China
Africa
Explore chapters and articles related to this topic
Miscellaneous
Published in Dan Zwillinger, CRC Standard Mathematical Tables and Formulas, 2018
Each place in a knot where 2 strands touch and one passes over (or under) the other is called a crossing. The number of crossings in a knot is called the crossing number. Let N(n) be the number of distinct prime knots with n crossings, counting chiral versions of the same knot separately. Then 13(2n-2-1)≤N(n)<∼en. $ \frac{1}{3}(2^{n - 2} - 1) \le N(n)\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\thicksim}$}}{ < } e^{n} . $
C
Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
crystal oscillator The rotor current is assumed to produce a magnetic field electrically and spatially orthogonal to the field produced by the main stator winding, thus contributing to a rotating magnetic field. cross-quad the simplest form of the common centroid concept, in which two matched transistors are formed by connecting diagonally opposite devices in a two-by-two array of transistors. crossarm a transverse, generally insulated member mounted horizontally on a utility pole. It carries insulators and allows wide spacing of overhead conductors. crossarm brace a brace, often insulated, which keeps a crossarm from rotating on its attachment bolts. crossbar switch a structure that allows N units to communicate directly with each other, point to point. Which pairs are connected depends on how the switch is configured at that point in time. Crossbars are usually implemented for small (8 or less) numbers of nodes, but not always. crossed field devices (CFD) radial or linear forward traveling wave amplifier or backward wave oscillator where radial or transverse DC accelerating electric fields are perpendicular to axial or longitudinal DC magnetic fields, respectively. crossing number the even number obtained by adding the number of changes in binary value on going once around a particular pixel location; crossing number is useful for finding skeletons of shapes and for helping with their analysis: it is a measure of the number of `spokes' of an object emanating from a specified location. crossmodulation modulation of a desired carrier by an undesired interfering signal due to interaction of the two signals in one or more nonlinear elements. crossover frequency the frequency where the magnitude of the open-loop gain is 1. crossover point a crossover point of a fuzzy set A is the point in the universe of discourse whose membership in A is 0.5. crosspoint a point at which two overlaping neighboring fuzzy sets have the same membership grade. crosspoint level the membership grade of a fuzzy set at a crosspoint. crosstalk (1) undesired coupling (resistive, capacitive, or inductive) from one signal wire or transmission line to a colocated signal wire or transmission line. (2) capacitative interference between two parallel transmission lines, in which a signal on one line affects a signal on the other line. crowbar a triggered, shunt device that diverts the stored energy of the beam power supply. CRR CRT See cochannel reuse ratio. See cathode ray tube.
Crossing edge minimization in radial outerplanar layered graphs using segment paths
Published in Optimization Methods and Software, 2023
Francisco Madera-Ramírez, Joel Antonio Trejo-Sánchez, José López-Martínez, Jorge Ríos-Martínez
A crossing is defined to be a common interior point of two edges; hence, a shared endpoint (of two adjacent edges) is not considered a crossing. The input graphs of our proposed algorithm are layered with concentric circles. The crossing number was studied in [10], and it is defined as the minimum number of crossings in any graph drawing. The crossing number of a graph with n vertices can not exceed the crossing number of the complete graph , indicating the upper bound of general graphs. A path is a sequence of distinct vertices , with , together with the edges (or segments) . The number of segments defines the length of the path.