SSI-2021: Scientific Services & Internet

We present a collection of selected materials from the All-Russian Conference "Scientific Services & Internet (SSI-2021), which took place on September 20-23, 2021 at Keldysh Institute of Applied Mathematics in Moscow, Russia. However, because of the worldwide COVID-19 crisis, SSI-2021 had to take place online. The issues discussed at the conference include: digital libraries, information systems, knowledge representation, national bibliographic systems, ontology engineering, parallel computing, Semantic Web, situational modeling

Wikidata in Metadata Formation Methods for Documents of Digital Mathematical Library

Methods for the formation of digital collections of a digital mathematical library are presented. With the help of tools for analyzing the structure of documents and their style features, the main set of document metadata has been formed. For each document, this set includes the title of the article, a list of authors, and a list of cited bibliography. To supplement the metadata, methods of extracting knowledge from Wikidata were used. With the help of the developed system of SPARQL-queries, the search and refinement of data on documents of the collections was carried out. In particular, information about the authors of the articles has been added (full spelling of surnames, first names, patronymics in various languages, place of work at the time of writing the article, etc.). In addition, methods are proposed for refining and supplementing bibliographic references given in the articles. When forming metadata of retro collections, a search was made in Wikidata for information about the years of life of authors of articles, URLs of web pages with information about articles and their authors. The results of the several digital collections formation, which are included in the digital library Lobachevskii-DML, are presented

Quasisolutions of Inverse Boundary-Value Problem of Aerodynamics for Dense Airfoil Grids

In the process of turbomachinery development, it is of great importance to accurately design impellers and select their blade shape. One of the promising approaches to solving this problem is based on the theory of inverse boundary-value problems in aerodynamics. It helps to develop methods for profiling airfoil grids with predetermined properties in the same way as it is done for isolated airfoils. In this paper, methods have been worked out to find quasisolutions of the inverse boundary-value problem in aerodynamics for a plane airfoil grid. Two methods of quasisolution have been described. The first “`formal” method is similar, in its essence, to the method used for construction of quasisolution for an isolated airfoil. It has been shown that such quasisolutions provide satisfactory results for grids having a sufficiently large relative airfoil pitch. If pitch values are low, this method is unacceptable, because “modified” velocity distribution in some areas is significantly different from the original one in this case. For this reason, areas with significant changes in the angle of the tangent line appear in the airfoil contour and the flow region becomes multivalent. To satisfy the conditions of solvability in the case of grids having a small airfoil pitch, a new quasisolution construction method taking into account the specifics of the problem has been suggested. The desired effect has been achieved due to changes in the weighting function of the minimized functional. The comparison of the results of construction of the new quasisolution with the results obtained by the “formal” method has demonstrated that the constructed airfoils are very similar when the pitch is large. In the case of dense grids, it is clear that preference should be given to the second method, as it brings less distortion to the initial velocity distribution and, thus, allows to physically find an actual airfoil contour

Influence of Bernstein modes on the efficiency of electron cyclotron resonance x-ray source

The article considers the factors influencing the temperature of hot electron component in an electron cyclotron resonance (ECR) x-ray source. In such sources the electron heating occurs often due to extraordinary electromagnetic wave propagating perpendicularly to the magnetic field. In this case the possibility of the absorption of Bernstein modes is regarded as an additional mechanism of electron heating. The Bernstein modes in an ECR x-ray source can arise due to either linear transformation or parametric instability of external transversal wave. The article briefly reviews also the further experiments which will be carried out to study the influence of Bernstein modes on the increase of hot electron temperature and consequently of x-ray emission. © 2006 American Institute of Physics

Influence of Bernstein modes on the efficiency of electron cyclotron resonance x-ray source

The article considers the factors influencing the temperature of hot electron component in an electron cyclotron resonance (ECR) x-ray source. In such sources the electron heating occurs often due to extraordinary electromagnetic wave propagating perpendicularly to the magnetic field. In this case the possibility of the absorption of Bernstein modes is regarded as an additional mechanism of electron heating. The Bernstein modes in an ECR x-ray source can arise due to either linear transformation or parametric instability of external transversal wave. The article briefly reviews also the further experiments which will be carried out to study the influence of Bernstein modes on the increase of hot electron temperature and consequently of x-ray emission. © 2006 American Institute of Physics