=Paper= {{Paper |id=Vol-2763/CPT2020_paper_p-2 |storemode=property |title=Application of bionic models for situation management |pdfUrl=https://ceur-ws.org/Vol-2763/CPT2020_paper_p-2.pdf |volume=Vol-2763 |authors=Olga Gerget,Nataliia Markova }} ==Application of bionic models for situation management== https://ceur-ws.org/Vol-2763/CPT2020_paper_p-2.pdf
                 Application of bionic models for situation management
                                                   O.M. Gerget1,2, N.A. Markova1
                                                 gerget@tpu.ru, markovana@tpu.ru
                                          1
                                            Tomsk Polytechnic University, Tomsk, Russia;
                                        2
                                          Siberian State Medical University, Tomsk, Russia

    The article discusses the concept of choosing the sequence of control actions in order to minimize the possibility of the system state
transition to an adverse one. For this purpose, the bionic model based on the synthesis of information approach, neural networks and
a genetic algorithm is developed. The functionality of each of the model elements and their interaction are presented in this paper.
Special attention is paid to neuroevolutionary interaction. At the same time, information about control actions is encapsulated in the
gene, which allowed increasing the functionality of the algorithm due to multidimensional data representation. The article describes
the principle of data representation in bionic models, which differs from the existing ones by the possibility of explicit or implicit
representation of the control action in the chromosome. In the explicit representation one neural network is formed, it describes the
effect of any of the control actions involved in the training. An implicit view creates a set of models, each of which describes the effect
of only one control action. A brief description of the software implemented in the Python programming language is provided.
    Keywords: information approach, neural networks, genetic algorithm, bionic model, choice of control actions.


1. Introduction                                                         2. Information method for calculating the
                                                                           generalized indicator
    The development of information technologies for
monitoring, prediction and situation modeling based on                      The application of the information approach in the
the application of bionic principles is one of the most                 structure of the bionic model makes it possible to
promising scientific directions [1-5]. Evolving over                    evaluate the state of the object of the study at the
millions of years in biosystems, structures have been                   considered moments of time and to reveal deviations
formed, in particular, genetic, immune, neural, providing               from the stationary state. Of interest is the formation of a
balanced development and availability of necessary                      single quantitative indicator [7, 8], which would allow to
information means of control and adaptive control in a                  assess the reaction of the object of the study to changes
changing environment. Attempts are currently being                      taking place under the influence of the internal and
made to integrate artificial information processing                     external environment.
systems that structurally reflect the functioning of                        On the basis of implementation and analysis of
dynamic systems. Particular attention is paid to the                    methods for construction of generalized estimates in the
development       of    models          and methods     that            information system, the approach [9] which considers the
comprehensively take into account the specifics of the                  information measure as a measure of preference of the
object of the study. In the article we will focus on the                behavior of the bioobject is used.
concept of choosing the sequence of control actions in                      The choice is justified by the analysis of the results
order to prevent the transition of the dynamic system to                obtained by:
an adverse state. For this purpose, we will consider the                1. The integral criterion based on the evaluation of
bionic model proposed by the authors [6].                                    similarity measure of observed and preferred state
    By the bionic model we will mean the mathematical                        areas in feature space, where similarity measure is
model, as well as its software implementation, built on                      normalized in Mahalanobis metric by intramultiple
the principle of functioning and organization of                             distance of reference (steady) state area [10].
biosystems.                                                             2. The integral criterion, in the basis of which Kulbak
    In order to implement situation management, namely,                      information measure is considered as a measure of
to choose the best solution, evaluate and predict the effect                 bioobject behavior preference [9, 11].
of the application of control actions it is necessary to                3. The entropy method for detecting body response to
have an adequate mathematical model. This role is                            impact [12].
performed by the bionic model of choosing the sequence
of control actions of the following type:                               3. Prediction of the state of the research object
                     < 𝑁𝑁𝑁𝑁, 𝐺𝐺𝐺𝐺, 𝐼𝐼, 𝐴𝐴 >                                based on bionic models
where 𝑁𝑁𝑁𝑁 - neural network models, 𝐺𝐺𝐺𝐺 - genetic                          Neural networks have been chosen as the basic
algorithms, 𝐼𝐼 - information method for calculating the                 technology in the bionic model structure in order to
generalized indicator of a biosystem, 𝐴𝐴 - model setting                predict the values of features characterizing the state of
algorithms.                                                             the system in dynamics, as well as when choosing a
    Synthesis of information approaches, neural networks                particular control action. This is due to the high
and genetic algorithms in bionic models allows systems                  efficiency of prediction; the possibility of implementing a
to exchange information and transfer the values of their                model ensemble and using recursive neural networks for
characteristics as input to another subsystem which                     a variable structure vector [13, 14].
improves the quality of functioning and interpretability.                   Let us consider an object whose state is characterized
                                                                        by informative features xi … and the ways to influence



Copyright Β© 2020 for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY
4.0)
the state of the object U = (u1,...,ul), where l is the                           object and generalized indicators obtained on the basis of
number of control actions.                                                        the information method.
   It is believed that the value of the i-th feature at a                             The implementation of the prediction algorithms is
point of time t +1 is determined according to the formula:                        based on recurrent neural networks [4, 15, 16], through
   π‘₯π‘₯𝑖𝑖 (𝑑𝑑 + 1) = 𝑓𝑓(π‘₯π‘₯𝑖𝑖 (𝑑𝑑), π‘₯π‘₯𝑖𝑖 (𝑑𝑑 βˆ’ 1), … , π‘₯π‘₯𝑖𝑖 (𝑑𝑑 βˆ’ 𝑛𝑛), … , 𝑒𝑒𝑗𝑗 ).   which it is possible to obtain an accurate identification of
   The problem comes down to solving the task of                                  behavior. The main advantage of using this approach is
predicting the time series. For this purpose, n neural                            the implementation of the "sequence-to-sequence
networks are formed, each of which describes the effect                           learning" idea, namely the input and output vectors are
of only one control action. Each of the neural networks                           not limited in size. You can put a vector of any length at
takes only the vector of indicators of the study object as                        the input and get the corresponding vector at the output.
an input, and the information about the type of the                               It should be noted that by analogy with the concept of
simulated impact is presented in all weights of the model.                        time representation in dynamic neural networks a new
The output of neural networks is the predicted values of                          principle of data representation in bionic models in the
both variables characterizing the state of the research                           form of explicit (Fig. 1) and implicit representation of
                                                                                  control actions (Fig. 2) is proposed in this case.




                                         Fig. 1. Machine learning with explicit representation of control actions




                                         Fig. 2. Machine learning with implicit representation of control actions
    When using an approach with explicit representation               4. Evolutionary approach in bionic model
of control actions, the result of machine learning is the                structure
only model presented (singleton) describing the effect of
                                                                           The application of the evolutionary approach in the
any of the control actions involved in learning. Such a
                                                                      structure of the bionic model has made it possible both to
model takes as input not only the values of the indicators
                                                                      search for the most effective control actions and to
describing the object of the study, but also the logical
                                                                      optimize hyperparameters of the models. In this case,
variables in which the control action is encoded (0 - no
                                                                      control actions are presented in two forms:
impact; 1 - impact is performed).
                                                                      - in case of explicit representation of control actions,
    In implicit representation, the result of machine
                                                                            the chromosome is constructed from genes, each of
learning is a set of models, each describing the effect of
                                                                            which determines the set of control actions applied to
only one control action. Each of the models accepts only
                                                                            the object of study at some point of time;
the vector of indicators of the study object, and the
                                                                      - in case of implicit representation, the chromosome is
information about the type of simulated impact is
                                                                            determined by genes characterizing certain
implicitly presented (i.e. distributed) in all weights of the
                                                                            properties of the model (number of layers, neurons
model.
                                                                            per a layer, short-term memory capacity, degree of
    The need to present information in two types is
                                                                            network connectivity, type of activation function,
justified by the fact that the explicit representation allows
                                                                            type of dynamic network deployment, etc.).
to regulate the "intensity" of the impact, but requires
                                                                           Fig. 3 shows a diagram for the general case where
careful presetting of weights and regularization
                                                                      there are several dependent control actions on the test
coefficients, which would determine the informativity of
                                                                      object at each time point. In this case, each chromosome
the input neurons that take the values describing the
                                                                      involved in the formation of the population is a matrix
control action to the input.
                                                                      (M)ij, where i is the type of action; j is the time point.
    When learning models with implicit representation of
                                                                           Two ways of presenting priori data were reflected
control actions, there is no problem of loss of
                                                                      both in the construction of the chromosome and in the
informativity of input neurons values. Each model
                                                                      defining of criterion function.
contains fewer configurable parameters. However, the
                                                                           With explicit representation, a gene is a vector of
type of impact and its β€œintensity” remain unchanged after
                                                                      logical variables, each of which determines the presence
learning, and a large number of models result in huge
                                                                      or absence of the control action. When the function
investment of time, compared to a model using explicit
                                                                      fitting is calculated, each gene is concatenated with a
representation.
                                                                      vector of values of variables describing the state of the
    The approaches described above are applicable to a
                                                                      study object and it is input to some model. The output
wide class of models, from linear regression to dynamic
                                                                      value of the model by means of a generalized assessment
and deep neural networks. Optimization of deep neural
                                                                      reflects the effectiveness of situation management.
network parameters is a computationally more
complicated task as "layered" architectures contain
combinations of nonlinearities defining a wide range of
learning problems described by the general term β€œdeep
learning”.




    Fig. 3. Chromosome type determined by the way control actions are presented in the model. Note: U = (u(1,) u2,...ul) is a vector of
             control actions; W = (w1,w2,...,wn) is a vector of neural model parameters; T = (t1,t2,...,tΟ„) are the time points
    In the implicit setting of control actions, each gene is   developed which implemented the following procedure
a vector of neural network model parameters describing a       of actions:
certain action. Thus, some "bank" of learnt models is              1. Loading of the table with integral criteria on tic
formed, vectors of weights remain unchanged in the             marks;
course of the evolutionary process, but they participate in        2. Data separation into training and test samples
chromosome formation.                                          according to cross-validation conditions;
    Each gene, since it is a fully functional model, takes a       3. Neural network training in order to obtain a
vector of variables describing the object of the study as      predictive generalized assessment of the state of the study
input, and its output is the predicted value of the            object at the next point of time;
generalized (integral) assessment of the dynamic system            4. Calculation of a prediction error;
state depending on the control action.                             5.    Optimal     selection    of     neural   network
                                                               hyperparameters using a genetic algorithm.
5. Methodological basis for choosing the                           The results of the prototype work made it possible to
   sequence of control actions during situation                assess the accuracy of this approach and to conclude on
   management                                                  the need to develop a software complex based on the
    We summarize and note the functionality of each            chosen algorithms.
element of the bionic model of choosing the sequence of            The prototype was developed in Matlab R2008b.
control actions during situation management.                       Python, a high-level programming language relating
    Let us have a database that stores the values of the       to freely distributed software, has been chosen as the
properties of the study objects at the following moments       main development tool.
of time: prior and after some control action is applied.            The program on Python consists of a main module
    1. For each object at each moment of time, we              and secondary modules that can be connected when
calculate the values of the generalized indicator and          running the main module code. Secondary modules are:
evaluate their deviations from the norm.                           β€’ NumPy - data interpolation, statistical functions,
    2. The control action on each object is modeled by a       optimized calculations;
neural network. As input data, values of variables                 β€’ Pandas - dataframe, loading and saving *.csv-files;
characterizing the state of the research object before             β€’ PyBrain - artificial neural networks, optimization
applying the control action are used. As the desired           methods, including genetic algorithm;
responses, both the variable values and the generalized            β€’ PyQt – components of the graphic interface.
indicator (I) values are used after the control action is          The selected tools allow you to move from the stage
applied. The objective function to be minimized is             of prototype development to the implementation of the
defined as the deviation of the generalized indicator from     finished software project quite quickly.
the norm.                                                          The whole process will be divided into several stages:
    3. The obtained set of neural network models forms a       collection of primary data and secondary data obtained
plurality of genes that can be specified by a vector of        from the results of additional studies. After the
neural network parameters (for an implicit form of             calculation of integral indicators based on the
control action) and a vector of logical variables in which     information approach, a graph of changes in the state of
the control action is encoded (in an explicit form).           the research object in time is displayed. The cubic spline
    4. The sequence of control actions is determined by        interpolates the data and calculates the rate of change of
known previous states (state variables) and predicted          the variables characterizing the state of the research
values of object state variables using genetic algorithm.      object.
In the process of genetic algorithm work the request to            Further, the calculation of predicted values of each of
neural networks for obtaining the predicted values of the      the indicators is performed separately, and a predicted
object state for all future time intervals is performed.       integrated assessment of the state during the situation
    5. The genetic algorithm forms and chooses new             control period is given. The deviations between the
generation by means of selection, crossover and                prediction and the stationary (normal) values at each time
mutation.                                                      point are determined and displayed on the graph. A
    6. The values of the fitting function of the genetic       sequence of control actions at which deviation is minimal
algorithm are determined as deviations (from the norm)         is formed.
of the value of the generalized indicator predicted by the
                                                               7. Results
neural network (by a gene). Among the set of control
actions, defined by chromosomes, the one at which the              Development and testing of the bionic model, which
value of the fitting function will be minimal is chosen        is based on the interaction of the information method,
(the range is set [0,1; 1]).                                   genetic algorithm and neural networks, allow for
                                                               situation control based on correct choice of the sequence
6. Software implementation                                     of control actions. The information method forms a
    At the first stage of development of information           single integral indicator characterizing the state of the
system in order to test the possibility of using artificial    object of the study. Artificial neural networks enable to
neural networks for predicting the state of dynamic            obtain prediction of integral assessment of the object
systems (the object of the study) a prototype was              state depending on the chosen control actions. The
genetic algorithm chooses a sequence of control actions        [8] Alifirova V.M., Brasovsky K.S., Zhukova I.A.,
that reduce the possibility of transition to adverse states.        Pecker J.S., Tolmachev I.V., Fokin V.A. Method of
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presented in the article differs from the existing ones by          Bulletin of Experimental Biology and Medicine,
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