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991.
A. A. Khrushchinskii S. A. Kuten’ N. M. Budevich V. F. Minenko O. M. Zhukova N. K. Luk’yanov 《Journal of Engineering Physics and Thermophysics》2007,80(6):1170-1177
Measurements of the beta-activity of milk, serving as the main source of information on the radioactive contamination of the
environment by the iodine isotope 131I, carried out on a DP-100 radiometer in the early post-Chernobyl period (1986) in Belarus, have been mathematically simulated.
The results obtained allow the conclusion that the indicated measurements should be analyzed again with consideration for
all of the nuclides present in milk.
__________
Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 6, pp. 102–108, November–December, 2007. 相似文献
992.
V. Sh. Shagapov S. A. Lepikhin M. N. Galimzyanov 《Journal of Engineering Physics and Thermophysics》2007,80(6):1206-1209
A steady flow of a bubble gas-liquid mixture in a nozzle having a circular cross section has been investigated. The possibility
of realization of superhigh temperatures and pressures in the gas phase of the mixture in the region near the smallest cross
section of the nozzle has been analyzed. The influence of the initial radius of the flow and the volume content of bubbles,
determining the volumetric rate of flow of the liquid supplied to the nozzle, on the pattern of the flow has been considered.
__________
Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 6, pp. 134–137, November–December, 2007. 相似文献
993.
V. P. Beskachko O. A. Golovnya A. E. Korenchenko 《Journal of Engineering Physics and Thermophysics》2007,80(1):132-135
The results of a numerical solution of the problem of vibrations of a torsion viscosimeter filled with an incompressible viscoplastic
liquid are presented. It has been shown that in the vicinity of the rotation axis there appears a dead zone, whose boundary
changes in the process of vibrations. The influence of plastic properties of the liquid on the characteristics of viscosimeter
vibrations has been determined. A method for identifying viscoplastic properties by the observed parameters of vibrations
is proposed.
__________
Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 1, pp. 124–127, January–February, 2007. 相似文献
994.
M. V. Filipskii S. T. Surzhikov 《Journal of Engineering Physics and Thermophysics》2007,80(2):284-291
A method and results of numerical modeling of radiative heating of the back surface of the MSRO (Mars Sample Return Orbiter)
space vehicle of the European Space Agency are presented. To determine radiation heat fluxes, the method of discrete ordinates
on unstructured tetrahedral grids is used. The radiative model is based on the radiation-transfer equation in a multigroup
approximation. Numerical calculation has been performed for the most thermally stressed point of the assumed trajectory of
the entry of an MSRO-type space vehicle into the Mars atmosphere. A comparison with the discrete ordinates method on structured
grids is made. Good agreement between the results of calculations on structured and unstructured grids is demonstrated. The
level of radiation heat fluxes to the back surface of the MSRO space vehicle is predicted.
__________
Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 2, pp. 71–78, March–April, 2007. 相似文献
995.
V. A. Sychevskii N. V. Pavlyukevich L. L. Vasil'ev S. Rozin 《Journal of Engineering Physics and Thermophysics》2003,76(1):18-27
A problem of the Stefan type which describes heat and mass transfer in a porous body with the double phase transition liquid–ice–vapor has been formulated and solved. 相似文献
996.
997.
Véronique Baroghel-Bouny Patrick Belin Matthias Maultzsch Dominique Henry 《Materials and Structures》2007,40(8):759-781
Within the framework of the evaluation and the prediction of chloride-induced corrosion risks, simple and rapid AgNO3 spray tests can be proposed for various issues. This paper forms the first part of a series. In this first part, the Maultzsch
procedure (spraying of 0.1-N AgNO3 solution + K2CrO4) as well as the procedure based on the use of a sole AgNO3 solution have been investigated on a broad range of concretes. These procedures have also been compared to the Collepardi
procedure (spraying of 0.1-N AgNO3 + fluoresceine). The feasibility of these colorimetric techniques on saturated specimens cast in laboratory, after non-steady-state
diffusion tests carried out in various conditions, is discussed. In addition, the results obtained from applying such spray
tests in field conditions on cores drilled out from various RC test specimens exposed to a marine environment (tidal zone)
and to a road and cold environment (freezing-thawing cycles and spraying of deicing salts) are presented. Colorimetric methods
have in particular been applied here to the assessment of the average chloride penetration depth and of its evolution versus
time (kinetics). Moreover, the detection threshold of these techniques has been investigated in various environments. The
possible sources of discrepancy on the results have been analysed. 相似文献
998.
Fresh niobium hydroxide was first precipitated from NbF5 solution using an aqueous ammonium hydroxide under basic conditions. Then a simple procedure of mixing lithium and niobium hydroxides together and heating at a low temperature (400 °C) produced pure ultrafine single phase LiNbO3 (LN). In the literature, this is the lowest temperature so far reported on the formation of LN. The phase content and lattice parameters are determined by X-ray diffraction (XRD). The average particle size and morphology were studied by transmission electron microscopy (TEM). 相似文献
999.
V. V. Emtsev P. Ehrhart D. S. Poloskin K. V. Emtsev 《Journal of Materials Science: Materials in Electronics》2007,18(7):711-714
Production processes of electrically active defects in degenerate silicon subjected to 2.5 MeV electron irradiation at T = 4.2 K and T = 300 K have been studied. The production rates of primary and secondary defects in irradiated samples are analyzed on the basis
of the known properties of radiation-produced defects in Si. It has been demonstrated that a striking difference in the production
rates of electrically active defects in n- and p-Si under irradiation at cryogenic temperatures may be related to the different
fate of Frenkel pairs in both materials. The production rate of primary defects in degenerate Si was found to be between 1.5 cm−1 and 2 cm−1. 相似文献
1000.
In this paper we consider A(θ)-stable finite difference methods for numerical solutions of dissipative partial differential equations of parabolic type.
Combining two rational approximation methods with different orders of accuracy, where the lower order method is applied n
0 times (n
0 fixed) at each time step, we prove the existence of a second order method which is contractive for all time steps. Moreover,
we shed light on the conditions on the lower order method which are sufficient (and sometimes necessary) to obtain the optimal
order of accuracy. For the one-dimensional heat equation we construct a family of numerical methods which are contractive
in the maximum norm for all values of the discretization parameters. We also present numerical examples to illustrate our
results.
Received: May 2002 / Accepted: January 2003 相似文献