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Segmentation Algorithm of Multispectral Images 多光谱图像的分割算法
Mathematical Models and Computer Simulations Pub Date : 2024-06-25 DOI: 10.1134/s2070048224700029
O. V. Nikolaeva
{"title":"Segmentation Algorithm of Multispectral Images","authors":"O. V. Nikolaeva","doi":"10.1134/s2070048224700029","DOIUrl":"https://doi.org/10.1134/s2070048224700029","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>An algorithm for the segmentation of multispectral images is presented. First the algorithm performs a preliminary estimate of the number of segments, then the image is divided into segments using a noniterative version of the <i>k</i>-means method. Next, statistical analysis is performed; segment pairs that are realizations of the same random vector are found and merged. The results of testing the algorithm on model and real (HYPERION sensor) data are presented. Partitions of real images, whose segments correspond to various elements of the landscape, are shown.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141501620","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}
引用次数: 0
Scattering by an Elastic Cylinder with an Inhomogeneous Coating of Sound Waves 带有不均匀涂层的弹性圆柱体对声波的散射
Mathematical Models and Computer Simulations Pub Date : 2024-06-25 DOI: 10.1134/s2070048224700054
L. A. Tolokonnikov, D. Yu. Efimov
{"title":"Scattering by an Elastic Cylinder with an Inhomogeneous Coating of Sound Waves","authors":"L. A. Tolokonnikov, D. Yu. Efimov","doi":"10.1134/s2070048224700054","DOIUrl":"https://doi.org/10.1134/s2070048224700054","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>This article studies the mathematical modeling of an acoustic field, which is scattered by a homogeneous isotropic cylinder with a radially inhomogeneous elastic coating. The primary perturbation field is a cylindrical harmonic sound wave emitted by a linear source. It is assumed that the axes of the source and scatterer are not parallel and do not lie in the same plane. The density and elastic moduli of the coating material are described by continuous functions of the radial coordinate. The results of the calculations of the angular characteristics of the scattered acoustic field in the far zone for different positions of the linear source are presented.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141513501","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}
引用次数: 0
Cluster Capillary Core Model for the Calculation of the Relative Phase Permeability for Oil and Water Filtration 用于计算油水过滤相对相渗透率的簇状毛细管芯模型
Mathematical Models and Computer Simulations Pub Date : 2024-06-25 DOI: 10.1134/s2070048224700066
M. A. Zagorovskiy, A. B. Shabarov, S. V. Stepanov
{"title":"Cluster Capillary Core Model for the Calculation of the Relative Phase Permeability for Oil and Water Filtration","authors":"M. A. Zagorovskiy, A. B. Shabarov, S. V. Stepanov","doi":"10.1134/s2070048224700066","DOIUrl":"https://doi.org/10.1134/s2070048224700066","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>This article describes a physical and mathematical model of the steady-state flow of an oil and water mixture in the pore space of a core, represented as a set of capillary clusters. The developed technique allows us to calculate the functions of the relative phase permeabilities (RPPs) based on the data of the standard laboratory core analysis and experiments on single-phase fluid filtration. As a result of the regression analysis of the laboratory data on terrigenous rocks of oil and gas fields in Western and Eastern Siberia, multiparameter dependences of the parameters of the interfacial interaction function (IIF) on the reservoir properties and parameters of the capillary cluster are obtained. It is established that the results of the RPP calculation using the proposed computational-experimental method are in good agreement with the experimental data.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":"117 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141513504","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}
引用次数: 0
Numerical Study of the Aerodynamics of the Head Unit during an Accident at the Start in Windy Conditions 大风条件下起跑事故中头部装置空气动力学数值研究
Mathematical Models and Computer Simulations Pub Date : 2024-04-22 DOI: 10.1134/s2070048224010022
M. I. Anikeeva
{"title":"Numerical Study of the Aerodynamics of the Head Unit during an Accident at the Start in Windy Conditions","authors":"M. I. Anikeeva","doi":"10.1134/s2070048224010022","DOIUrl":"https://doi.org/10.1134/s2070048224010022","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>In this study the flow around the bodies of a detachable head unit (DHU) with an emergency rescue system (ERS) and launch vehicle (LV) in the process of their separation in windy conditions is numerically simulated with the determination of forces, moments, and pressure distribution in a quasi-stationary formulation—the change in the distance between bodies is set discretely. The main task of this stage is to determine the influence of wind, propulsion jets, and the distance between objects on gasdynamic forces and moments.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":"247 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140800834","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}
引用次数: 0
Automatic Block-Structured Grid Generation in Turbo Machine Blade Passages by TurboR&D.Mesher Software TurboR&D.Mesher 软件自动生成涡轮叶片通道中的块状结构网格
Mathematical Models and Computer Simulations Pub Date : 2024-04-22 DOI: 10.1134/s2070048224010125
R. A. Zagitov, S. D. Salnikov, N. V. Shuvaev
{"title":"Automatic Block-Structured Grid Generation in Turbo Machine Blade Passages by TurboR&D.Mesher Software","authors":"R. A. Zagitov, S. D. Salnikov, N. V. Shuvaev","doi":"10.1134/s2070048224010125","DOIUrl":"https://doi.org/10.1134/s2070048224010125","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>This article describes the methodology of generating block-structured computational grids for turbomachine blade passages implemented in the TurboR&amp;D.Mesher software. The variational method is used as the main method of constructing a computational grid. A combination of the energy density functional and cell size functional is used. A multigrid approach is applied in order to speed up the process of grid generation. An algorithm for constructing a block topology in the blade passages, which takes several spanwise sections of the blade into account simultaneously, is proposed. To create a block topology of axisymmetric effects a method to determine the middle axis of the computational domain is used. The main features of the software are discussed, and the presented results demonstrate the high quality of the grids generated in a fully automatic mode.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140800873","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}
引用次数: 0
Numerical Study of the Features of the Propagation of Acoustic Disturbances in an Unregulated Supersonic Air Intake 对非管制超音速进气口声扰动传播特征的数值研究
Mathematical Models and Computer Simulations Pub Date : 2024-04-22 DOI: 10.1134/s2070048224010095
V. A. Shorstov
{"title":"Numerical Study of the Features of the Propagation of Acoustic Disturbances in an Unregulated Supersonic Air Intake","authors":"V. A. Shorstov","doi":"10.1134/s2070048224010095","DOIUrl":"https://doi.org/10.1134/s2070048224010095","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Using the Vortex and Wave Tracker program, a number of calculations are carried out to identify the peculiarities of the propagation of acoustic disturbances in the channel of a supersonic air intake with a high level of flow inhomogeneity and turbulence. The problems for a cylindrical channel with a uniform flow and the selected unregulated air intake are considered. The calculations are performed with and without the vortex-resolving approach, as well as with and without fan disturbances. The acoustic disturbances generated by the flow and the evolving disturbances of the fan are separated and considered by plotting phase velocity diagrams and comparing the results of different calculations. This study contains descriptions of the features of each of the components. The calculations show the weak influence of intense turbulence on the rate of attenuation of the fan disturbances and the strong influence on their structure, including a change in frequency. It is noted that the rapid transformation of the initial structure of disturbances should affect the operation of sound-absorbing structures and the process of noise shielding by the airframe elements. It should be noted that the flow in a practically acceptable air intake will be more homogeneous and less turbulent, which requires additional calculations before generalizing the conclusions.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":"50 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140800870","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}
引用次数: 0
Evaluation of the Accuracy of Modern Codes by Comparing the Calculated and Experimental Data on the Example of a Problem on a Supersonic Viscous Turbulent Gas Flow Around a Tandem of Back-Forcing and Forward-Forcing Steps 通过比较计算数据和实验数据评估现代代码的准确性--以围绕后向强制和前向强制串联步骤的超音速粘性湍流气体流为例
Mathematical Models and Computer Simulations Pub Date : 2024-04-22 DOI: 10.1134/s2070048224010046
S. M. Bosnyakov, M. E. Berezko, Yu. N. Deryugin, A. P. Duben, R. N. Zhuchkov, A. S. Kozelkov, T. K. Kozubskaya, S. V. Matyash, S. V. Mikhailov, M. K. Okulov, V. A. Talyzin, A. A. Utkina, N. A. Kharchenko, V. I. Shevyakov
{"title":"Evaluation of the Accuracy of Modern Codes by Comparing the Calculated and Experimental Data on the Example of a Problem on a Supersonic Viscous Turbulent Gas Flow Around a Tandem of Back-Forcing and Forward-Forcing Steps","authors":"S. M. Bosnyakov, M. E. Berezko, Yu. N. Deryugin, A. P. Duben, R. N. Zhuchkov, A. S. Kozelkov, T. K. Kozubskaya, S. V. Matyash, S. V. Mikhailov, M. K. Okulov, V. A. Talyzin, A. A. Utkina, N. A. Kharchenko, V. I. Shevyakov","doi":"10.1134/s2070048224010046","DOIUrl":"https://doi.org/10.1134/s2070048224010046","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Various program codes for the investigation of a viscous turbulent compressible gas flow around complicated configurations are described. A series of test calculations for a tandem of 3D back-forcing and forward-forcing steps are performed. The purpose of the calculations is to analyze the resolution accuracy of the separation zones using classical and modern methods. To achieve the goal, the physical features of the flow are described and the results obtained using different codes in the back-forcing and forward-forcing steps tandem test case are compared.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":"238 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140800939","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}
引用次数: 0
Study of the Vortex-Resolving Method of the Throttling Effect on Pressure Pulsation Spectra in a Paired Supersonic Air Intake 涡流解析法研究对偶超音速进气口压力脉动谱的节流效应
Mathematical Models and Computer Simulations Pub Date : 2024-04-22 DOI: 10.1134/s2070048224010071
D. A. Lyubimov
{"title":"Study of the Vortex-Resolving Method of the Throttling Effect on Pressure Pulsation Spectra in a Paired Supersonic Air Intake","authors":"D. A. Lyubimov","doi":"10.1134/s2070048224010071","DOIUrl":"https://doi.org/10.1134/s2070048224010071","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Using the vortex-resolving RANS/ILES method, the flow in a paired model supersonic air intake (SAI) of mixed compression with a boundary layer (BL) bleed system is investigated. The influence of the type of BL bleed system and throttling of each of the SAI on the flow characteristics, the level and spectra of pressure pulsations in the neighboring SAIs is analyzed. Cases with the same and different throttling in each of the SAIs, as well as a common and individual bleed system for neighboring SAIs, are considered. A brief description of the calculation method and boundary conditions is given. The levels of OASPL in the SAI are presented depending on the degree of throttling. The influence of throttling of one of the SAIs on the flow and features of the 1/3-octave spectra of pressure pulsations in the neighboring SAI is revealed.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":"101 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140800831","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}
引用次数: 0
A High-Order Accuracy Method for Calculating the Initial Icing Stage of a Civil Aircraft’s Structural Elements 计算民用飞机结构部件初始结冰阶段的高阶精确度方法
Mathematical Models and Computer Simulations Pub Date : 2024-04-22 DOI: 10.1134/s207004822401006x
S. M. Bosnyakov, A. V. Wolkov, S. V. Mikhaylov, V. Yu. Podaruev
{"title":"A High-Order Accuracy Method for Calculating the Initial Icing Stage of a Civil Aircraft’s Structural Elements","authors":"S. M. Bosnyakov, A. V. Wolkov, S. V. Mikhaylov, V. Yu. Podaruev","doi":"10.1134/s207004822401006x","DOIUrl":"https://doi.org/10.1134/s207004822401006x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>An effective approach based on the discontinuous Galerkin method (DGM) of a high-order accuracy for calculating the initial stage of an aircraft wing’s icing is presented. The problem is solved in the Euler approximation for small water droplets that do not affect the main flow. Systems of Navier–Stokes (NS) equations and Euler model equations for the liquid water content and some relations of the ice growth thermodynamics equations are written. The initial and boundary conditions are formulated. A supercomputer DGM implementation is proposed to solve these systems of equations. The efficiency of the parallel version for the code is investigated. Comments are given on the peculiarities of organizing the calculation procedure. The accuracy of the calculation using the DGM schemes of different accuracy orders is investigated. Test cases on the finely dispersed flow of supercooled droplets around a cylinder and a NACA0012 profile are presented. The numerical and experimental data are compared. A conclusion is drawn about the possibility of applying the developed methodology in practice.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":"163 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140800874","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}
引用次数: 0
Experimental Verification of the Method and Code for Calculating Low-Frequency Fluctuations at the Jet Boundary of a Full-Scale Subsonic Looped Type Wind Tunnel 全尺度亚音速环形风洞喷流边界低频波动计算方法和代码的实验验证
Mathematical Models and Computer Simulations Pub Date : 2024-04-22 DOI: 10.1134/s2070048224010058
S. M. Bosnyakov, D. V. Liverko, V. V. Malenko, S. V. Mikhaylov, A. N. Morozov
{"title":"Experimental Verification of the Method and Code for Calculating Low-Frequency Fluctuations at the Jet Boundary of a Full-Scale Subsonic Looped Type Wind Tunnel","authors":"S. M. Bosnyakov, D. V. Liverko, V. V. Malenko, S. V. Mikhaylov, A. N. Morozov","doi":"10.1134/s2070048224010058","DOIUrl":"https://doi.org/10.1134/s2070048224010058","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The results of computational and experimental sets, where low-frequency pulsations of the total pressure in the jet obtained by various methods are studied and compared, are presented. The calculation is performed by the LES (IDDES) method using the EWT-TSAGI code. The experiment is performed using pressure gauges, as well as ICD-100 and Kulite sensors. The flow is visualized. It is shown that the calculated and experimental data are in acceptable agreement with each other in all areas, except for the outer boundary of the jet, where the calculation grid has insufficient condensation.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140800932","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}
引用次数: 0
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