Engineering and technology notes

Octave function reference: butter filter

Jovan Stosic November 3, 2019 
 sf = 800; sf2 = sf/2;
 data=[[1;zeros(sf-1,1)],sinetone(25,sf,1,1),sinetone(50,sf,1,1),sinetone(100,sf,1,1)];
 [b,a]=butter ( 1, 50 / sf2 );
 filtered = filter(b,a,data);

 clf
 subplot ( columns ( filtered ), 1, 1)
 plot(filtered(:,1),";Impulse response;")
 subplot ( columns ( filtered ), 1, 2 )
 plot(filtered(:,2),";25Hz response;")
 subplot ( columns ( filtered ), 1, 3 )
 plot(filtered(:,3),";50Hz response;")
 subplot ( columns ( filtered ), 1, 4 )
 plot(filtered(:,4),";100Hz response;")

Source: Function Reference: butter

SymPy

Jovan Stosic October 26, 2019

SymPy is a Python library for symbolic computation. It provides computer algebra capabilities either as a standalone application, as a library to other applications, or live on the web as SymPy Live or SymPy Gamma. SymPy is simple to install and to inspect because it is written entirely in Python with few dependencies.[2][3][4] This ease of access combined with a simple and extensible code base in a well known language make SymPy a computer algebra system with a relatively low barrier to entry.

SymPy includes features ranging from basic symbolic arithmetic to calculus, algebra, discrete mathematics and quantum physics. It is capable of formatting the result of the computations as LaTeX code.[2][3]

SymPy is free software and is licensed under New BSD License. The lead developers are Ondřej Čertík and Aaron Meurer.

Source: SymPy – Wikipedia

Edward Elgar

Jovan Stosic October 23, 2019

Sir Edward William Elgar, 1st Baronet OM GCVO (/ˈɛlɡɑːr/; 2 June 1857 – 23 February 1934) was an English composer, many of whose works have entered the British and international classical concert repertoire. Among his best-known compositions are orchestral works including the Enigma Variations, the Pomp and Circumstance Marches, concertos for violin and cello, and two symphonies. He also composed choral works, including The Dream of Gerontius, chamber music and songs. He was appointed Master of the King’s Musick in 1924.

https://en.wikipedia.org/wiki/Edward_Elgar

Montgolfier brothers

Jovan Stosic October 20, 2019

Joseph-Michel Montgolfier (26 August 1740 – 26 June 1810) and Jacques-Étienne Montgolfier (6 January 1745 – 2 August 1799) were paper manufacturers from Annonay, in Ardèche, France best known as inventors of the Montgolfière-style hot air balloon, globe aérostatique. They launched the first piloted ascent, carrying Étienne. Joseph Michel also invented the self-acting hydraulic ram (1796), Jacques Étienne founded the first paper-making vocational school and the brothers invented a process to manufacture transparent paper.

https://en.wikipedia.org/wiki/Montgolfier_brothers

Charles Goodyear

Jovan Stosic October 19, 2019

Charles Goodyear (December 29, 1800 – July 1, 1860) was an American self-taught chemist and manufacturing engineer who developed vulcanized rubber, for which he received patent number 3633 from the United States Patent Office on June 15, 1844.

Goodyear is credited with inventing the chemical process to create and manufacture pliable, waterproof, moldable rubber.

Goodyear’s discovery of the vulcanization process followed five years of searching for a more stable rubber and stumbling upon the effectiveness of heating after Thomas Hancock.[5] His discovery initiated decades of successful rubber manufacturing in the Lower Naugatuck Valley in Connecticut, as rubber was adopted to multiple applications, including footwear and tires. The Goodyear Tire and Rubber Company is named after him.

https://en.wikipedia.org/wiki/Charles_Goodyear