Provide applicable models for the proposed design
A system model
A process model
Context
Model types
Iconic models are visually equivalent, two-dimensional (2D) or three-dimensional (3D) representations such as maps or world globes, 3D physical models, 3D models generated via CAD
Analogical models are functional equivalent representations such as electrical circuit diagrams, computerized simulations of manufacturing processes that behave like the physical process or system even though they may not physically resemble the reality
Symbolic models are high-level abstractions of reality that include the most important aspects of the process or system in symbolic or mathematical form, neglecting all (presumably) irrelevant details
Developing a model
Identify the specific result that the model is expected to provide
Consider both the types of models and the formats that could be used to represent the system or process, together with the reasons for selecting model types and formats
Is the model useful relative to the purpose for which it was developed? If not, modify the model accordingly
Does the model accurately describe the system or process under consideration? If not, identify those characteristics in the process or system that are either not included in the model or that are incorrectly embedded within the model
System Models
Deterministic models perform according to an expected pattern and produce the expected answer
Stochastic models based on various sample sets of empirical data predict the behavior of a system with a certain degree of uncertainty in the results
Process Models
Descriptive models provide the actual procedure that is followed to achieve a desired goal
Prescriptive models provide general guidelines and rules about how a process should be performed to achieve a desired objective
Model Enhancement
Explain the model to another person (not someone on the design team); this may lead to a deeper understanding of the model's relative strengths and weaknesses
Identify boundaries or constraints on the model: Are these realistic and consistent with the problem to be solved?
The model reflects various simplifying assumptions: Are these assumptions reasonable? If not, adjust the model, i.e., discard any unreasonable assumptions and make the model more complex
Develop additional simplifying assumptions and modify the model accordingly
Are all known facts and data properly embedded within the model? If not, why?
Obtain additional information if necessary
Are there similar problems/models available? If so, how does the model differ (if at all) from these other models? Why?
Use another (different) format to model the process or system and compare the two formats: Which is the more accurate representation and why?