Home – Home – Jornals – Avtometriya 2013 number 3

An heuristic method for determining the binarization threshold is proposed which is stably operating for bimodal and unimodal histograms of observed images. A measure based on the skewness and kurtosis of truncated distributions is proposed to choose the threshold. Experimental studies have shown that binarization can be successfully performed regardless of differences in class size.

Bayesian and maximum likelihood algorithms are considered. A comparative analysis of their effectiveness is performed. The results are specified for an image in the shape of an ellipse with linearly varying intensity.

A model of a fractional Brownian process is defined by its structural function with a Hurst exponent α ∈ (0, 1). It is proved that the spectral density of this process exists and coincides with the known power-law relationship only for values of the exponent α ∈ (0, 1/2]. In the range of α ∈ (1/2, 1), the spectral density does not exist and the periodogram estimate of the exponent has a constant value equal to 1/2. The theoretical results were verified by modeling trajectories of the process, calculating periodograms, and estimating the spectral density exponent.

The influence of adaptive bilateral filtration on the calculation of the fractal dimension of optical images is estimated. Filtration parameters are chosen on the basis of various criteria. The use of the maximum dispersion of the probability as the most effective parameter of estimating the image filtration quality is considered.

This paper presents a method for analyzing the fracture kinetics of a sample with multiple defects by calculating the change function of a crack image histogram. A method of automated identification of defect location is developed based on processing photo images of a surface with multiple defects taken at various stages of deformation of the investigated template. Experiments have confirmed that this method can be used to detect cracks whose direction coincides with one of the axes of the image.

A method of modeling a dynamic process on the Earth surface, for instance, a forest fire, with the use of a recurrent neural network is proposed. The learning process of the neural network, similar to the process of data assimilation in GIS technologies, is described. A method of acceleration of neural network learning by using the Kalman filtration is proposed. The efficiency of its application is analyzed, and the neural network parameters at which it is reasonable to use the Kalman filter are determined.

This paper considers the problem of improving the accuracy of time synchronization of sounding acoustic signals and recording of the pulses reflected from the seabed in offshore hydrocarbon exploration. The main method of exploration is continuous seismic profiling (CSP). The method is based on the analysis of the structure of an acoustic signal reflected from geological horizons. In this case, the possibility of resolving thin-layer structures is mainly determined by the accuracy of time synchronization. An instrumental method for increasing the required accuracy is proposed. A feature of this synchronization method is the use of dynamic autocorrection to add time corrections to the main devices of CPS systems, such as navigation, source control, and record control units, after each synchronization cycle with external GPS signals. This approach differs the proposed method from the traditional one. A test model created by this method showed that the guaranteed synchronization error is in the range ± 2 µs, while the technical requirements allow for errors not less than 1000 µs.

This paper presents an instrument designed to study temperature dependences of the small-signal capacitance and current of semiconductor structures in the range from −180 to +300 ºC.

The structure and specific features of operation of microelectromechanical systems, micromirror devices, and diffraction gratings controlled by an electric field are considered. Elements of microelectromechanical diffraction gratings and some applied problems solved with the use of these gratings are described. A new element of the microelectromechanical diffraction grating based on using dielectric materials with a high dielectric permeability in the gap between the electrodes is proposed. As compared with available analogs, this element has a lower control voltage, a higher clock frequency, and better processability. The characteristics of the new element and available analogs are compared.

Silver nanoparticles sprayed onto a crystalline quartz substrate are characterized by means of the low-frequency Raman scattering. Contributions of silver nanoparticles of different sizes to the Raman scattering spectrum are estimated. Data of scanning electron microscopy are used to verify the validity of the results obtained.

The temperature dependence of the intensity of generation of the second harmonic of laser radiation with λ = 1.064 µm in various powders of extra-pure potassium nitrate is studied. The powders are obtained from crystals grown in a KNO₃–Ba(NO₃)₂–H₂O water–salt system. It is demonstrated that the centrosymmetric phase is crystallized from pure solutions. If Ba(NO₃)₂ is added to the solution, non-centrosymmetric phases of KNO₃ or 2KNO₃ · Ba(NO₃)₂ double salt are formed. As the crystals are cooled down from the temperature of 160 ºC, the samples display a ferroelectric phase transition and a hysteresis relaxation dependence of the nonlinear optical response due to the method of sample preparation.

Methods are developed to record and process microimages which are suitable to obtain quantitative information about the fluorescence polarization anisotropy caused by resonance energy transport between green fluorescent protein (GFP)-labeled proteins in a living cell. The methods allow for accurate detection of dimers and higher order associates for GFP-labeled proteins. Protein-protein interaction between subunits of the trimeric GFP protein was recorded. The sources of hardware inaccuracies were found and ways to eliminate them were proposed, which reduced the coefficients of data variation by an order of magnitude in comparison with the previously obtained values.

The efficiency of adaptive correction of turbulent distortions of optical radiation depends on corrector control using information obtained by a wavefront sensor. A wavefront reconstruction algorithm based on analyzing the spatial transformations of the wavefront during passage of the light field through a Shack–Hartmann wavefront sensor and controlling the operation of the system is proposed.

A method for studying the temperature dependence of the effective refractive index of optical waveguides was proposed and tested. The samples were heated using a Peltier thermo-optic module. This technique is simple and easy and improves the measurement accuracy and capabilities of temperature studies of optical waveguides and the materials from which they are made. Obtained dependences can be used to determine the thermo-optic coefficient of film materials. The method was tested on optical waveguides using SiO₂–TiO₂ films produced by sol-gel technology.