Marc Schaefer, aka Enthalpy

But that won't let water boil gently, will it?

Stearic acid is a commercial product. Why should you make 10 grams of it?

Hi Anders, nice to see you! Interesting idea, if I got it: they create resonating small structures that increase towards 1 the emissivity of tungsten, and preferably only at the useful wavelengths. Well done. About visible light produced by any other material, alas... Any decent efficiency for thermal emission in the visible spectrum demands a temperature such that only tungsten works. Any other material has a bigger vapour pressure (even refractive ceramics that melt at a higher temperature than tungsten, alas again) so it can't attain the temperature of tungsten, because of evaporation. Then, temperature determines very strongly if light is emitted in the visible spectrum or in the infra-red, and this influence tends to be stronger than any improvement we can add to the design of the emitting body. Hence the trick with micro-resonators in tungsten is smart. I just wonder how long they last, because tungsten evaporates and a few µm are very little. Does the performance improvement allow to reduce the temperature, and this cooler operation still improve efficiency at identical lifespan? Low-voltage bulbs are better because the filament is thicker, and halogen because tungsten settles back on the filament. I doubt you can put any material other than tungsten (let's forget ITO, this one was just an example) for visible light. But for IR maybe. "Sort of" laser yes, because temperature won't achieve the population inversion needed to achieve gain at stimulated emission. But the resonator of the laser would improve light emission, yes. I wouldn't use metal for the mirrors since such thin layers evaporate so quickly, but dichroic mirrors. Then, at the E field antinodes of the cavity, emissivity increases - but it decreases at the nodes, cancelling out in a big part. So you would better have many small cavities, or a flat single one - and this begins to resemble quantum dots. The other solution to efficiency is non-thermal emission like LED or laser diode, but as you said, their light is still unpleasant.