- 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 powdered, granular, or pelleted form of amorphous carbon characterized by very large surface area per unit volume because of an enormous number of fine pores. Activated carbon is capable of collecting gases, liquids, or dissolved substances on the surface of its pores. For many gases and liquids, the weight of adsorbed material approaches the weight of the carbon.
Industry:Science
A power device for removing bulk materials from railway freight cars or highway trucks. Especially in the case of railway cars, the car structure may aid the unloading, as in the hopper-bottom dumper; here the unloader may be a vibrator which improves flow of the bulk material into a storage bin or to a conveyor. Thus an unloader is the transitional device between interplant transportation means and intraplant materials-handling facilities.
Industry:Science
A power-driven ship employed in commercial transport on the oceans and large inland bodies of water such as the Great Lakes. This article treats design considerations of merchant ships and includes detailed information on 10 merchant ship types. The relatively small craft used for inland waterway transportation are not commonly referred to as ships. For a description of such craft
Industry:Science
A powerful 3D imaging method using an electron microscope. Imaging biological objects with an electron microscope, in principle, is very similar to imaging with a light microscope. In electron tomography imaging, a high-energy (typically 100–400 kV) coherent electron beam is used as the illumination source, and the focusing lenses are magnetic lenses. The incident electron beam interacts with the specimen and carries information about the inner structure of the specimen as the images are formed through the objective lenses. These images are further magnified and recorded on photographic films or by charge-coupled-device (CCD) cameras as 2D projection images. The 2D projection images contain information through the thickness of the specimen collapsed onto a plane. Traditionally, this methodology has been used successfully to study cellular ultrastructure and analyze immunolabeling of ultrathin sections of biological specimens at resolutions that are 100 times better than that achieved with light microscopy. However, when thicker specimens are analyzed, due to the large depth of focus with the electron beam, 2D projection images contain superposition of features in the direction of the electron beam that obscures much of the information. Nevertheless, because these 2D projection images contain information from all heights of the specimen, it is therefore possible by combining different views of the projection images to obtain the 3D internal structure of the object from a set of 2D projection images using an imaging method such as electron tomography (ET).
Industry:Science
A powerful astronomical technique that uses radar echoes to furnish otherwise unavailable information about bodies in the solar system. By comparing a radar echo to the transmitted signal, information can be obtained about the target's size, shape, topography, surface bulk density, spin vector, and orbital elements, as well as the presence of satellites and in certain situations the target's mass and density. While other astronomical techniques rely on passive measurement of reflected sunlight or naturally emitted radiation, the illumination used in radar astronomy is a coherent signal whose polarization and time modulation or frequency modulation are tailored to meet specific scientific objectives. Through measurements of the distribution of echo power in time delay or Doppler frequency, radar achieves spatial resolution of a planetary target despite the fact that the radar beam is typically much larger than the angular extent of the target. This capability is particularly valuable for asteroids and planetary satellites, which appear as unresolved point sources through optical telescopes. Moreover, the centimeter-to-meter wavelengths used in radar astronomy readily penetrate cometary comas and the optically opaque clouds that conceal Venus and Titan, and also permit determination of near-surface roughness (abundance of wavelength-scale rocks), bulk density, and metal concentration in planetary regoliths.
Industry:Science
A powerful x-ray telescope in orbit around the Earth. Built by the National Aeronautics and Space Administration, it was launched and deployed by space shuttle <i>Columbia</i> on July 23, 1999. Named after the Indian-American astronomer Subrahmanyan Chandrasekhar, <i>Chandra</i> is unique because of its sensitivity and its extremely high precision mirrors. These features have made possible significant advances in astronomy—especially in relation to the life cycles of stars, the role of supermassive black holes in the evolution of galaxies, and the study of dark matter and dark energy.
Industry:Science
A powerfully oxidizing allotropic form of the element oxygen. The ozone molecule contains three atoms (O<sub>3</sub>), while the more common oxygen molecule has two atoms (O<sub>2</sub>).
Industry:Science
A power-generation prime mover utilizing the steady-flow principle of fluid acceleration, where nozzles are mounted on the moving element. The rotor is turned by the reaction of the issuing fluid jet and is utilized in varying degrees in steam, gas, and hydraulic turbines. All turbines contain nozzles; the distinction between the impulse and reaction principles rests in the fact that impulse turbines use only stationary nozzles, while reaction turbines must incorporate moving nozzles. A nozzle is defined as a fluid dynamic device containing a throat where the fluid pressure drops and potential energy is converted to the kinetic form with consequent acceleration of the fluid. For details of the two basic principles of impulse and reaction as applied to turbine design
Industry:Science
A power-operated digging machine consisting of a lower frame and crawlers, a machinery frame, and a gantry supporting a boom which in turn supports a dipper handle and dipper (see <b>illustration</b>). Dipper sizes range from 1 to 180 yd<sup>3</sup> (0.7 to 137 m<sup>3</sup>). The machines are powered by on-board diesel engines or by electric motors. Diesel-powered machines utilize a series of clutches and brakes that allow the operator to control various motions. Electric motor machines generally have individual motors for each motion, but occasionally clutches and brakes are used allowing one motor to drive two motions.
Industry:Science
A practical unit of energy often used in atomic, nuclear, and particle physics. It is the energy acquired by an electron (or any singly charged particle) when it is accelerated by a potential difference of 1 V. The unit of energy in the International System (SI) is the joule: 1 eV is equal to 1.6022 10<sup>−19</sup> J. Although the electronvolt is a non-SI unit, it is often expressed using SI prefixes, for example, meV (10<sup>−3</sup> eV), keV (10<sup>3</sup> eV), MeV (10<sup>6</sup> eV), GeV (10<sup>9</sup> eV).
Industry:Science
