Wayne and Layne

Nomogram

A nomogram, nomograph, or abac is a graphical calculating device, a two-dimensional diagram designed to allow the approximate graphical computation of a function: it uses a coordinate system other than Cartesian coordinates. Defining alternatively, a nomogram is a two-dimensionally plotted function with n parameter, from which, knowing n-1 parameters, the unknown one can be read, or fixing some parameters, the relationship between the unfixed ones can be studied.

A Smith Chart is a type of nomogram

Like a slide rule, it is a graphical analog computation device; and, like the slide rule, its accuracy is limited by the precision with which physical markings can be drawn, reproduced, viewed, and aligned. Most nomograms are used in applications where an approximate answer is appropriate and useful. Otherwise, the nomogram may be used to check an answer obtained from an exact calculation method.

The slide rule is intended to be a general-purpose device. Nomograms are usually designed to perform a specific calculation, with tables of values effectively built in to the construction of the scales.

via Nomogram – Wikipedia, the free encyclopedia.

Caterpillar Club

The Caterpillar Club is an informal association of people who have successfully used a parachute to bail out of a disabled aircraft. After authentication by the parachute maker, applicants receive a membership certificate and a distinctive lapel pin.

Before April 28, 1919, there was no way for a pilot to jump out of a plane and then to deploy a parachute. Parachutes were stored in a canister attached to the aircraft, and if the plane was spinning, the parachute could not deploy. Leslie Irvin developed a parachute that the pilot could deploy at will from a back-pack using a rip-cord. He joined the Army Air Service parachute research team, and in April 1919, he successfully tested his design, though he broke his ankle during the test. Irvin was the first person to make a premeditated free fall jump from an airplane. He went on to form the Irving Airchute Company which later became Irvin Aerospace. An early brochure of the Irvin Parachute Company credits William O’Connor 24 August 1920 at McCook Field near Dayton, Ohio as the first person to be saved by an Irvin parachute, but this feat was unrecognised. On 20 October 1922, Lieutenant Harold R. Harris, chief of the McCook Field Flying Station, jumped from a disabled Loening W-2A monoplane fighter. Shortly after, two reporters from the Dayton Herald, realising that there would be more jumps in future, suggested that a club should be formed. “Caterpillar Club” was suggested because the parachute canopy was made of silk, and because caterpillars have to climb out of their cocoons and fly away. Harris became the first member, and from that time forward any person who jumped from a disabled aircraft with a parachute became a member of the Caterpillar Club. Other famous members include General James Doolittle, Charles Lindbergh and retired astronaut John Glenn.In 1922, Leslie Irvin agreed to give a gold pin to every person whose life was saved by one of his parachutes. By 1945, the number of members with the Irvin pins had grown to over 34,000. In addition to the Irvin Air Chute Company formerly Irvin Aerospace – now a brand of Airborne Systems, other parachute manufacturers have also issued caterpillar pins for successful jumps. Airborne Systems Canada formerly Irvin Aerospace Canada still provides pins to people who made their jump long ago and are just now applying for membership. Another of these is Switlik Parachute Company, which though it no longer makes parachutes, still issues pins.

via Caterpillar Club – Wikipedia, the free encyclopedia.

Centennial Light

The Centennial Light is the world’s longest-lasting light bulb. It is at 4550 East Avenue, Livermore, California, and maintained by the Livermore-Pleasanton Fire Department. The fire department claims that the bulb is at least 109 years old and has been turned off only a handful of times. Due to its longevity, the bulb has been noted by The Guinness Book of World Records, Ripley’s Believe It or Not!, and General Electric.

via Centennial Light – Wikipedia, the free encyclopedia.

Westinghouse Sign

The Westinghouse Sign was a large, animated, electric sign advertising the Westinghouse Electric company and located in Pittsburgh, Pennsylvania, U.S.A. The sign was best known for the huge number of combinations in which its individual elements could be illuminated. The sign was removed in 1998 when the building on which it was mounted was demolished to make way for the construction of PNC Park.

The various corporations which have carried the Westinghouse name have erected countless signs and other promotional devices during the past 140 years, including many in the corporate hometown of Pittsburgh. A cubic Westinghouse sign stood in downtown Pittsburgh for approximately thirty five years and was so familiar that it was allowed to remain in place until 2002, even after the building it marked the Westinghouse Tower was no longer owned or occupied by Westinghouse.

via Westinghouse Sign – Wikipedia, the free encyclopedia.

Change in daylight per day

Spring is rapidly approaching, or already here, depending on where you live. Every year it always seems to me that the length of daylight increases a little bit day by day, and then suddenly, one day, it’s light until 7:00 PM! I wanted to see if this was just a perceptual effect, or if there was an actual increase in the amount of daylight change per day.

I obtained a table of sunrise and sunset times from the US Naval Meteorology and Oceanography Command, and plotted the data in Gnumeric.

Daylight in Pittsburgh, PA

The pink and yellow lines show the sunrise and sunset times in minutes after midnight. The teal line shows their difference, the total sunlight per day in minutes. The dark blue plot shows the change in minutes of daylight, the first derivative of daylight. We see that during the spring, the change in daylight increases, slows, reaches zero at the summer solstice, and then descends into negative numbers for the fall. Very interesting.

Convert M4A into MP3 with GNU/Linux, recursive and multithreaded

On a similar thread as an old post, Convert M4A into MP3 with GNU/Linux, I needed to convert a bunch of iTunes M4A unprotected audio files into standard MP3 files. With iTunes’ fondness for sorting by artist first, then by album, I ended up with a ton of single-file folders, making any scripting a bit of a pain. Also, converting a bunch of M4A files to MP3 is something that should be done in parallel on a multi-core CPU.

Here’s a snippet using find and xargs‘ multi-threading support to recursively find all M4A files and convert them to MP3 with as many threads as you want.

First, here’s the convm4a script that is called from the find/xargs line. Call it with a single argument, the location of an M4A file. The script with change to that directory and convert the file to a similarly-named MP3 file. Put this somewhere on your PATH (possibly in ~/bin/) and be sure to chmod +x convm4a.
#!/bin/bash
DIRNAME=`dirname "$1"`
FILENAME=`basename "$1" .m4a`
#echo "$DIRNAME"
cd "$DIRNAME"
faad -o - "${FILENAME}.m4a" | lame - "${FILENAME}.mp3" &> /dev/null

Test out that script to make sure it works. Then, run this line from the top of the directory full of your M4A files:

find -name '*\.m4a' -type f -print0 | xargs -P 4 -n 1 -0 convm4a

The -P 4 means to use four concurrent executions of convm4a, and the -n 1 means to only pass one argument to each invocation of convm4a. Change the number 4 to reflect the number of threads you want to run. You probably don’t want to exceed the number of CPU cores in your computer.