@article{BungValero2018,
  author    = {Bung, Daniel Bernhard and Valero, Daniel},
  title     = {Re-aeration on stepped spillways with special consideration of entrained and entrapped air},
  series = {Geosciences},
  volume    = {8},
  journal   = {Geosciences},
  number    = {9},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2076-3263},
  pages     = {Article number 333},
  year      = {2018},
  abstract  = {As with most high-velocity free-surface flows, stepped spillway flows become self-aerated when the drop height exceeds a critical value. Due to the step-induced macro-roughness, the flow field becomes more turbulent than on a similar smooth-invert chute. For this reason, cascades are oftentimes used as re-aeration structures in wastewater treatment. However, for stepped spillways as flood release structures downstream of deoxygenated reservoirs, gas transfer is also of crucial significance to meet ecological requirements. Prediction of mass transfer velocities becomes challenging, as the flow regime differs from typical previously studied flow conditions. In this paper, detailed air-water flow measurements are conducted on stepped spillway models with different geometry, with the aim to estimate the specific air-water interface. Re-aeration performances are determined by applying the absorption method. In contrast to earlier studies, the aerated water body is considered a continuous mixture up to a level where 75\% air concentration is reached. Above this level, a homogenous surface wave field is considered, which is found to significantly affect the total air-water interface available for mass transfer. Geometrical characteristics of these surface waves are obtained from high-speed camera investigations. The results show that both the mean air concentration and the mean flow velocity have influence on the mass transfer. Finally, an empirical relationship for the mass transfer on stepped spillway models is proposed.},
  language  = {en}
}
@article{BungValero2016,
  author    = {Bung, Daniel Bernhard and Valero, Daniel},
  title     = {Optical flow estimation in aerated flows},
  series = {Journal of Hydraulic Research},
  volume    = {54},
  journal   = {Journal of Hydraulic Research},
  number    = {5},
  publisher = {Taylor \& Francis},
  address   = {London},
  doi       = {10.1080/00221686.2016.1173600},
  pages     = {575 -- 580},
  year      = {2016},
  abstract  = {Optical flow estimation is known from Computer Vision where it is used to determine obstacle movements through a sequence of images following an assumption of brightness conservation. This paper presents the first study on application of the optical flow method to aerated stepped spillway flows. For this purpose, the flow is captured with a high-speed camera and illuminated with a synchronized LED light source. The flow velocities, obtained using a basic Horn-Schunck method for estimation of the optical flow coupled with an image pyramid multi-resolution approach for image filtering, compare well with data from intrusive conductivity probe measurements. Application of the Horn-Schunck method yields densely populated flow field data sets with velocity information for every pixel. It is found that the image pyramid approach has the most significant effect on the accuracy compared to other image processing techniques. However, the final results show some dependency on the pixel intensity distribution, with better accuracy found for grey values between 100 and 150.},
  language  = {en}
}
@article{CheenakulaGriebelMontagetal.2023,
  author    = {Cheenakula, Dheeraja and Griebel, Kai and Montag, David and Gr{\"o}mping, Markus},
  title     = {Concept development of a mainstream deammonification and comparison with conventional process in terms of energy, performance and economical construction perspectives},
  series = {Frontiers in Microbiology},
  volume    = {14},
  journal   = {Frontiers in Microbiology},
  number    = {11155235},
  editor    = {Huang, Xiaowu},
  publisher = {Frontiers},
  issn      = {1664-302X},
  doi       = {10.3389/fmicb.2023.1155235},
  pages     = {1 -- 15},
  year      = {2023},
  abstract  = {Deammonification for nitrogen removal in municipal wastewater in temperate and cold climate zones is currently limited to the side stream of municipal wastewater treatment plants (MWWTP). This study developed a conceptual model of a mainstream deammonification plant, designed for 30,000 P.E., considering possible solutions corresponding to the challenging mainstream conditions in Germany. In addition, the energy-saving potential, nitrogen elimination performance and construction-related costs of mainstream deammonification were compared to a conventional plant model, having a single-stage activated sludge process with upstream denitrification. The results revealed that an additional treatment step by combining chemical precipitation and ultra-fine screening is advantageous prior the mainstream deammonification. Hereby chemical oxygen demand (COD) can be reduced by 80\% so that the COD:N ratio can be reduced from 12 to 2.5. Laboratory experiments testing mainstream conditions of temperature (8-20°C), pH (6-9) and COD:N ratio (1-6) showed an achievable volumetric nitrogen removal rate (VNRR) of at least 50 gN/(m3∙d) for various deammonifying sludges from side stream deammonification systems in the state of North Rhine-Westphalia, Germany, where m3 denotes reactor volume. Assuming a retained Norganic content of 0.0035 kgNorg./(P.E.∙d) from the daily loads of N at carbon removal stage and a VNRR of 50 gN/(m3∙d) under mainstream conditions, a resident-specific reactor volume of 0.115 m3/(P.E.) is required for mainstream deammonification. This is in the same order of magnitude as the conventional activated sludge process, i.e., 0.173 m3/(P.E.) for an MWWTP of size class of 4. The conventional plant model yielded a total specific electricity demand of 35 kWh/(P.E.∙a) for the operation of the whole MWWTP and an energy recovery potential of 15.8 kWh/(P.E.∙a) through anaerobic digestion. In contrast, the developed mainstream deammonification model plant would require only a 21.5 kWh/(P.E.∙a) energy demand and result in 24 kWh/(P.E.∙a) energy recovery potential, enabling the mainstream deammonification model plant to be self-sufficient. The retrofitting costs for the implementation of mainstream deammonification in existing conventional MWWTPs are nearly negligible as the existing units like activated sludge reactors, aerators and monitoring technology are reusable. However, the mainstream deammonification must meet the performance requirement of VNRR of about 50 gN/(m3∙d) in this case.},
  language  = {en}
}
@article{DoeringKendrickLawson2013,
  author    = {D{\"o}ring, Bernd and Kendrick, C. and Lawson, R. M.},
  title     = {Thermal capacity of composite floor slabs},
  series = {Energy and buildings},
  volume    = {Vol. 67},
  journal   = {Energy and buildings},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1872-6178 (E-Journal); 0378-7788 (Print)},
  pages     = {531 -- 539},
  year      = {2013},
  language  = {en}
}
@article{DoeringRegerKuhnhenneetal.2015,
  author    = {D{\"o}ring, Bernd and Reger, Vitali and Kuhnhenne, Markus and Feldmann, Markus and Kesti, Jyrki and Lawson, Mark and Botti, Andrea},
  title     = {Steel solutions for enabling zero-energy buildings},
  series = {Steel Construction - Design and Research},
  volume    = {8},
  journal   = {Steel Construction - Design and Research},
  number    = {3},
  publisher = {Ernst \& Sohn},
  address   = {Berlin},
  issn      = {1867-0539},
  doi       = {10.1002/stco.201510029},
  pages     = {194 -- 200},
  year      = {2015},
  language  = {en}
}
@article{ErpicumCrookstonBombardellietal.2021,
  author    = {Erpicum, Sebastien and Crookston, Brian M. and Bombardelli, Fabian and Bung, Daniel Bernhard and Felder, Stefan and Mulligan, Sean and Oertel, Mario and Palermo, Michele},
  title     = {Hydraulic structures engineering: An evolving science in a changing world},
  series = {Wires Water},
  volume    = {8},
  journal   = {Wires Water},
  number    = {2},
  publisher = {Wiley},
  address   = {Weinheim},
  issn      = {2049-1948},
  doi       = {10.1002/wat2.1505},
  year      = {2021},
  language  = {en}
}
@article{FellinKingKirschetal.2010,
  author    = {Fellin, Wolfgang and King, Julian and Kirsch, Ansgar and Oberguggenberger, Michael},
  title     = {Uncertainty modelling and sensitivity analysis of tunnel face stability},
  series = {Structural safety},
  volume    = {32},
  journal   = {Structural safety},
  number    = {6},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0167-4730},
  doi       = {10.1016/j.strusafe.2010.06.001},
  pages     = {402 -- 410},
  year      = {2010},
  abstract  = {This paper proposes an approach to the choice and evaluation of engineering models with the aid of a typical application in geotechnics. An important issue in the construction of shallow tunnels, especially in weak ground conditions, is the tunnel face stability. Various theoretical and numerical models for predicting the necessary support pressure have been put forth in the literature. In this paper, we combine laboratory experiments performed at the University of Innsbruck with current methods of uncertainty and sensitivity analysis for assessing adequacy, predictive power and robustness of the models. The major issues are the handling of the twofold uncertainty of test results and of model predictions as well as the decision about what are the influential input parameters.},
  language  = {en}
}
@article{GosslaSato1998,
  author    = {Gossla, Ulrich and Sato, R.},
  title     = {Present production circumstances of aggregate in Germany / Sato, R.; Gossla, U.},
  series = {Cement \& Concrete (1998)},
  journal   = {Cement \& Concrete (1998)},
  pages     = {146 -- 153},
  year      = {1998},
  language  = {en}
}
@article{Hoettges1990,
  author    = {H{\"o}ttges, J{\"o}rg},
  title     = {Turbulence and Mixing Mechanics in Compound Open Channel Flow / Arnold, Uwe; H{\"o}ttges, J{\"o}rg; Rouv{\´e}, Gerhard},
  series = {On cutoff ratios of curved channels : paper presented at the 23rd Congress of the IAHR, Ottawa, Canada, August 21 - 25, 1989 / G. J. Klaassen; B. H. J.van Zanten},
  journal   = {On cutoff ratios of curved channels : paper presented at the 23rd Congress of the IAHR, Ottawa, Canada, August 21 - 25, 1989 / G. J. Klaassen; B. H. J.van Zanten},
  publisher = {Delft Hydraulics},
  address   = {Delft},
  year      = {1990},
  language  = {en}
}
@article{Hoettges1992,
  author    = {H{\"o}ttges, J{\"o}rg},
  title     = {A Full Finite Element Solution for the Unsteady Advection-Diffusion Equation},
  series = {Computational methods in water resources : [proceedings of the Ninth International Conference on Computational Methods in Water Resources held at the University of Colorado at Denver, U.S.A., in June 1992] / ed.: T. F. Russell},
  journal   = {Computational methods in water resources : [proceedings of the Ninth International Conference on Computational Methods in Water Resources held at the University of Colorado at Denver, U.S.A., in June 1992] / ed.: T. F. Russell},
  publisher = {Computational Mechanics Publications [u.a.]},
  address   = {Southampton [u.a.]},
  isbn      = {185312169X},
  year      = {1992},
  language  = {en}
}