- 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 machine that produces printed copy, character by character, as it is operated. Its essential parts are a keyboard, a set of raised characters or a thermal print head, an inked ribbon, a platen for holding paper, and a mechanism for advancing the position at which successive characters are printed. The QWERTY keyboard (named for the sequence of letters of the top row of the alphabet worked by the left hand) was designed in the 1870s. It contains a complete alphabet, along with numbers and the symbols commonly used in various languages and technical disciplines. The manual typewriter was introduced in 1874, followed by the electrically powered typewriter in 1934. By the late 1970s, electronic typewriters offered memory capability, additional automatic functions, and greater convenience. Further advances in electronic technology led to additional capabilities, including plug-in memory and function diskettes and cartridges, visual displays, nonimpact printing, and communications adapters. Although many typewriters are still in use, computers and word processing software largely have supplanted them.
Industry:Science
A machine that reduces the size of particles of raw material fed into it. The size reduction may be to facilitate removal of valuable constituents from an ore or to prepare the material for industrial use, as in preparing clay for pottery making or coal for furnace firing. Coarse material is first crushed. The moderate-sized crushings may be reduced further by grinding or pulverizing.
Industry:Science
A machine which converts the energy of an elevated water supply into mechanical energy of a rotating shaft. Most old-style waterwheels utilized the weight effect of the water directly, but all modern hydraulic turbines are a form of fluid dynamic machinery of the jet and vane type operating on the impulse or reaction principle and thus involving the conversion of pressure energy to kinetic energy. The shaft drives an electric generator, and speed must be of an acceptable synchronous value.
Industry:Science
A macromolecule derived from natural sources; also known as biological polymer. Nature has developed effective means for efficiently preparing and utilizing biopolymers. Some are used as structural materials, food sources, or catalysts. Others have evolved as entities for information storage and transfer. Familiar examples of biopolymers include polypeptides, polysaccharides, and polymers derived from ribonucleic acid (RNA) and deoxyribonucleic acid (DNA). Other examples include polyhydroxybutyrates, a class of polyesters produced by certain bacteria, and cis-1,4-polyisoprene, the major component of rubber tree latex.
Industry:Science
A macroscopic fungus with a fruiting body (also known as a sporocarp). It has been estimated that over 1,500,000 species of fungi exist on the Earth; yet only about 69,000 species have been described to date. Approximately 14% (10,000) described species of fungi are considered mushrooms. Mushrooms grow aboveground or underground. They have a fleshy or nonfleshy texture. Many are edible, and only a small percentage are poisonous.
Industry:Science
A magnesium-rich orthorhombic amphibole with perfect (210) cleavage and a color which varies from white to various shades of green and brown. It is a comparatively rare metamorphic mineral which occurs as slender prismatic needles, in fibrous masses, and sometimes in asbestiform masses. Anthophyllite may occur together with calcite, magnesite, dolomite, quartz, tremolite, talc, or enstatite in metacarbonate rocks; with plagioclase, quartz, orthopyroxene, garnet, staurolite, chlorite, or spinel in cordierite-anthophyllite rocks; and with quartz and hematite in metamorphosed iron formations and with talc, olivine, chlorite, or spinel in metamorphosed ultrabasic rocks. Anthophyllite is distinguished from other amphiboles by optical examination or by x-ray diffraction, and from other minerals by its two cleavage directions at approximately 126° and 54°.
Industry:Science
A magnetic field with axial symmetry capable of converging beams of charged particles of uniform velocity and of forming images of objects placed in the path of such beams. Magnetic lenses are employed as condensers, objectives, and projection lenses in magnetic electron microscopes, as final focusing lenses in the electron guns of cathode-ray tubes, and for the selection of groups of charged particles of specific velocity in velocity spectrographs.
Industry:Science
A magnetic field, far stronger than the Earth's magnetic field, which is possessed by many stars. Magnetic fields are important throughout the life cycle of a star. Initially, magnetic fields regulate how quickly interstellar clouds collapse into protostars. Later in the star formation process, circumstellar disk material flows along magnetic field lines, either accreting onto the star or flowing rapidly out along the rotation axis. Outflowing material (stellar winds) carries away angular momentum, slowing rotation at a rate that depends on stellar magnetic field strength. On the Sun, dark sunspots, prominences, flares, and other forms of surface activity are seen in regions where there are strong magnetic fields. There is some evidence that long-term variations in solar activity may affect the Earth's climate. Turbulence in the solar atmosphere drives magnetic waves which heat a tenuous corona (seen during eclipses) to millions of degrees. About 10% of hotter stars (with temperatures of about 10,000 K) with stable atmospheres are Ap stars, which have stronger magnetic fields that control the surface distribution of exotic elements. Even after stars end their internal fusion cycle and become compact remnants, magnetic fields channel accreting material from binary companions, occasionally producing spectacular novae. Despite the enormous gravity around pulsars, magnetic forces far exceed gravitational forces, creating intense electromagnetic beams that spin down (slow the rotation of) the pulsar.
Industry:Science
A magnetic waveguide atom interferometer is a device which creates an interference pattern by coherently splitting a Bose-Einstein condensate (BEC) into two separate parts, guiding each along separate paths using magnetic waveguides, and recombining them at some point later, resulting in interference between the two pieces of the condensate. Such a device is sensitive to the relative atomic phase between the two condensate pieces, and is therefore sensitive to the difference in path lengths traversed by the two condensate parts. A separated-path atom interferometer can detect anything that alters the condensate phase or path traveled, including inertial forces (such as gravity, gravity gradients, and rotation), magnetic fields, electric fields, and relativistic effects. There are a myriad of applications to inertial force sensors, particularly involving the detection of topographical features that have densities different from surrounding areas. Applications include navigation, object avoidance, detection of underground oil and minerals, corrections to the orbits of Global Positioning System (GPS) satellites, detection of subsurface structures such as tunnels, precision tests of general relativity, and searches for new fundamental forces. Atom interferometers are robust and potentially inexpensive devices for these applications, as they have no moving parts and can be built with commercially available technology. Waveguide interferometers add the benefits of extremely high sensitivity coupled with compact size.
Industry:Science
A main drive for developing reliable sources of renewable energy is the fast-growing worldwide energy demand with consequent depletion of fossil fuels, which supply over 85% of the present energy needs. Among the renewable energy sources used today (such as concentrating solar power, solar cells, wind, geothermal, hydropower, and biomass), concentrating solar power (CSP) is the only technology that can supply several times the world's energy requirements, since it has viable, efficient, and available one-day energy storage methods. Storage systems for other renewable sources, such as photovoltaic and wind, are much less efficient and more expensive. There also is not enough usable land for growing sufficient biomass. CSP plants have to be installed in deserts, because clouds and rain strongly lower their efficiency. Suitable deserts are one or two orders of magnitude larger than needed and, aside from some isolated islands, high-efficiency transmission lines can reach all populated areas. Most potential problems for large-scale installation of CSP are political rather than technical. However, since solar energy is the only large-scale renewable source we have for the future, we have to learn how to overcome such obstacles. North America and many other places do not have such obstacles.
Industry:Science
