Energy-efficient Light Sources Research Articles

<p class="ZootaxaTitle"><strong>New techniques for improving resolution and visual information on flight activity in Trichoptera</strong></p>

Earlier design and use of photographic rigs for recording insects in free flight, and the applications and shortcomings of those efforts are reviewed. Improvements included the following: Replacement of laser beams with infrared (IR) LED beam-emitters and IR phototransistor detectors; an array of nine intersection points to increase the possibility of capturing images; improved electronic circuitry to avoid multiple image capture; more energy-efficient and smaller UV light sources to attract insects; a more rigid aluminium frame to support the UV and IR LED transmitters and detectors; development of an ultra-high-speed flash system 5 μs, or faster, to produce even sharper images than those produced by the 25 μs standard speedlight flash units set at 1/128th power; and a transportable wooden box to house all the electronic components and mounts for cameras and speedlights. This paper describes the design features of the rig and its use in the field and illustrates and compares photographic results obtained using a variety of photographic techniques aimed at providing high quality, sharp, images of insects in free flight, continuous traces of the flight pattern of insects, strobe images, and combinations of these techniques. From these images reasonably accurate estimates of insect size, wing beat frequency, flight speed, and information on mechanics of flight can be obtained.

Multicriteria decision aid analysis for the optimum performance of an ambient light sensor: methodology and case study

Lighting corresponds to a significant amount of a building’s total energy consumption, hence a variety of alternatives exist so as to minimize the energy consumption used for lighting such as the installation of energy efficient light sources and the exploitation of lighting controls and more significantly daylight harvesting. The position of an ambient light sensor that adjusts artificial lighting according to daylight levels is a key factor that affects the operation of any daylight harvesting system. This paper presents a multicriteria decision aid method to find the optimal position for the installation of an ambient light sensor, thus optimizing the performance of daylight exploitation system. Three criteria are proposed namely visual comfort, energy saving and the coefficient of correlation between the illuminance on the working plane and the illuminance perceived by the sensor on the ceiling. The multicriteria method PROMETHEE II is applied so as to evaluate 30 alternative positions and deduce the optimal one in an office room. The proposed methodology is flexible and highly customizable and can contribute significantly to the efficient commissioning of any daylight harvesting system.

Factors Affecting Residents’ Adoption of Energy-efficient Lighting in Rural Areas of China

Energy conservation is one of the core topics to address the goals for sustainable development. Approximately 40% of the total energy are consumed by buildings currently [1]. Energy consumed by lighting accounts for about 20% among all the segments in buildings. Therefore, it’s extremely important to improve the energy efficiency of lighting in buildings. However, this process is relatively slow in the rural areas of China, despite the government’s policies and subsidies on lighting efficiency. According to the current study, only about half of the dwellings in the rural areas has adopted energy saving light sources. The aim of current study is to reveal the key factors that affect the adoption of energy-efficient lighting in the rural areas of Fujian province in China, and provide valuable information for addressing the barriers. From the survey data collected from 321 valid responses, it becomes clear that for the residents who lived in the rural area, their personal characteristics, the perceived ease of use, the perceived lighting quality, and the impact of indoor lighting on their health were not associated with the actual use of the energy-efficient light sources at home. On the other hand, social support, awareness of the technology, and the perception of cost effectiveness were identified to be significantly correlated with the acceptance of energy-efficient light sources. A mediation analysis further shows an important causal relationship among these factors. Social support significantly improves the users’ awareness toward energy-efficient lighting designs, which would influence their perception on the cost effectiveness, which in turn would translate into actual adoption of energy-efficient light sources. These findings will pave the way for better understanding of the influencing factors for the acceptance of energy-efficient light sources, and provide the policy makes with valuable information for the formation and implementation of favourable policies and support programs, in order to speed up the spread of energy-efficient light sources in rural areas of China.

Highly-efficient photocatalytic disinfection of Escherichia coli by copper-doped molybdenum disulfide/bismuth sulfide under low-powered visible light irradiation

Reliable and affordable access to clean water has posted a threat in rural areas and fast expanding urban centers. Herein, a copper-doped MoS2/Bi2S3 photocatalyst is reported for photocatalytic bacterial disinfection. Under the irradiation of a single 18 W energy-saving light bulb, Cu-MoS2/Bi2S3 was able to achieve 100% inactivation of E. coli in 60 min. This high efficiency of Cu-MoS2/Bi2S3 can be attributed to its enhancement of light absorption and rapid electron-hole separation. This work provides a new insight into the potential use of energy efficient light source for water sanitation.

Mating success of the black soldier fly, Hermetia illucens (Diptera: Stratiomyidae), under four artificial light sources

Larvae of the black soldier fly (BSF) Hermetia illucens (L.) (Diptera: Stratiomyidae) are promising organisms to be used for organic waste bioconversion. Breeding BSF indoors has been suggested as a cost-effective approach for countries with long winters or low sunlight levels through the year. As the BSF mating is visually mediated, artificial illumination conditions are critical to a successful indoor breeding system. In this study, we tested four different types of artificial light sources for their effects on BSF mating success. They included: (1) a halogen lamp; (2) a combination of a white light-emitting diode (LED) lamp and a fluorescent ultra violet lamp; (3) a metal halide lamp, and (4) a specially designed light-emitting diode (BSFLED) lamp, whose design was based on the specific BSF adult visual spectral sensitivity. We determined the spectra of four artificial light sources, compared their spectral composition in relation to the BSF-visible spectrum, and compared their effects on the mating success of two different BSF colonies. BSFLED was the most energy efficient light source in spectral composition and led to the highest mating success in terms of the percentage of inseminated females and fertile clutches. Thus, BSFLED is the most suitable light source tested in our experiment for breeding BSF indoors. The colony effect and possible light flickering effect on BSF mating success were also detected. The implications of these findings are discussed.

PROBLEMS OF STUDYING AND IMPLEMENTING INNOVATIVE LIGHTING TECHNOLOGIES IN VOCATIONAL EDUCATION

Recent studies indicate that the color temperature of the light flux from light sources can affect some biological functions in humans. It can be hypothesized that light sources, such as LED lamps, which are now installed in the lighting systems of educational institutions, may in some way affect the acquisition of educational content by students in the learning process and the quality of educational services in general. The modern education provides for independent learning activities using personal computers with liquid crystal monitors, which can be categorized as LED-based light sources by the emitted light spectrum and the emitter operation principle. The emergence of new lighting technologies, which in some way may affect the performance of students, and our new experimental data in the field of innovative education were translated into the idea of a new teaching method. The article describes the possibilities for creating a teaching method that is based on a combination of the innovative concept of the learning model, using a light-color environment with a modified spectrum of shades of white, and computer assisted express testing of the retained knowledge. It is assumed that the introduction of energy-efficient light sources in educational institutions may create a unique light-color environment with the possibility of dynamic changes in light temperature and flux, which can take the learning process to a new level.

Design of highly efficient phosphor-converted white light-emitting diodes with color rendering indices (R1 \u2212 R15) \u2265 95 for artificial lighting

Phosphor-converted white light-emitting diodes (pc-WLEDs) are excellent energy-efficient light sources for artificial lighting applications. One goal of artificial lighting is to make objects/images look natural – as they look under the sunlight. The ability of a light source to accurately render the natural color of an object is gauged by the parameter – color rendering index (CRI). A conventional pc-WLED has an average CRI ~ 80, which is very low for accurate color reproduction. To utilize the pc-WLEDs for artificial lighting applications, all the CRI points (R1 – R15) should be above 95. However, there is a trade-off between CRI and luminous efficacy (LER), and it is challenging to increase both CRI and LER. Herein we propose a novel LED package (PKG) design to achieve CRI points ≥95 and efficiency ~100 lm/W by introducing two blue LEDs and a UV LED in combination with green and red phosphors. The silicone encapsulant, the current through the LEDs, and the green/red phosphor ratio were optimized for achieving high CRI and LER. Our re-designed LED PKG will find applications in stadium lighting as well as for ultra-high-definition television production where high CRI points are required for the artificial light source.

A common type of commercially available LED light source allows for colour discrimination performance at a level comparable to halogen lighting

As light sources based on light emitting diodes (LED) are increasingly used to replace classic tungsten-based light sources in household lighting applications, possible impairments of colour perception under those light sources due to a different spectral power distribution become a major concern. The Colour Rendering Index (CRI) which is the only measure available to the end user is controversial and does not represent a comprehensive measure of colour perception. Aspects of colour perception disregarded by the CRI such as colour discrimination have to be taken into account as well. Therefore, we evaluated colour discrimination performance under a commercially available phosphor-converted LED light source from a popular brand (OSRAM) in comparison to a classic tungsten-based halogen light source. Colour discrimination performance was not affected by the type of light source, indicating that the phosphor-converted LED light source enables colour discrimination performance comparable to that of halogen lighting despite being associated with a lower CRI. Practitioner summary: Considering the increasing use of energy efficient light sources, we compared colour discrimination under a common type of phosphor-converted LED and under traditional halogen lighting. Colour discrimination performance was comparable in both lighting conditions, indicating that the phosphor-converted LED can replace halogen lighting without sacrificing colour discrimination for energy efficiency. Abbreviations: LED: light emitting diode; CRI: colour rendering index; CCT: correlated colour temperature; CIE: commission internationale de l’éclairage; FMHT: Farnsworth-Munsell 100-Hue Test; lm: lumen; lx: lux, lumen/m^2; W: watt; nm: nanometer; K: kelvin

A decision support system for techno-economic evaluation of indoor lighting systems with LED luminaires

The necessity for energy saving in lighting leads to installation of new energy efficient light sources, especially LED luminaires. Although solid state lighting is considered the dominant lighting technology for the future there exist no concrete methods to evaluate LED luminaires and decide the optimal one for each lighting application. Multicriteria decision methods are utilized in various decision problems so as to evaluate alternatives through complex and conflicting criteria. This paper introduces a decision support system for a complete techno-economic evaluation of LED luminaires through multicriteria analysis. Seven criteria are proposed so as to assess the technical and economic characteristics of LED luminaires and ensure their compliance with European Norms regarding office lighting. Laboratory measurements and lighting calculations in 8 indoor types of LED luminaires are performed so as to define their technical characteristics and evaluate their performance concerning the lighting of an office. Finally, the PROMETHEE II multicriteria method is applied, which ranks the 8 types of luminaires and determines the optimal one. The proposed decision support system can be applied to any type of luminaire and can be used by professionals who want to evaluate different luminaire suppliers and determine the optimal luminaire tender for the lighting of any indoor space.

Sonochemical Synthesis of Ce-doped TiO2 Nanostructure: A Visible-Light-Driven Photocatalyst for Degradation of Toluene and O-Xylene.

Ce-doped TiO2 nanostructures (CeT) with different amounts of Ce (0.5, 0.75, 1.0, 1.5, and 2.0 wt. %) were synthesized using a sonochemical processing method. The physicochemical properties of the prepared samples were explored using UV-visible diffuse reflectance spectroscopy (UV-vis DRS), field-emission TEM (FE-TEM), XRD, X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy (PL), and surface area and pore size analyzers. The photocatalytic performance of the prepared CeT was assessed by monitoring their degradation efficiencies for gaseous toluene and o-xylene—widely known as significant indoor air pollutants—under daylight irradiation. The prepared CeT exhibited significantly improved photocatalytic performance towards the degradation of toluene and o-xylene, which was much higher than that observed for pure TiO2 and commercial P25 TiO2. Particularly, photocatalytic degradation efficiencies by the prepared CeT catalysts increased remarkably in the case of o-xylene (up to 99.4%) compared to toluene (up to 49.1%). The degradation efficiency by the CeT was greatest for the CeT-0.75 sample, followed by, in order, CeT-1.0, CeT-0.5, CeT-1.5, and CeT-2.0 samples in agreement with the order of the surface area and the particle size of the catalysts. According to the change of light source, the average decomposition efficiencies for toluene and o-xylene by CeT-0.75 were shown in the order of conventional daylight lamp > violet light emitting diodes (LEDs) > white LEDs. The decomposition efficiencies normalized to supplied electric power, however, were estimated to be in the following order of violet LEDs > white LEDs > conventional daylight lamp, indicating that the LEDs could be a much more energy efficient light source for the photodecomposition of target toluene and o-xylene using the CeT-0.75 photocatalyst.

Анализ цветовых характеристик источников света на базе светоизлучающих диодов в системах динамичного освещения

Lighting equipment manufacturers provide the following data that determine the lighting quality: the color temperature (CT), the general color rendering index and the ripple coefficient. However, for a lighting system to be designed in a professional manner, it is necessary to know such parameters as variation of the radiation spectral distribution in the course of operation, the repeatability of characteristics and the influence of environmental conditions on the light device as a whole. All these parameters and characteristics will allow the designer to take into account the specific features of the facility that has to be illuminated. New technologies and new light sources give an impetus for revising the existing lighting standards and rules. Light-emitting diodes (LEDs) are a relatively new, promising and energy-efficient light source, which has a number of unique properties: a long service life, high luminous efficiency, a high color rendering index, aesthetics, environmental friendliness, reliability, high strength and the possibility to control both spectral and integral parameters and characteristics. Owing to the compact size of LEDs, it became possible to make luminaires of various shapes and sizes, and, as a result, of different power and luminous flux. The existing values of luminous efficacy and improvement of the color LED selection (binning) method allow one to speak about the possibility to make a white light source based on color crystals. The use of LED-based light sources in dynamic lighting installations are of great interest for studying them because such light sources open the possibility of dimming the luminous flux and changing the radiation chromaticity independently of each other. Methods of making white LED modules with a variable color temperature (CT) on the basis of two-crystal luminiferous LEDs with different CT and multicrystal LEDs are considered. The accomplished analysis of the data obtained as a result of calculations made it possible to select suitable combinations of LEDs ensuring the best values of the color rendering index and CT repeatability.

Microstructured light guiding plate for single-sided light emission as light source for room illumination

Microstructured light guiding plates (LGP) open up new capabilities in the design of energy efficient and flexible light sources for room lighting. One desirable application is the illumination of office rooms by LGPs located mainly at the façade. Starting with the requirements of an ideal light distribution curve for uniform room lighting, suitable optical microstructures have been designed and investigated by numerical ray tracing methods to be integrated in façade elements. The maximum of the desired light distribution curve for the test case is at an angle of 96° with respect to the vertical direction. The designed micro-system meets this requirement very well at an angle of 98° and a light cone width of 25°. The light emission of the proposed LGP is highly efficient with 80% coupling efficiency.

In-Use Photostability Practice and Regulatory Evaluation for Pharmaceutical Products in an Age of Light-Emitting Diode Light Sources

This article describes how the increased use of energy-efficient solid-state light sources (e.g., light-emitting diode [LED]-based illumination) in hospitals, pharmacies, and at home can help alleviate concerns of photodegradation for pharmaceuticals. LED light sources, unlike fluorescent ones, do not have spurious spectral contributions <400 nm. Because photostability is primarily evaluated in the International Council of Harmonization Q1B tests with older fluorescent bulb standards (International Organization for Standardization 10977), the amount of photodegradation observed can over-predict what happens in reality, as products are increasingly being stored and used in environments fitted with LED bulbs. Because photodegradation is premised on light absorption by a compound of interest (or a photosensitizer), one can use the overlap between the spectral distribution of a light source and the absorption spectra of a given compound to estimate if photodegradation is a possibility. Based on the absorption spectra of a sample of 150 pharmaceutical compounds in development, only 15% would meet the required overlap to be a candidate to undergo direct photodegradation in the presence of LED lights, against a baseline of 55% of compounds that would, when considering regular fluorescent lights. Biological drug products such as peptides and monoclonal antibodies are also expected to benefit from the use of more efficient solid-state lighting.

Room temperature continuous-wave nanolaser diode utilized by ultrahigh-Q few-cell photonic crystal nanocavities

Few-cell point-defect photonic crystal (PhC) nanocavities (such as LX and H1 type cavities), have several unique characteristics including an ultra-small mode volume (Vm), a small device footprint advantageous for dense integration, and a large mode spacing advantageous for high spontaneous-emission coupling coefficient (β), which are promising for energy-efficient densely-integratable on-chip laser light sources enhanced by the cavity QED effect. To achieve this goal, a high quality factor (Q) is essential, but conventional few-cell point-defect cavities do not have a sufficiently high Q. Here we adopt a series of modified designs of LX cavities with a buried heterostructure (BH) multi-quantum-well (MQW) active region that can achieve a high Q while maintaining their original advantages and fabricate current-injection laser devices. We have successfully observed continuous-wave (CW) lasing in InP-based L1, L2, L3 and L5 PhC nanocavities at 23°C with a DC current injection lower than 10 μA and a bias voltage lower than 0.9 V. The active volume is ultra-small while maintaining a sufficiently high confinement factor, which is as low as ~10-15 cm3 for a single-cell (L1) nanocavity. This is the first room-temperature current-injection CW lasing from any types of few-cell point-defect PhC nanocavities (LX or H1 types). Our report marks an important step towards realizing a nanolaser diode with a high cavity-QED effect, which is promising for use with on-chip densely integrated laser sources in photonic networks-on-chip combined with CMOS processors.

Up-Conversion Fluorescence of Phosphorous and Nitrogen Co-Doped Carbon Quantum Dots (CDs) Coupled with Weak LED Light Source for Full-Spectrum Driven Photocatalytic Degradation via ZnO-CDs Nanocomposites

In order to achieve efficient, green, and low-cost photocatalysts, carbon materials are highly desirable alternatives to other sensitizers such as; dyes and chalcogenide quantum dots. In this paper, we describe green synthesis of phosphorous and nitrogen co doped carbon quantum dots (CDs) from a low-cost source. The CDs were used as photosensitizers to enhance the visible-NIR driven photocatalytic degradation of organic compounds under weak LED light illumination as an energy efficient light source. The CDs were highly fluorescent and exhibit excitation wavelength independent fluorescence. Electrochemical measurements of CDs were performed to assess the conduction and valences bands. Nanocomposites ZnO-CDs, interestingly, the CDs as a photosensitizer showed dramatic catalytic enhancement, as 80% of methylene blue was degraded under irradiation with a weak LED white light, visible to near IR light, for 10 h. While ZnO under same circumstances, could remove only 10%. The enhancement mechanism in addition to transfer of photoelectrons from the conduction band of CDs to the conduction band ZnO, could also be related to up-conversion properties of CDs, increase the absorptivity of the light. The presented finding showed that low cost source of carbon was used to make efficient nanocomposite photocatalyst for degradation of organic wastes.

МЕТАЛОГАЛОГЕННІ ЛАМПИ: ДОСЯГНУТИЙ РІВЕНЬ ТА ШЛЯХИ ПОДАЛЬШОГО ПІДВИЩЕННЯ СВІТЛОВОЇ ЕФЕКТИВНОСТІ ЕНЕРГОЕКОНОМІЧНИХ ДЖЕРЕЛ СВІТЛА

В роботі аналізуються сучасні конструкції та параметри комерційних зразків металогалогенних ламп провідних світових виробників, їх переваги та недоліки перед іншими енергоекономічними джерелами світла та проведено аналіз можливих шляхів подальшого підвищення світлових параметрів цих ламп.

Advancement in Road Lighting

Road lighting is on the verge of one of the most attentive changes since its first introduction. The synergetic effect of the advancement of road lighting technology and usage pattern is going to change the concept of road lighting. By most estimates, light emitting diodes (LEDs) are the most energy efficient light sources that can be used in road lighting. Today, the energy saving potential when replacing HPS lamps with LED luminaires is one-third with current technology and two-thirds with improved technology in the future. This technological transformation has the potential of energy saving up to 83 % in comparison with HPS lamps. The energy saving is achievable with changing the pattern of use by intelligent road lighting control based on reducing burning hours. Intelligent road lighting can be based on such parameters as traffic density, ambient light, road condition and weather circumstances. It can also be more dynamic and consider the combined effect of road lighting and individual car headlights. The widespread adaptation of these emerging technologies is envisioned to lead towards more sustainable lighting.

Broadly Tunable Self-injection Locked InAs/InP Quantum-dash Laser Based Fiber/FSO/Hybrid Fiber-FSO Communication at 1610 nm

We report a self-injection-locked InAs/InP quantum-dash tunable laser with ∼11 nm (∼1602–1613 nm) tuning window for next generation multiuser ultrahigh capacity fiber/free-space optics (FSO)/hybrid fiber-FSO-based optical networks. A tunability of >18 independently locked subcarriers with ∼28 dB side mode suppression ratio (SMSR) and stable (±0.1 dBm) mode power is exhibited, and an estimated small injection ratio of ∼–22 dBm is found to sustain locking and SMSR. Error free transmission of 100 and 128 Gb/s externally modulated dual-polarization quadrature phase shift keying (DP-QPSK) signals over 20 km single mode fiber (SMF) and 16 m indoor FSO links are demonstrated across 8 and 4 individual subcarriers, respectively, thus covering the entire tuning range. Moreover, up to 168 (192) Gb/s successful transmission over 10 km SMF (BTB) and 176 Gb/s over 16 m FSO link is achieved on a ∼1610 nm subcarrier. Finally, a 128 Gb/s DP-QPSK transmission over 11 km SMF–8 m FSO–11 km SMF hybrid system is accomplished, thus paving the potential deployment of this single-chip, cost-effective, and energy efficient tunable light source in terabits/s next-generation passive optical networks.

Enhanced growth rate and ulvan yield of Ulva pertusa using light-emitting diodes (LEDs)

Light-emitting diode (LED) technology offers potential energy-efficient light sources for algal aquaculture. In this study, the growth rate and ulvan yield of Ulva pertusa used for broad commercial applications were enhanced in vitro. To investigate the response of Ulva to LEDs, algae were grown under white fluorescent, pure primary color LED, and mixed LED lights for 28 days. Ulva sp. under blue LED and white fluorescent light showed higher specific growth rate (SGR, 12% day−1) than other light sources, while the growth under mixed red-blue LED light was lower than that under white fluorescent lighting. Despite the differences in alga growth under LEDs and white fluorescent light, few differences are observed in N and P content among algae grown under any light source. U. pertusa showed tissue nitrogen and ulvan contents in the ranges of 4.4–6.7% and 20.4–25.1%, respectively, under all LED light treatments. The ulvan extracted from algae under blue LED showed high levels of antioxidant activity measured with 2,2-diphenylpicrylhydrazyl (DPPH) radical and hydrogen peroxide. Moreover, the ulvan obtained under different lights showed different monosaccharide compositions. Based on these results, LEDs should be considered as the main light sources for indoor seaweed cultivation.

Influence of blue/red vs. white LED light treatments on biomass, shoot morphology, and quality parameters of hydroponically grown kale

Abstract Solid-state light emitting diodes (LEDs) are emerging as an energy efficient alternative lighting source in controlled environments. The objective of this study was to examine the impact of sole-source LED lighting quality/duration on biomass, morphology, and nutritional quality of kale (Brassica oleracea var. acephala) in a controlled environment. ‘Premier’ kale seedlings were grown hydroponically using a 30 d production cycle. Experimental LED treatments included: 1) white LED for 37 d; 2) 5% B/95% R for 37 d; 3) 20%B/80%R for 30 d; 4) 20%B/80%R for 25 d; 5) 20%B/80%R for 20 d; and 6) 20%B/80%R for 15 d prior to harvest. Treatments were arranged in a randomized complete block design, and three complete experimental runs were conducted. Plant height (cm), leaf length and width (cm), shoot and root fresh mass (g) and dry mass (g) were collected at harvest. Kale shoot tissues were measured for nutritionally important pigments, glucosinolates, mineral elements, and soluble carbohydrates. All plants treated with 20%B/80%R lighting were shorter compared to the white (37 d) and 5%B/95%R (37 d) treatments, respectively. Chlorophyll fluorescence parameters were influenced by LED treatment, while maximum quantum yield (QYmax) was not. LED light treatment impacted kale zeaxanthin (P = 0.01), antheraxanthin (P = 0.01), fructose (P = 0.03), and potassium (P = 0.02). Data suggest that increasing blue light during production has limited impact on 37-d old hydroponic kale developmental and nutritional parameters over continuous white LED lighting.