Publikationen an der Fakultät für Informatik und Automatisierung ab 2015

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Al-Sayeh, Hani; Jibril, Muhammad Attahir; Bin Saeed, Muhammad Waleed; Sattler, Kai-Uwe
SparkCAD: caching anomalies detector for spark applications. - In: Proceedings of the VLDB Endowment, Bd. 15 (2022), 12, S. 3694-3697

Developers of Apache Spark applications can accelerate their workloads by caching suitable intermediate results in memory and reusing them rather than recomputing them all over again every time they are needed. However, as scientific workflows are becoming more complex, application developers are becoming more prone to making wrong caching decisions, which we refer to as caching anomalies, that lead to poor performance. We present and give a demonstration of Spark Caching Anomalies Detector (SparkCAD), a developer decision support tool that visualizes the logical plan of Spark applications and detects caching anomalies.
Soll, Marcus; Haase, Jan; Helbing, Pierre; Nau, Johannes
What are we missing for effective remote laboratories?. - In: IEEE Xplore digital library, ISSN 2473-2001, (2022), insges. 6 S.

Remote laboratories play an important role in modern education. Because of this, a multitude of different protocols and systems for building and integrating remote laboratories have been developed over the last years. This Paper analyses these different protocols and systems (SCORM / xAPI, IMS-LTI, IEEE 1876-2019, IVI / VISA, OPC-UA, Weblab-Deusto / LabsLand, GOLDi-Labs) and sorts them into different layers to build a protocol stack for implementing remote laboratories, accompanied by some examples of what is currently possible to implement. A gap in the protocol stack was identified between Controller and the whole Laboratory where no standardised protocol exists. Suggestions for the requirements of such a protocol are laid out. The new possibilities with such a protocol are presented by showing examples of new types of remote laboratories, followed by a short discussion of problems not yet solved by such a new protocol.
Aubel, Ines; Zug, Sebastian; Dietrich, André; Nau, Johannes; Henke, Karsten; Helbing, Pierre; Streitferdt, Detlef; Terkowsky, Claudius; Boettcher, Konrad; Ortelt, Tobias R.; Schade, Marcel; Kockmann, Norbert; Haertel, Tobias; Wilkesmann, Uwe; Finck, Matthias; Haase, Jan; Herrmann, Franziska; Kobras, Louis; Meussen, Bernhard; Soll, Marcus; Versick, Daniel
Adaptable digital labs - motivation and vision of the CrossLab project. - In: IEEE Xplore digital library, ISSN 2473-2001, (2022), insges. 6 S.

The flexibility and performance of digital laboratory elements such as remote labs, VR/AR or simulations summarized under the term cross-reality labs (CrossLabs), can be seen with the development in last and has been proven under the pandemic situation. Even though the potential of cross-reality labs is obvious referring to availability and flexibility for the students, these didactic solutions remain isolated at universities as well as for individual users. The implementations are mostly so rigid that the individual didactic objectives are not interchangeable between different universities and disciplines, hence there is a lack of interoperability. The CrossLab project seeks to design didactical, technical, and organizational solutions for open digital lab objects linking student-centered teaching and a cross-university learning environment. Of importance thereby is the fact that teaching is not adaptable to the digital laboratory, but the laboratories are adaptable to the requirements of the teaching-learning setting. The four project partners are working on a cross-type and cross-element mixture of diverse types of laboratories for cross-disciplinary use in a cross-universities settings. Thereby, the project leans on existing digital laboratories in various disciplines to create an open teaching and learning environment which can be adapted to the needs of students and to provide students with the skills necessary for future working scenarios.
Blum, Maren-Christina;
Elektrophysiologische Wirkung transokularer Ströme. - Ilmenau : Universitätsbibliothek, 2022. - 1 Online-Ressource (xxiv, 140 Blätter)
Technische Universität Ilmenau, Dissertation 2022

Die transkranielle Gleichstromstimulation mit schwachen Strömen (≤ 2 mA) ist ein etabliertes Verfahren zur Untersuchung des menschlichen Nervensystems und zur Behandlung psychologisch-neurologischer Erkrankungen. In den letzten Jahren hat die Stimulation des visuellen Systems, speziell der Retina, an Aufmerksamkeit gewonnen, da Hinweise auf positive Einflüsse einer transokularen Stromstimulation zur Behandlung neurodegenerativer retinaler Erkrankungen gefunden wurden. Bis heute fehlt jedoch ein Wirkungskonzept, das den Einfluss der Stromstimulation auf die verschiedenen retinalen Neuronen beschreibt. Aus Studien ist bekannt, dass ein visuell evoziertes Potential durch eine transkranielle Gleichstromstimulation des visuellen Cortex in den charakteristischen Amplituden beeinflusst werden kann. Daraus ergab sich das methodische Verfahren ein evoziertes Potential retinaler Herkunft, welches durch das Elektroretinogramm erfasst wird, in Kombination mit einer transokularen Stromstimulation zu nutzen, um den Einfluss der Stromstimulation auf die retinalen Zellen zu untersuchen. Durch Variation der visuellen Stimulationsparameter zur Generierung des Elektroretinogramms, ist es möglich, unterschiedliche retinale Neuronen in den Fokus zu nehmen. Im ersten Teil der Dissertation wurde ein grundlegendes Studienkonzept auf Basis des Verfahrens der experimentellen Prozessanalyse entwickelt. Aus diesem wurden Anforderungen an einen Mess- und Stimulationsplatz abgeleitet, um eine simultane transokulare Gleichstromstimulation und Aufnahme eines Elektroretinogramms zu ermöglichen. Des Weiteren wurden Anforderungen an das Studiendesign abgeleitet. Im zweiten Teil der Dissertation wurden insgesamt vier aufeinander aufbauende Probandenstudien durchgeführt, analysiert und interpretiert. In diesen wurden sowohl unterschiedliche retinale Neuronen als auch der Einfluss der Position der Stromstimulationselektroden untersucht. Aus den Ergebnissen wurde ein Wirkungskonzept für die transokulare Gleichstromstimulation auf die retinalen Neuronen abgeleitet. Dieses besagt, dass primär die retinalen Ganglienzellen während einer transokularen Gleichstromstimulation in ihrer elektrophysiologischen Aktivität beeinflusst werden. Die Ergebnisse der Dissertation lassen sich weiterführend für die Entwicklung und die Optimierung von Therapieverfahren zur Behandlung neurodegenerativer retinaler Erkrankungen sowie zur Entwicklung objektiver Messmethoden zum Nachweis einer transokularen Stromwirkung verwenden.
Cheng, Nuo; Li, Xiaohan; Li, Han; Liu, Xiaotong; Luo, Chuanyu; Lei, Shengguang; Li, Pu
PASNet: a self-adaptive point cloud sorting approach to an improved feature extraction. - In: IEEE Xplore digital library, ISSN 2473-2001, (2022), S. 956-960

A well-known difficulty in processing 3D point cloud is due to its unordered nature. The state-of-the-art 3D computer vision detection methods mainly use voxels to extract point cloud features. However, a drawback of point cloud voxelization is that some features of point cloud surface cannot be fully described. To address this problem, we propose an adaptive sorting approach for voxel-based point cloud. It adaptively ranks point cloud within voxels at first and then goes on to ex-tract voxel features using a multilayer perceptron, called PAS-Net (Points-Adaptive -Sorting-Net). The resulting method is plug-and-play and can be easily deployed in any voxel-based detection model. The proposed model was tested on the KITTI benchmark suit where a 2% - 7% improvement of the detection accuracy is achieved compared with other models using different point feature extraction methods.
Richter, Felix; Chen, Minqian; Schaub, Patrick; Wüst, Florian; Zhang, Di; Schneider, Steffen; Groß, Gregor Alexander; Mäder, Patrick; Dovzhenko, Oleksandr; Palme, Klaus; Köhler, Michael; Cao-Riehmer, Jialan
Induction of embryogenic development in haploid microspore stem cells in droplet-based microfluidics. - In: Lab on a chip, ISSN 1473-0189, Bd. 22 (2022), 22, S. 4292-4305

This work presents the application of droplet-based microfluidics for the cultivation of microspores from Brassica napus using the doubled haploid technology. Under stress conditions (e.g. heat shock) or by chemical induction a certain fraction of the microspores can be reprogrammed and androgenesis can be induced. This process is an important approach for plant breeding because desired plant properties can be anchored in the germline on a genetic level. However, the reprogramming rate of the microspores is generally very low, increasing it by specific stimulation is, therefore, both a necessary and challenging task. In order to accelerate the optimisation and development process, the application of droplet-based microfluidics can be a promising tool. Here, we used a tube-based microfluidic system for the generation and cultivation of microspores inside nL-droplets. Different factors like cell density, tube material and heat shock conditions were investigated to improve the yield of vital plant organoids. Evaluation and analysis of the stimuli response were done on an image base aided by an artificial intelligence cell detection algorithm. Droplet-based microfluidics allowed us to apply large concentration programs in small test volumes and to screen the best conditions for reprogramming cells by the histone deacetylase inhibitor trichostatin A and for enhancing the yield of vital microspores in droplets. An enhanced reprogramming rate was found under the heat shock conditions at 32 &ring;C for about 3 to 6 days. In addition, the comparative experiment with MTP showed that droplet cultivation with lower cell density (<10 cells per droplet) or adding media after 3 or 6 days significantly positively affects the microspore growth and embryo rate inside 120 nL droplets. Finally, the developed embryos could be removed from the droplets and further grown into mature plants. Overall, we demonstrated that the droplet-based tube system is suitable for implementation in an automated, miniaturized system to achieve the induction of embryogenic development in haploid microspore stem cells of Brassica napus.
Rath, Michael;
Utilizing traceable software artifacts to improve bug localization. - Ilmenau : Universitätsbibliothek, 2022. - 1 Online-Ressource (viii, 142, XXX Seiten)
Technische Universität Ilmenau, Dissertation 2022

Die Entwicklung von Softwaresystemen ist eine komplexe Aufgabe. Qualitätssicherung versucht auftretenden Softwarefehler (bugs) in Systemen zu vermeiden, jedoch können Fehler nie ausgeschlossen werden. Sobald ein Softwarefehler entdeckt wird, wird typischerweise ein Fehlerbericht (bug report) erstellt. Dieser dient als Ausgangspunkt für den Entwickler den Fehler im Quellcode der Software zu finden und zu beheben (bug fixing). Fehlerberichte sowie weitere Softwareartefakte, z.B. Anforderungen und der Quellcode selbst, werden in Software Repositories abgelegt. Diese erlauben die Artefakte mit trace links zur Nachvollziehbarkeit (traceability) zu verknüpfen. Oftmals ist die Erstellung der trace links im Entwicklungsprozess vorgeschrieben. Dazu zählen u.a. die Luftfahrt- und Automobilindustrie, sowie die Entwicklung von medizinischen Geräten. Das Auffinden von Softwarefehlern in großen Systemen mit tausenden Artefakten ist eine anspruchsvolle, zeitintensive und fehleranfällige Aufgabe, welche eine umfangreiche Projektkenntnis erfordert. Deswegen wird seit Jahren aktiv an der Automatisierung dieses Prozesses geforscht. Weiterhin wird die manuelle Erstellung und Pflege von trace links als Belastung empfunden und sollte weitgehend automatisiert werden. In dieser Arbeit wird ein neuartiger Algorithmus zum Auffinden von Softwarefehlern vorgestellt, der aktiv die erstellten trace links ausnutzt. Die Artefakte und deren Beziehungen dienen zur Erstellung eines Nachvollziehbarkeitsgraphen, welcher analysiert wird um fehlerhafte Quellcodedateien anhand eines Fehlerberichtes zu finden. Jedoch muss angenommen werden, dass nicht alle notwendigen trace links zwischen den Softwareartefakten eines Projektes erstellt wurden. Deswegen wird ein vollautomatisierter, projektunabhängiger Ansatz vorgestellt, der diese fehlenden trace links erstellt (augmentation). Die Grundlage zur Entwicklung dieses Algorithmus ist der typische Entwicklungsprozess eines Softwareprojektes. Die entwickelten Ansätze wurden mit mehr als 32.000 Fehlerberichten von 27 Open-Source Projekten evaluiert und die Ergebnisse zeigen, dass die Einbeziehung von traceability signifikant das Auffinden von Fehlern im Quellcode verbessert. Weiterhin kann der entwickelte Augmentation Algorithmus zuverlässig fehlende trace links erstellen.
Carmeli, Nofar; Zeevi, Shai; Berkholz, Christoph; Conte, Alessio; Kimelfeld, Benny; Schweikardt, Nicole
Answering (unions of) conjunctive queries using random access and random-order enumeration. - In: ACM transactions on database systems, ISSN 0362-5915, Bd. 47 (2022), 3, S. 9:1-9:49

As data analytics becomes more crucial to digital systems, so grows the importance of characterizing the database queries that admit a more efficient evaluation. We consider the tractability yardstick of answer enumeration with a polylogarithmic delay after a linear-time preprocessing phase. Such an evaluation is obtained by constructing, in the preprocessing phase, a data structure that supports polylogarithmic-delay enumeration. In this article, we seek a structure that supports the more demanding task of a “random permutation”: polylogarithmic-delay enumeration in truly random order. Enumeration of this kind is required if downstream applications assume that the intermediate results are representative of the whole result set in a statistically meaningful manner. An even more demanding task is that of “random access”: polylogarithmic-time retrieval of an answer whose position is given. We establish that the free-connex acyclic CQs are tractable in all three senses: enumeration, random-order enumeration, and random access; and in the absence of self-joins, it follows from past results that every other CQ is intractable by each of the three (under some fine-grained complexity assumptions). However, the three yardsticks are separated in the case of a union of CQs (UCQ): while a union of free-connex acyclic CQs has a tractable enumeration, it may (provably) admit no random access. We identify a fragment of such UCQs where we can guarantee random access with polylogarithmic access time (and linear-time preprocessing) and a more general fragment where we can guarantee tractable random permutation. For general unions of free-connex acyclic CQs, we devise two algorithms with relaxed guarantees: one has logarithmic delay in expectation, and the other provides a permutation that is almost uniformly distributed. Finally, we present an implementation and an empirical study that show a considerable practical superiority of our random-order enumeration approach over state-of-the-art alternatives.
Ng, Chuen Rue; Fiedler, Patrique; Kuhlmann, Levin; Liley, David; Vasconcelos, Beatriz; Fonseca, Carlos; Tamburro, Gabriella; Comani, Silvia; Lui, Troby Ka-Yan; Tse, Chun-Yu; Warsito, Indhika Fauzhan; Supriyanto, Eko; Haueisen, Jens
Multi-center evaluation of gel-based and dry multipin EEG caps. - In: Sensors, ISSN 1424-8220, Bd. 22 (2022), 20, 8079, S. 1-16

Dry electrodes for electroencephalography (EEG) allow new fields of application, including telemedicine, mobile EEG, emergency EEG, and long-term repetitive measurements for research, neurofeedback, or brain–computer interfaces. Different dry electrode technologies have been proposed and validated in comparison to conventional gel-based electrodes. Most previous studies have been performed at a single center and by single operators. We conducted a multi-center and multi-operator study validating multipin dry electrodes to study the reproducibility and generalizability of their performance in different environments and for different operators. Moreover, we aimed to study the interrelation of operator experience, preparation time, and wearing comfort on the EEG signal quality. EEG acquisitions using dry and gel-based EEG caps were carried out in 6 different countries with 115 volunteers, recording electrode-skin impedances, resting state EEG and evoked activity. The dry cap showed average channel reliability of 81% but higher average impedances than the gel-based cap. However, the dry EEG caps required 62% less preparation time. No statistical differences were observed between the gel-based and dry EEG signal characteristics in all signal metrics. We conclude that the performance of the dry multipin electrodes is highly reproducible, whereas the primary influences on channel reliability and signal quality are operator skill and experience.
Gonzalez, Avelino J.; Anchor, Thomas; Hevia, Anthony; Posadas, Andres; Wade, Josh; Ansag, R. A.; Benko, Kyle; Bottoni, Brooke; Kazakova, Vera; Alvarez, M. J.; Wong, Josiah M.; Martin, J.; Knauf, Rainer; Jantke, Klaus P.; Wu, Annie S.
The evolution of the fAIble system to automatically compose and narrate stories for children. - In: Journal of experimental & theoretical artificial intelligence, ISSN 1362-3079, Bd. 0 (2022), 0, S. 1-46

This article describes our long-term research into automated story generation and our resulting story generation architecture called fAIble that incorporates several innovations. fAIble determines each event that occurs in the tale using a combination of scripted sequences and stochastically chosen events. The probability of an event occurring is based on the skills and personalities of the characters who have agency. Event selection is also influenced by the context of the situation faced by the characters. Each event is associated with a description in grammatically-correct natural language that can be narrated orally via text-to-speech. We describe the evolution of fAIble, its architecture and the results of our independent evaluation of each of the four progressively developed fAIble prototypes (fAIble 0, I, II and III), as tested with human test subjects. On a continuous scale where 0 means unacceptable, 1 means acceptable and 2 means optimal, the composite human test subject rating average from the independent tests of the prototypes was 0.933. The paper also describes a summative assessment where test subjects were asked to review stories from all four prototypes and rank them comparatively. These comparative results indicate an improvement from the original (fAIble 0) to the last one (fAIble III).