- 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 system for assigning short codes to the Earth's climate zones. It consists of a hierarchical arrangement of the major climatic groups, subcategories within these groups, and in some cases further subdivisions describing seasonal variations within a climate set.
Industry:Science
A system for data storage in which digitally encoded information in the form of microscopic pits on a rotating disk is accessed by optical readout. The compact disk was originally developed as a music carrier providing high fidelity, random access, convenience, durability, and low cost. Its attributes made it suitable for storing diverse data such as video programs and computer software, and improvements allowed recordability and erasability. Greater storage capacity and more sophisticated integration of features is provided in the DVD optical disk format.
Industry:Science
A system for enhancing the acoustical properties of both indoor and outdoor spaces, particularly for unamplified speech, song, and music. Systems are subdivided into those that primarily change the natural reverberation in the room, increasing its level and decay time (reverberation enhancement systems); and those that essentially replace the natural reverberation (sound field synthesis systems).
Both systems may use amplifiers, electroacoustic elements, and signal processing to add sound field components to change the natural acoustics. Sound field enhancement is used to produce variable acoustics, to produce a particular acoustics which is not attainable by passive means, or because a venue has one or all of the following deficiencies: (1) unsuitable ratio between direct, early reflected, and reverberant sound; (2) unsatisfactory early reflection pattern; and (3) short reverberation times.
Industry:Science
A system for providing a comfortable environment within the passenger compartment of a vehicle. Controlled ventilation is utilized, along with a heater, an air conditioner, or an integrated heater and air-conditioner system. Linked to the setup is a windshield defrosting and defogging system capable of clearing the windshield as specified in a timed test, as required for all passenger cars manufactured for sale in the United States. Some vehicles have a ventilation-air filter which cleans the outside air that enters the passenger compartment through the fresh-air inlet. The increasing glass area of many passenger vehicles places an additional load on the air conditioner. Many vehicles incorporate solar-control glass to reduce solar transmission to the interior.
Industry:Science
A system for specifying coordinates for locating celestial objects. The International Celestial Reference System (ICRS) was adopted by the International Astronomical Union in 1994 as the new fundamental reference system. The ICRS is defined from a Barycentric Celestial Reference System, where “barycentric” means that the system is based on the center of mass of the solar system bodies, and a Geocentric Celestial Reference System, where “geocentric” means that the system is based on the center of the Earth. The systems are established based on specified gravitational potentials for the two origins. Their orientations are the same, and a standard set of equations, known as the Lorentz transformation, can be used to change from one to the other. Though the fiducial point (orientation of the <i>x</i> axis) of the new reference system is arbitrary, it has been chosen to agree with the dynamical equinox of the preexisting system of moving (dynamical) solar system objects adopted for the beginning of the year 2000, known as J2000.0, as closely as its accuracy allows.
Industry:Science
A system for the automatic control of motion by means of feedback. The term servomechanism, or servo for short, is sometimes used interchangeably with feedback control system (servosystem). In a narrower sense, servomechanism refers to the feedback control of a single variable (feedback loop or servo loop). In the strictest sense, followed in this article, the term servomechanism is restricted to a feedback loop in which the controlled quantity or output is mechanical position or one of its derivatives (velocity and acceleration).
Industry:Science
A system for the generation of electrical power through the interaction of a flowing, electrically conducting fluid with a magnetic field. As in a conventional electrical generator, the Faraday principle of motional induction is employed, but solid conductors are replaced by an electrically conducting fluid. The interactions between this conducting fluid and the electromagnetic field system through which power is delivered to a circuit are determined by the magnetohydrodynamic (MHD) equations, while the properties of electrically conducting gases or plasmas are established from the appropriate relationships of plasma physics. Major emphasis has been placed on MHD systems utilizing an ionized gas, but an electrically conducting liquid or a two-phase flow can also be employed.
Industry:Science
A system in which individual engineering, production, and marketing and support functions of a manufacturing enterprise are organized into a computer-integrated system. Functional areas such as design, analysis, planning, purchasing, cost accounting, inventory control, and distribution are linked through the computer with factory floor functions such as materials handling and management, providing direct control and monitoring of all process operations.
Industry:Science
A system in which the heat-emitting and heat-absorbing means is the surface of the ceiling, floor, or wall panels of the space which is to be environmentally conditioned. The heating or cooling medium may be air, water, or other fluid circulated in air spaces, conduits, or pipes within or attached to the panels. For heating, electric current may flow through resistors in or on the panels.
Industry:Science
A system made up of a gas, electrodes, and an enclosing wall in which an electric current is carried by charged particles in response to an electric field, the gradient of the electric potential, or the voltage between two surfaces. The gas discharge is manifested in a variety of modes (including Townsend, glow, arc, and corona discharges) depending on parameters such as the gas composition and density, the external circuit or source of the voltage, electrode geometry, and electrode material. A gas discharge can also be inductively coupled to an alternating-current (ac) circuit, eliminating the need for electrodes. Gas discharges are useful both as tools to study the physics existing under various conditions and in technological applications such as in the lighting industry and in electrically excited gas lasers.
Industry:Science
