11 Interfakultäre Einrichtungen
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Item Open Access On the accurate estimation of information-theoretic quantities from multi-dimensional sample data(2024) Álvarez Chaves, Manuel; Gupta, Hoshin V.; Ehret, Uwe; Guthke, AnneliUsing information-theoretic quantities in practical applications with continuous data is often hindered by the fact that probability density functions need to be estimated in higher dimensions, which can become unreliable or even computationally unfeasible. To make these useful quantities more accessible, alternative approaches such as binned frequencies using histograms and k -nearest neighbors ( k -NN) have been proposed. However, a systematic comparison of the applicability of these methods has been lacking. We wish to fill this gap by comparing kernel-density-based estimation (KDE) with these two alternatives in carefully designed synthetic test cases. Specifically, we wish to estimate the information-theoretic quantities: entropy, Kullback–Leibler divergence, and mutual information, from sample data. As a reference, the results are compared to closed-form solutions or numerical integrals. We generate samples from distributions of various shapes in dimensions ranging from one to ten. We evaluate the estimators’ performance as a function of sample size, distribution characteristics, and chosen hyperparameters. We further compare the required computation time and specific implementation challenges. Notably, k -NN estimation tends to outperform other methods, considering algorithmic implementation, computational efficiency, and estimation accuracy, especially with sufficient data. This study provides valuable insights into the strengths and limitations of the different estimation methods for information-theoretic quantities. It also highlights the significance of considering the characteristics of the data, as well as the targeted information-theoretic quantity when selecting an appropriate estimation technique. These findings will assist scientists and practitioners in choosing the most suitable method, considering their specific application and available data. We have collected the compared estimation methods in a ready-to-use open-source Python 3 toolbox and, thereby, hope to promote the use of information-theoretic quantities by researchers and practitioners to evaluate the information in data and models in various disciplines.Item Open Access Willingness to pay for digital wellbeing features on social network sites : a study with Arab and European samples(2024) Alshakhsi, Sameha; Babiker, Areej; Sindermann, Cornelia; Al-Thani, Dena; Montag, Christian; Ali, RaianIn recent years, concerns over the potential negative impacts of social network sites (SNS) on users’ digital wellbeing are on the rise. These concerns have sparked a growing demand for SNS to introduce changes to their business model and offer features that prioritize users’ wellbeing, even if it means introducing fees to users. Still, it is questionable whether such a new model is welcomed by users and commercially valid. In this paper, we investigate (i) people’s willingness to pay (WTP) for digital wellbeing services designed to foster more autonomy, control, and personal growth in users and (ii) the influence of sociodemographic variables, personality, and social networks use disorder (SNUD) on WTP. Data were collected through an online survey with participants from two distinct cultural contexts, the European and Arabic. The samples comprised 262 participants from Europe (Males: 57.63%) and 251 from Arab countries (Males: 60.56%). The participants ranged in age from 18 to 66 years (MEurope = 29.16, SD = 8.42; MArab = 31.24, SD = 8.23). The results revealed that a notable proportion of participants were willing to pay for digital wellbeing services (Europe: 24%; Arab: 30%). Females in the European sample demonstrated a higher WTP for “Mental Health Issues Minimization” compared to males. In the Arab sample, males showed a higher WTP for “Safeguarding Data Privacy” than females. Multiple regression analyses revealed that SNUD and the need for cognition emerged as significant and positive predictors of WTP in both the European and Arab samples. Differences in the relations of personality traits and sociodemographic variables on WTP in each sample were noted. These insights contribute to our understanding of the factors shaping individuals’ preferences and valuation related to digital wellbeing services on SNS and highlight the importance of considering sociodemographic variables and personal factors as well as cultural contexts when planning and introducing them.Item Open Access SyKonaS - Projektbericht. Nr. 4, Entwicklung und Anpassung von Instrumenten zur Konfliktbearbeitung im Rahmen der Energiewende(Stuttgart : Verbundvorhaben SyKonaS, Zentrum für interdisziplinäre Risiko- und Innovationsforschung der Universität Stuttgart (ZIRIUS), 2024) Püttner, Andreas; Liebhart, Laura; Wolf, Patrick; Jaschek, Carolin; León, Christian D.; Wassermann, Sandra; Wegner, Nils; Klug, Katharina; Otto, JonasDas Forschungsprojekt "SyKonaS - Systemische Konfliktanalyse mittels Szenariotechnik" hat zum Ziel, gesellschaftliche Konflikte und deren Wechselwirkungen in der Energiewende zu verstehen, zu antizipieren und Lösungsvorschläge zu entwickeln. Ein Teil des Projekts setzt sich mit der Identifikation und Weiterentwicklung von Instrumenten auseinander, die dazu beitragen sollen bzw. können, die im Rahmen des Projekts identifizierten Konflikte der Energiewende im Stromsektor zu mindern. Um die als besonders relevant identifizierten Konfliktfelder möglichst deckend bespielen und Lücken im bestehenden Instrumentenkasten schließen zu können, werden zum Teil bereits bestehende Instrumente weiterentwickelt und zum anderen neue Instrumente aufgegriffen, die in Deutschland bisher noch nicht in dieser Form umgesetzt sind.Item Open Access Uncharted water conflicts ahead : mapping the scenario space for Germany in the year 2050(2024) Kosow, Hannah; Brauner, Simon; Brumme, Anja; Hauser, Wolfgang; Hölzlberger, Fabian; Moschner, Janina; Rübbelke, Dirk; Vögele, Stefan; Weimer-Jehle, WolfgangIntroduction: In recent years, conflicts surrounding the use, distribution, and governance of surface water and groundwater in Germany have gained prominence in the media, on the political agenda, and in research. Increasing effects of climate change, such as heatwaves and drought but also extreme rain events and flooding, are considered to become more prominent and pressing in the future by different societal actors. However, it remains highly uncertain if and what type of conflicts related to water quantity Germany might actually face in the future (and how they will be framed). This paper addresses one dimension of this uncertainty - namely the future context uncertainty of possible resource and water governance conflicts. Our research contributes to an improved understanding of the uncertainty concerning future climatic, natural, land use related, political, economic, and other societal contexts that could impact water conflicts. Method: We ask: What are possible coherent context scenarios for Germany in the year 2050, and how are they expected to influence future water conflicts? In an expert-based process, we apply a qualitative and systematic method of systems analysis, cross-impact balances (CIB). With CIB, we build internally consistent scenarios of possible futures and map the future scenario space. Results and discussion: Diversity mapping with a new CIB web application of the ScenarioWizard reveals that the scenario space is rather large and diverse. The identified scenario space of n = 355 internally consistent scenarios spans four most diverse scenarios “Polycrisis,” “Economy and agriculture in crisis,” “Growth through adaptation to climate change,” and “Sustainable transformation.” Depending on the development of future contexts, the risk for future water resource and governance conflicts may unfold in various ways. We conclude that our scenario analysis provides a useful base for research and practice to address the context uncertainty of water conflicts in Germany. Our results can be used for risk assessment, to define societal framework assumptions for societal-hydrological modeling, and to develop robust and adaptive strategies and policies.Item Open Access Akteurskonflikten in der Energiewende gegensteuern : Impulse für die Instrumentenentwicklung : Impulspapier - SyKonaS(Stuttgart : Verbundvorhaben SyKonaS, Koordination: Zentrum für interdisziplinäre Risiko- und Innovationsforschung der Universität Stuttgart (ZIRIUS), 2024) Jaschek, Carolin; León, Christian D.; Liebhart, Laura; Püttner, Andreas; Wolf, Patrick; Klug, Katharina; Otto, Jonas; Wegner, Nils; Dreyer, Marion; Dreyer, Marion (Redaktion); Dratsdrummer, Frank (Redaktion); Witzel, Bianca (Redaktion)Dieses Impulspapier adressiert gesellschaftliche Energiewendekonflikte als politisches und rechtliches Handlungsfeld und präsentiert eine Reihe von Instrumentenoptionen für die Bearbeitung von bereits bestehenden und möglichen zukünftigen Akteurskonflikten im Kontext der Energiewende. Der Fokus liegt auf der Konfliktbearbeitung bei der Transformation des Stromsektors und auf drei ausgewählten Konfliktfeldern: Gerechtigkeit und Kosten-/Lastenverteilung, Flächennutzung und Partizipation.Item Open Access To bucket or not to bucket? : analyzing the performance and interpretability of hybrid hydrological models with dynamic parameterization(2024) Acuña Espinoza, Eduardo; Loritz, Ralf; Álvarez Chaves, Manuel; Bäuerle, Nicole; Ehret, UweHydrological hybrid models have been proposed as an option to combine the enhanced performance of deep learning methods with the interpretability of process-based models. Among the various hybrid methods available, the dynamic parameterization of conceptual models using long short-term memory (LSTM) networks has shown high potential. We explored this method further to evaluate specifically if the flexibility given by the dynamic parameterization overwrites the physical interpretability of the process-based part. We conducted our study using a subset of the CAMELS-GB dataset. First, we show that the hybrid model can reach state-of-the-art performance, comparable with LSTM, and surpassing the performance of conceptual models in the same area. We then modified the conceptual model structure to assess if the dynamic parameterization can compensate for structural deficiencies of the model. Our results demonstrated that the deep learning method can effectively compensate for these deficiencies. A model selection technique based purely on the performance to predict streamflow, for this type of hybrid model, is hence not advisable. In a second experiment, we demonstrated that if a well-tested model architecture is combined with an LSTM, the deep learning model can learn to operate the process-based model in a consistent manner, and untrained variables can be recovered. In conclusion, for our case study, we show that hybrid models cannot surpass the performance of data-driven methods, and the remaining advantage of such models is the access to untrained variables.Item Open Access Kontrollierte Grundwasseranreicherung (MAR): Ein Beitrag zur Lösung der Wasserprobleme in Lima, Peru : Abschlussbericht des Projekts NEWA-LIMA(Stuttgart : Universität Stuttgart, 2025) Fesch, Katharina; Hügler, Michael; León, Christian D.; Perez, Hiraida; Stauder, Stefan; Xanke, JulianDas vom Bundesministerium für Umwelt, Naturschutz, nukleare Sicherheit und Verbraucherschutz (BMUV) im Rahmen der Exportinitiative Umweltschutz geförderte Forschungsprojekt „NEWA-LIMA: Neue Wasserressourcen und innovative Abwasserbehandlung für aride Metropolregionen am Beispiel von Lima, Peru“ (Laufzeit: 2022-2024) hatte zum Ziel, die kontrollierte Grundwasseranreicherung (MAR, Managed Aquifer Recharge) als naturbasiertes und kostengünstiges Verfahren zur langfristigen Nutzung der Grundwasserressourcen aufzuzeigen und so einen Beitrag zur Lösung der Wasserprobleme in Lima/Peru zu leisten. Lima zählt zu den trockensten Metropolregionen der Welt, so dass die Wasserversorgung der 10 Mio. Einwohner zzgl. Industrie sowie Gewerbe eine enorme Herausforderung darstellt und in den kommenden Jahren sehr große Investitionen erfordert. Die lokalen Flüsse führen nur während der Regenzeit in den Anden für wenige Monate im Jahr Wasser und die Grundwasserressourcen sind begrenzt. Der vorliegende Bericht stellt die im Projekt entwickelten Lösungsansätze und erzielten Ergebnisse vor. Nach umfassenden Voruntersuchungen wurde auf dem Gelände einer Kläranlage im Lurín-Tal eine MAR-Pilotanlage errichtet. Sie bestand aus drei Erdbecken zur Versickerung von gereinigtem Abwasser sowie mehreren Kontrollbrunnen und wurde in Zusammenarbeit mit dem Wasserver- und Abwasserentsorger von Lima (SEDAPAL) über die Dauer von 17 Monaten betrieben. Die Reinigungsleistung der Bodenpassage wurde dabei durch umfangreiche mikrobiologische und chemische Wasseranalytik erfasst, einschließlich anthropogener Spurenstoffe und der neuartigen „wirkungsbezogenen Analytik“ (WBA). Begleitende kleintechnische Untersuchungen mit Aktivkohleadsorption und Umkehrosmose bewerteten den Einsatz dieser weitergehenden Aufbereitungstechnologien. Zudem erfolgte eine Prüfung der rechtlichen Rahmenbedingungen und der sozialen Implikationen von MAR-Vorhaben in Peru. Die Erarbeitung eines lokalen Grundwassermodells sowie eines Konzepts für den Einsatz von Tropfkörpern in der Abwasserreinigung dienten dazu, konkrete Empfehlungen für eine großtechnische MAR-Anwendung im Lurín-Tal ableiten zu können.Item Open Access Gestión de la Recarga del Acuífero: una contribución a la solución del problema del agua en Lima, Perú : informe final del proyecto NEWA-LIMA(Stuttgart : Universität Stuttgart, 2025) Fesch, Katharina; Hügler, Michael; León, Christian D.; Perez, Hiraida; Stauder, Stefan; Xanke, Julian; Manrique, Elizabeth (Übersetzerin)El proyecto NEWA-LIMA “Nuevos recursos hídricos y tratamiento innovador de aguas residuales para regiones metropolitanas áridas, tomando como ejemplo Lima, Perú”, financiado por el Ministerio del Ambiente de Alemania (BMUV) durante el período 2022 a 2024 tuvo como objetivo demostrar que la Recarga Gestionada de Acuíferos es un método natural y de bajo costo para el uso a largo plazo de los recursos hídricos subterráneos, contribuyendo de este modo a la solución de los problemas de agua en Lima. Lima es una de las regiones metropolitanas más áridas del mundo, por lo que el abastecimiento de agua para sus 10 millones de habitantes, así como para la industria y el comercio, representa un gran desafío que requerirá de inversiones significativas en los próximos años. Los ríos locales llevan agua solamente durante la época de avenida en los Andes y los recursos de agua subterránea son limitados. Este informe presenta las soluciones desarrolladas y los resultados obtenidos en este proyecto. Tras exhaustivas investigaciones preliminares, se construyó una planta piloto MAR en el terreno de una planta de tratamiento de aguas residuales (PTAR) en el valle del río Lurín. Constó de tres pozas de tierra para la infiltración de las aguas residuales tratadas, así como varios piezómetros. Fue operada en colaboración con la Empresa de Servicio de Agua Potable y Alcantarillado de Lima (SEDAPAL) durante un periodo de 17 meses. El rendimiento de depuración del paso por el suelo fue registrado mediante exhaustivos análisis microbiológicos y químicos del agua, incluidas sustancias antropogénicas y el innovador “análisis relacionado con el impacto” (WBA). Las investigaciones complementarias a pequeña escala con adsorción de carbón activado y ósmosis inversa evaluaron el uso de estas tecnologías avanzadas de tratamiento de agua. Se revisó el marco legal vigente y las implicaciones sociales de los proyectos MAR en Perú. La elaboración de un modelo local de aguas subterráneas y de un concepto para el uso de filtros percoladores en el tratamiento de aguas residuales sirvieron para definir recomendaciones respecto a una aplicación MAR a gran escala en el valle de Lurín.Item Open Access Semi-explicit integration of second order for weakly coupled poroelasticity(2024) Altmann, R.; Maier, R.; Unger, B.We introduce a semi-explicit time-stepping scheme of second order for linear poroelasticity satisfying a weak coupling condition. Here, semi-explicit means that the system, which needs to be solved in each step, decouples and hence improves the computational efficiency. The construction and the convergence proof are based on the connection to a differential equation with two time delays, namely one and two times the step size. Numerical experiments confirm the theoretical results and indicate the applicability to higher-order schemes.Item Open Access Higher-order iterative decoupling for poroelasticity(2024) Altmann, Robert; Mujahid, Abdullah; Unger, BenjaminFor the iterative decoupling of elliptic–parabolic problems such as poroelasticity, we introduce time discretization schemes up to order five based on the backward differentiation formulae. Its analysis combines techniques known from fixed-point iterations with the convergence analysis of the temporal discretization. As the main result, we show that the convergence depends on the interplay between the time step size and the parameters for the contraction of the iterative scheme. Moreover, this connection is quantified explicitly, which allows for balancing the single error components. Several numerical experiments illustrate and validate the theoretical results, including a three-dimensional example from biomechanics.