490 Works

The influence of the drainage regime on the installation and the response to vertical cyclic loading of suction caissons

Marc Stapelfeldt
Auf Suction-Caisson-Jackets gegründete Offshore-Windenergieanlagen übertragen Lasten durch einen vertikalen Druck-Zug-Mechanismus. Dieser Mechanismus ist unter Berücksichtigung zyklischer Lasten ein maßgebender Konstruktionsaspekt. Konstruktionsrichtlinien sind begrenzt und liefern lediglich grobe Schätzungen. Der derzeitige Mangel an Daten zum Tragverhalten von Suction-Caissons in Sand und geschichtetem Boden erfordert die Durchführung wissenschaftlicher Untersuchungen. Dies erfolgt durch numerische Berechnungen und Zentrifugenversuche in denen das Tragverhalten von Suction-Caissons unter vertikaler zyklischer Belastung betrachtet wird. Die Ergebnisse zeigen keine keinen systematischen Einfluss der Sauginstallation...

Computation of backwater effects in low lying (marshland) catchments : a re-usable and efficient method in an open source hydrological model

Sandra Hellmers, Christoph Sauer & Peter Fröhle
An efficient method to solve a significant weakness in hydrological modelling to compute backwater effects in low lying catchments is presented. The re-usable and transferable method is implemented in the open source software KalypsoNA (KalypsoHydrology) and validated with results of a tidal influenced low lying catchment study.

Die HOOU an der TUHH : Erfahrungen und Erfolge 2020

Ann-Kathrin Watolla, Angelika Gruhn, Sven Drücker, Jennifer Lehmann, Ruth Schaldach, Christin Burkhardt, Anna Lainé, Henning Haschke, Axel Dürkop, Florian Hagen, Alexander Christiansen, Steffen Walk, Durga Prasad Babu Nasika, Anne Rödl, Dodo Schielein, Tina Carmesin & Stephan Dublasky
Im Jahr 2020 wurden 16 Projekte im Rahmen der Hamburg Open Online University (HOOU) an der TUHH gefördert und umgesetzt. Die projektspezifischen Erfahrungen und Erfolge werden in dieser Broschüre zusammenfassend dargestellt.

Application of the Strain Energy Density method to butt-welded joints

Atilla Acar

The hierarchical finite cell method for nonlinear problems: moment fitting quadratures, basis function removel, and remeshing

Simeon Hubrich
In dieser Arbeit werden mehrere Ansätze diskutiert, um die Performance der Finite Cell Methode (FCM) weiter zu optimieren. Hierbei werden neue Moment Fitting Quadraturen eingeführt, welche den numerischen Integrationsaufwand erheblich reduzieren. Zur Verbesserung der Konditionierung des resultierenden Gleichungssystems wird ein Verfahren zur Eliminierung von Basisfunktionen vorgestellt. Desweiteren wird eine innovative Neuvernetzungsstrategie präsentiert, die das Problem stark verzerrter Elemente bei Simulationen mit großen Deformationen überwindet.

Counter-Current Suspension Extraction Process of Lignocellulose in Biorefineries to Reach Low Water Consumption, High Extraction Yields, and Extract Concentrations

Marc Conrad & Irina Smirnova
The processing of large quantities of water in biorefining processes can lead to immense costs for heating, evaporation, and wastewater disposal. These costs may prohibit the exploitation of alternative products, e.g., xylooligosaccharides from straw, which are regarded as too costly. A new counter-current extractions method is proposed that aims at low solvent (water) consumption, as well as high yields and extract concentrations. This process was evaluated with suspension extraction experiments with steam pretreated wheat straw...

Functionalized carbon nanotubes (CNTs) for water and wastewater treatment : preparation to application

Mian Muhammad-Ahson Aslam, Hsion-Wen Kuo, Walter Den, Muhammad Usman, Muhammad Sultan & Hadeed Ashraf
As the world human population and industrialization keep growing, the water availability issue has forced scientists, engineers, and legislators of water supply industries to better manage water resources. Pollutant removals from wastewaters are crucial to ensure qualities of available water resources (including natural water bodies or reclaimed waters). Diverse techniques have been developed to deal with water quality concerns. Carbon based nanomaterials, especially carbon nanotubes (CNTs) with their high specific surface area and associated adsorption...

Experimental validation and parameter study of a 2D geometry-based, flexible designed thermal motor model for different cooled traction motor drives

Peer-Ole Gronwald & Thorsten Alexander Kern
For identifying new improvement potentials for electric traction motors, accurate models are needed. In this paper, a geometry-based 2D lumped parameter thermal network model for different electric traction motor and cooling concepts is studied and validated. In the second section, the design and functionality of the thermal model is explained. In the third section, the best fit of the literature correlations for describing the different heat transfer mechanisms was identified and a parameter study of...

Estimation of methane production and electrical energy generation from municipal solid waste disposal sites in Pakistan

Sohoo Ihsanullah, Marco Ritzkowski, Zubair Ahmed Sohu, Senem Önen Cinar, Zhi Kai Chong & Kerstin Kuchta
This work aimed to estimate the annual methane production from the municipal solid waste disposal sites in Pakistan. In this study, the Intergovernmental Panel on Climate Change (IPCC) default methodology was used to estimate theoretical methane formation potential of the waste disposal sites in major cities of Pakistan. The estimates of this study are based on the last population census conducted in the year 2017 and latest available data regarding the waste generation and management...

Asymptotic tracking position control with active oscillation damping of a multibody Mars vehicle using two artificial augmentation approaches

Daniel Bodmer, Michael Krenmayr & Florian Holzapfel
The Valles Marineris Explorer Cooperative Swarm navigation, Mission and Control research project aims to explore the Valles Marineris canyon system on Mars with, among others, multibody rotary-wing unmanned aerial vehicles (UAVs) comprising of a hexrotor system and a helium-filled balloon being attached to it by means of a rope. In this paper, we develop a high-fidelity closed-loop control system in MATLAB® and Simulink™ to present the application of an adequate flight controller guaranteeing (1) asymptotic...

Opportunities and Challenges of the European Green Deal for the Chemical Industry: An Approach Measuring Innovations in Bioeconomy

Lisa Thormann, Ulf Neuling & Martin Kaltschmitt
The Circular Economy Action Plan, as part of the European Green Deal announced by the European Commission, is highly relevant to the chemical industry in relation to the production of sustainable products. Accordingly, the chemical industry faces the question of how far it can promote its own manufacture of sustainable products. Within this context, this article presents an approach on how to measure innovations in bioeconomy. The methodological framework developed provides the chemical industry with...

True strength of ceramic fiber bundles : experiments and simulations

Leandro Neckel, Cristian A. Faller, Matej Babič, Oscar R. K. Montedo, Carlos P. Bergmann & Rolf Janßen
A study on the strength of ceramic fiber bundles based on experimental and computational procedures is presented. Tests were performed on single filaments and bundles composed of two fibers with different nominal fiber counts. A method based on fiber rupture signals was developed to estimate the amount of filament rupture during the test. Through this method, the fiber bundle true strength was determined and its variation with the initial fiber count observed. By using different...

MPIFiles.jl: A Julia Package for Magnetic Particle Imaging Files

Tobias Knopp, Martin Möddel, Florian Griese, Franziska Werner, Patryk Szwargulski, Nadine Gdaniec & Marija Boberg

Quantification of the resilience of integrated energy systems using dynamic simulation

Anne Senkel, Carsten Bode & Gerhard Schmitz
This paper demonstrates the use of dynamic simulation to model and assess the resilience of an integrated energy system. First, several approaches from the field of resilience assessment are evaluated, and the most suitable is chosen and adapted to develop a metric that is applicable to dynamic simulation results. Second, as proof of concept, a model of an integrated energy system (gas, heat and power sector) is presented and evaluated using the introduced metric. To...

Fatigue and fatigue after impact behaviour of Thin- and Thick-Ply composites observed by computed tomography

Benedikt Kötter, Janina Mittelhaus, Johann Körbelin, Florian Bittner, Hans-Josef Endres & Bodo Fiedler
This study investigates the influence of load ratio and impact damage on the fatigue behaviour of high-performance carbon fibre reinforced polymers (CFRP) with areal fibre weights between 30 gsm and 360 gsm. For undamaged samples, the ultimate tensile and compressive strength, as well as the fatigue properties, are evaluated with regard to their layer thicknesses. The fatigue tests were performed under tension-tension (R=0.1), tension-compression (R=-0.5) and compression-compression (R=10) regime. The results are illustrated as a...

Connector-breaker games on random boards

Dennis Clemens, Laurin Kirsch & Yannick Mogge
The Maker-Breaker connectivity game on a complete graph Kn or on a random graph G ∼ Gn,p is well studied by now. Recently, London and Pluhár suggested a variant in which Maker always needs to choose her edges in such a way that her graph stays connected. It follows from their results that for this connected version of the game, the threshold bias on Kn and the threshold probability on G ∼ Gn,p for winning...

Metamodels for evaluating, calibrating and applying agent-based models : a review

Bruno Pietzsch, Sebastian Fiedler, Kai G. Mertens, Markus Richter, Cédric Scherer, Kirana Widyastuti, Marie-Christin Wimmler, Liubov Zakharova & Uta Berger
The recent advancement of agent-based modeling is characterized by higher demands on the pa-rameterization, evaluation and documentation of these computationally expensive models. Accordingly, there is also a growing request for “easy to go” applications just mimicking the input-output behavior of such mod-els. Metamodels are being increasingly used for these tasks. In this paper, we provide an overview of common metamodel types and the purposes of their usage in an agent-based modeling context. To guide modelers...

Model-based workflow for scale-up of process strategies developed in miniaturized bioreactor systems

Lukas Arndt, Vincent Wiegmann, Kim Beatrice Kuchemüller, Frank Baganz, Ralf Pörtner & Johannes Möller
Miniaturized bioreactor (MBR) systems are routinely used in the development of mammalian cell culture processes. However, scale-up of process strategies obtained in MBR- to larger scale is challenging due to mainly non-holistic scale-up approaches. In this study, a model-based workflow is introduced to quantify differences in the process dynamics between bioreactor scales and thus enable a more knowledge-driven scale-up. The workflow is applied to two case studies with antibody-producing Chinese hamster ovary cell lines. With...

A strategy for dimensionality reduction and data analysis applied to microstructure–property relationships of nanoporous metals

Norbert Huber
Nanoporous metals, with their complex microstructure, represent an ideal candidate for the development of methods that combine physics, data, and machine learning. The preparation of nanporous metals via dealloying allows for tuning of the microstructure and macroscopic mechanical properties within a large design space, dependent on the chosen dealloying conditions. Specifically, it is possible to define the solid fraction, ligament size, and connectivity density within a large range. These microstructural parameters have a large impact...

Optimization of soil aquifer treatment by chemical oxidation with hydrogen peroxide addition

Muhammad Usman, Muhammad Waseem, Nithish Mani & George Andiego
Trace organic compounds (TrOCs), mostly found in secondary effluents have a potential impact on the environment including surface water, groundwater and especially aquatic ecosystems. This study focuses on the oxidation of five selected TrOCs in column experiments simulating soil aquifer treatment (SAT) integrated with Fenton-like reaction using granular ferric hydroxide (GFH) as a catalyst. In order to determine the effectiveness of removing TrOCs by water through this approach, experiments were carried out with ultrapure water...

Critical thresholds for mode-coupling instability in viscoelastic sliding contacts

Antonio Papangelo, Carmine Putignano & Norbert Hoffmann
Mode-coupling instabilities are known to trigger self-excited vibrations in sliding contacts. Here, the conditions for mode-coupling (or “flutter”) instability in the contact between a spherical oscillator and a moving viscoelastic substrate are studied. The work extends the classical 2-Degrees-Of-Freedom conveyor belt model and accounts for viscoelastic dissipation in the substrate, adhesive friction at the interface and nonlinear normal contact stiffness as derived from numerical simulations based on a boundary element method capable of accounting for...

Variety-driven design to reduce complexity costs of a tire curing press family

Christoph Rennpferdt, Erik Greve & Dieter Krause
As a result of the prevailing megatrends, many companies are diversifying their product program further and further. Additional product variants are being developed in order to implement the increasing variety of offers. However, these variants increase the complexity within the company. The development of variety-oriented product structures is one way to counteract this increasing complexity. In this contribution, we will show how variety-oriented product structures can be developed with the help of the Design for...

Direct writing of colloidal suspensions onto inclined surfaces: optimizing dispense volume for homogeneous structures

Benedikt Winhard, Stefanie Haugg, Robert H. Blick, Gerold A. Schneider & Kaline Pagnan Furlan
Hypothesis: A process to fabricate structures on inclined substrates has the potential to yield novel applications for colloidal-based structures. However, for conventional techniques, besides the coffee ring effect (CRE), anisotropic particle deposition along the inclination direction (IE) is expected to occur. We hypothesize that both effects can be inhibited by reducing the dispense volume during printing by direct writing. Experiments: We combined an additive manufacturing technique, namely direct writing, with colloidal assembly (AMCA) for an...

Substrate integrated waveguide technology for Rx/Tx integrated array antennas

Thomas Jaschke
Diese Arbeit behandelt einen Gruppenstrahler mit integrierten Empfangs- und Sendeeinheiten für die mobile Satellitenkommunikation im K/Ka-Band. Die Realisierung wird durch im Substrat integrierten Wellenleitern ermöglicht, welche eingehend untersucht werden. Ein Leitungsmodell für sogenannte im Substrat integrierte mehrlagen Wellenleiter wird entwickelt. Es berücksichtigt Verluste und Leiter mit rauen Oberflächen. Hierauf basierend werden Komponenten entworfen und schließlich zu einem passiven Gruppenstrahler mit zwei Polarisationen zusammengesetzt. Dies demonstriert, dass im Vergleich zu getrennten Empfangs- und Sendeantennen eine erhebliche...

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