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Effect of the calcination temperature of the MnOx/Ga2O3 system on its structural and catalytic properties in the reaction of oxidation of CO and hydrocarbons. The dependences of the catalytic activity of MnO x /Ga2O3 in the reactions of CO and ethane oxidation on the calcination temperature exhibit an extremal behavior. The maximum values of activity are observed upon calcination of the system at 700°C, i.e., at the temperature that is limiting for the existence of a solid solution of manganese ions in γ-Ga2O3. The structural changes occurring with increasing calcination temperature are accompanied by a substantial decrease in the specific surface area of a sample. The observed rise in the specific catalytic activity (by a factor of ~7 upon an increase in the preliminary-calcination temperature from 600 to 800°C) confirms that the thermal activation effect exists for the given system.

The conversion of ethane on Al2O3, ZrO2, SiO2 oxides supported on fechral carrier under conditions of its resistive heating was investigated. A cold gas mixture consisting of ethane and nitrogen was fed to a spiral heated by an electric current to 900-1100 °C. It was shown that the ethane pyrolysis proceeds with the predominant formation of ethylene in the range of 650–950 °C. At higher temperatures, the yield of methane and carbon by-products increases significantly. The selectivity and yield of ethylene are affected by the nature of the carbon deposited.

The combined transformation of methane, its pyrolysis products and ethane in the two-section T-shaped reactor are investigated. In the first section of the reactor (the supply tube) the FeCrAl alloy spiral catalyst, which is heated by electric current, is located. A cold gas mixture consisting of methane and nitrogen was fed to a spiral heated to 800-1100 °C. Then the reaction gas got into the second section of the reactor and mixed with the flow of the ethane and nitrogen mixture. It was shown that there are principal possibility of C3 and C4 hydrocarbons receiving under these conditions. The effect of the spiral temperature on the composition of the reaction products was also investigated.

AK9 silumin samples (Al-Si) were treated by plasma electrolytic oxidation (PEO) in order to obtain surface oxide layer. These samples were not enough active as catalysts in CO oxidation (1% CO vol in air). Palladium activated samples were more active. Thus the temperature of 50% CO conversion for Pd/SiO2/Al-Si sample is T50 = 152 ̊C and T99 is 170 ̊C. According to IR spectroscopy and Raman spectroscopy as well as scanning electron microscopy data, the active layer of the most active sample Pd/SiO2/Al-Si presents by noncrystalline SiO2 with γ-alumina and palladium inclusions. the covering has of 10-20 nm Accordingly to atomic force microscopy data the roughness of surface layer is ∼ 10 – 20 nm.

MeOx/MA and Pd/MeOx/Ni-Al/MA catalysts (MA are metal alloy grids (fechral, nichrome, stainless steel (SS)), Ni-Al/MA are metal grids with a sputtered Ni-Al layer) with MeOx oxides Al2O3, Al2O3-CeO2 and Al2O3-MnO2 as the secondary supports were synthesized and tested in the oxidation of methane. The Ni-Al coating, which was used to improve the adhesion of oxides to a metallic underlayer, showed the highest catalytic activity in the deep oxidation of methane at 500 °C: the conversion on Ni-Al/SS and Pd/Ni-Al/SS samples was 11.7 and 97.7%, respectively. The catalysts were characterized by means of X-ray diffraction analysis and scanning electron microscopy.MeOx/MA and Pd/MeOx/Ni-Al/MA catalysts (MA are metal alloy grids (fechral, nichrome, stainless steel (SS)), Ni-Al/MA are metal grids with a sputtered Ni-Al layer) with MeOx oxides Al2O3, Al2O3-CeO2 and Al2O3-MnO2 as the secondary supports were synthesized and tested in the oxidation of methane. The Ni-Al coating, which was used to improve the adhesion of oxides to a metallic underlayer, showed the highest catalytic activity in the deep oxidation of methane at 500 °C: the conversion on Ni-Al/SS and Pd/Ni-Al/SS samples was 11.7 and 97.7%, respectively. The catalysts were characterized by means of X-ray diffraction analysis and scanning electron microscopy.

The Pd/Sibunit and Pd-Ga/Sibunit catalysts, which were supported on Sibunit with different textural characteristics, for liquid-phase acetylene hydrogenation were investigated. It was shown that the use of the support with a large surface area leads to an increase in catalytic activity and selectivity due to the increased dispersion of the active component. The promoting effect of gallium correlates with the probability of contact between the supported Pd and Ga components.

Some catalysts of CO oxidation on silumin alloy AK12M2, used for the manufacture of pistons for Russian cars were investigated. The catalysts were prepared by the method of plasma electrolytic oxidation of silumin in electrolytes of various compositions with further activation by the salts Ce, Cu, Co, Ni, Mn and Al. The catalytic tests were carried out in a flow reactor in a mixture of 1% CO and 99% air, with the temperature range of 25-500 °C. The most active catalysts in CO oxidation are those activated with Ce and Cu salts on silumin, treated for 3 hours in an electrolyte containing 4 g/l KOH, 40 g/l Na2B4O7 (conversion of CO is 93.7% at a contact time of 0.25 s). However, the catalysts obtained from silumin treated in the electrolyte containing 3 g/l KOH, 30 g/l Na2SiO3 are more suitable for practical usage. Because when the treatment time of those catalysts is 10 – 20 minutes it is possible to achieve comparable CO conversion. The morphology and composition of the catalysts were studied by the methods of a scanning electron microscope with energy-dispersive surface analysis and X-ray phase analysis. The surface of the non-activated sample consists of γ-Al2O3 and SiO2 particles, due to which the active components get attached to the support. CeO2 and CuO are present on the surface of the sample with the active component.Some catalysts of CO oxidation on silumin alloy AK12M2, used for the manufacture of pistons for Russian cars were investigated. The catalysts were prepared by the method of plasma electrolytic oxidation of silumin in electrolytes of various compositions with further activation by the salts Ce, Cu, Co, Ni, Mn and Al. The catalytic tests were carried out in a flow reactor in a mixture of 1% CO and 99% air, with the temperature range of 25-500 °C. The most active catalysts in CO oxidation are those activated with Ce and Cu salts on silumin, treated for 3 hours in an electrolyte containing 4 g/l KOH, 40 g/l Na2B4O7 (conversion of CO is 93.7% at a contact time of 0.25 s). However, the catalysts obtained from silumin treated in the electrolyte containing 3 g/l KOH, 30 g/l Na2SiO3 are more suitable for practical usage. Because when the treatment time of those catalysts is 10 – 20 minutes it is possible to achieve comparable CO conversion. The morphology and composition of the catalysts were studied by the method...

This work describes some functional economic trends in largest Russian cities. The assumption considered that low values of economic density in largest Russian cities are determined by their underdeveloped social capital. Essential imbalances have been identified in economic development, the localization of decision-making centers, and connectivity between Moscow and largest noncapital cities. These results confirm the point that the social capital in largest Russian cities is underdeveloped. Political and institutional conditions for the development of urban social capital as a largest factor of urban development are considered. Contradictions between urban-development objectives and current political and managerial practices have been identified. The reduction of democratic principles in city administration does not encourage urban social capital development and impedes formation of broad coalitions and elaboration of economic growth strategies in largest cities.

Model catalysts Pd/Ga2O3 of selective liquid-phase hydrogenation of acetylene to ethylene were prepared by impregnation of β-Ga2O3 with a palladium nitrate solution with following drying and reduction in a hydrogen flow at 200 °C. A part of the samples was then calcined in an argon flow at 200–500 °C. The as-prepared samples were tested in the reaction of selective liquid-phase hydrogenation of acetylene. EXAFS was used to study structure of the catalyst components. Based on the EXAFS data it was found that Pd–Ga alloys present in the subsurface region of Pd particles. The presence of these alloys increases activity and selectivity of catalysts. The alloys are decomposed by calcination in inert atmosphere following decrease in catalytic activity.

The paper develops a numerical method to analyze and model planar shapes via polygonal curve evolutions. Consider a smooth curve each point of which moves in the normal direction with speed equal to a function of the curvature and curvature derivatives at the point. Chosen the speed function properly, the evolving curve converges to a desired shape. Smooth curve evolutions are approximated by evolutions of polygonal curves. Discrete analogs of the curvature and its derivatives are considered and analyzed. We apply our approach to simplify curves for purposes of multiscale shape analysis, to model geodesics on a plane equipped with a Riemannian metric, to design of nonlinear splines satisfying various boundary conditions, and to detect objects in grey-scale images.

We propose a new approach for recognition, description and extraction of ridges and ravines based on singularity theory; the approach may be used for shape coding and animation.

A new concept of ridges, ravines and related structures (skeletons) associated with a surface in three-dimensional space is introduced. The concept is based on the investigation of relationships between the singularities of the distance function from the surface and singularities of caustic of the normals to the surface. It involves both local and global geometric surface properties and leads to the effective procedure for ridges and ravines recognition.

We propose a fully automatic and view-independent computational procedure for detecting salient curvature extrema in range data. Our method consists of two major steps: (1) smoothing given range data by applying a nonlinear diffusion of normals with automatic thresholding; (2) using a Canny-like non-maximum suppression and hysteresis thresholding operations for detecting crease pixels. A delicate analysis of curvature extrema properties allows us to make those Canny-like image processing operations orientation-independent. The detected patterns of creases can be considered as ‘shape fingerprints'. The proposed method can be potentially used for shape recognition, quality evaluation, and matching purposes.

We introduce a new concept of ridges, ravines and related structures (skeletons) associated with surfaces in three-dimensional space that generalizes the medial axis transformation approach. The concept is based on singularity theory and involves both local and global geometric properties of the surface; it is invariant with respect to translations and rotations of the surface. It leads to a method of hierarchic description of surfaces that yields new approaches to shape coding, rendering and design. The extraction of the features is based on differential geometry of surfaces with consequent segregation via multiscale analysis. Terrain feature recognition, dental shape reconstruction and medical imagery are a partial list of applications. >

On a smooth generic surface we define ridges to be the local positive maxima of the maximal principal curvature along its associated curvature line and ravines to be the local negative minima of the minimal principal curvature along its associated curvature line. We investigate relationships between these surface line features, singularities of the caustic generated by the surface normals, and the singularities of the distance function from the surface. We also propose a variational problem to model garment wrinkles and investigate relationships between singularities of a proper solution of the problem and singularities of the distance function.

Analyzing the 3D images of a given surface as viewed from different positions naturally leads to investigation of coordinate-independent geometric surface features reflecting its essential properties. In the present paper we study surface point features related to ridge and ravine lines on a surface. These lines introduced in our previous works are defined as curves corresponding to the boundary points of the skeleton of the distance transform of the surface. We show that the ridges and ravines can be extracted via the directional derivatives of the principal curvatures along the associated principal directions. However, even after this local description the direct extraction of the ridges and ravines is a time-consuming procedure. It turns out that the ridge and ravine lines contain some remarkable points (end points and others) that can be extracted relatively easily. After finding such points the procedure of ridge and ravine extraction becomes much simpler. Moreover, these points are closely connected with some singularities of caustics and wavefronts, and have an independent interest in image analysis as visual invariants. The paper is devoted to the investigation of such points and the accompanying geometry of singularities of wavefronts and caustics. We also demonstrate applicability of the ridges and ravines defined as above and related point features in image understanding.