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Experimental and numerical investigation on the effect of pressure on micromix hydrogen combustion
(2021)
The micromix (MMX) combustion concept is a DLN gas turbine combustion technology designed for high hydrogen content fuels. Multiple non-premixed miniaturized flames based on jet in cross-flow (JICF) are inherently safe against flashback and ensure a stable operation in various operative conditions.
The objective of this paper is to investigate the influence of pressure on the micromix flame with focus on the flame initiation point and the NOx emissions. A numerical model based on a steady RANS approach and the Complex Chemistry model with relevant reactions of the GRI 3.0 mechanism is used to predict the reactive flow and NOx emissions at various pressure conditions. Regarding the turbulence-chemical interaction, the Laminar Flame Concept (LFC) and the Eddy Dissipation Concept (EDC) are compared. The numerical results are validated against experimental results that have been acquired at a high pressure test facility for industrial can-type gas turbine combustors with regard to flame initiation and NOx emissions.
The numerical approach is adequate to predict the flame initiation point and NOx emission trends. Interestingly, the flame shifts its initiation point during the pressure increase in upstream direction, whereby the flame attachment shifts from anchoring behind a downstream located bluff body towards anchoring directly at the hydrogen jet. The LFC predicts this change and the NOx emissions more accurately than the EDC. The resulting NOx correlation regarding the pressure is similar to a non-premixed type combustion configuration.
Purpose Vascular risk factors and ocular perfusion are heatedly discussed in the pathogenesis of glaucoma. The retinal vessel analyzer (RVA, IMEDOS Systems, Germany) allows noninvasive measurement of retinal vessel regulation. Significant differences especially in the veins between healthy subjects and patients suffering from glaucoma were previously reported. In this pilot-study we investigated if localized vascular regulation is altered in glaucoma patients with altitudinal visual field defect asymmetry. Methods 15 eyes of 12 glaucoma patients with advanced altitudinal visual field defect asymmetry were included. The mean defect was calculated for each hemisphere separately (-20.99 ± 10.49 pro- found hemispheric visual field defect vs -7.36 ± 3.97 dB less profound hemisphere). After pupil dilation, RVA measurements of retinal arteries and veins were conducted using the standard protocol. The superior and inferior retinal vessel reactivity were measured consecutively in each eye. Results Significant differences were recorded in venous vessel constriction after flicker light stimulation and overall amplitude of the reaction (p \ 0.04 and p \ 0.02 respectively) in-between the hemispheres spheres. Vessel reaction was higher in the hemisphere corresponding to the more advanced visual field defect. Arterial diameters reacted similarly, failing to reach statistical significance. Conclusion Localized retinal vessel regulation is significantly altered in glaucoma patients with asymmetri altitudinal visual field defects. Veins supplying the hemisphere concordant to a less profound visual field defect show diminished diameter changes. Vascular dysregulation might be particularly important in early glaucoma stages prior to a significant visual field defect.
Through a mirror darkly – On the obscurity of teaching goals in game-based learning in IT security
(2021)
Teachers and instructors use very specific language communicating teaching goals. The most widely used frameworks of common reference are the Bloom’s Taxonomy and the Revised Bloom’s Taxonomy. The latter provides distinction of 209 different teaching goals which are connected to methods. In Competence Developing Games (CDGs - serious games to convey knowledge) and in IT security education, a two- or three level typology exists, reducing possible learning outcomes to awareness, training, and education. This study explores whether this much simpler framework succeeds in achieving the same range of learning outcomes. Method wise a keyword analysis was conducted. The results were threefold: 1. The words used to describe teaching goals in CDGs on IT security education do not reflect the whole range of learning outcomes. 2. The word choice is nevertheless different from common language, indicating an intentional use of language. 3. IT security CDGs use different sets of terms to describe learning outcomes, depending on whether they are awareness, training, or education games. The interpretation of the findings is that the reduction to just three types of CDGs reduces the capacity to communicate and think about learning outcomes and consequently reduces the outcomes that are intentionally achieved.
The transition within transportation towards battery electric vehicles can lead to a more sustainable future. To account for the development goal ‘climate action’ stated by the United Nations, it is mandatory, within the conceptual design phase, to derive energy-efficient system designs. One barrier is the uncertainty of the driving behaviour within the usage phase. This uncertainty is often addressed by using a stochastic synthesis process to derive representative driving cycles and by using cycle-based optimization. To deal with this uncertainty, a new approach based on a stochastic optimization program is presented. This leads to an optimization model that is solved with an exact solver. It is compared to a system design approach based on driving cycles and a genetic algorithm solver. Both approaches are applied to find efficient electric powertrains with fixed-speed and multi-speed transmissions. Hence, the similarities, differences and respective advantages of each optimization procedure are discussed.
Conventional EEG devices cannot be used in everyday life and hence, past decade research has been focused on Ear-EEG for mobile, at-home monitoring for various applications ranging from emotion detection to sleep monitoring. As the area available for electrode contact in the ear is limited, the electrode size and location play a vital role for an Ear-EEG system. In this investigation, we present a quantitative study of ear-electrodes with two electrode sizes at different locations in a wet and dry configuration. Electrode impedance scales inversely with size and ranges from 450 kΩ to 1.29 MΩ for dry and from 22 kΩ to 42 kΩ for wet contact at 10 Hz. For any size, the location in the ear canal with the lowest impedance is ELE (Left Ear Superior), presumably due to increased contact pressure caused by the outer-ear anatomy. The results can be used to optimize signal pickup and SNR for specific applications. We demonstrate this by recording sleep spindles during sleep onset with high quality (5.27 μVrms).
Seit dem Zeitpunkt seiner Gründung im Jahr 1909 lautet der Auftrag des Kölner Museums für Ostasiatische Kunst, der europäischen Gesellschaft die Kunst Ostasiens nahezubringen, für ein besseres Verständnis und die Wertschätzung seiner Kultur zu sorgen und somit auch Rassismus und kolonialistischem Denken entgegenzuwirken – ein Anliegen, welches noch heute von unveränderter Relevanz und Dringlichkeit ist.
Im Zentrum des neuen Erscheinungsbildes steht der gestürzte Buchstabe K und die somit entstehende Kombination von horizontaler und vertikaler, traditionell ostasiatischer Leserichtung deutet auf visueller Ebene ein Zusammenspiel zwischen den Kulturen an. Die Farbgebung des neuen Erscheinungsbildes greift die ruhige Atmosphäre des Museums auf und sorgt in Kombination mit einem streng gegliederten Raster für klare Struktur und Orientierung.
Yocu ist ein Konzept für den Gesundheitssektor, dass unter der Betrachtung der relevanten Trends und der Researchergebnisse den Therapieansatz des „Schröpfen“ in einen neuen modernen Kontext setzt, dabei aber die Vorteile der traditionellen Heilkunst nicht außer Acht lässt. Es handelt sich um ein Therapieprodukt für fasziale Verklebungen und Muskel-Skelett-Erkrankungen.
Mit Yocu bekommen Nutzer die Möglichkeit, sich selbst erfolgreich präventiv oder bei Beschwerden zu behandeln. Das könnte nicht nur die körperliche Gesundheit fördern, sondern auch das Gespür für den eigenen Körper. Seine körperlichen Bedürfnisse besser einschätzen zu können und in der Lage zu sein, diese zu erfüllen, stellt das Ziel des Konzepts dar.
Mit dem gewählten „Healthtech“ Ansatz soll der Zugang zur Selbsttherapie für Laien ermöglicht werden. Zusätzlich könnte das Konzept die Arbeit für Physiotherapeut:innen und Fitnesstrainer:innen erleichtern. Durch die Symbiose eines elektronischen Therapieproduktes mit einer Anwendungsapp ist die Behandlung punktgenau steuerbar und basiert nicht mehr ausschließlich auf Gefühl oder Erfahrung. Durch die Einsicht aller wichtigen Parameter, wird das Verständnis der Therapiemethode gefördert und Vertrauen hinsichtlich des Produkts geschaffen.
This paper discusses a new way of inflight power regeneration for electric or hybrid-electric driven general aviation aircraft with one powertrain for both configurations. Three different approaches for the shift from propulsion to regeneration mode are analyzed. Numerical cal-culation and wind tunnel results are compared and show the highest regeneration potential for the "Windmill" approach, where the propeller blades are flipped, and rotation is reversed. A combination of all regeneration approaches for a realistic flight mission is discussed.
Mit MULO wurde eine Serie multifunktionaler Objekte für den Wohnbereich entworfen. In Zeiten des Überangebots und des ständigen Wohnraumwechsels soll der Nutzer dieser Objekte mit einem modernen und schlichten Design unterstützt werden, das zu jedem Anlass passt. Die minimalistische Ästhetik mit hohem Komfort orientiert sich dabei an den Bedürfnissen des Endverbrauchers.
Als Verwandlungskünstler bereichert MULO jeden Wohnraum. Die gesamte Serie ist unter der Berücksichtigung der schnelllebigen und sich wandelnden Welt entworfen worden. Mit multifunktionalen Objekten ist das Produkt den flexiblen Anforderungen und Bedürfnissen des Menschen gewachsen. Die Bereiche Wohnen, Leben, Arbeiten, Schlafen und Entspannen werden durch das Sofa- , das Tisch- und das Keramik-System optimal abgedeckt. Durch die Verwendung von nachhaltigen und recycelbaren Materialien, setzt MULO ein kleines Statement und hinterlässt nachhaltig Eindruck.
Digital Shadows as the aggregation, linkage and abstraction of data relating to physical objects are a central vision for the future of production. However, the majority of current research takes a technocentric approach, in which the human actors in production play a minor role. Here, the authors present an alternative anthropocentric perspective that highlights the potential and main challenges of extending the concept of Digital Shadows to humans. Following future research methodology, three prospections that illustrate use cases for Human Digital Shadows across organizational and hierarchical levels are developed: human-robot collaboration for manual work, decision support and work organization, as well as human resource management. Potentials and challenges are identified using separate SWOT analyses for the three prospections and common themes are emphasized in a concluding discussion.
Experimental investigation of behaviour of masonry infilled RC frames under out-of-plane loading
(2021)
Masonry infills are commonly used as exterior or interior walls in reinforced concrete (RC) frame structures and they can be encountered all over the world, including earthquake prone regions. Since the middle of the 20th century the behaviour of these non-structural elements under seismic loading has been studied in numerous experimental campaigns. However, most of the studies were carried out by means of in-plane tests, while there is a lack of out-of-plane experimental investigations. In this paper, the out-of-plane tests carried out on full scale masonry infilled frames are described. The results of the out-of-plane tests are presented in terms of force-displacement curves and measured out-of-plane displacements. Finally, the reliability of existing analytical approaches developed to estimate the out-of-plane strength of masonry infills is examined on presented experimental results.
Seismic vulnerability estimation of existing structures is unquestionably interesting topic of high priority, particularly after earthquake events. Having in mind the vast number of old masonry buildings in North Macedonia serving as public institutions, it is evident that the structural assessment of these buildings is an issue of great importance. In this paper, a comprehensive methodology for the development of seismic fragility curves of existing masonry buildings is presented. A scenario – based method that incorporates the knowledge of the tectonic style of the considered region, the active fault characterization, the earth crust model and the historical seismicity (determined via the Neo Deterministic approach) is used for calculation of the necessary response spectra. The capacity of the investigated masonry buildings has been determined by using nonlinear static analysis. MINEA software (SDA Engineering) is used for verification of the structural safety of the structures Performance point, obtained from the intersection of the capacity of the building and the spectra used, is selected as a response parameter. The thresholds of the spectral displacement are obtained by splitting the capacity curve into five parts, utilizing empirical formulas which are represented as a function of yield displacement and ultimate displacement. As a result, four levels of damage limit states are determined. A maximum likelihood estimation procedure for the process of fragility curves determination is noted as a final step in the proposed procedure. As a result, region specific series of vulnerability curves for structures are defined.