1. Week 7 - Systems Engineering and Analysis
Buede Chapter 12 –
Graphical Modeling Techniques
Image from
Left – Systems engineers us a lot of graphical models which look like state diagrams. If you have to predict how the pieces of a large system will interact, you need help visualizing that. This one is a “generative model for how to create generative models.”
SE-Week 6

2. Wasson also talks about modeling
Mostly scattered by topic – what you are modeling.
E.g., Sec 15.2 – System behavioral response model
Ch 17 – Use Cases & UML
Ch 20 – Modeling system and support operations
Ch 51 – System modeling and simulation

3. Data, Process, and Behavior Models
Data Models – relationships among input and outputs.
Process Models – define functional decomposition of the system function and flow of inputs and outputs for those functions.
Behavior Models – define the control, activation, and termination of of system functions needed to meet performance requirements.

4. Modeling Approaches & Methods
Data Modeling
Entity-relationship diagrams (ERDs)
Higraphs
Process Modeling
Data flow diagrams (DFDs)
IDEF0
N2 charts
Behavior Modeling
Function flow block diagrams (FFBDs)
Behavior diagrams (BDs)
State-transition diagrams (STDs)
Statecharts
Control flow diagrams (CFDs)
Petri nets (PNs)
Object-oriented Modeling
Object modeling technique (OMT)
Real-time object-oriented modeling (ROOM)
Table 12.1

5. Data Flow Diagram Semantics
Figure 12.6

6. Context (External Systems) Diagram in DFD
Figure 12.9

7. N2 Charts – an SE favorite!
Figure 12.10

8. Function Flow Block Diagrams
Basic
Series
Concurrent
Selection
Multiple-exit function
Enhanced
Iteration
Looping
Replication
Series
Concurrent
Figure

9. Selection & Multiple-exit Functions, Iteration, Looping in FFBD
Figure 12.13

10. FFBD for Elevator

11. Elevator Functional Architecture

12. Behavior Diagrams
Figure 12.14

13. Finite State Machines
Finite state machines: discrete valued inputs, outputs and internal items
Sequential: past inputs impact current outputs (e.g., state-transition diagram)
Combinational: current outputs characterized only current inputs
Continuous machines: continuous and discrete inputs, outputs and internal items
Figure 12.16

14. State-transition Diagram for ATM
Event
Output
Partially
Completed
Figure 12.17

15. State-transition Diagram for an Elevator
Figure 12.18

16. Statechart External System Statechart For Cruise Control System
Figure 12.19

17. For Cruise Control System
Statechart, cntd
Decomposition of the
“Not Off” State
For Cruise Control System
Figure 12.20

18. of Cruise Control System
Statechart, cntd
Decomposition of the
“Alive” State
for the Indicator
of Cruise Control System
Figure 12.21

19. of Cruise Control System
Statechart, cntd
Decomposition of the
“On” State
for the Indicator
of Cruise Control System
Figure 12.22

20. Statechart for Cruise Control System
Figure 12.23

21. Object-oriented Modeling – our favorite in software?
Object Modeling Technique (OMT)
Object model (ERD)
Dynamic model (STD & nested state diagrams)
Functional model (DFD)
Real-time Object-oriented Modeling (ROOM)
Objects = Actors
Actors communicate via messages
ROOMcharts
Combine functional and behavioral models
Generalization of Statecharts
Unified Modeling Language (UML) (SysML)