@article{BetzoldDentel2022, author = {Betzold, Christina and Dentel, Arno}, title = {Smart integration of heat pumps by predictive controls}, series = {Heat Pumping Technologies Magazine}, volume = {40}, journal = {Heat Pumping Technologies Magazine}, number = {3}, doi = {https://doi.org/10.23697/7mmf-3f37}, pages = {25 -- 27}, year = {2022}, abstract = {The integration of heat pumps into a PV and battery system faces the challenge of sharing the available PV power among the actors. In order to coordinate this competition, a suitable energy concept, as well as the control, must match. In a cluster of eight terraced houses, an energy system has been implemented, which should represent a smart integration of heat pumps. To coordinate the interaction of the components, model predictive controls are used. The simulation shows very good results for the predictive controls, but the results cannot be replicated in total practice.}, language = {en} } @article{SchefflerModerSchrageetal.2023, author = {Scheffler, Holger and Moder, Michael and Schrage, Nico and Lippert, Kaj and Heß, Max and Rostan, Fabian and Carstensen, Dirk and K{\"o}hler, Albrecht and Schaarschmidt, Lars}, title = {Zusammenwirken von Planung und hydraulischer Untersuchung am HRB Weilers/Bracht}, series = {WASSERWIRTSCHAFT}, volume = {113}, journal = {WASSERWIRTSCHAFT}, number = {6}, publisher = {Springer Science and Business Media LLC}, issn = {0043-0978}, doi = {10.1007/s35147-023-1833-3}, pages = {44 -- 47}, year = {2023}, abstract = {Der Neubau eines Hochwasserr{\"u}ckhaltebeckens (HRB) erfordert umfangreiche hydraulische Untersuchungen. M{\"o}glichkeiten zur {\"U}berpr{\"u}fung und Optimierung einer wasserbaulichen Planung sind sowohl der physikalische Modellversuch als auch eine hydrodynamisch-numerische Str{\"o}mungsmodellierung. Fragestellungen zur Wirkungsweise und zu den Wechselwirkungen der Betriebseinrichtung eines HRB k{\"o}nnen so beantwortet werden. Der vorliegende Beitrag beschreibt das Zusammenwirken von Planung und hydraulischen Untersuchungen am Neubauprojekt HRB Weilers/Bracht in Hessen.}, language = {de} } @techreport{RoyFahnoeFarrieretal.2023, author = {Roy, Alastair and Fahn{\o}e, Kristian and Farrier, Alan and Heinrich, Marco and Kronb{\ae}k, Mette and Sowa, Frank}, title = {How the COVID-19 pandemic has affected the lives of homeless young people and welfare services in three European cities}, address = {Nuremberg/Copenhagen/Preston}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:92-opus4-18477}, pages = {3 -- 98}, year = {2023}, abstract = {At the beginning of the year 2020, the pandemic caused by COVID-19 reached Europe. European countries implemented restrictions on movement and public life in order to contain its spread. The pandemic, as well as these policy responses, altered everyday lives for people all over Europe. This research explores effects of the pandemic on the everyday lives and lived realities of homeless young people in three cities in different countries: Nuremberg (Germany), Copenhagen (Denmark) and Manchester (United Kingdom). We focus on young people between the ages of 18 and 29 who have experienced homelessness. In addition, we explore how three different social welfare organisations worked to provide practical and emotional support to homeless young people during the pandemic.}, language = {en} } @article{GundermannRaabRaabetal.2021, author = {Gundermann, Michael and Raab, Florian and Raab, Daniel and Botsch, Tilman}, title = {Investigation of the heat transfer coefficient during the condensation of small quantities of water vapour from a mixture with a high proportion of non-condensable gas in a horizontal smooth tube}, series = {International Journal of Heat and Mass Transfer}, volume = {170}, journal = {International Journal of Heat and Mass Transfer}, publisher = {Elsevier BV}, issn = {0017-9310}, doi = {10.1016/j.ijheatmasstransfer.2021.121016}, pages = {15}, year = {2021}, abstract = {During heat recovery of exhaust gas energy in a shell and tube heat exchanger, the exhaust gas is cooled down and the water vapour content may condense when the corresponding temperature is reached. In this case, a condensation heat exchanger allows recovering the latent heat in addition to the sensible heat and is therefore beneficial for a preferably high heat recovery. The database and algorithms for the design of this kind of apparatus are still nowadays quite week because only little experimental work is realized with condensation of water vapour from a mixture with a very high proportion of non-condensable gas in horizontal tubes. The actual research work improves this database with a considerable amount of experimental data and proposes a correlation for the prediction of the heat transfer coefficient in an exhaust gas heat exchanger in which parts of the gas humidity condense. All experiments were carried out under conditions, which are typical for this kind of heat exchangers, hence the presented results can be used for the design of condensation heat exchangers in industrial heat transfer systems. A gas inlet temperature of 120 °C, a range of the air-steam mixture Reynolds number 11,000 Re 31,000, three tube lengths between 1.87 m and 3.04 m, water vapour volume fractions of 7 \% to 14.5 \% as well as tube diameters of 22 mm and 28 mm were selected to derive the correlation. Furthermore, additional tube lengths (0.574 m, 0.973 m, 1.373 m) were investigated to determine the parameters influencing the condensation rate and comprehensive location profiles over the tube length. A correlation for a correction factor is derived, which enables to calculate the increase of the heat transfer coefficient due to condensation from the dry heat transfer coefficient without condensation. This dry heat transfer coefficient is calculated by the measured values in the inlet and outlet for a purely dry air-steam mixture cooling without condensation. The correction factor depend on the water vapour volume fraction, the Reynolds number and the geometry ratio between the inner diameter and the tube length.}, language = {en} } @article{BotschGoldsteinas2022, author = {Botsch, T. and Goldsteinas, A.}, title = {Unterdruckaufkohlung - Modellierung und Simulation der Eindringtiefe verschiedener Aufkohlungsgase in Sacklochbohrungen}, series = {HTM Journal of Heat Treatment and Materials}, volume = {57}, journal = {HTM Journal of Heat Treatment and Materials}, number = {5}, issn = {2194-1831}, doi = {10.1515/htm-2002-570507}, pages = {327-334}, year = {2022}, abstract = {Es wird ein Modell vorgestellt, mit dem f{\"u}r den Unterdruckaufkoh­lungsprozess die Eindringtiefe von Propan und Ethin in Sackloch­bohrungen vorhergesagt werden kann. Das Modell basiert auf Men­genbilanzen {\"u}berdas Gasvolumen in der Bohrung. Testrechnungenergaben eine gute {\"U}bereinstimmung zwischen dem berechneten Ver­lauf der Konzentration des Aufkohlungsgases in der Bohrung undder aus H{\"a}rtemessungen bestimmten Eindringtiefe. Die in demModell verwendeten Werte f{\"u}r die Aufkohlungswirkung bei der in derBohrung vorherrschenden geringen Propan- bzw. Ethinkonzentra­tion wurden gemessen und werden dargestellt. Aus den Messergeb­nissen wird deutlich, dass sich die Aufkohlungs wirkung von Propannur unwesentlich von der von Ethin unterscheidet und dass bereitsab einem Propan- oder Ethinanteil im Gas von ca. 20\% eine zufrie­denstellende Aufkohlung m{\"o}glich ist. F{\"u}r die industrielle Anwen­dung bedeutet dies, dass auch große und dicht gepackte Chargenmit Propan aufgekohlt werden k{\"o}nnen. Durch einen entsprechendgroßen Volumenstrom des zustr{\"o}menden Gases muss lediglich daf{\"u}rgesorgt werden, dass der Propangehalt im Zentrum der Chargegr{\"o}ßer als 20 \% ist. Modellrechnungen zeigen, dass sich Ethin vorallem deshalb besser zur Aufkohlung von Sackloch-bohrungen eignetals Propan, da der Diffusionswiderstand des bei der Aufkohlungs­reaktion entstehenden Zerfallsproduktes Wasserstoff sehr klein ist.Da die Verwendung von Ethin als Aufkohlungsgas aber aufw{\"a}ndigerund teurer ist als die von Propan, sollte Ethin nur eingesetzt werden,wenn dies unbedingt erforderlich ist. Das vorgestellte Modell kannhelfen, bereits vor den ersten Versuchen die maximale Bohrungs­tiefe bzw. den minimalen Bohrungsdurchmesser abzusch{\"a}tzen, dermit Propan bzw. Ethin noch aufgekohlt werden kann.}, language = {de} } @incollection{LemoueddaBreuerFranz2009, author = {Lemouedda, A. and Breuer, Michael and Franz, E.}, title = {Pareto optimization of heat transfer enhancement of finned-tube heat exchangers with delta-winglet vor-tex generators}, series = {Turbulence, heat and mass transfer 6 : proceedings of the Sixth International Symposium on Turbulence, Heat and Mass Transfer Rome, Italy, 14 - 18 September, 2009}, booktitle = {Turbulence, heat and mass transfer 6 : proceedings of the Sixth International Symposium on Turbulence, Heat and Mass Transfer Rome, Italy, 14 - 18 September, 2009}, isbn = {978-1-56700-262-1}, issn = {2377-2816}, doi = {10.1615/ICHMT.2009.TurbulHeatMassTransf.1860}, pages = {1015 -- 1018}, year = {2009}, abstract = {For circular finned tubes often used in heat exchangers, the wake regions behind the tubes are regions with low heat transfer coefficient. Delta-winglet vortex generators on the fin surfaces reduce the width of the wake regions and improve the overall heat transfer rate. The present work studies numerically the effect of enhancing the performance of the finned-tubes using delta-winglets. Simulations were carried out on a model of three circular tube rows with circular fins for Reynolds numbers of 500, 700, and 900 (based on the inlet velocity and the hydraulic diameter of unit cell). Eighteen basic configurations with different number and positions of delta-winglets were investigated. The flow and heat transfer behaviors are analyzed for certain configurations. Finally, the optimal configurations are presented based on the Pareto optimality strategy.}, language = {en} } @inproceedings{KrippnerFlade2021, author = {Krippner, Roland and Flade, Fabian}, title = {Building Integrated Solar Technology}, publisher = {International Solar Energy Society}, address = {Freiburg, Germany}, doi = {10.18086/swc.2021.09.01}, year = {2021}, language = {en} } @article{MoeldnerHentschelCarstensen2024, author = {M{\"o}ldner, Fabian and Hentschel, Bernd and Carstensen, Dirk}, title = {Ice-Jam Investigations along the Oder River Based on Satellite and UAV Data}, series = {Water}, volume = {16}, journal = {Water}, number = {10}, publisher = {MDPI AG}, issn = {2073-4441}, doi = {10.3390/w16101323}, year = {2024}, abstract = {The Oder River, situated along the border between Poland and Germany, is regularly affected by ice-jam events and their associated hazards, such as a sudden rise in water level and the endangerment to flood-protection infrastructure. The existing databases on past ice-jam events lack substantial information considering ice formation, blockage origins or the spatiotemporal evolution of the ice cover needed for a comprehensive understanding of relevant ice processes. Within this study, the evaluation of satellite and Uncrewed Aerial Vehicle (UAV) data was carried out in order to analyze the capabilities of enhancing river ice information in the study area. Satellite imagery was proven to be a valuable source of investigating ice-jam phenomena on all scales, leading to the identification of initial ice-jam locations, surveying spatiotemporal ice cover evolution or monitoring the maximum ice-cover extent. A simplified approach for river ice classification of satellite radar data using the K-Means Cluster Analysis is introduced, enabling the differentiation between river ice formations. Based on UAV data taken in this study, workflows were presented, allowing for measurements of ice floe velocities and the localization of flooded and ice-covered flow control structures.}, language = {en} } @article{BirknerForetaRinaldietal.2024, author = {Birkner, Lena and Foreta, Michael and Rinaldi, Ali and Orekhov, Anton and Willinger, Marc-Georg and Eichelbaum, Maik}, title = {Dynamic accelerated stress test and coupled on-line analysis program to elucidate aging processes in proton exchange membrane fuel cells}, series = {Scientific Reports}, volume = {14}, journal = {Scientific Reports}, number = {1}, publisher = {Springer Science and Business Media LLC}, issn = {2045-2322}, doi = {10.1038/s41598-024-54258-8}, year = {2024}, abstract = {AbstractThe application of hydrogen proton exchange membrane fuel cells (PEMFC) in greenhouse gas emission free heavy-duty vehicles requires extremely durable PEMFC components with service lives in the range of 30,000 h. Hence suitable test and analysis methods are required that reflect realistic operation scenarios, but significantly accelerate aging. For this purpose, a dynamic accelerated stress test was developed, which is coupled with a comprehensive in-depth in-situ and ex-situ analysis program to determine the aging processes of a PEMFC membrane electrode assembly (MEA). The test comprehends dynamic cycling between low, moderate and high load, different temperature and humidity conditions as well as recovery sequences to distinguish between reversible and irreversible failure modes. All phases of the PEMFC system (i.e. solid, liquid and gaseous) are monitored on-line during aging by sophisticated electrochemical, mass spectrometric and ion chromatographic analytical methods. The structural and elemental composition of the MEA before and after the aging program (post-mortem) are investigated by X-ray fluorescence, scanning and transmission electron microscopy. This program was able to age a commercial PEMFC to end-of-life in 1000 h, while providing an accurate picture of the aging processes involved.}, language = {en} } @article{FeixFadhilTroegel2024, author = {Feix, Tobias and Fadhil, Aseel Ali and Troegel, Dennis}, title = {Leaching of catalyst platinum from cured silicone elastomers: A preliminary study for comparing reagents}, series = {Hydrometallurgy}, volume = {225}, journal = {Hydrometallurgy}, publisher = {Elsevier BV}, issn = {0304-386X}, doi = {10.1016/j.hydromet.2024.106283}, pages = {1 -- 9}, year = {2024}, abstract = {Addition curing systems involve two-part silicones which require the mixture of a silicone polymer with a catalyst to initiate the cure. Platinum is the most commonly used metal catalyst for addition curing of silicones by hydrosilylation which involves the crosslinking by the addition reaction of silicon hydride species to unsaturated bonds, mainly C=C, but also C=O or C=N double bonds. After crosslinking of the polymers, the platinum catalyst cannot be recovered but remains in the silicone materials throughout the entire product life. In the end, platinum is disposed of together with the silicones and is thus lost to the value chain. The overall objective of this work was to develop a recycling process for the recovery of platinum from addition-cured silicone elastomers. In the first step, this was achieved by efficient digestion methods and by optimizing the leaching processes for exemplary commercial silicone elastomer products. Two different silicone materials were investigated, both of which were crosslinked with a platinum catalyst. The initial Pt content in the tested samples was 12.6 ± 0.2 mg/kg for a commercial silicone impression material and 6.3 ± 0.5 mg/kg for a silicone baking mold, measured by graphite furnace atomic absorption spectrometry (GF-AAS). Samples were first frozen with liquid nitrogen to improve brittleness and then crushed with a simple food processor to obtain a silicone granule. Various acid mixtures, mainly based on sulfuric acid, were investigated as digestion methods in order to extract platinum from the silicone network. These had different effects on the dissolution behavior of silicone samples and the amount of platinum extracted in each case. The amount of platinum leached from the filtrate of the digested samples in each case was measured by ICP-OES to evaluate the efficiency of different leaching mixtures. In addition, the dissolved platinum species present in the solutions was identified by UV/VIS as tetrachloridoplatinate(II) complex. The best platinum leaching results so far were obtained with two methods, both of which used a leaching mixture based on sulfuric acid and hexamethyldisiloxane (M2). In the presence of hydrochloric acid, 9.6 ± 1.6 mg platinum/kg was leached from the silicone impression material and 4.2 ± 0.8 mg platinum/kg from the silicone baking mold. With the additional use of aqua regia instead of hydrochloric acid, 10.4 ± 2.8 mg platinum/kg was extracted from the silicone impression material and 4.8 ± 1.0 mg platinum/kg was extracted from the silicone baking mold. These methods were replicated with n = 3. Using statistical evaluation methods (F-test, t-test, and confidence interval), no significant difference was found between these two best methods. Recovery of platinum(0) from leach mixtures has not yet been achieved due to high dilution and very low platinum concentration in samples and will be part of another study.}, language = {en} } @inproceedings{ThielSeisEichelbaum2022, author = {Thiel, Susanne and Seis, Volker and Eichelbaum, Maik}, title = {Scanning electrochemical microscopy for the characterization of fuel cell components}, series = {2022 International Workshop on Impedance Spectroscopy (IWIS)}, booktitle = {2022 International Workshop on Impedance Spectroscopy (IWIS)}, publisher = {IEEE}, doi = {10.1109/IWIS57888.2022.9975128}, pages = {14 -- 19}, year = {2022}, abstract = {The limited lifetime and severe degradation after long-term usage of polymer electrolyte membrane fuel cells (PEMFCs) are challenges that have to be overcome, if PEMFCs are to play the anticipated major role in a sustainable energy and transportation system based on green hydrogen. Therefore, analytical scanning methods to precisely characterize and understand the degradation and ageing mechanisms with high spatial resolution are essential. We are using and validating scanning electrochemical microscopy (SECM) as tool for detecting descriptors of the electrochemical performance of PEMFCs treated under different activation and ageing protocols. For this purpose, a pristine Nafion™ membrane, which is typically used as proton exchange membrane (PEM) in low temperature fuel cells, was activated and deactivated after well-defined protocols to demonstrate the fundamental suitability of SECM for investigating PEMFC components. Our results indicate that the impedance associated with the proton conductivity of the Nafion™ membrane as measured by SECM was dependent on the pretreatment of the membrane and increased in the following order: hot water < hydrochloric acid < sulfuric acid. The partial and complete deactivation of the membrane using Fenton's reagent and barium hydroxide, respectively, could be spatially visualized with SECM as well. In addition, we investigated a PEM as part of a complete membrane electrode assembly in a fully functional PEMFC after accelerated ageing tests and could identify an increased local PEM impedance by SECM. All trends could be confirmed by electrochemical impedance spectroscopy (EIS). Moreover, we investigated a typical gas diffusion layer (GDL) of a PEMFC with SECM. As a result, the microporous side of the GDL showed a much lower impedance than its macroporous side, which is comprehensible since it agrees with the additional carbon black coating on the former side.}, language = {en} } @article{ThielEichelbaum2024, author = {Thiel, Susanne and Eichelbaum, Maik}, title = {Scanning electrochemical microscopy for the differentiation of radical-induced degradation mechanisms in polymer electrolyte membranes}, series = {RSC Advances}, volume = {14}, journal = {RSC Advances}, number = {20}, publisher = {Royal Society of Chemistry (RSC)}, issn = {2046-2069}, doi = {10.1039/d4ra02203c}, pages = {13748 -- 13757}, year = {2024}, abstract = {In this work, a spatially resolved analytical method based on scanning electrochemical microscopy (SECM) to distinguish different degradation phenomena in polymer electrolyte membranes was developed. SECM was combined with a Franz diffusion cell to distinguish between radical-induced aging of a sulfonated tetrafluoroethylene based fluoropolymer-copolymer due to deactivation of the sulfonic acid groups followed by a decreased proton conductivity, and the radical-induced formation of cracks and holes in the polymer. The experiments were performed with ferrocyanide as redox mediator to detect holes and cracks, and protons (sulfuric acid) to determine the through-plane proton conductivity, respectively. A pristine Nafion™ membrane, a pristine Nafion™ membrane with an artificial pinhole and a Nafion™ membrane aged with Fenton's reagent were investigated to prove the measurement principle. It could be shown that holes and cracks can be reliably detected with this approach and discriminated from a change in proton conductivity. The presence of holes in the investigated aged membranes was confirmed by scanning electron microscopy, whereas the loss of sulfonate groups could be supported by infrared spectroscopy measurements.}, language = {en} } @incollection{RaufeisenBreuerBotschetal.2007, author = {Raufeisen, A. and Breuer, Michael and Botsch, T. and Delgado, A.}, title = {Analysis of Turbulent Structures in a Czochralski System Using DNS and LES Predictions}, series = {High Performance Computing in Science and Engineering `07}, booktitle = {High Performance Computing in Science and Engineering `07}, publisher = {Springer}, address = {Berlin, Heidelberg}, isbn = {9783540747383}, doi = {10.1007/978-3-540-74739-0_25}, pages = {371 -- 386}, year = {2007}, abstract = {A DNS of the turbulent flow and heat transfer in an idealized Czochralski configuration was conducted using a very fine grid. The results show the irregular forming of buoyant thermal plumes as well as the occurrence of a large, stable vortical structure in the bulk of the melt. In the averaged flow field a B´enard-cell-like pattern can be recognized. The DNS data served also as a reference for the validation of the LES method. The LES computations were conducted using different grid sizes, SGS models, and discretization methods. For relatively fine grids and central differences, the results agree very well with the DNS. Using an upwind discretization introduces numerical errors. In combination with coarser grids, this leads to large deviations and even qualitative differences. However, overall the computational effort could be reduced significantly by LES. Thus a compromise between accuracy achieved and effort required has to be found.}, language = {en} } @incollection{RaufeisenBreuerBotschetal.2011, author = {Raufeisen, A. and Breuer, Michael and Botsch, T. and Delgado, A.}, title = {Time-Dependent Three-Dimensional Simulation of the Turbulent Flow and Heat Transfer in Czochralski Crystal Growth Including the Three-Phase Boundary Movement}, series = {High Performance Computing in Science and Engineering 2010 - Transactions of the High Performance Computing Center, Stuttgart, HLRS 2010}, booktitle = {High Performance Computing in Science and Engineering 2010 - Transactions of the High Performance Computing Center, Stuttgart, HLRS 2010}, publisher = {Springer}, address = {Berlin, Heidelberg}, isbn = {9783642157479}, doi = {10.1007/978-3-642-15748-6_27}, pages = {353 -- 367}, year = {2011}, abstract = {In the literature, numerical computations of the Czochralski process for crystal growth are conducted using a quasi-steady state assumption for the crystallization neglecting time-dependent effects. In the present work, an algorithm is developed, which allows to calculate the transient behavior of the crystallization interface including the movement of the three-phase boundary and the free surface of the melt. Thus, in conjunction with the computation of the turbulent melt flow and heat transfer, more realistic predictions of the crystal growth can be achieved. Test cases show that with the algorithm, realistic phenomena like crystal diameter increase and decrease during the growth process could be reproduced.}, language = {en} } @incollection{RaufeisenBreuerBotschetal.2011, author = {Raufeisen, A. and Breuer, Michael and Botsch, T. and Delgado, A.}, title = {Time-Dependent Three-Dimensional Simulation of the Turbulent Flow and Heat Transfer in Czochralski Crystal Growth Including the Three-Phase Boundary Movement}, series = {High Performance Computing in Science and Engineering '10}, booktitle = {High Performance Computing in Science and Engineering '10}, publisher = {Springer}, address = {Berlin, Heidelberg}, isbn = {9783642157479}, doi = {10.1007/978-3-642-15748-6_27}, pages = {353 -- 367}, year = {2011}, abstract = {In the literature, numerical computations of the Czochralski process for crystal growth are conducted using a quasi-steady state assumption for the crystallization neglecting time-dependent effects. In the present work, an algorithm is developed, which allows to calculate the transient behavior of the crystallization interface including the movement of the three-phase boundary and the free surface of the melt. Thus, in conjunction with the computation of the turbulent melt flow and heat transfer, more realistic predictions of the crystal growth can be achieved. Test cases show that with the algorithm, realistic phenomena like crystal diameter increase and decrease during the growth process could be reproduced.}, language = {en} } @article{OebelMichalkeStollKleemannetal.2024, author = {Oebel, Benjamin and Michalke, Amelie and Stoll-Kleemann, Susanne and Gaugler, Tobias and Stein, Lennart}, title = {Towards true prices in food retailing}, series = {Sustainability Science}, volume = {11}, journal = {Sustainability Science}, number = {3}, publisher = {Springer}, doi = {10.1007/s11625-024-01477-7}, pages = {18}, year = {2024}, abstract = {Current crises (i.e., climate crisis, COVID-19 pandemic, Russian invasion of Ukraine, and the resulting energy and food shortages) indicate the need for robust, and sustainable supply chains with regional food production and farmland to secure food supply in the European Union (EU). Recent research shows that organic food is more resilient to supply chain disruptions and price fluctuations. In this context, we examine an approach for the sustainable and resilient transformation of agri-food networks: can an adaptation of value added tax (VAT) levels work as a financial incentive to amplify resilient agricultural practices and sustainable dietary patterns? Within the setting of the amendment of the European framework directive on the use of VAT in 2022, we model the effects of adapting the current German VAT system by (1) reducing VAT on organic vegetarian food to 0\% and (2) raising VAT on conventional meat and fish to 19\%. Based on historical data on organic sales shares and price elasticities, we project sales shares differentiated by product group for each scenario. Then, we calculate expected tax revenues, changes in consumption patterns, and arising total external climate costs in Germany for both scenarios. Our results show that the overall consumption share of organic food would increase by 21.83\% due to the modeled VAT reform compared to the status quo. Despite the VAT reduction to 0\% on organic vegetarian products, the measure would yield €2.04 billion in extra tax revenues in Germany per year due to the increased taxation on conventional meat products. We find that annual environmental costs of €5.31 billion can be avoided as a result of lower external climate costs of organic and vegetarian food. Therefore, adjusting VAT rates in the food market can be a political instrument to drive organic food consumption and reduce animal livestock. This supports re-territorialization of agriculture and a more sustainable and resilient European food supply.}, language = {en} } @article{LemoueddaBreuerFranzetal.2010, author = {Lemouedda, A. and Breuer, Michael and Franz, E. and Botsch, T. and Delgado, A.}, title = {Optimization of the angle of attack of delta-winglet vortex generators in a plate-fin-and-tube heat exchanger}, series = {International Journal of Heat and Mass Transfer}, volume = {53}, journal = {International Journal of Heat and Mass Transfer}, number = {23/24}, publisher = {Elsevier BV}, issn = {0017-9310}, doi = {10.1016/j.ijheatmasstransfer.2010.07.017}, pages = {5386 -- 5399}, year = {2010}, abstract = {Delta-winglet vortex generators (VGs) are known to enhance the heat transfer between the energy-carrying fluid and the heat transfer surfaces in plate-fin-and-tube banks. In this study optimal angles of attack of the delta-winglets are investigated based on the Pareto optimal strategy. The optimization process combines a CFD analysis, genetic algorithms and the response surface methodology. The angle of attack of a pair a delta-winglet-type VGs mounted behind each tube is varied between β = -90° and +90°. Three circular tube rows with inline and staggered tube arrangements are investigated for Reynolds numbers from 200 to 1200 (based on the inlet height and inlet velocity). The flow structure and heat transfer behavior is analyzed in detail for certain cases and the staggered and the inline tube arrangements are compared. Finally, for each of these arrangements the optimal sets of angles of attack for different Reynolds numbers are presented.}, language = {en} } @article{SchlipfStrieglGaugler2024, author = {Schlipf, Matthias and Striegl, Bastian and Gaugler, Tobias}, title = {Climate true-cost analysis of industrial goods and its regulatory implications on value chains and global competition}, series = {Journal of Industrial Ecology}, volume = {28}, journal = {Journal of Industrial Ecology}, number = {3}, editor = {Schlipf, Matthias}, doi = {10.1111/jiec.13469}, pages = {589-602}, year = {2024}, abstract = {Climate change and its damaging consequences for ecology and humanity is advancing. Industry and its metals sector are responsible for most greenhouse gas emissions. Current costs of industrial goods do not reflect the true costs caused by the externalized climate damages of its production and thus offer no competitive incentive to decarbonize. Additionally, regional climate regulation can lead to competitive distortion. We therefore aim to investigate the impact of climate cost internalization on the metals industry. Using true-cost analysis for an exemplary and widely used metal product, the effects of climate true costs depending on production region, technology, and energy mix, CO2e taxation and value chain are examined. Based hereon, the impact of internalizing climate true costs together with the introduction of a carbon-border tax on the carbon leakage problem, climate protection, and the cost situation for companies in global competition are investigated. The results of the study show that steel and wire production is responsible for most CO2e emissions showing significant decarbonization effects by steel recycling whereas production location and logistics play a minor role. On a competitive level, cost internalization has hardly any effect on the product costs because of the currently low CO2e-taxation rates. Thus, almost no incentive to produce or consume in a climate-protective way is generated, incentivizing production in pollution havens versus highly climate regulated regions. Instead, to realize emission efficiency gains and innovations leading to a competitive advantage of decarbonized products and value chains, a significant increase of CO2e-taxation rates together with a carbon-border tax is necessary.}, language = {en} } @article{BotschStumpmeierGanser2010, author = {Botsch, T. W. and Stumpmeier, S. and Ganser, J.}, title = {Simulation of the transient condensation process in steam pipes during start up of a steam power plant}, series = {Heat and Mass Transfer}, volume = {46}, journal = {Heat and Mass Transfer}, number = {10}, publisher = {Springer Science and Business Media LLC}, issn = {0947-7411}, doi = {10.1007/s00231-010-0714-3}, pages = {1187 -- 1197}, year = {2010}, abstract = {This paper introduces a model predicting the unsteady conditions in vertical pipes of a steam power station during start up of the plant. Knowing the time depending variation in the rate of condensation in the pipe is helpful for optimizing the design of the drainage system, which removes the condensate collected from the pipes. At present this system is designed on the basis of the total amount of condensate produced in a particular pipe during start up of the power plant. The model presented will provide a design based on the true maximum flow rate during said period. The paper describes the mass and energy balances for the gas and the condensate as well as the energy balance for the wall. All equations are transformed into a set of differential and algebraic equations and solved at once. The model was subsequently applied on genuine industrial scenarios. The results obtained from the model are discussed in detail and compared with experimental data. In all situations considered, the maximum condensate flow rate calculated was less than 50\% of the estimated value using standard design methods.}, language = {en} } @article{SteinMichalkeGaugleretal.2024, author = {Stein, Lennart and Michalke, Amelie and Gaugler, Tobias and Stoll-Kleemann, Susanne}, title = {Sustainability Science Communication}, series = {Sustainability}, volume = {16}, journal = {Sustainability}, number = {9}, editor = {Stein, Lennart}, doi = {10.3390/su16093842}, pages = {20}, year = {2024}, abstract = {The Anthropocene, marked by human-induced climate change, necessitates urgent action to address climate goals and respect planetary boundaries. While sustainability research provides knowledge, the first challenge lies in communicating the findings in an adequate manner to the public and several stakeholders, such as economic and political actors. Therefore, this study explores the significance of science communication in sustainability science, focusing on a case study—the True Cost Accounting (TCA) campaign by the University of Greifswald, Technical Institute of Nuremberg, and German retailer PENNY. TCA herein serves as a transparency tool, economic incentive, and discussion basis for sustainable consumption. This study investigates consumer perceptions of ecological prices of foods through a face-to-face survey during the 2023 PENNY campaign, comparing results to an informational campaign carried out in 2021. Findings indicate a high awareness of the true cost campaign in 2023, with 50.8\% of participants hearing about it. Consumers' willingness to pay true costs and potential behavior changes were explored. In comparison to results from the informational campaign of 2021, customers showed a decrease in this WTP when the true prices would actually impact their spending, indicating an attitude-behavior gap. In addition, a willingness to reduce the consumption of animal foods—if TCA was implemented—of 60.5\% was determined, suggests that TCA has the potential for sustainable behavior change. This study highlights factors that influence consumer attitudes and preferences regarding the inclusion of TCAs, such as environmental, social, and animal welfare costs. Customers' understanding of increased prices like, in this case, the compensation for environmental and social costs—is an argument in favor of true prices. The results emphasize the need for differentiated scientific communication strategies to bridge knowledge and action gaps in sustainability science.}, language = {en} } @article{RaufeisenBreuerBotschetal.2010, author = {Raufeisen, A. and Breuer, Michael and Botsch, T. and Delgado, A.}, title = {Prediction of the three-phase boundary movement in Czochralski crystal growth}, series = {Journal of Crystal Growth}, volume = {312}, journal = {Journal of Crystal Growth}, number = {16/17}, publisher = {Elsevier BV}, issn = {0022-0248}, doi = {10.1016/j.jcrysgro.2010.05.009}, pages = {2297 -- 2299}, year = {2010}, abstract = {A numerical algorithm is presented which allows three-dimensional time-dependent simulations of Czochralski and other crystal growth processes. Besides the computation of turbulent flow and heat transfer in the melt, it includes the movement of the crystallization interface between melt and crystal, the dynamics of the melt free surface with the meniscus and the variation of the three-phase boundary. Thus, there is the potential that crystal diameter variations, which occur during growth of the start and the end cone can be predicted. This is illustrated by results of sample computations.}, language = {en} } @inproceedings{SeidelOebelSteinetal.2023, author = {Seidel, Felix and Oebel, Benjamin and Stein, Lennart and Michalke, Amelie and Gaugler, Tobias}, title = {Entwicklung eines Frameworks zur Monetarisierung externer Gesundheitskosten von Lebensmitteln}, editor = {Seidel, Felix}, publisher = {Dr. K{\"o}ster}, address = {Berlin}, isbn = {978-3-96831-055-265}, year = {2023}, abstract = {Quantification and subsequent monetization of dietary externalities is essential to incentivise healthier and more sustainable diets. In this way, positive monetary incentives can be set for under-consumed foods such as fruits or whole grain products and negative monetary incentives for overconsumed foods such as red or processed meat. This not only promotes a shift to healthier diets, but also motivates a move towards a more ecological agricultural economy.}, language = {de} } @article{RaufeisenJanaBreueretal.2007, author = {Raufeisen, A. and Jana, S. and Breuer, Michael and Botsch, T. and Durst, F.}, title = {3D computation of oxygen transport in Czochralski crystal growth of silicon considering evaporation}, series = {Journal of Crystal Growth}, volume = {303}, journal = {Journal of Crystal Growth}, number = {1}, publisher = {Elsevier BV}, issn = {0022-0248}, doi = {10.1016/j.jcrysgro.2006.11.349}, pages = {146 -- 149}, year = {2007}, abstract = {For Czochralski (Cz) growth of silicon single crystals, 3D unsteady simulations of the oxygen transport in the turbulent melt flow were conducted using a new formulation for the evaporation at the free surface found by Sakai et al. [Electrochem. Solid-State Lett. 5 (8) (2002) G72]. Compared with 2D results from literature, the computed oxygen concentration now fits the experimental data better, showing lower values in the critical region beneath the crystal than in previous simulations, which mostly arises from the more accurate prediction of the flow field. Further computations of Cz configurations show how the oxygen distribution can be influenced by rotation of the crucible and crystal.}, language = {en} } @inproceedings{SeebergerBockletRiedhammer2023, author = {Seeberger, Philipp and Bocklet, Tobias and Riedhammer, Korbinian}, title = {Information Type Classification with Contrastive Task-Specialized Sentence Encoders}, publisher = {Association for Computational Linguistics}, doi = {10.48550/arXiv.2312.11020}, pages = {180-186}, year = {2023}, abstract = {User-generated information content has become an important information source in crisis situations. However, classification models suffer from noise and event-related biases which still poses a challenging task and requires sophisticated task-adaptation. To address these challenges, we propose the use of contrastive task-specialized sentence encoders for downstream classification. We apply the task-specialization on the CrisisLex, HumAID, and TrecIS information type classification tasks and show performance gains w.r.t. F1-score. Furthermore, we analyse the cross-corpus and cross-lingual capabilities for two German event relevancy classification datasets.}, language = {en} } @inproceedings{SeebergerRiedhammer2022, author = {Seeberger, Philipp and Riedhammer, Korbinian}, title = {Enhancing Crisis-Related Tweet Classification with Entity-Masked Language Modeling and Multi-Task Learning}, publisher = {Association for Computational Linguistics}, doi = {10.48550/arXiv.2211.11468}, pages = {70 -- 78}, year = {2022}, abstract = {Social media has become an important information source for crisis management and provides quick access to ongoing developments and critical information. However, classification models suffer from event-related biases and highly imbalanced label distributions which still poses a challenging task. To address these challenges, we propose a combination of entity-masked language modeling and hierarchical multi-label classification as a multi-task learning problem. We evaluate our method on tweets from the TREC-IS dataset and show an absolute performance gain w.r.t. F1-score of up to 10\% for actionable information types. Moreover, we found that entity-masking reduces the effect of overfitting to in-domain events and enables improvements in cross-event generalization.}, language = {en} } @inproceedings{SeebergerRiedhammer2022, author = {Seeberger, Philipp and Riedhammer, Korbinian}, title = {Combining Deep Neural Reranking and Unsupervised Extraction for Multi-Query Focused Summarization}, publisher = {National Institute of Standards and Technology (NIST)}, doi = {10.48550/arXiv.2302.01148}, pages = {7}, year = {2022}, abstract = {The CrisisFACTS Track aims to tackle challenges such as multi-stream fact-finding in the domain of event tracking; participants' systems extract important facts from several disaster-related events while incorporating the temporal order. We propose a combination of retrieval, reranking, and the well-known Integer Linear Programming (ILP) and Maximal Marginal Relevance (MMR) frameworks. In the former two modules, we explore various methods including an entity-based baseline, pre-trained and fine-tuned Question Answering systems, and ColBERT. We then use the latter module as an extractive summarization component by taking diversity and novelty criteria into account. The automatic scoring runs show strong results across the evaluation setups but also reveal shortcomings and challenges.}, language = {en} } @inproceedings{SchullerBatlinerAmiriparianetal.2022, author = {Schuller, Bj{\"o}rn and Batliner, Anton and Amiriparian, Shahin and Bergler, Christian and Gerczuk, Maurice and Holz, Natalie and Larrouy-Maestri, Pauline and Bayerl, Sebastian P. and Riedhammer, Korbinian and Mallol-Ragolta, Adria and Pateraki, Maria and Coppock, Harry and Kiskin, Ivan and Sinka, Marianne and Roberts, Stephen}, title = {The ACM Multimedia 2022 Computational Paralinguistics Challenge}, doi = {10.1145/3503161.3551591}, pages = {7120-7124}, year = {2022}, abstract = {The ACM Multimedia 2022 Computational Paralinguistics Challenge addresses four different problems for the first time in a research competition under well-defined conditions: In the Vocalisations and Stuttering Sub-Challenges, a classification on human non-verbal vocalisations and speech has to be made; the Activity Sub-Challenge aims at beyond-audio human activity recognition from smartwatch sensor data; and in the Mosquitoes Sub-Challenge, mosquitoes need to be detected. We describe the Sub-Challenges, baseline feature extraction, and classifiers based on the 'usual' ComParE and BoAW features, the auDeep toolkit, and deep feature extraction from pre-trained CNNs using the DeepSpectrum toolkit; in addition, we add end-to-end sequential modelling, and a log-mel-128-BNN.}, language = {en} } @inproceedings{HintzBayerlSinhaetal.2023, author = {Hintz, Jan and Bayerl, Sebastian P. and Sinha, Yamini and Riedhammer, Korbinian and Siegert, Ingo}, title = {Impact of pathological speech on speaker anonymization}, pages = {4}, year = {2023}, abstract = {With the ever-increasing usage of voice assistants, concerns for privacy and data security arise. Speech contains highly personal data that can be exploited for user profiling or identification [1]. On-device speech anonymization can serve as a measure to counteract this [2]. While these anonymization systems are being tested and evaluated through challenges and benchmarks [3], the commonly used datasets include no or only a few individuals with speech impairments, leading to low inclusivity, possible data bias, and privacy concerns for these groups [5]. For anonymization to work, it is crucial to evaluate and counteract bias if needed. Stuttering is a speech disorder with diverse characteristics. The well-known, defining symptoms are blocks, repetition and prolongation of sounds, syllables, and words while speaking [4]. The different primary stuttering symptoms vary strongly in their characteristics and occur over a different time context, making stuttering an ideal candidate to study the effects of pathological speech on the application of anonymization techniques. This paper analyzes the impact of stuttering on speaker anonymization, regarding the level of anonymity and utility. We present two methods to conceal speaker identity, us- ing voice conversion and re-synthesis. Firstly, Voice conversion, a process that adapts the way a source speaker speaks to a target speaker. It preserves some prosody of the source speaker, especially temporal aspects, with the goal of protecting the identity while at the same time preserving pathologic speech patterns. This could be applied in pathology-related processing, such as self-help training applications. Secondly, re-synthesis, based on an automatic speech recognition generating a transcript, which is afterward used to synthesize a new voice by a text-to-speech system. This process disentangles speaker information and text, granting a high level of anonymization. To compare these methods, we use subjective and objective measures.}, language = {en} } @inproceedings{BraunBayerlPerezToroetal.2023, author = {Braun, Franziska and Bayerl, Sebastian P. and P{\´e}rez-Toro, Paula A. and H{\"o}nig, Florian and Lehfeld, Hartmut and Hillemacher, Thomas and N{\"o}th, Elmar and Bocklet, Tobias and Riedhammer, Korbinian}, title = {Classifying Dementia in the Presence of Depression}, doi = {10.48550/arXiv.2308.08306}, pages = {5}, year = {2023}, abstract = {Automated dementia screening enables early detection and intervention, reducing costs to healthcare systems and increasing quality of life for those affected. Depression has shared symptoms with dementia, adding complexity to diagnoses. The research focus so far has been on binary classification of dementia (DEM) and healthy controls (HC) using speech from picture description tests from a single dataset. In this work, we apply established baseline systems to discriminate cognitive impairment in speech from the semantic Verbal Fluency Test and the Boston Naming Test using text, audio and emotion embeddings in a 3-class classification problem (HC vs. MCI vs. DEM). We perform cross-corpus and mixed-corpus experiments on two independently recorded German datasets to investigate generalization to larger populations and different recording conditions. In a detailed error analysis, we look at depression as a secondary diagnosis to understand what our classifiers actually learn.}, language = {en} } @article{MichalkeKoehlerMessmannetal.2023, author = {Michalke, Amelie and K{\"o}hler, Sandar and Messmann, Lukas and Thorenz, Andrea and Tuma, Axel and Gaugler, Tobias}, title = {True cost accounting of organic and conventional food production}, series = {Journal of Cleaner Production}, volume = {408}, journal = {Journal of Cleaner Production}, number = {137134}, doi = {10.1016/j.jclepro.2023.137134}, pages = {13}, year = {2023}, abstract = {Agriculture is one of the world's biggest polluters. Consumers are misled towards demand of unsustainable and inadequately priced food products by an insufficient internalization of externalities. Shifting demand towards more sustainable dietary choices can lead to a sustainable transition of agri-food networks. In this study, we evaluate environmental damage economically: we combine environmental assessment of different food products with the internalization of their monetary impacts. Life Cycle Assessments are modeled for conventional and organic foods and different production scenarios. The quantified environmental impacts are combined with True Cost Accounting to adjust food prices according to their environmental impacts. Using this framework for 22 German agricultural products, we find that on average, crop production generates externalities of about €0.79 per kg for conventional and about €0.42 for organic products. Conventional milk and eggs cause additional costs of about €1.29 per kg on average in organic systems and about €1.10 in organic ones. Conventional and organic meat generate externalities of €4.42 and €4.22 per kg, respectively, with beef generating the highest costs of all. The environmental favorability of organic products is confirmed, but the resulting organic market prices after internalization still exceed conventional prices. Externalities represent a negative impact on societal welfare, which should be addressed by policies supporting transparent pricing approaches.}, language = {en} } @inproceedings{BayerlRoccabrunaChowdhuryetal.2022, author = {Bayerl, Sebastian P. and Roccabruna, Gabriel and Chowdhury, ShammurA and Ciulli, Tommaso and Danieli, Morena and Riedhammer, Korbinian and Riccardi, Giuseppe}, title = {What can Speech and Language Tell us About the Working Alliance in Psychotherapy}, doi = {10.48550/arXiv.2206.08835}, pages = {5}, year = {2022}, abstract = {We are interested in the problem of conversational analysis and its application to the health domain. Cognitive Behavioral Therapy is a structured approach in psychotherapy, allowing the therapist to help the patient to identify and modify the malicious thoughts, behavior, or actions. This cooperative effort can be evaluated using the Working Alliance Inventory Observer-rated Shortened - a 12 items inventory covering task, goal, and relationship - which has a relevant influence on therapeutic outcomes. In this work, we investigate the relation between this alliance inventory and the spoken conversations (sessions) between the patient and the psychotherapist. We have delivered eight weeks of e-therapy, collected their audio and video call sessions, and manually transcribed them. The spoken conversations have been annotated and evaluated with WAI ratings by professional therapists. We have investigated speech and language features and their association with WAI items. The feature types include turn dynamics, lexical entrainment, and conversational descriptors extracted from the speech and language signals. Our findings provide strong evidence that a subset of these features are strong indicators of working alliance. To the best of our knowledge, this is the first and a novel study to exploit speech and language for characterising working alliance.}, language = {en} } @inproceedings{BayerlHoenigReisteretal.2020, author = {Bayerl, Sebastian P. and H{\"o}nig, Florian and Reister, Joelle and Riedhammer, Korbinian}, title = {Towards automated assessment of stuttering and stuttering therapy}, doi = {10.48550/arXiv.2006.09222}, pages = {10}, year = {2020}, abstract = {Stuttering is a complex speech disorder that can be identified by repetitions, prolongations of sounds, syllables or words and blocks while speaking. Severity assessment is usually done by a speech therapist. While attempts at automated assessment were made, it is rarely used in therapy. Common methods for the assessment of stuttering severity include percent stuttered syllables (\% SS), the average of the three longest stuttering symptoms during a speech task or the recently introduced Speech Efficiency Score (SES). This paper introduces the Speech Control Index (SCI), a new method to evaluate the severity of stuttering. Unlike SES, it can also be used to assess therapy success for fluency shaping. We evaluate both SES and SCI on a new comprehensively labeled dataset containing stuttered German speech of clients prior to, during and after undergoing stuttering therapy. Phone alignments of an automatic speech recognition system are statistically evaluated in relation to their relative position to labeled stuttering events. The results indicate that phone length distributions differ in respect to their position in and around labeled stuttering events.}, language = {en} } @inproceedings{BayerlWenningerSchmidtetal.2021, author = {Bayerl, Sebastian P. and Wenninger, Marc and Schmidt, Jochen and Wolff von Gudenberg, Alexander and Riedhammer, Korbinian}, title = {STAN: A stuttering therapy analysis helper}, doi = {10.48550/arXiv.2106.09545}, pages = {2}, year = {2021}, abstract = {Stuttering is a complex speech disorder identified by repeti-tions, prolongations of sounds, syllables or words and blockswhile speaking. Specific stuttering behaviour differs strongly,thus needing personalized therapy. Therapy sessions requirea high level of concentration by the therapist. We introduceSTAN, a system to aid speech therapists in stuttering therapysessions. Such an automated feedback system can lower thecognitive load on the therapist and thereby enable a more con-sistent therapy as well as allowing analysis of stuttering overthe span of multiple therapy sessions.}, language = {en} } @inproceedings{BayerlBrasserBuschetal.2019, author = {Bayerl, Sebastian P. and Brasser, Ferdinand and Busch, Christoph and Frassetto, Tommaso and Jauernig, Patrick and Kolberg, Jascha and Nautsch, Andreas and Riedhammer, Korbinian and Sadeghi, Ahmad-Reza and Schneider, Thomas and Stapf, Emmanuel and Treiber, Amos and Weinert, Christian}, title = {Privacy-preserving speech processing via STPC and TEEs (Poster)}, year = {2019}, language = {en} } @article{RaufeisenBreuerBotschetal.2009, author = {Raufeisen, A. and Breuer, Michael and Botsch, T. and Delgado, A.}, title = {Transient 3D simulation of Czochralski crystal growth considering diameter variations}, series = {Journal of Crystal Growth}, volume = {311}, journal = {Journal of Crystal Growth}, number = {3}, publisher = {Elsevier BV}, issn = {0022-0248}, doi = {10.1016/j.jcrysgro.2008.09.073}, pages = {695 -- 697}, year = {2009}, abstract = {For numerical simulations of the Czochralski crystal growth process, in the literature the quasi-steady state approach is used, i.e. the diameter of the crystal is kept constant. However, this leads to errors in the computation of the phase interface. In the present work, for the first time in 3D, the three-phase junction between melt, crystal and atmo-sphere is allowed to move in horizontal direction. Thus, diameter changes during the crystal growth process could be simulated accordingly. In the future, the vertical movement will be allowed as well, considering the free surface stresses. This will enable realistic predictions of the transient behavior of the crystallization front.}, language = {en} } @article{RaufeisenBreuerBotschetal.2008, author = {Raufeisen, A. and Breuer, Michael and Botsch, T. and Delgado, A.}, title = {DNS of rotating buoyancy- and surface tension-driven flow}, series = {International Journal of Heat and Mass Transfer}, volume = {51}, journal = {International Journal of Heat and Mass Transfer}, number = {25/26}, publisher = {Elsevier BV}, issn = {0017-9310}, doi = {10.1016/j.ijheatmasstransfer.2008.01.041}, pages = {6219 -- 6234}, year = {2008}, language = {en} } @article{TissotSowa2024, author = {Tissot, Anna Xymena and Sowa, Frank}, title = {(In)Visibility and the smartphone: Experiencing homelessness as dictated by urban figurations of social control}, series = {Mobile Media \& Communication : special issue}, volume = {12}, journal = {Mobile Media \& Communication : special issue}, number = {2}, issn = {2050-1587}, doi = {10.1177/20501579231214898}, pages = {293-309}, year = {2024}, abstract = {This contribution sheds light on how people experiencing homelessness in Germany make sense of an app designed with them in mind and whether using it would be of benefit to them. However, it must be acknowledged that the app has yet to be developed. "Urban figurations of social control," a term we use to refer to the social conditions of homelessness in Germany, give rise to a significant loss of trust as well as a state of vulnerability, feelings of loneliness, and limited agency for people experiencing homelessness. Drawing on a group discussion with 12 people experiencing homelessness that took place in Germany in 2019, our findings demonstrate that the respondents project particular fears and desires onto the use of the potential app. Whenever they fear surveillance and institutional control, they wish to be invisible to the app. On the other hand, their desire to access resources and information (food, places to sleep, housing) and to meet with peers in order to create meaningful social relationships requires their visibility. Thus, navigating between visibility and invisibility by way of a smartphone involves situationally and strategically constructing a safe environment for their digital participation, helping them to reduce their vulnerability and loneliness and restore their agency. Moreover, in that the app is used as a means of rendering assistance to homeless people (and highlighting the grievances associated with this) that is visible to others, the respondents challenge the current framing of homelessness. The supposed system of help is revealed to be the social problem itself.}, language = {en} } @article{RogersSrivastava2021, author = {Rogers, Helen and Srivastava, Mohit}, title = {Emerging Sustainable Supply Chain Models for 3D Food Printing}, series = {Sustainability}, volume = {13}, journal = {Sustainability}, doi = {doi.org/10.3390/su132112085}, year = {2021}, abstract = {3D printing technology is rapidly transforming supply chains across diverse manu-facturing sectors, enabling personalisation of consumer goods ranging from car parts, medical devices, toys, houses, and even clothing. Food production is also included in the breadth of applications of this expanding technology. Increasing consumer awareness about sustainability, including the problem of food waste, as well as growing interest in customised nutrition have led to the emergence of food industry research focused on aspects, such as packaging, portion size, and healthy sustainable ingredients, to satisfy consumer demands. The growing market for personalised food options in particular, requires increased flexibility and agility to tailor ingredients to an individual's specific requirements. Such specificity is not easily fulfilled using traditional mass production methods; however, the emerging technology of 3D food printing (3DFP) may be one solution. This paper evaluates the opportunities, risks, and challenges associated with 3DFP, with a focus on developing sustainable supply chains for future growth. Drawing on 12 semi-structured interviews with 3DFP industry managers and current literature in the domain, we propose three supply chain models for 3DFP services, as well as an overview of the key business drivers.}, language = {en} } @article{JimoBraziotisRogersetal.2022, author = {Jimo, Ajeseun and Braziotis, Christos and Rogers, Helen and Pawar, Kulwant}, title = {Additive manufacturing}, series = {International Journal of Production Economics}, volume = {253}, journal = {International Journal of Production Economics}, doi = {10.1016/j.ijpe.2022.108592}, pages = {14}, year = {2022}, abstract = {Using Resource Dependence Theory (RDT), this paper explores the changing state of Supply Chain (SC) complexities and dependencies resulting from Additive Manufacturing (AM) adoption, analysing implications for competitiveness. We utilised an adapted SC configuration framework to develop embedded case studies across the Aerospace, Automotive and Power Generation industries. The sample included fifteen companies deploying metal AM across three SC tiers. Using an abductive logic, our findings reveal that the complexity and dependency-reduction potential of AM depends on economic, industry, geographical, organisational and technological factors. We developed a conceptual framework for AM SC configuration and four propositions, which provide further insights into the interplay between SC complexities, dependencies and competitiveness. By utilising RDT, we contribute to the AM SC configuration literature by highlighting the mediating role that dependencies play in achieving competitiveness, as well as strategies adopted by firms to mitigate uncertainty. We also highlight the interplay between 'relationship and governance' and three other SC configuration dimensions in relation to competitiveness. Insights into the changing state of complexities and dependencies identified in this study could also support managerial decisions in AM SC design.}, language = {en} } @inproceedings{MaiWagnerStreit2020, author = {Mai, Annette and Wagner, Bernhard and Streit, Fabian}, title = {Elimination of Current Harmonics in Electrical Machines with Iterative Learning Control}, volume = {2020}, doi = {10.1109/EDPC51184.2020.9388177}, pages = {1-5}, year = {2020}, abstract = {The magnitude of current harmonics depends on the design of an electrical machine. By suppressing these harmonics noise can be reduced and efficiency improved. Iterative Learning Control (ILC) has proven effective in reducing harmonics. One of the challenges of working with ILC is operation at varying speeds. Variable speeds are particularly important for applications like automotive drives. The ILC period length changes during the learning process at varying speeds. Due to fixed sample rates, the number of values processed by the ILC varies with motor speed.This paper proposes a method to solve this problem and uses ILC at varying speeds. The ILC used to eliminate the harmonics is based on the inverse system. The usage of a two-dimensional memory array is proposed. This data structure holds rows for specific speeds between which interpolation is performed, enabling the elimination of errors which are periodically cyclic to one electrical rotation. This includes the reduction of the motor current harmonics. To verify the presented method a permanent magnet synchronous motor with distinctive 5th and 7th harmonics is used. In real-time implementations, limitations of memory and computational capacity occur.}, language = {en} } @inproceedings{WenningerBayerlSchmidtetal.2019, author = {Wenninger, Marc and Bayerl, Sebastian P. and Schmidt, Jochen and Riedhammer, Korbinian}, title = {Timage - A Robust Time Series Classification Pipeline}, doi = {10.48550/arXiv.1909.09149}, pages = {12}, year = {2019}, abstract = {Time series are series of values ordered by time. This kind of data can be found in many real world settings. Classifying time series is a difficult task and an active area of research. This paper investigates the use of transfer learning in Deep Neural Networks and a 2D representation of time series known as Recurrence Plots. In order to utilize the research done in the area of image classification, where Deep Neural Networks have achieved very good results, we use a Residual Neural Networks architecture known as ResNet. As preprocessing of time series is a major part of every time series classification pipeline, the method proposed simplifies this step and requires only few parameters. For the first time we propose a method for multi time series classification: Training a single network to classify all datasets in the archive with one network. We are among the first to evaluate the method on the latest 2018 release of the UCR archive, a well established time series classification benchmarking dataset.}, language = {en} } @inproceedings{WagnerBaumannBayerletal.2023, author = {Wagner, Dominik and Baumann, Ilja and Bayerl, Sebastian P. and Riedhammer, Korbinian and Bocklet, Tobias}, title = {Speaker Adaptation for End-To-End Speech Recognition Systems in Noisy Environments}, doi = {10.48550/arXiv.2211.08774}, pages = {6}, year = {2023}, abstract = {We analyze the impact of speaker adaptation in end-to-end automatic speech recognition models based on transformers and wav2vec 2.0 under different noise conditions. By including speaker embeddings obtained from x-vector and ECAPA-TDNN systems, as well as i-vectors, we achieve relative word error rate improvements of up to 16.3\% on LibriSpeech and up to 14.5\% on Switchboard. We show that the proven method of concatenating speaker vectors to the acoustic features and supplying them as auxiliary model inputs remains a viable option to increase the robustness of end-to-end architectures. The effect on transformer models is stronger, when more noise is added to the input speech. The most substantial benefits for systems based on wav2vec 2.0 are achieved under moderate or no noise conditions. Both x-vectors and ECAPA-TDNN embeddings outperform i-vectors as speaker representations. The optimal embedding size depends on the dataset and also varies with the noise condition.}, language = {en} } @article{RogersDoraTsolakisetal.2024, author = {Rogers, Helen and Dora, Manoj and Tsolakis, Naoum and Kumar, Mukesh}, title = {Plant-based Food Supply Chains}, series = {Applied Food Research}, volume = {4}, journal = {Applied Food Research}, number = {2}, doi = {10.1016/j.afres.2024.100440}, year = {2024}, abstract = {Plant-based protein food products are considered healthier, more nutritious, and substantially 'greener' than meat-based dietary offerings. For reasons such as these plant protein sources including peas/legumes, soy and algae are experiencing unpre-cedented market popularity. Amidst the multitude of alternative protein-based foods on offer, peas are the most promising plant-protein source as they contain all the essential amino acids and have a well-balanced nutritional profile in terms of fat and fibre. However, understanding the extent of the market feasibility of the respective pea protein supply chains (SCs), based on practical expertise, is of utmost importance for policymakers and industrialists alike to evaluate the growth potential of peas as a protein source. To this end, a survey was conducted among pea SC stakeholders to create an understanding of the level of market feasibility of pea protein-based products. A SWOT analysis consolidated the different views and resulted in the identification of specific strengths, weaknesses, opportunities, and threats within the industry. By focusing on understanding the challenges and prospects within peaprotein product SCs, this research provides a springboard for further research investigations into related plant protein-based products. The resulting blueprint of recommended initiatives can help inform the further development of pea protein SCs.}, language = {en} } @article{StielerLipotLehmann2022, author = {Stieler, Mara and Lipot, Sarah and Lehmann, Robert}, title = {Zum Stand der Onlineberatung in Zeiten der Corona-Krise. Entwicklungs- und Ver{\"a}nderungsprozesse der Onlineberatungslandschaft}, series = {e-beratungsjournal.net}, volume = {18}, journal = {e-beratungsjournal.net}, number = {1}, issn = {1816 - 7632}, doi = {10.48341/262p-7t64}, pages = {16}, year = {2022}, abstract = {Der folgende Artikel bietet einen praxisnahen {\"U}berblick zu Ver{\"a}nderungs- und Umstrukturierungsprozessen der Onlineberatungslandschaft, bedingt durch die Corona-Krise (Covid-19). Neben einer gestiegenen Nachfrage kam es bei einigen Tr{\"a}gern zu einer Erweiterung des bisherigen digitalen Beratungsangebotes. So wurden beispielsweise Angebote f{\"u}r neue Zielgruppen geschaffen oder bestehende Tools der Plattformen erweitert. Besonders (quasi)-synchrone Angebote wie die Chatberatung weisen eine gestiegene Nachfrage auf.}, language = {de} } @article{SrivastavaRogers2021, author = {Srivastava, Mohit and Rogers, Helen}, title = {Managing Global Supply Chain Risks: Effects of the Industry Sector}, series = {International Journal of Logistics Research and Applications}, volume = {25}, journal = {International Journal of Logistics Research and Applications}, number = {7}, doi = {10.1080/13675567.2021.1873925}, pages = {1091-1114}, year = {2021}, abstract = {Despite the abundance of articles addressing global supply chain risks and their mitigation strategies, there are surprisingly few insights into how different industries manage global supply chain risks while internationalising abroad. There are conflicting results from previous researches that specific global supply chain risk management practices work in one industry but not in others. We believe that in each industry sector, the global supply chain risks and their mitigation strategies differ. We used profile deviation and ideal profile methodology to identify top performers in three industry sectors (Audit, Finance and Consulting, Automotive, and IT and Software) and evaluated their best practices towards managing global supply chain risks. This study used an online survey to gather information on how Indian executives across these industries manage global supply chain risks during their internationalisation process and found the 'ideal' risk mitigation profiles for all three industries. These findings provide new insights to practitioners as they will serve as a useful reference tool for Indian executives planning to internationalise.}, language = {en} } @article{RogersDora2024, author = {Rogers, Helen and Dora, Manoj}, title = {Guest editorial: The interplay between new innovations, sustainability and food supply chains}, series = {Supply Chain Management}, volume = {29}, journal = {Supply Chain Management}, number = {3}, issn = {1359-8546}, doi = {10.1108/SCM-05-2024-644}, pages = {409-413}, year = {2024}, language = {en} } @techreport{TrumpAgcharBaumannetal.2021, author = {Trump, Sebastian and Agchar, Ismael and Baumann, Ilja and Braun, Franziska and Riedhammer, Korbinian and Siemandel, Lea and Ullrich, Martin}, title = {Spirio Sessions}, pages = {7}, year = {2021}, abstract = {This paper presents an ongoing interdisciplinary research project that deals with free improvisation and human-machine interaction, involving a digital player piano and other musical instruments. Various technical concepts are developed by student participants in the project and continuously evaluated in artistic performances. Our goal is to explore methods for co-creative collaborations with artificial intelligences embodied in the player piano, enabling it to act as an equal improvisation partner for human musicians.}, language = {en} } @inproceedings{AuerRogers2022, author = {Auer, Kathrin and Rogers, Helen}, title = {A research agenda for circular food waste management in Bavaria}, series = {Transportation Research Procedia}, volume = {67}, booktitle = {Transportation Research Procedia}, doi = {10.1016/j.trpro.2022.12.043}, pages = {131 -- 136}, year = {2022}, abstract = {It is no exaggeration to say that food waste along the supply chain is becoming a significant problem for humanity. Food waste is expensive and damaging to the en-vironment and climate e.g. Accorsi and Manzini (2019), Dani (2019), Dora et al. (2020). In Germany alone, food waste generates about 4 percent of the country's total annual greenhouse gas emissions (BMEL, 2022). Entrepreneurs are often perceived as the world's problem solvers. By offering innovative new products and services they are providing pathways to overcome some of the pressing global issues, including climate change. And more specifically innovative entrepreneurs, startups as well as established companies are actively seeking to tackle the problem of food waste using innovative business models and linking agile supply chains and production systems to these busi-ness models (Dora et al., 2020, Rogers and Srivastava, 2021). In Germany, for example, companies such as "Rettergut", Kn{\"o}delkult", "Etepete" or "TooGoodToGo", approach the problem of food waste with completely different business models. This ranges from saving "ugly" fruit and vegetables, to redistributing production surplus, as well as up-cycling food and creating (digital) platforms, to ensure surplus meets demand (Deutsche Umwelthilfe, 2021, Janssen, 2018). Other innovative business models (Baierl and Behrens, 2019), whereby imperfect produce, by-products of agriculture, waste and overproduction are efficiently used are part of this exploratory research. The authors create an overview of the status quo of the markets using the example of Germany's B2B food supply chain, covering market players, their transport-, sourcing and production strategies and business model applications. Many questions still need to be addressed, including the following: Can innovative business models from different industries be applied to food? Is the platform business model suitable for the reduction of food waste? Is it necessary for retailers - as the final (downstream) tier in the supply chain before the customer - to become more flexible regarding a varying supply of products? How can the sharing economy and regional or local sourcing add to a sustainable food supply chain/network? These and other pertinent questions will the addressed in this exploratory research, for which the answers will be sought by con-ducting interviews with key stakeholders within our network and examining use cases}, language = {en} } @article{KoegelPflitschNorthupetal.2022, author = {K{\"o}gel, Michael and Pflitsch, Andreas and Northup, Diana E. and Carstensen, Dirk and Medley, Joseph J. and Mansheim, Teresa and Killing, Thomas and Buschbacher, Michael and Angerer, Helena and Falkner, Julian and Kynatidis, Achilleas and Ott, Valentin and Regler, Simon}, title = {Combination of close-range and aerial photogrammetry with terrestrial laser scanning to answer microbiological and climatological questions in connection with lava caves}, series = {Applied Geomatics}, volume = {14}, journal = {Applied Geomatics}, number = {4}, publisher = {Springer Science and Business Media LLC}, issn = {1866-9298}, doi = {10.1007/s12518-022-00459-7}, pages = {679 -- 694}, year = {2022}, abstract = {Combining photogrammetric reconstruction (close-range photogrammetry, CRP) and airborne photogrammetry through the structure from motion method (SFM) with terrestrial three-dimensional (3D) laser scanning (TLS), Maelstrom Cave on Big Island, Hawaii (USA), was mapped in three dimensions. The complementary properties of the two methods generated an overall model that depicted significant features of the cave both spatially and visually. Through various processes, the complex geometric quantities were derived from the model that can be used to answer microbiological and climatological questions. In this report, the procedure for the three-dimensional acquisition of the terrain surface above Maelstrom Cave as well as the interior of the cave with TLS and SFM is described. It is shown how the different data sets were combined and contrasted, including a comparison of geometries from the different survey operations. Finally, the editing processes used to quantify and simplify the cave geometry are presented, as well as the analysis of the ellipses generated accordingly to determine the geometric quantities. Through the analysis of the cave geometry, important geometric properties of the Maelstrom Cave could be quantified and categorized. In this way, an effective tool was developed to directly correlate the structure of the cave system with climatological and microbiological parameters in order to answer the corresponding questions.}, language = {en} } @article{RogersSrivastavaTsakouetal.2024, author = {Rogers, Helen and Srivastava, Mohit and Tsakou, Miriam and Prashad, Anisha}, title = {Sustainable supply chain models for 3D printed houses}, series = {Supply Chain Forum}, journal = {Supply Chain Forum}, doi = {10.1080/16258312.2023.2298186}, pages = {1-16}, year = {2024}, abstract = {Although steps have been taken to improve sustainable practices in the construction industry, progress to date has been slow. Advances in 3D printing technology provide a significant opportunity to reconfigure construction industry supply chains to improve its sustainability credentials. This study investigates the adoption of 3D construction printing (3DCP) as a sustainable alternative and/or to augment traditional construction industry supply chains. By analysing six 3DCP organisations and feeding six critical insights into the Business Model Navigator, this study proposes three supply chain models i.e. generative construction service, hybrid service, and emergency service. A generative supply chain model can be used as an on-demand service for customers with limited knowledge of 3DCP. The hybrid model can integrate 3DCP with a traditional construction supply chain to construct part of the building. Finally, the emergency services model can be used to rapidly construct cost-effective housing (e.g for refugees). The adoption of 3D Printing using these supply chain models in housing construction supply chains has the potential to offer considerable benefits both for construction companies and end-users, while at the same time improving sustainability, affordability and productivity.}, language = {en} }