Home – Home – Jornals – Avtometriya 2005 number 2

The errors of estimating the 3D coordinates of a static scene and the camera orientation from an image sequence are analyzed. Two cameras moving in close trajectories form the images. The estimation is done by the maximum likelihood method. Results of computational experiments simulating various shooting conditions are presented.

Various approaches to improving the quality of dynamic point object detection by using stereo vision are considered. A triangulation algorithm with preliminary thresholding and an algorithm forming a set of marks over the whole stereopsis set are implemented and studied. The dependence of the detection probability on the false alarm level was experimentally obtained for the proposed algorithms for different signal-to-noise ratios. A theoretical dependence of the object amplitude on the false alarm level for the given detection probability is presented. The efficiency of using a priori information on the altitude curve of an object while its detecting is analyzed.

The solution to the problem of optimal linear forecasting the stationary stochastic process via the known trend is obtained. It is shown that this solution provides solving the problem of linear forecasting via an unknown trend if the linear forecast of the trend is replaced by its optimal linear estimator. The relation between errors of forecasting via known and unknown trend is found. Strong influence of the discorrelation effect on the forecast error is illustrated. Recommendations for designing practical forecasting algorithms are obtained.

The robust filter synthesis algorithm determining the state vector estimator of a continuous-time linear dynamic system with random jump parameters described by the Markovian chain with the finite number of states for a degenerate or ill-conditioned matrix of measurement noise intensities is considered. It is proposed to choose the filter transfer coefficients from the minimum sum of the trace of covariance matrix of filtering errors and the weighted innovation process covariance with simultaneous averaging over state probabilities of the random jump parameter. Conditions of asymptotic robust filter stability for a stationary system are obtained.

The approach to estimating the processes of localized plastic strain on a mesoscale level, which is based on constructing the fields of displacement vectors obtained by processing pairs of images, is developed. Comparative study of the algorithms from the viewpoint of noise immunity and time of determining surface displacements is carried out. The effects of subpixel calculation accuracy of displacements and postcorrection on the results of construction of displacement vector fields and subsequent calculation of strain components are analyzed. It is shown that the subpixel accuracy of constructing the displacement vector fields allows one to interpret more correctly the physical sense of the running processes and increase the accuracy of determining the strain components: components of the distortion tensor, the main plastic displacement, etc.

An approach to solving the problem of color or gray-scale image segmentation into regions of the same color is considered. The proposed algorithm is based on direct search for regions with the use of methods of working with lists, which are applied in logic programming and artificial intelligence systems.

The problem of detecting the discord in a sampling of the stochastic Gaussian process based on the observations with the use of the principle of minimum informative divergent distributions in the Kullback-Leibler metric is posed and solved.

An algorithm of analog signal restoration in the modified Sobolev space with additi- onal use of derivative samples is proposed. Transfer coefficients of the restoring filters are obtained. The possibility of reducing the truncation error in practical implementation of the algorithm in the space compared with similar algorithms in the space is shown.

The problem of designing the autocorrelation function (ACF) of an input signal for linear stationary discrete-continuous systems described by models in the state space is posed and solved. The problem of reconstructing the D-quasioptimal input signal from its D-optimal ACF is also considered. Results of computational modeling are presented.

Researches concerned with selective properties and processes of formation of nonuniform and nonstationary Bragg holograms in various recording materials are reviewed. Volume hologram models regarding the nonuniform light absorption, the recording layer thickness shrinkage, the change in the modulation value and the average refractive index value through the hologram depth, and showing the difference between selective properties of such holograms from the ideal knowledge are described. Analytical and numerical research methods that are most suitable for each model are considered.

Procedures of mating the needle-shaped unit of a rigid endoscope, which includes GRIN objective and translator, and a color video camera are presented. It is shown that a uniform flat-convex lens introduced to the system easily eliminates the chromatic aberration of position and magnification, and an additional uniform meniscus lens minimizes the aberrations of thin beams.

Results on experimental analysis of diffraction millimeter-wavelength radio-wave objectives based on phase cylindrical zone plates with four phase quantization amplitudes with application to quasi-optical radio-wave imaging systems are presented.

Modern conceptions of the evolution of cryogenic area of West Siberia during the last 5 million years are formulated on the basis of paleogeocryological interpretation of the unique paleoclimatic chronicles obtained by a large group of scientists for southern regions of West Siberia and the Siberian Platform as well as on the careful examination of recent publications on the changes of climatic and geocryological conditions during the last 800 000 years. It has been ascertained for the first time that the perennial rock freezing and the formation of the cryogenic strata in West Siberia began 3.1 million years ago. Three cryogenic epochs have been revealed in the range of 3.1-3.0 million years ago. The first epoch (3.10-3.08 million years ago) was the least cold and the shortest. The second epoch (2.82-2.47 million years ago) was remarkable for extremely severe geocryological conditions in cryochrons and severe condition in thermochrons. Consequently the cryogenic strata had been existing steadily for more than 350 000 years. The third epoch (1.92-0.00 million years ago) was notable for the multiple alternation of the aggradational (cryochrons) and degradational (thermochrons) epochs. During only the last 800 000 years 21 cryochrons and 20 thermochrons have been marked out, which differed in duration (from 2 to 60 thousand years) and in heat supply of climate. In the Early and Middle Neopleistocene 11 cryochrons has been revealed during which the rock temperature fell by 8-12

The Earth Cryosphere Institute of the Russian Academy of Sciences, Siberian Branch, undertook studies in West Siberia within the framework of Circumpolar Active-Layer Monitoring (CALM) International Program. The paper summarizes the results of active-layer monitoring that started in early 1970-s at profiles and grids, to which CALM sites were added in 1990-s. The results obtained at the CALM sites and the previously established grids and profiles allow estimating the main tendencies in the active-layer dynamics in different landscapes of two bio-climatic zones (tundra and taiga) under climate fluctuations. It is established that: climatic trends are not evident in tundra and low in taiga; active-layer fluctuations in general follow the climate changes; there are variations in response of different landscapes to climate changes; atmospheric precipitation plays an important role in active-layer annual fluctuations.

The influence of mountain topography on the evolution of alpine permafrost was studied under Southern Yakutia conditions using a two-dimensional finite difference thermal model. The altitudinal zonality in the mean annual ground surface temperature distribution and the spatial heterogeneity of thermal properties and water content of rocks were included in the model. It has been recognized that 100 Kyr, 33 Kyr, 1.5 Kyr and 208 years

Pollen spectra of Late Pleistocene and Holocene syngenetic ice wedges in the mouth of the Seyaha River of Eastern Yamal Peninsula have been considered. Changes of pollen spectra in ice-wedge ice, formed 22-10 ka BP, 9-6 ka BP and last 2-1.5 ka have been investigated.

The data of long-term field experiments on the effect of snow and soil covers on the soil thermal regime in various landscapes of Central Yakutia have been presented. The insulating effect of snow cover has been estimated taking into account the snow accumulation dynamics, the peculiarities of underlying vegetation and the degree of soil surface moistening. The greatest warming effect of snow cover is on the ice surface of lakes (a wintertime average is 23-26

In the present study we represent the new results of investigation of oil penetration in the upper horizons of permafrost on the testing bank (laid in 2000) in the entry of the river Pechora (Cape Bolvanskiy). The results of the permafrost sampling have shown that three years after the starting of the field experiment oil penetration was fixed throughout the depth of exposed permafrost (0,5-0,7 m). Its concentration reaches 600-800 mg/kg, which is comparable to the pollution of the layer of the seasonal defrostation. The received data have demonstrated that schlieren cryogenic textures of the frozen sediments did not inhibit the penetration and accumulation of hydrocarbon contaminants to the permafrost. Based on the theoretical and experimental data, the principal mechanisms of possible penetration of oil pollution into the permafrost have been considered.

Data of geocryological stations and of other observation monitoring permafrost objects have been systematized and small-scale electronic map of theirs location on the Russian permafrost territory have been elaborated. A great deal of geocryological stations are situated in the European north-east, north of West Siberia and Central Yakutia. The observations on the depth of seasonal thawing and permafrost temperature make up the main part of realized station work. It is possible to consider the fulfilled stock-taking as one of the preparatory stages for carrying out the IV International Polar Year (2007-2008).

The massive ice was recognized as an individual genetic type of underground ice only in the middle 70s, but it took 10 years more to get evidence of the buried glacial nature of massive ice in cryolithozone. The massive ice body has an unconformable top contact with cover sediments, typical glaciodeformations and the flecks of various moraine material including boulders more than 1 meter diameter. Despite the huge dimensions of ice bodies they are not adequately represented in relief; both chemical and isotope-oxigen contents of the massive ice are comparable with the glacial ice content and differ strongly from other types of underground ice. The genetic identification of massive ice introduces serious corrections in a number of fundamental theses of cryolithogenesis. In this paper the conditions of deglaciation and conservation of glacial ice in frozen strata have been reconstructed based on the analysis of permafrost-glacial situation at the southern margine of the modern Arctic glaciation area.

Analysis of basic hydrogeological and geocryological conceptions has been carried out. The system approach has been used. The definition of the term