TUHH Open Research
TORE is the repository for Open Access publications and for research data of the Hamburg University of Technology (TUHH). As a research information system, TORE makes the TUHH's research landscape visible to the outside world. Institutes and working groups, researchers, their publications, research data and projects are presented here.
Members of the TUHH can publish their scientific work such as dissertations, preprints or accepted manuscripts as well as research data here and make them available in the long term.
TUHH Institutions
104
Researchers
989
Projects
1443
Publications
15383
Research Data
101
Conferences
3161
Recent Additions
- PublicationCode verification of immersed boundary techniques using the method of manufactured solutions(2023)Code verification plays a crucial role for all finite element applications, especially for non-standard ones, such as immersed boundary approaches, which are typically based on novel algorithms and often error-prone in-house implementations. Instead of relying on rarely available analytical solutions or overkill FEM simulations, in this article, the capabilities of the method of manufactured solutions (MoMS) are explored, enabling an easy and straightforward derivation of closed-form reference solutions. The focus is kept on immersed problems, in particular, on the finite cell method (FCM), and manufactured solutions are derived for 2D and 3D problems involving voids and single/multiple inclusions. We propose several approaches for the construction of the manufactured solutions, where zero traction conditions for void regions and continuous normal stresses along material interfaces are directly fulfilled. Thus, no weak boundary conditions are required for reproducing the manufactured solution via FCM. This not only enables code verification for FCM implementations that lack the option of applying weak boundary conditions, but also keeps the simulation complexity low, when testing other relevant features, e.g., different integration schemes or the implementation of enrichment functions. The flexibility and wide application range of the MoMS in the context of immersed boundary simulations is demonstrated using static, quasi-static, and transient problems in the context of linear elasticity. Finally, the analytical derivations of the manufactured solutions used in this paper are provided as supplementary material.Publication Type: Journal ArticlePublisher DOI:10.1007/s00466-023-02411-x
- PublicationMining thermophiles for biotechnologically relevant enzymes: evaluating the potential of European and Caucasian hot springs(Springer, 2024-04)The development of sustainable and environmentally friendly industrial processes is becoming very crucial and demanding for the rapid implementation of innovative bio-based technologies. Natural extreme environments harbor the potential for discovering and utilizing highly specific and efficient biocatalysts that are adapted to harsh conditions. This review focuses on extremophilic microorganisms and their enzymes (extremozymes) from various hot springs, shallow marine vents, and other geothermal habitats in Europe and the Caucasus region. These hot environments have been partially investigated and analyzed for microbial diversity and enzymology. Hotspots like Iceland, Italy, and the Azores harbor unique microorganisms, including bacteria and archaea. The latest results demonstrate a great potential for the discovery of new microbial species and unique enzymes that can be explored for the development of Circular Bioeconomy. Different screening approaches have been used to discover enzymes that are active at extremes of temperature (up 120 °C), pH (0.1 to 11), high salt concentration (up to 30%) as well as activity in the presence of solvents (up to 99%). The majority of published enzymes were revealed from bacterial or archaeal isolates by traditional activity-based screening techniques. However, the latest developments in molecular biology, bioinformatics, and genomics have revolutionized life science technologies. Post-genomic era has contributed to the discovery of millions of sequences coding for a huge number of biocatalysts. Both strategies, activity- and sequence-based screening approaches, are complementary and contribute to the discovery of unique enzymes that have not been extensively utilized so far.Publication Type: Review ArticlePublisher DOI:10.1007/s00792-023-01321-3
- PublicationA comparative study of the fixed pivot technique and finite volume schemes for multi-dimensional breakage population balances(Elsevier, 2023-12)When modeling particle breakage, the use of a single dimension to characterize particulate systems becomes intractable when multiple dimensions (e.g., size and shape) are important. Amongst many potential numerical techniques, the Fixed Pivot Technique (FPT) and Finite Volume Schemes (FVS) are popular choices to resolve multi-dimensional breakage population balance equations (PBEs). However, whether there exists a general multi-purpose technique between the two remains unclear. Across all test cases with identical size domain and mesh, while both techniques demonstrate comparable accuracy in resolving the moments and number densities (with maximum difference in average relative errors of ∼O(100) and ∼O(102), respectively), and exhibit similar computational efficiency (time taken by FPT relative to FVS is of ∼O(100)), the choice of numerical technique is contingent upon the properties where accurate prediction is critical. To this end, FVS is the preferred choice when precise estimation of up to two properties is required owing to its simplicity, albeit requiring distinct schemes for different properties. Conversely, when more than two properties are crucial, the FPT is more suited as it preserves up to four properties in the internal 2D space. Overall, this work offers rational guidance for efficient and accurate modeling of multi-dimensional breakages.Publication Type: Journal ArticlePublisher DOI:10.1016/j.apt.2023.104272
- PublicationNICOL : a Neuro-Inspired Collaborative semi-humanoid robot that bridges social interaction and reliable manipulation(IEEE, 2023-11-01)Robotic platforms that can efficiently collaborate with humans in physical tasks constitute a major goal in robotics. However, many existing robotic platforms are either designed for social interaction or industrial object manipulation tasks. The design of collaborative robots seldom emphasizes both their social interaction and physical collaboration abilities. To bridge this gap, we present the novel semi-humanoid NICOL, the Neuro-Inspired COLlaborator. NICOL is a large, newly designed, scaled-up version of its well-evaluated predecessor, the Neuro-Inspired COmpanion (NICO). NICOL adopts NICO's head and facial expression display and extends its manipulation abilities in terms of precision, object size, and workspace size. Our contribution in this paper is twofold - firstly, we introduce the design concept for NICOL, and secondly, we provide an evaluation of NICOL's manipulation abilities by presenting a novel extension for an end-to-end hybrid neuro-genetic visuomotor learning approach adapted to NICOL's more complex kinematics. We show that the approach outperforms the state-of-the-art Inverse Kinematics (IK) solvers KDL, TRACK-IK and BIO-IK. Overall, this article presents for the first time the humanoid robot NICOL, and contributes to the integration of social robotics and neural visuomotor learning for humanoid robots.Publication Type: Journal ArticlePublisher DOI:10.1109/ACCESS.2023.3329370
- PublicationNew support size bounds for integer programming, applied to makespan minimization on uniformly related machines(Schloss Dagstuhl – Leibniz-Zentrum für Informatik, Dagstuhl Publishing, 2023)
; ; Mixed-integer linear programming (MILP) is at the core of many advanced algorithms for solving fundamental problems in combinatorial optimization. The complexity of solving MILPs directly correlates with their support size, which is the minimum number of non-zero integer variables in an optimal solution. A hallmark result by Eisenbrand and Shmonin (Oper. Res. Lett., 2006) shows that any feasible integer linear program (ILP) has a solution with support size s ≤ 2m · log(4m∆), where m is the number of constraints, and ∆ is the largest absolute coefficient in any constraint. Our main combinatorial result are improved support size bounds for ILPs. We show that any ILP has a solution with support size s ≤ m · (log(3A_{max}) + √(log(A_{max}))), where A_{max} := ∥A∥_1 denotes the 1-norm of the constraint matrix A. Furthermore, we show support bounds in the linearized form s ≤ 2m · log(1.46A_{max}). Our upper bounds also hold with A_{max} replaced by √m∆, which improves on the previously best constants in the linearized form. Our main algorithmic result are the fastest known approximation schemes for fundamental scheduling problems, which use the improved support bounds as one ingredient. We design an efficient approximation scheme (EPTAS) for makespan minimization on uniformly related machines (Q||Cmax). Our EPTAS yields a (1 + ε)-approximation for Q||Cmax on N jobs in time 2^O(1/ε log3(1/ε) log(log(1/ε))) + O(N), which improves over the previously fastest algorithm by Jansen, Klein and Verschae (Math. Oper. Res., 2020) with run time 2^O(1/ε log4(1/ε)) + N^O(1). Arguably, our approximation scheme is also simpler than all previous EPTASes for Q||Cmax, as we reduce the problem to a novel MILP formulation which greatly benefits from the small support.Publication Type: Conference PaperPublisher DOI:10.4230/LIPIcs.ISAAC.2023.13
Recent Additions
- Research DataAnhang zum Sammelbandartikel - Sozial, ökologisch oder technisch-verkehrlich – Straßenkonzepte als Ansatzpunkt für multifunktionale Straßenräume(2023-11-09)Anhang zum Beitrag in Kreutz, S. und Stokman, A. (Hrsg.) (2024): Transformation urbaner linearer Infrastrukturlandschaften - Wie Straßen und Gewässer zu attraktiven und klimaangepassten Stadträumen werden können. oekom Verlag. Die vorliegenden Tabellen stammen aus dem Sammelbandartikel: Sozial, ökologisch oder technisch-verkehrlich? – Straßenkonzepte als Ansatzpunkt für multifunktionale Straßenräume, der im Sammelband: Transformation urbaner linearer Infrastrukturlandschaften - Wie Straßen und Gewässer zu attraktiven und klimaangepassten Stadträumen werden können, erschienen ist. Die Tabelle in Anhang 1 gibt eine Übersicht der im Rahmen des Artikels durchgeführten Literatur-Review zu Straßenkonzepten und gibt Auskunft über die Autoren, das Publikationsjahr und den geographischen Bezug. Neben der Überblicksfunktion der verwendeten Literatur können zudem die zeitlichen Entwicklungs- und Anwendungshorizonte, als auch die geographische Verbreitung von Straßenkonzepten verdeutlicht werden. Anhang 2 gibt einen Überblick der im Rahmen des Literatur-Reviews herausgearbeiteten Maßnahmen und deren Ziele bzw. Eigenschaften. Dabei werden die jeweiligen Maßnahmen übergeordneten Zielkategorien zugeordnet, die induktiv aus den herausgearbeiteten Maßnahmen abgeleitet werden und auf eine Vielzahl an fachdisziplinären Perspektiven zurückzuführen ist.Data Type: Text
- Research DataEnhancing 3D reconstruction accuracy of multi-voltage FIB tomography images using multimodal machine learning(2023-11-09)
; ; ; ; ; ; This dataset contains simulated multi-voltage FIB tomography data of hierarchical nanoporous gold, trained machine learning model weights and segmentation results of synthetic and real hierarchical nanoporous gold data. For more information, please refer to the published research article: Enhancing 3D reconstruction accuracy of multi-voltage FIB tomography images using multimodal machine learning.Data Type: Dataset - Research DataRole of slice thickness quantification in the 3D reconstruction of FIB tomography data of nanoporous materials(2023-11-02)
; ; ; ; ; ; This dataset contains synthetic structures of hierarchical nanoporous gold, which mimics real hierarchical nanoporous gold structures, segmentation results and repositioned interpolated structures of the real hierarchical nanoporous gold dataset and trained weights of machine learning model used for interpolation. For more information, please refer to the published research article: Role of slice thickness quantification in the 3D reconstruction of FIB tomography data of nanoporous materials.Data Type: Dataset - Research DataDissertation Melanie Tabea Knoll - Appendix 6.4: Detachment of biomaterial - OCT and video time lapse(2023-10-13)In bioelectrochemical systems (BES), the conversion of chemical energy into electrical energy and vice versa can be catalyzed by electroactive microorganisms. The microorganism-electrode interaction is a key factor that can limit sufficient space-time yield required for industrial applications. Providing the organisms with an artificial scaffold that enhances this interaction compared to the naturally formed biofilm matrix can significantly improve the productivity of these systems. In the context of the dissertation, such a hybrid biomaterial was established by embedding the electroactive model organism Shewanella oneidensis in an agarose hydrogel. The possibility of detaching the hybrid biofilm material should be investigated, as the recovery of the biomaterial could be essential in future application processes and reveal the maximum number of electrons that can be supplied before the material degrades. The latter is an important parameter for the potential application of the biomaterial in bioelectrosynthesis, a process in which organisms grow on the cathode as a source of electrons and energy and where the biomaterial could have similar beneficial effects on productivity to those shown in this thesis for anodic systems. Synthetic biofilm detachment was induced by applying a negative current to a sprayed hydrogel in a BES flow cell reactor. Detachment from two electrode materials, a graphite plate and a graphite felt, was visualized using video recording and optical coherence tomography (OCT). The graphite felt resulted in partial detachment of parts of the biofilm, whereas the graphite plate resulted in complete detachment of the biomaterial as a whole.Data Type: Video
- Research DataSupplementary material to article with title: Development and Assessment of a Methodology for Abstraction of Topology Optimization Results to Enable the Substitution of Optimized Beams(2023-10-10)
; ; ; The data is supplementary material to the article with title "Development and Assessment of a Methodology for Abstraction of Topology Optimization Results to Enable the Substitution of Optimized Beams" of the International Congress on Applications of Lasers & Electro-Optics (ICALEO) 2023, 16-19 October 2023, Chicago, Illinois, United States. A more detailed background on the files is given in the article. Mph-files can be opened with the software COMSOL Multiphysics 6.0. Implemented submethodologies can be viewed using the Application Builder of the Software.Data Type: Simulation Data