Home – Home – Jornals – Avtometriya 2014 number 4

This paper presents the results of experimental studies and numerical calculations of weather-dependent ecological risks to social infrastructure facilities from the effects of powerful infrasonic vibrations generated by man-made and natural explosions. The results were obtained by applying an original ecologically safe approach developed by the authors and involving the use of seismic vibrators as sources simulating explosions but having much less power compared to the explosions. Such sources generate both seismic and acoustic (seismoacoustic) vibrations with precision metrological power and frequency-time characteristics, which, in contrast to explosions, ensures high reproducibility of research results. Results comparable to explosions are achieved due to the energy accumulation of weak vibroseismoacoustic signals. The propagation of infralow-frequency wave fields is studied depending on weather conditions and taking into account the effect of heterogeneity of the atmosphere. The results of the experiments are compared with those of numerical calculations.

Synthesis methods based on spatial-frequency filtering have been developed for fractal images for which the structure functions are power laws over a wide range of increments which is about one-quarter of the image size. It is shown that, using theWeierstrass function, only stationary processes (images) can be simulated. An algorithm for modeling fractional Brownian images is proposed and studied. It is established that the integral characteristic of the spectrum of a Brownian image with the Hurst parameter α is well approximated by a power function with an exponent 2(α + 1) for α ∈ (0, 1/2] and an exponent of 3 for α ∈ (1/2, 1). Using as an examples modifications of images of samples of amorphous alloys, it is shown that statistically self-similarity images little different from the original image can be simulated. This allows one to determine to what extent the structures visualized in the images exhibit fractal properties.

Well-known and original methods of spectral filtering of the seismic noise occurring in hydraulic fracturing have been studied and applied. They allow control of artificial noise and natural interference due to the nonlinear propagation of seismic signals and the resonance properties of the reservoir rock. Original spatial filtering is applied to eliminate the redundancy of location data. A threedimensional model for the reservoir fracture zone formed by hydraulic fracturing is proposed.

An approach is proposed to design transfer functions with prescribed direct measures of transient performance: overshoot and setting time. A technique for designing such functions is developed. A numerical example is given.

Digital identification and evaluation of the kinetics of damage accumulation on the surface of a fatigue sensor are performed using digital image processing. Damage accumulation is evaluated from the results of diagnosis of individual stages of cyclic deformation. It is found that the different stages of damage correspond to particular image parameters. The main features in the development of shear processes were identified by consistent processing of surface damage data. Theoretical background and experimental results are presented.

One way to increase the reliable and robust operation of large-scale computing systems is to introduce a reserve (a structural redundancy system) to them. A model for the analysis of the operation of distributed computing systems is proposed. The results of analytical and simulation modeling are presented. Flows of events with a Weibull distribution (shape parameter values of 1 and 0.78) are considered.

Results of computational experiments aimed at studying the accuracy characteristics of interchannel gradient reconstruction of signals of color digital images distorted by impulse noise with different brightness distribution laws, which are not correlated between the channels, are generalized. Examples of interchannel reconstruction of color digital images on the basis of different sets of gradient estimates are presented.

A signal processing algorithm for a passive seismic monitoring system is proposed and experimentally verified. This algorithm ensures effective detection and determination of the trajectory of a moving object. A concentrated receiver consisting of two geophones separated by a distance much smaller than the detected signal wavelength is used in experiments. Processing of experimental results shows that it is possible to determine not only the position of the seismically active object, but also the parameters of its motion.

A new method of decomposition of the interval of the values of random variables based on results of optimization of the nonparametric estimate of the probability density of the Rosenblatt-Parzen type is proposed. Its application in the problem of testing the hypothesis of identity of the distribution laws of two sequences of one-dimensional random variables is considered.

Various approaches to estimation and suppression of a motionless background with the use of texture correlations in the problem of detection of small-size dynamic targets are considered. Algorithms of suppression of a locally flat background, background suppression by means of bilateral filtration, and an algorithm of background estimation and suppression with the use of an autocorrelation function are implemented. For anisotropic textures with boundary transitions, an algorithm of background estimation and suppression along the boundary and an algorithm of three-channel filtration are proposed and implemented. Operation of these algorithms on textures representing different classes of images is compared. It is demonstrated that the algorithm with background estimation along the boundaries yields good results for model data with a large number of linear boundaries, but its operation on mixed-type textures is less efficient than that of other available approaches. Among the considered algorithms, the approach based on three-channel filtration ensures the greatest increase in the signal/noise ratio for various textures modeling real images.

A software system is presented for implementation of a fire model on the basis of a recurrent neural network, which ensures real-time simulation of fire evolution. The quality of traditional learning and learning based on the Kalman filter in experiments performed with the neural network is compared. It is demonstrated that the fire overcomes obstacles in the form of regions consisting of incombustible materials owing to the global character of connections of the neural network simulating the fire.

A method of calculating the range of operation of thermal imaging systems during detection, classification, recognition, and identification of objects is considered. The method is based on finding the functional relationship of the sought quantities with the threshold temperature sensitivity and the temperature-frequency characteristic of thermal imaging systems in the cases of tracking objects in homogeneous and non-homogeneous fields of thermal radiation.

A groove coated with a layer of indium that fills the groove during its formation is generated on the lower surface of sapphire in a single process under the action of laser pulses. The process is performed by using a pulsed gas laser with a wavelength of 0.337 µm. The laser beam is focused through sapphire onto a surface coated with indium. The sapphire motion velocity is uniform, and the sapphire displacement during the time between two pulses is 10% of the light spot diameter. The groove is formed by using the scanning mode (multiple passes of laser radiation through the groove). The pulse energy density in a single pass is sufficiently large. The process is carried out in air. It is found that the optimal option is two passes when the specific resistance of indium in the groove is only 3.8 times greater than the resistance of pure (99.999%) indium bars.

A method for measuring the concentration of a biomarker (acetone in human’s breath), which is based on the use of glow-discharge emission spectroscopy in air is proposed for the purpose of noninvasive glucose monitoring in diabetes patients’ blood. The experimental setup and measurement techniques are described, and preliminary results of clinical trials of the developed system under ambulatory conditions are presented.

Circle diagrams for the complex amplitude reflection coefficient are used for the development of a multilayer mirror, which includes a thin metal film. The proposed method allows calculating the asymmetrical front mirror of a two-mirror multiple-beam reflected light interferometer, which generates an interference pattern in the form of symmetrical narrow light bands.

The structure of a GaInP/GaAs/Ge triple-junction solar cell (SC) with an integrated Bragg reflector (BR) is optimized, resulting in reduction of losses of transmitted (reflected) radiation in tunnel diode layers. The optimized structure of the SC with a BR is obtained by means of metalorganic chemical vapor deposition. 20 × 30-mm SC samples are manufactured. The samples of SCs with and without BRs are tested under the action of electron fluxes with the energies of 1 MeV. It is shown that the SC radiation resistance can be increased by integrating a Bragg reflector into the SC structure and decreasing the thickness of the middle p–n junction base.