- 行业: Earth science
- Number of terms: 93452
- Number of blossaries: 0
- Company Profile:
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, ...
(1) One of a set of three coordinates in a spherical coordinate system. (2) A coordinate in a coordinate system on a sphere. Usually, two coordinates, in angular or linear units, fix the location of a point with respect to two great circles that intersect at right angles. However, the coordinates may be the great circle distances from two points on the sphere or may be the distance along one great circle and distance from another. The term is sometimes used to designate a coordinate on any surface approximately spherical.
Industry:Earth science
A theodolite sufficiently accurate and sturdy that it can be used in construction projects. The accuracy of a construction theodolite is usually sufficient that the instrument can also be used for third order surveying.
Industry:Earth science
An angle used as a coordinate, i.e., an angle which, alone or together with other coordinates, specifies the location of or direction to a point. Astronomers use two angular coordinates for specifying the directions to stars and similar celestial bodies. These coordinates are called the position of the body; the third coordinate, distance, is usually absent.
Industry:Earth science
An imaginary surface containing all points at which the barometric pressure is 29. 92 inches of mercury at a temperature of 15<sup>o</sup>C.
Industry:Earth science
(1) The systematic elimination of discrepancies between adjoining or overlapping triangulation networks on different datums by moving the origin, rotating, and stretching the networks until they fit each other. (2) The set of constants used to transform the coordinates of a station from one datum or ellipsoid to another, together with the coordinates on the two datums.
Industry:Earth science
One of the three coordinates of a point in a cylindrical coordinate-system.
Industry:Earth science
A conveyance that separates the land to be conveyed from that not to be conveyed by specifying a line or natural feature separating the two.
Industry:Earth science
(1) A parabolic curve used as a transition curve between different grades or slopes. (2) A Bz curve. (3) A transition curve in the vertical direction. It is usually parabolic and symmetrical about the highest point. (4) A parabolic curve used to connect grades of different slopes to avoid the sudden change in direction in passing from one grade to the other. This method of changing grade is usually used when there is an algebraic difference of more than 0. 2 percent in the initial and final grades.
Industry:Earth science
The amplitude of that term, in the equation for nutation in obliquity, which has the period of the longitude of the Moon's ascending node. Alternatively, the coefficient of cosΩ in the equation Δε = a cos Ω + b cos 2 Ω + c cos 2L`s + d cos 2L <sub>m</sub>, in which Δε is the nutation in obliquity of the ecliptic, Ω is the longitude of the Moon's ascending node, L <sub>s</sub> is the mean longitude of the Sun and L <sub>m</sub> is the longitude of the Moon. The value adopted by the International Astronomical Union in 1976 is 9. 2109" at epoch 2000.
Industry:Earth science
A method of selecting, from among a number of possible schedules for a project, that schedule which best satisfies certain desiderata such as efficiency, time for completion, etc. It involves separating the project into sub projects or steps and identifying those steps (the critical steps) whose place or timing in the sequence cannot be changed, and adjusting the rest of the schedule to accommodate these critical steps as well as possible.
Industry:Earth science
