检索结果-内蒙古大学图书馆

New possibilities of increasing accuracy for nondestructive testing - Part 2. Data processing algorithms

NDT & E INTERNATIONAL 1999年第7期32卷 403-408页

作者： Matiss, I Rotbakh, Y Latvian Acad Sci Inst Polymer Mech LV-1050 Riga Latvia

Data processing algorithms (multiparameter, correction, extrapolation) are considered for the testing methodology by calibrated disturbing factors. Multiparameter evaluation of several input parameters is based on forming independent testing channels and solving a set of equations. The correction algorithm provides the difference between ideal and disturbed calibration dependencies and therefore produces correction of measurement results. Several extrapolation algorithms make use of data transformation from the measurement range available for calibration to the real conditions of an experiment influenced by disturbing factors. (C) 1999 Elsevier Science Ltd. All rights reserved.

关键词： correction algorithm disturbing influence approximation extrapolation unilateral transducer

来源：评论

学校读者我要写书评

暂无评论

Correcting Calibrated Infrared Sky Imagery for the Effect of an Infrared Window

引用

JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY 2009年第11期26卷 2403-2412页

作者： Nugent, Paul W. Shaw, Joseph A. Pust, Nathan J. Piazzolla, Sabino Montana State Univ Elect & Comp Engn Dept Bozeman MT 59717 USA CALTECH Jet Prop Lab Pasadena CA USA

A method is demonstrated for deriving a correction for the effects of an infrared window when used to weatherproof a radiometrically calibrated thermal infrared imager. The technique relies on initial calibration of two identical imagers without windows and subsequently operating the imagers side by side: one with a window and one without. An equation is presented that expresses the scene radiance in terms of through-window radiance and the transmittance, reflectance, and emissivity of the window. The window's optical properties are determined as a function of angle over the imager's field of view through a matrix inversion using images observed simultaneously with and without a window. The technique is applied to calibrated sky images from infrared cloud imager systems. Application of this window correction algorithm to data obtained months before or after the algorithm was derived leads to an improvement from 0.46 to 0.91 for the correlation coefficient between data obtained simultaneously from imagers with and without a window. Once the window correction has been determined, the windowed imager can operate independently and provide accurate measurements of sky radiance.

关键词： correction algorithm Infrared radiation imaging instrument sky radiance window matrix inversion Emissivity

来源：评论

学校读者我要写书评

暂无评论

A technique of measuring and correcting emittance dilutions due to accelerator structure misalignments

引用

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 1996年第2-3期370卷 303-311页

作者： Raubenheimer, TO Kubo, K KEK TSUKUBAIBARAKI 305JAPAN

This paper describes a method of reducing the transverse emittance dilution in linear colliders due to transverse wakefields arising from misaligned accelerator structures. The technique is a generalization of the Wake-Free [T.O. Raubenheimer, Nucl. Instr. and Meth. A 306 (1991) 61] correction algorithm. The structure errors are measured locally by varying the bunch charge and/or bunch length and measuring the change in the beam trajectory. The structure errors can then be corrected by varying the trajectory or moving the structures. The results of simulations are presented demonstrating the viability of the technique.

关键词： Linear colliders correction algorithm LINEAR COLLIDERS Technology Accelerators emission

来源：评论

学校读者我要写书评

暂无评论

Solution of the Navier-Stokes equation with finite-differences on unstructured triangular meshes

引用

COMPUTERS & FLUIDS 1998年第5-6期27卷 695-708页

作者： Dwyer, HA Grcar, J Univ Calif Davis Davis CA 95616 USA Sandia Natl Labs Livermore CA USA

A low Mach number model of the Navier-Stokes equations has been developed for unstructured meshes. The numerical method combines many attractive features of the finite volume method and unstructured finite elements, however, inside the elements a finite difference scheme based on generalized coordinate transformations has been applied. The method of solution of the equations is a well developed pressure correction algorithm that has worked well previously for structured meshes. The physical applications in the paper include axisymmetry and two-dimensional problems, as well as variable density solutions of the Navier-Stokes equations. It is the authors' opinion that some of the methods developed in the paper may have been used by other investigators, however, we have not found references in the literature that explicitly use finite differences to solve flows on unstructured element based meshes. A major goal of the paper is to show some of the similarities between the finite element and the difference methods that are both very popular at the present time. It is hoped that these similarities will lead to better understanding and improvements in both techniques. (C) 1998 Elsevier Science Ltd. All rights reserved.

关键词： correction algorithm AXISYMMETRIC Finite differences FINITE ELEMENT finite volume method Numerical methods triangular mesh Analogy Navier-Stokes equations Meshes

来源：评论

学校读者我要写书评

暂无评论

Numerical Integration with Constraints for Mesh less Local Petrov-Galerkin Methods

引用

CMES-COMPUTER MODELING IN ENGINEERING & SCIENCES 2013年第3期95卷 205-228页

作者： Sun, L. Yang, G. Zhang, Q. Guangdong Univ Petrochem Technol Sch Sci Maoming 525000 Guangdong Peoples R China Zhongyuan Univ Technol Sch Comp Sci Zhengzhou 450007 Peoples R China Sun Yat Sen Univ Guangdong Prov Key Lab Computat Sci Guangzhou 510275 Guangdong Peoples R China Sun Yat Sen Univ Dept Sci Comp & Comp Applicat Guangzhou 510275 Guangdong Peoples R China

We propose numerical integration rules for meshless local Petrov-Galerkin methods (MLPG) employed to solve elliptic partial different equations (PDE) with Neumann boundary conditions. The integration rules are required to satisfy an integration constraint condition of Green's formula type (GIC). GIC was first developed in [Babuska, Banerjee, Osborn, and Zhang (2009)] for Galerkin meshless method, and we will show in this paper that it has better features for MLPG due to flexibility of MLPG in choosing different trial and test function spaces. A general constructive algorithm is presented to design the integration rules satisfying GIC. We also present a useful situation, where GIC holds automatically for Gaussian rules. According to this, we conclude that the conical weight is suggested to adopt in MLPG from viewpoint of reducing integration complexity. Approach to extending GIC in [Babuska, Banerjee, Osborn, and Zhang (2009)] to more general elliptic PDE, such as elasticity equation, is discussed. The 1D and 2D numerical results illuminate that GIC reduces the errors in the approximate solutions of MLPG significantly.

关键词： Meshless Petrov-Galerkin method (MLPG) numerical integration integration constraint Green's formula correction algorithm conical weight

来源：评论

学校读者我要写书评

暂无评论

Modeling and Kinematic Path Selection of Retractable Kirigami Roof Structures

引用

COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING 2019年第4期34卷 352-363页

作者： Cai, Jianguo Zhang, Qian Feng, Jian Xu, Yixiang Southeast Univ Natl Prestress Engn Res Ctr Minist Educ Key Lab C & PC Struct Nanjing Jiangsu Peoples R China Univ Sheffield Adv Mfg Res Ctr Sheffield S Yorkshire England

This article proposes a numerical method for the kinematic path modeling of retractable roof structures based on the concept of kirigami. The kinematics of origami structures have been studied by many researchers. However, the singular point in the kinematic path which will crucially affect the overall performance of the structure has not been investigated. In this article, the method to detect the singular point in the kinematic path is first introduced. Then, a prediction-correction algorithm is developed to simulate the motion along a uniquely determined path. A second-order program is used to select kinematic paths deviating from a singular point. After that, the proposed method is applied in the kinematic modeling of a kirigami structure to show its accuracy.

关键词： Singular Modeling kinematics Numerical methods Byways correction algorithm roof structure

来源：评论

学校读者我要写书评

暂无评论

Thermal expansion coefficient and algebraic models to correct values of specific mass as a function of temperature for corn biodiesel

引用

FUEL 2013年 106卷 646-650页

作者： Santos, Douglas Queiroz de Lima, Ana Lucia de Lima, Ana Paula Borges Neto, Waldomiro Fabris, Jose Domingos Univ Fed Uberlandia Inst Chem BR-38408100 Uberlandia MG Brazil Fed Univ Jequitinhonha & Mucuri Valleys UFVJM BR-39100000 Diamantina MG Brazil

Values of thermal expansion coefficients (b) were experimentally determined for three samples: a mineral diesel and two biodiesels constituted by either fatty acid ethyl esters (FAEE) or fatty acid methyl esters (FAME), from transesterification reactions using raw corn oil and ethyl or methyl alcohol. Values of b were found to be 8.36 (+/- 0.06) 10(-4) degrees C-1, 8.43 (+/- 0.09) x 10(-4) degrees C-1 and 8.39 (+/- 0.03) x 10(-4) degrees C-1, respectively, within 95% of statistical confidence. The thermal expansion coefficients for biodiesels from corn are higher than that for the mineral diesel. The expansion coefficient is also a key parameter in modeling fuel injection system of internal combustion engines. Comparing the two sets of data, for fossil diesel and biodiesel provides essential information to support the design and optimization of more efficient engines. A higher value for the cubic expansion coefficient implies that less specific mass of fuel is injected at higher temperatures, which can cause a loss in engine power. This is a fundamental parameter, reinforcing further the interest to establish an algebraic model to estimate the specific mass for a biofuel as a function of temperature, which is thought to be significantly different from that more commonly used for the fossil diesel. Polynomial models for such a correction were determined in this work;resulting rates for diesel and for corn oil biodiesels, based on either fatty acid methyl esters (FAME) or fatty acid ethyl esters (FAEE), were respectively -0.7089 kg m(-3) T-1, -0.7323 kg m(-3) T-1 and -0.7313 kg m(-3) T-1. From the linear correlation between these data and those from standard EN 14214, values for the sensitivity (slope term) are seemingly small, or roughly 0.723, but are high enough to cause relatively large impacts, in financial terms, for cases involving considerably big volumes of biodiesel, in commercial transactions. (c) 2012 Elsevier Ltd. All rights reserved.

关键词： Biodiesel Expansion coefficient correction algorithm Specific mass

来源：评论

学校读者我要写书评

暂无评论

A principal component analysis approach to correcting the knee flexion axis during gait

引用

JOURNAL OF BIOMECHANICS 2016年第9期49卷 1698-1704页

作者： Jensen, Elisabeth Lugade, Vipul Crenshaw, Jeremy Miller, Emily Kaufman, Kenton Mayo Clin Mayo Grad Sch Biomed Engn & Physiol Track Rochester MN 55905 USA Mayo Clin Div Orthoped Res Mot Anal Lab Charlton North L-1101 Rochester MN 55905 USA Chiang Mai Univ Dept Phys Therapy Whitaker Int Program Chiang Mai 50200 Thailand Univ Delaware Dept Kinesiol & Appl Physiol Newark DE 19713 USA

Accurate and precise knee flexion axis identification is critical for prescribing and assessing tibial and femoral derotation osteotomies, but is highly prone to marker misplacement-induced error. The purpose of this study was to develop an efficient algorithm for post-hoc correction of the knee flexion axis and test its efficacy relative to other established algorithms. Gait data were collected on twelve healthy subjects using standard marker placement as well as intentionally misplaced lateral knee markers. The efficacy of the algorithm was assessed by quantifying the reduction in knee angle errors. Crosstalk error was quantified from the coefficient of determination (r(2)) between knee flexion and adduction angles. Mean rotation offset error (alpha(o)) was quantified from the knee and hip rotation kinematics across the gait cycle. The principal component analysis (PCA)-based algorithm significantly reduced r(2) (p < 0.001) and caused alpha(o,knee) to converge toward 11.9 +/- 8.0 degrees of external rotation, demonstrating improved certainty of the knee kinematics. The within-subject standard deviation of alpha(o,hip) between marker placements was reduced from 13.5 +/- 1.5 degrees to 0.7 +/- 0.2 degrees (p < 0.001), demonstrating improved precision of the knee kinematics. The PCA-based algorithm performed at levels comparable to a knee abduction-adduction minimization algorithm (Baker et al., 1999) and better than a null space algorithm (Schwartz and Rozumalski, 2005) for this healthy subject population. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Gait analysis Kinematics Axis of rotation Marker placement correction algorithm

来源：评论

学校读者我要写书评

暂无评论

Increasing the Accuracy of Data-Measuring Systems for the Nondestructive Testing of the Thermal Properties of Solids

引用

MEASUREMENT TECHNIQUES 2015年第9期58卷 1010-1015页

作者： Selivanova, Z. M. Khoan, T. A. Tambov State Tech Univ Tambov Russia

A solution of the problem of increasing the accuracy of a data-measuring system for the nondestructive testing of the thermal properties of materials is proposed. An algorithm for correcting the technical imperfection of the structural components of the system, based on the use of a mathematical model of the measurement procedure and information on influencing destabilizing factors, is developed.

关键词： data-measuring system thermal properties of materials mathematical model intelligent sensor correction algorithm

来源：评论

学校读者我要写书评

暂无评论

A model-based Bayesian framework for ECG beat segmentation

引用

PHYSIOLOGICAL MEASUREMENT 2009年第3期30卷 335-352页

作者： Sayadi, O. Shamsollahi, M. B. Sharif Univ Technol Sch Elect Engn Biomed Signal & Image Proc Lab BiSIPL Tehran Iran

The study of electrocardiogram (ECG) waveform amplitudes, timings and patterns has been the subject of intense research, for it provides a deep insight into the diagnostic features of the heart's functionality. In some recent works, a Bayesian filtering paradigm has been proposed for denoising and compression of ECG signals. In this paper, it is shown that this framework may be effectively used for ECG beat segmentation and extraction of fiducial points. Analytic expressions for the determination of points and intervals are derived and evaluated on various real ECG signals. Simulation results show that the method can contribute to and enhance the clinical ECG beat segmentation performance.

关键词： correction algorithm ECG dynamical model extended Kalman filter fluctuating estimates fiducial points extraction segmentation

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：