useful cross section
61Expansion chamber — An Expansion chamber is an exhaust system used on a two stroke cycle engine to enhance its power output by improving its volumetric efficiency. It makes use of the energy left in the burnt exhaust exiting the cylinder to aid the filling of the… …
62Ellipse — Elliptical redirects here. For the exercise machine, see Elliptical trainer. This article is about the geometric figure. For other uses, see Ellipse (disambiguation). Not to be confused with ellipsis. An ellipse obtained as the intersection of a… …
63Neutron — This article is about the subatomic particle. For other uses, see Neutron (disambiguation). Neutron The quark structure of the neutron. (The color assignment of individual quarks is not important, only that all three colors are present.)… …
64Optical amplifier — An optical amplifier is a device that amplifies an optical signal directly, without the need to first convert it to an electrical signal. An optical amplifier may be thought of as a laser without an optical cavity, or one in which feedback from… …
65radioactivity — /ray dee oh ak tiv i tee/, n. Physics, Chem. the phenomenon, exhibited by and being a property of certain elements, of spontaneously emitting radiation resulting from changes in the nuclei of atoms of the element. Also called activity. [1895… …
66textile — /teks tuyl, til/, n. 1. any cloth or goods produced by weaving, knitting, or felting. 2. a material, as a fiber or yarn, used in or suitable for weaving: Glass can be used as a textile. adj. 3. woven or capable of being woven: textile fabrics. 4 …
67Maxwell's equations — For thermodynamic relations, see Maxwell relations. Electromagnetism …
68Slip (aerodynamic) — A slip is an aerodynamic state where an aircraft is moving sideways as well as forward relative to the oncoming airflow. In other words, for a conventional aircraft, the nose will not be pointing directly into the relative wind . Flying in a slip …
69Insect wing — Original veins and wing posture of a dragonfly. Hoverflies hovering to mate …
70M39 Pantserwagen — Type Armoured car Place of origin  Netherlands …
