Radio-frequency engineeringRadio-frequency (RF) engineering is a subset of electronic engineering involving the application of transmission line, waveguide, antenna and electromagnetic field principles to the design and application of devices that produce or use signals within the radio band, the frequency range of about 20 kHz up to 300 GHz. It is incorporated into almost everything that transmits or receives a radio wave, which includes, but is not limited to, mobile phones, radios, WiFi, and two-way radios.
Heat pumpA heat pump is a device that uses work to transfer heat from a cool space to a warm space by transferring thermal energy using a refrigeration cycle, cooling the cool space and warming the warm space. In cold weather a heat pump can move heat from the cool outdoors to warm a house; the pump may also be designed to move heat from the house to the warmer outdoors in warm weather. As they transfer heat rather than generating heat, they are more energy-efficient than other ways of heating a home.
List of concentration and internment campsThis is a list of internment and concentration camps, organized by country. In general, a camp or group of camps is designated to the country whose government was responsible for the establishment and/or operation of the camp regardless of the camp's location, but this principle can be, or it can appear to be, departed from in such cases as where a country's borders or name has changed or it was occupied by a foreign power. Certain types of camps are excluded from this list, particularly refugee camps operated or endorsed by the United Nations High Commissioner for Refugees.
Adolf Hitler's rise to powerAdolf Hitler's rise to power began in the newly established Weimar Republic in September 1919 when Hitler joined the Deutsche Arbeiterpartei (DAP; German Workers' Party). He rose to a place of prominence in the early years of the party. Being one of its best speakers, he was made the party leader after he threatened to otherwise leave. In 1920, the DAP renamed itself to the Nationalsozialistische Deutsche Arbeiterpartei – NSDAP (National Socialist German Workers' Party, commonly known as the Nazi Party).
