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COMPTES RENDUS DE L ACADEMIE DES SCIENCES SERIE II FASCICULE B-MECANIQUE PHYSIQUE ASTRONOMIE 1998年第12期326卷 905-910页

作者： Devries, F Brieu, M Univ Paris 06 ENSC ENSAM UPMCLab Modelisat & Mecan StructCNRSURA 1776 F-75252 Paris 05 France

This paper aims to develop a microscopic-macroscopic approach enabling the simulation of damage propagation in nonlinear elastic materials. The case of multilayered composite materials with imperfect bonding enables to present the method and the proposed non-incremental solution algorithm. (C) Academie des Sciences/Elsevier, Paris.

关键词： elastomer damage nonlinear algorithm

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Input Forces Estimation for nonlinear Systems by Applying a Square-Root Cubature Kalman Filter

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MATERIALS 2017年第10期10卷 1162-1162页

作者： Song, Xuegang Zhang, Yuexin Liang, Dakai Nanjing Univ Aeronaut & Astronaut State Key Lab Mech & Control Mech Struct Nanjing 210016 Peoples R China Southeast Univ Sch Instrument Sci & Engn Key Lab Microinertial Instrument & Adv Nav Techno Minist Educ Nanjing 210096 Jiangsu Peoples R China

This work presents a novel inverse algorithm to estimate time-varying input forces in nonlinear beam systems. With the system parameters determined, the input forces can be estimated in real-time from dynamic responses, which can be used for structural health monitoring. In the process of input forces estimation, the Runge-Kutta fourth-order algorithm was employed to discretize the state equations;a square-root cubature Kalman filter (SRCKF) was employed to suppress white noise;the residual innovation sequences, a priori state estimate, gain matrix, and innovation covariance generated by SRCKF were employed to estimate the magnitude and location of input forces by using a nonlinear estimator. The nonlinear estimator was based on the least squares method. Numerical simulations of a large deflection beam and an experiment of a linear beam constrained by a nonlinear spring were employed. The results demonstrated accuracy of the nonlinear algorithm.

关键词： input forces estimation nonlinear algorithm square-root cubature Kalman filter nonlinear estimator

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Selective image-sharpness enhancement by coupled nonlinear reaction-diffusion time-evolution equations and its application to suppression of breathing distortions in moving pictures

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ELECTRONICS AND COMMUNICATIONS IN JAPAN PART III-FUNDAMENTAL ELECTRONIC SCIENCE 2004年第5期87卷 33-47页

作者： Saito, T Satsumabayashi, J Komatsu, T Kanagawa Univ Fac Engn Yokohama Kanagawa 2218686 Japan

The authors describe a technique for selectively sharpening only edges that were blurred due to various causes without making interference factors such as random noise more conspicuous. The selective sharpening technique described in this paper is implemented as an iterative updating nonlinear algorithm obtained by discretizing a type of nonlinear reaction-diffusion time-evolution equations. The update terms of this algorithm consist of a quadratic nonlinear smoothing term, reaction term, and overshooting term. By performing quantitative evaluation experiments, the authors showed that the proposed technique has significantly better selective sharpness enhancement capabilities than existing sharpness enhancement techniques such as the peaking method. in addition, the authors introduced a processing parameter adaptive control method in the proposed technique and applied it to the suppression of breathing distortions in video sequences. Breathing distortions, which are video sequence distortions that often appear in old films, are time-varying blurring distortions that occur due to temporal variations of the focus. (C) 2004 Wiley Periodicals, Inc.

关键词： nonlinear partial differential equations nonlinear algorithm iterative algorithm time-varying blurring

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A frequency-divided gas prediction technology based on resistivity constraint

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NATURAL GAS INDUSTRY B 2020年第2期7卷 127-132页

作者： Jing Luo Furong Wu Dongjun Zhang Min Xu Hui Chen Jun Fan Liming Zhang Zhenwei Zhao China Natl Petr Corp Southwest Geophys Prospecting Res Inst BGP Inc Chengdu 610213 Sichuan Peoples R China PetroChina Southwest Oil & Gasfield Co Shale Gas Res Inst Chengdu 610056 Sichuan Peoples R China

The gas-water relationship in the Permian and Triassic biohermal beach reservoirs in the Sichuan Basin is complex, which results in a low drilling success rate and leads to sidetracking or even secondary sidetracking in some wells. Therefore, high-precision gas-water identification is the key to the drilling success rate. In this paper, the biohermal gas reservoir in the T work area of the eastern Sichuan Basin was taken as an example. Firstly, the frequency information of seismic data sensitive to gas bearing properties was exploited sufficiently by taking the deep/ shallow resistivity information which is sensitive to gas-water discrimination as a constraint and the nonlinear algorithm as a bridge. Then, combined with the information of full-band relative wave impedance, a nonlinear mapping relationship between the logarithmic difference curve of deep/shallow resistivity and the seismic waveform was established, and the gas bearing properties of the reservoir were predicted. In this way, a post-stack gas prediction method was developed. Finally, field application and effect analysis were carried out. And the following research results were obtained. First, gas layer information indicated by deep/shallow resistivity not only has the function of verification well, but can be extracted as a priori information for the constraint of seismic data. Second, frequency division information increases the mapping relationship between multi-frequency data volume and the logarithmic difference of deep/shallow resistivity, and the colored inversion, as the more reasonable full-band relative-wave impedance seismic data, is more conducive to gas and water identification. Third, based on the nonlinear mapping relationship, the data volume of a gas sensitive factor was obtained, and the range of gas layers was quantified, so as to realize the quantitative characterization of gas bearing properties. It is concluded that the gas prediction technology developed in this paper provides a

关键词： Sichuan Basin Permian-Triassic Biohermal beach reservoir Deep/shallow resistivity Frequency division Relative wave impedance Gas prediction nonlinear algorithm Post-stack prediction

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Contact modeling from images using cut finite element solvers

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ADVANCED MODELING AND SIMULATION IN ENGINEERING SCIENCES 2021年第1期8卷 1-23页

作者： Claus, S. Kerfriden, P. Moshfeghifar, F. Darkner, S. Erleben, K. Wong, C. Off Natl Etud & Rech Aerosp 8 Chemin Huniere F-91120 Palaiseau France PSL Res Univ MAT Ctr Mat Mines ParisTech CNRS UMR 7633 BP 87 F-91003 Evry France Cardiff Univ Sch Engn Cardiff CF243AA Wales Univ Copenhagen Dept Comp Sci Univ Pk 1 DK-2100 Copenhagen Denmark Hvidovre Univ Hosp Dept Orthopaed Surg Kettegaards Alle 30 DK-2650 Hvidovre Denmark

This paper presents a robust digital pipeline from CT images to the simulation of contact between multiple bodies. The proposed strategy relies on a recently developed immersed finite element algorithm that is capable of simulating unilateral contact between solids without meshing (Claus and Kerfriden in Int J Numer Methods Eng 113(6):938-966, 2018). It was shown that such an approach reduces the difficulties associated with the digital flow of information from analytically defined geometries to mechanical simulations. We now propose to extend our approach to include geometries, which are not defined mathematically but instead are obtained from images, and encoded in 3D arrays of voxels. This paper introduces two novel elements. Firstly, we reformulate our contact algorithm into an extension of an augmented Lagrangian CutFEM algorithm. Secondly, we develop an efficient algorithm to convert the surface data generated by standard segmentation tools used in medical imaging into level-set functions. These two elements give rise to a robust digital pipeline with minimum user intervention. We demonstrate the capabilities of our algorithm on a hip joint geometry with contact between the femur and the hip bone.

关键词： Contact nonlinear algorithm LaTIn Nonconforming finite element CutFEM Ghost penalty

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A Novel Method of 6-DoF Electromagnetic Navigation System for Surgical Robot

A Novel Method of 6-DoF Electromagnetic Navigation System fo...

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8th World Congress on Intelligent Control and Automation (WCICA)

作者： Li, Mao Song, Shuang Hu, Chao Chen, Dongmei Meng, Max Q. -H. Chinese Acad Sci Shenzhen Inst Adv Technol Shenzhen Peoples R China Chinese Univ Hong Kong Shatin Peoples R China Chinese Univ Hong Kong Dept Elect Engn Shatin Peoples R China Chinese Acad Sci Shenzhen Inst Adv Technol Shenzhen Peoples R China

ISBN: (纸本)9781424467129

The accurate magnetic localization and orientation technique has dramatically enhanced the applications of capsule endoscope for the gastrointestinal (GI) tract examination. Yet, the surgical robot has been hindered to use widely due to the limitations of current surgical navigation technique. In this paper, an electromagnetic navigation system based on coils and magnetic sensor is introduced. The coils perform as the excitation sources to create the variable magnetic field, and which is received by the magnetic sensor. The coupling between excitation sources and magnetic sensor can determine a set of equations which contain the 6-D parameters of position and orientation information. Then, the nonlinear algorithm is given to solve these equations, and the simulation results show that we can obtain acceptable accuracy of position and orientation through this method. In additional, the relationship between the SNR and the accuracy of position and orientation also be analyzed, at the minimum SNR level with 45dB, the average error of position and orientation are 1mm and 0.5 degrees.

关键词： Electromagnetic Navigation Surgical Robot Localization and Orientation Magnetic Sensing nonlinear algorithm

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High-accuracy three-dimensional tomographic observation of cell clusters 19

High-accuracy three-dimensional tomographic observation of c...

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19th Interferometry Conference

作者： Li, Ying Pan, Feng Ma, Xichao Xiao, Wen Yi, Xiaosu Beihang Univ Sch Instrumentat Sci & Optoelect Engn Key Lab Precis Optomechatron Technol Beijing 100191 Peoples R China

ISBN: (数字)9781510620704

ISBN: (纸本)9781510620704

Digital holographic micro-tomography (DHMT) is widely used for three-dimensional (3-D) detections in biomedical research, from which the information of refractive indexes (RI) distributions of cells obtained can reflect some pathological states. When measuring cells, a capillary is usually used to contain and rotate them. The accuracy of diffraction tomography methods, which is commonly used, is likely to decrease when the object induces complex scattering effects, especially when measuring cell clusters. The nonlinear algorithm based on multi-slice wave propagation method (WPM) we proposed earlier is preferred in these situations. In this paper, we perform 3-D measurements of cell clusters using the setup-rotating system and the WPM-based nonlinear algorithm. Quantitative 3-D distributions of RI can be obtained accurately to display the structures of the cell clusters. The experimental results demonstrate that the WPM-based nonlinear algorithm can provide high accuracy for cell clusters.

关键词： digital holographic micro-tomography refractive indexes distributions cell clusters nonlinear algorithm

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Model-based PDE method and model-free PDE method for motion de-blurring

Model-based PDE method and model-free PDE method for motion ...

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Conference on Visual Communications and Image Processing 2005

作者： Saito, T Harada, H Komatsu, T Kanagawa Univ High Tech Res Ctr Dept Elect Elect & Informat Eng Yokohama Kanagawa 2218686 Japan

ISBN: (纸本)0819459763

Once image motion is accurately estimated, we can utilize those motion estimates for image sharpening and we can remove motion blurs. First, for the motion de-blurring, this paper presents a model-based PDE method that minimizes the regularized energy functional defined with a spatially variant model of motion blurs. Unlike the case of spatially invariant image blurs, the minimization of the energy functional cannot be achieved in a closed non-iterative way, and we derive its iterative algorithm. The standard regularization method uses a square function to measure energy of its solution function, and employs the energy functional composed of the data-fidelity energy term to measure a deviation of a solution function from the assumed model of motion blurs and the regularization energy term to impose smoothness constraints on a solution function. However, the standard variational method is not proper for the motion de-blurring, because it is sensitive to model errors, and occurrence of errors are inevitable in motion estimation. To improve the robustness against the model errors, we employ a nonlinear robust estimation function for measuring energy to be minimized. Secondly, this paper experimentally compares the model-based PDE method with our previously presented model-free PDE method that does not need any accurate blur model. In the model-error-free case the model-based PDE method outperforms the model-free PDE method, whereas in the model-error case the latter works better than the former.

关键词： image sharpening spatially variant image blur regularization nonlinear algorithm iterative algorithm

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Nonparametric and nonlinear reconstruction of surfaces from qualitative observations

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nonlinear ANALYSIS-THEORY METHODS & APPLICATIONS 2005年第5-7期63卷 E1273-E1279页

作者： Rafajlowicz, Ewaryst Krzyzak, Adam Concordia Univ Dept Comp Sci Montreal PQ H3G 1M8 Canada Wroclaw Univ Technol Inst Engn Cybernet PL-50370 Wroclaw Poland

The aim of this paper is to discuss the problem of reconstructing surfaces from qualitative observations. The problem statement is motivated by examples from testing quality of materials. The proposed estimator is nonlinear and nonparametric. Its consistency is discussed and the rate of convergence is given. Then, we propose its smoothed and adaptive version and validate it using simulated data. (C) 2005 Published by Elsevier Ltd.

关键词： Nonparametric reconstruction Qualitative observations nonlinear algorithm Consistency Rate of convergence

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SOFFIT METAL-HALOGEN LAMPS OF 70, 100 AND 150 W POWER FOR COLOUR DECORATIVE AND ARCHITECTURAL ILLUMINATION

LIGHT & ENGINEERING

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LIGHT & ENGINEERING 2009年第3期17卷 37-42页

作者： Vdovin, Vladimir G. Vdovina, Nadezhda A. Lisma VNIIS Open Soc AN Lodygin Saransk Russia

This article presents lighting and colorimetric characteristics of recently developed soffit low-power metal-halogen lamps (LPMHL) of colour radiation intended for decorative and architectural illumination. Characteristics of the lamps, including colour purity and dominant wavelength, correspond to international standards. The results of light flux and colour purity control of these lamps are given using a reduction of the supply line voltage, in accordance with a nonlinear time algorithm, securing a protecting operation mode of the lamps and a direct saving of the electric power (up to 40%) in multiple lamp lighting installations.

关键词： metal halogen lamps (MHL) low-power MHL (LPMHL) soffit LPMHL lighting parameters colorimetric parameters colour purity wavelength (lambda) dominant lambda control (darkening) nonlinear algorithm electric power saving

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