Scientific methodThe scientific method is an empirical method for acquiring knowledge that has characterized the development of science since at least the 17th century (with notable practitioners in previous centuries; see the article history of scientific method for additional detail.) It involves careful observation, applying rigorous skepticism about what is observed, given that cognitive assumptions can distort how one interprets the observation.
Perovskite solar cellA perovskite solar cell (PSC) is a type of solar cell that includes a perovskite-structured compound, most commonly a hybrid organic–inorganic lead or tin halide-based material as the light-harvesting active layer. Perovskite materials, such as methylammonium lead halides and all-inorganic cesium lead halide, are cheap to produce and simple to manufacture. Solar-cell efficiencies of laboratory-scale devices using these materials have increased from 3.8% in 2009 to 25.
Mixed boundary conditionIn mathematics, a mixed boundary condition for a partial differential equation defines a boundary value problem in which the solution of the given equation is required to satisfy different boundary conditions on disjoint parts of the boundary of the domain where the condition is stated. Precisely, in a mixed boundary value problem, the solution is required to satisfy a Dirichlet or a Neumann boundary condition in a mutually exclusive way on disjoint parts of the boundary.
Automotive air conditioningAutomotive air conditioning systems use air conditioning to cool the air in a vehicle. A company in New York City in the United States first offered the installation of air conditioning for cars in 1933. Most of their customers operated limousines and luxury cars. On 7 October 1935, Ralph Peo of Houde Engineering, Buffalo, New York, applied for a patent for an "Air Cooling Unit for Automobiles". , was granted on 16 November 1937. In 1939, Packard became the first automobile manufacturer to offer an optional air conditioning unit in its 1940 model year cars.
