Definitions

flow

turbulent flow

Fluid flow in which the fluid undergoes irregular fluctuations, or mixing. The speed of the fluid at a point is continuously undergoing changes in magnitude and direction, which results in swirling and eddying as the bulk of the fluid moves in a specific direction. Common examples of turbulent flow include atmospheric and ocean currents, blood flow in arteries, oil transport in pipelines, lava flow, flow through pumps and turbines, and the flow in boat wakes and around aircraft wing tips.

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Fluid flow in which the fluid travels smoothly or in regular paths. The velocity, pressure, and other flow properties at each point in the fluid remain constant. Laminar flow over a horizontal surface may be thought of as consisting of thin layers, all parallel to each other, that slide over each other. It is common only where the flow channel is relatively small, the fluid is moving slowly, and its viscosity is relatively high. Examples include the flow of oil through a thin tube and blood flow through capillaries. Seealso turbulent flow.

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Introduction of genetic material (by interbreeding) from one population of a species to another, thereby changing the composition of the gene pool of the receiving population. The introduction of new characteristics through gene flow increases variability within the population and makes possible new combinations of traits. In humans, gene flow usually comes about through human migration.

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Graphical representation of a process, such as a manufacturing operation or a computer operation, indicating the various steps taken as the product moves along the production line or the problem moves through the computer. Individual operations can be represented by closed boxes, with arrows between boxes indicating the order in which the steps are taken and divergent paths determined by variable results.

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Alteration in size or shape of a body under the influence of mechanical forces. Flow is a change in deformation that continues as long as the force is applied. Gases and liquids normally flow relatively freely, while solids deform when subjected to forces. Most solids initially deform elastically (see elasticity), though rigid material such as metals, concrete, or rocks can sustain large forces while undergoing little deformation. If enough force is applied, even these materials will reach their elastic limit, at which point brittle substances fracture while ductile materials (see ductility) rearrange their internal structure, the result being plastic deformation (see plasticity).

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Sea basin, Orkney Islands, Scotland. Located off of Scotland's northern tip, the basin is about 15 mi (24 km) long and 8 mi (13 km) wide. Its extensive sheltered waters served as a major British naval base during World Wars I and II. The Germans scuttled their fleet there after World War I. The base was fortified in World War II following German attacks and the sinking of the battleship Royal Oak in 1939. The base closed in 1956.

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FLOW-MATIC, originally known as B-0, is possibly the first English-like Data Processing language. It was invented and specified by Grace Hopper, and development of the commercial variant started at Remington Rand in 1955 for the UNIVAC I. By 1958, the compiler and its documentation were generally available and being used commercially.

Contributions to COBOL

Flow-Matic was a major influence in the design of COBOL.

Several elements of Flow-Matic were incorporated into COBOL:

  • Defining Files in advance, and separating into INPUT and OUTPUT files.
  • Qualification of data-names (IN or OF clause).
  • IF END OF DATA (AT END) clause on file READ operations.
  • Figurative constant ZERO (originally ZZZ...ZZZ, where number of Z's indicated precision).
  • Dividing the program into sections, separating different parts of the program. Flow-Matic sections included Computer (Environment Division), Directory (Data Division), and Compiler (Procedure Division).

Sample Program

A sample FLOW-MATIC program (See text below.)
 0) INPUT  INVENTORY FILE=A
          PRICE FILE=B,
   OUTPUT PRICED-INV FILE=C
          UNPRICED-INV FILE=D,
   HSP D.
1) COMPARE PRODUCT-NO(A) WITH PRODUCT-NO(B)
   IF GREATER GO TO OPERATION 10;
   IF EQUAL GO TO OPERATION 5;
   OTHERWISE GO TO OPERATION 2.
2) TRANSFER A TO D.
3) WRITE ITEM D.
4) JUMP TO OPERATION 8.

5) TRANSFER A TO C.
6) MOVE UNIT-PRICE(B) TO UNIT-PRICE(C).
7) WRITE ITEM C.
8) READ ITEM B; IF END OF DATA GO TO OPERATION 12.
9) JUMP TO OPERATION 1.

10) READ ITEM B; IF END OF DATA GO TO OPERATION 12. 11) JUMP TO OPERATION 1.

12) SET OPERATION 9 TO GO TO OPERATION 2. 13) JUMP TO OPERATION 2.

14) TEST PRODUCT-NO(B) AGAINST ZZZZZZZZZZZZ;

   IF EQUAL GO TO OPERATION 16;
   OTHERWISE GO TO OPERATION 15.
15) REWIND B. 16) CLOSE-OUT FILES C, D. 17) STOP. (END)

References

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