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No antennae radiate all the power fed to them!
On 11/2/2014 5:02 AM, Lostgallifreyan wrote:
rickman wrote in : What? For a wave to have a "bulge" above the top of the tank means there is a trough well below the top of the tank. The amount of liquid does not change because you make waves in the tank. I didn't say it did. Anyway, What did you mean by, "that tank will hold more liquid that it would if brim full without the wave"??? I've been looking at images on Google, apparently the single half-wave form is concave in a tank of liquid, not convex. Maybe that too is possible, I don't know. If it is, then you can add liquid to what was a brim-fill tank before it overflows once the wave is set up, which would indicate that a form of storage has been set up. You are aware that a standing wave still moves up and down, no? So a trough turns into a crest and vice versa. -- Rick |
No antennae radiate all the power fed to them!
Lostgallifreyan wrote:
wrote in : The only external heat source in space is the Sun; solution, sun shade. Maybe not. I just did a bit of Googling for 'superconductors in space' minus quotes. There's a lot of statements abotu space missions ended because required helium or hydrogen coolant ran out, Yeah, the coolent ran out for the things that GENERATE a lot of heat and need to be cooled more than radiation can provide. Radiative cooling does not provide for a lot of cooling. and also of space having latent temperatures up to 100K, so a sun shade won't help a lot there with current materials. There really is no such thing as temperature in space as it is a vacuum. Also, show me the 100% efficient sun shade. Maybe the James Webb scope's shield might set some new precedents if that gets launched. Grocery store aluminum foil will come very, very close. Basically, any worth in the idea will come out of some compromise between ambient conditions and new higher temperature superconductors. And if they end up cheaper to lug up there than the current materials for antennas and matching networks, they may get used anyway. Without knowing what materials become available, and the needs for them, we can't assert a lot about what is possible. We already know what is possible. There is no undiscovered magic in superconductors. -- Jim Pennino |
No antennae radiate all the power fed to them!
On Sunday, November 2, 2014 1:51:46 PM UTC-6, Jerry Stuckle wrote:
No, I don't think any part of the ISS is in "constant shadow". I believe it rotates as it orbits the earth, and different parts of it are in the shade at different times. I could be wrong, though - I've never been there :) Hard to say.. Some parts away from the sun may stay dark during a daylight pass, but they may be lit on other passes, depending on the direction and angles to the sun. I suspect they want to keep the solar panels towards the sun as much as possible, but the panels themselves may be steerable to some degree. I've never been there in person, but I've been there via camera on many an orbit. Watching the planet from that platform can be good wholesome entertainment for the whole family. :) The station itself does not really appear to roll at all. Or at least that can be detected on a lit pass, and using the earth as a "roll indicator" of sorts. But anyone can watch for themselves as long as they are in contact, and not on a nighttime pass. The cameras they are using don't seem to be too sensitive at night. IE: I hardly ever notice the lights below on a dark pass. Of course, they zip around the planet in about 90 minutes time.. So quite a few chances during a day to see what parts of the station are lit, and which are not. Some cameras, like the one I'm watching right now do not show the station at all, while the one they were using a few minutes ago did. At this moment they are fixing to pass into darkness over the Atlantic. http://eol.jsc.nasa.gov/HDEV/ http://www.ustream.tv/channel/iss-hdev-payload |
No antennae radiate all the power fed to them!
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No antennae radiate all the power fed to them!
rickman wrote in :
Sort of like wrestling a pig. You get all dirty and the pig enjoys it. That's the one I was trying to remember last week. :) |
No antennae radiate all the power fed to them!
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No antennae radiate all the power fed to them!
On 11/2/2014 5:45 AM, Lostgallifreyan wrote:
rickman wrote in : I believe there are rather cold temperatures in space. A superconducting antenna could be used there with *no* supporting "apparatus". There's still such a thing as radiation resistance, I think, so it wouldn't stay cold even there. Given the size of a body, there's a limit to how fast it can get rid of heat at a given temperature.. I don't know the proper terminology for it though. Anyway, at low tenperature, the rate it can radiate heat is low, so it will quickly warm up out of low-temp superconducting state. Lol, radiation resistance is from the signal energy *leaving* the antenna. It does not show up as heat! You need to read up on the temperatures involved. Space is near absolute zero. The Sun warms things in the solar system, but before reaching Uranus even that heat drops to the point of N2 liquifying, 77 °K, still more than 70 °K above the temperature of space. So heat can still leave liquid nitrogen easily and allow it to freeze at 63 °K at one atmosphere. -- Rick |
No antennae radiate all the power fed to them!
|
No antennae radiate all the power fed to them!
rickman wrote in :
You are aware that a standing wave still moves up and down, no? So a trough turns into a crest and vice versa. I've seen waves on water in a tank that don;t. You can see them in the laminar flow froma tap set low, as the stream hits the ceramic. Totally static... About the other thing, I put it badly, but imaguine a tank brim-full. Now imagine a static half-wave, convex, supported by the sides with walls extended up from the tank (I didn't mention that before, stupidly). Now I'm not even sure that ONE halfwave can be static, convex, maybe it can only be stable concave due to gravity. I really don't know. I was just thining that if statiuc convex IS possible, then once set up, the edns of the takk have water reaching them below the brim, ergo you could chuck a bit more water in to top it up. :) Hence storage. Same (likely dubuious) logic as a flyhweel, in that to store extra anagery you can either rasie speed for fixed mass, or raise mass for fixed speed. If it's recirpocal, then an ability to add mass to that tank seemed to indicate storage capability being raised. There may well be a flaw in all that, but I'm expressing it as best I can. |
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