Changes in operating conditions or monitoring tools reduces the effectiveness of existing options for implementing networks and requires their reengineering. To ensure the effectiveness of design solutions, it is proposed to jointly solve the problems of structural, topological, parametric and technological optimization of system networks in terms of a variety of indicators. The basic formulation of the problem of reengineering of the topological structures of centralized three-level ground networks has been determined, for which a set of feasible solutions and estimates of indicators of costs, efficiency, reliability and survivability are formalized. Taking into account the fact that the cardinalities of the sets of admissible functioning technologies, parameters of elements and connections of networks are insignificant, the main difficulties are in solving problems of optimizing their topological structures. Such problems are solved with a variety of functional and cost indicators, taking into account numerous restrictions. The proposed universal functions for scalar estimation of options more accurately describe the preferences of the decision-maker and reduce the time complexity of the estimation procedures. Mathematical relationships were obtained to assess options for building centralized three-level networks in terms of costs, efficiency, reliability and survivability. Their use makes it possible to carry out scalar evaluations of alternative options in automatic mode. The proposed options evaluation functions more accurately describe the benefits of the design decision maker and allow reducing the time complexity of the evaluation procedures. optimization. Environmental monitoring network, structure, topology, reengineering, multi criteria development ISIT 2021: II International Scientific and Practical Conference CEUR Workshop Proceedings (CEUR-WS.org)
carried objects out safe technogenic society requires a
modern
systematic
observations, control, assessment of
human
impact on the environment, carried out by the
systems of integrated environmental monitoring
[
systems is using networks with different structures depending on the characteristics of the control.
The improvement of
2021 Copyright for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0). technologies for collecting, transmitting and processing data opens up new prospects for the development inexpensive of
monitoring data loggers are
networks:
increasingly
used [
Changes in operating conditions (requirements for reliability, observations, efficiency
and
number
of
accuracy
objects
of
of
observation) or monitoring tools (improvement of
technologies
processing,
storing
and
the
for
transmitting information) reduces the
effectiveness of existing options for implementing
networks and requires their reengineering. The
process of monitoring networks reengineering is
carried out based on the results of solving a
complex of combinatorial problems of optimizing
their structures, topologies, parameters of
elements and channels of information
transmission, selection of technologies for
collecting, transmitting and processing
information [
Taking into account the fact that the
cardinalities of the sets of admissible functioning
technologies, parameters of elements and
connections of networks are insignificant, the
main difficulties are in solving problems of
optimizing their topological structures. Such
problems are solved with a variety of functional
and cost indicators, taking into account numerous
restrictions. This requires the use of modern
models and methods to support the adoption of
multi-criteria decisions [
Despite numerous publications devoted to
solving the problems of reengineering the
topological structures of ground-based
environmental monitoring networks, a
contradiction was revealed between the need to
increase the efficiency of existing options for their
implementation and the limitations of
mathematical models of multi criteria problems of
their optimization. In particular, it is necessary to
improve the adequacy of models for assessing
functional and expenditure indicators,
preferences, decision-makers, and scalar
multicriteria assessment models for building networks
[
The aim of the study is to increase the efficiency of technologies for computer-aided design of ground-based environmental monitoring networks through the development of mathematical models of multi criteria problems of reengineering of their topological structures.
As the scale of monitoring systems grows, their cost and functional characteristics become more and more dependent on the topology of the (territorial) organization. As a result, it becomes necessary to solve topological optimization problems together with traditional problems of structural synthesis. This gives rise to the problem of structural-functional-parametric and topological synthesis.
Each of the options for building the system will be presented in the form of a tuple:
s E,R,G , (1) where E is the set of system elements; R - set of direct connections between the elements; G - set of locations of elements.
Each of the options for the structure of the monitoring system E,R can have different topologies G G* (where G* is the set of allowable locations of system elements).
Each of the options for building a system (1) will correspond to its own set of functional and cost indicators:
P ( E,R,G ) , (2) where is some reflection .
As a result of decomposition of the problem
for the reengineering of ground-based
environmental monitoring networks as
territorially distributed objects at the lower level,
the following tasks are identified Taski , i 1,6
[
Formally, each of the tasks will be presented in the form of a converter of its input data Ini in its original data Outi :
Taski : Ini Outi , i 1,6 .
Models of all tasks of the reengineering problem will be presented in the form:
ModТaski : InDatiE , InDatiI , Resi where InDatiE is the set of external input data; InDatiI - a set of internal input data; Resi - many restrictions; DesDeci - task solving.
After choosing the principles of construction
Task1 and the technology of functioning Task4 ,
the task of reengineering the topological
DesDeci , i
1, 6 ,
(3)
structures of three-level centralized monitoring
networks is considered in this formulation [
Specified: a set of elements of the existing network I { i } , i 1,n , which cover the entire set of monitoring objects; the existing version of the topological structure s S (where S is the set of admissible options), which is given by the locations of elements, nodes, center (the center is located at the base of the element i = 1 ), as well as links between elements, nodes and the center [sij ] , i, j 1,n (where sij 1 , if there is a direct connection between elements i and j - and sij 0
otherwise); the cost of creating or upgrading nodes [ci ] , [di ] , i = 1,n and links [cij ] , [dij ] i 1,n .
It is necessary to determine the best variant of the so S . network topological structure in terms of costs, efficiency (time of obtaining information), reliability and survivability.
The set of acceptable options for building a centralized three-level network is set by the conditions: where τC , τ E is the time for the center to issue a request and receive information on the monitoring object by the element; , is the amount of information in the request and the response to the request; γ1 , γ2 are capacities of communication channels "center-node" and "node-element"; h1, h2 is speed of request and response processing in network nodes.
We use the coefficient of the network availability as an indicator of its reliability, δCU u × δUE n k3 (s) = δC × δU u × δ E n × max sS
Each of the network reengineering options is set by the number of nodes u, in it, their locations and the scheme of connections between elements, nodes and the center [sij ] , i, j 1,n . It is considered that: the entire set of monitoring objects is controlled with a given frequency; nodes of the network are placed exclusively on the basis of elements; the elements are connected to the nodes in terms of the minimum cost (distance), the volume of requests to each element of the network is equal to α = [αi ], αi = const , i 1,n ; the volume of responses from each of the elements is equal to β = [βi ], βi = const , i 1,n .
k2(s) = τC +
+ τ E + α γ1 β γ2 + α γ1 + α h1 +
+ β h2
n β γ2 j=1 l= j n s jl s jj min, s S n n
i=1
Let us simplify the target function of the costs
of network reengineering [
[ci (1 - sii ) sii + di sii sii ] + + [cij (1 - sij ) sij + dij sij sij ] min.
j=1 i= j s S
The criterion of efficiency, which corresponds to minimizing the maximum time for obtaining monitoring data, can be presented in the following form: (4) (5) (6) (7) where δC , δU , δ E , δCU , δUE are availability factors of communication the
center, channels
node, element, "center-node" and n "node-element"; n , u = sii is the number of i=1 elements and nodes in the network.
We use the value of the proportion of elements
connected to the center in an operable network
with single damage to its components as an
indicator of survivability k4 (s) . In this case,
regardless of the type of network structure, when
the center is damaged k4 (s)
0 , and when one
element or one communication channel
"nodeelement" is damaged k4 (s)
(n
1) / n .With
this in mind, the criterion of maximizing the
survivability of the network will take into account
only the damage of the connections
"centernode", "node-element" and nodes:
k4 (s) =
min
1 j n
n
n n
j=2 i= j s jisii / n
max . (8)
s S
process of network optimization. Scalar
multifactor assessment models are used to select a
subset of the most effective options and the best
among them for building an environmental
monitoring network [
To determine the scalar estimates of the quality
of variants, we use the apparatus of utility theory
[
v P( s ) P( v ) ; s v P( s ) P( v ) .
It is proposed to establish the value of scalar
estimates for the quality of options based on the
generalized utility function built on the basis of
the Kolmogorov-Gabor polynomial [
The generalized utility function (9) makes it
possible to describe any consistent advantages of
the decision maker. Function (10) is the best in
terms of the "accuracy-complexity" complex
indicator among the common utility functions of
particular criteria [
Based on the results of the analysis of the current state of the problem, it was found that changes in requirements, operating conditions, the development of technical means and information technologies lead to the need for reengineering of existing environmental monitoring networks. To ensure the effectiveness of design solutions, it is advisable to solve jointly combinatorial problems of structural and topological optimization of networks with a variety of functional and cost indicators. Mathematical relationships were obtained to assess options for building centralized three-level networks in terms of costs, efficiency, reliability and survivability. Their use makes it possible to carry out scalar evaluations of alternative options in automatic mode. The proposed options evaluation functions more accurately describe the benefits of the design decision maker and allow reducing the time complexity of the evaluation procedures. The direction of further research can consist in accounting of the uncertainty of the functional and cost characteristics of networks in models of the problem using the apparatus of fuzzy or interval analysis and the decoupling of effective methods for optimizing networks with a variety of indicators.
Areas of further research of this problem may
be taking into account in the models of uncertainty
of functional and cost characteristics of
monitoring systems using the apparatus of
interval analysis or fuzzy mathematics [