Browsing by Subject "Decay (organic)"

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    Efficiency of sound energy decay analysis in auditoria
    (Institute of Acoustics, 2023-09) Xiang, N.; Gül, Zühre Sü
    Recent auditorium acoustics practice has included coupled-volume systems in several performing arts venues. This has stimulated research activities on acoustics in the coupled-volume systems. Based on experimentally measured room impulse responses acquired from existing auditoria, and several historically significant worship spaces, this paper addresses the challenges of analysing single-slope and multiple-slope sound energy decays often encountered in the experimentally measured room impulse responses in these venues. The analysis engages a parametric model of Schroeder decay functions, that decomposes the Schroeder decay data into single or multiple exponential decays along with a noise term. The model has been well validated using many experimental data. Several advanced analysis methods based on the decay model, such as nonlinear regressions, Bayesian probabilistic inference, and artificial neural networks have emerged to cope with analysis challenges raised in auditorium acoustics practice. This paper discusses conditions of implementing Schroeder integration for a higher efficiency of the numerical analysis and clarifies some unreasonable expectations/interpretations of Schroeder decay data. © 2023 Institute of Acoustics. All rights reserved.
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    Enhanced optical characteristics of light emitting diodes by surface plasmon of Ag nanostructures
    (SPIE, 2011) Jang L.-W.; Ju J.-W.; Jeon J.-W.; Jeon, D.-W.; Choi J.-H.; Lee, S.-J.; Jeon, S.-R.; Baek J.-H.; Sarı, Emre; Demir, Hilmi Volkan; Yoon H.-D.; Hwang, S.-M.; Lee I.-H.
    We investigated the surface plasmon coupling behavior in InGaN/GaN multiple quantum wells at 460 nm by employing Ag nanostructures on the top of a roughened p-type GaN. After the growth of a blue light emitting diode structure, the p-GaN layer was roughened by inductive coupled plasma etching and the Ag nanostructures were formed on it. This structure showed a drastic enhancement in photoluminescence and electroluminescence intensity and the degree of enhancement was found to depend on the morphology of Ag nanostructures. From the time-resolved photoluminescence measurement a faster decay rate for the Ag-coated structure was observed. The calculated Purcell enhancement factor indicated that the improved luminescence intensity was attributed to the energy transfer from electron-hole pair recombination in the quantum well to electron vibrations of surface plasmon at the Ag-coated surface of the roughened p-GaN. © 2011 SPIE.