office ppt template 029

7/30/2019 Office Ppt Template 029

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NETWORK DIAGRAMMINGTECHINIQUES AND THEIRIMPORTANCE

PRESENTERS:

Sadia Nosheen 2k9-che-40

Zia ullah 2k9-che-64

Fakhar Abbas 2k9-che-122

Waqas Ali 2k9-che-149


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CONTENTS

Definition

Types of network diagramss

PERT & CPM

Differences between PERT & CPM

Terminologies Creating a PERT/CPM diagram

Importance of network diagramming techinique


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Project Time Management

Project time management involves the processesrequired to ensure timely completion of a project.Processes include:

Activity definition Activity sequencing

Activity duration estimating

Schedule development Schedule control


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Schedule development

Schedule converts action plan intooperating time table

Basis for monitoring and controlling project

Scheduling more important in projects thanin production, because unique nature


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Project Network Diagrams

Project network diagrams are the preferredtechnique for showing activity sequencing

A project network diagram is a schematic displayof the logical relationships among, or sequencing

of, project activities Graphical portrayal of activities and event

Shows dependency relationships betweentasks/activities in a project

Clearly shows tasks that must precede(precedence) or follow (succeeding) other tasks ina logical manner

Clear representation of plan a powerful tool forplanning and controlling project


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Network Diagrams CPM

PERT

Bar Charts Milestone Chart

Gantt Chart


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Network Diagrams Developed in the 1950s

A graphical representation of the tasks necessary

to

complete a project

Clearly visualizes the flow of tasks &relationships


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Terminology Activity - A specific task or set of tasks that are

required by the project, use up resources, andtake time to complete

Event - The result of completing one or more

activities. An identifiable end state occurring at aparticular time. Events use no resources.

Network - The combination of all activities andevents define the project and the activityprecedence relationships


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Path - The series of connected activities (orintermediate events) between any two events in anetwork

Critical - Activities, events, or paths which, ifdelayed, will delay the completion of the project.

A projects critical path is understood to meanthat sequence of critical activities that connect theprojects start event to its finish event

Dummy Activity

Indicates only precedence relationships

Does not require any time of effort


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A dummy activity may be needed:

to prevent 2 or more activities sharingthe same starting and ending events.

to maintain network logic i.e. toensure that the network abides by the

precedence table.

OK, tellme theworst!!

Sometimes we have to use

Dummy activities.

We use a dashed arrow

to record these.


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Arrows An arrow leads from tail to headdirectionally

Nodes A node is represented by a circle

ACTIVITYPRECEEDING SUCCESSOR

EVENT


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Network Diagrams Two classic formats

AOA: Activity on Arrow

AON: Activity on Node

Each activity labeled with

Identifier (usually a letter/code)

Duration (in standard unit like days)


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Formats

Activity-on-arrow (AOA)

Arrows represent activities and nodes are eventsfor points in time, It uses an arrow to depict anactivity.

The length of arrow shows relative time

to complete tasks


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Activity-on-node (AON)

Nodes represent activities, and arrows showprecedence

relationships, It uses a node to depict anactivity.


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Project Network Rules

Networks typically flow from left toright.

An activity can not begin until all of itspreceding activities are complete.

Arrows indicate precedence and cancross over each other.

Are there any rules tofollow when drawingnetwork diagrams?


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Identify each activity with a uniqueidentifier, this identifier must increment(1.2.3, A,B,C etc) as the network proceeds.

Looping is not allowed.

Conditional statements are not allowed.

Use the start and stop nodes


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Time-Related Task

Properties


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Situations in network

diagram

A

B

C

A must finish before either Bor C can start

A

B

C both A and B must finish

before C can start


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D

C

B

A

both A and C must

finish before either ofB or D can start

A

C

B

D

DummyA must finish beforeB can start

both A and C mustfinish before D canstart


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Example

Develop the network for a project with followingactivities and immediate predecessors:

Activity Immediatepredecessors

A -

B -

C B

D A, C

E C

F C

G D,E,F

Try to do for the first five (A,B,C,D,E) activities


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Network of first five activities

1 3 4

2

5

We need tointroduce a

dummy activity


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Network Diagrams

NETWORK TECHNIQUESNETWORK TECHNIQUES

PERT

-Program Evaluation andReview Technique

- developed by the USNavy with BoozHamilton Lockheed

- on the PolarisMissile/Submarineprogram 1958

CPM

Critical Path Method

Developed by ElDupont for ChemicalPlant ShutdownProject- about

same time as PERT

Both use same calculations, almost similarMain difference is probabilistic and deterministic in time

estimationGantt Chart also used in scheduling


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Critical Path Method (CPM)

The Critical Path Method (CPM) is one of severalrelated techniques for doing project planning.CPM is for projects that are made up of a number

of individual "activities." If some of the activitiesrequire other activities to finish before they canstart, then the project becomes a complex web ofactivities.

It is used for one time estimations.


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CPM can help to figure out :

1. how long the complex project will take tocomplete

2. which activities are "critical," meaning that theyhave to be done on time or else the whole project

will take longer

WOW


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If you put in information about the cost ofeach activity, and how much it costs to

speed up each activity, CPM can help tofigure out:

1. whether you should try to speed up the project,

and, if so, 2. what is the least costly way to speed up the

project.


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Example

Right, nowwell solve

an exampleof CPM


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Doingwell!!!


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Keep going!!

Find the total path and the critical path


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Critical path


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A Critical Path is a specific set of sequential tasks upon

which the project completion date depends

Tasks on the critical path cannot be delayed without

delaying the project completion day If a task on the critical path is delayed by 1 day, then

the project completion date is delayed (at least) by 1

day

All projects have at least one Critical PathCritical Paths are the paths with duration = total project

duration

CPM Ad t d


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CPM: Advantages and

Disadvantages

Advantages Show precedence well

Reveal interdependencies not shown in other

techniques Ability to calculate critical path

Ability to perform what if exercises


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Disadvantages

Default model assumes resources are unlimited You need to incorporate this yourself (Resource

Dependencies) when determining the real CriticalPath

Difficult to follow on large projects


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Purpose

To simplify the planning and scheduling of largeand complex projects.

To incorporate uncertainty in the sense that it waspossible to schedule a project not knowingprecisely the details and duration's of all theactivities.

Event-oriented technique rather than start- andcompletion-oriented.

Used more in R&D-type projects where Cost is not

a major factor but Time is.


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Terminologies

PERT event: is a point that marks the start or completionof one (or more) tasks. It consumes no time, and uses noresources. It marks the completion of one (or more) tasks.It is not reached until all of the activities leading to that

event have been completed. Predecessor event: an event (or events) that immediately

precedes some other event without any other eventsintervening. It may be the consequence of more than one

activity. Successor event: an event (or events) that immediately

follows some other event without any other eventsintervening. It may be the consequence of more than one

activity.


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PERT activity: is the actual performance of a task. Itconsumes time, it requires resources (such as labor,materials, space, machinery), and it can be understood as

representing the time, effort, and resources required tomove from one event to another. A PERT activity cannotbe completed until the event preceding it has occurred.

Optimistic time (O): the minimum possible time requiredto accomplish a task, assuming everything proceeds betterthan is normally expected

Pessimistic time (P): the maximum possible time requiredto accomplish a task, assuming everything goes wrong(but excluding major catastrophes).

Most likely time (M): the best estimate of the timerequired to accomplish a task, assuming everythingproceeds as normal.


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Expected time (TE): the best estimate of the time

required to accomplish a task, assumingeverything proceeds as normal (the implicationbeing that the expected time is the average timethe task would require if the task were repeated

on a number of occasions over an extended periodof time).


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Creating a PERT DiagramSTEPS 1:

Determine the tasks that the project requires andthe order in which they must be completed

Determine the optimistic, most likely, andpessimistic time of each task

Compute for the Expected time using the formula

Te=(O+4M+P)/6

Determine whether to use AOA or AON diagrams


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Activity Predecessor Optimistic(a)

Normal(m)

Pessimistic(b)

Te(a+4m+b)/6

A --- 2 4 6 4.00B --- 3 5 9 5.33

C A 4 5 7 5.17

D A 4 6 10 6.33

E B, C 4 5 7 5.17

F D 3 4 8 4.50

G E 3 5 8 5.17f

Rightnowwell solveanexample


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Start

F

C

GE

D

B

A

Finish


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STEPS 2: Determine the ES & EF of each activity by:

Start at the beginning moving towards the end

ES & EF for the start activity is always 0 since they aremilestones

Use the EF of the predecessor activity as the ES of thecurrent activity

EF of an activity is computed by adding its ES with itsduration

For activities with 2 or more predecessor activities, usethe predecessor with the higher EF as the ES of thecurrent activity


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Creating a PERT Diagram

STEPS 3:

Determine the LS & LF of each activity by:

Start at the end and work towards the beginning

Use the LS of the successor activity as the LF of thecurrent activity

LS of an activity is computed by subtracting its LF withits duration

For activities with 2 or more successor activities, usethe successor with the lower LS as the LF of the currentactivity


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Creating a PERT Diagram

STEPS 4:

Compute for the critical path by adding theduration's of various paths for all activities

Determine if any activities have slack by

subtracting the activitys LF & EF


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PERT & CPM Similarities

Both follow the same steps and use network

diagrams Both are used to plan the scheduling of individual

activities that make up a project

They can be used to determine the earliest/lateststart and finish times for each activity


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PERT & CPM Differences

PERT is probabilistic whereas CPM is deterministic

In CPM, estimates of activity duration are basedon historical data

In PERT, estimates are uncertain and we talk of

ranges of duration and the probability that anactivity duration will fall into that range

CPM concentrates on Time/Cost trade off.

ADVANTAGES:


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ADVANTAGES:PERT chart explicitly defines and makes visible

dependencies (precedence relationships) between the

work breakdown structure (commonlyWBS) elementsPERT facilitates identification of the critical path and

makes this visible

PERT facilitates identification of early start, late start,

and slack for each activityPERT provides for potentially reduced project duration

due to better understanding of dependencies leading

to improved overlapping of activities and tasks where

feasible.

The large amount of project data can be organized &

presented in diagram for use in decision making.


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DISADVANTAGES

There can be potentially hundreds or thousands of activities

and individual dependency relationshipsPERT is not easily scalable for smaller projectsThe network charts tend to be large and unwieldy requiringseveral pages to print and requiring special size paper

The lack of a timeframe on most PERT/CPM charts makes itharder to show status although colours can help (e.g.,specific colour for completed nodes)When the PERT/CPM charts become unwieldy, they are nolonger used to manage the project.

Importance of a Network Diagram


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Importance of a Network Diagram

Visual Imagery:

It can be quite difficult for non-technical people tounderstand how a particular piece of softwareworks, and why its proper operation is so criticalto the success of the business. The network

diagram includes pictures that show each step inthe software process, from inputting the data todistributing the resulting reports.


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Faster Education:

Creating a detailed network diagram that shows

how a particular piece of software interfaces withcompany hardware and other pieces of softwareallows both new hires and existing employers togain a better understanding of the work they need

to do and how their particular jobs affect theentire organization. The ability to see each step inthe software development and softwaremanagement process in visual form is often

helpful for workers in the IT field and formembers of the management team.


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Better Record Keeping:

Documentation is a critical, but often overlooked,

part of any IT organization. Without the properdocumentation in place it can be difficult to trackdown problems in complex systems. By taking thetime to create a detailed network diagram for

each piece of software used in the company, theIT staff makes it easier for their colleagues to findand resolve problems, even if they have no directexperience with that type of software.


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Better Project Planning:

A detailed network diagram allows project managers andother members of the project team to plan their projects

more effectively. When everyone on the project team cansee exactly how the software works, and what othersystems it interfaces with, it is much easier for those teammembers to move forward with beneficial changes. A

good network diagram also allows project teams to avoidcostly mistakes that could have an impact the operation ofthose software packages and the networks on which theyrun. In fact, the Project Management Institute cites theimportance of network diagrams in their trainingmaterials and other literature.


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REFERENCES

www.smartdraw.com/specials/network.asp

www.edrawsoft.com/Network-Diagram-Tutorials.php

www.opnet.com/solutions/network_management/netmapper.htm

www.slideshare.com


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Thank You

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