ISYE SIM ARENA Week 6, 7

What sequence of Arena modules would you use to generate customer arrivals, use a server, and then have customers leave the system after they're done with the server?

a) Seize-Delay-Release

b) Create-Resource-Leave

c) Create-Process-Dispose

d) Create-Seize-Dispose

c) Create-Process-Dispose

TRUE or FALSE: Arena uses the P-I world view

True

TRUE or FALSE: The Basic Process template contains a number of spreadsheets, e.g. a Resource spreadsheet

True

Go to the Basic Process template and drop and drag a Create module over the main screen. Now click into the module. What do you see?

a) A field for "Time Between Arrivals

b) A field for time units

c) A field for "Entities per Arrival"

d) A field for "First Creation"

e) All of the above

e) All of the above

Go to the Basic Process template and drag and drop Create-Process-Dispose modules in that order. They should connect automatically. The "Connect" button connects the modules nicely. Now run the simulation by hitting the "Go" button. At this point you should see little guys getting generated and flowing from left to right, but do you see lines forming?

a) Yes, I see long lines with angry customers

b) No, I don't see any lines

b) No, I don't see any lines

From a Create-Process-Dispose module, click in the Process module and choose the "Seize Delay Release" option from the Action drop-down. Add 1 resource from the Resources menu, click ok and run the program. What do you see?

a) I see little guys running from left to right with an occasional line forming over the Process module

b) I see little guys running around but no lines

c) I don't see any movement

a) I see little guys running from left to right with an occasional line forming over the Process module

What happens if you choose the "Seize Delay" option from the Action drop down instead of choosing the "Seize Delay Release" option?

a) Little guys running from left to right with an occasional line forming over the Process module

b) You won't see any customers leaving and the line will get pretty big

b) You won't see any customers leaving and the line will get pretty big

Which spreadsheets are available in the Basic Process template?

a) Attribute spreadsheet

b) Entity spreadsheet

c) Queue spreadsheet

d) Reduce spreadsheet

e) Variable spreadsheet

f) All of the above

f) All of the above

Joe is a customer who needs to go to Point A with probability 0.5, Point B with probability 0.2, and Point C with probability 0.3 - which Decide module option would he use to do so?

a) 2-way by chance

b) n-way by chance

c) 2-way by condition

d) n-way by condition

b) n-way by chance

TRUE or FALSE: We can use the Assign Module to change an entity's picture

True

TRUE or FALSE: The system's work-in-process will typically be a variable - not an attribute

True. Attributes are properties for individual customers. Variables are properties of the entire system

Which expression will give you the number of customers in the queue called DaveRules.Queue in front of the server called Dave?

a) NQ(Dave)

b) NQ(DaveRules)

c) NQ(Dave.Queue)

d) NQ(DaveRules.Queue)

d) NQ(DaveRules.Queue)

What is the Separate module dialog box doing?

Name: Separate

Type: Duplicate Original

Percent Cost to Duplicate: 50

# of Duplicates: 2

a) A customer enters the block and then emerges along with an exact clone of himself

b) A customer enters the block and then emerges along with two exact clones of himself

c) Two customers enter the block and are then merged into one exiting customer

d) Three customers enter the block and are then merged into one exiting customer

b) A customer enters the block and then emerges along with two exact clones of himself

Model a single-server queueing system (e.g., a barber shop) with first-in-first-out queueing priority. Let the interarrivals be i.i.d. exponential with a mean of 10 minutes, EXPO(10), and let the services be i.i.d. TRIA(5,8,11) with the units in minutes.

What is the % of time that the server is busy?

a) 8

b) 20

c) 50

d) 80

e) 100

(d). This follows since the traffic intensity = arrival rate/service rate = (1/10)/(1/8) = 0.8.

If you run the thing for a while, you'll see that the rework Station gets pretty clogged up every once in a while - probably because the service times are EXPO(45) minutes. Let's suppose that management has noticed this as well and decides to upgrade that station so that the service times are now EXPO(10). Go ahead and make this change and comment on what you see.

a) There are still very long lines at Rework almost all of the time

b) There are occasionally extremely long lines at Rework

c) There are occasionally short lines, but long lines are very rare

d) There is never ever any line at Rework

c) There are occasionally short lines, but long lines are very rare

What is the value of the related logic expression? ((1 == 1) 10) + ((1 == 0) 5)

a) 0

b) 1

c) 5

d) 10

e) 15

d) 10

Since 1==1 is true and 1==0 is false, we have (110) + (05) = 10

TRUE or FALSE: You can find individual Seize, Delay and Release modules in this template

True

Where can you find some sort of Seize?

a) Within a Process module in the Basic Process template

b) A Seize module in the Advanced Process template

c) A Seize block in the Blocks template

d) All of the above

d) All of the above

Where can you set the buffer size of a certain queue?

a) Within a Process module in the Basic Process template

b) In a s Seize module in the Advanced Process template

c) In a Seize block in the Blocks template

d) In a Queue block in the Blocks template

e) In the Queue spreadsheet in the Basic Process template

f) All of the above

d) In a Queue block in the Blocks template

TRUE or FALSE: It's possible to request servers in a set randomly, cyclically, or according to some priority characteristic (such as the order in which they are placed in the set)

True

What would I do to change the lead time of orders from my supplier to UNIF(0,1) days (which happens to be a little faster than the current lead time)?

a) Go to the Variable spreadsheet in the Basic Process template and change the variable Delivery Lag to UNIF(0,1)

b) Go to the Expression spreadsheet in the Advanced Process template and change the expression Delivery Lag to UNIF(0,1)

c) Go to the "Wait for Delivery" Delay module in the main program and change the expression Delivery Lag to UNIF(0,1)

d) Bypass the "Ordering Decision" Decide module

e) Either b or c, since both are correct

e) Either b or c, since both are correct

The various queues build up and them calm down; but the peaks tend to get bigger and bigger as time passes.

One of the issues is due to the fact that we have strange priorities on the two servers depending on where the customer is in the model. Those priorities are set in the Process modules, just to the right of the Seize-Delay-Release sequence.

Question: What happens when you set the priorities to "Medium" in each of the 5 process modules?

a) All of the queues still exhibit that crazy behavior

b) A couple of the queues, but not all of them, still exhibit crazy behavior

c) Surprisingly things pretty much calm down

c) Surprisingly things pretty much calm down

What is the name of Arena's primary modeling approach world view?

a) Process-Interaction

b) Event-Scheduling

c) Continuous Modeling Flowchart

d) Mixed Modelig

e) Event-Interaction

a) Process-Interaction

TRUE or FALSE: the Basic Process panel contains various modules that can be used to flowchart simple models.

True

Which modules appear on the Basic Process panel?

a) Create

b) Dispose

c) Process

d) Hold

e) All of the above

f) Only a, b, c

f) Only a, b, c

TRUE or FALSE: The Basic Process template contains both modules and spreadsheets.

True

TRUE or FALSE: A Create module allows you the use a variety of customer interarrival time distributions.

True

Which of the following action sequences can you find in a Process module?

a) Delay

b) Seize-Delay

c) Delay-Release

d) Seize-Delay-Release

e) All of the above

e) All of the above

TRUE or FALSE: A process is generally considered to consist of both a resource and its associated queue.

True

TRUE or FALSE: You can change the number of servers on duty (i.e., the capacity) for a resource using the Resource spreadsheet.

True

TRUE or FALSE: You can change a queue discipline from FIFO to LIFO with one click by using the Queue spreadsheet.

True

Which is the only functionality of the Decide module that is 𝑛𝑜𝑡 offered?

a) 2-way by chance

b) n-way by chance

c) 2-way by choice

d) 2-way by condition

e) n-way by condition

c) 2-way by choice

Which is the only item that is probably not an attribute?

a) Customer's height

b) Priority of an entity

c) System's work in process

d) Entity's picture

e) Patient's blood pressure

c) System's work in process

Where can you set or chance a customer's picture?

a) Assign module

b) Assign spreadsheet

c) Attribute spreadsheet

d) Variable spreadsheet

e) Entity spreadsheet

f) both a and e

f) both a and e

Name: Barbershop

Resources: Resoure, Barber, 1

Suppose the queue has exactly 4 customers in it. Which of the following is true?

a) NQ(Barber) == 4

b) NQ(Barber.Queue) == 4

c) NQ(Barbershop) == 4

d) NQ(Barbershop.Queue) == 4

e) NR(Barber) == 4

d) NQ(Barbershop.Queue) == 4

TRUE or FALSE: You can use the Batch module to either merge customers together permanently (so that you can't recover all of their original attributes, even with a Separate module) or temporarily (so that you can eventually recover the original customers).

True

TRUE or FALSE: If you have a Temporary batch, then you can use the command Split Existing Batch to reproduce entities having their original attributes (before getting Batch'd).

True

If I wanted to make 5 runs of the simulation, each lasting 100 hours, what would I do in the Run Setup menu?

a) Set Number of Replications = 5, Replication Length = 100

b) Set Number of Replications = 100, Replication Length = 5

c) Set Number of Replications = 5, Replication Length = 5

d) Set Number of Replications = 100, Replication Length = 100

e) Set Number of Replications = 5, Replication Length = infinite

PreviousNext

a) Set Number of Replications = 5, Replication Length = 100

TRUE or FALSE: You can pre-assign a service time as an attribute before you actually get to the server that you'll be using

True

TRUE or FALSE: If you have Create module generating one-at-a-time customer arrivals, then it is not possible to use a different Create module with 4-at-a-time customer arrivals

False

TRUE or FALSE: Fake customers can be used to schedule machine breakdowns, keep track of which time period the simulation is currently in, and carry out other duties not associated with actual customers.

True

Which module / spreadsheet is NOT in the Advanced Process panel?

a) Seize

b) Delay

c) Release

d) Process

e) Expression spreadsheet

f) Failure spreadsheet

d) Process Module

Why are things like Seize, Delay, Release in multiple templates?

a) The Process module does not allow us to use Seize, Delay, Release with sufficient generality

b) What are you talking about? Seize, Delay, Release are not in multiple templates!

a) The Process module does not allow us to use Seize, Delay, Release with sufficient generality

TRUE or FALSE: You can schedule failures to occur after a random number of customers have used a resource or after a random amount of time has passed.

True

TRUE or FALSE: You are only allowed to schedule one type of failure for a particular resource

False

Which block is 𝑛𝑜𝑡 in the Blocks template?

a) Seize

b) Delay

c) Release

d) Alter

e) Queue

f) Process

Process block

TRUE or FALSE: The Queue block can connect up to the Seize module from the Advanced Process template.

False

Which kinds of sets are allowed?

a) Resource set

b) Counter set

c) Entity type set

d) Entity picture set

e) All of the above

e) All of the above

TRUE or FALSE: It is possible for the resource Joey to be a member of three different resource sets.

True

TRUE or FALSE: For easy display and organizational purposes, our Call Center simulation is divided into several submodels

True

TRUE or FALSE: The customer arrival pattern for our Call Center changes over the day and is therefore modeled as a nonhomogeneous Poisson process

True

TRUE or FALSE: All of the Tech Support servers for our Call Center are equally skilled and have the same concurrent work schedules

False

TRUE or FALSE. In our Call Center demo, fake customers are used to update a variable that keeps track of the period of the day

True

Consider our Call Center demo. What is the following Seize request asking for? Set, Product 1, 1, Preferred Order, Agent

a) Grab one server from the set Product 1 in the order listed when the set was defined, and store that guy's identity in the attribute Agent

b) Grab a random server from the set Product 1 and store that guy's identity in the attribute Agent

c) Grab a random Agent from the set Product 1 and store that guy's identity in Preferred Order

d) Set the value of the variable Product 1 equal to 1. Do this in Preferred Order (i.e., with high priority), and then store that value in the attribute Agent

a) Grab one server from the set Product 1 in the order listed when the set was defined, and store that guy's identity in the attribute Agent.

TRUE or FALSE. In our Inventory demo, fake customers are used to initiate a periodic inventory review.

True

Consider the Arena expression DISC(0.3, 1, 0.5, 3, 1.0, 6), which is a discrete random variable. What is this random variable's expected value?

0.3 -> 0.5 -> 1.0 is a cdf so the probabilities are actually 0.3, 0.2, 0.5

0.3 1 + 0.2 3 + 0.5 * 6 = 3.9

Consider a vanilla (s,S) = (5,12) inventory policy. If my inventory slips to 3, how many items do I order?

a) 5

b) 12

c) 9

d) 7

c) 9

TRUE or FALSE: It's perfectly Ok for a customer to go from Server 1 to Server 2 and then back to Server 1

True

TRUE or FALSE: Crazy stuff can happen if you start fooling around with multiple server visits, service priorities, and server times.

True

TRUE or FALSE: There are 100s of SMARTS files for you to play around with.

True