01.00.00 Physical-mathematical sciences
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THE REALIZATION OF GALOIS GROUPS BY TRINOMIALS OVER THE FIELD OF RATIONAL NUMBERS Q
01.00.00 Physical-mathematical sciences
DescriptionIt is known that not every finite group can be realized over the field of rational numbers as a Galois group of some binomial. In this connection, a more general question arises: suppose that there is given a finite transitive subgroup G of the symmetric group S on n symbols; Can this group G be realized as a Galois group of some trinomial of degree n over the field of rational numbers? In this paper we prove that every transitive subgroup of the group S can be realized in the form of the Galois group of a certain trinomial of the degree n, for the values n = 2, 3, 4. For n = 5 , 6 we give examples that realize concrete Galois groups. In the case n = 7, all the transitive subgroups of the group S are realized, except possibly one group of the isomorphic dihedral group D. Further calculations will be directed to the realization of specific Galois groups for n = 8, 9 ..., however, the number of transitive subgroups of the group S for n = 8, 9 ... grows very fast, so the larger the value of n, the more difficult it is to realize not just everything but the specific subgroup of the group S in the form of a trinomial over Q
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PROBABILISTIC MODEL OF THE PROCESS OF REDUCTION OF THE PRICE FOR PLANNED ACTIONS
01.00.00 Physical-mathematical sciences
DescriptionThe soil fertility increase issues are very relevant now. Intensive development of agriculture cannot be made effectively without complex actions for farmlands protection from different types of degradations. On the one hand, it is necessary to ensure the maximum harvest of crops, and to preserve and increase the fertility of the soil and prevent negative anthropogenic impact on the environment on the other. For an extended reproduction of soil fertility, a system of measures is necessary for introduction of mineral and organic fertilizers into the soil, agrotechnical and reclamation methods, stimulation of humus formation processes, and so on. Therefore, methods are important that allow us to estimate the planned measures in advance to improve soil fertility and to eliminate environmental damage. In the article, the estimated parameters are treated by random variables. This allows us to consider the uncertainty in terms of probability distributions. It is offered a probabilistic model of the process of reducing the price of the proposed activity. Mathematical expectation, variance, distribution density of the considered random variable probabilities as the main characteristics of the object state price are calculated. The model can be used to address issues of rational use of land, scientifically based land management organization, when drafting land reclamation project
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01.00.00 Physical-mathematical sciences
DescriptionThe concept of generic polynomial appeared in Saltman’s works at the end of the last century and it is connected with the inverse problem of Galois theory, which is still far from its complete solution. Let G be a finite group and K be a field, the polynomial f(x,t1, … , tn) with coefficients from the field K is generic for the group G, if Galois group of this polynomial over the field K(t1, … , tn) is isomorphic G and if for any Galois extension L/K with Galois group isomorphic G there are such values of parameters ti = ai , i = 1,2, … , n, that the field L is the splitting field of the polynomial f(x,a1, … , an) over K. Generic polynomials over a given field K and a given finite group G do not always exist, and if they exist then it’s not easy to construct them. For example, for a cyclic group of the eight order C8 there is no generic polynomial over the field of rational numbers Q, although there are found specific polynomials with rational coefficients having Galois group isomorphic C8. Therefore, this is of interest to construct generic polynomials for the group G in cases when G is a direct product of groups of lower orders. In this study we show to solve this problem in case when G is a direct product of certain cyclic groups and there is a type of corresponding generic polynomials. Moreover, we give constructions over the fields of characteristic 0 and over the fields of characteristic 2
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SIMULATION OF A PLASMA CHANNEL AND TRACK IN MOTION OF PLASMA SOURCE IN CONDUCTIVE ENVIRONMENT
01.00.00 Physical-mathematical sciences
DescriptionA model is developed that describes the formation of the plasma channel and the trace when moving in a conducting medium of various objects that are sources of plasma - ball lightning, plasmoids, charged particles, and so on. To describe the contribution of conduction currents, we modified the standard electrostatic equation considering the vortex component of the electric field. As a result of this generalization, a system of parabolictype nonlinear equations is formulated that describes the formation of the plasma channel and the track behind the moving object. In this formulation, the problem of the formation of the lightning channel in weak electric fields, characteristic for atmospheric discharges of cloudearth, is solved. Numerical simulation of the motion of plasma sources in a region with a ratio of the sizes 1/100, 1/200 makes it possible to find the shape of the channel and the total length of the track, as well as the branching regimes. It was previously established that there are three streamer branching mechanisms. The first mechanism is associated with the instability of the front, which leads to the separation of the head of the streamer into two parts. The second mechanism is related to the instability of the streamer in the base region, which leads to the branching of the streamer with the formation of a large number of lateral streamers closing the main channel of the streamer to the cathode. The third branching mechanism, observed in experiments, is associated with the closure of the space charge to the anode through the streamer system. These branching mechanisms are also revealed when the leader is spread. Numerical experiments have revealed a new channel branching mechanism and a trace behind a moving plasma object, caused by the conductivity of the medium
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TO THE QUESTION OF MATHEMATICAL MODELS OF MATERIAL FLOW MANAGEMENT
01.00.00 Physical-mathematical sciences
DescriptionThe article concentrates on the matters of current interest in the sphere of product flows. The object of research is the relocation of product flows from the supply sphere, represented by supply and sales organizations or other commercial-intermediary agencies, to the sphere of business enterprise. The ultimate goal of the production and economic system modeling is the preparation for managerial decision-making. The choice of the model depends on the purposes of the modeling, management functions, automation manufacturing step, applied mathematical tools technique. The article considers the main characteristics of the flow, which while retaining their individuality at the same time depend on each other and function logically in the economic space. The advantages and disadvantages of the material inventory and flows management in micrologistic intraproductive systems are being analyzed. External and internal environment, taken as a basis for the real logistical process modeling, determine the type of the principal stock regulation system and the type of the corresponding mathematical model. Methods and models of the stock theory, the primary objective of which is to determine the most important incoming product flow parameters of the system, are still in demand and their primary goal is to adapt the manufacturing company to the consumers’ needs
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01.00.00 Physical-mathematical sciences
DescriptionThe article is dedicated to a numerical investigation of a plane problem of the oscillation amplitude of a buried source, depending on the frequency and motion speed in various isotropic media. Three types of the medium are considered: a two-layer package with a rigidly fixed base, a two-layer package with a mechanically free base, a half-space. The source, in the form of a stress jump simulating a rigid inclusion of small dimensions, moves in the interface plane at a constant speed. Homogeneous boundary value problems are considered in a moving coordinate system associated with a source. The solution method is based on the usage of integral Fourier transforms, the method of direct contour integration and algorithms for constructing symbols of Green's matrices. The method of direct contour integration significantly simplifies calculations in comparison with the traditional approaches to the calculation of Fourier integrals. We have presented calculations of nine amplitude-frequency and amplitude-velocity characteristics for different combinations of medium and source types, that give an exhaustive qualitative and quantitative description of the solutions for boundary value problems in a wide range of velocities and frequencies. Comparative analysis of calculations showed a primary influence of the type of an elastic medium on the investigated characteristics, as well as the large influence of the source type. Which, in turn, revealed some substantial connections between the boundary value problems with a moving source and the corresponding problems with a stationary source
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THE LIMIT THEORY OF THE SOLUTIONS OF EXTREMAL STATISTICAL PROBLEMS
01.00.00 Physical-mathematical sciences
DescriptionMany procedures of applied mathematical statistics are based on the solution of extreme problems. As examples it is enough to name methods of least squares, maximum likelihood, minimal contrast, main components. In accordance with the new paradigm of applied mathematical statistics, the central part of this scientific and practical discipline is the statistics of non-numerical data (it is also called the statistics of objects of non-numerical nature or non-numeric statistics) in which the empirical and theoretical averages are determined by solving extreme problems. As shown in this paper, the laws of large numbers are valid, according to which empirical averages approach the theoretical ones with increasing sample size. Of great importance are limit theorems describing the asymptotic behavior of solutions of extremal statistical problems. For example, in the method of least squares, selective estimates of the parameters of the dependence approach the theoretical values, the maximum likelihood estimates tend to the estimated parameters, etc. It is quite natural to seek to study the asymptotic behavior of solutions of extremal statistical problems in the general case. The corresponding results can be used in various special cases. This is the theoretical and practical use of the limiting results obtained under the weakest assumptions. The present article is devoted to a series of limit theorems concerning the asymptotics of solutions of extremal statistical problems in the most general formulations. Along with the results of probability theory, the apparatus of general topology is used. The main differences between the results of this article and numerous studies on related topics are: we consider spaces of a general nature; the behavior of solutions is studied for extremal statistical problems of general form; it is possible to weaken ordinary requirements of bicompactness type by introducing conditions of the type of asymptotic uniform divisibility
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BAER’S LAW AND EINSTEIN’S VORTEX HYPOTHESES
01.00.00 Physical-mathematical sciences
DescriptionWe consider numerical solutions of the Navier-Stokes equations describing laminar and turbulent flows in channels of various geometries and in the cavity at large Reynolds numbers. An original numerical algorithm for integrating a system of nonlinear partial differential equations is developed, based on the convergence of the sequence of solutions of the Dirichlet problem. Based on this algorithm, a numerical model is created for the fusion of two laminar flows in a T-shaped channel. A new mechanism of meandering is established, which consists in the fact that when the two streams merge, a jet is formed containing the zones of return flow. Vortex motion in a rectangular cavity is studied. It is established that the numerical solution of the problem with discontinuous boundary conditions loses stability at Reynolds number Re> 2340. The trajectories of passive impurity particles in a cylindrical cavity are investigated. An explanation of the behavior of tea leaves in a cup of tea in the formation of a toroidal vortex because of circular stirring is confirmed, which is confirms the wellknown hypothesis of Einstein. A numerical model of flow in an open channel with a bottom incline in a rotating system is developed. It is shown that in both laminar and turbulent flow under certain conditions a secondary vortex flow arises in the channel due to the Coriolis force, which explains the well-known Baer law and confirms the Einstein hypothesis
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THE ASSESSMENT OF COMPLEXITY OF COMBINATORY METHOD OF NUMBERS’ FACTORIZATION
01.00.00 Physical-mathematical sciences
DescriptionThis article is devoted to the assessment of the calculating complexity of combinatory method of numbers’ factorization. The content of combinatory method is explained in the article of the same name published in the journal issued in November 2016. The author supposes that the reader has learnt its content and knows the basic notions of theory of calculating complexity of the algorithms. The following results of the learning of the given task are expounded in this article. The algorithm of combinatory method permits to accomplish the parallel calculations. Graph of any order is the separate structure, because its initial data are determined independently from the other graphs. So, the calculating complexity of the task about the factorization of numbers in the predetermined interval of the positive integers is defined by the complexity of the most laborious graph. The analysis of the graphs’ structure allows to state that it’s the graph of the third order. In any graph both branches of the first level give the separate structures- partitive graphs of the first level with independent input data. So, the calculating complexity of the graph complete is determined by the maximal complexity of the graph of the first level. The givenat random interval of positive integers stays without changes, if we observe the sequence of the adjacent intervals. In the results it’s stated that the assessment of complexity of combinatory method as well other present methods of numbers’factorization is exponential. In this aspect the combinatory method doesn’t compete with other actual methods. However, evaluating the scientific significance of the algorithm, the decisive factor is not the calculating complexity, but its originality, which permits to explain (if not to discover) any properties of the positive integers. In the conclusion of the article the author describes the advantages of combinatory method, permitting to appreciate the degree of its scientific novelty
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01.00.00 Physical-mathematical sciences
DescriptionIn this article, the properties of prefractal graphs generated by a seed representing a tree are investigated. To determine the phenomenon of the object under investigation with a fractal structure, we present a concept which is the degree of fractalization. The degree of fractalization will allow us to evaluate the structure relative to its belonging to the prefractal graphs