Home – Home – Jornals – Avtometriya 2004 number 1

The problem of detecting point dynamic objects is considered for new conditions of registering a sequence of images that differ by the presence of projective stationary background distortions. Algorithms for processing such sequences are presented. Results of experiments on investigating the influence of the input actions and the registration noise on the object detection probability are given.

A regression model with correlated observations of responses is considered. The groups of correlated observations have a multivariate distribution (Student

A decomposition approach to solving the ill-conditioned optimal estimation problems is developed using the invariance conditions. The approach allows construction of stable LSM estimators on the basis of two parallel algorithms whose dimension is substantially smaller than that of the classical LSM estimation procedure.

For the cone-beam tomographic reconstruction method, the radiation source moving trajectory consisting of two intersecting circles is studied. A circle choice algorithm for each plane intersecting the object is proposed to obtain the most accurate result of reconstruction. Computer simulation results are presented for qualitative evaluating the advantage of the circle choice algorithm. It is shown that for the trajectory under study the boundaries determination accuracy depends on the boundary location. Directions with the most accurate reconstruction are found.

An approach to distributed computer system (CS) self-diagnosis is proposed. Game-theory methods for CS dispatching in the mode of parallel task stream serving are developed. The architecture and software of a robust distributed cluster computer system are described.

Hybrid models of stochastic dependencies are considered in the presence of a priori data on their description in the incomplete space of controlled features. Asymptotic properties of the models are investigated. They are compared with results of computational experiment.

A computer model of a digital measurement system with parallel channels is developed. The system allows measuring the summarized error of a reconstructed signal in the presence of errors in individual channels. The influence of the errors of the static channel characteristic (zero offset and scaling) and the dynamic error arising as a result of channel synchronization errors is analyzed. Results of the analysis are presented in the time and frequency regions.

An approach to transformations of the definition function for geometric projection, offsetting, set-theoretic, and metamorphosis operations is considered. A characteristic of more complex operations for functionally defined objects with the use of perturbation functions: swept volume of moving solids and twisting a constructive solid, is presented. The adaptability and universality of this approach is illustrated by examples of images obtained while modeling geometric operations.

A mathematical method for modeling the adiabatic burning temperature depending on the molecular fuel structure is considered. The method was tested on experimental data in comparison with other methods.

It is proposed to solve the problem of document watermark identification by using decomposition of wavelet spectrum of a microdensitometer signal. The advantage of the proposed signal processing method over conventional methods is shown.

A composite material with an ordered periodic structure was formed as a result of spatially nonuniform photopolymerization and phase separation of a nematic liquid crystal and a polymer from the initial mixture containing a new acrylate monomer. The structure ensures refractive index modulation in the composite material volume. The obtained composite material is promising for application as electrically switchable transmission gratings.

The possibilities of applying the high-temperature superconducting quantum interferometers in measurement systems are investigated. Various designs of quantum interferometers are used: one-circuit, two-circuit, and Harvey interferometers. The following characteristics of the measurement systems are considered: the coefficient of input magnetic flux transformation to output voltage of the measurement channel, the sensitivity threshold, the frequency dependence of input noise spectral density, the amplitude frequency characteristic of magnetic flux transformation to output voltage of the measurement channel, and the upper boundary frequency of the measurement channel bandwidth. A method for investigating these characteristics is described and results are presented. It is shown that the Zimmermann type of interferometers is the most promising one. Applications of a magnetometer to finite measurement systems are illustrated.

The action of two spectral regions of UV light is compared from the viewpoint of defect creation and practical application of the created defects to image recording. A local near-activator anion excitation is created in one of the UV light regions in the - absorption band. This excitation at the final stage of transformation leads to creation of pairs of close defects where the activator hole center is created by ionization of the activator near which the light -quantum was absorbed. Electron centers arise in the process when the shallow traps initiated by the -centers are filled with electrons from the foregoing ionized activator. Excitation arises in another UV region (absorption band of 1s exciton) in the regular lattice. At the moment of origination it is associated with neither the activator nor the activator hole center. However, as a result of migration and relaxation this excitation also creates pairs of close defects on the basis of -centers already available in the crystal. Exciton polaritons are probably responsible for creation of the pairs The pairs of close defects can be used for image processing by photostimulated luminescence, each type of pairs gives different characteristics.

Peculiarities of propagation of femtosecond pulses through a focusing diffractive optical element are considered. It is shown that the time delay between the pulse and phase wavefronts can be decreased by fabricating the diffractive optical element on the optimal curvilinear surface.