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NASA

NASA Could Explore Titan With Squishable 'Super Ball Bot' 59

An anonymous reader writes "IEEE Spectrum reports on a rover design being developed at NASA Ames Research Center: Super Ball Bot. The premise is that the rover's brain and scientific equipment would be suspended in the center of a structure made of rigid rods and elastic cables. The rods and cables would be deformable, allowing the rover to roll over complex terrain without damage. This design would be ideal for exploring a place like Saturn's moon Titan. Its atmosphere is thick enough that a probe could drop the rover from 100km above the surface, and it would survive the fall without a parachute. 'In a scenario studied by the team (PDF), the robot could be collapsed to a very compact configuration for launch. Once it reaches the moon, it would pop open and drop to the surface, flexing and absorbing the force of impact. By shortening and lengthening the cables that connect its rigid components, the ball bot could then roll about the surface. These same cables could be used to pull back parts of the robot, so that science instruments at the center could be exposed and used.'"

Comment Good, more for me.... (Score 4, Interesting) 89

Have tried all of DFH's "Ancient Ales" (except the Kvasir which hasn't showed up locally yet), and they were all interesting and surprisingly drinkable. Their "Theobroma", a cacao-based beer based on a Honduran recipe is one of their best products.

Dogfish beers aren't for everyone. But their slogan "Off-Centered Ales for Off-Centered people" should explain that...

Comment I'll see your 6900, and raise you a 7AK7... (Score 1) 165

, which was arguably the very first electronic component specifically designed for use in computers. Most of the magic was in the ultra high purity nickel used in the cathode sleeve, to prevent interface formation and "sleeping sickness", which would result from even the slightest trace of silicon impurity in the nickel.

http://www.radiomuseum.org/tubes/tube_7ak7.html

Every electronics geek needs one of these on their desk. Fortunately, there were millions made, and they come up on eBay cheap, as they have no value to the audiophools....

Comment Mass tube swapping ignores the "bathtub curve"... (Score 1) 165

This was a major lesson that was learned during the early tube computer era. The best approach was NOT simply swapping out tubes after so many hours "to prevent in-service failures", but periodically running diagnostics checking pulse levels, etc.to identify tubes that were actually starting to slump off.

The failure rate vs life curve for most components (tubes included) has a high initial failure rate (so-called "infant mortality"), followed by a long period of low failure rates, which eventually trends upward at an increasing rate at end-of life. This produces a curve with a flat bottom and 2 peaks at the ends, like a cross-section of a bathtub.

By swapping out tubes before they hit the end of life, you push the entire tube complement in the equipment over toward the "infant mortality" end of the curve, actually INCREASING the failure rate over careful monitoring and replacing only those tubes that are actually starting to fail. All that tube swapping also results in increased failures through the increased handling of the glass tubes (breakage and seal leaks), wear on the sockets from pulling and inserting tubes, etc. The highest equipment uptime was achieved by not actually replacing tubes on a fixed schedule, but by overall system checks to identify and replace individual failing tubes BEFORE they progressed to the point of total failure.

Experience with electronic installations containing tens of thousands of tubes produced a huge amount of statistical data on component reliability, laying the foundations for modern reliability models and MTBF calculations.

A good read from 1960, when all this was being figured out is "Getting the Most out of Vacuum Tubes" by Bud Tomer, available on Archive.org:

https://archive.org/details/GettingTheMostOutOfVacuumTubes_105

Build

Interview: Ask Forrest Mims About Rockets, Electronics, and Engineering 120

With his popular Getting Started in Electronics, and Engineer's Mini-Notebook series and a number of different electronics kits sold at Radio Shack, Forrest Mims inspired countless scientists and engineers. Even though he received no formal academic training in science, Forrest has appeared in 70 magazines and scientific journals. He has worked as a consultant for the National Geographic Society, the National Science Teachers Association, and NASA’s Goddard Space Flight Center. Today, Mims works on many scientific projects including climate change research. He's agreed to answer all your questions about science and engineering. As usual, ask as many as you'd like, but please, one question per post.

Comment Filaments are generally under-run, as well... (Score 1) 1146

A typical "rough service" incandescent lamp intended for use on 120V contains a filament actually designed for normal light output at 130V. By underheating the filament, the filament retains more strength when lit, and is better able to handle shock and vibration in hand-held worklights, etc.

This negatively impacts efficiency, though.

Comment Re:Various applications in electrical equipment??? (Score 1) 216

Sold by 3M under the trade name "Fluorinert FC-43". Used primarily as a heat transfer fluid in exotic electronics.

The best known application to Slashdotters would be the Cray 2 supercomputer, which used a fluorinert "waterfall" to remove waste heat from the densely packed electronics. Some overclockers use it on high performance gaming rigs and the like, with the entire motherboard submerged in a bath of the stuff.

Because of the very high dielectric strength and low RF loss, it was used as a cooling medium in military radar gear, particularly airborne stuff.

Comment Not exactly a great idea for a legal defense... (Score 1) 670

Once you talk about making extracts (hash, hash oil, etc.) from your pound of weed, you move from "possession with intent to distribute", to "manufacturing of a controlled substance", the same charge that running a meth lab would get you.

Since you are now manufacturing, and not simply presumed to be selling, you move to the top of the food chain, and will make a great trophy for some ambitious narco-swine.

Comment I have 3 'scopes in the home lab at the moment.. (Score 1) 215

From newest to oldest:

Rigol DS1052E--A "cheap and cheerful" Chinese import 50 MHz 2 channel DSO. A good general hobby scope, easily upgradeable to 100MHz bandwidth with a simple reflash of the firmware. Has a sizable following in the hardware hacker community because of the high "bang for the buck" factor.

Tektronix 7623: A 3-slot mainframe with 75 MHz bandwidth An 1969 vintage analog storage scope, which accepts various interchangeable plug in units to give a huge range of features. Actually has an on-screen display for V/div and Time/div, which was bleeding edge stuff at the time it was introduced.

Tektronix 453: A 1963 vintage portable field service scope (designed for servicing IBM mainframes). Dual channel, 50 MHz. Built to take constant abuse and just keep working. Still a VERY usable scope for general purposes, and has the sharpest brightest trace of any scope I have ever used.

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