- 行业: Printing & publishing
- Number of terms: 178089
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- 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 theory which states that the particles of matter in all states of aggregation are in vigorous motion. In computations involving kinetic theory, the methods of statistical mechanics are applied to specific physical systems. The atomistic or molecular structure of the system involved is assumed, and the system is then described in terms of appropriate distribution functions. The main purpose of kinetic theory is to deduce, from the statistical description, results valid for the whole system. The distinction between kinetic theory and statistical mechanics is thus of necessity arbitrary and vague. Historically, kinetic theory is the oldest statistical discipline. Today a kinetic calculation refers to any calculation in which probability methods, models, or distribution functions are involved.
Industry:Science
A theory whose objective is to determine the scattering object, or an interaction potential energy, from the knowledge of a scattered field. This is the opposite problem from direct scattering theory, where the scattering amplitude is determined from the equations of motion, including the potential. The equations of motion are usually linear (operator-valued) equations. An example of an inverse problem was given in an article by M. Kac entitled “Can One Hear the Shape of a Drum?” For some drums this question can be answered yes, for yet others no, but for many the question remains unanswered.
Industry:Science
A thermodynamic cycle, operating as a heat engine or a heat pump, during which the working substance is in, or passes through, the vapor state. A vapor is a substance at or near its condensation point. It may be wet, dry, or slightly superheated. One hundred percent dryness is an exactly definable condition which is only transiently encountered in practice. Vapor behavior deviates so widely from the ideal gas laws that calculation requires the use of tables and graphs that give the experimentally determined properties of the fluid.
Industry:Science
A thermodynamic law, also known as Gay-Lussac's law, which states that at constant pressure the volume of a fixed mass or quantity of gas varies directly with the absolute temperature. Conversely, at constant volume the gas pressure varies directly with the absolute temperature. J. A. Charles and J. L. Gay-Lussac independently discovered the relation for an ideal gas. The relation is a useful and close approximation.
Industry:Science
A thermodynamic process in which the system undergoing the change exchanges no heat with its surroundings. An increase in entropy or degree of disorder occurs during an irreversible adiabatic process. However, reversible adiabatic processes are isentropic; that is, they take place with no change in entropy. In an adiabatic process, compression always results in warming, and expansion always results in cooling.
Industry:Science
A thermometer whose operation is based on Curie's law, which states that the magnetic susceptibility of noninteracting (that is, paramagnetic) dipole moments is inversely proportional to absolute temperature. Magnetic thermometers are typically used at temperatures below 1 K (−458°F). The magnetic moments in the thermometric material may be of either electronic or nuclear origin. Generally the magnetic thermometer must be calibrated at one (or more) reference temperatures.
Industry:Science
A thin sheet of wood of uniform thickness produced by peeling, slicing, or sawing. Depending on the manner of production and the portion of wood from which a veneer is made, the grain may be flat, vertical, or biased. Most veneer is rotary-cut from a bolt of wood, called a flitch, centered in the chucks of a lathe, which may have a capacity for logs from 2 to 16 ft (0.6 to 4.8 m) long, about 8 ft (2.4 m) being a common capacity. A nose bar bears against the flitch parallel to the center line of the lathe and a knife, also extending nearly the length of the lathe, peels off the veneer. Knives near the ends of the flitch cut the edges of theveneer.
Industry:Science
A thin, cellular, extraembryonic membrane forming a closed sac which surrounds the embryo in all reptiles, birds, and mammals and is present only in these forms; hence the collective term amniotes is applied to these animals. The amnion contains a serous fluid in which the embryo is immersed.
Industry:Science
A thinking system (also called value management or value analysis) used to develop decision criteria when it is important to secure as much as possible of what is wanted from each unit of the resource used. The resource may be money, time, material, labor, space, energy, and so on. The system is unique in that it effectively uses both knowledge and creativity, and provides step-by-step techniques for maximizing the benefits from both. It promotes development of alternatives suitable for the future as well as the present. This is accomplished by identifying and studying each function that is wanted by the customer or user, then applying knowledge and creativity to achieve the desired function. Resources are converted into costs to achieve direct, meaningful comparisons. By using the methods of value engineering, 15 to 40% reduction in the required resources often results.
Industry:Science
A thread or slender rod of metal. Wire is usually circular in cross section and is flexible. If it is of such a diameter or composition that it is fairly stiff, it is termed rod. The wire may be of several small twisted or woven strands, but if used for lifting or in a structure, it is classed as cable. Wire may be used structurally in tension, as in a suspension bridge, or as an electrical conductor, as in a power line. The working of metal into wire greatly increases its tensile strength. Thus, a cable of stranded small-diameter wires is stronger as well as more flexible than a corresponding solid rod. Wire may be treated or coated with various substances to protect it from corrosion or environmental influences. In addition, electrical conducting wire is usually covered with insulating material.
Industry:Science
