Today

More on Queuing System

Lessons from queuing theory

Short discussion on SanteMarie Hospital case (due Thursday)

Instructions are posted on Blackboard

Due at noon on Thursday 9/15

Instructions are on Blackboard

Questions will be added on ForClass

o You’ll be notified via email

You can do it in groups of at most 5.

Waiting Line Theory

BUAD311

Session 7

2

Next Class

Which one of these will have a shorter average wait time?

(Answer on ForClass)

Single queue

system

Multiple queue

system

Objectives

Classification of waiting line systems

Formulae for waiting line calculation

“Some” time later…

Hello!!!……

ARE YOU THERE?

Two causes of waiting lines

Capacity is lower than demand rate (even in the absence of

variability)

Capacity is higher than demand rate but there is variability

In the arrival process: the time between the arrival of two flow

units is not constant

In the service process: the time to process flow units differ from

one to the other

From now on we assume that

Process capacity > Demand rate

Terminology/characteristics of queues

Arrival

Pattern

Service

Pattern

• Distribution

of Arrival

Process

• Distribution

of Service

Times

Number of

servers

Buffer Size

• Can the

queue be

arbitrarily

long?

• E.g.,

Waiting

room size

Service

Discipline

• First-in

First-out

• Priority

• Shortest

processing

time

• Other

Queue Discipline

Who would receive service first?

7

Terminology and Classification of Waiting Lines

Define a queuing system by:

Arrival Pattern / Service Pattern / # of Servers / Queue Capacity / Discipline

Examples:

M/M/2 - Exponential interarrival times, exponential service times,

2 severs, infinite capacity, first-come-first-serve

M/G/8 – Exponential interarrival times, general service times,

8 servers, infinite capacity, first-come-first-serve

•

•

•

Notation:

M: Exponential

G: General...

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