A little bit of engineering (562404), страница 21

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Engineers work on control systems ranging from the everyday, passenger-actuated, as those that run an elevator, to the exotic, as systems for keeping spacecraft on course. Control systems are used extensively in aircraft and ships, in military fire-control systems, in power transmission and distribution, in automated manufacturing, and in robotics.

Engineers have been working to bring about two revolutionary changes in the field of communications and control: Digital systems are replacing analog ones at the same time that fiber optics are superseding copper cables. Digital systems offer far greater immunity to electrical noise. Fiber optics are likewise immune to interference; they also have tremendous carrying capacity, and are extremely light and inexpensive to manufacture.

Virtually unknown just a few decades ago, computer engineering is now among the most rapidly growing fields. The electronics of computers involve engineers in design and manufacture of memory systems, of central processing units, and of peripheral devices (see Computer). Foremost among the avenues now being pursued are the design of Very Large Scale Integration (VLSI) and new computer architectures. The field of computer science is closely related to computer engineering; however, the task of making computers more “intelligent” (artificial intelligence,), through creation of sophisticated programs or development of higher level machine languages or other means, is generally regarded as being in the realm of computer science.

One current trend in computer engineering is microminiaturization. Using VLSI, engineers continue to work to squeeze greater and greater numbers of circuit elements onto smaller and smaller chips. Another trend is toward increasing the speed of computer operations through use of parallel processors, superconducting materials, and the like.

This branch of engineering includes activities related to the discovery and exploration of mineral deposits and the financing, construction, development, operation, recovery, processing, purification, and marketing of crude minerals and mineral products. The mining engineer is trained in historical geology, mineralogy, paleontology, and geophysics, and employs such tools as the seismograph and the magnetometer for the location of ore or petroleum deposits beneath the surface of the earth (see Petroleum; Seismology). The surveying and drawing of geological maps and sections is an important part of the work of the engineering geologist, who is also responsible for determining whether the geological structure of a given location is suitable for the building of such large structures as dams.

This field pertains to the efficient use of machinery, labor, and raw materials in industrial production. It is particularly important from the viewpoint of costs and economics of production, safety of human operators, and the most advantageous deployment of automatic machinery.

Engineers in this field design, test, build, and operate machinery of all types; they also work on a variety of manufactured goods and certain kinds of structures. The field is divided into (1) machinery, mechanisms, materials, hydraulics, and pneumatics; and (2) heat as applied to engines, work and energy, heating, ventilating, and air conditioning. The mechanical engineer, therefore, must be trained in mechanics, hydraulics, and thermodynamics and must be fully grounded in such subjects as metallurgy and machine design. Some mechanical engineers specialize in particular types of machines such as pumps or steam turbines. A mechanical engineer designs not only the machines that make products but the products themselves, and must design for both economy and efficiency. A typical example of the complexity of modern mechanical engineering is the design of an automobile, which entails not only the design of the engine that drives the car but also all its attendant accessories such as the steering and braking systems, the lighting system, the gearing by which the engine's power is delivered to the wheels, the controls, and the body, including such details as the door latches and the type of seat upholstery.

This branch is concerned with the application of the engineering sciences to military purposes. It is generally divided into permanent land defense (see Fortification and Siege Warfare) and field engineering. In war, army engineer battalions have been used to construct ports, harbors, depots, and airfields. In the U.S., military engineers also construct some public works, national monuments, and dams (see Army Corps of Engineers).

Military engineering has become an increasingly specialized science, resulting in separate engineering subdisciplines such as ordnance, which applies mechanical engineering to the development of guns and chemical engineering to the development of propellants, and the Signal Corps, which applies electrical engineering to all problems of telegraph, telephone, radio, and other communication.

Engineers who have the overall responsibility for designing and supervising construction of ships are called naval architects. The ships they design range in size from ocean-going supertankers as much as 1300 feet long to small tugboats that operate in rivers and bays. Regardless of size, ships must be designed and built so that they are safe, stable, strong, and fast enough to perform the type of work intended for them. To accomplish this, a naval architect must be familiar with the variety of techniques of modern shipbuilding, and must have a thorough grounding in applied sciences, such as fluid mechanics, that bear directly on how ships move through water.

Marine engineering is a specialized branch of mechanical engineering devoted to the design and operation of systems, both mechanical and electrical, needed to propel a ship. In helping the naval architect design ships, the marine engineer must choose a propulsion unit, such as a diesel engine or geared steam turbine, that provides enough power to move the ship at the speed required. In doing so, the engineer must take into consideration how much the engine and fuel bunkers will weigh and how much space they will occupy, as well as the projected costs of fuel and maintenance. See also Ships and Shipbuilding.

This branch of engineering is concerned with the design and construction of nuclear reactors and devices, and the manner in which nuclear fission may find practical applications, such as the production of commercial power from the energy generated by nuclear reactions and the use of nuclear reactors for propulsion and of nuclear radiation to induce chemical and biological changes. In addition to designing nuclear reactors to yield specified amounts of power, nuclear engineers develop the special materials necessary to withstand the high temperatures and concentrated bombardment of nuclear particles that accompany nuclear fission and fusion. Nuclear engineers also develop methods to shield people from the harmful radiation produced by nuclear reactions and to ensure safe storage and disposal of fissionable materials. See Nuclear Energy.

This field of engineering has as its object the prevention of accidents. In recent years safety engineering has become a specialty adopted by individuals trained in other branches of engineering. Safety engineers develop methods and procedures to safeguard workers in hazardous occupations. They also assist in designing machinery, factories, ships, and roads, suggesting alterations and improvements to reduce the likelihood of accident. In the design of machinery, for example, the safety engineer seeks to cover all moving parts or keep them from accidental contact with the operator, to put cutoff switches within reach of the operator, and to eliminate dangerous projecting parts. In designing roads the safety engineer seeks to avoid such hazards as sharp turns and blind intersections, known to result in traffic accidents. Many large industrial and construction firms, and insurance companies engaged in the field of workers compensation, today maintain safety engineering departments. See Industrial Safety; National Safety Council.

This is a branch of civil engineering, but because of its great importance for a healthy environment, especially in dense urban-population areas, it has acquired the importance of a specialized field. It chiefly deals with problems involving water supply, treatment, and distribution; disposal of community wastes and reclamation of useful components of such wastes; control of pollution of surface waterways, groundwaters, and soils; milk and food sanitation; housing and institutional sanitation; rural and recreational-site sanitation; insect and vermin control; control of atmospheric pollution; industrial hygiene, including control of light, noise, vibration, and toxic materials in work areas; and other fields concerned with the control of environmental factors affecting health. The methods used for supplying communities with pure water and for the disposal of sewage and other wastes are described separately. See Plumbing; Sewage Disposal; Solid Waste Disposal; Water Pollution; Water Supply and Waterworks.

Scientific methods of engineering are applied in several fields not connected directly to manufacture and construction. Modern engineering is characterized by the broad application of what is known as systems engineering principles. The systems approach is a methodology of decision-making in design, operation, or construction that adopts (1) the formal process included in what is known as the scientific method; (2) an interdisciplinary, or team, approach, using specialists from not only the various engineering disciplines, but from legal, social, aesthetic, and behavioral fields as well; (3) a formal sequence of procedure employing the principles of operations research.

In effect, therefore, transportation engineering in its broadest sense includes not only design of the transportation system and building of its lines and rolling stock, but also determination of the traffic requirements of the route followed. It is also concerned with setting up efficient and safe schedules, and the interaction of the system with the community and the environment. Engineers in industry work not only with machines but also with people, to determine, for example, how machines can be operated most efficiently by the workers. A small change in the location of the controls of a machine or of its position with relation to other machines or equipment, or a change in the muscular movements of the operator, often results in greatly increased production. This type of engineering work is called time-study engineering.

A related field of engineering, human-factors engineering, also known as ergonomics, received wide attention in the late 1970s and the '80s when the safety of nuclear reactors was questioned following serious accidents that were caused by operator errors, design failures, and malfunctioning equipment. Human-factors engineering seeks to establish criteria for the efficient, human-centered design of, among other things, the large, complicated control panels that monitor and govern nuclear reactor operations.

Among various recent trends in the engineering profession, licensing and computerization are the most widespread. Today, many engineers, like doctors and lawyers, are licensed by the state. Approvals by professionally licensed engineers are required for construction of public and commercial structures, especially installations where public and worker safety is a consideration. The trend in modern engineering offices is overwhelmingly toward computerization. Computers are increasingly used for solving complex problems as well as for handling, storing, and generating the enormous volume of data modern engineers must work with.

The National Academy of Engineering, founded in 1964 as a private organization, sponsors engineering programs aimed at meeting national needs, encourages new research, and is concerned with the relationship of engineering to society.

Defense Systems

Defense Systems, combination of electronic warning networks and military strategies designed to protect a country from a strategic missile or bomber attack. Defense systems use radar and satellite detection systems to monitor a nation’s airspace, providing data that would allow defense forces to detect and coordinate against such an attack. Several large countries, including the United States, also maintain an arsenal of offensive nuclear weapons as a deterrent to a nuclear attack.

Modern defense systems originated during World War II (1939-1945) in response to the advent of long-range bomber aircraft. Radar stations in Great Britain were installed to detect approaching German bombers and give British fighter aircraft time to intercept the enemy. Before World War II, most nations focused national defense against assaults from land or sea.

After World War II, the United States enjoyed a brief period of military superiority as the sole possessor of nuclear weapons, but the detonation of the first Soviet atomic bomb in 1949 brought a new military threat. The United States began to focus its defenses on early detection of long-range bombers, to give U.S. fighter aircraft enough time to respond to a large-scale attack.

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