TY - JOUR A1 - Jost, Felix A1 - Kudruss, Manuel A1 - Koerkel, Stefan A1 - Walter, Sebastian F. T1 - A computational method for key-performance-indicator-based parameter identification of industrial manipulators JF - Journal of mathematics in Industry N2 - We present a novel derivative-based parameter identification method to improve the precision at the tool center point of an industrial manipulator. The tool center point is directly considered in the optimization as part of the problem formulation as a key performance indicator. Additionally, our proposed method takes collision avoidance as special nonlinear constraints into account and is therefore suitable for industrial use. The performed numerical experiments show that the optimum experimental designs considering key performance indicators during optimization achieve a significant improvement in comparison to other methods. An improvement in terms of precision at the tool center point of 40% to 44% was achieved in experiments with three KUKA robots and 90 notional manipulator models compared to the heuristic experimental designs chosen by an experimenter as well as 10% to 19% compared to an existing state-of-the-art method. KW - ACCURACY KW - collision avoidance KW - CONFIGURATIONS KW - industrial manipulators KW - key performance indicator KW - optimum experimental design KW - parameter identification KW - quantity of interest KW - ROBOT CALIBRATION Y1 - 2017 U6 - https://doi.org/10.1186/s13362-017-0039-7 VL - 7 IS - 9 PB - Springer Nature ER - TY - JOUR A1 - Raulf, Nicole A1 - Stein, Oliver T1 - A TRACE FORMULA FOR HECKE OPERATORS ON VECTOR-VALUED MODULAR FORMS JF - GLASGOW MATHEMATICAL JOURNAL N2 - We present a ready to compute trace formula for Hecke operators on vector-valued modular forms of integral weight for SL2(Z) transforming under the Weil representation. As a corollary, we obtain a ready to compute dimension formula for the corresponding space of vector-valued cusp forms, which is more general than the dimension formulae previously published in the vector-valued setting. Y1 - 2017 U6 - https://doi.org/10.1017/S0017089516000094 VL - 59 IS - 1 SP - 143 EP - 165 PB - Cambridge University Press ER - TY - JOUR A1 - Kuypers, Friedhelm A1 - Ucke, Christian T1 - Bierdeckelsalto JF - Physik in unserer Zeit N2 - Ein beliebtes Spiel besteht darin, einen auf einer Tischkante liegenden Bierdeckel von unten mit den ausgestreckten Fingern hochzuschnellen und dann nach einem oder mehreren Saltos zwischen Finger und Daumen wieder aufzufangen. Physikalisch gesehen, übt man einen Stoß auf den Bierdeckel aus. Die Anwendung von Impuls- und Drehimpulssatz führt zu einfachen Abschätzungen zur Mechanik des Bierdeckelsaltos. Mit Physik-Simulationsprogrammen lässt sich dieses Experiment nachvollziehen. Highspeed-Videos ergänzen Theorie und Simulation. Y1 - 2015 U6 - https://doi.org/10.1002/piuz.201401395 VL - 46 IS - 4 SP - 194 EP - 198 PB - Wiley ER - TY - JOUR A1 - Pereira, Clayton R. A1 - Pereira, Danilo R. A1 - Rosa, Gustavo H. A1 - Albuquerque, Victor Hugo C. A1 - Weber, Silke A. T. A1 - Hook, Christian A1 - Papa, João Paulo T1 - Handwritten dynamics assessment through convolutional neural networks BT - An application to Parkinson’s disease identification JF - Artificial Intelligence in Medicine N2 - Background and objective Parkinson’s disease (PD) is considered a degenerative disorder that affects the motor system, which may cause tremors, micrography, and the freezing of gait. Although PD is related to the lack of dopamine, the triggering process of its development is not fully understood yet. Methods In this work, we introduce convolutional neural networks to learn features from images produced by handwritten dynamics, which capture different information during the individual’s assessment. Additionally, we make available a dataset composed of images and signal-based data to foster the research related to computer-aided PD diagnosis. Results The proposed approach was compared against raw data and texture-based descriptors, showing suitable results, mainly in the context of early stage detection, with results nearly to 95%. Conclusions The analysis of handwritten dynamics using deep learning techniques showed to be useful for automatic Parkinson’s disease identification, as well as it can outperform handcrafted features. KW - Convolutional neural networks KW - Handwritten dynamics KW - Parkinson’s disease Y1 - 2018 U6 - https://doi.org/10.1016/j.artmed.2018.04.001 VL - 37 IS - May SP - 67 EP - 77 PB - Elsevier ER - TY - JOUR A1 - De, Sangita A1 - Niklas, Michael A1 - Brian, Rooney A1 - Mottok, Jürgen A1 - Brada, Premek T1 - Semantic Mapping of Component Framework Interface Ontologies for Interoperability of Vehicle Applications JF - Procedia Computer Science N2 - Over the past few years, ontology merging, and ontology semantic alignment has gained significant interest as research topics in automotive application domain for finding solutions to semantic data heterogeneity. To accomplish the complex and novel vehicle service requirements such as autonomous driving, V2X (Vehicle-to-Vehicle communication), etc. the automotive applications involve collaborations of several platform-specific data from heterogeneous enterprises component frameworks and consequently there has been increase in data interoperability issues. At the application component level, data interoperability relies on the semantic alignment or mapping between the various component framework interfaces data models represented as XML schemas (XSD). With the XML schemas being the preferred standard for the interface description exchange between most of the automotive application domain components, however, the data interoperability between the semantically equivalent but structurally different data constructs of multiple heterogeneous XSDs stands as a challenge in the absence of an ontology-based approach. To confront this crucial requirement for data interoperability and to increase in effect the reuse of existing components through their interfaces, we propose an approach to semantically map the various component framework interface data models when expressed as ontology schemas, based on the exploration of semantic synergies. The transformation between XSD and RDF (Resource Description Framework) schema representations and the use of queries over the ontology schemas for semantic mapping are demonstrated including a real-world case study. KW - component KW - interface KW - mapping KW - ontology KW - semantic Y1 - 2020 U6 - https://doi.org/10.1016/j.procs.2020.03.151 VL - 170 IS - 2 SP - 813 EP - 818 PB - Elsevier ER - TY - JOUR A1 - Herrmann, Frank A1 - Horkovics-Kovats, Robert A1 - Sultanow, Eldar T1 - Ein paralleler Algorithmus für API Mining von C# Code JF - Anwendungen und Konzepte der Wirtschaftsinformatik N2 - Die Konformitätsanalyse ist eine Technik der statischen Code-Analyse (SCA) zur Software-Qualitätssicherung. Ihr Kernproblem ist, dass Werkzeuge nicht aus bereits eingetretenen Fehlern automatisiert dazulernen. Zur Lösung wurde in dieser Arbeit das maschinelle Lernen (ML) evaluiert, indem ein wissenschaftlich fundierter und praktisch erprobter Ansatz zur unüberwachten Lerntechnik angewandt und das Ergebnis analysiert wurde. Es wurde festgestellt, dass zur Anwendung auf verschiedene Programmiersprachen nur ein sprachspezifisches API Mining-Tool notwendig ist. Ein derartiges Tool durchsucht in parallelisierter Form Codezeilen und normalisiert sie für maschinelle Lernprozesse. Dieses System wurde für die Programmiersprache C# implementiert, da viele Industrieprojekte in dieser Sprache entwickelt werden. Zur funktionalen Validierung wurde in einer Fallstudie gezeigt, dass Regeln mit einem positiven Effekt auf Software-Qualität gelernt wurden. Konkret wurde der Wartungsaufwand eines Code-Smells in einem Beispielprojekt durch das Auslagern einer gelernten Assoziation in eine gemeinsame Methode um den Faktor 30 reduziert. Die Laufzeit des Algorithmus wurde empirisch in acht open-source Repositorys evaluiert. Durch Parallelisierung kann eine durchschnittliche Laufzeitverbesserung von 45,16% erwartet werden. Allerdings wurden bei der Anwendung auch Grenzen deutlich: Viele Assoziationen sind nutzlos, die Regelbewertung ist von einem subjektiven Faktor abhängig und die Wirtschaftlichkeit des Tools ist deshalb nicht transparent. Dennoch belegt diese Arbeit, dass ein ML-basiertes SCA-Tool als ergänzende Qualitätssicherungsmaßnahme im Software-Engineering möglich ist. KW - Paralleler Algorithmus KW - API Mining KW - C# Code Y1 - 2022 U6 - https://doi.org/10.26034/lu.akwi.2022.3454 SN - 2296-4592 VL - 16 SP - 48 EP - 56 PB - Technische Hochschule Wildau ER - TY - JOUR A1 - Schildgen, Johannes T1 - Innovationen im Lernen von Java-Grundlagen JF - Java aktuell N2 - Ob in der Schule, im Studium oder Selbststudium: Die Möglichkeiten und Techniken, Java zu lernen, haben sich in den vergangenen Jahren entscheidend weiterentwickelt. Dieser Artikel gibt einen Einblick in innovative Möglichkeiten des Java-Lernens sowie einen Ausblick, der zeigt, dass sich nicht nur Programmiersprachen weiterentwickeln, sondern auch der Weg, wie wir sie lernen und lehren. Y1 - 2022 UR - https://www.doag.org/fileadmin/Daten/Zeitschriften/Java_aktuell/2022/03-2022-Java_aktuell-WEB.pdf VL - 3 SP - 47 EP - 51 PB - DOAG Dienstleistungen CY - Berlin ER - TY - JOUR A1 - Höschl, Michael A1 - Huiber, Patrick A1 - Korn, Robert T1 - Produktentwicklung für die hybride Zusammenarbeit: Studierende geben Input für digitale und hybride Beratungsprodukte JF - Projekt-Management aktuell N2 - Praxisprojekte in Zusammenarbeit mit externen Auftraggebern erfreuen sich in der Projektmanagementlehre zunehmender Beliebtheit - Learning by Doing. Die digitale Lehre eröffnet hier Chancen: Sie ermöglicht z. B. eine Zusammenarbeit über größere Distanzen und dient dem Ideen- und Erfahrungstransfer aus der online-Lehre in die Geschäftswelt. Die spezifischen Erfahrungen aus der Perspektive der OTH Regensburg sowie der des Auftraggebers, der Unternehmensberatung fifty1 aus Wien, werden vorgestellt. Studierende erarbeiteten Ideen für digitale Beratungsprodukte, die zu marktfähigen Angeboten des Auftraggebers weiterentwickelt werden. KW - Agilität KW - Blended Learning KW - Coaching KW - Design Thinking KW - Digiloges Arbeiten KW - digitale Zusammenarbeit KW - Digitalisierung KW - externe Auftraggeber KW - hybride Arbeitsformen KW - Kollaborationstools KW - Kreativitätstechnik KW - Online-Lehre KW - Scrum KW - Studierenden-Projekte KW - Unternehmensberatung Y1 - 2021 U6 - https://doi.org/10.24053/PM-2021-0092 VL - 32 IS - 5 SP - 41 EP - 45 PB - UVK Verlag CY - Tübingen ER - TY - JOUR A1 - Selgrad, Kai A1 - Lier, Alexander A1 - Martinek, Magdalena A1 - Buchenau, Christoph A1 - Guthe, Michael A1 - Kranz, Franziska A1 - Schäfer, Henry A1 - Stamminger, Marc T1 - A Compressed Representation for Ray Tracing Parametric Surfaces JF - ACM Transactions on Graphics N2 - Parametric surfaces are an essential modeling tool in computer aided design and movie production. Even though their use is well established in industry, generating ray-traced images adds significant cost in time and memory consumption. Ray tracing such surfaces is usually accomplished by subdividing the surfaces on-the-fly, or by conversion to a polygonal representation. However, on-the-fly subdivision is computationally very expensive, whereas polygonal meshes require large amounts of memory. This is a particular problem for parametric surfaces with displacement, where very fine tessellation is required to faithfully represent the shape. Hence, memory restrictions are the major challenge in production rendering. In this paper, we present a novel solution to this problem. We propose a compression scheme for a-priori Bounding Volume Hierarchies (BVHs) on parametric patches, that reduces the data required for the hierarchy by a factor of up to 48. We further propose an approximate evaluation method that does not require leaf geometry, yielding an overall reduction of memory consumption by a factor of 60 over regular BVHs on indexed face sets and by a factor of 16 over established state-of-the-art compression schemes. Alternatively, our compression can simply be applied to a standard BVH while keeping the leaf geometry, resulting in a compression rate of up to 2:1 over current methods. Although decompression generates additional costs during traversal, we can manage very complex scenes even on the memory restrictive GPU at competitive render times. KW - Production Rendering KW - Subdivision Surfaces KW - Displacement Mapping KW - Ray Tracing Y1 - 2016 U6 - https://doi.org/10.1145/2953877 VL - 36 IS - 1 SP - 1 EP - 13 PB - ACM CY - New York, NY, USA ER - TY - JOUR A1 - Franke, Linus A1 - Fink, Laura A1 - Martschinke, Jana A1 - Selgrad, Kai A1 - Stamminger, Marc T1 - Time-Warped Foveated Rendering for Virtual Reality Headsets JF - Computer Graphics Forum N2 - Rendering in real time for virtual reality headsets with high user immersion is challenging due to strict framerate constraints as well as due to a low tolerance for artefacts. Eye tracking-based foveated rendering presents an opportunity to strongly increase performance without loss of perceived visual quality. To this end, we propose a novel foveated rendering method for virtual reality headsets with integrated eye tracking hardware. Our method comprises recycling pixels in the periphery by spatio-temporally reprojecting them from previous frames. Artefacts and disocclusions caused by this reprojection are detected and re-evaluated according to a confidence value that is determined by a newly introduced formalized perception-based metric, referred to as confidence function. The foveal region, as well as areas with low confidence values, are redrawn efficiently, as the confidence value allows for the delicate regulation of hierarchical geometry and pixel culling. Hence, the average primitive processing and shading costs are lowered dramatically. Evaluated against regular rendering as well as established foveated rendering methods, our approach shows increased performance in both cases. Furthermore, our method is not restricted to static scenes and provides an acceleration structure for post-processing passes. KW - immersive VR KW - perceptually based rendering KW - real-time rendering KW - rendering KW - virtual environments Y1 - 2021 U6 - https://doi.org/10.1111/cgf.14176 VL - 40 IS - 1 SP - 110 EP - 123 PB - Wiley ER - TY - JOUR A1 - Selgrad, Kai A1 - Dachsbacher, C. A1 - Meyer, Q. A1 - Stamminger, M. T1 - Filtering Multi-Layer Shadow Maps for Accurate Soft Shadows JF - Computer Graphics Forum N2 - In this paper, we introduce a novel technique for pre-filtering multi-layer shadow maps. The occluders in the scene are stored as variable-length lists of fragments for each texel. We show how this representation can be filtered by progressively merging these lists. In contrast to previous pre-filtering techniques, our method better captures the distribution of depth values, resulting in a much higher shadow quality for overlapping occluders and occluders with different depths. The pre-filtered maps are generated and evaluated directly on the GPU, and provide efficient queries for shadow tests with arbitrary filter sizes. Accurate soft shadows are rendered in real-time even for complex scenes and difficult setups. Our results demonstrate that our pre-filtered maps are general and particularly scalable. Y1 - 2015 U6 - https://doi.org/10.1111/cgf.12506 VL - 34 IS - 1 SP - 205 EP - 215 PB - Wiley ER - TY - JOUR A1 - Mauerer, Wolfgang A1 - Scherzinger, Stefanie T1 - Digitale Forschungswerkzeuge : Nachhaltigkeit für Software und Daten JF - Forschung & Lehre (Forschung und Lehre) N2 - Die wissenschaftliche Reproduktionskrise hat den Blick auf digitale Forschungswerkzeuge intensiviert. Auch wenn der Mehraufwand für Reproduzierbarkeit und Zugänglichkeit zunehmend anerkannt wird, existieren noch Defizite in der Umsetzung, wenn es darum geht, die Datenbasis und Forschungswerkzeuge verfügbar zu machen Y1 - 2021 UR - https://www.wissenschaftsmanagement-online.de/system/files/downloads-wimoarticle/2021-10_WIMO_Digitale_Forschungswerkzeuge_Mauerer_Scherzinger.pdf VL - 28 IS - 10 SP - 816 EP - 817 PB - Zentrum für Wissenschaftsmanagement e.V. (ZWM)
 ER - TY - JOUR A1 - Bayerstadler, Andreas A1 - Becquin, Guillaume A1 - Binder, Julia A1 - Botter, Thierry A1 - Ehm, Hans A1 - Ehmer, Thomas A1 - Erdmann, Marvin A1 - Gaus, Norbert A1 - Harbach, Philipp A1 - Hess, Maximilian A1 - Klepsch, Johannes A1 - Leib, Martin A1 - Luber, Sebastian A1 - Luckow, Andre A1 - Mansky, Maximilian A1 - Mauerer, Wolfgang A1 - Neukart, Florian A1 - Niedermeier, Christoph A1 - Palackal, Lilly A1 - Pfeiffer, Ruben A1 - Polenz, Carsten A1 - Sepulveda, Johanna A1 - Sievers, Tammo A1 - Standen, Brian A1 - Streif, Michael A1 - Strohm, Thomas A1 - Utschig-Utschig, Clemens A1 - Volz, Daniel A1 - Weiss, Horst A1 - Winter, Fabian T1 - Industry quantum computing applications JF - EPJ Quantum Technology N2 - Quantum computing promises to overcome computational limitations with better and faster solutions for optimization, simulation, and machine learning problems. Europe and Germany are in the process of successfully establishing research and funding programs with the objective to dvance the technology’s ecosystem and industrialization, thereby ensuring digital sovereignty, security, and competitiveness. Such an ecosystem comprises hardware/software solution providers, system integrators, and users from research institutions, start-ups, and industry. The vision of the Quantum Technology and Application Consortium (QUTAC) is to establish and advance the quantum computing ecosystem, supporting the ambitious goals of the German government and various research programs. QUTAC is comprised of ten members representing different industries, in particular automotive manufacturing, chemical and pharmaceutical production, insurance, and technology. In this paper, we survey the current state of quantum computing in these sectors as well as the aerospace industry and identify the contributions of QUTAC to the ecosystem. We propose an application-centric approach for the industrialization of the technology based on proven business impact. This paper identifies 24 different use cases. By formalizing high-value use cases into well-described reference problems and benchmarks, we will guide technological progress and eventually commercialization. Our results will be beneficial to all ecosystem participants, including suppliers, system integrators, software developers, users, policymakers, funding program managers, and investors. KW - Benchmarks KW - Industry application KW - Quantum computing KW - QUTAC KW - Reference problems Y1 - 2021 U6 - https://doi.org/10.1140/epjqt/s40507-021-00114-x VL - 8 SP - 1 EP - 17 PB - Springer ER - TY - JOUR A1 - Christ, Andreas A1 - Brecht, Benjamin A1 - Mauerer, Wolfgang A1 - Silberhorn, Christine T1 - Theory of quantum frequency conversion and type-II parametric down-conversion in the high-gain regime JF - New Journal of Physics N2 - Frequency conversion (FC) and type-II parametric down-conversion (PDC) processes serve as basic building blocks for the implementation of quantum optical experiments: type-II PDC enables the efficient creation of quantum states such as photon-number states and Einstein–Podolsky–Rosen (EPR)-states. FC gives rise to technologies enabling efficient atom–photon coupling, ultrafast pulse gates and enhanced detection schemes. However, despite their widespread deployment, their theoretical treatment remains challenging. Especially the multi-photon components in the high-gain regime as well as the explicit time-dependence of the involved Hamiltonians hamper an efficient theoretical description of these nonlinear optical processes. In this paper, we investigate these effects and put forward two models that enable a full description of FC and type-II PDC in the high-gain regime. We present a rigorous numerical model relying on the solution of coupled integro-differential equations that covers the complete dynamics of the process. As an alternative, we develop a simplified model that, at the expense of neglecting time-ordering effects, enables an analytical solution. While the simplified model approximates the correct solution with high fidelity in a broad parameter range, sufficient for many experimental situations, such as FC with low efficiency, entangled photon-pair generation and the heralding of single photons from type-II PDC, our investigations reveal that the rigorous model predicts a decreased performance for FC processes in quantum pulse gate applications and an enhanced EPR-state generation rate during type-II PDC, when EPR squeezing values above 12 dB are considered. Y1 - 2013 U6 - https://doi.org/10.1088/1367-2630/15/5/053038 VL - 15 IS - 5 PB - IOP ER - TY - JOUR A1 - Gabriel, Christian A1 - Wittmann, Christoffer A1 - Sych, Denis A1 - Dong, Ruifang A1 - Mauerer, Wolfgang A1 - Andersen, Ulrik L. A1 - Marquardt, Christoph A1 - Leuchs, Gerd T1 - A generator for unique quantum random numbers based on vacuum states JF - Nature Photonics N2 - Random numbers are a valuable component in diverse applications that range from simulations over gambling to cryptography. The quest for true randomness in these applications has engendered a large variety of different proposals for producing random numbers based on the foundational unpredictability of quantum mechanics4,5,6,7,8,9,10,11. However, most approaches do not consider that a potential adversary could have knowledge about the generated numbers, so the numbers are not verifiably random and unique12,13,14,15. Here we present a simple experimental setup based on homodyne measurements that uses the purity of a continuous-variable quantum vacuum state to generate unique random numbers. We use the intrinsic randomness in measuring the quadratures of a mode in the lowest energy vacuum state, which cannot be correlated to any other state. The simplicity of our source, combined with its verifiably unique randomness, are important attributes for achieving high-reliability, high-speed and low-cost quantum random number generators. Y1 - 2010 U6 - https://doi.org/10.1038/nphoton.2010.197 VL - 4 IS - 10 SP - 711 EP - 715 PB - Springer ER - TY - JOUR A1 - Mauerer, Wolfgang A1 - Jaeger, Michael C. T1 - Open Source Engineering Processes JF - it - Information Technology N2 - Software engineering in open source projectsfaces similar challenges as in traditional software development(coordination of and cooperation between contributors, changeand release management, quality assurance, . . .), but often usesdifferent means of solving them. This leads to some salientdistinctions between both worlds, especially with respect tocommunication and how technical issues are addressed. Thevariations within open source software (OSS) communities areconsiderable, and many different approaches are currently inuse, ranging from informal conventions to highly systematic,formally specified and rigidly applied processes. We discussthe archetypal best practises in the field, illustrate them bypresenting example projects, and provide a comparison to tradi-tional approaches. T2 - Open Source-Entwicklungsprozesse KW - Open-Source-Softwaretechnik KW - Softwareentwicklungsprozesse KW - Softwarereleases KW - Linux Y1 - 2013 U6 - https://doi.org/10.1515/itit.2013.1008 VL - 55 IS - 5 SP - 196 EP - 203 PB - de Gruyter ER - TY - JOUR A1 - Coldenstrodt-Ronge, Hendrik B. A1 - Lundeen, Jeff S. A1 - Pregnell, Kenny L. A1 - Feito, Alvaro A1 - Smith, Brian J. A1 - Mauerer, Wolfgang A1 - Silberhorn, Christine A1 - Eisert, Jens A1 - Plenio, Martin B. A1 - Walmsley, Ian A. T1 - A proposed testbed for detector tomography JF - Journal of Modern Optics N2 - Measurement is the only part of a general quantum system that has yet to be characterised experimentally in a complete manner. Detector tomography provides a procedure for doing just this; an arbitrary measurement device can be fully characterised, and thus calibrated, in a systematic way without access to its components or its design. The result is a reconstructed POVM containing the measurement operators associated with each measurement outcome. We consider two detectors, a single-photon detector and a photon-number counter, and propose an easily realised experimental apparatus to perform detector tomography on them. We also present a method of visualising the resulting measurement operators. Y1 - 2009 U6 - https://doi.org/10.1080/09500340802304929 VL - 56 IS - 2-3 SP - 432 EP - 441 PB - Taylor&Francis ER - TY - JOUR A1 - Mauerer, Wolfgang A1 - Avenhaus, Malte A1 - Helwig, Wolfram A1 - Silberhorn, Christine T1 - How colors influence numbers: Photon statistics of parametric down-conversion JF - Physical Review A (Phys. Rev. A) N2 - Parametric down-conversion (PDC) is a technique of ubiquitous experimental significance in the production of nonclassical, photon-number-correlated twin beams. Standard theory of PDC as a two-mode squeezing process predicts and homodyne measurements observe a thermal photon number distribution per beam. Recent experiments have obtained conflicting distributions. In this article, we explain the observation by an a priori theoretical model solely based on directly accessible physical quantities. We compare our predictions with experimental data and find excellent agreement. Y1 - 2009 U6 - https://doi.org/10.1103/physreva.80.053815 VL - 80 IS - 5 PB - American Physical Society ER - TY - JOUR A1 - Mauerer, Wolfgang A1 - Sawallisch, J. A1 - Hillier, G. A1 - Oberthür, S. A1 - Hönick, S. T1 - Real-Time Android: Achieving determinism and ease of use JF - Embedded Wold Conference; Nuremberg, Germany, February 25, 2014 - February 27, 2014 Y1 - 2014 UR - http://www.linuxtag.org/2012/fileadmin/www.linuxtag.org/slides/Gernot%20Hillier%20+%20Wolfgang%20Mauerer%20+%20Jan%20Sawallisch%20-%20Android_%20real-time%20for%20the%20rest%20of%20us.p416.pdf SP - 1 EP - 7 ER - TY - JOUR A1 - Rohde, Peter P. A1 - Mauerer, Wolfgang A1 - Silberhorn, Christine T1 - Spectral structure and decompositions of optical states, and their applications JF - New Journal of Physics N2 - We discuss the spectral structure and decomposition of multi-photon states. Ordinarily 'multi-photon states' and 'Fock states' are regarded as synonymous. However, when the spectral degrees of freedom are included this is not the case, and the class of 'multi-photon' states is much broader than the class of 'Fock' states. We discuss the criteria for a state to be considered a Fock state. We then address the decomposition of general multi-photon states into bases of orthogonal eigenmodes, building on existing multi-mode theory, and introduce an occupation number representation that provides an elegant description of such states. This representation allows us to work in bases imposed by experimental constraints, simplifying calculations in many situations. Finally we apply this technique to several example situations, which are highly relevant for state of the art experiments. These include Hong–Ou–Mandel interference, spectral filtering, finite bandwidth photo-detection, homodyne detection and the conditional preparation of Schrödinger kitten and Fock states. Our techniques allow for very simple descriptions of each of these examples. Y1 - 2007 U6 - https://doi.org/10.1088/1367-2630/9/4/091 VL - 9 IS - 4 PB - IOP Publishing ER - TY - JOUR A1 - Helwig, Wolfram A1 - Mauerer, Wolfgang A1 - Silberhorn, Christine T1 - Multimode states in decoy-based quantum-key-distribution protocols JF - Physical Review A N2 - Every security analysis of quantum-key distribution (QKD) relies on a faithful modeling of the employed quantum states. Many photon sources, such as for instance a parametric down-conversion (PDC) source, require a multimode description but are usually only considered in a single-mode representation. In general, the important claim in decoy-based QKD protocols for indistinguishability between signal and decoy states does not hold for all sources. We derive bounds on the single-photon transmission probability and error rate for multimode states and apply these bounds to the output state of a PDC source. We observe two opposing effects on the secure key rate. First, the multimode structure of the state gives rise to a new attack that decreases the key rate. Second, more contributing modes change the photon number distribution from a thermal toward a Poissonian distribution, which increases the key rate. Y1 - 2009 U6 - https://doi.org/10.1103/physreva.80.052326 VL - 80 IS - 5 PB - American Physical Society ER - TY - JOUR A1 - Mauerer, Wolfgang A1 - Helwig, Wolfram A1 - Silberhorn, Christine T1 - Recent developments in quantum key distribution: Theory and practice JF - Annalen der Physik N2 - Quantum key distribution is among the foremost applications of quantum mechanics, both in terms of fundamental physics and as a technology on the brink of commercial deployment. Starting from principal schemes and initial proofs of unconditional security for perfect systems, much effort has gone into providing secure schemes which can cope with numerous experimental imperfections unavoidable in real world implementations. In this paper, we provide a comparison of various schemes and protocols. We analyse their efficiency and performance when implemented with imperfect physical components. We consider how experimental faults are accounted for using effective parameters. We compare various recent protocols and provide guidelines as to which components propose best advances when being improved. KW - experimental imperfections KW - quantum communication KW - Quantum cryptography Y1 - 2008 U6 - https://doi.org/10.1002/andp.200710284 VL - 17 IS - 2-3 SP - 158 EP - 175 PB - Wiley ER - TY - JOUR A1 - Avenhaus, Malte A1 - Coldenstrodt-Ronge, Hendrik B. A1 - Laiho, K. A1 - Mauerer, Wolfgang A1 - Walmsley, I. A. A1 - Silberhorn, Christine T1 - Photon Number Statistics of Multimode Parametric Down-Conversion JF - Physical Review Letters N2 - We experimentally analyze the complete photon number statistics of parametric down-conversion and ascertain the influence of multimode effects. Our results clearly reveal a difference between single-mode theoretical description and the measured distributions. Further investigations assure the applicability of loss-tolerant photon number reconstruction and prove strict photon number correlation between signal and idler modes. Y1 - 2008 U6 - https://doi.org/10.1103/physrevlett.101.053601 VL - 101 IS - 5 PB - American Physical Society ER - TY - JOUR A1 - Mauerer, Wolfgang A1 - Silberhorn, Christine T1 - Quantum key distribution with passive decoy state selection JF - Physical Review A N2 - We propose a quantum key distribution scheme which closely matches the performance of a perfect single photon source. It nearly attains the physical upper bound in terms of key generation rate and maximally achievable distance. Our scheme relies on a practical setup based on a parametric downconversion source and present day, nonideal photon-number detection. Arbitrary experimental imperfections which lead to bit errors are included. We select decoy states by classical postprocessing. This allows one to improve the effective signal statistics and achievable distance. Y1 - 2007 U6 - https://doi.org/10.1103/physreva.75.050305 VL - 75 IS - 5 PB - American Physical Society ER - TY - JOUR A1 - Mauerer, Wolfgang T1 - Datenvisualisierung mit Ggplot2 JF - Linux-Magazin N2 - Wer seine Daten mit ansehnlichen und informativen Graphen veranschaulichen möchte, braucht meist viel Geduld. Die R-Erweiterung Ggplot2 bringt System in die Grafik, drückt sich in knappem Quellcode aus und bläst frischen Wind in den Alltag der Datenvisualisierung. Y1 - 2012 UR - www.linux-magazin.de/Heft-Abo/Ausgaben/2012/03/Ggplot2 IS - 3 PB - Linux New Media AG ER - TY - JOUR A1 - Mauerer, Wolfgang T1 - Gimp-Perl: Gimp scripting for the rest of us JF - Linux Gazette Y1 - 2000 UR - https://linuxgazette.net/issue51/mauerer.html SN - 1934-371X IS - 51 ER - TY - JOUR A1 - Feld, Sebastian A1 - Roch, Christoph A1 - Gabor, Thomas A1 - Seidel, Christian A1 - Neukart, Florian A1 - Galter, Isabella A1 - Mauerer, Wolfgang A1 - Linnhoff-Popien, Claudia T1 - A Hybrid Solution Method for the Capacitated Vehicle Routing Problem Using a Quantum Annealer JF - Frontiers in ICT N2 - he Capacitated Vehicle Routing Problem (CVRP) is an NP-optimization problem (NPO) that has been of great interest for decades for both, science and industry. The CVRP is a variant of the vehicle routing problem characterized by capacity constrained vehicles. The aim is to plan tours for vehicles to supply a given number of customers as efficiently as possible. The problem is the combinatorial explosion of possible solutions, which increases superexponentially with the number of customers. Classical solutions provide good approximations to the globally optimal solution. D-Wave's quantum annealer is a machine designed to solve optimization problems. This machine uses quantum effects to speed up computation time compared to classic computers. The problem on solving the CVRP on the quantum annealer is the particular formulation of the optimization problem. For this, it has to be mapped onto a quadratic unconstrained binary optimization (QUBO) problem. Complex optimization problems such as the CVRP can be translated to smaller subproblems and thus enable a sequential solution of the partitioned problem. This work presents a quantum-classic hybrid solution method for the CVRP. It clarifies whether the implementation of such a method pays off in comparison to existing classical solution methods regarding computation time and solution quality. Several approaches to solving the CVRP are elaborated, the arising problems are discussed, and the results are evaluated in terms of solution quality and computation time. Y1 - 2019 U6 - https://doi.org/10.3389/fict.2019.00013 VL - 6 SP - 1 EP - 13 PB - Frontiers ER - TY - JOUR A1 - Niedersteiner, Sascha A1 - Lang, Jonas A1 - Pohlt, Clemens A1 - Schlegl, Thomas T1 - Klassifikation des Arbeitsfortschritts BT - Support-Vector-Machine-Ansatz für intelligente Arbeitsplätze JF - atp magazin N2 - Steigende Anforderungen an die Qualität von zum Teil manuell gefertigten Produkten führen dazu, dass Handarbeitsplätze mit Assistenzsystemen für die Unterstützung der am Arbeitsplatz arbeitenden Mitarbeiterinnen und Mitarbeiter ausgestattet werden. Der Beitrag beschreibt einen neuen Ansatz, um mittels Verfahren des maschinellen Lernens die Objekterkennung sowie die Transitionen eines, den Arbeitsprozess repräsentierenden Zustandsautomaten eines solchen Systems einzulernen. Hierfür werden nach einer Vorverarbeitung Daten aus einer Tiefenkamera in drei Stufen durch Support Vector Machines (SVM) klassifiziert und das Ergebnis mit dem Zustandsautomaten verknüpft. Das Konzept wird an einem industriellen Montageprozess überschaubarer Komplexität evaluiert; es zeigt gute Ergebnisse hinsichtlich der Robustheit gegenüber Fehlern bei der Objektklassifikation. KW - assistierender Arbeitsplatz KW - Maschinelles Lernen KW - Mensch-Maschine-Interaktion KW - robuste Erkennung des Arbeitsfortschritts KW - Tiefenkamera Y1 - 2017 U6 - https://doi.org/10.17560/atp.v59i11.1911 VL - 59 IS - 11 SP - 58 EP - 66 PB - Vulkan-Verlag ER - TY - JOUR A1 - Niedersteiner, Sascha A1 - Lang, Jonas A1 - Pohlt, Clemens A1 - Schlegl, Thomas T1 - Tracking work task completion - A support vector machine approach for assisting workbenches JF - atp edition N2 - Tightening quality requirements of industrial products involving manual assembly lead to the development of assisting workbenches with integrated functions to support workers performing these manual tasks. This contribution discusses a new approach to learning transitions of a finite state automaton representing the sequence of work tasks based on the video stream of a 3D depth camera. Preprocessed video data is fed into a three-stage classification scheme based on support vector machines. The results of the classification are then related to the state automation to trigger state transitions indicating the completion of a specific work task and the start of the next one. The proposed approach has been evaluated at an industrial assembly process of moderate complexity and shows very robust results with respect to disturbances caused by inaccurate object classification. N2 - Steigende Anforderungen an die Qualität von zum Teil manuell gefertigten Produkten führen dazu, dass Handarbeitsplätze mit Assistenzsystemen für die Unterstützung der am Arbeitsplatz arbeitenden Mitarbeiterinnen und Mitarbeiter ausgestattet werden. Der Beitrag beschreibt einen neuen Ansatz, um mittels Verfahren des maschinellen Lernens die Objekterkennung sowie die Transitionen eines, den Arbeitsprozess repräsentierenden Zustandsautomaten eines solchen Systems einzulernen. Hierfür werden nach einer Vorverarbeitung Daten aus einer Tiefenkamera in drei Stufen durch Support Vector Machines (SVM) klassifiziert und das Ergebnis mit dem Zustandsautomaten verknüpft. Das Konzept wird an einem industriellen Montageprozess überschaubarer Komplexität evaluiert; es zeigt gute Ergebnisse hinsichtlich der Robustheit gegenüber Fehlern bei der Objektklassifikation. T2 - Klassifikation des Arbeitsfortschritts - Support-Vector-Machine-Ansatz für intelligente Arbeitsplätze KW - 3D depth camera KW - assisting workbench KW - human-machine interaction KW - Machine learning KW - robust tracking of task completion KW - SYSTEM Y1 - 2017 U6 - https://doi.org/10.17560/atp.v59i11.1911 IS - 11 SP - 58 EP - 66 PB - DIV Deutscher Industrieverl. ER - TY - JOUR A1 - Jain, Brijnesh T1 - Revisiting inaccuracies of time series averaging under dynamic time warping JF - Pattern Recognition Letters N2 - This article revisits an analysis on (in)accuracies of time series averaging under dynamic time warping (dtw) conducted by Niennattrakul and Ratanamahatana [16]. They proposed a correctness-criterion for dtw-averages and postulated that dtw-averages can drift out of the cluster of time series to be averaged. They claimed that dtw-averages are inaccurate if they violate the correctness-criterion or suffer from the drift-out phenomenon. Furthermore, they conjectured that such inaccuracies are caused by the lack of triangle inequality. In this article, we show that a rectified version of the correctness-criterion is unsatisfiable and that the concept of drift-out is geometrically and operationally inconclusive. Satisfying the triangle inequality is insufficient to achieve correctness and unnecessary to overcome the drift-out phenomenon. We place the concept of drift-out on a principled basis and show that Fréchet means never drift out. The adjusted drift-out is a way to test to which extent an approximated dtw-average is coherent. Empirical results show that approximations obtained by the state-of-the-art averaging methods are incoherent in over a third of all cases. KW - k-means KW - Time series averaging KW - Dynamic time warping KW - Time series Y1 - 2019 U6 - https://doi.org/10.1016/j.patrec.2019.05.022 VL - 125 IS - July SP - 418 EP - 424 PB - Elsevier ER - TY - JOUR A1 - Jain, Brijnesh T1 - Making the dynamic time warping distance warping-invariant JF - Pattern Recognition N2 - The literature postulates that the dynamic time warping (dtw) distance can cope with temporal variations but stores and processes time series in a form as if the dtw-distance cannot cope with such variations. To address this inconsistency, we first show that the dtw-distance is not warping-invariant—despite its name and contrary to its characterization in some publications. The lack of warping-invariance contributes to the inconsistency mentioned above and to a strange behavior. To eliminate these peculiarities, we convert the dtw-distance to a warping-invariant semi-metric, called time-warp-invariant (twi) distance. Empirical results suggest that the error rates of the twi and dtw nearest-neighbor classifier are practically equivalent in a Bayesian sense. However, the twi-distance requires less storage and computation time than the dtw-distance for a broad range of problems. These results challenge the current practice of applying the dtw-distance in nearest-neighbor classification and suggest the proposed twi-distance as a more efficient and consistent option. KW - Nearest-neighbor rule KW - Dynamic time warping KW - Time series KW - Semi-metric Y1 - 2019 U6 - https://doi.org/10.1016/j.patcog.2019.05.016 VL - 94 IS - October SP - 35 EP - 52 PB - Elsevier ER - TY - JOUR A1 - Kucera, Markus T1 - On end-to-end safety for mobile COTS devices JF - Advances in Computer Science : an International Journal N2 - Today, ubiquitous mobile devices have not only arrived but entered the safety critical domain. There, systems are about to be controlled where human health or even human life is put at risk. For example, in automation systems first ideas surface to control parts of the system via a COTS smartphone. Another example is the idea to control the autonomous parking function of a car via a COTS smartphone too. As beneficial and convenient these ideas are on the first thought, on the second thought, dangers of these approaches become obvious. Especially in case of failures the system’s safety has to be maintained. The open question is how to achieve this mandatory requirement with COTS components, e.g. smartphones that are not developed following the development process necessary for safetycritical systems. This paper presents a concept to reliably detect human interaction while activating safety critical functions via COTS mobile devices. Thus a means is provided to detect erroneous activation requests for the safetycritical function. KW - Safety KW - Smartphone KW - Automotive KW - Control Y1 - 2015 UR - http://www.acsij.org/acsij/article/view/64 SN - 2322-5157 VL - 4 IS - 5 SP - 107 EP - 109 PB - ACSIJ ER - TY - JOUR A1 - De, Sangita A1 - Brada, Premek A1 - Mottok, Jürgen A1 - Niklas, Michael T1 - The Empirical Evaluation of Semantic Alignment Quality Metrics for Vehicle Domain Component Frameworks Interface Ontologies JF - FLAIRS 2021 : The 34th International FLAIRS Conference. Proceedings N2 - Semantic alignment of application software components’ ontologies represents a great interest in vehicle application domains that manipulate heterogeneous overlapping knowledge application frameworks. In the past few years, with the growth in the novel vehicle service requirements such as autonomous driving, V2X (Vehicle-to-Vehicle communication) and many others, automotive application software component models are becoming increasingly collaborative with other qualified cross-enterprise industrial partners to accomplish these complex service requirements. The most daunting impediment to this cross-enterprise collaboration is semantic interoperability. For efficient services collaboration through cross-enterprise semantic interoperability between the vehicle application frameworks’ software components, aligning the interface ontologies of these components by identifying the depth of semantic alignment relationships between the concepts of the interface ontologies is the major focus of this paper. In contrast to several existing ontology structural metrics, this work defines, evaluates and validates ontology metrics to measure the depth of semantic alignment between the vehicle domain software component frameworks’ interface ontological models. To emphasize the substantial role of semantic alignment of software component frameworks’ interface ontologies in semantic interoperability, a typical vehicle domain case study involving vehicle applications is considered for demonstration. Y1 - 2021 U6 - https://doi.org/10.32473/flairs.v34i1.128512 VL - 34 IS - 1 PB - LibraryPress@UF ER - TY - JOUR A1 - Schmid, Michael A1 - Fritz, Florian A1 - Mottok, Jürgen T1 - Fine-grained parallelism framework with predictable work-stealing for real-time multiprocessor systems JF - Journal of Systems Architecture N2 - Lately, parallel task models have received much attention in the development of real-time multiprocessor systems, as they allow highly compute-intensive tasks to have shorter deadlines which is very much required in modern reactive systems. However, missing modularity and portability can make parallel programming a cumbersome endeavor. As a consequence, compute-intensive sectors in the desktop and server segment have relied on parallelism frameworks such as Intel Threading Building Blocks, Cilk and OpenMP. These parallelism frameworks, however, are optimized for decent average case performance and consequently, do not meet the strict requirements imposed by real-time systems. In this paper, we present a proof-of-concept parallelism framework which was implemented in particular for soft real-time systems and having tight timing and safety requirements of such critical systems in mind. The proposed runtime system implements static memory allocation in a work-stealing environment that conforms to the strict space and tight probabilistic time bounds of work-stealing schedulers. Furthermore, we evaluate the performance of this framework by conducting multiprogrammed benchmarks on a real-time embedded multicore architecture. Y1 - 2022 U6 - https://doi.org/10.1016/j.sysarc.2022.102393 N1 - Corrigendum: https://www.sciencedirect.com/science/article/pii/S1383762123000528?via%3Dihub VL - 124 IS - March PB - Elsevier ER - TY - JOUR A1 - Haertl, Petra Maria A1 - Löschel, Rainer A1 - Repp, Natalia A1 - Pohl, Fabian A1 - Kölbl, Oliver A1 - Dobler, Barbara T1 - Frameless fractionated stereotactic radiation therapy of intracranial lesions: Impact of cone beam CT based setup correction on dose distribution JF - Radiation Oncology N2 - Background The purpose of this study was to evaluate the impact of Cone Beam CT (CBCT) based setup correction on total dose distributions in fractionated frameless stereotactic radiation therapy of intracranial lesions. Methods Ten patients with intracranial lesions treated with 30 Gy in 6 fractions were included in this study. Treatment planning was performed with Oncentra® for a SynergyS® (Elekta Ltd, Crawley, UK) linear accelerator with XVI® Cone Beam CT, and HexaPOD™ couch top. Patients were immobilized by thermoplastic masks (BrainLab, Reuther). After initial patient setup with respect to lasers, a CBCT study was acquired and registered to the planning CT (PL-CT) study. Patient positioning was corrected according to the correction values (translational, rotational) calculated by the XVI® system. Afterwards a second CBCT study was acquired and registered to the PL-CT to confirm the accuracy of the corrections. An in-house developed software was used for rigid transformation of the PL-CT to the CBCT geometry, and dose calculations for each fraction were performed on the transformed CT. The total dose distribution was achieved by back-transformation and summation of the dose distributions of each fraction. Dose distributions based on PL-CT, CBCT (laser set-up), and final CBCT were compared to assess the influence of setup inaccuracies. Results The mean displacement vector, calculated over all treatments, was reduced from (4.3 ± 1.3) mm for laser based setup to (0.5 ± 0.2) mm if CBCT corrections were applied. The mean rotational errors around the medial-lateral, superior-inferior, anterior-posterior axis were reduced from (−0.1 ± 1.4)°, (0.1 ± 1.2)° and (−0.2 ± 1.0)°, to (0.04 ± 0.4)°, (0.01 ± 0.4)° and (0.02 ± 0.3)°. As a consequence the mean deviation between planned and delivered dose in the planning target volume (PTV) could be reduced from 12.3% to 0.4% for D95 and from 5.9% to 0.1% for Dav. Maximum deviation was reduced from 31.8% to 0.8% for D95, and from 20.4% to 0.1% for Dav. Conclusion Real dose distributions differ substantially from planned dose distributions, if setup is performed according to lasers only. Thermoplasic masks combined with a daily CBCT enabled a sufficient accuracy in dose distribution. KW - CBCT KW - Setup error KW - Reproducibility KW - Daily dose distribution KW - Cumulative dose distribution KW - Actual dose distribution KW - Intracranial lesions Y1 - 2013 U6 - https://doi.org/10.1186/1748-717X-8-153 VL - 8 IS - 1 PB - BioMed Central CY - London ER - TY - JOUR A1 - Lukovszki, Tamas A1 - Schindelhauer, Christian A1 - Volbert, Klaus T1 - Resource efficient maintenance of wireless network topologies JF - Journal of Universal Computer Science N2 - Multiple hop routing in mobile ad hoc networks can minimize energy consumption and increase data throughput. Yet, the problem of radio interferences remain. However if the routes are restricted to a basic network based on local neighborhoods, these interferences can be reduced such that standard routing algorithms can be applied. We compare different network topologies for these basic networks, i.e. the Yao-graph (aka. Θ-graph) and some also known related models, which will be called the SymmYgraph (aka. YS-graph), the SparsY-graph (aka. YY-graph) and the BoundY-graph. Further, we present a promising network topology called the HL-graph (based on Hierarchical Layers). We compare these topologies regarding degree, spanner-properties, and communication features. We investigate how these network topologies bound the number of (uni- and bidirectional) interferences and whether these basic networks provide energy-optimal or congestion-minimal routing. Then, we compare the ability of these topologies to handle dynamic changes of the network when radio stations appear and disappear. For this we measure the number of involved radio stations and present distributed algorithms for repairing the network structure. KW - ad hoc networks KW - topology control KW - distributed algorithms Y1 - 2006 U6 - https://doi.org/10.3217/jucs-012-09-1292 VL - 12 IS - 9 SP - 1292 EP - 1311 PB - Verlag der Technischen Universität Graz ER - TY - JOUR A1 - Kohlert, Dieter A1 - Schreier, Franz T1 - Line-by-Line Computation of Atmospheric Infrared Spectra With Field Programmable Gate Arrays JF - IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing N2 - Radiative transfer modelling of high resolution infrared (or microwave) spectra still represents a major challenge for the processing of atmospheric remote sensing data despite significant advances in the numerical techniques utilized in line-by-line modelling by, e.g., optimized Voigt function algorithms or multigrid approaches. Special purpose computing hardware such as Field Programmable Gate Arrays (FPGAs) can be used to cope with the dramatic increase of data quality and quantity. Utilizing a highly optimized implementation of an uniform rational function approximation of the Voigt function, the molecular absorption cross section computation-representing the most compute intensive part of radiative transfer codes-has been realized on FPGA. Design and implementation of the FPGA coprocessor is presented along with first performance tests and an outlook for the ongoing further development. Y1 - 2011 U6 - https://doi.org/10.1109/JSTARS.2010.2098395 VL - 4 IS - 3 SP - 701 EP - 709 ER - TY - JOUR A1 - Kohlert, Dieter T1 - The sub-threshold behaviour of the MOS field-effect transistor JF - European Journal of Physics Y1 - 1998 UR - https://www.scopus.com/authid/detail.uri?authorId=6602919972#disabled VL - 19 IS - 2 SP - 125 EP - 131 PB - IOP Science ER - TY - JOUR A1 - Frikel, Jürgen T1 - Sparse regularization in limited angle tomography JF - Applied and Computational Harmonic Analysis N2 - We investigate the reconstruction problem of limited angle tomography. Such problems arise naturally in applications like digital breast tomosynthesis, dental tomography, electron microscopy, etc. Since the acquired tomographic data is highly incomplete, the reconstruction problem is severely ill-posed and the traditional reconstruction methods, e.g. filtered backprojection (FBP), do not perform well in such situations. To stabilize the reconstruction procedure additional prior knowledge about the unknown object has to be integrated into the reconstruction process. In this work, we propose the use of the sparse regularization technique in combination with curvelets. We argue that this technique gives rise to an edge-preserving reconstruction. Moreover, we show that the dimension of the problem can be significantly reduced in the curvelet domain. To this end, we give a characterization of the kernel of the limited angle Radon transform in terms of curvelets and derive a characterization of solutions obtained through curvelet sparse regularization. In numerical experiments, we will show that the theoretical results directly translate into practice and that the proposed method outperforms classical reconstructions. KW - Curvelets KW - Dimensionality reduction KW - limited angle tomography KW - Radon transform KW - Sparse regularization Y1 - 2013 U6 - https://doi.org/10.1016/j.acha.2012.03.005 VL - 34 IS - 1 SP - 117 EP - 141 PB - Elsevier ER - TY - JOUR A1 - Frikel, Jürgen T1 - Short communication: Dimensionality reduction of curvelet sparse regularizations in limited angle tomography JF - Proceedings in applied mathematics and mechanics : PAMM N2 - We investigate the reconstruction problem for limited angle tomography. Such problems arise naturally in applications like digital breast tomosynthesis, dental tomography, etc. Since the acquired tomographic data is highly incomplete, the reconstruction problem is severely ill-posed and the traditional reconstruction methods, such as filtered backprojection (FBP), do not perform well in such situations. To stabilize the inversion we propose the use of a sparse regularization technique in combination with curvelets. We argue that this technique has the ability to preserve edges. As our main result, we present a characterization of the kernel of the limited angle Radon transform in terms of curvelets. Moreover, we characterize reconstructions which are obtained via curvelet sparse regularizations at a limited angular range. As a result, we show that the dimension of the limited angle problem can be significantly reduced in the curvelet domain. Y1 - 2011 U6 - https://doi.org/10.1002/pamm.201110412 SN - 1617-7061 VL - 11 IS - 1 SP - 847 EP - 848 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Frikel, Jürgen A1 - Quinto, Eric Todd T1 - Artifacts in Incomplete Data Tomography with Applications to Photoacoustic Tomography and Sonar JF - SIAM Journal on Applied Mathematics N2 - We develop a paradigm using microlocal analysis that allows one to characterize the visible and added singularities in a broad range of incomplete data tomography problems. We give precise characterizations for photoacoustic and thermoacoustic tomography and sonar, and provide artifact reduction strategies. In particular, our theorems show that it is better to arrange sonar detectors so that the boundary of the set of detectors does not have corners and is smooth. To illustrate our results, we provide reconstructions from synthetic spherical mean data as well as from experimental photoacoustic data. KW - computed tomography KW - Fourier integral operators KW - Lambda tomography KW - limited angle tomography KW - microlocal analysis KW - photoacoustic tomography KW - radon transforms KW - sonar KW - spherical mean KW - thermoacoustic tomography Y1 - 2015 U6 - https://doi.org/10.1137/140977709 SN - 1095-712X SN - 0036-1399 VL - 75 IS - 2 SP - 703 EP - 725 PB - Society for Industrial and Applied Mathematics CY - Philadelphia, Pa. ER - TY - JOUR A1 - Frikel, Jürgen A1 - Quinto, Eric Todd T1 - Characterization and reduction of artifacts in limited angle tomography JF - Inverse Problems N2 - We consider the reconstruction problem for limited angle tomography using filtered backprojection (FBP) and lambda tomography. We use microlocal analysis to explain why the well-known streak artifacts are present at the end of the limited angular range. We explain how to mitigate the streaks and prove that our modified FBP and lambda operators are standard pseudodifferential operators, and so they do not add artifacts. We provide reconstructions to illustrate our mathematical results. Y1 - 2013 U6 - https://doi.org/10.1088/0266-5611/29/12/125007 SN - 0266-5611 SN - 1361-6420 VL - 29 IS - 12 PB - IOP Publishing CY - Bristol ER - TY - JOUR A1 - Storath, Martin A1 - Weinmann, Andreas A1 - Frikel, Jürgen A1 - Unser, Michael T1 - Joint image reconstruction and segmentation using the Potts model JF - Inverse Problems N2 - We propose a new algorithmic approach to the non-smooth and non-convex Potts problem (also called piecewise-constant Mumford–Shah problem) for inverse imaging problems. We derive a suitable splitting into specific subproblems that can all be solved efficiently. Our method does not require a priori knowledge on the gray levels nor on the number of segments of the reconstruction. Further, it avoids anisotropic artifacts such as geometric staircasing. We demonstrate the suitability of our method for joint image reconstruction and segmentation. We focus on Radon data, where we in particular consider limited data situations. For instance, our method is able to recover all segments of the Shepp–Logan phantom from seven angular views only. We illustrate the practical applicability on a real positron emission tomography dataset. As further applications, we consider spherical Radon data as well as blurred data. Y1 - 2015 U6 - https://doi.org/10.1088/0266-5611/31/2/025003 SN - 0266-5611 SN - 1361-6420 VL - 31 IS - 2 PB - IOP Publishing CY - Bristol ER - TY - JOUR A1 - Wieczorek, Matthias A1 - Frikel, Jürgen A1 - Vogel, Jakob A1 - Eggl, Elena A1 - Kopp, Felix A1 - Noël, Peter B. A1 - Pfeiffer, Franz A1 - Demaret, Laurent A1 - Lasser, Tobias T1 - X-ray computed tomography using curvelet sparse regularization JF - Medical physics N2 - PURPOSE Reconstruction of x-ray computed tomography (CT) data remains a mathematically challenging problem in medical imaging. Complementing the standard analytical reconstruction methods, sparse regularization is growing in importance, as it allows inclusion of prior knowledge. The paper presents a method for sparse regularization based on the curvelet frame for the application to iterative reconstruction in x-ray computed tomography. METHODS In this work, the authors present an iterative reconstruction approach based on the alternating direction method of multipliers using curvelet sparse regularization. RESULTS Evaluation of the method is performed on a specifically crafted numerical phantom dataset to highlight the method's strengths. Additional evaluation is performed on two real datasets from commercial scanners with different noise characteristics, a clinical bone sample acquired in a micro-CT and a human abdomen scanned in a diagnostic CT. The results clearly illustrate that curvelet sparse regularization has characteristic strengths. In particular, it improves the restoration and resolution of highly directional, high contrast features with smooth contrast variations. The authors also compare this approach to the popular technique of total variation and to traditional filtered backprojection. CONCLUSIONS The authors conclude that curvelet sparse regularization is able to improve reconstruction quality by reducing noise while preserving highly directional features. Y1 - 2015 U6 - https://doi.org/10.1118/1.4914368 SN - 0094-2405 SN - 2473-4209 VL - 42 IS - 4 SP - 1555 EP - 1565 PB - American Association of Physicists in Medicine ER - TY - JOUR A1 - Froese, Vincent A1 - Jain, Brijnesh A1 - Rymar, Maciej A1 - Welle, Mathias T1 - Fast Exact Dynamic Time Warping on Run-Length Encoded Time Series JF - Algorithmica N2 - Dynamic Time Warping (DTW) is a well-known similarity measure for time series. The standard dynamic programming approach to compute the DTW distance of two length-n time series, however, requires O(n2) time, which is often too slow for real-world applications. Therefore, many heuristics have been proposed to speed up the DTW computation. These are often based on lower bounding techniques, approximating the DTW distance, or considering special input data such as binary or piecewise constant time series. In this paper, we present a first exact algorithm to compute the DTW distance of two run-length encoded time series whose running time only depends on the encoding lengths of the inputs. The worst-case running time is cubic in the encoding length. In experiments we show that our algorithm is indeed fast for time series with short encoding lengths. Y1 - 2022 U6 - https://doi.org/10.1007/s00453-022-01038-3 PB - Springer Nature ER - TY - JOUR A1 - Davendra, Donald A1 - Herrmann, Frank A1 - Bialic-Davendra, Magdalena T1 - Chaotic Flower Pollination Algorithm for scheduling tardiness-constrained flow shop with simultaneously loaded stations JF - Neural computing & applications N2 - This paper introduces a novel chaotic flower pollination algorithm (CFPA) to solve a tardiness-constrained flow-shop scheduling problem with simultaneously loaded stations. This industrial manufacturing problem is modeled from a filter basket production line in Germany and has been generally solved using standard deterministic algorithms. This research develops a metaheuristic approach based on the highly efficient flower pollination algorithm coupled with different chaos maps for stochasticity. The objective function targeted is the tardiness constraint of the due dates. Fifteen different experiments with thirty scenarios are generated to mimic industrial conditions. The results are compared with the genetic algorithm and with the four standard benchmark priority rule-based deterministic algorithms of First In First Out, Raghu and Rajendran, Shortest Processing Time and Slack. From the obtained results and analysis of the relative difference, percentage relative difference and t tests, CFPA was found to be significantly better performing than the deterministic heuristics and the GA algorithm. KW - Flower pollination algorithm KW - Chaos maps KW - Flow shop with tardiness Y1 - 2022 U6 - https://doi.org/10.1007/s00521-022-08044-0 PB - Springer Nature ER - TY - JOUR A1 - Garkisch, Michael A1 - Steinke, Joss A1 - Steiner, Olivier A1 - Thiem, Carolin A1 - Zeyen, Anica T1 - Imagining the future beyond the crystal ball: Artificial Human Services here we come? JF - Journal of Technology in Human Services N2 - This special issue is focused on the topic of artificial intelligence in the field of human services. In addition to the importance and transformative potential of AI, the editorial presents in detail the areas of application, which range from case management, mental health, client support to administrative support and education. The special issue itself features three articles on AI technology in dementia care, AI in psychosocial support during natural disasters and LLM in mental health. The editorial also highlights important challenges related to data management, ethics, human rights and the need for an inclusive, human-centered design. The recommendations and future directions for further research emphasize the importance of interdisciplinary collaboration, ethical standards and stakeholder engagement, human-centered AI and data management to ensure responsible and effective integration and implementation of AI into human services. Y1 - 2025 U6 - https://doi.org/10.1080/15228835.2025.2502831 SP - 1 EP - 9 PB - Taylor & Francis ER - TY - JOUR A1 - Jain, Brijnesh A1 - Froese, Vincent A1 - Schultz, David T1 - An average-compress algorithm for the sample mean problem under dynamic time warping JF - Journal of Global Optimization N2 - Computing a sample mean of time series under dynamic time warping is NP-hard. Consequently, there is an ongoing research effort to devise efficient heuristics. The majority of heuristics have been developed for the constrained sample mean problem that assumes a solution of predefined length. In contrast, research on the unconstrained sample mean problem is underdeveloped. In this article, we propose a generic average-compress (AC) algorithm to address the unconstrained problem. The algorithm alternates between averaging (A-step) and compression (C-step). The A-step takes an initial guess as input and returns an approximation of a sample mean. Then the C-step reduces the length of the approximate solution. The compressed approximation serves as initial guess of the A-step in the next iteration. The purpose of the C-step is to direct the algorithm to more promising solutions of shorter length. The proposed algorithm is generic in the sense that any averaging and any compression method can be used. Experimental results show that the AC algorithm substantially outperforms current state-of-the-art algorithms for time series averaging. KW - Time series averaging KW - Fréchet function KW - Heuristic KW - Nonconvex optimization Y1 - 2023 U6 - https://doi.org/10.1007/s10898-023-01294-9 PB - Springer ER - TY - JOUR A1 - Johannsen, Florian A1 - Zellner, Gregor A1 - Griesberger, Philipp T1 - Creating a Functional Interdependency Map for Supporting the “Act of Improvement” in Business Process Improvement Projects JF - International Journal of Service Science, Management, Engineering, and Technology (IJSSMET) N2 - Business process improvement (BPI) is of high priority for practitioners. But especially the most value-adding phase in a BPI project, namely the “act of improvement”, is insufficiently supported despite the many existing methods and techniques. Until now, it is largely unclear as to what degree existing BPI techniques support each other and are interrelated with one another. Thus, the purpose of this paper is to investigate the functional interdependencies between BPI techniques to get a better understanding for the beneficial synergies between the BPI techniques and to provide a basis for purposefully combining them within projects. Based on the functional interdependencies, a graphical “Functional Interdependency Map” is developed and its usability demonstrated in an experiment. The paper is valuable for academics and practitioners alike because the impact of BPI on organizational performance is high. KW - BPI Technique KW - Business Process KW - Case Study KW - Conceptual Model KW - Design Science KW - Experiment KW - Map KW - Metamodel Y1 - 2022 U6 - https://doi.org/10.4018/IJSSMET.295557 SN - 1947-959X VL - 13 IS - 1 PB - IGI Global ER - TY - JOUR A1 - Schwägerl, Felix A1 - Westfechtel, Bernhard T1 - Integrated revision and variation control for evolving model-driven software product lines JF - Software and systems modeling N2 - Software engineering projects are faced with abstraction, which is achieved by software models, historical evolution, which is addressed by revision control, and variability, which is managed with the help of software product line engineering. Addressing these phenomena by separate tools ignores obvious overlaps and therefore fails at exploiting synergies between revision and variation control for models. In this article, we present a conceptual framework for integrated revision and variation control of model-driven software projects. The framework reuses the abstractions of revision graphs and feature models and follows an iterative, revision-control-like approach to software product line engineering called product-based product line development. A single version (i.e., a variant of a selected revision) is made available in a workspace, where the user may apply arbitrary modifications. Based on a user-provided specification of the affected variants, the changes are automatically written back to a transparent repository that relies on an internal multi-version storage. The uniform handling of revisions and variants of models is achieved by transparently mapping version concepts to a semantic base layer, which is defined upon propositional logic. At the heart of the conceptual framework is a dynamic filtered editing model, which allows that the versioned artifacts and the feature model co-evolve. We contribute algorithms for checkout and commit, which satisfy a set of consistency constraints referring to variant specifications in an evolving feature model. This article furthermore addresses the orchestration of collaborative development by distributed replication and the well formedness of text and model artifacts to be checked out into the workspace. The Eclipse-based tool SuperMod demonstrates the feasibility of the conceptual framework. It allows the user to reuse arbitrary editing tools for text-based programming and/or Ecore-based modeling languages. An evaluation based on three case studies investigates the properties of SuperMod with a specific focus on filtered editing. The evaluation demonstrates that the dynamic filtered editing model reduces the cognitive complexity and the amount of user interaction necessary for variation control when compared to unfiltered model-driven approaches to software product line engineering. Y1 - 2019 U6 - https://doi.org/10.1007/s10270-019-00722-3 SN - 1619-1366 VL - 18 IS - 6 SP - 3373 EP - 3420 PB - Springer Science and Business Media ER - TY - JOUR A1 - Linsbauer, Lukas A1 - Schwägerl, Felix A1 - Berger, Thorsten A1 - Grünbacher, Paul T1 - Concepts of variation control systems JF - Journal of Systems and Software N2 - Version control systems are an integral part of today’s software engineering. They facilitate the collaborative management of revisions (sequential versions) and variants (concurrent versions) of software systems under development. Typical version control systems maintain revisions of files and variants of whole software systems. Variants are supported via branching or forking mechanisms that conceptually clone whole systems in a coarse-grained way. Unfortunately, such cloning leads to high maintenance efforts. To avoid these disadvantages and support fine-grained variation, developers need to employ custom configuration mechanisms, which leads to a misappropriation of tools and undesired context switches. Addressing this trade-off, a number of variation control systems has been conceived, providing a richer set of capabilities for handling variants. Variation control systems decompose a software system into finer-grained variable entities and offer high-level metaphors to automatically manage this variability. In this paper, we classify and compare variation control systems and illustrate their core concepts and characteristics. All investigated variation control systems offer an iterative (checkout–modify–commit) workflow, but there are essential differences affecting developers. We highlight challenges and discuss research perspectives for developing the next generation of version and variation control systems. Y1 - 2021 U6 - https://doi.org/10.1016/j.jss.2020.110796 SN - 0164-1212 VL - 171 PB - Elsevier ER - TY - JOUR A1 - Kynast, Josef Paul A1 - Schwägerl, Felix A1 - Höcker, Birte ED - Martelli, Pier Luigi T1 - ATLIGATOR: editing protein interactions with an atlas-based approach JF - Bioinformatics N2 - Abstract Motivation Recognition of specific molecules by proteins is a fundamental cellular mechanism and relevant for many applications. Being able to modify binding is a key interest and can be achieved by repurposing established interaction motifs. We were specifically interested in a methodology for the design of peptide binding modules. By leveraging interaction data from known protein structures, we plan to accelerate the design of novel protein or peptide binders. Results We developed ATLIGATOR—a computational method to support the analysis and design of a protein’s interaction with a single side chain. Our program enables the building of interaction atlases based on structures from the PDB. From these atlases pocket definitions are extracted that can be searched for frequent interactions. These searches can reveal similarities in unrelated proteins as we show here for one example. Such frequent interactions can then be grafted onto a new protein scaffold as a starting point of the design process. The ATLIGATOR tool is made accessible through a python API as well as a CLI with python scripts. Availability and implementation Source code can be downloaded at github (https://www.github.com/Hoecker-Lab/atligator), installed from PyPI (‘atligator’) and is implemented in Python 3. Y1 - 2022 U6 - https://doi.org/10.1093/bioinformatics/btac685 SN - 1367-4803 VL - 38 IS - 23 SP - 5199 EP - 5205 PB - Oxford University Press (OUP) ER - TY - JOUR A1 - Stadler, Sebastian A1 - Cornet, Henriette A1 - Frenkler, Fritz T1 - Assessing Heuristic Evaluation in Immersive Virtual Reality: A Case Study on Future Guidance Systems JF - Multimodal Technologies and Interaction N2 - A variety of evaluation methods for user interfaces (UI) exist such as usability testing, cognitive walkthrough, and heuristic evaluation. However, UIs such as guidance systems at transit hubs must be evaluated in their intended application field to allow the effective and valid identification of usability flaws. However, what if evaluations are not feasible in real environments, or laboratorial conditions cannot be ensured? Based on adapted heuristics, in the present study, the method of heuristic evaluation is combined with immersive Virtual Reality (VR) for the identification of usability flaws of dynamic guidance systems (DGS) at transit hubs. The study involved usability evaluations of nine DGS concepts using the newly proposed method. The results show that compared to computer-based heuristic evaluations, the use of immersive VR led to the identification of an increased amount of “severe” usability flaws as well as overall usability flaws. Within a qualitative assessment, immersive VR is validated as a suitable tool for conducting heuristic evaluations involving significant advantages such as the creation of realistic experiences in laboratorial conditions. Future work seeks to further prove the suitability of using immersive VR for heuristic evaluations and compare the proposed method to other evaluative methods. KW - virtual reality KW - heuristic evaluation KW - human-computer interaction KW - user interfaces KW - guidance system Y1 - 2023 U6 - https://doi.org/10.3390/mti7020019 SN - 2414-4088 VL - 7 IS - 2 ER - TY - JOUR A1 - Kong, Penny A1 - Stadler, Sebastian A1 - Forchhammer, Niklas A1 - Cornet, Henriette T1 - Menschzentrierte Gestaltung für ein autonomes Mobilitätssystem in Singapur JF - ATZextra N2 - Die Automatisierung macht auch vor den öffentlichen Verkehrsmitteln nicht halt. Das Team Design for Autonomous Mobility von TUMCREATE stellt Ergebnisse aus der Designforschung vor, in der Virtual Reality und andere neue Methoden für das Design autonomer Verkehrsmittel untersucht werden. Das Team orientiert sich dabei stark am Menschen und versucht, allen Passagieren mehr Komfort und ein positives Reiseerlebnis zu bieten. Y1 - 2020 U6 - https://doi.org/10.1007/s35778-020-0112-5 SN - 2509-4610 SN - 2509-4602 VL - 25 IS - Suppl 1 SP - 38 EP - 43 PB - Springer Fachmedien CY - Wiesbaden ER - TY - JOUR A1 - Holler, Nathalie A1 - Westner, Markus T1 - Factors Influencing Cloud Computing Adoption in Small and Medium-Sized Enterprises: A Systematic Review JF - Informatica N2 - This paper investigates the factors influencing cloud computing adoption in small and medium-sized enterprises (SMEs) through a systematic literature review. The analysis identified twelve key factors influencing the adoption of cloud computing in SMEs. Based on the Technology-Organisation-Environment (TOE) model and the Technology Acceptance Model (TAM), a conceptual framework was developed for future research. The most important factors are cost, organisational readiness, compatibility, relative advantage and top management support. Other influential factors include security, perceived usefulness, firm size, government support, perceived ease of use, vendor support and competitive pressure. The majority of studies were conducted in Asian countries, including developing countries, limiting the generalisability of the findings to SMEs in more developed economies. This research highlights the need for cloud computing solutions that not only reduce costs and ensure high levels of security and privacy, but are also easy to use and integrate. Further research is recommended to explore these factors within SMEs in more developed economies. KW - cloud computing adoption KW - small and medium-sized enterprises (SMEs) KW - technology-organization-environment (TOE) framework KW - systematic literature review KW - digital transformation Y1 - 2025 U6 - https://doi.org/10.31449/inf.v49i1.6971 SN - 1854-3871 VL - 49 IS - 1 PB - Slovenian Association Informatika ER - TY - JOUR A1 - Schiering, Nadine A1 - Eichstädt, Sascha A1 - Heizmann, Michael A1 - Koch, Wolfgang A1 - Schneider, Linda-Sophie A1 - Scheele, Stephan A1 - Sommer, Klaus-Dieter T1 - Modelling of measuring systems – From white box models to cognitive approaches JF - Measurement: Sensors N2 - Mathematical models of measuring systems and processes play an essential role in metrology and practical measurements. They form the basis for understanding and evaluating measurements, their results and their trustworthiness. Classic analytical parametric modelling is based on largely complete knowledge of measurement technology and the measurement process. But due to digital transformation towards the Internet of Things (IIoT) with an increasing number of intensively and flexibly networked measurement systems and consequently ever larger amounts of data to be processed, data-based modelling approaches have gained enormous importance. This has led to new approaches in measurement technology and industry like Digital Twins, Self-X Approaches, Soft Sensor Technology and Data and Information Fusion. In the future, data-based modelling will be increasingly dominated by intelligent, cognitive systems. Evaluating of the accuracy, trustworthiness and the functional uncertainty of the corresponding models is required. This paper provides a concise overview of modelling in metrology from classical white box models to intelligent, cognitive data-driven solutions identifying advantages and limitations. Additionally, the approaches to merge trustworthiness and metrological uncertainty will be discussed. Y1 - 2024 U6 - https://doi.org/10.1016/j.measen.2024.101503 SN - 2665-9174 PB - Elsevier BV ER - TY - JOUR A1 - Beck, Nico A1 - Dovern, Jonas A1 - Vogl, Stefanie T1 - Mind the naive forecast! a rigorous evaluation of forecasting models for time series with low predictability JF - Applied Intelligence N2 - In the field of time series forecasting, numerous machine learning studies have assessed the performance of new methods on highly volatile data from macroeconomics and finance. Unlike in other domains, where models are also compared to simpler statistical or naive baselines, they mostly compare the performance solely relative to other complex models. This approach may lead to limited conclusions and reduce the practical significance of the results, as it overlooks the unpredictability of some highly volatile time series in the datasets used. We apply state-of-the-art methods from time-series econometrics and machine learning, including autoregressive integrated moving average (ARIMA), exponential smoothing (ETS), Bayesian vector autoregressive model (BVAR), long-short term memory neural networks (LSTM), historical consistent neural networks (HCNN), deep vector autoregressive neural networks (DeepVAR), temporal fusion transformers (TFT), and extreme gradient boosting (XGBoost). Our results demonstrate that no method consistently outperforms the naive (no-change) forecast for highly volatile time series from two popular datasets containing exchange rates and stock prices, rendering comparative analysis between complex models less meaningful. In contrast, when applied to more predictable macroeconomic price indices, many of the methods significantly outperform naive forecasts. We find that the performance of machine learning models deteriorates more than that of statistical models for high-volatility time series. This study highlights the critical importance of using appropriate benchmark models, including cost-effective, simple approaches, on datasets that permit meaningful conclusions. Y1 - 2025 U6 - https://doi.org/10.1007/s10489-025-06268-w VL - 55 IS - 6 PB - Springer ER - TY - JOUR A1 - Chavez Vega, Jhohan Harvey A1 - Schorr, Philipp A1 - Kaufhold, Tobias A1 - Zentner, Lena A1 - Zimmermann, Klaus A1 - Böhm, Valter T1 - Influence of Elastomeric Tensioned Members on the Characteristics of Compliant Tensegrity Structures in Soft Robotic Applications JF - Procedia Manufacturing N2 - The use of mechanically prestressed compliant structures in soft robotics is a recently discussed topic. Tensegrity structures, consisting of a set of rigid disconnected compressed members connected to a continuous net of prestressed elastic tensioned members build one specific class of these structures. Robots based on these structures have manifold shape changing abilities and can adapt their mechanical properties reversibly by changing of their prestress state according to specific tasks. In the paper selected aspects on the potential use of elastomer materials in these structures are discussed with the help of theoretical analysis. Therefore, a selected basic tensegrity structure with elastomer members is investigated focusing on the stiffness and shape changing ability in dependence of the nonlinear hyperelastic behavior of the used elastomer materials. The considered structure is compared with a conventional tensegrity structure with linear elastic tensioned members. Finally, selected criterions for the advantageous use of elastomer materials in compliant tensegrity robots are discussed. KW - compliant tensegrity structures KW - soft robotics KW - elastomers Y1 - 2020 U6 - https://doi.org/10.1016/j.promfg.2020.11.048 SN - 2351-9789 VL - 52 SP - 289 EP - 294 PB - Elsevier ER - TY - JOUR A1 - Strasser, Artur A1 - Strahringer, Susanne A1 - Westner, Markus T1 - Determinants of success and failure of knowledge transfer in information systems offshoring BT - A ranking-type Delphi study JF - International Journal of Information Technology and Management N2 - The transfer of knowledge from client to service provider poses major challenges in information systems (IS) offshoring projects. Knowledge transfer directly affects IS offshoring success. Therefore, associated challenges must be overcome. Our study examines the determinants of success and failure of knowledge transfer in IS offshoring projects based on a ranking-type Delphi study. We questioned 32 experts from Germany, each with more than ten years of experience in near- or offshore initiatives to seek a consensus among them. We identified 19 success and 20 failure determinants. These determinants are ranked in order of importance using best-worst scaling. Aspects of closer cooperation are critical for effective knowledge transfer. This includes regular collaboration, willingness to help and support, and mutual trust. In contrast, critical determinants of failure are concerned with fears and fluctuation of human resources. Hidden ambiguities or knowledge gaps, an unwillingness and disability to share knowledge, and high fluctuation of human resources negatively impact knowledge transfer. KW - best-worst scaling KW - Delphi KW - Information systems offshoring KW - knowledge transfer KW - determinants of success Y1 - 2023 U6 - https://doi.org/10.1504/IJITM.2023.10055151 SN - 1741-5179 VL - 22 IS - 1/2 PB - Inderscience ER - TY - JOUR A1 - Kratzer, Simon A1 - Westner, Markus A1 - Strahringer, Susanne T1 - Mehr als Vollzeit: Fractional CIOs in KMUs JF - HMD Praxis der Wirtschaftsinformatik N2 - Auch kleine und mittlere Unternehmen (KMUs) benötigen zunehmend ein effektives Informationstechnologie- (IT)-Management, um wettbewerbsfähig zu bleiben. Im Vergleich zu großen Unternehmen verfügen KMUs jedoch oft nicht über die Ressourcen, die Arbeitgeberattraktivität oder den Bedarf, um einen Chief Information Officer (CIO) in Vollzeit zu beschäftigen. Um diese Lücke zu schließen, hat eine wachsende Zahl von Expertinnen und Experten weltweit damit begonnen, CIO-Dienste in Teilzeit anzubieten. Auf diese Weise erhalten KMUs Zugang zu erfahrenen und kompetenten IT-Führungskräften zu einem Bruchteil der Kosten und ohne langfristige Verpflichtungen. Während diese so genannten „Fractional CIOs“ in der Praxis bereits einen Mehrwert schaffen, gibt es noch kaum wissenschaftliche Untersuchungen zu diesem neuen Phänomen. In einem größeren Forschungsprojekt mit insgesamt 62 Fractional CIOs aus 10 Ländern wurden daher eine Definition, Typen verschiedenartiger Engagements und Erfolgsfaktoren abgeleitet. Die vorliegende Studie fasst die Ergebnisse zusammen und setzt sie in Bezug zum deutschen Markt, indem sie drei Fractional CIOs/CTOs aus Deutschland befragt. Es zeigt sich, dass die folgenden vier Engagement-Typen von Fractional CIOs für KMUs in verschiedenen Situationen von Nutzen sind: Strategisches IT-Management, Restrukturierung, Skalierung und Hands-on Support. Darüber hinaus zeigt die Studie, dass Vertrauen, die Unterstützung durch das Top-Management-Team und die Integrität des Fractional CIOs Schlüsselfaktoren für den Erfolg von Fractional CIO-Engagements sind. Für den deutschen Markt werden die Ergebnisse durch drei befragte Fractional CIOs/CTOs weitgehend bestätigt. Die Fractional CIOs/CTOs können zwar keine genauen Gründe für die geringe Akzeptanz der Rolle nennen, betonen aber ihr Wertpotenzial für den deutschen Markt. KW - Chief Information Officer KW - Chief Technology Officer KW - Fractional CIO KW - Fractional CTO KW - Teilzeit-Interim-Management Y1 - 2023 U6 - https://doi.org/10.1365/s40702-023-01010-x SN - 2198-2775 PB - Springer ER - TY - JOUR A1 - Pozzobon, Enrico A1 - Weiß, Nils A1 - Mottok, Jürgen A1 - Matoušek, Václav T1 - An evolutionary fault injection settings search algorithm for attacks on safe and secure embedded systems JF - Neural Network World (NNW) Y1 - 2023 U6 - https://doi.org/10.14311/NNW.2023.33.020 VL - 33 IS - 5 SP - 357 EP - 374 PB - Czech Technical University in Prague ER - TY - JOUR A1 - Wintersperger, Karen A1 - Dommert, Florian A1 - Ehmer, Thomas A1 - Hoursanov, Andrey A1 - Klepsch, Johannes A1 - Mauerer, Wolfgang A1 - Reuber, Georg A1 - Strohm, Thomas A1 - Yin, Ming A1 - Luber, Sebastian T1 - Neutral Atom Quantum Computing Hardware: Performance and End-User Perspective JF - EPJ Quantum Technology N2 - We present an industrial end-user perspective on the current state of quantum computing hardware for one specific technological approach, the neutral atom platform. Our aim is to assist developers in understanding the impact of the specific properties of these devices on the effectiveness of algorithm execution. Based on discussions with different vendors and recent literature, we discuss the performance data of the neutral atom platform. Specifically, we focus on the physical qubit architecture, which affects state preparation, qubit-to-qubit connectivity, gate fidelities, native gate instruction set, and individual qubit stability. These factors determine both the quantum-part execution time and the end-to-end wall clock time relevant for end-users, but also the ability to perform fault-tolerant quantum computation in the future. We end with an overview of which applications have been shown to be well suited for the peculiar properties of neutral atom-based quantum computers. KW - Neutral atom quantum computers KW - Review KW - Quantum computing platforms KW - Performance metrics KW - Benchmarks Y1 - 2023 U6 - https://doi.org/10.1140/epjqt/s40507-023-00190-1 VL - 10 PB - Springer Nature ER - TY - JOUR A1 - Dahmen, Victoria A1 - Weikl, Simone A1 - Bogenberger, Klaus T1 - Interpretable Machine Learning for Mode Choice Modeling on Tracking-Based Revealed Preference Data JF - Transportation Research Record: Journal of the Transportation Research Board N2 - Mode choice modeling is imperative for predicting and understanding travel behavior. For this purpose, machine learning (ML) models have increasingly been applied to stated preference and traditional self-recorded revealed preference data with promising results, particularly for extreme gradient boosting (XGBoost) and random forest (RF) models. Because of the rise in the use of tracking-based smartphone applications for recording travel behavior, we address the important and unprecedented task of testing these ML models for mode choice modeling on such data. Furthermore, as ML approaches are still criticized for leading to results that are hard to understand, we consider it essential to provide an in-depth interpretability analysis of the best-performing model. Our results show that the XGBoost and RF models far outperform a conventional multinomial logit model, both overall and for each mode. The interpretability analysis using the Shapley additive explanations approach reveals that the XGBoost model can be explained well at the overall and mode level. In addition, we demonstrate how to analyze individual predictions. Lastly, a sensitivity analysis gives insight into the relative importance of different data sources, sample size, and user involvement. We conclude that the XGBoost model performs best, while also being explainable. Insights generated by such models can be used, for instance, to predict mode choice decisions for arbitrary origin–destination pairs to see which impacts infrastructural changes would have on the mode share. KW - travel behavior KW - sensitivity analysis KW - smartphone tracking KW - mode choice KW - revealed preference KW - interpretable machine learning Y1 - 2024 U6 - https://doi.org/10.1177/03611981241246973 SN - 0361-1981 VL - 2678 IS - 11 SP - 2075 EP - 2091 PB - SAGE Publications ER - TY - JOUR A1 - Brosig, Christoph A1 - Gräubig, Dix M. A1 - Strahringer, Susanne A1 - Westner, Markus T1 - Prerequisites and Causal Recipes for Manufacturers’ IT-Enabled Service Innovation Success JF - Communications of the Association for Information Systems N2 - For manufacturing firms, success in innovating IT-enabled services is a critical antecedent to benefit from digital servitization of their business models. Digital servitization literature has explored mechanisms for success in innovating IT-enabled services, indicating that the phenomenon is multifaceted and needs to be explained from multiple theoretical perspectives. We derive a conceptual model for success in innovating IT-enabled services covering its multifaceted nature by referring to knowledge-based and organizational control theory. We test this model using qualitative cases of IT-enabled service innovation initiatives in manufacturing firms and use set-theoretic analyses to account for the multifaceted nature of the phenomenon. The necessary condition analysis yields that a certain degree of service innovation capabilities is a prerequisite for success. With the results of a qualitative comparative analysis, we obtain five solution terms as causal recipes for success in innovating IT-enabled services. Our results contribute to research by offering a theory-based approach that explains the multiplicity of success in IT-enabled service innovation. Practitioners benefit from our results by understanding prerequisites and causal recipes for success while learning from unsuccessful initiatives in innovating IT-enabled services of manufacturing firms. Our study is also an example of how to rigorously calibrate qualitative data using a structured approach. Y1 - 2024 U6 - https://doi.org/10.17705/1CAIS.05509 SN - 1529-3181 VL - 55 SP - 205 EP - 256 PB - Association for Information Systems, AIS ER - TY - JOUR A1 - Hinterberger, Lukas A1 - Fischer, Sebastian A1 - Weber, Bernhard A1 - Neubauer, Katrin A1 - Hackenberg, Rudolf T1 - Extended Definition of the Proposed Open Standard for IoT Device IdentificAtion and RecoGnition (IoTAG) JF - International Journal on Advances in Internet Technology N2 - Internet of Things (IoT) devices are critical to operate and maintain, because of their number and high connectivity. A lot of security issues concern IoT devices and the networks they are integrated. To help getting an overview of an IoT network, the devices and the security, we propose a scoring system to get a good impression of IT security. This system generates single scores for each device, using features like encryption, update behavior, etc. Furthermore, a summarized score for the whole network is calculated, to show the status of the network security in an easy way for the administrator. To enable the scoring system, a precise list of the existing devices and their operating status is necessary. To achieve this, we present an open standard for the IoT Device IdentificAtion and RecoGnition (short IoTAG), which requires that devices report, e.g., their name, an unique ID, the firmware version and the supported encryption. The proposed standard is described in detail and an implementation guideline is given in this paper. Additionally, information about how to realize the serialization, the integrity and the communication with IoTAG. KW - Internet of Things KW - device identification KW - open standard KW - security rating KW - IoTAG Y1 - 2020 UR - https://www.thinkmind.org/articles/inttech_v13_n34_2020_2.pdf VL - 13 IS - 3 & 4 SP - 110 EP - 121 PB - IARIA ER - TY - JOUR A1 - Galka, Stefan A1 - Follath, Alexander A1 - Bross, Florian ED - Bauer, Wilhelm ED - Volk, Wolfram ED - Zäh, Michael T1 - Vorgehensmodell zur Erstellung Digitaler Zwillinge für Produktion und Logistik JF - Zeitschrift für wirtschaftlichen Fabrikbetrieb N2 - Der Digitale Zwilling (DZ) ist ein wichtiger Bestandteil der Industrie 4.0 und ermöglicht Anwendungen wie Predictive Maintenance, virtuelles Prototyping oder die Steuerung von Produktions- und Logistikprozessen. Herausforderungen bei der Entwicklung des Digitalen Zwillings entstehen durch fehlende Struktur und Standards. Mit diesem Beitrag soll ein Vorgehensmodell für die Erstellung eines Digitalen Zwillings im Bereich der Produktion und Logistik aufgezeigt werden. Das Vorgehensmodell hilft bei der Einordnung, für welche Anwendungsfälle ein Digitaler Zwilling entwickelt werden kann, welche Schritte bei einer Umsetzung erfolgen müssen, und gibt einen Überblick über die Voraussetzungen und Komplexität bei der Entwicklung. Das zentrale Element bildet dabei die zielgerichtete Aufbereitung und Analyse der zugrunde liegenden Daten mittels des in der Industrie etablierten Vorgehensmodell CRISP-DM. KW - Digitale Zwillinge KW - Simulation KW - Logistik KW - Produktion Y1 - 2022 U6 - https://doi.org/10.1515/zwf-2022-1127 VL - 117 IS - 11 SP - 691 EP - 696 PB - De Gruyter CY - Berlin ER - TY - JOUR A1 - Kopper, Andreas A1 - Fürstenau, Daniel A1 - Zimmermann, Stephan A1 - Klotz, Stefan A1 - Rentrop, Christopher A1 - Rothe, Hannes A1 - Strahringer, Susanne A1 - Westner, Markus T1 - Shadow IT and Business-Managed IT: A Conceptual Framework and Empirical Illustration JF - International Journal of IT/Business Alignment and Governance (IJITBAG) N2 - Research on Shadow IT is facing a conceptual dilemma in cases where previously “covert” systems developed by business entities are integrated in the organizational IT management. These systems become visible, are thus not “in the shadows” anymore, and subsequently do not fit to existing definitions of Shadow IT. Practice shows that some information systems share characteristics of Shadow IT but are created openly in alignment with the IT organization. This paper proposes the term “Business-managed IT” to describe “overt” information systems developed or managed by business entities and distinguishes it from Shadow IT by illustrating case vignettes. Accordingly,our contribution is to suggest a concept and its delineation against other concepts. In this way, IS researchers interested in IT originated from or maintained by business entities can construct theories with a wider scope of application that are at the same time more specific to practical problems. In addition, the terminology allows to value potentially innovative developments by business entities more adequately. KW - Alignment KW - Business-managed IT KW - IT governance KW - Shadow IT KW - Unternehmen KW - Informationstechnik KW - Datensicherung KW - Organizational IT management Y1 - 2018 U6 - https://doi.org/10.4018/IJITBAG.2018070104 VL - 9 IS - 2 SP - 53 EP - 71 PB - IGI Global ER - TY - JOUR A1 - Borg, Leise A1 - Frikel, Jürgen A1 - Jørgensen, Jakob Sauer A1 - Quinto, Eric Todd T1 - Analyzing Reconstruction Artifacts from Arbitrary Incomplete X-ray CT Data JF - SIAM Journal on Imaging Sciences N2 - This article provides a mathematical analysis of singular (nonsmooth) artifacts added to reconstructions by filtered backprojection (FBP) type algorithms for X-ray computed tomography (CT) with arbitrary incomplete data. We prove that these singular artifacts arise from points at the boundary of the data set. Our results show that, depending on the geometry of this boundary, two types of artifacts can arise: object-dependent and object-independent artifacts. Object-dependent artifacts are generated by singularities of the object being scanned, and these artifacts can extend along lines. They generalize the streak artifacts observed in limited-angle tomography. Object-independent artifacts, on the other hand, are essentially independent of the object and take one of two forms: streaks on lines if the boundary of the data set is not smooth at a point and curved artifacts if the boundary is smooth locally. We prove that these streak and curve artifacts are the only singular artifacts that can occur for FBP in the continuous case. In addition to the geometric description of artifacts, the article provides characterizations of their strength in Sobolev scale in certain cases. The results of this article apply to the well-known incomplete data problems, including limited-angle and regionof-interest tomography, as well as to unconventional X-ray CT imaging setups that arise in new practical applications. Reconstructions from simulated and real data are analyzed to illustrate our theorems, including the reconstruction that motivated this work a synchrotron data set in which artifacts appear on lines that have no relation to the object. KW - DATA TOMOGRAPHY KW - Fourier integral operators KW - GENERALIZED RADON-TRANSFORM KW - IMAGE-RECONSTRUCTION KW - incomplete data tomography KW - limited-angle tomography KW - METAL ARTIFACTS KW - microlocal analysis KW - PROJECTIONS KW - reconstruction artifact KW - region-of-interest tomography KW - SINGULARITIES KW - wavefront set KW - X-ray tomography Y1 - 2018 U6 - https://doi.org/10.1137/18M1166833 VL - 11 IS - 4 SP - 2786 EP - 2814 PB - SIAM PUBLICATIONS ER - TY - JOUR A1 - Kopper, Andreas A1 - Klotz, Stefan A1 - Westner, Markus A1 - Strahringer, Susanne T1 - Shadow IT and Business-managed IT BT - Practitioner Perceptions and Their Comparison to Literature JF - Journal of Information Technology Management (JITM) N2 - Two concepts describe the autonomous deployment of IT by business entities: Shadow IT and Business-managed IT. Shadow IT is deployed covertly, that is, software, hardware, or IT services created/procured or managed by business entities without alignment with the IT organization. In contrast, Business-managed IT describes the overt deployment of IT, that is, in alignment with the IT organization or in a split responsibility model. The purpose of this paper is to extend the conceptual understanding of Shadow IT and Business-managed IT, comparing the perceptions of 29 CIOs and senior IT managers with the results of a systematic literature review. By doing so, this paper presents a structured and comprehensive view of causing factors, outcomes, and governance of Shadow IT and Business-managed IT in practice. A comparison of academic literature and practitioner perceptions reveals the limitations and gaps of the current research and highlights avenues for future research. The authors find three category-spanning themes occurring as causing factors, outcomes, and—as part of governance measures—factors to improve the IT organization: (1) (Poor) business-IT alignment (2) (lack of) agility, and (3) (lack of) policies. This study is innovative with its comprehensive qualitative interview data that the authors compare to the existing literature. Therefore, the paper brings together theoretical and practical insights into Shadow IT and Businessmanaged IT, which should aid practitioners and scholars in decision making and future research. KW - Corporate Governance KW - Strategisches Management KW - Shadow IT KW - Business-managed IT KW - IT governance KW - Agility KW - Business-IT alignment KW - Informationsmanagement Y1 - 2019 UR - http://home.thejitm.org/XXX-4/contents.html SN - 1042-1319 VL - 30 IS - 4 ER - TY - JOUR A1 - Käss, Sebastian A1 - Brosig, Christoph A1 - Westner, Markus A1 - Strahringer, Susanne T1 - Short and sweet: multiple mini case studies as a form of rigorous case study research JF - Information Systems and e-Business Management N2 - Case study research is one of the most widely used research methods in Information Systems (IS). In recent years, an increasing number of publications have used case studies with few sources of evidence, such as single interviews per case. While there is much methodological guidance on rigorously conducting multiple case studies, it remains unclear how researchers can achieve an acceptable level of rigour for this emerging type of multiple case study with few sources of evidence, i.e., multiple mini case studies. In this context, we synthesise methodological guidance for multiple case study research from a cross-disciplinary perspective to develop an analytical framework. Furthermore, we calibrate this analytical framework to multiple mini case studies by reviewing previous IS publications that use multiple mini case studies to provide guidelines to conduct multiple mini case studies rigorously. We also offer a conceptual definition of multiple mini case studies, distinguish them from other research approaches, and position multiple mini case studies as a pragmatic and rigorous approach to research emerging and innovative phenomena in IS. KW - Case study research KW - Multiple mini case study KW - Short case study KW - Methodological guidance Y1 - 2024 U6 - https://doi.org/10.1007/s10257-024-00674-2 PB - Springer Nature ER - TY - JOUR A1 - Klotz, Stefan A1 - Kopper, Andreas A1 - Westner, Markus A1 - Strahringer, Susanne T1 - Von Schatten-IT zu Business-managed IT: Fachbereichs-IT gezielt gestalten JF - Wirtschaftsinformatik & Management N2 - Fachbereichs-IT, Schatten-IT, Business-managed IT. All diese Begriffe beschreiben IT, die neben den eigentlichen, regulären IT-Systemen oder -Prozessen in Unternehmen existieren und von Mitarbeiterinnen und Mitarbeitern der Fachbereiche genutzt werden. Im Fall von„Schatten-IT“ handelt es sich um IT-Systeme und -Prozesse (IT-Instanzen), die sich ohne Kenntnis der IT-Verantwortlichen etabliert haben; im Fall von„Business-managed IT“ entstehen die IT-Systeme und -Prozesse in Kenntnis der bzw. in Abstimmung mit den IT-Verantwortlichen im Unternehmen.„Fachbereichs-IT“ subsumiert Schatten-IT und Business-managed IT. Welche Ursachen führen zu solchen IT-Instanzen, welche Potenziale und Risiken haben diese IT-Instanzen und wie lassen sie sich steuern? KW - Business-managed IT KW - Fachbereichs IT KW - IT Governance KW - Schatten IT KW - Shadow IT Y1 - 2022 U6 - https://doi.org/10.1365/s35764-022-00421-7 SN - 1867-5913 SN - 1867-5905 VL - 14 IS - 4 SP - 282 EP - 287 PB - Springer Nature ER - TY - JOUR A1 - Klotz, Stefan A1 - Kopper, Andreas A1 - Westner, Markus A1 - Strahringer, Susanne T1 - Causing factors, outcomes, and governance of Shadow IT and business-managed IT BT - A systematic literature review JF - International Journal of Information Systems and Project Management N2 - Shadow IT and Business-managed IT describe the autonomous deployment/procurement or management of Information Technology (IT) instances, i.e., software, hardware, or IT services, by business entities. For Shadow IT, this happens covertly, i.e., without alignment with the IT organization; for Business-managed IT this happens overtly, i.e., in alignment with the IT organization or in a split responsibility model. We conduct a systematic literature review and structure the identified research themes in a framework of causing factors, outcomes, and governance. As causing factors, we identify enablers, motivators, and missing barriers. Outcomes can be benefits as well as risks/shortcomings of Shadow IT and Business-managed IT. Concerning governance, we distinguish two subcategories: general governance for Shadow IT and Business-managed IT and instance governance for overt Business-managed IT. Thus, a specific set of governance approaches exists for Business-managed IT that cannot be applied to Shadow IT due to its covert nature. Hence, we extend the existing conceptual understanding and allocate research themes to Shadow IT, Business-managed IT, or both concepts and particularly distinguish the governance of the two concepts. Besides, we find that governance themes have been the primary research focus since 2016, whereas older publications (until 2015) focused on causing factors. KW - Shadow IT KW - Business-managed IT KW - IT governance KW - literature review KW - outcomes KW - Betriebliches Informationssystem KW - Datensicherung KW - Literaturbericht Y1 - 2019 UR - http://www.sciencesphere.org/ijispm/archive/ijispm-070102.pdf U6 - https://doi.org/10.12821/ijispm070102 SN - 2182-7796 SN - 2182-7788 SN - 2182-780X VL - 7 IS - 1 SP - 15 EP - 43 ER - TY - JOUR A1 - Joblin, Mitchell A1 - Apel, Sven A1 - Mauerer, Wolfgang T1 - Evolutionary trends of developer coordination: a network approach JF - Empirical Software Engineering N2 - Software evolution is a fundamental process that transcends the realm of technical artifacts and permeates the entire organizational structure of a software project. By means of a longitudinal empirical study of 18 large open-source projects, we examine and discuss the evolutionary principles that govern the coordination of developers. By applying a network-analytic approach, we found that the implicit and self-organizing structure of developer coordination is ubiquitously described by non-random organizational principles that defy conventional software-engineering wisdom. In particular, we found that: (a) developers form scale-free networks, in which the majority of coordination requirements arise among an extremely small number of developers, (b) developers tend to accumulate coordination requirements with more and more developers over time, presumably limited by an upper bound, and (c) initially developers are hierarchically arranged, but over time, form a hybrid structure, in which core developers are hierarchically arranged and peripheral developers are not. Our results suggest that the organizational structure of large projects is constrained to evolve towards a state that balances the costs and benefits of developer coordination, and the mechanisms used to achieve this state depend on the project’s scale. KW - Developer coordination KW - Developer networks KW - Software evolution Y1 - 2016 U6 - https://doi.org/10.1007/s10664-016-9478-9 VL - 22 IS - 4 SP - 2050 EP - 2094 PB - Springer ER - TY - JOUR A1 - Joblin, Mitchell A1 - Mauerer, Wolfgang T1 - An Interactive Survey Framework for Validation of Social Network Analysis JF - The R Journal N2 - Abstract Social network analysis is extremely well supported by the R community and is routinely used for studying the relationships between people engaged in collaborative activities. While there has been rapid development of new approaches and metrics in this field, the challenging question of validity (how well insights derived from social networks agree with reality) is often difficult to address. We propose the use of several R packages to generate interactive surveys that are specifically well suited for validating social network analyses. Using our web-based survey application, we were able to validate the results of applying community-detection algorithms to infer the organizational structure of software developers contributing to open-source projects. Y1 - 2016 UR - https://journal.r-project.org/archive/2016/RJ-2016-010/index.html VL - 8 IS - 1 SP - 149 EP - 158 ER - TY - JOUR A1 - Leusch, Vera A1 - Corsten, Sabine A1 - Giordano, Katharina A1 - Kreiter, Daniel A1 - Lauer, Norina T1 - App erleichtert Gespräche über das Leben JF - Aktivieren : das Magazin für die soziale Betreuung N2 - Das Forschungsteam BaSeTaLK hat gemeinsam mit Menschen im Alter eine App zur Biografiearbeit fr Bewohner:innen in Senioreneinrichtungen entwickelt. Sie befähigt insbesondere Ehrenamtliche, biografische Gespräche zu führen. KW - Biografieforschung KW - Digitalisierung Y1 - 2022 UR - https://www.basetalk.de/wp-content/uploads/2022/10/Aktivieren_05_2022_App_erleichtert_Gespraeche_ueber_das_Leben.pdf SN - 2364-303X VL - 8 IS - 5 SP - 32 EP - 35 PB - Vincentz CY - Hannover ER - TY - JOUR A1 - Ebner, Andrea A1 - Frikel, Jürgen A1 - Lorenz, Dirk A1 - Schwab, J. A1 - Haltmeier, Markus T1 - Regularization of inverse problems by filtered diagonal frame decomposition JF - Applied and Computational Harmonic Analysis N2 - Inverse problems are at the heart of many practical problems such as image reconstruction or nondestructive testing. A characteristic feature is their instability with respect to data perturbations. To stabilize the inversion process, regularization methods must be developed and applied. In this paper, we introduce the concept of filtered diagonal frame decomposition, which extends the classical filtered SVD to the case of frames. The use of frames as generalized singular systems allows a better match to a given class of potential solutions and is also beneficial for problems where the SVD is not analytically available. We show that filtered diagonal frame decompositions yield convergent regularization methods, derive convergence rates under source conditions and prove order optimality. Our analysis applies to bounded and unbounded forward operators. As a practical application of our tools, we study filtered diagonal frame decompositions for inverting the Radon transform as an unbounded operator on L2(R2). Y1 - 2023 U6 - https://doi.org/10.1016/j.acha.2022.08.005 N1 - Preprint unter: https://arxiv.org/pdf/2008.06219.pdf OPUS-Einrag unter: https://opus4.kobv.de/opus4-oth-regensburg/admin/document/edit/id/2290 VL - 62 IS - January SP - 66 EP - 83 PB - Elsevier ER - TY - JOUR A1 - Maier, Robert A1 - Grabinger, Lisa A1 - Urlhart, David A1 - Mottok, Jürgen T1 - Causal Models to Support Scenario-Based Testing of ADAS JF - IEEE Transactions on Intelligent Transportation Systems N2 - In modern vehicles, system complexity and technical capabilities are constantly growing. As a result, manufacturers and regulators are both increasingly challenged to ensure the reliability, safety, and intended behavior of these systems. With current methodologies, it is difficult to address the various interactions between vehicle components and environmental factors. However, model-based engineering offers a solution by allowing to abstract reality and enhancing communication among engineers and stakeholders. Applying this method requires a model format that is machine-processable, human-understandable, and mathematically sound. In addition, the model format needs to support probabilistic reasoning to account for incomplete data and knowledge about a problem domain. We propose structural causal models as a suitable framework for addressing these demands. In this article, we show how to combine data from different sources into an inferable causal model for an advanced driver-assistance system. We then consider the developed causal model for scenario-based testing to illustrate how a model-based approach can improve industrial system development processes. We conclude this paper by discussing the ongoing challenges to our approach and provide pointers for future work. KW - automated driving systems KW - Automation KW - Bayesian networks KW - Causal inference KW - Data models KW - ISO Standards KW - model-based testing KW - Safety KW - Task analysis KW - Testing KW - Vehicles Y1 - 2023 U6 - https://doi.org/10.1109/TITS.2023.3317475 SN - 1524-9050 SP - 1 EP - 17 PB - IEEE ER - TY - JOUR A1 - Marterer, Verena A1 - Radouchová, Michaela A1 - Soukup, Radek A1 - Hipp, Susanne A1 - Blecha, Tomáš T1 - Wearable textile antennas: investigation on material variants, fabrication methods, design and application JF - Fashion and Textiles N2 - With the ongoing miniaturization of wireless devices, the importance of wearable textiles in the antenna segment has increased significantly in recent years. Due to the widespread utilization of wireless body sensor networks for healthcare and ubiquitous applications, the design of wearable antennas offers the possibility of comprehensive monitoring, communication, and energy harvesting and storage. This article reviews a number of properties and benefits to realize comprehensive background information and application ideas for the development of lightweight, compact and low-cost wearable patch antennas. Furthermore, problems and challenges that arise are addressed. Since both electromagnetic and mechanical specifications must be fulfilled, textile and flexible antennas require an appropriate trade-off between materials, antenna topologies, and fabrication methods—depending on the intended application and environmental factors. This overview covers each of the above issues, highlighting research to date while correlating antenna topology, feeding techniques, textile materials, and contacting options for the defined application of wearable planar patch antennas. KW - Wearable communication KW - Textile antenna KW - Patch antenna KW - Design requirements KW - Smart textiles KW - E-textiles Y1 - 2024 U6 - https://doi.org/10.1186/s40691-023-00369-1 VL - 11 PB - Springer Open ER - TY - JOUR A1 - Polz, Julius A1 - Glawion, Luca A1 - Gebisso, Hiob A1 - Altenstrasser, Lukas A1 - Graf, Maximilian A1 - Kunstmann, Harald A1 - Vogl, Stefanie A1 - Chwala, Christian T1 - Temporal Super-Resolution, Ground Adjustment, and Advection Correction of Radar Rainfall Using 3-D-Convolutional Neural Networks JF - IEEE Transactions on Geoscience and Remote Sensing N2 - Weather radars are highly sophisticated tools for quantitative precipitation estimation (QPE) and provide observations with unmatched spatial representativeness. However, their indirect measurement of precipitation high above ground leads to strong systematic errors compared to direct rain gauge measurements. Additionally, the temporal undersampling from 5-min instantaneous radar measurements requires advection correction. We present ResRadNet, a 3-D-convolutional residual neural network approach, to reduce these errors and, at the same time, increase the temporal resolution of the radar rainfall fields by a 5-min short-range prediction of 1-min time-steps. The network is trained to process spatiotemporal sequences of radar rainfall estimates from a composite product derived from 17 C-band weather radars in Germany. In contrast to previous approaches, we present a method that emphasizes the generation of spatiotemporally consistent and advection-corrected country-wide rainfall maps. Our approach significantly increased the Pearson correlation coefficient (PCC) of the radar product (from 0.63 to 0.74) and decreased the root mean squared error (mse) by 22% when compared to 247 rain gauges at a 5-min resolution. An additional large-scale comparison to eight years of data from 1138 independent manual daily gauges confirmed that the improvement is robust and transferable to new locations. Overall, our study shows the benefits of using 3-D convolutional neural networks (CNNs) for weather radar rainfall estimation to provide 1-min, ground-adjusted, that is, bias-corrected with respect to on-ground sensors, and advection-corrected radar rainfall estimates. KW - Rain KW - Radar measurements KW - Meteorological radar KW - Three-dimensional displays KW - Spaceborne radar KW - Spatial resolution KW - Reflectivity KW - Convolutional neural network (CNN) KW - deep learning KW - precipitation KW - residual neural network KW - weather radar Y1 - 2024 U6 - https://doi.org/10.1109/TGRS.2024.3371577 VL - 62 SP - 1 EP - 10 ER - TY - JOUR A1 - Reicheneder, Matthias A1 - Westner, Markus A1 - Matschi, Markus T1 - IT-Near- und Offshoring in deutschen Großunternehmen: Aktueller Stand, Motive und Auswahlkriterien JF - HMD Praxis der Wirtschaftsinformatik N2 - Die vorliegende Studie untersucht die aktuelle IT-Near- und Offshoring-Praxis in deutschen Großunternehmen. Dafür wurden 33 CIOs und IT-Führungskräfte mittels Interviews befragt. Haupttreiber der geografischen Verlagerung von IT-Services ins Ausland ist die Ressourcenverfügbarkeit in anderen Ländern, bedingt durch den Fachkräftemangel in Deutschland. Dies trifft auch auf die Auswahl geeigneter IT-Services für das Near- und Offshoring zu. Während IT-Near- und Offshoring historisch primär aufgrund von Kosteneinsparungen initiiert wurde, spielt dieser Aspekt heute eine untergeordnete Rolle. Die Interviewteilnehmer und -teilnehmerinnen sehen in Kosteneinsparungen zwar immer noch einen positiven Effekt, erwarten aber, dass dieser in Zukunft aufgrund der Angleichung des Kostenniveaus schwinden wird. Die Unternehmen verlagern hauptsächlich Applikationsbetrieb und -entwicklung, erkennen jedoch zunehmend das Potenzial, auch höherwertige Aufgaben, z. B. Projektmanagement und Unternehmensarchitekturmanagement, aus geografisch entfernteren Ländern erbringen zu lassen. Unternehmen, die ausschließlich IT-Nearshoring betreiben, erbringen weniger als ein Drittel ihrer IT-Services aus nahegelegenen Ländern. Firmen mit IT-Offshoring-Präsenzen weisen einen höheren IT-Near‑/Offshoringgrad auf und verlagern knapp die Hälfte der eigenen IT-Serviceerbringung ins Ausland. Die beliebtesten Länder sind Portugal für das Nearshoring und Indien für das Offshoring. KW - Nearshoring KW - Offshoring KW - IT Services KW - Drivers KW - Selection Criteria KW - Large Companies KW - Study KW - Motive KW - Auswahlkriterien KW - Großunternehmen KW - Studie Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-79582 SN - 1436-3011 N1 - Corresponding author der OTH Regensbrg: Markus Westner PB - Springer Nature CY - Wiesbaden ER - TY - JOUR A1 - Mauerer, Wolfgang A1 - Joblin, Mitchell A1 - Tamburri, Damian A1 - Paradis, Carlos A1 - Kazman, Rick A1 - Apel, Sven T1 - In Search of Socio-Technical Congruence: A Large-Scale Longitudinal Study JF - IEEE Transactions on Software Engineering (TSE) N2 - This paper describes a large-scale empirical study investigating the relevance of socio-technical congruence over key basic software quality metrics, namely, bugs and churn. That is, we explore whether alignment or misalignment of social communication structures and technical dependencies in large software projects influences software quality. To this end, we have defined a quantitative and operational notion of socio-technical congruence, which we call /socio-technical motif congruence/ (STMC). STMC is a measure of the degree to which developers working on the same file or on two related files, need to communicate. As socio-technical congruence is a complex and multi-faceted phenomenon, the interpretability of the results is one of our main concerns, so we have employed a careful mixed-methods statistical analysis. In particular, we provide analyses with similar techniques as employed by seminal work in the field to ensure comparability of our results with the existing body of work. The major result of our study, based on an analysis of 25 large open-source projects, is that STMC is /not/ related to project quality measures---software bugs and churn---in any temporal scenario. That is, we find no statistical relationship between the alignment of developer tasks and developer communications on one hand, and project outcomes on the other hand. We conclude that, wherefore congruence does matter as literature shows, then its measurable effect lies elsewhere. KW - Socio-Technical Congruence KW - Human Factors in Software Engineering; KW - Graph Analysis KW - Empirical Software Engineering KW - Quantitative Software Engineering KW - Mixed-Methods Research KW - Socio-Technical Analysis Y1 - 2022 U6 - https://doi.org/10.1109/TSE.2021.3082074 N1 - Corresponding author: Wolfgang Mauerer VL - 48 IS - 8 SP - 3159 EP - 3184 PB - IEEE ER - TY - JOUR A1 - Moser, Elisabeth A1 - Jobst, Simon A1 - Bierl, Rudolf A1 - Jenko, Frank T1 - A Deep Learning System to Transform Cross-Section Spectra to Varying Environmental Conditions JF - Vibrational Spectroscopy N2 - Absorption cross-sections provide a basis for many gas sensing applications. Therefore, any error in molecular cross-sections caused by varying environmental conditions propagates to spectroscopic applications. Original molecular cross-sections in varying environmental conditions can only be simulated for some molecules, whereas for most multi-atom molecules, one must rely on high-precision measurements at certain environmental configurations. In this study, a deep learning system trained with simulated absorption cross-sections for predicting cross-sections at a different pressure configuration is presented. The system’s capability to transfer to measured, multi-atom cross-sections is demonstrated. Thus, it provides an alternative to (pseudo-) line lists whenever the required information for simulation is unavailable. The predictive performance of the system was evaluated on validation data via simulation, and its transfer learning capabilities were demonstrated on actual measurement chlorine nitrate data. From the comparison between the system and line lists, the system shows slightly worse performance than pseudo-line lists but its predictive quality is still deemed acceptable with less than 5% relative integral change with a highly localized error around the peak center. This opens a promising way for further research to use deep learning to simulate the effect of varying environmental conditions on absorption cross-sections. KW - Spectroscopy KW - Deep learning KW - Simulation KW - Pressure broadening KW - Pseudo-line lists KW - Transfer learning Y1 - 2022 U6 - https://doi.org/10.1016/j.vibspec.2022.103410 SN - 0924-2031 VL - 122 IS - September PB - Elsevier ER - TY - JOUR A1 - Schönberger, Manuel T1 - Applicability of Quantum Computing on Database Query Optimization JF - SIGMOD '22: proceedings of the 2022 International Conference on Management of Data : June 12-17, 2022, Philadelphia, PA, USA N2 - We evaluate the applicability of quantum computing on two fundamental query optimization problems, join order optimization and multi query optimization (MQO). We analyze the problem dimensions that can be solved on current gate-based quantum systems and quantum annealers, the two currently commercially available architectures. First, we evaluate the use of gate-based systems on MQO, previously solved with quantum annealing. We show that, contrary to classical computing, a different architecture requires involved adaptations. We moreover propose a multi-step reformulation for join ordering problems to make them solvable on current quantum systems. Finally, we systematically evaluate our contributions for gate-based quantum systems and quantum annealers. Doing so, we identify the scope of current limitations, as well as the future potential of quantum computing technologies for database systems. Y1 - 2022 U6 - https://doi.org/10.1145/3514221.3520257 SP - 2512 EP - 2514 PB - ACM CY - New York, NY ER - TY - JOUR A1 - Lehmann, Thomas M. A1 - Palm, Christoph T1 - Color Line Search for Illuminant Estimation in Real World Scenes JF - Journal of the Optical Society of America (JOSA) A N2 - The estimation of illuminant color is mandatory for many applications in the field of color image quantification. However, it is an unresolved problem if no additional heuristics or restrictive assumptions apply. Assuming uniformly colored and roundly shaped objects, Lee has presented a theory and a method for computing the scene-illuminant chromaticity from specular highlights [H. C. Lee, J. Opt. Soc. Am. A 3, 1694 (1986)]. However, Lee’s method, called image path search, is less robust to noise and is limited in the handling of microtextured surfaces. We introduce a novel approach to estimate the color of a single illuminant for noisy and microtextured images, which frequently occur in real-world scenes. Using dichromatic regions of different colored surfaces, our approach, named color line search, reverses Lee’s strategy of image path search. Reliable color lines are determined directly in the domain of the color diagrams by three steps. First, regions of interest are automatically detected around specular highlights, and local color diagrams are computed. Second, color lines are determined according to the dichromatic reflection model by Hough transform of the color diagrams. Third, a consistency check is applied by a corresponding path search in the image domain. Our method is evaluated on 40 natural images of fruit and vegetables. In comparison with those of Lee’s method, accuracy and stability are substantially improved. In addition, the color line search approach can easily be extended to scenes of objects with macrotextured surfaces. Y1 - 2001 U6 - https://doi.org/10.1364/JOSAA.18.002679 VL - 18 IS - 11 SP - 2679 EP - 2691 ER - TY - JOUR A1 - Palm, Christoph T1 - Color Texture Classification by Integrative Co-Occurrence Matrices JF - Pattern Recognition N2 - Integrative Co-occurrence matrices are introduced as novel features for color texture classification. The extended Co-occurrence notation allows the comparison between integrative and parallel color texture concepts. The information profit of the new matrices is shown quantitatively using the Kolmogorov distance and by extensive classification experiments on two datasets. Applying them to the RGB and the LUV color space the combined color and intensity textures are studied and the existence of intensity independent pure color patterns is demonstrated. The results are compared with two baselines: gray-scale texture analysis and color histogram analysis. The novel features improve the classification results up to 20% and 32% for the first and second baseline, respectively. KW - Color texture KW - Co-occurrence matrix KW - Integrative features KW - KolmogKorov distance KW - Image classification Y1 - 2004 U6 - https://doi.org/10.1016/j.patcog.2003.09.010 VL - 37 IS - 5 SP - 965 EP - 976 ER - TY - JOUR A1 - Palm, Christoph A1 - Lehmann, Thomas M. T1 - Classification of Color Textures by Gabor Filtering JF - Machine GRAPHICS & VISION Y1 - 2002 VL - 11 IS - 2/3 SP - 195 EP - 219 ER - TY - JOUR A1 - Souza Jr., Luis Antonio de A1 - Passos, Leandro A. A1 - Mendel, Robert A1 - Ebigbo, Alanna A1 - Probst, Andreas A1 - Messmann, Helmut A1 - Palm, Christoph A1 - Papa, João Paulo T1 - Assisting Barrett's esophagus identification using endoscopic data augmentation based on Generative Adversarial Networks JF - Computers in Biology and Medicine N2 - Barrett's esophagus figured a swift rise in the number of cases in the past years. Although traditional diagnosis methods offered a vital role in early-stage treatment, they are generally time- and resource-consuming. In this context, computer-aided approaches for automatic diagnosis emerged in the literature since early detection is intrinsically related to remission probabilities. However, they still suffer from drawbacks because of the lack of available data for machine learning purposes, thus implying reduced recognition rates. This work introduces Generative Adversarial Networks to generate high-quality endoscopic images, thereby identifying Barrett's esophagus and adenocarcinoma more precisely. Further, Convolution Neural Networks are used for feature extraction and classification purposes. The proposed approach is validated over two datasets of endoscopic images, with the experiments conducted over the full and patch-split images. The application of Deep Convolutional Generative Adversarial Networks for the data augmentation step and LeNet-5 and AlexNet for the classification step allowed us to validate the proposed methodology over an extensive set of datasets (based on original and augmented sets), reaching results of 90% of accuracy for the patch-based approach and 85% for the image-based approach. Both results are based on augmented datasets and are statistically different from the ones obtained in the original datasets of the same kind. Moreover, the impact of data augmentation was evaluated in the context of image description and classification, and the results obtained using synthetic images outperformed the ones over the original datasets, as well as other recent approaches from the literature. Such results suggest promising insights related to the importance of proper data for the accurate classification concerning computer-assisted Barrett's esophagus and adenocarcinoma detection. KW - Maschinelles Lernen KW - Barrett's esophagus KW - Machine learning KW - Adenocarcinoma KW - Generative adversarial networks KW - Neuronales Netz KW - Adenocarcinom KW - Speiseröhrenkrebs KW - Diagnose Y1 - 2020 U6 - https://doi.org/10.1016/j.compbiomed.2020.104029 VL - 126 IS - November PB - Elsevier ER - TY - JOUR A1 - Graßmann, Felix A1 - Mengelkamp, Judith A1 - Brandl, Caroline A1 - Harsch, Sebastian A1 - Zimmermann, Martina E. A1 - Linkohr, Birgit A1 - Peters, Annette A1 - Heid, Iris M. A1 - Palm, Christoph A1 - Weber, Bernhard H. F. T1 - A Deep Learning Algorithm for Prediction of Age-Related Eye Disease Study Severity Scale for Age-Related Macular Degeneration from Color Fundus Photography JF - Ophtalmology N2 - Purpose Age-related macular degeneration (AMD) is a common threat to vision. While classification of disease stages is critical to understanding disease risk and progression, several systems based on color fundus photographs are known. Most of these require in-depth and time-consuming analysis of fundus images. Herein, we present an automated computer-based classification algorithm. Design Algorithm development for AMD classification based on a large collection of color fundus images. Validation is performed on a cross-sectional, population-based study. Participants. We included 120 656 manually graded color fundus images from 3654 Age-Related Eye Disease Study (AREDS) participants. AREDS participants were >55 years of age, and non-AMD sight-threatening diseases were excluded at recruitment. In addition, performance of our algorithm was evaluated in 5555 fundus images from the population-based Kooperative Gesundheitsforschung in der Region Augsburg (KORA; Cooperative Health Research in the Region of Augsburg) study. Methods. We defined 13 classes (9 AREDS steps, 3 late AMD stages, and 1 for ungradable images) and trained several convolution deep learning architectures. An ensemble of network architectures improved prediction accuracy. An independent dataset was used to evaluate the performance of our algorithm in a population-based study. Main Outcome Measures. κ Statistics and accuracy to evaluate the concordance between predicted and expert human grader classification. Results. A network ensemble of 6 different neural net architectures predicted the 13 classes in the AREDS test set with a quadratic weighted κ of 92% (95% confidence interval, 89%–92%) and an overall accuracy of 63.3%. In the independent KORA dataset, images wrongly classified as AMD were mainly the result of a macular reflex observed in young individuals. By restricting the KORA analysis to individuals >55 years of age and prior exclusion of other retinopathies, the weighted and unweighted κ increased to 50% and 63%, respectively. Importantly, the algorithm detected 84.2% of all fundus images with definite signs of early or late AMD. Overall, 94.3% of healthy fundus images were classified correctly. Conclusions Our deep learning algoritm revealed a weighted κ outperforming human graders in the AREDS study and is suitable to classify AMD fundus images in other datasets using individuals >55 years of age. KW - Senile Makuladegeneration KW - Krankheitsverlauf KW - Mustererkennung KW - Maschinelles Lernen Y1 - 2018 U6 - https://doi.org/10.1016/j.ophtha.2018.02.037 N1 - Corresponding authors: Bernhard H. F. Weber, University of Regensburg, and Christoph Palm VL - 125 IS - 9 SP - 1410 EP - 1420 PB - Elsevier ER - TY - JOUR A1 - Hantsch, Carolin A1 - Westner, Markus A1 - Matschi, Markus T1 - IT/OT Convergence: Status Quo and Implementation Recommendations N2 - This study examines IT/OT Convergence in 31 predominantly large German companies. It presents an "IT/OT Governance Framework" as a specific model for successful convergence implementation. The in-terviews revealed that companies are at very different stages of maturity in implementing IT/OT conver-gence. The analysis reveals a heterogeneous level of convergence maturity across the interviewed compa-nies, the majority of which are at the beginning or in the implementation phase. Close cooperation between IT and OT is favoured, but without IT completely taking over OT. An IT/OT tandem consisting of a CIO and a central OT responsible person is seen as the ideal way to take responsibility. Six specific recommen-dations were derived from the interviews and included in the IT/OT Governance Framework developed. These include ensuring top management support, using security as a driver, introducing a central OT re-sponsible person, bringing IT and OT teams closer together, continuously demonstrating the added value of convergence, and taking a step-by-step approach to implementation KW - IT/OT Konvergenz KW - IT KW - OT KW - Governance KW - Framework Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-77586 N1 - This document is an English translation of the article Hantsch, C., Westner, M. & Matschi, M. IT/OT-Konvergenz: Status-Quo und Umsetzungsempfehlungen. HMD (2024). https://doi.org/10.1365/s40702-024-01111-1 N1 - Die deutsche Originalveröffentlichung ist abgelegt unter: https://opus4.kobv.de/opus4-oth-regensburg/frontdoor/index/index/docId/7793 ER - TY - JOUR A1 - Hantsch, Carolin A1 - Westner, Markus A1 - Matschi, Markus T1 - IT/OT-Konvergenz: Status-Quo und Umsetzungsempfehlungen JF - HMD Praxis der Wirtschaftsinformatik N2 - Organisationen machen große Anstrengungen zur Verbesserung ihrer Ambidextrie, d. h. ihrer Fähigkeit sowohl Exploitationsziele (z. B. Effizienz, Vorhersagbarkeit) als auch Explorationsziele (z. B. Anpassbarkeit, Innovation) zu erreichen. Obwohl gemäß der Praxisliteratur Technologie in Software-Projekten dabei eine zentrale Rolle spielen kann, gibt es kaum Forschung dazu, wie technologische Faktoren Ambidexterie in Software-Projekten beeinflussen. In dieser Studie untersuchen wir die Rolle dreier technologischer Faktoren: kontinuierliche Integration, Standardisierung und Microservice-Architektur. Die Ergebnisse einer Mehrinformanten-Umfrage in 95 Projekten in der Schweiz und Dänemark zeigen, dass kontinuierliche Integration und Standardisierung mit höherer Ambidexterie einhergehen, während der Zusammenhang zwischen Microservice-Architektur und Ambidextrie nicht signifikant ist. Unser Artikel geht über die existierende Forschung hinaus, indem er zeigt, dass kontinuierliche Integration und Standardisierung nicht nur Exploitation, sondern auch Exploration fördern können. Wir diskutieren auch Gründe für den insignifikanten Zusammenhang zwischen Microservice-Architektur und Ambidextrie. N2 - This study examines IT/OT Convergence in 31 predominantly large German companies. It presents an “IT/OT Governance Framework” as a specific model for successful convergence implementation. The analysis reveals a heterogeneous level of convergence maturity across the examined companies, the majority of which are at the beginning or in the implementation phase. Close cooperation between IT and OT is favored, but without IT completely taking over OT. An IT/OT tandem consisting of a CIO and a central OT responsible person is seen as the ideal way to take responsibility. Six specific recommendations were derived from the interviews and included in the IT/OT Governance Framework developed. These include ensuring top management support, using security as a driver, introducing a central OT responsible person, bringing IT and OT teams physically closer together, continuously demonstrating the added value of convergence, and taking a step-by-step approach to implementation. KW - IT/OT Convergence KW - Operational Technology KW - OT KW - Governance Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-77937 N1 - Corresponding author der OTH Regensburg: Markus Westner PB - Springer Nature ER - TY - JOUR A1 - Grabinger, Lisa A1 - Hauser, Florian A1 - Wolff, Christian A1 - Mottok, Jürgen T1 - On Eye Tracking in Software Engineering JF - SN Computer Science N2 - Eye tracking is becoming more and more important as a research method within the field of software engineering (SE). Existing meta-analyses focus on the design or conduct of SE eye tracking studies rather than the analysis phase. This article attempts to fill this gap; it presents a systematic literature review of eye tracking studies in the field of SE—focusing mainly on the data analysis methods used. From the IEEE Xplore and ACM digital libraries we gather 125 papers up to the first quarter of 2024. Detailed evaluation provides information on the number of papers that use specific methods of analysis (i.e., descriptive or inferential statistics, and gaze visualization) or settings (e.g., sample size, technical setup, and selected aspects of research design). With the data obtained we can infer the popularity of specific analysis methods in the field. Those results enable efficient work on data analysis tools or education of aspiring researchers and can serve as basis for standardization or guidelines within the community—providing for methods to include as well as current inconsistencies. KW - Eye tracking KW - Software engineering KW - Empirical KW - Systematic literature review Y1 - 2024 U6 - https://doi.org/10.1007/s42979-024-03045-3 SN - 2661-8907 N1 - Zugehöriges Datenset: doi:10.5281/zenodo.11279180 VL - 5 IS - 6 PB - Springer CY - Singapore ER - TY - JOUR A1 - Heinrich, Bernd A1 - Zellner, Gregor A1 - Leist, Susanne T1 - Service integrators in business networks - The importance of relationship values JF - Electronic Markets N2 - To realise the potentials of CRM (customer relationship management), relationship-specific processes need to be designed and implemented in companies. This is all the more important and complicated in business networks where two or more actors collaborate to serve the customers. A good collaboration within business networks is the basis for understanding the customer process and identifying customer needs. But, even in these days of customer orientation, transaction orientation is still a matter of strong interest, and the following questions remain to be answered: What is the difference between relationship-oriented processes and transaction-oriented processes, and how can relationship-oriented processes be designed for a business network? The authors give first answers to both questions by using a systematic, goal-oriented specialisation of generic actions. To give an example, one relationship-oriented process will be designed and specified for a certain customer process in the course of this paper. Y1 - 2011 U6 - https://doi.org/10.1007/s12525-011-0075-x VL - 21 IS - 4 SP - 215 EP - 235 PB - Springer ER - TY - JOUR A1 - Broll, Alexander A1 - Goldhacker, Markus A1 - Hahnel, Sebastian A1 - Rosentritt, Martin T1 - Morphological effects of input data quantity in AI-powered dental crown design JF - Journal of dentistry N2 - OBJECTIVES: This retrospective in vitro study evaluated the impact of input data quantity on the morphology of dental crowns generated by AI-based software. The hypothesis suggests that increased input data quantity improves the quality of generated occlusal surfaces. METHODS: A dataset comprising n=30 patients (11 males, 19 females; age: 22-31 years) was analyzed. Input data was categorized into full dentition (full), quadrant data (quad), and adjacent teeth (adj). AI-based software (Dentbird Crown, Imageworks Inc.) generated crowns for a single lower first molar (36/46). Metrics were proposed to assess the morphology and occlusal relationships of the crowns, with the original tooth as reference. STATISTICS: Friedman Chi-Square tests, Wilcoxon signed rank tests, Kendall correlation and Fligner-Killeen tests (α = 0.05). RESULTS: Full and quad groups provided consistent reconstruction quality with no significant differences in morphology and occlusal relationships. The adj group showed significant (p<0.05) morphological deviations and higher reconstruction failure rates compared to the full and quad groups. Correlations (median: 0.19; min-max range: 0.01-0.54) indicate that the proposed metrics capture distinct morphological and functional crown aspects. CONCLUSION: The software reliably reconstructed crowns with at least quadrant-level input data. Performance declined with reduced input. Full-jaw scans did not enhance accuracy compared to quadrant data. CLINICAL SIGNIFICANCE: Increased input data quantity can improve the accuracy of AI-based restorations. As a result, prosthodontists benefit from predictable, accurate restoration proposals that reduce the need for digital chairside adjustments as well as manual modifications after fabrication. This streamlines clinical workflows and enhances the quality of restorations. Quadrant-level data has proven sufficient to generate high-quality reconstructions. Further input data did not significantly improve the accuracy of the reconstructions. The proposed metrics enable quantitative assessments of morphological and functional restoration quality, supporting reliable AI-driven workflows. Y1 - 2025 U6 - https://doi.org/10.1016/j.jdent.2025.105767 VL - 159 SP - 1 EP - 8 PB - Elsevier ER - TY - JOUR A1 - Broll, Alexander A1 - Rosentritt, Martin A1 - Schlegl, Thomas A1 - Goldhacker, Markus T1 - A data-driven approach for the partial reconstruction of individual human molar teeth using generative deep learning JF - Frontiers in Artificial Intelligence N2 - Background and objectiveDue to the high prevalence of dental caries, fixed dental restorations are regularly required to restore compromised teeth or replace missing teeth while retaining function and aesthetic appearance. The fabrication of dental restorations, however, remains challenging due to the complexity of the human masticatory system as well as the unique morphology of each individual dentition. Adaptation and reworking are frequently required during the insertion of fixed dental prostheses (FDPs), which increase cost and treatment time. This article proposes a data-driven approach for the partial reconstruction of occlusal surfaces based on a data set that comprises 92 3D mesh files of full dental crown restorations.MethodsA Generative Adversarial Network (GAN) is considered for the given task in view of its ability to represent extensive data sets in an unsupervised manner with a wide variety of applications. Having demonstrated good capabilities in terms of image quality and training stability, StyleGAN-2 has been chosen as the main network for generating the occlusal surfaces. A 2D projection method is proposed in order to generate 2D representations of the provided 3D tooth data set for integration with the StyleGAN architecture. The reconstruction capabilities of the trained network are demonstrated by means of 4 common inlay types using a Bayesian Image Reconstruction method. This involves pre-processing the data in order to extract the necessary information of the tooth preparations required for the used method as well as the modification of the initial reconstruction loss.ResultsThe reconstruction process yields satisfactory visual and quantitative results for all preparations with a root mean square error (RMSE) ranging from 0.02 mm to 0.18 mm. When compared against a clinical procedure for CAD inlay fabrication, the group of dentists preferred the GAN-based restorations for 3 of the total 4 inlay geometries.ConclusionsThis article shows the effectiveness of the StyleGAN architecture with a downstream optimization process for the reconstruction of 4 different inlay geometries. The independence of the reconstruction process and the initial training of the GAN enables the application of the method for arbitrary inlay geometries without time-consuming retraining of the GAN. KW - inlay restoration KW - dental prosthesis design KW - StyleGAN KW - machine learning KW - digital dentistry Y1 - 2024 U6 - https://doi.org/10.3389/frai.2024.1339193 SN - 2624-8212 VL - 7 PB - Frontiers Media SA ER - TY - JOUR A1 - Broll, Alexander A1 - Goldhacker, Markus A1 - Hahnel, Sebastian A1 - Rosentritt, Martin T1 - Generative deep learning approaches for the design of dental restorations: A narrative review JF - Journal of Dentistry N2 - Objectives: This study aims to explore and discuss recent advancements in tooth reconstruction utilizing deep learning (DL) techniques. A review on new DL methodologies in partial and full tooth reconstruction is conducted. Data/Sources: PubMed, Google Scholar, and IEEE Xplore databases were searched for articles from 2003 to 2023. Study selection: The review includes 9 articles published from 2018 to 2023. The selected articles showcase novel DL approaches for tooth reconstruction, while those concentrating solely on the application or review of DL methods are excluded. The review shows that data is acquired via intraoral scans or laboratory scans of dental plaster models. Common data representations are depth maps, point clouds, and voxelized point clouds. Reconstructions focus on single teeth, using data from adjacent teeth or the entire jaw. Some articles include antagonist teeth data and features like occlusal grooves and gap distance. Primary network architectures include Generative Adversarial Networks (GANs) and Transformers. Compared to conventional digital methods, DL-based tooth reconstruction reports error rates approximately two times lower. Conclusions: Generative DL models analyze dental datasets to reconstruct missing teeth by extracting insights into patterns and structures. Through specialized application, these models reconstruct morphologically and functionally sound dental structures, leveraging information from the existing teeth. The reported advancements facilitate the feasibility of DL-based dental crown reconstruction. Beyond GANs and Transformers with point clouds or voxels, recent studies indicate promising outcomes with diffusion-based architectures and innovative data representations like wavelets for 3D shape completion and inference problems. Clinical significance: Generative network architectures employed in the analysis and reconstruction of dental structures demonstrate notable proficiency. The enhanced accuracy and efficiency of DL-based frameworks hold the potential to enhance clinical outcomes and increase patient satisfaction. The reduced reconstruction times and diminished requirement for manual intervention may lead to cost savings and improved accessibility of dental services. KW - Tooth reconstruction KW - Dental prosthesis design KW - Deep Learning KW - Digital dentistry Y1 - 2024 U6 - https://doi.org/10.1016/j.jdent.2024.104988 SN - 0300-5712 VL - 145 PB - Elsevier ER - TY - JOUR A1 - Goldhacker, Markus A1 - Tomé, Ana Maria A1 - Greenlee, Mark W. A1 - Lang, Elmar Wolfgang T1 - Frequency-Resolved Dynamic Functional Connectivity Reveals Scale-Stable Features of Connectivity-States JF - Frontiers in Human Neuroscience N2 - Investigating temporal variability of functional connectivity is an emerging field in connectomics. Entering dynamic functional connectivity by applying sliding window techniques on resting-state fMRI (rs-fMRI) time courses emerged from this topic. We introduce frequency-resolved dynamic functional connectivity (frdFC) by means of multivariate empirical mode decomposition (MEMD) followed up by filter-bank investigations. In general, we find that MEMD is capable of generating time courses to perform frdFC and we discover that the structure of connectivity-states is robust over frequency scales and even becomes more evident with decreasing frequency. This scale-stability varies with the number of extracted clusters when applying k-means. We find a scale-stability drop-off from k = 4 to k = 5 extracted connectivity-states, which is corroborated by null-models, simulations, theoretical considerations, filter-banks, and scale-adjusted windows. Our filter-bank studies show that filter design is more delicate in the rs-fMRI than in the simulated case. Besides offering a baseline for further frdFC research, we suggest and demonstrate the use of scale-stability as a possible quality criterion for connectivity-state and model selection. We present first evidence showing that connectivity-states are both a multivariate, and a multiscale phenomenon. A data repository of our frequency-resolved time-series is provided. Y1 - 2018 U6 - https://doi.org/10.3389/fnhum.2018.00253 SN - 1662-5161 VL - 12 SP - 1 EP - 16 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Fellner, Marie-Christin A1 - Volberg, Gregor A1 - Wimber, Maria A1 - Goldhacker, Markus A1 - Greenlee, Mark W. A1 - Hanslmayr, Simon T1 - Spatial mnemonic encoding: Theta power decreases and medial temporal lobe BOLD increases co-occur during the usage of the method of loci JF - eNeuro N2 - The method of loci is one, if not the most, efficient mnemonic encoding strategy. This spatial mnemonic combines the core cognitive processes commonly linked to medial temporal lobe (MTL) activity: spatial and associative memory processes. During such processes, fMRI studies consistently demonstrate MTL activity, while electrophysiological studies have emphasized the important role of theta oscillations (3–8 Hz) in the MTL. However, it is still unknown whether increases or decreases in theta power co-occur with increased BOLD signal in the MTL during memory encoding. To investigate this question, we recorded EEG and fMRI separately, while human participants used the spatial method of loci or the pegword method, a similarly associative but nonspatial mnemonic. The more effective spatial mnemonic induced a pronounced theta power decrease source localized to the left MTL compared with the nonspatial associative mnemonic strategy. This effect was mirrored by BOLD signal increases in the MTL. Successful encoding, irrespective of the strategy used, elicited decreases in left temporal theta power and increases in MTL BOLD activity. This pattern of results suggests a negative relationship between theta power and BOLD signal changes in the MTL during memory encoding and spatial processing. The findings extend the well known negative relation of alpha/beta oscillations and BOLD signals in the cortex to theta oscillations in the MTL. KW - EEG KW - fMRI KW - memory encoding KW - method of loci KW - mnemonics KW - theta oscillations Y1 - 2016 U6 - https://doi.org/10.1523/ENEURO.0184-16.2016 SN - 2373-2822 VL - 3 IS - 6 SP - 1 EP - 16 PB - Society for Neuroscience CY - Washington, DC ER - TY - JOUR A1 - Goldhacker, Markus A1 - Keck, P. A1 - Igel, A. A1 - Lang, Elmar Wolfgang A1 - Tomé, Ana Maria T1 - A multi-variate blind source separation algorithm JF - Computer Methods and Programs in Biomedicine N2 - Background and objective The study follows the proposal of decomposing a given data matrix into a product of independent spatial and temporal component matrices. A multi-variate decomposition approach is presented, based on an approximate diagonalization of a set of matrices computed using a latent space representation. Methods The proposed methodology follows an algebraic approach, which is common to space, temporal or spatiotemporal blind source separation algorithms. More specifically, the algebraic approach relies on singular value decomposition techniques, which avoids computationally costly and numerically instable matrix inversion. The method is equally applicable to correlation matrices determined from second order correlations or by considering fourth order correlations. Results The resulting algorithms are applied to fMRI data sets either to extract the underlying fMRI components or to extract connectivity maps from resting state fMRI data collected for a dynamic functional connectivity analysis. Intriguingly, our algorithm shows increased spatial specificity compared to common approaches, while temporal precision stays similar. Conclusion The study presents a novel spatiotemporal blind source separation algorithm, which is both robust and avoids parameters that are difficult to fine tune. Applied on experimental data sets, the new method yields highly confined and focused areas with least spatial extent in the retinotopy case, and similar results in the dynamic functional connectivity analyses compared to other blind source separation algorithms. Therefore, we conclude that our novel algorithm is highly competitive and yields results, which are superior or at least similar to existing approaches. KW - Blind source separation KW - Independent component analysis KW - fMRI KW - Resting state KW - Retinotopy KW - Spatio temporal Y1 - 2017 U6 - https://doi.org/10.1016/j.cmpb.2017.08.019 SN - 1872-7565 SN - 0169-2607 VL - 151 SP - 91 EP - 99 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Wein, Simon A1 - Deco, Gustavo A1 - Tomé, Ana Maria A1 - Goldhacker, Markus A1 - Malloni, Wilhelm M. A1 - Greenlee, Mark W. A1 - Lang, Elmar Wolfgang T1 - Brain Connectivity Studies on Structure-Function Relationships: A Short Survey with an Emphasis on Machine Learning JF - Computational intelligence and neuroscience N2 - This short survey reviews the recent literature on the relationship between the brain structure and its functional dynamics. Imaging techniques such as diffusion tensor imaging (DTI) make it possible to reconstruct axonal fiber tracks and describe the structural connectivity (SC) between brain regions. By measuring fluctuations in neuronal activity, functional magnetic resonance imaging (fMRI) provides insights into the dynamics within this structural network. One key for a better understanding of brain mechanisms is to investigate how these fast dynamics emerge on a relatively stable structural backbone. So far, computational simulations and methods from graph theory have been mainly used for modeling this relationship. Machine learning techniques have already been established in neuroimaging for identifying functionally independent brain networks and classifying pathological brain states. This survey focuses on methods from machine learning, which contribute to our understanding of functional interactions between brain regions and their relation to the underlying anatomical substrate. KW - Brain Mapping KW - Brain/diagnostic imaging KW - Diffusion Tensor Imaging KW - Machine Learning KW - Magnetic Resonance Imaging KW - Nerve Net/diagnostic imaging KW - Neural Pathways/diagnostic imaging KW - Structure-Activity Relationship Y1 - 2021 U6 - https://doi.org/10.1155/2021/5573740 SP - 1 EP - 31 PB - Hindawi ER - TY - JOUR A1 - Goldhacker, Markus A1 - Fellner, Marie-Christin A1 - Volberg, G. A1 - Mullinger, K. J. A1 - Greenlee, Mark W. A1 - Hanslmayr, Simon T1 - Spurious correlations in simultaneous EEG-fMRI driven by in-scanner movement JF - NeuroImage N2 - Simultaneous EEG-fMRI provides an increasingly attractive research tool to investigate cognitive processes with high temporal and spatial resolution. However, artifacts in EEG data introduced by the MR scanner still remain a major obstacle. This study, employing commonly used artifact correction steps, shows that head motion, one overlooked major source of artifacts in EEG-fMRI data, can cause plausible EEG effects and EEG–BOLD correlations. Specifically, low-frequency EEG (< 20 Hz) is strongly correlated with in-scanner movement. Accordingly, minor head motion (< 0.2 mm) induces spurious effects in a twofold manner: Small differences in task-correlated motion elicit spurious low-frequency effects, and, as motion concurrently influences fMRI data, EEG–BOLD correlations closely match motion-fMRI correlations. We demonstrate these effects in a memory encoding experiment showing that obtained theta power (~ 3–7 Hz) effects and channel-level theta–BOLD correlations reflect motion in the scanner. These findings highlight an important caveat that needs to be addressed by future EEG-fMRI studies. Y1 - 2016 U6 - https://doi.org/10.1016/j.neuroimage.2016.03.031 VL - 133 IS - June SP - 354 EP - 366 PB - Elsevier ER -