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Coastal megaprojects in the blue economy: Towards equity and transformation for the coastal poor – a case study from Bangladesh
No full textThe rapid changing of coastal and marine systems is driven by underlying socio-economic factors, including privatization, industrialization, and conservation initiatives. These dynamics present significant equity and justice challenges for small-scale resource users. This research investigates the social impacts of coastal megaprojects development initiatives. Empirically, the case of Maheshkhali Island in the southeastern region of Bangladesh is examined, where a coal power plant and deep-sea port have recently been implemented within the wider context of blue economy agendas and debates. The thesis addresses the phenomena of displacement, dispossession, and marginalization experienced by coastal communities in the wake of substantial investments by the government and international stakeholders in alignment with national blue economy strategies. The thesis investigates how these developments exacerbate existing inequity, disrupt the livelihoods of those affected, and undermine resource access. In doing so, the thesis addresses wider concerns regarding blue economy governance, justice, and sustainability.
The study employs an interdisciplinary approach within the marine social sciences, combining political ecology, coastal conflict studies, blue justice, and interactive governance frameworks to examine governance responses and identify pathways for equitable blue economy development. Methodologically, the study undertakes literature review on the blue economy and conducts qualitative data collection (interviews, focus group discussions, and participant observation), social network analysis, and discourse analysis. The core of this research is presented in 6 articles. The study’s key findings, in Article 1, reveal discrepancies between global commitments to the blue economy and those in national policies. At the heart of these discrepancies is a lack of social equity and justice for marginalized resource users, identifying a need for scientific approaches to link to national policies to foster inclusive governance. Article 2 develops a conceptual framework for the creation of “safe spaces” with a focus on small-scale fisheries, offering equity-focused blue economy development for the implementation of equitable and sustainable practices that are grounded in international guidelines. Article 3 analyzes blue economy governance networks in Bangladesh, and reveals a concentration of power, the marginalization of local stakeholders, and a narrow focus on fisheries, tourism, and shipping in the blue economy governance perceptions of key national blue economy stakeholders. Article 4 offers empirical evidence of injustices and inequity in Maheshkhali Island and provides a critique of the development narratives along with geopolitics influences in Bangladesh. Article 5 explores the diversities and commonalities of the discourses that the blue economy stakeholders (i.e., local small-scale resource users) engage in and identifies the need for participatory processes to address environmental, health, and livelihood concerns. Article 6 uses “interactive governance” as a systemic framework to seek governance responses to injustice and inequity in blue economy initiatives in principles of justice, encompassing recognition, procedural fairness, and distributive equity, to foster sustainable and inclusive blue economy transformations.
This research contributes to the growing scholarship on coastal and ocean conflicts within megaproject implementation, equity, and governance challenges in blue economy contexts of the Global South, and offers a basis for policymakers for informed policy-making. A policy brief with the most important findings and recommendations is under preparation
Suitability of process chains for generating hydrophilic, wear resistant LIPSS-structured surfaces
No full textDas wachsende Bewusstsein für Umweltfragen führt zu immer größeren Anstrengungen, neue, umweltfreundliche tribologische Systeme für die Blechumformung zu entwickeln. Mit der Identifizierung einer geeigneten Prozesskette zur Erzeugung hydrophiler, verschleißbeständiger LIPSS-strukturierter Oberflächen für den Kontakt gegen Stahl wurde im Rahmen dieser Arbeit das übergeordnete Ziel verfolgt, deionisiertes Wasser als Alternative zu konventionellen Schmierstoffen in der Umformung möglich erscheinen zu lassen. Die Ergebnisse dieser Arbeit aus Sessile-Drop-Tests, Stift-Platte-Tests und Streifenziehversuchen ohne Umlenkung belegen zwar das hohe Potential von Strukturbeschichtungsvarianten aus LIPSS und Titannitrid, nach derzeitigem Kenntnisstand reicht jedoch dies nicht aus, um deionisiertes Wasser in der Blechumformung, beispielsweise beim Tiefziehen, als Alternative zu konventionellem Schmierstoff möglich erscheinen zu lassen
An integrated software platform to analyze the role of human mobility in vector-borne disease transmission
No full textHuman mobility plays a crucial part in the transmission of vector-borne diseases. The relationship between human mobility and disease transmission is a complex phenomenon since it involves the dynamics of human movement, disease transmission, and the interactions between humans and their environment. Several tools to support such complex analyses exist; however, they focus on one or a few aspects of mobility analysis and visualization, leading to tedious and potentially error-prone work when utilizing them across multiple platforms. To address this challenge, this study aimed to 1) develop the Mobility Analysis for Vector-borne Disease platform (MoVe), which integrates visualization, spatial analysis, and agent-based simulation functions, and 2) demonstrate the effectiveness of MoVe.
The MoVe platform consists of spatial analysis and agent-based simulation components. The spatial analysis component extracts essential information with regard to human mobility. The agent-based simulation function is designed to explore the effects of mobility patterns on the transmission of vector-borne diseases. It features a novel individual-level probabilistic risk estimation, which is easily interpretable, and also facilitates the examination of the effects of disease control strategies through what-if scenario analyses.
To demonstrate MoVe’s effectiveness, observational case studies are presented investigating the role of human mobility in malaria transmission in Tha Song Yang District, Tak Province, Thailand, where cross-border importation plays an important role. The participants in the observational case studies were randomly selected from the local population. MoVe was used to analyze the mobility data collected via a smartphone application installed on the participants' smartphones over a one-year period.
Findings from the case studies indicated that demographics and seasonal factors were crucial in determining patterns of cross-border mobility. During the dry season (August-December), it was common for farmers, laborers, and unemployed participants to cross the Thai-Myanmar border. However, only farmers crossed the border in the wet (May-July) season. This demonstrates the ability of MoVe to detect variations in mobility patterns.
Utilizing the extracted mobility patterns from the spatial analysis function, the simulation in MoVe investigated the role of cross-border mobility in malaria transmission in Thailand. It revealed that cross-border mobility among Thais, primarily farmers, significantly contributes to malaria infections in Thailand during the wet season. However, during the dry season, malaria infections in Thailand are largely driven by the cross-border mobility of infected short-term migrants from Myanmar. These findings indicate that the primary challenge hindering malaria elimination in Thailand, particularly at the Thai-Myanmar border, is the cross-border mobility of different populations
On the concepts of quality for local solutions of nonlinear programs
No full textThis thesis covers the topic of assessing the quality of local solutions in both standard and parametric nonlinear programming.
From a theoretical perspective, a formal definition of a quality criterion for local solutions of nonlinear programs is introduced, and the notions of primary and secondary quality criteria are distinguished. Since the primary criterion is inherently associated with the optimality of local solutions, the main focus is on secondary criteria. In particular, over 25 existing secondary quality criteria are systematically reviewed and analyzed. These criteria, arising in both non-parametric and parametric nonlinear programming, are derived from the fields of dynamical systems, robust optimization, stochastic optimization, and parametric sensitivity analysis.
From an applied perspective, two novel secondary quality criteria are proposed: the maximum radius of attraction (MRoA) and the parametric stability score (PSS). MRoA is a measure of quality for local solutions of non-parametric nonlinear programs. It is defined as the radius of the largest ball centered at a local solution such that a given optimization algorithm, once initialized inside that ball, is guaranteed never to escape it and is expected to converge to the same solution. PSS, in turn, quantifies the quality of local solutions of parametric nonlinear programs. It is defined as the maximum magnitude of a perturbation of the nominal parameter, such that for any smaller perturbation, the solutions and corresponding optimal costs of the nominal and perturbed problems remain within prescribed distances. The utility of the PSS concept is demonstrated using an optimal control problem for accomplishing the swing-up maneuver of the pendulum on a cart system.
For both proposed criteria, connections to the field of online optimization are established, emphasizing their potential to support informed decision-making
Control of robots with hybrid locomotion capabilities
No full textHybrid locomotion robots—systems combining multiple modes of motion—are well-suited for challenging terrain and have broad practical applications. However, developing effective control strategies remains challenging due to nonlinear dynamics, multimodal locomotion, computational constraints, and multiple objectives. Existing solutions are often not portable to unconventional morphologies, requiring substantial redesign. This thesis proposes multiple control solutions for three morphologically distinct robots: Asguard, SherpaTT, and ARTER.
Asguard’s five-spike wheel design presents challenges in forward motion and point turning. A cascaded position–velocity–torque controller improves wheel positioning accuracy by up to 56 % while maintaining defined offsets. The controller based on a novel torque estimator using mechanical coupling deflection enables real-time torque control. Adjusting inter-wheel offsets reduces resistance to motion by up to 90 %. For point turns on rough terrain, an algorithm that utilizes external load torques enables reliable rotation, outperforming baseline controllers.
Dedicated control frameworks, denoted as Motion Control System (MCS), are developed for the wheel-legged robots SherpaTT and ARTER. SherpaTT-MCS supports teleoperation, assistance functions, and autonomy. Its terrain adaptation module improves force distribution by 80 % and reduces attitude error by up to 95 % in laboratory tests. It has been successfully deployed in over ten research projects and has proven its efficacy in three Mars-analogous field trials. ARTER-MCS incorporates kinematic modeling of parallel linkages and nonlinear model predictive control, and is currently in active use in multiple projects.
For ARTER, a Deep Reinforcement Learning (DRL)-based terrain adaptation controller is introduced, leveraging compressed height-maps via autoencoders. Ten variants of the controller were trained using different combinations of observations, including contact distances and latent-space representations. The controller that demonstrated the strongest performance utilized contact-detection and a 4-dimensional terrain latent space as observation, offering a favorable combination of both performance and complexity. All controllers achieved baseline objectives and has the potential to be ported to other platforms with active suspension.
ARTER also demonstrates stepping locomotion via a controller that combines the movement of the manipulator arm, the legs and the wheels. This controller applies hierarchical reinforcement learning and action masking, integrating domain knowledge to simplify training. A three-level hierarchy is employed: the lowest level manages diverse simpler motions (manipulator, longitudinal motion, end-effector height adjustments, etc.); the middle level sequences these for stepping in and out of obstacles; the top level manages task transitions. The architecture generalizes across three different types of stepping terrain and generated motion comparable to that of an expert operator.
In summary, this thesis presents a series of control solutions designed to enhance the locomotion performance, efficiency, and adaptability of hybrid robotic platforms. The learning-based methods offer strong morphological generalization and address long-sequence tasks with reduced engineering effort. These contributions represent quantitative and qualitative advancements in the control of diverse robots with hybrid locomotion capabilities
Erzeugung von Carrier-Strukturen mittels Laserbearbeitung auf Titanlegierungen
No full textThe global market for dental and orthopedic implants has grown in recent years due to the ageing of the population. Reports indicate that the number of implant-related surgeries is increasing significantly from year to year. Despite the rapid technological advancement, some dental and orthopedic surgeries are unsuccessful due to implant-related problems such as inflammation or lack of osseointegration. Therefore, further improvements need to be made to the implants to combat these specific problems in order to significantly reduce the number of unsuccessful implant surgeries.
In the present work, laser surface texturing of Ti6Al4V was performed using a femtosecond laser system at high repetition rates to create unique micro-structures on its surface. The influence of laser pulse overlap and laser repetition rates play a major role on structure formation. Laser texturing with a high degree of overlap resulted in melting of the material, leading to the formation of specific micro-structures that can be used as cavities for drug delivery. The reason for melt formation on the surface of Ti alloy is attributed to local heat accumulation at high repetition rates. It was also demonstrated that such structures can be fabricated on materials with low thermal conductivity, which prevent heat dissipation into the bulk of the material.
Laser textured micro-structures serve as a drug- delivery cavities which are to be filled with drugs before the implantation. After the implantation is performed, drugs loaded in the cavities released to prevent bacterial adhesion and biofilm formation on the surface of the implant. In addition, laser texturing also can enhance the wettability of implants and matrix mineralization (bone formation), which was previously observed on laser textured surfaces.
Laser textured titanium alloys have demonstrated to have smaller heat-affected zone (HAZ) compared to nano- or picosecond lasers, which does not affect the mechanical properties of implant. To investigate the change in mechanical properties due to laser texturing, fatigue tests were performed on textured titanium samples with two specific types of micro-structures to be used for drug delivery. Some of the samples were heat treated prior fatigue tests in order to eliminate the residual stresses induced by laser texturing. Fatigue tests revealed that micro-structures have deteriorative effect on mechanical properties of textured samples. Nevertheless, one type of micro-structures is better in terms of mechanical stability.
In addition, laser textured samples were tested on wettability. The results shown that structures are hydrophilic after the fabrication, and with time they become hydrophobic. The reason behind it is found to be chemical alteration of textured sample surfaces.
In general, above stated features suggest that surface texturing of Ti alloys using femtosecond laser direct writing is a promising method for fabrication of functional surfaces which can combat bacterial adhesion and biofilm formation after implantation
Understanding human activities from videos: enabling robotic agents for semantic manipulation and task execution
No full textThis dissertation presents an end-to-end framework that enables robotic agents to acquire manipulation competence from human demonstration videos by unifying semantic abstraction, 3D spatial reasoning, and physics-informed validation within a single coherent pipeline. From raw monocular video, the system extracts temporally aligned evidence of human–object interaction, including contact cues, grasp configurations, spatial relations, and motion evolution across canonical manipulation phases (approach, grasp, move, release). These observations are organized into an Event Designator that decomposes activity into three complementary representations—Action, Motion, and Scene Designators—capturing what is being done, how it unfolds over time, and where it occurs with respect to the geometric and semantic structure of the environment. Through multimodal integration of vision, language, and geometry, the framework grounds task-level reasoning in measurable physical evidence, producing interpretable and reusable task knowledge rather than isolated labels or free-form descriptions.
To ensure physical reliability and transferability, the learned designators are validated and refined within a physics-enabled digital twin that explicitly models contact dynamics, stability, friction, and constraint satisfaction. This perception–simulation loop supports systematic error analysis and iterative refinement, converting semantically grounded representations into execution-ready parameters such as grasp strategies, motion constraints, and tool–object interaction profiles. The dissertation contributes (i) a fine-grained manipulation phase analysis pipeline for extracting atomic interaction structure from video, (ii) the Task–Event Designator architecture for hierarchical, causally coherent task representation, (iii) an enhanced SMPL-X–based module for expressive motion capture and contact-aware human–scene reasoning coupled with 3D scene reconstruction, and (iv) a translation mechanism enabling cross-embodiment execution via a general-purpose FK–IK controller, demonstrated on real robotic platforms. Collectively, this work advances video-based robot learning from imitation toward context-aware understanding and physically grounded execution, improving interpretability, generalization, and robustness across diverse tasks and environments
Health Literacy in the context of socioeconomic disadvantage: determinants, intervention strategies, needs, and measurement among long-term unemployed people
No full textSignificant health literacy deficits in Germany and across Europe led to the publication of the National Action Plan for Health Literacy in 2018, providing a framework for targeted interventions. Subsequently, the literature revealed initial efforts to promote health literacy among specific population groups. Despite these efforts, systematic approaches—particularly for socioeconomically disadvantaged groups—remain scarce. This dissertation aims to bridge these gaps by (a) identifying modifiable predictors of health literacy, (b) analyzing effective intervention strategies to promote health literacy among populations experiencing socioeconomic disadvantage, (c) exploring the specific health literacy needs of long-term unemployed individuals, and (d) assessing the suitability of standard health literacy measurement tools for socioeconomically disadvantaged populations, using long-term unemployed individuals as a case example. Long-term unemployed individuals were chosen as a focal group because they fulfill multiple risk factors for low health literacy, such as socioeconomic disadvantage and a high prevalence of chronic mental and physical illnesses, making them particularly vulnerable.
To address these objectives, the study employed a variety of methodological approaches: (a) a rapid review, (b) a systematic review, (c) a triangulation of qualitative data with a scoping review, and (d) an explorative qualitative think-aloud study.
Key findings highlighted language proficiency, frequency of internet use, and use of online and television-based resources for obtaining health-related information as the most significant modifiable predictors of health literacy. Successful intervention strategies identified in the literature often assessed group-specific needs prior to implementation, utilized multilingual intervention materials, and involved bilingual facilitators. Among unemployed populations, the primary health literacy needs identified pertained to mental health. Furthermore, these individuals faced primarily difficulties in applying health information to their daily lives. Participants in long-term unemployment demonstrated significant difficulties in comprehending standard health literacy assessment questions, such as those in the HLS-EU-Q16 questionnaire. These challenges were primarily attributed to the level of abstraction required by the questionnaire, which was often too demanding for respondents.
Culturally sensitive, tailored interventions that provide multilingual informational materials emerged as promising approaches to promote health literacy. Long-term unemployed individuals could benefit from interventions designed to facilitate the practical application of health information in everyday life. Additionally, the comprehensibility of standard health literacy measurement tools could be improved by incorporating context-specific explanations and audiovisual elements
Many-body effects and quantum-optical mode coupling in semiconductor lasers
No full textSemiconductor lasers are invaluable tools for technological progress. They are indispensable for applications in optical communications, integrated photonic circuits, entanglement generation, quantum computing and sensing. This work develops a comprehensive quantum-optical semiconductor laser theory based on an equation of motion approach, capturing a broad spectrum of laser phenomena. A key focus is the linewidth behavior of singlemode quantum-well lasers. Deviations from the Schawlow-Townes behavior, particularly in micro- and nanolasers, are investigated. Many-body effects, including Coulomb interactions and electron-phonon coupling, significantly influence laser characteristics and alter the gain spectrum. Furthermore, the work extends the laser theory to multimode operation, identifying critical mode coupling mechanisms and introducing the concept of a “coherent phase” as a criterion for distinguishing between quantum and classical regimes. It is discussed that spontaneous emission disrupts phase coherence, while conventional lasers maintain it above the threshold. The research also explores the role of electron scattering in multimode lasing, demonstrating its major impact on laser characteristics. Additionally, the developed multimode laser theory is used to investigate mode locking in single-section quantum-dot lasers. Established theories for mode locking are based on a classical description of the light field, whereas here a quantum-optical theory is developed. Quantum fluctuations and relaxation dynamics are shown to play a crucial role for pulse generation. An analytical lower limit for the width of the beat-note spectrum is derived, with future work suggested to explore intensity-dependent effects on mode locking stability. These findings contribute to the theoretical foundation necessary for advancements in on-chip quantum computing, quantum communication, and integrated photonics
Online-Überwachung von Fischer-Tropsch-Flüssigkraftstoffprodukten über Massenspektrometrie mit chemischer Ionisation bei Atmosphärendruck
No full textDer Prozess der Fischer-Tropsch-Synthese (FTS) wandelt Synthesegas in
Kohlenwasserstoffe um und ermöglicht, in Verbindung mit erneuerbaren
Energien und nachhaltigen Kohlenstoffquellen, die Herstellung flüssiger
Kraftstoffe und Chemikalien ohne den Einsatz fossiler Rohstoffe. Fluktuationen
in der Produktion erneuerbarer Energien erfordern unter Umständen
einen dynamischen FTS-Betrieb, was sowohl die Prozesssicherheit als auch
die Qualitätskontrolle vor Herausforderungen stellt, gleichzeitig aber auch
Chancen für eine Prozessintensivierung bietet.
In instationären FTS-Betriebsszenarien ist eine schnelle und umfassende
Online-Analyse der Produkte entscheidend, um dynamische Reaktions- und
Transportprozesse zu verstehen und die Prozesseffizienz kontinuierlich zu
bewerten. Dies gestaltet sich jedoch als schwierig, da die konventionelle Produktanalyse
mittels Gaschromatographie (GC) eine zeitintensive Trennung
der einzelnen Produktkomponenten zur Quantifizierung erfordert.
In dieser Arbeit wird eine alternative Methode zur Produktanalyse entwickelt,
die auf der Massenspektrometrie mit chemischer Ionisation bei Atmosphärendruck
(APCI-MS) basiert. Mit diesem Ansatz wird eine Überwachung von
FTS-Produkten im Flüssigkraftstoffbereich (C5–C20) im heißen, gasförmigen
Produktstrom in Abständen von fünf Minuten ermöglicht. Ein GC-Instrument
wird als zuverlässige Referenz verwendet.
Im ersten experimentellen Teil werden eindeutig definierte Kohlenwasserstoffstandards
analysiert, um APCI-Massenspektren detailliert auszuwerten
und die Messmethode schrittweise zu etablieren. Dabei besteht die zentrale
Herausforderung darin, geeignete MS-Ionisierungsbedingungen und Ionenarten
mit minimaler Fragmentierung zu identifizieren, um sicherzustellen,
dass Kohlenwasserstoffe unterschiedlicher Kettenlänge keine überlappenden
Signale erzeugen. Die Untersuchung verschiedener Alkanstandards führt
zur Identifikation sauerstoffhaltiger [M–H+O]+-Ionen als vielversprechende
Kandidaten für diese Anwendung. Eine „Proof-of-Principle“-Studie zeigt
eine lineare Beziehung zwischen den Signalintensitäten und den Alkankonzentrationen,
selbst in Mischungen und unter variierenden Injektionsraten.
Eine fortschreitende Ablagerung von Kohlenwasserstoffen in der Ionenquelle
reduziert jedoch die Genauigkeit der zeitlichen Analyse, insbesondere bei
schwereren Verbindungen.
Eine mechanistische Studie unter Verwendung von 18O-markiertem Wasser
und wechseldem trockenen/befeuchteten MS-Trägergas untersucht die Rolle
von Wasser in der Ionenquelle. Zwei verschiedene Effekte werden beobachtet.
Einerseits wird vermutet, dass die für die Analyten charakteristischen
[M–H+O]+-Ionen durch sekundäre Oberflächenreaktionen mit adsorbiertem
Wasser entstehen. Andererseits remobilisiert einströmendes gasförmiges
Wasser zuvor abgelagerte Kohlenwasserstoffe, was zu denselben Ionentypen
führt und unerwünschte Signalüberschneidungen zur Folge hat. Da Wasser
bei der FTS ein vielproduziertes Nebenprodukt ist, wird der Stabilisierung
des Wassergehalts in der Ionenquelle eine entscheidende Bedeutung beigemessen,
was durch eine kontinuierliche Befeuchtung des MS-Trägergases
gewährleistet wird.
Intensivere Ionisierungsbedingungen werden angewendet, um die Ablagerung
von Kohlenwasserstoffen in der Ionenquelle zu minimieren. Dies führt
jedoch zu einer stärkeren Fragmentierung. Zudem werden bei der Verwendung
von [M–H+O]+-Ionen signifikante Signalüberschneidungen zwischen
n-Alkanen und 1-Alkenen festgestellt. Aus diesem Grund werden dreifach
sauerstoffhaltige [M–H+3O]+-Ionen als neue Zielionen definiert, die zwar
in geringeren Intensitäten auftreten, jedoch eindeutige Signale sowohl für
n-Alkane als auch für 1-Alkene liefern.
Die Anwendung der entwickelten APCI-MS-Methode auf die FTS im zweiten
Versuchsabschnitt bestätigt die Eignung von [M–H+3O]+-Ionen zur Überwachung
von C5–C20 n-Alkanen und 1-Alkenen während des Prozesses. In einer
dynamischen Fallstudie, bei der sich die Reaktantflussrate alle fünf Minuten
ändert, zeigt sich der Vorteil der schnellen Probenahme mit der MS-Methode
im Vergleich zur herkömmlichen, 40-minütigen GC-Analyse für die effiziente
Überwachung von Flüssigkraftstoffprodukten während eines instationären
FTS-Betriebs.
Die aktuellen Einschränkungen und Unsicherheiten der Methode werden
systematisch ermittelt und bewertet, was zu konkreten Empfehlungen für
zukünftige Forschungsarbeiten führt. Auf der Grundlage dieser Thesis kann
der entwickelte analytische Ansatz langfristig dazu beitragen, das Verständnis
transienter FTS-Phänomene zu erweitern und die Entwicklung optimierter
Designs sowie Strategien für lastflexible FTS-Anlagen zu fördern