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...