The principal differences in formulation and solution to the problems of modeling security and reliability characteristics of information systems are studied. Applicability of the Markov models for the systems security threats based on the characteristics is analyzed. Correctness of the use of Markov processes in modeling the characteristics of information system security and reliability is justified. The necessity of consideration of the system vulnerability threat instead of an attack threat is proved. Models based on Markov processes and enlarged Markov chains for information system security, as well as a formal model of infringer are developed. The models are reported to be of possible use in development of an information system protection means.

A new method of robust controllers design for linear system with delay is developed. The system is supposed to be rude with respect to parametric uncertainty and variation of the delay value; the controllers implement traditional and associated with them control laws. The proposed approach is based on the aperiodic stability criterion and the dynamic compensation method. The transfer function of the controller is determined analytically with the use of the transfer function of the object under the control.

Thermo-optical inhomogeneities in active element of solid-state laser responsible for thermal stress and deformation as well as disturbances in generated radiation are studied. It is proposed to compensate for linear distortion by means of variations in angular and spatial position of opaque mirror in the laser cavity with electro-optical direction regulator. A special feature of the regulator is application of a device designed for control over the mirror position. The device contains a hinged elastic beam with a console bearing the cavity mirror; the beam deformation is performed by a differential screw device of linear movement. Application of the elastic beam makes it possible to correct simultaneously angular and linear position of the mirror with the use of a single transfer origin. An algorithm is developed for the control over the electro-optical direction regulator.

A computer model has been developed to predict temperature drift of sensing elements in fiber-optic gyroscope under external thermal and mechanical actions with the account for the piezo-optic effects. A distinguishing feature of the model is that computation of the stress-strain state of the structure is based on detailed discretization of each turn of the optic fiber in the optic fiber loop. The model is implemented in the framework of the STAR-CCM + software used in combination with a post processor developed by the authors.

Three approaches to the problem of interpolation of color spectrum locus line specified in tabulated form are considered: the first is based on interpolation in the space of color coordinates, the second uses interpolation in the space of chromaticity coordinates, and the third one utilizes interpolation of the spectral locus as some tabular curve having its specific shape. Mathematical relations describing the behavior of spectral gamut in the visible wavelengths range are derived.

A method is developed for calculating stationary temperature values for isothermal space objects of conical and cylindrical shape moving along circular orbits in the plane of the terminator or staying in the Earth shadow. Conditions for thermal similarity of conical and cylindrical objects are studied. It is shown that conical and cylindrical objects with equal relations of the radius of the basis to the height and half-angle at the cone vertex, β not exceeding 10о have equivalent thermal characteristics and close temperature values. Under the conditions, for orbits height of 600 – 40 000 km the temperatures of conical and cylindrical objects are close enough, the difference increases up to 3 K0 and over when β is more than 20о. The temperature of spherical object taken as a reference one is found to coincide with the temperature of conical and cylindrical object at the same conditions only at angles of cone and cylinder axes orientation are α = 40о and α = 140о on a solarconstant orbit at β =13о, and α = 60о and α = 120о correspondingly in the Earth shadow.

Possibilities of increasing reliability of information obtained with the use of automated monitoring and control systems in energy production industry are qnalyzed. The necessity of coupling the procedures of information input from a sensor with message encoding is justified. New principles of coding combining twopulse conditional correlation code first synthesized by the author, with a cyclic code are proposed. The proposed approach is reported to ensure a high level of reliability with the probability of non-detectable distortion in input-output data signals channel of ~10-14 which is 2-3 orders of magnitude better than the regulatory requirements. The developed method makes it possible to diagnose the fault circuit communication with the sensor, i.e., to detect a short circuit or open circuit, simultaneously with the sensor status survey.

The international PolFusion experiment devoted to investigation of nuclear dd-fusion reaction with polarized initial particles is considered. A mathematical model of the polarized source is proposed to simulate high intensity polarized beams using calculation and optimization of the atomic trajectories in high-gradient magnetic fields. A significant achievement of the described model is calculation of three-dimensional trajectories instead of cylindrical two-dimensional calculations used in former models. Basic approaches used in the trajectories calculations are described, results of calculation carried out for ANKE ABS polarized source are presented as an illustration. An advantage of the three-dimensional approach is demonstrated.

Analysis of associated masses of fluid and oscillation frequencies of bellows sensing elements with the account for their specific configuration and number of corrugations is carried out. Mathematical models of bellows sensing elements dynamics in compensatory devices of the type used in control systems applied in viscous environment requiring introduction of associated masses in corresponding dynamic equations are developed. The consideration of the bellows sensing element dynamics is based on the flat sections method; amendment to the spatial flow of the corrugation of the bellows is introduced, and transition to a system with lumped parameters is performed. Correctness and adequacy of the developed mathematical models are confirmed by comparison of calculated values with the data of experiments performed with specially designed test bench to study the associated masses of fluid with various viscosity for a number of bellows sensing elements. It is shown that the developed mathematical models and methods of calculation of associated masses under external flow calls for introduction of a correcting factor depending on the specific configuration of the corrugation of the bellows (toroidal or disc-like).

Approaches to automated profile formation for object of research and educational activity in the information system of the University are presented. The approaches under consideration allows to increase the quality of the sampling used as a base for recommendations system for users of the information system for selection of research manager or a student, research activity, grants, papers, and periodicals for publication of scientific results.