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@PHDTHESIS{Brger:1049044,
      author       = {Börger, Kristian},
      title        = {{I}mprovement and {V}alidation of {V}isibility {M}odels in
                      {F}ire {S}afety},
      volume       = {74},
      school       = {Wuppertal},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2025-05139},
      isbn         = {978-3-95806-857-5},
      series       = {Schriften des Forschungszentrums Jülich IAS Series},
      pages        = {ix, 97},
      year         = {2025},
      note         = {Dissertation, Wuppertal, 2024},
      abstract     = {In case of fire, smoke poses the major threat to the
                      occupants of public or residential buildings. Notably,
                      besides the smoke’s toxicity, reduced visibility can
                      prevent people from safe egress. Commonly applied fire
                      models to assess visibility at the building’s design stage
                      often rely on input quantities that could not be
                      consistently validated across multiple studies. Furthermore,
                      the common interpretation of simulation results does not
                      accurately mirror real-world conditions. This dissertation
                      aims to develop robust methods for the experimental
                      validation of visibility models and the enhanced
                      post-processing of simulation results in the context of
                      performance based design. The thesis comprises three
                      publications exploring these topics. The first publication
                      introduces the improvement of an existing photometric method
                      (LEDSA) to measure temporally and spatially resolved
                      extinction coe!cients in laboratory test fires. LEDSA
                      involves capturing the smoke induced change in intensity of
                      LEDs using consumer digital cameras. Validating against the
                      established MIREX measurement system revealed, that
                      utilizing RAW image data significantly improves measurement
                      accuracy compared to the previously used JPG files. While
                      using higher quality LEDs helped to increase reproducibility
                      of the measurements, further uncertainties of the model and
                      the experimental setup could be identified. In the second
                      publication, LEDSA is compared on multiple test fires to the
                      Radiance Method, which was developed at the University of
                      Waterloo. It involves measuring the contrast on adjacent
                      light and dark areas in image or video footage. The Radiance
                      Method measurements align well with LEDSA and the MIREX for
                      smoke from n-heptane pool fires, with much lower
                      computational e"ort than LEDSA. However, only LEDSA was in
                      line with the MIREX measurements for wood smouldering fires,
                      while the Radiance Method could only reproduce patterns of
                      the reference measurement. The third publication shifts
                      focus from model validation to application, introducing
                      visibility maps as a novel approach to assess visibility in
                      performance based design. By post-processing existing data
                      from fire simulations, the maps indicate areas where exit
                      signs remain visible along the route of egress. Integrating
                      the extinction coe!cient along the line of sight allows
                      applying Jin’s empirical correlation to non-homogeneous
                      smoke environments, providing for a more realistic
                      assessment of visibility, than the classical way of treating
                      it as a local quantity. Visibility maps can also account for
                      additional factors like view angle and visual obstruction of
                      exit signs.},
      cin          = {IAS-7},
      cid          = {I:(DE-Juel1)IAS-7-20180321},
      pnm          = {5111 - Domain-Specific Simulation $\&$ Data Life Cycle Labs
                      (SDLs) and Research Groups (POF4-511)},
      pid          = {G:(DE-HGF)POF4-5111},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      doi          = {10.34734/FZJ-2025-05139},
      url          = {https://juser.fz-juelich.de/record/1049044},
}