Monotone compact running schemes for systems of hyperbolic equations

For quasilinear hyperbolic equations, conservative absolutely stable compact schemes are presented that are monotone in a wide range of local Courant numbers. The schemes are fourth-order accurate in space on a compact stencil and first-or third-order accurate in time. They are efficient and are solved by the running calculation method. The convergence rate of the schemes is analyzed in detail in the case of mesh refinement for solutions of various orders of smoothness. The capabilities of the schemes are demonstrated by solving well-known one-dimensional test problems for gas dynamics equations.     

Analysis of Metrological Provision Problems of a Test Stand for Testing Radio-Electronic Products for Resistance to Irradiation with High-Energy Heavy Ions

Physics of Particles and Nuclei Letters - The problems of the metrological certification of beams of high-energy heavy charged particles (HCPs) and protons that will be used in the study—as...     

Effect of the Nucleon-Density Distribution on the Description of Nuclear Decay

It is proposed to test the parameters used in a self-consistent analysis of the nucleon distribution in nuclei via the calculation of the nucleus–nucleus potential, which is necessary for describing nuclear decays. The nucleon distribution is shown to correlate with the parameters of the nucleon–nucleon interaction. A unified approach to calculating characteristic alpha-decay and spontaneous-fission times is developed on the basis of the dinuclear-system model.     

Bicompact Schemes for the Multidimensional Convection–Diffusion Equation

Computational Mathematics and Mathematical Physics - Bicompact schemes are generalized for the first time to the linear multidimensional convection–diffusion equation. Schemes are constructed...     

Measurement of the absorption coefficient for UCN at a copper surface

The probability of ultra-cold neutron capture at a copper surface was measured by the activation method. The experimental absorption coefficient is well accounted for by a calculation which takes into account the presence of a CuO-layer at the surface of a Cu-film.     

Poisson Kernel on the Quantum Lobachevsky Spaces

We define an analog of the Poisson transform on the quantum Lobachevsky spaces.     

Selective oxidation of hydrocarbons into synthesis gas at short contact times: Design of monolith catalysts and main process parameters

This review summarizes the main achievements of the Boreskov Institute of Catalysis (Siberian Division, Russian Academy of Sciences) in the development of efficient and stable monolith catalysts for selective oxidation of hydrocarbons into synthesis gas at short contact times. Research in this field has included (1) design of new types of active component based on metal oxides, (2) design of new types of monolith support and development of supporting procedures for active components, and (3) optimization of process parameters for different types of fuel (natural gas, isooctane, and gasoline) and oxidant (air oxygen, including its mixtures with water and carbon dioxide), including the start-up regime. Design of active components (platinum, nickel, or their combination) supported on fluorite-like solid solutions based on cerium dioxide and rare-earth (samarium, gadolinium, and praseodymium) or zirconium cations has been aimed at separating hydrocarbon activation (on metal sites) and oxidation (on the support) and conjugating the separated steps of hydrocarbon oxidation at the metal-oxide interface. Optimization of oxygen mobility in the support lattice by varying the nature and concentration of doping cation along with optimization of hydrocarbon activation on supported metal clusters allow hydrocarbons to be completely converted into synthesis gas by selective oxidation or dry or steam reforming at contact times of a few milliseconds, ruling out undesirable carbon build-up on the catalyst surface. The development of new types of monolith support has targeted the enhancement of thermal shock resistance, including testing of supports based on thermally stable metal foils and composites (cermets). The main steps of the production of these supports have been refined, including unique technologies of blast dusting and hydrothermal treatment. The electric conductivity of these systems allows a quick startup of selective oxidation to be performed by passing electric current, and their thermal conductivity minimizes the temperature gradient arising from heat transfer in the bed. Procedures for loading monolith supports with active components have been developed, including impregnation, washcoating, or encapsulation in cermet matrices. The catalysts produced show a high efficiency and an operational stability adequate to the above tasks in the selective oxidation and steam-air autothermal reforming of natural gas (including processes under pressure), isooctane, and gasoline into synthesis gas.__________Translated from Kinetika i Kataliz, Vol. 46, No. 2, 2005, pp. 243–268.Original Russian Text Copyright © 2005 by Sadykov, Pavlova, Bunina, Alikina, Tikhov, Kuznetsova, Frolova, Lukashevich, Snegurenko, Sazonova, Kazantseva, Dyatlova, Usoltsev, Zolotarskii, Bobrova, Kuzmin, Gogin, Vostrikov, Potapova, Muzykantov, Paukshtis, Burgina, Rogov, Sobyanin, Parmon.     

Theoretical Optimization of Neutron and Physical Characteristics of a Multiplying Pulsed Neutron Source Based on a Proton Accelerator

Physics of Particles and Nuclei Letters - The neutron source operating at the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research (JINR, Dubna, Russia), based on an IBR-2M...