TY - JOUR A1 - Dumic, Emil A1 - Bjelopera, Anamaria A1 - Nüchter, Andreas T1 - Dynamic point cloud compression based on projections, surface reconstruction and video compression JF - Sensors N2 - In this paper we will present a new dynamic point cloud compression based on different projection types and bit depth, combined with the surface reconstruction algorithm and video compression for obtained geometry and texture maps. Texture maps have been compressed after creating Voronoi diagrams. Used video compression is specific for geometry (FFV1) and texture (H.265/HEVC). Decompressed point clouds are reconstructed using a Poisson surface reconstruction algorithm. Comparison with the original point clouds was performed using point-to-point and point-to-plane measures. Comprehensive experiments show better performance for some projection maps: cylindrical, Miller and Mercator projections. KW - 3DTK toolkit KW - map projections KW - point cloud compression KW - point-to-point measure KW - point-to-plane measure KW - Poisson surface reconstruction KW - octree Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-252231 SN - 1424-8220 VL - 22 IS - 1 ER - TY - JOUR A1 - Buchin, Kevin A1 - Buchin, Maike A1 - Byrka, Jaroslaw A1 - Nöllenburg, Martin A1 - Okamoto, Yoshio A1 - Silveira, Rodrigo I. A1 - Wolff, Alexander T1 - Drawing (Complete) Binary Tanglegrams JF - Algorithmica N2 - A binary tanglegram is a drawing of a pair of rooted binary trees whose leaf sets are in one-to-one correspondence; matching leaves are connected by inter-tree edges. For applications, for example, in phylogenetics, it is essential that both trees are drawn without edge crossings and that the inter-tree edges have as few crossings as possible. It is known that finding a tanglegram with the minimum number of crossings is NP-hard and that the problem is fixed-parameter tractable with respect to that number. We prove that under the Unique Games Conjecture there is no constant-factor approximation for binary trees. We show that the problem is NP-hard even if both trees are complete binary trees. For this case we give an O(n 3)-time 2-approximation and a new, simple fixed-parameter algorithm. We show that the maximization version of the dual problem for binary trees can be reduced to a version of MaxCut for which the algorithm of Goemans and Williamson yields a 0.878-approximation. KW - NP-hardness KW - crossing minimization KW - binary tanglegram KW - approximation algorithm KW - fixed-parameter tractability Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-124622 VL - 62 ER - TY - INPR A1 - Nassourou, Mohamadou T1 - Doing Webservices Composition by Content-based Mashup: Example of a Web-based Simulator for Itinerary Planning N2 - Webservices composition is traditionally carried out using composition technologies such as Business Process Execution Language (BPEL) [1] and Web Service Choreography Interface (WSCI) [2]. The composition technology involves the process of web service discovery, invocation, and composition. However these technologies are not easy and flexible enough because they are mainly developer-centric. Moreover majority of websites have not yet embarked into the world of web service, although they have very important and useful information to offer. Is it because they have not understood the usefulness of web services or is it because of the costs? Whatever might be the answers to these questions, time and money are definitely required in order to create and offer web services. To avoid these expenditures, wrappers [7] to automatically generate webservices from websites would be a cheaper and easier solution. Mashups offer a different way of doing webservices composition. In web environment a Mashup is a web application that brings together data from several sources using webservices, APIs, wrappers and so on, in order to create entirely a new application that was not provided before. This paper presents first an overview of Mashups and the process of web service invocation and composition based on Mashup, then describes an example of a web-based simulator for navigation system in Germany. KW - Mashup KW - Wrapper KW - Mashup KW - Webservice Composition KW - Wrappers Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-50036 ER - TY - THES A1 - Houshiar, Hamidreza T1 - Documentation and mapping with 3D point cloud processing T1 - Dokumentation und Kartierung mittels 3D-Punktwolkenverarbeitung N2 - 3D point clouds are a de facto standard for 3D documentation and modelling. The advances in laser scanning technology broadens the usability and access to 3D measurement systems. 3D point clouds are used in many disciplines such as robotics, 3D modelling, archeology and surveying. Scanners are able to acquire up to a million of points per second to represent the environment with a dense point cloud. This represents the captured environment with a very high degree of detail. The combination of laser scanning technology with photography adds color information to the point clouds. Thus the environment is represented more realistically. Full 3D models of environments, without any occlusion, require multiple scans. Merging point clouds is a challenging process. This thesis presents methods for point cloud registration based on the panorama images generated from the scans. Image representation of point clouds introduces 2D image processing methods to 3D point clouds. Several projection methods for the generation of panorama maps of point clouds are presented in this thesis. Additionally, methods for point cloud reduction and compression based on the panorama maps are proposed. Due to the large amounts of data generated from the 3D measurement systems these methods are necessary to improve the point cloud processing, transmission and archiving. This thesis introduces point cloud processing methods as a novel framework for the digitisation of archeological excavations. The framework replaces the conventional documentation methods for excavation sites. It employs point clouds for the generation of the digital documentation of an excavation with the help of an archeologist on-site. The 3D point cloud is used not only for data representation but also for analysis and knowledge generation. Finally, this thesis presents an autonomous indoor mobile mapping system. The mapping system focuses on the sensor placement planning method. Capturing a complete environment requires several scans. The sensor placement planning method solves for the minimum required scans to digitise large environments. Combining this method with a navigation system on a mobile robot platform enables it to acquire data fully autonomously. This thesis introduces a novel hole detection method for point clouds to detect obscured parts of a captured environment. The sensor placement planning method selects the next scan position with the most coverage of the obscured environment. This reduces the required number of scans. The navigation system on the robot platform consist of path planning, path following and obstacle avoidance. This guarantees the safe navigation of the mobile robot platform between the scan positions. The sensor placement planning method is designed as a stand alone process that could be used with a mobile robot platform for autonomous mapping of an environment or as an assistant tool for the surveyor on scanning projects. N2 - 3D-Punktwolken sind der de facto Standard bei der Dokumentation und Modellierung in 3D. Die Fortschritte in der Laserscanningtechnologie erweitern die Verwendbarkeit und die Verfügbarkeit von 3D-Messsystemen. 3D-Punktwolken werden in vielen Disziplinen verwendet, wie z.B. in der Robotik, 3D-Modellierung, Archäologie und Vermessung. Scanner sind in der Lage bis zu einer Million Punkte pro Sekunde zu erfassen, um die Umgebung mit einer dichten Punktwolke abzubilden und mit einem hohen Detaillierungsgrad darzustellen. Die Kombination der Laserscanningtechnologie mit Methoden der Photogrammetrie fügt den Punktwolken Farbinformationen hinzu. Somit wird die Umgebung realistischer dargestellt. Vollständige 3D-Modelle der Umgebung ohne Verschattungen benötigen mehrere Scans. Punktwolken zusammenzufügen ist eine anspruchsvolle Aufgabe. Diese Arbeit stellt Methoden zur Punktwolkenregistrierung basierend auf aus den Scans erzeugten Panoramabildern vor. Die Darstellung einer Punktwolke als Bild bringt Methoden der 2D-Bildverarbeitung an 3D-Punktwolken heran. Der Autor stellt mehrere Projektionsmethoden zur Erstellung von Panoramabildern aus 3D-Punktwolken vor. Außerdem werden Methoden zur Punktwolkenreduzierung und -kompression basierend auf diesen Panoramabildern vorgeschlagen. Aufgrund der großen Datenmenge, die von 3D-Messsystemen erzeugt wird, sind diese Methoden notwendig, um die Punktwolkenverarbeitung, -übertragung und -archivierung zu verbessern. Diese Arbeit präsentiert Methoden der Punktwolkenverarbeitung als neuartige Ablaufstruktur für die Digitalisierung von archäologischen Ausgrabungen. Durch diesen Ablauf werden konventionellen Methoden auf Ausgrabungsstätten ersetzt. Er verwendet Punktwolken für die Erzeugung der digitalen Dokumentation einer Ausgrabung mithilfe eines Archäologen vor Ort. Die 3D-Punktwolke kommt nicht nur für die Anzeige der Daten, sondern auch für die Analyse und Wissensgenerierung zum Einsatz. Schließlich stellt diese Arbeit ein autonomes Indoor-Mobile-Mapping-System mit Fokus auf der Positionsplanung des Messgeräts vor. Die Positionsplanung bestimmt die minimal benötigte Anzahl an Scans, um großflächige Umgebungen zu digitalisieren. Kombiniert mit einem Navigationssystem auf einer mobilen Roboterplattform ermöglicht diese Methode die vollautonome Datenerfassung. Diese Arbeit stellt eine neuartige Erkennungsmethode für Lücken in Punktwolken vor, um verdeckte Bereiche der erfassten Umgebung zu bestimmen. Die Positionsplanung bestimmt als nächste Scanposition diejenige mit der größten Abdeckung der verdeckten Umgebung. Das Navigationssystem des Roboters besteht aus der Pfadplanung, der Pfadverfolgung und einer Hindernisvermeidung um eine sichere Fortbewegung der mobilen Roboterplattform zwischen den Scanpositionen zu garantieren. Die Positionsplanungsmethode wurde als eigenständiges Verfahren entworfen, das auf einer mobilen Roboterplattform zur autonomen Kartierung einer Umgebung zum Einsatz kommen oder einem Vermesser bei einem Scanprojekt als Unterstützung dienen kann. T3 - Forschungsberichte in der Robotik = Research Notes in Robotics - 12 KW - 3D Punktwolke KW - Robotik KW - Registrierung KW - 3D Pointcloud KW - Feature Based Registration KW - Compression KW - Computer Vision KW - Robotics KW - Panorama Images Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-144493 SN - 978-3-945459-14-0 ER - TY - JOUR A1 - Petschke, Danny A1 - Staab, Torsten E.M. T1 - DLTPulseGenerator: a library for the simulation of lifetime spectra based on detector-output pulses JF - SoftwareX N2 - The quantitative analysis of lifetime spectra relevant in both life and materials sciences presents one of the ill-posed inverse problems and, hence, leads to most stringent requirements on the hardware specifications and the analysis algorithms. Here we present DLTPulseGenerator, a library written in native C++ 11, which provides a simulation of lifetime spectra according to the measurement setup. The simulation is based on pairs of non-TTL detector output-pulses. Those pulses require the Constant Fraction Principle (CFD) for the determination of the exact timing signal and, thus, the calculation of the time difference i.e. the lifetime. To verify the functionality, simulation results were compared to experimentally obtained data using Positron Annihilation Lifetime Spectroscopy (PALS) on pure tin. KW - lifetime spectroscopy KW - signal processing KW - pulse simulation Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-176883 VL - 7 ER - TY - JOUR A1 - Krueger, Beate A1 - Friedrich, Torben A1 - Förster, Frank A1 - Bernhardt, Jörg A1 - Gross, Roy A1 - Dandekar, Thomas T1 - Different evolutionary modifications as a guide to rewire two-component systems JF - Bioinformatics and Biology Insights N2 - Two-component systems (TCS) are short signalling pathways generally occurring in prokaryotes. They frequently regulate prokaryotic stimulus responses and thus are also of interest for engineering in biotechnology and synthetic biology. The aim of this study is to better understand and describe rewiring of TCS while investigating different evolutionary scenarios. Based on large-scale screens of TCS in different organisms, this study gives detailed data, concrete alignments, and structure analysis on three general modification scenarios, where TCS were rewired for new responses and functions: (i) exchanges in the sequence within single TCS domains, (ii) exchange of whole TCS domains; (iii) addition of new components modulating TCS function. As a result, the replacement of stimulus and promotor cassettes to rewire TCS is well defined exploiting the alignments given here. The diverged TCS examples are non-trivial and the design is challenging. Designed connector proteins may also be useful to modify TCS in selected cases. KW - histidine kinase KW - connector KW - Mycoplasma KW - engineering KW - promoter KW - sensor KW - response regulator KW - synthetic biology KW - sequence alignment Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-123647 N1 - This is an open access article. Unrestricted non-commercial use is permitted provided the original work is properly cited. VL - 6 ER - TY - THES A1 - Binder, Andreas T1 - Die stochastische Wissenschaft und zwei Teilsysteme eines Web-basierten Informations- und Anwendungssystems zu ihrer Etablierung T1 - The stochastic science and two subsystems of a web-based information and application system for its establishment N2 - Das stochastische Denken, die Bernoullische Stochastik und dessen informationstechnologische Umsetzung, namens Stochastikon stellen die Grundlage für das Verständnis und die erfolgreiche Nutzung einer stochastischen Wissenschaft dar. Im Rahmen dieser Arbeit erfolgt eine Klärung des Begriffs des stochastischen Denkens, eine anschauliche Darstellung der von Elart von Collani entwickelten Bernoullischen Stochastik und eine Beschreibung von Stochastikon. Dabei werden sowohl das Gesamtkonzept von Stochastikon, sowie die Ziele, Aufgaben und die Realisierung der beiden Teilsysteme namens Mentor und Encyclopedia vorgestellt. Das stochastische Denken erlaubt eine realitätsnahe Sichtweise der Dinge, d.h. eine Sichtweise, die mit den menschlichen Beobachtungen und Erfahrungen im Einklang steht und somit die Unsicherheit über zukünftige Entwicklungen berücksichtigt. Der in diesem Kontext verwendete Begriff der Unsicherheit bezieht sich ausschließlich auf zukünftige Entwicklungen und äußert sich in Variabilität. Quellen der Unsicherheit sind einerseits die menschliche Ignoranz und andererseits der Zufall. Unter Ignoranz wird hierbei die Unwissenheit des Menschen über die unbekannten, aber feststehenden Fakten verstanden, die die Anfangsbedingungen der zukünftigen Entwicklung repräsentieren. Die Bernoullische Stochastik liefert ein Regelwerk und ermöglicht die Entwicklung eines quantitativen Modells zur Beschreibung der Unsicherheit und expliziter Einbeziehung der beiden Quellen Ignoranz und Zufall. Das Modell trägt den Namen Bernoulli-Raum und bildet die Grundlage für die Herleitung quantitativer Verfahren, um zuverlässige und genaue Aussagen sowohl über die nicht-existente zufällige Zukunft (Vorhersageverfahren), als auch über die unbekannte feststehende Vergangenheit (Messverfahren). Das Softwaresystem Stochastikon implementiert die Bernoullische Stochastik in Form einer Reihe autarker, miteinander kommunizierender Teilsysteme. Ziel des Teilsystems Encyclopedia ist die Bereitstellung und Bewertung stochastischen Wissens. Das Teilsystem Mentor dient der Unterstützung des Anwenders bei der Problemlösungsfindung durch Identifikation eines richtigen Modells bzw. eines korrekten Bernoulli-Raums. Der Lösungsfindungsprozess selber enthält keinerlei Unsicherheit. Die ganze Unsicherheit steckt in der Lösung, d.h. im Bernoulli-Raum, der explizit die vorhandene Unwissenheit (Ignoranz) und den vorliegenden Zufall abdeckend enthält. N2 - Stochastic thinking, Bernoulli stochastics and its information technological realization, called Stochastikon, represent the basis for understanding and successfully utilizing stochastic science. This thesis defines the concept of stochastic thinking, introduces Bernoulli stochastics, which has been developed by Elart von Collani, and describes the IT system Stochastikon. The concept and the design of Stochastikon are outlined and the aims, tasks and realizations of the two subsystems Mentor and Encyclopedia are given in detail. Stochastic thinking enables a realistic view of reality. This means a view, which is in agreement with observation and experience and, thus, takes into account uncertainty about future developments. In this context the term of uncertainty is used exclusively with respect to future development and materializes in variability. Sources of uncertainty are on the one hand human ignorance about fixed facts on the one hand and randomness on the other. Bernoulli stochastics makes available a set of rules for developing a quantitative model about uncertainty taking particularly into account the two sources ignorance and randomness. The model is called Bernoulli-Space, which is the basis for reliable and precise quantitative procedures for statements about the random future (prediction procedures) as well as about the unknown fixed past (measurement procedures). The software system, called Stochastikon, implements Bernoulli stochastics based on a set of self-sustained intercommunicating subsystems. The Subsystem Encyclopedia makes stochastical knowledge available, while the Subsystem Mentor supports the user for solving (stochastic) problems by identifying the correct model respectively correct Bernoulli-Space. The problem solving process is free of uncertainty, because all uncertainty is modelled by Bernoulli-space. KW - Stochastik KW - stochastisches Denken KW - Bernoullische Stochastik KW - Bernoulli-Raum KW - Stochastikon KW - stochastic thinking KW - Bernoulli stochastics KW - Bernoullispace KW - Stochastikon Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-26146 ER - TY - JOUR A1 - Wienrich, Carolin A1 - Carolus, Astrid T1 - Development of an Instrument to Measure Conceptualizations and Competencies About Conversational Agents on the Example of Smart Speakers JF - Frontiers in Computer Science N2 - The concept of digital literacy has been introduced as a new cultural technique, which is regarded as essential for successful participation in a (future) digitized world. Regarding the increasing importance of AI, literacy concepts need to be extended to account for AI-related specifics. The easy handling of the systems results in increased usage, contrasting limited conceptualizations (e.g., imagination of future importance) and competencies (e.g., knowledge about functional principles). In reference to voice-based conversational agents as a concrete application of AI, the present paper aims for the development of a measurement to assess the conceptualizations and competencies about conversational agents. In a first step, a theoretical framework of “AI literacy” is transferred to the context of conversational agent literacy. Second, the “conversational agent literacy scale” (short CALS) is developed, constituting the first attempt to measure interindividual differences in the “(il) literate” usage of conversational agents. 29 items were derived, of which 170 participants answered. An explanatory factor analysis identified five factors leading to five subscales to assess CAL: storage and transfer of the smart speaker’s data input; smart speaker’s functional principles; smart speaker’s intelligent functions, learning abilities; smart speaker’s reach and potential; smart speaker’s technological (surrounding) infrastructure. Preliminary insights into construct validity and reliability of CALS showed satisfying results. Third, using the newly developed instrument, a student sample’s CAL was assessed, revealing intermediated values. Remarkably, owning a smart speaker did not lead to higher CAL scores, confirming our basic assumption that usage of systems does not guarantee enlightened conceptualizations and competencies. In sum, the paper contributes to the first insights into the operationalization and understanding of CAL as a specific subdomain of AI-related competencies. KW - artificial intelligence literacy KW - artificial intelligence education KW - voice-based artificial intelligence KW - conversational agents KW - measurement Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-260198 VL - 3 ER - TY - THES A1 - Kaempgen, Benedikt T1 - Deskriptives Data-Mining für Entscheidungsträger: Eine Mehrfachfallstudie T1 - Descriptive data mining for decision-makers: a multiple case study N2 - Das Potenzial der Wissensentdeckung in Daten wird häufig nicht ausgenutzt, was hauptsächlich auf Barrieren zwischen dem Entwicklerteam und dem Endnutzer des Data-Mining zurückzuführen ist. In dieser Arbeit wird ein transparenter Ansatz zum Beschreiben und Erklären von Daten für Entscheidungsträger vorgestellt. In Entscheidungsträger-zentrierten Aufgaben werden die Projektanforderungen definiert und die Ergebnisse zu einer Geschichte zusammengestellt. Eine Anforderung besteht dabei aus einem tabellarischen Bericht und ggf. Mustern in seinem Inhalt, jeweils verständlich für einen Entscheidungsträger. Die technischen Aufgaben bestehen aus einer Datenprüfung, der Integration der Daten in einem Data-Warehouse sowie dem Generieren von Berichten und dem Entdecken von Mustern wie in den Anforderungen beschrieben. Mehrere Data-Mining-Projekte können durch Wissensmanagement sowie eine geeignete Infrastruktur voneinander profitieren. Der Ansatz wurde in zwei Projekten unter Verwendung von ausschließlich Open-Source-Software angewendet. N2 - Despite high potential of data mining in business and science many projects fail due to barriers between the developer team and the end user. In this work a more transparent approach to describing and explaining data to a decision-maker is presented. In decision-maker-centric tasks project requirements are defined and finally the results composed to a story. A requirement is made of a tabular report and possibly patterns in its data, each understandable to a decision-maker. The technical tasks consist of a data assay, the integration of data within a data warehouse and, as required, the creation of reports and the discovery of patterns. Multiple data mining projects benefit from each other through knowledge management and a common infrastructure. The approach has been applied to two projects exclusively using open source systems. KW - Data Mining KW - Entscheidungsträger KW - Fallstudie KW - Methodologie KW - Endnutzer KW - Business Intelligence KW - Open Source KW - data mining KW - case study KW - process model KW - end user KW - open source Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-46343 ER - TY - INPR A1 - Nassourou, Mohamadou T1 - Design and Implementation of Architectures for Interactive Textual Documents Collation Systems N2 - One of the main purposes of textual documents collation is to identify a base text or closest witness to the base text, by analyzing and interpreting differences also known as types of changes that might exist between those documents. Based on this fact, it is reasonable to argue that, explicit identification of types of changes such as deletions, additions, transpositions, and mutations should be part of the collation process. The identification could be carried out by an interpretation module after alignment has taken place. Unfortunately existing collation software such as CollateX1 and Juxta2’s collation engine do not have interpretation modules. In fact they implement the Gothenburg model [1] for collation process which does not include an interpretation unit. Currently both CollateX and Juxta’s collation engine do not distinguish in their critical apparatus between the types of changes, and do not offer statistics about those changes. This paper presents a model for both integrated and distributed collation processes that improves the Gothenburg model. The model introduces an interpretation component for computing and distinguishing between the types of changes that documents could have undergone. Moreover two architectures implementing the model in order to solve the problem of interactive collation are discussed as well. Each architecture uses CollateX library, and provides on the one hand preprocessing functions for transforming input documents into CollateX input format, and on the other hand a post-processing module for enabling interactive collation. Finally simple algorithms for distinguishing between types of changes, and linking collated source documents with the collation results are also introduced. KW - Softwarearchitektur KW - Textvergleich KW - service based software architecture KW - service brokerage KW - interactive collation of textual variants KW - Gothenburg model of collation process Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-56601 ER - TY - INPR A1 - Nassourou, Mohamadou T1 - Design and Implementation of a Model-driven XML-based Integrated System Architecture for Assisting Analysis, Understanding, and Retention of Religious Texts:The Case of The Quran N2 - Learning a book in general involves reading it, underlining important words, adding comments, summarizing some passages, and marking up some text or concepts. Once deeper understanding is achieved, one would like to organize and manage her/his knowledge in such a way that, it could be easily remembered and efficiently transmitted to others. This paper discusses about modeling religious texts using semantic XML markup based on frame-based knowledge representation, with the purpose of assisting understanding, retention, and sharing of knowledge they contain. In this study, books organized in terms of chapters made up of verses are considered as the source of knowledge to model. Some metadata representing the multiple perspectives of knowledge modeling are assigned to each chapter and verse. Chapters and verses with their metadata form a meta-model, which is represented using frames, and published on a web mashup. An XML-based annotation and visualization system equipped with user interfaces for creating static and dynamic metadata, annotating chapters’ contents according to user selected semantics, and templates for publishing generated knowledge on the Internet, has been developed. The system has been applied to the Quran, and the result obtained shows that multiple perspectives of information modeling can be successfully applied to religious texts, in order to support analysis, understanding, and retention of the texts. KW - Wissensrepräsentation KW - Wissensmanagement KW - Content Management KW - XML KW - Koran KW - Knowledge representation KW - Meta-model KW - Frames KW - XML model KW - Knowledge Management KW - Content Management KW - Quran Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-65737 ER - TY - THES A1 - Klein, Dominik Werner T1 - Design and Evaluation of Components for Future Internet Architectures T1 - Entwurf und Bewertung von Komponenten für zukünftige Internet Architekturen N2 - Die derzeitige Internetarchitektur wurde nicht in einem geplanten Prozess konzipiert und entwickelt, sondern hat vielmehr eine evolutionsartige Entwicklung hinter sich. Auslöser für die jeweiligen Evolutionsschritte waren dabei meist aufstrebende Anwendungen, welche neue Anforderungen an die zugrundeliegende Netzarchitektur gestellt haben. Um diese Anforderungen zu erfüllen, wurden häufig neuartige Dienste oder Protokolle spezifiziert und in die bestehende Architektur integriert. Dieser Prozess ist jedoch meist mit hohem Aufwand verbunden und daher sehr träge, was die Entwicklung und Verbreitung innovativer Dienste beeinträchtigt. Derzeitig diskutierte Konzepte wie Software-Defined Networking (SDN) oder Netzvirtualisierung (NV) werden als eine Möglichkeit angesehen, die Altlasten der bestehenden Internetarchitektur zu lösen. Beiden Konzepten gemein ist die Idee, logische Netze über dem physikalischen Substrat zu betreiben. Diese logischen Netze sind hochdynamisch und können so flexibel an die Anforderungen der jeweiligen Anwendungen angepasst werden. Insbesondere erlaubt das Konzept der Virtualisierung intelligentere Netzknoten, was innovative neue Anwendungsfälle ermöglicht. Ein häufig in diesem Zusammenhang diskutierter Anwendungsfall ist die Mobilität sowohl von Endgeräten als auch von Diensten an sich. Die Mobilität der Dienste wird hierbei ausgenutzt, um die Zugriffsverzögerung oder die belegten Ressourcen im Netz zu reduzieren, indem die Dienste zum Beispiel in für den Nutzer geographisch nahe Datenzentren migriert werden. Neben den reinen Mechanismen bezüglich Dienst- und Endgerätemobilität sind in diesem Zusammenhang auch geeignete Überwachungslösungen relevant, welche die vom Nutzer wahrgenommene Dienstgüte bewerten können. Diese Lösungen liefern wichtige Entscheidungshilfen für die Migration oder überwachen mögliche Effekte der Migration auf die erfahrene Dienstgüte beim Nutzer. Im Falle von Video Streaming ermöglicht ein solcher Anwendungsfall die flexible Anpassung der Streaming Topologie für mobile Nutzer, um so die Videoqualität unabhängig vom Zugangsnetz aufrechterhalten zu können. Im Rahmen dieser Doktorarbeit wird der beschriebene Anwendungsfall am Beispiel einer Video Streaming Anwendung näher analysiert und auftretende Herausforderungen werden diskutiert. Des Weiteren werden Lösungsansätze vorgestellt und bezüglich ihrer Effizienz ausgewertet. Im Detail beschäftigt sich die Arbeit mit der Leistungsanalyse von Mechanismen für die Dienstmobilität und entwickelt eine Architektur zur Optimierung der Dienstmobilität. Im Bereich Endgerätemobilität werden Verbesserungen entwickelt, welche die Latenz zwischen Endgerät und Dienst reduzieren oder die Konnektivität unabhängig vom Zugangsnetz gewährleisten. Im letzten Teilbereich wird eine Lösung zur Überwachung der Videoqualität im Netz entwickelt und bezüglich ihrer Genauigkeit analysiert. N2 - Today’s Internet architecture was not designed from scratch but was driven by new services that emerged during its development. Hence, it is often described as patchwork where additional patches are applied in case new services require modifications to the existing architecture. This process however is rather slow and hinders the development of innovative network services with certain architecture or network requirements. Currently discussed technologies like Software-Defined Networking (SDN) or Network Virtualization (NV) are seen as key enabling technologies to overcome this rigid best effort legacy of the Internet. Both technologies offer the possibility to create virtual networks that accommodate the specific needs of certain services. These logical networks are operated on top of a physical substrate and facilitate flexible network resource allocation as physical resources can be added and removed depending on the current network and load situation. In addition, the clear separation and isolation of networks foster the development of application-aware networks that fulfill the special requirements of emerging applications. A prominent use case that benefits from these extended capabilities of the network is denoted with service component mobility. Services hosted on Virtual Machines (VMs) follow their consuming mobile endpoints, so that access latency as well as consumed network resources are reduced. Especially for applications like video streaming, which consume a large fraction of the available resources, is this an important means to relieve the resource constraints and eventually provide better service quality. Service and endpoint mobility both allow an adaptation of the used paths between an offered service, i.e., video streaming and the consuming users in case the service quality drops due to network problems. To make evidence-based adaptations in case of quality drops, a scalable monitoring component is required that is able to monitor the service quality for video streaming applications with reliable accuracy. This monograph details challenges that arise when deploying a certain service, i.e., video streaming, in a future virtualized network architecture and discusses possible solutions. In particular, this work evaluates the performance of mechanisms enabling service mobility and presents an optimized architecture for service mobility. Concerning endpoint mobility, improvements are developed that reduce the latency between endpoints and consumed services and ensure connectivity regardless of the used mobile access network. In the last part, a network-based video quality monitoring solution is developed and its accuracy is evaluated. T3 - Würzburger Beiträge zur Leistungsbewertung Verteilter Systeme - 01/14 KW - Leistungsbewertung KW - Netzwerkmanagement KW - Virtuelles Netzwerk KW - Mobiles Internet KW - Service Mobility KW - Endpoint Mobility KW - Video Quality Monitoring Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-93134 SN - 1432-8801 ER - TY - JOUR A1 - Steininger, Michael A1 - Kobs, Konstantin A1 - Davidson, Padraig A1 - Krause, Anna A1 - Hotho, Andreas T1 - Density-based weighting for imbalanced regression JF - Machine Learning N2 - In many real world settings, imbalanced data impedes model performance of learning algorithms, like neural networks, mostly for rare cases. This is especially problematic for tasks focusing on these rare occurrences. For example, when estimating precipitation, extreme rainfall events are scarce but important considering their potential consequences. While there are numerous well studied solutions for classification settings, most of them cannot be applied to regression easily. Of the few solutions for regression tasks, barely any have explored cost-sensitive learning which is known to have advantages compared to sampling-based methods in classification tasks. In this work, we propose a sample weighting approach for imbalanced regression datasets called DenseWeight and a cost-sensitive learning approach for neural network regression with imbalanced data called DenseLoss based on our weighting scheme. DenseWeight weights data points according to their target value rarities through kernel density estimation (KDE). DenseLoss adjusts each data point’s influence on the loss according to DenseWeight, giving rare data points more influence on model training compared to common data points. We show on multiple differently distributed datasets that DenseLoss significantly improves model performance for rare data points through its density-based weighting scheme. Additionally, we compare DenseLoss to the state-of-the-art method SMOGN, finding that our method mostly yields better performance. Our approach provides more control over model training as it enables us to actively decide on the trade-off between focusing on common or rare cases through a single hyperparameter, allowing the training of better models for rare data points. KW - supervised learning KW - imbalanced regression KW - cost-sensitive learning KW - sample weighting KW - Kerneldensity estimation Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-269177 SN - 1573-0565 VL - 110 IS - 8 ER - TY - JOUR A1 - Seufert, Anika A1 - Schröder, Svenja A1 - Seufert, Michael T1 - Delivering User Experience over Networks: Towards a Quality of Experience Centered Design Cycle for Improved Design of Networked Applications JF - SN Computer Science N2 - To deliver the best user experience (UX), the human-centered design cycle (HCDC) serves as a well-established guideline to application developers. However, it does not yet cover network-specific requirements, which become increasingly crucial, as most applications deliver experience over the Internet. The missing network-centric view is provided by Quality of Experience (QoE), which could team up with UX towards an improved overall experience. By considering QoE aspects during the development process, it can be achieved that applications become network-aware by design. In this paper, the Quality of Experience Centered Design Cycle (QoE-CDC) is proposed, which provides guidelines on how to design applications with respect to network-specific requirements and QoE. Its practical value is showcased for popular application types and validated by outlining the design of a new smartphone application. We show that combining HCDC and QoE-CDC will result in an application design, which reaches a high UX and avoids QoE degradation. KW - user experience KW - human-centered design KW - design cycle KW - application design KW - quality of experience Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-271762 SN - 2661-8907 VL - 2 IS - 6 ER - TY - THES A1 - Nogatz, Falco T1 - Defining and Implementing Domain-Specific Languages with Prolog T1 - Definition und Implementierung domänenspezifischer Sprachen mit Prolog N2 - The landscape of today’s programming languages is manifold. With the diversity of applications, the difficulty of adequately addressing and specifying the used programs increases. This often leads to newly designed and implemented domain-specific languages. They enable domain experts to express knowledge in their preferred format, resulting in more readable and concise programs. Due to its flexible and declarative syntax without reserved keywords, the logic programming language Prolog is particularly suitable for defining and embedding domain-specific languages. This thesis addresses the questions and challenges that arise when integrating domain-specific languages into Prolog. We compare the two approaches to define them either externally or internally, and provide assisting tools for each. The grammar of a formal language is usually defined in the extended Backus–Naur form. In this work, we handle this formalism as a domain-specific language in Prolog, and define term expansions that allow to translate it into equivalent definite clause grammars. We present the package library(dcg4pt) for SWI-Prolog, which enriches them by an additional argument to automatically process the term’s corresponding parse tree. To simplify the work with definite clause grammars, we visualise their application by a web-based tracer. The external integration of domain-specific languages requires the programmer to keep the grammar, parser, and interpreter in sync. In many cases, domain-specific languages can instead be directly embedded into Prolog by providing appropriate operator definitions. In addition, we propose syntactic extensions for Prolog to expand its expressiveness, for instance to state logic formulas with their connectives verbatim. This allows to use all tools that were originally written for Prolog, for instance code linters and editors with syntax highlighting. We present the package library(plammar), a standard-compliant parser for Prolog source code, written in Prolog. It is able to automatically infer from example sentences the required operator definitions with their classes and precedences as well as the required Prolog language extensions. As a result, we can automatically answer the question: Is it possible to model these example sentences as valid Prolog clauses, and how? We discuss and apply the two approaches to internal and external integrations for several domain-specific languages, namely the extended Backus–Naur form, GraphQL, XPath, and a controlled natural language to represent expert rules in if-then form. The created toolchain with library(dcg4pt) and library(plammar) yields new application opportunities for static Prolog source code analysis, which we also present. N2 - Die Landschaft der heutigen Programmiersprachen ist vielfältig. Mit ihren unterschiedlichen Anwendungsbereichen steigt zugleich die Schwierigkeit, die eingesetzten Programme adäquat anzusprechen und zu spezifizieren. Immer häufiger werden hierfür domänenspezifische Sprachen entworfen und implementiert. Sie ermöglichen Domänenexperten, Wissen in ihrem bevorzugten Format auszudrücken, was zu lesbareren Programmen führt. Durch ihre flexible und deklarative Syntax ohne vorbelegte Schlüsselwörter ist die logische Programmsprache Prolog besonders geeignet, um domänenspezifische Sprachen zu definieren und einzubetten. Diese Arbeit befasst sich mit den Fragen und Herausforderungen, die sich bei der Integration von domänenspezifischen Sprachen in Prolog ergeben. Wir vergleichen die zwei Ansätze, sie entweder extern oder intern zu definieren, und stellen jeweils Hilfsmittel zur Verfügung. Die Grammatik einer formalen Sprache wird häufig in der erweiterten Backus–Naur–Form definiert. Diesen Formalismus behandeln wir in dieser Arbeit als eine domänenspezifische Sprache in Prolog und definieren Termexpansionen, die es erlauben, ihn in äquivalente Definite Clause Grammars für Prolog zu übersetzen. Durch das Modul library(dcg4pt) werden sie um ein zusätzliches Argument erweitert, das den Syntaxbaum eines Terms automatisch erzeugt. Um die Arbeit mit Definite Clause Grammars zu erleichtern, visualisieren wir ihre Anwendung in einem webbasierten Tracer. Meist können domänenspezifische Sprachen jedoch auch mittels passender Operatordefinitionen direkt in Prolog eingebettet werden. Dies ermöglicht die Verwendung aller Werkzeuge, die ursprünglich für Prolog geschrieben wurden, z.B. zum Code-Linting und Syntax-Highlighting. In dieser Arbeit stellen wir den standardkonformen Prolog-Parser library(plammar) vor. Er ist in Prolog geschrieben und in der Lage, aus Beispielsätzen automatisch die erforderlichen Operatoren mit ihren Klassen und Präzedenzen abzuleiten. Um die Ausdruckskraft von Prolog noch zu erweitern, schlagen wir Ergänzungen zum ISO Standard vor. Sie erlauben es, weitere Sprachen direkt einzubinden, und werden ebenfalls von library(plammar) identifiziert. So ist es bspw. möglich, logische Formeln direkt mit den bekannten Symbolen für Konjunktion, Disjunktion, usw. als Prolog-Programme anzugeben. Beide Ansätze der internen und externen Integration werden für mehrere domänen-spezifische Sprachen diskutiert und beispielhaft für GraphQL, XPath, die erweiterte Backus–Naur–Form sowie Expertenregeln in Wenn–Dann–Form umgesetzt. Die vorgestellten Werkzeuge um library(dcg4pt) und library(plammar) ergeben zudem neue Anwendungsmöglichkeiten auch für die statische Quellcodeanalyse von Prolog-Programmen. KW - PROLOG KW - Domänenspezifische Sprache KW - logic programming KW - knowledge representation KW - definite clause grammars Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-301872 ER - TY - JOUR A1 - Müller, Konstantin A1 - Leppich, Robert A1 - Geiß, Christian A1 - Borst, Vanessa A1 - Pelizari, Patrick Aravena A1 - Kounev, Samuel A1 - Taubenböck, Hannes T1 - Deep neural network regression for normalized digital surface model generation with Sentinel-2 imagery JF - IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing N2 - In recent history, normalized digital surface models (nDSMs) have been constantly gaining importance as a means to solve large-scale geographic problems. High-resolution surface models are precious, as they can provide detailed information for a specific area. However, measurements with a high resolution are time consuming and costly. Only a few approaches exist to create high-resolution nDSMs for extensive areas. This article explores approaches to extract high-resolution nDSMs from low-resolution Sentinel-2 data, allowing us to derive large-scale models. We thereby utilize the advantages of Sentinel 2 being open access, having global coverage, and providing steady updates through a high repetition rate. Several deep learning models are trained to overcome the gap in producing high-resolution surface maps from low-resolution input data. With U-Net as a base architecture, we extend the capabilities of our model by integrating tailored multiscale encoders with differently sized kernels in the convolution as well as conformed self-attention inside the skip connection gates. Using pixelwise regression, our U-Net base models can achieve a mean height error of approximately 2 m. Moreover, through our enhancements to the model architecture, we reduce the model error by more than 7%. KW - Deep learning KW - multiscale encoder KW - sentinel KW - surface model Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-349424 SN - 1939-1404 VL - 16 ER - TY - JOUR A1 - Ali, Qasim A1 - Montenegro, Sergio T1 - Decentralized control for scalable quadcopter formations JF - International Journal of Aerospace Engineering N2 - An innovative framework has been developed for teamwork of two quadcopter formations, each having its specified formation geometry, assigned task, and matching control scheme. Position control for quadcopters in one of the formations has been implemented through a Linear Quadratic Regulator Proportional Integral (LQR PI) control scheme based on explicit model following scheme. Quadcopters in the other formation are controlled through LQR PI servomechanism control scheme. These two control schemes are compared in terms of their performance and control effort. Both formations are commanded by respective ground stations through virtual leaders. Quadcopters in formations are able to track desired trajectories as well as hovering at desired points for selected time duration. In case of communication loss between ground station and any of the quadcopters, the neighboring quadcopter provides the command data, received from the ground station, to the affected unit. Proposed control schemes have been validated through extensive simulations using MATLAB®/Simulink® that provided favorable results. KW - scalable quadcopter Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-146704 VL - 2016 ER - TY - JOUR A1 - Petschke, Danny A1 - Staab, Torsten E.M. T1 - DDRS4PALS: a software for the acquisition and simulation of lifetime spectra using the DRS4 evaluation board JF - SoftwareX N2 - Lifetime techniques are applied to diverse fields of study including materials sciences, semiconductor physics, biology, molecular biophysics and photochemistry. Here we present DDRS4PALS, a software for the acquisition and simulation of lifetime spectra using the DRS4 evaluation board (Paul Scherrer Institute, Switzerland) for time resolved measurements and digitization of detector output pulses. Artifact afflicted pulses can be corrected or rejected prior to the lifetime calculation to provide the generation of high-quality lifetime spectra, which are crucial for a profound analysis, i.e. the decomposition of the true information. Moreover, the pulses can be streamed on an (external) hard drive during the measurement and subsequently downloaded in the offline mode without being connected to the hardware. This allows the generation of various lifetime spectra at different configurations from one single measurement and, hence, a meaningful comparison in terms of analyzability and quality. Parallel processing and an integrated JavaScript based language provide convenient options to accelerate and automate time consuming processes such as lifetime spectra simulations. KW - Lifetime spectroscopy KW - Positron annihilation spectroscopy KW - Simulation KW - Time resolved measurements Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-202276 VL - 10 ER - TY - RPRT A1 - Raffeck, Simon A1 - Geißler, Stefan A1 - Hoßfeld, Tobias T1 - DBM: Decentralized Burst Mitigation for Self-Organizing LoRa Deployments T2 - Würzburg Workshop on Next-Generation Communication Networks (WueWoWas'22) N2 - This work proposes a novel approach to disperse dense transmission intervals and reduce bursty traffic patterns without the need for centralized control. Furthermore, by keeping the mechanism as close to the Long Range Wide Area Network (LoRaWAN) standard as possible the suggested mechanism can be deployed within existing networks and can even be co-deployed with other devices. KW - Datennetz KW - LoRa Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-280809 ER - TY - RPRT A1 - Rossi, Angelo Pio A1 - Maurelli, Francesco A1 - Unnithan, Vikram A1 - Dreger, Hendrik A1 - Mathewos, Kedus A1 - Pradhan, Nayan A1 - Corbeanu, Dan-Andrei A1 - Pozzobon, Riccardo A1 - Massironi, Matteo A1 - Ferrari, Sabrina A1 - Pernechele, Claudia A1 - Paoletti, Lorenzo A1 - Simioni, Emanuele A1 - Maurizio, Pajola A1 - Santagata, Tommaso A1 - Borrmann, Dorit A1 - Nüchter, Andreas A1 - Bredenbeck, Anton A1 - Zevering, Jasper A1 - Arzberger, Fabian A1 - Reyes Mantilla, Camilo Andrés T1 - DAEDALUS - Descent And Exploration in Deep Autonomy of Lava Underground Structures BT - Open Space Innovation Platform (OSIP) Lunar Caves-System Study N2 - The DAEDALUS mission concept aims at exploring and characterising the entrance and initial part of Lunar lava tubes within a compact, tightly integrated spherical robotic device, with a complementary payload set and autonomous capabilities. The mission concept addresses specifically the identification and characterisation of potential resources for future ESA exploration, the local environment of the subsurface and its geologic and compositional structure. A sphere is ideally suited to protect sensors and scientific equipment in rough, uneven environments. It will house laser scanners, cameras and ancillary payloads. The sphere will be lowered into the skylight and will explore the entrance shaft, associated caverns and conduits. Lidar (light detection and ranging) systems produce 3D models with high spatial accuracy independent of lighting conditions and visible features. Hence this will be the primary exploration toolset within the sphere. The additional payload that can be accommodated in the robotic sphere consists of camera systems with panoramic lenses and scanners such as multi-wavelength or single-photon scanners. A moving mass will trigger movements. The tether for lowering the sphere will be used for data communication and powering the equipment during the descending phase. Furthermore, the connector tether-sphere will host a WIFI access point, such that data of the conduit can be transferred to the surface relay station. During the exploration phase, the robot will be disconnected from the cable, and will use wireless communication. Emergency autonomy software will ensure that in case of loss of communication, the robot will continue the nominal mission. T3 - Forschungsberichte in der Robotik = Research Notes in Robotics - 21 KW - Lunar Caves KW - Spherical Robot KW - Lunar Exploration KW - Mapping KW - 3D Laser Scanning KW - Mond KW - Daedalus-Projekt KW - Lava Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-227911 SN - 978-3-945459-33-1 SN - 1868-7466 ER -