Refine
Departments, institutes and facilities
- Fachbereich Informatik (606)
- Fachbereich Ingenieurwissenschaften und Kommunikation (235)
- Institut für Technik, Ressourcenschonung und Energieeffizienz (TREE) (216)
- Institute of Visual Computing (IVC) (210)
- Institut für Cyber Security & Privacy (ICSP) (201)
- Fachbereich Wirtschaftswissenschaften (148)
- Institut für Verbraucherinformatik (IVI) (134)
- Fachbereich Angewandte Naturwissenschaften (76)
- Institut für funktionale Gen-Analytik (IFGA) (56)
- Internationales Zentrum für Nachhaltige Entwicklung (IZNE) (54)
Document Type
- Conference Object (1806) (remove)
Year of publication
Keywords
- FPGA (11)
- Machine Learning (9)
- Usable Security (9)
- Virtual Reality (9)
- Privacy (8)
- Robotics (7)
- Sustainability (7)
- DPA (6)
- Education (6)
- Entrepreneurship (6)
WiFi-based Long Distance (WiLD) networks have emerged as a promising alternative technology approach for providing Internet in rural areas. An important factor in network planning of these wireless networks is estimating the path loss. In this work, we present various propagation models we found suitable for point-to-point (P2P) operation in the WiFi frequency bands. We conducted outdoor experiments with commercial offthe- shelf (COTS) hardware in our testbed made of 7 different long-distance links ranging from 450 m to 10.3 km and a mobile measurement station. We found that for short links with omni-directional antennas ground-reflection is a measurable phenomenon. For longer links, we show that either FSPL or the Longley-Rice model provides accurate results for certain links. We conclude that a good site survey is needed to exclude influences not included in the propagation models.
Quantifying Interference in WiLD Networks using Topography Data and Realistic Antenna Patterns
(2019)
Avoiding possible interference is a key aspect to maximize the performance in Wi-Fi based Long Distance networks. In this paper we quantify self-induced interference based on data derived from our testbed and match the findings against simulations. By enhancing current simulation models with two key elements we significantly reduce the deviation between testbed and simulation: the usage of detailed antenna patterns compared to the cone model and propagation modeling enhanced by license-free topography data. Based on the gathered data we discuss several possible optimization approaches such as physical separation of local radios, tuning the sensitivity of the transmitter and using centralized compared to distributed channel assignment algorithms. While our testbed is based on 5 GHz Wi-Fi, we briefly discuss the possible impact of our results to other frequency bands.
SDN and WMN evolved to be sophisticated technologies used in a variety of applications. However, a combined approach called wmSDN has not been widely addressed in the research community. Our idea in this field consists of WiFi-based point-to-point links managed by the OpenFlow protocol. We investigate two different issues regarding this idea. First, which WiFi operational mode is suitable in an OpenFlow managed broadcast domain? Second, does the performance decrease compared with other routing or switching principles? Therefore, we set up a real-world testbed and a suitable simulation environment. Unlike previous work, we show that it is possible to use WiFi links without conducting MAC address rewriting at each hop by utilizing the 4-address-mode.
In the project EILD.nrw, Open Educational Resources (OER) have been developed for teaching databases. Lecturers can use the tools and courses in a variety of learning scenarios. Students of computer science and application subjects can learn the complete life cycle of databases. For this purpose, quizzes, interactive tools, instructional videos, and courses for learning management systems are developed and published under a Creative Commons license. We give an overview of the developed OERs according to subject, description, teaching form, and format. Following, we describe how licencing, sustainability, accessibility, contextualization, content description, and technical adaptability are implemented. The feedback of students in ongoing classes are evaluated.
Influence of design of extrusion blow molding (EBM) in terms of extrusion direction set-up and draw ratio as well as process conditions (mold temperature) on storage modulus of high density polyethylene EBM containers was analyzed with dynamic mechanical analysis. All three parameters - mold temperature, flow direction and draw ratio - are statistically significant and lead to relative and absolute evaluation of storage modulus. Furthermore, flow induced changes in crystallinity was analyzed by differential scanning calorimetry. Obtained data on deformation properties can be employed for more sophisticated finite element simulations with the aim to reach more sustainable extrusion blow molding production.
En el siguiente trabajo se presentan las diferentes alternativas tecnológicas que brindarán soporte para las comunicaciones en el Proyecto Campo Conectado, priorizando el bajo consumo y mantenimiento. Esta plataforma de transmisión proveerá la conectividad necesaria para la recolección y envío de los datos requeridos por los productores agropecuarios, con el fin de mejorar la gestión de los procesos productivos y comerciales. Se comenta además los orígenes del proyecto y los actores involucrados en el mismo, destacándose el trabajo interinstitucional e interdisciplinar que se lleva a cabo.
On the design and performance of a hybrid-integrated high-T c superconducting C-band oscillator
(1992)
Datenschutz und informationelle Selbstbestimmung sind Bestandteile aktueller Leitbilder einer Digitalen Bildung in der Schule. Im Kontext der Schulschließungen und der vorrangigen Nutzung digitaler Medien zeigte sich jedoch, dass Datenschutz weder als Thema noch als Gestaltungsprinzip digitaler Lernumgebungen in der bildungsadministrativen und pädagogisch-praktischen Schulwirklichkeit systematisch verankert ist. Die Diskrepanz zwischen aktuellen Leitbildern einer digitalen Bildung und der sichtbar problematischen Praxis des digitalen Notfalldistanzunterrichts markiert den Ausgangspunkt des Beitrages, der sich der übergeordneten Frage widmet, welche Herausforderungen sich bei der Realisierung von Datenschutz in der Schul- und Unterrichtswirklichkeit in einer digital geprägten Welt stellen. Im Sinne einer Problemfeldanalyse werden prototypische Handlungsprobleme der Schule herausgearbeitet. Fokussiert betrachtet werden exemplarische Herausforderungen und Anforderungen an Technologien und Akteur:innen der inneren und äußeren Schulentwicklung auf den Ebenen der Unterrichtsentwicklung, der Personalentwicklung, der Technologieentwicklung und der Organisationsentwicklung.
The continuously increasing number of biomedical scholarly publications makes it challenging to construct document recommendation algorithms that can efficiently navigate through literature. Such algorithms would help researchers in finding similar, relevant, and related publications that align with their research interests. Natural Language Processing offers various alternatives to compare publications, ranging from entity recognition to document embeddings. In this paper, we present the results of a comparative analysis of vector-based approaches to assess document similarity in the RELISH corpus. We aim to determine the best approach that resembles relevance without the need for further training. Specifically, we employ five different techniques to generate vectors representing the text in the documents. These techniques employ a combination of various Natural Language Processing frameworks such as Word2Vec, Doc2Vec, dictionary-based Named Entity Recognition, and state-of-the-art models based on BERT. To evaluate the document similarity obtained by these approaches, we utilize different evaluation metrics that account for relevance judgment, relevance search, and re-ranking of the relevance search. Our results demonstrate that the most promising approach is an in-house version of document embeddings, starting with word embeddings and using centroids to aggregate them by document.
The continuous increase of biomedical scholarly publications makes it challenging to construct document recommendation algorithms to navigate through literature, an important feature for researchers to keep up with relevant publications. Understanding semantic relatedness and similarity between two documents could improve document recommendations. The objective of this study is performing a comparative analysis of vector-based approaches to assess document similarity in the RELISH corpus. Here we present our approach to compare five different techniques to generate vectors representing the text in the documents. These techniques employ a combination of various Natural Language Processing frameworks such as Word2Vec, Doc2Vec, dictionary-based Named Entity Recognition as well as state-of-the-art models based on BERT.
In this paper, several blocking techniques are applied to matrices that do not have a strong blocked structure. The aim is to efficiently use vectorization with current CPUs, even for matrices without an explicit block structure on nonzero elements. Different approaches are known to find fixed or variable sized blocks of nonzero elements in a matrix. We present a new matrix format for 2D rectangular blocks of variable size, allowing fill-ins per block of explicit zero values up to a user definable threshold. We give a heuristic to detect such 2D blocks in a sparse matrix. The performance of a Sparse Matrix Vector Multiplication for chosen block formats is measured and compared. Results show that the benefit of blocking formats depend – as to be expected – on the structure of the matrix and that variable sized block formats can have advantages over fixed size formats.
AI systems pose unknown challenges for designers, policymakers, and users which aggravates the assessment of potential harms and outcomes. Although understanding risks is a requirement for building trust in technology, users are often excluded from legal assessments and explanations of AI hazards. To address this issue we conducted three focus groups with 18 participants in total and discussed the European proposal for a legal framework for AI. Based on this, we aim to build a (conceptual) model that guides policymakers, designers, and researchers in understanding users’ risk perception of AI systems. In this paper, we provide selected examples based on our preliminary results. Moreover, we argue for the benefits of such a perspective.
OpCog: an industrial development approach for cognitive agent systems in military UAV applications
(2008)
Programmable logic controllers (PLCs) have traditionally been used on numerous machines for control of the various processing and manufacturing steps. In response to an initiative by the Expert Committee Chemical Industry (FA CH), suitable metrics have been defined in order to permit rapid static analysis of comprehensive PLC programs. A tool was developed for this purpose which is also able to determine quality criteria. Additional to seven of the new metrics five metrics derived from Halstead and McCabe are used to determine the quality-criteria: testability, self-description, legibility and simplicity. New concepts were developed to determine and to calculate these criteria. The results are documented in hyper-language files with links to the called modules and control-graphs for each function. The tool was validated by three voluminous PLC-programs, two are from industrial projects.