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Tri Cuong Do,Tri Dung Dang,안경관 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.4
Wave energy is known to be a promising energy source for the goal of environmental protection and reducing dependence on fossil fuel sources. Hydraulic power-take-off (HPTO) is a key technology of wave energy converters which determines the energy recovery efficiency of the whole system. This paper presents a novel control strategy for HPTO to enhance the regenerated power and energy efficiency by using a suitable configuration of a variable displacement hydraulic motor and a generator. A control management strategy was designed to adjust the tilt angle of the hydraulic motor and the generator resistance load to maintain them working in the highest performance area under variable wave conditions. To verify the proposed system, a simulation model was built in AMESim software based on the previous experiment test bench configuration. Simulation results showed that by applying the proposed strategy, the generated energy increased during the working process. Compared with other control methods, the improvement of energy generation efficiency of the proposed control management method was approximately 10% higher in the low and medium wave conditions.
Impact of Vocational Training on Wages of Ethnic Minority Labors in Vietnam
DO, Ha Thi Hai,MAI, Cuong Ngoc,MAI, Anh Ngoc,NGUYEN, Nui Dang,PHAM, Toan Ngoc,LE, Huong Thi Thu,TRAN, Manh Dung,VU, Tri Tuan Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.6
This research investigates the impact of vocational training on wages of ethnic minority labors in emerging countries; Vietnam is the case study. The study uses secondary data from 2014 to 2018 collected through Vietnam Household Living Standards Surveys (VHLSS) conducted by the General Statistics Office. In order to analyze the impact of vocational training on wages of ethnic minority areas in Vietnam, this research creates ethnic area variables. According to Vietnamese regulations, ethnic areas are communes of 51 different provinces, inhabited by ethnic minority people. The statistics from VHLSS in 2018, show that the proportion of labors of working age with a certificate was 22.5%. The research employs Heckman Sample Selection Model to estimate the impact of vocation training on wage of labors in ethnic minority areas. The results show that vocational training plays a crucial role in improving the wages of ethnic minorities and has a positive impact. However, apart from the achieved outcomes, vocational training and job creation for ethnic minorities are not without limitations and shortcomings. Based on the findings, some recommendations to ethnic minority labors, enterprises and the Government are proposed to encourage participation in vocational training for the purpose of promoting the efficiency of the labor market.
Tri Dung Dang,Tri-Cuong Do,안경관 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.5
The hydraulic power take-off (HPTO) is considered as the most promising method to convert wave power to electrical power. This paper presents an experimental assessment of the power conversion of a wave energy converter using HPTO. Based on the experimental results, a modification of accumulator pre-charged pressure and a control strategy were proposed to improve the system performance. System design, the working principle and mathematical model of all components were described. The proposed method was verified based on both simulation and experimental tests. The results showed that the system always works at an optimal condition under different input wave conditions.
Tri Dung Dang,Tri Cuong Do,Hoai Vu Anh Truong,Cong Minh Ho,Hoang Vu Dao,YU YINGXIAO,정은진,안경관 사단법인 유공압건설기계학회 2019 드라이브·컨트롤 Vol.16 No.1
The objective of this study was to design and model the PEM fuel cell excavator with supercapacitor/battery hybrid power source to increase efficiency as well as eliminate greenhouse gas emission. With this configuration, the system can get rid of the internal combustion engine, which has a low efficiency and high emission. For the analysis and simulation, the governing equations of the PEM system, the supercapacitor and battery were derived. These simulations were performed in MATLAB/Simulink environment. The hydraulic modeling of the excavator was also presented, and its model implemented in AMESim and studied. The whole system model was built in a co-simulation environment, which is a combination of MATLAB/Simulink and AMESim software. The simulation results were presented to show the performance of the system.
Dang, Tri Dung,Do, Tri Cuong,Truong, Hoai Vu Anh,Ho, Cong Minh,Dao, Hoang Vu,Xiao, Yu Ying,Jeong, EunJin,Ahn, Kyoung Kwan The Korean Society for Fluid Power and Constructio 2019 드라이브·컨트롤 Vol.16 No.1
The objective of this study was to design and model the PEM fuel cell excavator with supercapacitor/battery hybrid power source to increase efficiency as well as eliminate greenhouse gas emission. With this configuration, the system can get rid of the internal combustion engine, which has a low efficiency and high emission. For the analysis and simulation, the governing equations of the PEM system, the supercapacitor and battery were derived. These simulations were performed in MATLAB/Simulink environment. The hydraulic modeling of the excavator was also presented, and its model implemented in AMESim and studied. The whole system model was built in a co-simulation environment, which is a combination of MATLAB/Simulink and AMESim software. The simulation results were presented to show the performance of the system.
Improvement of Energy Saving for Hybrid Hydraulic Excavator with Novel Powertrain
Yingxiao Yu,Tri Cuong Do,Bifeng Yin,Kyoung Kwan Ahn 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.2
To reduce the energy consumption and emission, an innovative powertrain and the energy management strategy are proposed for hydraulic excavator in this paper. The novel powertrain consists of the engine, motor/generator, planetary gear, gearbox, and variable hydraulic pump. The energy regeneration system is also applied on the system to regenerate the potential energy and charge the battery. An improved equivalent consumption minimization strategy is proposed to control the engine, motor/generator, hydraulic pump and gearbox. The engine working points can be located in high efficiency range, with the proposed powertrain and the energy management strategy. To verify the energy saving efficiency of the proposed system, the test bench is built in laboratory. Compared with the current hybrid system, the energy saving efficiency reaches 11% in condition of a large velocity. Compared with the current hybrid system and conventional system, the energy saving efficiencies are 4% and 48% respectively with different cylinder velocities. The fuel consumption and emission of hydraulic excavator can be reduced effectively with the proposed powertrain and energy management strategy.
Independent Metering Valve: A Review of Advances in Hydraulic Machinery
Thanh Ha Nguyen,Tri Cuong Do,Kyoung Kwan Ahn 유공압건설기계학회 2020 드라이브·컨트롤 Vol.17 No.4
In light of the environmental challenges, energy-saving strategies are currently under investigation in the construction industry. This paper focuses on the energy-saving method used in the hydraulic system based on independent metering (IM) technologies, which can overcome the lost energy at the main control valve of the conventional electrohydraulic servo system. By scientifically arranging the proportional valves, the IM system can individually control the flow rate of the inlet and the outlet ports of the actuators. In addition, the IMV system can be used to effectively regenerate energy under different operating modes, thereby saving more energy than conventional hydraulic systems. Therefore, the IMV system has a great potential to improve the energy efficiency of hydraulic machinery. The overall IMV system, including the configuration, proportional valve, operation mode, and the control strategy is introduced via state-of-the-art hydraulic technologies. Finally, the challenges of IM systems are discussed to provide researchers with directions for future development.
Duc-Thien Tran,Tri-Cuong Do,안경관 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.12
This paper presents a robust control regarding position control of an electro-hydraulic rotary actuator (EHRA) system under the presence of the lumped uncertainties such as the variant payload, the unknown friction, and the uncertain parameters. The proposed control is developed on a high order sliding mode control (HOSMC) and an extended high gain observer (EHGO). In detail, the HOSMC is derived to not only reduce the chattering effect but also guarantee the stability for the EHRA. In addition, the EHGO is used as a disturbance estimator to compensate the lumped uncertainties. Consequently, it helps to improve control performance. Furthermore, the stability and robustness of the whole system are theoretically proved by a Lyapunov approach. The proposed control is practically implemented through both the co-simulation between AMESIM and MATLAB, and the experiments. The results are compared to other controllers to exhibit the effectiveness of the proposed control with the lumped uncertainties.
Hoang Vu Dao,Xuan Dinh To,Hoai Vu Anh Truong,Tri-Cuong Do,Cong Minh Ho,Tri Dung Dang,안경관 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.4
Fuel cell hybrid electric construction equipment (FCHECE) is known as a promising solution to achieve the goal of energy saving and environment protection. Energy management strategy is a key technology of FCHECE, which splits the energy fl ow between power sources. This paper presents a novel optimal energy management strategy for a hybrid electric-powered hydraulic excavator system to enhance power performance, power sources lifespan, and fuel economy. As for the proposed powertrain configuration, fuel cell serves as a primary energy source, and supercapacitor and battery are considered as energy storages. The integration of supercapacitor and battery in fuel cell vehicle has advantages of improving power performance and storing the regenerative energy for future usage. An energy management strategy based on fuzzy logic control and a rule-based algorithm is proposed to effectively distribute the power between the three sources and reuse the regenerative energy. Furthermore, the parameters of the fuzzy logic system are optimized using the combination of a backtracking search algorithm which provides a good direction to the global optimal region and sequential dynamic programming as a local search method to fi ne-tune the optimal solution in order to reduce the hydrogen consumption and prolong the lifetime of the power sources. Simulation results show that the proposed energy management strategy enhances the vehicle performance, improves fuel economy of the FCHECE by 10.919%, increase battery and supercapacitor charge-sustaining capability as well as efficiency of the fuel cell system.