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A new design method to account for interlaminar stresses in laminated composites using machine learning
No full textLightweight design is critical for improving the efficiency and sustainability of engineering applications. Laminated composites, with their high strength-to-weight ratio and tailored material properties, play a key role but introduce interlaminar stresses, particularly near free edges where delamination failures often occur. Addressing these stresses typically requires computationally expensive 3D finite element simulations, limiting their use in early design stages. This study presents a machine learning approach using Gaussian process regression and artificial neural networks to efficiently predict interlaminar stresses based on in-plane stress data from shell FE simulations. Achieving high predictive accuracy, this method enables cost-effective, early-stage composite design optimization under complex loading scenarios
Enhancing privacy through unlinkable data sharing with user-in-the-loop access control
No full textIn our information-driven society, the volume of data generated by individuals has grown significantly. Protecting the privacy of individuals is becoming more challenging, as this data can reveal detailed insights into personal preferences and behavior. To address this challenge, we introduce a user-centric, privacy-preserving data-sharing solution that leverages a central data storage service, hereafter referred to as the data intermediary. By integrating local differential privacy with user-in-the-Ioop access control, our system enables data providers to securely and unlinkably store their data at the intermediary. Data consumers can localize and request data via the intermediary. The data providers are included in access decisions without disclosing their identity nor by enabling the linking of their data. We evaluated our approach using theoretical analysis and simulations. Our findings indicate that our system achieves c-privacy and safeguards data providers against external and internal attackers, malicious data consumers, and an honest-but-curious intermediary. Moreover, our method reduces the message overhead for data discovery in our system by more than half compared to existing approaches
Sonderprüfstände in Forschung und Produktentwicklung
No full textExperimentelle Untersuchungen sind in Forschung und Entwicklung unabdingbar. Besonders bei der Analyse von Hochleistungswerkstoffen sowie dem Testen von Leichtbaustrukturen unter vielfältigen Randbedingungen werden hohe Anforderungen an die benötigten Prüfstände gestellt. In diesem Kapitel werden am PKT entwickelte Sonderprüfstände und Prüfstanderweiterungen sowie deren Anwendung vorgestellt
Normen anwenden, Kompetenz entwickeln: Aufmaßarbeit als Lerngegenstand in der beruflichen Bildung des Maler- und Lackiererhandwerks
No full textEin Aufmaß zu nehmen ist eine zentrale Handlung im Maler- und Lackiererhandwerk: Es verbindet technisches Messen, rechtliche Vorgaben und wirtschaftliche Verantwortung. Hier wird untersucht, wie das bauberufliche Aufmaß nach VOB – in der Praxis oft als technische Nebentätigkeit unterschätzt – als berufsbezogene Kerntätigkeit im Maler- und Lackiererhandwerk didaktisch fundiert, praxisnah und regelkonform in Ausbildung und Unterricht verankert werden kann.Taking measurements is a core activity in the painter and varnisher trade, integrating technical measurement, legal requirements, and economic responsibility. This article examines how building trade measurement in accordance with the VOB – often underestimated in practice as a technical side task – can be embedded as a core occupational practice in the painter and varnisher trade in a didactically grounded, practice-oriented and regulation-compliant manner within vocational education and training
Beyond dividing wall columns: Improved process intensification through liquid-only transfer and heat integration
No full textMany chemical companies aim to achieve climate neutrality by 2050, requiring raw material changes and significant reductions in process energy. Since distillation accounts for a large share of energy use, it is a key target for process improvements. One promising approach is thermal coupling between columns, which is already industrially implemented, especially in dividing wall columns. However, such configurations often suffer from limited operational flexibility due to the fixed vapor split between parallel sections, which is largely fixed during design and difficult to adjust during operation. This limitation can be overcome by replacing each bidirectional vapor-and-liquid connection with a liquid-only transfer side stream. This concept allows each column to operate at an individual pressure and enables new options for heat integration. The present study introduces a structured approach for assessing and optimizing such systems with one or two liquid-only transfer side streams, particularly when combined with direct heat integration. Promising configurations are first identified through an efficient shortcut screening and can further be optimized using superstructure optimization. A case study on separating benzene, toluene, and para-xylene demonstrates that liquid-only transfer configurations with direct heat integration can significantly reduce energy and costs, and in many cases outperform conventional thermally coupled systems
First-in-human application of dynamic fluoroscopic analysis to quantify intersegmental motion in mandibular free flap reconstruction
No full textOsseous non-union following free flap reconstruction of segmental mandibular defects can prolong patients’ dental rehabilitation. Various plating systems have been developed to optimize biomechanical fixation, but healing may be retarded. Quantifying intersegmental micromovements could help monitor healing but remains challenging. This study investigates a novel method to visualize segmental movements during healing using a fluoroscopy-based approach. To track segment movements, tantalum beads were implanted intraoperatively in the osseous flap and native mandibular segments. Additionally, single-plane fluoroscopic imaging was performed to assess bead position at maximum mouth opening and intercuspation. Bead positions were merged as three-dimensional objects. Intersegmental movements were quantified using model-based roentgen stereophotogrammetry (mbRSA). Exemplarily, preliminary images were collected from one patient. Fluoroscopic imaging with mbRSA effectively displayed movements and allowed quantification. Translation and rotation were assessed between the native mandible and the flap during maximum mouth opening and intercuspation. For the first time, our analyses demonstrate the feasibility of quantifying segment mobility during healing. This first in men study illustrates the feasibility of the method to monitor intersegmental movements in cases of maxillofacial reconstructions. Further research involving larger patient cohorts is necessary to identify relevant thresholds and differentiate from those that result in lack of healing
Autonomous and AI-enabled systems: extensions or replacements of human will and control?
No full textUse of autonomous, AI-enabled, or opaque systems raises many concerns, and some argue that for these to be permissibly deployed in high-stakes or critical domains, they must be subject to so-called “meaningful human control” (MHC). In this article, I focus on the military domain and rebut a strong version of this critique, arguing that off-the-loop systems – i.e., those which can select and engage targets without contemporaneous human input or oversight – can be permissibly deployed while retaining clear lines of responsibility and control. I show that ex ante operational constraints and targeting parameters can provide combatants and would-be deployers of off-the-loop systems with strong means to ensure that deployed systems are serving as extensions of combatants’ wills, establishing the necessary degree of moral and legal responsibility required. I further show that such constraints and parameters represent clear lines of control that deployers have over such systems, even when these systems, during deployments, are utterly outside of human control. I conclude by distinguishing between what I call “will-extending” and “will-offloading” systems, showing that off-the-loop systems can serve to extend users’ and deployers’ wills, making such systems inherently subject to meaningful human control. Throughout, the discussion focuses on the example of autonomous and AI-enabled systems in the military domain, but the underlying arguments relate to such systems more generally, showing how these, if utilized as “will-extending” systems, may be used in a controlled and responsibility-retaining manner
Adaptive tolerances for staggered solution algorithms in fluid-structure interaction
No full textStaggered solution algorithms are a well-known alternative to monolithic approaches for solving strongly coupled multi-field problems. A coupling between the subproblems is achieved by exchanging coupling quantities between the solvers. Implicit coupling schemes are realized by letting the solvers solve each load or time step repeatedly until convergence up to a given coupling tolerance is achieved. In fluid-structure interaction as well as a variety of other problem classes, the equations governing the individual fields are nonlinear. Accordingly, each solver performs an inner iterative solution procedure that terminates once an inner tolerance is reached. The basic idea of this work builds on the possibility to adaptively adjust these inner tolerances based on carefully designed rules while preserving the black-box nature of the solvers. The resulting coupling scheme yields significant improvements in computational efficiency compared to classical schemes where the inner solver tolerances are held fixed. This is demonstrated in several numerical examples. The idea is tested in combination with state-of-the-art convergence acceleration schemes and can be realized within any staggered solution approach by only minor modifications to the participating solvers
Transfer of an agrochemical process to a two-phase-operated jet loop reactor using the x-scaling approach
No full textLight simulation framework for the optimization of spatial structures for intra-satellite LiFi-communication
No full textLight Fidelity (LiFi) for intra-satellite communication offers immense advantages like flexible AIT and reduced harness complexity. This paper presents a simulation framework for light propagation with the primary goal to optimize positioning, spatial structures and other system parameters for intra-satellite LiFi-communication architectures. Initial tests were conducted with generic scenarios, such as obstacle simulation and the alignment of transmitters and receivers. In a subsequent step, a complete 3D model of a CubeSat was integrated into the simulation. The results demonstrate that the framework is already suitable for optimizing and visualizing optical communication structures. This allows for virtual analysis, enhancing or complementing physical test setups in the early stages of development