17 research outputs found

    SOLUTIONS OF CONSERVATION LAW SYSTEMS

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    The work covers the mathematical models of the physical systems described by the differential equations expressing the conservation properties. The aim is to reveal and analyse the basic mathematical structures connected with the problems of approximated method convergence; to prove the theorems about global solvability of the Cauchy problem for the quasi-linear and semi-linear systems having application in the mathematical physics. The convergence of regular approximated methods to the functional solution of conservation laws at condition of the weak approximation and weak method stability has been substantiated. The possible classes of correctness have been described. The convergence of difference method to the functional solution for the Boltzmann type equations has been substantiated. The solvability on a whole has been proved, and the convergence of approximated methods for the general type non-linear conservation lay systems and for concrete models has been substantiated. The results are used in the Moscow State University, in the Physical-Energetical Institute, in the Institute of Nuclear Power Engineering, in the Institute of Hydrodynamics a.o. The application field: gas dynamics, physical kineticsAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

    Forming of ducted axisymmetric supersonic air inlets

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    Relevance of the research. The efficiency of fuel chemical energy conversion into mechanical motion of a supersonic aircraft is determined by energy losses due to aerodynamic drag of the aircraft and total pressure losses in the air inlet of jet engine. Therefore, ceteris paribus the aircraft with lower level of these losses will be more energy efficient. Significant increase in energy efficiency is expected from the use of axisymmetric isentropic ducted air inlets. In the framework of the non-viscous flow, a numerical method is offered for these air inlets with a contoured central body and a cylindrical shell designing. The main aim of the study. Currently there are no designing methods for axisymmetric isentropic ducted air inlets without elements projecting over a cylindrical body of the aircraft. Therefore, the aim of the study is to develop a methodology for designing such inlets. The methods used in the study. Numerical implementation of the characteristics method for isentropic flow is used. The proposed method involves the decision of two problems. In the first problem a flow line around the given focus point of characteristics is plotted which starts at a break point of central body. In the second problem the rest of the contour is calculated using the reversed flow in an annular nozzle with a cylindrical shell. Simultaneously with the decision of the second problem, the position of the shell is determined. The central body can contain angular points at the edges of the contour. If we use an intermediate flow line then the central body will be smooth. The results. The authors developed the methodology for calculating different axisymmetric supersonic air inlet contours, which geometrical characteristics are uniquely described by the original data

    Estimating the Parameters of Traffic Flows on the Basis of Processing of Localization Data on the Movement of Vehicles

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    The article describes the method of estimating the parameters of transport flows using the two-fluid mathematical model of Herman-Prigogine and developed and based on the proposed method of estimating the parameters of the system on the basis of passive processing of navigation data on the movement of vehicles. The efficiency of the proposed algorithms, mathematical models for estimating the parameters of road traffic flow and system as a whole was confirmed during its testing using a set of tracks on the main highways of Commonwealth of Independent States

    Genetic Association Study and Machine Learning to Investigate Differences in Platelet Reactivity in Patients with Acute Ischemic Stroke Treated with Aspirin

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    Aspirin resistance (AR) is a pressing problem in current ischemic stroke care. Although the role of genetic variations is widely considered, the data still remain controversial. Our aim was to investigate the contribution of genetic features to laboratory AR measured through platelet aggregation with arachidonic acid (AA) and adenosine diphosphate (ADP) in ischemic stroke patients. A total of 461 patients were enrolled. Platelet aggregation was measured via light transmission aggregometry. Eighteen single-nucleotide polymorphisms (SNPs) in ITGB3, GPIBA, TBXA2R, ITGA2, PLA2G7, HMOX1, PTGS1, PTGS2, ADRA2A, ABCB1 and PEAR1 genes and the intergenic 9p21.3 region were determined using low-density biochips. We found an association of rs1330344 in the PTGS1 gene with AR and AA-induced platelet aggregation. Rs4311994 in ADRA2A gene also affected AA-induced aggregation, and rs4523 in the TBXA2R gene and rs12041331 in the PEAR1 gene influenced ADP-induced aggregation. Furthermore, the effect of rs1062535 in the ITGA2 gene on NIHSS dynamics during 10 days of treatment was found. The best machine learning (ML) model for AR based on clinical and genetic factors was characterized by AUC = 0.665 and F1-score = 0.628. In conclusion, the association study showed that PTGS1, ADRA2A, TBXA2R and PEAR1 polymorphisms may affect laboratory AR. However, the ML model demonstrated the predominant influence of clinical features
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