All-inorganic reflective phosphor-in-glass film(PiGF) converter has garnered widespread attentions for high brightness laser-driven white lighting,while its poor color quality and low luminescence stability have been ...All-inorganic reflective phosphor-in-glass film(PiGF) converter has garnered widespread attentions for high brightness laser-driven white lighting,while its poor color quality and low luminescence stability have been inevitable roadblocks.Herein,the bicolor PiGF containing green-emitting Y3Al3.08Ga1.92O12:Ce3+(YAGG) and red-emitting CaAlSiN_(3):Eu^(2+)(CASN) phosphors bonded on Al2O3substrate was prepared for enabling high color quality laser-driven white lighting in reflective configuration.The bicolor PiGF has high quantum efficiency and good structure stability.By optimizing the CASN content,PiGF thickness and Al_(2)O_(3) content,the reflective bicolor PiGF based white laser diode(LD)displays good luminescence performance with a luminous flux of 451.5 lm and a luminous efficacy of142.3 lm/W and high color quality with a color rendering index(CRI) of 85.3 and a correlated color temperature(CCT) of 5177 K under the incident laser power of 3.15 W,and still has excellent luminescence and color stabilities(CRI and CCT) under the continuous laser excitation of 5.61 W,attributed to the good thermal conductivity and high reflectivity of Al_(2)O_(3) substrate and scattering enhancement effect of Al_(2)O_(3) particles.It can be foreseen that the reflective bicolor PiGF converter provides a promising strategy for enabling high quality laser-driven white lighting.展开更多
To date,most current reports on the development and optimization of artificial lighting sources have focused on the energy performance levels and limited color qualities of white light-emitting diodes(LEDs).However,th...To date,most current reports on the development and optimization of artificial lighting sources have focused on the energy performance levels and limited color qualities of white light-emitting diodes(LEDs).However,these properties are insufficient in terms of representing all performance levels required when adjusting white LEDs for healthy and smart lighting.Here,we introduce essential and advanced figures of merit pertaining to circadian performance as well as vision performance and color quality.We compare all possible properties of commercialized artificial lighting,daylight and four-package white LEDs which consist of long-wavelength pass dichroic filter(LPDF)-capped,phosphor-converted red,amber and green LEDs(pc-LEDs)and a blue LED.We show that these tunable four-package white LEDs produce a tunable circadian effect for melatonin suppression/secretion,a high color quality for color perception/reproduction,high efficiency for energy savings and tunable figures of merit for the smart LED lighting market.展开更多
The production of colored flames is the primary purpose of military signaling, projectile tracing, and illuminating devices. Certain elements and compounds when heated to high temperature have the unique property of e...The production of colored flames is the primary purpose of military signaling, projectile tracing, and illuminating devices. Certain elements and compounds when heated to high temperature have the unique property of emitting lines or narrow bands in the visible region(380-780 nm). This study, reports on the development of novel yellow colored flame compositions with enhanced spectral performance in terms of luminous intensity, and color quality to standard Russian yellow tracer. The light intensity and the imprint spectra of developed yellow flares were measured using digital luxmeter and UV e Vis. spectrometer respectively. The main giving of this study is that the light intensity, and color quality of Russian yellow tracer were improved by 287%, and 170% respectively. This was accomplished by means of optimizing the ratio of novel binder to color source using aluminum metal fuel. Aluminumbased formulations were found to maximize the formation of yellow reactive emitting specimens, and to eliminate any interfering incandescent emission resulted from Mg O. Quantification of yellow color emitting specimens in the combustion gaseous products was achieved using chemical equilibrium thermodynamic code named ICT(Institute of Chemical Technology in Germany, Virgin 2008); in an attempt to judge the light quality. This improvement in yellow flare performance established the rule that the emission intensity increases as the reaction temperature increases. In the meantime upper limit of temperature was avoided to maximize the color quality.展开更多
Cognitive radio(CR) is a promising solution to improve the spectrum utilization.The cognitive radio networks includes the primary user(PU) system with authorized spectrum and the secondly user(SU) system without autho...Cognitive radio(CR) is a promising solution to improve the spectrum utilization.The cognitive radio networks includes the primary user(PU) system with authorized spectrum and the secondly user(SU) system without authorized spectrum. When the SUs want to use the spectrum, they have to find the idle channels that are not occupied by the PUs. So the QoS of the SUs will be affected not only by the characteristic of their own business, but also by the behavior of the PUs.Currently, in order to ensure the quality of the SU services, the M-LDWF algorithm is widely used in scheduling. However, the M-LWDF algorithm didn't fully consider the difference among the SUs. For those SUs who are in the process of communication but have to change channel due to the return of the PU, they should have higher scheduling priority. In this paper, we put forward an improved algorithm based on M-LWDF. In order to guarantee the QoS of the SUs those were in the processing of communication, we gave the higher scheduling priority. Simulation results show that the improved algorithm can effectively decrease the dropping rate and improve the QoS of the SUs and the performance of the whole system.展开更多
This paper proposes a negotiation-based TDMA scheme for ad hoc networks, which was modeled as an asynchronous myopic repeated game. Compared to the traditional centralized TDMA schemes, our scheme operates in a decent...This paper proposes a negotiation-based TDMA scheme for ad hoc networks, which was modeled as an asynchronous myopic repeated game. Compared to the traditional centralized TDMA schemes, our scheme operates in a decentralized manner and is scalable to topology changes. Simulation results show that, with respect to the coloring quality, the performance of our scheme is close to that of the classical centralized algorithms with much lower complexity.展开更多
Multi-color phosphor-in-glass(PiG)film has been considered as a promising color converter in high-quality laser lighting owing to its outstanding merits of phosphor versatility,tunable luminescence,and simple preparat...Multi-color phosphor-in-glass(PiG)film has been considered as a promising color converter in high-quality laser lighting owing to its outstanding merits of phosphor versatility,tunable luminescence,and simple preparation.However,the opto-thermal properties of PiG film are severely affected by the photon reabsorption and backward scattering of phosphor structure and the heat conduction of substrate.Herein,a unique sandwich design of phosphor structure was introduced in the multi-color PiG film for high-quality laser lighting.By elaborately synthesizing the borosilicate glass with low glass transition temperature(T_(g)),similar expansion coefficient,and high refractive index(RI),the sandwiched PiGs were prepared by sintering(~600℃)broadband green and red phosphor glass films on the double sides of sapphire.The green and red PiG films were tightly coated on the sapphire with no delamination and maintained higher luminescence intensity than raw phosphors at high temperatures.By simultaneously coupling photon reabsorption and backward scattering,the sandwiched green PiG film-sapphire-red PiG film(G-S-R PiG)yields a high-quality white light with a high luminous efficacy of 163 lm/W and an excellent color rendering index(CRI)of 85.4 under a laser power of 2.4 W,which are the best comprehensive results yet reported.Benefiting from the ingenious sandwich design with heat-conducting sapphire and thin PiG films,the G-S-R PiG displays low working temperatures(<200℃)under high-power laser excitation.This work reveals the role of sandwiched phosphor structure in photon loss and heat dissipation,which provides a new strategy to design PiG films for high-quality laser lighting.展开更多
基金Project supported by the Science and Technology Project of Shenzhen City (JSGG20210802154213040)the Guangdong Basic and Applied Basic Research Foundation (2024A1515010001)the Shenzhen Postdoctoral Research Funding Project。
文摘All-inorganic reflective phosphor-in-glass film(PiGF) converter has garnered widespread attentions for high brightness laser-driven white lighting,while its poor color quality and low luminescence stability have been inevitable roadblocks.Herein,the bicolor PiGF containing green-emitting Y3Al3.08Ga1.92O12:Ce3+(YAGG) and red-emitting CaAlSiN_(3):Eu^(2+)(CASN) phosphors bonded on Al2O3substrate was prepared for enabling high color quality laser-driven white lighting in reflective configuration.The bicolor PiGF has high quantum efficiency and good structure stability.By optimizing the CASN content,PiGF thickness and Al_(2)O_(3) content,the reflective bicolor PiGF based white laser diode(LD)displays good luminescence performance with a luminous flux of 451.5 lm and a luminous efficacy of142.3 lm/W and high color quality with a color rendering index(CRI) of 85.3 and a correlated color temperature(CCT) of 5177 K under the incident laser power of 3.15 W,and still has excellent luminescence and color stabilities(CRI and CCT) under the continuous laser excitation of 5.61 W,attributed to the good thermal conductivity and high reflectivity of Al_(2)O_(3) substrate and scattering enhancement effect of Al_(2)O_(3) particles.It can be foreseen that the reflective bicolor PiGF converter provides a promising strategy for enabling high quality laser-driven white lighting.
基金This work was supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIP)(No.2011-0017449).
文摘To date,most current reports on the development and optimization of artificial lighting sources have focused on the energy performance levels and limited color qualities of white light-emitting diodes(LEDs).However,these properties are insufficient in terms of representing all performance levels required when adjusting white LEDs for healthy and smart lighting.Here,we introduce essential and advanced figures of merit pertaining to circadian performance as well as vision performance and color quality.We compare all possible properties of commercialized artificial lighting,daylight and four-package white LEDs which consist of long-wavelength pass dichroic filter(LPDF)-capped,phosphor-converted red,amber and green LEDs(pc-LEDs)and a blue LED.We show that these tunable four-package white LEDs produce a tunable circadian effect for melatonin suppression/secretion,a high color quality for color perception/reproduction,high efficiency for energy savings and tunable figures of merit for the smart LED lighting market.
基金funding the research project entitled“Enhanced Visible Tracers for Illumination and Tracking”
文摘The production of colored flames is the primary purpose of military signaling, projectile tracing, and illuminating devices. Certain elements and compounds when heated to high temperature have the unique property of emitting lines or narrow bands in the visible region(380-780 nm). This study, reports on the development of novel yellow colored flame compositions with enhanced spectral performance in terms of luminous intensity, and color quality to standard Russian yellow tracer. The light intensity and the imprint spectra of developed yellow flares were measured using digital luxmeter and UV e Vis. spectrometer respectively. The main giving of this study is that the light intensity, and color quality of Russian yellow tracer were improved by 287%, and 170% respectively. This was accomplished by means of optimizing the ratio of novel binder to color source using aluminum metal fuel. Aluminumbased formulations were found to maximize the formation of yellow reactive emitting specimens, and to eliminate any interfering incandescent emission resulted from Mg O. Quantification of yellow color emitting specimens in the combustion gaseous products was achieved using chemical equilibrium thermodynamic code named ICT(Institute of Chemical Technology in Germany, Virgin 2008); in an attempt to judge the light quality. This improvement in yellow flare performance established the rule that the emission intensity increases as the reaction temperature increases. In the meantime upper limit of temperature was avoided to maximize the color quality.
基金supported by Beijing Key Laboratory of Work Safety Intelligent Monitoring (Beijing University of Posts and Telecommunications)
文摘Cognitive radio(CR) is a promising solution to improve the spectrum utilization.The cognitive radio networks includes the primary user(PU) system with authorized spectrum and the secondly user(SU) system without authorized spectrum. When the SUs want to use the spectrum, they have to find the idle channels that are not occupied by the PUs. So the QoS of the SUs will be affected not only by the characteristic of their own business, but also by the behavior of the PUs.Currently, in order to ensure the quality of the SU services, the M-LDWF algorithm is widely used in scheduling. However, the M-LWDF algorithm didn't fully consider the difference among the SUs. For those SUs who are in the process of communication but have to change channel due to the return of the PU, they should have higher scheduling priority. In this paper, we put forward an improved algorithm based on M-LWDF. In order to guarantee the QoS of the SUs those were in the processing of communication, we gave the higher scheduling priority. Simulation results show that the improved algorithm can effectively decrease the dropping rate and improve the QoS of the SUs and the performance of the whole system.
基金supported in part by National Science Fund for Distinguished Young Scholars under Grant No.60725105National Key Basic Research Program of China ( 973 Program ) under Grant No.2009CB320404+2 种基金Program for Changjiang Scholars and Innovative Research Team in University under Grant No.IRT0852National Natural Science Foundation of China under Grants No.60972047, 61072068111 Project under Grant No.B08038
文摘This paper proposes a negotiation-based TDMA scheme for ad hoc networks, which was modeled as an asynchronous myopic repeated game. Compared to the traditional centralized TDMA schemes, our scheme operates in a decentralized manner and is scalable to topology changes. Simulation results show that, with respect to the coloring quality, the performance of our scheme is close to that of the classical centralized algorithms with much lower complexity.
基金financially supported by the National Natural Science Foundation of China(51805196 and 51775219)Key Research and Development Program of Hubei Province(2021BAA213 and 2020BAB068)China Postdoctoral Science Foundation(2021M701308).
文摘Multi-color phosphor-in-glass(PiG)film has been considered as a promising color converter in high-quality laser lighting owing to its outstanding merits of phosphor versatility,tunable luminescence,and simple preparation.However,the opto-thermal properties of PiG film are severely affected by the photon reabsorption and backward scattering of phosphor structure and the heat conduction of substrate.Herein,a unique sandwich design of phosphor structure was introduced in the multi-color PiG film for high-quality laser lighting.By elaborately synthesizing the borosilicate glass with low glass transition temperature(T_(g)),similar expansion coefficient,and high refractive index(RI),the sandwiched PiGs were prepared by sintering(~600℃)broadband green and red phosphor glass films on the double sides of sapphire.The green and red PiG films were tightly coated on the sapphire with no delamination and maintained higher luminescence intensity than raw phosphors at high temperatures.By simultaneously coupling photon reabsorption and backward scattering,the sandwiched green PiG film-sapphire-red PiG film(G-S-R PiG)yields a high-quality white light with a high luminous efficacy of 163 lm/W and an excellent color rendering index(CRI)of 85.4 under a laser power of 2.4 W,which are the best comprehensive results yet reported.Benefiting from the ingenious sandwich design with heat-conducting sapphire and thin PiG films,the G-S-R PiG displays low working temperatures(<200℃)under high-power laser excitation.This work reveals the role of sandwiched phosphor structure in photon loss and heat dissipation,which provides a new strategy to design PiG films for high-quality laser lighting.
