Uchenye Zapiski Kazanskogo Universiteta. Seriya Fiziko-Matematicheskie Nauki最新文献

{"title":"Sensitivity to Initial Data Errors in Interpreting Temperature Logging of an Isolated Injection Well Segment","authors":"K. Potashev, D. R. Salimyanova, A. B. Mazo, A. A. Davletshin, A. V. Kosterin","doi":"10.26907/2541-7746.2024.2.238-249","DOIUrl":"https://doi.org/10.26907/2541-7746.2024.2.238-249","url":null,"abstract":"This study considers the inverse problems inherent in interpreting temperature logging data from an isolated segment of the injection well in order to ascertain its operating period and the thermophysical properties of the oil reservoir.The forward problem of thermal conductivity was reduced to a one-dimensional axisymmetric formulation within the oil reservoir layer, disregarding the vertical thermal exchange with neighboring layers.The inverse problem of determining the well operating period was solved by reformulating the forward problem with regard to the temperature field derivative, which enabled the use of first-order optimization methods. Thus, Nesterov’s method was applied. An algorithm to automatically scale one of the method’s parameters (step length) was developed, and the optimal value of the second parameter (inertial step) was calculated. This increased the efficiency of the method by 10 – 15 % in solving the problem under consideration.The algorithm’s stability against perturbations in the initial data on temperature and thermophysical properties was demonstrated. The sensitivity analysis revealed that a 1 % error in the temperature measurements results in a standard deviation of the solution, which is about 2 % from the true value of the well operating period. A similar level of error was seen when the thermal diffusivity was overor underestimated by approximately 15 %. The solution was little sensitive to variations in the heat transfer coefficient between the oil reservoir and the well at characteristic magnitudes; even with a twofold distortion, the error in the determination of the well operating period did not exceed 1.5 %. To mitigate the error in thermometry interpretation to 1 %, temperature measurements must have an error margin of no more than 0.25 %, alongside precisely specified thermophysical properties of the oil reservoir, or, alternatively, when temperature is measured accurately, the rock thermal diffusivity must be set within an error margin of less than 3 %, but it is nearly impossible under real conditions.Increasing the number of temperature measurements diminishes the sensitivity to measurement errors, with the optimal efficacy achieved at 10 measurements, rendering further increments impractical.Therefore, the algorithm’s stability and the solution’s sensitivity of the inverse problem of determining the reservoir thermal diffusivity for a given operating period of the well relative to temperature measurement errors were found. The results show that a 1 % error in temperature measurements leads to a standard deviation of about 6 % from the true value. ","PeriodicalId":516762,"journal":{"name":"Uchenye Zapiski Kazanskogo Universiteta. Seriya Fiziko-Matematicheskie Nauki","volume":"54 34","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141804655","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":"Experimental and Theoretical Study on the Failure of Sandwich Specimens with Tabs under Four-Point Bending","authors":"V. Paimushin, S. Kholmogorov, M. Makarov, N. V. Levshonkova","doi":"10.26907/2541-7746.2024.2.200-219","DOIUrl":"https://doi.org/10.26907/2541-7746.2024.2.200-219","url":null,"abstract":"The problem of testing sandwich specimens with composite facing layers and a transversally soft core for four-point bending was formulated. The localized external load from the loading rollers to the facing layer of the specimen was assumed to be transmitted through composite tabs, which reduced the stress concentration in the compressed facing layer. The external facing layers and tabs were analyzed for deformation mechanics using S.P. Timoshenko’s kinematic model. The model considered compression in the facing layers but not in the tabs. The core was classified as transversally soft with zero tangential stresses. The tabs were connected to the facing layers through adhesive interlayers, and the displacement vectors of the front surfaces of the tabs were coupled kinematically with the displacement vectors of the front surfaces of the facing layers. The relationships between the transverse shear stresses and strain in the facing layers were assumed to be physically nonlinear, with the shear modulus being a function of the shear strain.Using the generalized variational principle of virtual displacements, a system of nonlinear differential equilibrium equations for the facing layers and tabs was derived. The system was closed by three more equations, which were the conditions for the kinematic coupling of the facing layers with the core based on tangential displacements. To numerically solve the formulated problem, the finite sum method, also known as the method of integrating matrices, was employed. This method involved reducing the original boundary value problem to integro-algebraic equations with Volterra-type operators of the second kind and additional relations for determining the unknown integration constants. The algorithm of the developed method was implemented as an application software, which facilitated a series of computational experiments. The results obtained were compared with the experimental data on the four-point bending of sandwich specimens with the facing layers made of a unidirectional fiber-reinforced composite characterized by specific geometric and physico-mechanical properties, as well as with tabs under the loading rollers. It was shown that the use of tabs significantly increases the ultimate compressive failure stresses in the facing layers.","PeriodicalId":516762,"journal":{"name":"Uchenye Zapiski Kazanskogo Universiteta. Seriya Fiziko-Matematicheskie Nauki","volume":"48 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141805570","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 Aeroelastic Oscillations in the Wall of a Flat Channel Filled with Viscous Gas and Resting on a Vibrating Foundation","authors":"V. Popov, A. A. Popovа","doi":"10.26907/2541-7746.2024.2.220-237","DOIUrl":"https://doi.org/10.26907/2541-7746.2024.2.220-237","url":null,"abstract":"This article considers the problem of aeroelastic oscillations in the channel wall having a suspension with hardening cubic nonlinearity, which were induced by the vibration of the channel foundation. The narrow flat channel formed by two parallel rigid walls and filled with pulsating viscous gas was examined. The bottom wall was stationary, while the opposite one had a nonlinear elastic suspension. The aeroelasticity problem was formulated for the isothermal state of the gas and channel walls. Considering the narrowness of the channel, the equations of dynamics were derived for a thin layer of the viscous gas, and the asymptotic analysis of the problem was performed by the perturbation method. Using the method of iterations, the law of viscous gas pressure distribution in the channel was determined, and the equation of aeroelastic oscillations in the channel wall was obtained as a generalization of the Duffing equation. This equation was solved by the harmonic balance method. The primary nonlinear aeroelastic response of the channel wall and the nonlinear phase shift were expressed as implicit functions. These characteristics were studied numerically to evaluate the influence of the nonlinear elastic suspension of the channel wall and the viscous gas inertia and compressibility on the nonlinear oscillations in the channel wall.","PeriodicalId":516762,"journal":{"name":"Uchenye Zapiski Kazanskogo Universiteta. Seriya Fiziko-Matematicheskie Nauki","volume":"37 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141806105","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":"Influence of Photoexcitation Conditions on the Spin Polarization of Nitrogen-Vacancy Centers in Isotopically Enriched Silicon Carbide 6H-28 SiC","authors":"F. F. Murzakhanov, G. Mamin, M. Sadovnikova, D. Shurtakova, O. P. Kazarova, E. Mokhov, M. Gafurov","doi":"10.26907/2541-7746.2024.2.187-199","DOIUrl":"https://doi.org/10.26907/2541-7746.2024.2.187-199","url":null,"abstract":"Spin defects in semiconductors are attracting interest as a material basis for quantum information and computing technologies. In this work, the spin properties of negatively − charged nitrogen-vacancy ( NV ) centers in a 6H-SiC silicon carbide crystal enriched with the 28 Si isotope were studied by high-frequency ( 94 GHz) electron paramagnetic resonance (EPR) − methods. Due to an optical excitation channel at the NV centers, it was possible to initialize the electron spin of the defect using a laser source, which led to a significant increase in the intensity of the recorded EPR signal. The dependences of the observed spin polarization were analyzed at different optical excitation wavelengths ( λ = 640 – 1064 nm), output power ( 0 – 500 mW), and temperature ( 50 – 300 K) of the crystal. The results obtained reveal the optimal experimental conditions for maximizing the efficiency of optical quantum energy transfer to − the spin system. This opens up new possibilities for using NV centers in 6H-SiC to create multi-qubit spin-photon interfaces operating in the infrared region.","PeriodicalId":516762,"journal":{"name":"Uchenye Zapiski Kazanskogo Universiteta. Seriya Fiziko-Matematicheskie Nauki","volume":"66 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141802380","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":"Modeling the Inertial Deposition of Aerosol Particles in a Mixed-Type Filter","authors":"D. A. Safin, S. Zaripov, R. Mardanov, E. A. Kosterina","doi":"10.26907/2541-7746.2024.2.262-272","DOIUrl":"https://doi.org/10.26907/2541-7746.2024.2.262-272","url":null,"abstract":"This article presents a mathematical model that describes the movement of suspended aerosol particles in a mixed-type filter. For the carrier medium, a model of incompressible fluid flow in a porous periodic element consisting of many cylinders with diameters in the nano- and micrometer range was adopted. The Stokes boundary value problem for the flow function was solved using the boundary element method. The efficiency of the deposition of suspended particles was determined by calculating their trajectories in the identified velocity field of the carrier medium. For various ratios of mass fractions of nano- and microfibers, the dependences of the deposition efficiency due to the inertial impact and interception mechanism on the Stokes number were found.","PeriodicalId":516762,"journal":{"name":"Uchenye Zapiski Kazanskogo Universiteta. Seriya Fiziko-Matematicheskie Nauki","volume":"37 15","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141806094","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":"R-Linear Conjugation Problem on the Unit Circle in the Parabolic Case","authors":"S. Rogosin, L. Primachuk, M. Dubatovskaya","doi":"10.26907/2541-7746.2024.2.250-261","DOIUrl":"https://doi.org/10.26907/2541-7746.2024.2.250-261","url":null,"abstract":"","PeriodicalId":516762,"journal":{"name":"Uchenye Zapiski Kazanskogo Universiteta. Seriya Fiziko-Matematicheskie Nauki","volume":"86 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141802488","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":"On the Linear Complexity of Generalized Cyclotomic Sequences with Odd Period","authors":"V. Edemskiy","doi":"10.26907/2541-7746.2024.2.162-172","DOIUrl":"https://doi.org/10.26907/2541-7746.2024.2.162-172","url":null,"abstract":"The linear complexity of new generalized cyclotomic sequences with odd period was estimated. The sequences were defined using generalized cyclotomic classes composite modulo. Conditions sufficient for the existence of binary and non-binary sequences with high linear complexity were obtained. The earlier results on the linear complexity of sequences with the period equal to the power of a prime were generalized.","PeriodicalId":516762,"journal":{"name":"Uchenye Zapiski Kazanskogo Universiteta. Seriya Fiziko-Matematicheskie Nauki","volume":"58 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141809492","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":"Mixed Boundary Value Problem for a Monotone Equation with a Lower Order Term and Point Sources on the Right Side","authors":"O. Zadvornov, G. O. Trifonova","doi":"10.26907/2541-7746.2024.2.173-186","DOIUrl":"https://doi.org/10.26907/2541-7746.2024.2.173-186","url":null,"abstract":"","PeriodicalId":516762,"journal":{"name":"Uchenye Zapiski Kazanskogo Universiteta. Seriya Fiziko-Matematicheskie Nauki","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141807309","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":"Diophantine Equation Generated by the Subfield of a Circular Field","authors":"I. G. Galyautdinov, E. Lavrentyeva","doi":"10.26907/2541-7746.2024.2.147-161","DOIUrl":"https://doi.org/10.26907/2541-7746.2024.2.147-161","url":null,"abstract":"","PeriodicalId":516762,"journal":{"name":"Uchenye Zapiski Kazanskogo Universiteta. Seriya Fiziko-Matematicheskie Nauki","volume":"69 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141806666","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":"Multivariate Rayleigh, Rice, and Nakagami distributions and their applications in communication theory","authors":"Yu. A. Brychkov, N. Savischenko","doi":"10.26907/2541-7746.2024.2.127-146","DOIUrl":"https://doi.org/10.26907/2541-7746.2024.2.127-146","url":null,"abstract":"A method was developed to calculate the symbol and bit error probabilities for coherent diversity reception of multi-position signal structures in a communication channel with additive white Gaussian noise (AWGN) and general fading described by the multivariate Rayleigh and Nakagami distributions, as well as the bivariate Rice distribution.","PeriodicalId":516762,"journal":{"name":"Uchenye Zapiski Kazanskogo Universiteta. Seriya Fiziko-Matematicheskie Nauki","volume":"80 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141812790","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}