检索结果-南通市图书馆

A nonparametric spectrum estimation method for dispersion and attenuation analysis of borehole acoustic measurements

引用

Petroleum Science 2023年第1期20卷 241-248页

作者： Bing Wang Wei Li Qing Ye Kun-Yu Ma State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China Beijing Research Center Aramco AsiaBeijing100102China

dispersion and attenuation analysis can be used to determine formation anisotropy induced by fractures,or *** this paper,we propose a nonparametric spectrum estimation method to get phase dispersion characteristics and attenuation *** designing an appropriate vector filter,phase velocity,attenuation coefficient and amplitude can be inverted from the waveform recorded by the receiver *** analysis of this algorithm is compared with Extended Prony Method(EPM)and Forward and Backward Matrix Pencil(FBMP)*** on the analysis results,the proposed method is capable of achieving high resolution and precision as the parametric spectrum estimation *** the meantime,it also keeps high stability as the other nonparametric spectrum estimation *** last,applications to synthetic waveforms modeled using finite difference method and real data show its *** real data processing results show that the P-wave attenuation log is more sensitive to oil formation compared to S-wave;and the S-wave attenuation log is more sensitive to shale formation compared to P-wave.

关键词： dispersion analysis Attenuation factor Nonparametric spectrum estimation method Acoustic logging Fluid type evaluation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

analysis of high-frequency local coupling instability induced by multi- transmitting formula - P-SV wave simulation in a 2D waveguide

引用

Earthquake Engineering and Engineering Vibration 2017年第1期16卷 1-10页

作者： Xie Zhinan Zhang Xubin Institute of Engineering Mechanics China Earthquake Administration Key Laboratory of Earthquake Engineering and Engineering vibration of China Earthquake Administration Harbin 150080 China

Local coupling instability will occur when the numerical scheme of absorbing boundary condition and that of the field wave equation allow energies to spontaneously enter into the computational domain. That is, the two schemes support common wave solutions with group velocity pointed into the computation domain. The key to eliminate local coupling instability is to avoid such wave solutions. For lumped-mass finite element simulation of P-SV wave motion in a 2D waveguide, an approach for stable implementation of high order multi-transmitting formula is provided. With a uniform rectangular mesh, it is proven and validated that high-freqaency local coupling instability can be eliminated by setting the ratio of the element size equal to or greater than x/2 times the ratio of the P wave velocity to the S wave velocity. These results can be valuable for dealing instability problems induced by other absorbing boundary conditions.

关键词： absorbing boundary condition local coupling instability dispersion analysis group velocity multi-transmitting formula

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Effect of Element Distortion on the Numerical dispersion of Spectral Element Methods

引用

Communications in Computational Physics 2011年第4期9卷 937-958页

作者： S.P.Oliveira G.Seriani Departamento de Matematica Universidade Federal do ParanaCuritiba-PR81531-980Brazil Istituto Nazionale di Oceanografia e di Geofisica Sperimentale Borgo Grotta Gigante42/cSgonico(TS)34010Italy

Spectral element methods are well established in the field of wave propagation,in particular because they inherit the flexibility of finite element methods and have low numerical dispersion *** latter is experimentally acknowledged,but has been theoretically shown only in limited cases,such as Cartesian *** is well known that a finite element mesh can contain distorted elements that generate numerical errors for very large *** the present work,we study the effect of element distortion on the numerical dispersion error and determine the distortion range in which an accurate solution is obtained for a given error *** also discuss a double-grid calculation of the spectral element matrices that preserves accuracy in deformed geometries.

关键词： Spectral element method dispersion analysis slivering

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Numerical study of dispersion characteristics of dipole flexural waves in a cased hole with different cement conditions

引用

Applied Geophysics 2022年第1期19卷 29-40,143,144页

作者： Yang Meng-En Lv Wei-Guo Wu Yang Cui Zhi-Wen Liu Jin-Xia College of Physics Jilin UniversityChangchun 130021China

Crossed-dipole acoustic logging technology is mainly used to measure shear wave and determine the anisotropy or fractures of formation in the fi eld of acoustic *** on the propagation characteristics of dipole flexural waves in cased holes,and the wavefi eld of fundamental flexural mode at three bonding conditions:good cement bonding,poorly bonded interface I,and poorly bonded interface *** dispersion curves of flexural waves are calculated,and the eff ects of cement parameters(elastic parameters and geometric dimensions)on dispersion curves are *** RAI method is used to calculate the dipole full waveforms in a cased hole with conventional or ultralight cement surrounded by a soft ***,the weighted spectral semblance is used to conduct the dispersion analysis of the full *** numerical results show that the cutoff frequency of flexural waves exceeds the frequency band of the current dipole logging tools in the well-bonded cased hole with conventional cement in soft ***,when ultralight cement is used,the cutoff frequency shifts toward low values,and the ultralight cement bonding is conducive to measuring flexural waves in soft *** interface I is poorly bonded,the cutoff frequency shifts toward low values,and the change is evident in soft *** cutoff frequency in the case of ultralight cement bonding is more evident than that of conventional cement *** only interface II is poorly bonded,regardless of the cement used,the cutoff frequencies are all below 2 *** dipole full-wave analysis of diff erent bonding conditions further illustrates that the dispersion characteristics of flexural waves are sensitive to the cement bonding quality of cased holes.

关键词： Soft formation cased borehole flexural wave ultralight cement dispersion analysis cement bonding

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Static and Dynamic Indicators in the analysis of Internal Sources of Companies＇ Investments Financing

引用

Journal of Modern Accounting and Auditing 2017年第3期13卷 108-120页

作者： Rajko M. Bukvic Radica Z. Pavlovic Aleksandar M. Gajic Geographical Institute "Jovan Cvijic" of the Serbian Academy of Sciences and Arts Belgrade Serbia Nizhny Novgorod State University of Engineering and Economics Knyaginino Russia University John Naisbitt Belgrade Serbia Higher Business School of Professional Studies "Prof. dr Radomir Bojkovic" Krusevac Serbia

The Republic of Serbia is characterized by an unsatisfactory macroeconomic environment. Under the conditions of an evident shortage of liquid assets, the financial capital has moved from real to the financial sector, which led companies to over-indebtedness and shutdown of their own capacities. Therefore, capital investments largely depend on internal financing sources and the ability of companies to internally generate funds for investments. In this regard, an emphasis is placed on the difference in the assessment of the company＇s investment capacity based on internal financing sources, which are measured using static and dynamic indicators in order to prove the necessity of applying dynamic coefficients, which are unfortunately not present in our domestic practice. The paper examines and proves the advantages of the use of the dynamic approach for such analyses using the example of energy sector, which is one of the most important branches in Serbian economy.

关键词： dynamic and static coefficients dynamic analysis investments financing sources dispersion analysis

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

THE CAUCHY PROBLEM OF THE HARTREE EQUATION

引用

Journal of Partial Differential Equations 2008年第1期21卷 22-44页

作者： Miao Changxing Xu Guixiang Zhao Lifeng Institute of Applied Physics and Computational Mathematics P. O. Box 8009 Beijing 100088 China

In this paper, we systematically study the wellposedness, illposedness of the Hartree equation, and obtain the sharp local wellposedness, the global existence in Hs, s≥1 and the small scattering result in Hs for 2 〈γ〈 n and s ≥ 2/γ - 1. In addition, we study the nonexistence of nontrivial asymptotically free solutions of the Hartree equation.

关键词： Hartree equation well-posedness illposedness Galilean invariance dispersion analysis scattering asymptotically free solutions.

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

A meshfree method for inverse wave propagation using collocation and radial basis functions

A meshfree method for inverse wave propagation using colloca...

引用

第十一届南方计算力学学术会议（SCCM-11）

作者： Lihua Wang Zhen Wang Zhihao Qian School of Aerospace Engineering and Applied Mechanics Tongji University

A stable and highly accurate meshfree scheme based on strong form collocation associated with radial basis functions and explicit time integration is proposed to solve ill-posed inverse wave propagation problems. Tikhonov regularization technique and the L-curve criterion are employed to deal with the noise measurement data before solving the governing equation to get a stable solution. Appropriate weights are first derived for imposing boundary conditions and known conditions from the measurement data to yield the optimal convergence for inverse problems. Compared to the required iterative procedures in common methods, no iteration is needed in the proposed method which leads to the time-saving computation and avoids the instability resulting from the iterative methods. dispersion analysis describes that this method has much less dispersion error than the classical finite element method(FEM) and popular weak form meshfree methods, and stability analysis is performed to predict the critical time step for the explicit time integration. Another outstanding advantage of this method is it’s effortless to extend the solution scheme of one-dimensional inverse problem to high-dimensional inverse problems. Furthermore, the influences of the high noise into measurement data are evaluated, which demonstrate that even handling with very high noise in the input data the proposed algorithm can achieve stable and high-accuracy solutions.

关键词： strong form collocation radial basis functions ill-posed inverse wave propagation problem Tikhonov regularization dispersion analysis stability analysis

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

欢迎您,

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

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

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

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

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：