CONSTRUCTION OF CONCEPTUAL MODELS OF SYSTEMS AND THEIR FORMALIZATION, Transition from description to block model. - Modeling of systems


At the first stage of computer modeling - the construction of the conceptual model M r of the system 5 and its formalization - the model is formulated and its formal scheme is constructed, ie, the main purpose of this stage is the transition from a meaningful description of the object to its mathematical model, in other words, the process of formalization. Modeling of computer systems at the present time is the most universal and effective method for evaluating the characteristics of large systems. The most responsible and least formalized moments in this work are the boundary between the system 5 and the external environment & pound; the simplification of the description of the system and the construction of the conceptual and then formal model of the system. The model should be adequate, otherwise it is impossible to obtain positive results of modeling, that is, the study of the process of functioning of the system on an inadequate model in general loses its meaning. An adequate model will be understood as a model that, with a certain degree of approximation at the understanding level of the modeled system, the developer of the model reflects the process of its functioning in the external environment.

Go from description to block model.

The most rational way to build a model of the system by block principle. In this case, three autonomous groups of blocks of this model can be distinguished. The blocks of the first group are a simulator of the environmental effects E on the system 5; blocks of the second group are actually a model of the process of functioning of the system under study; blocks of the third group are auxiliary ones and serve for machine realization of blocks of the first two groups, as well as for fixing and processing the simulation results.

Let's consider the mechanism of transition from the description of the process of functioning of some hypothetical system to the model of this process [29, 351. For clarity, we introduce the idea of ​​describing the properties of the process of functioning of system 5, ie, its conceptual model M x as a collection of some elements, conditionally represented by squares as shown in Fig. 3.2, a. These squares represent a description of some subprocesses of the process of operation of system 5, E , etc. The transition from description of the system to its model in this interpretation is reduced to excluding from consideration of some secondary elements of the description (elements 5 - 8.39 - 41.43 - 47). It is assumed that they do not have a significant effect on the course of the processes investigated using the model. A part of the elements (14, 15, 28, 29, 42) is replaced by passive links A A , reflecting the internal properties of the system (Figure 3.2, 6). i> Some of the elements (1 - 4, 10, 11, 24, 25) are replaced by the input factors x and the external environment 1 . Combinations are also possible: the elements 9, 18, 19, 32, 33 are replaced by the passive AND 2 Elements 22, 23,36, 37 reflect the effect of the system on the external environment y.

The remaining elements of system 5 are grouped into blocks 51, 5 П , 5 Ш , reflecting the process of functioning of the system under study. Each of these blocks is sufficiently autonomous, which is expressed in the minimal number of connections between them. The behavior of these blocks should be well studied and for each of them a mathematical model is constructed, which in turn can contain a number of subblocks. The constructed block model of the process of functioning of the system 5 being investigated is intended for analysis of the characteristics of this process, which can be carried out with the machine realization of the model obtained.

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