SpacemanSpiff

"all useful things no doubt, but things you don't change on a per-folder basis that often- while literally not having an "up one level" button. At all."

Add the "path" menu to your Finder window toolbar. You now have access to all parent folders of the current directory in two clicks. It's one of the first tweaks I make setting up a new OSX install. Along with dumping "all my files" from the sidebar and as the new window default.

After using Ubuntu for most of the summer don't get me started on the UI inconsistencies I experienced there. I don't disagree with you that there are things in OSX which also don't make sense, by my overall impression is that the UI of OSX is much more refined than what's available for Linux out of the box. YMMV.

Excellent project, but the shading on the solar panels from the railings is more than likely severely reducing the output of the panels at lower sun angles. Even shading a single cell on a series connected panel effectively reduces the output of ALL cells. Also having peak power tracking would increase panel utilization. I really like the power monitoring using the Arduino though.

from the linked Wikipedia article: The neat coincidence that 2^10 is nearly equal to 10^3 provides the basis of a technique of estimating larger powers of 2 in decimal notation. Using 2^10a+b ≈ 2b10^3a is fairly accurate for exponents up to about 100. For exponents up to 300, 3a continues to be a good estimate of the number of digits.

For example, 2^53 ≈ 8×10^15. The actual value is closer to 9×10^15.

I've encountered malware where the computer being used to administer the site was compromised, and the malicious code was injected periodically this way. So make sure your personal computer, as well as the computers of anyone with write access to the site is clean. Good luck.

yeah, I caught that irony too. College professors, lol. I do admire the guy for the large amount of effort he put into the presentation though. I mean he disassembled and re-assembled parts of a watch in front of the class, not to mention the slides and models. Pretty sweet.

great video, thanks for posting!

Agreed. I've done all kinds of accidental abuse to AVRs, shorting outputs while testing, powering an entire circuit through the USART pins, switching the PDI connector on an XMEGA (3.3V) with a +5V USB connector, that sort of thing. They seem to be quite resilient. A classmate of mine apparently had a 5V AVR powered by +12V for quite some time in one of his projects when the voltage regulator silently failed. Apparently it operated for several days like this. My favorite discussion about the resilience of the AVR comes from 26C3 "Advanced Microcontroller Programming", available here on youtube: http://www.youtube.com/watch?feature=player_detailpage&v... "You can zap 15kV spikes into the clock inputs and it will continue to run..."

Here's a nice discussion about Switched Reluctance Motors courtesy of TI (and control thereof): http://www.ti.com/lit/an/spra420a/spra420a.pdf

So assuming we're talking about a synchronous machine aka permanent magnet AC motor, the control of whether the motor acts as a generator or motor is inherent in the physics of the machine. Inside the motor are polyphase AC windings which with the help of an inverter create a rotating electromagnetic field (usually the stator). The rotor position is sensed, and thus the control system can vary the angle between the electromagnetic field and magnets in the rotor. This angle is called the torque angle, and if it it is leading the rotor ("pulling it along") then the machine produces torque. If some external force accelerates the rotor (or if the control changes the phase angle) then the rotor is lagging ("pushing against the magnetic field") then the torque is converted into output current. Practically this means that a synchronous motor spinning at a particular speed (again set by the AC inverter) will consume power if it is under load and produce electric power if externally driven. The AC inverter is designed such that power can flow in either direction. When supplying power to the motor it acts as an inverter, when the motor is supplying power it acts as a rectifier. So basically the control just needs to change the phase angle to control whether the motor produces torque or acts as a generator.

I assume that the operation of the switched reluctance motor covered in the article is similar.

I second AP Circuits. I've been using them for prototypes for about 5 years now and am very happy with their work.

The 555 design contest winners (from 4/2011): http://www.555contest.com/2011/04/the-555-contest-winners-an...

I especially like the adding machine made from 102 555s: http://www.vk2zay.net/article/258

Nice. Thanks for pointing this out.

I checked out the video you linked. It's now all of a sudden marked Private for some reason... Is there any corroboration from SpaceX that there was indeed an engine failure? It looked to me like it could have been ice breaking off near max Q or some kind of shockwave interacting with the exhaust plume. I'm not questioning your observation but it didn't look definitive to me. I agree that having redundancy is good though.

I just emailed the author of the article (Seth Stevenson) to see if he would let the mapmaker know about his map being mentioned on Hacker News. Maybe we can get some contact info for those of us interested in purchasing the map. I know I would be interested in one.

my favorite part of the article:

Algorhyme

        I think that I shall never see
        a graph more lovely than a tree.
        A tree whose crucial property
        is loop-free connectivity.
        A tree that must be sure to span
        so packet can reach every LAN.
        First, the root must be selected.
        By ID, it is elected.
        Least-cost paths from root are traced.
        In the tree, these paths are placed.
        A mesh is made by folks like me,
        then bridges find a spanning tree.

                         Radia Perlman

Agreed. Permanent magnet synchronous motors are just one kind of traction motor. There are alternatives out there that don't require rare earth magnets. See this nice table: http://en.wikipedia.org/wiki/Electric_motor#Categorization

cessna_172 Fixed-wing_aircraft Aircraft Vehicles Bicycle Human-powered_transport Transport Cargo Commerce Buying San_Juan_de_Dios_Market Guadalajara,_Jalisco States_of_Mexico Mexico Spanish_language Romance_languages Indo-European_languages Language_family Language Human Precambrian Eon_(geology) Chronology Time Measurement Magnitude_(mathematics) Property_(philosophy) Modern_philosophy Philosophy 28 steps to philosophy

Wow, the components on the GPS board look like they are hand soldered, which to me means very low volume/specialized production.

Czech

I wonder if this phenomena is at all related to red sprites and blue jets http://en.wikipedia.org/wiki/Blue_Jets

from the article:

Writing to random locations in system memory isn't generally a wise design practice. Unsurprisingly, the game would generate spectacular crashes as a result. A human player would be driving blind and usually crash right away, limiting the scope of system casualties. The AI opponents had no such weakness. The computer would scan immediately in front, to the left, and to the right of its position to determine if it was about to hit a wall and change directions accordingly. So as far as the computer was concerned, system memory looked no different than screen memory. As Marco described it,

We can only speculate what it started doing once it left screen memory, since it obviously would look to find a way to continue going in a direction that was occupied by 0’s. If it became blocked and ran into a “wall” of numbers, it would die. In those spectacular crashes though, it would sometimes be running around very much “alive” until at some point it either overwrote some code being executed with a trail that didn’t make sense, or it would access some memory mapped device that would then cause a crash. But it wasn’t immediate – the AI ran around for a little while out there before it crashed the system.

-- Wow, thanks for this - the imagery here is great.

awesome, I look forward to trying it out.

"If I had asked my customers what they wanted, they would have said a faster horse." Attributed to Henry Ford

Alternately for the $20,000 he could get an old cessna 172, learn how to maintain it and get his A&P mechanic license and have a safe and reliable way to fly during nice weather. Still would need an "airport car" to get to work from the airport though.

Check out the Terrafugia: http://www.terrafugia.com/aircraft.html I am skeptical as you are about the possibility of a practical flying car, but I've been watching this one for a couple of years and it seems on the right track. It'll be an LSA (Light Sport Aircraft) which makes pilot certification and maintenance simpler and cheaper. It would still have to be landed at an airport, but I think it's pretty neat nevertheless.

from the article: "Besides the electromagnetic fields created by mobile-phone networks and wireless LANs, ultrafine particles emitted by cars and trucks may also be to blame. These particles are so small they are able to enter the organisms."

I think particle pollution is a much more plausible answer because the radiated power emitted by WiFi and cell phones is so minuscule.

Ensign Robin Lefler I think: http://www.startrek.com/database_article/lefler-ensign-robin

I remember a college "introduction to economics" class where the professor asserted that in this new technological age, the typical economic cycles of growth and recession were obsolete; that from here on out it was just growth growth growth. This was in 1999.

Except in this case the "business card" emulates a USB HID keyboard. No autorun, no file storage. Although the HID device could send some malicious keystrokes I suppose.