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Simulation von künstlichen Muskeln im Vergleich zu natürlichen Muskeln
No full textPersonen, die Gliedmaßen verloren haben oder eine Amputation erlebt haben, sind auf moderne Prothesen angewiesen, um ihren täglichen Aktivitäten nachzugehen. In den letzen 30 Jahren hat sich der Bereich der künstlichen Muskeln von der Idee, biologische Muskeln nachzuahmen, entwickelt. Künstliche Muskeln werden derzeit für den Einsatz in der Industrie, der Robotik und für medizinische Anwendungen erforscht. Es bleibt jedoch die Frage, ob künstliche Muskeln eingesetzt in Prothesen, biologischen Skelettmuskel ersetzen können und ein ähnliches Verhalten und eine ähnliche Reaktion wie dieser erzielen können. Um diese Frage zu beantworten, wurde eine umfassende Literaturrecherche zu verschiedenen Arten künstlicher Muskeln durchgeführt. Diese Recherche umfasst die Stärken und Schwächen der verschiedenen Arten künstlicher Muskeln. Nach der Literaturrecherche wurden ein mathematisches Python-Modell eines biologischen Skelettmuskels und ein Modell eines künstlichen Muskels entworfen. Als künstlicher Muskel wurde ein auf Licht reagierender Hydrogel-Aktuator konstruiert. Ein auf Licht reagierendes Hydrogel kann durch Bestrahlung mit UV-Licht zur Aufnahme von Wasser durch Diffusion geführt werden, und schwillt daraufhin an. Die Python-Modelle der beiden Muskeln dienen zur Berechnung des dynamischen Kontraktionsverhaltens unter verschiedenen Belastungskräften. Ein Vergleich des Kontraktionsverhaltens zeigte, dass biologische Muskeln trotz größerer Belastung, schneller kontrahieren und größere Dehnungen erzeugen. Die langsame Kontraktion des Hydrogel-Aktuators ist bedingt durch die langsame Diffusion des Wassers während des Anschwellens. Es wurde gezeigt, dass eine Halbierung der Diffusionslänge zu einer Verdoppelung der Dehnung des Aktuators führen kann. Um die Leistung von Hydrogel-Aktuatoren zu verbessern, müssen Maßnahmen ergriffen werden, um geringe Diffusionslängen zu gewährleisten.Individuals who have experienced limb loss or amputation depend on modern prosthetics to facilitate their daily activities. Over the last 30 years, the field of artificial muscles has evolved from the idea of mimicking biological muscle. Artificial muscles are being researched for use in industry, robotics, and medical applications. However, the question remains as to wether artificial muscles can also be used in prosthetics to substitute for biological skeletal muscle and provide similar behavior and response. To answer this question a comprehensive literature review of different artificial muscle types has been conducted. This review covers the strength and weaknesses of each type of artificial muscle. A mathematical Python model of a biological skeletal muscles and an artificial muscles model were designed following the literature review. The artificial muscle was constructed using a light-responsive hydrogel actuator. A light-responsive hydrogel has the capacity to be triggered by a light stimulus, resulting in the absorption of water through diffusion and subsequent swelling in size. The Python models are designed to calculate the dynamic contraction behavior of the muscles under different load forces. A comparison of the contraction behavior demonstrated that biological muscles contract faster with greater load and higher strains. The slow contraction of the hydrogel actuator is caused by the slow diffusion of water during the swelling process. It has been demonstrated that reducing the diffusion distance by half results in a twofold increase of the actuators strain. In order to enhance the performance of hydrogel actuators, measures must be taken to ensure low diffusion distances
Untersuchung von Kernanregungen induziert durch inelastische Elektron Streuung
No full textDie Diplomarbeit untersucht die Möglichkeit inwieweit Kernanregungen induziert durch inelastische Elektronstreuung (NEIES) für technologische Anwendungen genutzt werden können. Das Ziel ist die selektive Anregung von Kernzuständen und damit die Änderung der Kerneigenschaften wie Lebensdauer und Zerfallspfad. Die Diplomarbeit umfasst eine quantitative Studie in welcher Anregungswirkungsquerschnitte und daraus folgende Übergangsraten für eine Auswahl von Kernen berechnet werden. Insbesondere wird die Abhängigkeit der Anregungswirkungsquerschnitte von der Ordnungszahl Z, der Anregungsenergie E_x und der Multipol-Ordnung Eλ and Mλ untersucht. Die theoretische Basis für diese Rechnungen verwendet eine realistische Elektron-Kern Wechselwirkung, welche auf dem Austausch virtueller Photonen beruht, und benützt eine Multipol-Entwicklung der Übergangsoperatoren. Mit den entsprechenden Beziehungen wurde ein numerisches Programm entwickelt, welches die Anregungswirkungsquerschnitte als Funktion der Energie des Elektronstrahls für verschiedene Kerne und Anregungszurände berechnet. Weiters wurden für die berechneten Wirkungsquerschnitte Übergangsraten für realistische Parameter des Elektronenstrahls bestimmt, um das Anwendungspotential und die Durchführbarkeit von NEIES abschätzen zu können.This master thesis investigates the extent to which nuclear excitations induced by inelastic electron scattering (NEIES) can be used for technological applications. The aim is to selectively excite nuclear states thus influencing nuclear properties such as lifetimes or decay pathways. The work provides a quantitative study in which initial estimates of inelastic excitation cross sections and the resulting transition rates are performed for a selection of nuclei. For this purpose, cross sections are calculated for various atomic numbers Z, excitation energies E_x and multipole orders Eλ and Mλ. The theoretical basis of the work makes use of the electromagnetic electron-nucleus interaction, the description of the scattering process via virtual photons and a multipole expansion of the relevant transition operators. Based on this, a numerical code was developed that implements the formulas and determines the cross sections as a function of the electron energy. From the calculated cross sections, typical transition rates are then derived using realistic beam parameters to evaluate the experimental potential and the feasibility of NEIES based excitation schemes
Demokratische Stadtentwicklung zwischen Aufbruch und Krise : Soziale Schieflagen und neue Wege der Mitbestimmung
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Casimir effect and gravitational balance: A search for stable configurations
No full textIn this study, we examine the role of the repulsive Casimir force in counteracting the gravitational contraction of a thin, spherically symmetric shell. Our primary focus is to explore the possibility of achieving a stable, balanced configuration within the theoretically reliable weak-field limit. To this end, we consider various types of Casimir forces, including those generated by massless scalar fields, massive scalar fields, electromagnetic fields, and temperature-dependent fields
A quasi-2D multiphase flow proton exchange membrane fuel cell model for efficient distributed cell state prediction
Get PDFTo enhance the durability and performance of proton exchange membrane fuel cells, it is essential to capture both spatial and temporal variations of internal states during dynamic operation. While existing reduced-order models (0D/1D) lack spatial resolution, 3D models are often too computationally expensive for transient simulations. To bridge this gap, we present a quasi-2D, time-dependent multiphase model capable of predicting distributed cell states with high computational efficiency. The model accounts for key transport phenomena, including convection, multicomponent diffusion, capillary effects, and membrane water dynamics via electro-osmotic drag and diffusion. It also includes nitrogen crossover, finite-rate sorption/desorption at membrane interfaces, and heat generation from electrochemical reactions, proton conduction, and phase change. A linearisation scheme combined with Chebyshev collocation ensures low computational cost and near real-time capability. Validation against high-resolution 3D computational fluid dynamics simulations confirms the model's accuracy in predicting polarisation curves, gas species distributions, liquid water accumulation, and temperature profiles. Dynamic simulations under load transients further demonstrate its ability to capture key physical processes, underpinning the importance of spatially resolved water transport. By enabling fast and accurate simulations of both steady-state and dynamic fuel cell behaviour, the proposed model supports extensive parametric studies, control system development, and predictive diagnostics. Its computational efficiency makes it a valuable tool for improving fuel cell efficiency, longevity, and system-level control strategies
Architectural Approaches for the Integration of Safety and Security in I4.0
Get PDFThe field of industrial automation is rapidly evolving, with Industry 4.0 (I4.0) introducing increasing levels of connectivity, complexity, and cyber-physical integration. A new challenge faced by modern factories is ensuring both safety and security in a landscape wherean Operational Technology (OT) and Information Technology (IT) converge and intertwine, potentially exposing critical systems to new security vulnerabilities and safety risks. Traditionally, safety is a well-developed domain, while security is an emerging one in industrial sectors and is often treated as an afterthought, leading to weak security posture or security issues whose fixes are costly during system operation.That is why safety and security have to be systematically integrated throughout the entire system lifecycle, especially the earlier phases, encompassing requirements definition, system design, implementation, and operational phases. Standardization and regulation play a pivotal role in ensuring both safety and security. Critical infrastructures are required to comply with numerous safety and security standards, and this compliance landscape is becoming increasingly complex with the introduction of new security-focused regulations such as the Cyber Resilience Act and the EU AI Act. These compliance activities are to a large extent manual and therefore time-consuming, and they are further complicated by the existing knowledge gap among safety and security specialists. Consequently, there is a growing demand for automated, computer-assisted safety and security verification and validation. Achieving such automation, however, requires rigorous modelling and is particularly challenging given the inherently textual and often ambiguous nature of standards.This thesis addresses the discussed challenges of integrating safety and security into I4.0 automation system architectures during design phase, with an emphasis on compliance with relevant security standards while considering safety. We present a formal methodology for modeling system architecture, along with safety and security requirements from different standards and their interrelations. The modelling approach relies on ontology and knowledge graph technologies, which enable the consolidation of all safety- and security-related information within a unified knowledge base. This integration facilitates advanced reasoning capabilities and the extraction of new insights from the modelled information enabling safety and security verification and validation during design phase.To have a standardized and reusable framework for modeling system architecture, the modelling itself is done based on IEC 42010 which is an international standard for architecture descriptions of systems and software.Additionally, we leverage emerging technologies, specifically Large Language Models (LLMs), to further enhance the effectiveness and usability of our methodology. The goal is to reduce the complexity of modelling technologies and make the approach usable by a broader range of users, including those who may not be safety or security specialists. Furthermore, the concept of digital twins and the underlying potentials are considered and explored. Specifically the Asset Administration Shell model is explored as a new standardized digital representation of assets providing all relevant information and functions in a standardized, machine-readable format, facilitating data exchange and communication between different systems and companies throughout an asset's lifecycle.Our results through use case studies and prototyping demonstrate that embedding safety and security by design into system design leads to measurable improvements in safety and security, compared to prior siloed approaches. This integrative approach promotes coordinated stakeholder collaboration during the design phase, helping to prevent safety and security issues that would be more costly and difficult to address in later development stages.The insights gained extend beyond the immediate industrial setting, offering a blueprint for secure digitalization in other cyber-physical domains. Broadly, this work contributes to a safer and more secure industrial future, where digital innovation is balanced by rigorous protective measures—thus accelerating the trustworthy adoption of I4.0 practices across diverse sectors
