Abstract:LED lighting fixtures are widely used in various fields due to their advantages of energy efficiency,environmental friendliness,and long lifespan.However,during vacuum-thermal tests in space environment simulators,LED fixtures failed to ignite under vacuum(＜1 × 10-3 Pa)and low-temperature(-196 ℃)conditions.Research revealed that at startup,the junction temperature of the LED was only around 100 K,causing a significant increase in forward voltage,which hindered the ignition of the lamp.To address this issue,this study performed thermal design on the LED fixtures and improved the lighting system's startup circuit,successfully achieving illumination under vacuum and low-temperature conditions.This LED lighting system has been applied in a certain model of vacuum-thermal test in China,effectively expanding the application range of LED light sources and providing reliable lighting support for space environment simulators.

Abstract:A dose-response analysis was conducted on the sterilization performance of low-pressure mercury lamps in low-temperature environments.Escherichia coli,Staphylococcus aureus,and Bacillus subtilis spores were selected as representative strains.Within the temperature range of 20℃ to-20℃,the sterilization effect was explored by varying the ultraviolet dose.The experimental results show that low-pressure mercury lamps exhibit highly efficient disinfection capability at low temperatures,requiring lower doses to inactivate various bacterial strains.For example,at-20℃,Staphylococcus aureus achieved qualified sterilization(log reduction factor RF＞3)with only 10 mJ/cm2 after 30 min of treatment,whereas more than 20 mJ/cm2 was required at room temperature.Simulation-based optimization of ultraviolet lamp arrangement in refrigeration devices,followed by experimental verification,confirmed that the system meets the high-efficiency disinfection requirements under low-temperature conditions.

Abstract:With the promotion of the concept of healthy lighting and the clarification of the mechanisms of photobiological effects,factors such as illuminance,spectral power distribution(SPD),timing of light exposure,duration,prior light history,as well as light direction,age,and visual field,all influence human circadian rhythms and physical and mental health.To quantify the effects of light on circadian rhythms,various mathematical models for evaluating photobiological circadian effects have been proposed,including the Circadian Stimulus(CS)model,Melanopic Equivalent Illuminance(EML)model,Equivalent Daylight Illuminance(EDI),and Daily Cumulative Light Action(DCLA)model.Meanwhile,metrics that characterize the non-visual effects of light have been continuously developed,such as the circadian action factor(acv),biological rhythm factors C/P and B/P,melanopic ratio M/P,α-opic effective irradiance(α-opic ELR),and the Circadian Action Factor(CAF).By analyzing the evolution,advantages,and limitations of mainstream circadian lighting models and photobiological circadian factors,this review summarizes the current state and development trends in circadian lighting.Future circadian lighting models and evaluation indicators are expected to become more refined and systematic,providing a solid theoretical foundation for the practical application of healthy lighting.

Abstract:This article takes the lighting planning and design of Guangzhou Science and Technology Education City as an example to explore how,under the context of urban-campus integration,light can be used to define spatial boundaries,guide sightlines,and express emotions,thereby creating"restrictive"or"open"nighttime campus environments.It also refines a set of indicators for nightscape lighting,providing a reference framework for future nighttime lighting development in university towns.

Abstract:In response to the issue of shortened service life of near-ultraviolet LEDs caused by light degradation of encapsulation materials and heat accumulation during long-term use,three types of LEDs with a peak wavelength of 360 nm were selected.By combining solder joint temperature analysis with degradation mechanism methods,a comparative study was conducted on the reliability differences between semi-inorganic encapsulation(quartz-silicone)and fully inorganic encapsulation(ceramic-metal),as well as between domestic and imported products.The experimental results provide data support for encapsulation process optimization and lifetime prediction.

Abstract:During museum visits,luminance changes caused by spatial transitions can easily lead to both physiological and psychological fatigue in visitors.To explore the optimal luminance configuration across different museum spaces,this study selected a typical visiting route—outdoor to lobby,foyer,and exhibition hall-and simulated five sets of lighting environments with varying luminance levels across spatial transitions.A subjective evaluation experiment was conducted to assess satisfaction with these lighting conditions.The results revealed a clear preference pattern:higher luminance environments generally received higher subjective evaluation scores.However,excessive luminance differences between adjacent spaces significantly reduced comfort ratings,with some visitors even reporting strong discomfort.Based on the experimental findings,this study proposed appropriate spatial luminance contrast ratios to ensure visual comfort during the visiting process,and provided adaptive design recommendations for museums from a lighting environment perspective.

Abstract:Plant lighting,as a key technology for modern high-efficiency agriculture,faces major constraints in industrial application due to the spectral adaptability and economic cost of its light sources.This paper systematically compares fluorescent-converted LEDs(pc-LEDs)and pure red-blue LEDs in terms of light quality,photosynthetic photon efficacy,energy consumption,and cost characteristics in plant lighting,and reviews the research progress on Mn4+-activated oxide red phosphors.The study shows that although pc-LEDs have lower photosynthetic photon efficiency than pure red-blue LEDs,their broad-spectrum,multi-peak emission characteristics may enhance crop yield.However,in the long term,pc-LEDs exhibit higher energy consumption and maintenance costs,making their overall cost still higher than that of pure red-blue LEDs.Mn4+-activated oxide phosphors,as a key material for pc-LEDs in plant lighting,have been extensively studied.Research indicates that some phosphors(e.g.,BaLaMgSbO6:Mn4+,CaAl12O19-CaAl4O7-MgAl2O4:Mn4+)achieve internal quantum efficiencies exceeding 80％,with excellent thermal stability and spectral adaptability.Future work should focus on optimizing crystal field design and ion co-doping to promote the large-scale application of low-cost,thermally stable Mn4+-based phosphors,thereby advancing innovations in agricultural lighting technology.

Abstract:Smart poles integrate multiple functions such as lighting,communications,surveillance,energy,and environmental monitoring,continuously generating massive,multi-dimensional,real-time data covering sectors including energy,communications,security,transportation,and environmental protection.Through processes such as"resource integration,productization,and assetization,"this data can be formalized as recognized assets,evaluated,and accounted for.By aligning with practical needs and leveraging key data such as location,energy consumption,operations,and video,value-driven applications and scenario development can be implemented,thereby enhancing the value of these data assets.

Abstract:With the rapid development of automotive intelligence technologies,ambient lighting in smart cockpits has emerged as a highly regarded functional feature.This study aims to investigate the impact of ambient light color in intelligent cockpits on the emotions of drivers and passengers,as well as potential individual differences.Using a driving-scenario-adapted emotion wheel and Spearman correlation analysis,the relationship between colors and emotions was examined.Experimental results indicate that colors such as red,green,and blue show strong associations with emotions,while pink,purple,and bluish-purple exhibit relatively weaker emotional correlations.Specific colors can effectively elicit or mitigate particular emotional responses-for example,green promotes positive emotions,whereas red stimulates excitement.Based on these findings and analysis of driving scenarios,preliminary recommendations are proposed for selecting ambient light colors to regulate emotions under different driving conditions.The results of this study provide valuable insights for automotive manufacturers and designers,contributing to the creation of smarter and more human-centered cockpit lighting environments.

Abstract:With urban nightscape lighting evolving from purely functional requirements toward integrated demands encompassing aesthetics,culture,and ecology,constructing a visually high-quality and sustainable lighting environment has become a key challenge.This study takes the Jinji Lake Right Bank Art Plaza in Suzhou as a practical case to propose a method for enhancing the aesthetic value of urban nightscapes through lighting design.By employing layered lighting techniques,dynamic color-temperature control with 18-step adjustments,and digital design tools,combined with low-level lighting design and low-carbon technologies,the project achieves a nighttime atmosphere characterized as"romantic,elegant,and leisurely."Post-implementation surveys indicate a significant increase in visitor dwell time and enhanced night-time economic activity,demonstrating the effectiveness of integrating aesthetics with technology.The research provides a reference paradigm for urban public space nightscape design that balances artistic value with ecological benefits,while also outlining future directions for city nightscape lighting.

Abstract:Nighttime lighting in modern office buildings plays a crucial role in shaping architectural identity,enhancing work environment quality,and creating a comfortable atmosphere.This study takes the lighting design of buildings surrounding the Southeast Plaza in the West Gate area of Peking University's urban renewal project as an example,illustrating the expression methods of modern office building nighttime lighting.The study also considers daytime effects by integrating hidden lighting fixtures within architectural decorative structures.Through analysis of relevant cases,technical solutions,and comparative practice examples,the project demonstrates the improved quality and visual effects of both building lighting and the surrounding environment.

Abstract:This study investigated a proof-of-concept wavelength division multiplexing(WDM)ultra-high-speed underwater visible light communication(UVLC)system based on two commercial LEDs and five custom-designed micro-LEDs.By employing pre-equalization and orthogonal frequency-division multiplexing modulation techniques,an aggregate communication rate of 28.82 Gbps was achieved in a 0.6 m underwater environment.This represents a record-breaking transmission speed for micro-LED-based UVLC,a 43％increase over the previous highest record of 20.09 Gbps.Compared to a single-channel 455 nm micro-LED(7.23 Gbps),the system achieved a fourfold capacity gain.In addition,this study analyzed the modulation bandwidth and optical power characteristics of each wavelength source,and simulated extended-distance transmission using 63％and 40％neutral density filters.The WDM-UVLC system with a 63％filter achieved an aggregate data rate of 18.35 Gbps,with the shortest estimated transmission distance of 1.81 m for the 650 nm wavelength channel.Using a 40％filter,the WDM-UVLC achieved a total communication rate of 15.36 Gbps,with a shortest estimated transmission distance of 2.75 m,while blue-green wavelengths with lower attenuation in water exceeded an estimated 8 m transmission distance.Notably,for the 455 nm channel,a signal-to-noise ratio(SNR)reduction of only 5 dB was sufficient to maintain a bit error rate(BER)below 3.8 × 10-3,demonstrating the robustness and potential of the system under power fluctuations.This research not only validates the potential of wavelength division multiplexing combined with micro-LEDs for high-speed underwater communication but also highlights multi-color micro-LEDs as ideal candidates for WDM-UVLC transmitters.With appropriate optical filtering and design,more integrated WDM systems can be realized in the future.

Abstract:In response to the multiple reflow failure issues of SnCu0.7 solder joints in flip-chip LED packaging,this study employed X-ray tomography,SEM-EDS analysis,and push-pull strength testing to reveal the thermal cycling failure mechanisms.The experimental results show that:after a single reflow,a(Ni,Cu)3Sn4 layer with a thickness difference of 3.2 μm forms on the chip/pad side;subsequent(Cu,Ni)6Sn5 phase transformation occurs on the pad side,while the growth rate on the chip side slows down.The interfacial fracture mode shifts from ductile to brittle,and the shear strength decreases to 52.4 MPa.The void ratio increases to 18.5％,with the maximum single-pore area fraction reaching 4.7％,leading to junction temperature rise.Thermal accumulation effects cause a reduction in refractive index,resulting in 1.8％luminous flux loss and 3.55％photoelectric efficiency degradation.The study indicates that uneven IMC growth,void aggregation,and thermal dissipation failure form a vicious cycle,providing a quantitative basis for the microstructure-performance correlation in high-density flip-chip packaging processes.

Abstract:Day-night light exposure levels are closely related to individual physical and mental health.Due to their relatively free behavior patterns,university students show large individual differences in the level and timing of light exposure.In this study,60 university students were recruited from South China Normal University.Using the ecological momentary assessment(EMA)method,continuous light exposure data were collected for one week,while psychological alertness,emotional states at different daytime periods,and nighttime sleep were also measured.The aim was to examine the impact of different daytime light exposure patterns on students' sleep and psychological functioning.Based on daytime light exposure measurements,two typical patterns emerged:the"M-shaped"type and the"flat-line"type.Statistical analysis showed that the M-shaped type had lower average light intensity during both daytime and nighttime compared to the flat-line type,and in both patterns,participants' daytime light exposure remained at a relatively low level.Moreover,the M-shaped pattern displayed larger fluctuations in light exposure,with lower exposure around 8:00 a.m.and 2:00 p.m.,and higher levels at other times of day.Under this pattern,participants tended to have an earlier circadian rhythm.In contrast,the flat-line pattern maintained a relatively stable level of light exposure throughout the day,and participants under this pattern reported higher sustained alertness,greater work efficiency,and fewer negative emotions,though with a delayed circadian phase.

Abstract:AlGaN based far-ultraviolet(FUV)LEDs with emission wavelength shorter than 250 nm have significant application potential in fields like safe sterilization and sterilization,non-invasive phototherapy,and environmental monitoring,and in recent years they have gradually become a new research hotspot in the ultraviolet LED field.This paper introduces recent advances at home and abroad in improving the luminous efficiency of AlGaN-based FUV LEDs,and provides a comprehensive analysis of the research and development challenges and technical solutions from the perspectives of epitaxial material growth,n/p-type doping efficiency,quantum structure design,light extraction efficiency and reliability.

Abstract:In the context of human-machine-environment interaction,adjusting the brightness of mobile phone screens based on ambient light levels has become an important means of enhancing visual comfort for users and improving the architectural lighting environment.However,current research focuses on ambient illuminance,ignoring the role of ambient luminance in the user's perception of the target object.At the same time,existing brightness perception models are mostly limited to a specific brightness range in the visual field,without considering the brightness distribution characteristics in the visual field and the perceptual characteristics of brightness in the surrounding visual field,which leads to the inability to accurately adjust the brightness of the mobile phone screen in complex environments,thus reducing the user's visual comfort.Therefore,this study starts from the ambient brightness and the visual area in the field of view and investigates the differences in the user's perception of brightness in different areas of the field of view.The study shows that the user's perceived sensitivity to the background luminance of the visual field decreases significantly with increasing eccentricity,and that the position factor has a greater effect on luminance perception than the orientation factor.This study aims to provide basic data and luminance partitioning methods for studying the influence mechanism of complex visual field background luminance on mobile phone screen luminance by constructing a model of visual field background luminance perception sensitivity,in order to promote the harmonious development of human-machine and built environment.

Abstract:In order to improve driver safety while driving in tunnels,the virtual simulation experiments was used to analyze eye movement characteristics-such as gaze point trajectories-of participants driving through tunnels equipped with red,yellow and blue chevron-shaped guiding signs respectively.Additionally,a questionnaire survey was carried out with the participants.The results showed that:participants demonstrated the highest level of attention when driving in tunnel environments with blue markings on the sidewalls,while red marking led to the most dispersed attention.Pupil size variation was most stable in tunnels with blue markings,whereas the yellow markings resulted in the greatest fluctuation in pupil area.Participants expressed the highest preference and visual comfort for the blue markings.However,red markings were found to enhance driver's alertness more effectively.Considering both the eye-tracking characteristics and subjective evaluations of participants during the simulated driving experiment,it was found that the most suitable design for chevron-shaped guidance markings in highway tunnels is a white arrow on a blue background.

Abstract:Smart and effective regulation of shading blinds can adapt to dynamic light environments and continuously create a visually comfortable lighting environment.However,existing control systems often suffer from unclear mechanisms regarding visualcomfort indicators and lack sufficient capabilities in dynamic prediction and smart decision-making.This research integrates machine learning techniques with the dynamic programming algorithm from reinforcement learning to develop a dynamic indoor lighting environment prediction model and an intelligent agent.This approach addresses the limitations of nonlinear fitting in dynamic prediction and the lack of precision in regulation,thereby enabling effective control of intelligent shading blinds with improved visual comfort performance.

Abstract:Urban parks serve as essential spaces for recreation and leisure.However,with the rapid development of nightscape lighting in these parks,issues related to ecological sustainability have gradually emerged,resulting in some parks failing to adequately consider ecological impacts in their lighting design.Light pollution can have adverse effects on plants,animals,the night sky,and human well-being.This study takes Shanghai Expo Culture Park as a case to explore how nightscape lighting design can be carried out with respect for the natural ecological environment.By integrating the park's landscape features and nighttime usage patterns,the design incorporates the cultural identity of the Expo,utilizes eco-friendly lighting technologies and intelligent lighting controls,and aims to create a high-quality,ecologically friendly nighttime lighting environment in urban parks.The findings provide a valuable reference for future urban park landscape lighting projects.

Abstract:Currently,light and shadow art festivals have evolved beyond mere artistic displays to become a nexus connecting policy direction,technological innovation,and public demand.During the critical phase of the 14th Five-Year Plan's transition toward high-quality development,the night-time cultural and tourism economy has become a vital strategic pillar for fostering new consumption momentum,revitalizing urban vitality,and enhancing cultural soft power.Taking the Second Beijing Chaoyang International Light Festival(Chaoyang Park Section)as a practical case study,this paper systematically explores the entire process of planning,designing,and creating scenes for a modern digital light and shadow art festival from the perspective of a lighting designer.Through detailed analysis of preliminary research,establishment of design principles,circulation planning,zoning layout,scene construction,customized product development,multi-disciplinary collaboration,effect testing,and green design practices,the paper presents a comprehensive overview of the planning and implementation process.It offers a reusable strategy framework for empowering urban cultural tourism through digital light and shadow art.As a participant in the planning of the light festival,this paper reflects on the entire process of the project's development from a first-person perspective,summarizing the design principles of modern light art festivals.Through practical implementation and verification,the study proposes a reusable strategy framework for empowering urban cultural tourism with digital light and shadow art.