The aim of the thesis is to increase the efficiency and reduce the risks of information transfer in the information and communication networks (ICN) of critical infrastructure systems (CIS) by developing information technologies, the models of structures and methods for the risk-adaptive management of the data flow parameters of the CIS ICN. The object of the research is the processes of managing the information and communication networks of critical infrastructure systems. The methods of research are the fundamentals of theories - the set-theoretical approach, the methods of the queuing theory, optimization models and the methods of operation research, the methods of the information theory and the theory of complex systems, the methods of functional analysis, the methods of mathematical statistics. The scientific novelty of the thesis is based on the fact that the work for the first time deals with 1) the methodology of the risk-adaptive management of ICN data flows, which unlike the existing ones, implements the structural and parametric synthesis of the information and technical component, the adaptive traffic management taking into account the assignment of applied tasks to the network nodes and two-loop risk management, which will ensure the operation of ICN that is adaptive to external conditions and resistant to risks; 2) the mathematical model of the data flows of the multilevel information structure of the network which, unlike the available ones, has a three-level non-stratified structure and consists of a number of subnets and groups of nodes that enable determining the parameters of data flows among the nodes in a group as well as among subnets for calculating the characteristics of the load of communication channels and the network equipment of CIS ICN; 3) the method of ICN structure development, which, unlike the existing ones, involves the synthesis of the hierarchy of structures and the formalization of selection tasks on the basis of set-theoretical models, enables increasing the efficiency of using the information and technical resources of the network; 4) the method of the adaptive management of the assignment of information data flows, which, unlike the existing ones, takes into account probable types of communication channels, a possible change in the requirements of application tasks or the activity of a user and enables reducing the total cost of maintenance; 5) the method of ICN risk assessment, which, unlike the existing ones, identifies partial risks with the help of the cognitive maps and the cause-effect diagram of the factors, risks and their consequences, which increases the accuracy of the quantitative assessment of possible damage to the functioning of the network by better accounting for its causes. The following items were improved: 1) the method of determining the parameters of the data flows of the network information structure by metering the amount of data among the network nodes while performing both applied tasks and system applications by a number of users and calculating the intensity of data flows among users and nodes enables differentiating the data flows of each CIS task; 2) the mathematical model of the ICN technical structure by calculating the parameters of the network data flows according to the information structure enables assessing the impact of each system application on the load of communication channels and communication equipment of the network; 3) the model of the assignment of applied tasks to the nodes of the information and communication network by determining the objective function for minimizing both computational and data transfer costs and restrictions caused by the requirements of the technical and information structures of the network; 4) the method for assigning the resources of a multi-server node of information processing by examining the system of servers as a set of single-line queuing systems and by using information on the distribution of the bandwidth of communication channels, thereby reducing the cost of flow maintenance. The following item were further developed: the models for assessing the ICN quality and efficiency by determining the general criterion for the quality of the network structure and the criterion for the data transmission that take into account the characteristics of processing information messages, which enables simulating the data transfer processes in a more adequate way and ensuring more efficient ICN operation without allocating redundant resources.
