“delta”的概念、定义、翻译、参考文献-科学参考

delta

Mathematics

The Greek letter d, written δ‎, capital Δ‎. A small increment in the value of the variable x is usually denoted by δ‎x. When y is a function of x, $\frac{δ y}{δ x}$ represents the average rate of change of y with respect to x at a point and the derivative of y with respect to x is defined as the limit of that ratio as δ‎x → 0. So

$y' = \frac{d y}{d x} =_{δ x \to 0}^{lim} \frac{δ y}{δ x} .$

Chemical Engineering

As a capital, it represents the difference between two values such as the difference in pressure between two points, Δp. As a lower case, δ commonly represents a partial derivative used in partial differential calculus.

Geology and Earth Sciences

A discrete protuberance of sediment formed where a sediment-laden current enters an open body of water, at which point there is a reduction in the velocity of the current. This results in rapid deposition of the sediment, which forms a body, for example at the mouth of a river where the river discharges into the sea or a lake. There is a characteristic coarsening upwards of sediments. A river provides the sediments to form a delta; but the shape and nature of a delta is controlled by a variety of factors including climate, water discharge, sediment load, rate of subsidence of the sea or lake floor, and the nature of the river-mouth processes (particularly tidal and wave energy). One classification of delta types, based on variations in transport patterns on the delta, subdivides deltas into three classes: (a) river-dominated, e.g. the Mississippi and Po; (b) wave-dominated, e.g. the Rhône and Nile; (c) tide-dominated, e.g. the Ganges and Mekong. See also gilbert-type delta.
Delta

Geography

A low-lying area at the mouth of a river, formed from alluvial deposition, that occurs as the river’s silt-carrying capacity is checked when it slows in the more tranquil waters of a lake or sea. Deltas develop through the progradation of river mouths and delta shorelines producing a subaerial deltaic plain over the seaward delta-front deposits. See Bellotti et al. (2011) Holocene 21, 1105 for a detailed study of the Tiber delta. Gao (2007) Geomorph. 85, 3–4 thinks that river deltas may be limited when sediment retention approaches zero, when the delta front advances into deep waters, or by the combination of sea-level rise and subsidence.
Inland deltas
form in hot, arid inland drainage areas, where water dynamics and sediment transport are very different, especially deposition associated with expansion–contraction dynamics at the channel head. As a result, the mean slope of the delta decreases with distance from the apex, while in coastal deltas it increases towards; see Seybold et al. (2010) Geophys. Res. Lett. DOI:10.1029/2009GL041605.
Delta shore composition

单词	delta
释义	delta Mathematics The Greek letter d, written δ‎, capital Δ‎. A small increment in the value of the variable x is usually denoted by δ‎x. When y is a function of x, $\frac{δ y}{δ x}$ represents the average rate of change of y with respect to x at a point and the derivative of y with respect to x is defined as the limit of that ratio as δ‎x → 0. So $y' = \frac{d y}{d x} =_{δ x \to 0}^{lim} \frac{δ y}{δ x} .$ Chemical Engineering As a capital, it represents the difference between two values such as the difference in pressure between two points, Δp. As a lower case, δ commonly represents a partial derivative used in partial differential calculus. Geology and Earth Sciences A discrete protuberance of sediment formed where a sediment-laden current enters an open body of water, at which point there is a reduction in the velocity of the current. This results in rapid deposition of the sediment, which forms a body, for example at the mouth of a river where the river discharges into the sea or a lake. There is a characteristic coarsening upwards of sediments. A river provides the sediments to form a delta; but the shape and nature of a delta is controlled by a variety of factors including climate, water discharge, sediment load, rate of subsidence of the sea or lake floor, and the nature of the river-mouth processes (particularly tidal and wave energy). One classification of delta types, based on variations in transport patterns on the delta, subdivides deltas into three classes: (a) river-dominated, e.g. the Mississippi and Po; (b) wave-dominated, e.g. the Rhône and Nile; (c) tide-dominated, e.g. the Ganges and Mekong. See also gilbert-type delta. Delta Geography A low-lying area at the mouth of a river, formed from alluvial deposition, that occurs as the river’s silt-carrying capacity is checked when it slows in the more tranquil waters of a lake or sea. Deltas develop through the progradation of river mouths and delta shorelines producing a subaerial deltaic plain over the seaward delta-front deposits. See Bellotti et al. (2011) Holocene 21, 1105 for a detailed study of the Tiber delta. Gao (2007) Geomorph. 85, 3–4 thinks that river deltas may be limited when sediment retention approaches zero, when the delta front advances into deep waters, or by the combination of sea-level rise and subsidence. Inland deltas form in hot, arid inland drainage areas, where water dynamics and sediment transport are very different, especially deposition associated with expansion–contraction dynamics at the channel head. As a result, the mean slope of the delta decreases with distance from the apex, while in coastal deltas it increases towards; see Seybold et al. (2010) Geophys. Res. Lett. DOI:10.1029/2009GL041605. Delta shore composition
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