- 行业: Printing & publishing
- 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.
The processes whereby mass, energy, or momentum are transported from one region of a material to another under the influence of composition, temperature, or velocity gradients. If a sample of a material in which the chemical composition, the temperature, or the velocity vary from point to point is isolated from its surroundings, the transport processes act so as eventually to render these quantities uniform throughout the material. The nonuniform state required to generate these transport processes causes them to be known also as nonequilibrium processes. Associated with gradients of composition, temperature, and velocity in a material are the transport processes of diffusion, thermal conduction, and viscosity, respectively. For a large class of materials, the laws that govern the transport processes are quite simple.
Industry:Science
The production of bulk electric power for industrial, residential, and rural use. Although limited amounts of electricity can be generated by many means, including chemical reaction (as in batteries) and engine-driven generators (as in automobiles and airplanes), electric power generation generally implies large-scale production of electric power in stationary plants designed for that purpose. The generating units in these plants convert energy from falling water, coal, natural gas, oil, and nuclear fuels to electric energy. Most electric generators are driven either by hydraulic turbines, for conversion of falling water energy; or by steam or gas turbines, for conversion of fuel energy. Limited use is being made of geothermal energy, and developmental work is progressing in the use of solar energy in its various forms.
Industry:Science
The study of mechanisms of inheritance in animals and plants by using cells in culture. In such cells, chromosomes and genes can be reshuffled by parasexual means rather than having to depend upon the genetic recombination and chromosome segregation that occur during the meiotic cell divisions preceding gamete formation and sexual reproduction. Genetics is concerned with the role of genes and chromosomes and their environmental interactions in the development and function of individuals and the evolution of species. Genetic analysis of complex multicellular organisms classically requires multigeneration families. Because fairly large numbers of progeny of defined matings have to be scored, genetic analysis of animals and plants with long generation times, small families, or lack of controlled matings is difficult and slow.
Industry:Science
The study of spatial and temporal patterns in the abundance and distribution of organisms and of the mechanisms that produce those patterns. Species differ dramatically in their average abundance and geographical distributions, and they display a remarkable range of dynamical patterns of abundance over time, including relative constancy, cycles, irregular fluctuations, violent outbreaks, and extinctions. The aims of population ecology are threefold: (1) to elucidate general principles explaining these dynamic patterns; (2) to integrate these principles with mechanistic models and evolutionary interpretations of individual life-history tactics, physiology, and behavior as well as with theories of community and ecosystem dynamics; and (3) to apply these principles to the management and conservation of natural populations.
Industry:Science
The subdiscipline of biology that concentrates on the relationships between organisms and their environments; it is also called environmental biology. Ecology is concerned with patterns of distribution (where organisms occur) and with patterns of abundance (how many organisms occur) in space and time. It seeks to explain the factors that determine the range of environments that organisms occupy and that determine how abundant organisms are within those ranges. It also emphasizes functional interactions between co-occurring organisms. In addition to its character as a unique component of the biological sciences, ecology is both a synthetic and an integrative science since it often draws upon information and concepts in other sciences, ranging from physiology to meteorology, to explain the complex organization of nature.
Industry:Science
The source of energy required for the propulsion of airborne vehicles. This energy is released in the form of heat and expanding gases that are products of a combustion reaction that occurs when fuel combines with oxygen from ambient air. The exhaust gases are water vapor formed from hydrogen in the fuel, carbon dioxide formed from carbon in the fuel, traces of carbon monoxide and nitrogen oxides, and heated but uncombusted components of the intake air. Aircraft fuel is burned with ambient air and is thereby distinct from rocket propellants, which carry both fuel and oxidant. An important criterion for aircraft fuel is that its energy density, or heat of combustion per unit of weight, be high. This allows reasonable expenditures of fuel during takeoff, efficient performance in flight, and long range of flight duration.
Industry:Science
The movement through the atmosphere or space, sustained by aerodynamic reaction or other forces. Animal flight includes gliding and flapping flight. Four animal groups evolved flapping flight, namely insects, pterosaurs, birds, and bats. Flapping flight in vertebrates was probably preceded by gliding; in insects it may have originated by leaping and gliding, by surface skimming on water, or (if small enough) by passive floating in the air. Flying insects show greater variation than flying vertebrates, and their flight spans a wider range of Reynolds numbers, which is the ratio of inertial forces to viscous forces in the flow. Flight of tiny insects is in the lower range of Reynolds numbers, where viscous forces are dominant, whereas large insects and vertebrates operate in the higher range, where inertial forces are important.
Industry:Science
The reaction or result produced by applying an input signal to a system. Given a system, or interconnection of devices to perform a desired function, the signals processed by that system can be divided into several categories, some of which are referred to as causes, stimuli, or input signals; and others, as responses, effects, or output signals. Although there can be multiple input and output signals for a given system, attention will be focused on single-input single-output systems. Often, the input and output signals of interest are functions of time only, although the discussions given can be generalized to more than one independent variable, such as space and time. Also, attention will be limited to continuous-time signals and systems, although the discussion can be easily put in terms of discrete-time signals and systems.
Industry:Science
The tendency of atoms or molecules to coalesce into extended condensed states. This tendency is practically universal. In all but exceptional cases, condensation occurs if the temperature is sufficiently low; at higher temperatures, the thermal motions of the constituents increase, and eventually the solid assumes gaseous form. The cohesive energy is the work required to separate the condensed phase into its constituents or, equivalently, the amount by which the energy of the condensed state is lower than that of the isolated constituents. The science of cohesion is the study of the physical origins and manifestations of the forces causing cohesion, as well as those op-posing it. It is thus closely related to the science of chemical bonding in molecules, which treats small collections of atoms rather than extended systems.
Industry:Science
The primary role of most universities has changed over the last 40 years as they have become research institutions with little faculty time to teach undergraduate students. At the same time, the role of engineers in society and the skills required to fill this role have also changed. Dramatic advances in computers and communications are responsible in part for these changes, while providing new teaching tools and an improved knowledge of the learning process. As a result, there has been an extensive and intensive reevaluation of engineering curricula and teaching methodologies. Computers and multimedia technology will profoundly affect teaching and learning in the future. They are, however, only tools, and there will always be a need for faculty involvement in mentoring, lecturing, and the more traditional methods of instruction.
Industry:Science
