Home – Home – Jornals – Avtometriya 2015 number 3

The problem of constructing a semi-parametric spline regression model is considered. A new model of penalty splines with variable penalty coefficients is proposed. In the model, it is assumed that the coordinates of the basis points are determined by solving the optimization problem of minimizing the residual sum of squares. The choice of values of the penalty coefficients is based on the representation of the original model in the form of a random-effects model (variance component model). A series of computer simulation experiments was performed to reconstruct the regression line with different noise levels and in the presence of outliers. The results of computational experiments to reconstruct the regression line are presented that show greater accuracy of the new model in comparison with conventional models.

A method for output-uniform coding of Markov sources with finite memory is proposed. The efficiency of the coding is estimated and compared with the efficiency of input-uniform coding.

The paper deals with the use of high-performance computing systems with a paralleloperation architecture to solve problems of image processing. The idea of using reconfigurable computing environments is set out. The synthesis of models of reconfigurable computing environments for some problems of binary image processing is considered, and the results of their operation are demonstrated.

A cuckoo search algorithm for identifying the parameters of fuzzy approximators and classifiers is presented. The results of experiments on eight sets of data from the KEEL repository are described. Comparison with analogs are given.

Statistical simulation of distributed sets of objects integrated into a large network and forming an operating environment is considered. The simulation is carried out on square matrices with random filling using percolation theory. Statistical features of the clusters of objects that arise in this case are analyzed. Along with well-known stochastic percolation, the concept of a controlled percolation of the operating environment is introduced, which is implemented in two phases: in the first phase, a stochastic basis with a relatively low concentration of objects is created, and in the second phase, additional objects are introduced in the intercluster intervals in order to obtain the shortest percolation path while minimizing the total cost of such two-phase operation. This model is used to consider vehicle navigation by visual landmarks randomly distributed in the operating environment.

This paper presents a method of monochromatic diffraction ultrasonic transmission tomography that takes into account the amplitude-phase distribution of the field diffracted on the object. The depth resolution of objects is achieved by multi-angle measurements. The results of numerical modeling and experimental studies at a frequency of 40 kHz in air confirm the applicability of the method.

An approach is proposed to perform a mathematical analysis of an ordered relief formed on the nanotitanium surface after laser shock-wave treatment. This approach enables one to obtain informative attributes and a quantitative estimate of parameters of morphological structures being formed with allowance for the stochastic and cyclic nature of this process.

The problem of statistical synthesis of the algorithm of detection of spatial objects by equipment that ensures a hyperspectral mode of observations is solved by using the log-likelihood ratio. Characteristics of detecting objects with completely known parameters and also with an unknown amplitude are obtained.

One of the aspects of passive detection and ranging associated with using amplitude (power) measurements in single-position direction finders is discussed. For such a motionless direction finder, a goniometric-energy method of passive detection and ranging is developed, which makes it possible to determine the slant range of the radiating target with partly known parameters of its motion. A solution for a three-dimensional case with due allowance for the nonstationary character of the radio detection and ranging generalized coefficient is obtained. A complex algorithm of comprehensive estimation of this coefficient and the range for the model of straightline uniform motion of the target is constructed. Results of a computational experiment are presented, which confirm the possibility of using the developed method in practice.

A method for measuring a phase difference between two interfering wavefronts on the basis of analyzing the trajectories that are formed by the intensities of pairs of points in a series of interferograms with different phase shifts is proposed. This method does not require a priori knowledge of the actual values of phase shifts.

A method for direct laser thermochemical writing of gray-scale microimages in thin chromium films is developed and studied. The method includes exposing a chromium film with a focused laser beam with variable power intensity and developing it in a selective etchant. The range of variation of the transmission by more than 100 times is obtained. The nonlinearity of the dependence of the chromium film transmission on the power intensity of the exposing beam is eliminated by software correction. The samples of the raster (with a size of 64×64 and a step of 176 μm) of apertures (36 μm) with the gray-scale Gaussian transmission function are manufactured experimentally. This raster is used in the modified Shack - Hartmann sensor.

A confocal experimental scheme with two polycapillary lenses is used to analyze the nearsurface layers of samples by X-ray fluorescent microanalysis with an accuracy of up to 10 μm. To increase the spatial resolution, it is required to account for the influence of the spread function of the confocal X-ray optical node. It is interesting to experiment with a tunable aperture of the confocal volume. In this case, the contribution of tuning inaccuracies in the spread function can increase. A method for describing the spread function of a confocal X-ray microscope that allows for its retuning and accounts for the effect of the angular tuning errors is proposed and experimentally proved. The method is based on the use of an approximating expression of the type of asymmetric approximation of the “Gaussian beam caustic”.

A new method for measuring radial and axial displacements of complex-shaped blade tips with the help of a distributed cluster of two single-coil eddy-current sensors with sensitive elements made as conductor strips is described. The main distinctive features of the method and the results of an experimental analysis of families of calibration characteristics of both sensors are considered. This analysis proves a higher sensitivity to changes in radial displacements and an extended range of axial displacement measurements of the new method as compared to the existent one.

A new class of electrostatic power microgenerators, which transform the energy of mechanical microvibrations to the electric form, is described. The transformation principle is based on transmitting external microvibrations to the microgenerator frame where thin layers of electrets are located, and a moving electrode is suspended on a weak suspension between these layers; this moving electrode performs alternating impacts on the frame. Generator operation is numerically analyzed, and analytical estimates of the generated power are obtained. It is shown that the power produced by such a generator is appreciably greater than the power generated in the classical circuit based on excitation of forced vibrations of a moving plate.