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- Number of terms: 178089
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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 temporary component of current and voltage in an electric circuit which has been disturbed. In ordinary circuit problems, a stabilized condition of the circuit is assumed and steady-state values of current and voltage are sufficient. However, it often becomes important to know what occurs during the transition period following a circuit disturbance until the steady-state condition is reached. Transients occur only in circuits containing inductance or capacitance. In general, transients accompany any change in the amount or form of energy stored in the circuit. After the following Introduction, transients in direct-current (dc) and alternating-current (ac) circuits with lumped elements are discussed. Transients of a more complex nature occur on distributed-parameter circuits, such as transmission lines. Such phenomena are elaborated upon in a separate section on transients in power systems. Finally, the modeling of transients in digital simulation is explained.
Industry:Science
A temporary wall-like structure which keeps water and soil out of a building site so that construction can proceed under dry conditions. Cofferdams are used in the construction of foundations, bridge piers, dams, dry docks, and similar structures which require dewatering and excavation of an area. The dewatered area can be completely surrounded by a cofferdam structure or a combination of earth slopes and cofferdam structure.
The type of construction is dependent on the site depth, soil conditions, fluctuations in water level, availability of materials, working conditions inside the cofferdam, and location either on land or in water. In most situations, since safety, ease of construction, and convenience are the most important considerations, and economy of materials is less important, refined methods of analysis may not be justified. However, an understanding of soil and water pressure against the cofferdam walls is necessary for even the most approximate design. Other important considerations in cofferdam design are the hydraulic analysis of seepage conditions (including filtering), and erosion of the bottom (scour) in streams and rivers.
Industry:Science
A tentative supposition with regard to an unknown state of affairs, the truth of which is thereupon subject to investigation by any available method, either by logical deduction of consequences which may be checked against what is known, or by direct experimental investigation or discovery of facts not hitherto known and suggested by the hypothesis. A classical example is the nebular hypothesis with regard to the origin of the solar system. The “truth” of this hypothesis may be checked by its ability to explain the properties of the solar system as now observed.
Industry:Science
A term applied commercially to any limestone or dolomite taking polish. Marble is extensively used for building and ornamental purposes.
Industry:Science
A term applied to a group of substances which include the sugars, starches, and cellulose, along with many other related substances. This group of compounds is vital in the lives of plants and animals, both as structural elements and in the maintenance of functional activity. Plants are unique in that they have the power to synthesize carbohydrates from carbon dioxide and water in the presence of the green pigment chlorophyll through the energy derived from sunlight, by the process of photosynthesis. This process is responsible not only for the existence of plants but for the maintenance of animal life as well, since animals obtain their entire food supply directly or indirectly from the carbohydrates of plants.
Industry:Science
A term applied to directional surveying instruments which record photographically the direction and magnitude of well deviations from the vertical. Two instruments of this type are in wide use, the Schlumberger photoclinometer and the Surwell clinograph. Both instruments record a series of deviation measurements on one trip into and out of the well. From this series of data it is possible to plot quite accurately the course of the well.
Industry:Science
A term broadly used to denote either the dissipation of energy in, and the consequent decay of, oscillations of all types or the extent of the dissipation and decay. The energy losses arise from frictional (or analogous) forces which are unavoidable in any system or from the radiation of energy to space or to other systems. For sufficiently small oscillations, the analogous forces are proportional to the velocity of the vibrating member and oppositely directed thereto; the ratio of force to velocity is -<i>R,</i> the mechanical resistance. For the role of damping in the case of forced oscillations, where it is decisive for the frequency response,
Industry:Science
A term broadly used to refer to how an individual understands what others are saying. More narrowly, speech perception is viewed as the way a listener can interpret the sound that a speaker produces as a sequence of discrete linguistic categories such as phonemes, syllables, or words.
Industry:Science
A term characterizing an excitation in a wave or field, connoting fundamental particlelike properties such as energy or mass, momentum, and angular momentum for this excitation. In general, any field or wave equation that is quantized, including systems already treated in quantum mechanics that are second-quantized, leads to a particle interpretation for the excitations which are called quanta of the field. This term historically was first applied to indivisible amounts of electromagnetic, or light, energy usually referred to as photons.
Industry:Science
A term commonly used in the evaluation for positive-displacement machinery performance which expresses the average net pressure difference in pounds per square inch (lb/in.<sup>2</sup> or psi) on the two sides of the piston in engines, pumps, and compressors. It is also known as mean pressure and is abbreviated mep or mp.
Industry:Science
