Refine
Year of publication
- 2024 (54) (remove)
Institute
- Fachbereich Medizintechnik und Technomathematik (23)
- IfB - Institut für Bioengineering (10)
- Fachbereich Elektrotechnik und Informationstechnik (8)
- Fachbereich Luft- und Raumfahrttechnik (7)
- INB - Institut für Nano- und Biotechnologien (7)
- Fachbereich Chemie und Biotechnologie (5)
- Fachbereich Wirtschaftswissenschaften (5)
- ECSM European Center for Sustainable Mobility (4)
- Nowum-Energy (2)
- Arbeitsstelle fuer Hochschuldidaktik und Studienberatung (1)
Language
- English (54) (remove)
Document Type
- Article (34)
- Conference Proceeding (12)
- Part of a Book (3)
- Book (2)
- Preprint (2)
- Working Paper (1)
Keywords
- Engineering education (2)
- Hot S-parameter (2)
- 1P hub loads (1)
- 3-D printing (1)
- 316L (1)
- ABE (1)
- Accuracy (1)
- Acid crash (1)
- Active humidity control (1)
- Acyl-amino acids (1)
- Acylation (1)
- Additive manufacturing (1)
- Aeroelasticity (1)
- Ageing (1)
- Agent-based modeling (1)
- Aminoacylase (1)
- Analytical models (1)
- Anatomy (1)
- Bio-inspired systems (1)
- Biocatalysis (1)
- Biological hydrogen (1)
- Biosurfactants (1)
- Boundary integral equations, (1)
- Butanol (1)
- C. acetobutylicum (1)
- Capacitive model (1)
- Carrier solvents (1)
- Centrifugal twisting moment (1)
- Chaperone (1)
- Circuit simulation (1)
- Coal (1)
- Collagen fibrils (1)
- Comparative simulation (1)
- Complex-valued eigenvalues (1)
- Connective tissues (1)
- Constitutive model (1)
- Control engineering (1)
- DAC (1)
- DC machines (1)
- Damage mechanics theory (1)
- Dark fermentation (1)
- Data analysis (1)
- Data visualization (1)
- Database (1)
- Discontinuous fractures (1)
- Dynamic modeling (1)
- E. coli detection (1)
- ESATAN-TMS (1)
- Eigenvalue trajectories (1)
- Electrochemical impedance spectroscopy (1)
- Electronic cigarettes (1)
- Electronic learning (1)
- Energy dispatch (1)
- Energy market (1)
- Enzyme coverage (1)
- Exponential Euler scheme, (1)
- Extension–twist coupling (1)
- Extracellular matrix (ECM) (1)
- Fault detection (1)
- Field-effect biosensor (1)
- Flutter (1)
- Focusing (1)
- Free-base nicotine (1)
- Fuel cell (1)
- Furnace (1)
- Fusion (1)
- German (1)
- Germany (1)
- H2 (1)
- Health management system (1)
- Hydrogenotrophic methanogens (1)
- Hydrolysis (1)
- Impedance analysis (1)
- Instruments (1)
- Interior transmission problem (1)
- LPBF (1)
- LQR (1)
- Li7La3Zr2O12 (1)
- LiGaO2 (1)
- Lifting propeller (1)
- Low field NMR (1)
- Low voltage (1)
- Lunar Surface (1)
- MOS (1)
- MPC (1)
- Manifolds (1)
- Master stamp (1)
- Matlab (1)
- Measurement (1)
- Mechanical stability (1)
- Metabolic shift (1)
- Methane (1)
- Methanogenesis (1)
- Mode converter (1)
- Modeling (1)
- Monitoring (1)
- Multianalyte detection (1)
- Muscle (1)
- Musculoskeletal system (1)
- Non-model-based Evaluation (1)
- Non-parallel fissures (1)
- Nonlinear eigenvalue problems (1)
- Obstacle avoidance (1)
- Online diagnostic (1)
- Online services (1)
- Open Data (1)
- Open source (1)
- Organic waste (1)
- P2G (1)
- PEM fuel cell (1)
- PPO (1)
- Parabolic SPDEs (1)
- Path planning (1)
- Penicillin (1)
- Photolithographic mimics (1)
- Physiology (1)
- Plasma (1)
- Plasma diagnostics (1)
- Power dissipation (1)
- Pre-culture (1)
- Pretreatment (1)
- Propeller whirl flutter (1)
- Quartz crystal microbalance (1)
- Raman spectroscopy (1)
- Refining (1)
- Reinforcement Learning (1)
- Relative air humidity (1)
- Renewable energy sources (1)
- Rotatory Inverted Pendulum (1)
- SLM (1)
- Simulation (1)
- Software packages (1)
- Surface imprinted polymer (1)
- Synchronous machines (1)
- Tapered ends (1)
- Thermal Model (1)
- Thermal analysis (1)
- Thermal conductivity (1)
- Throughput (1)
- Time-series (1)
- Training (1)
- Trapeze effect (1)
- Uniaxial compression test (1)
- Unmanned aerial vehicles (1)
- Unsteady aerodynamics (1)
- Weak organic acids (1)
- aquaculture (1)
- artificial olfactory image (1)
- biodegradable polymers (1)
- biomethane (1)
- bubble column (1)
- carbon dioxide removal (1)
- catalytic metal (1)
- chip-based sensor setup (1)
- climate neutrality (1)
- coupled Néel–Brownian relaxation dynamics (1)
- direct air capture (1)
- economics (1)
- electrical conductivity of liquids (1)
- electronic nose (1)
- field-effect structure (1)
- frequency mixing magnetic detection (1)
- ga-doping (1)
- garnet solid electrolyte (1)
- gas sensor (1)
- glycine (1)
- hydrogels (1)
- hydrogen peroxide (1)
- impedance spectroscopy (1)
- key performance indicators (1)
- large language models (1)
- light-addressing technologies (1)
- magnetic biosensing (1)
- magnetic nanoparticles (1)
- magnetic relaxation (1)
- metal-oxide-semiconductor structure (1)
- methanation (1)
- microfluidics (1)
- micromagnetic simulation (1)
- micronutrients (1)
- negative emissions (1)
- optical spore trapping (1)
- plug flow reactor (1)
- polyaspartic acid (1)
- rollout (1)
- scanned light pulse technique (1)
- semantic role labeling (1)
- solid-state battery (1)
- speaker attribution (1)
- sterilization conditions (1)
- superabsorbent polymers (1)
- swelling properties (1)
- temperature (1)
- thermometry (1)
- visualization (1)
The Inverted Rotary Pendulum: Facilitating Practical Teaching in Advanced Control Engineering
(2024)
This paper outlines a practical approach to teach control engineering principles, with an inverted rotary pendulum, serving as an illustrative example. It shows how the pendulum is embedded in an advanced course of control engineering. This approach is incorporated into a flipped-classroom concept, as well as classical teaching concepts, offering students practical experience in control engineering. In addition, the design of the pendulum is shown, using a Raspberry Pi as the target platform for Matlab Simulink. This pendulum can be used in the classroom to evaluate the controller design mentioned above. It is analysed if the use of the pendulum generates a deeper understanding of the learning contents.
Many important properties of bacterial cellulose (BC), such as moisture absorption capacity, elasticity and tensile strength, largely depend on its structure. This paper presents a study on the effect of the drying method on BC films produced by Medusomyces gisevii using two different procedures: room temperature drying (RT, (24 ± 2 °C, humidity 65 ± 1%, dried until a constant weight was reached) and freeze-drying (FD, treated at − 75 °C for 48 h). BC was synthesized using one of two different carbon sources—either glucose or sucrose. Structural differences in the obtained BC films were evaluated using atomic force microscopy (AFM), scanning electron microscopy (SEM), and X-ray diffraction. Macroscopically, the RT samples appeared semi-transparent and smooth, whereas the FD group exhibited an opaque white color and sponge-like structure. SEM examination showed denser packing of fibrils in FD samples while RT-samples displayed smaller average fiber diameter, lower surface roughness and less porosity. AFM confirmed the SEM observations and showed that the FD material exhibited a more branched structure and a higher surface roughness. The samples cultivated in a glucose-containing nutrient medium, generally displayed a straight and ordered shape of fibrils compared to the sucrose-derived BC, characterized by a rougher and wavier structure. The BC films dried under different conditions showed distinctly different crystallinity degrees, whereas the carbon source in the culture medium was found to have a relatively small effect on the BC crystallinity.
This paper investigates the interior transmission problem for homogeneous media via eigenvalue trajectories parameterized by the magnitude of the refractive index. In the case that the scatterer is the unit disk, we prove that there is a one-to-one correspondence between complex-valued interior transmission eigenvalue trajectories and Dirichlet eigenvalues of the Laplacian which turn out to be exactly the trajectorial limit points as the refractive index tends to infinity. For general simply-connected scatterers in two or three dimensions, a corresponding relation is still open, but further theoretical results and numerical studies indicate a similar connection.
New insights into the influence of pre-culture on robust solvent production of C. acetobutylicum
(2024)
Clostridia are known for their solvent production, especially the production of butanol. Concerning the projected depletion of fossil fuels, this is of great interest. The cultivation of clostridia is known to be challenging, and it is difficult to achieve reproducible results and robust processes. However, existing publications usually concentrate on the cultivation conditions of the main culture. In this paper, the influence of cryo-conservation and pre-culture on growth and solvent production in the resulting main cultivation are examined. A protocol was developed that leads to reproducible cultivations of Clostridium acetobutylicum. Detailed investigation of the cell conservation in cryo-cultures ensured reliable cell growth in the pre-culture. Moreover, a reason for the acid crash in the main culture was found, based on the cultivation conditions of the pre-culture. The critical parameter to avoid the acid crash and accomplish the shift to the solventogenesis of clostridia is the metabolic phase in which the cells of the pre-culture were at the time of inoculation of the main culture; this depends on the cultivation time of the pre-culture. Using cells from the exponential growth phase to inoculate the main culture leads to an acid crash. To achieve the solventogenic phase with butanol production, the inoculum should consist of older cells which are in the stationary growth phase. Considering these parameters, which affect the entire cultivation process, reproducible results and reliable solvent production are ensured.
Lifting propellers are of increasing interest for Advanced Air Mobility. All propellers and rotors are initially twisted beams, showing significant extension–twist coupling and centrifugal twisting. Torsional deformations severely impact aerodynamic performance. This paper presents a novel approach to assess different reasons for torsional deformations. A reduced-order model runs large parameter sweeps with algebraic formulations and numerical solution procedures. Generic beams represent three different propeller types for General Aviation, Commercial Aviation, and Advanced Air Mobility. Simulations include solid and hollow cross-sections made of aluminum, steel, and carbon fiber-reinforced polymer. The investigation shows that centrifugal twisting moments depend on both the elastic and initial twist. The determination of the centrifugal twisting moment solely based on the initial twist suffers from errors exceeding 5% in some cases. The nonlinear parts of the torsional rigidity do not significantly impact the overall torsional rigidity for the investigated propeller types. The extension–twist coupling related to the initial and elastic twist in combination with tension forces significantly impacts the net cross-sectional torsional loads. While the increase in torsional stiffness due to initial twist contributes to the overall stiffness for General and Commercial Aviation propellers, its contribution to the lift propeller’s stiffness is limited. The paper closes with the presentation of approximations for each effect identified as significant. Numerical evaluations are necessary to determine each effect for inhomogeneous cross-sections made of anisotropic material.
In the research domain of energy informatics, the importance of open datais rising rapidly. This can be seen as various new public datasets are created andpublished. Unfortunately, in many cases, the data is not available under a permissivelicense corresponding to the FAIR principles, often lacking accessibility or reusability.Furthermore, the source format often differs from the desired data format or does notmeet the demands to be queried in an efficient way. To solve this on a small scale atoolbox for ETL-processes is provided to create a local energy data server with openaccess data from different valuable sources in a structured format. So while the sourcesitself do not fully comply with the FAIR principles, the provided unique toolbox allows foran efficient processing of the data as if the FAIR principles would be met. The energydata server currently includes information of power systems, weather data, networkfrequency data, European energy and gas data for demand and generation and more.However, a solution to the core problem - missing alignment to the FAIR principles - isstill needed for the National Research Data Infrastructure.
Due to the transition to renewable energies, electricity markets need to be made fit for purpose. To enable the comparison of different energy market designs, modeling tools covering market actors and their heterogeneous behavior are needed. Agent-based models are ideally suited for this task. Such models can be used to simulate and analyze changes to market design or market mechanisms and their impact on market dynamics. In this paper, we conduct an evaluation and comparison of two actively developed open-source energy market simulation models. The two models, namely AMIRIS and ASSUME, are both designed to simulate future energy markets using an agent-based approach. The assessment encompasses modelling features and techniques, model performance, as well as a comparison of model results, which can serve as a blueprint for future comparative studies of simulation models. The main comparison dataset includes data of Germany in 2019 and simulates the Day-Ahead market and participating actors as individual agents. Both models are comparable close to the benchmark dataset with a MAE between 5.6 and 6.4 €/MWh while also modeling the actual dispatch realistically.
This paper serves as an introduction to the ECTS monitoring system and its potential applications in higher education. It also emphasizes the potential for ECTS monitoring to become a proactive system, supporting students by predicting academic success and identifying groups of potential dropouts for tailored support services. The use of the nearest neighbor analysis is suggested for improving data analysis and prediction accuracy.
We conducted a scoping review for active learning in the domain of natural language processing (NLP), which we summarize in accordance with the PRISMA-ScR guidelines as follows:
Objective: Identify active learning strategies that were proposed for entity recognition and their evaluation environments (datasets, metrics, hardware, execution time).
Design: We used Scopus and ACM as our search engines. We compared the results with two literature surveys to assess the search quality. We included peer-reviewed English publications introducing or comparing active learning strategies for entity recognition.
Results: We analyzed 62 relevant papers and identified 106 active learning strategies. We grouped them into three categories: exploitation-based (60x), exploration-based (14x), and hybrid strategies (32x). We found that all studies used the F1-score as an evaluation metric. Information about hardware (6x) and execution time (13x) was only occasionally included. The 62 papers used 57 different datasets to evaluate their respective strategies. Most datasets contained newspaper articles or biomedical/medical data. Our analysis revealed that 26 out of 57 datasets are publicly accessible.
Conclusion: Numerous active learning strategies have been identified, along with significant open questions that still need to be addressed. Researchers and practitioners face difficulties when making data-driven decisions about which active learning strategy to adopt. Conducting comprehensive empirical comparisons using the evaluation environment proposed in this study could help establish best practices in the domain.
Aircraft configurations with propellers have been drawing more attention in recent times, partly due to new propulsion concepts based on hydrogen fuel cells and electric motors. These configurations are prone to whirl flutter, which is an aeroelastic instability affecting airframes with elastically supported propellers. It commonly needs to be mitigated already during the design phase of such configurations, requiring, among other things, unsteady aerodynamic transfer functions for the propeller. However, no comprehensive assessment of unsteady propeller aerodynamics for aeroelastic analysis is available in the literature. This paper provides a detailed comparison of nine different low- to mid-fidelity aerodynamic methods, demonstrating their impact on linear, unsteady aerodynamics, as well as whirl flutter stability prediction. Quasi-steady and unsteady methods for blade lift with or without coupling to blade element momentum theory are evaluated and compared to mid-fidelity potential flow solvers (UPM and DUST) and classical, derivative-based methods. Time-domain identification of frequency-domain transfer functions for the unsteady propeller hub loads is used to compare the different methods. Predictions of the minimum required pylon stiffness for stability show good agreement among the mid-fidelity methods. The differences in the stability predictions for the low-fidelity methods are higher. Most methods studied yield a more unstable system than classical, derivative-based whirl flutter analysis, indicating that the use of more sophisticated aerodynamic modeling techniques might be required for accurate whirl flutter prediction.