Home – Home – Jornals – Avtometriya 2016 number 2

This paper describes the control of computations in a distributed computing environment (DCE) on the basis of its meta-monitoring and simulation modeling. Computations are controlled by a multiagent system with a given organizational structure. Resource allocation is carried out by agents with the use of economic mechanisms for controlling their supply and demand. Controlling actions for agents are formed on the basis of the simulation modeling of functional processes of the DCE. Data about the DCE resources and processes are collected and emergency situations in the DCE nodes are detected and prevented by the meta-monitoring system of this environment. The research results are the techniques for selecting control actions and the methods for intellectual processing and effective storage of data.

The efficiency of detecting point objects in images obtained by a photodetector array is analyzed. It is shown that the detection efficiency depends both on the image processing method and on the relationship between the sizes of the array elements, the gaps between these elements, and the point spread function of the optical system forming the image. Results of a computational experiment are given, which confirm the existence of an optimal relationship between these parameters.

A novel approach is proposed for solving probability problems arising in studying reliability of readout of random point structures. The essence of this approach is based on combining specialized program-analytical and discrete-combinatorial methods of research seldom used in academic practice. The efficiency of the proposed approach is demonstrated by an example of solving a particular problem that involves two-threshold readout of random point images.

This paper describes a set of tests for uniformity of observations which are ranked by power. It is shown that most tests commonly used for the hypothesis of uniformity are biased relative to a certain kind of competing hypotheses. It is emphasized that specific tests meant only for uniformity have no obvious advantages over nonparametric goodness-of-fit tests used for the same purpose.

This paper describes the problem of passive identification of heat equation coefficients with account for the noise of the behavior of the object dynamics model and for the noise of the measuring system model. The use of the finite difference method allowed for reducing the solution of partial differential equations to the solution of a system of linear finite-difference and algebraic equations described by models in the form of a state space. Presentation of the heat equation in form of such a model makes it possible to apply the Kalman filter algorithm for the reliable estimation of the behavior of the object under study.

The kinetics of mirrors with saturable absorption is investigated by a pump-probe singlefrequency technique in reflection of femtosecond pulse radiation with the central wavelength of 1040 nm. The double modulation method with probe radiation detection at the summary frequency allows suppressing the scattered pump radiation contribution and reaching the reflection change sensitivity at a level of 10^-5. The kinetics of recovery of the linear reflectivity of the mirror including resonant quantum wells with nanostructured barriers is studied for the surface density of photons in pump pulses of (0.3-5.8) x 10¹⁴ cm^-2. The time of electron-hole recombination (7.8 ps) is found to be appreciably shorter than in samples with quantum wells separated by thick barriers; the time of ionization of excitons localized in quantum wells (0.2-0.4 ps) increases with the pump intensity.

A two-beam interferometer based on a beam-splitter cube with a fixed photosensitive element is proposed. The interferometer is designed for generating interference patterns with a tunable period. The only type of motion resulting in a change in the period is interferometer rotation with respect to the source of the light beam. The greatest width of the range of convergence angle tuning is close to 50°, and possible values of this angle lie in the interval from 10 to 180°. The interferometer arms have identical lengths owing to its symmetry. The absence of adjustment elements ensures high stability of the instrument with respect to vibrations.

The interaction of a cold vortex ring with flame in an axisymmetric configuration has been investigated using methods of Hilbert optics, shearing interferometry, and numerical simulation. The impact of a cold vortex ring formed by a pressure pulse from the annular area surrounding the source on the flame has been numerically simulated. The modes of breakup of the flame structure, blow-off, and quenching under various conditions of vortex ring formation were identified. It is shown that in the case of both complete and partial quenching, most of the flame is blown off. However, in the case of incomplete quenching of the flame, in its lower part there is a small combustion zone, which then grows back to the previous size.

Investigations of the defect structure of a gradient-activated stoichiometric LiNbO₃:Mg²⁺, Cr³⁺ crystal, in which the chromium concentration has a constant value of 0.1 at. % along the crystal growth axis, and the magnesium concentration changes smoothly from 5.5 to 2.0 al. %. The threshold concentration of Mg²⁺ ions (2.35 at. %) in these crystals with a concentration width of change in the center composition (Cr optical center and its nearest neighbors) of 0.09 at. % Mg²⁺ ions is established.

The transformation of zero-order Bessel beams to a second-order Bessel vortex beam in a c-cut CaCO₃ crystal has been studied experimentally. It has been shown that it is possible to control the beam transformation in the crystal during heating. The influence of the thermo-optic effect and the linear thermal expansion of the crystal on the transformation of the Bessel beam is explained.

Optical (refractive index and absorption coefficient) and thermo-optical (linear thermal expansion and thermo-optic coefficients) characteristics of a new hybrid organic-inorganic photopolymer material "Hybrimer-TATS" based on thiol-siloxane and tetraacrylate oligomers are studied. Variation of the ratio of initial components makes it possible to change the thermo-optic coefficient from -0.7 x 10^-4 to 0,66 x 10^-4 K^-1, which offers prospects for synthesizing athermal optical components and optical elements with a high sensitivity to temperature variation for thermal sensors.

The architecture, composition, specific features of operation, and technical characteristics of an automated control system of the Large Solar Vacuum Telescope of the Baikal astrophysical observatory are considered. The system is used for automation of both the observation process (automatic telescope guiding to the Sun, selection of a needed region in the solar disk image, guiding based on prescribed coordinates, and video monitoring of the basic subsystems of the telescope) and the auxiliary operations (evacuation, siderostat mirror unloading, and dome control).

The problem of controller design for nonlinear multi-channel dynamical plants is discussed. Trajectory motion tracking control for a multilink manipulator is treated as an example of the proposed design methodology. A distinctive feature of the discussed approach to calculate controller parameters is that two-time-scale motions are artificially forced in a closed-loop system where stability of the fast mode is provided by selection of the controller parameters while the induced slow mode correspond to the reference model of desired nonlinear plant behavior. Simulation results for a two-link manipulator robot manipulator tracking control system are presented.

Mosaic focal plane arrays (MFPAs) have been designed, and a number of addressing schemes reducing the blind zone have been proposed. A precision technology for fabricating MFPAs with a total size of the blind zone of not more than 30 μm has been developed. Certain systemic issues of applying MFPAs are discussed. The designed 3072 x 576 uncooled microbolometer MFPAs based on 384 x 288 submodules with a pixel pitch of 17-51 μm provide ~99 % image conversion efficiency in the infrared range and those with a pixel pitch of 100 μm provide 100 % image conversion efficiency in the terahertz range.

The possibility of designing a micro-opto-electro-mechanical (MOEM) angular velocity transducer based on the optical tunneling effect is discussed. A MOEM transducer model has been developed. Dependences of the output optical power and output voltage on angular velocity have been obtained. The effective measurement range of angular velocities that provides quasilinearity of the transfer function has been determined. The effects of the design parameters of the sensitive element and temperature on the performance of the transducer are analyzed.