Connection or dependence, proceeding from the subordination of the parts of a thing to one principle or purpose, as in the parts of a discourse, or of a system of philosophy; consecutiveness
maintenance of a constant phase relationship between rotating or oscillating waves or objects Loss of phase coherence of the spins results in a decrease in the transverse magnetization and hence a decrease in the NMR signal
A term that's applied to electromagnetic waves When they "wiggle" up and down together (in phase) they are said to be coherent A laser is a good example of coherent light An ordinary light bulb produces incoherent light much like the random waves produced when many raindrops hit a puddle Electromagnetic radiation is coherent when the photons are produced in such a way that they are in phase with one another and incoherent when the phases of the photons are random Partial coherence is an intermediate situation where there a significant fraction of the photons have related phase, but not all of them
Coherence can be devided into spatial and temporal coherence For any em wave, if at time t=0 and t0 the phase diference between two points in space remains the same, we say the em wave has spatial coherence; If at a point P, the em wave at t and t+dt has same phase difference if dt is the same, temporal coherence exists
The degree of coherence or interferometric correlation is a measure of the spatial variance of the phase difference between two radar acquisitions It pertains to additional radar amplitude information, which describes the similarity of phase between two radar acquisitions: a high level of coherence (close to 1) indicates very good phase correlation between two images, and is a consequence of properties of the target as compared to different radar scattering phenomena and the absence of change which may have affected the target Conversely, for weak coherence, the degree of coherence tends towards 0
The ordering of writes to a single location, such as shared memory Atomic stores to a given location are coherent if they are serialized in some order, and no processor is able to observe any subset of those stores as occurring in a conflicting order
The ratio of coherent output power between channels in a dual-channel DSA An effective means of determining the similarity of vibration at two locations, giving insight into the possibility of cause and effect relationships
Coherence is a state or situation in which all the parts or ideas fit together well so that they form a united whole. The anthology has a surprising sense of coherence
In physical optics, the term used to describe either the temporal or spatial correlation of two wave disturbances The mutual coherence function () of two wave fields E(t) and E(t) is the same as their temporal cross correlation r(): The spatial coherence function (r,r) of a wave field E is the same as its spatial autocorrelation g(r,r): The spatial autocorrelation of the wave field from distant, extended but spatially incoherent astronomical sources depends only on the separation r-r and not on the absolute locations r or r where the wave field is sampled The spatial autocorrelation function can be estimated from measurements made with correlation-type radio interferometers: it differs from the visibility function that is sampled by a real interferometer only through the effects of the primary beam attenuation and the spatial averaging performed by finite-sized antennas
Connection or dependence, proceeding from the subordination of the parts of a thing to one principle or purpose, as in the parts of a discourse, or of a system of philosophy; consecutiveness
A relation among a number of elements, such as propositions or concepts, that fit together well: consistency; cohesiveness See practical reasoning for an example <Discussion> < References> Paul Thagard
attribute of received echoes with constant relative phase shift versus time (e g originating from non-moving targets), in contrast to the incoherent echoes received from many small targets moving relative to each other, as falling rain drops do