Course Flashcards
What is a model? Describe it
- Description of a phenomenon
- Representation of a system
- Simplification
- Set of instructions for generating a behavior
What different types of behavior in a model is there?
- Model behavior - what the model does
* Model structure - What makes it do what it does?
What kind of purpose does a model have?
- Conceptual frame
- Communication tool
- Summarizing a large amount of data
- Provide understandning
- Identify missing knowledge
What is a system?
Collection of entities that act and interact together
What is a simulation?
- Imitation
- Developing an executable model
- Experimenting with a model
- Category of problem solvning
There are several ways of studying a system - what are they?
- Experimenting with the actual system
- Experimenting with model of a system
- -> Physical
- -> Mathematical (analytical, statistical, simulation)
Why would you like to do a model and not try out the actual (physical) system?
- Not accessible (to small, large etc)
- Not existing yet
- Unknown structure
- To expensive
What are the 7 dimensions for simulation models?
- Object behind the model
- Static vs. Dynamic model
- Domain of the simulation time
- Determinism vs. Stochastic
- How entities are represented
- Kind of dependency
- Domain/range of variables
What is the domain of the simulated time?
- Continuous - change in small intervals
* Discrete - changes in particular points
Describe the deterministic approach vs stochastic
- Deterministic - future events can be predicted from simulated history
- Stochastic - probability that a particular event occurs
Describe how different entities can be represented
- Macro models - describes a single object whichs’s properties are put into relation to each other
- Micro models - several objects whichs properties and relation between are analyzed
- Multi-level-models - objects of one model are aggregated into higher-level objectives and tacked as a model on the higher level. Properties and relations on the higher level may be derived from properties and relations on the lower level objectives.
Whats the characteristics of ABM?
- Dynamic
- Usually time-discrete
- Mostly Stochastic
- Non-linear
- Micro models, also multi-level models
- All kind of objectives
Whats the alternative microsimulation approaches?
- Queueing systems (discrete event simulation)
- Object-oriented simulation
- Cellular automata
Describe discrete event simulation
- Simulation state is only updated during event processing
- Very efficient; easy to distribute
- Event queue contains events that will be done –> advanced time, change state according to event type, generate events and put into a queue.
Describe object oriented simulation
- Sequence of events as input, triggering state change
Describe cellular automata
- Every cell is equal
- State transition is local in time and space
- Macro-level phenomena can be observed that cannot be derived from micro-level transition functions
- Parallel update of all cells