Performance-based optimization of LQR for active mass damper using symbiotic organisms search

Pei-Ching Chen,Bryan J. Sugiarto,Kai-Yi Chien 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.27 No.4

The linear-quadratic regulator (LQR) has been applied to structural vibration control for decades; however, selection of the weighting matrices of an LQR mostly depends on trial and error. In this study, a novel metaheuristic optimization method named as symbiotic organisms search (SOS) algorithm is applied to tuning LQR weighting matrices for active mass damper (AMD) control systems. A 10-story shear building with an active mass damper installed at the top is adopted as a benchmark for numerical simulation in order to realize the optimization performance considering three objective functions for mitigation of structural acceleration. Two common optimization methods including genetic algorithm (GA), and particle swarm optimization (PSO) are also applied to this benchmark for comparison purposes. Numerical simulation results indicate that SOS is superior to GA and PSO on searching the minimized solution of the three objective functions. Meanwhile, minimizing the square root of the sum of the squares of peak modal acceleration achieves the best control performance of structural acceleration among the three objective functions. In addition, force saturation is proposed and applied in the optimization process such that the control force level is close to the force capacity of AMD under specified earthquake intensity. Furthermore, the control performance of the optimized LQR is compared with that of the LQR designed by applying three common weighting selection methods when the 10-story building is subjected to various earthquake excitations. Simulation results demonstrate that the optimized LQR significantly outperforms the three LQRs on structural acceleration responses as expected and reduces story drift slightly better than the three LQRs. Finally, the performance-based optimized LQR is experimentally validated by conducting shake table testing in the laboratory. The experimental results and structural control performance are discussed and summarized thoroughly.

Robust stability analysis of real-time hybrid simulation considering system uncertainty and delay compensation

Pei-Ching Chen,Po-Chang Chen 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.25 No.6

Real-time hybrid simulation (RTHS) which combines physical experiment with numerical simulation is an advanced method to investigate dynamic responses of structures subjected to earthquake excitation. The desired displacement computed from the numerical substructure is applied to the experimental substructure by a servo-hydraulic actuator in real time. However, the magnitude decay and phase delay resulted from the dynamics of the servo-hydraulic system affect the accuracy and stability of a RTHS. In this study, a robust stability analysis procedure for a general single-degree-of-freedom structure is proposed which considers the uncertainty of servo-hydraulic system dynamics. For discussion purposes, the experimental substructure is a portion of the entire structure in terms of a ratio of stiffness, mass, and damping, respectively. The dynamics of the servo-hydraulic system is represented by a multiplicative uncertainty model which is based on a nominal system and a weight function. The nominal system can be obtained by conducting system identification prior to the RTHS. A first-order weight function formulation is proposed which needs to cover the worst possible uncertainty envelope over the frequency range of interest. Then, the Nyquist plot of the perturbed system is adopted to determine the robust stability margin of the RTHS. In addition, three common delay compensation methods are applied to the RTHS loop to investigate the effect of delay compensation on the robust stability. Numerical simulation and experimental validation results indicate that the proposed procedure is able to obtain a robust stability margin in terms of mass, damping, and stiffness ratio which provides a simple and conservative approach to assess the stability of a RTHS before it is conducted.

Numerical modelling of a shear-thickening fluid damper using optimal transit parameters

Pei-Ching Chen,Chung-Han Yu,Yohanes K. Surjanto,Shen-Kai Peng,Kuo-Chun Chang 국제구조공학회 2022 Smart Structures and Systems, An International Jou Vol.30 No.5

The viscosity of a shear-thickening fluid damper (STFD) can increase dramatically when the STFD undergoes highrate of excitation. Therefore, accurate numerical modelling of the STFD has been considered difficult due to this distinct feature. This study aims to develop a numerical model to accurately simulate the response of the STFD. First, a STFD is designed, fabricated, and installed in the laboratory. Then, performance tests are conducted in which sine waves with nine frequencies at three amplitude levels are adopted as the displacement excitations to the STFD. A novel numerical model which contains two parameter sets of the discrete Bouc-Wen model as well as two parameters for transiting the two parameter sets. Therefore, a total number of eighteen parameters need to be identified in the damper model. The symbiotic organisms search is applied to optimize the parameters. Numerical simulation results demonstrate that the proposed STFD model with transit parameter sets outperforms the conventional discrete Bouc-Wen model. The proposed STFD model can be applied to analyses of structures in which STFDs are installed in the future.

Real-time hybrid simulation of smart base-isolated raised floor systems for high-tech industry

Pei-Ching Chen,Shiau-Ching Hsu,You-Jin Zhong,Shiang-Jung Wang 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.23 No.1

Adopting sloped rolling-type isolation devices underneath a raised floor system has been proved as one of the most effective approaches to mitigate seismic responses of the protected equipment installed above. However, pounding against surrounding walls or other obstructions may occur if such a base-isolated raised floor system is subjected to long-period excitation, leading to adverse effects or even more severe damage. In this study, real-time hybrid simulation (RTHS) is adopted to assess the control performance of a smart base-isolated raised floor system as it is an efficient and cost-effective experimental method. It is composed of multiple sloped rolling-type isolation devices, a rigid steel platen, four magnetorheological (MR) dampers, and protected high-tech equipment. One of the MR dampers is physically tested in the laboratory while the remainders are numerically simulated. In order to consider the effect of input excitation characteristics on the isolation performance, the smart base-isolated raised floor system is assumed to be located at the roof of a building and the ground level. Four control algorithms are designed for the MR dampers including passive-on, switching, modified switching, and fuzzy logic control. Six artificial spectrum-compatible input excitations and three slope angles of the isolation devices are considered in the RTHS. Experimental results demonstrate that the incorporation of semi-active control into a base-isolated raised floor system is effective and feasible in practice for high-tech industry.

Servo control strategy for uni-axial shake tables using long short-term memory networks

Pei-Ching Chen,Kui-Xing Lai 국제구조공학회 2023 Smart Structures and Systems, An International Jou Vol.32 No.6

Servo-motor driven uniaxial shake tables have been widely used for education and research purposes in earthquake engineering. These shake tables are mostly displacement-controlled by a digital proportional-integral-derivative (PID) controller; however, accurate reproduction of acceleration time histories is not guaranteed. In this study, a control strategy is proposed and verified for uniaxial shake tables driven by a servo-motor. This strategy incorporates a deep-learning algorithm named Long Short-Term Memory (LSTM) network into a displacement PID feedback controller. The LSTM controller is trained by using a large number of experimental data of a self-made servo-motor driven uniaxial shake table. After the training is completed, the LSTM controller is implemented for directly generating the command voltage for the servo motor to drive the shake table. Meanwhile, a displacement PID controller is tuned and implemented close to the LSTM controller to prevent the shake table from permanent drift. The control strategy is named the LSTM-PID control scheme. Experimental results demonstrate that the proposed LSTM-PID improves the acceleration tracking performance of the uniaxial shake table for both bare condition and loaded condition with a slender specimen.

Morphological Responses of Grapevine Root to Copper Stress Given Different Calcium Nutritional Levels

Pei-Yi Chen,Kai-Wei Juang,Bo-Ching Chen,Yung-I Lee 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

Gastrodia elata Bl. Attenuated Learning Deficits Induced by Forced-Swimming Stress in the Inhibitory Avoidance Task and Morris Water Maze

Pei-Ju Chen,Keng-Chen Liang,Hui-Chen Lin,Ching-Liang Hsieh,Kuan-Pin Su,Mei-Chu Hung,Lee-Yan Sheen 한국식품영양과학회 2011 Journal of medicinal food Vol.14 No.6

This study adopted the forced-swimming paradigm to induce depressive symptoms in rats and evaluated the effects on learning and memory processing. Furthermore, the effects of the water extract of Gastrodia elata Bl., a well-known Chinese traditional medicine, on amnesia in rats subjected to the forced-swimming procedure were studied. Rats were subjected to the forced-swimming procedure, and the inhibitory avoidance task and Morris water maze were used to assess learning and memory performance. The acquisition of the two tasks was mostly impaired after the 15-minute forced-swimming procedure. Administration of the water extract of G. elata Bl. for 21 consecutive days at a dosage of 0.5 or 1.0 g/kg of body weight significantly improved retention in the inhibitory avoidance test, and the lower dose showed a better effect than the higher one and the antidepressant fluoxetine (18 mg/kg of body weight). In the Morris water maze, the lower dose of the water extract of G. elata Bl. significantly improved retention by shortening escape latency in the first test session and increasing the time in searching the target zone during the probe test. These findings suggest that water extracts of G. elata Bl. ameliorate the learning and memory deficits induced by forced swimming.

Acupuncture for ventilator-dependent patients at a hospital-based respiratory care center: A randomized controlled trial

Jia-Ming Chen,Wan-Li Chiang,Bin-Chuan Ji,Ruei-Jhe Jhang,Pei-Hsin Chen,Ya-Lun Li,Che-Ju Chang,Sung-Yen Huang,Tsung-Chieh Lee,Chia-Yun Chen,Ching-Hsiung Lin,Sheng-Hao Lin 한국한의학연구원 2023 Integrative Medicine Research Vol.12 No.4

Background: In intensive care units, mechanical ventilation is an important therapy to help patients with dysp- nea. However, long-term ventilator dependence would consume huge medical resources and increase the risk of morbidity and mortality. The aim of the study was to examine the efficacy of the acupuncture combined with western medical care on ventilator parameters in ventilator-dependent patients. Methods: In this clinical trial, 80 ventilator-dependent patients aged 20 to 80 years old were randomly assigned to acupuncture group and control group in the respiratory care center (RCC) of Changhua Christian Hospital. Besides regular medical care and therapy, participants in the acupuncture group received acupuncture therapy at the same 17 acu-points for 20 minutes once a day, a total of 12 sessions. The ventilator parameters were recorded to evaluate the respiratory efficiency for all participants. The primary outcome was rapid shallow breathing index (RSBI), and secondary outcomes were respiratory rate (RR), tidal volume (TV) and ventilation per minute (MV). Results: Though there was no significant difference in the parameter between the acupuncture group and the control group, we found the trend of decreasing RSBI in the acupuncture group. In subgroup analyses, the mean of RSBI significantly decreased 16.02 (with the SD in 60.84) in acupuncture group, while it increased 17.84 (with the SD in 39.38) in control group (p = 0.036) after 12 sessions. Conclusion: Acupuncture treatment can improve breathing ability of patients with respirator dependence in respiratory care center.

The Application of Creative Thinking Teaching in Nursing Education for Youth Children’s Nutrition

Ching-Chi Yeh,Ju-Chen Yen,Pei-Yu Lee 한국간호과학회 2023 한국간호과학회 학술대회 Vol.2023 No.11

Utilizing Creative Quality Management to Enhance Hand Hygiene among Healthcare Personnel

Pei-Yu Lee,Ju-Chen Yen,Ching-Chi Wang 한국간호과학회 2023 한국간호과학회 학술대회 Vol.2023 No.11