Ballon Generali diameter of . It has been used as advertising billboard for Fortis, then from 2002 for Eutelsat. In 2008, a partnership has been signed with Banque populaire and Airparif : renamed "ballon Air de Paris", its internal illumination system changes the outer colour in real-time, according to the ambient air pollution in Paris, measured by Airparif : from green (good) to red (bad) through orange (poor). This system was completed by an independent lighting (panels light-emitting diode, visible especially at night on the lower part of the shell) stating the air quality near traffic with the same colour code. On
P–n diode P–n diode This article provides a more detailed explanation of p–n diode behavior than that found in the articles p–n junction or diode. A p–n diode is a type of semiconductor diode based upon the p–n junction. The diode conducts current in only one direction, and it is made by joining a "p"-type semiconducting layer to an "n"-type semiconducting layer. Semiconductor diodes have multiple uses including rectification of alternating current to direct current, detection of radio signals, emitting light and detecting light. The figure shows two of the many possible structures used for "p–n" semiconductor diodes, both adapted to increase