Materials that make up a computer
A computer consists of four main components:
System unit.
Keyboard.
Monitor.
The system unit is usually assembled from plastic, less often from metals. The boards located inside the block are attached to metal guides.
The system unit contains such important parts as the motherboard, power supply, electronic circuits (processor, device controllers, etc.), disk drives (storage devices). All these elements are assembled from different materials.
The power supply ensures the operation of all elements that make up the computer. The power supply to all elements of the computer is carried out through wires woven into bundles, the basis of which is a metal wire capable of conducting electric current, usually made of copper or aluminum.
On the motherboard, as well as on other boards that are located in other elements of the computer, there are many parts soldered onto current-carrying copper tracks deposited on PCB. These are microcircuits, transistors, diodes, resistances, capacitors. Microcircuits, transistors and diodes are made of silicon or germanium. Coal resistances. Mica capacitors. Also on the motherboard there are connectors into which the processor, device controllers, video card and other elements included in the computer are connected. The metal contacts of the connectors are gold-plated to improve current conductivity in the contact area.
The central processing unit is the “brain” of the computer. It defines the basic characteristics of the computer. A microprocessor is a large integrated circuit formed on a silicon chip. Silicon has semiconducting properties; its conductivity can be controlled by introducing impurities. The microprocessor contains millions of transistors connected to each other by thin conductors made of aluminum or copper.
Manufacturing a microprocessor is a complex technical process. It includes many stages. Let's note one thing: microprocessors are formed on the surface of thin silicon wafers, which are cut from long cylindrical silicon crystals grown from molten silicon sand. Next, thin layers of various materials are applied to these plates. On them, a “pattern” of the future microcircuit is formed layer by layer using a photolithographic method.
Since individual elements of electronic circuits heat up during operation, excess heat must be removed from them. Radiators that are attached to these parts serve this purpose.
Radiators are metal plates with a ribbed surface, which improves heat exchange between the part and the environment. Radiators are usually made of aluminum or copper.
The computer is equipped with a floppy disk drive, a CD or DVD drive for CD or DVD disks, and a hard drive (hard drive). They serve to store information.
A hard drive is a box made of metal and plastic that protects the board with parts inside it that control the operation of the hard drive and the hard drive itself on which the information is recorded. The hard drive is made of plastic, ceramic, aluminum or glass round plates on which a special magnetic coating is applied. During playback, the disc rotates and information stored on the disc is removed from it using a laser beam.
Flexible magnetic disks consist of a plastic housing that encloses the disk itself, made of plastic or ceramic.
Currently, floppy magnetic disks are replacing compact discs (CDs) or DVDs. They are made from the same materials as the hard drive.
The keyboard is a plastic case, on the front side of which there are keys with images of letters and numbers. Inside it there is a board that converts the signal and outputs it to the system unit.
The mouse also has a plastic body, on the front side of which there are two buttons. There are several mouse designs. The most common optical-mechanical mouse. Its main element is a heavy rubber-coated ball. Two rollers with vertical and horizontal axes of rotation are pressed against the ball inside the housing. When the mouse moves, the rollers rotate disks with slots, on both sides of which there are LED-photodiode pairs. There are also optical mice. In them, the light emitted by the LED is reflected from the mat and hits the photodetector. This mouse has no mechanical parts and lasts much longer than an optical-mechanical mouse.
The main device for displaying information from a computer is the monitor. The main function of a monitor is to provide visual information.
There are three types of monitors:
Cathode ray tube (CRT).
Liquid crystal (LCD)
Plasma (TFT)
CRT monitors or picture tubes consist of a hermetic glass bulb, an electron gun and a deflection system. The inner surface of the screen is coated with a phosphor that emits light when bombarded by electrons fired from an electron gun. Chemical compounds based on rare earth metals - europium, yttrium, erbium, etc. - are used as phosphors. In color CRT monitors, the phosphor consists of discrete elements that reproduce primary colors - red, green, blue, when electrons hit them. To reproduce these colors, three electron guns are used, one for each color.
LCD monitors consist of a substance that is in a liquid state, but at the same time has some properties inherent in crystalline solids. Liquid crystals have anisotropy of optical properties associated with order in the orientation of molecules. Liquid crystalline substances were discovered back in 1888. However, they were first used to create calculators and digital watches in the second half of the 20th century.
The operation of LCD panels is based on the phenomenon of polarization of light flux. It is known that some liquid substances, like crystals, are capable of transmitting only that component of light whose electromagnetic induction vector lies in a plane parallel to the optical plane of the polaroid. For the remainder of the light output, the Polaroid will be opaque. Due to their similarity to crystalline substances in electro-optical properties, these substances were called liquid crystals. The LCD monitor screen has several layers, the key role being played by two glass panels and a thin layer of liquid crystals between them.
Plasma (TFT) monitors consist of thin-film transistors and have several advantages over LCD monitors. They have reduced energy consumption and heat dissipation. The TFT-based panel is designed in this way: three color filters (red, green, blue) are integrated one after the other in the glass plate. Each pixel is a combination of three cells or subpixel elements. The principle of operation of a plasma panel is a controlled cold discharge of rarefied gas (xenon or neon) in an ionized state (cold plasma). The working element (pixel) that forms a point in the image is a group of three subpixels responsible for the three primary colors, respectively. It should be noted that plasma monitors are resistant to electromagnetic fields, which allows them to be used in industrial environments.
Healthy lifestyle - A healthy lifestyle and its components help a person maintain optimal health. It actively influences our entire lives.
What components of a healthy lifestyle are important for a person’s long life? Today we will try to understand this issue.
Almost everyone has heard the words about a healthy lifestyle, that a healthy lifestyle will help you live a long time. For many years it gives you the opportunity to look young and well-groomed.
But why do people neglect this and do not strive to implement the basic elements of a healthy lifestyle? Maybe because they don't know what it is.
Components of a healthy lifestyle
A healthy lifestyle is a lifestyle that is aimed at preventing diseases, strengthening the human body with the help of simple components: proper nutrition, exercise, giving up bad habits and a calm life that does not cause nervous shock.
A deterioration in his health forces a person to think about a healthy lifestyle. This is influenced by: the environment, stressful work, crime news, bad habits, etc.
But you can try to solve these problems if:
develop the habit of leading a healthy lifestyle from early childhood;
know that the environment does not always benefit the human body;
remember that cigarettes, alcohol and drugs cause irreparable damage to health;
proper nutrition improves health, reduces the risk of cardiovascular diseases, improves the condition of skin, hair and nails, and also promotes better digestion;
playing sports makes you feel energetic throughout your life;
adjust your emotional, psychological and spiritual well-being.
Let's look at how elements of a healthy lifestyle affect a person and what needs to be done to improve life. To understand why you should lead a healthy lifestyle, remember what a person looks like who doesn’t.
Life without a healthy lifestyle
A person who leads a healthy lifestyle stands out in any team. But why can't everyone constantly focus on improving their well-being? Usually, it depends on the people who surround the person. For example, if the family does not like to play sports, then the child will refuse morning exercises. If all your friends eat at a fast food cafe, then not every person will be able to resist this. This situation arose in the United States, when all residents of the country began to be called a “fast food nation.”
What happens if pregnant women stop taking care of their health? This situation can lead to the birth of an entire generation of unhealthy children. In addition, it is worth remembering about genetic inheritance. Many years of research by scientists have proven that bad habits on the paternal side are passed on not only to children, but to grandchildren and great-grandchildren. This means that families will grow up with generations of people with bad habits and poor health.
For many young people, this is supplemented by sedentary office work, which by a certain age makes itself felt by various diseases, obesity, and musculoskeletal disorders. Stressful situations in transport, at home and at work lead to disruption of the nervous and cardiovascular systems.
Ecology and healthy lifestyle
Anyone can fight such factors on their own. The main thing in your life is to find a place to lead a healthy lifestyle. But there are moments that are difficult to influence, and they have a negative impact on the human body. These factors include the ecological state of the environment. Polluted water bodies, exhaust gases, increased background radiation and much more, which reduces human life by tens of years.
Alcohol causes no less harm than smoking. But the worst thing is that its excessive use leads a person to degradation. Alcohol causes great harm to the heart. The heart muscles become flabby and contractions become sluggish. When drinking alcohol, metabolism worsens, the walls of blood vessels become thin, blood clotting increases, resulting in a heart attack and the development of atherosclerosis.
Under quality service, service product is understood as a complex of their useful properties, regulatory and technological characteristics of service, thanks to which public and individual needs are satisfied at the level of established requirements, comparable to both national traditions and world standards. The useful properties of a service are those objective characteristics that appear during its consumption and that meet the demands and needs of consumers, as well as state and regulatory legal criteria.
Thus, the understanding of quality includes an economic component + is based on the regulatory framework. Quality has different degrees of expression (high, medium, low) depending on the cost that the consumer agrees to. Quality issue as an economic category arose along with the development of social production, with the beginning of the generation of services as a response to the everyday needs of people.
Today, all manufacturers in the world are concerned with the problem of improving the quality of production, including the production of services. The positive result of improving the quality of service products is important for all participants and parties.
The main thing is that the quality of the service increases its competitiveness in the market.
However, quality indicators, as well as problems associated with the production of quality products, are specific to each industry, including the tourism sector.
Currently, the concept of quality as a category is normalized and defined by standards.
Self-control and departmental control, state control.
1. standardization
2. certification
3. licensing
According to the definition International Organization for Standardization (ISO)) quality- is a set of properties and characteristics of a product that give it the ability to satisfy conditional or anticipated needs. There is also a definition of product quality given in GOST 15467-79, according to which “ product quality- a set of properties of a product that determine its suitability to satisfy certain needs in accordance with its purpose.”
Object of standardization- products, services and processes that are repeatedly reproduced and/or used. It is the standard that essentially defines the conditions and methods that ensure quality indicators.
Management of standardization activities at the state level in Russia is carried out by Gosstandart of Russia.
In tourism, it is difficult to examine the quality of the product without first finding out the content of the tourist service. Usually, the act of purchase and sale here does not correspond in time and place to the production of paid services, which means that the sale of some of them is carried out by some tourist enterprises, and the production and provision of them by others. Schematically speaking, the process under consideration is triune, including services for the purchase and sale of a range of services, travel and stay in tourist destinations. During an organized tourist trip, the lack of one of the above-mentioned components violates the unity of the process, and then it is impossible to talk about tourist services as a complex. Without buying and selling, travel is impossible; without traveling, staying in points of interest to tourists is impossible. The quality of tourist services depends on the work of teams involved in the three stages of the tourism process. Thus, tourism services simultaneously cover activities in the production, supply and sale of services and goods.
The soils of the Non-Chernozem Zone of the RSFSR are poor soils. The application of organic fertilizers can dramatically increase their fertility and enhance the microbiological activity of the soil. And every year there are more and more of them. Therefore, the gardener must find reserves for creating composts himself. Translated from Latin, compost means “composite”. It includes various organic residues and mixtures with peat, soil, feces, phosphate rock and other components. Compost is as effective as manure.
During the year, the garden plot is 600 sq. m can be obtained from plant residues, last year's leaves, household waste, toilet waste, 120 kg of finished compost. This amount is enough to fertilize 50% of the garden area.
The presence of compost heaps in the garden indicates the high agronomic and sanitary culture of the gardener, his diligence, because without any special material costs he provides his garden, vegetable garden and flower garden with rich organic fertilizer.
Types of composts
Several types of composts are known: peat-manure, peat-fecal, peat-ash, peat-phosphorite, peat-garbage, peat-garbage-garbage, garden prefabricated, peat-turf, etc. Depending on the type of compost, it becomes ready for use within 6-12 months, except for peat fecal, which ripens by the end of the second year.
Ingredients of all composts
The main component of all composts is aerated peat. If it is not there, use the soil of the upper horizon. Ready compost is used at the rate of 4 kg per 1 sq. m 20 cm soil layer. Peat fecal compost is used for all fruit, berry and ornamental crops, except strawberries, potatoes, and root crops. Other types of composts are used for all crops.
Making compost
For the annual preparation of any type of compost in a 600 sq. m. garden. m should have 1 t of peat. The largest amount of plant residues, last year's leaves, and vegetable waste is observed in May, June and September. All this waste is put into compost.
For the compost site, choose the most shaded place in the garden, away from the garden house - both yours and your neighbor's. It is best to place the compost heap close to the utility unit.
It is rational to have two compost heaps in the garden: one from the current year, the other from the past, with compost that is already ripe and suitable for use.
A pit 1.5 - 1.25 wide and 0.5 m deep is dug under the compost heap. Its length depends on the amount of plant residues. The height of the heap is increased to 1.5 m. The soil removed from the pit can be used instead of peat. If the area is wet, then a pit is not made.
An asbestos-cement pipe is laid in the middle of the compost heap, the ends of which are open to air, which helps accelerate the maturation of the compost due to the activity of aerobic microorganisms. At the bottom of the compost heap, pour dry, aerated peat in a layer of 10-15 cm or put 15-20 cm of sod.
Compost consisting of carbon-containing layers (last year's leaves, pine or spruce needles, sawdust, wood chips, shavings, bark, paper, hay, straw, rotten wood) and nitrogen-containing substances (green weeds with above-ground and root systems, fresh grass, turf, waste from vegetables, potato and tomato tops, garbage, fermented sludge, manure, litter, urine, slop, soapy water, etc.), has the greatest nutritional value.
Compost is laid in layers. The first layer of 40 cm is made of carbon-containing substances, then a layer of 10 cm of nitrogen-containing substances, etc. If there is little waste of this type, then any nitrogen mineral fertilizer is applied at the rate of 2 - 3 kg of nitrogen fertilizers per 100 kg of leaves. To neutralize excess acidity of compost, 2-3 kg of lime, or 4-5 wood ash, or 5-6 kg peat ash, or 2-3 kg of stove soot are added per 100 kg of mass (about 7-8 buckets). To increase the nutritional value of compost per 100 kg of mass, add 2 - 3 kg of superphosphate or 2 - 4 kg of phosphate rock.
The compost is mixed monthly using a pitchfork. If the compost contains dry components, they are moistened with water, urine, or slurry.
To preserve heat in the compost and reduce the volatilization of ammonia, the pile is covered with peat, earth, turf or old film.
Gardeners who are just starting to develop a plot should remember that over the course of several years they will need a lot of fertile soil for vegetables, fruits, berries and ornamental crops. Such soil is the surface layer, or, as it is called, turf. The turf is cut from the construction sites of the future garden house, utility block and from the areas where paths are laid.
B. Popov
Iron - ductile metal of silver-white color with low hardness (HB 80). Melting point - 1539°C, density 7.83 g/cm 3 . Has polymorphic modifications. With carbon, iron forms a chemical compound and solid solutions.
Ferrite is called a solid solution of carbon in a-iron. The carbon content in ferrite is very low - a maximum of 0.02% at a temperature of 727°C. Due to such a low carbon content, the properties of ferrite coincide with the properties of iron (low hardness and high ductility). A solid solution of carbon in the high-temperature modification Feα (i.e., Feδ) is often called δ-ferrite or high-temperature ferrite.
Rice. 8.1. Ferrite
Austenite is a solid solution of carbon in γ-iron. The maximum carbon content in austenite is 2.14% (at a temperature of 1147°C). Has a hardness of HB 220. Fig. 8.2. Austenite
Rice. 8.2. Austenite
Cementite is a chemical compound of iron with carbon (iron carbide) Fe 3 C. It contains 6.67% carbon (by weight). It has a complex rhombic crystal lattice. It is characterized by very high hardness (HB 800), extremely low ductility and brittleness.
Rice. 8.3. Lamellar perlite
Rice. 8.4. Granular perlite
Perlite is a mechanical mixture of ferrite and cementite. Contains 0.8% carbon, formed from austenite at a temperature of 727°C. It has a lamellar structure, i.e. its grains consist of alternating plates of ferrite and cementite. Pearlite is a eutectoid.
Eutectoid - this is a mechanical mixture of two phases, formed from a solid solution (and not from a liquid alloy, like a eutectic).
Ledeburite is a eutectic mixture of austenite and cementite. Contains 4.3% carbon, formed from a liquid alloy at a temperature of 1147°C. At a temperature of 727°C, the austenite included in ledeburite transforms into pearlite, and below this temperature ledeburite is a mechanical mixture of pearlite and cementite.
The cementite phase has five structural forms: primary cementite, formed from a liquid alloy; secondary cementite, formed from austenite; tertiary cementite, formed from ferrite; ledeburite cementite; cementite perlite.
Fe-Fe 3 C diagram. In Fig. Figure 8.5 shows a diagram of the state of iron alloys with cementite. The horizontal concentration axis shows carbon content from 0 to 6.67%. The left vertical axis corresponds to 100% iron content. It shows the melting point of iron and the temperature of its polymorphic transformations. The right vertical axis (6.67% carbon) corresponds to 100% cementite content. The letter designation of the points on the diagram is adopted in accordance with the international standard and is not subject to change.
| Dot | Heating temperature, °C | Limit carbon concentration, % | Characteristics of a point |
| A | Melting point of iron | ||
| IN | 0,51 | Composition of the liquid phase during a peritectic reaction | |
| WITH | 4,3 | Composition of eutectic - ledeburite | |
| D | 6,67 | Melting point of cementite | |
| E | 2,14 | Limiting solubility of carbon in γ-iron | |
| J | 0,16 | Composition of austenite during peritectic reaction | |
| H | 0,1 | Ferrite composition during peritectic reaction | |
| N | Conversion of δ - iron to γ - iron | ||
| G | Conversion of α - iron to γ - iron | ||
| S | 0,8 | Eutectoid composition - pearlite | |
| P | 0,025 | Limiting solubility of carbon in α - iron | |
| Q | 0,01 | Minimum solubility of carbon in α - iron |
Rice. 8.5. Iron-carbon phase diagram.
Iron-carbon alloys, depending on the carbon content, are divided into technical iron (up to 0.02% C), steel (from 0.02 to 2.14% C) and cast iron (from 2.14 to 6.67% C). Steel containing up to 0.8% C is called hypoeutectoid, 0.8% C is eutectoid, and over 0.8% C is hypereutectoid. Cast iron containing from 2.14 to 4.3% C is called hypoeutectic, exactly 4.3% is eutectic and from 4.3 to 6.67% C is hypereutectic.
The structure of industrial iron is ferrite grains or ferrite with a small amount of tertiary cementite. An essential structural component of steel is pearlite. The structure of hypoeutectoid steel consists of evenly distributed grains of ferrite and pearlite. Eutectoid steel consists only of pearlite. The structure of hypereutectoid steel consists of pearlite grains surrounded by a continuous or discontinuous network of secondary cementite. Cast iron is characterized by the presence of ledeburite in its structure. The structure of hypoeutectic cast iron consists of pearlite, secondary cementite and ledeburite, eutectic - of ledeburite and hypereutectic - of ledeburite and primary cementite.
The significance of the iron-cementite diagram is that it allows one to explain the dependence of the structure and, accordingly, the properties of steels and cast irons on the carbon content and to determine heat treatment modes to change the properties of steels.
Questions for self-control.
1. Name the components, phases and structural components of the diagram.
2. What are ferrite, austenite, pearlite, ledeburite and cementite?
3.Tell the properties of the microstructure of the phases and structural components of the diagram.
4. Write the transformation reactions on the diagram.
5. What are the liquidus and solidus lines of the diagram?
6. Describe the process of crystallization of alloys with different carbon contents (<0,025; 0,16;0,51; 0,8; 1,5; 2,5 и 4,3%).
Lesson 9. Practical work No. 1 “Study of the phase diagram of “Iron-cementite”.
Goal of the work:
Study of phases and structural components, as well as phase transformations of the diagram.
Material equipment:
To carry out the work, you must have: a poster of the state diagram of Fe-Fe 3 C, an album of phase microstructures and structural components of the diagram.
