Preface

At present, it is the era of knowledge explosion, people have accumulated a lot of knowledge, with the rapid development of science and technology, explosive knowledge and technology, people are overwhelmed and exhausted. Despite the constant efforts to control the chaos caused by the development of various processes and the division of disciplines, the way knowledge itself is described has always been the key to simplifying the problem:

• The concise and coherent mathematical formula of mathematics is far better than the ninety-nine mantra of the abacus,
• With physical formulas, we can understand the universal laws of the material world simply and clearly.

In addition to physics and mathematics, which are scientific reasoning formulas, and human natural language, we also need a form that can describe various concepts, and organize them clearly, so that we can understand the relationship between various concepts at a glance. Because of the unique human-oriented logical thinking of software logic and the characteristics of work involving various industries, the domain modeling that starts with the UML class diagram of the software industry modeling specification can be used as a method for us to organize knowledge in various fields.

The output of domain modeling is the domain model, which is a form that describes natural language more clearly than natural language, organizes various concepts graphically, helps people understand complex information, and is the basis for effective analysis before specific work.

This article is the knowledge model of physics in the second semester of the second semester of junior high school that I helped my daughter CC organize with domain modeling methods：

• Let the reader know that domain modeling can help collate a variety of expertise and be useful for everyone, from students and engineers to scientists.
• Other parents and teachers who are concerned about secondary school students are also welcome as references.

Body

First, let's look at what domain modeling is. It is important to learn a method and understand the basic concepts, and there are 2 core concepts here:

• Field
• Object

Now that we understand the basic concepts, let's take a look at what domain modeling is:

In the software industry, domain modeling is a very effective method because of the need to understand business domain knowledge, and it is basically a consensus that domain modeling is a necessary skill for product managers, requirements analysts, architects, and software development engineers. In other fields, such as systems engineering, hardware, various professional fields (such as optoelectronics, mechanics, electronics, communications) or more broadly, secondary schools and universities, domain modeling is basically a state that most people do not understand at all, and even if they occasionally involve software projects, they will think that it is a seemingly useful but uncertain method and turn away. Here, with my 20 years of experience in dozens of projects involving more than 10 fields, domain modeling is really a very important basic skill, as long as you want to sort out the huge amount of knowledge, whether it is related to software or not, you can use it, it can help you clarify the knowledge context, concisely grasp the essence of the problem.

Domain modeling is mainly to organize various knowledge and concepts in the problem domain, which is much like people using natural language to describe various things in the real world with various words, and these words themselves are the classification of things, such as the noun "table, plane, elephant". However, because of the universality of writing, natural language can only be described in the form of line by line, word by word, and then the person who reads it, according to his own knowledge map, organizes various concepts into various conceptual relationships in his mind, but the concepts in each person's mind do not have a clear presentation form, resulting in confusion in various conceptual relationships. The domain model is to use UML class diagrams to model various concepts in the domain, so that the logical relationships in the mind have a clear form, which is much better.

Let's take a look at the elements, characteristics, and relationships of a class diagram for domain modeling:

Challenges of domain modeling

There are 3 key aspects of domain modeling:

1.Have a deep understanding of object-oriented analysis methods and be able to identify objects, classes, and relationships from requirements descriptions.

2.Accurately understand the modeling mechanism of classes, attributes, behaviors, and relationships in UML class diagrams.

3. Be familiar with the problem area and be able to grasp the core knowledge of the problem area.

These three elements are undoubtedly mutually reinforcing, and must be organically combined to achieve complete domain modeling. Most of what you see in books is the domain modeling of e-commerce and information management systems, which focuses on data and has an innate close correlation with computer data processing, so domain modeling is not complicated and easy to reach a consensus. For those logical domains with complex logic and inconspicuous data relationships, domain modeling has a higher challenge.

Lower grade 8, domain modeling of physics subject knowledge

In order to illustrate that domain modeling is a basic ability, here is a summary of domain modeling in physics under the eighth grade compiled for my daughter CC：

• I want everyone to understand how important modeling is for knowledge understanding.
• Parents of other secondary school students are also welcome to use as references.
• There will be domain modeling in other disciplines in the future: )

General framework of forces:

First of all, it should be made clear that the principles of mechanical motion are taught in the second year of junior high school physics, which involves some basic basic principles:

• The object has inertia：the object remains stationary or moves in a straight line at a uniform speed without the action of external force; (This is Newton's first law)
• To change the inertia of an object, a force needs to be applied：the acceleration of an object is proportional to the force and inversely proportional to the mass of the object; The direction of acceleration is the same as the direction of the applied force, a=F/m a-acceleration, f-force, m-mass. (This is Newton's second law)
• Force is the interaction of 2 objects：the acting and reacting forces between the two interacting objects are always equal in magnitude and opposite in direction, acting on the same straight line. (This is Newton's third law)

There are also some basic concepts:

• Force: The action of one object on another object, the result of which can produce acceleration or deformation, the unit of force is N (Newton).
• Work: An object A exerts a force F on another object B, causing this object to move some distance in the direction of the force, that is, say Object A does work on object B. It can also be said that the force F does work on object B. The product of the force F acting on the object and the displacement s s of the object in the direction of the force is the quantity of work. W =F s。 The unit of work - joule (ear) J, 1 joule = 1 Newton · m , 1J = 1N · m
• Energy (energy): If an object can do work externally, it needs to have energy, referred to as energy.

The basic properties of the force are also broken down:

• The three elements of force: the point of application, the direction, and the magnitude
• 2. Force balance: After the object is subjected to the action of 2 forces, it still maintains the original state of inertia (stationary or uniform linear motion state)

These are modeled as follows:

Diagrams are helpful for analysis, but the order of reading is more arbitrary, and words are conducive to arranging the order of reading, so the meaning expressed in the above diagram is described in words as follows, in natural language, the most important thing is nouns and verbs, which express objects and actions respectively. In order to distinguish between nouns and verbs, in the following textual descriptions, the nouns are in Chinese and the verbs are in English.

• objects have motion,
• Motion has velocity, and velocity has inertia
• The change in the velocity of an object is called acceleration (called).
• The force of the subject on the object can be generated
• The process by which the body exerts force can do work
• The main body that can do work has energy
• Force has three elements: the point of application, the direction, and the magnitude
• Multiple forces can be synthesis,
• If two forces are equal in magnitude and opposite in direction, the name (called) is the equilibrium of the two forces

For each force, there is a model framework, which is described in class diagrams for analysis, and table descriptions are easy to write and read, so the key content in each diagram is listed "Force Analysis Table":

The following is an analysis of each force according to the model framework of the force: elastic force, gravity, friction force, pressure, buoyancy

Elastic Modeling:

Force Analysis Table:

Gravity Modeling:

Force Analysis Table:

Friction Modeling:

Force Analysis Table:

Pressure frame mold construction:

Force Analysis Table:

Buoyancy Modeling:

Force Analysis Table:

Modeling of work, power, and mechanical energy:

Representation of knowledge after domain modeling:

These are some of the knowledge that takes force as the research perspective in the laws of mechanical motion. These models should be very useful for understanding knowledge, but for students, it is undoubtedly still complicated, and the description of book knowledge needs to be applied to students after clear logical relationships.

Postscript

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