Slate industry in Spain keep cutting machinery cool. After quarrying regional authorities often dictate that the landscape is returned as much as possible to its original state, and waste rock left as part of the extraction process is returned adjacent to the quarry Slate industry in Spain 90% of Europes's natural slate used for roofing originates from the slate industry in Spain, with the region of Galicia being the primary source of production. Slate is a fine-grained metamorphic rock that splits into thin, smooth-surfaced layers. Metamorphic rock is rock which was once igneous or sedimentary and has been subsequently subjected to heat and pressure
Change of variables (PDE) Change of variables (PDE) Often a partial differential equation can be reduced to a simpler form with a known solution by a suitable change of variables. The article discusses change of variable for PDEs below in two ways: For example, the following simplified form of the Black–Scholes PDE is reducible to the heat equation by the change of variables: in these steps: Advice on the application of change of variable to PDEs is given by mathematician J. Michael Steele: Suppose that we have a function formula_24 and a change of variables formula_25 such that there exist functions formula_26 such that