One of the modifications of the mathematical models used to describe processes in multi-service communication networks and telecommunication systems is the queueing system with heterogeneous servers. As a rule, for simulation of such processes the system with non-Poisson input flows is used. We consider the queuing system with infinite number of servers of n different types and exponential service time. Incoming flow is a Semi Markovian Process (SM-flow). Investigation of n-dimensional stochastic process characterizing the number of occupied servers of different types is performed using the initial moments method.

Nowadays, a great variety of methods and models are available for software maintenance effort estimation. Each method or model provides desirable results for an appropriate type of software, maintenance technique, and estimated parameters. However, none of them is suitable for estimating databases updating time because of iterative nature of databases life cycle and routine technique for their updating. It is clear that Queueing theory is close to resolve this problem. Unfortunately, it does not meet the requirements of all kind of databases. In particular, it is not useful for critical infrastructure systems with high operational risk and for systems with indeterminate or “unknown” arrival jobs processes, which include nuclear power projects. The article revealed some weaknesses of Queueing theory when using it for nuclear power projects databases and proposed a novel approach based on Network calculus. An example of using the approach for a nuclear power plant instrumentation and control system database is also presented.

We consider an application of power indices, which take into account preferences of agents for coalition formation proposed for an analysis of power distribution in elected bodies to reveal most powerful (central) nodes in networks. These indices take into account the parameters of the nodes in networks, a possibility of group influence from the subset of nodes to single nodes, and intensity of short and long interactions among the nodes.

We consider the problem of reliability assurance of a local ground-based distributed radio direction finding system (RDFS), which consists of a local dispatching center (LDC) and unattended radio terminals (URT), which are up to several hundred kilometers apart from the LDC and are connected to the LDC via communication channels. The performance criteria of the RDFS are defined according to its topology and structure. Requirements on the mean time between failures (MTBF) and the availability factor are imposed. A methodic has been developed for determining the reliability parameters both in approximate analytical form and in the form of a formalized simulation model that takes into account different hierarchy levels of the system from the topology of the network and communication channels to the printed board assemblies and individual types of electronic components. Simulation and calculation of reliability measures was performed using an automated system for reliability calculation of electronic modules and reconfigurable manufacturing calculation (ASONIKA). The weak spots (least reliable elements) of the RDFS have been revealed and recommendations were given to ensure the reliability of individual elements and the RDFS as a whole. The composition of spare parts for LDC, URT equipment and communication channels is proposed.