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
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Relationship to Chapter 16 (Logic diagrams)
In chapter 16, you studied how the logical elements connect to the diagrams -- it's also a kind of model. The diagram shows how the signal goes through the elements and, or, NE. Now we go up to the level: what if we need to describe the structure of the connections in the abstract, without being linked to electricity? The models are the simplified images of objects. In fact, any logical scheme is a model of some process of processing data. Before drawing the diagram, the engineer creates the model, decides which inputs are important and how to connect the elements.
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Examples of models
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Subway diagram
Graphic model
The tops are stations, the ribs are distillation, and they show connections, but they don't show exact distances.
First name
Ma'am
Physics
Inf
Anne
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Boris.
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Performance table
Table Model
The lines are students, the columns are objects, the objects are × properties.
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Urban map
Graphic model
Visual representation of streets, squares, benchmarks.
F
m
a
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Formula F=ma
Mathematical model
A connection of power, mass and acceleration, describing the law of physics.
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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.
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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).
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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.
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Types of information models
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Table
objects x properties
The objects in the rows, the properties in the columns, the most common type, Excel, OBD.
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Graph
vertebrate + ribs
Networks, relationships, paths, social media, maps, addictions.
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Hierarchical
tree
File system, classification, organizational structures.
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Graphic
diagrams, drawings
Maps, diagrams, technical drawings, visual perception.
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Mathematical
formulas
Laws of physics, economic models, formulas.
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Programme
code
Simulation models, simulations, the most flexible type.
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Mini test
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Modelling — 5 out of 50 questions
Level:
Newcomer
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Question 1 out of 5
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