Research on Aeroelasticity Phenomenon in Aeronautical Engineering

Aeroelasticity phenomena arise when structural deformations induce changes on aerodynamic forces due to airplane structures that are not completely rigid. The additional aerodynamic forces cause an increase in the structural deformations, which leads to greater aerodynamic forces in a feedback process. These interactions may become smaller until reaching a condition of equilibrium or may diverge catastrophically if resonance occurs. Flutter is an instability aeroelasticity phenomenon which is the most difficult to predict. In this chapter, a numerical method and an experimental method were realized to predict aeroelastic response and characteristic parameters of a wing structure. The numerical method was firstly developed based on the interaction between computational fluid dynamic and computational structural dynamic methods using a coupling system, fluid–solid interaction (FSI), in the ANSYS software. Then, an experiment was set up in suitable conditions to study aeroelasticity characteristics with the goal of comparing the numerical results with the experimental results on the same wing structure at low speed. After that, a developed code based on immersed boundary method (IBM) was realized to predict aeroelasticity response and characteristic parameters of the wing structure. AGARD 445.6 wing model was chosen for this developed procedure at high speed. Obtained results were compared to other numerical and experimental results

Red-emitting Ba2Si5N8Eu2+ conversion phosphor: A new selection for enhancing the optical performance of the in-cup packaging MCW-LEDs

In this research, the influence of the red-emitting Ba2Si5N8Eu2+ convention phosphor on the optical performance of the 7,000K and 7,700K in-cup packaging multi-chip white LEDs (MCW-LEDs) is investigated. The effect of the red-emitting Ba2Si5N8Eu2+ convention phosphor is demonstrated based on Mie Theory by Mat Lab and Light Tools software. The research results indicated that the optical performance of MCW-LEDs was crucially affected by the red-emitting Ba2Si5N8Eu2+ phosphor's concentration. This paper provides an essential recommendation for selecting and developing the phosphor materials for MW-LEDs manufacturing.Web of Science51art. no. 148615

Enhancement of color rendering index for white light LED lamps by red Y2O3:EU3+ phosphor

We present an application of the red Y2O3:Eu3+ dopant phosphor compound for reaching the color rendering index as high as 86. The Multi-Chip White LED lamps (MCW-LEDs) with high Correlated Color Temperatures (CCTs) including 7000 K and 8500 K are employed in this study. Besides, the impacts of the Y2O3:Eu3+ phosphor on the attenuation of light through phosphor layers of the various packages is also demonstrated based on the Beer-Lambert law. Simulation results provide important conclusion for selecting and developing the phosphor materials in MCW-LEDs manufacturing

ViHOS: Hate Speech Spans Detection for Vietnamese

The rise in hateful and offensive language directed at other users is one of the adverse side effects of the increased use of social networking platforms. This could make it difficult for human moderators to review tagged comments filtered by classification systems. To help address this issue, we present the ViHOS (Vietnamese Hate and Offensive Spans) dataset, the first human-annotated corpus containing 26k spans on 11k comments. We also provide definitions of hateful and offensive spans in Vietnamese comments as well as detailed annotation guidelines. Besides, we conduct experiments with various state-of-the-art models. Specifically, XLM-R$_{Large}$ achieved the best F1-scores in Single span detection and All spans detection, while PhoBERT$_{Large}$ obtained the highest in Multiple spans detection. Finally, our error analysis demonstrates the difficulties in detecting specific types of spans in our data for future research. Disclaimer: This paper contains real comments that could be considered profane, offensive, or abusive.Comment: EACL 202

The induction and identification of novel Colistin resistance mutations in Acinetobacter baumannii and their implications.

Acinetobacter baumannii is a significant cause of opportunistic hospital acquired infection and has been identified as an important emerging infection due to its high levels of antimicrobial resistance. Multidrug resistant A. baumannii has risen rapidly in Vietnam, where colistin is becoming the drug of last resort for many infections. In this study we generated spontaneous colistin resistant progeny (up to >256 μg/μl) from four colistin susceptible Vietnamese isolates and one susceptible reference strain (MIC <1.5 μg/μl). Whole genome sequencing was used to identify single nucleotide mutations that could be attributed to the reduced colistin susceptibility. We identified six lpxACD and three pmrB mutations, the majority of which were novel. In addition, we identified further mutations in six A. baumannii genes (vacJ, pldA, ttg2C, pheS and conserved hypothetical protein) that we hypothesise have a role in reduced colistin susceptibility. This study has identified additional mutations that may be associated with colistin resistance through novel resistance mechanisms. Our work further demonstrates how rapidly A. baumannii can generate resistance to a last resort antimicrobial and highlights the need for improved surveillance to identified A. baumannii with an extensive drug resistance profile

Sr2Si5N8:Eu2+ phosphor: a novel recommendation for improving the lighting performance of the 7000 K remote-packaging white LEDs

In the last few years, white LED lamps (WLEDs) have been popularly used in general lighting because of some excellent properties, such as fast response time, environment friendliness, small size, long lifetime, and high efficiency. In this research, we propose a novel recommendation for improving the lighting performance (in terms of the colour rending index, colour quality scale, and luminous efficiency) of the 7000 K remote-packaging WLEDs by adding the red-emitting Sr2Si5N8:Eu2+ phosphor to the yellow-emitting YAG:Ce phosphor compound. In the first stage, we use MATLAB to investigate the light scattering process based on Mie Theory. After that, we use the Light Tool software to simulate and demonstrate this process. Finally, the simulation results are verified with analytical analysis, which clearly shows that the lighting performance of the 7000 K remote-packaging WLEDs significantly depended on the Sr2Si5N8:Eu2+ concentration. The results provided a potential practical solution for manufacturing remote phosphor WLEDs in the near future.Web of Science67434133