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RISS 인기검색어
- 검색키워드
- 저자 : Chun-Xu Qu (검색결과 3 건)
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Spurious mode distinguish by eigensystem realization algorithm with improved stabilization diagram
Chun-Xu Qu,Ting-Hua Yi,Xiao-Mei Yang,Hong-Nan Li 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.63 No.6
Modal parameter identification plays a key role in the structural health monitoring (SHM) for civil engineering. Eigensystem realization algorithm (ERA) is one of the most popular identification methods. However, the complex environment around civil structures can introduce the noises into the measurement from SHM system. The spurious modes would be generated due to the noises during ERA process, which are usually ignored and be recognized as physical modes. This paper proposes an improved stabilization diagram method in ERA to distinguish the spurious modes. First, it is proved that the ERA can be performed by any two Hankel matrices with one time step shift. The effect of noises on the eigenvalues of structure is illustrated when the choice of two Hankel matrices with one time step shift is different. Then, a moving data diagram is proposed to combine the traditional stabilization diagram to form the improved stabilization diagram method. The moving data diagram shows the mode variation along the different choice of Hankel matrices, which indicates whether the mode is spurious or not. The traditional stabilization diagram helps to determine the concerned truncated order before moving data diagram is implemented. Finally, the proposed method is proved through a numerical example. The results show that the proposed method can distinguish the spurious modes.
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Jian Zhang,Chun-Xu Qu,Ting-Hua Yi,Hong-Nan Li 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.27 No.1
Concrete bridge decks may suffer local damage such as delamination, cracking, reinforcement corrosion and spalling during service. Visual inspection and nondestructive evaluation (NDE) technologies are extensively used for monitoring damage in bridge decks. This paper presents a damage detection method for decks of concrete girder bridges using the frequency obtained from an actively excited vehicle. First, the solution for the frequency of the deck with a concentrated mass is derived with Rayleigh's method, where the bridge deck is regarded as a slab supported on four sides, and the test vehicle is simplified as a concentrated mass. The validity of the proposed method that uses the frequency change to detect the local damage is verified. Then, the damage detection procedure for bridge decks is proposed, and the numerical analysis is performed on a typical concrete girder bridge to prove the validity of the method. Finally, the damage detection experiment for the plywood plate verifies the effectiveness of the proposed method. The results of this study provide an effective method for detecting damage in the decks of concrete girder bridges, which is time-saving and easier to implement.
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Association between Dietary Behavior and Esophageal Squamous Cell Carcinoma in Yanting
Zhao, Lin,Liu, Chun-Ling,Song, Qing-Kun,Deng, Ying-Mei,Qu, Chen-Xu,Li, Jun Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.20
Background: Yanting is one of high risk areas for esophageal cancer and the screening program was therefore initiated there. This study was aimed to investigate the dietary behaviors on the risk of esophageal squamous cell carcinoma (ESCC), among the individuals with normal and abnormal esophagus mucosa. Materials and Methods: A frequency matched case-controls study was proposed to estimate the different distribution of dietary behavior between individuals of control, esophagitis and cancer groups. Cancer cases were selected from hospitals. Esophagitis cases and controls were selected from screening population for ESCC. Health workers collected data for 1 year prior to interview, in terms of length of finishing a meal, temperature of eaten food and interval between water boiling and drinking. Chi-square, Kruskal-Wallis tests and unconditional logistic regression model were used to estimate differences and associations between groups. Results: Compared with controls, length of finishing a meal ${\geq}15mins$ was related to a reduced OR for cancer (OR=0.46, 95%CI, 0.22-0.97) and even compared with cases of esophagitis, the OR of cancer was reduced to 0.30 (95%CI, 0.13-0.72). The OR for often eating food at a high temperature was 2.48 (95%CI 1.06, 5.82) for ESCC as compared with controls. Interval between water boiling and drinking of ${\geq}10mins$ was associated with lower risk of cancer: the OR was 0.18 compared with controls and 0.49 with esophagitis cases (p<0.05). Conclusions: Length of eating food ${\geq}15mins$ and interval between water boiling and drinking ${\geq}10mins$ are potentially related to reduced risk of esophageal SCC, compared with individuals with normal and abnormal esophageal mucosa. Recommendations to Yanting residents to change their dietary behaviors should be made in order to reduce cancer risk.
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