angular length
61Diffraction topography — (short: topography ) is an X ray imaging technique based on Bragg diffraction. Diffraction topographic images ( topographs ) record the intensity profile of a beam of X rays (or, sometimes, neutrons) diffracted by a crystal. A topograph thus… …
62The Dark Energy Survey — DES logo The Dark Energy Survey (DES) is a survey that aims to probe the dynamics of the expansion of the universe and the growth of large scale structure. The collaboration is composed of research institutes and universities from United… …
63Architecture and Civil Engineering — ▪ 2009 Introduction Architecture For Notable Civil Engineering Projects in work or completed in 2008, see Table (Notable Civil Engineering Projects (in work or completed, 2008)). Beijing was the centre of the world of architecture… …
64Defining equation (physics) — For common nomenclature of base quantities used in this article, see Physical quantity. For 4 vector modifications used in relativity, see Four vector. Very often defining equations are in the form of a constitutive equation, since parameters of… …
65Optimum HDTV viewing distance — is the distance that provides the viewer with the optimum immersive visual HDTV experience. Although opinions vary on the exact screen size to distance relationship, formal research and recommendations suggest closer is preferred to further[not… …
66Rotation around a fixed axis — Rotational motion can occur around more than one axis at once, and can involve phenomena such as wobbling and precession. Rotation around a fixed axis is a special case of rotational motion, which does not involve those phenomena. The kinematics… …
67Tidal acceleration — is an effect of the tidal forces between an orbiting natural satellite ( i.e. a moon), and the planet (called the primary) that it orbits. It causes a gradual recession of a satellite in a prograde orbit away from the primary, and a corresponding …
68quantum mechanics — quantum mechanical, adj. Physics. a theory of the mechanics of atoms, molecules, and other physical systems that are subject to the uncertainty principle. Abbr.: QM Cf. nonrelativistic quantum mechanics, relativistic quantum mechanics. [1920 25]… …
69chemical bonding — ▪ chemistry Introduction any of the interactions that account for the association of atoms into molecules, ions, crystals, and other stable species that make up the familiar substances of the everyday world. When atoms approach one another …
70Gear — For the gear like device used to drive a roller chain, see Sprocket. This article is about mechanical gears. For other uses, see Gear (disambiguation). Two meshing gears transmitting rotational motion. Note that the smaller gear is rotating… …
