Home – Home – Jornals – Avtometriya 2014 number 6

The tendency to miniaturization of mechanical, electronic, and optical components imposes more stringent requirements to technologies of two-dimensional and three-dimensional fabrication, including laser micromachining. The high efficiency and simultaneous rigorous compliance with technical conditions in terms of accuracy and quality of the processed surface is reached only with the use of certain machining regimes, which are called optimal regimes. Determination of such regimes by methods of mathematical modeling is a difficult task; therefore, experimental methods based on statistical algorithms of data processing are being developed now. Specific features of application of these algorithms are considered.

Head-mounted displays for common-use optical information systems of three types (retroreflective, immersive, and transparent) are considered. Advantages of transparent displays equipped by real object distance meters and occlusive masks for correct interposition and occlusion of virtual and real objects are demonstrated.

Data on the structure of glasses and relaxors at nanometer scales are analyzed. It is found that the similarity of glass and relaxor structures at the nanoscale is due to the process of their production from the high-temperature phase of initial products: cooling of the liquid (glass melt) and crystal (relaxor). Experimental information about the mechanism of formation of nanostructures can be used for engineering purposes.

This paper presents a review of the state-of-the-art of methods for obtaining maximum likelihood estimates of signal parameters of Doppler lidars and laser Doppler anemometers.

This paper considers various approaches to improving the detection performance of point dynamic objects by using stereo vision under conditions where complete joint processing of a stereo pair of images is impossible. An improved triangulation algorithm with double thresholding is implemented. The possibility of forming marks from epipolar lines is studied for the case of a priori known shooting geometry. The situation of stereo observation of a dynamic object by moving cameras is simulated. The dependence of the detection probability on the level of false alarms is obtained experimentally for the proposed algorithms using model data.

Problems arising in calculating the probability of errorless readout of random fields with the coordinates of point objects forming the random field being registered by integrators with a limited number of threshold levels are considered. New results obtained with the use of computer analytics are presented. For the process of registration performed by single-level integrators, original ways of finding the errorless readout probability that do not require multidimensional integration are proposed.

Optimization of wavelet filtering algorithms with two– and three–parameter threshold functions is considered. The optimization is performed in two ways: by selecting the best threshold function and estimating its optimal parameters. Recommendations for the use of certain threshold functions in practice are given based on analysis of the results of numerical studies.

A method of interpolated estimation based on Bayesian theory is proposed to compensate for noise in an airborne electromagnetic system for mineral exploration. Expressions for estimates of the parameters of the Gaussian noise model are derived. Results of experimental application of the developed noise estimation algorithm for various parameters of the experiment are presented.

This paper deals with the real–time synthesis of high-quality images, a method of defining free forms without approximating them with polygons or patches, issues of using perturbation functions for real–time animation of the surfaces of three–dimensional objects. A method for visualizing functionally defined objects adapted for graphics processing units is proposed, and methods of transforming the describing function are implemented for geometric operations: deformation, displacement and metamorphosis, or morphing, including those for nonhomeomorphic objects. Advantages of the method of defining surfaces to the existing methods (algebraic and Bezier methods and their visualization techniques) are shown.

The image segmentation problem (partitioning into uniform regions) that uses brightness, color, and texture differences is considered. The criterion of uniformity is the estimation of the proximity of points in the combined attribute space. A metric is proposed for this space. This goal is achieved with a hierarchical algorithm based on the analysis of distances in the attribute space.

An algorithm for the analytical synthesis of functional observers is proposed which is based on a nondegenerate transformation of a state vector using the technology of matrix canonization and methods for solving linear matrix equations of arbitrary dimension. Conditions of the solvability of the synthesis problem and the invariance of the constructed observer to signal perturbations in the form of a system of linear matrix equations are formulated.

An important initial step in seismic tomography studies that use the kinematic characteristics of elastic waves is the optimal choice of the reference velocity distribution which corresponds to the principal known component of the velocity function in linearization. A numerical analysis of the determination of the reference velocity distribution parameters depending on the properties of the system of observations used is given.