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in astronomy, one of the two diametrically opposite points of the celestial sphere at which the plane of the orbit of some celestial body intersects a reference coordinate plane that is either the plane of the ecliptic or of the equator. The points where the orbit intersects the reference plane are sometimes also called nodes. A distinction is made between the ascending node (astronomical symbol ), where the celestial body crosses from the southern to the northern side of the reference plane, and the descending node (symbol ), where the body crosses the reference plane in the opposite direction.
For planets, comets, and the moon the ecliptic serves as the reference plane. In this case, the position of the nodes on the celestial sphere is defined by their longitudes. When the orbits of artificial earth satellites are determined, the plane of the equator serves as the reference plane, and the positions of the nodes are given by the right ascensions of the nodes. The longitude of the ascending node and the right ascension of the ascending node are orbital elements.
For binary stars the points where the orbits intersect the plane perpendicular to the line of sight are called nodes.
in botany, the part of a shoot axis on which the leaf, the bud, and, sometimes, the adventitious roots form.
Nodes are separated by internodes. On the basis of the distance between nodes, shoots are distinguished as being long or short. Nodes form on the growing point of a shoot when the leaf rudiments first appear. At the node the procambial bundles of the developing leaf become embedded in the axis of the shoot. From these bundles and from the bundles of previously laid down leaves the common bundles of the shoot axis are formed. The common bundles constitute the entire conducting system of the axis. The anatomical structure of nodes varies, depending on the leaf arrangement, the number of procambial bundles in the leaf, and the way the bundles enter the node. Bundles of the axillary buds (branches), which form branch traces, join the conducting system of the shoot axis at the node. The structure of the shoot nodes is a taxonomic character for many plant species.
in mathematics, a type of singular, or critical, point of a differential equation (seeSINGULAR POINT). All integral curves passing through points in a sufficiently small neighborhood of a node enter the node.
In Russian mathematical literature, three different types of such nodes are distinguished: ordinary (obychnyi), degenerate (vyrozhdennyi), and special (osobyi). An ordinary node is a critical point such that all but one of the integral curves passing through the point are tangent to the same line (Figure l, a). In the case of a degenerate node, all the integral curves passing through the node are tangent to the same line (Figure l, b). In the case of a special, or dicritical (dikriticheskii), node, integral curves enter the origin from every direction (Figure l, c). In English, the first two cases are sometimes called improper nodes, and the third case is sometimes referred to as a proper node.
The term “node” is also applied to one type of singular point of a curve.
The Russian word for node—uzel—also has the meaning of knot. In topology a knot is, in the simplest case, a continuous closed space curve that does not intersect itself.
in physics, a point or surface in a standing-wave system at which the kinetic or potential energy of the wave is zero. In a stretched flexible string exhibiting sinusoidal free vibrations, tension nodes alternate with displacement nodes. In a standing sound wave, pressure nodes alternate with velocity nodes. In both cases, positions of zero potential energy alternate with positions of zero kinetic energy. Potential energy nodes coincide with kinetic energy antinodes, or loops, and kinetic energy nodes coincide with potential energy antinodes. In electromagnetic standing waves, nodes of the electric and magnetic fields are positions of zero electric and magnetic field strength, respectively; nodes of the electric field are antinodes of the magnetic field, and. vice versa.
panel point, node
node(1) See Node.js.
(2) In a network, a node is a junction or connection point. Every terminal, computer, hub, switch and router is a node. Devices that hold and serve data are "hosts." See host, hub, switch, router and terminal.
(3) In database management, a node is an item of data that can be accessed by two or more routes. See DBMS.
(4) In the Document Object Model (DOM), which exposes HTML and XML content to an application or script, every element, every attribute of that element, and each piece of textual content for every attribute is considered a node. See DOM.
(5) In computer graphics, a node is an endpoint of a graphical element. See graphics.
(6) In multiprocessing systems, a node can be a single processor or system. In MPP, it is one processor. In SMP, it is one computer system with two or more processors and shared memory. See SMP and MPP.
|The First Four Nodes of the Internet|
|Scrawled on this paper in 1969 were the first four nodes of the ARPANET network, which later became the Internet. (Image courtesy of The Computer History Museum, www.computerhistory.org)|