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Spm ap-network model-

Assistant Professor at Vellore Institute Of Technology um Vellore Institute Of Technology
6. Jan 2016
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Spm ap-network model-

  1. SPM-UNIT II ACTIVITY PLANNING Prof. Kanchana Devi
  2. Network Planning Models Prof. Kanchana Devi 2  Scheduling techniques model the project’s activ ities and their relationships as a “Network”.  In network time flows from left to right  These techniques were developed in 1950’s  There are two best techniques:  CPM (Critical Path Method)  PERT (Program Evaluation Review Technique)  Both uses an “activity-on-arrow” approach  Activities are drawn as arrows joining circles, or nodes  Which show the start and completion time of the activities
  3. Precedence Network Prof. Kanchana Devi 3  Recently used , Popular one  It uses “activity-on-node” networks  Where activities are represented as nodes  Links between the nodes are represented as sequencing requirements.
  4. Formulating a Network Model Prof. Kanchana Devi 4  First stage:  Representing the activities and their relationships as graph.  In “Activity-on-node”  Representing the activities as nodes(boxes) and the lines between nodes represent the dependencies.
  5. Rules:Constructing Precedence Network Prof. Kanchana Devi 5  A project network should have only one start node  A project network should have only one end node  A node has a duration  Links normally have no duration  Precedents are the immediate preceding activities  Time moves from left to right  A network may not contain loops  A network should not contain dangles
  6. Fragment of precedence Network Prof. Kanchana Devi 6 Install Program Test Data Take-on Code
  7. A loop represents an impossible sequence Prof. Kanchana Devi 7 Code Program Release Program Test Program Diagnose Errors Correct Errors
  8. A Dangle Prof. Kanchana Devi 8 Design Program Install Program Test Program Code Program Write User Manual
  9. Resolving the Dangle Prof. Kanchana Devi 9 Design Program Install Program Test Program Code Program Write User Manual Sign-Off
  10. Representing Lagged Activities Prof. Kanchana Devi 10  Undertake two activities in parallel as there is a lag between two.  Activities are lagged because a stage in one activity must be completed before the other may proceed.  Show each stage as separate activity.
  11. Adding Time Dimension Prof. Kanchana Devi 11  Each activity have an estimate of its duration.  Forward pass – Earliest dates at which activities may commence and project be completed.  Backward pass – Latest start dates for activities and critical path.
  12. Project Specification Prof. Kanchana Devi 12
  13. Project Activity Network Prof. Kanchana Devi 13
  14. Project Activity Network represented as CPM Network Prof. Kanchana Devi 14
  15. Dummy activities 15  When two paths within a network have a common event to occur.  It is incorrect to require both hardware specification and data structure design
  16. Using Dummy Activities Prof. Kanchana Devi 16
  17. ……. Prof. Kanchana Devi 17  Dummy activities shown as dotted lines have a zero duration and use no resources.  Use of dummy activity where two activities share the same start and end nodes makes it easier to distinguish activity end points.
  18. Forward Pass Prof. Kanchana Devi 18 Activity Duration (Weeks) Earliest Start Date (Weeks) Earliest Finish Date(Weeks) A 6 0 6 B 4 0 4 C 3 6 9 D 4 4 8 E 3 4 7 F 10 0 10 G 3 10 13 H 2 9 11
  19. CPM Network Prof. Kanchana Devi 19
  20. A CPM Network after forward pass Prof. Kanchana Devi 20
  21. Activity table for forward pass Prof. Kanchana Devi 21 Activity Duration (weeks) Earliest Start Date Latest Start Date Earliest Finish Date Latest Finish Date Total Float A 6 0 6 B 4 0 4 C 3 6 9 D 4 4 8 E 3 4 7 F 10 0 10 G 3 10 13 H 2 9 11
  22. Backward Pass Prof. Kanchana Devi 22
  23. CPM Network after the backward pass Prof. Kanchana Devi 23
  24. Identifying the Critical Path Prof. Kanchana Devi 24  Any delay on the critical path will delay the project.  Difference between earliest and latest date for an event is known as slack.  Event with slack of zero is critical as any delay in achieving that event will delay the completion date of the project.
  25. Critical Path Prof. Kanchana Devi 25 Event Number Latest Date Earliest Date Slack
  26. Activity Float Prof. Kanchana Devi 26  As events have slack, activities possess float.  Total float is the difference between earliest start and latest start ( or difference between earliest finish and latest finish)
  27. Activity Schedule showing total float for each activity Prof. Kanchana Devi 27
  28. Activity Schedule Prof. Kanchana Devi 28 Actvity Name Time Actvity Name Time 1-2 A 4 5-6 G 4 1-3 B 1 5-7 H 8 2-4 C 1 6-8 I 1 3-4 D 1 7-8 J 2 3-5 E 6 8-10 K 5 4-9 F 5 9-10 L 7
  29. Activity Network Diagram Prof. Kanchana Devi 29 1 2 3 5 4 7 6 8 109
  30. Solution Prof. Kanchana Devi 30 Activity Activity Name Normal Time E.S E.F L.S L.F Total Float 1-2 A 4 0 4 5 9 5 1-3 B 1 0 1 0 1 0 2-4 C 1 4 5 9 10 5 3-4 D 1 1 2 9 10 8 3-5 E 6 1 7 1 7 0 4-9 F 5 5 10 10 15 5 5-6 G 4 7 11 12 16 5 5-7 H 8 7 15 7 15 0 6-8 I 1 11 12 16 17 5 7-8 J 2 15 17 15 17 0 8-10 K 5 17 22 17 22 0 9-10 L 7 10 17 15 22 5
  31. Problem 1 Prof. Kanchana Devi 31  Draw activity network of the project.  Find total float of each activity. Activity Time inWeeks 1-2 20 1-3 25 2-3 10 2-4 12 3-4 5 3-5 10
  32. Problem 2 Prof. Kanchana Devi 32  Find out the critical path and total float. Activity Immediate Predecessor Time A 3 B 8 C 5 D A 9 E C 2 F B,E 6 H B,E 12 G D 11
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