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McGraw Hill Financial, Inc. is an American publicly traded corporation headquartered in Rockefeller Center in New York City. Its primary areas of business are financial, publishing, and business services.
A fit that has considerable negative allowance so that the diameter of a hole is less than the diameter of a shaft that is to pass through the hole, also called a heavy force fit. Shrink fits are used for permanent assembly of steel external members, as on locomotive wheels. The difference between a shrink fit and a force fit is in method of assembly. Locomotive tires, for instance, would be difficult to assemble by force, whereas a shaft and hub assembly would be convenient for force fit by a hydraulic press. In shrink fits, the outer member is heated, or the inner part is cooled, or both, as required. The parts are then assembled and returned to the same temperature.
Industry:Science
A fixed point in a material body through which the resultant force of gravitational attraction acts. The resultant of all forces or attractions produced by the Earth's gravity on a body constitutes its weight. This weight is considered to be concentrated at the center of gravity in mechanical studies of a rigid body. The location of the center of gravity for a body remains fixed in relation to the body regardless of the orientation of the body. If supported at the center of gravity, a body would remain balanced in its initial position. Coordinates, as for an aircraft, are conveniently chosen with origin at the center of gravity.
Industry:Science
A flat, largely waterless, sparsely populated, and sand-covered region in south-central Africa which occupies much of Botswana, plus adjacent parts of South Africa and Namibia. The precise boundaries of the Kalahari are difficult to define since it merges into humid regions to the north and east, and the arid Karoo and Namib further south and west. However, the generally agreed-upon boundaries are the Okavango-Zambezi “swamp zone” in the north and the Orange River in the south, with the western and eastern boundaries (in eastern Namibia and eastern Botswana, respectively) coinciding with the extent of the sandy Kalahari group sediments (see <b>illustration</b>).
Industry:Science
A flattened, ring-shaped device used to improve the tightness of a screw fastener. Three types of washer are in common use: plain, spring-lock, and antiturn (tooth-lock) washers. Standard plain washers are used to protect a part from damage or to provide for a wider distribution of the load. Because a plain washer will not prevent a nut from turning, a locking-type washer should be used to prevent a bolt or nut from loosening under vibration (see <b>illus.</b>). For industrial applications, spring-lock washers are intended to compensate for possible loosening between assembled parts and to facilitate assembly and disassembly. Lock washers create a continuous pressure between the parts and the fastener. The antiturn-type washers may be externally serrated, internally serrated, or both. The bent teeth bite into the bearing surface to prevent the nut from turning and the fastening from loosening under vibration. To speed up assembly, a variety of permanent preassembled bolt-and-washer and nut-and-washer combinations are available.
Industry:Science
A flavoring material obtained from the roots of at least four species of the genus <i>Smilax</i> (Liliaceae). These are <i>S</i>. <i>medica</i> of Mexico, <i>S</i>. <i>officinalis</i> of Honduras, <i>S</i>. <i>papyracea</i> of Brazil, and <i>S</i>. <i>ornata</i> of Jamaica, all tropical American vines found in the dense, moist jungles (see <b>illus.</b>). The flavoring is used mostly in combination with other aromatics such as wintergreen.
Industry:Science
A flexible device of connected links used to transmit power. A drive consists of an endless chain which meshes with sprockets located on the shaft of a driving source, such as an electric motor/reducer, and a driven source, such as the head shaft of a belt conveyor.
Industry:Science
A flexible web or mat of fibers isolated from wood or other plants materials by the operation of pulping. Nonwovens are webs or mats made from synthetic polymers, such as high-strength polyethylene fibers, that substitute for paper in large envelopes and tote bags.
Industry:Science
A flexible, lightweight structure, generally intended to retard the passage of an object through the atmosphere by materially increasing the resistive surface. Parachutes have continued to be the simplest and cheapest devices for the deceleration of payloads, people, and vehicles since their first recorded use in 1797. Comprising cloth and suspension lines, their construction is far simpler than that of aircraft. As a result, parachute construction and design is a fairly mature art. However, their very “softness” makes their aerodynamics much more complicated, so complicated in fact that modern supercomputers are not powerful enough to completely simulate both the evolution of the parachute shape and the internal and external airflows, either during inflation or during rapid flight maneuvers. Indeed, unlike aircraft, which are solid structures that deflect the air around them, parachutes not only deflect the surrounding air but also adopt shapes that are dictated by it. During inflation, such feedback is even more dominant as both shape and flows are basically unsteady (that is, do not remain constant in time). Finally, given the lack of streamlining both during and after inflation, turbulent flow rather than laminar flow controls the aerodynamics.
Industry:Science
A flight technique in which an aircraft rises directly into the air and settles vertically onto the ground. Such aircraft do not need runways but can operate from a small pad or, in some cases, from an unprepared site. The helicopter was the first aircraft that could hover and take off and land vertically, and is now the most widely used VTOL concept.
Industry:Science
A flooded portion of the northwest continental margin of Europe occupying an area of over 200,000 mi<sup>2</sup> (500,000 km<sup>2</sup>). The North Sea has extensive marine fisheries and important offshore oil and gas reserves. In the south, its depth is less than 150 ft (50 m), but north of 58° it deepens gradually to 600 ft (200 m) at the top of the continental slope. A band of deep water down to 1200 ft (400 m) extends around the south and west coast of Norway and is known as the Norwegian Trench (see <b>illus.</b>).
Industry:Science
