Â­TÂ­here are many different ways to create a motion sensor. For example: 1  It is common for stores to have a beam of light crossing the room near the door, and a photosensor on the other side of the Â­room. 2  When a customer breaks the beam, the photosensor detects the change in the amount of light and rings a bell.
Definition of weir. 1  1 : a fence or enclosure set in a waterway for taking fish. 2  2 : a dam in a stream or river to raise the water level or divert its flow.
Industrial Effluent Guidelines. Effluent Guidelines are national standards for industrial wastewater discharges to surface waters and publicly owned treatment works (municipal sewage treatment plants). We issue Effluent Guidelines for categories of existing sources and new sources under Title III of the Clean Water Act.