Abstract
The results of a direct numerical simulation are presented which describe the specific process of a porous medium high-temperature siliconizing. The calculations were performed taking into ...account the diffusion, the weak pressure gradient across a workpiece and the heat release during the condensation of gaseous silicon in pores. Phenomenological formulas for the evaporation and condensation coefficients in dependence on temperature are offered. An evolutionary equation for the temperature distribution in a sample is derived, which takes into account these processes. Mathematical statement of the problem is based on the modified MIM-model with addition Darcy’s law. Numerical modeling has been fulfilled by the finite difference method using an explicit scheme. It is shown that the heating release in the sample slows down the process of particle settling. The results of numerical simulation are consistent qualitatively with known experimental data.
Smooth hydrocarbon films formed on the vacuum chamber walls in tokamaks under the erosion of graphite elements during deuterium plasma discharges are the main accumulators of hydrogen isotopes in ...carbon matrices. Therefore, they can be considered as a promising material for hydrogen storage applications. In the present work, such hydrocarbon CD
x
films (x ∼ 0.5) produced in T-10 tokamak (NRC Kurchatov Institute, Russia) were studied using scanning electron microscopy (SEM), NEXAFS and EXAFS spectroscopies together with thermal desorption (TD) for the films' characterization and estimation of their hydrogen storage capacity. The C 1s X-ray absorption spectra of the CD
x
films were recorded for the first time using the BESSY II storage ring facility (Germany). The obtained NEXAFS spectra were found typical for CK-spectra of sp
3
+ sp
2
hydrocarbon systems with a high H/C ratio. The role of Fe impurities from the tokamak chamber walls was elucidated as a catalytic effect "facilitating" the thermal desorption of hydrogen (deuterium) from CD
x
films. The Fe K-edge spectra allowed to confirm a fractal (self-affined) structure of CD
x
films, with a minimal sp
2
fractal aggregate ∼2-3 nm, and formation of 3D carbon sp
3
+ sp
2
network, accumulated a large number of H-isotopes and C
x
H
y
hydrocarbons. It was found that the H storage and thermal desorption properties of the CD
x
films can be improved by their inherent Fe impurities, capable to reduce the barrier of TD and to increase the H/C storage capacity by several times even at room temperature.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
Abstract
The article presents the results of research in the field of diagnostics of a traction electric motor of the 1DT.003.11 type of the alternating current electric train of the EP3D series by ...simulating emergency modes of functioning of the fuzzy logic of a modular dynamical neural network. It is proposed to solve the problems of assessing the reliability of traction electric motors in railway transport with an increased service life using simulation modeling of the ANFIS modular neural network in the MATLAB package. The result of modeling the statistical diagnostic parameters of the traction motor is an assessment of the change in the linguistic coefficients of the residual life of the traction motor of the EP3D electric train and recommendations for the maintenance of traction electric motors, depending on their technical condition at the current time of operation.
Cold flow simulation of Pobeda furnace bubbled bath hydro-gas dynamics was performed using a bottom gas-protected lance. It was shown that gas infusion into liquid at Archimedes criterion Ar = 5–60 ...is carried out in the pulse-coupled regime. The area of gas and liquid interaction was investigated at Ar = idem for separated and united air egress through ring and round nozzles. At all considered values of Ar, a two-phase zone was formed in liquid that was composed of “leg” with different geometrical shape, cavity, and gas-liquid layer over the bath surface. Characteristic features of blowing zone formation, flame configuration, and its structure in relation to the blow injection configuration and Ar values were found. It was detected that, at intense blowing through the lance center and ring gap, an ejected liquid prevailed in the cavity structure, the content of which increased upon increase in gas consumption in shell, but near the nozzle face, the “leg” is composed of the gas phase. A hypothesis was formulated that the presence of an additional amount of sulfide melt in oxidative streamline provides more complete magnetite destruction in the bath volume and at close proximity of the nozzle provides formation of a protective coating. The sizes of the most indicative geometrical areas of flame were quantified, which gave evidence about periodic and extreme behavior of jet spread in liquid. Empirical equations of the relation between maximum linear and across “leg” sizes at dynamical conditions of blow injection in shell (Ar
shell
) and central tube (Ar
c
) are obtained for two values Ar
shell
≥ Ar
c
and Ar
shell
≤ Ar
c
. It was estimated that blow injection in shell increases extension velocity of the “leg” on the nozzle face to 137 mm/s. The dependence of average height (
H
avg
, m) of splash lift over calm bath surface was defined, which at 25 ≥ Ar
shell
≥ 5 and 60 ≥ Ar
c
≥ 12 has the form
H
avg
= 0.027(Ar
shell
+ Ar
c
)
0.27
. Using Schlichting’s equation, a value of maximum offset from the nozzle surface where cooperative axial movement in liquid of ring and round flow with isovelocity is preserved is calculated. It is proposed that a protective effect of bottom lance with shell appears in the lance belt area over a distance of 7–10 cm from the nozzle surface. The cavity after separation from the nozzle moves down vertically, but countercurrent liquid flow bounding on the cavity front moves in the opposite direction, flowing around the phase interface with comparable velocity. On the basis of more intense change in the transverse size of the interaction zone in the nozzle area and noticeable sideways liquid movement, it was recommended to take corrective action for decreasing the action of melt erosion in the lance belt of the Pobeda furnace on the entrance region of flow development.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The adsorption and protective properties of the corrosion inhibitors SolIng IK-2, IK-3, and IK-4(A) are studied by the method of electrochemical impedance spectroscopy. It is found that these ...inhibitors efficiently protect against corrosion in 1 M HCl solution. The calculated degrees of surface filling indicate a high adsorption capacity of the studied compounds, which strongly depends on their composition. SolIng IK-2 and IK-4(A) are the most effective compositions exhibiting a high degree of surface filling already at low concentrations (at concentrations up to 0.025 g/L θ = 0.6–0.98).
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The results of the study of the properties and structural features of amorphous hydrocarbon films CD
x
(
x
~ 0.5) obtained in the plasma discharge of the T-10 tokamak are presented, which ...characterize these films as a hydrocarbon system with carbon
sp
3
+
sp
2
states (mainly with
sp
3
states). The films form a branched three-dimensional fractal carbon network with a fractal structure and a high specific surface. Such a CD
x
system facilitates accumulation and storage of both hydrogen isotopes and hydrocarbons in a stable state. Its desorption characteristics can be improved by the catalytic effect of iron impurities.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The electrical properties of C
60
F
18
fluorofullerene molecules with a high electric dipole moment during their physical adsorption on various surfaces were studied in order to investigate the ...possibility of creating interfaces with specified physical and chemical characteristics and controlling their properties. Spatial maps of the electrostatic potential and electric field strength of a single molecule were obtained. The distribution of the electrostatic potential of single-layer and multilayer, close-packed and sparse, as well as ordered and disordered ensembles of fluorofullerene molecules C
60
F
18
earlier observed in experiments, and their effect on the substrate were modeled using the density functional theory. The calculations confirmed the experimentally established splitting of the F1
s
level in an electric field directed along the axis of symmetry of the molecule (linear Stark effect). Based on the nature of the interaction of the adsorbate molecules with the substrate and with each other, the influence of collective electrostatic effects on the monolayer structure and the shift of the core electronic levels, conclusions were drawn about the presence of local electric fields above the island film and in the near-surface region of the substrate, and the film growth process. The results of this study can be used to interpret the electrostatic potential distributions obtained by scanning quantum dot microscopy.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Despite certain achievements in care provision to those with severe chest injury the problem of managing flail chest is far from being resolved. Traditional management includes forced continuous ...artificial pulmonary ventilation in order to provide internal pneumatic stabilization of the chest. However the results of this approach can not be recognized as satisfactory due to high frequency of complications, need for tracheostomy, long-term stay of such patients in the intensive care department, development of nosocomial infections.Early restoration of the chest carcass with the help of costal valve fixation by the plate with angular stability allows reducing the duration of the artificial pulmonary ventilation and decreasing the frequency of potential respiratory and pleural complications.
The air fluorescence telescopes are one essential part of the Pierre Auger Project, currently under construction in Argentina. With a pixel camera of 440 photomultiplier tubes the telescopes observe ...fluorescence light induced by cosmic ray extensive air showers passing through the atmosphere. In this paper we report on a method to monitor the dc anode current in each photomultiplier by statistical analysis of the signal fluctuations. The method has in our case the advantage that we were able to implement it using free resources of FPGA logic; therefore no additional electronics is required. We present details of the current monitor design and its performance measured with a prototype device.
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