03 - SysML Flashcards
1
Q
What are some key advantages of Model-Based Systems Engineering (MBES)?
A
- Shared understanding of system requirements and design
- Assists in managing complex system development
- Improved design quality
- Supports early and ongoing verification & validation to reduce risk
- Provides value through the life cycle (e.g., training)
- Enhances knowledge capture
- Primary artifact is system model,
- Other artifacts are secondary
2
Q
Explain “Shared understanding of system requirements and design” in MBES.
A
- Validation of requirements
- Common basis for analysis and design
- Facilitates identification of risks
3
Q
Explain “Assists in managing complex system development” in MBES.
A
- Separation of concerns via multiple views of an integrated model
- Supports traceability through hierarchical system models
- Facilitates impact analysis of requirements and design changes
- Supports incremental development & evolutionary acquisition
4
Q
How does MBES improve design quality?
A
- Reduces errors and ambiguity
- Provides a more complete representation.
5
Q
Explain the view on artifacts in MBES.
A
- The primary artifact is the system model, an integrated, coherent, consistent view created using dedicated systems modeling tools.
- Other artifacts are secondary, automatically generated from the system model and using the same modeling tool.
- The system model serves as a central repository for design decisions.
- Each decision is captured as a model element (or a relationship) in a single place within the system model.
6
Q
Describe modelling languages in MBSE.
A
Grammar - semiformal language that defines
- Elements you are allowed to put into your model
- Allowable relationships
- Set of notation you can use to display the elements and relationships on diagrams
7
Q
Describe modeling methods in MBSE.
A
- Set of design tasks that a modelling team performs to create a system model
- Design tasks that ensure that everyone on the team is building the system model consistently
8
Q
Design modelling tools in MBSE.
A
- Designed to comply with the rules of one or more modelling languages
- Enabling users to construct well-formed models in those languages
- Different from diagramming tools (Visio) -> creation of diagrams with no model underlying those diagrams
- Modification in a modelling tool changes the underlying model’s element, updating all the other diagrams with that element.
9
Q
What are two modelling needs?
A
- System-of-Systems
- Multiple Levels
10
Q
Briefly describe SysML.
A
- Graphical modelling language
- Subset of UML 2 with extensions
- Model and data interchange via XML Metadata Interchange
- Semantics = meaning, Notation = representation of meaning
- Methodology and tool independent
11
Q
Name the three main diagram types that compose a SysML diagram.
A
- Behavior Diagram
- Requirement Diagram (New from UML 2)
- Structure Diagram
12
Q
What are the subtypes of diagrams inside a Behavior Diagram?
A
- Activity Diagram (Modified from UML 2)
- Sequence Diagram
- State Machine Diagram
- Use Case Diagram
13
Q
What are the subtypes of diagrams inside a Structure Diagram?
A
- Block Definition Diagram (Modified from UML 2)
- Internal Block Diagram (Modified from UML 2) -
–one type —>Parametric Diagram (New from UML 2) - Package Diagram
14
Q
Explain a Package Diagram.
A
- Expresses information about the structure of a system model (a package containment hierarchy).
- Conveys the logical groupings of model elements.
- Organizes the model
- By system hierarchy
- By diagram type
- Using viewpoints to augment model organization
15
Q
Explain a Block Definition Diagram.
A
- Primary type of diagram to communicate structural information about a system
- Expresses types of structures that can exist internally and externally
- Describes the relationship among blocks (composition, association, specialisation)
- Generalizes relationships between elements, allowing hierarchy and design abstractions
16
Q
Explain an Internal Block Diagram.
A
- Contrary to a Block Definition Diagram (BDD) where a block is a black-box, blocks are represented as white-box implementation
- Complements the information in BDD
- Shows connections between blocks
- Describes services that interact with\ one another
- Defines types of matter, energy, and data that can flow among them across their connections.
17
Q
Explain a Parametric Diagram.
A
Type of Internal Block Diagram.
- Expresses a set of constraints
- Generally, equations and inequalities
- Determine the values that are valid in a system that is operating nominally
- Expresses equations between value properties, providing support for engineering analysis and identification of critical performance properties
- Represents the usage of the constraints in an analysis context
- Focuses on the flow of matter, energy, and data
- Specifies transformation of inputs to outputs
- Can create call behavior actions in an activity to model behavioral decomposition
- Allows model asynchronous communication among structures within a distributed system.
- Wait time actions can be used for periodic behaviors
- Activity partitions allow for activity’s actions responsibility allocation to specific structures within a system
18
Q
Explain an Activity Diagram.
A
Explains how an input is processed, serving as a problem description. It can show parallel sets of activities.
19
Q
Explain a State Machine Diagram.
A
- Expresses information about a system’s state-based behavior response to event occurrences
- Usually depicts the life cycle of a block
- Supports event-based behavior
- Transition with trigger, guard, action
- State with entry, exit, and do-activity
- Can include nested sequential or concurrent states
- Can send/receive signals to communicate between blocks during state transitions
- Has three event types
- Change event
- Time event
- Signal event
20
Q
Explain a Use Case Diagram.
A
- Black-box view of the services that a system provides
- Provides means for describing basic functionality in terms of usages/goals of the system by the actors
- Serves as system context diagrams
- Displays the generalizations among actors and use cases
- Displays the included relationships and extended relationships among use cases
21
Q
Explain a Sequence Diagram
A
- Present information about a system’s behavior over time, focusing on the communications occurring among specific system parts.
- Often used to model a test case. A single execution path through a use case with specified input values and expected output values.
- Ability to completely and unambiguously specify a system behavior
- Conveys all three essential pieces of information
- The order of the behaviors that occur
- Which structure performs each behavior
- Which structure invokes each behavior
- Server as inputs into the development stage of the system life cycle
- Provides representations of message-based behavior, to represent the flow of control and describe the interaction between parts
- Provides mechanisms for representing complex scenarios, allowing reference sequences, control logic and lifeline decomposition
22
Q
Explain a Requirement Diagram.
A
- A requirement stereotype represents a text-based requirement
- Includes an id and text properties
- Can add user-defined properties such as a verification method
- Can add user-defined requirements categories
- Requirements hierarchy describes requirements contained in a specification
