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Individual Information Sovereignty: User Perspectives and Digital Interventions for Navigating Privacy and Misinformation
No full textIn an ever more complex and opaque digital information landscape, individuals increasingly share sensitive data and rely on various digital sources for information.
In doing so, they face increasing challenges in engaging with digital information flows.
This dissertation explores two critical directions of digital information flows: (1) the disclosure of sensitive information related to privacy and (2) the consumption of information, with a particular focus on misinformation.
To effectively address these challenges, individuals require support in regaining their information sovereignty, which this dissertation conceptualises as a form of autonomy, control, and competence in navigating digital information flows related to privacy and misinformation.
Overall, this dissertation provides a user-centred perspective rooted in Human-Computer Interaction to explore conceptual and methodological insights, user perspectives, and design implications for digital interventions with the overarching aim of supporting Individual Information Sovereignty.
To do this, this dissertation employs a range of qualitative and quantitative research methods, including representative surveys, interviews, focus groups, think-aloud studies, and online experiments.
Findings on conceptual and methodological insights demonstrate how precise operationalisation and measurement of concepts such as privacy and corresponding behaviour are essential prerequisites for accurately determining user needs.
Findings on user perspectives highlight diverse, context-dependent, and evolving perspectives and patterns in digital technology use as well as support needs.
Users express a fundamental tension between the advantages of digital information availability and the risk of information overload, leading to challenges in maintaining control over digital information flows.
In the context of emergencies, for example, the use of social media is especially hindered by perceived privacy implications and the risk of false rumours.
In general, users desire greater transparency and comprehensibility when navigating privacy and misinformation, suggesting that interventions should prioritise empowering user autonomy through tailored, clear and well-structured information.
Finally, findings on design implications for digital interventions to support navigating privacy and misinformation highlight the potential of transparent and personalised approaches. For instance, personalised cookie banners tailored to users' privacy knowledge reduce the acceptance of browser cookies. Additionally, personalised nudges and transparent, indicator-based interventions support the identification of misleading information in text, videos, and charts.
Overall, this dissertation demonstrates the heterogeneity of user perspectives and the potential of transparent and personalised interventions to support Individual Information Sovereignty. This approach aims to empower users to navigate digital information flows in a more informed and self-determined way
Risikotechnologien in europäischen Mediendiskursen : Der korpuslinguistische Zugriff am Beispiel „Biotechnologie“
No full textIn diesem Beitrag wird exemplarisch vorgeführt, wie sprachstatistische Verfahren, die im Rahmen der sog. „Korpuslinguistik“ entwickelt werden, im Bereich der Risikoforschung eingesetzt werden können. Es wird gezeigt, wie einzelne Technologien in Medientexten als Risiken thematisiert werden und was daraus jeweils für die Konzeptualisierung von „Risiko“ folgt. Korpuslinguistische Verfahren ermöglichen einen großflächigen Zugriff auf sprachliche Ordnungsmuster, die mit der entsprechenden Heuristik als Spuren begrifflich gefasster Perspektiven auf Sachverhalte interpretiert werden können. Beispielhaft werden im folgenden Beitrag Korpusdaten zur Wahrnehmung von Grüner Gentechnik als Risikotechnologie aus der deutschen, englischen und italienischen Presse dargestellt. Dabei zeigt sich, dass der Risikobegriff jeweils Eigenheiten aufweist, die sich in einer je spezifischen Überlagerungssituation von nationalen Bewertungstraditionen und der je thematischen Technologie formieren. Durch den Einsatz der Korpuslinguistik lassen sich kollektive Einstellungen und Denkmuster zu Risiken nicht nur erahnen und am Einzelfall zeigen, sondern in ihrem Ausmaß und ihrer gesellschaftlichen Relevanz im Wortsinne ermessen. Auf diese Weise lassen sich verlässliche Daten über die Einstellung öffentlicher Akteure zu Risikotechnologien erheben und als Basis für gesellschaftliche, wissenschaftliche und politische Beratungen fruchtbar machen
The interplay of selective occupation and magnetic properties of high entropy spinel oxides
No full textWe investigate the interplay between the selective occupation (cationic site and valence preferences) and magnetic properties of three high entropy spinel oxides (HESOs). One of the samples ((Co,Cr,Fe,Mn,Ni)O) is well known in the literature, while the other two HESOs ((Co,Fe,Mn)O, (Co,Fe,Mn,Ni)O) are unstudied. XAS and RIXS of the transition metal L-edge, and ligand field theory (LFT) calculations were also used to determine the selective occupation. We found that nickel and chromium assume exclusively and sites, respectively. Iron undergoes a transition from to with increasing entropy. Manganese and cobalt adapt according to the remaining cations. The determined selective occupation can accurately predict the trend of the saturation magnetic moment . The decrease in correlates with the transition of iron cations. Gaining a more extensive understanding of how the selective occupation is directed, and what implications this has on the structural, electronic, and magnetic properties, will lead the way to tailoring HESOs to individual applications
A New Approach to the Construction of Subdivision Algorithms. English Translation of the Dissertation: Ein neuer Ansatz zur Konstruktion von Subdivisionsalgorithmen
No full textIn this thesis, a new approach for constructing subdivision algorithms for generalized quadratic and cubic B-spline subdivision for subdivision surfaces and volumes is presented. First, a catalog of quality criteria for these subdivision algorithms is developed, serving as a guideline for the construction process.
The construction begins by generating the desired subdominant eigenvectors as the vertices of regular convex 2-polytopes for surfaces and convex 3-polytopes for volumes using circle packings. Subsequently, these polytopes are utilized to construct a Colin-de-Verdière-matrix for the generalized quadratic and a Colin-de-Verdière-like matrix for the generalized cubic B-spline subdivision. These matrices are then adjusted using the matrix exponential to obtain subdivision matrices with the desired properties.
All subdivision algorithms introduced in this paper empirically exhibit a subdominant eigenvalue of 1/2 with the desired algebraic and geometric multiplicity. For the quadratic case, this property can even be formally proven. Moreover, the corresponding eigenvectors form a convex polytope in the central region for the generalized quadratic B-spline subdivision algorithms, while for the generalized cubic B-spline subdivision algorithms, they represent the refinement of a convex polytope. Additionally, the constructed subdivision algorithms fulfill various other quality criteria, such as affine invariance and convex hull preservation. Furthermore, they possess a dominant eigenvalue of 1, respect all symmetries of the underlying structure, and exhibit appropriate support for the refinement rules. The scientific contribution of this work lies in the elaboration of the quality criteria and the novel construction of the subdivision algorithms, including corresponding proofs and empirical analyses. Specifically, an alternative to the Catmull-Clark algorithm with a subdominant eigenvalue of 1/2 is presented for generalized cubic B-spline subdivision surfaces. For generalized volumetric B-spline subdivision, subdivision algorithms with a suitable spectrum are introduced, making them promising candidates for applications such as simulations in isogeometric analysis. Furthermore, it is demonstrated that the original Catmull-Clark algorithm [CC78] is not suitable for generalization to volumetric subdivision and that the established subdivision algorithms [Baj+02] and [JM99] do not exhibit a suitable spectrum for several combinatorial configurations. Additionally, research approaches for the volumetric case are proposed, aiming to generalize from hexahedral to arbitrary structures.
The construction of the subdivision matrices was also implemented algorithmically in Matlab. The corresponding software package, including functions for uniform refinement and for plotting subdivision volumes, can be found at: https://doi.org/10.48328/tudatalib-184
Surface‐Engineered Cenospheres Encapsulating Phase Change Materials for Functional Cementitious Composites
No full textThe escalating global energy demand underscores the critical need for advanced solutions for energy‐efficient buildings. Passive thermal energy storage systems using microencapsulated phase change materials (PCMs) offer promise but face integration challenges in cementitious materials due to weakening mechanical strength, which arises from poor shell strength and weak interfacial bonding with cementitious phases. This study introduces a novel approach for synthesizing functionalized microencapsulated PCMs from fly ash‐based cenospheres addressing interfacial compatibility. Cenospheres are perforated for PCM encapsulation and sealed using two different materials: 1) melamine‐formaldehyde (MF), a standard polymeric shell; and 2) silica, selected for its chemical compatibility with cementitious phases. Experimental results show that the silica sealing improved mechanical strength by 50% over those of MF, corroborated by molecular dynamic simulations showing silica's binding energy with calcium silicate hydrate exceeded threefold, with more than twice the uniaxial tensile strength. Thermal analyses confirmed the preservation of PCM in both sealing approaches. This work establishes a transformative pathway for advancing PCM‐based thermal energy storage in building materials
The three limits of the hydrostatic approximation
No full textThe primitive equations are derived from the 3D Navier–Stokes equations by the hydrostatic approximation. Formally, assuming an ε‐thin domain and anisotropic viscosities with vertical viscosity νz=O(εᵞ) where γ=2, one obtains the primitive equations with full viscosity as ε→0. Here, we take two more limit equations into consideration: For γ2 the primitive equations with only horizontal viscosity −ΔH as ε→0. Thus, there are three possible limits of the hydrostatic approximation depending on the assumption on the vertical viscosity. The latter convergence has been proven recently by Li, Titi, and Yuan using energy estimates. Here, we consider more generally νz=ε²δ and show how maximal regularity methods and quadratic inequalities can be an efficient approach to the same end for ε,δ→0. The flexibility of our methods is also illustrated by the convergence for δ→∞ and ε→0 to the 2D Navier–Stokes equations
Integrating regional survey data into life cycle assessment: prospective environmental consequences of directing apple pomace to insect farming
No full textPurpose: Insect cultivation on bio-residues exemplifies the circular bioeconomy (CBE) concept by integrating three core CBE strategies: the use of bio-residues, multi-output production chains, and cascading. The sustainability of CBE technologies using bio-residues needs to be evaluated on a case-by-case basis, taking into account regional aspects and the technologies’ future potential. This study provides methodological guidance for assessing the environmental consequences of diverting a by-product from its current to a future utilization pathway through a prospective and consequential life cycle assessment (LCA) at a regional level.
Methods: We illustrate the developed methods with a case study of black soldier fly larvae (BSFL) rearing on an apple pomace (AP)–based feed in Hesse, Germany. We analyze the regional AP situation regarding availability, seasonality, spatial distribution, and market situation, through an industry survey among Hessian press houses and integrate this information into our LCA model to scale it to the regional level, consider regional transport scenarios, and reflect regional market effects of diverting AP. Furthermore, we systematically upscale the process chain to an early industrial scale.
Results and discussion: The annual generation of 11,300 tFM AP in Hesse could supply a small industrial BSFL plant. AP occurs with high spatial density in the south of Hesse. Press houses are concerned that the cost of AP disposal will increase and that it will be difficult to find a recipient for AP in the future. These aspects support a new and centralized use of AP. However, its high seasonality and unstable nature is a hurdle. Diverting the AP annually generated in Hesse from its current utilization as biogas substrate or ruminant feed to insect farming results in a reduction compared to the status quo in land use by 6.4E + 05 to 6.8E + 05 m²a crop eq and in freshwater eutrophication by 3.7E + 03 to 3.8 E + 03 kg P eq when BSFL replace soybean meal. However, most environmental impacts show an increase, for example, global warming potential increases by 3.6E + 07 to 3.8E + 07 kg CO₂ eq. The LCA results identify improvement options such as reducing the feed conversion rate and optimizing the use of feed additives.
Conclusion: This study shows how the regional situation of an industrial by-product can be investigated through a regional industry survey and how this information can be integrated into a cLCA model using a methodological framework. We show that the market situation of by-products can differ regionally, emphasizing the need of region-specific integration into cLCA models
Amorphous doped indium tin oxide thin‐films by atomic layer deposition : insights into their structural, electronic and device reliability
No full textThin semiconducting films of magnesium doped indium‐ and tin oxide are prepared by thermal atomic layer deposition (ALD). The metal oxide films are deposited at 200 °C from the precursors trimethylindium, tetrakis(dimethylamido)tin, bis(ethylcyclopentadienyl)magnesium and water as oxidant. These thin‐films are observed to be amorphous by electron microscopy and X‐ray diffraction. However, they exhibited a near‐range atomic order with correlation lengths of up to 10 Å, as demonstrated by high energy total scattering at grazing incidence employing synchrotron radiation. Even minor alterations in composition reveal a significant impact on the thin‐film transistor (TFT) device parameters, due to magnesium's high oxygen binding capability and its ability to inhibit the formation of oxygen vacancies, resulting in a decrease of free charge carriers in the material. Stability tests indicate a device degradation after storage in ambient conditions due to water adsorption on the surface, which could be reversed by an additional annealing step which qualify the films as robust. This studie demonstrate the possibility of employing minor amounts of high band gap oxides such as MgO to manipulate and control the electric behavior of the active channel layer performance in inorganic TFT devices
Maximum length binary sequences and spectral power distribution of periodic signals
No full textThe maximum length binary sequence (MLBS) is widely used as a broadband pseudo-random noise excitation signal, for example, for system identification. Although its properties have been known for decades, misleading or inaccurate statements can be found in many references. For example, it is sometimes stated that the spectrum of the MLBS is white, whereas in other references a sinc behavior is stated. In this paper, we therefore analyze the MLBS properties based on precise definitions for the given context (time-discrete vs. time-continuous, periodic vs. non-periodic, etc.), especially with respect to Fourier analysis. Another difficulty arises from the fact that in the literature the mathematical definitions are often simplified by means of normalizations which makes the physical interpretation difficult. Therefore, special emphasis is put on scaling factors which allow such a physical interpretation