{"title":"From Texts to Knowledge Graph in the Semantic Library LibMeta","authors":"O. M. Ataeva, V. A. Serebryakov, N. P. Tuchkova","doi":"10.1134/s1995080224602625","DOIUrl":"https://doi.org/10.1134/s1995080224602625","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The problem of constructing a knowledge graph for previously unprocessed scientific texts is studied. The task is to analyze the use of various machine processing methods for extracting text semantics using the example of an interdisciplinary subject area. The goal of the research is to create a semantic model of the subject area of an interdisciplinary scientific journal and use a knowledge graph to navigate through data. The semantic model is based on the ontology of the LibMeta library. Texts and metadata receive connections due to the processing procedure and become part of the ontology of the semantic library. The interdisciplinary subject area is integrated into the library content as a related area of the ‘‘mathematics’’ ontology of the LibMeta library. A comparison of texts is carried out according to different characteristics, thematic proximity, commonality of research methods and approaches, problem setting and their symbolic representation. The results of preliminary text processing and the results in the form of a knowledge graph integrated into the library content are presented. The formulation of the problem of constructing an ontology and a knowledge graph for an interdisciplinary subject area adjacent to mathematics is considered by the authors as part of the general problem of managing mathematical knowledge.</p>","PeriodicalId":46135,"journal":{"name":"Lobachevskii Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142216974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Propagation of Acoustic Waves in a Moving Monodispersed Gas Suspension","authors":"E. A. Teregulova","doi":"10.1134/s1995080224602376","DOIUrl":"https://doi.org/10.1134/s1995080224602376","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>In this work, we study the propagation of plane acoustic waves in a uniformly moving monodispersed gas suspension. A mathematical model was constructed and the dispersion relation was obtained.</p>","PeriodicalId":46135,"journal":{"name":"Lobachevskii Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142217098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Mathematical Model of Asphaltene Deposition During Oil Production","authors":"A. I. Nikiforov, G. A. Nikiforov","doi":"10.1134/s1995080224602303","DOIUrl":"https://doi.org/10.1134/s1995080224602303","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Asphaltenes are heavy hydrocarbon molecules that exist naturally in petroleum reservoir fluids. Asphaltene precipitation may occur during pressure depletion or during gas injection processes to improve oil recovery. Inside the reservoir, the precipitated asphaltene can deposit onto the rock surface or remain as a suspended solid in the oil phase. Precipitated asphaltenes are one of the main causes of decreased permeability. A new approach to modeling asphaltene deposition during oil production has been developed. In the model, oil is represented by two hydrocarbon components (‘‘oil’’ and ‘‘asphaltene’’) that do not dissolve in water and the theory of an ideal solution of a binary mixture is used. Closing relations for the mass and momentum conservation equations describing porosity, permeability and mass transfer are constructed using the pore size distribution function and a model of an ideal porous medium consisting of a bundle of capillaries.</p>","PeriodicalId":46135,"journal":{"name":"Lobachevskii Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142217092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Mathematical Model of Rod Lateral Oscillations Considering an External Tangential Load","authors":"I. V. Kudinov, A. V. Pashin, Yu. A. Kryukov","doi":"10.1134/s1995080224602431","DOIUrl":"https://doi.org/10.1134/s1995080224602431","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A mathematical model has been developed for lateral oscillations of a rod fixed at one end, taking into account internal friction and external tangential harmonic loading. Analysis of the results of numerical calculations has shown that when the natural oscillation of the rod coincide with the external load frequency, resonant oscillations occur, accompanied by significant increase in the amplitude of rod oscillations, limited by the friction coefficient. At load frequencies approaching to the natural oscillation frequency, the amplitude of oscillations at each point of the rod is accompanied by periodic increase and decrease, qualifying them as bifurcation-flutter oscillations (beats). When the amplitude and frequency of the load oscillation change, the rod oscillations occur in the form of wave packets with amplitude-frequency modulation. In general, rod oscillations occur with an infinitely large number of amplitudes and frequencies. The maximum frequency at minimum amplitude is observed in sections of the rod close to the fixed end.</p>","PeriodicalId":46135,"journal":{"name":"Lobachevskii Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142216984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Probabilistic Analysis of the Coefficients of Stochastic Differential Equations in Their Modeling of the Air–Sea Interaction in the North Atlantic","authors":"K. P. Belyaev, N. P. Tuchkova, K. A. Romashina","doi":"10.1134/s1995080224602406","DOIUrl":"https://doi.org/10.1134/s1995080224602406","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The observational data for 1979–2018 in the North Atlantic region\u0000have been used for the analysis of the heat fluxes. The dynamics\u0000of air-sea interaction between ocean and atmosphere has been\u0000modeled by the stochastic differential equation (SDE) which use\u0000the heat fluxes observations taken from those databased. The\u0000coefficients of the SDE represented the diffusion stochastic\u0000process have been statistically defined from the original dataset.\u0000Earlier the existence and uniqueness of the solution in strong\u0000sense of SDE generated by the modeled diffusion process has been\u0000proved. In the current work the drift and diffusion coefficients\u0000have been smoothed and approximated by the trigonometric functions\u0000with sought amplitude and phase characteristics within chosen\u0000year. Their spatial and temporal intra-annual variability of those\u0000characteristics has been studied and analyzed. Also, the\u0000corresponding Fokker–Planck–Kolmogorov (FPK) equation for the\u0000SDE with smoothed coefficients has been constructed and\u0000numerically solved. Numerical calculations realized on the\u0000Lomonosov-2 supercomputer of the Lomonosov Moscow State\u0000University.</p>","PeriodicalId":46135,"journal":{"name":"Lobachevskii Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142216976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Metric Effects in Event Space and Einstein’s Gravitation Theory","authors":"P. A. Belov, S. A. Lurie","doi":"10.1134/s199508022460239x","DOIUrl":"https://doi.org/10.1134/s199508022460239x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A variant of the mechanistic gravitation theory is considered as a 4D theory of elasticity of the event space. A 4D displacement vector is introduced, where the fourth component is the local uneven time of the physical process generating the gravitational field. An analysis of the kinematic model of the mechanistic theory of gravity is presented. It is shown that Einstein’s gravity is a particular theory of the 4D theory of elasticity of the event space with a field of defects. Kinematic models of 4D space-time continuum are proposed, allowing to formulate the variational mechanistic models of gravity. Lagrangian of gravitational field models are formulated for the kinematic variables of a defect-free space–time continuum, continuum with conserved dislocations and a 4D space-time continuum with generated dislocations and conserved disclinations.</p>","PeriodicalId":46135,"journal":{"name":"Lobachevskii Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142216975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Numerical Simulation of Inverse Retrospective Problems for a Two-Dimensional Heat Equation","authors":"S. A. Kolesnik, E. M. Stifeev","doi":"10.1134/s1995080224602583","DOIUrl":"https://doi.org/10.1134/s1995080224602583","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The paper proposes a new, unique method for numerically solving inverse problems for nonlinear conditions using the example of the problem of restoring the initial condition for a two-dimensional heat equation with boundary conditions of the third kind. In this problem, the initial condition is an unknown function of two variables, and is determined from experimental temperature values. The proposed method is based on using the parametric identification method, the implicit gradient descent method and Tikhonov’s regularization method. An algorithm and a software package for numerical solution have been developed. The use of the implicit gradient descent method allowed for faster convergence (number of iterations) compared to zero-order methods. Numerous results of numerical experiments have been obtained and discussed. An analysis of the behavior of solution functions with and without the use of Tikhonov’s regularizing functional along with the impact of the regularizing parameter has been carried out. The results of computational experiments using the proposed numerical method showed that the error in the results obtained does not exceed the error in the experimental data due to the correct choice of the regularizing parameter.</p>","PeriodicalId":46135,"journal":{"name":"Lobachevskii Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142217046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Nonlinear Resonant Gas Oscillations in Resonators with Variable Cross-section","authors":"D. A. Gubaidullin, B. A. Snigerev","doi":"10.1134/s1995080224602170","DOIUrl":"https://doi.org/10.1134/s1995080224602170","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>In a number of studies, it has been shown that the geometry of an acoustic resonator strongly affects its resonant frequencies, as well as the nonlinear shape of the standing pressure waves generated inside the cavity. In this paper, we consider three resonators with different wall shapes (cone, exponential and bulb-shaped resonators) in which gas vibrations are formed due to an external periodic force. The acoustic field in the resonators is generated by the vibration of the left wall of the enclosure. The oscillation frequency of this wall is chosen so that the lowest acoustic mode can propagate along the resonator. The fully compressible form of the Navier–Stokes equations is used, and the explicit time-stepping algorithm is employed for modeling the motion of acoustic waves. The structure of acoustic flows of the second order, resulting from the interaction between the wave field and viscous effects on the walls, leads to the formation of flow patterns. These patterns can be revealed by averaging solutions over a specific period of time. To evaluate the performance of resonators, the pressure amplitude gain factor is used. This is defined as the ratio of pressure amplitude at the small end of the resonator to the pressure amplitude at its large end. It has been found that the best performance is observed in a flask-shaped resonator.</p>","PeriodicalId":46135,"journal":{"name":"Lobachevskii Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142217079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Estimation of Oil Reservoir Transmissivity and Storativity Fields Using a Radial Basis Function Network Based on Inverse Problem Solving","authors":"V. P. Kosyakov, D. Yu. Legostaev","doi":"10.1134/s199508022460225x","DOIUrl":"https://doi.org/10.1134/s199508022460225x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>In the oil industry, there is a noticeable trend towards using proxy models to simulate various levels of complexity in order to make operational predictions. In particular, machine learning techniques are being actively developed in the context of the digitalization and automation of production processes. This paper proposes a method for combining a physically relevant fluid flow model with machine learning techniques to address the challenges of history-matching and prediction. The approach is demonstrated using synthetic oil reservoir models. The synthetic model has significant zonal inhomogeneities in the permeability and storativity fields. The simplified single-phase flow through a porous medium model was used for the proposed approach. This model was matched to the historical values of the development parameters by restoring the fields of the reservoir parameters. Properties fields were reconstructed using a radial basis functions network and a fully connected linear layer. Based on the reconstructed field, interwell connectivity coefficients were calculated, which corresponded qualitatively and quantitatively to the true interwell connectivity coefficients. The predictive characteristics of the proposed approach were evaluated by split the historical dataset into training and test time intervals.</p>","PeriodicalId":46135,"journal":{"name":"Lobachevskii Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142217085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Application of the Wavelet Transform in the Analysis of Non-stationary Processes in Aerodynamic Experiments","authors":"O. E. Kirillov","doi":"10.1134/s1995080224602248","DOIUrl":"https://doi.org/10.1134/s1995080224602248","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The article provides the technique and examples of using the wavelet transform to analyze time series with a non-stationary spectrum obtained in aerodynamic experiments. The peculiarity and novelty of this technique is the definition and use of the concept of wavelet energy as a simpler and more visual function of time, which allows analyzing the evolution of signal energy. As an example, the results of a study of the effect of anomalous passage of a high-frequency signal along a long pneumatic line are presented.</p>","PeriodicalId":46135,"journal":{"name":"Lobachevskii Journal of Mathematics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142217084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}