Computer Sciences

Construction of Hierarchies in Multidimensional Data Models

This article considers a method of automated determination of hierarchies in dimensions of multidimensional data model, constructed from the source relational database. Construction of hierarchies is realized on the basis of attribute dependencies of source database.

DDoS Attack Detection Using Fuzzy Neural Network

In this article we analyze SYN Flood type of DDoS attack. We suggest method to detect this attack using a fuzzy neural network. Also we introduce modified back-propagation algorithm for neural network teaching.

About Reconstruction of Small Tournaments

A tournament of order n is a complete graph of n nodes with each arc assigned a unique direction. The reconstruction conjecture in graph theory says that graphs are determined uniquely by their subgraphs. This conjecture was proved to be false when P. K. Stockmeyer discovered several infinite families of counterexample pairs of digraphs (including tournaments). In this paper we observe known results about reconstruction of tournaments and present our approach to study reconstruction of all tournaments with up to 12 vertexes.

A Model for Forecasting Characteristics of Floods Affecting the Value of the Caused Damage

According to GOST (State Standard) characteristics of floods are selected that have influence on the extent of damage. Forecasting of such characteristics will improve the efficiency of liquidation of floods effects. On the basis of formal apparatus of system dynamics that takes into account the casual relationships between modeled variables a mathematical model is developed to forecast characteristics of floods. A graph of cause-effect relations that exist between modeled characteristics is constructed.

Analysis of the Ways of Occurrence and Prevention of Critical Combinations of Events in Man-machine Systems

Models, methods and algorithms are proposed for analyzing the processes of development and preventing critical combinations of events of various kinds that lead to accidents and catastrophes in man-machine and organizational systems. Critical combinations are combinations of events that are individually relatively harmless, but in combination lead to an accident. In technogenic systems, such events are individual operator errors, equipment failures and adverse environmental effects.

The Dynamical Cause-effect Links’ Presentation in Human-machine Systems

A method of presentation variable cause-effect links for modeling processes in dynamic systems is proposed. Such a representation corresponds to the changing conditions that are associated with the action of many diverse factors that accompany the functioning of complex human-machine systems. The presence or absence of a causal relationship between the individual events in the proposed model is defined as a result of a set of stochastic or deterministic functions.

Method for Analysis of Closed Queueing Networks with Discrete Time, Batch Movements of Customers and Dynamic Control of Service Rates

The closed queueing networks with single class of customers, discrete time and batch movements of customers are considered. Queues include multiple identical servers with geometric distribution of service times. A method for dynamic control of service rates in queues is proposed. The control is realized by use of different service rates during fixed time intervals in process of networks operation. When this method is used in queueing networks of considered type, close to given customer allocation among queueing systems is provided.

The Algorithm for Checking Transitivity of Mappings Associated with the Finite State Machines from the Groups ASp

The paper deals with a question of determining the property of transitivity for mappings defined by finite automata. A criterion of transitivity for mappings defined by finite automata on the words of finite length in terms of finite automata and trees of deterministic functions is presented. It is shown that for finite automata from groups ASp an algorithm can be constructed for checking transitivity. To prove this fact some properties of Abelian groups of permutations are used.

Indices of States in Dynamical System of Binary Vectors Associated with Palms Orientations

Dynamical system of binary vectors associated with palms orientations is considered. A tree is called a palm with s + c edges if it is a union of c + 1 paths with common end vertex and all of these paths except perhaps one (with s edges) have a length 1. The system splits into finite subsystems according to the dimension of states. States of a finite dynamical system (B s+c ,γ) are all possible orientations of a given palm with s + c edges.

Adaptive Algorithm of Parametric Synthesis of Hybrid Dynamical Systems

Hybrid dynamical systems (HDS) are connected by means of the boundary conditions and the constraint’s conditions systems of ordinary differential equations and partial differential equations with the corresponding initial conditions. Under the parametric synthesis we understand the algorithm for selecting parameters of feedbacks of controlled HDS, providing the required quality of transients.