- Sektör: Government
- Number of terms: 5261
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The United States Army Corps of Engineers is a federal agency with a mission to provide vital public engineering services in peace and war to strengthen the nation's security, energize the economy, and reduce risks from disasters. It is also a major U.S. Army organization employing some 38,000 ...
Calculating an age in years for geologic materials by measuring the presence of a short-life radioactive element (e.g., carbon-14) or a long-life element (e.g., potassium-40/argon-40). The term applies to all methods of age determination based on nuclear decay of naturally-occurring radioactive isotopes. Carbon-14 methods are often used to determine the age of peat or wood found in barrier islands.
Industry:Engineering
The state of a tidal current when its velocity is near zero, especially the moment when a reversing current changes direction and its velocity is zero. Sometimes considered the intermediate period between ebb and flood currents during which the velocity of the currents is less than 0.05 meter per second (0.1 knot).
Industry:Engineering
(1) A comparatively high promontory with either a cliff or steep face extending out into a body of water, such as a sea or lake. An unnamed head is usually called a headland. (2) The section of rip current which has widened out seaward of the breakers, also called head of rip. (3) Seaward end of breakwater or dam.
Industry:Engineering
On open seacoasts, a structure extending into a body of water, which is designed to prevent shoaling of a channel by littoral materials and to direct and confine the stream or tidal flow. Jetties are built at the mouths of rivers or tidal inlets to help deepen and stabilize a channel.
Industry:Engineering
The narrow strip of land in immediate contact with the sea, including the zone between high and low water lines. A shore of unconsolidated material is usually called a beach.. Also used in a general sense to mean the coastal area (e.g., to live at the shore). Also sometimes known as the littoral.
Industry:Engineering
(1) The zone bordering a continent extending from the line of permanent immersion to the depth, usually about 100 m to 200 m, where there is a marked or rather steep descent toward the great depths of the ocean. (2) The area under active littoral processes during the holocene period. (3) The region of the oceanic bottom that extends outward from the shoreline with an average slope of less than 1:100, to a line where the gradient begins to exceed 1:40 (the continental slope).
Industry:Engineering
(1) Steel wire-mesh basket to hold stones or crushed rock to protect a bank or bottom from erosion.
(2) Structures composed of masses of rocks, rubble or masonry held tightly together usually by wire mesh so as to form blocks or walls. Sometimes used on heavy erosion areas to retard wave action or as a foundation for breakwaters or jetties.
Industry:Engineering
The periodic rising and falling of the water that results from gravitational attraction of the Moon and Sun and other astronomical bodies acting upon the rotating Earth. Although the accompanying horizontal movement of the water resulting from the same cause is also sometimes called the tide, it is preferable to designate the latter as tidal current, reserving the name tide for the vertical movement.
Industry:Engineering
Waves that occur within a fluid whose density changes with depth, either abruptly at a sharp surface of discontinuity (an interface), or gradually. Their amplitude is greatest at the density discontinuity or, in the case of a gradual density change, somewhere in the interior of the fluid and not at the free upper surface where the surface waves have their maximum amplitude.
Industry:Engineering
A wave with fluid particles that do not revolve around an axis through their centers, although the particles themselves may travel in circular or nearly circular orbits. Irrotational waves may be progressive, standing, oscillatory, or translatory. For example, the Airy, Stokes, cnoidal, and solitary wave theories describe irrotational waves. Compare trochoidal wave.
Industry:Engineering
