- Industry: Earth science
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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, ...
An orbital perturbation obtained by integrating the appropriate differential equations numerically with respect to time, yielding the perturbation at times between the starting time and the upper limit.
Industry:Earth science
(1) In general, a straight line perpendicular to a surface or to another line. (2) In geodesy, a straight line perpendicular to the surface of a particular ellipsoid. While the term normal is also used correctly to designate a straight line perpendicular to the surface of the geoid, the term vertical should be used if the line whose tangents are in the direction of gravity at each point is meant. Normal applies, in general, to a line of unspecified length, but some writers use it to designate the length of the line between the ellipsoid and the minor axis of the ellipsoid and designate it by Z or N. To this particular line the French apply the term great normal. The length is the radius of curvature of that ellipse in which a plane through the prime vertical intersects the ellipsoid.
Industry:Earth science
A hypothetical pendulum whose motion is described exactly by mathematical formulas.
Industry:Earth science
(1) The figure formed by two intersecting, straight half-lines terminating at their point of intersection. The two lines are called the sides of the plane angle; the point of intersection is called the vertex. (2) The figure formed by rotating a straight line about one of its terminal points. The initial position of the line is called the initial side and the final position the terminal side. Rotation is, by convention, considered positive if done in the counter-clockwise direction. An angle formed by rotation is therefore a directed angle. It can be represented by a vector whose length represents the size of the angle and whose direction is positive or negative according as the rotation was counter-clockwise or clockwise. (3) A number (ratio) expressing the rate at which the sides of a plane angle (f) diverge. The ratio is obtained by drawing an arc of a circle from the initial side of the angle (f) to the terminal side, using the vertex as center, with an arbitrary radius and dividing the length of the arc by the radius of the circle. A ratio of exactly one is called a radian (symbol r). An angle whose two sides coincide has a size of either 0 radians or π radians; the angle between a line and the perpendicular to it is π/2 radians. For example, 1.57085 93268r. The number obtained by multiplying the size of an angle in radians by 360/2π is called a sexagesimal measure of the angle in degrees. One degree contains 60 minutes of arc and one minute of arc contains 60 seconds of arc, so that the number of minutes less than a degree in the angle is obtained by multiplying the fractional part of the angle in degrees by 60 to get minutes and fractional parts of a minute and multiplying the fractional part of a minute by 60 to get the number of seconds and fractional parts of a second. The symbols <sup>o</sup>, ', " denote degrees, minutes and seconds respectively. For example, 57<sup>o</sup> 17' 44.866". The number obtained by multiplying by 400 instead of by 360 is called a centesimal measure of the angle in gons. The fractional part may be expressed in centesimal sub-units by a process similar to that given for obtaining minutes and seconds, but multiplying in each step by 100 to get centigons and centicentigons, respectively. For example, 63g 66cg 19.77ccg. The number obtained by multiplying by 24/2π is called the hour angle measure of the angle. It is used almost solely by astronomers and is derived from the astronomical method of measuring time. Sub-units in minutes of time and seconds of time are obtained by multiplying the fractional part by 60, exactly as for minutes of arc and seconds of arc. However, there are 15 minutes of arc in one second of time and 15 seconds of arc in one second of time. For example, 3h 49m 10.997s. Note that radian, sexagesimal and centesimal measures are non-dimensional, whereas hour angle measure has the dimension of time.
Industry:Earth science
Ein mathematisches Pendel ist eine Idealisierung des realen Pendels. Die Pendelschwingung wird anhand mathematischer Formeln exakt definiert. Es ist ein grundlegendes Modell zum Verständnis von Pendelschwingungen.
Industry:Earth science
El péndulo simple o matemático es un sistema idealizado cuyo movimiento viene exactamente definido mediante fórmulas matemáticas.
Industry:Earth science
The quantity 2 ω sin φ, in which ω is the rate of rotation of the Earth (7.292 116 x 10 <sup>-3</sup> radians per second) and φ is the geodetic latitude. Oceanographers usually denote the quantity by f or by kg.
Industry:Earth science
The right ascension of the Moon is determined at a place of known astronomic longitude and at the place whose astronomic longitude is wanted, at the time of the Moon's culmination (the passage of the Moon's center through the celestial meridian) by comparing the Moon's coordinates with the coordinates of several stars nearby. The difference in longitude is then the difference in right ascension divided by the Moon's hourly rate of motion in right ascension.
Industry:Earth science
(1) The observation of events in the heavens, i.e., of celestial phenomena. This does not imply making measurements. (2) Measurement of the altitude or azimuth, or both, of a celestial body. (3) The data obtained from measurements made of the location or position of a celestial body.
Industry:Earth science
A tube, used for measuring the pressure in a moving fluid, bent into the form of an L. Both ends are open. The base of the L lies in the stream parallel to the direction of flow, with the open end pointed upstream. The upright projects above the surface of the stream. The height of the fluid in the upright is proportional to the pressure of the fluid upon the open end in the stream. The pressure is usually proportional to the speed of the fluid, so that the Pitot tube is also used to determine speed either of the fluid or of the body on which the Pitot tube is mounted. The device was first described by H. Pitot (1732), who used it for determining the speed of water at different depths in a stream.
Industry:Earth science
