No abstract available

[en] The passage of low frequency phonons through the liquid ⁴He - aluminium single crystal interface has been studied

[en] This article focuses on the use of mathematical modeling for the calculation of electrical circuits. The Mat Lab software package is selected. A method has been developed for calculating complex electrical circuits by solving systems of linear algebraic equations using the matrix method. An example of the calculation in the Mat Lab package of the currents of the branches and node potentials of an electrical circuit is given. The conclusion was made about the universality of the use of mathematical modeling in technical calculations. (author)

[en] Within the scheme of spontaneously broken symmetry the massive solutions for the model of massless Dirac fields with four-fermion interaction are derived by the method of the Bogolyubov canonical transformations. The solution depends nonanalytically on the coupling constant and cannot be obtained by summing the finite number of the perturbation series diagrams

[en] The results of study of metal-alloyed palladium-barium emitters' of modern very high frequency high-powered electronic vacuum tubes by scanning electron microscopy (SEM) and scanning tunneling microscopy/spectroscopy (STM/STS) are presented. Since the Pd/Ba foil surface is fairly smooth and is not oxidized in air STM/STS investigations are carried out in air in normal laboratory environment. SEM and STM images show that the emitter surface has a complex porous structure. The cathode surface study by STS in tunneling gap modulation mode allowed to take a map of phase distribution with various work function values and high lateral resolution. Obtained images demonstrate the presence of three phases on the Pd/Ba emitter surface, viz. barium-oxygen compounds, intermetallic, and palladium. As it is seen from presented STS image the phase with a low work function value (barium oxides) is concentrated along boundaries of the substance inclusions with work function corresponding to the intemetallic compound Pd₅Ba. This supports the model of low work function areas obtained via Ba segregation from the intermetallic compound and oxidation. The presented methods may be used in the Pd/Ba cathode manufacturing process for increasing the yield of electronic devices in microwave tube production and optimize the emitters' characteristics

No abstract available

[en] Paper presents the results of the estimated analysis of thermal and thermal-stress states of a heat exchanger of a device for localization of WWER-1000 NPP corium melt. One determined the maximum thermal loads and margin for heat exchange crisis for the specific operating conditions. On the basis of calculations of the stress-strained state conducted in two- and three-dimensional terms one determined the areas of development and the values of plastic distortions. The conducted analysis has demonstrated that the values of the critical thermal flows with margin for the specific operating conditions are over the real thermal loads, while the heat exchanger design ensures keeping of its integrity under the specific stress-strained state

No abstract available

[en] The weight function method is described to analyze the crack growth behavior in functionally graded materials and in particular materials with a rising crack growth resistance curve. Further, failure of graded thermal barrier coatings (TBCs) under cyclic surface heating by laser irradiation is modeled on the basis of fracture mechanics. The damage of both graded and non-graded TBCs is found to develop in several distinct stages: vertical cracking→delamination→blistering→spalling. This sequence can be understood as an effect of progressive shrinkage due to sintering and high-temperature creep during thermal cycling, which increases the energy-release rate for vertical cracks which subsequently turn into delamination cracks. The results of finite element modeling, taking into account the TBC damage mechanisms, are compatible with experimental data. An increase of interface fracture toughness due to grading and a decrease due to ageing have been measured in a four-point bending test modified by a stiffening layer. Correlation with the damage observed in cyclic heating is discussed. It is explained in which way grading is able to reduce the damage

[en] The thermal stress and damage analysis of the light water reactor (LWR) vessel is considered in a severe accident conditions. The high temperature corium accumulates on the vessel bottom and necessary condition of its holding is intensive cooling of vessel. External flooding with outside cooling of the LWR vessel is one of the accident management strategies being proposed to ensure the integrity of the vessel after a severe accident. (author). 8 refs., 5 figs