Disk Scheduling Algorithms: FIFO, SSF, SCAN, C-SCAN
Disk Scheduling Algorithms
A. B. C. D. E. F. G. H.
seek: 0. 0. 0. 0. 8. 8. 8. 14.
cyl req 12. 4. 10 2. 20. 3. 17. 4
If these requests are served in FIFO order, then the following sequence of seeks ensues:
At time 0, requests A, B, C, and D arrive. To serve A, we seek 4 cylinders outward from 8 to 12. At time 4, we seek 8 cylinders inward to reach cylinder 4 and serve B (meanwhile E, F, G arrive). At time 12, we seek 6 cylinders outward to 10 to serve C (meanwhile H arrives).
At time 18, we seek 8 cylinders
Read MoreUnderstanding Cuts and Sections in Technical Drawing
Cuts and Sections in Technical Drawing
Court: Is the artifice by which, in the representation of a piece, we remove part of it to clarify and make easier its representation and dimensioning.
Section: Intersection of a cutting plane with a part (the area indicated in red). As seen when rendering a section, unlike a cut, it does not render the rest of the piece that is behind it. Whenever possible, we prefer to represent the section as it is a clearer and simpler representation.
Types of Cuts
- Total Cut:
Mechanical Fasteners and Dimensioning Standards
Dimensions
Dimensions should be placed in the most descriptive view of the feature being dimensioned. A feature should be dimensioned only once. Each feature should be dimensioned or identified with a note. Dimension features or surfaces should be done to a logical reference point. Center lines or center marks should be used on all circles, holes, and slots. Arrowheads are used to terminate dimension lines. The point of the arrowheads on the leader line must make contact with the feature line.
Staggered
Read MoreMechanical Fasteners and Dimensioning Standards
Dimensioning Standards
Dimensions should be placed in the most descriptive view of the feature being dimensioned. A feature should be dimensioned only once. Each feature should be dimensioned or identified with a note. Dimension features or surfaces should be done to a logical reference point. Center lines or center marks should be used on all circles, holes, and slots. Arrowheads are used to terminate dimension lines. The point of the arrowheads on the leader line must make contact with the feature
Read MoreEngineering Drawing: Essential Concepts and Techniques
Unit 6: Development of Surfaces
1. What is the Significance of Development?
Development is a graphical method of obtaining the area of the surfaces of a solid. In engineering, many objects cannot be manufactured by conventional manufacturing processes because of their size and shape. Thus, they are fabricated using the development phenomenon from metal sheets. Some examples include boiler shells and chimneys, pressure vessels, shovels, trays, boxes and cartons, feeding hoppers, large pipe sections,
Read MoreEngineering Drawings and Design Development
Drawing Types and Scales
In engineering, most design information is shown on drawings. Today, drawings are generally not drawn by hand. They are produced on a computer, using CAD (Computer-Aided Design) systems.
A key factor on a drawing is the scale – that is, the size of items on the drawing in relation to their real size. When all the items on a drawing are shown relative to their real size, the drawing is drawn to scale and can be called a scale drawing. An example of a scale is 1:10 (one to ten)
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