Физико-механические характеристики композита на основе полиимидной матрицы, наполненной оксидом вольфрама
The erosion coefficients of W-Cu composites, tungsten, and copper are determined experimentally for conditions simulating plasma collapse, with a mean hydrogen-particle energy of around 2 keV. The microrelief variation of the composite surface under the action of single and repeated plasma pulses of length 15-20 μsec is investigated, with a heat-flux density of (5-7)·106 W/cm2.
The article presents some results of the investigation into the conceptual basis of semantics of the English adjectives comprising the lexical category “Mental characteristics of human beings”. A case study of compound adjectives shows that the conceptual basis of their semantics is formed, in particular, by space conceptions that reflect humans’ ontological knowledge and are realized through the conceptual metaphor “container”. This research revealed that this metaphor underlies the semantics of the majority of the compound adjectives in question. The head-word semantics is based on the concept CONTAINER, which is verbalized via eight substantive stems (head-, pat-, brain- etc). The container is believed to possess certain properties, which are verbalized via the second element of the compounds. The quality of humans’ mental activity is associated with the container properties. As the examples demonstrate, the following parameters of the container are projected on the target domain of human beings mental characteristics: size, weight, thickness of the shell, substance physical qualities. Corruption of these is seen as the reason of inability to understand or memorize new information, in particular: smaller size of the container, excessively thick shell, excessively high/low weight of the substance, wrong substance. The field of negative mental characteristics is nominated more rigorously and meticulously: the number of these compounds is twice that of the compounds with positive mental characteristics.
The behaviour of sandwich structures of cold cathodes has been studied in a glow discharge. The differences in the behaviour of the cold-cathode composite structures under the action of a glow discharge in a helium-neon mixture are discussed.
In this paper it has been studied an effect of vacuum ultraviolet (VUV) irradiation at different temperatures on microstructure of polystyrene composites filled with organo-siloxane filler. It has been shown that the combined effects of vacuum and vacuum ultraviolet irradiation on the test materials result in a slight changes of surface layers. Irradiation at cryogenic temperature results cracks formed on the surface. It is suggested that the introduction of organo-siloxane filler lowers the operating temperature of the composite up to -170 º C, with damage to the surface layer of a thickness of 10 microns. Investigation of the evolution of the surface relief patterns has been performed. It has been shown a smoothing of the surface relief under influence of VUV.
Mechanical performances of titanium biomedical implants manufactured by superplastic forming are strongly related to the process parameters: the thickness distribution along the formed sheet has a key role in the evaluation of post-forming characteristics of the prosthesis. In this work, a finite element model able to reliably predict the thickness distribution after the superplastic forming operation was developed and validated in a case study. The material model was built for the investigated titanium alloy (Ti6Al4V-ELI) upon results achieved through free inflation tests in different pressure regimes. Thus, a strain and strain rate dependent material behaviour was implemented in the numerical model. It was found that, especially for relatively low strain rates, the strain rate sensitivity index of the investigated titanium alloy significantly decreases during the deformation process. Results on the case study highlighted that the strain rate has a strong influence on the thickness profile, both on its minimum value and on the position in which such a minimum is found.
The ХХV International scientific – technical conference “Foundry 2018” was held of the 18-20 April 2018 at “Rostov” hotel in the city of Pleven, Bulgaria. Its aim is to provide a meeting place for scholars from different countries to present their scientific achievements and to discuss the problems of casting production.
The structural and spectroscopic features of the EuAl3(BO3)4 individual skeletal microcrystals synthesized by a melt solution method have been studied. Their infrared spectra taken from the as-grown microcrystal surfaces mainly contain the lines of the rhombohedral modification of EuAl3(BO3)4 and additional peaks of its monoclinic modification. TEM and X-ray diffraction studies confirm that these additional peaks in the IR spectra belong to the monoclinic C2/c polytype of the EuAl3(BO3)4 compound. We are the first to demonstrate the presence of coherent monoclinic domains in rhombohedral EuAl3(BO3)4 crystals by TEM. Cathodoluminance spectroscopy shows that the microcrystals generate strong emission lines in the range 580–630 nm, and their intensities are strongly influenced by the crystal orientation.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.