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Flood-induced building damage assessment in Germany: Evaluating data sources for rapid disaster response
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Biomass-based antimicrobial cellulose aerogels as an alternative to plastic materials and theoretical studies of gel formation
No full textCellulose aerogels are polysaccharide-based materials with high potential to become a novel, sustainable thermal insulation and filter material. The fact that cellulose is a component commonly found in biomass, gives great potential to develop sustainable process and materials with exceptional physical properties.
The aim of the presented research is the exploitation of agricultural lignocellulosic residues to develop cellulose aerogels for several applications as an alternative to current fossil-based plastic materials. The project “GelSus” focuses on the production of cellulose aerogels with antimicrobial properties for sustainable food-packaging, filters and thermal insulation, whereas project “PISA” focuses on the pilot scale production of cellulose aerogels to be used as a sustainable thermal insulation in buildings.
The objectives include the extraction of the cellulose from the lignocellulosic biomass with an alkali-based process and the synthesis of the cellulose aerogels, using the sodium hydroxide-urea approach to generate the cellulose solution. Additionally, material models for cellulose aerogels are developed from atomic to product scale. Furthermore, the modification of the cellulose aerogels is studied, to make them more resistant against bacteria resulting in a longer service life of these cellulose aerogels.
The obtained results indicate significant potential of cellulose aerogels as novel, sustainable thermal insulation with good antimicrobial properties. Good agreement of experimental and numerical observations was proven, indicating clear potential of the developed numerical approach for virtual representation of the chosen biopolymer-based aerogel system
Investigation of the relationship between settlement structure and tweet density within rapidly growing settlements in Africa
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Mapping aids using output-directed programming increase novices' performance in programming mobile robotic systems
No full textAbstract
Context:
Novices programming robotic systems’ behavior, like quadcopter missions, face several challenges and require adequate support to overcome initial barriers. One approach to support novices is to display multiple representations such as graphical previews along with the code editor. Such supportive representations, however, also pose challenges for novices: finding corresponding information in the code and in the preview. To facilitate this, mapping aids can be implemented to clarify the connections between code and preview and foster a deeper understanding. Using output-directed programming, that is, adding the ability to reverse expression evaluation in the domain-specific language, is a promising basis for easily creating and implementing mapping aids.
Objective:
We investigated, whether mapping aids based on output-directed programming can improve learning language semantics and overall program correctness and how these mapping aids support novices while implementing quadcopter missions.
Method:
In our study, we tested
participants while interacting and learning in an online programming environment. Using our 2x2 between-subject design study, we investigated the effects of two mapping aids: highlighting (supports to find element-based connections in the environment) and dynamic linking (supports finding similarities on the semantic level of the content) on program correctness including a typical error, learning outcomes as well as traces of learning strategies.
Results:
While highlights were more helpful for implementing the quadcopter missions (mission 1:
**,
), dynamic linking improved learning outcomes on the comprehension (
,
*,
) and application level (
,
*,
). Traces of learning strategies were related to higher program correctness (organizing (changes in the preview)):
,
***; elaborating (time engaging in the task)):
***) and higher learning outcomes (organizing:
,
***; elaborating :
,
***).
Conclusions:
Implementing mapping aids through output-directed programming supports novices in developing a better semantic understanding of the domain specific language. Depending on the program tasks, different mapping aids might be effective. Based on traces of learning strategies while programming, adaptive interactive programming environments might support users individually
Techno-economic analysis of offshore methanol production with consideration of fluctuating input flows
No full textDie Integration erneuerbarer Energien in Power-to-X-Systeme erfordert flexible chemische
Produktionsprozesse, die im Teillastbetrieb arbeiten können. Diese Arbeit untersucht die
Machbarkeit der Teillastproduktion von Methanol aus Wasserstoff und Kohlendioxid und
bewertet deren Auswirkungen auf Wasserstoff- und Methanolkosten unter variabler OffshoreWindversorgung. Aspen Plus®-Simulationen wurden durchgeführt, um das Verhalten der
wichtigsten Reaktions- und Trennstufen bei reduzierten Durchflussraten zu analysieren, mit
Teillasten von 50 %, 75 % und 100 % der Nennkapazität. Die Ergebnisse zeigen, dass
Reaktoren und Wärmetauscher tiefe Lastreduktionen tolerieren, die Destillationskolonnen
jedoch den betrieblichen Engpass darstellen und unter ~50 % der Auslegungskapazität
hydraulisch instabil werden. Niedrigere Lasten führten zu vermindertem Flüssig-DampfKontakt, reduzierter Stoffübertragungseffizienz und Abweichungen in den
Wärmetauscherleistungen, während verlängerte Reaktorverweilzeiten diese Effekte teilweise
ausgleichen, sodass bei reduzierten Durchflussraten leicht höhere Umsetzungen erzielt wurden.
Betriebliche Anpassungen waren notwendig, um die Produktspezifikationen bei Teillast
aufrechtzuerhalten. Die techno-ökonomische Analyse zeigte, dass flexible
Wasserstoffnachfrage durch variierende Lastanpassungsintervalle die Systemleistung erheblich
verbesserte und Kosten senkte. Schnellere Anpassungen steigerten die Windnutzung,
reduzierten den Wasserstoffspeicherbedarf und optimierten die Kapitalaufteilung, wodurch die
LCOH (Levelized Cost of Hydrogen) und LCOM (Levelized Cost of Methanol) verringert wurden. Trotz leicht erhöhter Elektrolyser-Kapazität sanken die Gesamtkosten aufgrund von Einsparungen bei Speicher-, Plattform- und Windinfrastruktur. Wasserstoff bleibt der größte Kostenfaktor. Die Arbeit identifiziert die Trennstufen als technischen Engpass im Teillastbetrieb, während die Speicherauslegung das wirtschaftliche Nadelöhr darstellt. Hybride und modulare Lösungen für Destillation und Wärmeaustausch könnten die minimale realisierbare Last, Prozesseffizienz und Wirtschaftlichkeit verbessern. Die Ergebnisse unterstreichen die Bedeutung betrieblicher
Flexibilität in Power-to-Methanol-Systemen und zeigen einen Weg zur wirtschaftlich tragfähigen Integration variabler erneuerbarer Energien bei gleichzeitiger Produktqualität und Systemzuverlässigkeit
Hybrid Simulation Models for high-performance and versatile airport simulations: Integrating System Dynamics and Agent-Based Approaches
No full textThis paper outlines a novel simulation approach that integrates multiple simulation concepts. Agent-based network models are combined with a set of state charts rules. The resulting simulation then interacts with an energy flow simulation based on system dynamics rules at runtime. The work is based on the many challenges that modern airports face, such as growing passenger numbers, strict safety regulations, unpredictable disruptions and the worsening climate crisis. The transformation process in aviation is therefore attracting increasing attention. In order to capture this complexity, simulation modelling has become an integral part of strategic and operational decision-making processes. Our hybrid modelling approach aims to provide a comprehensive framework for analysing both macro-level system behaviour and micro-level agent behaviour.
The simulation's high-speed capability makes it ideal for What-If cycles, enabling efficient analysis and evaluation of management decisions on incidents by presenting the results to the user in a capacity-based view. This simulation approach is intended to promote the integration of the Airport Collaborative Decision-Making concept (A-CDM), enabling different airport stakeholders to make joint decisions