Transcript Short-Term Scheduling

Operations
Management
Chapter 15 –
Short-Term Scheduling
PowerPoint presentation to accompany
Heizer/Render
Operations Management, 8e
© 2006
Prentice
Hall, Inc. Hall, Inc.
©
2006
Prentice
15 – 1
Strategic Importance of
Short-Term Scheduling
 Effective and efficient scheduling
can be a competitive advantage
 Faster movement of goods through a
facility means better use of assets
and lower costs
 Additional capacity resulting from
faster throughput improves customer
service through faster delivery
 Good schedules result in more
reliable deliveries
© 2006 Prentice Hall, Inc.
15 – 2
Scheduling Decisions
Organization
Arnold Palmer
Hospital
University of
Missouri
Lockheed-Martin
factory
Hard Rock Cafe
Delta Airlines
Table 15.1
© 2006 Prentice Hall, Inc.
Managers Must Schedule the Following
Operating room use
Patient admissions
Nursing, security, maintenance staffs
Outpatient treatments
Classrooms and audiovisual equipment
Student and instructor schedules
Graduate and undergraduate courses
Production of goods
Purchases of materials
Workers
Chef, waiters, bartenders
Delivery of fresh foods
Entertainers
Opening of dining areas
Maintenance of aircraft
Departure timetables
Flight crews, catering, gate, ticketing personnel
15 – 3
Activity in Sequencing
 Sequence the following cars into as many work days as
needed. Garage can work on two cars simultaneously
 Assume first come first serve sequencing; 8 hour
workday. Customers arrive in the following order
DAY 1
 Car 3: Maintenance ; time needed 6 hours
 Car 4: Maintenance ; time needed 10 hours
 Car 1: Repair ; time needed 2 hours
 Car 2: Repair ; time needed 2.5 hours
DAY 2
 Car 5: Maintenance ; time needed 3.5 hours
 Car 6: Repair ; time needed 3.5 hrs
 Car 7: Maintenance ; time needed 4 hours
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15 – 4
Solution: Sequencing
Repair Track 1
Car 3: Repair - 6 hours
Day 1
Car 1: Maintenance 2 hours
Repair Track 1
Car 2: Maintenance 2.5 hours
Day 2
Car 6:Maintenance 3.5 hours
Repair Track 2
Car 4: Repair – 8 hours
Repair Track 2
Car 4: Repair – 2 hours
Car 5: Repair – 3.5 hours
Car 7:Maintenance 2.5 hours
Repair Track 1
Day 3
© 2006 Prentice Hall, Inc.
Repair Track 2
Car 7:Maintenance 1.5 hours
15 – 5
Activity in Sequencing_2
 Schedule the following cars into 2 work days.
Garage can work on two cars simultaneously
 Method: Garage controlled scheduling
(First assigned first serve; or capacity-based
scheduling). 8 hours per day work time.
 Car 3: Maintenance ; time needed 6 hours
 Car 4: Maintenance ; time needed 10 hours
 Car 1: Repair ; time needed 2 hours
 Car 2: Repair ; time needed 2.5 hours
 Car 5: Maintenance ; time needed 3.5 hours
 Car 6: Repair ; time needed 3.5 hrs
 Car 7: Maintenance ; time needed 4 hours
© 2006 Prentice Hall, Inc.
15 – 6
Solution: Sequencing _2
 Schedule for days 1 and 2. Notice one track for long
duration work and the other for fast jobs!
Fast turnaround jobs
Repair Track 1
Day 1
Car 1: Repair - 2 hours
Long turnaround jobs
Repair Track 2
Car 4: Repair – 8 hours
Car 5: Maintenance 3.5 hours
Car 2: Maintenance 2.5 hours
Repair Track 1
Day 2
Car 6: Maintenance 3.5 hours
Repair Track 2
Car 4: Repair – 2 hours
Car 3: Repair – 6 hours
Car 7:Maintenance 4.0 hours
© 2006 Prentice Hall, Inc.
15 – 7
Definitions
 Scheduling is the assignment of due dates
to specific work or jobs.
 Loading is the assignment of jobs to work
centers.
 Sequencing: Determining the order in
which jobs should be done at each work
center so that due dates are met.
 Input-Output control: Any technique that
enables managers to manage workflows at
each work center by comparing work
added to work completed.
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15 – 8
Positioning
Scheduling
Figure 15.1
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15 – 9
Defining Scheduling
 Scheduling deals with the assignment of
activities (demand) to resources (supply)
(or vice-versa) and timing of activities. E.g.
supply could be production capacity of a firm)
 Types of scheduling situations
 Type I: Supply options (M) are fewer
than demand options (N)
 Type II: Supply options (M) are equal to
demand options (N)
 Type III: Supply options (M) exceed the
number of demand options (N)
© 2006 Prentice Hall, Inc.
15 – 10
Objectives of Scheduling
 Goals of scheduling
 Type I: Supply options (M) are fewer than
demand options (N)
 Assign scarce supply to demand to minimize cost or
maximize benefits
Type II: Supply options (M) are equal to
demand options (N)
 Assign supply to demand to minimize cost or
maximize benefits for total process
Type III: Supply options (M) exceed the
number of demand options (N)
 Scheduling is done for limited capacity and excess
capacity is outsourced.
© 2006 Prentice Hall, Inc.
15 – 11
Methods of Scheduling
 Forward scheduling concept
Scheduling begins as soon as customer
requests and requirements are known
Scheduling begins from the estimated start date
of the project and works forward to determine the
start and finish dates for each of the activities that
make up the order.
 Backward scheduling concept
Scheduling begins from the expected delivery date
and works backwards to determine the finish and start
dates for the activities that make up the order.
[Usually this method is available for projects that have long
completion times, large number of units or parts, and have
the completion of project on or before the delivery deadline
as a key objective] .
© 2006 Prentice Hall, Inc.
15 – 12
Loading_Activity_A

We own a hotel which has a large ballroom. We have to
schedule activities for two Saturdays in May. The closing time
of the ballroom each Saturday is 10 pm. Which activities
would you schedule? We charge per hour for the time a client
spend using room. No charges for cleaning and preparation
times.
 Event A: 9 am - 1 pm, Cleanup needed after event 2
hrs.
 Event B: 4 pm – 7 pm, preparation needed before
event 0.5 hours. Cleanup needed after event 1 hrs.
Event C: 5 pm - 10 pm, preparation needed before
event 1 hours. Cleanup after event 2 hrs.
Event D: 9 am -12 pm, preparation needed before
event 1 hours. Cleanup after event 1 hrs.
Event E: 11 am – 8 pm, preparation needed before
event 2 hours. Cleanup after event 2 hrs.
© 2006 Prentice Hall, Inc.
15 – 13
Activity_A Scheduling Criteria and Options

Option1
 Event A: 9 am - 1 pm AND Event B: 4 – 7 pm
 Event D: 9 am -12 pm AND Event C: 5 - 10 pm.

Option 2
 Event A: 9 am - 1 pm AND Event C 5 - 10 pm.
 Event D: 9 am -12 pm AND Event B: 4 – 7 pm

Option 3
 Event A: 9 am - 1 pm AND Event B OR Event C
Event E: 11 am – 8 pm
Scheduling Criteria: Why did we schedule the way we did? We
are tried to maximize the utilization of the ballroom
(maximize utilization)!
Other criteria; Min. Cost, Min. waiting time or Work in
progress
(WIP)
© 2006 Prentice
Hall, Inc.
15 – 14
Comparing Options_Activity_A

Option1
 Event A: 9 am - 1 pm AND Event B: 4 – 7 pm
 Event D: 9 am -12 pm AND Event C: 5 - 10 pm.

Option 2
 Event A: 9 am - 1 pm AND Event C 5 - 10 pm.
 Event D: 9 am -12 pm AND Event B: 4 – 7 pm

Option 3
 Event A: 9 am - 1 pm AND Event B OR Event C
Event E: 11 am – 8 pm
OPTION 3: Less switching costs, maximize utilization,
minimize waiting times, maximize profits
© 2006 Prentice Hall, Inc.
15 – 15
Activity_Scheduling
If you could change one thing in the operations scheduling of this
case, what would you change?
We own a hotel which has a large ballroom. We have to schedule
activities for two Saturdays in May. The closing time of the
ballroom each Saturday is 10 pm. Which activities would you
schedule? We charge per hour for time spent in room. No
charges for cleaning and preparation times.
 Event A: 9 am - 1 pm, Cleanup needed after event 2 hrs.
 Event B: 4 pm – 7 pm, preparation needed before event 0.5
hours. Cleanup needed after event 1 hrs.
 Event C: 5 pm - 10 pm, preparation needed before event 1
hours. Cleanup after event 2 hrs.
 Event D: 9 am -12 pm, preparation needed before event 1
hours. Cleanup after event 1 hrs.
 Event E: 11 am – 8 pm, preparation needed before event 2
hours. Cleanup after event 2 hrs.
© 2006 Prentice Hall, Inc.
15 – 16
Activity_Scheduling
If you could change one thing in the operations scheduling of this
case, what would you change?
Demand Options:
 Charge for cleaning time
Set minimum reservation time
Capacity Options:
Build new ballroom
Extend working hours per day
© 2006 Prentice Hall, Inc.
15 – 17
Scheduling Criteria
 Types of scheduling/sequencing criteria
 Goal-based approaches
 Minimize cost, waiting times
 Minimize work-in-process
 Maximize profits
 Priorities-based approaches
 First-come first serve or Last-in-first-out
 Longest processing time
 Earliest due date
 Shortest processing time
© 2006 Prentice Hall, Inc.
15 – 18
Job Loading Methods
 Types of scheduling methods
 Arbitrary approaches
 Useful when there are no constraints of
resources (Supply exceeds demand)
 Rule-based approaches
 Useful when there are constraints of resources
 Priorities-based approaches
 Useful when there are constraints of resources
and there are priorities among suppliers or
customers
© 2006 Prentice Hall, Inc.
15 – 19
Assignment Method
(Type II Scheduling)
 A special class of linear programming models
that assign tasks or jobs to resources
 Objective is to minimize cost or time
 Only one job (or worker) is assigned to one
machine (or project)
© 2006 Prentice Hall, Inc.
15 – 20
Assignment Method
1.
Create zero opportunity costs by repeatedly subtracting
the lowest costs from each row and column
2.
Draw the minimum number of vertical and horizontal
lines necessary to cover all the zeros in the table. If the
number of lines equals either the number of rows or the
number of columns, proceed to step 4. Otherwise
proceed to step 3.
3.
Subtract the smallest number not covered by a line from
all other uncovered numbers. Add the same number to
any number at the intersection of two lines. Return to
step 2.
4.
Optimal assignments are at zero locations in the table.
Select one, draw lines through the row and column
involved, and continue to the next assignment.
© 2006 Prentice Hall, Inc.
15 – 21
Assignment Example
Typesetter
Job
R-34
S-66
T-50
Step 1a - Rows
C
$11
$ 8
$ 9
$14
$10
$12
$ 6
$11
$ 7
Least numbers
per row
Typesetter
A
© 2006 Prentice Hall, Inc.
B
Step 1b - Columns
Typesetter
Job
R-34
S-66
T-50
A
$ 5
$ 0
$ 2
B
$ 8
$ 2
$ 5
C
$ 0
$ 3
$ 0
Job
R-34
S-66
T-50
Least numbers
per column
A
B
C
$ 5
$ 0
$ 2
$ 6
$ 0
$ 3
$ 0
$ 3
$ 0
15 – 22
Assignment Example
Step 2 - Lines
Typesetter
Job
R-34
S-66
T-50
A
B
C
$ 5
$ 0
$ 2
$ 6
$ 0
$ 3
$ 0
$ 3
$ 0
The smallest uncovered
number is 2 so this is
subtracted from all other
uncovered numbers and
added to numbers at the
intersection of lines
Step 3 - Subtraction
Typesetter
Because only two lines
are needed to cover all
the zeros, the solution
is not optimal (it is
fewer than the number
of jobs to assign)
© 2006 Prentice Hall, Inc.
Job
R-34
S-66
T-50
A
B
C
$ 3
$ 0
$ 0
$ 4
$ 0
$ 1
$ 0
$ 5
$ 0
15 – 23
Assignment Example
Step 2 - Lines
Typesetter
Job
R-34
S-66
T-50
A
B
C
$ 3
$ 0
$ 0
$ 4
$ 0
$ 1
$ 0
$ 5
$ 0
Because three lines are
needed to cover all the
numbers, the solution
is optimal and job
assignments can now
be made
© 2006 Prentice Hall, Inc.
Start by assigning S-66 for
worker B.
Job T-50 must go to worker A.
This leaves R-34 to worker C as
this is the least cost assignment
for worker C.
Step 4 - Assignments
Typesetter
Job
R-34
S-66
T-50
A
B
C
$ 3
$ 0
$ 0
$ 4
$ 0
$ 1
$ 0
$ 5
$ 0
15 – 24
Assignment Example
From the original cost table
Minimum cost = $6 + $10 + $9 = $25
Step 4 - Assignments
Costs Table
Typesetter
Typesetter
A
Job
R-34
S-66
T-50
© 2006 Prentice Hall, Inc.
$11
$ 8
$ 9
B
$14
$10
$12
C
$ 6
$11
$ 7
Job
R-34
S-66
T-50
A
B
C
$ 3
$ 0
$ 0
$ 4
$ 0
$ 1
$ 0
$ 5
$ 0
15 – 25
Opportunity Loss: Example 2 (Deriving
Opportunity Loss Table)
Assignment Costs Table
Typesetter
Job
R-34
S-66
T-50
A
B
C
$11
$ 8
$ 9
$14
$10
$12
$ 6
$11
$ 7
Opportunity Loss Table
(Sales – Costs) Table
Typesetter
Typesetter
A
B
C
Job
R-34
S-66
T-50
© 2006 Prentice Hall, Inc.
Assume that the fixed sale price
for each job is as follows :
R-34 = $ 15 /unit;
S-66 = $ 15 /unit;
T-50 = $ 14 /unit;
$15-$11 $15-$14 $15-$6
$15-$8 $15-$10 $15-$11
$14-$9 $14-$12 $14-$7
Job
R-34
S-66
T-50
A
B
C
$ 4
$ 7
$ 5
$ 1
$ 5
$ 2
$ 9
$ 4
$ 7
15 – 26
Assignment: Example 2 (Deriving
Opportunity Loss Table)
The table has profit margins that are earned for each unit made. To
find the optimal assignment, use the method but subtract the highest
score of each row not the least one.
Typesetter
A
Job
R-34
S-66
T-50
B
1
Typesetter
C
Opportunity Loss Table
$ 4
$ 7
$ 5
$ 1
$ 5
$ 2
$ 9
$ 4
$ 7
Take highest number from each column
and subtract from all the numbers
in the column.
Note -2 is the highest number in column B!
© 2006 Prentice Hall, Inc.
Job
R-34
S-66
T-50
A
B
-$ 5
$0
-$ 2
-$ 8
-$ 2
-$ 5
Typesetter
Job
R-34
S-66
T-50
A
B
-$ 5
$0
-$ 2
-$ 6
$0
-$ 3
2
C
$0
-$ 3
$0
3
C
$0
-$ 3
$0
15 – 27
Assignment: Example 2 (Deriving
Opportunity Loss Table)
Draw lines across the zeros. As only two lines cross all the zeros,
solution is not yet optimal.
Opportunity Loss Table
Typesetter
Job
R-34
S-66
T-50
4
A
B
-$ 5
$0
-$ 2
-$ 6
$0
-$ 3
C
$0
-$ 3
$0
Take highest number from uncrossed
cells and subtract it from all other
uncrossed numbers in each column.
Add the number to number on the intersection
Intersection to get table 5.
This is not an optimal solution – 2 lines
through all zeros
© 2006 Prentice Hall, Inc.
15 – 28
Opportunity Loss: Example 2
Largest
uncrossed
number
Table 5 now has three lines
going through all the zeros. An
optimal assignment can now be
Made for our problem!
Typesetter
Assign C to R-34; assign A to T-50;
assign B to S-66;
The profit margin of the assignment
is taken from first table:
=
$5 + $ 5 + $ 9 = $ 19
Gross Margin - Opportunity Loss Table
Typesetter
A
Job
R-34
S-66
T-50
© 2006 Prentice Hall, Inc.
$ 4
$ 7
$ 5
B
$ 1
$ 5
$ 2
1
Job
R-34
S-66
T-50
A
B
-$ 5
$0
-$ 2
-$ 6
$0
-$ 3
Typesetter
C
$ 9
$ 4
$ 7
Job
R-34
S-66
T-50
4
A
B
-$ 3
$0
$0
-$ 4
$0
-$ 1
5
C
$0
-$ 3
$0
C
$0
-$ 5
$0
15 – 29
Gantt Load Chart Method
(Type III Scheduling)
Day
Work
Center
Metalworks
Monday
Tuesday
Job 349
Job 349
Job 408
Painting
Processing
Thursday
Friday
Job 350
Mechanical
Electronics
Wednesday
Job 408
Job 349
Job 295
Job 408
Unscheduled
Job 349
Center not available
Figure 15.3
© 2006 Prentice Hall, Inc.
15 – 30
Plan 1: Gantt Staffing Chart (Type III
Scheduling)
Bill
Mon
Tue
Off
Off
Mary
Wed
Thu
Off
Off
Sue
Schedule
Off
Will
Off
Off
Bob
Off
Off
Mon
Off
Fri
Sat
Sun
Off
Off
Josh
Off
Off
1. Required Capacity
5
5
6
5
8
9
9
2. Max available staff
7
7
7
7
7
7
7
3. Max off duty limits
2
2
1
2
-1
-2
-2
4. Scheduled off-duty
3
3
2
3
2
1
0
5. Extra staff needed
1
1
1
1
3
3
2
Scheduled off duty minus Max. off duty limit ( row 4. Minus row 3.)
What would you advise the manager to do?
© 2006 Prentice Hall, Inc.
15 – 31
Plan 2: Gantt Staffing Chart (Type III
Scheduling)
Sat
Sun
Bill
Off
Off
Mary
Off
Off
Sue
Off
Off
Mon
Schedule
Tue
Wed
Thu
Fri
Will
Off
Off
Bob
Off
Off
Mon
Josh
Off
Off
Off
Off
1. Required Capacity
5
5
6
5
8
9
9
2. Max available staff
7
7
7
7
7
7
7
3. Max off duty staff
2
2
1
2
-1
-2
-2
4. Scheduled off-duty
1
2
1
2
2
3
3
5. Extra staff needed
-1
0
0
0
3
5
5
4. Minus 3
This solution shifts all temp staff requirement to
weekends
What could be the benefit/problem with this plan?
© 2006 Prentice Hall, Inc.
15 – 32
Gantt Schedule Chart
Example
Job
Day
1
Day Day
2
3
Day Day Day Day Day
4
5
6
7
8
A
B
Start of an
activity
End of an
activity
Scheduled
activity time
allowed
Actual work
progress
Maintenance
Nonproduction
time
C
Figure 15.4
© 2006 Prentice Hall, Inc.
Point in time
when chart is
reviewed
Now
15 – 33
Sequencing
 Specifies the order in which jobs should be
performed at work centers
 Priority rules are used to dispatch or
sequence jobs
 FCFS: First come, first served
 SPT: Shortest processing time
 EDD: Earliest due date
 LPT: Longest processing time
© 2006 Prentice Hall, Inc.
15 – 34
Sequencing Example
Apply the four popular sequencing rules
to these five jobs
Job
A
B
C
D
E
© 2006 Prentice Hall, Inc.
Job Work
(Processing) Time
(Days)
6
2
8
3
9
Job Due
Date
(Days)
8
6
18
15
23
15 – 35
Sequencing: FCFS Example
FCFS: Sequence A-B-C-D-E (assume that all jobs
arrived on same day in the sequence given).
Job
Sequence
Job
Work
(Proce
ssing)
Time
Wait
Times
Flow
Time
Job Due
Date
A
6
0
6
8
0
B
2
6
8
6
2
C
8
8
16
18
0
D
3
16
19
15
4
E
9
19
28
23
5
28
28
49
77
© 2006 Prentice Hall, Inc.
Job
Lateness
11
15 – 36
Sequencing Example
FCFS: Sequence A-B-C-D-E
Average completion time =
Total flow time
= 77/5 = 15.4 days
Number of jobs
Total job work time
Utilization =
Total flow time = 28/77 = 36.4%
Total flow time
Average number of
jobs in the system = Total job work time = 77/28 = 2.75 jobs/month
Total late days
Average job lateness = Number of jobs = 11/5 = 2.2 days
© 2006 Prentice Hall, Inc.
15 – 37
Sequencing Example
SPT (Shortest processing time): Sequence B-D-A-C-E
Job
Sequence
Job Work
(Processing)
Time
Flow
Time
Job Due
Date
B
2
2
6
0
D
3
5
15
0
A
6
11
8
3
C
8
19
18
1
E
9
28
23
5
28
65
Job
Lateness
9
The sequence changes with the priority rule
© 2006 Prentice Hall, Inc.
15 – 38
Sequencing Example
SPT: Sequence B-D-A-C-E
Total flow time
Average completion time =
= 65/5 = 13 days
Number of jobs
Total job work time
Utilization =
Total flow time = 28/65 = 43.1%
Total flow time
Average number of
=
= 65/28 = 2.32
jobs in the system
Total job work time
jobs/months
Total late days
Average job lateness = Number of jobs = 9/5 = 1.8 days
© 2006 Prentice Hall, Inc.
15 – 39
Sequencing Example
EDD (Earliest due date) : Sequence B-A-D-C-E
Job
Sequence
Job Work
(Processing)
Time
Flow
Time
Job Due
Date
B
2
2
6
0
A
6
8
8
0
D
3
11
15
0
C
8
19
18
1
E
9
28
23
5
28
68
© 2006 Prentice Hall, Inc.
Job
Lateness
6
15 – 40
Sequencing Example
EDD: Sequence B-A-D-C-E
Total flow time
Average completion time =
Number of jobs
= 68/5 = 13.6 days
Total job work time
Utilization = Total flow time
= 28/68 = 41.2%
Total flow time
Average number of
=
= 68/28 = 2.43 jobs/
jobs in the system
Total job work time
month
Total late days
Average job lateness = Number of jobs = 6/5 = 1.2 days
© 2006 Prentice Hall, Inc.
15 – 41
Sequencing Example
LPT (Longest processing time): Sequence E-C-A-D-B
Job
Sequence
Job Work
(Processing)
Time
Flow
Time
Job Due
Date
E
9
9
23
0
C
8
17
18
0
A
6
23
8
15
D
3
26
15
11
B
2
28
6
22
28
103
© 2006 Prentice Hall, Inc.
Job
Lateness
48
15 – 42
Sequencing Example
LPT: Sequence E-C-A-D-B
Total flow time
Average completion time =
= 103/5 = 20.6 days
Number of jobs
Total job work time
Utilization =
Total flow time = 28/103 = 27.2%
Total flow time
Average number of
=
= 103/28 = 3.68 jobs
jobs in the system
Total job work time
Total late days
Average job lateness = Number of jobs = 48/5 = 9.6 days
© 2006 Prentice Hall, Inc.
15 – 43
Summary Sequencing Examples
Summary of Rules
Average Number
of Jobs in
Average
Utilization
System per
Lateness
(%)
month
(Days)
Rule
Average
Completion
Time (Days)
FCFS
15.4
36.4
2.75
2.2
SPT
13.0
43.1
2.32
1.8
EDD
13.6
41.2
2.43
1.2
LPT
20.6
27.2
3.68
9.6
© 2006 Prentice Hall, Inc.
15 – 44
Comparison of
Sequencing Rules
 No one sequencing rule excels on all
criteria
 SPT does well on minimizing flow time and
number of jobs in the system
 But SPT moves long jobs to the end which
may result in dissatisfied customers
 FCFS does not do especially well on any
criteria (or does poorly on most criteria)
but it is perceived as fair by customers
 EDD minimizes lateness
© 2006 Prentice Hall, Inc.
15 – 45
Improving Performance of System
 Changing setting of due dates
 Changing process serial to parallel form
A
B
C
A
B
E
C
© 2006 Prentice Hall, Inc.
E
D
D
15 – 46
Example from Service Industry
Patie
nt
Health Issue (Treatment time)
A
F
G
B
C
I
D
H
E
Pain in head (1 hr)
Skin disease (1 hr)
Sun burns (1 hr)
Brain tumor (2 hrs)
Depression (1 hr)
Pollen issues (2 hrs)
Migraine pains (2 hrs)
Skin cancer (2 hrs)
Skin exam (1 hr)
First priority
Second priority
appointment
appointment
8-9 am
9-10 am
10-11 am
8-10 am
2-3 pm
2-4 pm
2-4 pm
8-10 am
11-12 am
10-11 am
10-11 am
11-12 pm
10-12pm
1-2 pm
10-12 pm
8-10 am
2-4 pm
2-3 pm
There are two doctors in a specialist clinic, one is a dermatologist the
other is a neurologist. The patients call-in the order shown. Create a
schedule for the clinic assuming that each specialist works 8-12 pm
and 1-4pm daily. Assign slots to patients using First come First serve
priority rule. Assume that the appointments slots are one hour each. 15 – 47
© 2006 Prentice Hall, Inc.
Resolution from Service Industry
Day 1
8-9
Nurlo
gist
9-10
A
Aller
gist
F
Day 2
10-11
11-12
B
B
G
1-2
2-3
3-4
C
H
8-9
9-10
10-11
D D
H
1112
E
I
I
There are two doctors in a specialist clinic, one is a dermatologist the
other is a neurologist. The patients call-in the order shown. Create a
schedule for the clinic assuming that each specialist works 8-12 pm
and 1-4pm daily. Assign slots to patients using First come First serve
priority rule. Assume that the appointments slots are one hour each.
© 2006 Prentice Hall, Inc.
15 – 48
Resolution from Service Industry
Day 1
8-9
9-10
Day 2
10-11
11-12
Nurlo
gist
B
A
E
Aller
gist
H
F
G
1-2
C
2-3
3-4
8-9
9-10
10-11
1112
D
I
There are two doctors in a specialist clinic, one is a dermatologist the
other is a neurologist. The patients call-in the order shown. Create a
schedule for the clinic assuming that each specialist works 8-12 pm
and 1-4pm daily. Assign slots to patients using First come First serve
priority rule combined with SPT and LPT time slots
© 2006 Prentice Hall, Inc.
15 – 49