Modelling and information models

Содержание и основные понятия

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Alterna · Chapter 17 · page 17.1
Modelling and information models
The models, the construction stages.
Model
The model is always simpler than the original, otherwise it is not necessary.
GEF
PIF
OGE No. 9
EGE No. 1
01
What's a model?
Definition
Model
is a simplified analogy of an object that preserves its important properties.
Why do you need a model?
Study an object without access (a distant star, a distant past).
To understand how the system will behave without risk (samolette, nuclear reactor).
To predict the consequences (wet, economy).
Transfer knowledge (globus, drawing).
Analogies
The globe is a model of the Earth. It does not convey all the details (mounts, buildings), but it retains the key: shape, size, location of the mainland. If it were the size of the earth, it would not be a model.
02
Types of models
Material (local)
Physical expression: a globe, a model at home, an animal's pet, used when it is impossible or dangerous to study the original directly.
Information
Description of the object in the information language: text, table, graph, formula, drawing, program, basis of computer simulation.
Dynamics
Static
- describe the condition (photos, map).
Dynamic
- describe behavior (Video, simulation, motion formula).
03
Modelling phases
Problem Statement
What do we want to know? What are the properties important?
Object analysis
- to highlight the essentials, to throw away the extra ones.
Model building
- Select the form (formula, table, graph, program).
Decision / analysis
- explore the model, get results.
Interpretation
- to move the result to the original, check it out.
Example: Modeling a projectile flight
Problem: Where will the projectile, fired at the angle, go?
Essential: mass, initial speed, angle, g = 9.8 m/s2.
Model: x(t)=v·cos(α)·t, y(t):v·sin(α)(t) - g·t2/2.
Decision: Find t at which y=0 (excluding t=0).
Interpretation: flight range L = v2·sin(2α)/g.
04
Types of information models
📊
Table
objects x properties
The objects in the rows, the properties in the columns, the most common type, Excel, OBD.
🌐
Graph
vertebrate + ribs
Networks, relationships, paths, social media, maps, addictions.
🌳
Hierarchical
tree
File system, classification, organizational structures.
📐
Graphic
diagrams, drawings
Maps, diagrams, technical drawings, visual perception.
🔢
Mathematical
formulas
Laws of physics, economic models, formulas.
💻
Programme
code
Simulation models, simulations, the most flexible type.
05
Mini test
📝
6 modelling questions