Level Rate Diagrams (LRDs)

Question 1

True or false

LRDs are the most important concept in HSD

Answer 1

True

Question 2

Which provides more information between a CLD and a LRD?

Answer 2

A LRD.

Question 3

What type of analysis do LRDs provide?

Answer 3

Has actual numbers allowing for quantitative analysis.

Question 4

What are rates associated with?

Answer 4

Rates have flows associated with them.

Question 5

Levels have accumulated over time and ___ conditions.

Answer 5

initial

Question 6

What are LRDs an essential step in?

Answer 6

LRDs are an essential step in building a model for simulations.

Question 7

What do LRDs shift focus away from?

Answer 7

Shifts focus away from an individual in the system to see larger accumulation.

Question 8

What are the components of LRDs? (5)

Answer 8

• Level (stock)
• Rate (flow)
• Auxiliary variable
• Boundary
• Arrows

Question 9

What is a Level (stock)?

Answer 9

Variable in a system that accumulates and represents the state of the system at a given time. (stuff of the model)

Question 10

What is a Rate (flow)?

Answer 10

Variable in a system that represents the rate of change of a quantity over time and influences the level either positively (as an inflow) or negatively (as an
outflow).

Question 11

What is an Auxiliary variable?

Answer 11

Additional variable that is neither a level nor a rate and often represents a coefficient, conversion factor or lookup table.

Question 12

What does a boundary do?

Answer 12

Limits of a model.

Question 13

What is the function of arrows in LRDs?

Answer 13

Links the components of a system drawing to illustrate dependencies.

Question 14

What do state variables do?

Answer 14

Identifies the state of the system.

Question 15

Levels (stocks) must be ______.

Answer 15

quantifiable

Question 16

Accumulations all around us

- Levels with ____ rates can go up and levels with ____ rates can go down

Answer 16

inflows

outflows

Question 17

Accumulation of the net flow rate over time

- Net flow rate = ______________________.

Answer 17

Net flow rate = inflow rate – outflow rate

Question 18

How are levels (stocks) represented mathematically?

Answer 18

Mathematically represented by an integral.

Question 19

How are rates always measured?

Answer 19

Always measured per unit time.

Question 20

What is a rate?

Answer 20

Represented variables/events that cause levels to increase or decrease

Question 21

Do rates have memory?

Answer 21

No memory.

Question 22

How are rates mathematically represented?

Answer 22

Mathematically represented as derivatives dy/dx.

Question 23

How do you get an increase and decrease in rate?

Answer 23

Increase: inflow
Decrease: outflow

Question 24

What is the function of an auxiliary level? (3)

Answer 24

• Adds additional information to the model (not a level or rate)
• Adds model transparency and details (decreased abstractions or hidden information)
• Allows model to function properly

Question 25

What could auxiliary variables contain? (3)

Answer 25

Could contain: - Numerical value (constant) - Equation or calculation - Look up table

Question 26

What do boundaries focus on?

Answer 26

Focuses on modelling and not real world phenomena.

Question 27

What are boundaries?

Answer 27

Boundaries are an important part of modelling and define the part of the system we are interested in.

Question 28

In terms of boundaries, Start: End:

Answer 28

Start: Source End: Sink

Question 29

What is the equation of an example level?

Answer 29

Question 30

What is the equation for example rate?

Answer 30

Question 31

What is the OTHER formula for example level?

Answer 31

Question 32

What does the differentiation of a level result in?

Answer 32

Question 33

``` What are the level rate pairs for the following? Distance (m) - Speed (m/s) - Energy (J) - Charge (C) - ```

Answer 33

Distance (m) - (m/s) Speed/Velocity Speed (m/s) - (m/s^2) Acceleration Energy (J) - (J/s) = W Power Charge (C) - (C/s) = A Current

Question 34

What is dimensional analysis?

Answer 34

Analysis of relationship between physical quantities.

Question 35

What are the two parameters for dimensional analysis? (2)

Answer 35

- We analyse the units measured | - Treat units as algebraic

Question 36

What are the base Si units? (5)

Answer 36

Question 37

What are the Si prefixes?

Answer 37