Publikationen an der Fakultät für Informatik und Automatisierung ab 2015

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Bedini, Francesco; Räth, Timo; Maschotta, Ralph; Sattler, Kai-Uwe; Zimmermann, Armin
Automated transformation of a domain-specific language for system modeling to Stochastic Colored Petri Nets. - In: IEEE Xplore digital library, ISSN 2473-2001, (2024), insges. 8 S.

Petri Net models are widely recognized for their ability to analyze concurrent, stochastic processes based on a solid mathematical foundation. However, one drawback of Petri Nets is their low-level abstraction: they offer only a few basic elements like places and transitions to represent all system components. While this limitation may not be an issue when working with small models, it becomes challenging when attempting to model larger processes or systems. As the complexity increases, the number of elements in the Petri Net also grows, making it difficult to distinguish and maintain them effectively. Furthermore, Petri Nets require verification to ensure that they accurately represent the behavior of the system they are intended to model. This verification process must be repeated whenever a model is created or modified. To address these challenges, this paper describes a Stochastic colored Petri Net semantics of a domain-specific language that allows modeling time-based hardware and software systems. We have developed a custom Eclipse-based framework that allows for both graphical and textual modeling, providing editors with useful features such as real-time validation of model constraints, which is not feasible at the low-level Petri Net abstraction due to the lack of contextual information. The DSL also offers the advantage of easy conversion from other modeling languages thanks to an intermediate language. From the model, valid Stochastic Colored Petri Nets (SCPNs) can be generated, which can automatically simulate certain system properties consistently. This approach aims to enhance modeling capabilities and alleviate some of the limitations associated with traditional Petri Nets.
Aguirre Mehlhorn, Marcel; Dierend, Hauke; Richter, Andreas; Shardt, Yuri A. W.
A stakeholder analysis of operational design domains of automated driving systems. - In: IEEE Xplore digital library, ISSN 2473-2001, (2024), insges. 2 S.

Developing an automated driving system (ADS) involves collaboration between various stakeholders. To support this process, the concept of operational design domain (ODD) has emerged. Nonetheless, stakeholders require variable levels of information from an ODD. A thorough investigation has identified eight main stakeholder categories. Furthermore, a stakeholder analysis is used to assess their expectations, interests, and influence. These findings briefly summarise all necessary ODD engineering requirements and deliverables for all ODD stakeholders.
Mora, Karin; Rzanny, Michael Carsten; Wäldchen, Jana; Feilhauer, Hannes; Kattenborn, Teja; Kraemer, Guido; Mäder, Patrick; Svidzinska, Daria; Wolf, Sophie; Mahecha, Miguel
Macrophenological dynamics from citizen science plant occurrence data. - In: Methods in ecology and evolution, ISSN 2041-210X, Bd. 00 (2024), 0, insges. 16 S.

Phenological shifts across plant species is a powerful indicator to quantify the effects of climate change. Today, mobile applications with automated species identification open new possibilities for phenological monitoring across space and time. Here, we introduce an innovative spatio-temporal machine learning methodology that harnesses such crowd-sourced data to quantify phenological dynamics across taxa, space and time. Our algorithm links individual phenological responses across thousands of species and geographical locations, using a similarity measure. The analysis draws on nearly ten million plant observations collected through the AI-based plant identification app Flora Incognita in Germany from 2018 to 2021. Our method quantifies changes in synchronisation across the annual cycle. During the growing season, synchronised behaviour can be encoded by a few characteristic macrophenological patterns. Nonlinear spatio-temporal changes of these patterns can be efficiently quantified using a data compressibility measure. Outside the growing season, the phenological synchronisation diminishes introducing noise into the patterns. Despite biases and uncertainties associated with crowd-sourced data, for example due to human data collection behaviour, our study demonstrates the feasibility of deriving meaningful indicators for monitoring plant macrophenology from individual plant observations. As crowd-sourced databases continue to expand, our approach holds promise to study climate-induced phenological shifts and feedback loops.
Funnell, Jessica L.; Fougere, Jasper; Zahn, Diana; Dutz, Silvio; Gilbert, Ryan J.
Delivery of TGFβ3 from magnetically responsive coaxial fibers reduces spinal cord astrocyte reactivity in vitro. - In: Advanced biology, ISSN 2701-0198, Bd. 0 (2024), 0, 2300531, S. 1-14

A spinal cord injury (SCI) compresses the spinal cord, killing neurons and glia at the injury site and resulting in prolonged inflammation and scarring that prevents regeneration. Astrocytes, the main glia in the spinal cord, become reactive following SCI and contribute to adverse outcomes. The anti-inflammatory cytokine transforming growth factor beta 3 (TGFβ3) has been shown to mitigate astrocyte reactivity; however, the effects of prolonged TGFβ3 exposure on reactive astrocyte phenotype have not yet been explored. This study investigates whether magnetic core-shell electrospun fibers can be used to alter the release rate of TGFβ3 using externally applied magnetic fields, with the eventual application of tailored drug delivery based on SCI severity. Magnetic core-shell fibers are fabricated by incorporating superparamagnetic iron oxide nanoparticles (SPIONs) into the shell and TGFβ3 into the core solution for coaxial electrospinning. Magnetic field stimulation increased the release rate of TGFβ3 from the fibers by 25% over 7 days and released TGFβ3 reduced gene expression of key astrocyte reactivity markers by at least twofold. This is the first study to magnetically deliver bioactive proteins from magnetic fibers and to assess the effect of sustained release of TGFβ3 on reactive astrocyte phenotype.
Zahn, Diana; Diegel, Marco; Valitova, Alina; Dellith, Jan; Dutz, Silvio
Magnetic barium hexaferrite nanoparticles with tunable coercivity as potential magnetic heating agents. - In: Nanomaterials, ISSN 2079-4991, Bd. 14 (2024), 12, 992, S. 1-20

Using magnetic nanoparticles (MNPs) for extracorporeal heating applications results in higher field strength and, therefore, particles of higher coercivity can be used, compared to intracorporeal applications. In this study, we report the synthesis and characterization of barium hexa-ferrite (BaFe12O19) nanoparticles as potential particles for magnetic heating. Using a precipitation method followed by high-temperature calcination, we first studied the influence of varied synthesis parameters on the particles’ properties. Second, the iron-to-barium ratio (Fe/Ba = r) was varied between 2 and 12. Vibrating sample magnetometry, scanning electron microscopy and X-ray diffraction were used for characterization. A considerable influence of the calcination temperature (Tcal) was found on the resulting magnetic properties, with a decrease in coercivity (HC) from values above 370 kA/m for Tcal = 800-1000 ˚C to HC = 45-70 kA/m for Tcal = 1200 ˚C. We attribute this drop in HC mainly to the formation of entirely multi-domain particles at high Tcal. For the varying Fe/Ba ratios, increasing amounts of BaFe2O4 as an additional phase were detected by XRD in the small r (barium surplus) samples, lowering the particles’ magnetization. A decrease in HC was found in the increased r samples. Crystal size ranged from 47 nm to 240 nm and large agglomerates were seen in SEM images. The reported particles, due to their controllable coercivity, can be a candidate for extracorporeal heating applications in the biomedical or biotechnological field.
Petkoviâc, Bojana; Ziolkowski, Marek; Töpfer, Hannes; Haueisen, Jens
A new stress tensor approach for application to the conductor surface. - In: Compel, ISSN 2054-5606, Bd. 0 (2024), 0

Purpose: The purpose of this paper is to derive a new stress tensor for calculating the Lorentz force acting on an arbitrarily shaped nonmagnetic conductive specimen moving in the field of a permanent magnet. The stress tensor allows for a transition from a volume to a surface integral for force calculation. Design/methodology/approach: This paper derives a new stress tensor which consists of two parts: the first part corresponds to the scaled Poynting vector and the second part corresponds to the velocity term. This paper converts the triple integral over the volume of the conductor to a double integral over its surface, where the subintegral functions are continuous through the different compartments of the model. Numerical results and comparison to the standard volume discretization using the finite element method are given. Findings: This paper evaluated the performance of the new stress tensor computation on a thick and thin cuboid, a thin disk, a sphere and a thin cuboid containing a surface defect. The integrals are valid for any geometry of the specimen and the position and orientation of the magnet. The normalized root mean square errors are below 0.26% with respect to a reference finite element solution applying volume integration. Originality/value: Tensor elements are continuous throughout the model, allowing integration directly over the conductor surface.
Oppermann, Hannes; Fiedler, Patrique; Haueisen, Jens
Microstates analysis for dry and gel-based multichannel electroencephalography. - In: 9th European Medical and Biological Engineering Conference, (2024), S. 122-130

Spatial analysis of EEG data, e.g. using short-term stable microstates, is increasingly used in neuroscience and clinical applications. At the same time, scenarios involving mobility, sports, and home-based activities are becoming more prevalent in EEG studies. For this purpose, dry EEG electrodes are more and more commonly used. Thus, our objective was a comparison of microstates analysis between dry and gel-based EEGs. 256-channel EEGs were recorded from 30 volunteers using dry and gel-based electrodes during resting state eyes closed and eyes open. Microstates were extracted for each measurement and time-domain parameters were calculated. We found a high degree of consistency between the microstate maps extracted from dry and gel-based measurements for both eyes closed and eyes open conditions. The topographic similarities between the average maps for dry and gel-based recordings were above 81.5% for each of the seven extracted maps. We conclude that topographic microstate analyses are feasible using multichannel EEG setups with new dry EEG electrodes.

Baumstark, Alexander; Paradies, Marcus; Sattler, Kai-Uwe; Kläbe, Steffen; Baumann, Stephan
So far and yet so near - accelerating distributed joins with CXL. - In: 20th International Workshop on Data Management on New Hardware (DaMoN 2024), (2024), 7, insges. 9 S.

Distributed partitioned joins are one of the most expensive operators in distributed DBMSs where a major part of the execution is attributed to network transfer costs. Although high-speed network technologies, such as RDMA, can lower this cost, they still come with significantly higher latency than local DRAM access. The emerging CXL interconnect protocol promises to provide direct and cache-coherent access to remote memory while offering byte-addressable memory access without CPU intervention. For short-distance communication in distributed DBMSs, CXL represents an interesting alternative for low-latency requirements. In this work, we explore how CXL can be leveraged for engine-internal communication and data exchange. We discuss and apply communication strategies to distributed joins. We emulate various CXL characteristics based on optimistic and pessimistic assumptions on the real performance of upcoming CXL devices and evaluate their impact on the execution of distributed joins. Our results show that CXL has the potential to improve distributed join performance.
Karbstein, Kevin; Kösters, Lara; Hodač, Ladislav; Hofmann, Martin; Hörandl, Elvira; Tomasello, Salvatore; Wagner, Natascha D.; Emerson, Brent C.; Albach, Dirk; Scheu, Stefan; Bradler, Sven; de Vries, Jan; Irisarri, Iker; Li, He; Soltis, Pamela S.; Mäder, Patrick; Wäldchen, Jana
Species delimitation 4.0: integrative taxonomy meets artificial intelligence. - In: Trends in ecology and evolution, ISSN 1872-8383, Bd. 0 (2024), 0, S. 1-14

Although species are central units for biological research, recent findings in genomics are raising awareness that what we call species can be ill-founded entities due to solely morphology-based, regional species descriptions. This particularly applies to groups characterized by intricate evolutionary processes such as hybridization, polyploidy, or asexuality. Here, challenges of current integrative taxonomy (genetics/genomics + morphology + ecology, etc.) become apparent: different favored species concepts, lack of universal characters/markers, missing appropriate analytical tools for intricate evolutionary processes, and highly subjective ranking and fusion of datasets. Now, integrative taxonomy combined with artificial intelligence under a unified species concept can enable automated feature learning and data integration, and thus reduce subjectivity in species delimitation. This approach will likely accelerate revising and unraveling eukaryotic biodiversity.
Tangalychev, Roman; Korotenko, Vasilii; Efimov, Igor; Efimov, Oleg N.
Properties of AlCl3 guanidine deep eutectic solvent with addition of polyethylene oxide of different molecular weights supported by quantum-chemical calculation. - In: Journal of energy storage, ISSN 2352-152X, Bd. 96 (2024), 112665, S. 1-8

Deep eutectic solvent of AlCl3 with guanidine HCl was synthesized in the molar ratio 3:1 in the presence of polyethylene glycols of various molecular weights from 1500 to 5&hahog;106 g/mol. Concentration of polymer was 2.5 %, 5 % and 10 %. Temperature dependence between 25 and 70 ˚C of conductivity of each electrolyte was calculated from the cyclic voltammetry of aluminum deposition-stripping measurements. It was found that conductivity increases with molecular weight of polymer in the interval between 2 and 10 kD. This result was interpreted as binding of AlCl3 guanidine to two different sites which have hydroxyl (chain ends) and ether (middle chain) oxygen with relatively higher and lower binding energy respectively. Polymer with longer chain has more low energy binding sites which causes lesser binding and consequently higher conductivity of electrolyte. B3LYP-D3 and DLPNO-CCSD(T) computations support experimental results. DES are discussed in terms of Pearson HSAB principle.