1 main forms of human activity energy costs. Control work Energy costs in various forms of activity. Classification of working conditions. Energy expenditure at rest and during exercise
Classification of the main forms of human activity
Lecture 2 Fundamentals of labor physiology
The subjects heard the old sentences better, as they implicitly resembled them, although they were not aware of this.
Precedence effect
Parry Jacobi
Listen to a series of sentences - no explicit playback
Evaluation of loud noises
Against the background of noise, new - old proposals
When new - the noise seemed louder
"How to Become Famous Overnight with No Effort"
Diego Maradona
Sebastian Weisdorf
Richard Gere
John Kennedy
Marilyn Monroe
Roger Bannister
Day 2 Who are these people?
Marilyn Monroe - Actress
Richard Gere - actor
Indira Gandhi - politician
Francis Coppola - film director
Sebastian Weisdorf - footballer/politician/director/scientist
Dmitry Nikolaevich Uznadze (1886/87 - 1950)
Unconscious attitude - the readiness of the subject to perform a certain action or to react in a certain direction, which is the result of his past experience.
The nature and organization of labor activity have a significant impact on the change in the functional state of the human body. The various forms of labor activity are divided into physical and mental labor.
Physical work characterized by a load on the musculoskeletal system and functional systems of the human body (cardiovascular, neuromuscular, respiratory, etc.), which ensure its activity. Physical labor, while developing the muscular system and stimulating metabolic processes, at the same time has a number of negative consequences. First of all, this is the social inefficiency of physical labor, associated with its low productivity, the need for high physical exertion and the need for long - up to 50% of working time - rest.
Brainwork combines works related to the reception and processing of information that requires a predominantly * sensory apparatus, attention, memory, as well as the activation of thought processes, the emotional sphere. This type of labor is characterized by hypokinesia, i.e. a significant decrease in human motor activity, leading to a deterioration in the reactivity of the body and an increase in emotional stress. Hypokinesia is one of the conditions for the formation of cardiovascular pathology in mental workers. Prolonged mental stress has a depressing effect on mental activity: the functions of attention (volume, concentration, switching), memory deteriorate
(short-term and long-term), perception (a large number of errors appear).
In modern human labor activity, the volume of purely physical labor is insignificant. In accordance with the existing physiological classification of labor activity, there are:
forms of labor that require significant muscle activity. This type of labor activity takes place in the absence of mechanized means for performing work and is characterized by increased energy costs;
mechanized forms of labor. A feature of mechanized forms of labor is the change in the nature of muscle loads and the complication of the action program. Under the conditions of mechanized production, there is a decrease in the volume of muscle activity, small muscles of the limbs are involved in the work, which should provide greater speed and accuracy of movements necessary to control the mechanisms. The monotony of simple and mostly local actions, the monotony and the small amount of information perceived in the process of labor lead to the monotony of labor and the rapid onset of fatigue;
forms of labor associated with semi-automatic and automatic production. With such production, a person is excluded from the process of direct processing of the object of labor, which is entirely performed by the mechanism. The task of a person is limited to performing simple operations for servicing the machine: submit material for processing, set the mechanism in motion, remove the machined part. Characteristic features of this type of work: monotony, increased pace and rhythm of work, loss of creativity;
Group forms of labor - assembly line. This form of labor is determined by the division of the labor process into operations, a given rhythm, a strict sequence of operations, automatic supply of parts to each workplace using a conveyor. At the same time, the shorter the time interval spent by the worker on the operation, the more monotonous the work, the more simplified its content, which leads to premature fatigue and rapid nervous exhaustion;
Forms of work associated with remote control. With these forms of labor, a person is included in the management system as a necessary operational link, the load on which decreases with an increase in the degree of automation of the management process. There are forms of production process control that require frequent human actions, and forms of control in which the operator's actions are episodic, and his main task is to control instrument readings and maintain constant readiness to intervene, if necessary, in the process of managing an object;
Forms of intellectual (mental) labor are divided into operator, managerial, creative, labor of medical workers, labor of teachers, students, students. These types differ in the organization of the labor process, the uniformity of the load, the degree of emotional stress.
The work of the operator is characterized by great responsibility and high neuro-emotional stress. For example, the work of an air traffic controller is characterized by the processing of a large amount of information in a short time and increased neuro-emotional tension.
The work of the head of institutions, enterprises
(managerial work) is determined by an excessive amount of information, an increase in the lack of time for its processing, increased personal responsibility for decisions made, and the periodic occurrence of conflict situations.
The work of teachers and medical workers is characterized by constant contacts with people, increased responsibility, often lack of time and information to make the right decision, which causes the degree of neuro-emotional stress.
The work of pupils and students is characterized by the tension of the main mental functions, such as memory, attention, perception; the presence of stressful situations (exams, tests).
The most complex form of labor activity, which requires a significant amount of memory, stress, attention, is creative work. The work of scientists, designers, writers, composers, artists, architects leads to a significant increase in neuro-emotional stress. With such tension associated with mental activity, one can observe tachycardia, an increase in blood pressure, an increase in pulmonary ventilation and oxygen consumption, an increase in body temperature and other changes in the autonomic functions of a person.
The energy that a person needs for life is released in his body in the process of redox decomposition of carbohydrates, proteins, fats and other organic compounds contained in food. Redox reactions in living organisms can proceed both with the participation of oxygen and without the participation of oxygen. Anaerobic oxidation is characterized by a smaller amount of released energy and is of limited importance in higher organisms.
Aerobic oxidation of 1 g of fat in the body releases 38.94, while oxidation of 1 g of protein or 1 g of carbohydrates
* 17.6 kJ of energy. This energy is partially spent on useful work and partially dissipated in the form of heat, heating the human body and the environment (the efficiency of muscle tissues is 40 ... 60%).
The totality of chemical reactions in the human body is called metabolism. To characterize the total energy ‘metabolism, the concepts of basal metabolism and metabolism are used in various types of activity.
The basal metabolism is characterized by the amount of energy expenditure in a state of complete muscle rest under standard conditions (at a comfortable ambient temperature, 12 ... 16 hours after eating in the supine position). Energy consumption for life processes under these conditions for a person weighing 75 kg is 87.5 W.
Changes in posture, intensity of muscular activity, information saturation of labor, degree of emotional stress and other factors lead to additional
energy costs. So, in a sitting position due to the work of the body, energy costs exceed 5 ... 10 % the level of general metabolism, in a standing position - by 10 ... 15%, with a forced uncomfortable posture - by 40-50 %.
With intensive intellectual work, the brain's need for energy is 15-20% of the basal metabolism (the brain mass is 2% of the body mass). The increase in total energy costs during mental work is determined by the degree of neuro-emotional tension. So, when reading aloud while sitting, energy consumption increases by 48%, when delivering a public lecture - by 94%, for computer operators - by 60 ... 100%. An increase in metabolism and energy consumption during work leads to an increase in heat generation. With heavy physical work, body temperature can rise by 1 ... 1.5 degrees.
The level of energy consumption can serve as a criterion for the severity of the intensity of the work performed, which is important for optimizing working conditions and its rational organization. The level of energy consumption is determined by the method of indirect colorimetry, i.e. full gas analysis (taking into account the volume of oxygen consumption and emitted carbon dioxide). (With an increase in the severity of work, oxygen consumption and the amount of energy consumed increase significantly.
Option 9.
10. Energy costs for various forms of activity. Classification of working conditions
The level of human energy consumption in various forms of activity serves as a criterion for the severity and intensity of the work performed, is of great importance for optimizing working conditions and its rational organization. The level of energy consumption is determined by the method of full gas analysis, while taking into account the volume of consumption
oxygen and released carbon dioxide. With an increase in the severity of labor, oxygen consumption and the amount of energy consumed increase significantly.
The severity and intensity of labor are characterized by the degree of functional stress of the body. It can be energetic, depending on the power of work (during physical labor), and emotional (during mental labor), when information overload occurs.
Physical labor is characterized by a heavy load on the body, requiring mainly muscle effort and appropriate energy supply, and also affects functional systems (cardiovascular, neuromuscular, respiratory, etc.), stimulates metabolic processes. Its main indicator is severity. Energy consumption during physical labor, depending on the severity of the work, is 4000 - 6000 kcal per day, and with a mechanized form of labor, energy costs are 3000 - 4000 kcal.
With very hard work, oxygen consumption continuously increases, and oxygen debt can occur when non-oxidized metabolic products accumulate in the body. The growth of metabolism and energy consumption leads to an increase in heat generation, body temperature by 1-1.5 ° C. Thus, energy costs are a criterion for the physical severity of labor.
Mental labor combines work related to the reception and transmission of information, requiring activation of the processes of thinking, attention, memory. This type of labor is characterized by a significant decrease in motor activity. The main indicator of mental labor is tension, which reflects the load on the central nervous system. Energy consumption during mental work is 2500-3000 kcal per day. But energy costs vary depending on the working posture. So, in a working posture sitting, energy costs exceed the level of basal metabolism by 5–10%; standing by 10-25%, with a forced uncomfortable posture - by 40-50%. With intensive intellectual work, the brain's need for energy is 15-20% of the total metabolism in the body. The increase in total energy costs during mental work is determined by the degree of neuro-emotional tension. Daily energy consumption during mental work increases by 48% when reading aloud while sitting, by 90% - when lecturing, by 90-100% - for computer operators. In addition, the brain is prone to inertia, because after the cessation of work, the thought process continues, which leads to greater fatigue and exhaustion of the central nervous system than during physical labor.
Mental work is associated with nervous tension, which depends on the significance, danger and responsibility of the work. With nervous tension, tachycardia, an increase in blood pressure, an ECG change, and an increase in oxygen consumption occur. For the correct organization of mental activity, it is necessary: to gradually "enter" the work, to observe the rhythm, systematicity.
Muscular work affects the cardiovascular system, increasing blood flow from 3-5 L / min to 20-40 L / min to ensure gas exchange. At the same time, the number of heart contractions increases to 140-180 per minute. and blood pressure up to 180-200 mm Hg.
An increase in the intensity of work is accompanied by an increase in air exchange (from 5-8 l / min to 100 l / min), respiratory rate (from 10-20 to 30-40 per min) and the proportion of oxygen use (from 3-4% to 4-8% ). The latter is due to the effort of C*2 diffusion into the lungs.
Under the influence of muscular work, the morphological composition of the blood, its physicochemical properties change: the number of erythrocytes and hemoglobin content increase, the process of erythrocyte regeneration intensifies, and the number of leukocytes increases. These changes indicate an increase in the function of the hematopoietic organs. Certain changes during physical work occur in endocrine functions (increase in blood levels of adrenaline, etc.), which contributes to the mobilization of energy resources of the body.
Working conditions are a set of factors of the working environment that affect the working capacity and health in the process of work.
Based on hygienic criteria, working conditions are divided into 4 classes 1:
1. Optimal working conditions ensure maximum labor productivity and minimum stress on the human body. Optimal standards have been established for microclimate parameters and labor process factors. For other factors, such working conditions are conditionally used, under which the levels of adverse factors do not exceed those accepted as safe for the population (within the background).
Not only the health of workers is preserved, but also prerequisites are created for maintaining high labor productivity. At the same time, such working conditions are taken as optimal, under which adverse factors do not exceed the levels accepted as safe for the population.
2. Permissible working conditions. With them, the harmful effects do not exceed the levels established for workplaces, and possible changes in the functional state of the body are restored during rest, and should not have an adverse effect in the near and long term on the health of workers and their offspring. Changes in the functional state of the body are restored during a regulated rest or by the beginning of the next shift.
Classes 1 and 2 correspond to safe working conditions.
3. Harmful working conditions, under which the presence of harmful production factors exceeding hygienic standards has an adverse effect on the body of the worker and his offspring.
4. Dangerous working conditions. Exposure to harmful factors during the shift poses a threat to life, and there is a high risk of severe forms of acute occupational injuries.
In accordance with R.2.2.755-99, three classes of working conditions are distinguished in terms of the severity and intensity of labor.
Optimal (easy) work.
Allowable work (moderate).
Harmful (hard) work.
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The increase in total energy costs during mental work is determined by the degree of neuro-emotional tension. So, when reading aloud while sitting, energy consumption increases by 48%, when delivering a public lecture - by 94%, for computer operators - by 60 ... 100%.
The level of energy consumption can serve as a criterion for the severity and intensity of the work performed, which is important for optimizing working conditions and its rational organization.
The physical severity of labor is a load on the body during labor, requiring mainly muscle effort and appropriate energy supply. Taking into account the type of load and loaded muscles, physical work is divided into static and dynamic 2.
Static work is associated with the fixation of tools and objects of labor in a stationary state, with the maintenance of the body or its parts in space (fixation of the working posture).
There is no external muscular work, but the tense state of the muscles remains, lasting indefinitely. This leads to severe muscle fatigue, and taking into account their insufficient blood supply, to a disease of the muscular and peripheral nervous system. An example of static work is a sentry at the post.
Dynamic work - the process of muscle contraction, leading to the movement of the load, as well as the human body itself or its parts, in space. Play a role: strength, speed, accuracy, intensity of movement.
At the same time, the energy of the body is spent both on maintaining a certain tension in the muscles and on the mechanical effect of work. Dynamic work is subdivided into general muscular work performed by more than 2/3 of the muscles of the skeletal muscles, including the legs and torso (loaders, agricultural workers); regional muscular work, which is performed by the muscles of the shoulder girdle and upper limbs; local muscle work involving less than 1/3 of the skeletal muscles.
The severity and intensity of labor are characterized by the degree of functional stress of the body. It can be energetic, depending on the power of work - during physical labor, and emotional - during mental labor, when information overload occurs.
The intensity of labor is characterized by the emotional burden on the body during labor, which requires mainly the work of the brain to receive and process information. The easiest is mental work, in which there is no need to make decisions. Such working conditions are considered optimal. If the operator works and makes decisions within the framework of one instruction, then such working conditions are acceptable.
The stressful harmful conditions of the 1st degree include work that is associated with solving problems using known algorithms. Creative activity that requires solving complex problems in the absence of an obvious solution algorithm should be classified as hard work of the 2nd degree.
Working conditions can also be:
- physical;
household;
social;
production.
As a result of the impact on a person of physical working conditions, the following may occur: overwork; hypothermia; overheat; pollution and draft.
Comfortable conditions include: household amenities, livability, comfort. In accordance with current regulations, the following conditions are considered comfortable:
- t \u003d 18-20 ° C;
- pressure 760 mm Hg. Art.;
- minimum air velocity - 0.1 m/s, relative humidity - 45-50% in summer, 50-55% - in winter.
Features of the labor activity of women and adolescents 3
When using women and adolescents in the workplace, it is necessary to take into account the anatomical and physiological characteristics of their body.
In adolescence, there is an accelerated growth of the bones of the skeleton and muscles, especially the limbs, and at the same time, weakness of the ligamentous apparatus, faster muscle fatigue, and deviations in the development of the respiratory and gastrointestinal tract are not uncommon.
For persons aged 16-18 years, a reduced - 36-hour - working week is established. The use of the labor of adolescents in carrying heavy loads is limited, and if the work is connected specifically with the transfer of heavy loads, then the weight of the load should not exceed 4.1 kg.
The anatomical and physiological characteristics of women in some cases, with an unsatisfactory working environment, can contribute to the occurrence of gynecological diseases and affect the reproductive function of women. For working women, they regulate the limits for carrying and moving goods, introduce more favorable work and rest regimes, limit the use of women's labor at night, and establish for them a mode of work with part-time work or part-time work week.
The maximum weight of the load lifted and moved by women, subject to the alternation of this work with other types of work up to 2 times per hour, is 10 kg, and with constant lifting and moving of weights during the work shift - 7 kg.
Since the body of a woman is especially vulnerable during pregnancy, there is a need to transfer women for a certain time to work that is not associated with the danger of exposure to difficult and harmful working conditions.
37. Natural defense systems of the body
The human body has a number of systems to ensure its own safety. These include some sense organs: eyes, ears, nose; musculoskeletal system; leather; immune defense system; pain, as well as protective-adaptive reactions such as inflammation and fever. Protective and adaptive reactions are aimed at maintaining the constancy of the internal environment of the body and adapting it to the conditions of existence, they are regulated by reflex and humoral (hormones, enzymes, etc.) way. For example, the eyes have eyelids - two musculocutaneous folds that cover the eyeball when closed. The eyelids have the function of protecting the eyeball, reflexively protecting the organ of vision from excessive light flux, mechanical damage, help moisten its surface and remove foreign bodies with a tear. Ears at excessively loud sounds provide a protective reaction: the two smallest muscles of our middle ear contract sharply and the three smallest bones (hammer, anvil and stirrup) stop vibrating completely, blockage occurs, and the ossicular system does not let excessively strong sound vibrations into the inner ear.
Sneezing belongs to the group of defensive reactions and represents forced exhalation through the nose (when coughing - forced exhalation through the mouth). Due to the high speed of the air jet, foreign bodies and irritating agents that have got there are carried away from the nasal cavity.
Lachrymation occurs when irritants enter the mucous membrane of the upper respiratory tract: nose, nasopharynx, trachea and bronchi. A tear not only stands out, but also enters the nasal cavity through the lacrimal canal, thereby washing away the irritating substance (therefore, they "squish" their nose when crying).
Pain occurs when the normal course of physiological processes in the body is disturbed when receptors are irritated when organs and tissues are damaged due to exposure to harmful factors. Pain is a signal of danger to the body and at the same time pain is a protective device that causes special protective reflexes and reactions. Subjectively, a person perceives pain as a painful, oppressive sensation. Objectively, the pain is accompanied by some autonomic reactions (dilated pupils, increased blood pressure, pallor of the skin of the face, etc.). With pain, the release of biologically active substances increases (for example, the concentration of adrenaline increases in the blood). Pain sensitivity is inherent in almost all parts of our body. The nature of pain sensations depends on the characteristics of a particular organ and the strength of the destructive effect. For example, pain in case of damage to the skin differs from a headache; in case of injury to the nerve trunks, a burning pain sensation occurs - causalgia. Pain sensation as a protective reaction often indicates the localization of the pathological process.
65. Methods and means of protection against noise, give schemes: soundproof casing, screening of noise sources, noise suppressor
According to GOST 12.1.003-83, when developing technological processes, designing, manufacturing and operating machines, industrial buildings and structures, as well as organizing workplaces, all necessary measures should be taken to reduce the noise affecting a person to values that do not exceed permissible values.
Noise protection should be ensured by the development of noise-proof equipment, the use of means and methods of collective protection, including building acoustics, and the use of personal protective equipment.
First of all, you should use the means of collective protection. In relation to the source of noise excitation, collective protective equipment is divided into means that reduce noise at the source of its occurrence, and means that reduce noise along the path of its propagation from the source to the protected object.
Noise reduction at the source is achieved by improving the design of the machine or changing the process. Means that reduce noise at the source of its occurrence, depending on the nature of noise generation, are divided into means that reduce noisemechanical origin, aerodynamic And hydrodynamic origin, electromagnetic origin.
Methods and means of collective protection, depending on the method of implementation, are divided into construction-acoustic, architectural-planning and organizational-technical and include:
- noise emission redirection;
rational planning of enterprises and industrial premises;
acoustic treatment of rooms;
soundproofing application.
The choice of the width of the sanitary protection zone depends on the installed equipment, for example, the width of the sanitary protection zone around large thermal power plants can be several kilometers. For objects located within the city, the creation of such a sanitary protection zone sometimes becomes an unsolvable task. It is possible to reduce the width of the sanitary protection zone by reducing noise along the paths of its propagation.
Personal protective equipment (PPE) is used when it is not possible to ensure an acceptable noise level in the workplace in other ways.
The principle of operation of PPE is to protect the most sensitive channel of noise exposure to the human body - the ear. The use of PPE helps to prevent the disorder not only of the hearing organs, but also of the nervous system from the action of an excessive stimulus.
PPE is most effective, as a rule, in the high frequency region.
PPE includes anti-noise inserts (ear plugs), earmuffs, helmets and hard hats, special suits.
In the free zone, sound intensity decreases by 6 dB(A) for doubling the distance from its source. For example:
1 m - 70 dB(A)
2 m - 64 dB(A)
4 m - 58 dB(A)
8 m - 52 dB(A).
If there are other buildings or surfaces in the space around the sound source, it becomes a semi-reflective zone. In a semi-reflective zone, the sound intensity decreases by 3 dB(A) for doubling the distance from its source. But from some point in this zone, the value of 6 dB (A), characteristic of the free zone, applies. For example:
1 m - 70 dB(A)
2 m - 67 dB(A)
4 m - 64 dB(A)
8 m - 58 dB(A).
With the help of such simple calculations, it is possible to estimate the noise level within a radius of 100 m from its source.
The noise remains in the engine room. If the room is deserted or the staff works in it for a short time and from time to time, this method is quite acceptable.
If the room is constantly occupied or used for other purposes at the same time, it may be more advantageous to close the power unit with a soundproof casing, which provides an opening for cooling air, a duct for the removal of heated air and noise barriers. Enclosure cladding made of glass wool or rock wool, attached with perforated panels, absorbs some of the mechanical noise. The same principle is used in the direct-flow muffler.
Such a casing provides indoor noise level acceptable for the personnel working in it. An additional benefit is the significant reduction in noise levels around the engine room. See fig. 1 (49). The engine ventilation system must be changed to remove blow-by gases from the casing and, if necessary, from the room. This will prevent clogging of the radiator core. If engine noise cannot be reduced, make sure that there are no other sources of noise in the vicinity that are stronger than engine noise. Perhaps the installation has nothing to do with it.
One of the ways to reduce the noise of gas turbine driven units is the installation of soundproof casings that completely cover the most noisy units. A significant advantage of this method is the ability to reduce noise by any required value at the calculated points located at the workplaces of workers. Casings can be removable or collapsible, have viewing windows, opening doors, as well as openings for entering various communications. In this case, all the elements listed above must be structurally designed in such a way as to provide the same acoustic efficiency as that of a continuous sealed casing.
According to the design, soundproof casings are divided into:
1) removable, completely covering the source of noise;
2) collapsible, covering the entire sound-active surface or only part of it;
3) deaf, airtight, having no passages for entering communications, viewing windows, doors, etc.;
4) leaky, with passages for entering communications, viewing windows, doors, etc.
Basic requirements for the device and design of soundproof casings:
1) her casing elements must have the same soundproofing ability;
2) casings should be installed on the floor, on rubber gaskets, since as a result of vibration, the walls of the casing can serve as sources of structural noise;
3) in all cases when vibrations from an isolated noise source can be transmitted to the casing, the outer walls of the casing must be covered with a mastic-type vibration-damping material, the coating thickness of which should be 2-3 times greater than the walls of the casing;
4) provide for a gap between the surface of the noise source and the casing wall;
5) steel, duralumin and other sheet materials are recommended as a structural material for the manufacture of casings;
6) the inner surface of the casing walls must be lined with sound-absorbing materials 30-50 mm thick.
Enclosing surfaces of the casing (Figure 2) consist of a metal casing, sound-absorbing lining, perforated sheet. The casing has openings for the passage of air, which are made in the form of slotted mufflers. On the air intake side, a rectangular slotted absorption muffler is installed, and on the air outlet side, a muffler in the form of narrow concentric rings formed by sound-absorbing elements. The drive shaft runs inside a cylindrical absorption muffler. The effectiveness of all provided silencers is equal to the soundproofing capacity of the casing.
Figure 2 - Scheme of the soundproof casing
1 - fan; 2, 4 - cylindrical and slotted mufflers; 3 - unit; 5 - rubber gasket; 6 - metal sheet; 7 - sound-absorbing material; 8- perforated sheet
Acoustic screens are, in accordance with the classification of GOST 12.1.029-80, one of the means of sound insulation.
There are natural and artificial screens. Artificial? these are specially made screens to reduce mainly local noise sources, widely used to reduce the noise of transformers, mobile compressor rooms, cooling towers, etc. It is known to use a screen to reduce the entire noise of thermal power plants. For this purpose, a wall 153 m long and 18 m high was built at the Redondo Beach TPP (USA). Appropriate placement of noisy equipment behind natural screens from the residential area allows in some cases to solve the problem of noise reduction from them. The maximum efficiency of outdoor screens can reach 25-30 dBA.
The ability of screens to reduce noise is based on the reflection and dispersion of sound waves incident on them. A “sound shadow” is formed behind the screen if its dimensions are larger than the wavelength of the sound wave. The screens achieve the greatest efficiency in the region of high frequencies, the least - in the region of low frequencies.
The reduction in the sound pressure level of an infinitely long conventional screen DL e is determined by the formula
, (5.1)
Where N= 2d/l? Fresnel number; l =c/f ? wavelength, m; With? sound speed, m/s; f? frequency Hz; d =a+b-d; and +b? the length of the shortest path from the source to the calculated point, passing through the upper edge of the screen; d? the distance between them along a straight (hairline) line (Fig. 5.2); th is the hyperbolic tangent.
When d=0 at the border of the shadow DL e =5 dB. When calculating noise reduction, instead of formula (5.1), you can use Fig.3.
Rice. 3. Sound shielding schemes with natural barriers: A ? mound; b ? - building; V ? excavation; ISH ? noise source
Noise silencers of the GTU are installed at the outlets of the suction duct and exhaust duct into the atmosphere. Silencers must provide the necessary noise reduction in the required frequency range and have a minimum aerodynamic drag.
etc.................
FEDERAL AGENCY FOR EDUCATION
State educational institution
higher professional education
MOSCOW STATE UNIVERSITY
FOOD PRODUCTION (MGUPP)
Department ""
Human energy costs in various activities.
Moscow 2013
Introduction
The level of human energy consumption in various forms of activity serves as a criterion for the severity and intensity of the work performed, is of great importance for optimizing working conditions and its rational organization. The level of energy consumption is determined by the method of complete gas analysis, while taking into account the volume of oxygen consumption and carbon dioxide released. With an increase in the severity of labor, oxygen consumption and the amount of energy consumed increase significantly.
The severity and intensity of labor are characterized by the degree of functional stress of the organism. It can be energetic, depending on the power of work (during physical labor), and emotional (during mental labor), when information overload occurs.
Forms of work
Types of labor activity of a person can be classified as follows.
1. Labor requiring significant muscle activity.
2. Group form (conveyor), accompanied by monotony, rhythm, a certain pace, and is often associated with rapid fatigue and nervous exhaustion.
3. Mechanized forms of labor.
4. Automated labor. It is characterized by monotony and loss of creativity.
5. Mental work. It is characterized by increased attention, a large amount of information, increased sensory tension, emotionality, nervous tension, enhanced mineral metabolism in brain cells, and the possibility of stressful situations.
In turn, mental labor has the following forms.
1. The work of the dispatcher (increased nervous tension due to great personal responsibility, especially at nuclear power plants (NPP) and in aviation).
2. Managerial work (personal responsibility, a large amount of information).
3. Creative work (emotional stress, memory, attention).
4. The work of a teacher, a health worker (contact with people, a large amount of information, emotional stress).
5. The work of students and pupils (increased attention, memory, stressful situations).
Any type of labor activity has the following phases of change in working capacity:
Phase 1 - working out (for physical labor, the time spent is from several minutes to 1.5 hours, for mental labor up to 2.5 hours);
Phase 2 - high performance (approximately 2-2.5 hours);
Phase 3 - reduced performance (characterized by fatigue, deterioration of attention, disorder of the auditory and visual analyzers, an increase in the number of errors).
Statistically, the highest labor productivity is observed on such days of the week as Tuesday, Wednesday and Thursday.
The performance of a person also depends on the shift and the time within the shift:
1. maximum efficiency in the 1st shift from 8 am to 12 pm, in the second shift from 2 pm to 5 pm;
2. The minimum performance is observed in the night shift, from about 3 to 5 hours.
When organizing your work, it is advisable to observe the following recommendations:
1. the workplace must meet the requirements of ergonomics and technical aesthetics;
2. combine physical work with mental work, observe the alternation of work and rest, given that mental work requires more frequent but short breaks, while physical work is the opposite.
The traditional, officially accepted approach to the problem of restoring a person's energy costs says that a certain amount of energy must be spent on a certain amount of work, which, in turn, must be restored with a strictly defined amount of food.
Energy consumption in various forms of activity
The daily energy consumption of a person includes the value of the basal metabolism and the energy necessary to perform professional work, sports and other forms of muscle activity. Mental labor requires little energy costs. During physical work, energy consumption can reach very large values. For example, when walking, energy is consumed by 80 - 100% more compared to rest, while running - by 400% or more. consumption energy physical activity
According to the nature of the production activity performed and the amount of energy costs, the adult population can be divided into 4 groups. The first group includes persons whose professions are not related to physical labor. Their daily energy consumption is 2000 - 3000 kcal. For those engaged in fully mechanized labor, energy consumption is increased to 3500 kcal. With non-mechanized fishing, the daily energy consumption can reach 4000 kcal. Very hard non-mechanized labor causes energy consumption equal to 4500 - 5000 kcal. In some cases, when performing long and hard work, the daily energy consumption can increase to 7000 - 8000 kcal. With the mechanization of industry and agriculture, the energy consumption of workers has sharply decreased (for example, when mowing by hand, the daily energy consumption reaches an average of 7,200 kcal, while mowing by a machine - 3,600 kcal). Sports activity is accompanied by a significant increase in daily energy consumption (up to 4500 - 5000 kcal). On days of training with increased loads and competitions in some sports (cross-country skiing, long-distance running, etc.), these values \u200b\u200bcan be even higher. Ceteris paribus, the energy consumption is the greater, the relatively longer and more intense the work performed.
Muscular work is necessary for the normal functioning of the body. The amount of energy spent directly on physical work should be at least 1200 - 1300 kcal per day. In this regard, for people who do not engage in physical labor and spend less energy on muscle activity, physical exercise is especially necessary.
The level of energy consumption is also affected by the emotions that arise during any activity. They can enhance or, conversely, reduce the metabolism and energy in the body. Energy consumption depends not only on the amount of work performed, but also on the environmental conditions in which the work is performed: air temperature and humidity, barometric pressure, wind force.
The rhythm of work movements also affects energy consumption. However, the rhythm of work that causes the minimum energy consumption is not always the most beneficial. In general, the tedium of work cannot be judged by the amount of energy expenditure. For example, very tedious static work requires less energy to perform than seemingly easier dynamic work.
After the end of muscular activity, energy expenditure remains for some time still elevated compared to the level of rest. This is due to chemical processes in the muscle associated with the oxidation of lactic acid and the elimination of oxygen debt.
When a person performs mechanical work, the coefficient of efficiency can reach 20 - 25%. The rest of the released energy is converted into heat. Efficiency during physical work depends on the structure of movements, their pace, on the number of muscles involved in the work, on the fitness of the person performing the work.
Energy consumption in various activities
Kind of activity |
Energy consumption per 1 kg of body weight |
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The work of a carpenter and metal worker |
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The labor of a bricklayer |
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Tractor labor |
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Labor of an agricultural worker |
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Household labor |
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Mental work in the laboratory sitting |
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Mental work in the laboratory standing |
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Classes at the school |
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Personal hygiene |
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Putting on and taking off shoes and clothes |
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Eating while sitting |
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Standing rest |
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Rest sitting |
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Rest lying without sleep |
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Bed making |
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Physical exercise |
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Walking 110 steps in 1 min |
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Walking 6 km/h |
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Running 8 km/h |
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Running 10.8 km/h |
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Cycling at a speed of 10-12 km/h |
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Swimming at 50 m/min |
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Energy expenditure in various sports activities
Kinds of sports |
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Gymnastics, fencing |
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Volleyball basketball |
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Short distance runners, jumpers, throwers |
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Long distance runners |
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Boxing, wrestling, weightlifting |
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a light weight |
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average weight |
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heavy weight |
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Alpine skiing, ski jumping |
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Ski race |
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Swimming |
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Shooting |
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Horseback Riding |
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Cycling |
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The last two tables are considered as average because. the level of real energy consumption varies depending on the degree of training of a person, external conditions and other factors. Given the insufficient accuracy of the method for determining energy costs using these tables, the results obtained should be increased by 10-15%.
Energy expenditure at rest and during exercise
An increase in physical activity leads to an increase in energy consumption obtained from a sports diet. From the table, we see, for example, that slow walking increases energy expenditure by 3 times compared to sleep, and sprinting by more than 40 times.
Energy expenditure at rest and during exercise
The nature of the load, the state of the body |
Energy consumption per 1 min per 1 kg of body weight, cal |
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Rest lying down (no sleep) |
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Mental work sitting |
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Reading aloud |
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Standing in the yard |
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Walking 50 meters per minute |
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Walking 6 km/h |
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Indoor walking 100 m/min |
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Skiing on level ground |
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Swimming |
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Walking 8 km/h |
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Walking interspersed with running, 140 m/min |
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Obstacle course driving |
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crawling |
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Running 60 m in competitions |
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The level of fitness has a significant effect on energy expenditure. Sports training reduces energy consumption, protects the athlete's body from overwork, shortens the recovery period after work, and makes it possible to develop significant stress in a short time.
This is achieved by better coordination of movements, greater adaptability of the cardiovascular and respiratory systems to work, as well as certain shifts in metabolic processes.
Replenishment of human energy costs
In essence, digestion is a "stove" where "firewood" is burned - proteins, fats and carbohydrates, which have a calculated amount of energy (1 gram of fat gives 9.3 kcal, 1 gram of carbohydrates and 1 gram of protein - 4.1 kcal each). Accordingly, energy is spent:
1. for life support (together with thermoregulation) - approximately 50-60% (1 kcal per 1 kg of body weight per hour, and during sleep approximately 0.93 kcal per 1 kg of body weight per hour);
Types of energy costs
For each person, the amount of energy entering his body and the amount of energy that is expended in the process of his activity is of great importance. It is important that the income and expenditure of energy are in a ratio that allows a person to feel vigorous and healthy.
Allocate such energy costs:
- unregulated;
- Adjustable.
Unregulated are the energy costs for BX and the specifically dynamic action of food. The energy of the main metabolism is spent in order to ensure the functioning of internal organs, goes to redox reactions and maintain a constant temperature of the human body.
Remark 1
In other words, BX- This is the minimum level of energy consumption that supports the vital functions of the body.
It can be determined under the condition of complete muscular and nervous rest. Value basal metabolism associated with body weight, height, age, gender, the state of the endocrine system, i.e. with the individual characteristics of each person. As a rule, for women, for example, the basic exchange rate is $5$ -$10$% lower than that of men. In children, it is higher than in adults, relative to body weight, by $10$ -$15$%. In increasing the basal metabolism, the specific dynamic action of food associated with the process of digestion plays its role. The basal metabolic rate will be $30$-$40$% higher with protein digestion, $4$-$14$% with fat digestion, and $4$-$5$% with carbohydrate digestion. If the diet is mixed, then the increase in basal metabolism occurs on average by $10$ -$15$%, subject to the optimal amount of digested products.
To the group regulated energy costs include the energy costs in the process of various human activities. As a rule, the greatest energy costs are associated with physical work, because in the working muscles there is a significant increase in oxidative processes. The intensity of muscle movements increases the level of energy consumption. BX when walking calmly, it increases by $ 80 - $ 100 $ %, and while running - by $ 400 $ %.
For energy cost estimates There are several methods, the most accurate of which is direct calorimetry. Its essence is connected with measuring the amount of thermal energy released during the performance of any work in special chambers with a high degree of thermal insulation. The method does not provide the possibility of measurements in many types of activities and requires long-term observations.
Less accurate, but more accessible and simple, is the method indirect nutritional calorimetry. When using this method, the amount of food consumed is calculated and body weight is monitored.
Energy consumption during physical activity is determined heart rate integration method. The bottom line lies in fixing the heart rate with the help of equipment throughout the work.
Forms of activity and energy costs
Human activity is associated with energy costs, which depend on the intensity of muscle work, the working posture of the body, the information saturation of labor, emotional stress, temperature, humidity, air velocity and other factors. Due to the work of the muscles of the body in the sitting position, energy expenditure exceeds the level of basal metabolism by $5$…$10$%, in the standing position by $10$…$15$%, and the forced uncomfortable posture leads to an increase by $40$…$50$%. Different forms of human activity have different hygienic standards for daily energy consumption.
According to energy consumption, the following groups are distinguished:
Employees mental labor. Representatives of this group are business leaders, teachers, scientists, doctors, writers, journalists, students. For men of this group, the daily energy consumption is $2550-$2800 kcal, for women - $2200-$2400 kcal, the average value is $40 kcal/kg of body weight.
Employees light physical labor- workers of automated lines, sewers, veterinarians, agronomists, nurses, sellers of industrial goods, trainers, physical education instructors. Men spend $3000$-$3200$ kcal per day, women of this group spend $2550-$2700 kcal. The average value increases to $43$ kcal/kg of body weight.
Work medium in severity. The workers in this group are surgeons, drivers, workers in the food industry, water transport, food vendors. Energy consumption for men per day is $3200-$3650 kcal and for women $2600-$2800 kcal. For $1$ kg of body weight, energy costs increase to $46$ kcal.
Workers employed hard physical labor- these are builders, metallurgists, machine operators, athletes, agricultural workers. Their daily energy consumption is the highest and for men it is $3700-$4250 kcal, for women it is $3150-$3900 kcal, with an average of $53 kcal/kg of body weight.
The last group includes people particularly hard physical labor. This group includes steelworkers, miners, lumberjacks, loaders, with daily energy consumption for men $3900$-$4300$ kcal. Consumption for women is not standardized. The average energy expenditure per $1$ kg of body weight is $61$ kcal.
Remark 2
The listed energy costs are calculated for men weighing $70$ kg, and for women weighing $60$ kg.
For each group, it is important to observe three age categories:
- From 19 to 28 years old;
- 30 to 39 years old;
- From 40 to 59 years old.
Organization of a rational mode of work and rest
To improve efficiency and prevent fatigue, it is important to be able to properly and rationally organize the regime of work and rest. In the mode, it is necessary to determine the time and duration of breaks for rest during the working day. In the middle of the working day, as a rule, a long lunch break is provided, in addition to which it is important to include short breaks during the working day. So that monotonous work on the assembly line does not lead to fatigue, $5$ -$10$ minute breaks are introduced into the mode after each hour of work, you can turn on calm music that has a beneficial effect on performance. Active recreation is also included in the rational organization of the labor regime.
Remark 3
More THEM. Sechenov, who proved that tired muscles quickly restore their performance when other muscles work, substantiated the expediency of outdoor activities from a physiological point of view.
Under production conditions, the discovery of the scientist was used in the form of a set of physical exercises, specially designed for this. But it was a distant Soviet past, when, indeed, the morning of the whole country began with exercises. Nowadays, morning exercises are done, perhaps, only in kindergartens and in the army, but some companies may be an exception, where employees are forced to spend the whole working day sitting at a computer monitor. True, in the country's schools, too, during the lesson, it is necessary to resort to short physical education sessions.
Remark 4
In general, a set of special exercises, selected for people of different specialties, performs very important work- first of all, it helps to improve the activity of the cerebral cortex, activates the functional processes of the whole organism, increases emotional tone and, as a rule, performance.
Energy costs for morning exercises per minute is $ 0.0648 kcal / kg of body weight. The highest level of efficiency, in accordance with the daily cycle, is observed in the morning and afternoon hours. Accordingly, from $8$-$12$ hours and from $14$-$17$ hours.
By the evening performance goes down and at night reaches its minimum.
different performance and in a week. On Monday, there is an induction into the labor process after a day off, and the highest level falls on the $2$-th, $3$-th, $4$-th day of the working week. By the end of the week performance declining.
There are 3 principles for establishing a rational regime of work and rest:
- Production needs (they must be satisfied);
- The highest working capacity of the employee (it must be ensured);
- Public and private interests (they must be combined).
Remark 5
Thus, a comprehensive socio-economic approach is needed when choosing the optimal mode of work and rest. This approach has a specific goal - to give a complete and comprehensive assessment of its optimization from the point of view of both personal and public interests, the interests of production and the physiological capabilities of a person.
The main forms of human activity and their classification
The nature and organization of labor activity have a significant impact on changes in the functional state of the human body. The form of labor activity is divided into physical and mental labor.
Physical work It is characterized primarily by an increased load on the musculoskeletal system and its functional systems (cardiovascular, neuromuscular, respiratory, etc.) that ensure its activity. Physical labor, while developing the muscular system and stimulating metabolic processes, at the same time has a number of negative consequences, primarily the social inefficiency of physical labor associated with its low productivity, the need for high physical exertion and the need for long (up to 50% of working time) rest.
Brainwork- combines work related to the reception and processing of information, requiring mainly the tension of the sensory apparatus, attention, memory, as well as the activation of thinking processes, the emotional sphere for this type of work is characterized by hypokinesia, i.e. a significant decrease in human motor activity, but leading to a deterioration in the reactivity of the body and an increase in emotional stress. Hypokinesia is one of the conditions for the formation of cardiovascular pathology in mental workers. Prolonged mental stress has a depressing effect on mental activity: the functions of attention (volume, concentration, switching), memory (short-term and long-term), and perception worsen (a large number of errors appear).
In accordance with the existing physiological classification of labor activity, there are:
Forms of labor that require significant muscle activity;
mechanized forms of labor;
Forms of labor associated with automatic, semi-automatic production;
Group forms of labor conveyor;
Forms of work associated with remote control;
Forms of intellectual or mental labor.
Forms of labor requiring significant muscular activity take place in the absence of mechanization; these works are characterized by increased energy consumption.
A feature of mechanized forms of labor is the change in the nature of muscle loads and the complication of the action program. Under the conditions of mechanized production, there is a decrease in the volume of muscle activity, small muscles of the limbs are involved in the work, which should provide greater speed and accuracy of movements necessary to control the mechanisms. The monotony of simple and mostly local actions, the monotony and the small amount of information perceived in the process of labor leads to the monotony of labor. At the same time, the excitability of the analyzers decreases, attention is scattered, the speed of reactions decreases, fatigue quickly sets in.
In semi-automatic production, a person is switched off from the process of direct processing of the object of labor, which completely performs the mechanism. The characteristic features of this type of work are monotony, an increased pace and rhythm of work, and a loss of creativity.
The conveyor form of labor is determined by the fragmentation of the labor process into operations, a given rhythm by a strict sequence of operations, automatic supply of parts to each workplace using a conveyor. At the same time, the shorter the time interval spent by workers on the operation, the more monotonous the work, the more simplified its content, which leads to premature fatigue and rapid nervous exhaustion.
In the forms of labor associated with the remote control of the production process and mechanisms, a person is included in the control system as a necessary operational link. In cases where the control panel requires frequent human actions, the worker's attention is discharged in numerous movements. In cases of rare active actions, the employee is in a state of readiness and action, his reactions are few.
Forms of intellectual labor are divided into operator, managerial, creative, labor of medical workers, labor of teachers, students, students. These types differ in the organization of the labor process, the uniformity of the load and the degree of emotional stress.
The work of the operator is characterized by great responsibility and high neuro-emotional stress. For example. The work of an air traffic controller is characterized by the processing of a large amount of information in a short time and increased neuro-emotional tension. The work of the heads of institutions and enterprises (managerial work) is determined by an excessive amount of information, an increase in the lack of time for its processing, increased personal responsibility for decisions made, and the periodic occurrence of conflict situations.
The work of teachers and medical workers is characterized by constant contacts with people, increased responsibility, often lack of time and information to make the right decision, which causes the degree of neuro-emotional stress. The work of pupils and students is characterized by the tension of basic mental functions, such as memory, attention, perception; the presence of stressful situations (exams, tests).
The most complex form of labor activity, which requires a significant amount of memory and attention, is creative work. The work of scientists, designers, writers, composers, artists, architects leads to a significant increase in neuro-emotional stress. With such tension associated with mental activity, one can observe tachycardia, an increase in blood pressure, an ECG change, an increase in pulmonary ventilation and oxygen consumption, an increase in human body temperature and other changes in autonomic functions.
The energy costs of a person depend on the intensity of muscular work, the information saturation of labor, the degree of emotional stress and other conditions (temperature, humidity, air velocity, etc.).
The daily energy consumption for persons of mental labor (engineers, doctors, teachers, etc.) is 10.5 ... 11.7 MJ, for workers in mechanized labor and the service sector (nurses, saleswomen, workers servicing machines) - 11.3 ... 12 .5 MJ, for workers performing moderate work (machine operators, miners, surgeons, foundry workers, agricultural workers, etc.) - 12.5 ... 15.5 MJ, for workers performing heavy physical work (miners, metallurgists, lumberjacks, loaders) - 16.3…18 MJ.
Energy costs vary depending on the working posture. When working in a sitting position, energy costs increase by 5-10% of the level of basal metabolism, when working standing by 10-25%, with a forced uncomfortable position by 40-50%. Intensive intellectual work requires the brain's energy needs of 15-20% of the total metabolism in the body (the brain mass is 2% of the body mass). The increase in total energy costs during mental work is determined by the degree of neuro-emotional stress. So, when reading aloud, energy consumption increases by 48%, when delivering a public lecture by 94%, for computer operators by 60-100%.
