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排序方式: 共有92条查询结果,搜索用时 17 毫秒
1.
V. V. Kuznetsov S. V. Dimov A. S. Shamirzaev 《Journal of Engineering Thermophysics》2017,26(3):353-358
The paper presents the results of an experimental study of heat transfer in boiling of refrigerant R-21 in a downward flow in a vertical assembly of minichannels of a plate-fin heat exchanger. Characteristic regimes of vapor-liquid flow and heat transfer coefficients have been obtained for the case of plain fins in the ranges of low mass velocities and heat fluxes that are typical of the industry but poorly studied. The obtained data show no significant dependence of the heat transfer coefficient on the heat flux density and mass velocity, which may be explained by the decisive effect of the evaporation of thin liquid film on the heat transfer at low heat flux density. 相似文献
2.
Filtration of a microsuspension of aluminosilicate particles in a highly-permeable porous medium formed by a glass-sphere
filling is investigated. The particle-to-filling granule diameter ratio varied from 0.046 to 0.109 and the volumic particle
concentration ratio from 0.001 to 0.02. The data on the specimen permeability dynamics and its dependence on the initial concentration
of the suspension microparticles and the ratio of their diameter to that of the porous medium granules are obtained. The permeability
is shown to considerably vary along the specimen. Two stages of the porous medium damage by the trapped microparticles are
established. The critical parameter of the formation of an impermeable cake in the initial region of the specimen are determined. 相似文献
3.
4.
In order to neutralize beams of high-energy negative ions, it is convenient to use a plasma target. It is necessary to confine a target plasma within a magnetic trap. It is of importance to restrict the escape of a plasma from the inlet and outlet holes in the target. It is proposed to confine a target plasma in a magnetic trap with a weak longitudinal field with circular multipole walls and with inverse plugs (with an inverse field). Experiments in which a plasma is confined in an axisymmetric trap of this type with one double inverse plug, which restricts longitudinal plasma outflow, are described. A cathode pellet emitting accelerated electrons for plasma production by gas ionization is installed at the opposite end face of the trap on the axis. The experiment shows that inverse plugs suppress strongly the plasma outflow into the end-face hole. The mechanism of this suppression is revealed. It is found that electrons are confined within a trap predominantly by magnetic fields. 相似文献
5.
Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 3, pp. 166–174, May–June, 1989. 相似文献
6.
Kyril Dimov Pavel Pavlov 《Journal of polymer science. Part A, Polymer chemistry》1969,7(10):2775-2792
The possibility of obtaining modified cellulose products by reacting cellulose xanthogenate in solutions containing oxidizers and acrylonitrile was studied. The ability of the cellulose xanthogenate–hydrogen peroxide redox system to initiate graft copolymerization of acrylonitrile on the cellulose was demonstrated. The influence of various factors on the processes was investigated. An attempt was made to clarify the nature of the reactions involved. 相似文献
7.
8.
K. Dimov E. Terlemezyan 《Journal of polymer science. Part A, Polymer chemistry》1972,10(11):3133-3141
Products of pre-esterification of dimethyl terephthalate with ethylene glycol at various times carried out with two catalysts, i.e., calcium acetate and a mixture of manganese and sodium acetates, were studied. Thin-layer chromatography was used to follow the fundamental reaction and determine the type and degree of oligomerization. It was established that the manganese–sodium acetate mixed catalyst is more efficient both with regard to pre-esterification and oligomerization. 相似文献
9.
Summary The separation of C1–C4 mononitroalkanes on four wall-coated glass open tubular (capillary) columns (liquid phases: OV-101, Ucon-LB-550X, NPGS and Carbowax 20M) was investigated. Retention indices were determined and the influence of the different factors (analysis temperature, method of determining the gas holdup time and the nature of the stationary phases) on their reproducibility were studied. Linear regression equations permit the pre-calculation of the retention indices of C1–C4 mononitroalkanes from their properties on all liquid phases studied. 相似文献
10.
We consider quantum Hall states at even-denominator filling fractions, especially nu=5/2, in the limit of small Zeeman energy. Assuming that a paired quantum Hall state forms, we study spin ordering and its interplay with pairing. We give numerical evidence that at nu=5/2 an incompressible ground state will exhibit spontaneous ferromagnetism. The Ginzburg-Landau (GL) theory for the spin degrees of freedom of paired Hall states is a perturbed CP2 model. We compute the coefficients in the GL theory by a BCS Stoner mean-field theory for coexisting order parameters, and show that even if repulsion is smaller than that required for a Stoner instability, ferromagnetic fluctuations can induce a partially or fully polarized superconducting state. 相似文献