Enthalpy

Original Tárogató music, neither folklore nor lengthy sheet with the superfluous reverberation: http://www.paschart.ch/music/instruments/tarogatos.html the two other instruments could be tenor tarotatok.

Being narrow contrabasses, both Tubax (which are morphed saxophones, longer and narrower) must have a huge natural range. http://www.eppelsheim.com/en/instruments/tubax-eb/ http://www.eppelsheim.com/en/instruments/tubax-bb/ Their saxophone fingerings hamper exploiting it as they prevent many open-closed combinations that reach the high notes. The fingerings I last proposed (Jul 08, 2017) improve that. The same holds for the low sarrusophones and rothphones. I would keep independent register keys on such instruments, with no automatic works. A wide set of them, operated equivalently by both thumbs when they don't play the five low notes. But for C-D trill, a single thumb must press at once the cover for D and the (lower) second register key. Tone holes not too large make cross fingerings more efficient. Tube bendings should be wide. Marc Schaefer, aka Enthalpy

The question is whether the small tokamak suffices. If a fission reactor can produce more 99Mo than necessary, it doesn't make it better. The huge neutron flux in a fission reactor is an equally huge drawback. This, and the fission itself, produces huge amounts of radioisotopes that pollute the desired 99Mo, lead to proliferation, and are unwanted independently of any production. Computing the mean free path gives figures of few cm, not 10cm. "Moderator". Nobody wants to keep fast neutrons. I didn't write "moderator made of molybdenum". Why do you suggest this bad idea? Any reactor designer and design uses several materials. ---------- I'm a bit uncomfortable by the many times you introduce arguments based on implicit and false assumptions: straight neutron path, only molybdenum, target outside the containment, neutron reflector, and so on. I estimate that your knowledge for neutronics is better than that. In case this is deliberate, it resembles more propaganda than scientific arguments.

If computing with more details than the exponent, you get figures smaller than that. Deflecting (you write "reflector", I din't) the neutrons by an other material that thermalizes them makes a huge difference, just as I had expected. It gives the neutrons a Brownian motion that lets them pass many times through the molybdenum. Under such conditions, the absorption is much more favourable than in the "straight path" model. Very roughly, if neutrons diffuse from a neutron-rich side to a neutron-poor one through a material that is N times thicker than their mean free path there, they make mean N2 collisions during the diffusion, and their Brownian motion is N times longer than the material thickness, giving many more opportunities for the absorbing material to act. A D=2m machine won't cost more than a D=20m one. But yes, I did scale the cost as the volume, which is wrong (as I has suggested). Can anybody do it better at this point? No, the target doesn't have to be outside the containment. Why do you suggest that, and are affirmative? At Iter, the tritium-breeding blankets will be inside. By taking arbitrary and uniform thicknesses, implicitly relying on a wrong neutron straight-path model, you get wrong figures.

Even when the ions have enough energy, which happens at an accelerator, the lucky collisions are rare. Most events are quasi-collisions that dissipate the energy without result. Because the target is cold, the energy lost by the impinging ion isn't available any more for future collisions. In a plasma as opposed, where all ions are hot (if not all hot enough to react), ion collisions don't waste energy: all the heat energy remains available. Only light radiation (and plasma leaks) let the plasma loose energy, and this is a much slower process. The net result is that you get more reactions with the same energy input from a plasma. This is the very reason why attempts to obtain net energy from fusion reactions use a plasma rather than an accelerator. Fusors and polywells (electrostatic confinement) are much worse than tokamaks at obtaining many fusion reactions and at obtaining them with a small power input. The fusion experts' consensus is that they can't produce net energy, for instance. Independently of any rationale, if you check the measured neutron production rate and the reaction rate per power input unit, fusors are very week, much weaker than particle accelerators. Thermalized neutrons are more favourable than that. As the cross-section for elastic collisions exceeds the absorption cross-section by far, they change their direction many times before getting absorbed, instead of flying through in a right path. As soon as the thickness produces many direction changes, the flux decrease isn't any more an exponential depending just on the absorption cross-section. I must have a look first, but my gut feeling is that the flux decrease with thickness resembles a diffusion equation then, with a faster decrease. Interleaving 98Mo with elements that deflect neutrons better would improve that effect. That's for material properties. There are engineering means too. At 4K instead of 77K, the exponential decrease length resulting only from the absorption drops from 0.6m to 0.14m. The production of 99Mo doesn't need to catch all neutrons neither: I estimated one single 0.001*Iter tokamak to cover ideally twice the worldwide demand, but several machines are needed for short delivery routes and for redundancy, so using 10% or 5% of the neutrons would suffice, even if not intellectually pleasant. Then we're far under 7mm thickness at 4K. Neutrons can also be channelled - and many more subtle operations - but that's too widely out of my knowledge. 99Mo doesn't have to be separated from 98Mo if I understand properly - but I could be horribly wrong. 98Mo is stable, while the decay of 99Mo produces the useful 99mTc which is separated at the hospital https://en.wikipedia.org/wiki/Technetium-99m_generator At least, the activity of the presently delivered "99Mo" is much lower than if it were pure.

Yes. But in a plasma, that energy is not lost through the elastic collision. If one D or T has more energy than average, it will lose energy over the collisions in average, but the other ions receive this energy, which remains available for future collisions. If, ideally, the plasma is perfectly contained, the only energy loss is by X-ray emission, due to electrons deflected by ions (a good reason to avoid heavier ions in a tokamak). As opposed, with an accelerator, the target nuclei are cold, and the energy transferred by the impinging ion is just spread over the cold matter which can't make successful collisions from that: this energy is lost. The storage ring of an accelerator wouldn't be good neither. Here all ions are "hot" but collisions give them a transverse energy which isn't useable in the future. I can only think of a plasma where collisions keep the energy reusable. Among the devices, fusors and polywells give a small reaction rate, tokamaks a big one.

Yes, that's it. Thick graphite is required, but that's affordable. Cooling it and placing the target needs some engineering. Then, I only compare the relative cross-sections to know what proportion of neutrons is absorbed by 98Mo to produce 99Mo. This paper of 2016 describes their accelerator that produces 1012n/s http://onlinelibrary.wiley.com/doi/10.1002/er.3572/full and cites existing machines that produce up to 1013n/s and announce a goal of 1014 to 1015n/s for their future machine. Compare with 2*1015n/s estimated here. That's a partial picture. All cited machines consume D+T, not D+D as I assumed. Feeding the 0.001*Iter machine with D+T would make 100* more neutrons, or 2*1017n/s. It's the basic reason favouring tokamaks to produce energy too. The same energy expense is reused in many collisions in a plasma. An accelerator uses the expended energy in few collision. An other, qualitative comparison: if the operator of a fusor or accelerator has tritium available, which is produced by a fission reactor, he can obtain 99Mo from that same fission reactor, more easily and efficiently than by consuming the tritium. The D+D tokamak, as opposed, works without the uranium cycle. This gives more flexibility against politics and ageing reactors.

Thanks both for your interest! Yes. The present chain for 99Mo is organized to minimize this loss. Accumulation and shipment are done over few hours. This is an excellent reason to have one or more production sites per continent. It reminds me of how the ancient Romans had ice in their fridges: it was brought down from mountains by slaves. If only I knew that! But what I have read is that the other alternatives to fission reactors produce too few neutrons, fusors being worse than accelerators, and that's a strong limitation. Apparently, a small tokamak has at least this argument in favour.

Hello dear friends! I'd like to propose to produce radioisotopes using the D-D reaction in miniature Tokamaks, especially for medicine. Tokamaks (including stellarators) top the rate of permanent nuclear fusion reactions for a given size and input power https://en.wikipedia.org/wiki/Tokamak https://en.wikipedia.org/wiki/Stellarator so big machines fed with D-T claim to produce net energy (present) at affordable cost (uncertain future) https://en.wikipedia.org/wiki/ITER As a neutron source instead, the machines would Not try to produce any energy, even less net energy; Receive only deuterium (2H or D) without the scarce 50% tritium (3H or T); Be 10*10*10 times smaller than Iter with the same operating conditions: D=1.2m and 50kW input and 20M€ (...err); Emit neutrons to irradiate fertile material like 98Mo. Their activity or misuse would produce little plutonium, tritium and radioactive waste. From my estimates, the isotopes production would be naturally good - maybe at a lower cost than the other alternatives to fission reactors. ---------- Figures Welcome to double-checkers, even more as usually, as a 3.7*1010 factor may well lack somewhere! Iter is to produce 500MW heat (over 400s, let's forget that) from a 17.6MeV reaction, that's 1.8*1020/s. At the same induction, density and 150MK, the D-D reaction is 0.012* as frequent as D-T and the machine is 1000* smaller, for a reaction rate of 2.1*1015/s. Every second D+D reaction produces 3He+n, the other T+p, but T is consumed 80* faster in a D+T reaction that produces one neutron too: 4He+n. So 2.1*1015/s neutrons as well. The target shall catch all neutrons (how?) and consist of pure 98Mo (that's more expensive than presently) in the example I choose. Something (Nitrogen behind graphite and molybdenum? Heavy methane?) shall thermalize the 4kW neutron flux to 77K=6.6meV: http://www.nndc.bnl.gov/sigma/index.jsp thank you! (n, total) 6.07b http://www.nndc.bnl.gov/sigma/getPlot.jsp?evalid=15091&mf=3&mt=1⊄=10 (n, elastic) 5.79b http://www.nndc.bnl.gov/sigma/getPlot.jsp?evalid=15091&mf=3&mt=2⊄=10 (n, gamma) 0.26b http://www.nndc.bnl.gov/sigma/getPlot.jsp?evalid=15091&mf=3&mt=102⊄=10 I heavily overinterpretate curves made by models and don't integrate over the energy distribution. Then, the inelastic collisions section is 0.28b and (n, gamma) make 90% of these or 1.9*1015/s. Still 60% at 300K so money shall decide. Over a 5*24h week, the tokamak produces 8.3*1020 atoms of 99Mo. 2.75 days half-life = 343ks exponential decay mean 2.4*1015Bq=65 000 Ci produced per week. 99Mo decays fully to 99mTc used for medical imaging. The worldwide demand is 12 000 Ci per week according to Aiea https://www.iaea.org/About/Policy/GC/GC54/GC54InfDocuments/English/gc54inf-3-att7_en.pdf satisfied by one mini-tokamak - rather several ones, since 99Mo must be transported swiftly. This allows for: Correction of limited errors in my estimate; Account for limited design constraints; A smaller machine, or if possible less strong fields; Production of other radioisotopes; Work during daytime. Build and sell two mini-tokamaks per continent for redundancy. Marc Schaefer, aka Enthalpy

The last fingerings I proposed look excellent for the flute - simple, flexible - and the drawbacks small - high A, middle D and two trills less than perfect. But these fingerings fit the oboe, saxophone and others less well: The middle C on the second register isn't normal on the oboe and is bad on the saxophone; These instrument go usually to low Bb; which justifies my fingerings of Jul 01, 2017 for them. A first improvement is to attribute (approximately) four notes to the indexes rather than the little fingers, because They are stronger, faster and more mobile; They move easily in the opposite direction to the other fingers. This eases cross-fingerings. A second improvement, independently of the involved fingers, is to put the related group of toneholes near to the throat, not to the bell: (Approximately) two covers can then be closed and two open at rest; Moving them takes less force and is more quiet; The keyworks are simpler and easier to adjust; It's easy for the musician and keyworks to open one hole and close a lower one, as needed by high registers cross-fingerings; On small instruments, the hands' location is more comfortable. This example moves four covers from Bb to C# with six keys. Some keys address only cross-fingerings: open C# leave C, or close Bb leave B. Other combinations are possible, including one key per hole and one finger targeting sometimes several, possibly at different phalanxes. Only experiments can tell. ---------- The two lower registers' fingerings with both improvements can become: (click for full size) I won't risk any forecast about cross-fingerings for higher registers on these instruments. Holes can be opened independently from C# down to Eb now - four notes more for big flexibility. Marc Schaefer, aka Enthalpy

Amazing. I only don't see why it should be called "flute", but to my opinion, synthesized music doesn't need to reproduce existing instruments. By the way, this sound is periodic, as about any one from a synthesizer, so it has no chance to imitate a flute, a sax, a violin... whose sound is inherently non-periodic. The misconception (sound quality = harmonics) dates back to Helmholtz and is carefully propagated to new student generations since then. With a periodic sound, one can more or less imitate a clarinet or an oboe.

The flute should benefit from my fingerings (hopefully). Since Boehm's excellent improvements, every design detail thrives to minimize the losses: huge tone holes, no register key, at least two consecutive tone holes open at the main closed-open transition... Any departure results in a weak and dull sound. For instance the C# hole, which is located at D and is an oversized register key serving for just three notes, is far too small as a C# tone hole and makes horrible notes. F# are played with the ring finger, making difficult transitions with E. Eb must be opened but for D, whose transitions with any note are difficult. Cross-fingerings make the complete 3rd octave, and the combinations they need exclude many useful variations, for instance F# closing G# as on the saxophone. And as the 3rd G# uses a wrong tone hole ( C) it's badly low - I've played two exceptions only. As a consequence, the flute has cumbersome fingerings, and about any small improvement is excluded. But I hope a big one is possible - tabula rasa. ---------- Here the little fingers act like the six others to provide a half-tone each instead of four together. The thumbs make 5 more notes, as most flutes go to low C, and have no register key. The flutist shall hold the instrument (very precisely as a flute) at his palms with handles like a bassoon; this needs careful design. Click for full size: Fingerings are uniformly easy on the two first octaves. Trills at the lower end of the 2nd octave are questionable, since these notes aren't good on the Boehm flute. Maybe an added low B improves that, or a tiny register key serving for these C C# D only and opened by a thumb key along the three note keys for simultaneous use - or add the usual trill keys near the throat. ---------- Being completely independent, the high 8 note holes give full flexibility to cross-fingerings at the 3rd octave and above. Written one octave lower than it sounds. Click for full size: Simple logic (H3, H4, H5, H6...) applies fully to the Boehm flute and I use it here too. D Eb E F F# (optionally C#) open one hole at the 3rd pressure node and all holes beginning at the 4th. The thumbs note holes are not displayed, only the keys. G G# could also open just the holes at the 3rd and 4th pressure nodes and all holes beginning at the 5th. Not done on the Boehm flute, may ease the pp. G# must intonate perfectly, big progress. A can only open the holes 3rd and 4th+ nodes and should be nearly as good as G on present flutes, not as good as A which opens the 5th hole too. Bb B C should improve as they open the proper 4th 5th 6th+ holes. Not needing the trill keys, they make easier transitions with other notes. C# is the last accessing the 4th node but the first accessing the 8th (or 7th) one. Most present instruments can play an F with uncertain stability and intonation. My fingerings improve that, hopefully. ---------- The development of such a flute should be a reasonable effort, as the holes positions and sizes could nearly be kept and their adjustments are intuitive. The C joint is 3 holes longer, the main joint 3 shorter, the head is kept. The rest is keyworks. Beyond the flute, only the clarinet has logical cross-fingerings, but isn't a candidate for such fingerings. The oboe family and tárogató play the upper register with cross-fingerings, so this design for the flute should benefit them as well. Shift all holes and fingerings one note lower to emit Bb, or add thumb keys, plus register keys. Though, the small tone holes, which are vital to a double reed's sound quality, and distinguish the tárogató from a saxophone, make cross-fingerings unpredictable. So a design would need both to define the best cross-fingerings and let them intonate properly, which takes more time. Marc Schaefer, aka Enthalpy

The thumbs and little fingers must close many tone hole covers at once, and perfect tightness demands accurately synchronized keyworks. ---------- On the saxophone, the F, E and D covers close the F# accurately, with years-proof adjustments through cork thickness, so a small adaptation shall fit my purpose: The tubes' diameter gives stiffness over a good length, the other subparts are cast and soldered, as usual. Lower covers act directly on higher ones, not as a daisy-chain: stiffer and more accurate. Assembling the instrument's joints can be done naturally at the ends of the little fingers' section and thumbs' section. Key overlaps can transmit the movement between the joints as on the clarinet, and pressing the covers down (blue key on the sketch) when assembling spares the corks. The keys for the right little finger can have a common axis nearly aligned with the covers' one, optionally shared with the keys for the left finger. The keys for the thumbs would rather have an axis at the bottom left or right, transmitting the movement to the lower joint at an instrument's side. It seems logic to have the axis at one side for the little fingers' covers and at the other side for the thumbs' covers. Individual finger keys could have acted on several covers at the transmission between the joints, but I expect mounting inaccuracies to create leaks then. It would also demand to press all covers individually when assembling: less easy with big instruments. ---------- If the instrument's section bearing the little fingers' or thumbs' section makes a U-turn, like the boot does on a bassoon, synchronizing the covers seems easy too: Such keyworks look quiet, simple and affordable, and on some instruments (oboe?) the other holes operated by one finger each can be open, with no cover at all. Could that make cheap instruments? Marc Schaefer, aka Enthalpy

This first drawn example addresses woodwinds that cover naturally some 2.5 octaves: oboe family, saxophone, tárogató, sarrusophone and rothphone... https://en.wikipedia.org/wiki/T%C3%A1rogat%C3%B3 https://en.wikipedia.org/wiki/Sarrusophone https://en.wikipedia.org/wiki/Rothphone it doesn't apply as is to the bassoon nor clarinet family. The existing fingerings of the saxophone (the sarrusophone and rothphone have the same) are rather convenient but need complicated mechanics, and the holes closed below the height-defining one make the sound quality and intonation unequal. Additionally, the traditional tárogató has less convenient fingerings and the oboe family requires more complicated mechanics. ---------- So that's my proposal, here with 4 plateaux operated by the little fingers and 5 by the thumbs: (click to enlarge) The musician can use the right or left little finger for any of the four notes, and the right or left thumb for any of the five thumb notes. As on the Boehm clarinet, it lets alternate the right and left hands on successive notes. ---------- The little finger keys close 1, 2, 3 or 4 plateaux at once, but at least the fingers don't have to slide between the keys. Big saxophones may better transfer one plateau to the thumbs. Tightness requires accurate mechanics, to be described later. Trills require only to extend the second and third registers by a full tone. For the medium C-D, one thumb must hold the speaker key and the D key while the other trills the C, so either the speaker and D keys must be close enough, or an additional key acting on both is provided. My proposal has just one tone hole for each note. This reduces some losses, and spreads evenly the extra volume of the closed holes, whose effect is easier to compensate, including at the harmonics. ---------- The drawn third register is theoretical! Early saxophones and sarrusophones had foreseen it that way, using the lower speaker hole with the upper tone holes. For supposedly good reasons, they now have extra tone holes to play the high notes on the second register and make trills too. This can combine with my proposal. The note height of the third register and above follows no simple logic with the narrow tone holes of the oboe, bassoon, tárogató, for which the drawn fingerings are inaccurate. Nearly all use cross-fingerings instead, where an isolated tone hole is open at a pressure node (sometimes at several) well above the main transition between closed and open holes. This spoils the lower modes and reflects better the desired mode. My design's highest six tone holes are independent, which gives full flexibility to cross-fingerings, and all the holes open below the main transition ease the emission. Marc Schaefer, aka Enthalpy ---------- Hi DrP, I'll come back!

Hi DrP, nice to see you here! The very nature and usefulness of a forum are the contributions that don't go in the expected direction, so "isn't what you were looking for" is absolutely fine. A somewhat similar attempt was at the octo-basse, an oversized bowed string instrument made by Vuillaume. As the musician couldn't reach the top of the strings, he played the notes' height on a keyboard, and a mechanical transmission pressed the strings at the corresponding length. No electricity needed. And believe it or not, the Montreal symphonic orchestra has recently bought such an instrument. https://www.youtube.com/results?search_query=octo-basse

Hello dear musicians, music lovers and everyone! I'd like to describe fingerings for music instruments with tone holes (which almost means woodwinds) and the associated mechanics. My goals for these fingerings are: Open all holes below the height-defining one, at least on the two first registers; Have no difficult key nor sequence of notes; Not need to close a hole and open an other simultaneously, at least on the two first registers. That's a difficulty of the flute; Need few tone holes regularly spaced and reasonable mechanics; But I don't primarily address the ease or possibility to disassemble the instrument. 1) and 4) make the sound quality more even and let build an instrument with better intonation. To achieve that, my very own personal proposal (... other people have proposed so many!) is: Give one half-tone to the index, middle finger and ring finger of each hand, to cover the upper part of all registers; Continue lower by approximately 4 half-tones with the little fingers. Each has the full set of keys like on the Boehm clarinet; Continue even lower by approximately 5 half-tones with the thumbs. Each has the full set of keys too; Trills near a register limit are made by the little fingers or thumbs, so the registers must overlap. No extra tone hole. Have register keys at the thumbs. Preferably, each thumb has the full set of register keys. The third register and above can't be common to all instruments: an additional register key suffices for some, others need cross fingerings, still others have extra tone holes. One finger for each of the highest six holes make cross fingerings more flexible. Expect differences among the instruments at the two first registers too. The thumbs, being agile in two directions, are the best fingers to operate several keys - bassoon players can confirm. The full set of keys at right and left little fingers is very convenient on the Boehm clarinet, where musicians alternate the notes among the hands. I propose to generalize it to the thumbs, both for lower notes and register keys. Drawings to come should make it clearer. They take me a little time. Marc Schaefer, aka Enthalpy

What of the previous ideas could be retrofit on the CL-415 Canadair? The remote control needs "only" control and video transmissions. Since the plane supposedly has hydraulic actuators at all controls, servovalves can be added as alternatives to the manual inputs. This avoids fatalities, since crashes do happen in this job, and lets share the scooper-bomber operator among several aircraft. It also improves the payload. Fuel cells still weigh much: 0.5kg/kW https://en.wikipedia.org/wiki/Toyota_Mirai so replacing 2*1775kW turbines takes 1775kg fuel cells. The electric motors can be lighter, but the hydrogen tanks are heavier. So while the flight duration improves a lot, the payload diminishes. More interesting at a new design, especially if not a flying boat, to my opinion. The in-flight scooping ski makes most sense if not a flying boat, to save structure mass and ease the design. At the CL-415, it would let use shallower waters and save kerosene. It's also safer against debris collisions. Pressure-fed water tanks would avoid to spread the last water inefficiently, and above all, they are a life-saving means against stalling.

As an alternative to parylene, the US patent 2,917,499 from 1959 https://www.google.com/patents/US2917499 describes a monomer that can be applied on a surface and polymerizes by air contact. The resulting hydrocarbon polymer layer is water-tight and resists solvents. That would make a thick coating faster than parylene. The patent doesn't describe the possible drawbacks.

SpaceX gave information about their future Raptor methane engine https://en.wikipedia.org/wiki/Raptor_(rocket_engine_family) only a true full-flow, including one fuel-rich pre-chamber, can achieve 300bar in the chamber. I've seen no report about soot or not at the pre-chamber and turbine. Soot would make the reuse of the engine more difficult and reduce the efficiency. Thermodynamic equilibrium tells "soot", but maybe the pre-chamber can first have a balanced flame, then quench it at once with the methane, so soot has no time to form at moderate temperature between the pre-chamber and the chamber. In case soot remains an issue, replacing the methane-rich pre-chamber by the recombination of an auxiliary propellant would keep much of Raptor's design and performance. Hydrogen peroxide, hydrazines and methylamine are badly dangerous, but I've described amine mixes that recombine at a good temperature without soot (paperwork!): http://www.scienceforums.net/topic/82965-gas-generator-cycle-for-rocket-engines-variants/ and followings http://www.scienceforums.net/topic/83156-exotic-pumping-cycles-for-rocket-engines/ and followings check for grey shaded tables. Liquid amine mixes can be fed from their tank by helium, and solid ones recompose in their casing, with turbine inlet vanes controlling the pressure hence speed of recomposition. Raptor's vacuum 3.5MN and Isp=382s with 360:100 mix ratio need 203kg/s methane subcooled to 447kg/m3. Liquid injectors to 300bar and a pump, 88% and 74% efficient, take 20.9MW at the shaft. Expanding from 88bar to 1.8bar at a 79% efficient nickel alloy turbine need 23kg/s of added amine mix. This flux, 2.4% of oxygen+methane mass, expands further to 0.4bar and 730m/s to provide roll control and add 17kN (0.5%). The composite Isp drops by 1.9%, but 0.5% more thrust and propellants improve a first stage, whose performance drops by about 1.5%. ---------- An other alternative may be an oxygen-rich staged cycle with a molybdenum alloy turbine to keep a good chamber pressure. At a new engine design, I'd rather have cyclopropane or spiropentane in an oxygen-rich staged cycle, or to smash methane's performance, cool the engine with the oxygen, and burn ethylene or if possible bicyclobutane. Marc Schaefer, aka Enthalpy

To communicate with Earth, a presently projected manned base on the Moon's far side needs a data relay. This can be a first application for a Solar sail on the scale already described here. The relay would reside 2Mm North or South of the L2 Lagrange point, 65Mm beyond the Moon. The tilted sail provides over decades the permanent 46µm/s2 thrust inaccessible to chemical propulsion. The relay is always clear from L2 where the Moon eclipses the transmission: better than the fuel-saving eight-shaped wobble around L2. The thrust has always a component opposed to the Sun's direction, so the relay resides also before or after L2, maybe it circles around it in a month. The sail's orientation can rotate regularly or oscillate up to about twice a day. I won't refine this. The 1.7hm2 sail can have 5 booms and sectors as described on 25 August 2013. The booms described on 15 March 2015 weigh 180kg, shrouds 40kg, a 13µm film 320kg. At 60° angle of incidence, 41mN North or South allow a 900kg spacecraft, leaving 360kg for the bus and payload. If compatible with the sail, the bus could resemble a geosynchronous satellite: one side facing Earth and Moon, with antennas on East and West sides, a rotating Solar panel at North or South side. Emitting 300W=+55dBm at 10GHz and 65Mm distance (-209dB), antennas of D=1.8m (44dBi) at the relay and D=1m (39dBi) on the Moon let receive -71dBm, enough for high definition videos. Interrupting the sail's metal film several times per microwave length makes it transparent. If starting from slightly tilted Leo, the craft would take good 5 years to reach L2. Vega can put the 900kg on a higher orbit. Marc Schaefer, aka Enthalpy

Hello everybody! Microsoft has released a patch against Wannacry (aka Wannacrypt, WanaCrypt0r 2.0, Wanna Decryptor) even for Windows XP but if you browse with XP or anything less than Seven, their page won't work. That is, you can get the US-English patch for XP, or a translated patch for XP embedded. None applies directly on a Windows XP that is neither English nor Embedded. So here are the download addresses for the translated patches for XP sp3: http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-ara_ec0e5c3d7d1433686c5d59a144d25f99d2e42945.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-chs_dca9b5adddad778cfd4b7349ff54b51677f36775.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-cht_a84b778a7caa21af282f93ea0cdada0f7abb7d6a.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-csy_0d3b05e28c9b74e02f8880d510236e2ca946136f.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-dan_2923c2e1c5af998fccbefdf943dd21541290970a.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-deu_c1e81e14c283f2adbbdce9c1de348b4295b6a45c.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-ell_c7096e83ecfbb487569f986f50ec9cd7bf1b6476.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-enu_eceb7d5023bbb23c0dc633e46b9c2f14fa6ee9dd.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-esn_1fbe054158b612f4d37558975f925469239fa4c3.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-fin_8437b82a5813c7bbfc49acf41184964571dbc4a7.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-fra_eb47689656c58ab374521babb9bdca07304d87f5.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-heb_6f350108d1fc966e2827275791f7fa59ed2b796e.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-hun_c224c0c73222bf850a7c3925aa77710374dea7c6.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-ita_fd509a8ba0a6d53bbe3ebe596ea8c8a15e0a2852.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-jpn_1836e8e67fdffb285b730c1476ec1806bc7c5658.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-kor_b2a6516e2fd541c75ebb4bcaeb15e91846ac90c5.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-nld_b5ca96f480a0c1eed967f4d61d8eb7c8ace46003.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-nor_8267b2e4fee715c7c5dc8694a9ec851fb3af2a74.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-plk_05bec673af4dad0a111aacb89fe2c463539c010e.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-ptb_916cb3aa70ee0e49588196aae0df8f19bfd1c127.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-ptg_90b15b2c32519cc241a8edebd1d912ab93b8b950.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-rus_84397f9eeea668b975c0c2cf9aaf0e2312f50077.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-sve_83fda8bb513115db20f024cecf43008fe8bc36c4.exe http://download.windowsupdate.com/d/csa/csa/secu/2017/02/windowsxp-kb4012598-x86-custom-trk_6e77a15f3faabd3db9928e7adedcde687f412a72.exe choose your language(s) in the file name after "-custom-", for instance ptb is Brazilian Portuguese. Scienceforums shortens the links, but you see them full by overflying with the mouse.

Hi sunshaker, Magnetic fields do alter orbitals. The proper theory for orbitals is quantum mechanics, and its description of orbitals wouldn't straightly say "speed" and "radius", but this image isn't very wrong. Try to read about the Zeeman effect. Possible states for the mobile electrons in a solid result in part from orbitals, which are stationary states of electrons in isolated lone atoms, but heavily modified by the interaction of the atoms as they're close to an other, so deducing the solid's behaviour from atomic orbitals would be difficult or possibly sterile. The effect of magnetic fields on superconductivity is known: it hampers, for every material I know. The effect is well explained and doesn't result from the Zeeman effect. A stronger external induction implies a colder temperature to reach superconductivity, or implies a smaller current density, or both. Even at extreme cold and tiny current density, there is a maximum induction beyond which superconductivity is impossible, it's called the critical induction. Well, in type II superconductors, there are two transitions, but they behave identically. Have a look at Wikipedia. Pressure is needed with some materials only. As the induction hampers superconductivity, my guess is that it would imply a bigger pressure.

Here's a situation similar to the hydrogenoid atom, but simpler as it involves no quantum mechanics. Two particles collide head-on and rebound elastically, for instance a proton and a positron with speed relativistic but not enough to make new particles. Their common centre of mass is immobile as is a first observer who sees them reverse their speed. A second observer has a constant speed u, say perpendicular to the particles' path. He sees both particles having a speed component -u before, during and after the rebound. The punched screens make it more dramatic: the immobile observer sees the particles come back through the holes, hence the moving observer too, and the screens have kept their speed -u. The particles' momentum along u is u times their relativistic mass before and after the collision. We wish this momentum component to be constant over the collision, so the moving observer must attribute to the particles a mass that is constant over the collision - even when the transverse speed gets smaller or zero as the kinetic energy converts into electrostatic energy. That's consistent with the mass of heavy nuclei, where an observer external to the nucleus weighs the protons' electrostatic repulsion. By the way, this increase doesn't depend on the speed u, which can be small. Though, the immobile observer computes the collision with a particle mass depending on the speed only, not on the electrostatic energy. Worse, the moving observer too computes the transverse speeds during the rebound using no mass contribution from the electrostatic interaction. So the mass of the electrostatic interaction depends on the observer, or worse, on his purpose, yuk. Possibly like: the repulsion energy makes particles heavier except for the acceleration that results from this interaction. O good. Spread the electrostatic contribution to the mass in the vacuum where the fields of both particles interfere, rather than on the particles? But why wouldn't that mass slow the particles' acceleration due to the repulsion? The interference of the fields moves with the particles. Uncomfortable too: the lighter particle, which carries the biggest increase of relativistic mass since the centre of mass is immobile, also carries the biggest increase of electrostatic mass, despite both particles experience the same electrostatic potential, including the slope and curvature. So the electrostatic contribution doesn't depend on local field quantities, but on the particle's history through the field, or possibly on the rest mass. I didn't consider the magnetic induction here, despite charges move. Nor the radiation, despite charges accelerate (but identical particles would radiate little). Did I botch something? Would someone kindly shed light on this mess? Marc Schaefer, aka Enthalpy

Tesla has improved its batteries and you get a 14kWh Powerwall-2 for 120kg, 1.12m*0.74m*140mm and 5500usd. A battery-powered aircraft looks now less like a demonstrator and more like a vehicle. The following example is adapted from DG Flugzeugbau's DG1001T, thanks http://www.dg-flugzeugbau.de/wp-content/uploads/Flyer-DG-1001T_d.pdf http://www.dg-flugzeugbau.de/en/maintenance-service-aircraft/scale-drawings-gliders Modifications bring the 750kg to: 475kg frame 200kg two people with luggage 480kg four batteries 40kg propulsion and wheels ------------------------------- 1195kg take-off mass The frame mass is kept by giving up the full +7g -5g aerobatic capability. Two main wheels let take-off autonomously; powering them for take-off would be easier than at airliner speed. A longer wing chord keeps the speed. This reduces the lift-to-drag from >46 to estimated 30 at 40m/s = 144km/h = 78knt, so 391N provide the cruise speed. 75% efficiency need 20.9kWe, fitting the Powerwall-2 unit 5kW mean and 7kW peak. The capacity lets fly 2.6h for 370km = 200nm range. Marc Schaefer, aka Enthalpy

The cited document has the same scientific value as about everything related with LENR: none. I'd close an eye on the g versus kg, the 9g versus 7g, and so on... But NOT about the electron's energy in a periodic potential equalling its kinetic energy. Nor about the nuclei's potential being allegedly a barrier. Did you notice? Their are positively charged and attract the electrons. And so on and so forth. B*llocks.