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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 graphical language used by engineers and other technical personnel associated with the engineering profession. The purpose of engineering drawing is to convey graphically the ideas and information necessary for the construction or analysis of machines, structures, or systems.
Industry:Science
A graphical procedure for converting impedances into reflection coefficients and vice versa. At high-frequency circuit operation, voltages and currents behave like traveling waves propagating over finite-length components. Copper traces on printed circuit boards, coaxial cables, and even simple wires become transmission lines. Changes in the length or operating frequency of these transmission lines result in periodic impedance behaviors not encountered in low-frequency circuits. Frequently, the impedance is replaced by the reflection coefficient, a more convenient way to quantify the transmitted and reflected voltage-current waves. To show how the impedance can be converted into a reflection coefficient and vice versa, P. H. Smith developed an ingenious graphical procedure based on conformal mapping principles. His approach permits an easy and intuitive display of the reflection coefficient as well as the complex impedance in a single graph. Although such a graphical procedure, nowadays known as the Smith chart, was developed in the 1930s prior to the computer age, it has retained its popularity and can be found in every data book describing passive and active high-frequency components and systems. Almost all computer-aided design programs utilize the Smith chart for the analysis of circuit impedances, design of matching networks, and computations of noise figures, gain, and stability circles. Even instruments such as the ubiquitous network analyzer have the option to represent certain measurement data in a Smith chart format.
Industry:Science
A graphical relationship between a set of variables that are related by a mathematical equation or law. The fundamental principle involved in the construction of a nomographic or alignment chart consists of representing an equation containing three variables, <i>f</i>(<i>u</i>,υ,<i>w</i>) = 0, by means of three scales in such a manner that a straight line cuts the three scales in values of <i>u</i>, υ, and <i>w</i>, satisfying the equation. The cutting line is called the isopleth or index line. Numbers may be quickly and easily read from the scales of such a chart even by one unfamiliar with the construction of the chart and the equation involved. <b>Figure 1</b> illustrates such an example. Assume that it is desired to find the value of <i>E</i> when <i>D</i> = 2 and <i>Q</i> 50. Lay a straightedge through 50 on the <i>Q</i> scale and through 2 on the <i>D</i> scale and read 11. 8 at its intersection with the <i>E</i> scale. As another example, it might be desired to know what value or values of <i>D</i> should be used if <i>E</i> and <i>Q</i> are required to be 10 and 60, respectively. A straightedge through <i>E</i> = 10 and <i>Q</i> = 60 cuts the <i>D</i> scale in two points, <i>D</i> = 2. 8 and 9.4. This is equivalent to finding two positive roots of the cubic equation <i>D</i><sup>3</sup> − 10<i>D</i><sup>2</sup> + 56. 25 = 0. It is assumed that <i>g</i> = 32 ft/s<sup>2</sup> in this equation.
Industry:Science
A graphical technique for determining whether a process is or is not in a state of statistical control. Being in statistical control means that the extent of variation of the output of the process does not exceed that which is expected on the basis of the natural statistical variability of the process. Several main types of control charts are used, based on the nature of the process and on the intended use of the data.
Industry:Science
A great ocean current transporting about 7 × 10<sup>7</sup> tons (6.3 × 10<sup>7</sup> metric tons) of water per second (1000 times the discharge of the Mississippi River) northward from the latitude of Florida to the Grand Banks off Newfoundland. Before the days of scientific oceanography, it was supposed that the origin of the water in the Gulf Stream was the Gulf of Mexico. The origin has since been traced farther upstream, through the Gulf of Mexico and Caribbean, to the Great North and South Equatorial currents of the Atlantic. The Gulf Stream is thought of now as a portion of a great horizontal circulation in the ocean, where particles of water execute closed circuits, sometimes moving slowly in mid-ocean regions and other times rapidly in strong currents like the Gulf Stream. Thus the beginning and end of the Stream have arbitrary geographical limits.
Industry:Science
A grinding and pulverizing machine consisting of a shell or drum rotating on a horizontal axis. The material to be reduced in size is fed into one end of the mill. The mill is also charged with grinding material such as iron balls. As the mill rotates, the material and grinding balls tumble against each other, the material being broken chiefly by attrition.
Industry:Science
A grinding machine in which balls rotate under pressure to crush materials, such as coal, to a fine consistency. The material is usually fed through a chute to the inside of a ring of closely spaced balls. In most designs the upper spring-loaded race applies pressure to the balls, and the lower race rotates and grinds the coarse material between it and the balls (see <b>illus.</b>). The finely ground material discharges along the outer periphery of the ball races. For the pulverization of coal, hot air, introduced between the lower race and the pulverizer housing, lifts or carries the fines to a cyclone classifier at the center of the pulverizer. There the finer particles discharge from the pulverizer while the larger particles return to the grinding zone for further reduction in size. Two or more rings of balls can be cascaded in one machine to obtain greater capacity or output. Counterrotating top and bottom rings also are used to increase pulverizer capacity. Such pulverizers are compact and the power required per ton of material ground is relatively low.
Industry:Science
A ground mapping system that uses analog radar equipment to provide surveillance of aircraft and other surface vehicles on an airport surface. It is used by air-traffic controllers in airport control towers to monitor and control the movement of aircraft and vehicles. A situation display of the targets includes a map identifying the runways and taxiways and a visual map of the airport features, created through the contrast on the radar display resulting from the absence of returns from smooth concrete surfaces and the ground-clutter returns from grassy areas. An important safety function of the airport surface detection equipment (ASDE) is to determine whether or not a runway is clear for the next departure or arrival operation. The prevention of runway incursions by aircraft or by service vehicles has become more urgent because of several incidents since 2003. This runway clearance determination is aided by the ASDE's capability to display an image of the aircraft in which the target's extremities (nose, tails, and wing tips), especially for large aircraft, are evident to the eye.
Industry:Science
A ground tissue chiefly concerned with the manufacture and storage of food. The primary functions of plants, such as photosynthesis, assimilation, respiration, storage, secretion, and excretion—those associated with living protoplasm—proceed mainly in parenchymal cells. Parenchyma is frequently found as a homogeneous tissue in stems, roots, leaves, and flower parts. Other tissues, such as sclerenchyma, xylem, and phloem, seem to be embedded in a matrix of parenchyma; hence the use of the term ground tissue with regard to parenchyma is derived. The parenchymal cell is one of the most frequently occurring cell types in the plant kingdom.
Industry:Science
A ground vehicle propelled by a motor that is powered by electrical energy from rechargeable batteries or other source onboard the vehicle, or from an external source in, on, or above the roadway. Examples are the golf cart, industrial truck and tractor, automobile, delivery van and other on-highway truck, and trolley bus. In common usage, electric vehicle refers to an automotive vehicle in which the propulsion system converts electrical energy stored chemically in a battery into mechanical energy to move the vehicle. This is classed as a battery-only-powered electric vehicle. The other major class is the hybrid-electric vehicle, which has more than one power source.
Industry:Science
