Tran Hoang Quang Minh

Y2O3:Eu3+ phosphor: a novel solution for an increase in color rendering index of multi-chip white LED packages

Abstract In this study, a novel compound is synthesized by adding the red-emitting Y2O3:Eu3+ dopant to conformal phosphor package (CPP) or in-cup phosphor package (IPP), to be employed as a component in multi-chip white LEDs lamps (W-LEDs). It was found that this solution can enhance the color rendering index (CRI) of W-LEDs that have correlated color temperatures of 5600 K through 8500 K to more than 86. Besides, the impacts of the Y2O3:Eu3+ phosphor on the attenuation of light through the phosphor layers, CPP and IPP, are also demonstrated based on the Beer–Lambert law and Mie theory. These results provide important information for producing W-LEDs with higher CRI.

Red-emitting α-SrO·3B2O3:Sm2+ phosphor: an innovative application for increasing color quality and luminous flux of remote phosphor white LEDs

Abstract By adding red-emitting α-SrO·3B2O3:Sm2+ phosphor and SiO2 co-doping particles to yellow-emitting YAG:Ce phosphor compound, a novel method for improving lighting performance of white LEDs with remote phosphor structure, which have an average correlated color temperature (CCT) of 5600–8500 K, is proposed and demonstrated. By varying α-SrO·3B2O3:Sm2+ concentration from 2 to 30% and maintaining 5% SiO2, the obtained results indicated that color rendering index (CRI), color quality scale (CQS), and luminous flux can be increased significantly. Moreover, the Mie-scattering theory is employed to verify the scattering properties, which have an effect on the enhancement of color quality and luminous flux. The results prove a prospective practical solution for manufacturing remote phosphor white LED (RP-WLED) having higher color quality and luminous flux.

Technical Efficiency for Selection and Estimation Quality of Distance Relay Protection Setting

Among the relay protections, line distance relay protections have a large proportion. Distance relay protections have some special features compared with the current relay protections. To study and develop technical effect criterion for selection of distance relay protection settings (high-voltage lines) and technical efficiency criterion for estimating this setting is main purpose of this paper. The probability statistical algorithms are used to calculate the above criteria. Finally base on these criteria, search and estimate effective ways to set lines distance relay protection.

Performance Enhancement for Energy Harvesting Based Two-Way Relay Protocols in Wireless Ad-hoc Networks with Partial and Full Relay Selection Methods

Abstract In this paper, we propose two relay selection methods to enhance system outage performance for energy harvesting (EH) based two-way relaying protocols in wireless adhoc networks. In the proposed protocol, two source nodes communicate with each other via the assistance of multiple decode-and-forward (DF) relays using three-phase digital network coding. At the first and second phases, two sources broadcast their data to the relays. Employing a power-splitting model, the relays would harvest energy from radio frequency (RF) signals of the sources to transmit the data at the third phase. We propose a simple partial relay selection (PRS) method and an opportunistic relay selection (ORS) method to enhance the reliability of data transmission at the cooperative phase. For performance evaluation, we derive exact and asymptotic expressions of the system outage probability (SOP) for the proposed protocols over block Rayleigh fading channels. Finally, Monte Carlo simulations are presented to verify the theoretical derivations as well as to compare the performance of the proposed protocols with that of the random relay selection protocol.

Adaptive Energy Harvesting Relaying Protocol for Two-Way Half-Duplex System Network over Rician Fading Channels

We investigate the system performance of a two-way amplify-and-forward (AF) energy harvesting relay network over the Rician fading environment. For details, the delay-limited (DL) and delay-tolerant (DT) transmission modes are proposed and investigated when both energy and information are transferred between the source node and the destination node via a relay node. In the first stage, the analytical expressions of the achievable throughput, ergodic capacity, the outage probability, and symbol error ratio (SER) were proposed, analyzed, and demonstrated. After that, the closed-form expressions for the system performance are studied in connection with all system parameters. Moreover, the analytical results are also demonstrated by Monte Carlo simulation in comparison with the closed-form expressions. Finally, the research results show that the analytical and the simulation results agree well with each other in all system parameters.

Improving Color Uniformity and Color Rending Index of Remote-Phosphor Packaging White Leds by Co-Doping Sio2 And Sr2si5n8:Eu2+ Particles

Abstract Based on some advantageous properties, such as fast response time, environment friendliness, small size, long lifetime, and high efficiency, white LEDs are increasingly used in common illumination applications. In this research, by co-doping of redemitting Sr2Si5N8:Eu2+ phosphor and adding SiO2 particles to yellow-emitting YAG:Ce phosphor compounds, a new approach for improving color uniformity and color rending index of remote-phosphor structure white LEDs is proposed and demonstrated. The obtained results clearly indicate that the color rendering index (CRI) and color uniformity (ΔCCT) significantly depend on Sr2Si5N8:Eu2+ concentration. The results provide a potential practical solution for manufacturing remote-phosphor white LEDs (RP-WLEDs) in the near future.

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

Abstract In this research, the influence of the red-emitting Ba2Si5N8Eu2+ convention phosphor on the optical performance of the 7,000 K and 7,700 K 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.

Novel lighting properties of white LEDs with two-layered remote phosphor package using red-emitting α-SrO·3B2O3:Sm2+ phosphor

Abstract This paper investigates a method for improving the lighting performance of white light-emitting diodes (WLEDs), packaged using two separating remote phosphor layers, yellow-emitting YAG:Ce phosphor layer and red-emitting α-SrO·3B2O3:Sm2+ phosphor layer. The thicknesses of these two layers are 800 μm and 200 μm, respectively. Both of them have been examined at average correlated color temperatures (CCT) of 7700 K and 8500 K. For this two-layer model, the concentration of red phosphor has been varied from 2 % to 30 % in the upper layer, while in the lower layer the yellow phosphor concentration was kept at 15 %. It was found interesting that the lighting properties, such as color rendering index (CRI) and luminous flux, are enhanced significantly, while the color uniformity is maintained at a level relatively close to the level in one-layer configuration (measured at the same correlated color temperature). Besides, the transmitted and reflected light of each phosphor layer have been revised by combining Kubelka-Munk and Mie-Lorenz theories. Through the analysis, it is demonstrated that the packaging configuration of two-layered remote phosphor that contains red-emitting α-SrO·3B2O3:Sm2+ phosphor particles provides a practical solution to general WLEDs lighting.

Improving the Optical Properties of the 8500 K In-cup Packaging WLEDs by Using the Green-emitting CaF 2 :Ce 3+ , Tb 3+ Phosphor

In last few decades, Light emitting diode (LED) with a series of excellence advantages is considered as the next generational light source. In this research, by co-doping the Green-emitting CaF2:Ce3+, Tb3+ phosphor to yellow-emitting YAG:Ce phosphor compound, an innovative approach for improving optical properties of the 8500 K in-cup phosphor packaging white LED lamps (WLEDs) is proposed, investigated, and demonstrated. By using Mie Theory with Mat Lab and Light Tool software, the obtained results show that the optical properties of the 8500 K in-cup phosphor packaging WLEDs is significantly influenced by the Green-emitting CaF2:Ce3+, Tb3+ phosphor’s concentration. From the research results, the correlated color temperature deviation (D-CCT) decreased from 9200 K to 3700 K, and the luminous flux increased from 940 lm. to 1500 lm., respectively. The results indicated that the green-emitting CaF2:Ce3+, Tb3+ phosphor could be considered as a potential solution for manufacturing the in-cup packaging phosphor WLEDs with high CCT shortly.

Increasing the color quality of the 7000K conformal packaging MCW-LEDs by varied red-emitting K2SiF6:Mn4+ conversion phosphor’s size

Abstract Phosphor-converted white light-emitting diodes (pc-WLEDs) are energy efficient and environmentally friendly light sources with a long lifetime, applicable in both display backlights and general lighting. In this research, we investigated the influence of the red-emitting K2SiF6:Mn4+ conversion phosphor on the color quality of the 7000K conformal packaging multi-chip white LEDs (MCW-LEDs). 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 color quality of MCW-LEDs was crucially affected by the red-emitting K2SiF6:Mn4+ conversion phosphor’s size. This research demonstrated a significant recommendation for selecting and developing the phosphor materials for MCW-LEDs manufacturing.