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Hypograph of a function. In mathematics, the hypograph or subgraph of a function: is the set of points lying on or below its graph. A related definition is that of such a function's epigraph, which is the set of points on or above the function's graph.
Epigraph of a function A function (in black) is convex if and only if the region above its graph (in green) is a convex set.This region is the function's epigraph. In mathematics, the epigraph or supergraph [1] of a function: [,] valued in the extended real numbers [,] = {} is the set = {(,) : ()} consisting of all points in the Cartesian product lying on or above the function's graph. [2]
A thermic fluid heater (TFH), [1] also known as a thermal oil heater, is a device used for indirect heat transfer through a thermic fluid. It heats the fluid to a desired temperature and then transfers that heat to various processes without any direct contact between the heating source and the product.
Old Saybrook Center is the primary village and a census-designated place (CDP) in the town of Old Saybrook, Middlesex County, Connecticut, United States. The population was 2,278 at the 2020 census, [3] out of 10,481 in the entire town of Old Saybrook. The CDP includes the traditional town center and the peninsula known as Saybrook Point. [4]
A. O. Smith Corporation is an American manufacturer of both residential and commercial water heaters and boilers, and the largest manufacturer and marketer of water heaters in North America. It also supplies water treatment and water purification products in the Asian market. [ 6 ]
An oil heater, also known as an oil-filled heater, oil-filled radiator, or column heater, is a common form of convection heater used in domestic heating. Although filled with oil , it is electrically heated and does not involve burning any oil fuel ; the oil is used as a heat reservoir (buffer).
Direct electric resistance tank water heaters are not included in the Energy Star program; however, the Energy Star program does include electric heat pump units with energy factors of 200% or higher. Tankless gas water heaters (as of 2015) must have an energy factor of 90% or higher for Energy Star qualification.
In 2009, Rheem and Ruud were the first to sell a Hybrid Heat Pump Water Heater, which was more than twice as efficient as similar electric water heaters. [25] Also in the same year, Rheem and Ruud central air conditioners were reported to have the fewest percentage of units requiring repair among all major HVAC brands according to Consumer Reports.