Paulo Ribeiro de Arruda, Brazilian electrical engineer (Itapetininga, São Paulo State 30 May 1909 – São Paulo 22 November 1985)

Developed an absolute method for determination of frequencies in radio electrical spectrum at his doctoral thesis (1939)

Authored Sobre um acessório electromecânico para o oscilógrafo de raios catódicos (1948)

Discovered a new type of motion that named caterpillar type

Introduced new improvements to electron microscope

Developed a number of devices that were not patented

PATENTS

Polyanalyzer, an electromechanical device that enables the observation and simultaneous record of many periodic signs or phenomena on the screen of a single oscillograph  

Microtome for ultra-thin sections employing caterpillar type motion (1959) 

Remote control of micro dislocation by means of caterpillar type motion

Automat employing  caterpillar type motion

A system of grains purge using thermal process (number 957.350) with engineer Lauro Vianna Bacellar