Vestnik Sankt-Peterburgskogo Universiteta Seriya 10 Prikladnaya Matematika Informatika Protsessy Upravleniya最新文献

{"title":"STRUCTURE OF A 4-DIMENSIONAL ALGEBRA AND GENERATING PARAMETERS OF THE HIDDEN DISCRETE LOGARITHM PROBLEM","authors":"N. Moldovyan, A. Moldovyan","doi":"10.21638/11701/spbu10.2022.202","DOIUrl":"https://doi.org/10.21638/11701/spbu10.2022.202","url":null,"abstract":"Structure of a 4-dimensional algebra and generating parameters of the hidden discrete logarithm problem the field GF'(p) is studied in connection with using it as algebraic support of the hidden discrete logarithm problem that is an attractive primitive of post-quantum signature schemes. It is shown that each invertible 4-dimensional vector that is not a scalar vector is included in a unique commutative group representing a subset of algebraic elements. Three types of commutative groups are contained in the algebra and formulas for computing the order and the number of groups are derived for each type. The obtained results are used to develop algorithms for generating parameters of digital signature schemes based on computational difficulty of the hidden logarithm problem.","PeriodicalId":43738,"journal":{"name":"Vestnik Sankt-Peterburgskogo Universiteta Seriya 10 Prikladnaya Matematika Informatika Protsessy Upravleniya","volume":"89 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76456208","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":"Recovering complex reflection coefficient using the reference layer algorithm for multilayer systems with non-collinear magnetic ordering","authors":"Yu. A. Salamatov, E. S. Nikova, D. I. Devyaterikov, Evgeny A. Kravtsov","doi":"10.21638/11701/spbu10.2022.412","DOIUrl":"https://doi.org/10.21638/11701/spbu10.2022.412","url":null,"abstract":"This work analyzes two mathematical algorithms for processing experimental curves in polarized neutron reflectometry, one of which makes it possible to determine the complex reflection coefficient. The approbation was carried out for a Fe/Cr type superlattice with an irregular non-collinear ordering of the magnetic moments of the Fe layers. The processing of the experiment was carried out both by direct refinement of the structure parameters and by the method of calculating the module and phase of the reflectometry signal using the Gd reference layer. The results obtained with different methods are compared with each other. To clarify the structural and magnetic characteristics, the Levenberg-Marquardt algorithm was applied in both cases. The obtained data on the magnetic structure is in agreement with the theoretical model of magnetization of a layered antiferromagnet of finite dimensions in a weak field. The presented modification of the reference layer method can be considered as the phase problem solution in polarized neutron reflectometry.","PeriodicalId":43738,"journal":{"name":"Vestnik Sankt-Peterburgskogo Universiteta Seriya 10 Prikladnaya Matematika Informatika Protsessy Upravleniya","volume":"1100 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76741217","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 convergence of dynamic quasiperiodic systems","authors":"Sergey A. Strekopytov, M. Strekopytova","doi":"10.21638/11701/spbu10.2022.106","DOIUrl":"https://doi.org/10.21638/11701/spbu10.2022.106","url":null,"abstract":"The convergence problem for non-autonomous systems of differential equations with a quasiperiodic right-hand side in an independent argument is considered. It is proposed to replace the consideration of the set of solutions of the system of differential equations under consideration by considering the movements of a dynamic quasi-periodic system generated by these differential equations. Necessary and sufficient conditions are obtained when a dynamic quasi-periodic system has the convergence property, and a proof is given.","PeriodicalId":43738,"journal":{"name":"Vestnik Sankt-Peterburgskogo Universiteta Seriya 10 Prikladnaya Matematika Informatika Protsessy Upravleniya","volume":"63 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77521474","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 modeling of malignant ovarian tumors","authors":"A. Goncharova, E. Kolpak, Maria Yu. Vil’, Alina Abramova, E. Busko","doi":"10.21638/11701/spbu10.2022.110","DOIUrl":"https://doi.org/10.21638/11701/spbu10.2022.110","url":null,"abstract":"The article explores modeling the development of ovarian cancer, the treatment of this oncologicaldisease in women, the assessment of the time to achieve remission, and the assessment of the time of the onset of relapse. The relevance of the study is that ovarian cancer is one of the most common cancers in women and has the highest mortality rate among all gynecological diseases. Modeling the process of the development of the disease makes it possible to better understand the mechanism of the development of the disease, as well as the time frame of the onset of each stage, as well as the assessment of the survival time. The aim of the work is to develop a model of an ovarian tumor. It is based on a model of competition between two types of cells: epithelial cells (normal cells) and tumor cells (dividing cells). The mathematical interpretation of the competition model is the Cauchy problem for a system of ordinary differential equations. Treatment is seen as the direct destruction of tumor cells by drugs. The behavior of solutions in the vicinity of stationary points is investigated by the eigenvalues of the Jacobi matrix of the right side of the equations. On the basis of this model, the distribution of conditional patients by four stages of the disease is proposed. Biochemical processes that stimulate the accelerated growth of the tumor cell population are modeled by a factor that allows tumor cells to gain an advantage in a competitive relationship with epithelial cells. The spatio-temporal dynamics of an ovarian tumor leads to a modification of the competition model due to the introduction of additional factors into it, taking into account the presence of increased nutrition of ovarian tumors, the exit of the tumor from the plane of the ovary, as well as the effect of treatment on tumor cells. The new model describes the interaction conditions with a system of second-order partial differential equations. The results of computer modeling demonstrate an assessment of the distribution of conditional patients by stages of the disease, the time of onset of relapse, the duration of remission, the obtained theoretical results of modeling are compared with the real data.","PeriodicalId":43738,"journal":{"name":"Vestnik Sankt-Peterburgskogo Universiteta Seriya 10 Prikladnaya Matematika Informatika Protsessy Upravleniya","volume":"26 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75906814","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":"Extraction of common properties of objects for creation of a logic ontology","authors":"T. Kosovskaya, N. N. Kosovskii","doi":"10.21638/11701/spbu10.2022.103","DOIUrl":"https://doi.org/10.21638/11701/spbu10.2022.103","url":null,"abstract":"The paper describes an approach to the formation of ontology based on descriptions of objects in terms of the predicate calculus language. With this approach, an object is represented as a set of its elements, on which a set of predicates is defined that defines the properties of these elements and the relationship between them. A description of an object is a conjunction of literals that are true on elements of an object. In the present work, ontology is understood as an oriented graph with descriptions of subsets as nodes and such that the elements of a set at the end of an oriented edge have the properties of the elements of the set at the beginning of this edge. Three settings of an ontology construction problem are considered: 1) all predicates are binary and subsets of the original set of objects are given; 2) all predicates are binary and it is required to find subsets of the original set; 3) among the predicates there are many-valued ones and subsets of the original set of objects are given. The main tool for construction such a description is to extract an elementary conjunction of literals of predicate formulas that is isomorphic to subformulas of some formulas. The definition of an isomorphism of elementary conjunctions of atomic predicate formulas is given. The method of ontology construction is formulated. An illustrative example is provided.","PeriodicalId":43738,"journal":{"name":"Vestnik Sankt-Peterburgskogo Universiteta Seriya 10 Prikladnaya Matematika Informatika Protsessy Upravleniya","volume":"73 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85205352","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 effective elastic properties of a material with mutually perpendicular systems of parallel cracks","authors":"Abdulla M. Abakarov, Y. Pronina","doi":"10.21638/11701/spbu10.2022.109","DOIUrl":"https://doi.org/10.21638/11701/spbu10.2022.109","url":null,"abstract":"The effective properties of cracked solids are often expressed in terms of the crack density parameter or its tensor generalization, using the approximation of noninteracting cracks. This approximation remains accurate at sufficiently high crack densities, provided the location of cracks are random. The presented analysis confirms that the effective elastic moduli of a material with ordered fracture structures strongly depend on the linear dimensions of cracks and their mutual arrangement even at a constant crack density. A change in these parameters can cause a noticeable anisotropy of the effective properties of the material even when the eigenvalues of the crack density tensor are equal to each other. The effective elastic characteristics of a material with one doubly periodic system of parallel cracks are compared with those for a material with two mutually perpendicular systems of such cracks in a two-dimensional formulation. The calculations are carried out using the approximate method of M. Kachanov for determining the mean stresses at the cracks edges, applicable for large systems of interacting cracks. Analysis of the obtained results showed that the effective compliance of the material in a certain direction is largely determined by the effects of interaction (shielding and amplification) within a system of parallel cracks perpendicular to this direction. The interaction of this system of cracks with the perpendicular system has a weak effect on the indicated properties in the case of rectangular symmetry of the system. In this case, the interaction of mutually perpendicular systems of cracks leads to a violation of the symmetry of the tensor of effective elastic constants.","PeriodicalId":43738,"journal":{"name":"Vestnik Sankt-Peterburgskogo Universiteta Seriya 10 Prikladnaya Matematika Informatika Protsessy Upravleniya","volume":"162 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78011232","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":"ANALYSIS OF SIMPLIFIED GAS TRANSPORTATION MODELS. CALCULATION OF THE GAS LEAK LOCATION IN A PIPELINE","authors":"G. Kurbatova, E. Vinogradova, V. A. Klemeshev","doi":"10.21638/11701/spbu10.2022.205","DOIUrl":"https://doi.org/10.21638/11701/spbu10.2022.205","url":null,"abstract":"An approach to a simplified calculation of the characteristics of a steady gas flow through a pipeline is proposed. In this approach, the pressure is calculated using an isothermal model; the temperature analysis is reduced to a cubic equation solving. A simple analytical gas leak point coordinate dependence on the pressure and gas flow values is obtained at outlet from the pipeline. The result of comparison of calculations for the general and simplified models of gas flow in pipelines is presented. A criterion has been determined for the fulfillment of which it is permissible to use a simplified approach to calculating the gas characteristics and the leak point coordinates. Using an example of practical interest, the high accuracy of the calculation according to the proposed approach of both pressure and temperature in the flow and the gas leak coordinate in the pipeline is demonstrated.","PeriodicalId":43738,"journal":{"name":"Vestnik Sankt-Peterburgskogo Universiteta Seriya 10 Prikladnaya Matematika Informatika Protsessy Upravleniya","volume":"15 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85148131","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":"Stability of operator-difference schemes with weights for the hyperbolic equation in the space of summable functions with carriers in the network-like domain","authors":"A. P. Zhabko, V. Provotorov, S. Sergeev","doi":"10.21638/11701/spbu10.2022.311","DOIUrl":"https://doi.org/10.21638/11701/spbu10.2022.311","url":null,"abstract":"This work is a natural continuation of the authors’ research on flow phenomena in the direction of increasing the dimensionality of the network-like domain of change of the space variable. The possibility of practical use of the analysis of the stability of operator-difference schemes to solve the issue of stability (stabilization) of wave phenomena in the engineering of the process of transferring continuous media through network-like carriers (water pipelines, gas and oil pipelines, industrial carriers of petroleum products) is shown. Namely, if the scheme is stable, then sufficiently small changes in the initial data of the mathematical model of the process imply small changes of the solution of the difference problem, i. e. in practice do not lead to undesirable aftereffects. If the schema is unstable, then small changes to the initial data can lead to arbitrarily large changes of the solution. In the process of exploitation of industrial constructions of network-like carriers, wave phenomena inevitably arise, the consequence of which are various kinds of instabilities that entail destruction of one nature or another. It is possible to avoid or essentially reduce such undesirable oscillations using the analysis of the stability properties of the mathematical model of the wave process. The obtained results are used in the algorithmically and digitalization of modern technological processes of the movement of fluid media and gases.","PeriodicalId":43738,"journal":{"name":"Vestnik Sankt-Peterburgskogo Universiteta Seriya 10 Prikladnaya Matematika Informatika Protsessy Upravleniya","volume":"7 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84456952","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":"V. ZUBOV’S OPTIMUM DAMPING METHOD IN THE CONTROL PROBLEM OF ONE GYROSCOPE SYSTEM","authors":"A. P. Zhabko, Natalya A. Zhabko, P. Yakovlev","doi":"10.21638/11701/spbu10.2022.208","DOIUrl":"https://doi.org/10.21638/11701/spbu10.2022.208","url":null,"abstract":"The article considers the control problem of the aircraft cabin simulator with a four-axis gimbal gyroscopic system. The difficulty of the control problem of standard three-axis gimbal gyroscopic system is the presence of the phenomena “gimbal lock” when the two axes of the system become collinear or close to collinear. One of the applied solutions to avoid “gimbal lock” is to use of the fourth additional gimbal. Such fore-axis gimbal systems are presented in the works of various autors. However, the problem of an optimal control of four-axis gimbal gyroscopic system is still under the question. Sufficient conditions for the solvability of the control problem are obtained on the base of the one-to-one interconnection between the movement of the cabin, the angular velocities of the cabin axes and the necessary deviations of gimbals rotation angles. This result is presented in lemmas. According this obtained sufficient conditions, the algorithm for constructing a control of the gimbal system in terms of optimal damping process of movement, according to Zubov’s method, is proposed.","PeriodicalId":43738,"journal":{"name":"Vestnik Sankt-Peterburgskogo Universiteta Seriya 10 Prikladnaya Matematika Informatika Protsessy Upravleniya","volume":"14 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74417664","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":"Quality criteria for control of epidemic process","authors":"Serge E. Miheev, V. Mikheev","doi":"10.21638/11701/spbu10.2022.112","DOIUrl":"https://doi.org/10.21638/11701/spbu10.2022.112","url":null,"abstract":"The total number of those infected at the end of an epidemic and the maximum number of infected during an epidemic are considered as two quality criteria for control by delayed isolation of the SIR- and SIRS-type infections. The temporal Barabasi Albert graph is used to model the contacts between individuals. Simulations are run to estimate optimal delays.","PeriodicalId":43738,"journal":{"name":"Vestnik Sankt-Peterburgskogo Universiteta Seriya 10 Prikladnaya Matematika Informatika Protsessy Upravleniya","volume":"42 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74461696","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}