Modeling of the Concentration Field of Solid Phase in a Hydrocyclone in Suspension Separation by Pressure Flotation

A mathematical model of suspension separation by pressure flotation in a hydrocyclone was developed. The continuity equation was solved numerically for a flux of particles of the solid phase in a flow of a non-Newtonian suspension in a hydrocyclone. The concentration field of solid particles was determined. The effect of the defining similarity criteria on the distribution of concentrations was studied.     

Kinetic model for hydrocarbon synthesis from CO and H2 accounting for its intragroup distribution

A method to describe a multicomponent process of hydrocarbon synthesis from CO and H₂ over iron catalysts and a kinetic model to calculate the intragroup distribution of up to C₂₀ hydrocarbons, are suggested. Values for the kinetic parameters are presented.

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CO H₂ . , C₂₀, .

     

Kinetic investigation of CO oxidation in the presence of SO2

The kinetics of CO oxidation on a mixed, Pd-containing catalyst have been studied by the gradientless method. The reaction rates were measured as a function of the temperature and the CO and SO₂ concentrations. A break has been found on the kinetic curves, showing the influence of CO concentration on the reaction rate.

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CO . — , CO .

     

Kinetic models of CO oxidation on Pd-containing catalysts (with and without SO2)

The effect of reactants and experimental conditions on the Pd/C catalyzed oxidation of DS at 110–150°C and 0.3–1.0 MPa in alkaline aqueous solution is described with emphasis on the maximal reaction rate, yield of DGA and catalyst deactivation. Oxygen causes practically irreversible deactivation of catalyst.

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DS Pd/C 110–150°C 0.3–1.0 . , DGA . .

     

Simplest model of catalytic oscillator

The simplest mathematical model for self-oscillations in catalytic reactions whose mechanism includes the steps: 1)ZX; 2) X+2Z3Z; 3) ZQ, is described.

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, : 1. ZX; 2. X+2Z3Z; 3. ZQ.

     

Directionality and mode structure of radiation of semiconductor lasers with electron-beam pumping

We present results of investigations of the directionality diagram and mode structure of radiation of semiconductor lasers with electron pumping that have microrelief reflectors instead of a blind mirror and output mirrors, whose coefficient of reflection depends on the wavelength and the angle of light propagation. Application of such mirrors allows one to narrow the spectrum of output radiation of the lasers, simultaneously reducing the threshold and increasing the output power. The discovered multilobe structure of the directionality diagrams is explained on the basis of geometrical optics. The possibility of controlling the directionality of radiation depending on the spectral and angular characteristics of the output mirror is shown. Reported at the Second International Scientific and Technical Conference on Quantum Electronics, Minsk, November 23–25, 1998. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 5, pp. 092–697, Septemter–October, 1999.     

Structure and Physicochemical Mechanisms of Interaction of Bone Tissue with Titanium Implants in Cases of Tuberculous Osteitis

Technical Physics - The structural and physicochemical mechanisms of interaction of bone tissue with titanium implants under conditions of tuberculous osteitis are studied using scanning electron...     

A Nonlinear Electric Model of the Transient Photoelectric Current in an Organic Photodiode

One of the possible causes of the degradation of organic photodiodes is explained in terms of a nonlinear resistance–capacitance model. Electronic switches for switching photodiode parameters when light is turned on and off are used as nonlinear elements in the equivalent circuit. The model treats the photodiode as a spatially localized photovoltage generator loaded on a passive four-terminal device connected with the electrodes through passive interface layers. The presence of passive layers that have areas with oppositely directed built-in pulling electric fields is the main cause of the degradation of photodiode characteristics. The proposed equivalent circuit well reproduces the experimental transient and steady-state processes in organic photodiodes and can be useful both for measuring the electrical parameters of photodiodes and for studying the processes leading to their degradation.