![]() ![]() (3) The degree of sharpness of a displayed or printed image. (2) The number of bits used to record the value of a sample in a digitized signal. This article is provided by FOLDOC - Free Online Dictionary of Computing ( ) resolution (1) See resolve and name resolution. Resolution with backtracking is the basic control mechanism So we have proved the new literal, mortal(socrates). ((NOT man(socrates)) OR mortal(socrates))Īnd since (NOT A) AND A = False, and False OR A = A we can Which is why the left hand side of the implication is said toīe negative and the right positive. (The implication only fails if its premise is true but itsĬonclusion is false). The truth table for the implication function is "man(socrates)" could be considered to be on the right handĪnd is therefore "positive". "positive" in one and "negative" in the other to produce a new ItĮliminates, by unification, a literal that occurs Resolution is applied to two clauses in a sentence. The situation has been greatly improved by the use of aperture synthesis and very long baseline interferometry ( VLBI).Ī mechanical method for proving statements ofįirst order logic, introduced by J. In radio astronomy, where the same formulae for spatial resolution apply but where very much greater wavelengths are studied, apertures maybe 30 times greater than those used in optical telescopes can only give poor resolution. Very high spatial resolution is thus now feasible. The distorting effects of the Earth's atmosphere are greatly reduced in telescopes with active or adaptive optics, and are removed in orbiting telescopes. This is partly because of the difference in brightness and because Pluto is not a point source, but mainly because poor seeing prevented the larger-aperture telescopes from reaching the limiting angle. Although well above the limiting angle for large telescopes, Charon had not been resolved it was detected as an elongated photographic image. The discovery of Pluto's satellite Charon in 1978 shows that the Dawes (or Rayleigh) limit cannot be too strictly applied. Viewed under perfect seeing conditions with a 7.5-cm aperture (right) they are not resolved with 15-cm (center) they are just resolved and with 30-cm (left) they are clearly separated. The illustration shows the images of two stars of equal magnitude separated by 0.8 seconds of arc. Two stars are at a telescope's Rayleigh limit when the center of the Airy disk of one star falls on the first dark ring of the diffraction pattern of the other. The stars will just be resolved, however, when their Airy disks touch. If the two disks substantially overlap then increased aperture or magnification merely gives a larger blur of light, and the telescope has not sufficient resolving power to separate the images. Because of diffraction effects however, the image of each star is not a point of light but a disk (see Airy disk). When the angular separation of two stars is very small, it might be thought that the use of a large enough aperture or high enough magnification would always resolve the light into two distinct images.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |