The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Erkki Ikonen - One of the best experts on this subject based on the ideXlab platform.
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Method for analysing Luminous Intensity of light-emitting diodes
Measurement Science and Technology, 2006Co-Authors: Pasi Manninen, Jari Hovila, Petri Kärhä, Erkki IkonenAbstract:Light-emitting diodes (LEDs) have built-in lenses that enable spatially limited light beams. The use of lenses increases the Luminous Intensity levels, but complicates accurate LED Intensity measurements. A novel method for determining the Luminous Intensity of the LED is proposed. The method based on a modified inverse-square law describes the behaviour of an LED in terms of its Luminous Intensity, the radius of the virtual source and the location of the virtual source. The applicability of the method was tested for 17 LED types with different packages, angular Intensity distributions and power levels. When applying the new method to the measurement data, instead of the inverse-square law of the point source, the distance dependence of apparent LED Luminous Intensity of up to 47% reduced to statistical variation of less than 1%.
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Determination of Luminous Intensity of light-emitting diodes with modified inverse-square law
2005Co-Authors: Petri Kärhä, Jari Hovila, Lauri Seppälä, Erkki IkonenAbstract:We present a method that can be used for accurate analysis of Luminous Intensity measurements of LEDs. The method is based on the modified inverse-square law where information on the LED behavior is included in three parameters; Luminous Intensity, radius of the image of the source, and location of the image of the source. The method was studied with 17 different LEDs. The standard deviation of the fitting was typically less than 1%.
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Realization of the unit of Luminous Intensity at the HUT
Metrologia, 2000Co-Authors: P Toivanen, Farshid Manoochehri, Erkki IkonenAbstract:A description is presented of an upgraded trap-detector-based realization of the units of Luminous Intensity (candela) and illuminance (lux) at the Helsinki University of Technology (HUT). The realization is accomplished using a reference photometer, a light source and a distance-measurement system. A thorough characterization is presented of the reference photometer, consisting of a reflection trap detector, a temperature-controlled V(λ) filter and a high-precision aperture. The maintenance of the units is described. An updated uncertainty budget of the realization is given. Two of the three main uncertainty components of our earlier realizations have been significantly decreased. The uncertainty analysis indicates a relative expanded uncertainty of 2.2 × 10-3 for the realization of the candela and 1.8 × 10-3 for that of the lux. The HUT has participated in three international measurement comparisons, whose results are reviewed. According to the results, the HUT candela deviates by +4.0 × 10-3 from the candela of the Swedish National Testing and Research Institute with an expanded uncertainty of 10-2, -2.7 × 10-3 from that of the National Physical Laboratory (UK) with an expanded uncertainty of 5.6 × 10-3 and -3.3 × 10-3 from the world mean with an expanded uncertainty of 5.9 × 10-3.
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International comparison of Luminous Intensity units between the NPL (UK) and the HUT (Finland)
Metrologia, 1999Co-Authors: T M Goodman, P Toivanen, H. Nyberg, Erkki IkonenAbstract:The results are presented of an international comparison of the SI photometric base unit, the candela, as realized and maintained at the National Physical Laboratory (NPL, UK) and the Metrology Research Institute at Helsinki University of Technology (HUT, Finland). Both laboratories base their Luminous Intensity units on absolutely calibrated photometers and these, as well as the more traditional transfer standard lamps, were used for the comparison. The results show that the units established and maintained at the two laboratories agree to well within the expanded uncertainty.
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Comparison of Luminous-Intensity scales based on trap detectors and incandescent lamps
Metrologia, 1995Co-Authors: L Liedquist, Erkki Ikonen, H FagerlundAbstract:New Luminous-Intensity scales have been developed in Finland and Sweden based on silicon trap detectors having responsivities compared with an absolute cryogenic radiometer at a wavelength of 543,516 nm. The low reflectance of the trap device makes it possible to use a V(?) filter in conjunction with the trap where the filter is separately characterized in transmittance. The new scales were compared with the scale currently in use in Sweden, which is based on incandescent lamps calibrated by the Bureau International des Poids et Mesures (BIPM). The agreement of the scales is generally within ?1%. The Finnish scale was typically 0,2% to 0,6% below the BIPM-based scale, and the trap-based scale of Sweden is typically 0% to 0,5% below the BIPM-based scale when compared at a measurement distance of 4 m. Different sizes of aperture and different distances to the source showed variations up to ?1%. The transmittances of the V(?) filters were measured separately by the two institutes and showed an agreement better than 0,1% in the colour-correction factor.
Akiko Nakata - One of the best experts on this subject based on the ideXlab platform.
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Luminous Intensity for Traffic Signals: A Scientific Basis for Performance Specifications
1999Co-Authors: John D. Bullough, Peter Boyce, Andrew Bierman, Kathryn M. Conway, K. Huang, Claudia M. Hunter, Akiko NakataAbstract:The objective of this project was to evaluate light emitting diode (LED) traffic signals with various lighting Intensity as compared with incandescent traffic signals of the same nominal color. In addition, the traffic signals were to be evaluated against the Luminous Intensity of 200 mm, which is the Luminous Intensity recommended by the Institute of Transportation Engineers. It was found that there is no difference in mean number of missed signals, mean reaction time, and percentage of correct color identification (and rated conspicuity and brightness) for an LED and incandescent traffic signal of the same nominal color and the same luminance.
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Luminous Intensity for Traffic Signals: A Scientific Basis for Performance Specifications - Appendices
1999Co-Authors: John D. Bullough, Peter Boyce, Andrew Bierman, Kathryn M. Conway, K. Huang, Claudia M. Hunter, Conan P. O'rourke, Akiko NakataAbstract:Luminous Intensity for Traffic Signals: A Scientific Basis for Performance Specifications - Appendices
John D. Bullough - One of the best experts on this subject based on the ideXlab platform.
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Luminous Intensity Requirements for Service Vehicle Warning Beacons
2015Co-Authors: John D. Bullough, Mark S. ReaAbstract:Flashing yellow warning beacons are used on a wide variety of service vehicles including highway construction vehicles, dump trucks, delivery vehicles, snow plows, and tow trucks. These lights serve as an important line of defense for several million U.S. workers in the transportation, construction and utilities sectors, who are overrepresented in terms of workplace fatalities. In order to understand visual responses to warning beacons varying in their Luminous Intensity characteristics, flashing yellow warning beacons were presented under laboratory conditions simulating daytime and nighttime roadway scenes. Response times to the onset of flashing and subjective ratings of beacon visibility and of the visibility of low-contrast objects in the scenes were measured. The results provide a preliminary basis for the development of quantitative specifications of warning beacon Luminous Intensity characteristics that ensure high levels of visibility under both daytime and nighttime conditions, while minimizing glare, especially at night.
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Luminous Intensity for Traffic Signals: A Scientific Basis for Performance Specifications
1999Co-Authors: John D. Bullough, Peter Boyce, Andrew Bierman, Kathryn M. Conway, K. Huang, Claudia M. Hunter, Akiko NakataAbstract:The objective of this project was to evaluate light emitting diode (LED) traffic signals with various lighting Intensity as compared with incandescent traffic signals of the same nominal color. In addition, the traffic signals were to be evaluated against the Luminous Intensity of 200 mm, which is the Luminous Intensity recommended by the Institute of Transportation Engineers. It was found that there is no difference in mean number of missed signals, mean reaction time, and percentage of correct color identification (and rated conspicuity and brightness) for an LED and incandescent traffic signal of the same nominal color and the same luminance.
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Luminous Intensity for Traffic Signals: A Scientific Basis for Performance Specifications - Appendices
1999Co-Authors: John D. Bullough, Peter Boyce, Andrew Bierman, Kathryn M. Conway, K. Huang, Claudia M. Hunter, Conan P. O'rourke, Akiko NakataAbstract:Luminous Intensity for Traffic Signals: A Scientific Basis for Performance Specifications - Appendices
Antoni Różowicz - One of the best experts on this subject based on the ideXlab platform.
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Adaptive Luminaire with Variable Luminous Intensity Distribution
Energies, 2020Co-Authors: M. Leśko, Henryk Wachta, Antoni Różowicz, Sebastian RóżowiczAbstract:The field of indoor lighting covers a wide range of lighting uses with varying requirements for lighting conditions to be satisfied by properly selected lighting equipment. The need to frequently change the arrangement of useable areas entails the necessity to adapt the lighting to new requirements. A good solution for reducing costs and saving time is a luminaire adjusting the Luminous flux and spatial Luminous Intensity distribution in a wide range. The authors present the concept of an adaptive luminaire and its construction assumptions. In addition, the results of studies on the development of the concept are shown together with conditions and limitations that influenced the construction of the luminaire. The analysis of the surface of the moveable reflector is presented, and the results of testing the luminaire prototype are compared with the results of simulation tests.
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A Concept of an Adaptive Luminaire with Variable Luminous Intensity Distribution
2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4), 2018Co-Authors: Marcin Lesko, Henryk Wachta, Krzysztof Baran, Antoni RóżowiczAbstract:The article presents an innovative concept of adaptive luminaire with variable Luminous Intensity distribution. It enables adjustment of photometric characteristic of luminaire to variable arrangement of the facility, including the quantitative regulation of Luminous flux and spatial distribution. A solution presented in this paper was developed as part of a research project titled “Development of the Intelligent Light Distribution System SOLLS ACTIVE SKY” and is the subject of patent application. The authors present the results of simulation tests in terms of the possibility of obtaining different Luminous Intensity distribution and lighting parameters on the working plane, with variable position relative to the arrangement of the luminaires. The use of a luminaire with variable Luminous Intensity distribution as part of an adaptive lighting system allows for quick and cost-free introduction of changes in the lighting of selected functional zones inside the facility. It is possible to adjust the lighting in case of changes in the size or position of the working plane, while the position of luminaire is constant.
Fernandes Machado - One of the best experts on this subject based on the ideXlab platform.
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Influence of Luminous Intensity on textile effluent photodegradation Influence of Luminous Intensity on textile effluent photodegradation Influence of Luminous Intensity on textile effluent photodegradation Influence of Luminous Intensity on textile
2005Co-Authors: Veronice Slusarski Santana, André Luís Alberton, Regina Camargo, Fernandes MachadoAbstract:Degradation tests were carried out to determine the Luminous Intensity influence on textile industry effluent photodegradation. TiO 2, Nb 2O5, Nb 2O5-TiO 2 and Nb 2O5/TiO 2 were used as photocatalysts. FTIR (Fourrier Transform Infrared) and TPR (Temperature Program Reduction) results showed interaction between different forms of the oxides in the Nb 2O5-TiO 2 and Nb 2O5/TiO 2 catalysts and the forming of a new phase in Nb 2O5-TiO 2. The reaction rate was significantly influenced by the Luminous Intensity. Luminous Intensity decrease caused decolourisation increase and COD reduction decrease, suggesting that the concentration of the hydroxyl groups, which are responsible for the chromophores groups degradation, is proportional to the Luminous Intensity. RESUMO. Influencia da intensidade luminosa na fotodegradacao de efluente textil. Testes de degradacao foram realizados com o objetivo de determinar a influencia da intensidade luminosa na fotodegradacao de um efluente industrial textil. Como fotocatalisadores foram utilizados TiO 2, Nb 2O5, Nb 2O5-TiO 2 e Nb 2O5/TiO 2. Os resultados de FTIR (Infravermelho com Transformada de Fourrier)e RTP (Reducao a Temperatura programada) mostraram a existencia de interacao entre os oxidos de forma diferenciada nos catalisadores Nb 2 O 5 -TiO 2 e Nb 2 O 5 /TiO 2 e a formacao de uma nova fase no Nb 2 O 5 -TiO 2 . A taxa de reacao foi significativamente influenciada pela intensidade luminosa. A reducao da intensidade luminosa ocasionou o aumento da descoloracao e a diminuicao da reducao de DQO, sugerindo que a concentracao dos grupos hidroxila, que sao responsaveis pela degradacao dos grupos cromoforos, e proporcional a intensidade luminosa. Palavras-chave: fotodegradacao, intensidade luminosa, TiO 2, Nb 2O5, efluente textil.
