Lecture - Project, Planning and Control.pdf
- 1. UNIT 4 System Schedule ME 342 A System Design and Analysis Dr. Kailash Chaudhary Ph.D. (Mechanical Design), M.E. (P & I), B.E. (Mechanical Engg) Assistant Professor Department of Mechanical Engineering MBM University Jodhpur
- 2. 2 Project Planning, Scheduling and Control Project a set of partially ordered, interrelated activities that must be completed to achieve a goal.
- 3. 3 Network Models PERT Program Evaluation and Review Technique probabilistic features CPM Critical Path Method cost/time trade-offs project scheduler
- 4. 4 Objectives Planning, scheduling, and control of complex projects Find critical activities to manage resources (management by exception) Determine flexibility of non-critical activities (slack) Estimate earliest completion time of project Determine time cost trade-offs
- 5. 5 Service Industry Distribution Industry Producing Industry Business and Industry a taxonomy Raw materials Continuous Processing Discrete Products Mining Drilling Farming Construction Manufacturing Chemicals Food Refinery Batch Mass Processing Production
- 6. 6 Production Systems Job shops Flow shops Batch production Mass production Cellular manufacturing Project Shop Continuous Processing Gosh. Can you tell us more about these?
- 7. 7 Project Shop single product in fixed location material and labor brought to the site usually job shop/flow shop associated functionalized production system examples include construction and shipbuilding
- 8. 8 The Elements of Project Scheduling Project Definition. Statement of project, goals, and resources required. Activity Definitions. Content and requirements of each activity. Project Scheduling. Specification of starting and ending times of all activities. Project Monitoring. Keeping track of the progress of the project.
- 9. 9 Definitions Activity an effort (task) that requires resources and takes a certain amount of time. Event a specific accomplishment or milestone (the start or finish of an activity). Project a collection of activities and events leading to a definable goal. Network a graphical representation of a project depicting the precedence relationships among the activities and events. Critical Activity an activity that if delayed will hold up the scheduled completion of a project. Critical Path the sequence of critical activities that forms a continuous path from the start of a project to its completion.
- 10. 10 Framework for Analysis Analyze project in terms of activities and events Determine sequence (precedence) of activities (develop network) Assign estimates of time, cost, and resources to all activities Identify the critical path monitor, evaluate, and control progress of project
- 11. 11 Network Representation Projects may be represented as networks with: Arrows representing activities. Nodes representing completion of a set of activities (milestones). Pseudo activities may be required to satisfy precedence relationships.
- 12. 12 Network Development 1 2 3 events (nodes) activities (arcs) Activities have duration and may have precedence. Define activities in terms of their beginning and ending events. e.g. Activity 1-2 must precede Activity 2-3
- 13. 13 Network Development (continued) 1 2 3 4 Event 1 is start of project Activities 1-2, 1-3, and 1-4 have no predecessors and may start simultaneously
- 14. 14 Network Development (continued) n-2 n-3 n n-1 Event n is the end of the project. Activities (n-3 n, (n-2) n, and (n-1) - n must be completed for the project to be completed.
- 15. 15 Network Development (continued) 6 7 8 9 Activities 6-7, 6-8, and 6-9 cannot start until activity 5-6 has been completed. 5 burst event
- 16. 16 Network Development (continued) 8 5 6 7 Activities 5-8, 6-8, and 7-8 must be completed before activity 8-9 may begin. 9 merge event
- 17. 17 Network Development (continued) 8 5 6 7 Activities 5-8, 6-8, and 7-8 must be completed before activity 8-9, 8-10, or 8-11 may begin. 9 10 11 Gosh! A combined merge and burst event. Are these rare or what?
- 18. 18 Dummy activity A C A D B D W R O N G 7 5 6 9 10 A B C D 7 5 6 9 10 A B D C 8 dummy has no resources and no duration
- 19. 19 Project Networks Collection of nodes and arcs Depicted graphically Events are uniquely numbered Arcs are labeled according to their beginning and ending events Ending events always have higher numbers than beginning events Two activities cannot have the same beginning and ending events Activity lengths have no significance
- 20. 20 Our Very Own Example product development activity description precedence A design promotion campaign - B initial pricing - C product design - D promotion cost analysis A E manufacture prototype C F test and redesign E G final pricing B,D,F H market test G
- 21. 21 product development 1 2 3 4 6 7 5 A B C D E F G H
- 22. 22 Notation i-j = an activity of a project di-j = the duration of activity i-j Ei = the earliest time event i can occur ESi-j = the earliest start time of activity i-j EFi-j = the earliest finish time of activity i-j LSi-j = the latest start time of activity i-j LFi-j = the latest finish time of activity i-j Li = the latest time event i can occur
- 23. 23 Our Very Own Example product development activity precedence duration (days) A (1-2) - 17 B (1-5) - 7 C (1-3) - 33 D (2-5) A 6 E (3-4) C 40 F (4-5) E 7 G (5-6) B,D,F 12 H (6-7) G 48
- 24. 24 product development forward pass 1 2 3 4 6 7 5 A(17) B(7) C(33) D(6) E(40) F(7) G(12) H(48) E1 = 0 ES1-2 = 0 ES1-5 = 0 ES1-3 = 0 EF1-2 = 17 EF1-5 = 7 EF1-3 = 33 E2 = 17 E5 = 7 E3 = 33 ES5-6 = 80 EF5-6 = 92 E6 = 92 ES2-5 = 17 ES3-4 = 33 EF2-5 = 23 EF3-4 = 73 E4 = 73 ES4-5 = 73 EF4-5 = 80 E5 = 80 ES6-7 = 92 EF6-7 = 140 E7 = 140
- 25. 25 product development backward pass 1 2 3 4 6 7 5 A(17) B(7) C(33) D(6) E(40) F(7) G(12) H(48) L1 = 0 LF1-2 = 74 LF1-5 = 80 LF1-3 = 33 L2 = 74 L3 = 33 L6 = 92 LF5-6 = 92 LS5-6 = 80 LF2-5 = 80 LS2-5 = 74 LF3-4 = 73 LS3-4 = 33 L4 = 73 LF4-5 = 80 LS4-5 = 73 L5 = 80 L7 = 140 LF6-7 = 140 LS6-7 = 92 LS1-2 = 57 LS1-5 = 73 LS1-3 = 0
- 26. 26 Activity Slack Si-j = LSi-j ESi-j Si-j = LFi-j EFi-j or Activity LS ES Slack 1-2 57 0 57 1-5 73 0 73 1-3 0 0 0 2-5 74 17 57 3-4 33 33 0 4-5 73 73 0 5-6 80 80 0 6-7 92 92 0 critical activities
- 27. 27 Critical Path Method An analytical tool that provides a schedule that completes the project in minimum time subject to the precedence constraints. In addition, CPM provides: Starting and ending times for each activity Identification of the critical activities (i.e., the ones whose delay necessarily delay the project). Identification of the non-critical activities, and the amount of slack time available when scheduling these activities.
- 28. 28 critical path 1 2 3 4 6 7 5 A(17) B(7) C(33) D(6) E(40) F(7) G(12) H(48) ES1-3 = 0 LS1-3 = 0 ES5-6 = 80 LS5-6 = 80 ES3-4 = 33 LS3-4 = 33 ES4-5 = 73 LS4-5 = 73 ES6-7 = 92 LS6-7 = 92 ES1-5 = 0 LS1-5 = 73 ES2-5 = 17 LS2-5 = 74 ES1-2 = 0 LS1-2 = 57
- 29. 29 Critical Path Activities focus management attention increase resources eliminate delays eliminate critical activities overlap critical activities break activity into smaller tasks outsource or subcontract
- 30. 30 Critical Path by LP 1 Min . : , pairs n n i j i ij E subj to E E d i j earliest start times 1 1 Min . : , pairs n n i i j i ij nL L subj to L L d i j latest start times
- 32. 32 More Activity Durations let a = optimistic time b = pessimistic time m = most likely time 2 2 2 12 a b b a 2 2 2 2 3 18 a m b a b m ab am bm 2 2 4 6 18 a m b b a uniform: triangular: beta:
- 33. 33 activity durations product development activity a m b A (1-2) 6 18 24 17 9 3 B (1-5) 6 6 12 7 1 1 C (1-3) 24 30 54 33 25 5 D (2-5) 6 6 6 6 0 0 E (3-4) 24 36 72 40 64 8 F (4-5) 6 6 12 7 1 1 G (5-6) 6 12 18 12 4 2 H (6-7) 36 48 60 48 16 4 2 beta note: based upon a 6 day workweek
- 34. 34 critical path analysis product development activity a m b C (1-3) 24 30 54 33 25 5 E (3-4) 24 36 72 40 64 8 F (4-5) 6 6 12 7 1 1 G (5-6) 6 12 18 12 4 2 H (6-7) 36 48 60 48 16 4 sum 140 110 2 beta From the Central Limit Theorem, project completion time is normally distributed with a mean of 140 days and a standard deviation of = 10.5 days. 110
- 35. 35 Probability Statements Probability project will be completed by day 150 is given by: 150 140 Pr 150 Pr Pr .95 .829 10.5 T T z Probability project will be completed after day 130 is given by: 130 140 Pr 130 Pr Pr .95 .171 10.5 T T z
- 36. 36 Resource Constraints Activity ES Duration staffing 1-2 0 17 5 1-5 0 7 7 1-3 0 33 10 2-5 17 6 4 3-4 33 40 6 4-5 73 7 3 5-6 80 12 5 6-7 92 48 6
- 37. 37 Resource Profile early start schedule 0 10 20 30 40 50 60 70 80 30 25 20 15 10 5 1-2 1-5 1-3 3-4 2-5 4-5 5-6 We need too many people at the start of the project!
- 38. 38 Late Start Staffing Activity ES Duration staffing 1-2 57 17 5 1-5 73 7 7 1-3 0 33 10 2-5 74 6 4 3-4 33 40 6 4-5 73 7 3 5-6 80 12 5 6-7 92 48 6
- 39. 39 Resource Profile late start schedule 0 10 20 30 40 50 60 70 80 30 25 20 15 10 5 1-2 1-5 1-3 3-4 2-5 4-5 5-6 the late start schedule. Then we can layoff some folks.
- 40. 40 Time Costing Methods Suppose that projects can be expedited by reducing the time required for critical activities. Doing so results in an increase in some costs and a decrease in others. The goal is to determine the optimal number of days to schedule the project to minimize total cost. Assume that there is a linear time/cost relationship for each activity.
- 41. 41 Time-Cost Trade-offs time crash time normal time crash cost normal cost , n n i j i j d c , c c i j i j d c
- 42. 42 Heuristic Crashing c n i j i j i j n c i j i j c c k d d = $ / day time cost activity normal crash normal crash k C (1-3) 33 25 10 20 1.25 E (3-4) 40 31 22 35 1.44 F (4-5) 7 5 8 12 2.0 G (5-6) 12 9 17 30 4.33 H (6-7) 48 40 30 48 2.25
- 43. 43 An LP approach let yi-j = number of time units activity i-j is crashed K = indirect cost per day , min . : 0 0 1,2,..., i j i j n all i j n j i i j i j n c i j i j i j i k y K E subt to E E y d i j y d d i j E i n
- 45. 45 Forward Pass set Ei = 0 i=1; j=2 set ESi-j = Ei EFi-j = Ei + di-j Ej = max {Ej , EFi-j} If i-j is an activity set j = j + 1 j <= n i = i + 1 j = 2 j > n i < n stop i = n If i-j not an activity
- 46. 46 Backward Pass set Li = En i=1; j=n set LFi-j = Li LSi-j = Li - di-j Lj = min {Lj , LFi-j} If i-j is an activity set i = i + 1 i < n j = j - 1 i = 1 i = n j > 0 stop j = 0 If i-j not an activity