Authorship：Last author   Language：English   Publishing type：Part of collection (book)   Publisher：Springer Nature Switzerland  

DOI： 10.1007/978-3-031-33465-8_75

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Part of collection (book)   Publisher：Springer Nature Switzerland  

DOI： 10.1007/978-3-031-33465-8_59

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Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：{MDPI} {AG}  

<jats:p>This research investigates the influence of the pre-existing defects within concrete taken from the in-service irrigation structure on the strain distribution. The X-ray Computed Tomography (CT) technique is employed to investigate the internal concrete matrix and evaluate the defect distribution in it. The cracking system in a concrete matrix is detected as a damage type caused by the severe environment, and it is varied by the different degrees in all samples. The geometric properties of defects and their spatial location are obtained by image processing of CT images. The compression test with Acoustic Emission (AE) and Digital Image Correlation (DIC) measurements is conducted to analyze the fracture processes and acquire the damage spatial information. The AE signal descriptors are effective parameters for real-time detection and potential local damage monitoring. Moreover, the analysis of the DICM strain and displacement fields reveals the most potential fracture zones. The AE source location analysis indicated a connection between pre-existing defects and strain localization. The AE events and strain are high in the defect areas. Additionally, the amplitude and frequency of the AE events correlated with the location of the defects indicating that the structure weakness at that point leads to concentrated deformation development.</jats:p>

DOI： 10.3390/app13116727

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Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier {BV}  

DOI： 10.1016/j.cscm.2023.e02088

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Authorship：Last author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.11408/jsidre.91.I_57

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Authorship：Last author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2472/jsms.72.188

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Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media {LLC}  

DOI： 10.1007/s10333-022-00910-w

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Other Link： https://link.springer.com/article/10.1007/s10333-022-00910-w/fulltext.html

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Frontiers Media {SA}  

<jats:p>Steel sheet pile materials are primarily used for canal structure construction for irrigation and drainage of agricultural fields in Japan. Recently, accelerated corrosion of steel materials and buckling phenomena in pitting corrosion parts have been detected in in-service steel sheet pile canals. In this study, we focus on the buckling phenomenon of in-service steel sheet pile canals, which is detected by non-contact monitoring using digital image analysis. The buckling phenomenon index is evaluated as the inclination angle of the steel sheet pile due to deformation. As a digital image analysis, Hough transform is applied, which is a figure detection method in digital images, to detect a straight line that describes the distance and angle parameters. The angle parameter corresponds to the inclination angle index of in-service steel sheet pile with a buckling phenomenon. As a result, the maximum difference between the analyzed angles by Hough transform and the measured angles is evaluated as 0.9° after the image rotation correction. The relation of the analyzed angles by Hough transform and the measured angles of the buckling phenomenon is correlated. Therefore, the degradation of steel sheet pile canals is quantitatively evaluated by using digital image analysis with unmanned aerial vehicle monitoring. This study’s significance is non-contact and simple measurement by using a digital image which can reduce a working time and perform quick diagnosis in extensive areas.</jats:p>

DOI： 10.3389/fbuil.2022.948232

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Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Frontiers Media {SA}  

<jats:p>The durability of concrete irrigation infrastructures decreases easily due to environmental effects, such as the freeze-thawed process. The degree of damage in concrete is, in most cases, evaluated by an unconfined compression test or ultrasonic test. The limiting states of structures are the result of a gradual accumulation of microdefects during the in-service period, which leads to the initiation and development of macroscopic cracks, loss of performance, and Failure. Therefore, to maintain such structures, it is necessary to properly determine the degree of damage by non-destructive testing. For effective maintenance and management of in-service structures, it is necessary to evaluate not only such mechanical properties as strength but also the degree of damage. Quantitative damage evaluation of concrete is proposed by applying the X-ray CT method and related non-destructive inspection, which is based on estimating cracking damage effects. In this study, the damage evaluation of concrete-core samples is investigated by X-ray CT parameters and the non-destructive parameters. The samples tested were taken from the damaged concrete headwork in Niigata, Japan, about 50 years after its construction. The geometric properties of the concrete matrix were calculated by the analysis of X-ray CT images. After X-ray CT measurement, an ultrasonic test and a resonant frequency test were performed. The dynamic modulus of elasticity was calculated by using ultrasonic pulse velocity and resonant frequency. As a result, based on the relationship between the geometric properties of the concrete matrix and the non-destructive parameters, the accumulation of damage in the samples tested was correlated with the ratio of the total area of cracks to the observation area. In damaged conditions, the high value of its ratio is demonstrated under low ultrasonic pulse velocity. These results suggest that the most sensitive components in a concrete body to the degree of damage are cracks in mortar and the ratio of the total area of cracks to the observation area. These values are affected by the internal actual cracks. Thus, the damage of concrete could be quantitatively evaluated by the geometric properties of the concrete matrix and its physical properties.</jats:p>

DOI： 10.3389/fbuil.2022.947759

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.11408/jsidre.90.I_239

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Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.11408/jsidre.90.IV_13

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Authorship：Last author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.11408/jsidre.89.I_1

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Authorship：Last author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.11408/jsidre.88.I_59

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier {BV}  

DOI： 10.1016/j.conbuildmat.2020.118343

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.11408/jsidre.88.I_67

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.11408/jsidre.88.I_145

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Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media {LLC}  

DOI： 10.1007/s10333-019-00752-z

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s10333-019-00726-1

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Authorship：Last author,　Corresponding author   Language：Japanese  

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.11408/jsidre.84.I_317

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media {LLC}  

DOI： 10.1617/s11527-015-0672-9

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Part of collection (book)   Publisher：Springer Netherlands  

For detailed inspections of concrete structures, non-destructive tests (NDT) are often conducted and then mechanical properties are compared with detected NDT parameters. In this chapter, damage evaluation of concrete by AE and X-ray computerized tomography (CT) tests are presented. The concrete damage is visualized by X-ray CT. Since nucleation of AE events in damaged concrete is affected by crack distribution, the damage parameter estimated is correlated with the dynamic modulus of elasticity Ed which is calculated from P-wave velocity. The results confirm that the damage of concrete could be estimated by applying AE measurement, damage parameter in damage mechanics, CT images and modulus Ed. It is also shown that the static modulus E0 is closely correlated with the dynamic modulus Ed. Based on a relation between AE rate and the damage parameter, the damage of concrete is quantitatively estimated.

DOI： 10.1007/978-94-017-7606-6_9

Scopus

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Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

The Great East-Japan Earthquake hit Tohoku area in Japan on March 11, 2011. A large number of concrete structures were damaged due to the 9.0 magnitude earthquake of the Richter-scale. Prior to reconstruction and retrofit of these structures, damage evaluation of in situ concrete structures is now in urgent demand. In this concern, quantitative damage estimation of concrete is proposed to be performed, applying acoustic emission (AE) measurement in a uniaxial compression test of core samples. Generating behavior of AE events in the core test is quantitatively analyzed, based on the rate process theory, because notable discrepancy of AE activity is observed between damaged concrete and undamaged concrete. The damage is quantitatively defined by a scalar damage parameter in damage mechanics. Correlating AE rate with the damage parameter, quantitative estimation of damage is proposed in terms of the relative modulus of elasticity (E-0/E*). Concrete core samples were taken from reinforced concrete columns of an existing canal in the both periods of pre and post the earthquake. Prior to the compression test, distribution of microcracks in a concrete-core sample was inspected by helical X-ray computed tomography (CT), which scans at 1-mm intervals. The results suggest that the damage of concrete could be quantitatively estimated from damage parameter E-0/E* without knowing the original state of the concrete at construction. The static moduli E-0/E* and dynamic moduli E-d/E* is closely correlated. A relation between AE rate and the damage parameters is correlated, and thus the earthquake damage of concrete is quantitatively estimated using AE. (C) 2014 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.conbuildmat.2014.05.016

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Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

In recent years, the accelerated corrosion of steel sheet pile in an agricultural canal has been problems. In this research, evaluation of bending characteristics is conducted in corroded steel sheet pile with concrete coating by using AE and DICM. The test specimens are made of three-layer composite which is composed of steel sheet pile, concrete and precast panel. Thus, the deformation behavior of testing samples could be evaluated by AE and DICM parameters. A relation between torsional behavior due to the concavo-convex shape of steel sheet pile and bending behavior of composite was correlated.

DOI： 10.2208/jscejam.70.I_81

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Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

For effective maintenance and management of pipeline system, it is necessary to evaluate not only the damage of pipe materials but also the detection of pressure waves such as water hammer. In this study, non-destructive inspections of pressure waves are proposed by applying acoustic emission (AE) and image analysis. Thus, pressure waves were detected in the model pipeline system, based on control of valve closing time (0.40-10.48s). The AE behavior of pressure waves were dependent on the degree of maximum pressure scale and could be evaluated applying AE parameter analysis. Using digital image correlation method (DICM), a relationship between maximum pressure level and displacement is correlated. By monitoring the pressure waves in model pipeline based on these results, the generated pressure waves was successfully detected by non-destructive inspection methods.

DOI： 10.2208/jscejsp.70.I_143

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Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publisher：The Japanese Society of Irrigation, Drainage and Rural Engineering  

For effective maintenance and management of pipeline system, it is necessary to evaluate not only the damage of pipe materials but also the detection of pressure waves such as water hammer. In this study, non-destructive inspections of pressure waves are proposed by applying acoustic emission (AE) and image analysis. Thus, pressure waves were detected in the model pipeline system, based on control of valve closing time (0.40-10.48s). The AE behavior of pressure waves were dependent on the degree of maximum pressure scale and could be evaluated applying AE parameter analysis. Using digital image correlation method (DICM), a relationship between maximum pressure level and displacement is correlated. By monitoring the pressure waves in model pipeline based on these results, the generated pressure waves was successfully detected by non-destructive inspection methods.

DOI： 10.11408/jsidre.81.479

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Authorship：Lead author,　Corresponding author  

DOI： 10.2208/jscejsp.69.I_49

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

As a detailed inspection of a concrete structure in service, core samples are usually drilled out and then mechanical properties are measured. In this study, damage estimation of concrete structures from core samples is developed, applying acoustic emission (AE) and X-ray computed tomography method. Concrete-core samples were taken from reinforced concrete of an existing canal. These samples are strongly damaged by freezing and thawing process. Crack distributions of concrete-core samples were inspected with helical Computerized Tomography (CT) scans, which were undertaken at 1-mm intervals. After helical CT scan, damage of testing samples was evaluated, based on fracturing behavior under compression and AE activity. AE behavior is dependent on the degree of damage, and could be approximated by applying the AE rate-process analysis and damage mechanics. AE generation behavior is associated with crack volume due to damage accumulation in concrete. The damage is quantitatively defined by a scalar damage parameter in damage mechanics. Applying the scalar damage parameter, quantitative estimation of damage is proposed in terms of relative modulus of elasticity which is named "durability index". By calculating the durability index, the initial damage of samples is estimated from AE database. The decrease in mechanical properties could be evaluated by comparing the average CT number with the durability index, both of which are affected by internal cracks generated. Thus, the damage of concrete structures is quantitatively evaluated by AE and X-ray computed tomography method. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.conbuildmat.2010.05.005

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Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1617/s11527-010-9640-6

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Other Link： http://link.springer.com/article/10.1617/s11527-010-9640-6/fulltext.html

Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1617/s11527-010-9639-z

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Other Link： http://link.springer.com/article/10.1617/s11527-010-9639-z/fulltext.html

Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1617/s11527-010-9638-0

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Other Link： http://link.springer.com/article/10.1617/s11527-010-9638-0/fulltext.html

Authorship：Last author   Language：Japanese  

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.11532/structcivil.56A.665

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Cement Association  

As a detailed inspection of a concrete structure in service, core samples are usually drilled out and then physical properties are measured. In this study, damage estimation of concrete-core samples from structural concrete is developed, applying elastic wave method and X-ray computed tomography method. Concrete-core samples taken from reinforced concrete of an existing canal were tested. These samples are strongly influenced by freezing and thawing process. The crack distributions of concrete-core samples were inspected with helical CT scans, which were undertaken at one-millimeter intervals. After helical CT scan, damage of freeze-thawed samples was evaluated, based on elastic wave parameter. It is confirmed that the development of actual cracks in core samples were decreased in CT number and elastic wave velocity. In low CT number's portion, the elastic wave parameter is decreasing compared to non-cracked portion. These results suggest that the decrease in physical properties could be evaluated by comparing average CT number with elastic wave properties in core test. These values are affected by the internal actual cracks. Thus, the damage of freeze-thawed concrete in service structures could be quantitatively evaluated by elastic wave method and X-ray computed tomography method.

DOI： 10.14250/cement.63.204

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：日本コンクリート工学協会  

コンクリート構造物の損傷は,局所的に進行し,構造体の耐力を低下させる。本研究では,損傷が進行したコンクリート水路構造物の補修効果を熱特性の空間的分布構造の観点から評価した。評価手法には,推計統計学指標に加えて,空間データの評価手法の一つである地質統計学のセミバリオグラムを用いた。検討の結果,表面被覆工を施したコンクリート壁面の熱特性は,明確なセミバリアンスとラグの関係が得られ,コンクリート構造物の補修効果の検証へのセミバリオグラムの有効性が明らかになった。損傷部の検出には,セミバリアンスと統計指標である尖度と歪度の関係が有効であることが示唆された。

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Other Link： http://dl.ndl.go.jp/info:ndljp/pid/10641491

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

It is widely reported and realized that durability of concrete decreases due to such effects, as salt and chemical attack, freezing and thawing, and carbonation and fatigue. In existing structures mechanical damage of concrete has been practically estimated from the strength by a compression test and a rebound hammer test. For effective maintenance of concrete structures, it is necessary to evaluate quantitatively not only the strength of concrete but also the degree of damage. Quantitative damage evaluation of structural concrete is proposed by applying acoustic emission (AE) technique and damage mechanics. Consequently, damage evaluation is conducted on concrete cores of an existing structure.
Core-samples were collected from an arch fragment of a reinforced concrete road bridge that had been in service for 87 years. Compressive strengths and Young's moduli were measured during the compression test along with AE measurement. Dynamic Young's moduli were also calculated from the longitudinal wave velocity. Thus the relative damages are quantitatively evaluated from static and dynamic Young's moduli and compared with results of AE rate-process analysis.

DOI： 10.1617/s11527-006-9133-9

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

In recent years, deterioration of concrete structures has been widespread and become a social problem. Because the durability of concrete structures decreases easily due to such external effects, as carbonation and freezing-thawing process, it has been important to evaluate not only the strength but also the damage of concrete. Thus, damage evaluation of structural concrete is developed, applying acoustic emission (AE) method. Damaged concrete samples are examined, based on fracturing behavior under unconfined compression. AE behavior of the concrete under compression is dependent on the degree of damage, and could be analyzed by the rate process analysis. Using Loland's model, a relationship between stress and strain is modeled, and a relation between the AE rate and the damage parameter is correlated. By calculating Young's modulus of the intact concrete from the database of this correlation, the relative damage of the concrete in an actual structure is successfully estimated. (C) 2003 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.conbuildmat.2003.10.009

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Total pages：418p   Language：Japanese

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Authorship：Corresponding author   Language：Japanese  

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publisher：The Japanese Society of Irrigation Drainage and Rural Engineering  

DOI： 10.11408/jjsidre.82.1_7

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publisher：日本下水道協会  

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)   Publisher：環境新聞社  

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper, summary (international conference)  

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Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese  

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Event date： 2021.10

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2021.10

Language：English  

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Presentation type：Poster presentation  

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