500 Naturwissenschaften und Mathematik
Refine
Year of publication
- 2019 (23) (remove)
Document Type
- Part of a Book (13)
- Master's Thesis (6)
- Article (3)
- Conference Proceeding (1)
Has Fulltext
- yes (23)
Keywords
- Biogas (2)
- CALB (2)
- Esterification (2)
- Lipase (2)
- Nitrification (2)
- On-demand production (2)
- Sozialökologie (2)
- :metabolon (1)
- Acceptor reaction (1)
- Agrarökologie (1)
Faculty
- Angewandte Naturwissenschaften (F11) (10)
- Fakultät 10 / :metabolon Institut (4)
- Fakultät 12 / Institut für Technologie und Ressourcenmanagement in den Tropen und Subtropen (4)
- Fakultät 04 / Institut für Versicherungswesen (1)
- Fakultät 06 / Institut für Baustoffe, Geotechnik, Verkehr und Wasser (1)
- Fakultät 09 / Institut Anlagen und Verfahrenstechnik (1)
- Fakultät 09 / Institut für Rettungsingenieurwesen und Gefahrenabwehr (1)
- Fakultät 10 / Institut für Automation & Industrial IT (1)
Resilience in relation to flood risk management (FRM) is not a new concept, yet parts of the FRM community are still struggling to apply it. The main challenge this study addresses is the question as to whether parts of the FRM community should still adopt, or rather “leap‐frog,” resilience. The main purpose is to evaluate whether resilience is a still on‐going trend or, already subsiding. Research suggests that resilience is an on‐going trend that connects research and policy and has gained international recognition as expressed by international guidelines and bodies promoting its research but also its operationalization. Academic literature in the area of FRM also shows a significant continuing development. Resilience enables to analyze dynamics and transformations of riverine areas, or coastal zones in connection to an integrated social‐environmental system approach with more emphasis and conceptual basis than previous concepts. Resilience is more than a short‐lived notion and it appears that FRM researchers cannot avoid addressing it. Resilience often is a convergence of ideas and mainstreaming of efforts, which in many venues is absolutely necessary and can help, for example, to decrease silo‐thinking. But as academics, we have a mandate to remain skeptical and remain on the look‐out for novel ideas, too.
This article is categorized under:
Engineering Water > Planning Water
The quantification of greenhouse gas emissions from aquatic ecosystems requires knowledge about the spatial and temporal dynamics of free gas in sediments. Freezing the sediment in situ offers a promising method for obtaining gas‐bearing sediment samples, unaffected by changes in hydrostatic pressure and sample temperature during core withdrawal and subsequent analysis. This article presents a novel freeze coring technique to preserve the in situ stratigraphy and gas bubble characteristics. Nondestructive X‐ray computed tomography (CT) scans were used to identify and characterize coring disturbances of gravity and freeze cores associated with gassy sediment, as well as the effect of the freezing process on the gas bubble characteristics. Real‐time X‐ray CT scans were conducted to visualize the progression of the freezing process. Additional experiments were conducted to determine the freezing rate to assess the probability of sediment particle/bubble migration, and gas bubble nucleation at the phase transition of pore water to ice. The performance of the freeze coring technique was evaluated under field conditions in Olsberg and Urft Reservoir (Germany). The results demonstrate the capability of the freeze coring technique for the preservation of gas‐bearing sediments and the analysis of gas bubble distribution pattern in both reservoirs. Nevertheless, the obtained cores showed that nearly all gravity and freeze cores show some degree of coring disturbances.
Anaerobic digestion plants have the potential to produce biogas on demand to help balance renewable energy production and energy demand by consumers. A proportional integral (PI) controller is constructed and tuned with a novel tuning method to control biogas production in an optimal manner. In this approach, the proportional part of the controller is a function of the feeding rate and system's degree of stability. To estimate the degree of stability, a simulation‐based soft sensor is developed. By means of the PI controller, the requirement for gas storage capacity of the digester is reduced by approximately 30 % compared to a constant, continuous feeding regime of the digester.
Durch das permanente Wachstum der Weltbevölkerung wird der Bedarf von Textilien stetig steigen. Die Produktvielfalt sowie der Konsum der Textilien werden immer größer. Die aktuellen Recyclingtechniken ermöglichen es nicht, den Rohstoffkreislauf für Textilien zu schließen. Dies liegt auch darin begründet, dass derzeit große Mengen der Textilien aus Mischgeweben zwischen Baumwolle und PET bestehen. Die Trennung dieser Komponenten ist jedoch eine Grundvoraussetzung für die Entwicklung eines geschlossenen Rohstoffkreislaufs und stellt gleichzeitig eine große Herausforderung für das Recycling dar. Durch chemische Recyclingverfahren können die Rohstoffe getrennt, aufbereitet und in die Textilproduktion zurückgeführt werden. In dieser Arbeit wird aufgezeigt, wie ein chemischer Recyclingprozess, der einen geschlossenen Rohstoffkreislauf erlaubt, technisch realisiert werden kann. Der Prozess erzeugt eine PET-Fraktion und eine Celluloselösung, die in weiteren Verarbeitungsschritten zu einer Regeneratfaser versponnen wird. In dieser frühen Projektphase werden in dieser Arbeit ebenfalls die Investitionsausgaben und die Herstellungskosten für das Verfahren abgeschätzt.
Die vorliegende Masterarbeit behandelt die Bewertung der eingegangenen Unternehmensrisiken im Rahmen der Lebensversicherung und die hiervon abgeleiteten Auswirkungen zur Unternehmenssteuerung.
Dabei wird einerseits die Angemessenheit der sog. „Standardformel“ nach Solvency II überprüft, die in den europäischen Mitgliedsstaaten einen weitestgehend einheitlichen Ansatz bei der Bewertung der Risiken von Versicherungsunternehmen verwendet. Andererseits werden unter ökonomischen Überlegungen versicherungsmathematische Methoden vorgestellt, wie ein Lebensversicherer seine Risiken unternehmensindividueller ermitteln und damit seinen tatsächlichen Risikokapitalbedarf bestimmen kann.
Zur Quantifizierung der Ergebnisse werden die Berechnungsvorgaben der Standardformel für ausgewählte Risikomodule nachgebildet und mit den in dieser Arbeit vorgestellten unternehmensindividuellen Berechnungen verglichen und analysiert. Es zeigt sich, dass trotz der Komplexität des Solvency II-Modells eine noch differenziertere Herangehensweise notwendig ist, damit ein einzelnes Unternehmen seine Risiken adäquat und möglichst individuell bestimmen kann. Zur Gewährleistung einer nicht bestandsgefährdenden Unternehmensfortführung müssen die Versicherungsunternehmen bei Betrachtung ihrer Risiken mithilfe des EU-weiten Aufsichtssystems Solvency II in der Lage sein, die korrekten Rückschlüsse zur Unternehmenssteuerung zu ziehen. Die in dieser Arbeit vorgestellten versicherungsmathematischen Ansätze können dabei den Prozess zur unternehmenseigenen Risiko- und Solvabilitätsbeurteilung (ORSA) unterstützen.
The post-conflict setting in Colombia resulted after the signing of the peace agreement between the Revolutionary Armed Forces of Colombia (FARC) and the national Government at the end of 2016, faces two main problems. On one hand, the environmental degradation and the pressure over the ecosystems now exposed to the economic and socio-demographic dynamics of the country; and on the other hand, the increase of violence in rural areas characterized by the abundance of natural resources. These two problems can be linked through the complex dynamics of natural resources appropriation. Among the natural resources affecting the course of the post-conflict in Colombia, gold appears as one of the most relevant sources of violence and environmental degradation. This condition makes it crucial to understand the complex local dynamics of mining regions in order to propose alternatives for consolidating a sustaining peace. The armed groups, the state, the private companies, and traditional gold mining communities are all stakeholders involved in gold mining and the conflicts around this activity. Nevertheless, communities have been denied as a formal actor.
This work aims to give voice to those communities, understanding them as a key actor for peacebuilding. This research seeks to understand the relationship between gold mining and the social-armed conflict in Colombia, to identify which are the drivers for the increasing of this activity during the post-conflict, as well as which strategies developed by traditional gold mining communities can contribute to peacebuilding. Thus, an integrative analytical framework is developed. This theoretical framework integrates 1) environmental peacebuilding to evaluate the possibilities of natural resources to becoming tools for cooperation, and 2) political ecology to clarify, from a multi-scalar approach, the socio-political context in which the conflict takes place. Hence, from a qualitative approach that involves several ethnographic methods is found that artisanal-ancestral miners and traditional miners organized to remain in their territories in a context of dispossession, have developed socio-ecological systems and natural resources management strategies relevant to implement initiatives of environmental peacebuilding that can be sustained over time and aimed to overcome the structural causes of violence and environmental degradation.
STEPsCON 2018 was jointly organized by the Faculty of Applied Natural Sciences of TH Köln (Germany) and the University of Oulu (Finland) on the occasion of the 50th anniversary of the Leverkusen – Oulu town twinning. The conference focused on sustainability issues and covered the current state of research in four key topics:
1. Sustainable Medicine and Pharmaceuticals
2. Resources and Bioremediation
3. Sustainable Chemistry & Industrial Biotechnology
4. Innovative Materials & Formulations
For use in a landfill, a laboratory reactor for safe and environmentally friendly biological utilization of low-concentration methane gas will be further developed. The current principle of denitrification-coupled aerobic methane oxidation will be replaced by methane oxidation under anaerobic conditions. Anaerobic methane oxidation offers the advantage that, in addition to methane, nitrate also undergoes biodegradation. Another advantage is that the oxygen content can be significantly lower. This reduces the risk of the formation of an explosive atmosphere in the reactor. Currently, the principle of anaerobic methane oxidation is known. However, organisms capable of doing so are not yet available as a pure culture. Therefore, several biomasses were probed for the ability of anaerobic methane oxidation. It was found that moor-heavy sediment, activated sludge from the leachate treatment plant and biomass from the local biogas plant oxidize methane after the natural carbon source (C source) was been removed.
The synthesis of 17-hydroxy-oleic acid based oligomeric esters was investigated with immobilized Pseudozyma antarctica Lipase B and hexanediol as co-substrate. The effects of different reaction parameters on velocity and product composition at equilibrium conditions were analyzed. The synthesis of oleic acid esters was used as a reference system for initial evaluation of reaction parameters. The reaction with oleic acid and hexanediol was fastest at an enzyme concentration of 5% at 60 °C and high conversions of > 90 % were achieved in non-polar solvents in the presence of molecular sieves. In heptane an oleic acid conversion of 96 % was reached with a final diester to monoester ratio of > 4:1. In syntheses trials with 17-hydroxy-oleic acid the formation of oligomers was verified with GPC, however; conversion was generally lower than with oleic acid. Removal of hydroxyl fatty acid monomers and dimers and the formation ester functionalities could be verified by GC analysis. An increase of the degree of oligomerization was observed simultaneously by GPC analysis. The number-average molecular weight was around 1400 in the best trials corresponding to a degree of oligomerization of around 4 units of hydroxyl-fatty acid attached to a hexanediol core. Though transformations were not complete, the final oligomer size was in the lower range of polyester diols used for polyurethane manufacturing.
Due to the worldwide shortage of petrochemical based resources, the usage of renewable bio-based raw materials for established and novel products becomes increasingly important.[1] Such bio-based resources are already used for the fabrication of a variety of products, e. g. paper, lubricants, detergents or cosmetics. In the future they are expected to emerge in many more applications in industry and household.[1]
A very promising approach relies on the use of glycolipids as a source of hydroxy-oleic acid.[2] Microbial glycolipids are produced for instance via fermentation from natural resources such as plant oils and sugar.[3] After fermentation complex product mixtures are obtained with the composition depending on the microorganism, substrate and fermentation time.[3] The successful use of microbial glycolipids and hydroxy-oleic acid (HOA) derived therefrom as bio-based intermediates requires reliable analytical methods as well as robust manufacturing processes for the synthesis and cleavage of bio-based molecules. In order to obtain hydroxy-oleic acids as bio-based intermediates, the acidic cleavage of microbial derived sophorolipid was investigated. In addition the implementation of HOA in polyurethane (PU) systems was explored.