Necessary and sufficient conditions for quasi-strongly regularity of Graph Product

A $k$-regular graph ($k\ge 1$) with $n$ vertices is called a quasi-strongly regular graph with parameter $\lambda$ (\lambda\in\NN) if any two adjacent vertices have exactly $\lambda$ neighbors in common.A graph product is a binary operation on graphs. In this paper we prove some necessary and sufficient conditions for Decartes Product, Tensor Product, Lexicographical product and Strong product to be quasi-strongly regular

The influences of the number of concrete dowels to shear resistance based on push out tests

To reduce the depth of floor-beam structures and to save the cost of headed-shear studs, many types of shallow composite beam have been developed during the last few years. Among them, the shallow-hollow steel beam consists of web openings, infilled with in-situ concrete (named concrete dowel) has been increasingly focused recently. In this new kind of structure, this concrete dowel plays an important role as the principal shear connector. This article presents an investigation on the shear transferring mechanism and failure behavior of the trapezoid shape concrete dowel. An experimental campaign of static push-out tests has been conducted with variability in the number of web openings (WOs). The results indicate that the mechanical behavior of concrete dowel could be divided into crushing, compression, and tension zones and exhibits brittle behavior. The longitudinal shear resistance and specimen's stiffness are strongly affected by the number of considered WO

STUDY OF EFFECT OF FRICTION STIR WELDING PARAMETERS ON IMPACT ENERGY OF AA7075-T6

The influences of the tool rotation speed (denoted w) and the welding speed (denoted v) on the impact energy at the representative zones in the friction stir welding (FSW) of AA7075-T6 were investigated. Here, the standard V–Notched specimens were applied in which the notches were addressed at the stirred zone (SZ), the heat affected zones (HAZ) in both the advancing side and the retreating side and the mixed zone (MZ). The experimental results showed that, in all cases, the lowest impact energy is located at the stirred zone and that energy seems to be increased from the SZ to the HAZ across the welding. Furthermore, it is also found that the impact energy is decreased when the ratio of rotation speed to welding speed (w/v) is increased. The microstructure, the temperature distribution, and the hardness in and around the welded zone were considered and discussed

An Empirical Study of Affective Commitment: the Case of Machinery Enterprises in Hochiminh City

The study aims to investigate the impact of participation in decision-making (PDM) and perceived organizational support (POS) on affective commitment in machinery enterprises. The study applies structural equation modeling (SEM) to test the research hypotheses. The authors surveyed 220 employees who work in machinery enterprises to collect data for the research. The study results indicate that both PDM and POS positively impact affective commitment. The findings provide empirical evidence to support the theoretical models that PDM and POS have a positive effect on affective commitment. The findings have implications for management theory: PDM and POS are the key antecedents of affective commitment. The findings also have implications for practical management in the machinery enterprises that managers should practice both PDM and POS to increase affective commitment

PROTECTIVE BEHAVIOR AGAINST COVID-19 AMONG VIETNAMESE PEOPLE IN THE SOCIAL DISTANCING CAMPAIGN: A CROSS-SECTIONAL STUDY

In the global fight against the rapid spread of COVID-19, a variety of unprecedented preventive measures have been implemented across the globe, as well as in Vietnam. How Vietnamese people respond to threats to their health and life remains unclear. For this reason, the current study aims to examine Vietnamese people’s protective behavior and its factors. Based on 1,798 online survey respondents’ data collected on the last three days of the nationwide social distancing campaign in mid-April, it is found that gender, knowledge of COVID-19 and preventive measures, and attitudes towards the COVID-19 prevention policies are the three main factors of participants’ protective behaviors. We also find that males are less likely than females to adopt precautionary measures. People who are knowledgeable about COVID-19 may have inappropriate practices towards it. Further research is needed to examine other determinants of protective behaviors to provide more useful information for authorities, public health policy-makers, and healthcare workers to deliver the best practices to control COVID-19 in our country

GEOTOURISM CURRENT STATE AND FUTURE PROSPECTS: A CASE STUDY IN THE CAO BANG UNESCO GLOBAL GEOPARK, VIETNAM

Cao Bang Geopark is one of three UNESCO heritage sites in Vietnam, with unique geological, landscape and cultural properties of high value to tourism. This study aims to provide a better understanding of the potential for geotourism development in Cao Bang Global Geopark, thereby proposing reasonable development strategies in the future. The research using the multicriteria assessment and SWOT analysis tool found that Cao Bang Global Geopark has a high ability to attract tourists and exploit large tourism resources globally. However, the infrastructure, technical facilities, human resources and investment capital for geotourism are still limited and need to be improved. The research results can be considered useful references for academia and managers in finding strategies and solutions for sustainable geotourism development at Cao Bang Geopark in the future