- 行业: Printing & publishing
- Number of terms: 178089
- Number of blossaries: 0
- Company Profile:
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 surface-area light source that employs the principle of electroluminescence to produce light. Light panels are composed of two sheets of electrically conductive material, one a thin conducting backing and the other a transparent conductive film, placed on opposite sides of a plastic or ceramic sheet impregnated with a phosphor, such as zinc sulfide, and small amounts of compounds of copper or manganese. When an alternating voltage is applied to the conductive sheets, an electric field is applied to the phosphor. Each time the electric field changes, it dislodges electrons from the edges of the phosphor crystals. As these electrons fall back to their normal atomic state, they affect the atoms of the slight “impurities” of copper or manganese, and radiation of the wavelength of light is emitted.
Industry:Science
A suspension of minute droplets or ice crystals produced by the condensation of water vapor. This article presents an outline of cloud formation upon which to base an understanding of cloud classifications. For a more technical consideration of the physical character of atmospheric clouds, including the condensation and precipitation of water vapor,
Industry:Science
A suspension of small particles in a gas. The particles may be solid or liquid or a mixture of both. Aerosols are formed by the conversion of gases to particles, the disintegration of liquids or solids, or the resuspension of powdered material. Aerosol formation from a gas results in much finer particles than disintegration processes (except when condensation takes place directly on existing large particles). Dust, smoke, fume, haze, and mist are common terms for aerosols. Dust usually refers to solid particles produced by disintegration, while smoke and fume particles are generally smaller and formed from the gas phase. Mists are composed of liquid droplets. These special terms are helpful but are difficult to define exactly.
Industry:Science
A symmetry of the fundamental (microscopic) equations of motion of a system; if it holds, the time reversal of any motion of the system is also a motion of the system. To date, only two phenomena have shown evidence (at least indirect) for violation of time reversal invariance. One is the violation of <i>CP</i> invariance observed in the decays of the neutral mesons <i>K</i><sub><i>L</i></sub> and <i>B</i><sup>0</sup>, B<sup>0</sup>. The other is the baryon asymmetry of the universe.
Industry:Science
A synchronous machine used to convert alternating current (ac) to direct current (dc), or vice versa. The ac-to-dc converter has been superseded by solid-state converters using silicon controlled rectifiers (SCRs) or power MOSFETs (for reasons of efficiency, lower maintenance costs, and less trouble) or by motor-generator sets. Converters are no longer manufactured, but there are converters still in use.
Industry:Science
A syndrome of abnormal traits that appears in the hybrids between certain strains of the fruit fly <i>Drosophila melanogaster</i>. The traits include partial sterility and greatly elevated rates of genetic mutations and chromosome rearrangements. Strains can be classified as P for paternally contributing or M for maternally contributing, so that only the hybrid sons and daughters of M females mated to P males show hybrid dysgenesis.
Industry:Science
A synthetic discipline that describes the distributions of living and fossil species of plants and animals across the Earth's surface as consequences of ecological and evolutionary processes. Biogeography overlaps and complements many biological disciplines, especially community ecology, systematics, paleontology, and evolutionary biology.
Industry:Science
A synthetic method which avoids the premature termination of growing radicals and produces polymers with precise compositions, architectures, and functionalities.
Industry:Science
A system carried on many aircraft to warn the pilot that the aircraft may be in danger of inadvertent contact with the ground. It is intended to reduce the occurrence of controlled-flight-into-terrain (CFIT) accidents, in which aircraft with no apparent mechanical difficulty or defect strike the ground while under the direct or indirect control of the pilot. These accidents usually occur in conditions of poor visibility (due to atmospheric obscuration such as fog or rain, or darkness of night) where external visual cues are not available to provide added assurance of terrain clearance. Since 1975, federal aviation regulations have required installation of the system on large turbine-powered aircraft in commercial service.
Industry:Science
A system composed of two almost equal-size asteroids orbiting around their center of mass, or one moonlet revolving around a larger primary body. The discovery of binary asteroids will aid the work of observers and theorists alike, since they help to determine the nature of these remnants of the solar system formation.
Industry:Science
