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Hi alan2. Enjoy: http://www.sciencenews.org/articles/20020105/fob2.asp Is not a new article, but lately there is very little noise about the technology. Miguel Edit-added: http://www.scirus.com/srsapp/search?q=magnetocaloric+metals&ds=jnl&ds=nom&ds=web&g=s&t=all

OK. A sort of a blender at melting temperature, the size of the wanted batch. In the mentioned alloy example, what trick is needed to prevent the phosphor to stop existing by becoming smoke when gets to ignition temperature way before iron melts? There should be dozens of elements that will refuse to stay 'alive' at high furnace temperatures... how is that controlled ? Simply such alloys are impossible to achieve; or engineering strategies/processes get into play ?

Hi. When a magnetocaloric compound is exposed to a magnetic field it heats up; Until when? For how long ? As long as the field increases? If the material heats up -say 10ºC- ; starts cooling back by radiation/convection/other or maintains:eek: a delta t ? Miguel

If you want an alloy of say iron, manganese, phosphor, and germanium; do you melt them with desired proportions in a very, very hot 'blender' and push the 'on' button for a while ? Or is it more rocket science than that ?

Hi. Too many years ago, a knowledgeable chemist engineer told me that an iron object would hardly rust ever again if treated with caustic soda. What is the treatment? dipping in a solution? media blasting? burying the metal in it? what concentration, or else ? Miguel

Hi all. The basics are simple, the currents produced by dissimilar metals in seawater, the erosion and deposition of material depending on the electronegativity... I see it as a simple galvanic cell, a 'battery', but I have a void somewhere in all this. If an iron barge floats on seawater, and no other metals are part of its hull, will still need (Zn, Al) sacrificial anodes attached ? If an aluminium boat hull has a bronze propeller I can understand the migration of charges and erosion of metals; but what if the hull is only aluminium and no other metals, will it still deteriorate and need protection ? Now, an aluminium hull has good electrical connection with its stainless steel shaft and bronze propeller, as they are all attached to each other... how does the corrosion/electric currrents work there ? If a boat with aluminium hull is 20 metres away from an iron one; will there be electrical / ionic / metal migration / currents in the seawater and between the boats ? Any clear light is welcome. I believe am mixing battery reactions, electrolysis and electroplating... Miguel

You can form your own opinions... http://www.youtube.com/watch?v=_9ak7iiYwVQ http://www.fdp.nu/perendev/default.asp

It is in video: http://www.metacafe.com/watch/718152/how_to_turn_water_into_ice_in_seconds/ Thanks.

DrDNA: Precipitation in the sense of some ions being in higher concentration near the bottom of the container. To say it simpler, a solution of a teaspoon of salt in a litre of water, steady temperature, capped, undisturbed for a year. Which ions will sink because of their greater specific weight; Na or Cl ? Miguel

Hi all. In a plain solution of table salt, left for years undisturbed in a closed jar; which ions will be more abundant (precipitate) at the bottom - Cl or Na ? Miguel

Thanks, Rocket and Pioneer. I did not think of those variables; the air pressure to be watched; and the viscosity being lower can result in smaller bubbles. Yes, the smaller the better for my application. Thanks

Am back with my bubbles ; would like opinions on what would happen if very fine air bubbles are released from aquarium type stones under a fluid as viscous as honey. The actual test will happen in a few days as am waiting for some supplies but will apreciate your opinion before. I believe large bubbles would surface and eventually pop, but small ones (smaller than ~1mmØ) would stay trapped at least several hours. The question is; if the supply of bubbles does not stop from the bottom of the container; how will the mix behave; will there be a limit of expansion ? Will tunneling to release the air develop ? I find it hard to visualize. Help please. Miguel

This is not my field of expertise, obviously... I believe boron phosphate dissolves in water ; would it cause the bubbles in soapy water to harden ? Or what would you do to harden bubbles ? Miguel feparetz

Hi. Do not know about your radiotron CRT , but I may be of help. Is there a particular number for such tube? ----> Look trough the glass to the connections of the four pins, the filament should be entering into the center of a small metal tube, and you already identified them as it glows. The other two may be cathode, a connection to the small metal tube. The last may be a grid, there is a chance you can see trough the glass the actual grid of ultrafine wire. Applying 300V instead of the full rated 500V should produce some indication of the tube being functional. I do not know what you mean with PD. Miguel

Checking prices of the stuff, they are absolutely absurd. If a couple of cubic metres are needed, it's bankruptcy, and its only about 30 Kg. of material Can something similar be made in a backyard ?, does not need to be a superb product, just similar to that extremely light white packing material we all know, polyestyrene foam. Miguel

Hi. In many flavors : http://www.helmets.org/fourwhel.htm Miguel

Been there, done that, and it is not always convenient. The oven solution does work, a butane torch on the solder side works, slammi ng the board at the right melting moment; removal by hand works... The best way for me, is to keep the parts as they are on the old boards, and remove the ones as needed. Will not need bins, saves a ton of work done to zillion parts that you will end using perhaps 2%, 90% of parts removed by 'brute heat' will have solder splashes everywhere on them, requiering more cleanup work. And, complete boards provide a bonus, you can saw-off complete operational sections or stages instead of building them. Miguel

Thanks for the responses ------> That I do not know what it is. I will search for it. Miguel:-)

Hmmm... I would need to be smarter to understand the thingy. The camera is a video camera, not a photographic camera, no time stamp in any EXIF, ant time is irrelevant. The video would be captured as individual pictures every certain amount of time triggered depending on the speed being towed to take pictures 'back to back' or properly said, sequential without overlap nor gaps. And every frame has to be saved with its Lat/Long/heading as 'subtitles' to the hard drive, no posterior editing/adding/insertion of any GPS logs onto the frames. The "run a script" does it mean running a program? Made with basic, visual basic, C... ? How to 'tap' to the GPS data entering the computer with such program ? Another data to be superimposed as 'subtitles' to each frame is from a depth sensor. I was a programmer too long ago to remember how to do it now. Miguel

Hi. If I have a global positioning satellite receiver GPS on a laptop USB port, and also a video input fed to the computer; How to stamp latitude, longitude and heading on each video frame recorded in the hard drive as to log images location for a towed submarine camera ? To make it harder; if the camera is towed 100 horizontal metres behind the boat, how to compensate the stamped readings for accuracy at all headings ? Miguel

For ice cubes to stick, their mating surfaces have to be wet, and no need to press them. The only place an ice cube is at 0Cº is at its surface if wet. Inside is below zero, up to waaaay below zero. This is something usually misunderstood. For a while I was daily buying large quantities of ice blocks to preserve seafood, and on a day I decided to ask : "What is the temperature of the ice you sell" ? Many idiots responses at that place was 'zero degrees, of course'. If it was 'zero degrees', it would melt in seconds. Joining ice cubes freeze their wet joining surfaces as the heat at the wet surfaces is quickly drawn by the colder core of the cubes. Miguel

May not the best place to post the subject, sorry, but : I have never lived in a house with a fireplace. Am a total ignorant on all about them. Planning to install a cast iron freestanding one on a vacation home that has a brick chimney with a ~8" duct inlet, and i wonder where does the air needed for combustion comes from ? If from the living space ; windows and doors must not be 'airtight', must allow some air to leak in to supply the burning ? If very cold outside, any supply air entering would work against the desired heating. If airtight, would the fumes flow freely to the chimney ? How does it work? Thanks, Miguel

A sound wave propagates at 340 m/s ; air from a fan across may move at say 3.4 m/s for easy figures. We have 100:1 ratio. A wavefront from a stone thrown on a river may propagate at about 50 cm/s ; for the same ratio of 100:1 would mean the current flowing at 5 mm/s -relatively very slow - With such speeds, is easy to visualize the wave will reach the shore in front of the thrower in good intensity. Perhaps that (ratio) is why the sound does make it across the crosswind. If the river was much, much faster, as 1m/s , the wave would not reach the shore in front of the thrower, but way down the river. (equivalent of sound not being heard) Seems a fast enough air speed would prevent hearing the sound. Just trying to find an explanation. Miguel

Alan - Not here to kick any ass, and less YT's . Am here to learn. Just another point of view perhaps more visualizable than audio and air. If the waves reach the stone thrower's shore, should explain the independence between both medium and wave propagations. YT's question is a good valid one, and electromagnetic waves and mechanical waves do not behave equal. Miguel

A similar case would be Would a stone thrown on a river make waves that will reach the shore anyway even when the current is transporting the water mass down the river?