Some remarks on functional dependencies in relational datamodels

The concept of minimal family is introduced. We prove that this family and family of functional dependencies (FDs ) determine each other uniquely. A characterization of this family is presented. We show that there is no polynomial time algorithm finding a minimal family from a given relation scheme. We prove that the time complexity of finding a minimal family from a given relation is exponential in the number of attributes

Investigating the elements influencing the psychological issues of reform school students

Reformatory students are those whose deviant behaviors and habits prevent them from receiving education under normal educational conditions. These students frequently lead a careless, undisciplined lifestyle, being unwilling to work and learn eager to play and demanding. Therefore, when they are admitted to reformatories with severe study and lifestyle requirements, they have great psychological difficulty adjusting to their new environment. Students’ psychological issues in adapting to reformatory learning and living regimes are difficult and psychological deficits make it challenging for students to adapt to reformatory learning and living conditions. In Vietnam, 665 students from reformatory schools were polled to determine the causes of psychological issues. According to the findings, a variety of elements contribute to students’ psychological difficulties. Individual student conditions such as health, awareness, attitudes and actions as well as inappropriate habits, living without goals or aspirations, etc. are on the subjective side of the equation. On the objective side are the students’ conditions, family, education and psychological obstacles brought on by less-than-ideal circumstances which will make it more difficult for community students to adapt. Both the new school and society must pay more attention to reformatory students in order to establish the conditions necessary for successful integration into the new school and ultimate readmission into society for these students

PREMILINARY RESEARCH ON ARSENIC POLLUTION OF SURFACE AND GROUND WATER IN TRA NANG GOLD EXPLOITATION REGION-LAM DONG PROVINCE AND CAO LANH TOWN-DONG THAP PROVINCE

Joint Research on Environmental Science and Technology for the Eart

Factors Affecting Business Performance: Expanding Theoretical Measurements

Purpose: The article aims to expand a scale system of factors that impacts on business performance.   Theoretical framework: The paper based on the empirical data collected from various types of participants, including accountants (for information providing), managers (for decision-making), sales staff (for work), and lecturers (for research) in Vietnam.   Design/methodology/approach: By descriptive and comparative statistical analysis of SPSS 20 software with 124 valid observations, the survey has proposed the scale system of influencing factors (03 groups of external factors, 05 groups of internal factors) and business performance measures (10 financial and 11 non-financial indicators).   Findings: This study points out the different evaluations according to the demographic features of survey subjects on the group of financial indicators. Specifically, the group of accountants (representing information providers) obtains a lower score than the group of information users. Likewise, the post-graduated participants show stricter assessments of financial indicators in comparison to the rest of the group.   Research, Practical & Social implications: These results suggest the scale system for measuring influencing factors toward business performance in enterprises for further research.   Originality/value: The value of the study is providing an expansion of the factors affecting the efficiency of an enterprise and points out a commonly used set of financial performance measurement indicators. Research results provide useful references for research on related issues

Morphodynamic modeling and causes of closure of My A inlet

Morphodynamics and sediment transport of the My A inlet in the low flow season are modeled using Delft3D. The simulation model takes into account the forcing of waves, tides and river flows. Model outputs of sediment transport and morphological changes of allow analysing the mechanism and cause of inlet closure. The analysis shows that longshore sediment is accreted on the northern side of the inlet both on the ebb tidal delta and along the north coast, but onshore sediment transport by wave reworking is the main process to close the inlet

A Robust Mobile Robot Navigation System using Neuro-Fuzzy Kalman Filtering and Optimal Fusion of Behavior-based Fuzzy Controllers

This study proposes a control system model for mobile robots navigating in unknown environments. The proposed model includes a neuro-fuzzy Extended Kalman Filter for localization task and a behaviorbased fuzzy multi-controller navigation module. The neuro-fuzzy EKF, used for estimating the robot’s position from sensor readings, is an enhanced EKF whose noise covariance matrix is progressively adjusted by a fuzzy neural network. The navigation module features a series of independently-executed fuzzy controllers, each deals with a specific navigation sub-task, or behavior, and a multi-objective optimizer to coordinate all behaviors. The membership functions of all fuzzy controllers play the roles of objective functions for the optimizer, which produces an overall Pareto-optimal control signal to drive the robot. A number of simulations and real-world experiments were conducted to evaluate the performance of this model

Applying means-end chain theory and laddering interviews to the study of product attributes for Dalat potatoes

Dalat potato brand has currently been facing unfair competition from wholesalers using Chinese potatoes labeled with Vietnamese brand to disguise their true origin. Accordingly, potatoes from China are first transported to Lam Dong and then covered by Lam Dong soil to cheat consumers. This study, therefore, aims to explore key attributes of Dalat potatoes, and the benefits and values created by these attributes for consumers of Dalat potatoes. In order to address the research objective, the study uses a qualitative approach based on means-end chain theory and laddering interviews to collect and analyze the data. Eventually, the linkage between attributes, consequences and values are established to help governmental authorities of Lam Dong province to develop strategies for promoting Dalat potato brand. The finding shows that ‘High food value’, ‘Trustful product’ and ‘Tasty and greasy taste’ are key attributes of Dalat potatoes. The linkage between potatoes attributes, benefits and values show that consuming good farm produce like Dalat potatoes help consumers enjoy a better life. This is essential for authorities to position and build a more solid brand for this specialty. To conclude, the paper discusses some managerial implications for promoting and branding Dalat potatoes

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