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Comparative study of multi-element modification and rhodium promotion of Co₃O₄-based spinel catalysts for N₂O decomposition
No full textThe removal of nitrous oxide (N₂O) from industrial flue gases remains a significant environmental challenge due to the intrinsic kinetic stability of the N₂O molecule. Among available abatement technologies, the direct catalytic decomposition of N₂O into harmless N₂ and O₂ (deN₂O) represents a promising, reagent-free solution. In this study, we systematically screened a series of catalysts obtained from Co₃O₄ by addition of transition elements, magnesium and aluminum (10 wt%), and analog series with addition of rhodium (Rh; 1 wt%), from which Co-Al-Rh emerged as the most active catalyst formulation. Characterization by H₂-TPR and XPS indicated improvement in the redox performance and increasing weakening of the Co-O bond upon addition of a second element and of Rh. The addition of Rh resulted also in a significant enhancement in catalytic activity. Complementary kinetic studies revealed a shift in the rate-determining step (RDS) between N-O bond cleavage and O₂ desorption, depending on catalyst composition. These results highlight the critical role of Co-O bond weakening in facilitating oxygen mobility and promoting activity
Von der Oberfläche bis zum Meeresboden: Laser-basierte Erfassung von Unterwasservegetation
No full textMusic "Han" Istanbul
No full textIstanbul, die Stadt in der ich aufgewachsen bin ist zwar eine dichte Metropole mit viel Geschichte und Kultur , aber verfügt wenig an nicht kommerzielle Treffpunkte für einen sozialen Austausch. Auf der Suche nach einem möglichen Standort im historischen Handelsgebiet Unkapani weckte ein moderner Bau meine Interesse : Der Gewerbebau IMC in Istanbul erbaut in den 1960er Jahren, ursprünglich als ein Markt für Textilhändler, steht heute zum Teil leer und wirkt verlassen. Im Zuge der Revitalisierung der Nachbarschaftsgebiete ist der weitläufige Bestand in den letzten Jahren vom Abriss bedroht. Um einen Abbruch entgegenzuwirken möchte ich mit meinem Projekt einen Vorschlag für eine Umnutzung vorbringen. Der Bestand soll eine neue Funktion bekommen und eine Chance für einen öffentlichen Aufenthalt im städtischen Kontext sowie eine Perspektive für die Zukunft darstellen.Einer der weitläufigen Gewerbeblöcke wurde jahrelang als Musikmarkt genutzt und war für viele Musikliebende ein bekannter Aufenthaltsort. Am Beispiel des Musikmarktes ist ein Umnutzungskonzept zu entwickeln, um das Gebäude und die Geschichte der Musik wieder aufleben zu lassen. Zufolge der Veränderungen wie z.B Digitalisierung, erfüllt das Gebäude nicht mehr seine herkömmliche Nutzung als Markt. Der innerhalb der letzten Jahren einem ökonomischen und sozialen Wandel unterliegende Musikmarkt soll im Rahmen der Diplomarbeit eine neue Funktion mit Raum für Musik bekommen.Istanbul, the city where I grew up, is a dense metropolis with a lot of history and culture, but has few non-commercial meeting places for social interaction. While searching for a possible location in the historic trading area of Unkapani, a modern building caught my attention: The IMC commercial building in Istanbul, built in the 1960s, originally as a market for textile traders, is now partly empty and looks deserted. In the course of the revitalization of the neighboring areas, the existing building also has been threatened with demolition in recent years. In order to preventing the demolition, I would like to put forward a proposal for a chance of use with my project. The existing building is to be given a new function. The conversion should represent an opportunity for a public space in an urban context as well as a perspective for the future.The extensive commercial building consists of several building blocks. One of these blocks was used as a music market for many years and was a familiar location for many music lovers in the city. Using the multi-storey music market as an example, a conversion concept is to be developed in order to revitalise the building and the history of music. As a result of economic, social and technological changes such as digitalisation, online sales and the pandemic, the building no longer fulfils its traditional use as a market
Leveraging the Subtle: Hidden Factors in Recommender Systems
Full text linkRecommender systems are pivotal in various domains, aiding users in their decision-making. However, current systems often overlook subtle factors that significantly impact user preferences and choices. This work aims to bridge this gap by exploring the conceptof implicit item characteristics -- latent features that influence user decision-making in addition to explicit content. The investigation is divided into three key research areas. Firstly, we explore how to systematically identify and expose implicit item characteristics to enhance recommender systems in two key domains: tourism and news. Using advanced analytics such as cluster analysis and multiple linear regression, we map tourist destinations to the established Seven-Factor Model in tourism. In the news, we employ natural language processing techniques to reveal hidden features essential for tailoring recommendations. Secondly, we introduce a novel system called PicTouRe to elicit tourists' implicit preferences through pictures. Leveraging convolutional neural networks, we translate visual preferences into a Seven-Factor profile for each user, simplifying decision-making and capturing both immediate touristic desires and enduring personality traits. Lastly, we enhance news recommender systems by leveraging sentiment and emotions of news articles. Two models, RobustSentiRec and EmoRec, were developed to capture these implicit characteristics, aligning recommendations more closely with user preferences but also raising ethical concerns around potential sentiment and emotional echo chambers. Our findings offer a robust framework for more nuanced, user-sensitive recommendations, opening new avenues for future research and applications in recommender systems
Democracy between stone and transparency - Transformation of the Globusprovisorium into a town hall in Zurich
No full textDas als „Globusprovisorium“ bezeichnete Bauwerk in Zürich bildet den historischen und räumlichen Ausgangspunkt dieser Diplomarbeit. In einer Zeit, in der urbane Verdichtung und der Abriss bedeutender Bausubstanz vorherrschen, steht das Globusprovisorium als Symbol für den Erhalt und die adaptive Umnutzung historischer Gebäude. Seine Rolle im politischen Diskurs, insbesondere die Globuskrawalle von 1968, sowie seine städtebauliche Lage an der Limmat prägen die theoretische Auseinandersetzung. Im Zentrum stehen die Fragen, wie Transparenz, Zugänglichkeit, Flexibilität und Kommunikation in bestehenden Strukturen räumlich umgesetzt werden können. Ferner wird erarbeitet, welche Potenziale die adaptive Wiederverwendung sowie der Einsatz von Naturstein, als nachhaltigem, repräsentativem Material für demokratische Architektur, besitzen.Ausgehend von diesen theoretischen Grundlagen wird am Beispiel des Entwurfs für ein neues Rathaus in Zürich erarbeitet, wie historische Elemente des Globusprovisoriums in ein modernes, hybrides Gebäude integriert werden können. Der überwiegende Teil des Bestandes wird erhalten oder an anderer Stelle im Gebäude wiederverwendet. Ergänzt wird diese zirkuläre Struktur durch den neu eingefügten Naturstein, der als tragender Kern dient und sowohl strukturell als auch atmosphärisch Verbindungen schafft. Gestalterisch wird das Bestandsgerüst freigespielt und neu bestückt. Ein offenes Erdgeschoss verbindet Stadt, Limmat und Gebäude. Das Bestandsdach vereint die Nutzungen. Der Ratssaal wird als neuer Hochpunkt gesetzt, während das Bürgerforum in der bestehenden Kubatur verankert bleibt und sich als niederschwelliger Diskursraum zur Stadt öffnet.Es soll ein Raum entstehen, der nicht nur administrative Funktionen erfüllt, sondern als offener Ort auch der politischen Bildung, dem Bürgerdialog und dem öffentlichen Diskurs dient. Dieses Gebäude soll die Verbindung von der Vergangenheit zur Zukunft sichtbar und erlebbar machen und einen Beitrag zur Diskussion über den verantwortungsvollen Umgang mit historischer Bausubstanz leisten. Der Entwurf zeigt, wie gestalterische Transformation, Materialkreisläufe und ein bewusster Umgang mit Naturstein dazu beitragen können, demokratische Prozesse räumlich zu stärken und die Bedeutung des Ortes als politisches Forum in die Zukunft zu tragen.The building in Zurich known as the ‘Globusprovisorium’ forms the historical and spatial starting point for this thesis. At a time when urban densification and the demolition of important buildings are prevalent, the Globusprovisorium stands as a symbol for the preservation and adaptive reuse of historic buildings. Its role in political discourse, particularly the Globus riots of 1968, as well as its urban location on the Limmat River, shape the theoretical discussion. The focus is on questions of how transparency, accessibility, flexibility and communication can be spatially implemented in existing structures. Furthermore, the potential of adaptive reuse and the use of natural stone as a sustainable, representative material for democratic architecture is explored.Based on these theoretical principles, the design for a new town hall in Zurich is used as an example to illustrate how historical elements of the Globusprovisorium can be integrated into a modern, hybrid building. Most of the existing structure will be preserved or reused elsewhere in the building. This circular structure is complemented by the newly inserted natural stone, which serves as a load-bearing core and creates connections both structurally and atmospherically. In terms of design, the existing framework is exposed and refitted. An open ground floor connects the city, the Limmat River and the building. The existing roof unites the uses. The council chamber is set as a new high point, while the citizens‘ forum remains anchored in the existing cubature and opens up to the city as a low-threshold space for discourse.The aim is to create a space that not only fulfils administrative functions, but also serves as an open venue for political education, civic dialogue and public discourse. This building is intended to make the connection between the past and the future visible and tangible, and to contribute to the discussion about the responsible use of historical buildings. The design shows how creative transformation, material cycles and the conscious use of natural stone can help to strengthen democratic processes spatially and carry the significance of the location as a political forum into the future
CFD–experimental assessment of open-tube airlift photobioreactors for CO₂ capture and nutrient removal
No full textThis study presents a novel open-tube airlift photobioreactor (PBR) designed with the support of computational fluid dynamics (CFD) and experimentally compared with closed-tube and wall reactors. A validated Euler–Euler CFD model was ≤ 5 % error, indicating enhanced gas holdup, circulation uniformity, and mass transfer in the open-tube geometry, achieving a volumetric mass transfer coefficient (kLa) of 0.037 s⁻¹ at Usg = 0.05 m.s⁻¹ . Flow analysis confirmed the reduced vortex formation and more streamlined riser–downcomer transitions, which promoted longer bubble residence times. Cultivation with Chlorella vulgaris showed enhanced biological performance: biomass concentration reached 1.8 g.L⁻¹ , nitrate removal was 55 %, phosphate consumption was nearly complete after 10 days, and CO₂ capture efficiency peaked at 85 %, outcompeting conventional flat-panel and bubble column PBRs (60–75 %). These results highlight the open-tube airlift PBR a potential platform for simultaneous CO₂ bio fixation, nutrient removal, and biomass production with high potential for sustainable wastewater treatment
Photo and mechanochemically induced reduction of nitroarenes using ammonia borane
No full textThis study presents an advanced approach for the reduction of nitroarenes to anilines, employing cucurbit[7]uril as a catalyst and ammonia borane as a hydrogen source, signifying noteworthy progression in photochemical supramolecular catalysis. Expanding the capability of ammonia borane, a mechanochemical reduction approach for the same reaction has also been established. Additionally, the developed mechanochemical protocol was successfully extended for similar types of synthetic scenarios, including (a) reductive amidation of nitro compounds with carboxylic acids and (b) amidation of carboxylic acids. The products of these reactions i.e., anilines and amides, are indispensable precursors in the manufacture of pharmaceuticals, agrochemicals, and other chemically significant entities
Completing the hierarchy of rotational defects in monolayer MoS₂ through symmetry-aware evolutionary search
No full textMonolayer molybdenum disulfide (MoS₂) shows a plethora of defect configurations, which constitutes the basis for tailoring material properties through defect engineering. Detailed characterization of these defects remains challenging due to the complexity of the potential energy surface. We efficiently explore the three-fold rotational defect potential energy surface in monolayer MoS₂ by combining an evolutionary algorithm with a machine-learning force field. To improve the performance of the structure searches, the algorithm hierarchically restricts the exploration process to a lower-dimensional subspace, utilizing the symmetry operators associated with the investigated defects. We demonstrate that these constrained trajectories exhibit lower global uncertainty measures during the evolution, produce final structures with lower energy distributions and converge faster. Our approach results in the discovery of several novel structures with reasonable computational effort, thereby completing the hierarchy of rotational defects in MoS₂
Power optimal torque distribution for overactuated electric vehicles: analysis and experimental validation
No full textThe optimal integration of redundant actuators in an overactuated vehicle may be found by considering energy efficiency in the actuator allocation strategy. This paper investigates the potential to reduce the drive power demand of an electric vehicle with wheel individual drive through optimal allocation of drive torques and steering angles at the front and rear wheels. The actuator allocation problem is considered for the entire feasible normal and tangential acceleration range of the vehicle. The influences of electrical power losses of the motor-inverter system and tyre slip power losses on power demand are examined. By just considering the tyre slip power losses, the optimal control allocation reduces the drive power demand up to 20%, with the most significant reduction in the region of medium to high normal and tangential accelerations. The potential power reduction with respect to suboptimal strategies is validated in simulation and experimental tests by implementing the optimal torque distribution strategy as a feed-forward control on a demonstrator vehicle. The theoretically found power reduction gains are experimentally validated