21-12-2012, 11:44 AM
Network Model Of A Project
Network Model.pptx (Size: 114.8 KB / Downloads: 21)
INTRODUCTION
It consists of a number of activities.
For example activities in building construction.
Activities are performed in sequence.
Example:- We must complete laying the foundation before erecting walls.
Each activity will require certain time ,called its duration.
Activities ,relationships and durations are represented by arrow diagram called activity graph.
Activities are shown as directed lines or edges.
Nodes represent the beginning and completion of activities called events.
An activity represented by edge(i ,j) cannot be started before all activities leading to node I have been completed.
Dummy Activity:-
An edge which represents only a precedence relationship and not any job in a project.
They are represented by broken edges.
They become necessary when existing activities are not enough to represent all relationships accurately.
Analysis of an activity network
Activity networks are analyzed by managers for studying and optimizing the execution of project.
Sequence of adjacent edges from source to sink node is called a path.
In figure 2 we have:
Critical path computation
Once a network representation has been completed, the activites labelled properly and described in appropriate form, we are ready to determine total time it would take to complete the entire project to identify the critical activites.
Backward pass
So far we have calculated the Earliest Start Time (EST) and the Earliest Finish Time (EFT) for each task. The next step in calculating the critical path is to re-time the network starting at the end and calculate the Latest Start Time (LST) and Latest Finish Time (LFT) for each task.