The system and its main elements. System element - what is it? Examples of system elements. Elements of the economic system. The foundation of quality and its components
The functional environment of the system is a set of laws, algorithms and parameters characteristic of the system, according to which the interaction (exchange) between the elements of the system and the functioning (development) of the system as a whole is carried out.
An element of the system is a conditionally indivisible, independently functioning part of the system.
However, the answer to the question of what is such a part can be ambiguous. For example, as elements of the table, one can name “legs, boxes, a lid, etc.,” or “atoms, molecules,” depending on what task the researcher faces.
Therefore, we will accept the following definition: an element is the limit of the division of the system from the point of view of the aspect of consideration, the solution of a specific problem, the goal set.
Components and subsystems.
The concept of a subsystem implies that a relatively independent part of the system is singled out, which has the properties of the system, and in particular, has a subgoal, to which the subsystem is oriented, as well as other properties - integrity, communication, etc., determined by the laws of systems.
If parts of the system do not have such properties, but are simply collections of homogeneous elements, then such parts are usually called components.
Connection. The concept of connection is included in any definition of a system and ensures the emergence and preservation of its integral properties. This concept simultaneously characterizes both the structure (statics) and the functioning (dynamics) of the system.
Communication is defined as a limitation of the degree of freedom of elements. Indeed, the elements, entering into interaction (connection) with each other, lose some of their properties, which they potentially possessed in a free state.
Connections can be characterized by direction, strength, character (or type).
On the basis of the first feature, the connections are divided into directed and non-directed.
On the second - on strong and weak.
According to the nature (kind), there are connections of subordination, generation (or genetic), equal (or indifferent), management.
System structure- a set of links that provide energy, mass and information exchange between the elements of the system, which determines the functioning of the system as a whole and the ways of its interaction with the external environment.
Often the structure of the system is drawn up in the form of a graph. In this case, the elements are the vertices of the graph, and the edges denote connections.
If the directions of connections are distinguished, then the graph is oriented. Otherwise, the graph is undirected.
Target- a preconceived result of conscious human activity.
Symbolically, this definition of the system is represented as follows:
S ≡< A, R, Z >,
where A are elements;
R is the relationship between
elements;
Concepts characterizing the functioning and development of the system
The processes taking place in complex systems ah, as a rule, it is not immediately possible to represent in the form of mathematical relations or at least algorithms.
Therefore, in order to somehow characterize a stable situation or its changes, they use special terms borrowed by systems theory from the theory of automatic control, biology, and philosophy.
State. The concept of "state" usually characterizes an instant photo, a "slice" of a system, a stop in its development.
It is determined either through input actions and output signals (results), or through macro parameters, macro properties of the system (pressure, speed, acceleration).
Behavior. If a system is capable of transitioning from one state to another, then it is said to have behavior.
This concept is used when the patterns (rules) of the transition from one state to another are unknown. Then they say that the system has some kind of behavior and find out its nature, the algorithm.
Equilibrium. The concept of equilibrium is defined as the ability of a system in the absence of external disturbances (or under constant influences) to maintain its state for an arbitrarily long time.
Sustainability. Stability is understood as the ability of a system to return to a state of equilibrium after it has been brought out of this state under the influence of external (or in systems with active elements - internal) perturbing influences.
The state of equilibrium to which the system is able to return is called sustainable a state of balance.
The return to this state may be accompanied by an oscillatory process. Accordingly, unstable equilibrium states are possible in complex systems.
System classification
| sign | Types of systems |
| 1. Nature of the object | Natural Artificial - Real - Abstract |
| 2. The nature of the relationship with the environment | Open (continuous exchange) Closed (weak connection) |
| 3. Causation | Deterministic Probabilistic |
| 4. The nature of the elements | economic, social, technical, political, biological |
| 5. Degree of organization | Well organized Poorly organized Self-organized |
| 6. Relative to time | Static Dynamic |
| 7. By degree of difficulty | Small and Large Simple and Complex |
| 8. By the uniformity of the elements | Homogeneous Heterogeneous |
Large and complex systems
Large systems are those whose modeling is difficult due to their dimension, and complex systems are those for which there is not enough information to model.
Sometimes they allocate Very complex systems”, for the modeling of which humanity does not have the necessary information. This is the brain, the universe, society.
When modeling large systems, the decomposition method is used, in which the reduction in dimension is carried out by splitting into subsystems.
When modeling complex systems, special methods for reducing uncertainty are used.
There are many concepts of a system. Consider the concepts that most fully reveal its essential properties (Fig. 1).
Rice. 1. The concept of a system
"A system is a complex of interacting components."
"A system is a set of connected operating elements."
"A system is not just a collection of units ... but a collection of relationships between these units."
And although the concept of a system is defined in different ways, it is usually understood that a system is a certain set of interconnected elements that form a stable unity and integrity, which has integral properties and patterns.
We can define a system as something whole, abstract or real, made up of interdependent parts.
system any object of animate and inanimate nature, society, process or set of processes, scientific theory, etc., can be, if they define elements that form a unity (integrity) with their connections and interconnections between them, which ultimately creates a set of properties, inherent only to this system and distinguishing it from other systems (emergence property).
System(from the Greek SYSTEMA, meaning "a whole made up of parts") is a set of elements, connections and interactions between them and the external environment, forming a certain integrity, unity and purposefulness. Almost every object can be considered as a system.
System is a set of material and non-material objects (elements, subsystems) united by some kind of links (information, mechanical, etc.), designed to achieve a specific goal and achieve it in the best possible way. System defined as a category, i.e. its disclosure is made through the identification of the main properties inherent in the system. To study the system, it is necessary to simplify it while retaining the main properties, i.e. build a model of the system.
System can manifest itself as a holistic material object, which is a naturally conditioned set of functionally interacting elements.
An important means of characterizing a system is its properties. The main properties of the system are manifested through the integrity, interaction and interdependence of the processes of transformation of matter, energy and information, through its functionality, structure, connections, external environment.
Property is the quality of the object parameters, i.e. external manifestations of the way in which knowledge about an object is obtained. Properties make it possible to describe system objects. However, they can change as a result of the functioning of the system.. Properties are external manifestations of the process by which knowledge about an object is obtained, it is observed. Properties provide the ability to describe system objects quantitatively, expressing them in units that have a certain dimension. The properties of system objects can change as a result of its action.
There are the following basic properties of the system :
· The system is a collection of elements . Under certain conditions, elements can be considered as systems.
· The presence of significant relationships between elements. Under significant connections are understood as those that naturally, necessarily determine the integrative properties of the system.
· Presence of a specific organization, which is manifested in a decrease in the degree of system uncertainty compared to the entropy of system-forming factors that determine the possibility of creating a system. These factors include the number of elements of the system, the number of significant links that an element may have.
· The presence of integrative properties , i.e. inherent in the system as a whole, but not inherent in any of its elements separately. Their presence shows that the properties of the system, although they depend on the properties of the elements, are not completely determined by them. The system is not reduced to a simple collection of elements; decomposing the system into separate parts, it is impossible to know all the properties of the system as a whole.
· emergence – the irreducibility of the properties of individual elements and the properties of the system as a whole.
· Integrity - this is a system-wide property, which consists in the fact that a change in any component of the system affects all its other components and leads to a change in the system as a whole; and vice versa, any change to the system is reflected in all components of the system.
· Divisibility – it is possible to decompose the system into subsystems in order to simplify the analysis of the system.
· Communication. Any system operates in the environment, it experiences the effects of the environment and, in turn, affects the environment. Relationship between environment and system can be considered one of the main features of the functioning of the system, an external characteristic of the system, which largely determines its properties.
The system is inherent property to develop, adapt to new conditions by creating new links, elements with their own local goals and means to achieve them. Development– explains complex thermodynamic and informational processes in nature and society.
· Hierarchy. Under the hierarchy refers to the sequential decomposition of the original system into a number of levels with the establishment of a relationship of subordination of the lower levels to the higher ones. Hierarchy of the system consists in the fact that it can be considered as an element of a system of a higher order, and each of its elements, in turn, is a system.
An important system property is system inertia, which determines the time required to transfer the system from one state to another for given control parameters.
· Multifunctionality - the ability of a complex system to implement a certain set of functions on a given structure, which manifests itself in the properties of flexibility, adaptation and survivability.
· Flexibility - this is the property of the system to change the purpose of functioning depending on the conditions of functioning or the state of subsystems.
· adaptability - the ability of the system to change its structure and choose options for behavior in accordance with the new goals of the system and under the influence of environmental factors. An adaptive system is one in which there is a continuous process of learning or self-organization.
· Reliability – this property of the system to implement the specified functions for a certain period of time with the specified quality parameters.
· Safety – the ability of the system not to inflict unacceptable impacts on technical objects, personnel, environment during its operation.
· Vulnerability - the ability to receive damage under the influence of external and (or) internal factors.
· Structured - the behavior of the system is determined by the behavior of its elements and the properties of its structure.
· Dynamism is the ability to function in time.
· The presence of feedback.
Any system has a purpose and limitations. The purpose of the system can be described by the objective function U1 = F (x, y, t, ...), where U1 is the extreme value of one of the quality indicators of the system functioning.
System Behavior can be described by the law Y = F(x), which reflects changes at the input and output of the system. This determines the state of the system.
State of the system- this is an instant photograph, or a cut of the system, a stop in its development. It is determined either through input interactions or output signals (results), or through macro parameters, macro properties of the system. This is a set of states of its n elements and links between them. The task of a particular system is reduced to the task of its states, starting from the birth and ending with the death or transition to another system. The real system cannot be in any state. Restrictions are imposed on her condition - some internal and external factors (for example, a person cannot live 1000 years). Possible states of a real system form a certain subdomain Z SD (subspace) in the state space of the system – a set of admissible states of the system.
Equilibrium- the ability of the system in the absence of external disturbing influences or under constant influences to maintain its state for an arbitrarily long time.
Sustainability- this is the ability of the system to return to a state of equilibrium after it has been brought out of this state under the influence of external or internal disturbing influences. This ability is inherent in systems when the deviation does not exceed a certain established limit.
3. The concept of system structure.
System structure- a set of system elements and links between them in the form of a set. System structure means the structure, location, order and reflects certain relationships, the relationship of the constituent parts of the system, i.e. its structure and does not take into account the set of properties (states) of its elements.
The system can be represented by a simple enumeration of elements, but most often, when studying an object, such a representation is not enough, because it is required to find out what the object is and what ensures the fulfillment of the set goals.
Rice. 2. System structure
The concept of a system element. By definition element is an integral part of a complex whole. In our concept, a complex whole is a system that is an integral complex of interrelated elements.
Element- a part of the system that has independence in relation to the entire system and is indivisible with this method of separating parts. The indivisibility of an element is considered as the inexpediency of taking into account its internal structure within the model of a given system.
The element itself is characterized only by its external manifestations in the form of connections and relationships with other elements and the external environment.
The concept of communication. Connection- a set of dependencies of the properties of one element on the properties of other elements of the system. To establish a relationship between two elements means to identify the presence of dependencies of their properties. The dependence of the properties of elements can be one-sided and two-sided.
Relationships- a set of bilateral dependencies of the properties of one element on the properties of other elements of the system.
Interaction- a set of relationships and relationships between the properties of elements, when they acquire the character of mutual assistance to each other.
The concept of the external environment. The system exists among other material or non-material objects that are not included in the system and are united by the concept of "external environment" - objects of the external environment. The input characterizes the impact of the external environment on the system, the output characterizes the impact of the system on the external environment.
In fact, the delineation or identification of a system is the division of a certain area of the material world into two parts, one of which is considered as a system - an object of analysis (synthesis), and the other - as an external environment.
External environment- a set of objects (systems) existing in space and time, which are supposed to have an effect on the system.
External environment is a set of natural and artificial systems for which this system is not a functional subsystem.
Structure types
Let's consider a number of typical system structures used in the description of organizational, economic, production and technical objects.
Usually the concept of "structure" is associated with a graphical display of elements and their relationships. However, the structure can also be represented in matrix form, the form of a set-theoretic description, using the language of topology, algebra, and other system modeling tools.
Linear (serial) the structure (Fig. 8) is characterized by the fact that each vertex is connected to two neighboring ones. If at least one element (connection) fails, the structure is destroyed. An example of such a structure is a conveyor.
Ring the structure (Fig. 9) is closed, any two elements have two directions of communication. This increases the speed of communication, makes the structure more tenacious.
Cellular the structure (Fig. 10) is characterized by the presence of redundant connections, which increases the reliability (survivability) of the functioning of the structure, but leads to an increase in its cost.
Multiconnected structure (Fig. 11) has the structure of a complete graph. The reliability of functioning is maximum, the efficiency of functioning is high due to the presence of the shortest paths, the cost is maximum.
starry structure (Fig. 12) has a central node that acts as a center, all other elements of the system are subordinate.
graphovaya structure (Fig. 13) is usually used in the description of production and technological systems.
Network structure (net)- a kind of graph structure, which is a decomposition of the system in time.
For example, a network structure can display the operation of a technical system (telephone network, electrical network, etc.), stages of human activity (when manufacturing products - a network diagram, when designing - a network model, when planning - a network model, a network plan, etc. d.).
Hierarchical the structure is most widely used in the design of control systems, the higher the level of the hierarchy, the fewer links its elements have. All elements except the upper and lower levels have both command and subordinate control functions.
Hierarchical structures represent the decomposition of the system in space. All vertices (nodes) and connections (arcs, edges) exist in these structures simultaneously (not separated in time).
Hierarchical structures in which each element of the lower level is subordinate to one node (one vertex) of the higher one (and this is true for all levels of the hierarchy) are called treelike structures (structures type "tree"; structures on which tree-order relations hold, hierarchical structures with strong connections) (Fig. 14, a).
Structures in which an element of a lower level can be subordinated to two or more nodes (vertices) of a higher level are called hierarchical structures with weak connections (Fig. 14, b).
In the form of hierarchical structures, the designs of complex technical products and complexes, the structures of classifiers and dictionaries, the structures of goals and functions, production structures, and organizational structures of enterprises are presented.
In general, the termhierarchy more broadly, it means subordination, the order of subordination of the lowest in position and rank of persons to the highest, arose as the name of the "service ladder" in religion, is widely used to characterize relationships in the apparatus of government, the army, etc., then the concept of hierarchy was extended to any coordinated subordination order of objects.
Thus, in hierarchical structures, only the allocation of levels of subordination is important, and there can be any relationship between levels and components within a level. In accordance with this, there are structures that use the hierarchical principle, but have specific features, and it is advisable to highlight them separately.
System approach in management
The concept and types of systems. Essence systems approach and system analysis in management. Control system as an object of research. The main elements of the control system. Functional division of managerial labor. The number of intermediate levels of the hierarchical control system. Number of managers at each intermediate level. The number and professional composition of management personnel under each head. The matrix of subordination of managers. The quality of the management system. Quality criterion. Control Systems Research: Methodology and Process. Research and design of organizational structures of management.
A system is a set of interdependent elements that form a single whole; the whole performs some function. In a system, all its elements must be interdependent and/or interacting. The most diverse elements can be combined into a “whole”, but this “whole” is not yet a system until the mechanism of their interaction is formed. Even Aristotle wrote that the hand, separated from the body, is no longer a hand. And Hegel figuratively put it this way: only a corpse has parts, and the body has a new quality: it lives.
The world as a whole is a complex system, which in turn consists of many large and small systems. System is the opposite of chaos.
Systems take a variety of forms. Major systems include:
biological;
Technological;
Social (including socio-economic).
Socio-economic systems include enterprises, industries, municipalities, regions, etc. The system always reacts to external perturbations and tends to return to a state of equilibrium. However, if under the influence external forces If the system moves far from the equilibrium state, then it can become unstable and not return to the equilibrium state. At a certain point (bifurcation point), the behavior of the system becomes undefined. Sometimes even a slight impact on the system can lead to significant consequences, and then the system passes into a new quality. Moreover, this transition is carried out in leaps and bounds.
A great contribution to the development of systems theory was made by the Russian philosopher and economist A. A. Bogdanov (1873-1928), the author of the work “General Organizational Science (Tectology)”. He developed the foundations of the theory of the structure of systems and substantiated general patterns their development. Bogdanov believed that the subject of study of tektology should be the organizational principles and laws common to all systems - the conscious activity of people, their mental and physical complexes, living and dead nature. When developing the concepts of tectology, Bogdanov expressed a number of new ideas, including the concepts of a control and controlled system, feedback, modeling, later developed by cybernetics and general theory systems, formulated and substantiated the universal law of the physiological expenditure of energy.
Shiroko knows the theory of functional systems developed by P. K. Anokhin, which considers the activity of the organism as a whole as single system. An adapted, properly functioning system is able to reject an extra element, but if any functional part of it fails, then the operation of the system as a whole will be threatened.
Man as a biological being is a system. In addition, as a participant in the production process, he is a component of another system called sociotechnical.
Any system can be considered as a subsystem of some larger system. So, the municipality is a subsystem of the subject of the federation. General features for the allocation of subsystems (parts) in social systems are the following:
Subsystems should be such that they can have a significant impact on the achievement of the final results of the system;
Subsystems must be tied to the whole with the help of certain relations of each part to some general system characteristic (or characteristics) that has the necessary and logical functional connection with the performance of general system tasks;
Subsystems should be appropriately linked to the behavior of all elements of the system and reflect the constant functioning of the mutual relations established for individual elements of the system through its subsystems with the environment.
The subsystem is formed from elements that are the structure-forming part of any system. For example, an enterprise is an element of an industry.
Any social system consists of two independent, but interconnected subsystems: managed and managing. The managed subsystem includes all elements that provide the direct process of creating material and spiritual wealth or providing services. The control subsystem includes all elements that ensure the process of purposeful impact on groups of people and resources of the controlled subsystem. One of the most important elements of the control subsystem is the organizational structure of management.
Communication between the control and managed systems is carried out with the help of information that serves as the basis for the development of managerial decisions and actions coming from the control system to the controlled one for execution.
Any social system is self-governing. At the same time, in the process of management, it experiences external influences. External and internal influences in any system are closely interconnected and mutually determined: the more significant one is, the less the role of the other.
A number of conditions are necessary for the self-organization of the system. Among them, the following are primarily noted: 1) the relative openness of the system, which implies the presence of certain flows into it (human resources, energy, capital, goods, etc.); 2) the presence of an element of randomness (for example, randomness of natural origin, randomness in scientific and technical inventions and the consequences of their application, etc.); 3) non-linearity of the law of interaction of various parts of the social system; 4) the certainty of the range of system parameters that play an important role in the qualitative behavior of the social system, the so-called control parameters. Moreover, if the control parameters have critical points beyond which the behavior of the system changes radically and new types of solutions arise, then such control parameters are called bifurcational. The controlling (bifurcation) parameters of the macroeconomic level can be the coefficients of efficiency of production interaction, some integrated characteristics (for example, the gross national product), etc.
The technical system is a proportional combination of separate technical means from many separate types of various equipment (production capacities of an enterprise, industry, with the help of which people in the process of material production are able to produce products of a given quality in a certain quantity).
The technological system is based on the division of activities, material and spiritual production into stages and processes. For example, lawmaking has such stages as a legislative initiative, discussion of a law, adoption of a law, signing and publication of a law.
The organizational system includes management structures, provisions and instructions, with the help of which they influence the managed subsystem.
The economic system is a unity of economic and financial processes and connections.
Social system - people and their associations created for joint life activity (individual, family, state).
Technical, technological, organizational, economic and social systems are interconnected and create an integral organism.
All organizations are systems. In order to understand how a system performs its function, it is necessary to know how all its elements are interconnected with each other and how it is connected with the system that forms its external environment.
This raises two important questions. How to set system boundaries? What should be considered subsystems corresponding to it? The answers to these questions depend on the purpose of the analysis.
When setting the boundaries of the system, you always have to rely on common sense. The wider the scope of the problem, the wider the system under study and the more variables that need to be taken into account. Thus, the problem of discrimination in employment can be seen as one aspect of a larger problem requiring action in the areas of legislation, education, housing, political rights, and so on. However, this raises the problem of the adequacy of resources for the need to study this larger system. If the resources are not sufficient, then the main goal is divided into sub-goals, which facilitates the approach to solving the main problem. This is achieved due to the fact that the resources released after solving subtasks are directed to solving the main problem.
Systems are divided into natural and artificial. The first are natural, and the second are social, that is, man-made.
Everything that is not included in the system and affects it, or that the system itself affects, is called its external environment.
In addition, systems are either closed or open. A closed system has rigid fixed boundaries, its actions are relatively independent of the environment surrounding the system. It can exist at least for some period of time on its own, without interaction with the environment. For example, hours. Closed physical systems are subject to entropy - the tendency to dry out. In management, closed systems can conditionally include organizations whose management protects their system from information exchange with the external environment (from innovations, education, etc.). Such systems are also subject to exhaustion. There is every reason to believe that one of the main reasons for the collapse of the Soviet model state structure was its closeness from the outside world. Another example of closeness from the outside world today is the DPRK.
An open system (the majority of them) is characterized by interaction with the external environment. Such a system is not self-sustaining, therefore it depends on energy, information, materials, capital, labor resources coming from outside. In the transformation process, the system processes these inputs, converting them into products or services. These products and services are the system's outputs to the environment. If the organization of management is efficient, then the process of transformation creates an added value of inputs, and as a result many possible additional exits, such as profit, sales increase, employee satisfaction, organization growth, etc.
Moreover, an open system has the ability to adapt to changes in the external environment and must do so in order to continue its functioning.
In order for any system to achieve dynamic equilibrium (dynamic homeostasis), it must have feedback - information input that tells whether the system really has a stable state and whether it is subject to destruction. This is the main purpose of systems management. Having received information about its state, the system can also influence the dynamics of material and energy inputs. Therefore, the system must have a block for monitoring inputs, functioning, and outputs, capable of correcting the system's activity based on feedback signals.
Feedback is understood as obtaining information about the results of the influence of the control system on the controlled system by comparing the actual state with the specified (planned) one. The essence of feedback is to establish the dependence of personal, collective and public interests on the results of management decisions.
open systems, and in particular, social ones tend to increase in complexity and differentiation. This in turn leads to a coordination problem. Hence, there is a need to optimize the growth of the system, minimize the levels of the hierarchy and links to each of them, and minimize the reasonable boundaries of the control range.
Systems theory considers a controlled system not autonomously, but in its relationship with the environment and explores methods for adapting the system to changing external conditions.
According to the degree of complexity, the systems are divided into large and complex. Complex systems include those that are built to solve multi-purpose problems.
Managers are mainly engaged in open systems, because all organizations are open systems.
With the help of mathematical modeling, cybernetics and information theory, attempts are currently being made to create a comprehensive theory of management systems, although progress along this path has so far been modest.
Any automatic system consists of separate interconnected structural elements that perform certain functions, which are commonly called elements or means of automation. From the point of view of the functional tasks performed by the elements in the system, they can be divided into perceiving, setting, comparing, transforming, executive and corrective.
Perceiving elements or primary transducers (sensors) measure the controlled quantities of technological processes and convert them from one physical form to another (for example, it converts the temperature difference into thermoEMF).
Setting elements of automation (setting elements) serve to set the required value of the controlled variable Xo. This value should correspond to its actual value. Examples of drivers: mechanical controllers, electrical controllers such as variable resistors, variable inductors and switches.
Comparing elements of automation the set value of the controlled variable X0 is compared with the actual value X. The error signal Δ X = Xo - X obtained at the output of the comparing element is transmitted either through the amplifier or directly to the actuating element.
Transforming elements carry out the necessary signal conversion and its amplification in magnetic, electronic, semiconductor and other amplifiers, when the signal power is insufficient for further use.
Executive elements create control actions on the control object. They change the amount of energy or matter supplied to or removed from the controlled object so that the controlled value corresponds to a given value.
Corrective elements serve to improve the quality of the management process.
In addition to the basic elements in automatic systems, there are also auxiliary, which include switching devices and protection elements, resistors, capacitors and signaling equipment.
All, regardless of their purpose, have a certain set of characteristics and parameters that determine their operational and technological features.
The main of the main characteristics is element static characteristic. It represents the dependence of the output value Xout on the input Xin in the steady state, i.e. Xout \u003d f (Xin). Depending on the influence of the sign of the input value, there are non-reversible (when the sign of the output value remains constant over the entire range of change) and reversible static characteristics (when a change in the sign of the input value leads to a change in the sign of the output value).
Dynamic response is used to evaluate the operation of the element in dynamic mode, i.e. when rapid change input value. It is set by the transient response, transfer function, frequency response. The transient response is the dependence of the output value Хout on time τ: Хout = f (τ) - with an abrupt change in the input signal Хin.
Transfer ratio can be determined by the static characteristic of the element. There are three types of transmission coefficients: static, dynamic (differential) and relative.
Static Gain K st is the ratio of the output value Xout to the input Xin, i.e. Kst \u003d Xout / Xin. The transfer coefficient is sometimes referred to as the transform coefficient. In relation to specific structural elements, the static transmission coefficient is also called the gain (in amplifiers), the reduction factor (in gearboxes), etc.
For elements with a non-linear characteristic, a dynamic (differential) transfer coefficient Kd is used, i.e. Kd =Δ xv /Δ Hvh.
Relative gain The cat is equal to the ratio of the relative change in the output value of the element ΔXout/Xout. n to the relative change in the input value ΔХin/Хin. n,
Cat \u003d (ΔXout / Xout. n) / ΔXin / Xin. n,
where Whoa. n and Khvh. n - nominal values of the output and input quantities. This coefficient is a dimensionless value and is convenient when comparing elements that are different in design and principle of operation.
Sensitivity threshold- the smallest value of the input quantity, at which there is a noticeable change in the output quantity. It is caused by the presence in the structures of friction elements without lubricants, gaps and backlashes in the joints.
A feature of automatic closed systems, which use the principle of control by deviation, is the presence of feedback. Let us consider the principle of feedback operation using the example of a temperature control system for an electric heating furnace. In order to maintain the temperature within the specified limits, the control action applied to the object, i.e. the voltage supplied to the heating elements, is formed taking into account the temperature value.
With the help of a primary temperature transducer, the output of the system is connected to its input. Such a connection, i.e., a channel through which information is transmitted in the opposite direction compared to the control action, is called feedback.
Feedback is positive and negative, rigid and flexible, main and additional.
positive feedback A connection is called when the signs of the feedback action and the master action coincide. Otherwise, the feedback is called negative.
Scheme of the simplest automatic control system: 1 - control object, 2 - main feedback link, 3 - comparison element, 4 - amplifier, 5 - actuator, 6 - feedback element, 7 - corrective element.
If the transmitted effect depends only on the value of the controlled parameter, i.e., does not depend on time, then such a connection is considered rigid. hard feedback operates in both steady state and transient modes. Flexible feedback is called a connection that operates only in the transitional mode. Flexible feedback is characterized by the transmission through it to the input of the first or second derivative of the change in the controlled variable with respect to time. With flexible feedback, an output signal exists only when the controlled variable changes with time.
Home Feedback connects the output of the control system to its input, i.e., connects the controlled value with the master device. The remaining feedbacks are considered additional or local. Additional feedback transmit an impact signal from the output of any link of the system to the input of any previous link. They are used to improve the properties and characteristics of individual elements.
GENERAL CHARACTERISTICS AND CLASSIFICATION OF SYSTEMS
System: Definition and classification
The concept of a system is one of the fundamental ones and is used in various scientific disciplines and spheres of human activity. The well-known phrases "information system", "man-machine system", "economic system", "biological system" and many others illustrate the prevalence of this term in various subject areas.
There are many definitions in the literature of what a “system” is. Despite the differences in wording, they all rely to some extent on the original translation of the Greek word systema - a whole made up of parts, connected. We will use the following rather general definition.
System- a set of objects united by links so that they exist (function) as a single whole, acquiring new properties that these objects do not have separately.
A note about the new properties of the system in this definition is a very important feature of the system, which distinguishes it from a simple collection of unrelated elements. The presence of new properties in a system that are not the sum of the properties of its elements is called emergence (for example, the performance of the "collective" system is not reduced to the sum of the performance of its elements - members of this team).
Objects in systems can be both material and abstract. In the first case, one speaks of material (empirical) systems; in the second - about abstract systems. Abstract systems include theories formal languages, mathematical models, algorithms, etc.
Systems. Principles of consistency
To identify systems in the surrounding world, you can use the following principles of consistency.
The principle of external integrity - isolation systems from the environment. The system interacts with the environment as a whole, its behavior is determined by the state of the environment and the state of the entire system, and not by some separate part of it.
System isolation in the environment has its purpose, i.e. the system is characterized by purpose. Other characteristics of the system in the surrounding world are its input, output and internal state.
The input of an abstract system, for example, some mathematical theory, is the statement of the problem; the output is the result of solving this problem, and the destination will be the class of problems solved within the framework of this theory.
The principle of internal integrity is the stability of links between parts of the system. The state of systems depends not only on the state of its parts - elements, but also on the state of the connections between them. That is why the properties of the system are not reduced to a simple sum of the properties of its elements; those properties appear in the system that are absent from the elements separately.
The presence of stable links between the elements of the system determines its functionality. Violation of these links can lead to the fact that the system will not be able to perform its assigned functions.
The principle of hierarchy - in the system, subsystems can be distinguished, defining for each of them its own input, output, purpose. In turn, the system itself can be seen as part of a larger systems.
Further division of subsystems into parts will lead to the level at which these subsystems are called elements of the original system. Theoretically, the system can be divided into small parts, apparently indefinitely. However, in practice this will lead to the appearance of elements whose connection with the original system, with its functions, will be difficult to grasp. Therefore, an element of the system is considered to be such smaller parts of it that have some qualities inherent in the system itself.
Important in the study, design and development of systems is the concept of its structure. System structure- the totality of its elements and stable links between them. To display the structure of the system, graphic notations (languages), block diagrams are most often used. In this case, as a rule, the representation of the system structure is performed at several levels of detail: first, the system's connections with the external environment are described; then a diagram is drawn with the selection of the largest subsystems, then their own diagrams are built for the subsystems, etc.
Such detailing is the result of a consistent structural analysis of the system. Method structural systems analysis is a subset of system analysis methods in general and is used, in particular, in programming engineering, in the development and implementation of complex information systems. The main idea of structural system analysis is a step-by-step detailing of the studied (simulated) system or process, which begins with a general overview of the object of study, and then involves its consistent refinement.
AT systems approach to the solution of research, design, production and other theoretical and practical problems, the analysis stage together with the synthesis stage form the methodological concept of the solution. In the study (design, development) of systems, at the analysis stage, the initial (developed) system is divided into parts to simplify it and solve the problem sequentially. At the stage of synthesis, the results obtained, individual subsystems are connected together by establishing links between the inputs and outputs of the subsystems.
It is important to note that the split systems into parts will give different results depending on who and for what purpose performs this partitioning. Here we are talking only about such partitions, the synthesis after which allows us to obtain the original or conceived system. These do not include, for example, the "analysis" of the "computer" system with a hammer and chisel. So, for a specialist implementing an automated information system, information links between departments of the enterprise will be important; for a specialist in the supply department - links that display the movement of material resources in the enterprise. The result is a variety of options block diagrams systems that will contain various connections between its elements, reflecting a particular point of view and the purpose of the study.
Performance systems, in which the main thing is the display and study of its relations with the external environment, with external systems, is called a representation at the macro level. The representation of the internal structure of the system is a representation at the micro level.
System classification
Classification systems involves the division of the entire set of systems into different groups - classes that have common features. The classification of systems can be based on various features.
In the most general case, two large classes of systems can be distinguished: abstract (symbolic) and material (empirical).
According to the origin of the system, they are divided on natural systems(created by nature), artificial, as well as systems of mixed origin, in which there are both natural elements and elements made by man. Systems, which are artificial or mixed, are created by man to achieve his goals and needs.
Let's give brief characteristics some general types of systems.
Technical system is an interconnected, interdependent complex of material elements that provide a solution to a certain problem. Such systems include a car, a building, a computer, a radio communication system, etc. A person is not an element of such a system, and the technical system itself belongs to the class of artificial ones.
Technological system- a system of rules, norms that determine the sequence of operations in the production process.
Organizational system in general, it is a set of people (collectives) interconnected by certain relationships in the process of some activity, created and managed by people. Known combinations of "organizational-technical, organizational-technological system" expand the understanding of the organizational system by means and methods professional activity members of organizations.
Other name - organizational and economic the system is used to designate systems (organizations, enterprises) participating in the economic processes of creating, distributing, exchanging material goods.
economic system- a system of productive forces and production relations that develop in the process of production, consumption, distribution of material goods. A more general socio-economic system additionally reflects social ties and elements, including relations between people and teams, working conditions, recreation, etc. Organizational and economic systems operate in the field of production of goods and / or services, i.e. within an economic system. These systems are of the greatest interest as objects of implementation. economic information systems(EIS), which are computerized systems for collecting, storing, processing and disseminating economic information. A private interpretation of the EIS are systems designed to automate the tasks of managing enterprises (organizations).
According to the degree of complexity, simple, complex and very complex (large) systems are distinguished. Simple Systems are characterized by a small number of internal connections and the relative ease of mathematical description. Characteristic for them is the presence of only two possible states of operability: in case of failure of the elements, the system either completely loses its operability (the ability to fulfill its purpose), or continues to perform the specified functions in full.
Complex systems have a branched structure, a wide variety of elements and relationships, and many health states (more than two). These systems lend themselves to mathematical description, as a rule, with the help of complex mathematical relationships (deterministic or probabilistic). Complex systems include almost all modern technical systems (TV, machine, spaceship etc.).
Modern organizational and economic systems (large enterprises, holdings, manufacturing, transport, energy companies) are among the very complex (large) systems. The following features are typical for such systems:
the complexity of the appointment and the variety of functions performed;
large system sizes in terms of the number of elements, their interconnections, inputs and outputs;
a complex hierarchical structure of the system, which makes it possible to single out several levels in it with fairly independent elements at each level, with their own goals for the elements and features of functioning;
the presence of a common goal of the system and, as a result, centralized control, subordination between elements of different levels with their relative autonomy;
the presence in the system of active elements - people and their teams with their own goals (which, generally speaking, may not coincide with the goals of the system itself) and behavior;
the variety of types of relationships between the elements of the system (material, informational, energy connections) and the system with the external environment.
Due to the complexity of the purpose and functioning processes, the construction of adequate mathematical models characterizing the dependencies of output, input and internal parameters for large systems is impossible.
According to the degree of interaction with the external environment, there are open systems and closed systems. A system is called a closed system, any element of which has connections only with the elements of the system itself, i.e. a closed system does not interact with the external environment. Open systems interact with the external environment, exchanging matter, energy, information. All real systems are closely or weakly connected with the external environment and are open.
By the nature of the behavior of the system is divided into deterministic and non-deterministic. Deterministic systems are those systems in which the components interact with each other in a precisely defined way. The behavior and state of such a system can be unambiguously predicted. When non-deterministic systems such an unambiguous prediction cannot be made.
If the behavior of the system obeys probabilistic laws, then it is called probabilistic. In this case, predicting the behavior of the system is performed using probabilistic mathematical models. We can say that probabilistic models are a certain idealization that allows you to describe the behavior of non-deterministic systems. In practice, the classification of a system as deterministic or non-deterministic often depends on the objectives of the study and the details of the consideration of the system.
