Economical technology for cryoproduct storage and delivery

Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 11, pp. 22–23, November, 1992.     

Self-reinforced materials based on aluminum nitride

Powder Metallurgy and Metal Ceramics -     

Three-dimensional inverse scattering of a dielectric target embedded in a lossy half-space

A modified iterative Born method is applied for three-dimensional inversion of a lossless dielectric target embedded in a lossy half-space. The forward solver employs a modified form of the extended Born method, and the half-space Green's function is computed efficiently via the complex-image technique. Example results are shown, with all scattering data based on a computational model, utilizing a rigorous forward solver distinct from that employed in the inversion. In addition, distinct gridding schemes are used in the forward and inverse solvers. Simple Tikhonov regularization is found to yield adequate results for inversion of noisy data.     

Exciton photoluminescence in doped quasi-1D structures based on silicon

The dependence of carrier density in silicon quantum wires sheathed with SiO₂ on the wire diameter and the position of impurity atoms in respect to the wire center is analyzed theoretically. It is shown that, as the diameter of wires and nanocrystals decreases, the ionization energy of a dopant increases; therefore, the free carrier density decreases, and the screening of the Coulomb attraction becomes ineffective. As a result, the photoluminescence is defined by the radiative recombination of excitons even in the case of heavily doped Si. These conclusions are supported by the data of experimental study of spectral, excitation-power, and temperature dependences of photoluminescence in porous silicon structures fabricated on lightly and heavily doped Si substrates.     

PIK-2 Reactor with a Low Consumption of High-Enrichment Uranium

Calculations of the possibility of switching the matrix of the fuel-element cores and the vessel with the reactor envelope to weakly neutron-absorbing aluminum and lowering at the same time the fuel content in the fuel elements by 40% are performed for the high-flux PIK reactor which is under construction in Gatchina. As a result, the flux density of the thermal neutrons in the heavy-water reflector increases by a factor of 1.4–1.5 and the maximum unperturbed flux reaches a world record value – 1.9·10¹⁵ sec^–1·cm^–2. The nonuniformity of the volume energy-release decreases to 2.3. The weight of the control rods and reactor safety increase. As a result of the decrease of the fuel content in the fuel elements and the increase of the run duration, about 60 kg of high-enrichment uranium ²³⁵U are saved annually, decreasing annual fuel costs by one third.     

Specifics of initial steam condensation and its influence on corrosion damage in turbines

Processes of corrosion cracking of the metal of turbine blades in the region of initial steam condensation are considered. Possible ways of preventing corrosion-fatigue damage to the blades are proposed.     

对交通预测工作的几点看法

近来,随着一些重大工程的建成使用,提高了上海交通设施的服务能力,使交通格局发生了一些变化,交通状况也出现了新的特点。但同时也发现,有些新的交通设施的使用情况与规划设计存在着一定的差异。因此,有关部门开展了一些项目的后评估工作,以总结经验,并为今后工作提供依据。交     

CFD Simulation of Liquid Film Flow on Inclined Plates

A two‐phase flow CFD model using the volume of fluid (VOF) method is presented for predicting the hydrodynamics of falling film flow on inclined plates, corresponding to the surface texture of structured packing. Using the proposed CFD model the influence of the solid surface microstructure, liquid properties and gas flow rate on the flow behavior was investigated. From the simulated results it was shown that under the condition of no gas flow the liquid flow patterns are dependent on the microstructure of the plates, and proper microstructuring of the solid surface will improve the formation of a continuous liquid film. It was also found that liquid properties, especially surface tension, play an important role in determining the thin‐film pattern. However, there are very different liquid film patterns under the action of gas flow. Thinner liquid films break easily, but thicker liquid films can remain continuous even at higher gas flow rates, which demonstrates that all factors affecting the liquid film thickness will affect the liquid film patterns under conditions of counter‐current two‐phase flow.     

十年磨一剑——记上海上大玲珀化工科技有限公司董事长朱勇强

穿着朴实，谈吐文雅，举止端庄，从他富有表情的脸上和那对炯炯有神的眼睛，折射出一个青年科技企业家特有的自信、干练、豁达与刚毅。他，就是上海上大玲珀化工科技有限公司的董事长朱勇强博士。在与他寒喧之际，记者感到朱博士是位思维敏捷、善于开拓、好学求进、富有创新精神和管理才能的既懂技术、又会经营的复合型人才。他谈吐中潜在的智慧、才干和创业的理念使记者佩服。