Stress wave velocity patterns in the longitudinal–radial plane of trees for defect diagnosis

Li, Guanghui; Weng, Xiang; Du, Xiaocheng; Feng, Hailin

doi:10.1016/j.compag.2016.03.021

Cited by 15 publications

(9 citation statements)

References 13 publications

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“…In contrast, other studies found that the stress wave detection method should be improved. For instance, Li et al [18] presented the stress wave velocity model to diagnosis the internal defects in urban trees. According to Guntekin et al [19], the imaging results and detection precision still need to be improved, although many stress wave detection devices are capable of generating twodimensional or three-dimensional tomographic images of wood cross sections.…”

Section: Introductionmentioning

confidence: 99%

Detection and Prediction of Internal Damage in the Ancient Timber Structure Based on Optimal Combined Model

Wang

Qian

et al. 2019

Advances in Civil Engineering

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It is currently known that using stress wave and drilling resistance to detect the internal damage in the ancient timber structure is not a highly precise process. To improve the detection precision of this process, a simulation test was used to detect the internal damage of poplar and elm in ancient buildings. In this empirical study, we compared the detection precision of these two detection methods. Based on the idea of variable weight, we introduced three combined forecasting models based on the IOWA operator, IOWGA operator, and IOWHA operator to predict the internal damage in the ancient timber structure. The results show that the combined forecasting model based on the IOWA operator is more effective in predicting compared to a single detection method and other combined forecasting models. To be more specific, the results show that the detection precision of the combined model is increased by 25.8% and 4.7%, respectively, compared to the precision of the stress wave and drilling resistance tests. The error indicators of the combined forecasting model based on the IOWA operator are better than those of the other combined forecasting models. In addition, the analysis results based upon cross-validation theory show the combined forecasting model based on the IOWA operator has the best applicability, which provides a new practical method for evaluating internal damage of timber components in ancient buildings.

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Section: Introductionmentioning

confidence: 99%

Detection and Prediction of Internal Damage in the Ancient Timber Structure Based on Optimal Combined Model

Wang

Qian

et al. 2019

Advances in Civil Engineering

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“…Despite these minor discrepancies, the 3D results generally agree with the 2D results, showing the most severe internal decay on the 90 cm cross section above ground, and medium quality of wood on the 120 cm cross section, with similar sizes, shapes and locations. Since Arbotom is a popular tool in the industry and has been used in numerous studies on non-destructive testing (Yang and Luo, 2011;Li et al, 2016), it can be concluded that the proposed approach achieves satisfactory results in modelling the exterior and the internal wood health of tree trunks. The generation of the 3D model of wood decay took around 30 min on a standard PC (i7, 6700K, 16GB RAM), with kriging being the most computationally complex part of the process.…”

Section: Resultsmentioning

confidence: 98%

“…The sound wave velocity can be impacted by the number of annual rings, angles between the acoustic sensors and the deviation of the cross section from the horizontal plane. It has been found that while reconstructing the wood quality of a tree trunk in 3D, the behaviour of the sound waves is significantly different on the longitudinal-radial plane (where "longitudinal" is the vertical height direction) (Li et al, 2016). Therefore, care needs to be taken when computing the velocities of sound waves in 3D, as those crossing vertical heights are more complex than those on a horizontal cross section of the tree trunk.…”

Section: Aims and Objectivesmentioning

confidence: 99%

“…Each mid-point is assigned the weighted average velocity of the corresponding nearly intersecting lines. Horizontal lines connecting sensors at the same height level receive a larger weight than those connecting sensors at different levels, because the velocities obtained for sensors at different height levels are considered less reliable due to the anisotropy of wood (Li et al, 2016). To ensure that the computed average velocity is reliable, the length of each shortest line segment is computed and those line segments whose lengths exceed an empirical threshold are eliminated from the process.…”

Section: Computation Of Sonic Velocitiesmentioning

confidence: 99%

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3D reconstruction of internal wood decay using photogrammetry and sonic tomography

Zhang

Khoshelham

2020

The Photogrammetric Record

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Knowledge of deteriorations within tree trunks is critical for arborists to conduct individual tree health assessments. Sonic tree tomography, a non‐destructive technique using sound waves, has been widely used to estimate the size and shape of internal decay based on sound wave velocity variations. However, it has commonly been applied to 2D horizontal or vertical cross sections and its accuracy is questionable due to the poor approximation of the shape of the cross section. This paper proposes an integration of close‐range photogrammetry and sonic tomography to enable accurate reconstruction of the exterior and interior of the tree trunk in 3D. The internal wood quality is represented by the spatially interpolated sound wave velocities, using the time of flight of the sound waves and the coordinates of the acoustic sensors obtained from the photogrammetric model. Experimental results show that the proposed approach provides a realistic 3D visualisation of the size, shape and location of the internal deteriorations.

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“…The success of using the single‐path stress wave timing method to detect internal decay in live trees has been reported in many papers (McCracken, ; Mattheck and Bethge, ; Yamamoto et al., ). However, this method is limited in its ability to detect moderate to severe internal defects in trees, as it is not sufficiently sensitive to detect internal decays at an early stage or of small size (Li et al., ).…”

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confidence: 99%

Reliability of acoustic tomography and ground‐penetrating radar for tree decay detection

Jiao

2018

Appl Plant Sci

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Premise of the StudyVarious nondestructive testing technologies have been used for detecting and visualizing internal defects in urban trees. The results obtained by using different nondestructive testing tools can be interpreted in different ways, which may result in inaccurate assessment of the true condition of the inspected trees. The main objective of this study was to evaluate the reliability of acoustic tomography and ground‐penetrating radar (GPR) technology for detecting internal decay in a number of different tree species.MethodsOne hundred and forty‐seven individual trees of 33 species were inspected at a historic park in Yangzhou, Jiangsu Province, China, using a combination of visual inspection, acoustic tomography, GPR scanning, and resistance micro‐drilling methods. Special image processing procedures were developed to analyze the acoustic and radar images and to estimate the proportion of compromised wood.ResultsThe acoustic tomography tests revealed 10 defective trees with acoustic shadows suggesting compromised wood in more than 10% of the cross‐section area. The actual nature of these defects on living trees can be ascertained by conducting resistance micro‐drilling at selected paths. The Tree Radar Unit (TRU) System produced 85% false positive predictions and thus was not successful in visualizing the true physical conditions of the trees.ConclusionsAcoustic tomography can successfully detect trees with internal decay and cavities. A combination of visual inspection, acoustic tomography, and resistance micro‐drilling is an effective approach to detect, measure, and visualize internal defects on a diversity of tree species. The image processing procedures we developed make possible the quantitative analysis of compromised wood and could improve the science‐based tree risk assessment process. In contrast, the TRU System presented challenges in field applications, particularly on trees with small diameters and irregularly shaped trunks. The images obtained in this study using the TRU system were largely inaccurate and not reliable for tree inspection.

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Stress wave velocity patterns in the longitudinal–radial plane of trees for defect diagnosis

Cited by 15 publications

References 13 publications

Detection and Prediction of Internal Damage in the Ancient Timber Structure Based on Optimal Combined Model

Detection and Prediction of Internal Damage in the Ancient Timber Structure Based on Optimal Combined Model

3D reconstruction of internal wood decay using photogrammetry and sonic tomography

Reliability of acoustic tomography and ground‐penetrating radar for tree decay detection

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