Home – Home – Jornals – Avtometriya 2008 number 5

An algorithm for estimating the parameters and correcting the geometric distortions for the unknown focal length is obtained. A relationship between the directional field and the values of geometric distortion parameters is found. The relationship makes it possible to transform straight scratch images into horizontal lines. Results of experimental investigation are presented. They prove the possibility of using the directional field for solving the problem of correcting the geometric distortions of images obtained in track or ballistic investigations.

Measuring crystal diameters during Czochralski growth is investigated. An image of the crystallization meniscus zone is analyzed. Informative parameters are determined for finding crystal diameters. An algorithm for calculating the diameter of meniscus applied for crystal growth control is described. Results on operation of a sensor using the algorithm during real crystal growth are presented.

Applying the ant colony algorithm for solving the problem of parametric fuzzy model identification is presented. Transition from continuous optimization to discrete one via constructing a complete oriented decision-search graph is determined. A gradient algorithm is considered as the second optimization step. Experiments for analyzing the performance of the algorithms for optimization and fuzzy system are described.

The algorithm for reconstructing a 2D input signal (the image measured) by a finite realization of a 2D signal at the digital optical recording system output with the use of the fast Fourier transform is analyzed. The image reconstruction error is estimated.

Reconstructing the phase distribution of scalar speckle fields arising under light-induced scattering in a photorefractive  crystal is considered. A phase distribution reconstruction method based on simultaneous processing of two interferograms obtained for orthogonal planes of converging reference and signal beams is proposed. The method is more advantageous than single-interferogram methods for analyzing interferograms in the frequency domain because it enables to reduce the number of false-detected optical vortices and increase the SNR in phase reconstruction.

A method for physical process approximation using the differential Taylor transformation is substantiated. The power basis is transformed to bases of orthogonal Chebyshev polynomials. It is shown that the convergence of series is substantially increased by transition to expansion in Chebyshev polynomials of first kind and shifted Chebyshev polynomials. An algorithm for calculating differential spectrum discretes is formulated. It is observed that in the Chebyshev bases, the value of spectrum discretes decreases constantly as their number grows. In this case, it is possible to stop computing the discretes as they achieve the required small value, but this cannot be done in the power basis. Numerical examples illustrate the advantage of the proposed approach.

The average and maximum number of positive overshoots of the multiparticle Doppler signal envelope for the given threshold and also the average durations of positive and negative overshoots as a function of threshold are found. It is shown that the average duration of the positive envelope overshoots is inversely proportional and the average duration of the negative overshoots is proportional to the relative threshold. A tradeoff threshold value that ensures the required measurement accuracy for an admissible level of signal information loss is found.

Publications concerned with investigation and synthesis of switched systems are reviewed. Frequently used mathematical models of the systems are presented. Attention is focused on the problem of system stability for arbitrary and limited switching signals. Relationship between switched and fuzzy systems is illustrated. Some approaches to synthesizing switched controllers and state observers are considered.

A method for identifying some parameters of a dynamic undersea vehicle - environment system, such as a moment of inertia of rotating drive components with regard to the adjoint moments of inertia and a viscous friction factor of a propeller, is proposed. Simulation validated the high rate of convergence of the desired parameters to the true values.

A version of designing a gearless electric-power steering control system is described. An algorithm for calculating a modified PD controller based on localization is proposed for a simplified mathematical model of control object in the form of a classical two-mass steering-wheel - torsion - steering gear system. Modeling shows that such a PD controller ensures the desired system speed and damping vibrations caused by the control object.

Minimization of a partially monotone function system describing the finite-state machine (FSM) behavior is considered. A notion of a prime system implicant with maximal characteristics is introduced. It is proved that the shortest irredundant sum of the implicants is a union of the shortest irredundant sums of implicants with the same characteristics. In all implicants, the literals corresponding to the state variables have no inversions. The shortest irredundant sum of the implicants is used for FSM self-checking design.

A numerical model of processes in glow discharge plasmas is presented. The model is intended for simulating the work of plasma deposition reactors. One type of ion is considered. The ion and electron plasma components are modeled by kinetic equations with collisions. An effective parallel algorithm for modeling the processes in monosilane plasmas is designed; its main characteristics are given. Results of numerical modeling using the model are adequate to data obtained in physical experiments.

Methods of analysis and optimization of distributed multidimensional queues with priorities and dynamic control of the quality of services for sublevels of controlling multiple accesses to the medium access control in 3G/4G multiservice mobile and wireless networks are developed. A theoretical-game formulation of the problem of distributed dynamic control of the quality of services is proposed. The results obtained are based on the development of a numerical-analytical method for balancing load intensities.