Synthesis,energy transfer mechanism,and tunable emissions of novel Na3La(VO4)2:Re3+ (Re3+ = Dy3+, Eu3+, and Sm3+) vanadate phosphors for near-UV-excited white LEDs

In this study, novel Eu³⁺-, Dy³⁺-, and Sm³⁺-activated Na₃La(VO₄)₂ phosphors were synthesized using a solid state reaction method. X-ray diffraction analysis results indicated that the Na₃La(VO₄)₂ phosphors had an orthorhombic crystal structure with the Pbc21 space group. There were two different La(1)O₈ and La(2)O₈ polyhedra with high asymmetry in the crystal structure. Scanning electron microscopy revealed that the product had a sheet morphology with an irregular particle size. Further, the luminescence properties, including the excitation and emission spectra, and luminescence decay curve, were investigated using a fluorescence spectrometer. The results showed that the Na₃La(VO₄)₂ compound was an excellent host for activating the luminescence of Eu³⁺ (614 nm), Dy³⁺ (575 nm), and Sm³⁺ (647 nm) ions. Further, Dy³⁺/Eu³⁺ co-doped Na₃La(VO₄)₂ phosphors were exploited, and the energy transfer from Dy³⁺ to Eu³⁺ was demonstrated in detail by the photoluminescence excitation, photoluminescence spectra, and luminescent decay curves. The results showed that the energy transfer efficiency from Dy³⁺ to Eu³⁺ was highly efficient, and the energy transfer mechanism was dipole–dipole interactions. Finally, tunable emissions from the yellow region of CIE (0.3925, 0.4243) to the red region of CIE (0.6345, 0.3354) could be realized by rationally controlling the Dy³⁺/Eu³⁺ concentration ratio. These phosphors may be promising materials for the development of solid-state lighting and display systems.     

Lighting preferences in office spaces concerning the indoor thermal environment

The accurate prediction of the visual comfort zone in an indoor environment is difficult as it depends on many parameters. This is especially the case for large compact urban areas in which the density and shadow from neighboring buildings can limit the accessible daylighting in indoor spaces. This paper investigates the satisfaction range for illuminance regarding indoor air temperature in office buildings and the significant parameters affecting this range in six office buildings in Tehran, Iran. Lighting comfort has been evaluated by a subjective survey (509 total responses) and field measurement. The questionnaires were filled out in 146 and 109 rooms in summer and winter, respectively. The results show that the illuminance should not be less than 550 lx, while illuminance between 600 and 650 lx provides the highest satisfaction level. The satisfaction with lighting level is affected by individual parameters such as age, type of activity, and environmental parameters such as window orientation, external obscurations, and season. A relationship was observed between lighting level satisfaction and thermal condition acceptance, and the overall comfort depends more on thermal conditions than the lighting level.     

LED在照明工程中的应用及安装应注意的事项

本文通过工程实际阐述LED光源特点、发展趋势以及LED在照明工程中的应用和LED照明产品在工程安装中应注意的事项。     

广州地铁四号线照明控制系统研究

介绍了广州地铁四号线目前地下车站、高架车站采用的由BAS（楼宇自动化系统）实现的照明控制模式，以及笔者推荐的高架车站采用智能照明控制系统的设计方案，包括其系统构成、功能、接口、控制要求等，并对由BAS实现的照明控制系统和智能照明控制系统进行了比较，总结出采用智能照明控制系统的特点和优越性。     

照明设计——实践与发现：走进照明教育

光与照明是城市与建筑设计中的一个重要方面，而照明教育则担负着专业知识普及和提高的职责，文中介绍了国际照明教育的万法和途径，并指出了目前照明领域的热点问题，最后介绍了同济大学开展照明教学的思路和成果。     

照明质量在工业生产中的重要性与存在的问题

从照明的功能出发,剖析照明质量在工业生产活动中的重要性和工业照明的特点,重点论述了影响工业照明设计与照明质量的各个要素(如应充分满足工艺和工况环境要求,工业照明对照度、显色性、色温、眩光的要求,提高照度稳定性、照明系统的可靠性和安全性的措施等)。经实地考察,发现照明设计方案不贴近工序要求,灯具配光不合理,灯具布置欠妥等问题。     

The impact of lighting and table linen as ambient factors on meal intake and taste perception

Many ambient variables appear to impact amount and duration of food intake as well as taste perception. Two studies were conducted to determine whether changing light intensity has an impact on meal duration and volume as well as sensory and qualitative aspects of tomato soup in an experimental setting. Using a randomized crossover design in study 1, 66 participants were served tomato soup twice, under dimmed and bright light. In study 2, 159 participants were assigned to one of four randomization groups. A 2 × 2 design as a group setting was chosen adding a tablecloth as another ambient component. In both studies, participants assessed the soups’ appearance, sensory attributes, and the overall taste, quality and consistency on 100 mm visual analog scales. Meal duration and amount were also assessed. In study 1, there were no significant differences in amount, duration and sensory attributes between lighting conditions, except for the saltiness of the soup which was perceived as saltier under the low light condition (p = 0.019). In study 2, participants ate more, longer and rated sensory attributes and quality higher when seated with tablecloth. The longest duration, highest amount and quality were observed in the dimmed light condition with tablecloth. The tablecloth seemed to have a higher impact on food amount, meal duration and overall taste perception than lighting condition. The results suggest that single ambience factors such as lighting might only play a role in food intake and perception in combination with other ambient factors, such as decorative aspects.     

Multivariate analysis of subjective evaluation of indoor lighting environment

Though subjective feelings affected by lighting have been studied a lot, multivariate experimental studies are lacking in this research field. Central composite rotatable design (CCRD) was applied to investigate the influence of illuminance, correlated color temperature (CCT) and illuminance uniformity on satisfaction in this study. A series of subject experiments were carried out and polynomial regression models of luminous satisfaction for different activity scenarios were generated. Illuminance and CCT affected the satisfaction significantly in visual task scenarios, and the effect of them was independent with each other, which was demonstrated by the regression model (R² = 0.89). The variation of luminous satisfaction in general activity scenarios cannot be fully explained by the three investigated factors. The results contributed to the knowledge of multivariate analysis of luminous environment and indicated that much could be expected referring to the application of CCRD in this field.     

What encourages local authorities to engage with energy performance contracting for retrofitting? Evidence from German municipalities

Municipalities aiming at mitigating climate change by implementing new energy efficiency technologies face budgetary and capacity constraints. Outsourcing through energy service contracting could provide a solution. This paper reports results from a survey of 1298 municipalities concerning barriers to retrofitting public street lighting and the possible role of energy service contracting to overcome these barriers. Using a logistic regression analysis, the authors investigate determinants of opting for energy service contracts in the specific context of LED retrofits. Results point to an advantage of outsourcing in a financially and capacity-constrained environment, which corresponds with the main reasons for engaging in contracting: minimising investments and financial risks. However, municipalities often do not fully grasp the risks associated with retrofitting especially using a novel technology such as LED. In relation to that they underestimate the risk reduction potential of energy performance contracts (EPC). Previous experience with outsourcing increases the probability to engage in servitization although certain existing partnerships, particularly with utilities, prevent municipalities from considering energy performance contracts. Interestingly, engaging an energy consultant has a negative propensity to use energy service contracts, while pre-negotiated standardised contracts for energy performance contracts have a positive influence.     

A critical examination of perceptual and cognitive effects attributed to full-spectrum fluorescent lighting

Full-spectrum fluorescent lighting (FSFL) has been credited with causing dramatic improvements in vision, perception and cognitive performance as compared with other fluorescent lamp types. These effects are hypothesized to occur because of similarity between FSFL emissions and daylight, which is said to have evolutionary superiority over other light sources. This review, covering 1945-98, critically considers the evidence for these claims. In general, poorquality research has resulted in an absence of simple deterministic effects that can be confidently attributed to fluorescent lamp type. Promising avenues for lighting- behaviour research include investigations of cognitive mediators of lighting—behaviour relationships, and flicker rates and colour rendering effects on visual processing, appearance judgements and affect. Good lighting solutions are more complex than lamp type specification.