Substrate-dependent optical absorption characteristics of titanium dioxide thin films

We used the electron-beam evaporation method in various oxygen partial pressure environments to deposit TiO(2) thin films on various glass substrates at 300 degrees C. We found the threshold oxygen partial pressures above which the film is transparent are different for films on various substrates. Below the threshold oxygen partial pressure, the refractive index and the extinction coefficient of the films varied from substrate to substrate. The films on substrates with higher threshold oxygen partial pressure were associated with a higher extinction coefficient and a higher growth rate. These phenomena are correlated with the appearance of rutile phase in the anatase phase, which is also correlated with variations in the Al(2)O(3) and Na(2)O content in the substrates. The Al(2)O(3) content in the substrate tends to enhance the formation of rutile phase in the film and to give a higher extinction coefficient for the film, while the Na(2)O content in the substrate tends to retard the rutile formation in the film and to give a lower extinction coefficient for the film.     

银掺杂的半导体氧化物二氧化碳传感器研究

报道了银掺杂的半导体氧化物CuO-BaTiO_3对CO_2的敏感特性。分析了Ag掺杂量对CuO-BaTiO_3灵敏度的影响。Ag掺杂量不仅影响CuO-BaTiO_3对CO_2是的灵敏度和工作温度,还影响材料在空气中的电阻值。通过适当量的Ag掺杂提高了CuO-BaTiO_3的化学活性,增强了对CO_2的吸附和反应,使传感器对CO_2的灵敏度提高。银掺杂的CuO-BaTiO_3传感器对CO_2的检测范围为1.0×10~(-4)到10％,最小检测浓度为1.0×10~(-4)。还对银掺杂后的稳定性进行了分析。     

Mathematical modeling of high-temperature thermophysical characteristics of rubber-like thermal protection materials

Based on analyzing and generalizing results of theoretical and experimental investigations of main regularities of heat transfer in the thermal protection of the combustion chamber, the mathematical and computer models of high-temperature characteristics of rubber-like thermal protection materials are formulated. The distinctive feature of the models is taking into account the change in the composition and structure of the destructing material in the process of heating up to high temperatures. Results of the numerical simulation satisfactorily agree with experimental data.     

Decomposition characteristics of carbon dioxide by gas tunnel-type plasma jet

The increase of warm-room gas is thought to cause the rise of atmosphere temperature, which is called the warm-room effect. Therefore, the decomposition treatment of carbon dioxide (CO₂) gas is an important research subject in order to solve the global environmental problem. In this study, a high-energy plasma process was used to decompose CO₂ gas as a warm-room gas, and the decomposition mechanism was clarified by varying the plasma operation conditions. The possibility of transforming of the CO₂ gas to various resources was also discussed. Firstly, the performance test of the gas tunnel-type plasma jet used for decomposition of CO₂ was conducted, and decomposition characteristics of CO₂ gas by the gas tunnel-type plasma jet was determined under various conditions. The decomposition ratio of CO₂ was about 30%, when the power input was P=8 kW, and the CO₂ content in argon was 10%. Secondly, the improvement of operating conditions of the plasma jet was discussed in order to enhance its performance.     

Mathematical modeling and numerical simulation of flow characteristics in an upflow reactor

Abstract

Determining and modeling of the extent of a treatment process in a reactor require knowledge of the flow characteristics. Residence time distribution (RTD), hydrodynamic dispersion coefficients, and velocity distribution are three important terms. Velocity distribution can be measured by a laser doppler anemometer (LDA) accurately, but RTD and hydrodynamic dispersion coefficients must be analyzed by mathematical modeling and dye testing. In this paper, the mathematical modeling and numerical simulation of a upflow reactor are developed. Rhodamine B and a fluorometer are used in laboratory testing. By applying the Euler FTCS (forward‐time‐center‐space) finite‐difference method, the results of dye tests and convection‐dispersion models are compared. The relationship between hydro‐dynamic dispersion coefficients and flow rates is discussed.     

Emissivity of carbon dioxide

This paper presents a new correlation for the emissivity of carbon dioxide gas, suitable for extrapolating existing nomograms to large optical thickness values and high temperatures.     

Mathematical modeling of particle growth

Continuity equations for particle distributions by size and residence times are considered in processes associated with particle growth. The relation between these equations and the particle-balance equation in phase space is shown.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 32, No. 2, pp. 346–349, February, 1977.     

Mathematical modeling of the process of sublimation drying

A complex physicomathematical analysis of vacuum sublimation drying has been given. Approaches to calculation and designing of sublimation dryers have been proposed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 1, pp. 48–55, January–February, 2006.     

Mathematical modeling of the process compaction of wood

Within the framework of the mechanics of heterophase systems a mathematical model for the process of pressing wood has been offered; this model takes account of the influence of its complex rheological properties and surface phenomena in thin interlayers of water on the change in a porous structure. With numerical methods, a study has been made of the influence of the sample’s humidity and temperature fields on the strength and quality of the material obtained. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 5, pp. 62–69, September–October, 2005.     

Mathematical modeling of the rheology of swelling systems

Consideration is given to a mathematical model of the rheology of swelling systems, the basis for which is provided by generalization of the filtration-consolidation theory to the case where the mass of the solid phase of a porous skeleton changes due to the flow of a fluid during the swelling and shrinkage processes under the action of osmotic pressure. The problem on swelling and shrinkage of a clay layer has been formulated and solved. The features of the model, which are important for explanation of certain characteristic features of the processes in swelling systems, have been investigated based on an analysis of the solution. It has been shown that the solutions obtained are in good agreement with experimental results. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 6, pp. 93–99, November–December, 2005.     

Mathematical modeling of natural-gas production systems

It is proposed that a gas-bearing bed and a well be considered a single system. It is demonstrated that the equation of state of an imperfect gas can be linearly approximated. Institute of Physicochemical Problems of the North, Siberian Branch of the Russian Academy of Sciences Yakutsk, Russia. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 4, pp. 540–544, July–August, 1996     

Mathematical modeling of river ice processes

River ice processes involve complex interactions between hydrodynamic, mechanical, and thermal processes. River ice research has largely been driven by engineering and environmental problems that concern society, including ice effects on flooding, hydropower, navigation, ecology, and the environment. Important findings on river ice research before 1980 have been summarized by Ashton (1986) and Donchenko (1987). Significant progress has been made in river ice research in the last three decades. Mathematical modeling has been an essential part of this progress. Mathematical models have been developed for various river ice processes. They not only helped to advance understanding of the physical processes by complementing field and laboratory studies, but also provided tools for planning and design of engineering projects. In this paper, models of various river ice processes during the winter, from freeze-up to breakup, are reviewed after a brief overview of river ice phenomena. Following the discussion of these ‘component’ models, a discussion on ‘comprehensive’ models and an analytical framework which links all river ice processes in a coherent manner is presented.     

Mathematical modeling of laser-induced diffusion processes

The possibility of using lasers to form semiconductor materials (cadmium and mercury tellurides) with a predetermined width of the band gap was explored using mathematical modeling. A one-dimensional physicomathematical model based on diffusion and heat conduction equations and transport equations for laser radiation with temperature- and concentration-dependent coefficients was used. Self-similar solutions were used in order to obtain certain qualitative regularities of the processes. In the general case the corresponding system of partial differential equations was integrated numerically. Institute of Mathematical Simulation, Russian Academy of Sciences, Moscow. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 2, pp. 194–205, March–April, 1996.     

Mathematical modeling of jet volcanic eruption

Results of mathematical modeling of the evolution in the atmosphere of jet-eruption products with the prescribed physical parameters in the outlet section of the volcano crater are reported. Consideration has been given both to low-power eruptions (the most typical ones) and to eruptions of intermediate and high power (catastrophic).     

Mathematical modeling of flows from canals

In the hydrodynamic formulation, two-dimensional steady filtration in homogeneous isotropic ground from canals through a soil layer to the underlying highly permeable pressure water-bearing stratum is considered in the presence of the ground capillarity and evaporation from the free surface. To study filtration, a combined multiparametric boundary-value problem of the theory of analytical functions is formulated, which is solved using the P. Ya. Polubarinova-Kochina method and procedures of conformal mapping of regions of a special kind that are characteristic of the problems of subsurface hydromechanics. On the basis of this model an algorithm of calculating the capillary water spreading and the filtration discharge is developed for the situations where in water filtration from canals provision is made for the ground capillarity, evaporation from the free-surface of groundwater, and the additional pressure from the side of water of the underlying wellpermeable bed. With the aid of the obtained accurate analytical relations and numerical calculations a hydrodynamic analysis is made of the structure and character of specific features of the modeled process as well as of the effect of all physical parameters of the scheme on the filtration characteristics.     

Mathematical modeling of the inductional tempering of steel samples

Complete mathematical modeling of processes of inductional tempering in various inductors is performed on a computer. Using regularizing algorithms, the problem of heat control and the problem of purposive control are solved.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 43, No. 6, pp. 955–960, December, 1982.