operation research's cpm techniques
TRANSCRIPT
“Pull” system to avoid overproductionMilk example – weekly batch or daily purchase?Next purchase triggered when you start using the only bottle of milk you have.Not an example of zero-inventory, but still a pull system.Because of demand uncertainty and lead-times, in many cases inventory is necessary to allow for smooth production.Hence TPS follows the supermarket model or keeping a small amount in stock. As soon as customers take products away, they are replenished.Each demand instance triggers a part being pulled from upstream.The triggering mechanism is called “Kanban” which means cards, signboard or a poster.
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CONTENTS INTRODUCTION NETWORKS TECHNIQUE’Si) CRITICAL PATH METHOD (CPM)ii) PROGRAM EVALUATION & REVIEW TECHNIQUE EVENTS TIMESi) Earliest Events times ii) Latest Events times FLOAT TERMS USED IN CPM CRITICAL PATH ANAYLYSIS
INTRODUCTION In present days the
competitions, market trends, economics factors, environmental etc many factors increase the complexity for and enterprise that added the pressure of the brain of decision maker.
Project is one which consist of no. of interrelated activities so it is impossible to take decision on the intuition based.
INTRODUCTION (CONTINU…)Management always looks for some
method and techniques which may help is Planning, Scheduling and Controlling the project.
The analysis whose aim is to sequence the project activities so that project completition time and cost are properly balanced so such types of analysis is called the Network Analysis.
NETWORK TECHNIQUES A network (also called the
network diagram or network technique) is a symbolic representation of the essential characteristic of project.
There are two widely applied network techniques
i) CRITICAL PATH METHOD (CPM)ii) PROGRAMME EVALUATION &
REVIEW TECHNIQUE (PERT)
PROGRAMME EVALUATION AND REVIEW TECHNIQUE (PERT)PERT is develop in 1957 by U.S NAVY for
scheduling the research and development work for polarize the missile program.
Its uses event oriented network in which the successive events are joined by arrows.
Its is preferred to those projects in which the time for various activities are not pre defined.
There is no significant to guideline.
CRITICAL PATH METHOD (CPM)
The CPM’s development were initiated by E.I du pont de Neumours company in 1956.
It is the activity oriented network which consist of a number of a well recognized jobs, task or activities.
CPM is generally used for simple, repetitive types of projects for which the activity time and cost are known mean it is of deterministic nature.
It uses in the projects like construction of building, road, bridge, yearly closing of accounts by a company can be handled by CPM.
Thus it is deterministic rather then probabilistic model.
EVENT TIMES Each event node needs two boxes, to
mark in the event times.
LATEST EVENT TIME
EARLIEST EVENT TIME
Earliest Event TimesThe EET for an event occurs when all
activities leading into that event are complete.
To find EETs, work forwards through the network from the start node to the finish node.
EARLIEST EVENT TIMES
Latest Event TimesThe LET for an event is the latest it
can occur without delaying subsequent events.
To find LETs, work backwards through the network from the finish node to the start node.
EARLIEST EVENT TIMES
LATEST EVENT TIMES
FloatThe amount of time an activity can
be delayed or lengthened. Sometimes this is called slack.
Mathematically,Float LFT EFT
TERMS USED IN NETWORK’S (CPM)ACTIVITY It is the physical identifiable part of
project which requires time for its execution
It is represented be and arrow, the tail of which represent the start and the head the finish of the activity
HeadTail
EVENT The beginning and end points of an
activity are called nodes.It is represented by a circle.The head event of an activity is always
greater then the tail event. Event 2 > Event 1
Event 2Event 1
Activity
PATHAn unbroken chain of activities arrows
connecting the initial event to some other event is called a path.
1 2Activity 1
3
Activity 2 Activity 3
LOOPING Some times the due to fall network
sequences a condition as shown arises
2
3
4 51
DUMMY ACTIVITY It is the activity which only
dependency of one activity on the other.
It is the one which does not consume any time mean’s (duration is to 0).
Its is usually represented by dotted line arrow.
EB
A
D (Dummy Activity)
C
NETWORKIt is the graphical representation of
logically and sequentially connected arrows and nodes representative activities and events of the project.
Network are also called arrow diagram. The figure follows illustrate the
network of various activities
B
A
E
C
D F
CRITICAL PATH ANALYSIS EXAMPLE : Mr. JHON called for a
interview today so from start he is performing the following necessary activities in their particular duration.
i) Draw the network diagram.ii) Indicate the critical path.iii) Create an event table to find out
the earliest and latest event time and total float of the project.
Critical Path Analysis
Activity duration
Shower 3Dry hair 8Fetch car 7Iron clothes 12Dress and make-up
10
Drive to interview
20
Precedence table
Activity Immediately preceding activities
duration
A Shower - 3B Dry hair A 8C Fetch car - 7D Iron clothes - 12E Dress and make-
upB,D 10
F Drive to interview
C,E 20
The last activities that must be completed
before an activity can begin
Activity on Arc Network
A(3)D(12)
B(8)
E(10)C(7) F(20)
1 5
4
3
2
The network will build up with each mouse click, in the order you would construct it on paper.
Event Times
A(3)D(12)
B(8)
E(10)C(7) F(20)
1 5
4
3
2
Earliest event timeEET
Latest event timeLET
Each event node needs two boxes, to mark in the event times.
Earliest Event Times
A(3)D(12)
B(8)
E(10)C(7) F(20)
1 5
4
3
2
0
3
12
22
42
To find EETs, work forwards through the network from the start node to the finish node.
The EET for an event occurs when all activities leading into that event are complete.
Latest Event Times
A(3)D(12)
B(8)
E(10)C(7) F(20)
1 5
4
3
23
0
12
22
42
42
22
12
4
0
To find LETs, work backwards through the network from the finish node to the start node.
The LET for an event is the latest it can occur without delaying subsequent events.
Critical Activities
A(3)D(12)
B(8)
E(10)C(7) F(20)
1 5
4
3
23 4
0 0
12
12
22 22
42
42
Critical activities are activities that cannot run late. For critical activities:Latest finish — Earliest start = length of activity
The green arrows mark the critical activities, which form the critical path. The critical path(s) must form a continuous route from the start node to the finish node.
EVENT TABLE
E.S
E.F
L.S
L.F
A 3 0 3 5 9 6 * B 8 3 1
1 4 1
2 1 *
C 7 0 7 15
22
15 *
D 12 12 22
12 22
0 YES
E 10 0 12
0 12
0 YES
F 20 22 42
22 42
0 YES
Activity
Duration
Earliest Time
Latest Time
Total Float
C.P.M
QUESTION ???
REPRESENTED BY,MUHAMMAD YOUNUS A. QURESHI 08IN70