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Discussion of "A 3D image-based method to measure soil stiffness in triaxial tests" by Wang et al. 2024 (DOI: /10.1007/s11440-023-01977-3)

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ACTA GEOTECHNICA 2024年第11期19卷 7759-7761页

作者： Li, Lin Nanjing Forestry Univ Coll Civil Engn 159 Longpan Rd Nanjing 210037 Jiangsu Peoples R China

Wang et al. (2024) proposed a new method to measure soil stiffness through triaxial tests. This discussion illustrates some limitations of the proposed method and details several modifications on the post-image analysis process to enhance its capability. These modifications include the introduction of true stereophotogrammetry for camera and triaxial cell wall orientation, optical ray tracing technique for optical ray reconstruction, and three-dimensional digital image correlation (3D-DIC) for full-field two-dimensional (2D) point cloud generation. With these modifications, the capability of the new method can be significantly improved from only local strain to full-field deformation measurement at a higher accuracy and resolution.

关键词： Camera calibration image-based method Optical ray tracing Triaxial test

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A Compact High-Speed image-based method for Measuring the Longitudinal Motion of Living Tissues

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SENSORS 2020年第16期20卷 4573.-4573.页

作者： Yang, Ruilin Liao, Heqin Ma, Weng Li, Jinhua Wang, Shuxin Tianjin Univ Sch Mech Engn Key Lab Mech Theory & Equipment Design Minist Educ Tianjin 300350 Peoples R China Natl Ocean Technol Ctr Tianjin 300112 Peoples R China

Intraoperative imaging of living tissue at the cell level by endomicroscopy might help surgeons optimize surgical procedures and provide individualized treatments. However, the resolution of the microscopic image is limited by the motion of living tissue caused by heartbeat and respiration. An active motion compensation (AMC) strategy has been recognized as an effective way to reduce, or even eliminate, the influence of tissue movement for intravital fluorescence microscopy (IVM). To realize the AMC system, a high-speed sensor for measuring the motion of tissues is needed. At present, state-of-the-art commercialized displacement sensors are not suitable to apply in minimally invasive imaging instruments to measure the motion of living tissues because of the size problem, range of measurement or the update rate. In this study, a compact high-speed image-based method for measuring the longitudinal motion of living tissues is proposed. The complexity of the proposed method is the same as that of the traditional wide-field fluorescent microscopy (WFFM) system, which makes it easy to be miniaturized and integrated into a minimally invasive imaging instrument. Experimental results reveal that the maximum indication error, range of measurement and the sensitivity of the laboratory-built experimental prototype is 150 mu m, 6 mm and -211.46 mm(-1) respectively. Experimental results indicate that the proposed optical method is expected to be used in minimally invasive imaging instruments to build an AMC system.

关键词： motion of living tissues active motion compensation image-based method simple structure animal experiment

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Performance evaluation of an image-based measurement method used to determine the geometric errors of cone-beam CT instruments

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ADVANCES IN INDUSTRIAL AND MANUFACTURING ENGINEERING 2020年 1卷

作者： Baldo, Crhistian R. Probst, Gabriel M. Dewulf, Wim Fed Univ ABC Ctr Engn Modeling & Appl Social Sci Santo Andre SP Brazil Katholieke Univ Leuven Dept Mech Engn Leuven Belgium

Computed Tomography (CT) has been used in an upward trend to inspect dimensional and geometric characteristics of manufactured parts. The complexity of the measurement chain, however, gives rise to many influence factors that affect the measurement accuracy. Some of these factors are under the control of the user, who needs to properly set some CT instrument parameters for a specific measurement task. Over other influence factors, the user may have some degree of control, such as the interaction of the x-rays with the physical matter, which produces image discrepancies. Finally, there are some influence factors over which the user may have no control at all, such as misalignments resulted from imperfections of the CT instrument hardware. In this regard, this paper describes the experimental evaluation of the geometric errors of a cone-beam CT instrument using an image-based method to map them. The experiments were performed under different test conditions, designed with the main purpose of understanding the behavior of the geometric errors in time and space, as well as assisting the appropriate actions to be taken for e.g. error correction by software. Special attention was given to the evaluation of the effectiveness of the measurement method itself to detect the geometric errors.

关键词： CT instruments Geometric errors image-based method Experimental data analysis

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An image-based method to automatically propagate bony landmarks: application to computational spine biomechanics

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COMPUTER methodS IN BIOMECHANICS AND BIOMEDICAL ENGINEERING 2015年第14期18卷 1535-1542页

作者： de Oliveira, Marcelo E. Netto, Luiz M. G. Kistler, Michael Brandenberger, Daniel Buechler, Philippe Hasler, Carol-C. Swiss Fed Inst Technol Robot Syst Lab CH-1015 Lausanne Switzerland Univ Bern Grad Sch Cellular & Biomed Sci Bern Switzerland State Univ Sao Paulo Dept Mat Sci Sao Paulo Brazil Univ Bern Inst Surg Technol & Biomech Bern Switzerland Univ Childrens Hosp Dept Orthopaed Basel Switzerland

In attempts to elucidate the underlying mechanisms of spinal injuries and spinal deformities, several experimental and numerical studies have been conducted to understand the biomechanical behavior of the spine. However, numerical biomechanical studies suffer from uncertainties associated with hard- and soft-tissue anatomies. Currently, these parameters are identified manually on each mesh model prior to simulations. The determination of soft connective tissues on finite element meshes can be a tedious procedure, which limits the number of models used in the numerical studies to a few instances. In order to address these limitations, an image-based method for automatic morphing of soft connective tissues has been proposed. Results showed that the proposed method is capable to accurately determine the spatial locations of predetermined bony landmarks. The present method can be used to automatically generate patient-specific models, which may be helpful in designing studies involving a large number of instances and to understand the mechanical behavior of biomechanical structures across a given population.

关键词： automatic morphing soft connective tissues finite element meshes image-based method

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Point density for soil specimen volume measurements in image-based methods during triaxial testing

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ACTA GEOTECHNICA 2023年第11期18卷 5661-5679页

作者： Fayek, Sara Zhang, Xiong Galinmoghadam, Javad Cawlfield, Jeffrey Missouri Univ Sci & Technol Civil Architectural & Environm Engn Rolla MO 65409 USA Missouri Univ Sci & Technol Geosci & Geol & Petr Engn Rolla MO 65409 USA

Discrete measurement targets were frequently utilized in image-based methods on the specimen's surface to monitor the soil specimen during triaxial testing. However, the required density of measurement targets that should be used in triaxial testing to achieve highly accurate volume measurement has not been investigated. To overcome this limitation, this paper presents a parametric study to determine the optimum target/point densities to be utilized on the triaxial soil specimen surface to achieve the desired level of volume measurement accuracy in image-based methods. LiDAR scanning was applied to establish the "ground truth" volume of the specimen. The effects of deformation and failure modes were investigated by calculating the volume measurement accuracy at different strain levels and for different undisturbed soil specimens of clay and sand with silt. An interpolation method was proposed to increase the number of discrete targets representing the triaxial specimen's surface. The analysis results show that a higher target density is required at a larger strain. Also, adding the number of interpolation points can only increase the accuracy to a certain level. As the volume measurement accuracy was different for each of the clay and sand with silt specimens, the non-uniform deformation, and failure mode of the specimen can affect the required optimum density of discrete measurement targets. In conclusion, it is recommended to choose the optimum density of targets based on the accuracy requirement, the maximum soil deformation level, and the expected failure mode of the specimen.

关键词： image-based method LiDAR Triaxial testing Volume measurement

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Polydisperse particle inline image method and its application onto gas-liquid flow in a stirred tank

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AICHE JOURNAL 2024年第6期70卷 e18398-e18398页

作者： Wang, Haoliang Yang, Li Li, Xiangyang Cheng, Jingcai Yang, Chao Chinese Acad Sci Inst Proc Engn State Key Lab Petr Mol & Proc Engn CAS Key Lab Green Proc & Engn Beijing 100190 Peoples R China Hubei Three Gorges Lab Yichang Peoples R China Sichuan Univ Coll Chem Engn Chengdu 610065 Peoples R China Univ Chinese Acad Sci Sch Chem Engn Beijing Peoples R China

Bubbles of different sizes exhibit distinct hydrodynamic behaviors and their dense coexistence complicates seriously the multiphase flow. The commonly-used arithmetic average method (e.g., PIV) treats every bubble equally and consequently erases many physical details. In this study, a polydisperse particle inline image method is developed to simultaneously measure comprehensive feature set of every bubble in bubble swarms and carrier phase velocity. By harnessing the optimal frame rate capture alongside assigning IDs for tracking, complete identification of polydisperse swarm in single frame is integrated with the accurate acquisition of transient dynamics across multiple frames. In gas-liquid stirred tanks, the bubble deformation is notably intensified owing to the presence of collisions driven by velocity differences. A novel analysis of bubble hydrodynamics decomposed by bubble size reveals they are jointly commanded by the inertial effect and size effect. Actual flow regime of the system is essentially the superposition of multiple dissimilar flow patterns.

关键词： bubble dynamic behaviors bubble size distribution image-based method multiphase reactor stirred tank

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image-based estimation method for field inhomogeneity in brain echo-planar images with geometric distortion using k-space textures

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CONCEPTS IN MAGNETIC RESONANCE PART B-MAGNETIC RESONANCE ENGINEERING 2015年第3期45卷 142-152页

作者： Kumazawa, Seiji Yoshiura, Takashi Honda, Hiroshi Kyushu Univ Fac Med Sci Dept Hlth Sci Fukuoka Fukuoka 8128582 Japan Hokkaido Univ Sci Fac Hlth Sci Dept Radiol Technol Sapporo Hokkaido 0068585 Japan Kagoshima Univ Grad Sch Med & Dent Sci Dept Radiol Kagoshima Kagoshima 8908520 Japan Kyushu Univ Grad Sch Med Sci Dept Clin Radiol Fukuoka Fukuoka 8128582 Japan

Echo-planar imaging (EPI) can suffer from geometrical distortion due to magnetic field inhomogeneity. To correct the geometric distortions in EPI, a magnetic field map is used. Our purpose was to develop a novel image-based method for estimating the field inhomogeneity map from the distorted EPI image and T1-weighted image of the brain using k-space textures. based on magnetic resonance imaging physics, our method synthesizes the distorted image to match the measured EPI image through the generating process of EPI image by updating the estimated field inhomogeneity map. The estimation process was performed to minimize the cost function, which was defined by the synthesized EPI image and the measured EPI image with geometric distortion, using an iterative conjugate gradient algorithm. The proposed method was applied to simulation and human data. To evaluate the performance of the proposed method quantitatively, we used the normalized root mean square error (NRMSE) between the ground truth and the results estimated by our proposed method. In simulation data, the values of the NRMSE between the ground truth and the estimated field inhomogeneity map were <0.08. In both simulation and human data, the estimated EPI images were very similar to input EPI images, and the NRMSE values between them were <0.09. The results of the simulated and human data demonstrated that our method produced a reasonable estimation of the field inhomogeneity map. The estimated map could be used for distortion correction in EPI images. (c) 2015 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 45B: 142-152, 2015

关键词： echo-planar imaging field inhomogeneity geometric distortion image-based method k-space texture

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Bubble boundary R-CNN: A multitask model for segmenting and reconstructing overlapping bubbles

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SEPARATION AND PURIFICATION TECHNOLOGY 2025年 358卷

作者： Kang, Qizhou Ye, Feng Li, Qin Li, Ru Wang, Jianfeng Wang, Haoliang Yu, Hui Cheng, Jingcai Li, Xiangyang Yang, Chao Sichuan Univ Sch Chem Engn Chengdu 610065 Peoples R China Zhengzhou Univ Sch Ecol & Environm Zhengzhou 450001 Peoples R China Chinese Acad Sci Inst Proc Engn CAS Key Lab Green Proc & Engn State Key Lab Petr Mol & Proc Engn Beijing 100190 Peoples R China

When measuring the dynamic characteristics of bubbles using image-based methods, the images including complex overlapping of bubbles with irregular shape pose a huge challenge to current bubble reconstruction algorithms. based on the Mask R-CNN architecture, a multitask model "Bubble Boundary R-CNN" is proposed for detection, segmentation and shape reconstruction of overlapping bubbles with high deformation at high gas velocities. By leveraging shared deep features from detection and segmentation, model achieves flexible bubble reconstruction and accurate size distribution extraction from high gas velocity bubble flows. To overcome the limitations of Mask R-CNN and address the challenges posed by high-deformation and overlapping bubbles, a semantic segmentation auxiliary head and the Boundary-preserving Mask Head (BMask Head) are introduced to enhance edge information and extract bubble boundary features. Additionally, an Overlapping Boundary Prediction Network (OBPN) is proposed to reconstruct boundary features that are lost due to bubble occlusion and predict the complete bubble shapes. The optimized model shows its ability to flexibly and accurately reconstruct overlapped and deformed bubbles by varying occlusion rates and circularity. The new model has also proven its reliability when applied to bubble images from a bubble column at gas velocities of up to 0.067 m3/s. In future work, more efforts are needed to further enhance the detection capability of the model and reduce missed and multiple detections at high gas velocity.

关键词： image-based method Bubbles overlapping Mask R -CNN Segmenting Reconstruction

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Analytical verification of FFT-based micromechanical simulations near an elliptical crack tip by using composite voxels

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MECHANICS OF ADVANCED MATERIALS AND STRUCTURES 2024年第28期31卷 10859-10868页

作者： Tari, Vahid Kantzos, Christopher Anglin, Benjamin S. Rollett, Anthony D. ATI Specialty Mat Monroe NC 28111 USA Carnegie Mellon Univ Dept Mat Sci & Engn Pittsburgh PA USA

In this paper, we make use of composite voxels in elasto-viscoplastic formulations based on fast Fourier transforms (EVPFFT) to calculate the stress field around an elliptical crack. The predicted stress field at the vicinity of the crack is verified against recently developed analytical solutions. The representation of an elliptical crack in the image-based method is stair-stepped, resulting in oscillations that are mitigated by the use of partially-filled, i.e. composite voxels. Dependencies of the oscillations in the predicted stress fields based on minor changes in the crack size crack size and aspect ratio are discussed and quantified. New understanding is gained of the factors that affect the oscillations, such as the aspect ratio of the ellipse, and the effect of minor changes in the crack interface location. The results show that the use of composite voxels significantly reduces the spurious oscillations in predicted stress fields, and consequently improves the agreement between the EVPFFT simulations and analytical solutions.

关键词： Elasto-viscoplastic fast Fourier transforms elliptical crack composite voxels image-based method

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Bildbasierte Frischbetonprüfung

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BETON- UND STAHLBETONBAU 2023年第10期118卷 716-724页

作者： Schack, Tobias Coenen, Max Haist, Michael Leibniz Univ Hannover Inst Baustoffe Appelstr 9a D-30167 Hannover Germany

Homogenitat - d.h. die Gleichmassigkeit der Zusammensetzung und Eigenschaften des Betons im frischen und festen Zustand - ist eine zentrale Anforderung an den Baustoff Beton. Variationen der Homogenitat aussern sich in der Regel in lokalen Veranderungen z.B. des E-Moduls, der Festigkeit oder Dauerhaftigkeit. Insbesondere bei hochfliessfahigen (>= F5) und selbstverdichtenden Betonen (SVB), aber z.B. auch bei LP-Betonen ist die Homogenitat eine zeitabhangige Grosse und andert sich durch Entmischungsprozesse wie z.B. Sedimentation der groben Gesteinskornung und Wasserabsonderung oder infolge einer ungeeigneten Verarbeitung. Eine Bewertung der Homogenitat des frischen Betons ist mit den gegenwartigen Prufverfahren auf der Baustelle nur augenscheinlich moglich, da insbesondere die raumliche Verteilung der Betonausgangsstoffe (und damit die Homogenitat) bislang nicht quantifiziert werden kann. Aufbauend auf den bereits in den ersten beiden Teilen dieses Beitrags vorgestellten bewertbaren Eigenschaften wird in diesem Beitrag das Eigenschaftsspektrum der bildbasierten Frischbetonprufung um die Homogenitat des Frischbetons erweitert. Dazu werden visuell erfassbare Eigenschaften des ausgebreiteten Frischbetons im Rahmen der Ausbreitmassprufung - Leimabsonderungen im Randbereich sowie geometrische Verteilung der Gesteinskornung an der Oberflache - herangezogen. image-based quality conctrol - part 3: homogeneity of fresh concreteHomogeneity - i.e. the uniformity of the composition and properties of concrete in its fresh and hardened state - is a central requirement for concrete as a building material. Variations in homogeneity usually expressed in local changes, e.g. in the modulus of elasticity, strength or durability. Especially in the case of highly flowable (>= F5) and self-compacting concretes (SCC) but also, for example, in the case of air entrained concretes, homogeneity is a time-dependent variable and changes due to segregation processes such as sedimentation and bleed

关键词： digitale Qualitatsprufung bildbasierte methodik Ausbreitmassprufung Homogenitat Entmischung digital quality control image-based method flow table test homogeneity segregation

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