Universität Stuttgart
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Item Open Access Strukturierte Modellierung von Affekt in Text(2020) Klinger, Roman; Padó, Sebastian (Prof. Dr.)Emotionen, Stimmungen und Meinungen sind Affektzustände, welche nicht direkt von einer Person bei anderen Personen beobachtet werden können und somit als „privat“ angesehen werden können. Um diese individuellen Gefühlsregungen und Ansichten dennoch zu erraten, sind wir in der alltäglichen Kommunikation gewohnt, Gesichtsausdrücke, Körperposen, Prosodie, und Redeinhalte zu interpretieren. Das Forschungsgebiet Affective Computing und die spezielleren Felder Emotionsanalyse und Sentimentanalyse entwickeln komputationelle Modelle, mit denen solche Abschätzungen automatisch möglich werden. Diese Habilitationsschrift fällt in den Bereich des Affective Computings und liefert in diesem Feld Beiträge zur Betrachtung und Modellierung von Sentiment und Emotion in textuellen Beschreibungen. Wir behandeln hier unter anderem Literatur, soziale Medien und Produktbeurteilungen. Um angemessene Modelle für die jeweiligen Phänomene zu finden, gehen wir jeweils so vor, dass wir ein Korpus als Basis nutzen oder erstellen und damit bereits Hypothesen über die Formulierung des Modells treffen. Diese Hypothesen können dann auf verschiedenen Wegen untersucht werden, erstens, durch eine Analyse der Übereinstimmung der Annotatorinnen, zweitens, durch eine Adjudikation der Annotatorinnen gefolgt von einer komputationellen Modellierung, und drittens, durch eine qualitative Analyse der problematischen Fälle. Wir diskutieren hier Sentiment und Emotion zunächst als Klassifikationsproblem. Für einige Fragestellungen ist dies allerdings nicht ausreichend, so dass wir strukturierte Modelle vorschlagen, welche auch Aspekte und Ursachen des jeweiligen Gefühls beziehungsweise der Meinung extrahieren. In Fällen der Emotion extrahieren wir zusätzlich Nennungen des Fühlenden. In einem weiteren Schritt werden die Verfahren so erweitert, dass sie auch auf Sprachen angewendet werden können, welche nicht über ausreichende annotierte Ressourcen verfügen. Die Beiträge der Habilitationsarbeit sind also verschiedene Ressourcen, für deren Erstellung auch zugrundeliegende Konzeptionsarbeit notwendig war. Wir tragen deutsche und englische Korpora für aspektbasierte Sentimentanalyse, Emotionsklassifikation und strukturierte Emotionsanalyse bei. Des Weiteren schlagen wir Modelle für die automatische Erkennung und Repräsentation von Sentiment, Emotion und verwandten Konzepten vor. Diese zeigen entweder bessere Ergebnisse, als bisherige Verfahren oder modellieren Phänomene erstmalig. Letzteres gilt insbesondere bei solchen Methoden, welche auf durch uns erstellte Korpora ermöglicht wurden. In den verschiedenen Ansätzen werden wiederkehrend Konzepte gemeinsam modelliert, sei es auf der Repräsentations- oder der Inferenzebene. Solche Verfahren, welche Entscheidungen im Kontext treffen, zeigen in unserer Arbeit durchgängig bessere Ergebnisse, als solche, welche Phänomene getrennt betrachten. Dies gilt sowohl für den Einsatz künstlicher neuronaler Netze, als auch für die Verwendung probabilistischer graphischer Modelle.Item Open Access Perceptions of threat and policy attitudes : the case of support for anti-terrorism policies in Germany(2019) Trüdinger, Eva-Maria; Bernhagen, Patrick (Prof. Dr.)Item Open Access Weak or strong : on coupled problems in continuum mechanics(2010) Markert, Bernd; Ehlers, Wolfgang (Prof. Dr.-Ing.)The present work aims at giving a concise introduction to the vast field of coupled problems, particularly to those of importance in engineering and physics. Therefore, the common terminology and an appropriate classification of coupled equation systems is presented accompanied by some mathematical and computational issues. Attention is focused on volumetrically coupled multi-field formulations arising from the continuum mechanical treatment of multi-physics problems, but also geometrically coupled problems are addressed. Based on actual problems in the areas of poroelastodynamics, continuum biomechanics, and fluid-saturated porous media in general both the theoretical modeling by means of coupled continuum equations as well as the efficient numerical solution in the context of the finite element method (FEM) are presented and discussed in a problem-oriented fashion.Item Open Access Hydrogeodesy : a Bayesian perspective(2025) Tourian, Mohammad J.; Sneeuw, Nico (Prof. Dr.)While historically focused on local scales, modern hydrologic studies have increasingly adopted a global perspective, recognizing water as a finite resource and the interconnection between regions. This global perspective puts hydrology within the water cycle framework, offering a comprehensive view of water dynamics across regions and scales. Despite this framework’s conceptual clarity, accurately quantifying the global water cycle remains challenging due to the complexity of capturing localized and large-scale patterns, variations in topography, climate, and land use, as well as temporal variability. These complexities hinder comprehensive measurements, resulting in knowledge gaps around key water cycle components, including river discharge, surface water storage, soil moisture dynamics, and subsurface water storage and flow. Inspired by the existing knowledge gaps in the water cycle, an emerging field known as Hydrogeodesy comes to the forefront. Hydrogeodesy is the discipline that uses terrestrial and primarily spaceborne geodetic data, both geometric and gravimetric, to support global water cycle quantification. Utilizing technologies such as satellite altimetry, gravimetry, imaging, InSAR, GNSS, and GNSS-Reflectometry, hydrogeodesy offers direct or indirect measurements of key water cycle components, including terrestrial water storage, and river discharge, significantly advancing our understanding of water dynamics. Despite advancements in spaceborne geodetic sensors, hydrogeodesy faces challenges such as limitations in the spatiotemporal resolution of satellite measurements, measurement uncertainties, unobserved variables, inconsistencies in background models, and the difficulty of separating aggregated measurements. Possible solutions to these challenges involve combining different data types, including satellite, ground-based observations, and model outputs, to benefit from their complementary strengths. However, this presents its own challenges, as it requires reconciling datasets with varying resolutions, accuracies, and temporal scales. To address some of the challenges listed above, Bayesian approaches offer viable solutions by providing probabilistic interpretations and uncertainty quantification. Bayesian approaches offer a robust framework for updating prior knowledge with new data to yield a posterior distribution, enabling a probabilistic interpretation and explicit uncertainty estimation of parameters. This is especially valuable in hydrogeodesy, where parameters like river discharge, soil moisture, and groundwater storage are often estimated indirectly and carry substantial uncertainties. This habilitation thesis provides a foundational discussion on Bayesian modeling and statistics and demonstrates the versatility and power of Bayesian methods in enhancing our understanding of water cycle components by presenting three distinct Bayesian applications in hydrogeodesy. The first study applies a Bayesian approach, specifically the Kalman filter, to estimate river discharge using spaceborne geodetic measurements. In hydrogeodetic studies, the Kalman filter and dynamic systems are especially valuable, as they enable the integration of multiple data sources and the continuous updating of estimates with incoming measurements. This is particularly beneficial for river systems, which inherently function as a dynamic system. To assess this potential, a method is introduced that uses the cyclostationary properties of discharge as prior information, while observed altimetric discharge data provide the likelihood. Together, these yield a posterior providing an unbiased daily discharge estimate. The method is applied to the Niger River basin and its main tributaries and validated against in situ data from 18 gauges. Results show a high average Correlation Coefficient (CC) of 0.9 and an average relative Root Mean Squared Error (RMSE) and bias of 15%. This method effectively estimates daily river discharge across entire basins and shows promise for global application, especially in data-scarce regions. With satellite altimetry data from multiple virtual stations and historical discharge data, daily discharge estimates with an error under 20% could be attainable in many river basins worldwide. The growing availability of spaceborne geodetic data, such as that provided by SWOT, further enhances this potential by delivering comprehensive measurements of river height and width, along with global discharge estimates. In most real-world applications, including hydrogeodesy, the Gaussianity assumption required by the Kalman filter does not hold, limiting its applicability. Inspired by this challenge, and motivated by the need to overcome the limitations of the poor spatial resolution of the GRACE and GRACE-FO missions, the second study proposes a Bayesian method to downscale GRACE data, proposing a nonparametric method to infer the posterior distribution directly, without any assumption for the likelihood or posterior. The prior distribution is obtained based on GRACE data values using the monthly variation of GRACE data. To model the likelihood functions, copulas are employed to capture dependencies among multivariate distributions. Monthly empirical copulas are constructed and fitted to analytical copulas, conditioned on specific quantile values, reflecting the dependency between GRACE and fine-scale data. A key advantage of this copula-supported Bayesian approach is its capacity to represent uncertainties in both data and models, even with variable input quality. The proposed downscaling approach is applied to the Amazon Basin, utilizing four different fine-scale datasets: WGHM, PCR-GLOBWB, SURFEX-TRIP, and the ensemble of flux data and soil moisture data from GLEAM and ASCAT. Validation is conducted against two independent datasets: space-based Surface Water Storage Change (SWSC) and GPS-observed Vertical Crustal Displacement Change (VCDR). In SWSC validation, downscaled results capture spatial variations in river storage with high CC and a relative RMSE of 26%. VCDR validation involves two analyses: comparing GPS-VCDR with TWSF-based VCDR using Green’s function convolution, where downscaled products yield RMSE values between 2.27 and 5.65 mm/month, outperforming input fine-scale data with 14 mm/month RMSE. In terms of CC, downscaled results achieve an average value of -0.81 versus -0.73 for the input. The proposed Bayesian framework effectively downscales GRACE data, with performance highly dependent on input data quality. The copula-supported Bayesian approach offers valuable uncertainty quantification even with inconsistent input data. This method aids in understanding water storage variations in small catchments, supporting local hydrological studies, and can be applied to other water cycle parameters as an alternative to traditional methods. Although a direct posterior is obtained for each grid cell in the downscaling study, spatial dependencies among neighboring grid cells are not considered. Graphical models are particularly well-suited for capturing such spatial dependencies. To address this limitation - and inspired by the challenge of noisy water level estimates from satellite altimetry over inland water bodies - the third study presents a Bayesian approach that formulates a probabilistic graphical model known as a Markov Random Field (MRF), with a Maximum A Posteriori estimation of the MRF (MRF-MAP) as the objective. There to improve inland altimetry, a retracking method is proposed. Unlike conventional retracking methods that target a single waveform point, a holistic approach by identifying retracking lines within 2D radargrams, treating the radargram as a segmented image. This segmentation divides the radargram into Front and Back segments, resembling a binary image segmentation task. The proposed MRF-MAP framework uses spatial dependencies as prior information, with the likelihood based on the temporal evolution of pixel labels across groundtrack cycles. Two temporal energy functions are applied: 1D, based solely on pixel intensity, and 2D, which includes both intensity and bin values, with the posterior probability maximized using the maxflow algorithm. The maxflow algorithm is then applied to obtain MAP solution, yielding a segmented radargram where the retracking line is defined as the boundary between segments. The proposed retracker method is applied to both pulse-limited and SAR altimetry datasets across nine U.S. lakes and reservoirs with varying altimetry characteristics. Validated against in situ data, the proposed method improves RMSE by approximately 0.25 m with the 1D temporal energy function and 0.51 m with the 2D function. The main advantage of the proposed method is its robustness against unexpected waveform variations, making it especially valuable for complex radargrams where conventional retrackers often deliver outliers. By integrating both spatial and temporal information, this method offers a more comprehensive understanding of the data and has broad applicability, such as improving the classification of SWOT pixel cloud points by incorporating spatiotemporal detail. Through these case studies, the thesis illustrates the advantages of Bayesian approaches in improving the accuracy and reliability of hydrological estimates - such as river discharge, terrestrial water storage, and water level measurements - derived from spaceborne geodetic sensors. By integrating theoretical insights with practical applications, the thesis demonstrates how Bayesian methods can effectively improve spatiotemporal resolution, obtain uncertainties, enhance data fusion, and accommodate the complexities inherent in hydrological systems. This combination of foundational knowledge and real-world examples shall establish a base for advancing the use of Bayesian approaches in hydrogeodetic research and beyond. Moreover, by highlighting the challenges in hydrogeodesy, this thesis provides a clear direction for future research and development in the field. It emphasizes critical areas requiring attention, such as improving the spatial and temporal resolution of hydrological estimates, addressing inherent uncertainties in geodetic observations, and developing more effective methods for assimilating diverse data sources. The thesis encourages the refinement of geodetic data processing techniques and the adoption of probabilistic frameworks, such as Bayesian modeling, in future work. Building upon the work presented here, future studies can ultimately achieve more accurate and reliable insights into the Earth's systems.Item Open Access Kraft-Wärme-Kopplung im Wärmemarkt Deutschlands und Europas : eine Energiesystem- und Technikanalyse(2014) Blesl, Markus; Voß, Alfred (Prof. Dr.-Ing.)Im Wärmemarkt stehen seit Jahren unterschiedlichste Wärmeversorgungstechnologien auf Basis fossiler und erneuerbarer Energieträger, sowie Strom und Fernwärme untereinander als auch mit Einsparoptionen im Wettbewerb. Ein Großteil des Endenergieverbrauchs in Deutschland und der EU27 wird heute und zukünftig für die Deckung der Wärmenachfrage aufgewendet. Der Wärmemarkt steht damit im Fokus energiepolitischer und –wirtschaftlicher Fragestellungen. Ziel der Ausführungen ist es, mögliche Einflussfaktoren auf den Wärmemarkt in Deutschland und Europa zu analysieren. Die Auswirkungen hinsichtlich der Struktur der eingesetzten Energieträger und Technologien bis zum Jahr 2050 werden untersucht. Ein Schwerpunkt wird hierbei auf die Untersuchung der Rolle der Kraft-Wärme-Kopplung (KWK) und Fernwärme gelegt. Die Bewertung der KWK und Fernwärme und deren Vergleich zur getrennten Erzeugung hängen von der gewählten Versorgungsaufgabe ab. Entsprechend werden unterschiedliche Rangfolgen gekoppelter und ungekoppelter Wärmeversorgungstechnologien bei einer Analyse mit Hilfe von CO2-Vermeidungskosten, der ganzheitlichen Bilanzierung und einer para-metrisierten Versorgungsaufgabe ermittelt. Für die Beurteilung der energetischen, umweltseitigen und kostenseitigen Implikationen un-terschiedlicher Versorgungssysteme im Wärmemarkt wird eine detaillierte länderspezifische Untersuchung mittels einer Energiesystemanalyse durchgeführt. Hierfür wird das paneuropäi-sche Energiesystemmodell TIMES PanEU entwickelt, in welchem sowohl länderspezifische und sektoral differenzierte Versorgungstechnologien des Wärmemarktes als auch die beste-henden Versorgungsstrukturen modelliert sind. Die Entwicklung der Wärmenachfrage auf Nutzenergieebene wird basierend auf Simulationsergebnissen vorgegeben. So reduziert sich beispielsweise der spezifische Wärmebedarf des Gebäudebestandes in Deutschland bis zum Jahr 2050, trotz regulatorischer Vorgaben z. B. hinsichtlich des Gebäudestandards sowie de-ren Fortschreibung, aufgrund der aktuellen energetischen Sanierungszyklen und -quoten le-diglich auf Neubaustandard des Jahres 2007. Die Ergebnisse der Szenarienanalysen mit dem Energiesystemmodell TIMES PanEU zeigen, dass fossile Energieträger in wesentlich größerem Maße als Elektrowärmeanwendungen und der Einsatz von erneuerbaren Energien im Wärmemarkt von politischen Vorgaben (z.B. einem Treibhausgasminderungsziel) beeinflusst werden. Die Rolle der Fernwärme wird in erheblicher Weise dadurch bestimmt, ob diese quasi CO2-frei erzeugt werden kann. Optionen hierfür bestehen in Form von KWK-Anlagen auf Basis fossiler Energieträger mit CO2-Abscheidung und Speicherung, auf Basis von Geothermie oder Biomasse sowie durch Wärmepumpen und Solarthermie. Das technische und wirtschaftliche Potenzial dieser Erzeugungsoptionen ist ein limitierender Faktor für den Ausbau der Fern- und Nahwärmeversorgung in Deutschland.Item Open Access On the computational modeling of micromechanical phenomena in solid materials(2013) Linder, Christian; Miehe, Christian (Prof. Dr.-Ing. habil.)This work aims to contribute to the research on the constitutive modeling of solid materials, by investigating three particular micromechanical phenomena on three different length scales. The first microscopic phenomenon to be considered on the macroscopic scale is the process of failure in solid materials. Its characteristic non-smoothness in the displacement field results in the need for sophisticated numerical techniques in case one aims to capture those failure zones in a discrete way. One of the few finite element based methods successfully applied to such challenging problems is the so called strong discontinuity approach, for which failure can be described within the individual finite elements. To avoid stress locking, a higher order approximation of the resulting strong discontinuities is developed in the first part of this work for both, purely mechanical as well as electromechanical coupled materials. A sophisticated crack propagation concept relying on a combination of the widely used global tracking algorithm and the computer graphics based marching cubes algorithm is employed to obtain realistic crack paths in three dimensional simulations. Secondly, materials with an inherent network microstructures such as elastomers, hydrogels, non-woven fabrics or biological tissues are considered. The development of advanced homogenization principles accounting for such microstructures is the main focus in the second part of this work to better understand the mechanical and time-dependent effects displayed by such soft materials. Finally, the incorporation of wave functions into finite element based electronic structure calculations at the microscopic scale aims to account for the fact that the properties of condensed matter as for example electric conductivity, magnetism as well as the mechanical response upon external excitations are determined by the electronic structure of a material.Item Open Access Modeling the long-term behavior of structural timber for typical serviceclass-II-conditions in South-West Germany(2010) Schänzlin, Jörg; Kuhlmann, Ulrike (Prof. Dr.-Ing.)Creep deformation influences the serviceability limit state as well as the ultimate limit state of timber structures. In order to consider this time-dependent behavior, creep coefficients and rheological models have been developed by various researchers. Comparing the rheological models, quite different temporal deformations are evaluated for a duration of load of 50 ears. In order to find the model, which is most suitable to the situation in the region of Tübingen, South-West Germany, the existing deformations of several beams in roof structures in opened, protected but not heated buildings are measured. By loading the structure the elastic global stiffness of the particular element is determined. So creep coefficients can be evaluated, which should have been used by the engineer in order to get the existing deflection fter 50 years. Within the region of Tübingen, on average a creep coefficient of 2.23 was found based on these measurements. However, the standard deviation of 0.97 is quite large. For the numerical evaluation of the time-dependent behavior Toratti’s model is modified, so that it matches the measured deformations. This modified model is verified by an additional set of measurements in the region of Breisgau-Hochschwarzwald, where the influence of the snow on the creep coefficient has to be taken into account. However, the application of the modified model takes too much time due to the numerical solutions of the single time steps. By means of a case study, functions are fitted to the results of the models in order to develop “simple” functions for the determination of the creep coefficient with respect to the main influences. The creep deformation influences the ultimate limit state especially in composite structures or elements subjected to compression. For this reason, the influence of the increased creep strain is approximated for columns, in order to reach the same safety level as proposed in the current regulations in DIN 1052. Additionally, the design procedure for timber-concrete-composite structures is modified in order to consider the increased creep coefficients.Item Open Access State of the art of the co-incineration of waste-derived fuels and raw materials in clinker/cement plants(2021) Schönberger, Harald; Garrecht, Harald (Prof. Dr.-Ing.)The treatise is about the co-incineration of waste-derived fuels and raw materials in clinker/cement production plants and its impact on emissions to air. Depending on the incineration conditions, emissions to air can exceed existing requirements. This is demonstrated and explained by both conventional parameters such as dust, nitrogen oxides, sulphur dioxide, carbon monoxide, volatile organic carbon, mercury and other heavy metals, ammonia and hydrogen chloride and special organic pollutants such as benzene, polychlorinated dibenzo-p-dioxins and furans (PCCD/F), polychlorinated biphenyls (PCB), hexachlorobenzene (HCB) and polycyclic aromatic hydrocarbons (PAH).Item Open Access Advanced methods for a sustainable sediment management of reservoirs(Stuttgart : Eigenverlag des Instituts für Wasser- und Umweltsystemmodellierung der Universität Stuttgart, 2022) Haun, Stefan; Wieprecht, Silke (Prof. Dr.-Ing.)As a result of an increasing demand on storing water, sustainable reservoir management will become more and more important in the future. Minimizing, or in the best case avoiding, the loss of storage due to sedimentation is a challenging task because each reservoir has unique boundary conditions. Hence, not every management strategy is suitable for a given reservoir. Due to the combination of state of the art measurement methods and hydro‐morphodynamic models, reservoir sedimentation can be better predicted in the future and the success of sediment management strategies can be assessed. The development of advanced measurement methods makes it possible to obtain data with a high accuracy, but also with a high spatial and temporal resolution. The combination of recent measurement approaches with reliable hydro‐morphodynamic numerical prediction models, enhances a highly accurate prediction and understanding of governing processes. This opens new possibilities for an objective selection of important parameters, essential spatial domains as well as for the temporal resolution of measurements. This will finally lead to more reliable predictions about the future of reservoirs that provide water for human life, health and wealth. The presented scientific work gives an overview of recent developments to investigate hydromorphological processes in reservoirs.Item Open Access Thermofluids with porous media(2024) Chu, Xu; Weigand, Bernhard (Prof. Dr.-Ing. habil.)