@phdthesis{Baunach2012, author = {Baunach, Marcel}, title = {Advances in Distributed Real-Time Sensor/Actuator Systems Operation - Operating Systems, Communication, and Application Design Concepts -}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-76489}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2012}, abstract = {This work takes a close look at several quite different research areas related to the design of networked embedded sensor/actuator systems. The variety of the topics illustrates the potential complexity of current sensor network applications; especially when enriched with actuators for proactivity and environmental interaction. Besides their conception, development, installation and long-term operation, we'll mainly focus on more "low-level" aspects: Compositional hardware and software design, task cooperation and collaboration, memory management, and real-time operation will be addressed from a local node perspective. In contrast, inter-node synchronization, communication, as well as sensor data acquisition, aggregation, and fusion will be discussed from a rather global network view. The diversity in the concepts was intentionally accepted to finally facilitate the reliable implementation of truly complex systems. In particular, these should go beyond the usual "sense and transmit of sensor data", but show how powerful today's networked sensor/actuator systems can be despite of their low computational performance and constrained hardware: If their resources are only coordinated efficiently!}, subject = {Eingebettetes System}, language = {en} } @article{SchaffarczykKoehnOggianoetal.2022, author = {Schaffarczyk, Alois and Koehn, Silas and Oggiano, Luca and Schaffarczyk, Kai}, title = {Aerodynamic benefits by optimizing cycling posture}, series = {Applied Sciences}, volume = {12}, journal = {Applied Sciences}, number = {17}, issn = {2076-3417}, doi = {10.3390/app12178475}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-285942}, year = {2022}, abstract = {An approach to aerodynamically optimizing cycling posture and reducing drag in an Ironman (IM) event was elaborated. Therefore, four commonly used positions in cycling were investigated and simulated for a flow velocity of 10 m/s and yaw angles of 0-20° using OpenFoam-based Nabla Flow CFD simulation software software. A cyclist was scanned using an IPhone 12, and a special-purpose meshing software BLENDER was used. Significant differences were observed by changing and optimizing the cyclist's posture. Aerodynamic drag coefficient (CdA) varies by more than a factor of 2, ranging from 0.214 to 0.450. Within a position, the CdA tends to increase slightly at yaw angles of 5-10° and decrease at higher yaw angles compared to a straight head wind, except for the time trial (TT) position. The results were applied to the IM Hawaii bike course (180 km), estimating a constant power output of 300 W. Including the wind distributions, two different bike split models for performance prediction were applied. Significant time saving of roughly 1 h was found. Finally, a machine learning approach to deduce 3D triangulation for specific body shapes from 2D pictures was tested.}, language = {en} } @phdthesis{Eichelberger2005, author = {Eichelberger, Holger}, title = {Aesthetics and automatic layout of UML class diagrams}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-14831}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2005}, abstract = {In the last years, visual methods have been introduced in industrial software production and teaching of software engineering. In particular, the international standardization of a graphical software engineering language, the Unified Modeling Language (UML) was a reason for this tendency. Unfortunately, various problems exist in concrete realizations of tools, e.g. due to a missing compliance to the standard. One problem is the automatic layout, which is required for a consistent automatic software design. The thesis derives reasons and criteria for an automatic layout method, which produces drawings of UML class diagrams according to the UML specification and issues of human computer interaction, e.g. readability. A unique set of aesthetic criteria is combined from four different disciplines involved in this topic. Based on these aethetic rules, a hierarchical layout algorithm is developed, analyzed, measured by specialized measuring techniques and compared to related work. Then, the realization of the algorithm as a Java framework is given as an architectural description. Finally, adaptions to anticipated future changes of the UML, improvements of the framework and example drawings of the implementation are given.}, subject = {URL}, language = {en} } @article{BartlWenningerWolfetal.2021, author = {Bartl, Andrea and Wenninger, Stephan and Wolf, Erik and Botsch, Mario and Latoschik, Marc Erich}, title = {Affordable but not cheap: a case study of the effects of two 3D-reconstruction methods of virtual humans}, series = {Frontiers in Virtual Reality}, volume = {2}, journal = {Frontiers in Virtual Reality}, doi = {10.3389/frvir.2021.694617}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-260492}, year = {2021}, abstract = {Realistic and lifelike 3D-reconstruction of virtual humans has various exciting and important use cases. Our and others' appearances have notable effects on ourselves and our interaction partners in virtual environments, e.g., on acceptance, preference, trust, believability, behavior (the Proteus effect), and more. Today, multiple approaches for the 3D-reconstruction of virtual humans exist. They significantly vary in terms of the degree of achievable realism, the technical complexities, and finally, the overall reconstruction costs involved. This article compares two 3D-reconstruction approaches with very different hardware requirements. The high-cost solution uses a typical complex and elaborated camera rig consisting of 94 digital single-lens reflex (DSLR) cameras. The recently developed low-cost solution uses a smartphone camera to create videos that capture multiple views of a person. Both methods use photogrammetric reconstruction and template fitting with the same template model and differ in their adaptation to the method-specific input material. Each method generates high-quality virtual humans ready to be processed, animated, and rendered by standard XR simulation and game engines such as Unreal or Unity. We compare the results of the two 3D-reconstruction methods in an immersive virtual environment against each other in a user study. Our results indicate that the virtual humans from the low-cost approach are perceived similarly to those from the high-cost approach regarding the perceived similarity to the original, human-likeness, beauty, and uncanniness, despite significant differences in the objectively measured quality. The perceived feeling of change of the own body was higher for the low-cost virtual humans. Quality differences were perceived more strongly for one's own body than for other virtual humans.}, language = {en} } @techreport{GrigorjewDiederichHossfeldetal.2022, type = {Working Paper}, author = {Grigorjew, Alexej and Diederich, Philip and Hoßfeld, Tobias and Kellerer, Wolfgang}, title = {Affordable Measurement Setups for Networking Device Latency with Sub-Microsecond Accuracy}, 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-28075}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-280751}, pages = {5}, year = {2022}, abstract = {This document presents a networking latency measurement setup that focuses on affordability and universal applicability, and can provide sub-microsecond accuracy. It explains the prerequisites, hardware choices, and considerations to respect during measurement. In addition, it discusses the necessity for exhaustive latency measurements when dealing with high availability and low latency requirements. Preliminary results show that the accuracy is within ±0.02 μs when used with the Intel I350-T2 network adapter.}, subject = {Datennetz}, language = {en} } @phdthesis{Baumeister2004, author = {Baumeister, Joachim}, title = {Agile development of diagnostic knowledge systems}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9698}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2004}, abstract = {The success of diagnostic knowledge systems has been proved over the last decades. Nowadays, intelligent systems are embedded in machines within various domains or are used in interaction with a user for solving problems. However, although such systems have been applied very successfully the development of a knowledge system is still a critical issue. Similarly to projects dealing with customized software at a highly innovative level a precise specification often cannot be given in advance. Moreover, necessary requirements of the knowledge system can be defined not until the project has been started or are changing during the development phase. Many success factors depend on the feedback given by users, which can be provided if preliminary demonstrations of the system can be delivered as soon as possible, e.g., for interactive systems validation the duration of the system dialog. This thesis motivates that classical, document-centered approaches cannot be applied in such a setting. We cope with this problem by introducing an agile process model for developing diagnostic knowledge systems, mainly inspired by the ideas of the eXtreme Programming methodology known in software engineering. The main aim of the presented work is to simplify the engineering process for domain specialists formalizing the knowledge themselves. The engineering process is supported at a primary level by the introduction of knowledge containers, that define an organized view of knowledge contained in the system. Consequently, we provide structured procedures as a recommendation for filling these containers. The actual knowledge is acquired and formalized right from start, and the integration to runnable knowledge systems is done continuously in order to allow for an early and concrete feedback. In contrast to related prototyping approaches the validity and maintainability of the collected knowledge is ensured by appropriate test methods and restructuring techniques, respectively. Additionally, we propose learning methods to support the knowledge acquisition process sufficiently. The practical significance of the process model strongly depends on the available tools supporting the application of the process model. We present the system family d3web and especially the system d3web.KnowME as a highly integrated development environment for diagnostic knowledge systems. The process model and its activities, respectively, are evaluated in two real life applications: in a medical and in an environmental project the benefits of the agile development are clearly demonstrated.}, language = {en} } @phdthesis{Boehler2005, author = {B{\"o}hler, Elmar}, title = {Algebraic closures in complexity theory}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-16106}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2005}, abstract = {We use algebraic closures and structures which are derived from these in complexity theory. We classify problems with Boolean circuits and Boolean constraints according to their complexity. We transfer algebraic structures to structural complexity. We use the generation problem to classify important complexity classes.}, subject = {Komplexit{\"a}tstheorie}, language = {en} } @article{ElsebergBorrmannNuechter2013, author = {Elseberg, Jan and Borrmann, Dorit and N{\"u}chter, Andreas}, title = {Algorithmic Solutions for Computing Precise Maximum Likelihood 3D Point Clouds from Mobile Laser Scanning Platforms}, series = {Remote Sensing}, volume = {5}, journal = {Remote Sensing}, number = {11}, doi = {10.3390/rs5115871}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-130478}, pages = {5871-5906}, year = {2013}, abstract = {Mobile laser scanning puts high requirements on the accuracy of the positioning systems and the calibration of the measurement system. We present a novel algorithmic approach for calibration with the goal of improving the measurement accuracy of mobile laser scanners. We describe a general framework for calibrating mobile sensor platforms that estimates all configuration parameters for any arrangement of positioning sensors, including odometry. In addition, we present a novel semi-rigid Simultaneous Localization and Mapping (SLAM) algorithm that corrects the vehicle position at every point in time along its trajectory, while simultaneously improving the quality and precision of the entire acquired point cloud. Using this algorithm, the temporary failure of accurate external positioning systems or the lack thereof can be compensated for. We demonstrate the capabilities of the two newly proposed algorithms on a wide variety of datasets.}, language = {en} } @phdthesis{Zink2024, author = {Zink, Johannes}, title = {Algorithms for Drawing Graphs and Polylines with Straight-Line Segments}, doi = {10.25972/OPUS-35475}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-354756}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2024}, abstract = {Graphs provide a key means to model relationships between entities. They consist of vertices representing the entities, and edges representing relationships between pairs of entities. To make people conceive the structure of a graph, it is almost inevitable to visualize the graph. We call such a visualization a graph drawing. Moreover, we have a straight-line graph drawing if each vertex is represented as a point (or a small geometric object, e.g., a rectangle) and each edge is represented as a line segment between its two vertices. A polyline is a very simple straight-line graph drawing, where the vertices form a sequence according to which the vertices are connected by edges. An example of a polyline in practice is a GPS trajectory. The underlying road network, in turn, can be modeled as a graph. This book addresses problems that arise when working with straight-line graph drawings and polylines. In particular, we study algorithms for recognizing certain graphs representable with line segments, for generating straight-line graph drawings, and for abstracting polylines. In the first part, we first examine, how and in which time we can decide whether a given graph is a stick graph, that is, whether its vertices can be represented as vertical and horizontal line segments on a diagonal line, which intersect if and only if there is an edge between them. We then consider the visual complexity of graphs. Specifically, we investigate, for certain classes of graphs, how many line segments are necessary for any straight-line graph drawing, and whether three (or more) different slopes of the line segments are sufficient to draw all edges. Last, we study the question, how to assign (ordered) colors to the vertices of a graph with both directed and undirected edges such that no neighboring vertices get the same color and colors are ascending along directed edges. Here, the special property of the considered graph is that the vertices can be represented as intervals that overlap if and only if there is an edge between them. The latter problem is motivated by an application in automated drawing of cable plans with vertical and horizontal line segments, which we cover in the second part. We describe an algorithm that gets the abstract description of a cable plan as input, and generates a drawing that takes into account the special properties of these cable plans, like plugs and groups of wires. We then experimentally evaluate the quality of the resulting drawings. In the third part, we study the problem of abstracting (or simplifying) a single polyline and a bundle of polylines. In this problem, the objective is to remove as many vertices as possible from the given polyline(s) while keeping each resulting polyline sufficiently similar to its original course (according to a given similarity measure).}, subject = {Graphenzeichnen}, language = {en} } @article{TsouliasJoerissenNuechter2022, author = {Tsoulias, Nikos and J{\"o}rissen, Sven and N{\"u}chter, Andreas}, title = {An approach for monitoring temperature on fruit surface by means of thermal point cloud}, series = {MethodsX}, volume = {9}, journal = {MethodsX}, issn = {2215-0161}, doi = {10.1016/j.mex.2022.101712}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-300270}, year = {2022}, abstract = {Heat and excessive solar radiation can produce abiotic stresses during apple maturation, resulting fruit quality. Therefore, the monitoring of temperature on fruit surface (FST) over the growing period can allow to identify thresholds, above of which several physiological disorders such as sunburn may occur in apple. The current approaches neglect spatial variation of FST and have reduced repeatability, resulting in unreliable predictions. In this study, LiDAR laser scanning and thermal imaging were employed to detect the temperature on fruit surface by means of 3D point cloud. A process for calibrating the two sensors based on an active board target and producing a 3D thermal point cloud was suggested. After calibration, the sensor system was utilised to scan the fruit trees, while temperature values assigned in the corresponding 3D point cloud were based on the extrinsic calibration. Whereas a fruit detection algorithm was performed to segment the FST from each apple. • The approach allows the calibration of LiDAR laser scanner with thermal camera in order to produce a 3D thermal point cloud. • The method can be applied in apple trees for segmenting FST in 3D. Whereas the approach can be utilised to predict several physiological disorders including sunburn on fruit surface.}, language = {en} }