Browsing by Author "Hsu, Ting-Yu"

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Continuous structural health monitoring of the Sayano-Shushenskaya Dam using off-site seismic station data accounting for environmental effects
(2020-01-01)
Hsu, Ting-Yu
;
Valentino, Arygianni
;
Liseikin, Aleksei
;
Krechetov, Dmitry
;
Chen, Chun-Chung
Damage to a huge dam can cause great loss of human life and property, but disasters and their consequences can be minimized by implementing effective dam safety monitoring strategies. However, establishing a permanent monitoring system on a huge darn is costly. Additionally, for reasons of national security, many darns and information about them may not be able to be accessed by researchers. Accordingly, continuously monitoring the structural health of a dam by measurement may be difficult. This study presents a way to continuously monitor the health of a dam using vibration signals that are measured not on the dam but close to it. The Sayano-Shushenskaya Dam in Russia is used to demonstrate the idea. Intensive ambient vibration measurements were firstly made once to determine the natural frequencies of the dam. Then the natural frequencies of the dam under varying environmental effects are obtained from the spectra of the seismic records obtained at Cheryomushki seismic station, which is located 4.4 km northeast of the darn. To account for the effects of varying environmental conditions on the natural frequencies, an autoencoder in the form of an unsupervised learning neural network, was employed. The autoencoder was trained using the natural frequencies without using any environmental factors to learn the intrinsic behavior of the darn under varying environmental conditions. The errors between input data to the trained autoencoder and the regenerated data from the autoencoder can be used to determine whether the dam is under normal conditions. A finite element model of the dam was constructed to simulate changes of natural frequencies due to cracks in the dam structure. The results demonstrate that the proposed method can feasibly monitor the structural health of the dam.
Porous Organic TFTs for the Applications on Real-Time and Sensitive Gas Sensors
(2011-08-01)
Zan, Hsiao-Wen
;
Dai, Ming-Zhi
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Hsu, Ting-Yu
;
Lin, Hung-Cheng
;
Meng, Hsin-Fei
A pentacene-based organic thin-film transistor (OTFT) with a porous active layer is demonstrated for the first time. The porous OTFT exhibits a fast, sensitive, and reversible response to ammonia gas with a detection limit as 500 ppb, whereas the OTFT without porous structure has a slow response and a poor recovery behavior. The sensing mechanism dominated by the dissociation of hydroxyl groups of the polymer dielectric layer is raised and discussed. The proposed device is the first OTFT-based ammonia sensor with reversible response and high sensitivity in low parts-per-million range. It is promising for the development of a diagnostic breath analysis system.
Stable Encapsulated Organic TFT With a Spin-Coated Poly(4-Vinylphenol-Co-Methyl Methacrylate) Dielectric
(2011-08-01)
Zan, Hsiao-Wen
;
Hsu, Ting-Yu
;
光電工程學系
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Department of Photonics
The influences of encapsulation on the hysteresis and the gate-bias-stress effects (both positive and negative gate bias stresses) of pentacene organic thin-film transistors (OTFTs) with poly(4-vinylphenol) and poly(4-vinylphenol-co-methyl methacrylate) (PVP-PMMA) gate dielectrics are investigated. The encapsulation and the use of less polar gate dielectrics like PVP-PMMA copolymers are both important to suppress moisture adsorption and to obtain a stable pentacene OTFT. Compared to the air-stable OTFT with a fluoropolymer dielectric, the stable encapsulated OTFT with a PVP-PMMA dielectric is a low-cost promising candidate for mass production consideration.