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A novel bio-inspired hierarchical tetrachiral structure that enhances energy absorption capacity
Duy Binh Pham,Shyh-Chour Huang 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.7
This study proposes a novel hierarchical tetrachiral structure inspired by the shell structure of nautilus animals. The parameters of unit cells were designed in compliance with the dimensions of the universal testing machine and the 3D printer. A model made up of 5×5 unit cells of the novel structure was designed and simulated in SolidWorks and ABAQUS software, respectively. To verify the accuracy of the simulated result, the fused deposition modeling 3D-printing technique was adopted to fabricate both traditional and novel structures with acrylonitrile butadiene styrene material and then the quasi-static compression test was conducted. Additionally, the influence of relative density and strain rate on the performance of the structures also was investigated in this study. The findings showed that the novel structure possesses higher energy absorption than the traditional structure. Furthermore, strain rate and relative density have a significant effect on the performance of the structure. Finally, the proposed novel structure can be used in energy-absorbing, impact-resistant devices.
( Dien Minh Vu ),( Binh Hoa Pham ),( Duc Pham Xuan ),( Dung Nguyen Dinh ),( Vinh Nguyen Duy ) 한국공업화학회 2023 공업화학 Vol.34 No.3
Fuel cells are one of the renewable energy sources that have sparked a lot of scientific attention for solving problems related to the energy crisis and environmental pollution. One of the most crucial subjects concerning the utilization of fuel cells is modeling. Therefore, an analytical steady-state and dynamic fuel cell model was described in this study. The parameter for the identification process was investigated, and the MATLAB/Simulink implementation was demonstrated. A 15-W proton exchange membrane fuel cell was used to apply the suggested modeling methodology. Comparing experimental and simulation findings indicated that the model error was constrained to 3%. This study showed that temperature and humidity affect fuel cell performance.
What Influences Decision on Seasoned Equity Offerings of Listed Vietnamese Companies?
LE, Long Hau,NGUYEN, Thi Binh Nhi,PHAM, Xuan Quynh,VUONG, Quoc Duy,LE, Tan Nghiem Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.5
This paper investigates the determinants on decision to conduct seasoned equity offerings (SEOs) of listed companies on the Ho Chi Minh Stock Exchange in Vietnam. Seasoned equity offerings (SEOs) are defined as the issue of more stocks by a firm to raise more capital after a primary issue. Using panel data collected from audited financial statements of 99 listed companies on the Ho Chi Minh Stock Exchange during 2014-2018, the study employs a logit regression model by fixed effects method to examine factors that affect the decision to implement seasoned equity offerings of those companies. The findings of this study show that profit, revenue growth and company's size have a positively significant impact on the decision, while dividend pay-out ratio negatively significantly influences the equity issuing decision. Furthermore, these results are robust after controlling for the forms of equity offerings, i.e. bonus stocks, stock dividends and rights to buy shares. These findings are consistent with economic theories such as agency theory, pecking order theory, and growth opportunity theory, and also could be explained by the real situations of the Vietnamese stock exchange. This study has important implications for corporate managers, policy makers and investors.