Browsing by Author "Hung, Shih Lin"

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Combining subspace approach and short time Fourier analysis for locating structural damage storeys
(2015-08-01)
Huang, Chiung Shiann
;
Chen, Liane Jye
;
Hung, Shih Lin
;
Ding, Chun Ting
;
Su, Wei Chih
This study proposes a novel and efficient approach for locating the floors of a building whose stiffnesses change after being subject to a strong earthquake. The floors that may be damaged are determined by comparing the unitary stiffness matrix in different stages in the life cycle of a building. To evaluate the coefficient matrices of a state-space model, the proposed procedure applies a subspace approach in conjunction with the short time Fourier analysis. The dynamic characteristics of a structure are determined from the coefficient matrices. Next, the unitary stiffness matrix is constructed by identifying natural frequencies and mode shapes. The effectiveness of the proposed procedure is verified using the measured earthquake acceleration responses of a three-storey structure that sustains damage on one or two floors and an eight-storey steel frame under a 200 Gal and a 1200 Gal earthquake, such as the Chi-chi earthquake that shook Taiwan on September 1999. The proposed scheme is compared to mode shape based approaches in identifying damaged floors, and is demonstrated to be superior to both MAC (Modal Assurance Criterion) and COMAC (Coordinate Modal Assurance Criterion).
Developing an energy-efficient and low-delay wake-up wireless sensor network-based structural health monitoring system using on-site earthquake early warning system and wake-on radio
(2019-02-01)
Hung, Shih Lin
;
Ding, Jiun Ting
;
Lu, Yung Chi
;
土木工程學系
;
資訊工程學系
The stability and durability of the energy supply for sensing nodes in a wireless sensors network (WSN) is an important research issue and requiring improvement for WSNs in structural health monitoring (SHM) systems. Having control sensors periodically enter a low-power mode or sleep state is commonly used to reduce energy consumption. If a node receives a sampling command but the node remains in listening-time cycle, the sampling process will be delayed. Hence, the capabilities of radio triggering can improve stability and durability when integrated with an external low-power circuit attached to sensing nodes. Transmitting a wake-up command when specific start-up conditions are met to quickly awaken sensing nodes to work wirelessly is also an effective approach. The objective of this work is to integrate sensing field-type p-wave technology to construct an intelligent energy economical WSN with sentry nodes embedded with an earthquake early warning (EEW) system. Sentry nodes are integrated with WSN gateways and employed to link and synchronize all sensing nodes in advance through seismic prediction and radio-triggering technology. In this mode, the average power consumed was measured at 350A. A sensor will be more effective in measuring structural responses after an earthquake by increasing available sleep time.