Fabrication and evaluation of capacitive silicon resonators with piezoresistive heat engines

Van Toan, N.,Van Nha, N.,Song, Y.,Ono, T. Elsevier Sequoia 2017 Sensors and actuators. A, Physical Vol.262 No.-

<P>This work reports the design, fabrication and evaluation of capacitive silicon resonators with piezoresistive heat engines. A combination of capacitive transduction and piezoresistive actuation based on a piezoresistive heat engine in the single micromechanical resonator is proposed to achieve a low insertion loss and small motional resistance. Capacitive silicon resonators with single and multiple piezoresistive beams have been demonstrated. In these structures, resonant bodies are divided into many parts that are connected to each other by using small piezoresistive beams to enhance electromechanical transductions by the piezoresistive heat engines. When a bias voltage V-b = 7 V is applied to the piezoresistive beams, the insertion loss and motional resistance of the capacitive silicon resonator with multiple piezoresistive beams are improved by 20 dB (enhanced from -68 dB to -48 dB) and 90% (reduced from 125.5 k Omega to 12.5 k Omega), respectively, in comparison to the case without a bias voltage. In addition, the tuning frequency characteristic with the piezoresistive effect is increased by 165 times over that of the structure with only the capacitive effect. (C) 2017 Elsevier B.V. All rights reserved.</P>

An online Indigenous Knowledge Database on Climate Change Adaptation of Farmers in the Vietnam Mekong Delta

Van Hoa Nguyen,Thi Mai Phung Bui,Thanh Phong Le,Hoang Tung Nguyen,Minh Tuyen Truong,Minh Nhut Do,Van Nha Duong 인간식물환경학회 2022 인간식물환경학회지 Vol.25 No.6

Background and objective: For countries vulnerable to climate change as Vietnam, indigenous knowledge (IK) might assist in revealing the values of local people's adaptations to environmental stresses and potentially support decision-making. Despite IK can provide the adaptive capacity of local people's activities within environmental contexts, but it is rapidly vanishing. This study aimed to describe the documentation of IK associated with climate change adaptation of farmers in the Vietnam Mekong Delta (VMD). Methods: We focused on collecting and establishing online access to IK documents through collaboration between IK holders, public sector, collecting institutions, and researchers in the five agro-ecological zones of the VMD. An online IK database for storing IK documents has been designed and implemented based on the web application schema. Results: Through interviews, we gathered IK from farming practices that are well-adapted to climate risks such as floods, droughts, and saltwater intrusions as well as traditional knowledge being used to forecast weather, flood, and saltwater intrusion. The database for storing IK documents has been successfully deployed using free and open-source software. The database currently contains more than 260 IK documents, with their location on agro-ecological zones displayed on a web-based map. Conclusion: We have captured and provided an online access to IK on climate change adaptation of the farmers in the VMD. This research is expected as an initial strategy for long-term sustainable development of the agriculture system in this region.

The Relationship Between Business Resources, Outside Cooperation, Dynamic Capability, and Performance of Startup Enterprises

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.

Factors Affecting Sustainable Tourism Development in Ba Ria-Vung Tau, Vietnam

VU, Dong Van,TRAN, Ghi Nha,NGUYEN, Hien Thi Thu,NGUYEN, Cong Van Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.9

Sustainable development - including tourism development - is the general trend of all economies. With the orientation to build and develop the tourism industry into a key economic sector and become a tourist center of the Southeast region, Vietnam, Ba Ria-Vung Tau Province is demanding a proper, rational, development policy, while ensuring the development and exploitation of immediate natural advantages, and ensuring long-term sustainable development. The objective of this study is to examine the factors and their trends in sustainable tourism development in Ba Ria-Vung Tau Province, Vietnam. Methods used include descriptive statistical analysis, exploratory factor analysis and regression analysis. Data was collected from the results of a survey of 550 domestic and foreign tourists visiting Ba Ria-Vung Tau. With the help of SPSS statistical software, 12 groups of factors affecting sustainable development were identified including: economy, society, environment, humanistic tourism resources, natural tourism resources, tourism human resources, tourism products and service, tourism quality, infrastructure, technical facilities, governmental management and group of criteria to evaluate sustainable tourism development. The research results show that there are four groups of factors that significantly affect sustainable tourism development in Ba Ria-Vung Tau. These are groups of factors: Society, Environment, Tourism products and service, and Technical facilities.

Compressive Force Control of Flexure Bearings of Semi-active QZS Vibration Isolator

Pham Van Trung(팜반트콩),Pham Minh Nha(팜민나),Kyoung-Rock Kim(김경록),Hyeong-JoonAhn(안형준) 한국트라이볼로지학회 2011 한국트라이볼로지학회 학술대회 Vol.2011 No.10

Sustainable Earnings and Its Forecast: The Case of Vietnam

DO, Nhung Hong,PHAM, Nha Van Tue,TRAN, Dung Manh,LE, Thuy Thu Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.3

The study aims to provide better understanding of sustainable earnings by a comprehensive analysis of earnings persistence of business firms in Vietnam as an example of developing economies in South-East Asia. Dataset of 1,278 publicly listed firms (excluding banking and financial services firms) on Vietnam Stock Exchange for the period from 2008 to 2017 was collected. By applying fixed effect regression model, the empirical results provided the basis to measure the persistence index (Pers index) and find low level of their earnings persistence. The literature of earnings quality analysis in developed countries suggests earnings persistence as a noteworthy determinant of future earnings forecast and stock valuation. However, research of sustainable earnings in developing countries is still highly underdeveloped. For Vietnamese listed firms, the average Pers index was estimated for the period from 2008 to 2010, indicating low level of earnings persistence. We also incorporated earnings persistence level into future earnings forecast by running the quintile regression model divided the data into four equal levels and conducted each section independently to see the difference in each percentile, thence assessed the factors' influence on the specific model. The findings provide important information on the expected returns of firms, especially helping investors make sound decisions.

Biodiversity of Superfamily Pyraloidea (Lepidoptera) in Northern Vietnam

Y. S. Bae,Pham Van Nha,Pham Thi Vuong 한국응용곤충학회 2005 한국응용곤충학회 학술대회논문집 Vol.2005 No.05

A Fault-tolerant Synchronous Sliding Mode Control for a 4-DOF Parallel Manipulator With Uncertainties and Actuator Faults

Duc Thien Tran,Nguyen Thanh Nha,Ngo Van Thuyen,Le Hoang Lam,Kyoung Kwan Ahn 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.4

This paper proposes a novel fault-tolerant synchronous sliding mode control for a 4-DOF parallel manipulator against uncertainties such as modelling error and actuator faults. The proposed control is developed with the consensus approach, sliding mode control, and extended state observer to manage the tracking objective and guarantee the synchronous requirements. The consensus approach combines the tracking and synchronous errors, which helps to integrate both the tracking and synchronous requirements into cross-coupling errors. Firstly, the kinematics and dynamics of the parallel manipulator are described according to the geometric and Euler Lagrange approaches with the challenges. Secondly, the Lyapunov approach is implemented to verify the stability and robustness of the proposed control in theory. Then, some simulations are conducted in MATLAB Simulink with the robotic dynamics generated by converting the design model in SOLIDWORKs into SIMSCAPE. The comparisons between the proposed control and other controllers are made by creating simulations to evaluate the advantages of the proposed approach.

Taxonomic Notes of Moths (Lepidoptera) in the North Vietnam

Yang-Seop Bae,Le Xuan Vi,Kyu-Tek Park,Nguyen Nhu Cuong,Pham Van Nha,Pham Thi Vuong,Jong-Gyun Park 한국응용곤충학회 2009 한국응용곤충학회 학술대회논문집 Vol.2009 No.05

In Vietnam, the moths were reported by some foreign entomologist such as de Joannis (1900), Ronkay (1989), Speidel & Kononenko (1998), Park et al. (2006), and Lien et al. (2008). In 1928 -1929 de Joannis created the original data of moths. His final reports on Lepidoptera were 45 families, 611 species of Noctuidae, and 461 species of Pyralidae. After the Vietnam War in North (1954), many times were collected in North Vietnam by National Institute of Plant Protection (NIPP). But all of them focused on fauna of the agricultural pests. According to the publication of NIPP (1967-1968), 533 species of 37 families of which there were 91 species of Noctuidae in the North Vietnam and some other moths known as the insect pests have been reported. In 1977 there were 77 species of Pyralidae known as the insect pests in the North Vietnam. The purpose of this study is to assess diversity of Lepidoptera order and to clarify the fauna in the Northern part of Vietnam, base on the Korea Vietnam collaborative insect-research project (2004-2006). The collecting have been conducted in four National Parks (Tam Dao, Cuc Phuong, Ba Be, and Bach Ma) Given results of the survey in the North of Vietnam from 2002 to 2006, 816 species of Lepidoptera classified by 4 families; Noctuidae (564 species), Pyraloidae (201 species), Sphingidae (28 species), and Lecithoceridae (23 species). Many of the identified species of macro-moths including Noctuidae, Pyraloidae and Lecithoceridae are known as the very newest one in Vietnam.