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MAGAZINE OF CIVIL ENGINEERING 2023年第3期119卷

作者： Ravshanov, R. Abdullaev, Z. S. Kotov, E. V. Turkmanova, Sh. N. Res Inst Dev Digital Technol & Artificial Intellig Tashkent Uzbekistan Tashkent Inst Irrigat & Agr Mechanizat Engineers Tashkent Uzbekistan Peter Great St Petersburg Polytech Univ St Petersburg Russia

The unsteady fluid flow in a three-layer porous medium is numerically investigated and is an important and topical problem. An analytical solution of the equation for the pressure fluid layer is obtained on the basis of the theory of elastic regime, taking into account the overflow from the coating and the low -permeability layer into the low-permeability bulkhead and external sources that greatly affect the liquid level change. In the main bounded aquifer only horizontal liquid migrations prevail, and in the cover and low -conductive layers only vertical migrations prevail, allowing for horizontal components of the flow rate to be omitted here. Evaporation from the surface of a liquid in a porous medium is considered. Evaporation from the surface of a liquid in a porous medium significantly affects the distribution of overflows in the layers and the distribution of the liquid level in a porous medium. Therefore, when designing vertical drains for enhanced oil recovery in multilayer reservoirs and designing fluid flows in reservoirs, evaporation must be taken into account. The computational experiments have established that the dynamics of changes in the liquid level in a porous medium depends significantly on the evaporation parameter. With an increase in its value, the liquid level in a porous medium decreases proportionally over time. The accuracy of the numerical solution using the balance equation showed that the error does not exceed 1.3%.

关键词： mathematical model groundwater filtration analytical solution numerical algorithm

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On the Simultaneous Identification of the Volumetric Heat Capacity and the Thermal Conductivity of a Substance 13th

On the Simultaneous Identification of the Volumetric Heat Ca...

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13th International Conference on Optimization and Applications (OPTIMA)

作者： Albu, Alla Gorchakov, Andrei Zubov, Vladimir Russian Acad Sci Fed Res Ctr Comp Sci & Control Moscow Russia

ISBN: (纸本)9783031225420;9783031225437

The study of nonlinear problems associated with heat transfer in the substance is very important for practice. Previously, we proposed an efficient algorithm for identifying the thermal conductivity of a substance based on the results of experimental observation of the dynamics of the temperature field in an object. In this paper, we investigate the possibility of extending the application of the proposed algorithm to obtain a numerical solution to the problem of simultaneous identification of the temperature-dependent the thermal conductivity and the volumetric heat capacity of the substance under study. The consideration is carried out on the basis of the first initial-boundary value problem for the one-dimensional non-stationary heat equation. The considered inverse coefficient problem is reduced to a variational problem, which is solved by gradient methods based on the application of the Fast Automatic Differentiation technique.

关键词： Nonlinear problems Inverse coefficient problems Heat equation numerical algorithm Fast Automatic Differentiation

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The Problem of the Optimal Packing of the Equal Circles for Special Non-Euclidean Metric 5th

The Problem of the Optimal Packing of the Equal Circles for ...

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5th International Conference on Analysis of Images, Social Networks, and Texts (AIST)

作者： Kazakov, Alexander L. Lempert, Anna A. Nguyen, Huy L. Matrosov Inst Syst Dynam & Control Theory SB RAS Irkutsk Russia Irkutsk Natl Res Tech Univ Irkutsk Russia

ISBN: (纸本)9783319529202;9783319529196

The optimal packing problem of equal circles (2-D spheres) in a bounded set P in a two-dimensional metric space is considered. The sphere packing problem is to find an arrangement in which the spheres fill as large proportion of the space as possible. In the case where the space is Euclidean this problem is well known, but the case of non-Euclidean metrics is studied much worse. However there are some applied problems, which lead us to use other special non-Euclidean metrics. For instance such statements appear in the logistics when we need to locate a given number of commercial facilities and to maximize the overall service area. Notice, that we consider the optimal packing problem in the case, where P is a multiply-connected domain. The special algorithm based on optical-geometric approach is suggested and implemented. The results of numerical experiment are presented and discussed.

关键词： Optimal packing problem Equal circles Non-Euclidean space Multiply-connected domain numerical algorithm Computational experiment

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Discrete State Event-Driven Approach for High-Power Converter Simulations 11

Discrete State Event-Driven Approach for High-Power Converte...

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11th Annual IEEE Energy Conversion Congress and Exposition (ECCE)

作者： Shi, Bochen Zhao, Zhengming Zhu, Yicheng Yu, Zhujun Ju, Jiahe Yuan, Liqiang Chen, Kainan Tsinghua Univ Dept Elect Engn State Key Lab Control & Simulat Power Syst & Gene Beijing Peoples R China

ISBN: (纸本)9781728103952

Demands for high-power converters are increasing rapidly. Nevertheless, due to their complex structures and multi-time-scale features, accurate and efficient simulation of such systems has long been a huge obstacle. Aiming at improving the unacceptably slow simulation speed of high-power converters, this paper improves Discrete State Event-Driven (DSED) approach by implementing a decoupling method. Taking a 10kV 1MW electric energy router as an example, this paper evaluates the effectiveness of DSED with the proposed decoupling method in high-power applications. In the studied case, compared with commercially available tool for power electronics simulation, PLECS (R), DSED can achieve an up to 1000-fold improvement in simulation speed under the same accuracy: PLECS (R) takes 6 hours while DSED only takes 18 seconds. DSED provides a powerful simulation tool for analysis, design and control of high-power converters.

关键词： event-driven simulation numerical algorithm circuit partitioning high-power converter electric energy router solid-state transformer

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Experimental determination of the elastic-viscous characteristics of elastic ropes 7

Experimental determination of the elastic-viscous characteri...

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7th Scientific-Technical Conference Material Problems in Civil Engineering (MATBUD)

作者： Pavlov, Peter Evlogiev, Daniel Univ Architecture Civil Engn & Geodesy Sofia 1046 Bulgaria

The conducted analytical, numerical and experimental studies for waiving of the elastic-viscous characteristics of elastic ropes are presented in the current report. The analytical studies are related to the creation of a dynamic and mathematical model of a vibrating system, supported by such ropes. The numerical studies refer to the creation of a corresponding program and a simulation model. The experimental activities refer to the modification of an existing dynamic stand for the implementation of an experimental setting, corresponding to the initial dynamic model. Additional numerical activities are carried out in connection with the development of a programming module for receiving, processing and analysis of the results of the experimental studies. By applying of the combined procedure, the data for the resistance of randomly selected group of ropes, at different deformation in them, are received. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://***/lienses/by-nc-nd/4.0). Peer-review under responsibility of organizing committee of the 7th Scientific-Technical Conference Material Problems in Civil Engineering

关键词： elastic ropes dynamic model numerical algorithm experimental set elastic-viscous characteristics

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Computing Contraction Metrics: Comparison of Different Implementations 24

Computing Contraction Metrics: Comparison of Different Imple...

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24th International Symposium on Mathematical Theory of Networks and Systems (MTNS)

作者： Giesl, P. Hafstein, S. Mehrabinezhad, I Univ Sussex Dept Math Falmer BN1 9QH England Univ Iceland Fac Phys Sci Dunhagi 5 IS-107 Reykjavik Iceland

We discuss the implementation of a novel demanding algorithm to compute contraction metrics for nonlinear systems. We compare MATLAB- and C++-implementations and study the effect of parallelizing the code. Further, we explore the use of different low-level math-libraries for the C++ -implementation and the use of an undocumented code-path that considerably speeds up MATLAB code on AMD's Ryzen processors. Copyright (C) 2021 The Authors.

关键词： Contraction metric Riemannian metric Lyapunov function numerical algorithm Mesh-free collocation

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Decomposition peculiarities at the modeling microwave devices with discrete spatial spectra

Decomposition peculiarities at the modeling microwave device...

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VIth International Conference on Mathematical Methods in Electromagnetic Theory (MMET 96)

作者： Tkachenko, V Inst of Radiophysics and Electronics of the Natl Acad of Sciences of Ukraine Kharkov Ukraine

ISBN: (纸本)9660200269

Use of the technique of generalized scattering matrices is convenient for solving complicated problems of scattering on the base of decomposition principle. Use of this principle in commonly accepted versions, when the decomposition is carried out into characteristic simple segments of common topology (key blocks), is obvious. However in a number of cases decomposition can be successfully applied while modeling the structures, in which some key blocks are not evident. It is shown earlier that, while modeling key blocks by the momentum method at essentially different dimensions of the channels being connected, one can increase calculation accuracy by means of the decomposition of the element into two virtual ones. This idea is realized in this paper in the version, accounting the character of momentum method solution more completely.

关键词： waveguides modeling numerical algorithm

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Computation of Initial Transformation for Implicit Double Step in the Periodic QZ algorithm 23

Computation of Initial Transformation for Implicit Double St...

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23rd International Conference on System Theory, Control and Computing (ICSTCC)

作者： Sima, Vasile Natl Inst Res & Dev Informat Bucharest Romania

ISBN: (纸本)9781728106991

The periodic QZ algorithm (pQZ) is required in many applications, including periodic linear systems, cyclic matrices and matrix pencils, and some structured eigenproblems. The implicit double pQZ step is the essential part of this algorithm, since it determines its convergence rate. The pQZ step acts on a formal matrix product already reduced to the Hessenberg-triangular form. Each pQZ step starts with an initial transformation aimed to make the first column of the identity matrix and of the Wilkinson double-shift polynomial parallel. This transformation is found in an implicit manner, without evaluating the formal matrix product and the polynomial. This paper presents in detail the computation of the initial transformation in the periodic QZ step, and summarizes the benefits obtained using a new such approach for solving skew-Hamiltonian/Hamiltonian eigenproblems. The previous convergence failures are avoided and the number of iterations necessary to converge can be significantly reduced.

关键词： linear multivariable system periodic system numerical algorithm software stability

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Heterogeneity, aggregate uncertainty, and the short-term interest rate

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JOURNAL OF BUSINESS & ECONOMIC STATISTICS 1996年第4期14卷 399-411页

作者： DenHaan, WJ UNIV CALIF SAN DIEGO DEPT ECONLA JOLLACA 92093 USA

This article analyzes the relationship between the short-term interest rate and diversity (i.e., the number of types) in models with heterogeneous agents and incomplete markets. The number of types needed to approximate a continuum varies across examples. In all cases, however, the number of types has little effect on the average interest rate and consumption variability. In these models, the set of state variables is large because the equilibrium law of motion depends on the cross-sectional wealth distribution. The article shows how to solve these models numerically by approximating the distribution using moments or percentiles.

关键词： asset pricing dynamic equilibrium model large set of state variables numerical algorithm

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Outlier Detection, Clustering, and Classification - Methodologically Unified Procedures for Conditional Approach 12th

Outlier Detection, Clustering, and Classification - Methodol...

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12th International Conference on Computational Collective Intelligence (ICCCI)

作者： Kulczycki, Piotr Franus, Krystian Polish Acad Sci Syst Res Inst Warsaw Poland AGH Univ Sci & Technol Fac Phys & Appl Comp Sci Krakow Poland

ISBN: (纸本)9783030630065;9783030630072

The subject of the study are three fundamental procedures of contemporary data analysis: outliers detection, clustering and classification. The issue is considered in a conditional approach - introduction of specific (e.g. current) values to the model allows in practice a significantly precise description of the reality under research. The same methodology has been used for all three above tasks, which considerably facilitates the interpretations, potential modifications and practical applications of the material investigated. Using non-parametric methods frees the procedures under investigation from a distribution in the considered dataset.

关键词： Data analysis Data mining Outliers detection Clustering Classification Conditional approach Distribution free methods numerical algorithm

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