SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
Optimizing print-room operations at Open Access Labs,
Texas A&M University
Course project for graduate course on Business Process Simulation, Analysis and
Design
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
1. Executive Summary:
This project analyzes operations of the four printers in the print room at the first floor of
the Student Computing Center (SCC). There are help desk, information desk and resource desk
in the lab to assist the users with support requests, resource requests and other miscellaneous
requests. Till the end of 2008, there were a total of 3 printers but at the start of 2009 an
additional printer was bought to meet the increasing number of print requests. During peak
hours of the weekdays, the average print requests given per hour were 1200. Due to large
memory space occupied by requests having size larger than 40 MB, these print requests
blocked the print queues not allowing the small-sized print requests to process. As a result,
large queues used to form leading to large waiting times for the users in the print collection
desk. Occasionally, there was jamming of print-jobs at one of the printers blocking the other
print jobs. All these factors increased the waiting time for users and this was the reason an
additional printer was bought.
In the current system, large print jobs are routed to the fourth printer based on the size
of the print jobs. This process however neglects the RIP time associated with a print job. The
performance of the older system with three printers is compared with the current model of
four printers by using Extend to simulate the respective models. The efficiency parameters
such as throughput rate, process utilization and process capacity are calculated and compared
to determine the performance of the old and current systems. The recommendation is to
implement rerouting software in the print server that will reroute print jobs to the fourth
printer not only based on the print size but also based on the blocking RIP time of the jobs.
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
2. Introduction:
Open access computer lab (OALs) provides computing and other information technology
related services to the faculty, students and staff of Texas A&M University. There are 13 labs
throughout the TAMU campus which comprise the Open Access Lab system.
The following data briefly outlines the IT-infrastructure of the OAL:
• 1800 computers: one-third replaced every year to stay abreast with technology changes
• 49 servers: 3 year replacement cycle
• 13 large scale printers: 5 year replacement cycle
Various services provided by the OAL-CIS include:
• Maintenance of student and faculty accounts
• Providing wireless access throughout the campus
• Trouble shooting of software and hardware related faults
• Software applications for students, staff and faculty at reduced rates
• Classrooms for special classes
Our case study is focused on the Student computing Centre and its operations as it is the
busiest lab in the OAL system with an average of more than 400 users using the lab during peak
hours. The SCC has the following equipments
• Apple iMacs - 15
• Plotter
• PC Workstations - 556
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
• Linux Workstations - 1
• Black and White Printer (Backup) - 1
• Color and Transparency Printers - 2
• Graphic Workstations - 5
• Black and White Printers - 4
• Laser Graphics Personal LFR Plus - 1
• Digital Video Capture/Record Workstation - 5
• Scanners - 27
• Slide Scanner - 2
• Gateway Wireless Laptop - 2
• USB Floppy Drives (for IMACs) - 2
In addition, the SCC houses three classrooms as well as group-study areas in its two-storey
facility. Appendix 1 and 2 shows the average number of users at SCC and the printer utilizations
respectively.
The services at the SCC are classified into the following groups:
1.1 Information Desk Operations:
The information booth of the SCC handles all incoming calls and can provide customers
with immediate help to some questions. If a customer requires further help, the CIS staff
working at the information booth can direct customers to other sources of help.
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
1.2 Help Desk Operations:
The Help Desk at the SCC is staffed by knowledgeable student workers available to
answer any question a customer has. When immediate solutions cannot be found, the staff will
find another means of answering the question by enlisting the help of another staff member,
calling Help Desk Central, or consulting a manual. If all else fails, the staff can open a Keystone
slip to have the question researched until an answer is found.
1.3 Resource Desk:
The resource desk contains any peripherals needed at the SCC. These peripherals are
available on a check-out basis and must be returned immediately after use. The resource desk
also houses many product manuals available for check out and the color and large-format
printers of the SCC.
1.4 Print Rooms Operations:
The Student Computer Center's print rooms are located on the left side of the building
on both the first and second floor. Users by logging in with their ID’s can give print outs that is
collected from the printers and stacked in shelves by CIS workers. Scope will be limited to the
Process Analysis and Design of the first floor print room operations at the SCC.
3. Scope of the project
The focus of this project is on analyzing and improving print room operations of SCC for
the peak hours from 9.00 AM to 6.00 PM. Apart from that, some suggestions for improvement
in other operations at SCC will also be made; however, these suggestions are more business
and customer oriented rather than process oriented. The study focuses on print room
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
operations of the SCC mainly because of the complaints of customers having to face large
waiting times for their prints. The process analysis focuses on the printers that are present in
SCC and how the print queues can be routed properly to allow a proper utilization of the
printers and reduce the waiting time of the users to collect the print outs during the peak hours
of SCC.
4. Process description
Each time a user gives a printout the information goes to the server where the
information is stored. The server initiates the printing process by sending the information to the
print queues. Initially the information is RIPped (Raster Image Processing) which essentially
means that the files are converted to a print-system readable format. This is essential because
the print server is UNIX based whereas the SCC houses three different operating systems
(WINDOWS, LINUX and MACINTOSH). Each printer has a queue where the print orders are
prioritized as per their arrival time in the queue; in other words it’s a FIFO queue. After RIPping,
the files are printed by the printers and are output into print trays. Student workers then collect
the prints and file them as per the USER IDs.
Usually print orders with low memory and low number of pages are ripped faster and
printed quickly; however when the size of information coming through increases to say 40 MB,
the RIP process takes longer time to finish. This causes a long RIP queue being formed which in
turn blocks the print orders that follow. This increases the waiting time for the users. To
aggravate the condition, paper jams in any of the printers cause the print operations to stop
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
leading to long RIP queues. These jams are cleared manually by the stationed student workers.
The process flow of the system is shown in Appendix.3
5. Problem Description and Analysis:
Till the end of 2008, there were three printers in print room. The three printers were
identical with an image processing speed of 90 iPM (images per minute).
In the last quarter of 2008, customer complaints about long queues and large waiting times
began pouring in. Concerned, the management outlined the following practices to handle the
complaints:
• Manually routing large prints to one designated printer
• Holding large prints and releasing them later in lean hours.
However, the problem was still not resolved. Designating one printer only for large files
essentially implied there were only two printers available for printing the regular prints.
Moreover, the size of “large” files was left at the discretion of student workers stationed in the
print-room at that hour. Holding the files was also not advisable as many students wanted their
files released immediately so as to attend classes.
To get over this situation, the management finally decided to order printer. Because of
an improved processor, the new printer that was installed in January 2009 can process the
orders at a much higher rate. In addition, the printer has an image processing rate of 110 iPM
(images per minute).
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
Upon installation, two separate queues were created for the new printer. One was a
regular queue that would accept all file whereas the other queue was named “Large” and
would only accept files larger than 40 MB. This move proved effective and customer
complaints reduced considerably.
However, due to fixed definition of large file at 40 MB, a file of 39.9 MB can go to any of
the printers (including the older printers). This still causes problems of blocking and
consequently large queues. Due to this a student worker has to be around continuously
monitoring the print logs and rerouting the large files in the small printer queues to the large
printer queue. While the problem is not very pronounced currently, this project is aimed at
providing additional suggestions that can further increase the efficiency of the system.
6. Process Variables
The following process variables were identified and considered for the designing the model
in Extend.
• Inter Arrival Time
• RIP Time
• Print Time
• Filing Time
6.1 Inter Arrival time:
It is the distribution of the prints that are given by the users from the work station.
6.2 RIP Time
RIP time is the time taken to transform the digital information about fonts and graphics
that describes the appearance of the file into an image composed of individual dots to the
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
printer. Raster Image Processor is a firmware i.e. a printer driver software which takes the
image and text of the print jobs and tells the wide format printer where and how to place each
squirt of ink on the paper.
6.3 Print Time
The time a print job was initiated at one of the terminals of the computer
6.4 Filing Time
Time taken to file the printouts collected from the printer tray
7. Basic Data Collection and Analysis:
For the purpose of modeling the process in extend, the following parameters were needed
• Print Inter arrival time
• RIP Start time and stop time
• Print start time and stop time
• Number of Pages in a print order
• Memory size of each print order
The following information was collected from the print logs of the print rooms for the peak
hours of the SCC. These data were statistically fitted with proper distributions using statistical
distribution fitting and linear regression analysis.
7.1 Print inter-arrival times
The input data was analyzed using Chi squared goodness of fit tests on commercially
available software. The distribution was selected based on the rank and availability in the
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
simulation software. It was seen from the statistical distribution fitting that the inter arrival
times fell under Weibull distribution and the parameters required for this distribution were
noted. The rank and the distribution that was found using Chi –squared test are shown in the
table 1
Distribution Rank
Weibull 1
Normal 2
Beta 3
Lognormal 4
Exponential 5
Erlang 6
Table 1. Inter Arrival distributions
7.2 Number of Pages
The same process was carried out for the number of pages using statistical tests for
discrete distributions. Poisson distribution was selected to model the number of pages file.
7.3 Correlation between RIP time and file size:
Linear regression lines fitted through data points, initially the data were separated based
on the file size. Data with file size greater than 1 MB and less than 1 MB was grouped separately
and regression lines were fitted. Linear regressions were fitted for both the cases and some
randomness was given to the smaller file size as they were not exactly linear. The linear
aggression analysis is shown in the figure 1
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
12 50
y = 3.9116x + 1.7472 y = 0.9851x + 9.7144
10 40
Time in Seconds
Time in Seconds
8
30
6
20
4
2 10
0 0
0.0 0.5Size in MB 1.0 1.5 0.0 10.0 20.0 30.0 40.0
Size in MB
Figure 1. Linear Regression Analysis
8. Time Motion Analysis
The layout of the print-room is shown in appendix 4. The present system employs two
student workers in the lean hours and three during peak hours. The workers are usually
stationed at one of two the workstations, while the third worker is stationed around the large
printer (in the aft row). The prints come out onto the print trays in the order that they were
received and hence are not sorted. Thus a student worker who picks up a batch of completed
printouts from the tray has to traverse through the entire file rack, in the order that the prints
were received. It is quite obvious that this process can be made more efficient by reducing the
distance a student worker has to move.
One way to achieve this is by segregating the prints into three parts in the alphabetical order.
Thus, first printer will only receive documents whose user IDs are from A to I, the second from J
to S and so on. The accuracy of this categorization can be increased by performing a statistical
data analysis and obtaining the distribution for various user IDs. Alternatively, this can be done
in real time by analyzing the User IDs of the users present in the lab and distributing them in
three parts. The accuracy of the system will depend on the functionalities of the software being
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
used. Due to confidentiality concerns, the User IDs were not available for analysis and hence,
data analysis using random numbers was performed. The result for the analysis is presented in
the following table 2.
Current Proposed
Jobs Distance Jobs Distance
3 47 4 13
4 45 6 23
4 44 6 16
6 52 7 28
6 54 8 21
6 56 8 27
7 89 9 23
7 74 9 44
9 93 10 48
11 81 12 27
11 86 12 34
11 101 12 35
Table 2. Time Motion Analysis
As is evident from the data presented, the distances moved by the student workers in the
proposed system is between half and one-third of the distances moved in the current system.
Thus, such a step would considerably improve the efficiency of the process.
9. Modeling considerations:
The following components were used to simulate the following processes of our model and are
shown in Appendix 5.
9.1. Pausing and holding of jobs
Pausing of jobs occurs when a printer is not able to process the print jobs present in its queue
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
Sometimes the print jobs are delayed due to inexplicable reasons.
This phenomenon is depicted in our model by using a delay block and a DE Output block. The
DE output block routes 1% of the incoming jobs to the delay block which holds the print jobs.
The remaining 99% jobs are routed to a decision block.
9.2. File segregation and routing
The decision block routes jobs with a Memory size of less than 20MB to one of the four small
print queues named SCC 1 to SCC 4. The large print jobs are routed to the large print queue
9.3. Ripping and Printing
Ripping process for the jobs from the queues is depicted using Machine blocks. After the
ripping process is complete, the jobs are routed to the Printing machine blocks. The printing
process is depicted using Machine blocks which are connected with a down-time block that
specifies the anticipated down time during the printing process.
9.4 Random batching of jobs
The jobs are randomly batched based on the motion-study analysis simulated using the Input
Random Number and Equation block. The equation block simulates the motion time analysis.
The print jobs are then carried by the student workers. The student workers are depicted by
using Transporter block. The student workers carry the print jobs to the print-file racks.
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
10. Results
Four cases have been analyzed using the simulation model:
• Current system
• Current system with time motion analysis results implemented
• Old system
• Old system with time motion analysis implemented
The results are shown in Appendix 6.
As is evident from results (please refer to the RIP utilization for current system and RIP
utilization for old system with time motion analysis implemented), the old system was capable
of handling the peak hour demand for printouts. Moreover, the time analysis implementation
shows a considerable reduction in the number of jobs left on the print tray at the end of
simulation, both in the old system as well as the current system.
11. Recommendations:
After carrying out a comprehensive analysis of the available data and empirical facts
provided by the management at SCC, we would make the following recommendations to
improve the processes at SCC:
11.1 Print Room Recommendations:
Purchasing re-routing software packages for the printers that are featured with the
following capabilities:
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
11.1.1 Redefining file size
Currently, print jobs with size less than 40 MB are routed to of one the four queues
responsible for handling print jobs with size less than 40 MB. However, it has been observed that
quite a few print jobs have an average size ranging between 20 MB and 39.9 MB and are thus
routed to the three printers with lower capacities. This increases the utilization of these small
printers increasing the waiting time of print jobs in the queues. Currently the print jobs have to
be rerouted manually by the student workers to the large queue thereby increasing their
utilization.
It is thus recommended that re-routing software be implemented in all the printers that will
automate the routing process of the print jobs based on following considerations:
• Routing to be done based on rip time instead of file size.
• In case of an accidental large file coming in the small file queue and taking a larger time to be
processed, the software to re-route it to the larger printer.
• Reducing the set definition of large file from 40 MB to 20 MB.
11.1.2 Segregation of printers based on alphabetical ordering of the user IDs
It is recommended that the printers be assigned jobs for specific alphabet ranges in
accordance with their proximity to the print-filing racks. Based on a time motion analysis carried
out to establish the motion of student workers between print-filing racks and printer locations, it
is observed that the total no of visits of the student workers to the print-filing racks is reduced
two to three-folds by re-aligning printers according to user-id’s, a considerable improvement
over the current system.
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
11.2 General recommendations:
11.2.1 Macintosh orientation during induction
Many users come for WPA installation and they are dissatisfied as student workers are
not conversant with Macintosh.
11.2.2 Rotation of student workers between different labs
As certain labs are busier than others, it is advised that student workers be rotated
between different labs to ensure fairness by means of equitable distribution of work among the
student workers. This will improve the morale and efficiency of workers.
12. Conclusion:
It is observed that in the older system with three printers, the capacity was not
sufficient enough to handle the print jobs during peak hours. In the current system with four
printers, it is observed that the rerouting software can improve the utilization of the smaller
printers. It is observed that if the rerouting software is installed for the previous system with
three printers, the capacity improvement is sufficient to satisfy the demand during peak hours.
However, the load for the two student workers would become large. Thus, the current system
with four printers and three student workers is a better system though it has potential for
further improvements. The improvement will be in the form of reduced blocking of small print
jobs facilitated by the software packages which reroute the print jobs to the large queues based
on the RIP time and size of print jobs.
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
APPENDIX 1. Average number of users at SCC
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
APPENDIX 2 Printer Utilization
Printer 1
Printer 2
Printer 3
Note: Data for the Printer 4 is not updated.
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
APPENDIX 3a PROCESS FLOW CHART: UNTIL DECEMBER 2008
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
APPENDIX 3b PROCESS FLOW CHART: SINCE JANUARY 2009
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
APPENDIX 3C Process Flow Diagram
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
APPENDIX 4 Time Motion Analysis
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
APPENDIX 5 MODEL
ev ent Activ ity
Queue
Stats
Stats
count Update Update
T U
D M
Set A(5) D
Rand
sensor
1 2 3
T 0.01 a
Rand ?
0.99 b
Set A(5)
select Get
1 2 3
L w p A
Memory
∆
No of Pages
R
p
Serv er Queue Get Rand
Rand
A
∆ 1 2 3
1 2 3 Memory
No of Papers
Eqn
Eqn

Rand
1 2 3
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
APPENDIX 5 MODEL
T
# #
C T U
L w p L w p
T U S T U S Count Var Trans 36
n
R r # demand speed
R p
p A D down
1 2 A D down
SCC 1 OP 1
RIP 1 Printer 1 Rand
Eqn
L w p s 1 2 3 #
T U S #
T U S 3 4 L w p C T U
Count Var 29
R Trans
p n
A D down R
SCC 2 A D down p r # demand speed
Printer 2
RIP 2 1 2 OP 2
Rand
Eqn
L w p 1 2 3 #
s C #
T U S T U S L w p T U
3 4 Count Var Trans 37
R n
p
A D down R r demand speed
SCC 3 A D down p #
RIP 3 1 2 Printer 3 OP 3
Rand
Eqn
L w p s
T U S L w p 1 2 3
Set A(5) 3 4
Get T U S #
R
p Get C #
R T U
SCC 4 A A D down p 38
Count
A ∆ A D down OP 4 Var Trans
Printer 4 n
∆ No of Pages RIP 4 r #
1 2 demand speed
Memory
L w p
R s
p
3 4 Rand
Large Queue
Eqn
Eqn 1 2 3
Rand Eqn
1 2 3
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
APPENDIX 5 MODEL
event Activity
Queue
Stats
Stats
count Update
Update
T
T U # #
C T U
D M L w p T U S
L w p
T U S Count Var Trans 36
Set A(5) n
Rand D
R r # demand speed
R p A D down
p
sensor A D down OP 1
SCC 1 RIP 1 1 2
Printer 1 Rand
12 3
Eqn
T 0.01 a
L w p s 1 2 3 #
T U S #
Rand ?
0.99 b 3 4 L w p C
T U S T U
Set A(5) Count Var Trans 29
select Get R p n
A D down R
1 2 3 SCC 2 A D down Printer 2
p r # demand speed
Memory L w p A OP 2
RIP 2 1 2
∆ Rand
No of Pages
Eqn
R p
Server Queue Rand L w p 1 2 3 #
Get #
T U S s L w p C
Rand T U S T U
3 4 Count Var
A Trans 37
R p n
∆ 1 2 3
SCC 3 A D down R p r # demand speed
1 2 3 Memory A D down
RIP 3 1 2 Printer 3 OP 3
No of Papers
Rand
Eqn Eqn
L w p s
L w p 1 2 3
Set A(5) 3 4 T U S
Get T U S #
R p Get C #
SCC 4
R p T U
A A D down Count 38
Var Trans
A ∆ A D down Printer 4 OP 4
n
Eqn
 ∆ No of Pages RIP 4
1 2
r # demand speed
Memory
L w p
Rand
R p s
Large Queue 3 4 Rand
1 2 3
Eqn
1 2 3
Eqn
Rand Eqn
1 2 3
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
APPENDIX 6a Results
Print Stats
4 Printers - Proposed
PRINTER UTIL RIP UTIL
1 0.58 1 0.70
2 0.54 2 0.60
3 0.55 3 0.63
4 0.49 4 0.38
4 Printers - Current
PRINTER UTIL RIP UTIL
1 0.63 1 0.68
2 0.57 2 0.69
3 0.50 3 0.64
4 0.42 4 0.37
3 Printers - Proposed
PRINTER UTIL RIP UTIL
1 0.59 1 0.67
2 0.58 2 0.69
3 0.57 3 0.64
3 Printers - Current
PRINTER UTIL RIP UTIL
1 0.60 1 0.80
2 0.56 2 0.78
3 0.63 3 0.74
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SCC Print Room Operations Parijat Sinha, Pradheep Lakshmanaswamy, Keyur Sadhani
APPENDIX 6b Results
Queue Stats
4 Printers - Proposed
MAX AVG MAX
AVG LENGTH ARRIVALS DEPARTURES
LENGTH WAIT WAIT
OP 1 Stack 0.07 5 1.02 28.68 365 365
OP 2 Stack 0.09 7 1.11 51.83 335 335
OP 3 Stack 0.03 5 0.40 30.57 342 342
OP 4 Stack 0.70 18 8.34 76.26 393 393
4 Printers -
Current
MAX AVG MAX
AVG LENGTH ARRIVALS DEPARTURES
LENGTH WAIT WAIT
OP 1 Stack 19.04 58 218.51 511 374 340
OP 2 Stack 8.52 48 92.00 350.67 393 319
OP 3 Stack 19.73 72 199.01 568.64 367 349
OP 4 Stack 42.98 145 316.89 876.81 390 331
3 Printers - Proposed
MAX AVG MAX
AVG LENGTH ARRIVALS DEPARTURES
LENGTH WAIT WAIT
OP 1 Stack 0.10 5 0.89 25.22 340 340
OP 2 Stack 0.20 9 1.85 63.29 319 319
OP 3 Stack 0.03 5 0.25 22.32 349 349
3 Printers -
Current
MAX AVG MAX
AVG LENGTH ARRIVALS DEPARTURES
LENGTH WAIT WAIT
OP 1 Stack 39.25 172 615.83 1578.00 430 181
OP 2 Stack 20.20 196 727.92 1640.00 416 181
OP 3 Stack 50.96 169 980.59 1754.40 387 130
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