Stabilization for equal-order polygonal finite element method for high fluid velocity and pressure gradient

This paper presents an adapted stabilisation method for the equal-order mixed scheme of finite elements on convex polygonal meshes to analyse the high velocity and pressure gradient of incompressible fluid flows that are governed by Stokes equations system. This technique is constructed by a local pressure projection which is extremely simple, yet effective, to eliminate the poor or even non-convergence as well as the instability of equal-order mixed polygonal technique. In this research, some numerical examples of incompressible Stokes fluid flow that is coded and programmed by MATLAB will be presented to examine the effectiveness of the proposed stabilised method

A Tourists' Travel Intention in the Context of Covid-19 in Viet Nam

The novel coronavirus pneumonia has seriously affected the development of tourism in Vietnam and even the whole world. Combining the current of VietNam's mitigation and the gradual recovery of tourism, this paper puts the research perspective on tourists' travel intention, and constructs a new theoretical structure by using TPB and TRA theory, This study presents the findings of a research which examined the relationship Subject norms and perceived behavioral control have a significant impact on Attitude and tourists' desire to travel;  the Attitude and desire to travel has a significant positive impact on tourists' travel intention, a little empirical study investigates these relationships together. This article investigates these relationships using SEM with data 437 tourists in the Vietnam. Findings of the study revealed that Attitude mediates the relationship between Subject norms, Perceived Behavioral Control, and Travel intention. Desire to travel mediates the relationship between Subject Norm, Perceived Behavioral Control and Travel intention. Based on the study findings, implications for theory and practice are discussed. Keywords: COVID-19, Theory of planned behaviour(TPB), Theory of reasoned action(TRA),Viet Nam DOI: 10.7176/EJBM/13-14-07 Publication date:July 31st 202

Lignin and Cellulose Extraction from Vietnam’s Rice Straw Using Ultrasound-Assisted Alkaline Treatment Method

The process of cellulose and lignin extraction from Vietnam’s rice straw without paraffin pretreatment was proposed to improve economic efficiency and reduce environmental pollution. Treatment of the rice straw with ultrasonic irradiation for 30 min increased yields of lignin separation from 72.8% to 84.7%. In addition, the extraction time was reduced from 2.5 h to 1.5 h when combined with ultrasonic irradiation for the same extraction yields. Results from modern analytical methods of FT-IR, SEM, EDX, TG-DTA, and GC-MS indicated that lignin obtained by ultrasound-assisted alkaline treatment method had a high purity and showed a higher molecular weight than that of lignin extracted from rice straw without ultrasonic irradiation. The lignin and cellulose which were extracted from rice straw showed higher thermal stability with 5% degradation at a temperature of over 230°C. The ultrasonic-assisted alkaline extraction method was recommended for lignin and cellulose extraction from Vietnam’s rice straw

Factors influencing the urge to buy impulsively of Vietnamese online buying customers towards Biti’s Hunter sport shoes

Our study investigates the factors that drive Vietnamese online shoppers in Ho Chi Minh City (HCMC) to make impulsive purchases of Biti's Hunter sports shoes (BHS), using the Stimulus-Organism-Response (S-O-R) theory and the Technology Acceptance Model (TAM). Mixed methods are applied: in-depth interviews with ten regular online shoppers and focus group discussions with e-commerce managers for qualitative data collection, and survey techniques to gather quantitative data from 319 online shoppers. Data analysis was performed using SPSS 22.0 and AMOS 22.0. Our findings reveal five factors as a stimulus - visual appeal, website ease of use, product availability, portability, and social influence – and three factors as an organism - instant gratification, impulsiveness, and trust, that lead to the response of urge to buy impulsively. Significant positive effects are found among these constructs, except the relationship between portability and impulsiveness, visual appeal, social influence, trust, instant gratification, and urge to buy impulsively

The impact of firm size on the performance of Vietnamese private enterprises: A case study

This article investigates the effect of firm size on the performance of Vietnamese private enterprises. Based on the data from the Annual Enterprise Survey from 2009 to 2018, this study uses an ordinary least-squares regression model (OLS) to point out the effects of firm size (growth rate, total assets, and total labor) on the performance of Vietnamese private enterprises in both static and dynamic states. According to the results of the quantitative model, total assets are the biggest factor for determining firm performance, followed by total labor and growth rate. The results highlight the issue in Vietnamese private enterprises development in terms of scale, despite the fact that their number is growing, as the scale of enterprises decreases (the proportion of micro and small enterprises increases, but the proportion of medium and big enterprises decreases). Besides, the disadvantages of scale also negatively affect the development process of Vietnamese private enterprises, including accessing capital, increase in production or productivity, business expansion, and improving competitiveness. AcknowledgmentsThis research is supported by the National Science Project “Development of Private Enterprises in the Southwest Region in the new context” (KHCN-TNB/14-19/X15)

POTENTIOMETRIC SENSOR FOR HYDROGENE ION BASED ON NEUTRAL CARRIER IN A POLY (VINYL CHLORIDE) MEMBRANE WITH POLYANILINE SOLID CONTACT

Joint Research on Environmental Science and Technology for the Eart

Effects of financial statements information on firms’ value: evidence from Vietnamese listed firms

The paper studies the effects of information reporting in financial statements on values of Vietnamese firms. The study uses panel data with 1,070 observations from 214 firms, which are listed in the stock market of Vietnam in the period from 2012 to 2016. Multiple regression results show that the growth, firm size, profitability, auditing quality and timelineness are positively related to firm values, whereas the capital structure, auditing explanation negatively affect that indicator. The paper also indicates the inconsistency in measuring firms’ value by different measures including EV, Tobin’s Q or share price. Moreover, the research results reflect that measuring firms’ value by EV is more appropriate. The results of empirical research are instructive for enterprises to improve the usefulness of information in financial statements, thereby enhancing enterprises’ values

VLSP SHARED TASK: SENTIMENT ANALYSIS

Sentiment analysis is a natural language processing (NLP) task of identifying orextracting the sentiment content of a text unit. This task has become an active research topic since the early 2000s. During the two last editions of the VLSP workshop series, the shared task on Sentiment Analysis (SA) for Vietnamese has been organized in order to provide an objective evaluation measurement about the performance (quality) of sentiment analysis tools, and encouragethe development of Vietnamese sentiment analysis systems, as well as to provide benchmark datasets for this task. The rst campaign in 2016 only focused on the sentiment polarity classication, with a dataset containing reviews of electronic products. The second campaign in 2018 addressed the problem of Aspect Based Sentiment Analysis (ABSA) for Vietnamese, by providing two datasets containing reviews in restaurant and hotel domains. These data are accessible for research purpose via the VLSP website vlsp.org.vn/resources. This paper describes the built datasets as well as the evaluation results of the systems participating to these campaigns

A computational study on structure and stability of nitrogen-doped titanium clusters TinN (n = 1-10)

A study was performed using density functional theory at the PW91PW91/DGDZVP2 level to investigate the structures and stability of the neutral nitrogen-doped titanium clusters TinN (n = 1-10). The most stable isomers may have spin state ranging from doublet to quartet to sextet. Interestingly, the ground-state structures of these clusters are consistently formed by adding an N atom on an edge and a face of the pure titanium cluster and the N atom prefers to stay on surface of the clusters. Doping with an N atom increases the stability of titanium clusters and decreases their metallicity. Moreover, the analyses of average binding energy, second-order energy differences and fragmentation energy according to cluster size imply a special stability of Ti6N. Keywords. N-doped titanium clusters, PW91PW91 functional, cluster stability, electronic structure, HOMO‑LUMO gap

RESEARCH AND PRODUCTION OF PERMEABLE CONCRETE AS A SUSTAINABLE SURFACE LAYER FOR URBAN INFRASTRUCTURES AND THE EFFECT OF MAINTENANCE METHOD ON ITS INFILTRATION CAPACITY

Recently, permeable concrete has been considered one of the "Best Management Practices" in rainwater collection and cleaning. The outstanding properties of this type of concrete are its relatively high porosity (typically 15 ÷ 30% in volume) and the linking/connection of the internal pore system resulting in high water permeability and retention. However, one of the limitations to the widespread application of this eco-friendly material is the decrease of permeable capacity over time due to the clogging materials and the lack of regular maintenance. This paper performs an experimental approach for manufacturing permeable concrete that has both high water permeability and meets the strength requirement (1). At the same time, the influence of clogging sand and typical maintenance methods on the infiltration rate of permeable or pervious concrete is presented (2). Based on the literature review and obtained experimental results in this study, maintenance measures to ensure the required permeability for urban surface structures and sustainable surface water drainage are also proposed (3)