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Dong Van VU1,Tai Van PHAM2,Ghi Nha TRAN3,Anh Phuong Thi NGUYEN4,Cong Van NGUYEN5 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.6
This study seeks to examine the relationship between business resources (through VRIN: Valuable - valuable, Rare - scarce; Inimitable - difficult to adapt, Irreplaceable - hard to replace), dynamic capability, external cooperation, and efficiency of startups operating in the seafood export sector. Research data was collected randomly and conveniently from 250 enterprises in Ba Ria-Vung Tau province, Vietnam, from October 2020 to December 2020. After excluding those ineligible, the remaining 204 enterprises meet the research conditions. With the support of SPSS-AMOS 22 dedicated software, using the 5-step Likert scale and Structural Equation Modeling (SEM), the study conducted analysis steps such as verifying convergence, discriminant value, unidirectional and scale reliability when giving the components correlated freely in the critical model by Confirmatory Factor Analysis (CFA) analysis. Results of the study have shown that the enterprise resource factor - VRIN has a positive impact on dynamic capability, and outside cooperation. However, in contrast to previous studies, we found that the relationship between enterprise resources - VRIN and performance as well as the relationship between dynamics capacity and performance is not clear. This shows that seafood exporters need to promote, exploit and effectively use this precious resource to improve business efficiency.
Dynamic analysis of the 3CRS parallel robot using carbon/natural fibers hybrid composite links
Anh Vu Nguyen,Belhassen Chedli Bouzgarrou,Karine Charlet,Alexis Beakou 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10
With the aim of improving the damping capacity of high-speed industrial robots, the links made of carbon/natural fibers reinforced hybrid composite is used for replacing aluminum links in the limbs of the 3CRS robot, a 6-degrees of freedom (DOFs) parallel robot with only 3 limbs. In this paper, vibration and damping analyses of the 3CRS robot, integrating composite links, are presented. The dynamic analysis of the robotic structure with the viscoelastic composite links are performed by an analytical method based on the matrix structural analysis method combined with the Lagrange equations and the correspondence principle. By using the analytical method, the modal frequencies and the loss factor of the reformed robot with the hybrid composite links are determined and compared with those of the initial robot with the aluminum links. The results show that the reformed robot with the hybrid composite links has similar modal frequencies, but considerably higher damping capacity in comparison with the initial robot. The damping improvements could allow the robot to achieve higher precision, operate with faster speeds/accelerations and work in harder dynamic loading conditions. It confirms therefore the benefits of using carbon/natural fibers hybrid composite in robotic structures.
Focusing ultrasonic waves in a 2-D covered channel above the periodic array of Helmholtz resonators
Anh Hoang Vu,황영인,김학준,송성진 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.10
This paper presents the numerical simulation and experiments on focusing low-frequency ultrasonic waves in a 2-D covered channel above acoustic metamaterials composed of the periodic array of Helmholtz resonators, in which the refractive index can be in a negative value. The 2-D channel above the acoustic metamaterials is covered by a plate to limit the area affected by the negative refractive index metamaterials. Ultrasonic waves propagated in the 2-D covered channel are found to be highly dependent on input frequency and the designed Helmholtz resonator structure, where its negative refractive index causes the focusing phenomenon in this channel. From the numerical simulation and experiments, an amplitude focus spot is observed in the peak-to-peak of the time domain signal and frequency response at 125 kHz by mapping a pressure field in the 2-D covered channel. Different focal points with several input frequencies are also identified. Our research demonstrates the possibility of applying the designed lens based on acoustic metamaterials to improve the focusing effect in ultrasonic testing.