@phdthesis{Schmidt2011, author = {Schmidt, Marco}, title = {Ground Station Networks for Efficient Operation of Distributed Small Satellite Systems}, isbn = {978-3-923959-77-8}, doi = {10.25972/OPUS-4984}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-64999}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {The field of small satellite formations and constellations attracted growing attention, based on recent advances in small satellite engineering. The utilization of distributed space systems allows the realization of innovative applications and will enable improved temporal and spatial resolution in observation scenarios. On the other side, this new paradigm imposes a variety of research challenges. In this monograph new networking concepts for space missions are presented, using networks of ground stations. The developed approaches combine ground station resources in a coordinated way to achieve more robust and efficient communication links. Within this thesis, the following topics were elaborated to improve the performance in distributed space missions: Appropriate scheduling of contact windows in a distributed ground system is a necessary process to avoid low utilization of ground stations. The theoretical basis for the novel concept of redundant scheduling was elaborated in detail. Additionally to the presented algorithm was a scheduling system implemented, its performance was tested extensively with real world scheduling problems. In the scope of data management, a system was developed which autonomously synchronizes data frames in ground station networks and uses this information to detect and correct transmission errors. The system was validated with hardware in the loop experiments, demonstrating the benefits of the developed approach.}, subject = {Kleinsatellit}, language = {en} } @article{SchmidSchindelinCardonaetal.2010, author = {Schmid, Benjamin and Schindelin, Johannes and Cardona, Albert and Longair, Martin and Heisenberg, Martin}, title = {A high-level 3D visualization API for Java and ImageJ}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67851}, year = {2010}, abstract = {Background: Current imaging methods such as Magnetic Resonance Imaging (MRI), Confocal microscopy, Electron Microscopy (EM) or Selective Plane Illumination Microscopy (SPIM) yield three-dimensional (3D) data sets in need of appropriate computational methods for their analysis. The reconstruction, segmentation and registration are best approached from the 3D representation of the data set. Results: Here we present a platform-independent framework based on Java and Java 3D for accelerated rendering of biological images. Our framework is seamlessly integrated into ImageJ, a free image processing package with a vast collection of community-developed biological image analysis tools. Our framework enriches the ImageJ software libraries with methods that greatly reduce the complexity of developing image analysis tools in an interactive 3D visualization environment. In particular, we provide high-level access to volume rendering, volume editing, surface extraction, and image annotation. The ability to rely on a library that removes the low-level details enables concentrating software development efforts on the algorithm implementation parts. Conclusions: Our framework enables biomedical image software development to be built with 3D visualization capabilities with very little effort. We offer the source code and convenient binary packages along with extensive documentation at http://3dviewer.neurofly.de.}, subject = {Visualisierung}, language = {en} } @article{SchloerRingHotho2020, author = {Schl{\"o}r, Daniel and Ring, Markus and Hotho, Andreas}, title = {iNALU: Improved Neural Arithmetic Logic Unit}, series = {Frontiers in Artificial Intelligence}, volume = {3}, journal = {Frontiers in Artificial Intelligence}, issn = {2624-8212}, doi = {10.3389/frai.2020.00071}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-212301}, year = {2020}, abstract = {Neural networks have to capture mathematical relationships in order to learn various tasks. They approximate these relations implicitly and therefore often do not generalize well. The recently proposed Neural Arithmetic Logic Unit (NALU) is a novel neural architecture which is able to explicitly represent the mathematical relationships by the units of the network to learn operations such as summation, subtraction or multiplication. Although NALUs have been shown to perform well on various downstream tasks, an in-depth analysis reveals practical shortcomings by design, such as the inability to multiply or divide negative input values or training stability issues for deeper networks. We address these issues and propose an improved model architecture. We evaluate our model empirically in various settings from learning basic arithmetic operations to more complex functions. Our experiments indicate that our model solves stability issues and outperforms the original NALU model in means of arithmetic precision and convergence.}, language = {en} } @inproceedings{SchlosserJarschelDuellietal.2010, author = {Schlosser, Daniel and Jarschel, Michael and Duelli, Michael and Hoßfeld, Tobias and Hoffmann, Klaus and Hoffmann, Marco and Morper, Hans Jochen and Jurca, Dan and Khan, Ashiq}, title = {A Use Case Driven Approach to Network Virtualization}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-55611}, year = {2010}, abstract = {In today's Internet, services are very different in their requirements on the underlying transport network. In the future, this diversity will increase and it will be more difficult to accommodate all services in a single network. A possible approach to cope with this diversity within future networks is the introduction of support for running isolated networks for different services on top of a single shared physical substrate. This would also enable easy network management and ensure an economically sound operation. End-customers will readily adopt this approach as it enables new and innovative services without being expensive. In order to arrive at a concept that enables this kind of network, it needs to be designed around and constantly checked against realistic use cases. In this contribution, we present three use cases for future networks. We describe functional blocks of a virtual network architecture, which are necessary to support these use cases within the network. Furthermore, we discuss the interfaces needed between the functional blocks and consider standardization issues that arise in order to achieve a global consistent control and management structure of virtual networks.}, subject = {Virtualisierung}, language = {en} } @phdthesis{Schlosser2011, author = {Schlosser, Daniel}, title = {Quality of Experience Management in Virtual Future Networks}, doi = {10.25972/OPUS-5719}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69986}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Aktuell beobachten wir eine drastische Vervielf{\"a}ltigung der Dienste und Anwendungen, die das Internet f{\"u}r den Datentransport nutzen. Dabei unterscheiden sich die Anforderungen dieser Dienste an das Netzwerk deutlich. Das Netzwerkmanagement wird durch diese Diversit{\"a}t der nutzenden Dienste aber deutlich erschwert, da es einem Datentransportdienstleister kaum m{\"o}glich ist, die unterschiedlichen Verbindungen zu unterscheiden, ohne den Inhalt der transportierten Daten zu analysieren. Netzwerkvirtualisierung ist eine vielversprechende L{\"o}sung f{\"u}r dieses Problem, da sie es erm{\"o}glicht f{\"u}r verschiedene Dienste unterschiedliche virtuelle Netze auf dem gleichen physikalischen Substrat zu betreiben. Diese Diensttrennung erm{\"o}glicht es, jedes einzelne Netz anwendungsspezifisch zu steuern. Ziel einer solchen Netzsteuerung ist es, sowohl die vom Nutzer erfahrene Dienstg{\"u}te als auch die Kosteneffizienz des Datentransports zu optimieren. Dar{\"u}ber hinaus wird es mit Netzwerkvirtualisierung m{\"o}glich das physikalische Netz so weit zu abstrahieren, dass die aktuell fest verzahnten Rollen von Netzwerkbesitzer und Netzwerkbetreiber entkoppelt werden k{\"o}nnen. Dar{\"u}ber hinaus stellt Netzwerkvirtualisierung sicher, dass unterschiedliche Datennetze, die gleichzeitig auf dem gleichen physikalischen Netz betrieben werden, sich gegenseitig weder beeinflussen noch st{\"o}ren k{\"o}nnen. Diese Arbeit  besch{\"a}ftigt sich mit ausgew{\"a}hlten Aspekten dieses Themenkomplexes und fokussiert sich darauf, ein virtuelles Netzwerk mit bestm{\"o}glicher Dienstqualit{\"a}t f{\"u}r den Nutzer zu betreiben und zu steuern. Daf{\"u}r wird ein Top-down-Ansatz gew{\"a}hlt, der von den Anwendungsf{\"a}llen, einer m{\"o}glichen Netzwerkvirtualisierungs-Architektur und aktuellen M{\"o}glichkeiten der Hardwarevirtualisierung ausgeht. Im Weiteren fokussiert sich die Arbeit dann in Richtung Bestimmung und Optimierung der vom Nutzer erfahrenen Dienstqualit{\"a}t (QoE) auf Applikationsschicht und diskutiert M{\"o}glichkeiten zur Messung und {\"U}berwachung von wesentlichen Netzparametern in virtualisierten Netzen.}, subject = {Netzwerkmanagement}, language = {en} } @article{SchererFleishmanJonesetal.2021, author = {Scherer, Marc and Fleishman, Sarel J. and Jones, Patrik R. and Dandekar, Thomas and Bencurova, Elena}, title = {Computational Enzyme Engineering Pipelines for Optimized Production of Renewable Chemicals}, series = {Frontiers in Bioengineering and Biotechnology}, volume = {9}, journal = {Frontiers in Bioengineering and Biotechnology}, issn = {2296-4185}, doi = {10.3389/fbioe.2021.673005}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-240598}, year = {2021}, abstract = {To enable a sustainable supply of chemicals, novel biotechnological solutions are required that replace the reliance on fossil resources. One potential solution is to utilize tailored biosynthetic modules for the metabolic conversion of CO2 or organic waste to chemicals and fuel by microorganisms. Currently, it is challenging to commercialize biotechnological processes for renewable chemical biomanufacturing because of a lack of highly active and specific biocatalysts. As experimental methods to engineer biocatalysts are time- and cost-intensive, it is important to establish efficient and reliable computational tools that can speed up the identification or optimization of selective, highly active, and stable enzyme variants for utilization in the biotechnological industry. Here, we review and suggest combinations of effective state-of-the-art software and online tools available for computational enzyme engineering pipelines to optimize metabolic pathways for the biosynthesis of renewable chemicals. Using examples relevant for biotechnology, we explain the underlying principles of enzyme engineering and design and illuminate future directions for automated optimization of biocatalysts for the assembly of synthetic metabolic pathways.}, language = {en} } @techreport{SavvidisRothTutsch2022, type = {Working Paper}, author = {Savvidis, Dimitrios and Roth, Robert and Tutsch, Dietmar}, title = {Static Evaluation of a Wheel-Topology for an SDN-based Network Usecase}, series = {W{\"u}rzburg Workshop on Next-Generation Communication Networks (WueWoWas'22)}, journal = {W{\"u}rzburg Workshop on Next-Generation Communication Networks (WueWoWas'22)}, doi = {10.25972/OPUS-28071}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-280715}, pages = {3}, year = {2022}, abstract = {The increased occurrence of Software-Defined-Networking (SDN) not only improves the dynamics and maintenance of network architectures, but also opens up new use cases and application possibilities. Based on these observations, we propose a new network topology consisting of a star and a ring topology. This hybrid topology will be called wheel topology in this paper. We have considered the static characteristics of the wheel topology and compare them with known other topologies.}, subject = {Datennetz}, language = {en} } @phdthesis{Sauer2010, author = {Sauer, Markus}, title = {Mixed-Reality for Enhanced Robot Teleoperation}, isbn = {978-3-923959-67-9}, doi = {10.25972/OPUS-4666}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-55083}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {In den letzten Jahren ist die Forschung in der Robotik soweit fortgeschritten, dass die Mensch-Maschine Schnittstelle zunehmend die kritischste Komponente f{\"u}r eine hohe Gesamtperformanz von Systemen zur Navigation und Koordination von Robotern wird. In dieser Dissertation wird untersucht wie Mixed-Reality Technologien f{\"u}r Nutzerschnittstellen genutzt werden k{\"o}nnen, um diese Gesamtperformanz zu erh{\"o}hen. Hierzu werden Konzepte und Technologien entwickelt, die durch Evaluierung mit Nutzertest ein optimiertes und anwenderbezogenes Design von Mixed-Reality Nutzerschnittstellen erm{\"o}glichen. Er werden somit sowohl die technische Anforderungen als auch die menschlichen Faktoren f{\"u}r ein konsistentes Systemdesign ber{\"u}cksichtigt. Nach einer detaillierten Problemanalyse und der Erstellung eines Systemmodels, das den Menschen als Schl{\"u}sselkomponente mit einbezieht, wird zun{\"a}chst die Anwendung der neuartigen 3D-Time-of-Flight Kamera zur Navigation von Robotern, aber auch f{\"u}r den Einsatz in Mixed-Reality Schnittstellen analysiert und optimiert. Weiterhin wird gezeigt, wie sich der Netzwerkverkehr des Videostroms als wichtigstes Informationselement der meisten Nutzerschnittstellen f{\"u}r die Navigationsaufgabe auf der Netzwerk Applikationsebene in typischen Multi-Roboter Netzwerken mit dynamischen Topologien und Lastsituation optimieren l{\"a}sst. Hierdurch ist es m{\"o}glich in sonst in sonst typischen Ausfallszenarien den Videostrom zu erhalten und die Bildrate zu stabilisieren. Diese fortgeschrittenen Technologien werden dann auch dem entwickelten Konzept der generischen 3D Mixed Reality Schnittselle eingesetzt. Dieses Konzept erm{\"o}glicht eine integrierte 3D Darstellung der verf{\"u}gbaren Information, so dass r{\"a}umliche Beziehungen von Informationen aufrechterhalten werden und somit die Anzahl der mentalen Transformationen beim menschlichen Bediener reduziert wird. Gleichzeitig werden durch diesen Ansatz auch immersive Stereo Anzeigetechnologien unterst{\"u}tzt, welche zus{\"a}tzlich das r{\"a}umliche Verst{\"a}ndnis der entfernten Situation f{\"o}rdern. Die in der Dissertation vorgestellten und evaluierten Ans{\"a}tze nutzen auch die Tatsache, dass sich eine lokale Autonomie von Robotern heute sehr robust realisieren l{\"a}sst. Dies wird zum Beispiel zur Realisierung eines Assistenzsystems mit variabler Autonomie eingesetzt. Hierbei erh{\"a}lt der Fernbediener {\"u}ber eine Kraftr{\"u}ckkopplung kombiniert mit einer integrierten Augmented Reality Schnittstelle, einen Eindruck {\"u}ber die Situation am entfernten Arbeitsbereich, aber auch {\"u}ber die aktuelle Navigationsintention des Roboters. Die durchgef{\"u}hrten Nutzertests belegen die signifikante Steigerung der Navigationsperformanz durch den entwickelten Ansatz. Die robuste lokale Autonomie erm{\"o}glicht auch den in der Dissertation eingef{\"u}hrten Ansatz der pr{\"a}diktiven Mixed-Reality Schnittstelle. Die durch diesen Ansatz entkoppelte Regelschleife {\"u}ber den Menschen erm{\"o}glicht es die Sichtbarkeit von unvermeidbaren Systemverz{\"o}gerungen signifikant zu reduzieren. Zus{\"a}tzlich k{\"o}nnen durch diesen Ansatz beide f{\"u}r die Navigation hilfreichen Blickwinkel in einer 3D-Nutzerschnittstelle kombiniert werden - der exozentrische Blickwinkel und der egozentrische Blickwinkel als Augmented Reality Sicht.}, subject = {Mobiler Roboter}, language = {en} } @phdthesis{Saska2009, author = {Saska, Martin}, title = {Trajectory planning and optimal control for formations of autonomous robots}, isbn = {978-3-923959-56-3}, doi = {10.25972/OPUS-4622}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-53175}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2009}, abstract = {In this thesis, we present novel approaches for formation driving of nonholonomic robots and optimal trajectory planning to reach a target region. The methods consider a static known map of the environment as well as unknown and dynamic obstacles detected by sensors of the formation. The algorithms are based on leader following techniques, where the formation of car-like robots is maintained in a shape determined by curvilinear coordinates. Beyond this, the general methods of formation driving are specialized and extended for an application of airport snow shoveling. Detailed descriptions of the algorithms complemented by relevant stability and convergence studies will be provided in the following chapters. Furthermore, discussions of the applicability will be verified by various simulations in existing robotic environments and also by a hardware experiment.}, subject = {Autonomer Roboter}, language = {en} } @inproceedings{SanusiKlemke2021, author = {Sanusi, Khaleel Asyraaf Mat and Klemke, Roland}, title = {Immersive Multimodal Environments for Psychomotor Skills Training}, series = {Proceedings of the 1st Games Technology Summit}, booktitle = {Proceedings of the 1st Games Technology Summit}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-246016}, pages = {9-15}, year = {2021}, abstract = {Modern immersive multimodal technologies enable the learners to completely get immersed in various learning situations in a way that feels like experiencing an authentic learning environment. These environments also allow the collection of multimodal data, which can be used with artificial intelligence to further improve the immersion and learning outcomes. The use of artificial intelligence has been widely explored for the interpretation of multimodal data collected from multiple sensors, thus giving insights to support learners' performance by providing personalised feedback. In this paper, we present a conceptual approach for creating immersive learning environments, integrated with multi-sensor setup to help learners improve their psychomotor skills in a remote setting.}, language = {en} }