Browsing by Author "Chen, Chun-Chung"

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Compressive Column Load Identification in Steel Space Frames Using Second-Order Deflection-Based Methods
(2018-07-01)
Bonopera, Marco
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Chang, Kuo-Chun
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Chen, Chun-Chung
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Lin, Tzu-Kang
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Tullini, Nerio
This paper presents a comparison of two static nondestructive methods used to assess compressive loads in columns of steel space frames. The first method requires knowledge of the flexural rigidity of the column under investigation, whereas the second method requires knowledge of the column's buckling load. In each method, short-term displacements are measured at given cross-sections along the member under examination, which is subjected to an additional transverse load. The two methods were verified in this study through experimental and numerical tests on a column of a small-scale space frame prototype with generic connections and end conditions. Estimations of compressive forces were generally reliable when second-order effects were accurately considered. In conclusion, the two methods can be successfully used to test steel space frames in a laboratory or under real conditions.
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
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Valentino, Arygianni
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Liseikin, Aleksei
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Krechetov, Dmitry
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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.
Efficiency Enhancement and Sensitive Broadband 1Hz similar to 1kHz of Power Generator by Recycling Vibration Energy on Automobile
(2012)
Wei, Mao-Qugn
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Ko, Fu-Hsiang
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Sun, Tai-Ping
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Chen, Hsuen-Li
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Lin, Yung-Bin
Based on novel design of moveable magnet between two mutually inimical magnetic forces without strict fabrication, for the first time, we demonstrate successfully a producible power generator with significant efficiency enhancement at broadband frequency range of 1 Hz similar to 1 kHz, 3D-colis stack-ability for output voltage improvement, and recycling vibration energy on automobile simultaneously. Even though the vibration frequency is as low as 1 Hz, two orders-of-magnitude improvements in normalized power (the ratio of power to product of external force and coil turns) provided from previous reports can be obtained. Further, comparing our device with maturely accelerometer chip (MMA7361) indicates that proposed strategies benefit harvesting vibration energy on driving automobile indeed. This vibrated power generator in-turn provides high potential for applications, such as human motion (1 Hz similar to 2 Hz), sporting (5 Hz similar to 10 Hz), and automotive (10 Hz similar to 1 kHz) etc..
Local hemostatic matrix for endoscope-assisted removal of intracerebral hemorrhage is safe and effective
(2018-01-01)
Luh, Hui-Tzung
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Huang, Abel Po-Hao
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Yang, Shih-Hung
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Chen, Chien-Ming
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Cho, Der-Yang
Background/Purpose: Minimally invasive endoscope-assisted (MIE) evacuation of spontaneous intracerebral hemorrhage (ICH) is simple and effective, but the limited working space may hinder meticulous hemostasis and might lead to rebleeding. Management of intraoperative hemorrhage is therefore a critical issue of this study. This study presents experience in the treatment of patients with various types of ICH by MIE evacuation followed by direct local injection of FloSeal Hemostatic Matrix (Baxter Healthcare Corp, Fremont, CA, USA) for hemostasis. Methods: The retrospective nonrandomized clinical and radiology-based analysis enrolled 42 patients treated with MIE evacuation of ICH followed by direct local injection of FloSeal Hemostatic Matrix. Rebleeding, morbidity, and mortality were the primary endpoints. The percentage of hematoma evacuated was calculated from the pre-and postoperative brain computed tomography (CT) scans. Extended Glasgow Outcome Scale (GOSE) was evaluated at 6 months postoperatively. Results: Forty-two ICH patients were included in this study, among these, 23 patients were putaminal hemorrhage, 16 were thalamic ICH, and the other three were subcortical type. Surgery-related mortality was 2.4%. The average percentage of hematoma evacuated was 80.8%, and the rebleeding rate was 4.8%. The mean operative time was 102.7 minutes and the average blood loss was 84.9 mL. The mean postoperative GOSE score was 4.55 at 6-months' follow-up. Conclusion: This study shows that local application of FloSeal Hemostatic Matrix is safe and effective for hemostasis during MIE evacuation of ICH. In our experience, this shortens the operation time, especially in cases with intraoperative bleeding. A large, prospective, randomized trial is needed to confirm the findings. Copyright (C) 2017, Formosan Medical Association. Published by Elsevier Taiwan LLC.