Home – Home – Jornals – Avtometriya 2009 number 2

A high-resolution image is constructed by joint interpolation of a series of low-resolution images differing in mutual shifts which are not multiples of the sampling interval. Interpolation coefficients are determined by using correlations between the readings of the initial images. Results of experiments showing the efficiency of the proposed approach are given.

An optimal method of generalized estimation of the values of linear functionals is developed for the case where experimental data include not only selected values of the measured process, but also values of its derivatives of various orders. In addition, experimental data are assumed to contain a multistructural piecewise-continuous interference, which is known to accuracy of parameters and for which the instants of the structural change are unknown. The method is invariant to this type of interferences and does not require extension of the space of states, as compared to available estimation techniques.

A Welch-type estimator (an estimator obtained by averaging over the time shift) for the spectral density function of a stationary continuous-time random process is considered. The bias and variance of the statistical estimator are studied, and some recommendations concerning the choice of its parameters are formulated.

Methods for forming a three-dimensional image of the Earth surface and objects on this surface with the use of an airborne multichannel radio-thermal location station are proposed. These methods are based on range measurement, image reconstruction, and correlation-extreme combination of frames.

This paper considers a group of linear perspectives for transformation of three-dimensional visual scenes based on a patented method of displaying objects. Projective transformation matrices, including those for three-dimensional graphics application programs, are given.

A method is proposed for estimating non-multiple seasonal periods by an example of data on cyclic solar activity in the form of Wolf numbers. The values of the periods obtained are used to construct a multiplicative seasonal model in which the number of periods cannot exceed five in practice. Two possible variants of the algorithm for choosing the initial approximations of the model parameters with the use of a pseudorandom number generator are described. A modification of the two-stage steepest descent algorithm with improved performance and stability is given. For incomplete inadequate autoregressive moving average models, an additional criterion of proximity of the trajectory formed by the model to actual data is proposed, which can improve the forecast quality.

Relations between the accuracy of hotspot determination and the monitoring area of remote forest fire detection systems are considered. The indicated characteristics have a significant effect on the efficiency of the systems considered. The efficiency can be increased by simultaneously using visual monitoring means and automated mapping of forest compartments in the monitored area. Procedures for searching the forest compartment number and determining compartment boundaries are discussed.

A method for gas sampling in hypersonic hot-shot wind tunnels is proposed. A sampler designed on the basis of this method is shown to ensure heat removal for "freezing" the sample and to provide reliable information about the composition of a hypersonic gas flow. A diagnostic system for multispecies gas mixtures on the basis of small-size sensors is developed and manufactured. Testing this system in an IT-302M hypersonic hot-shot wind tunnel shows that the measurements correctly capture the trends in the behavior of oxygen concentration as a function of flow energy, but the values are underestimated approximately by 2% with respect to the true values. Possible reasons for this behavior of the sensor are discussed.

A method of coupled interactions for real-time management of resource allocation is proposed. A distinctive feature of the method is the replacement of the enumeration of decision patterns, requiring high computational efforts, by bilateral negotiations aimed at detecting conflicts and reaching compromises between incoming requests and available means in constructing complex schedules. This feature provides significant advantages during solution of complex problems of real-time resource allocation, which can be important for corporate and government management systems.

A Shack-Hartmann type wavefront sensor designed on the basis of a low-aperture off-axis diffraction lens array is described. Tests experiments showed that the sensor is capable of measuring wavefront slopes at array subapertures of size 640Ч640 μm with an error not exceeding 4.80 arcseconds (0.15 pixel), which corresponds to the standard deviation (SD) (SD = 0.0170λ) at the reconstructed wavefront. Advantages of the array used in the sensor and the technology of its manufacture are discussed. The sensor tested in the experiments can be used to measure atmospheric turbulence parameters and as an element of adaptive optical imaging systems.

Results of analyzing chromatic aberrations of an eye model with different designs of intraocular lenses (IOLs), that is, artificial crystalline lenses (refractive, diffractive-refractive, diffractive, and harmonic, i.e., multiorder lenses) are represented. Investigations were carried out sequentially for elements of the model, namely, for a cornea, refractive and diffractive components, and IOL, and as a whole, for a cornea + IOL. It is shown that diffractive-refractive IOLs in which the diffractive components produce a positive additional focal power possess the best chromatic characteristics. Chromatic aberration of the eye model with such IOLs is 2 times less than that of a model with a refractive IOL, whereas with other IOL designs it is 2 times greater and even more.

Direct numerical modeling of propagation of optical pulses is performed to determine the "tails" of the probability density function of marks and spaces and the statistics of errors in an optical communication link on the basis of a standard single-mode fiber and a dispersion-compensation fiber with a reduced density of marks in the initial bit sequence. Simple analytical approximations for the tails of the probability density function are determined, which allows accurate estimation of the error probability in the link.