527 research outputs found

    Electronic operation and control of high-intensity gas-discharge lamps

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    The ever increasing amount of global energy consumption based on the application of fossil fuels is threatening the earth’s natural resources and environment. Worldwide, grid-based electric lighting consumes 19 % of total global electricity production. For this reason the transition towards energy efficient lighting plays an important environmental role. One of the key technologies in this transition is High-Intensity Discharge (HID) lighting. The technical revolution in gas-discharge lamps has resulted in the highlyefficient lamps that are available nowadays. As with most energy efficient light solutions, all HID lighting systems require a ballast to operate. Traditionally, magnetic ballast designs were the only choice available for HID lighting systems. Today, electronic lampdrivers can offer additional power saving, flicker free operation, and miniaturisation. Electronic lamp operation enables additional degrees of freedom in lamp-current control over the conventional electro-magnetic (EM) ballasts. The lamp-driver system performance depends on both the dynamics of the lamp and the driver. This thesis focuses on the optimisation of electronically operated HID systems, in terms of highly-efficient lamp-driver topologies and, more specifically, lamp-driver interaction control. First, highly-efficient power topologies to operate compact HID lamps on low-frequency-square-wave (LFSW) current are explored. The proposed two-stage electronic lamp-driver consists of a Power Factor Corrector (PFC) stage that meets the power utility standards. This converter is coupled to a stacked buck converter that controls the lamp-current. Both stages are operated in Zero Voltage Switching (ZVS) mode in order to reduce the switching losses. The resulting two-stage lamp-drivers feature flexible controllability, high efficiency, and high power density, and are suitable for power sandwich packaging. Secondly, lamp-driver interaction (LDI) has been studied in the simulation domain and control algorithms have been explored that improve the stability, and enable system optimisation. Two HID lamp models were developed. The first model describes the HID lamp’s small-signal electrical behaviour and its purpose is to aid to study the interaction stability. The second HID lamp model has been developed based on physics equations for the arc column and the electrode behaviour, and is intended for lampdriver simulations and control applications. Verification measurements have shown that the lamp terminal characteristics are present over a wide power and frequency range. Three LDI control algorithms were explored, using the proposed lampmodels. The first control principle optimises the LDI for a broad range of HID lamps operated at normal or reduced power. This approach consists of two control loops integrated into a fuzzy-logic controller that stabilises the lamp-current and optimises the commutation process. The second control problem concerns the application of ultra high performance (UHP) HID lamps in projection applications that typically set stringent requirements on the quality of the light generated by these lamps, and therefore the lampcurrent. These systems are subject to periodic disturbances synchronous with the LFSW commutation period. Iterative learning control (ILC) has been examined. It was experimentally verified that this algorithm compensates for repetitive disturbances. Third, Electronic HID operation also opens the door for continuous HID lamp dimming that can provide additional savings. To enable stable dimming, an observer-based HID lamp controller has been developed. This controller sets a stable minimum dim-level and monitors the gas-discharge throughout lamp life. The HID lamp observer derives physical lamp state signals from the HID arc discharge physics and the related photometric properties. Finally, practical measurements proved the proposed HID lamp observer-based control principle works satisfactorily

    Revision of the EU Green Public Procurement Criteria for Street Lighting and Traffic Signals - Preliminary Report

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    Lighting is used on more than 1.6 million km of roads in EU28 countries, accounting for some 35 TWh of electricity consumption (1.3% of total electricity consumption) and costing public authorities almost €4000 million each year. A broad review of relevant technical, policy, academic and legislative literature has been conducted. This report examines the current market situation and the potential for reducing environmental impacts and electricity costs by assessing the recent developments in road lighting technology, particularly LEDs. Particularly important areas identified relate to energy efficiency, light pollution, product durability and, specifically for longer lasting and rapidly evolving new LED technologies, reparability and upgradeability. The information in this report shall serve as a basis for discussion with stakeholders about the further development and revision of EU GPP criteria for street lighting and traffic signals.JRC.B.5-Circular Economy and Industrial Leadershi

    Reducing Barriers To The Use of High-Efficiency Lighting Systems

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    White Top-Emitting OLEDs on Metal Substrates

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    This work focusses on the development of top-emitting white organic light-emitting diodes (OLEDs), which can be fabricated on metal substrates. Bottom-emitting OLEDs have been studied intensively over the years and show promising perspectives for future commercial applications in general lighting. The development of top-emitting devices has fallen behind despite the opportunities to produce these devices also on low-cost opaque substrates. This is due to the challenges of top-light-emission concerning the achievement of a broad and well-balanced white emission spectrum in presence of a strong microcavity. The following work is a further step towards the detailed understanding and optimization of white top-emitting OLEDs. First, the available metal substrates and the deposited silver electrodes are examined microscopically to determine their surface characteristics and morphology in order to assess their applicability for thin-film organic stacks of OLEDs. The examination shows the suitability for untreated Alanod metal substrates, which display low surface roughness and almost no surface defects. For the deposited silver anodes, investigations via AFM show a strong influence of the deposition rate on the surface roughness. In the main part of the work top-emissive devices with both hybrid and all-phosphorescent architecture are investigated, in which three or four emitter materials are utilized to achieve maximum performance. The feasibility for top-emitting white OLEDs in first and second order devices is investigated via optical simulations, using the example of a three-color hybrid OLED. Here, the concept of a dielectric capping layer on top of the cathode is an essential criterion for broadband and nearly angle independent light emission. The main focus concerning the investigation of fabricated devices is the optimization of the organic stacks to achieve high efficiencies as well as excellent color quality of warm white emission. The optimization of the hybrid layer structure based on three emitter materials using a combined aluminum-silver anode mirror resulted in luminous efficacies up to 13.3 lm/W and 5.3 % external quantum efficiency. Optical analysis by means of simulation revealed a superior position concerning internal quantum efficiency compared to bottom-emitting devices with similar layer structure. The devices show an enhanced emission in forward direction compared to an ideal Lambertian emitter, which is highly preferred for lighting applications. The color quality - especially for devices based on a pure Al anode - is showing excellent color coordinates near the Planckian locus and color rending indices up to 77. The introduction of an additional yellow emitter material improves the luminous efficacy up to values of 16.1 lm/W and external quantum efficiencies of 5.9 %. With the choice of a all-phosphorescent approach, using orange-red, light blue and green emitter materials, luminous efficacies of 21.7 lm/W are realized with external quantum efficiencies of 8.5 %. Thereby, color coordinates of (x, y) = (0.41, 0.45) are achieved. Moreover, the application of different crystalline capping layers and alternative cathode materials aim at a scattering of light that further reduces the angular dependence of emission. Experiments with the crystallizing material BPhen and thin carbon nanotube films (CNT) are performed. Heated BPhen capping layer with a thickness of 250 nm show a lower color shift compared to the NPB reference capping layer. Using CNT films as cathode leads to a broadband white emission at a cavity thickness of 160 nm. However, due to very high driving voltages needed, the device shows low luminous efficacy. Finally, white top-emitting organic LEDs are successfully processed on metal substrates. A comparison of three and four color based hybrid devices reveal similar performance for the devices on glass and metal substrate. Only the devices on metal substrate show slightly higher leakaged currents. During repeated mechanical bending experiments with white devices deposited on 0.3 mm thin flexible Alanod substrates, bending radii up to 1.0 cm can be realized without device failure.Diese Arbeit richtet ihren Schwerpunkt auf die Entwicklung von top-emittierenden weißen organischen Leuchtdioden (OLEDs), welche auch auf Metallsubstraten gefertigt werden können. Im Laufe der letzten Jahre wurden bottom-emittierende OLEDs sehr intensiv studiert, da sie vielversprechende Perspektiven für zukünftige kommerzielle Anwendungen in der Allgemeinbeleuchtung bieten. Trotz der Möglichkeit, OLEDs auch auf kostengünstigen lichtundurchlässigen Substraten fertigen zu können, blieb die Entwicklung von top-emittierenden Bauteilen dabei allerdings zurück. Dies läßt sich auf die enormen Herausforderungen von top-emittierenden OLEDs zurückführen, ein breites und ausgeglichenes weißes Abstrahlungsspektrum in Gegenwart einer Mikrokavität zu generieren. Die folgende Arbeit liefert einen Beitrag zum detaillierten Verständnis und der Optimierung von weißen top-emittierenden OLEDs. Zunächst werden die verfügbaren Metallsubstrate und abgeschiedenen Silberelektroden auf ihre Oberflächeneigenschaften und Morphologie mikroskopisch untersucht, um damit ihre Verwendbarkeit für organische Dünnfilmstrukturen in OLEDs einzuschätzen. Die Untersuchung zeigt eine Eignung von unbehandelten Alanod Metallsubstraten auf, welche eine niedrige Oberflächenrauigkeit und fast keine Oberflächendefekte besitzen. Bei den abgeschiedenen Silberelektroden zeigen Untersuchungen mit dem Rasterkraftmikroskop eine starke Beeinflussung der Oberflächenrauigkeit durch die Aufdampfrate. Im Hauptteil der Arbeit werden top-emittierende Dioden mit hybrid und voll-phosphoreszenter Architektur untersucht, in welcher drei oder vier Emittermaterialien verwendet werden, um eine optimale Leistungscharakteristik zu erreichen. Die Realisierbarkeit von top-emittierenden weißen OLEDs in Dioden erster und zweiter Ordnung wird durch optische Simulation am Beispiel einer dreifarb-OLED mit Hybridstruktur ermittelt. Dabei ist das Konzept der dielektrischen Deckschicht - aufgebracht auf die Kathode - ein essenzielles Kriterium für breitbandige und annähernd winkelunabhängige Lichtemission. Der Schwerpunkt im Hinblick auf die Untersuchung von hergestellten Dioden liegt in der Optimierung der organischen Schichtstrukturen, um hohe Effizienzen sowie exzellente warmweiße Farbqualität zu erreichen. Im Rahmen der Optimierung von hybriden Schichtstrukturen basierend auf drei Emittermaterialien resultiert die Verwendung eines kombinierten Aluminium-Silber Anodenspiegels in einer Lichtausbeute von 13.3 lm/W und einer externen Quanteneffizienz von 5.3 %.Eine optische Analyse mit Hilfe von Simulationen zeigt eine überlegene Stellung hinsichtlich der internen Quanteneffizient verglichen mit bottom-emittierenden Dioden ähnlicher Schichtstruktur. Die Dioden zeigen eine verstärkte vorwärts gerichtete Emission im Vergleich zu einem idealen Lambertschen Emitter, welche in hohem Maße für Beleuchtungsanwendungen erwünscht ist. Es kann eine ausgezeichnete Farbqualität erreicht werden - insbesondere für Dioden basierend auf einer reinen Aluminiumanode - mit Farbkoordinaten nahe der Planckschen Strahlungskurve und Farbwiedergabeindizes bis zu 77. Die weitere Einführung eines zusätzlichen gelben Emittermaterials verbessert die Lichtausbeute auf Werte von 16.1 lm/W und die externe Quanteneffizient auf 5.9 %. Mit der Wahl eines voll-phosphoreszenten Ansatzes unter der Verwendung eines orange-roten, hellblauen und grünen Emittermaterials werden Lichtausbeuten von 21.7 lm/W und externe Quanteneffizienten von 8.5 % erzielt. Damit werden Farbkoordinaten von (x, y) = (0.41, 0.45) erreicht. Darüberhinaus zielt die Verwendung von verschiedenen kristallinen Deckschichten und alternativen Kathodenmaterialien auf eine Streuung des ausgekoppelten Lichts ab, was die Winkelabhängigkeit der Emission vermindern soll. Experimente mit dem kristallisierenden Material BPhen und dünnen Filmen aus Kohlenstoffnanoröhren werden dabei durchgeführt. Geheizte BPhen Deckschichten mit einer Schichtdicke von 250 nm zeigen eine geringere Farbverschiebung verglichen mit einer NPB Referenzdeckschicht. Die Verwendung von Kohlenstoffnanoröhren als Kathode führt zu einer breitbandigen weißen Emission bei einer Kavitätsschichtdicke von 160 nm. Schließlich werden weiße top-emittierende organische Leuchtdioden erfolgreich auf Metallsubstraten prozessiert. Ein Vergleich von drei- und vierfarb-basierten hybriden Bauteilen zeigt ähnliche Leistungsmerkmale für Dioden auf Glas- und Metallsubstraten. Während wiederholten mechanischen Biegeexperimenten mit weißen Dioden auf 0.3 mm dicken flexiblen Alanodsubstraten können Biegeradien bis zu 1.0 cm ohne Bauteilausfall realisiert werden

    White Top-Emitting OLEDs on Metal Substrates

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    This work focusses on the development of top-emitting white organic light-emitting diodes (OLEDs), which can be fabricated on metal substrates. Bottom-emitting OLEDs have been studied intensively over the years and show promising perspectives for future commercial applications in general lighting. The development of top-emitting devices has fallen behind despite the opportunities to produce these devices also on low-cost opaque substrates. This is due to the challenges of top-light-emission concerning the achievement of a broad and well-balanced white emission spectrum in presence of a strong microcavity. The following work is a further step towards the detailed understanding and optimization of white top-emitting OLEDs. First, the available metal substrates and the deposited silver electrodes are examined microscopically to determine their surface characteristics and morphology in order to assess their applicability for thin-film organic stacks of OLEDs. The examination shows the suitability for untreated Alanod metal substrates, which display low surface roughness and almost no surface defects. For the deposited silver anodes, investigations via AFM show a strong influence of the deposition rate on the surface roughness. In the main part of the work top-emissive devices with both hybrid and all-phosphorescent architecture are investigated, in which three or four emitter materials are utilized to achieve maximum performance. The feasibility for top-emitting white OLEDs in first and second order devices is investigated via optical simulations, using the example of a three-color hybrid OLED. Here, the concept of a dielectric capping layer on top of the cathode is an essential criterion for broadband and nearly angle independent light emission. The main focus concerning the investigation of fabricated devices is the optimization of the organic stacks to achieve high efficiencies as well as excellent color quality of warm white emission. The optimization of the hybrid layer structure based on three emitter materials using a combined aluminum-silver anode mirror resulted in luminous efficacies up to 13.3 lm/W and 5.3 % external quantum efficiency. Optical analysis by means of simulation revealed a superior position concerning internal quantum efficiency compared to bottom-emitting devices with similar layer structure. The devices show an enhanced emission in forward direction compared to an ideal Lambertian emitter, which is highly preferred for lighting applications. The color quality - especially for devices based on a pure Al anode - is showing excellent color coordinates near the Planckian locus and color rending indices up to 77. The introduction of an additional yellow emitter material improves the luminous efficacy up to values of 16.1 lm/W and external quantum efficiencies of 5.9 %. With the choice of a all-phosphorescent approach, using orange-red, light blue and green emitter materials, luminous efficacies of 21.7 lm/W are realized with external quantum efficiencies of 8.5 %. Thereby, color coordinates of (x, y) = (0.41, 0.45) are achieved. Moreover, the application of different crystalline capping layers and alternative cathode materials aim at a scattering of light that further reduces the angular dependence of emission. Experiments with the crystallizing material BPhen and thin carbon nanotube films (CNT) are performed. Heated BPhen capping layer with a thickness of 250 nm show a lower color shift compared to the NPB reference capping layer. Using CNT films as cathode leads to a broadband white emission at a cavity thickness of 160 nm. However, due to very high driving voltages needed, the device shows low luminous efficacy. Finally, white top-emitting organic LEDs are successfully processed on metal substrates. A comparison of three and four color based hybrid devices reveal similar performance for the devices on glass and metal substrate. Only the devices on metal substrate show slightly higher leakaged currents. During repeated mechanical bending experiments with white devices deposited on 0.3 mm thin flexible Alanod substrates, bending radii up to 1.0 cm can be realized without device failure.Diese Arbeit richtet ihren Schwerpunkt auf die Entwicklung von top-emittierenden weißen organischen Leuchtdioden (OLEDs), welche auch auf Metallsubstraten gefertigt werden können. Im Laufe der letzten Jahre wurden bottom-emittierende OLEDs sehr intensiv studiert, da sie vielversprechende Perspektiven für zukünftige kommerzielle Anwendungen in der Allgemeinbeleuchtung bieten. Trotz der Möglichkeit, OLEDs auch auf kostengünstigen lichtundurchlässigen Substraten fertigen zu können, blieb die Entwicklung von top-emittierenden Bauteilen dabei allerdings zurück. Dies läßt sich auf die enormen Herausforderungen von top-emittierenden OLEDs zurückführen, ein breites und ausgeglichenes weißes Abstrahlungsspektrum in Gegenwart einer Mikrokavität zu generieren. Die folgende Arbeit liefert einen Beitrag zum detaillierten Verständnis und der Optimierung von weißen top-emittierenden OLEDs. Zunächst werden die verfügbaren Metallsubstrate und abgeschiedenen Silberelektroden auf ihre Oberflächeneigenschaften und Morphologie mikroskopisch untersucht, um damit ihre Verwendbarkeit für organische Dünnfilmstrukturen in OLEDs einzuschätzen. Die Untersuchung zeigt eine Eignung von unbehandelten Alanod Metallsubstraten auf, welche eine niedrige Oberflächenrauigkeit und fast keine Oberflächendefekte besitzen. Bei den abgeschiedenen Silberelektroden zeigen Untersuchungen mit dem Rasterkraftmikroskop eine starke Beeinflussung der Oberflächenrauigkeit durch die Aufdampfrate. Im Hauptteil der Arbeit werden top-emittierende Dioden mit hybrid und voll-phosphoreszenter Architektur untersucht, in welcher drei oder vier Emittermaterialien verwendet werden, um eine optimale Leistungscharakteristik zu erreichen. Die Realisierbarkeit von top-emittierenden weißen OLEDs in Dioden erster und zweiter Ordnung wird durch optische Simulation am Beispiel einer dreifarb-OLED mit Hybridstruktur ermittelt. Dabei ist das Konzept der dielektrischen Deckschicht - aufgebracht auf die Kathode - ein essenzielles Kriterium für breitbandige und annähernd winkelunabhängige Lichtemission. Der Schwerpunkt im Hinblick auf die Untersuchung von hergestellten Dioden liegt in der Optimierung der organischen Schichtstrukturen, um hohe Effizienzen sowie exzellente warmweiße Farbqualität zu erreichen. Im Rahmen der Optimierung von hybriden Schichtstrukturen basierend auf drei Emittermaterialien resultiert die Verwendung eines kombinierten Aluminium-Silber Anodenspiegels in einer Lichtausbeute von 13.3 lm/W und einer externen Quanteneffizienz von 5.3 %.Eine optische Analyse mit Hilfe von Simulationen zeigt eine überlegene Stellung hinsichtlich der internen Quanteneffizient verglichen mit bottom-emittierenden Dioden ähnlicher Schichtstruktur. Die Dioden zeigen eine verstärkte vorwärts gerichtete Emission im Vergleich zu einem idealen Lambertschen Emitter, welche in hohem Maße für Beleuchtungsanwendungen erwünscht ist. Es kann eine ausgezeichnete Farbqualität erreicht werden - insbesondere für Dioden basierend auf einer reinen Aluminiumanode - mit Farbkoordinaten nahe der Planckschen Strahlungskurve und Farbwiedergabeindizes bis zu 77. Die weitere Einführung eines zusätzlichen gelben Emittermaterials verbessert die Lichtausbeute auf Werte von 16.1 lm/W und die externe Quanteneffizient auf 5.9 %. Mit der Wahl eines voll-phosphoreszenten Ansatzes unter der Verwendung eines orange-roten, hellblauen und grünen Emittermaterials werden Lichtausbeuten von 21.7 lm/W und externe Quanteneffizienten von 8.5 % erzielt. Damit werden Farbkoordinaten von (x, y) = (0.41, 0.45) erreicht. Darüberhinaus zielt die Verwendung von verschiedenen kristallinen Deckschichten und alternativen Kathodenmaterialien auf eine Streuung des ausgekoppelten Lichts ab, was die Winkelabhängigkeit der Emission vermindern soll. Experimente mit dem kristallisierenden Material BPhen und dünnen Filmen aus Kohlenstoffnanoröhren werden dabei durchgeführt. Geheizte BPhen Deckschichten mit einer Schichtdicke von 250 nm zeigen eine geringere Farbverschiebung verglichen mit einer NPB Referenzdeckschicht. Die Verwendung von Kohlenstoffnanoröhren als Kathode führt zu einer breitbandigen weißen Emission bei einer Kavitätsschichtdicke von 160 nm. Schließlich werden weiße top-emittierende organische Leuchtdioden erfolgreich auf Metallsubstraten prozessiert. Ein Vergleich von drei- und vierfarb-basierten hybriden Bauteilen zeigt ähnliche Leistungsmerkmale für Dioden auf Glas- und Metallsubstraten. Während wiederholten mechanischen Biegeexperimenten mit weißen Dioden auf 0.3 mm dicken flexiblen Alanodsubstraten können Biegeradien bis zu 1.0 cm ohne Bauteilausfall realisiert werden

    Resonant Behaviour of Pulse Generators for the Efficient Drive of Optical Radiation Sources Based on Dielectric Barrier Discharges

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    Dielectric barrier discharge (DBD) excimer lamps emit vacuum-UV optical radiation. This work presents novel methods for efficiently operating DBDs with short, high-voltage pulses. Transformer-less systems utilising SiC power semiconductor switches are presented. Pulse frequencies of up to 3.1 MHz and peak inverter efficiencies of 92 % were achieved. The work encloses both mathematical backgrounds of pulsed resonant circuits and practical implementation of low-inductive power stages

    Electrical, Optical and acoustic diagnostics of atmospheric pressure gas discharges

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    This thesis presents original diagnostic investigations of atmospheric pressure gaseous discharges, operating in owing helium and helium with low concentrations (0.1 - 1 %) of gas admixtures, together with novel biomedical surface functionalisations. The initial body of this work focuses on comprehensive electrical and optical diagnostics of the operation of an industrial scale dielectric barrier discharge (DBD), maintained in a 10 l/min w of both helium and helium with 1% admixed oxygen. The experimental results reveal a coupling between the power dissipated in the discharge and the discharge homogeneity which, in turn, correlates to a shift in the power supply operating frequency and species optical emission intensities. The shift in the operating frequency is shown to be dependent upon increased charge deposition on the electrodes, as the input power is increased, thus changing the overall system capacitance through charge-voltage LIssajous gure analyses. Furthermore it is demonstrated that the gas temperature did not exceed approximately 380-410 K over the full parameter space, in the helium discharge, through model tting of the rst negative system of the N+2 band around 391.4 nm. A real-time, PC based monitoring diagnostic system has been developed which is used to perform long term analyses of a laboratory DBD chamber in helium and helium with 0.1% admixtures of both oxygen and nitrogen. Post analysis of the results, through multivariate analysis of the large experimental datasets, show that rapid system characterisations are faciltated using this method, the outcomes of which are compared with both global and uid model outputs within the literature. Passive acoustic diagnostics of a plasma jet system, together with signal analysis in the time, frequency and time-frequency domains are explored. Here it is found that ow induced mode transitions from buoyant, through laminar, to turbulent regimes may be identied using time-frequency scalogram plots. It is shown that the scalogram plots may also be used to identify the point at which power coupling together with the plume length are maximised. The transition into a fully turbulent plume structure is shown to be accompanied by low frequency acoustic signals which modulate the acoustic rst harmonic in the time-frequency domain. Moreover, a non invasive measurement of the power coupled into the discharge is demonstrated through passive acoustic sensing whilst the jet ow is laminar. Finally, surface modications of disposable plastics for biosensor applications are performed. In this work it is shown that the density of packing of both 40 nm and 80 nm gold nanoparticles may be tailored, through variation of the gas input ow rate of a linear eld jet, in order to enhance the optical signal according to the Mie theory for light extinction at a metal nanoparticle interface. The functionalisation using long chain polethyleneglycol has also been demonstrated to provide a protein repellent surface for non-specic protein binding reduction

    Proceedings of the International Workshop on: "Status, Prospects and Strategies for LEDs in General Lighting" - Ispra, Italy, 3-4 May 2007

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    This book contains the Proceedings of the International Workshop on "Status, Prospects and Strategies for LEDs in General Lighting", Ispra, Italy, 3-4 May 2007. The European Commission DG-Joint Research Centre organised a workshop focused on the latest R&D, market information, and application on LED for general lighting, in order to gather the latest information to the topic. Researchers, market analysts, LED manufacturers, luminaire manufactures and lighting experts were invited to contribute their views on the possible use of LEDs for general lighting. The presentations were made by the leading experts and market actors and covered the technical and commercial advances in the LED technology developed for lighting applications, as well as EU policies and programmes supporting energy efficient lighting.JRC.H.8-Renewable energie

    NASA Tech Briefs Index, 1978

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    Approximately 601 announcements of new technology derived from the research and development activities of the National Aeronautics and Space Administration are presented. Emphasis is placed on information considered likely to be transferrable across industrial, regional, or disciplinary lines. Subject matter covered includes: electronic components and circuits; electron systems; physical sciences; materials; life sciences; mechanics; machinery; fabrication technology; and mathematics and information sciences
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