Nonlinear Control of an Active Magnetic Bearing with Output Constraint

In this paper, an appropriate control strategy is proposed to handle the nonlinear dynamics ofan active magnetic bearing (AMB). The goal of the control design is to drive the AMB rotor to the origin with improved transient response. In order to achieve this task, back stepping control technique with a barrier Lyapunov function are employed to keep the tracking error trajectory inside a predefined zone to avoid possible mechanical contact between rotor and stator. Besides, a speed observer is also used since information about rotor speed is not always available. The stability of the closed-loop system is proven. The effectiveness of the proposed control strategy is verified by numerical simulations

Multi-faceted insights of entrepreneurship facing a fast-growing economy: A literature review

This study explores entrepreneurship research in Vietnam, a lower-middle-income country in Southeast Asia that has witnessed rapid economic growth since the 1990s but has nonetheless been absent in the relevant Western-centric literature. Using an exclusively developed software, the study presents a structured dataset on entrepreneurship research in Vietnam from 2008 to 2018, highlighting: low research output, low creativity level, inattention to entrepreneurship theories, and instead, a focus on practical business matters. The scholarship remains limited due to the detachment between the academic and entrepreneur communities. More important are the findings that Vietnamese research on entrepreneurship, still in its infancy, diverges significantly from those in developed and emerging economies in terms of their content and methods. These studies are contextualized to a large extent to reflect the concerns of a developing economy still burdened by the high financial and nonfinancial costs

Applying calcium fluoride and silica particles: A solution to improve color homogeneity of pc-WLEDS

This article focuses on enhancing the lighting efficiency of pc-WLEDs, a new and advanced lighting solution that has received lots of attention. To adapt to the demand of modern lighting, the lighting performance of pc-WLEDs must be improved, especially the color homogeneity and luminous flux, two of the most important quality indicators of pc-WLEDs. Through experiments, this article proposes using the scattering enhancement particles (SEPs) such as CaF2 and SiO2 with yellow phosphor Y3Al5O12:Ce3+ in pc-WLEDs configuration. The pc-WLEDs model is created by using the LightTools program and set at 8500 K correlated color temperature, while the experimental results yielded from this simulation will be verified by Mie-scattering theory. The information from this article reveals the scattering coefficients of SEPs at 455 nm and 595 nm wavelengths. Moreover, it is confirmed that the employment of CaF2 is effective in promoting the color but may damage the luminous efficiency if the concentration is too high while the SEP material, SiO2, exhibits high luminous efficiency at all concentration

FACTORS AFFECTING THE SHARE OF FAKE NEWS ABOUT COVID-19 OUTBREAK ON SOCIAL NETWORKS IN VIETNAM

In recent days in Vietnam, the amount of fake news spreading online about the Covid-19 epidemic has shown signs of increasing, causing information confusion and complicating the situation. This fact has received significant attention from scientists. To supplement the evidence of previous studies, enrich the research literature and make policy recommendations to the Government, this study explores the factors influencing the sharing of fake news on social networks. This study was conducted through a cross-sectional survey using an intentional sampling technique (n = 200) multivariate linear regression analysis technique was applied to prove the hypotheses. Research results show that the factors of altruism, entertainment, socialization, self-promotion, and instant information sharing have a positive and meaningful impact on sharing fake news about Covid_19 on social networks

Improving Bayesian statistics understanding in the age of Big Data with the bayesvl R package

The exponential growth of social data both in volume and complexity has increasingly exposed many of the shortcomings of the conventional frequentist approach to statistics. The scientific community has called for careful usage of the approach and its inference. Meanwhile, the alternative method, Bayesian statistics, still faces considerable barriers toward a more widespread application. The bayesvl R package is an open program, designed for implementing Bayesian modeling and analysis using the Stan language’s no-U-turn (NUTS) sampler. The package combines the ability to construct Bayesian network models using directed acyclic graphs (DAGs), the Markov chain Monte Carlo (MCMC) simulation technique, and the graphic capability of the ggplot2 package. As a result, it can improve the user experience and intuitive understanding when constructing and analyzing Bayesian network models. A case example is offered to illustrate the usefulness of the package for Big Data analytics and cognitive computing

Effect of TiO2_2 anatase nanocrystallite on electrical properties of PPy/TiO2_2 nanocomposite

Polypyrrole/titanium dioxide nanocomposite (PPy/TiO2) was synthesized by in-situ chemical polymerization of pyrrole (Py) monomer in colloidal suspension of TiO2 anatase. TEM images show that TiO2 anatase nanoparticles with size of around 3–4 nm are randomly imbedded on the surface and inside of PPy grain. The random distribution of TiO2 anatase nanoparticle in PPy matrix form variety of p-n contact on the surface and inside of the materials. As expectation, the charge exchange between oxygen and the PPy affect the p-n depletion regions and then modify the electrical properties of PPy. Upon exposure to the open air the conductivity of the PPy/TiO2 nanocomposite exhibits an increase of about 20 folds much larger than that of neat PPy. The enhancement is accounted for the modification of in the surface conductance of PPy/TiO2 nanocomposite as a combination of the TiO2 coupling and oxygen interaction

On how religions could accidentally incite lies and violence: folktales as a cultural transmitter

Folklore has a critical role as a cultural transmitter, all the while being a socially accepted medium for the expressions of culturally contradicting wishes and conducts. In this study of Vietnamese folktales, through the use of Bayesian multilevel modeling and the Markov chain Monte Carlo technique, we offer empirical evidence for how the interplay between religious teachings (Confucianism, Buddhism, and Taoism) and deviant behaviors (lying and violence) could affect a folktale’s outcome. The findings indicate that characters who lie and/or commit violent acts tend to have bad endings, as intuition would dictate, but when they are associated with any of the above Three Teachings, the final endings may vary. Positive outcomes are seen in cases where characters associated with Confucianism lie and characters associated with Buddhism act violently. The results supplement the worldwide literature on discrepancies between folklore and real-life conduct, as well as on the contradictory human behaviors vis-à-vis religious teachings. Overall, the study highlights the complexity of human decision-making, especially beyond the folklore realm

Improving quality of health care for gender-based violence victims at health facilities in Viet Nam

This report presents the results of the May 2009 baseline (pre-intervention) assessment among health care providers (HCPs), and the July 2010 pre- and post-Training of Trainers assessments among HCPs, in Ho Chi Minh City (HCMC) and Da Nang, regarding the issue of quality of care for victims of gender-based violence (GBV) at health facilities in Vietnam. The views of HCPs detailed in this report represent an important foundation for project development and implementation in the study locations. The pre- and post-Training of Trainers questionnaire aimed to assess the HCPs on the topics covered in the training course. The results showed that basic knowledge of hospital staff about GBV improved significantly as an immediate result of training. After the training all the participants were aware of the GBV Laws and related regulations. Many HCPs in Vietnam seek information independently to help them better serve patients who are victims of GBV. Results of this report encourage continuing support of additional training, hospital protocols, and a network of referral agencies

THE IMPACT OF GROUP FACEBOOK USER-GENERATED CONTENT ON CONSUMER PURCHASE INTENTION – A CASE IN TOURISM INDUSTRY

Consulting social networks has become a common practice for tourists when planning their trips. However, there is a relative scarcity of scientific literature on this topic. The purpose of this study is to test the model of predictors of group Facebook user-generated content on tourists' purchase intention. To accomplish this, online surveys were conducted, gathering data from both tourists and individuals planning to travel. The theory of Planned Behavior and Information Acceptance Model were adapted and empirically examined by using Confirmatory Factor Analysis and Structural Equation Modeling. Results and findings reveal significant and meaningful relationships between various factors of Facebook user-generated content and tourists' purchase intention. Additionally, the study offers practical suggestions for hospitality management, administrative teams, and Facebook businesses to effectively leverage user-generated content for attracting online tourists

An open database of productivity in Vietnam's social sciences and humanities for public use

This study presents a description of an open database on scientific output of Vietnamese researchers in social sciences and humanities, one that corrects for the shortcomings in current research publication databases such as data duplication, slow update, and a substantial cost of doing science. Here, using scientists’ self-reports, open online sources and cross-checking with Scopus database, we introduce a manual system and its semi-automated version of the database on the profiles of 657 Vietnamese researchers in social sciences and humanities who have published in Scopus-indexed journals from 2008 to 2018. The final system also records 973 foreign co-authors, 1,289 papers, and 789 affiliations. The data collection method, highly applicable for other sources, could be replicated in other developing countries while its content be used in cross-section, multivariate, and network data analyses. The open database is expected to help Vietnam revamp its research capacity and meet the public demand for greater transparency in science management