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    Wyświetlanie 1-9 z 9
    Tytuł:
    Numerical analysis of the compositional graded quaternary barrier AlGaN-based ultraviolet-C light-emitting diode
    Autorzy:
    Malik, S.
    Usman, Muhammad
    Hussain, M.
    Munsif, M.
    Khan, S.
    Rasheed, S.
    Ali, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1818198.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
    Tematy:
    ultraviolet
    light-emitting diodes
    efficiency
    quantum wells
    Opis:
    The compositional graded quaternary barriers (GQBs) instead of ternary/conventional quantum barriers (QBs) have been used to numerically enhance the efficiency of AlGaN-based ultraviolet light-emitting diode (LED). The performance of LED with GQBs is examined through carrier concentrations, energy band diagrams, radiative recombination, electron and hole flux, internal quantum efficiency (IQE), and emission spectrum. As a function of the operating current density, a considerable reduction in efficiency droop is observed in the device with composition-graded quaternary barriers as compared to the conventional structure. The efficiency droop in case of a conventional LED is ~77% which decreased to ~33% in case of the proposed structure. Moreover, the concentration of electrons and holes across the active region in case of the proposed structure is increased to ~156% and ~44%, respectively
    Źródło:
    Opto-Electronics Review; 2021, 29, 3; 80--84
    1230-3402
    Pojawia się w:
    Opto-Electronics Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Structure equation as novel strategy for optimum reflector design
    Autorzy:
    Ou, Chung-Jen
    Powiązania:
    https://bibliotekanauki.pl/articles/174423.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    illumination design
    light-emitting diodes
    structure equation
    Opis:
    The optimal use of energy resources is the central dogma for green technology and bio-optics. Reflectors provide a simple and fundamental structure for energy transport from a light emitting diode (LED) chip, and an appropriately designed reflector can reduce the fabrication cost of secondary optics for the LED. This paper demonstrates the role of three proposed reflector geometric factors in the two performance metrics – uniformity and collected energy (power), for designing LED reflectors. Through canonical factor analysis, a linear structure equation for LED reflector is suggested, and the methodology for designing the optimal shape is discussed. In addition, a generalized factor and a synthesis response are proposed for a more comprehensive investigation of optical performance. Results indicate a key parameter for balancing the optical performance, and the effects of various parameters and the trade-offs are revealed.
    Źródło:
    Optica Applicata; 2020, 50, 1; 95-110
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical analysis of the compositional graded quaternary barrier AlGaN-based ultraviolet-C light-emitting diode
    Autorzy:
    Malik, S.
    Usman, Muhammad
    Hussain, M.
    Munsif, M.
    Khan, S.
    Rasheed, S.
    Ali, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1818193.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
    Tematy:
    ultraviolet
    light-emitting diodes
    efficiency
    quantum wells
    Opis:
    The compositional graded quaternary barriers (GQBs) instead of ternary/conventional quantum barriers (QBs) have been used to numerically enhance the efficiency of AlGaN-based ultraviolet light-emitting diode (LED). The performance of LED with GQBs is examined through carrier concentrations, energy band diagrams, radiative recombination, electron and hole flux, internal quantum efficiency (IQE), and emission spectrum. As a function of the operating current density, a considerable reduction in efficiency droop is observed in the device with composition-graded quaternary barriers as compared to the conventional structure. The efficiency droop in case of a conventional LED is ~77% which decreased to ~33% in case of the proposed structure. Moreover, the concentration of electrons and holes across the active region in case of the proposed structure is increased to ~156% and ~44%, respectively.
    Źródło:
    Opto-Electronics Review; 2021, 29, 3; 80--84
    1230-3402
    Pojawia się w:
    Opto-Electronics Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Concept and implementation of adaptive road lighting concurrent with vehicles
    Autorzy:
    Zalewski, S.
    Pracki, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/200253.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    lighting technology
    road lighting
    lighting control
    light emitting diodes
    Opis:
    The paper presents the authors’ concept of an adaptive road lighting that is concurrent with vehicles moving on roads. The lighting system is based on luminaires with light emitting diodes. The authors describe the operation of the adaptive road lighting system and point out benefits and limitations of the solution. The theoretical considerations are supported by an analysis of the installed and working system that was implemented at Bożeny street in Poznan, Poland. The system was also evaluated by the residents living near the street.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2019, 67, 6; 1117-1124
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Design of LED collimator for uniform illumination using two freeform lenses
    Autorzy:
    Zeng, J.
    Li, X.
    Ge, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/173429.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    illumination design
    lenses
    light-emitting diodes
    optical design
    high uniformity
    Opis:
    Regulating the illuminance distribution of an LED collimator to produce a uniform illumination in both the near field and the far field is a challenge in illumination design. In this paper, we present an effective method for designing two separated freeform lenses to control the illuminance distribution and the direction of the rays from the LED. The first lens redistributes the ray energy, and the second one collimates them to obtain a uniform collimated illumination. According to the conservation law of energy, Snell’s law, Fermat’s law and tangent-plane iterative method, the two freeform surfaces could be calculated simultaneously. The simulation results show that the two freeform lenses can control most of rays into an angle within ±1.5° for an LED with 1 × 1 mm size. The illuminance uniformities are higher than 0.9 in both the near field and the far field.
    Źródło:
    Optica Applicata; 2018, 48, 3; 413-420
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Selected metrology problems implied by the application of LED technology in lighting
    Wybrane problemy metrologiczne implikowane stosowaniem technologii LED w oświetleniu
    Autorzy:
    Błaszczak, U. J.
    Zając, A. S.
    Powiązania:
    https://bibliotekanauki.pl/articles/408716.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
    Tematy:
    light emitting diodes
    measurement
    lighting technology
    diody elektroluminescencyjne
    pomiary
    technika świetlna
    Opis:
    High power LEDs replace traditional light sources in all possible lighting applications, causing significant problems in assessing the quality of lighting. This issue is not limited only to the construction aspects of the measuring equipment, but also has a cognitive dimension. The article presents an overview of the current state of knowledge on color rendering and evaluation of discomfort glare in relation to the widespread use of LEDs in lighting. Some selected parameters developed copyright sources with LED sets. Basic limitations in UGR measurement were indicated
    Diody świecące dużej mocy zastępują klasyczne źródła światła właściwie we wszystkich możliwych aplikacjach oświetleniowych, co powoduje znaczne problemy w ocenie jakości oświetlenia. Zagadnienie to nie sprowadza się wyłącznie do aspektów konstrukcyjnych aparatury pomiarowej, lecz także ma wymiar poznawczy. W artykule przedstawiono przegląd aktualnego stanu wiedzy na temat oddawania barw oraz oceny olśnienia przykrego w odniesieniu do powszechnego stosowania diod LED w oświetleniu. Omówiono wybrane parametry opracowywanych autorskich źródeł z zestawami LED. Wskazano podstawowe ograniczenia w technice pomiarów UGR.
    Źródło:
    Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska; 2016, 3; 6-11
    2083-0157
    2391-6761
    Pojawia się w:
    Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Effect of Light-Emitting Diodes Illumination Period and Light Intensity on High Rate Algal Reactor System in Laundry Wastewater Treatment
    Autorzy:
    Tangahu, B. V.
    Triatmojo, A.
    Purwanti, I. F.
    Kurniawan, S. B.
    Powiązania:
    https://bibliotekanauki.pl/articles/123276.pdf
    Data publikacji:
    2018
    Wydawca:
    Polskie Towarzystwo Inżynierii Ekologicznej
    Tematy:
    algae
    Chlorella vulgaris
    laundry wastewater
    illumination period
    light-emitting diodes
    light intensity
    microalgae
    Opis:
    Wastewater that contains high concentration of nutrients can create instability in water ecosystem if left untreated. Laundry wastewater contains nutrients in high concentration. The nutrients that commonly found in laundry wastewater are nitrogen and phosphorus. This study had a purpose to determine the effect of illumination period and light intensity for the removal of Chemical Oxygen Demand (COD), Nitrogen-ammonia (NH3-N), and phosphate (P) content using Chlorella vulgaris in High Rate Algal Reactor (HRAR) treatment. Variables that used were exposure period of 12 and 24 hours and light intensity of 2000–3000 Lux, 4000–5000 Lux, and 6000–7000 lux. The parameters tested to determine the efficiency of nutrient removal were COD, Nitrogen-ammonia, phosphate and Chlorophyll α to determine the condition of algae development. The results showed that the highest nutrient removal were obtained by the reactor with 24 hours illumination period with light intensity of 6000–7000 Lux that was capable of removing 54.63% of COD, and 22.15% of P. The 12-hour illumination period was better in terms of NH3-N removal, up to 50.07%. On the basis of the of statistic test result, the illumination period did not significantly influence the removal efficiency of COD, NH3-N and P indicated by P-value >0.05, while the light intensity significantly affect the removal of COD and NH3-N showed by P value <0.05.
    Źródło:
    Journal of Ecological Engineering; 2018, 19, 6; 170-175
    2299-8993
    Pojawia się w:
    Journal of Ecological Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Spectrally tunable light source based on light-emitting diodes for custom lighting solutions
    Autorzy:
    Burgos-Fernandez, F. J.
    Vilaseca, M.
    Perales, E.
    Herrera-Ramirez, J. A.
    Martinez-Verdu, F. M.
    Pujol, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/173803.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    solid state lighting
    light-emitting diodes
    CIE standard illuminants
    minimization algorithm
    customized lighting design
    radiometry
    Opis:
    This study describes a novel spectral LED-based tunable light source used for customized lighting solutions, especially for the reconstruction of CIE (Commission Internationale de l'Eclairage) standard illuminants. The light source comprises 31 spectral bands ranging from 400 to 700 nm, an integrating cube and a control board with a 16-bit resolution. A minimization algorithm to calculate the weighting values for each channel was applied to reproduce illuminants with precision. The differences in spectral fitting and colorimetric parameters showed that the reconstructed spectra were comparable to the standard, especially for the D65, D50, A and E illuminants. Accurate results were also obtained for illuminants with narrow peaks such as fluorescents (F2 and F11) and a high-pressure sodium lamp (HP1). In conclusion, the developed spectral LED-based light source and the minimization algorithm are able to reproduce any CIE standard illuminants with a high spectral and colorimetric accuracy able to advance available custom lighting systems useful in the industry and other fields such as museum lighting.
    Źródło:
    Optica Applicata; 2016, 46, 1; 117-129
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Iprovements OLED operation due to using additional layers
    Poprawa działania diod typu OLED przy wykorzystaniu dodatkowych warstw
    Autorzy:
    Hotra, Z.
    Volynyuk, D.
    Voznyak, L.
    Kostiv, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/159361.pdf
    Data publikacji:
    2010
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Elektrotechniki
    Tematy:
    organiczna dioda elektroluminescencyjna
    dioda
    warstwa transportowa
    elektroluminescencja
    organic light emitting diodes
    hole transport layer
    electroluminescent
    Opis:
    In this work we proposed OLED structure with NiPc as hole transport layer. Current-voltage and luminance characteristic of ITO/NiPc/Alg3/PEGTE/Al and ITO/Alg3/PEGTE/Al structures were also investigated. It was shown that using NiPc as hole transport layer reduced operating voltage and improved OLED performance.
    W pracy została zaproponowana struktura OLED z warstwą NiPc jako warstwą transportową. Zbadano jej charakterystyki prądowo-napięciową oraz luminancyjną na podłożu ITO/NiPc/Alg3/PEGTE/Al i ITO/Alg3/PEGTE/Al. Wykazano, że używając związku NiPc jako warstwy transportowej zmniejsza się napięcie pracy OLED jednocześnie poprawiając jego wydajność.
    Źródło:
    Prace Instytutu Elektrotechniki; 2010, 247; 19-24
    0032-6216
    Pojawia się w:
    Prace Instytutu Elektrotechniki
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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