Information models. Presentation on the topic "stages of modeling" Presentation on the topic stages of building an information model
Description of the presentation by individual slides:
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Stages of modeling Setting the goal of modeling. Analysis of the modeled object and identification of all its known properties. Analysis of the selected properties from the point of view of the purpose of modeling and determination of which of them should be considered significant. Selecting the model presentation form. Formalization. Analysis of the resulting model for consistency. Analysis of the adequacy of the resulting model to the object and purpose of modeling. Achieving the modeling goal.
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For the same object, for different modeling purposes, different properties will be considered essential. The essential features of a paper model of an airplane are the wings, the body, their relative position, and the ability to fly. For an aircraft designer constructing a computer simulation model to test the reliability of the design under different flight conditions, the model of the aircraft will be a change graphic image and calculated parameters on the display screen when changing the value of the input variable parameters. The essential features here are the pattern and nature of the dependence of the behavior of the aircraft and its individual elements on the external conditions affecting it.
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How correctly and completely the essential features are identified depends on the compliance of the constructed model with the given goal, that is, its adequacy to the purpose of modeling. Adequacy presupposes that the model reproduces with the necessary completeness all the characteristics of the object that are essential for the purpose of modeling. But the adequacy of the model to the modeling object will depend on how we can express these selected essential features, in what form we depict them. The choice of the form of representation of the selected features of the modeling object is the next stage of the modeling process.
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Forms of presentation information model may be: verbal description, table, drawing, diagram, drawing, formula, algorithm, computer program and so on.
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Formalization is the reduction (reduction) of the essential properties and characteristics of an object to the selected form, that is, it is the process of constructing information models using formal languages. The result of the formalization stage will be an information model. But before we talk about the end of the modeling process, the constructed model must be checked for consistency and analyzed to what extent it is adequate to the object and purpose of the modeling. If the constructed model is contradictory, then after identifying all the observed contradictions, they must be eliminated: correct the drawing, change the program, clarify the formula, etc. And again check the refined model for consistency.
Computer science lesson "Main stages of developing and researching models on a computer"
The purpose of the lesson: organize joint educational activities to form and develop students’ research skills; create conditions for mastering modeling technology.
Must know: the main stages of developing and researching models on a computer.
Must be able to: build a model of an object or process according to the goal.
Work plan
Organizational moment
Test work Appendix 2 (test)
Explanation new topic. (presentation + compulsory medical insurance)
Using a computer to study information models of various objects and systems makes it possible to study their changes depending on the value of certain parameters. The process of developing models and studying them on a computer can be divided into several main stages.
At the first stage of researching an object or process, it is usually built descriptive information model . Such a model identifies the object’s parameters that are essential from the point of view of the goals of the study, and neglects the unimportant parameters.
At the second stage, it is created formalized model, that is, the descriptive information model is written using some formal language. In such a model, with the help of formulas, equations, inequalities, etc., formal relationships between the initial and final values of the properties of objects are fixed, and restrictions are also imposed on the permissible values of these properties.
However, it is not always possible to find formulas that clearly express the desired quantities through the initial data. In such cases, approximate mathematical methods are used to obtain results with a given accuracy.
At the third stage, it is necessary to transform the formalized information model into computer model , that is, express it in a language understandable to a computer. There are two fundamentally different ways to build a computer model:
1) constructing an algorithm for solving the problem and coding it in one of the programming languages;
2) building a computer model using one of the applications (spreadsheets, DBMS, etc.).
In the process of creating a computer model, it is useful to develop a convenient graphical interface that will allow you to visualize the formal model, as well as implement an interactive dialogue between a person and a computer at the stage of studying the model.
The fourth stage of information model research is to conduct computer experiment. If a computer model exists in the form of a program in one of the programming languages, it needs to be executed and the results obtained.
If a computer model is examined in an application such as a spreadsheet, you can sort or search the data, create a chart or graph, and so on.
The fifth stage consists of analysis of the results obtained and adjustment of the model under study. If the results obtained from studying the information model differ from the measured parameters of real objects, we can conclude that errors or inaccuracies were made at the previous stages of building the model. For example, when constructing a descriptive quality model essential properties of objects may be incorrectly selected, errors in formulas may be made during the formalization process, and so on. In these cases, it is necessary to adjust the model, and the model can be refined many times until the analysis of the results shows their compliance with the object being studied.
Questions to Consider
1. In what cases can individual stages of constructing and researching a model be omitted? Give examples of creating models during the learning process.
4. Physical education. just a minute
5. Practical work (handouts)
In today's lesson, I suggest you build a computer model of an object with given geometric properties.
Lesson summary
"Laboratory work modeling"
“Simulation in the environment graphic editor”
Target: consolidate students' work with a fragment of a drawing (copying, pasting, rotating, deleting).
Exercise 1. Constructing an equilateral triangle with a given side
This algorithm suggested by Euclid in the 4th century BC. e.
Construct a triangle using the algorithm shown in the figure and prove it.
Fig.1
Task 2. Creating geometric compositions from ready-made mosaic shapes.
The figure shows samples of ornaments and the elementary figures from which it is made. Model this ornament according to the sample.
Fig.2
Fig.3
Tasks for independent work
Task 3. Open the file figure4.jpg, using operations with fragments, create your own pattern and color it as you wish. Don't forget to save the file!
"Lesson 59"
Lesson 59. Construction and study of physical models
Let's consider the process of constructing and studying the model using a specific example of the movement of a body thrown at an angle to the horizon.
Project "Throwing a ball into the court"
During training, tennis players use ball throwing machines. You need to give the machine a program that will force the ball into the court. To do this, you need to set the required speed and angle of throwing the ball.
drawing from textbook p. 155
From the problem statement it follows:
the ball is small compared to the Earth, so it can be considered a material point;
the change in the height of the ball is small, therefore the acceleration of gravity can be considered a constant value (g = 9.8), the movement along the Y axis can be considered uniformly accelerated;
the throwing speed is low, so air resistance can be neglected, and the movement along the X axis can be considered uniform.
To formalize the model, we use formulas known from physics
x=v0*cos a* t,
y=v0*sin a*t - (g*t^2)/2
From the second formula we express the time t, considering y = 0, since the ball will fall to the ground:
v0*sin a*t - (g*t^2)/2=0;
t*(v0*sin a- (g*t)/2)=0;
t=0 or v0*sin a- (g*t)/2=0,
that is, the ball will be on the surface of the Earth twice - at the beginning of the movement and at the end.
We are interested in the second case, from here we get
t= (2*v0*sin a)/g
Substituting the found t into the formula for calculating x we get:
x=(v0*cos a*2*v0*sina)/g=(v0^2*sin2a)/g
Let the platform be located at a distance s and have length l. Then the hit will occur, if ss+l, then the flight
Let's solve the problemin spreadsheets
Let's denote the table columns
Let's add the formulas
As you can see, the result is displayed in text form. You can plot the movement of the ball. Think for yourself how to do this.
Let's solve the problem in the object-oriented programming environment Gambas
screenshot GUI
To enter the initial data: initial speed v0, angle of throwing the ball a, length of the court l and its distance s - we will place 4 ValueBox numeric windows. To display the variable x - another numeric window ValueBox. To display the result: Undershoot, Overshoot, Hit- place the inscription Label on the form. Let's sign each numeric window by displaying Label next to them and changing the Text parameter to Initial speed, Throwing angle, Distance to the platform, Length of the platform respectively. To run the program we need a Button on which we write Start.
Create the Button1_Click event double click by button.
Program code
Public Sub Button1_Click
"We declare the variables g and pi as constants, and the rest as decimal fractions
Const g As Single = 9.81
Const pi As Single = 3.14
Dim v0, a,s,l,x As Single
"Reading the value of user-entered variables from numeric windows
v0=ValueBox1.Value
a=ValueBox2.Value
s=ValueBox3.Value
l=ValueBox4.Value
"We calculate the value of x and display it in the number window
x=v0^2*Math.Sin(2*a*pi/180)/g
ValueBox5.Value=x
"We go through the options for x values and display the result of the throw
Label1.Text="Underage"
Label1.Text="Flight"
Label1.Text="Hit"
Homework
Read clause 5.4. Answer orally Control questions.
Complete the spreadsheet solution with a graph of the ball's movement.
View presentation content
"Prez"
Stage I. Formulation of the problem
1.Description of the task (in plain language, in the most general phrases)
2. The purpose of the modeling (it depends on the chosen purpose which characteristics of the object under study are considered significant and which are discarded).
“what will happen if?..” - determining the consequences of impact on the object and making the right decision.
“how to do it so that...” - creating objects with specified properties.
3. Formalization of the task (formalism - strict order).
Formalization is carried out in the form of searching for answers to questions that clarify the general description of the problem.
Stage II. Model development
1. Information model
The selection of the most significant data when forming an information model and its complexity are determined by the purpose of the modeling.
Information model of the text...
2. Computer model (model implemented using software environment)
Examples: typing, car movement, furniture arrangement...
Stage III. Computer experiment
1. Experimental plan (must clearly reflect the sequence of work with the model)
Testing is the process of checking the correctness of the model.
A test is a set of initial data that allows you to determine the correctness of the model.
2. Conducting research
If you are confident in the correctness of the constructed model, you can proceed to the study.
Stage IV. Analysis of simulation results
This stage is decisive - either you continue the research or finish it.
If the results do not correspond to the goals of the task, it means that mistakes were made at the previous stages.
If such errors are identified, then the model needs to be adjusted, that is, a return to one of the previous stages.
The process is repeated until the experimental results meet the modeling goals.
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Slide captions:
STAGE 1 Construction of a descriptive information model. Descriptive information models are typically built using natural languages and pictures.
Model of the solar system Thus, Copernicus’ heliocentric model of the world was formulated in natural language in the following way: - The Earth revolves around the Sun, and the Moon revolves around the Earth; - all planets revolve around the Sun.
Stage 2 Formalization of the information model The descriptive information model is written using formal language
Model of the solar system
Stage 3 Creating a computer model Creating a model in one of the programming languages Creating computer models using spreadsheets or other applications
Stage 4 Computer experiment The computer model is launched, the initial data is entered, graphs and diagrams are constructed
Stage 5 Analysis of the results and adjustment of the model under study If the results obtained during the study of the model do not correspond to the parameters of real objects, we can conclude that inaccuracies were made at the previous stages.
Questions: In what cases can certain stages of building and researching a model be omitted? Give examples of creating models during the learning process.
On the topic: methodological developments, presentations and notes
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There are 18 presentations in total
CONCEPT OF A MODEL
Each object has a large number of different properties. In progress
construction of the model, the main ones, the most significant for
ongoing property research.
Different sciences study objects and processes from different angles and
are building Various types models.
A model is a new object that reflects essential
features of the object, phenomenon or process being studied.
The same object can have many models, and different objects
can be described by one model.
No model can replace the object itself. But when solving a specific
tasks when we are interested in certain properties of the object being studied,
the model turns out to be useful, and sometimes the only tool
research.
by area of use:
Training models – used in teaching;
Experienced ones are reduced or enlarged copies of the projected
object. Used to study and predict its future
characteristics
Scientific - technical - created to study processes and phenomena
Game - rehearsal of the behavior of an object in various conditions
Imitation - a reflection of reality to one degree or another (this
trial and error method)
by time factor:
Static – models that describe the state of the system in
a certain point in time (a one-time snapshot of information on
this object). Examples of models: classification of animals, structure
molecules, list of planted trees, condition survey report
teeth at school, etc.
Dynamic – models describing processes of change and development
systems (changes of an object over time). Examples: description of movement
bodies, development of organisms, process of chemical reactions. Classification of models by branch of knowledge is a classification by
branches of human activity: Mathematical, biological,
chemical, social, economic, historical, etc.
according to presentation form:
Material are object (physical) models. They always have
real embodiment. Reflect external properties and internal
the structure of the original objects, the essence of the processes and phenomena of the original object. This is an experimental method of understanding the environment
environment. Examples: children's toys, human skeleton, stuffed animal, model
solar system, school textbooks, physical and chemical experiments
Abstract (intangible) - have no real embodiment. Their
information is the basis. this is a theoretical method of knowledge
environment. Based on their implementation, they are:
Mental models are formed in the human imagination as a result of
thoughts, conclusions, sometimes in the form of some image. This is a model
accompanies conscious human activity.
Verbal – mental models expressed in conversational form.
Used to convey thoughts
Information models – purposefully selected information about
object, which reflects the most significant for the researcher
properties of this object. DEVELOPMENT AND RESEARCH STAGES
MODELS ON COMPUTER
Using a Computer to Research Information Patterns
various objects and systems allows you to study their changes in
depending on the value of certain parameters. Development process
models and their study on a computer can be divided into several
main stages.
Descriptive information model. At the first stage of the study
of an object or process, descriptive information is usually built
model. This model highlights the significant, from the point of view of goals,
of the research being carried out, the parameters of the object, and unimportant
neglects parameters.
Formalized model. At the second stage, a formalized
model, i.e. the descriptive information model is written with
using some formal language. In such a model, using
formulas, equations or inequalities, formal relationships are fixed
between the initial and final values of object properties, as well as
restrictions are imposed on the permissible values of these properties. Computer model. At the third stage, it is necessary to formalize
convert the information model into a computer model, i.e.
express it in a computer-readable language. There are various
ways to build computer models, including:
- creation of a computer model in the form of a project in one of the languages
programming;
- building a computer model using spreadsheets
or other applications.
Computer experiment. If a computer model exists in
form of a project in one of the programming languages, it needs to be run in
execution, enter the initial data and get the results.
If a computer model is examined in an application, then it is possible to construct
chart or graph, sort and search data, or
use other specialized data processing methods.
Analysis of the results obtained and adjustment of the model under study.
The fifth stage consists of analyzing the results obtained and making adjustments
the model under study. In case of discrepancy between the results obtained from
research of the information model, measured parameters of real
objects, we can conclude that at the previous stages of construction
the model contained errors or inaccuracies. TYPES OF INFORMATION MODELS
Tabular - objects and their properties are presented in the form of a list, and their
values are placed in rectangular cells. Scroll
objects of the same type are placed in the first column (or row), and the values
their properties are placed in the following columns (or rows)
Hierarchical – objects are distributed among levels. Each element
a high-level element consists of lower-level elements, and a low-level element
level can be part of only one element of a higher
level
Network – used to reflect systems in which connections between
elements have a complex structure According to the degree of formalization, information models can be figurative and symbolic.
Iconic models:
Geometric (drawing, pictogram, drawing, map, plan, volumetric
image)
Structural (table, graph, diagram, diagram)
Verbal (description in natural languages)
Algorithmic (numbered list, step-by-step enumeration, flowchart)
Iconic models:
Mathematical – represented by mathematical formulas that display
parameter connection
Special – presented on special. languages (notes, chemical formulas)
Algorithmic - programs ANALYSIS AND OPTIMIZATION
INFORMATION MODEL
In case of discrepancy between the results obtained during the study
information model, the measured parameters of real objects can be made
conclusion that errors were made at the previous stages of model construction or
inaccuracies.
For example, when building a descriptive qualitative model there may be
essential properties of objects were incorrectly selected during the formalization process
errors may be made in formulas, etc. In these cases, it is necessary
make adjustments to the model, and the model can be refined
repeatedly until the analysis of the results shows their correspondence to what is being studied
object. start working. The time required for machine operations is approximately
the same amount as for manually multiplying given numbers on paper.
The considered example shows the essence of the difficulties that arise when using
Computer: low speed of input data can negate the huge
computing speed. These difficulties led at one time to the fact that computers
were used mainly only to solve individual complex scientific and technical problems.
Economic and other management problems solved in automated control systems differ
much more source data. Therefore, trying to use
A computer in the mode of solving individual problems as applied to management leads to
extremely inefficient use of machines. Truly effective
comprehensive automation of management processes at all levels of national
economy can only exist if economic mechanisms and
organizational forms of management (primarily document flow, as well as
forms of accounting, material interest, etc.) are brought into compliance
with the huge new opportunities that modern electronic
Computer Engineering.