- 行业: Earth science
- Number of terms: 93452
- Number of blossaries: 0
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Founded in 1941, the American Congress on Surveying and Mapping (ACSM) is an international association representing the interests of professionals in surveying, mapping and communicating spatial data relating to the Earth's surface. Today, ACSM's members include more than 7,000 surveyors, ...
The ability of the eye to adjust its sensitivity to varying intensities of illumination.
Industry:Earth science
An interior angle between adjacent sides of a closed figure, which is obtained by subtracting the sum of all the other interior angles of the figure from the theoretical value of the sum of all the interior angles. The concluded angle is most frequently met with in triangulation, where it is obtained by subtracting the sum of two known angles of a triangle from 180° plus the spherical excess of the triangle.
Industry:Earth science
The deviation of the measured value of a geodetic quantity from the theoretical value of that quantity, because there is a corresponding deviation of the Earth's actual structure at the point of measurement from the theoretical structure.
Industry:Earth science
(1) The bearing at the opposite end of a line from the observer, as measured from the astronomic meridian at the opposite end of the line. Back bearings to all lines (other than north south lines) differ from the bearings at the observer's station by the amount of the convergence of the meridians between the points. (2) The direction of a line from point A to point B as determined at point B and as corrected for the curvature of the line from A.
Industry:Earth science
(1) A unit of pressure equal to 106 dynes per square centimeter. Formerly called the barye. It was first suggested by Bjerknes in 1911. In SI units, it is 105 newton/m² or 105 Pa. The unit is used in both meteorology and oceanography. One standard atmosphere is 1. 013250 bars. The pressure exerted by a column of water 1 m deep is very nearly 1 decibar (1 dbar), which makes the unit convenient for oceanographers. (2) A long object of uniform but arbitrary cross section and of considerable mass. The width and depth of the solid are about the same. If the width is considerably greater than the depth, or vice versa, the object is called a sheet. (3) A ridge or mound of sand, gravel, or other unconsolidated material below the level of high water, especially at the mouth of a river or estuary, or lying a short distance from and usually parallel to a beach, and which may obstruct navigation.
Industry:Earth science
A marked point established in connection with a triangulation (or traverse) station to provide a starting azimuth for dependent surveys. The geodetic azimuth from the station to the azimuth mark is determined instrumentally; its distance is often determined only approximately but should be accurate enough that the effect, on measured angles, of the ordinary errors made in horizontal control of the USA. These markers are usually located so they are readily available, without special construction to elevate either instrument or centering instrument and target, can be ignored. Since 1928, azimuth markers consisting of bronze tablets set in concrete or stone have been established in connection with the basic target. At a station having an established azimuth mark, both the geodetic azimuth and the grid azimuth of the mark on the State Plane Coordinate System have been computed and published.
Industry:Earth science
That defect of a lens system in which the focal point shifts when the aperture is decreased. It is the result of the combined effects of a number of optical aberrations.
Industry:Earth science
A horizontal board nailed horizontally to two substantial posts, with the upper edge of the board preferably at grade or at some whole number of feet above or below grade. Batter boards are commonly erected, during construction of a building or in laying sewers, etc. , to help in alinement of the foundations, determine the depth of the necessary excavation, etc.
Industry:Earth science
Adjustment by an arithmetical process, as distinguished from a graphical adjustment, which is done geometrically. The usually procedure is to determine the discrepancies which exist among combinations of measurements, express these discrepancies in the form of condition equations or observation equations, and solve these equations to obtain corrections to the measurements (e.g., adjust the measurements) or corrections to the quantities on which the measurements depend. If there are more measurements than there are unknowns, the method of least squares is used.
Industry:Earth science
The difference between the reciprocal of the actual density ρ(S,T,P) of a sample of water and the reciprocal of sea water having a salinity S of 35 o/oo, a.
Industry:Earth science
