The run-up of nonlinearly deformed sea waves on the coast of a bay with a parabolic cross-section

The run-up of long waves on the coast of a bay with a parabolic cross-section, where the region of constant depth along the principal axis of the bay is connected with the linearly inclined segment, is considered. The study is carried out analytically in the framework of the nonlinear shallow-water theory under the approximation that the height of the initial wave is small compared to the basin depth, and the reflection from the inflection point of the bottom is negligibly small. Three types of incident waves, viz., a sinusoidal wave and solitary waves of positive and negative polarities, are considered in detail. It is shown that a sinusoidal wave undergoes nonlinear deformation at a segment of constant depth faster than solitary waves of positive and negative polarities. Solitary waves of negative polarity steepen somewhat faster than solitary waves of positive polarity. Waves of positive polarity steepen at wave front, while waves of negative polarity steepen at wave rear. These differences in steepness may become crucial at the wave run-up stage, since the wave run-up height on the coast of a bay with a parabolic cross-section is directly proportional to the steepness of a wave that arrives at the slope and can lead to the anomalous run-up of waves on the coast.     

Catalytic pyrolysis of propane-butane hydrocarbon mixture on the composite ceramic materials in an open system

Catalytic pyrolysis of propane-butane hydrocarbon mixture on the composite ceramic materials with the surface modified with zinc-, cadmium- phosphorus- and silicon-containing compounds in an open system was studied in the temperature range 500–850°C, at the rate of the gas mixture flow 20–200 ml min⁻¹, contact duration 0.75–155 s, and the values of the heterogeneity factor 2.0 to 2.9×10⁵ cm⁻¹. The catalytic activity of the systems under similar conditions was compared, the influence of various factors on the yield of ethylene and propylene was investigated and the sooting was estimated.     

Oxidation of CO on Zr-, Fe-, Cr-, Ni-, and Cu-containing Catalysts Prepared by Pyrolysis of Metal β-Diketonates on a Synthetic Ceramic Foam

Catalytic systems containing Zr, Fe, Cr, Ni, and Cu composite coatings were suggested for oxidation of CO to CO₂. The coatings were prepared by gas-phase thermolysis of metal acetylacetonates and hexafluoroacetylacetonates on a synthetic ceramic foam. The kinetic and activation parameters of the CO oxidation on these catalysts were determined, and the relative activities of the catalysts were evaluated.     

Interfacial long traveling waves in a two‐layer fluid with variable depth

Long wave propagation in a two‐layer fluid with variable depth is studied for specific bottom configurations, which allow waves to propagate over large distances. Such configurations are found within the linear shallow‐water theory and determined by a family of solutions of the second‐order ordinary differential equation (ODE) with three arbitrary constants. These solutions can be used to approximate the true bottom bathymetry. All such solutions represent smooth bottom profiles between two different singular points. The first singular point corresponds to the point where the two‐layer flow transforms into a uniform one. In the vicinity of this point nonlinear shallow‐water theory is used and the wave breaking criterion, which corresponds to the gradient catastrophe is found. The second bifurcation point corresponds to an infinite increase in water depth, which contradicts the shallow‐water assumption. This point is eliminated by matching the “nonreflecting” bottom profile with a flat bottom. The wave transformation at the matching point is described by the second‐order Fredholm equation and its approximated solution is then obtained. The results extend the theory of internal waves in inhomogeneous stratified fluids actively developed by Prof. Roger Grimshaw, to the new solutions types.     

Oxidation of CO on Mn-Containing Catalysts Prepared by Pyrolysis of Metal β-Diketonates on Synthetic Ceramic Foam

New catalytic systems for oxidation of CO to CO₂ were developed. These systems are based on composite Mn, Mn-Ni, and Mn-Cu coatings and are prepared by gas-phase thermolysis of metal β-diketonates on a ceramic foam support. The relative activity of the new catalytic systems was examined. The kinetic and activation parameters of the oxidation of CO on these catalysts were determined.     

Kinetic features of thermal decomposition of cobalt acetylacetonate and development of catalysts for the oxidation of carbon monoxide,based on the decomposition products

The kinetic features of thermal decomposition of cobalt acetylacetonate in a vacuum were elucidated, and the volatile thermolysis products were identified. The homogeneous-heterogeneous character of the process was shown. Catalysts for the oxidation of CO to CO₂ were developed on the basis of cobalt acetylacetonate decomposition products and synthetic cellular ceramics, and the kinetic and activation parameters of the oxidation were determined.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004, pp. 1770–1774.Original Russian Text Copyright © 2004 by Tsyganova, Didenkulova, Shekunova, Faerman, Aleksandrov.This revised version was published online in April 2005 with a corrected cover date.     

Long Wave Run-up on Plane and “Non-Reflecting” Slopes

The long wave run-up on two types of slopes is investigated numerically within the framework of nonlinear shallow water theory using the CLAWPACK software. One of the slopes represents a plane slope widely used in the laboratory and numerical experiments; the second is the so-called “non-reflecting” slope (h ~ x^4/3, where h is the basin depth and x is the distance from the shoreline). In the case of very low wave amplitudes when there is no wave breaking, the run-up height is greater on the non-reflecting beach than that on the plane slope. As the wave amplitude increases, the breaking effects have the stronger impact in the case of non-reflecting beach and the run-up height becomes smaller.     

Catalytic pyrolysis of the propane-butane hydrocarbon raw material

Principal characteristics are determined of the process of pyrolysis of the propane-butane hydrocarbon raw material in a steel reactor in the presence of catalysts (ceramic film type polyphosphate covering on the steel reactor walls) containing metals of II and III groups of Periodical Table with the overall composition Me _x O _y ·z(P₂O₅), where x = 1, 2; y = 1, 3; z = 2, 3. By the investigation a sequence of catalytic activity of the samples of the metal-containing coverings by their effect on the yield of ethylene and propylene is elucidated: Zn > Cd > Sr > Ce. The similar sequence corresponds to inhibiting activity at the cocking inhibition.     

The Role of a Thick Soliton in the Dynamics of the Soliton Gas Within the Framework of the Gardner Equation

Radiophysics and Quantum Electronics - We study the statistical moments of the soliton gas (mean field, variance, skewness, and kurtosis), which is described within the framework of the Gardner...     

Carbon monoxide oxidation by atmospheric oxygen on catalysts prepared by pyrolysis of transition metal β-diketonates on the synthetic foam ceramics

The results of development of new catalytic systems for the carbon monoxide oxidation to dioxide are systematized. The catalysts were produced by gas-phase thermal decomposition of the transition metal acetylacetonates on the synthetic foam ceramics. The kinetic and activation parameters of the oxidation on the catalysts were studied and their relative activity was explored. The activity of catalysts at the oxidation with air oxygen were found to depend on the nature of the deposited metal and the carrier. A synergistic effect in the bimetallic copper catalysts was revealed.