20005 research outputs found
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Schlussbericht zum IGF-Vorhaben "BePoT" (Nr. 22590 N)
No full textIm Forschungsprojekt "BePoT" wurde das Trichtermodell aus der Produktionslogistik erfolgreich auf den Portalkranbetrieb eines KV-Terminals übertragen. Darauf basierend wurden Durchlaufdiagramme und Betriebskennlinien für zwei wesentliche Auftragsarten der KV-Terminals – Kranaufträge und Abfertigungsaufträge – abgeleitet. Diese Modelle ermöglichen es zum einen, den Zielkonflikt zwischen einer hohen mittleren Kranleistung und einer kurzen mittleren Durchlaufzeit von Kran- und Abfertigungsaufträgen systematisch und allgemeingültig zu beschreiben. Zum anderen bilden sie eine Grundlage für die im Projekt entwickelten Monitorings- bzw. Auslastungs- und Buchungssystem. Darüber hinaus erfolgte im Forschungsprojekt die Entwicklung der Teilmodelle für drei wesentliche operative Verschwendungsarten in KV-Terminals – Zwischenlagerung, Umstapler und Kranleerfahrten – sowie für die entsprechenden Verbesserungsmaßnahmen – Direktumschläge, Stapellogiken und Doppelspiele. Diese Teilmodelle beschreiben zum einen die jeweiligen Verschwendungen bzw. Maßnahmen in Abhängigkeit von ihren Stellgrößen. Zum anderen ist es möglich, durch ihre Integration in die Kennlinienmodelle die einzelnen Effekte sowie den Gesamteffekt auf die logistischen Zielgrößen eines KV-Terminals zu beschreiben. Die im Projekt erzielten Ergebnisse zeigen, dass diese Verbesserungsmaßnahmen ein großes Potential haben, die Umschlagleistung von KV-Terminals zu steigern und den logistischen Zielkonflikt in den Terminals zu entschärfen.In the “BePoT” research project, the Funnel model from production logistics was successfully transferred to the gantry crane operations of a combined transport terminal. Based on this, throughput diagrams and Logistic Operating Curves (LOCs) were derived for two main types of orders at combined transport terminals – crane orders and dispatch orders. On the one hand, these models make it possible to systematically and generally describe the logistics objective conflict between high mean crane output rate and short mean throughput times of crane and dispatch orders. On the other hand, they form the basis for the monitoring, utilization, and booking systems developed in the project. In addition, the research project developed partial models for three key types of operational waste at combined transport terminals – intermediate storage, restacking and empty crane runs – as well as for the corresponding improvement measures – direct transshipments, stacking logics and double cycles. These partial models describe the respective types of waste and improvement measures as a function of their control variables. On the other hand, by integrating them into the LOC models, it is possible to describe the individual effects and the overall effect on the logistics objectives of combined transport terminals. The results achieved in the project show that these improvement measures have great potential to increase the handling performance and to defuse the logistics objective conflict in combined transport terminals.Bundesministerium für Wirtschaft und Energie (BMWE
FjordLink: comparison of starlink and 5G networks for teleoperated vessel control
No full textThe rapid growth of Low Earth Orbit satellite networks, such as Starlink, is increasing global connectivity by enabling low-latency broadband access in regions where wired and cellular networks fall short. Prior research focuses on the performance of Starlink in terrestrial settings. Yet, there is limited research on the performance of Starlink in coastal and maritime environments, raising the question of how Starlink performs in the presence of waves and tides. In this paper, we introduce the FjordLink, a combined Starlink and 5G dataset for coastal maritime connectivity. We collect over 500,000 measurements using a Flat High Performance dish and 5G modems on a research vessel for four months. Starlink and 5G networks achieve median RTTs of less than 50 ms and mean upload throughputs exceeding 35 Mbps. Our results show that Starlink operates similarly (e.g., with a 10 ms median latency difference) in both maritime and terrestrial environments, and improves the 99th percentile latency compared to 5G networks. As a case study, we utilize traces from FjordLink in emulation to evaluate BBR, CUBIC, and Reno congestion control algorithms, where BBR achieves 18% higher upload throughput than CUBIC and Reno
Systematic design of structured packings based on shape optimization
No full textDistillation is not only a widely-used but also an energy-intensive separation process, in which internals such as structured packings play an important role. Increasing mass transfer efficiency by designing improved structured packings in order to provide a large interfacial area while enabling low pressure drop is one promising approach to quickly reduce the energy requirements of vacuum distillation where low pressure drop is important for separation efficiency and thermal stability of the processed media. The current work presents an innovative method to optimize structured packings by means of constrained shape optimization on the basis of computational fluid dynamics simulations to minimize the pressure drop while maintaining a constant specific surface area. To solve the fluid dynamic optimization problem, a gradient-based local optimization algorithm in a continuous adjoint formulation is utilized. The shape optimization is applied for a commonly used Rombobak packing, and tested as a refinement method for an initial structure derived by topology optimization. The results demonstrate a successful reduction of the pressure drop in both cases, which can be attributed to several factors, including the refinement of the edges and the mending of the dead zones
Constitutive scientific generative agent (CSGA): leveraging large language models for automated constitutive model discovery
No full textData-driven approaches for constitutive modeling enable rapid, automated generation of models that predict a material’s mechanical response under load. Integrating theoretical knowledge into these approaches, which are then called grey-box approaches, can improve sample efficiency, extrapolation capability, and interpretability, albeit typically at the cost of experts required to use them. Recently, general-purpose large language model (LLM)-based scientific discovery methods have emerged as user-friendly approaches to scientific discovery. In this work, we compare two representatives of these paradigms: highly specialized constitutive artificial neural networks (CANNs) and the general LLM-based scientific generative agent (SGA) to evaluate current LLM capabilities in constitutive modeling. In addition, we introduce the constitutive scientific generative agent (CSGA) to combine both approaches’ strengths by enriching the SGA’s prompts with domain-specific data and materials theory. We compare CANN, SGA, and CSGA on three benchmark problems by assessing their accuracy in predicting stress responses under prescribed strain conditions. While our results show that CANNs remain the most accurate approach overall, the CSGA significantly outperforms the SGA and demonstrates the promise of specialized LLM-based methods for constitutive modeling. Moreover, the CSGA’s intuitive plain text interface and the full interpretability of the generated constitutive models make it a practical, accessible complement to existing approaches
Approach for classification of requirements and test conditions for safety-compliant testing of hydrogen components
No full textHydrogen is widely seen as one of the potential key energy sources of the future. Despite the existence of numerous guidelines specifying the tests required for certification of components in various fields, the potential dangers of hydrogen as a medium in test environments are not yet sufficiently taken into account. This work presents a classification-based approach to structure the requirements for tests with hydrogen-carrying components and to systematically derive measures that allow for efficient and safe tests within the demanded specifications. Finally, this approach is applied exemplarily to a cyclic test of a CFRP hydrogen tank
Concave geometric wear compensation in automated flap wheel grinding
No full textAbrasive flap wheels are widely used for finishing and deburring due to their adaptability to conform to the local workpiece geometry. The geometric wear, which depends on the contact situation, has significant influence on the grinding results, making consistent output of automated flap wheel grinding challenging. In this paper, concave geometric wear of flap wheels and its effects on the grinding result are investigated. Based on flap wear and surface assessment, an approach for compensating concave flap wear by rotating the tool is proposed and investigated. Results showed that uneven material removal for minor concave wear can be reduced, allowing for more efficient tool utilization
PKT im Überblick – Organisation, Projekte und Ausstattung
No full textDie Vielfalt an Produkten und Produktentwicklungsprozessen stellt Ingenieure fortwährend vor Herausforderungen. Besonders bei der Beherrschung von Komplexität infolge hoher Variantenvielfalt sowie der Strukturanalyse im Rahmen der Produktentwicklung bestehen zahlreiche offene Fragstellungen, aus denen ein Forschungsbedarf resultiert. Das Institut für Produktentwicklung und Konstruktionstechnik (PKT) der Technischen Universität Hamburg (TUHH) unter der Leitung von Professor Dr.-Ing. Dieter Krause stellt sich diesen Herausforderungen, um einen Beitrag zum wissenschaftlichen Fortschritt auf dem Gebiet der Produktentwicklung zu leisten.
Im vorliegenden Sammelwerk werden Forschungserkenntnisse des PKT aus den Jahren 2021 bis 2025 vorgestellt. Ziel ist es, einen Überblick über die unterschiedlichen Forschungsbereiche und Anwendungsfelder des PKT zu geben. Durch gezielte Einblicke in vielfältige Forschungsthemen sollen Erfahrungen auf den jeweiligen Gebieten aufgezeigt und ein Überblick über die Aktivitäten der letzten 5 Jahre gegeben werden.
Im ersten Kapitel wird ein Kurzüberblick über die Struktur des PKT, dessen Forschungsprojekte, sowie die Ausstattung gegeben. Darauf folgt im zweiten Kapitel ein Rückblick auf ausgewählte Ereignisse der Jahre 2021 bis 2025 aus den Bereichen Wissenschaftsdiskurs, Lehre und dem Wissenstransfer in die Industrie. Ein Einstieg in konkrete Forschungsinhalte erfolgt in den Themenkapiteln drei bis acht. Diese sind nach den jeweiligen Fokusthemen Modularisierung, Nachhaltigkeit in der Produktentwicklung, modellbasierte Entwicklung, Leichtbau, Sonderprüfstände und Medizintechnik gegliedert
Whey protein-based aerogels: structural insights, zinc-carrier properties, and zinc bioavailability in Caco-2 cells
No full textDue to their large surface area and modifiable structures, aerogels derived from biopolymers like whey protein isolate (WPI) are gaining attention as micronutrient carriers. However, their ability to incorporate essential trace elements like zinc, and how these ions affect aerogel structure and zinc bioavailability, remain poorly understood. This study aimed at characterizing the influence of zinc ions on the structural and morphological properties of WPI-based aerogels along with their ability for zinc delivery. Initially, hydrogels were prepared with WPI and zinc chloride at pH 1 and pH 3 and compared with formulations containing calcium chloride or sodium chloride. The hydrogels were then converted into aerogels via solvent exchange and supercritical drying. Analytical characterization included liquid chromatography-mass spectrometry for protein component profiling, flame atomic absorption spectrometry for metal retention, Fourier-transform infrared spectroscopy for secondary structure analysis, Brunauer-Emmett-Teller surface area measurements, scanning electron microscopy for morphological assessment, digestibility and zinc uptake in Caco-2 enterocytes via Zinpyr-1 fluorescence. Results showed a relative increase of β-lactoglobulin and a substantial ion loss during the hydrogel-to-alcogel transition – up to 70 % for calcium and 52 % for zinc – mainly due to solvent exchange, which affects protein-ion interactions. Fourier-transform infrared spectroscopy revealed increased intermolecular β-sheet formation and hydrogen bonding in the presence of divalent ions, suggesting enhanced protein-metal coordination. At pH 1, the aerogels exhibited pronounced porosity, a large surface area and enhanced enzymatic digestibility. In contrast, aerogels formed at pH 3 appeared denser, less digestible and retained higher amounts of metal ions. Zinc release from undigested aerogels was limited, likely due to matrix binding, whereas trypsin digestion slightly increased the zinc but without clear evidence for increased bioavailability compared to inorganic zinc. These findings show that pH and ion type influence the structure and function of WPI aerogels, highlighting their potential for targeted, digestible metal ion delivery
Validation of skew detection concepts for future leading-edge slats
No full textAccording to a policy statement released by the FAA, the safety analysis of flight control systems must be expanded to structural elements for certification of future commercial aircrafts [FAA 15]. This results in new requirements for high-lift systems. Conventional monitoring sensors, such as angular position sensors on the drive shaft or torque sensors at the drive unit, focus on detection of failures in the drivetrain rather than structural defects at the inematics or control surfaces. In a previous paper the authors identified the need for a new monitoring solution to fulfil these new requirements. A high potential concept consisting of position sensors monitoring the kinematic movement was identified via virtual testing. Another promising monitoring concept and the validation of the previously utilized modelling method via a test rig are presented in this paper. For this purpose, the test results for a multitude of failure scenarios are presented, analysed and compared to the findings of the virtual tests. Based on the outcome, additional insights of the validation process will be shared, and the most promising monitoring concept for skew detection will be proposed.Bundesministerium für Wirtschaft und Energie (BMWE
Computer-aided scaffold design optimization towards enhanced bone regeneration
No full textLarge bone defects remain a clinical challenge, with a gold standard treatment - autologous bone graft - that presents many drawbacks. Design optimized scaffolds appear as a promising alternative [1]; however, bone scaffold design remains a trial and error approach where some specific properties (porosity, mechanical properties, etc) are individually optimized. Thus, the aim of this study was to develop a computer-aided scaffold design optimisation framework towards enhanced bone regeneration, taking into account the dynamics of the bone regeneration process.
A computer model of scaffold-guided bone regeneration was developed and tested against different experimental setups that have used different scaffold designs for large bone defect healing in large animal models [2,3]. The model takes into account the scaffold design (architecture and material properties) as well as its interaction with different cellular processes (e.g. migration). Computer model predictions of bone tissue formation within the scaffold pores were compared against in vivo experimental data. The validated model was then used to develop a computer framework that allow us to optimize the scaffold design with the objective of achieving maximum bone regeneration.
The computer model of scaffold-supported bone regeneration is able to explain experimental observations of bone tissue formation within a honeycomb titanium scaffold and a strut-based PCL-βTCP scaffold. In both experimental settings, scaffold surface guidance was predicted to play a key role on the regulation of cellular activity. Computer-aided optimization resulted in a scaffold design which was predicted to achieve almost complete bone regeneration within a large bone defect.
We have developed a framework that allows 1) to investigate the mechanisms behind scaffold-supported bone regeneration and 2) to optimize the scaffold design to achieve maximum bone regeneration. Although, the computer model of bone regeneration has shown promising results in different experimental settings, further testing of the model and validation against experimental data is needed to ensure model robustness. The optimization framework allows shape optimization of specific scaffold designs. Future studies will focus on the validation of the optimization framework