- 行业: Earth science
- Number of terms: 93452
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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, ...
Any one of several ratios, determined by Benoit, between various units of length and the meter. The more important ratios are:<br>
Industry:Earth science
Associated with cartography; having to do with mapping in a general sense.
Industry:Earth science
A quantity B giving the difference between the acceleration caused by the gravitational attraction of a spherical cap and the acceleration caused by the gravitational attraction of a Bouguer plate. i.e., of an infinite plate of the same thickness and composition as the cap. The spherical cap has a radius equal to the average radius of the Earth, a thickness equal to that of the Bouguer plate (usually taken as the elevation at the point of measurement) and an apex angle of 2<sup>o</sup> 59'56" (the outer diameter of Hayford zone O). Bullard's term is subtracted from a Bouguer gravity anomaly to obtain the equivalent, modified Bouguer gravity anomaly.
Industry:Earth science
The statement, resulting from Einstein's special theory of relativity, that if one clock is moving with respect to another, the moving clock will be found to be running slower than the other. The paradox is of little importance in surveying except when clocks at widely separated locations are to be synchronized by moving a clock from the one location to the other. In an experiment in which four cesium clocks were carried around the world, it was found that moving the clocks in the direction of rotation of the Earth slowed the moving clocks up, while moving them in the opposite direction speeded them up.
Industry:Earth science
A camera and all the equipment used with it for taking pictures. A camera system consists, typically, of the camera itself, a range finder, an exposure meter, the photographic film or plates and the operator. An aerial camera system also includes a timing device or intervalometer for controlling the shutter, a vacuum pump if the camera holds the film in place by vacuum, and a source of electric power for driving the camera and other items. The aircraft may be considered a part of the system if it is used only for aerial photography. The items other than the camera are called accessories.
Industry:Earth science
(1) According to the theory of isostasy, the balancing of masses above and below the geoid so that vertical pressure in regions close to the surface is approximately constant regardless of the elevation or depth of the physical surface. Such regions are said to be in isostatic equilibrium. If all parts of the region are in isostatic equilibrium, compensation is said to be local; if isostatic equilibrium holds for the region as a whole but not for parts of the region, compensation is said to be regional. The terms completely compensated and undercompensated are applied to compensation in such regions. (2) The quantity: (1 - (average isostatic anomaly))/(average Bouguer anomaly).
Industry:Earth science
That half of a meridian or celestial meridian which passes from one pole to another and through the antipode or nadir of the observer.
Industry:Earth science
The tools, equipment, buildings, and other constructions that businesses now use to produce goods and services.
Industry:Earth science
The separation of a collection of things, called elements objects, concepts, phenomena, etc. into sets, called categories, according to a set of rules such that: given any element, the set in which that element belongs can be determined from the rules; and given any set, the elements in that set can be found. The number of elements may be finite or infinite; the number of sets may be finite or infinite. The sets themselves may be collected into larger groupings which are sets of sets, and these again collected into larger grouping which are sets of sets of sets, etc. The different stages of collection are usually given distinctive names such as phylum, class, order, family, and so on, or may be numbered as 1st level, 2nd level, and so on. A complete classification assigns each element to one and only one set of a particular level; all the elements in one set have at least one common characteristic (which is given by the rules); two elements from different sets (of a particular level) differ in at least one characteristic (as specified by the rules). A partial classification assigns each element to one or more sets of a particular level, i.e., an element may belong to two or more sets at the same level at the same time.
Industry:Earth science
