Publications Search Results
1 - 10 of 333
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PublicationJul@ - A web app to support the political participation of adolescents and young adults in rural areas( 2023-11)This paper presents the concept, a prototype and the initial test of a web app that supports the political participation of young people in rural areas in ermany. Rural adolescents and young adults are often not adequately represented in the political dialogue. With the proposed web app, the authors want to address this issue and create new forms of participation. Within this paper, the requirements engineering and design process in cooperation with the target group is described. Based upon the users’ input from requirements engineering workshops and a design thinking workshop, a user interface of the planned application was designed and optimized. Subsequently, a first version of the web app was developed and tested in an event with young people. Our research shows that requirements of young people in rural areas for the app deviate from those of professional youth care organizations, thus creating challenges for the rollout of the proposed application.
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PublicationAI Based Predictive Maintenance as a Key Enabler for Circular Economy: The KYKLOS 4.0 Approach( 2023-09-27)Circular economy (CE) is a recent model of production and consumption. According to the European Parliament, this model simply extends the life cycles of products through sharing, leasing, reusing, repairing, refurbishing, and recycling existing materials as much as possible. Digitalization plays a crucial role in the transformation towards a sustainable circular economy. By providing accurate information about appliances and machines conditions, minimizing waste and promoting a longer life for them can be achieved. Predictive maintenance (PdM) is a service using data analytics and aiming at detecting machine failures, degraded performance, or a downtrend in product quality before one of these occur. Due to the advantages that artificial intelligence (AI) techniques currently offer, more and more predictive maintenance solutions start incorporating them in order to better analyse the gathered data. This paper gives an overview of the Deep Learning toolkit that has been developed within the European project KYKLOS 4.0, and which provides a bunch of functionalities including data collection and preprocessing, models definition, and models validation. This toolkit is also endowed with a graphical user interface facilitating its use. It has also been tested with publicly available datasets as well as datasets collected in manufacturing environments. In the current paper, the toolkit will be described in the context of a pilot where the data were collected from a shipyard located in the Astander city, in Spain.
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PublicationChallenges in publishing research data - a FraunhoferCase Study( 2023-08-14)
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PublicationInfluence of the active-to-passive area ratio on the electrically induced strain of a fiber-reinforced dielectric elastomer actuator( 2023)There is an increasing interest to use novel elastomers with inherent or modified advanced dielectric and mechanical properties, as components of dielectric elastomer actuators (DEA). This requires corresponding techniques to assess their electromechanical performance. One performance criterion is the electrically induced deformation of the active electrode area. In this work, a rectangular DEA is used to investigate the influence of the ratio between the active electrode and the passive area on the actuator deformation. For this purpose, a dielectric silicone film is bonded on one surface to a unidirectional carbon fiber fabric. Thereby, highly anisotropic mechanical properties are implemented. When strains are applied perpendicular to the fiber direction, the composite hardly contracts in the fiber direction due to the superior stiffness of the fibers. In addition, the conductive fiber structure also acts as a highly anisotropic compliant electrode. By application of a second paste-like electrode onto the silicone film a DEA is created that operates in a pure shear configuration. This assembly enables the modification of the active-to-passive area ratio and the investigation of its effect on the actuator deformation. Image-based measurements are used to determine the strain of the active electrode area. The experimental results are compared to a lumped-parameter model that considers the electromechanical properties of the fiber-reinforced DEA. In summary, the ratio of the active-to-passive area has a significant influence on the measured deformation. Especially for novel actuator materials that do not exhibit large strains, an active-to-passive ratio of 50 % proves to be particularly advantageous.
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PublicationPilot Study on Interaction with Wide Area Motion Imagery Comparing Gaze Input and Mouse Input( 2023)
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PublicationUltrarapid Industrial Large-Area Processing Using Laser Interference Patterning Methods( 2023)Fabrication of two- and three-dimensional structures in the micro- and nano-range allows a new degree of freedom for the design of materials by tailoring desired material properties and, thus, obtaining enhanced functionalities. Such complex designs are only possible using novel fabrication techniques with high resolution, even in the nanoscale range. Additionally, the implementation of methods capable to produce the mentioned structures into industrial applications requires the ability to process large areas at high throughputs. An innovative solution for high-speed surface patterning of periodic structures is laser-based interferometric methods, such as laser interference lithography (LIL) and Direct Laser Interference Patterning (DLIP). Here, periodic structures can be produced in different materials by overlapping a certain number of laser beams over the material’s surface. These methods are introduced in this chapter, showing different processing systems and configurations, demonstrating the possibility for the fast and precise tailoring of material surface microstructures and topographies on industrial relevant scales. Finally, several application examples are described.
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PublicationArea reconnaissance with heterogeneous groups of autonomous systems( 2023)In the last years Unmanned Vehicles for different environments (UxVs) have been recognized as relevant game changers and key technologies for a wide range of military and civilian applications. Even parallel deployment of heterogeneous autonomous assets as swarms or cooperating teams is no longer science fiction, but a realistic operational scenario. Their effectiveness can be significantly increased by optimization of number, capabilities and application strategy of assigned assets, particularly in time-critical tasks (e.g. the search for missing persons, disaster relief and modern warfare operations). Especially, the movements of the vehicles must be carefully managed. However, the use of small UxVs is often accompanied by limitations like short mission time and limited sensor coverage, which in turn can be compensated by the intelligent assignment of vehicles with increased autonomy in cooperating groups. An important basis for efficient and effective autonomous reconnaissance, especially in swarming or teaming scenarios, is movement optimization considering the capabilities of the heterogeneous vehicles equipped with different sensor systems operating in a combined mission. For this purpose, algorithms have been developed at Fraunhofer IOSB that enable appropriate planning and dynamic processing in very different situations for heterogeneous groups of cooperating vehicles. In the following, two exploration methods for reconnaissance missions are described in more detail and their possibilities are discussed and compared.
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PublicationAutomatisierte Analyse von Bruchflächen mittels künstlicher neuronaler Netzwerke (KNN) für kerntechnisch relevante Sicherheitskomponenten( 2023)Für die sichere Bewertung von kerntechnisch relevanten Sicherheitskomponenten ist eine präzise und zuverlässige Analyse der Bruchflächen nach erfolgtem Prüfvorgang erforderlich. Auf einem eigens erstellten Bruchflächen-Datensatz konnten Modelle mit verschiedenen bekannten neuronalen Netzwerkarchitekturen zur Bildsegmentierung trainiert werden. Die Auswertung der an einem Testdatensatz erzielten Modellgüten "mIoU" zeigte, dass die untersuchten Architekturen sehr gut zur pixelfeinen Klassifizierung der Bruchmechanismen geeignet sind. Darauf aufbauend konnten an den erzeugten Masken über die sog. Area Average Methode Anrisslängen vermessen werden. Die automatisierten Risslängenmessung zeigte dabei statistisch nachweisbar eine sehr hohe Präzision, Vergleichbarkeit und Wirtschaftlichkeit.
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PublicationInfluence of Medial Patellofemoral Ligament Reconstruction on Patellofemoral Contact in Patients With Low-Flexion Patellar Instability: An MRI Study( 2023)Background: Medial patellofemoral ligament (MPFL) reconstruction is a well-established procedure for the treatment of patients with patellofemoral instability (PFI) at low flexion angles (0°-30°). Little is known about the effect of MPFL surgery on patellofemoral cartilage contact area (CCA) during the first 30° of knee flexion. Purpose/Hypothesis: The purpose of this study was to investigate the effect of MPFL reconstruction on CCA using magnetic resonance imaging (MRI). We hypothesized that patients with PFI would have a lower CCA than patients with healthy knees and that CCA would increase after MPFL reconstruction over the course of low knee flexion. Study Design: Cohort study; Level of evidence, 2. Methods: In a prospective matched-paired cohort study, the CCA of 13 patients with low-flexion PFI was determined before and after MPFL reconstruction, and the data were compared with those of 13 healthy volunteers (controls). MRI was performed with the knee at 0°, 15°, and 30° of flexion in a custom-designed knee-positioning device. To suppress motion artifacts, motion correction was performed using a Moiré Phase Tracking system via a tracking marker attached to the patella. The CCA was calculated on the basis of semiautomatic cartilage and bone segmentation and registration. Results: The CCA (mean ± SD) at 0°, 15°, and 30° of flexion for the control participants was 1.38 ± 0.62, 1.91 ± 0.98, and 3.68 ± 0.92 cm2, respectively. In patients with PFI, the CCA at 0°, 15°, and 30° of flexion was 0.77 ± 0.49, 1.26 ± 0.60, and 2.89 ± 0.89 cm2 preoperatively and 1.65 ± 0.55, 1.97 ± 0.68, and 3.52 ± 0.57 cm2 postoperatively. Patients with PFI exhibited a significantly reduced preoperative CCA at all 3 flexion angles when compared with controls (P ≤.045 for all). Postoperatively, there was a significant increase in CCA at 0° of flexion (P =.001), 15° of flexion (P =.019) and 30° of flexion (P =.026). There were no significant postoperative differences in CCA between patients with PFI and controls at any flexion angle. Conclusion: Patients with low-flexion patellar instability showed a significant reduction in patellofemoral CCA at 0°, 15°, and 30° of flexion. MPFL reconstruction increased the contact area significantly at all angles.
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PublicationApplication of experimental and analytical approaches in characterizing coronary stents( 2023)Coronary artery disease (CAD) affects every fifth person in the world. The gold-standard treatment for CAD is stent implantation, however, the existing therapy is not sufficient due to many reasons. For instance, in-stent restenosis, biocompatibility, controlled degradation rate, protein adsorption, and adequate endothelialization are still the main concerns. In the last two decades, the field of stent technology has been grown rapidly and many new stent types and in vitro testing methods for stent characterization have been developed to minimize the aforementioned issues. In this vicinity, there are still many unaddressed issues: i) the quantitative analysis of corrosion is conducted with simpler samples made of stent material instead of stents, in most cases due to the absence of a mathematical model to calculate the entire stent surface area (ESSA); ii) in vitro stent testing in environments that are very far from actual physiological environments; iii) Evaluation of the influence of in-vitro test conditions on coated metallic stents; iv) absence of flow-induced shear stress (FISS) corrosion model, to mention a few. This thesis presents the novel ESSA model, the fluid dynamic experimental setup with the integration of various sensors and pH control, the influence of in vitro degradation behavior of the titanium oxynitride (TiOxNy) coated stainless steel stents and anodized AZ31 samples, and the FISS corrosion model. The results show some important contributions in this field, however, there is still a huge potential for the development of promising stent characterization solutions.
