- 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 curved lattice grid dome that utilizes the equilateral triangle as the basis of its surface grid geometry. Buckminster Fuller, the inventor and champion of the geodesic dome, obtained a patent in 1954 that described a method of dividing a spherical surface into equilateral triangles. The realization that a triangular modular grid could be imposed on a spherical surface had great impact on the design philosophies of architects in Fuller's time.
Industry:Science
A curved piece of ground and polished or molded material, usually glass, used for the refraction of light. Its two surfaces have the same axis. Usually this is an axis of rotation symmetry for both surfaces; however, one or both of the surfaces can be toric, cylindrical, or a general surface with double symmetry. The intersection points of the symmetry axis with the two surfaces are called the front and back vertices and their separation is called the thickness of the lens.
Industry:Science
A customer premises communications system that provides its station subscribers with a wide variety of telephony services and access to public switched telephone network (PSTN) trunk circuits provided by local exchange carrier (LEC) and interexchange carrier (IEC) services. Standard private branch exchange (PBX) system hardware elements include the common equipment (cabinets, shelf carriers, printed circuit boards) and telephone instruments. Peripheral servers may also be included in the system design configuration to support systems management and voice messaging requirements. A PBX system is privately owned and physically located at the user subscriber's premises. Telephony services provided by a PBX range from basic communications operations (provisioning of dial tone and switched connections between peripheral endpoints) to station user-controlled call processing features (such as call transfer, call forwarding, and call waiting) to advanced software applications (such as multisystem networking and call contact centers).
Industry:Science
A cutting fluid, usually an oil or emulsion of a lubricating phase (oil, graphite, and so on) in water, is traditionally used in machining operations to reduce heat generated by friction, to lubricate, and to flush away chips (residual cut metal). The costs of maintenance, record keeping, and compliance with current and proposed regulations are rapidly boosting the expense of using cutting fluids. In 1980, cutting fluids and their disposal accounted for less than 3% of the cost of most machining processes. Today, cutting fluids account for as much as 16% of the cost of a machined part because of increased costs and stringent environmental regulations. In contrast, tooling accounts for only about 4% of that same part.
Industry:Science
A cyclic hydrocarbon alcohol commonly classified as a lipid because it is insoluble in water but soluble in a number of organic solvents. It is the major sterol in vertebrate cells and the most common sterol of eukaryotes, but it is absent from most prokaryotes. In vertebrates, the highest concentration of cholesterol is in the myelin sheath that surrounds nerves and in the plasma membrane that surrounds all cells. Insects and most invertebrates cannot synthesize cholesterol; therefore, they rely on dietary cholesterol for use in their membranes and as a precursor of ecdysone, a molting hormone required during growth and development.
Industry:Science
A cyclic organic compound that contains nitrogen in a negative oxidation state and is of limited distribution among living organisms. Over 10,000 alkaloids of many different structural types are known; and no other class of natural products possesses such an enormous variety of structures.
Industry:Science
A cyclosilicate mineral family with (BO<sub>3</sub>) triangular groups and a complex chemical composition. The general formula can be written XY<sub>3</sub>Al<sub>6</sub>(OH)<sub>4</sub>(BO<sub>3</sub>)<sub>3</sub>(Si<sub>6</sub>O<sub>18</sub>), in which X = Na, Ca, and Y = Al, Fe<sup>3+</sup>, Li, Mg, Mn<sup>2+</sup>. The more common tourmalines are dravite (X,Y = Na,Mg), schorl (X,Y = Na,Fe), uvite (X,Y = Ca,Mg), and elbaite (X,Y = Na,Li). Fluorine commonly substitutes in the hydroxyl position. Tourmaline is a hard (7½ on Mohs scale), varicolored mineral which can be an important semiprecious gemstone.
Industry:Science
A cylinder or fluid motor that converts hydraulic power into useful mechanical work. The mechanical motion produced may be linear, rotary, or oscillatory. Operating pressures range from a few pounds per square inch gage (psig or lb/in.<sup>2</sup> gage) to several thousand, but usually are about 500–5000 psig (3.4–34 megapascals). Sizes vary from 0.2-in.<sup>2</sup> (1.3-cm<sup>2</sup>) linear actuators capable of a few pounds of force to extremely large linear or rotary actuators capable of exerting hundreds of tons of force. Operation exhibits high force capability, high power per unit weight and volume, good mechanical stiffness, and high dynamic response. These features lead to wide use in precision control systems and in heavy-duty machine tool, mobile, marine, and aerospace applications.
Industry:Science
A cylindrical body with a helical groove cut into its surface. For practical purposes a screw may be considered to be a wedge wound in the form of a helix so that the input motion is a rotation while the output remains translation. The screw is to the wedge much the same as the wheel and axle is to the lever in that it permits the exertion of force through a greatly increased distance.
Industry:Science
A cylindrical fastener with an integral head on one end and an external screw thread on the other end designed to be inserted through holes in assembled parts and to mate with an internally threaded block, called a nut, which is turned to tighten or loosen the bolt. Tensioning the fastener by turning the nut differentiates a bolt from a screw, which is tightened by turning its head.
Industry:Science
