Seismic study of shallow circular tunnel in Red River sand (Vietnam)

Attention should be paid to tunnels' seismic behaviour since many of them have been damaged by earthquakes. The paper presented a seismic study of a shallow circular tunnel by physical modelling on shaking table test. A small scale tunnel model of the Hanoi pilot metro line's underground segment was placed in the middle of a rigid soil container and buried in Red River sand (Vietnam). The table was vibrated along the soil container's long wall, with a simulated seismic wave created from the 1788 Tolmezzo (Italia) accelerogram. Five testing campaigns were executed, and the model's acceleration data were studied. The uni-directional vibration created by the shaking table caused the three-directional vibration of the physical model. The Fast Fourier Transform (FFT) frequency spectrum analyses were performed. The vibration characteristics of the model (i.e., frequency graph's structure, maximal acceleration, dominant frequency, strong-motion duration) in three orthogonal directions under the artificial earthquake action were compared. The obtained results proved the complicated seismic impacts on a shallow tunnel

Moment Resistances of wide flange beams with initial imperfection and residual stresses

Elastic and inelastic moment resistances of W-steel beams with considering the effects of initial imperfections and residual stresses are numerically investigated in the present study. The numerical model is implemented in ABAQUS in which residual stresses are incorporated by using initial conditions while the initial imperfection is imported through the first lateral-torsional buckling mode. By comparing the FEA moment resistances of W250x45 steel beams against those of the CSA S16 and Eurocodes 3 design standards, it is observed that (i) If the effects of initial imperfections and residual stresses are excluded, the inelastic resistances are close to a fully plasticized section moment. In contrast, if the effects are included, the inelastic resistances are significantly smaller than the fully plasticized moment. (ii) The effects of initial imperfections on the moment resistance are significant for intermediate and long spans. Although the initial imperfection taken in the present study is 4.0 mm, that is within the allowable limit specified in the design standards (i.e., not greater than L/1000), the moment resistances with the taken imperfection are considerably smaller than the design moments specified in the design standards, and (iii) When considering steel beams with the effects of initial imperfection and residual stresses, the moment resistances based on the CSA S16 and EC3-6.3.2.3 solutions are higher, while those based on EC3-6.3.2.2 solution are lower than the moment capacities of the beams with the initial imperfection. This indicates that EC3-6.3.2.2 clause is the most safety design for the moment resistances

The Influence Of Human Resource Policy On Job Satisfaction In Predicting Organizational Commitment

Purpose:  This research aims to explore the relationship among  human resource policy, job  satisfaction and  organizational commitment  through  the perception of employees working in small and medium enterprises in Vietnam.   Theoretical framework: The human resource functions and related distinct processes that help attract, develop, and retain a company's human resources. They involve employees and guide them to help carry out activities aimed at achieving organizational goals employees (Jahanian et al., 2012).  Business leaders are always cautious when reviewing existing human resource policies and constantly improving to make employees satisfied with their jobs, thereby helping them improve their productivity and commitment to the organization.    Design/methodology/approach:   The qualitative method is based on an overview of previous studies, the research team builds the first scale, then the questionnaire is sent to the experts and conducts a trial survey with 30 employees to control the survey, edit and complete the concepts of the questionnaire. For the quantitative research, data was collected using convenience sampling method from a total of 400 employees and managers who are working at SMEs in Viet Nam. The method of  and Confirmatory Factor Analysis (CFA),  Structural Equation Modeling (SEM) were carried out to measure the influence of latent variables on  organizational commitment.   Findings:  The research results show that employees' perceptions of HR policies include selection and recruitment; training and improvement; evaluation of employees’ tasks; stability and promotion in work, remuneration and reward, and encouragement of participation and innovation.  These HR policies have a direct positive impact on job satisfaction and commitment to the organization. In addition, job satisfaction has a significant positive effect on organizational commitment. Therefore, it is necessary to improve the implementation of HR policies to promote employee job satisfaction, which helps to increase commitment to the organization.    Research, Practical & Social implications:  We recommend future research that expands on other components for a comprehensive assessment of HR policies. In addition, it is necessary to analyze in detail the components of organizational commitment such as affective commitment,  Continuance commitment, Normative commitment.   Originality/value: The results of standardized estimation of the parameters of the research model show that the relationship between the concepts in the formal research model is statistically significant (p<0.05). HR policies have been shown to have the most positive impact on job satisfaction in SMEs.&nbsp

Moment Resistances of wide flange beams with initial imperfection and residual stresses

Elastic and inelastic moment resistances of W-steel beams with considering the effects of initial imperfections and residual stresses are numerically investigated in the present study. The numerical model is implemented in ABAQUS in which residual stresses are incorporated by using initial conditions while the initial imperfection is imported through the first lateral-torsional buckling mode. By comparing the FEA moment resistances of W250x45 steel beams against those of the CSA S16 and Eurocodes 3 design standards, it is observed that (i) If the effects of initial imperfections and residual stresses are excluded, the inelastic resistances are close to a fully plasticized section moment. In contrast, if the effects are included, the inelastic resistances are significantly smaller than the fully plasticized moment. (ii) The effects of initial imperfections on the moment resistance are significant for intermediate and long spans. Although the initial imperfection taken in the present study is 4.0 mm, that is within the allowable limit specified in the design standards (i.e., not greater than L/1000), the moment resistances with the taken imperfection are considerably smaller than the design moments specified in the design standards, and (iii) When considering steel beams with the effects of initial imperfection and residual stresses, the moment resistances based on the CSA S16 and EC3-6.3.2.3 solutions are higher, while those based on EC3-6.3.2.2 solution are lower than the moment capacities of the beams with the initial imperfection. This indicates that EC3-6.3.2.2 clause is the most safety design for the moment resistances

Managing marketing strategies at Tesla, Inc in 2023

Tesla, Inc (Tesla, for short) was experiencing one of the most challenging periods in its entire 20-year history. The stock (TSLA) fell off a cliff, having lost approximately 69% of its year-to-date value on the 30th of December 2022. Despite the effort from CEO Elon Musk and the whole company, Tesla missed its targets, selling fewer cars than expected in 2022. Tesla and CEO Elon Musk must urgently re-consider its marketing strategy to meet its long-term target of delivering 20 million cars annually by 2030

European super league and Manchester United FC in 2022

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COMPUTER INTERACTIVE TEACHING TECHNOLOGY FOR ELECTRONICS ENGINEERING UNIVERSITY.

Virtual reality technology currently tends to develop and apply strongly in all areas of social life. Therefore, the application of virtual reality technology in education and training is becoming more and more urgent. If we know how to effectively exploit and apply virtual reality technology to the design of the education and training process, the teaching of teachers and the acquisition of learners' knowledge will become easy, born dynamic. However, in order to achieve high efficiency, it is necessary to have a creative, flexible and appropriate application based on the actual conditions of each field, each school, the learning ability of learners, the ability to use using modern teaching facilities of teachers, specific subject