Encyclopedia of computer science and technology / Harry Henderson.—Rev. ed. p. cm. Includes bibliographical references and index. PDF | On Sep 30, , Hans-Werner Gottinger and others published Encyclopedia of Computer Science and Technology. general-purpose computer to much better than 1 millisecond ( s) or to deliver Standards and Technology [UTC(NIST)] and by the U.S. Naval Observatory.

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ter technologies continually implement new computer con- sumer products. A . Ralston and E. Reilly, Encyclopedia of Computer Science. bestthing.info 8. Encyclopedia of Computer Science and Technology bridges the gap between scanty "computer glossaries" with brief definitions and dense multivolume. Computer science handbook / editor-in-chief, Allen B. Tucker—2nd ed. p. cm. .. in computer graphics, software technology, and parallelism. The s saw would not have appeared in such an encyclopedia even ten years ago. We begin .

CAD systems also offer "zoom" features analogous to a camera lens, whereby a designer can magnify certain elements of a model to facilitate inspection. Computer models are typically three dimensional and can be rotated on any axis, much as one could rotate an actual three dimensional model in one's hand, enabling the designer to gain a fuller sense of the object.

CAD systems also lend themselves to modeling cutaway drawings, in which the internal shape of a part is revealed, and to illustrating the spatial relationships among a system of parts.

CAD systems have no means of comprehending real-world concepts, such as the nature of the object being designed or the function that object will serve.

CAD systems function by their capacity to codify geometrical concepts. Thus the design process using CAD involves transferring a designer's idea into a formal geometrical model.

Efforts to develop computer-based "artificial intelligence" AI have not yet succeeded in penetrating beyond the mechanical—represented by geometrical rule-based modeling.

Other limitations to CAD are being addressed by research and development in the field of expert systems. This field is derived from research done in AI. One example of an expert system involves incorporating information about the nature of materials—their weight, tensile strength, flexibility, and so on—into CAD software. By including this and other information, the CAD system could then "know" what an expert engineer knows when that engineer creates a design.

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The system could then mimic the engineer's thought pattern and actually "create" more of the design. Expert systems might involve the implementation of more abstract principles, such as the nature of gravity and friction, or the function and relation of commonly used parts, such as levers or nuts and bolts.

Such futuristic concepts, however, are all highly dependent on our abilities to analyze human decision processes and to translate these into mechanical equivalents if possible. One of the key areas of development in CAD technologies is the simulation of performance.

Among the most common types of simulation are testing for response to stress and modeling the process by which a part might be manufactured or the dynamic relationships among a system of parts. In stress tests, model surfaces are shown by a grid or mesh, that distort as the part comes under simulated physical or thermal stress.

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Dynamics tests function as a complement or substitute for building working prototypes. The ease with which a part's specifications can be changed facilitates the development of optimal dynamic efficiencies, both as regards the functioning of a system of parts and the manufacture of any given part.

Simulation is also used in electronic design automation, in which simulated flow of current through a circuit enables the rapid testing of various component configurations.

The processes of design and manufacture are, in some sense, conceptually separable. Yet the design process must be undertaken with an understanding of the nature of the production process.

It is necessary, for example, for a designer to know the properties of the materials with which the part might be built, the various techniques by which the part might be shaped, and the scale of production that is economically viable.

The conceptual overlap between design and manufacture is suggestive of the potential benefits of CAD and CAM and the reason they are generally considered together as a system. Another important trend is toward the establishment of a single CAD-CAM standard, so that different data packages can be exchanged without manufacturing and delivery delays, unnecessary design revisions, and other problems that continue to bedevil some CAD-CAM initiatives.

Finally, CAD-CAM software continues to evolve in such realms as visual representation and integration of modeling and testing applications.

Before the true power of computing could be realized, therefore, the naive view of calculation had to be overcome.

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The inventors who laboured to bring the computer into the world had to learn that the thing they were inventing was not just a number cruncher, not merely a calculator. For example, they had to learn that it was not necessary to invent a new computer for every new calculation and that a computer could be designed to solve numerous problems, even problems not yet imagined when the computer was built.

They also had to learn how to tell such a general problem-solving computer what problem to solve. In other words, they had to invent programming. They had to solve all the heady problems of developing such a device, of implementing the design, of actually building the thing. The history of the solving of these problems is the history of the computer.

That history is covered in this section, and links are provided to entries on many of the individuals and companies mentioned. In addition, see the articles computer science and supercomputer. Early history The abacus The earliest known calculating device is probably the abacus. It dates back at least to bce and is still in use today, particularly in Asia.

Encyclopedia of Computer Science and Technology

Now, as then, it typically consists of a rectangular frame with thin parallel rods strung with beads. Long before any systematic positional notation was adopted for the writing of numbers, the abacus assigned different units, or weights, to each rod. This scheme allowed a wide range of numbers to be represented by just a few beads and, together with the invention of zero in India, may have inspired the invention of the Hindu-Arabic number system.

In any case, abacus beads can be readily manipulated to perform the common arithmetical operations—addition, subtraction, multiplication, and division—that are useful for commercial transactions and in bookkeeping. The abacus is a digital device; that is, it represents values discretely. A bead is either in one predefined position or another, representing unambiguously, say, one or zero. As any person can attest, adding two digit numbers is much simpler than multiplying them together, and the transformation of a multiplication problem into an addition problem is exactly what logarithms enable.

This simplification is possible because of the following logarithmic property: the logarithm of the product of two numbers is equal to the sum of the logarithms of the numbers. By , tables with 14 significant digits were available for the logarithms of numbers from 1 to 20,, and scientists quickly adopted the new labour-saving tool for tedious astronomical calculations.

Most significant for the development of computing, the transformation of multiplication into addition greatly simplified the possibility of mechanization. In Edmund Gunter , the English mathematician who coined the terms cosine and cotangent, built a device for performing navigational calculations: the Gunter scale, or, as navigators simply called it, the gunter. That first slide rule was circular, but Oughtred also built the first rectangular one in The analog devices of Gunter and Oughtred had various advantages and disadvantages compared with digital devices such as the abacus.

What is important is that the consequences of these design decisions were being tested in the real world.

Digital calculators: from the Calculating Clock to the Arithmometer In the German astronomer and mathematician Wilhelm Schickard built the first calculator. He described it in a letter to his friend the astronomer Johannes Kepler , and in he wrote again to explain that a machine he had commissioned to be built for Kepler was, apparently along with the prototype , destroyed in a fire.

He called it a Calculating Clock , which modern engineers have been able to reproduce from details in his letters.

A century earlier, Leonardo da Vinci sketched plans for a calculator that were sufficiently complete and correct for modern engineers to build a calculator on their basis. The first calculator or adding machine to be produced in any quantity and actually used was the Pascaline, or Arithmetic Machine , designed and built by the French mathematician-philosopher Blaise Pascal between and To solve any real problem, we must give some semantic interpretation.

The integration of telecommunications with computing allowed people in remote places such as branch offices to use computers located in distant parts of their organization. This is a characteristic feature of software development Vliet Does the medium of the array fix the correct use of stacks? The first category covers applications that require the organization, storage, and retrieval of large amounts of information such as library catalogs or bank records.

In addition to climate change, the editors have attempted to strengthen the GES 5th edition's coverage of emerging diseases. Are these two notions at odds with each other?

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