The SONARMAN (from gidro... And soundman), studies features of distribution, reflectance and decay of sound waves in a substantial aqueous medium - seas, oceans, lakes, etc. - basically for the purposes of a submerged detection and ranging, communication, etc.

HYDROBIOLOGY (from gidro... And biology), science about the organisms dwelling in an aqueous medium, their relations one another and with conditions of a habitation, about a biological effeciency of oceans, seas and inland waters.

HYDROBORATING, apposition of diborane Â2Í6 or his derivative to unsaturated compounds. It is widely used in organic synthesis for introduction in molecules of functional groups, obtaining of optically active substances, etc.

HYDROGENERATOR (from gidro... And the generator), the synchronous generator spun by the hydraulic turbine. The rotor of a hydrogenerator is reinforced on one (routinely vertical) to the bank with the driving wheel of the turbine. Power of a hydrogenerator up to 700 MVt and more.

HYDROGENATION, the same, that hydrogenation.

HYDROGEOLOGICAL MAPS, map conditions of burial and distribution of underground waters; contain data about quality and productivity of water-bearing horizons, a rule of the ancient base of the hydrostatic pressure systems, etc.

HYDROGEOLOGY (from gidro... And geology), science about underground waters; studies their structure, properties, an origin, regularities of distribution and motion, and also interaction with rocks. The becoming of hydrogeology concerns to 2-nd floor. 19 century.

The HYDROGEOCHEMISTRY, section of hydrogeology, studies chemical composition of a hydrosphere and geochemical processes weeping in her (formation of chemical composition of underground waters and regularities of migration in them of chemical elements).

HYDROGRAPH (from gidro... And... Columns), the schedule of a time history of a discharge of water in a transit of the river (channel). Reflects character of distribution of an aqueous runoff during year, a season, a flood (high water), a low-water.

HYDROGRAPHIC NETWORK, set of the rivers, lakes, bogs, channels, water reservoirs within the limits of any terrains. It is defined by quotient of density of a fluvial net, ozernosti and logginesses; when consider only system of channels, apply the term "fluvial net".

The HYDROGRAPHIC SERVICE, executes navigatsionno-hydrographic maintenance of marine, marine and river fleet. Compounds and emits navigational charts, locies, tide tables, etc., establishes aid to navigation (beacons, signal lights, protective marks, etc.), notifies seafarers on changes of a mode of float.

The SURVEYING VESSEL, intended for measurements of depths, filming of a foreshore, etc. on seas, the rivers, lakes.

HYDROGRAPHIC STEERING Main, scientific - administrative agency in Russia. It is based in 1827 (up to 1885 - Steering of a general - hydrograph) at the Marine ministry. Conducted hydrographic, meteorological activities. From 1972 functions of Hydrographic steering executes Headquarters of navigation and oceanography of the Ministry of Defence of the USSR; with 1992 - the Ministries of Defence of the Russian Federation.

HYDROGRAPHY (from gidro... And... grafija), 1) the section of land hydrology dedicated the description of the rivers, lakes, water reservoirs and their separate parts with quality and the quantity indicator of their rule, physiographic conditions, a mode and use. 2) the Science investigator shipping lines, forms a box of oceans, seas, lakes, water reservoirs, the rivers, channels and developing ways of improvement of navigable waters.

HYDRAULIC ENGINE, the same, that a hydraulic motor.

HYDRODYNAMICS (from gidro... And dynamics), section of hydromechanics, studies motion of liquids and their influence on solids streamlined by them. Theoretical methods of hydrodynamics are based on the solution of the precise or approximated equations circumscribing the physical phenomena in driving liquid or gas. In experimental hydrodynamics originating problems are investigated on the models streamlined by a liquid or gas, thus conditions of a similarity of the theory should be respected. Outcomes of hydrodynamics use at designing the ships, airplanes, missiles, etc.

HYDRODYNAMICS the INSTITUTE of a name of M.A.Lavrentjeva of the Siberian branch of the Russian Academy of Science, is organized in 1957 in Novosibirsk. Probes on mechanics of a viscous fluid and gas, mechanical properties of solids and polymers; development of a pulse technique.

HYDRODYNAMIC TRANSMISSION, the hydraulic transmission consisting of paddle wheels with a general working cavity in which the twisting moment is transmitted from one sprocket other at the expense of change of a moment of momentum of working fluid. Hydraulic clutches concern to a hydrodynamic transmission and hydraulic torque converters.

HYDRODYNAMIC BORING, destruction of rocks in a bottom of a well a high-head flush.

HYDRODYNAMIC DRAG FORCE, the force originating at motion of a body in a liquid or incompressible gas, and also at flow of a liquid or gas in the channel.