Block 1 Flashcards
What’s a system?
A collection of connected, associated or interdependent parts forming a complex whole.
What are the ways that a system’s purpose are decided?
- An innate, naturally occuring purpose
2. A designed purpose
Function vs purpose?
- Function is a system responding to inputted goals
- Teleological Purpose is an internal goal
Autonomy?
in-built mechanism for adapting their actions to achieve their goals
Feedback?
how a system adapts autonomously to achieve a desired goal.
- a measured aspect of the environment
- compared to the desired state
- corrective action is taken
Homeostasis?
A stable state. When the system moves away from a desired value, it acts to return to this.
Characteristics of systems?
- arranged in some way
- interactions between parts
- sub-systems show a degree of autonomy
- behaviour not always as expected or desired
Specific characteristics of man-made systems?
- based on scientific principles
- significant technical and financial risk
- not self-sustaining
Benefits of a system of systems?
- each system addresses a certain function.
- quicker to develop a new product by reusing systems
- any issues can be because of a certain system
- new systems can be integrated over a longer lifecycle as needs change
- systems can be recycled
Complexity?
Where a system has a lot of interactions, leading to a collective behaviour that is hard to work out from them
What’s hierarchy in a system?
Sub systems of stable intermediate forms.
Ingredients of Complexity?
- Collection of many interacting objects (agents)
- Objects’ behaviour may be affected by feedback
- Objects can adapt
- The system is typically “open”
- The system exhibits emergent phenomena which are generally surprising
- There might not be an obvious controller
- There is a mix of order and disorder
Types of hierarchies?
- Function (purpose of sub-systems)
- Control (linked by data interactions)
- Structural (physical arrangement)
- Taxonomic (based on classification)
- Organisational (manager/employee)
- Procurement (where parts are from)
Can a system have more than one hierarchy?
Yes, they can have many. They’re just ways to arrange components.
‘True’ hierarchy?
Each subsystem only communicates with those directly around it, ie. parent and child
Example of hierarchy drawing software?
Microsoft Visio
Why do systems naturally tend away from their desired state?
They tend towards their lowest energy state (entropy / 2nd law of thermo)
Reduction?
The idea that the whole system can be understood by looking at the parts, with each behaviour coming from a component.
Properties that a system can have?
Attributes (physical and others) -Mass -Volume … Functions (actions a thing can perform) -Movement -Display … Behaviours (sequence of functions in response to a stimulus)
Decomposition?
Breaking down a system into parts/subsystems (top down)
Can often be done by different hierarchies
Composition? (synthesis)
Grouping components into subsystems (bottom up)
Typical uses of composition and decomposition?
decomposition (top down) is used more for systems and composition (bottom up) methods are used to supplement this.
Benefits of reductionism?
- simplifies complicated systems
- effective for mechanical systems
Drawbacks of reductionism?
-some behaviours can’t be explained by particular parts
Emergence?
Some properties aren’t designed into a system, but emerge.
Can’t be predicted by looking at the individual components
