检索结果-内蒙古大学图书馆

Two-dimensional shifted Legendre polynomials operational matrix method for solving the two-dimensional integral equations of fractional order

引用

APPLIED MATHEMATICS AND COMPUTATION 2018年 322卷 40-54页

作者： Hesameddini, Esmail Shahbazi, Mehdi Shiraz Univ Technol Dept Math Sci POB 71555-313 Shiraz Iran

This work approximates the unknown functions based on the two-dimensional shifted Legendre polynomials operational matrix method (2D-SLPOM) for the numerical solution of two-dimensional fractional integral equations. The present method reduces these equations to a system of algebraic equations and then this system will be solved numerically by Newton's method. Moreover, an estimation of the error bound for this algorithm will be shown by preparing some theorems. Some examples are presented to demonstrate the validity and applicability of the proposed method with respect to the two-dimensional block pulse functions method (2D-BPFs) and two-dimensional Bernstein polynomials operational matrix method (2D-BPOM). (C) 2017 Elsevier Inc. All rights reserved.

关键词： Two-dimensional shifted Legendre polynomials Two-dimensional fractional integral equations Error estimate numerical algorithm

来源：评论

学校读者我要写书评

暂无评论

Identification of atypical (rare) elements-a conditional, distribution-free approach

引用

IMA JOURNAL OF MATHEMATICAL CONTROL AND INFORMATION 2018年第3期35卷 923-937页

作者： Kulczycki, Piotr Charytanowicz, Malgorzata Kowalski, Piotr A. Lukasik, Szymon Polish Acad Sci Syst Res Inst Ctr Informat Technol Data Anal Methods Warsaw Poland AGH Univ Sci & Technol Fac Phys & Appl Comp Sci Div Informat Technol & Syst Res Krakow Poland Catholic Univ Lublin Fac Math Comp Sci & Landscape Inst Math & Comp Sci Lublin Poland

The discovery of atypical elements has become one of the most important challenges in data analysis and exploration. At the same time it is not an easy matter with difficult conditions, and not even strictly defined. This article presents a ready-to-use procedure for identifying atypical elements in the sense of rarely occurring. The issue is considered in a conditional approach, where describing and conditioning variables can be multidimensional continuous with the second type also potentially categorical. The application of nonparametric concepts frees the investigated procedure from distributions of describing and conditioning variables. Ease of interpretation and completeness of the presented material lend themselves to the use of the worked out method in a wide range of tasks in various applications of data analysis in science and practice.

关键词： atypical element rare element outlier atypical element identification conditional approach nonparametric method distribution-free method numerical algorithm

来源：评论

学校读者我要写书评

暂无评论

On Lie symmetry mechanics for Navier-Stokes equations unified with non-Newtonian fluid model: A classical directory

引用

PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS 2019年 535卷 122469-000页

作者： Rehman, Khalil Ur Malik, M. Y. King Khalid Univ Coll Sci Dept Math Abha Saudi Arabia Air Univ Dept Math PAF Complex E-9 Islamabad 44000 Pakistan

It is noticed that the most of the researchers having affiliation with the field of fluid science formulate the physical problems by coupling the constitutive relation of the fluid models with the Navier-Stokes equations. The ultimate system of partial differential equations in this direction becomes non-linear in nature due to which investigators always faced problem to narrate the flow field properties. Therefore, in this article we propose the symmetry toolkit to obtain the one parameter group of transformations for the flow controlling differential equations rather than to move-on with the so-called transformations available in literature. To propose idea we have considered the thermally magnetized Williamson fluid flow field along with heat source/sink and chemical reaction effects. The mathematical model is constructed by coupling the constitutive relation of Williamson fluid model with the Navier-Stokes equations in terms of partial differential equations. Such equations are reduced into system of ordinary differential equations by using self-constructed scaling group of transformations via symmetry analysis. The reduced system is solved by numerical algorithm. The key observations are added by means of graphs and tables. It is observed that both Weissenberg number and Hartmann number has same impact of Williamson fluid velocity. Further, Williamson fluid concentration reflects decline magnitude towards higher values of both Schmidt number and chemical reaction parameter. It is well trusted that the structuring of one parameter group of transformations for the particular flow problem will be helpful to report complete description as compared to utilizing the so-called transformations from an existing work. (C) 2019 Elsevier B.V. All rights reserved.

关键词： Symmetry analysis Williamson fluid model Magnetized flow field Heat source/sink Chemical reaction numerical algorithm

来源：评论

学校读者我要写书评

暂无评论

Identification of the Thermal Conductivity Coefficient Using a Given Surface Heat Flux

引用

COMPUTATIONAL MATHEMATICS AND MATHEMATICAL PHYSICS 2018年第12期58卷 2031-2042页

作者： Albu, A. F. Zubov, V. I. Russian Acad Sci Fed Res Ctr Comp Sci & Control Dorodnicyn Comp Ctr Moscow 119333 Russia State Univ Moscow Inst Phys & Technol Dolgoprudnyi 141700 Moscow Oblast Russia

The inverse problem of determining a temperature-dependent thermal conductivity coefficient is studied. The study is based on the Dirichlet boundary value problem for the two-dimensional nonstationary heat equation. The cost functional is defined as the rms deviation of the surface heat flux from experimental data. For the numerical solution of the problem, an algorithm based on the modern fast automatic differentiation technique is proposed. Examples of solving the posed problem are given.

关键词： heat conduction inverse coefficient problems gradient heat equation adjoint equations numerical algorithm

来源：评论

学校读者我要写书评

暂无评论

Heat spreading path optimization of IGBT thermal network model

引用

MICROELECTRONICS RELIABILITY 2019年 103卷 113511-000页

作者： Cui, Haoyang Hu, Fengye Zhang, Yu Zhou, Kun Shanghai Univ Elect Power Sch Elect & Informat Engn Shanghai Peoples R China

This paper presents a theoretical study on the thermal reliability of Insulated-gate bipolar transistor (IGBT) power modules. Although the Cauer thermal network (CTN) model is widely recognized as an essential tool to analyze the thermal performance of IGBT, the heat propagation path, however, deviates from the actual situation and causing an error calculation of junction temperature. Therefore, the thermal resistance (R-th) and thermal capacity (C-th) values are optimized by the heat spreading angle of each material layer, and the influence of baseplate heat dissipation effects is fully considered by adding the heat convection mechanism to the CTN model, which includes interaction between heat conduction and heat convection, thus achieving the integrity of the heat spreading path. Effectiveness of proposed model is validated by simulation studies of finite element analysis and Simulink, the junction temperature estimation results show that the proposed model is more accurate than the conventional CTN model especially in the good dissipation conditions. Thus, accurate thermal behavior estimation could be fairly interpreted by the optimized heat spreading path.

关键词： IGBT module Spreading angle Thermal network model Transient thermal impedance numerical algorithm

来源：评论

学校读者我要写书评

暂无评论

Identification of Thermal Conductivity Coefficient Using a Given Temperature Field

引用

COMPUTATIONAL MATHEMATICS AND MATHEMATICAL PHYSICS 2018年第10期58卷 1585-1599页

The problem of determining the temperature-dependent thermal conductivity coefficient is studied. The study is based on the Dirichlet boundary value problem for the two-dimensional nonstationary heat equation. The cost functional is defined as the rms deviation of the temperature field from experimental data. For the numerical solution of the problem, an algorithm based on the modern fast automatic differentiation technique is proposed. Examples of solving the posed problem are given.

关键词： heat conduction inverse coefficient problems gradient heat equation adjoint equations numerical algorithm

来源：评论

学校读者我要写书评

暂无评论

Nonlinear vibrations of fluid transporting pipelines on a viscoelastic foundation

MAGAZINE OF CIVIL ENGINEERING

引用

MAGAZINE OF CIVIL ENGINEERING 2019年第2期86卷 30-45页

作者： Khudayarov, B. A. Turaev, F. Z. Tashkent Inst Irrigat & Agr Mechanizat Engineers Tashkent Uzbekistan

The article presents the results of a study of vibration process in pipelines conveying fluid or gas. A mathematical model pipeline was used in the form of cylindrical shell and a viscoelastic foundation in the form of two-parameter model of the Pasternak. The hereditary Boltzmann-Volterra theory of viscoelasticity is used to describe viscoelastic properties. The effects of the parameters of the Pasternak foundations, the singularity in the heredity kernels and geometric parameters of the pipeline on vibrations of structures with viscoelastic properties are numerically investigated. It is found that an account of viscoelastic properties of the pipeline material leads to a decrease in the amplitude and frequency of vibrations by 20-40%. It is shown that an account of viscoelastic properties of soil foundations leads to a damping of vibration process in pipeline.

关键词： vibration process foundation pipeline mathematical model numerical algorithm cylindrical shell

来源：评论

学校读者我要写书评

暂无评论

The Dissection algorithm for the Second-Born Self-Energy

引用

PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS 2019年第7期256卷 1800573-1800573页

作者： Perfetto, Enrico Stefanucci, Gianluca CNR ISM Div Ultrafast Proc Mat FLASHit Area Ric Roma 1 Monterotondo Italy Univ Roma Tor Vergata Dipartimento Fis Via Ricerca Sci I-00133 Rome Italy INFN Sez Roma Tor Vergata Via Ric Sci 1 I-00133 Rome Italy

Here, an algorithm to efficiently compute the second-Born self-energy of many-body perturbation theory is described. The core idea consists in dissecting the set of all four-index Coulomb integrals into properly chosen subsets, thus avoiding to loop over those indices for which the Coulomb integrals are zero or negligible. The scaling properties of the algorithm with the number of basis functions is discussed. The computational gain is demonstrated in the case of one-particle Kohn-Sham basis for organic molecules.

关键词： nonequilibrium Green's functions numerical algorithm second-Born self-energy

来源：评论

学校读者我要写书评

暂无评论

Efficient Implementation of a Transport Model in Periodic Layered Structures

引用

COMPUTATIONAL MATHEMATICS AND MATHEMATICAL PHYSICS 2018年第6期58卷 967-975页

作者： Muradyan, M. G. Armenian State Univ Econ Yerevan 0025 Armenia

An analytical representation of the general solution to a finite-difference system describing transport in a periodic medium is found. On the basis of this representation, an efficient numerical algorithm is developed... 详细信息

关键词： transport in periodic media reflection and transmission operators dissipative and conservative transport analogue of the Milne problem numerical algorithm

来源：评论

学校读者我要写书评

暂无评论

algorithm for shear flows in arbitrary cross-sections of thin-walled bars

MAGAZINE OF CIVIL ENGINEERING

引用

MAGAZINE OF CIVIL ENGINEERING 2019年第8期92卷 3-26页

作者： Yurchenko, V Kyiv Natl Univ Construct & Architecture Kiev Ukraine

Development of a general computer program for the design and verification of thin-walled bar structural members remains an actual task. Despite the prevailing influence of normal stresses on the stress-strain state of thin-walled bars design and verification of thin-walled structural members should be performed taking into account not only normal stresses, but also shear stresses. Therefore, in the paper a thin-walled bar of an arbitrary cross-section which is undergone to the general load case is considered as investigated object. The main research question is development of mathematical support and knoware for numerical solution for the shear stresses problem with orientation on software implementation in a computer-aided design system for thin-walled bar structures. The problem of shear stresses outside longitudinal edges of an arbitrary cross-section (including open-closed multi-contour cross-sections) of a thin-walled bar subjected to the general load case has been considered in the paper. The formulated problem has been reduced to the searching problem for unknown shear forces flows that have the least value of the Castigliano's functional. Besides, constraints-equalities of shear forces flows equilibrium formulated for cross-section branch points, as well as equilibrium equation formulated for the whole cross-section relating to longitudinal axes of the thin-walled bar have been taken into account. A detailed numerical algorithm intended to solve the formulated problem has been proposed by the paper. The algorithm is oriented on software implementation in systems of computer-aided design of thin-walled bar structures. Developed algorithm has been implemented in SCAD Office environment by the program TONUS. numerical examples for calculation of thin-walled bars with open and open-closed multi-contour cross-sections have been considered in order to validate developed algorithm and verify calculation accuracy for sectorial cross-section geometrical properties an

关键词： thin-walled bar arbitrary cross-section shear forces flow closed contour graph theory numerical algorithm numerical examples software implementation

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：