Y2O3:Eu3+ concentration and particle size: their impacts on color rendering index and lumen of multi-chip white diodes

Aiming at achieving higher colour standard for multi-chip white light-emitting diode (MCW-LEDs) through the enhancement of their color rendering index (CRI), this article worked on and proposed a novel MCW-LED package using a compound of red phosphor Y2O3:Eu3+. The red phosphors were synthesized and applied to build both protective coating and in-cup phosphor configurations. The CRI of MCW-LED which has high correlated colour heat of 8,500 K was observed to be heightened to 86. Moreover, the scattering of the light when added the red phosphor Y2O3:Eu3+ is demonstrated using Mie-scattering theory, while the influences of the red-light enhancement is analyzed using the law of Lambert-Beer

Integrating SiO2 nanoparticles to achieve color uniformity and luminous efficiency enhancement for white light emitting diodes

A phosphor structure with SiO2 nanoparticles is proposed to achieve the enhancement in the correlated color temperature (CCT) homogeneity and the luminescence performance for white light-emitting diodes (WLEDs). As SiO2 is integrated into the phosphorus compound, the scattering effect of this material contributes to better blue-light utilization. Thus, this innovative packaging design results in a significant increased lumen efficiency, more than 12%, in comparison with that of conventional dispensing ones. Meanwhile, the angular CCT deviation also decreases considerably, from 522 K to 7 K, between the angles of -70 and 700. Moreover, this reduction leads to the diminishment of yellow ring phenomenon effect. In addition, the measurement of haze demonstrates that there is a strong scattering in the visible spectrum when SiO2 is added into the silicone film. Besides that, when increasing the driving current, SiO2 stabilizes the chromaticity coordinate shift, which is a vital requirement for indoor lighting applications. Furthermore, SiO2 nanoparticles own excellent optical features, cost efficiency, and simple production will probably turn this material into a potential material in advancing the optical performance of WLEDs

Study of LaSiO3Cl:Ce3+,Tb3+ and Ca5B2SiO10:Eu3+ Phosphors for Improving Hue Standard and Illuminating Beam of WLEDs

Remote phosphor arrangements usually have low color quality and superior lumen output to that of conformal phosphor arrangements and in-cup phosphor arrangements. For this reason, many researches are done so that we could enhance the chromatic quality for the remote phosphor arrangements. For this research, we are suggesting the double-layer remote phosphor arrangement to boost the CRI (short for color rendering index) as well as the CQS (short for color quality scale) in WLED devices. Three identical WLED arrangements which have dissimilar chromatic temperature which covers 5600 K, 8500 K will be used in this paper. The initial idea involves placing one sheet of blue phosphor LaSiO3Cl:Ce3+,Tb3+ or one sheet of red phosphor Ca5B2SiO10:Eu3+ over a sheet of yellow phosphor YAG:Ce3+. After that, seek an appropriate concentration of Ca5B2SiO10:Eu3+ so that we could obtain the most desirable chromatic performance. Judging the result, the element Ca5B2SiO10:Eu3+ seem to help improve the CRI and CQS levels. Particularly, the greater the concentration of La2O3:Eu3+ is, the greater level the CRI and the CQS will get, because of the boost in red illumination within the WLED devices. In addition, the blue phosphor layer LaSiO3Cl:Ce3+,Tb3+ helps increase the lumen output. But the decline of the lumen as well as the chromatic performance manifests if the concentration of LaSiO3Cl:Ce3+,Tb3+ and Ca5B2SiO10:Eu3+ is beyond required level. This is demonstrated by utilizing the theory of Mie-scattering as well as the law of Beer–Lambert. This research’s result is important for the augmentation of white light performance in the WLED devices

Application of CaTiO3:Pr3+ Phosphor for Enhancing the Hue Standard of WLEDs with Double-Film Distant Phosphor Structure

Due to its great thermal stability, the WLEDs (short for white-light diodes), which are made of PiG (short for phosphor-in-glass), appear to be an optical source most effective at generating potent white illumination. However, the actual applications they offer are limited by their poor color rendering and color uniformity. To improve the color rendering and uniformity, this study suggested utilizing a configuration involving a PiG-RPL (short for PiG integrated with a lens of phosphor in red). The phosphor YAGG (also known as Y3Al3.08Ga1.92O12:Ce3+) and borosilicate glass powders were printed, then sintered to generate the green PiG, and then using an inverted dispensing approach, we applied the CASN phosphor silicone in red color (also known as CaAlSiN3:Eu2+) to the said PiG. As a result, with a current of 350 mA, the WLEDs made of PiG-RPL exhibit highly remarkable chromatic performance for the CRI (also known as color rendering index) values determined as Ra = 95.6 with R9 = 95.2 and fidelity/gamut values determined as Rf = 92 with Rg = 99.2. The color quality of the PiG-RPL based WLEDs is steady over a wide range of currents, from 100 to 1000 mA. Moreover, PiG-RPL based WLEDs have better color uniformity than typical PiG based WLEDs. The PiG-RPL structure was proposed in this paper to improve the WLEDs’ chromatic generation as well as chromatic homogeneity. We made the PiGRPL via placing a lens of CASN phosphor above a PiG in green color made of YAGG phosphor. For WLEDs, the PiG-RPL provides extremely remarkable chromatic generation. Furthermore, the WLEDs that are made of PiG-RPL have better color uniformity than those made of PiG and PiG-RPP. The PiG-RPL color converters are considered to be promising for high-power WLEDs, offering great color rendering and color uniformity

MEDICAL STUDENTS’ EVALUATION OF AN ENGLISH FOR SPECIFIC PURPOSES COURSEBOOK: A CASE IN VIETNAM

The current study investigates students’ evaluation of the English for Specific Purposes (ESP) coursebook taught at a medical college in the Mekong Delta, Vietnam. After using it for a year, the users, including medical students and their teachers, have given some unofficial feedback on the book. This study provided insightful official information about how its student users perceive the coursebook they were adopting. Data on the evaluations of the ESP coursebook were gained from questionnaires administered to 166 students majoring in nursing and pharmacy in charge of ESP programs. Semi-structured interviews were employed with four students to get more specific apprehension. The results of this study indicated that students were satisfied with the ESP coursebook in terms of the covering of four skills, the presence of vocabulary and grammar, relevant content, understandable social and cultural context, suitability for mix-level students. In addition, participants perceived that communicative skills were not sufficiently presented, examples in grammar were not more interesting, the illustrations were not diverse and enough, and the cover was simple but not appealing. Suggestions regarding the pedagogical implications for the adoption and evaluation of the coursebook were discussed

Can ChatGPT pass the Vietnamese National High School Graduation Examination?

This research article highlights the potential of AI-powered chatbots in education and presents the results of using ChatGPT, a large language model, to complete the Vietnamese National High School Graduation Examination (VNHSGE). The study dataset included 30 essays in the literature test case and 1,700 multiple-choice questions designed for other subjects. The results showed that ChatGPT was able to pass the examination with an average score of 6-7, demonstrating the technology's potential to revolutionize the educational landscape. The analysis of ChatGPT performance revealed its proficiency in a range of subjects, including mathematics, English, physics, chemistry, biology, history, geography, civic education, and literature, which suggests its potential to provide effective support for learners. However, further research is needed to assess ChatGPT performance on more complex exam questions and its potential to support learners in different contexts. As technology continues to evolve and improve, we can expect to see the use of AI tools like ChatGPT become increasingly common in educational settings, ultimately enhancing the educational experience for both students and educators.Comment: 9 pages, 13 figures, 4 table

A Structured SVM Semantic Parser Augmented by Semantic Tagging with Conditional Random Field

PACLIC 19 / Taipei, taiwan / December 1-3, 200