Refine
Year of publication
Document Type
- Article (135)
- Master's Thesis (67)
- Conference Proceeding (34)
- Part of a Book (18)
- Study Thesis (16)
- Working Paper (16)
- Report (11)
- Bachelor Thesis (10)
- Other (5)
- Preprint (2)
Language
- English (315) (remove)
Has Fulltext
- yes (315)
Keywords
- Rückversicherung (30)
- Reinsurance (29)
- Versicherung (25)
- Kölner Forschungsstelle Rückversicherung (22)
- Versicherungswirtschaft (21)
- Germany (17)
- USA (13)
- Market Research (12)
- Export Opportunities (10)
- EOS (9)
Faculty
- Fakultät 12 / Institut für Technologie und Ressourcenmanagement in den Tropen und Subtropen (69)
- Angewandte Naturwissenschaften (F11) (40)
- Fakultät 04 / Institut für Versicherungswesen (35)
- Fakultät 04 / Schmalenbach Institut für Wirtschaftswissenschaften (30)
- Fakultät 07 / Institut für Nachrichtentechnik (14)
- Fakultät 09 / Cologne Institute for Renewable Energy (13)
- Fakultät 09 / Institut für Rettungsingenieurwesen und Gefahrenabwehr (12)
- Fakultät 10 / Advanced Media Institute (12)
- Fakultät 07 / Institut für Medien- und Phototechnik (11)
- Fakultät 10 / Institut Allgemeiner Maschinenbau (10)
The main scope of this work is to develop nano-carbon-based mixed matrix celluloseacetate membranes (MMMs) for the potential use in both gas and liquid separation processes. Forthis purpose, a variety of mixed matrix membranes, consisting of cellulose acetate (CA) polymerand carbon nanotubes as additive material were prepared, characterized, and tested. Multi-walledcarbon nanotubes (MWCNTs) were used as filler material and diacetone alcohol (DAA) as solvent.The first main objective towards highly efficient composite membranes was the proper preparationof agglomerate-free MWCNTs dispersions. Rotor-stator system (RS) and ultrasonic sonotrode (USS)were used to achieve the nanofillers’ dispersion. In addition, the first results of the application of thethree-roll mill (TRM) technology in the filler dispersion achieved were promising. The filler material,MWCNTs, was characterized by scanning electron microscopy (SEM) and liquid nitrogen (LN2)adsorption-desorption isotherms at 77 K. The derivatives CA-based mixed matrix membranes werecharacterized by tensile strength and water contact angle measurements, impedance spectroscopy,gas permeability/selectivity measurements, and water permeability tests. The studied membranesprovide remarkable water permeation properties, 12–109 L/m2/h/bar, and also good separationfactors of carbon dioxide and helium separations. Specifically, a separation factor of 87 for 10%He/N2feed concentration and a selectivity value of 55.4 for 10% CO2/CH4feed concentrationwere achieved.
Elaeis guineensis Jacq. or oil palm is a native species of West Africa. Its oils, extracted from the fruit mesocarp and the kernel are widely used in the food industry, industrial applications, and bioenergy production. Due to its versatility, profitability and growing demand, the global oil palm agroindustry raises concerns regarding deforestation, effects in biodiversity, contamination and related to social issues such as labor conditions, poverty, and social conflicts. In Mexico, the establishment and subsequent growth of the oil palm industry was promoted by past government policies and financial support. In Chiapas the current main producer of the country, the expansion can be also attributed to oil palm resilience to floods, hurricanes, and the economic profitability.
The objective of this study is to evaluate the sustainability status of the oil palm production system within Acapetahua and Villa Comaltitlán Municipalities by analyzing the indicators of sustainability. To achieve this, the Evaluation Framework for Natural Resource Management Systems (MESMIS), was adapted to measure the attributes status of productivity, stability, reliability, resilience, self-management, equity, and adaptability, of the different dimensions of sustainability (environmental, social, political, and economic).
It was identified that MESMIS is an appropriate framework to study oil palm system in Acapetahua and Villa Comaltitlán municipalities. The methodology allowed the identification of critical points, and relevant indicators that include land use and vegetation cover changes, oil palm cashflow, good agricultural practices, farmers´ training, level of participation and farmers´ well-being. As a result, it was identified that vegetation and land use changes were principally from pastures land and previous oil palm plantations, and a positive profitability in the last two years. Soil and water conservation practices are implemented, and farmers have received different trainings principally from social mills, but other good agricultural practices and awareness of social problems should be improved, while the social participation evaluation showed a weak status of the political dimension.
In recent years there have been numerous technical innovations such as CGM systems or insulin pumps that have made life easier for people with type 1 diabetes. However, this also means that more and more information is available. The aim of the present study is to find out more about the daily handling of information. The following research question was asked: What information do people with type 1 diabetes use? To answer this research question, a quantitative online survey of people with type 1 diabetes was conducted by Prof. Dr. Matthias Fank at the Technical University of Cologne. The online survey mainly consisted of 25 closed questions, which were asked on a scale from 0 to 10. The responses of 1,025 people who are at least 18 years old were included in the evaluation. The most important information for type 1 diabetics is the "current value". 67.5% have this on Place 1 placed. Current glucose levels are provided by CGM systems used by 94.2% of people with type 1 diabetes. Quarterly visits to the diabetologist are important and provide important information. 30.8% “completely” agree with this statement on a scale from 0 to 10. Only 2.2% of people with type 1 diabetes are satisfied with their current diabetes management apps. There is a desire for a manufacturer-independent app. The strongest agreement with a value of 10 was chosen by almost a quarter (24.6%) of the people with type 1 diabetes. The study provides an insight into diabetes therapy and shows the need for action.
In Sierra Leone, at the moment 10 out of the total 14 districts are faced with the problem of large-scale land investments for industrial agriculture (oil palm, sugarcane…). The production is mainly for the local, regional and world market. There are quite many of these investments in the planning stage, while some are extending their operations by taking more land from communities or are already at the production stage. Studies and media reports have claimed a number of negative impacts felt in communities hosting these companies, ranging from loss of land, food insecurity, increase in poverty to loss of livelihoods, environmental degradation as well as social and cultural problems. The goal of this thesis is to examine the impacts of the operations of “Socfin Agriculture Company” on food security of local communities in Malen Chiefdom, Pujehun District of Sierra Leone.
Both quantitative and qualitative research methods are used for data collection, analyses, and interpretation of results. The research uses household income and expenditure to compare household food security before and after the start of the company’s operations. It examines consequences of community’s loss of land to support household food production versus casual wage earn from employment created by the company to meet household food security.
The results show a loss of household’s income sources and a significant decrease in households’ income. Households’ food crop production has reduced accompanied by a complete loss of cash crop farming. Households affected by the operations of the company have lost access to land and other natural resources that support food production. Furthermore, the company employs very few people in comparison to the total population of affected communities. Calculation of total wage earn from employment by the company cannot meet the staple food (rice) needs of the households. Also, households claimed a host of unfilled promises made by the company and national government at the onset of the operations of the company.
In conclusion, household food production is the most significant determinant for household food security, with regards to food availability, accessibility, utilization and stability of supply. Therefore, national government should carefully study and develop a framework that addresses food security of households impacted by the operations of the rapidly growing large-scale land investment companies and ensure a fair share of the local community in the economic development of the country and suggesting ways of improving access rights in the context of tenure.
With Google’s Flutter framework continuing to grow in popularity for companies and developers alike, the need for an understanding of how to utilize the framework in a large-scale context has become more relevant than ever. The purpose of this thesis is to document the crucial steps most development teams using Flutter in a large-scale application will face. Additionally, a fully documented, large-scale reference application was generated so that other developers may use it as an aid when creating their own Flutter projects on a similar scale. Multiple steps were taken to ensure that optimal solutions were chosen for each aspect of the development process. For each of those aspects, a wide range of possible solutions were explored, compared and analysed. Finally, one of the possible solutions was chosen based on a wide range of scientific papers and community-generated sources. Additionally, an interview with an expert in the field was conducted to further validate those decisions. After the application was fully implemented, ten crucial aspects of the development process were identified. Those ten aspects are now explained in detail in this thesis. Ultimately, the knowledge provided by this thesis can act as a map for peers using Flutter in a large-scale context and help them overcome the crossroads they will most likely come to face.
REST became the go to approach when it comes to large scale distributed systems on, or outside the World Wide Web. This paper aims to give a brief overview of what REST is and what its main draws and benefits are. Secondly, I will showcase the implementation of REST using HTTP and why this approach became as popular as it is today. Based on my research I concluded that REST’s advantages in scalability, coupling, performance and its seamless integration with HTTP enabled it to rightfully overtake classic RPC based approaches.
Hydrogen is nowadays in focus as an energy carrier that is locally emission free. Especiallyin combination with fuel-cells, hydrogen offers the possibility of a CO2neutral mobility, providedthat the hydrogen is produced with renewable energy. Structural parts of automotive componentsare often made of steel, but unfortunately they may show degradation of the mechanical propertieswhen in contact with hydrogen. Under certain service conditions, hydrogen uptake into the appliedmaterial can occur. To ensure a safe operation of automotive components, it is therefore necessary toinvestigate the time, temperature and pressure dependent hydrogen uptake of certain steels, e.g., todeduct suitable testing concepts that also consider a long term service application. To investigate thematerial dependent hydrogen uptake, a tubular autoclave was set-up. The underlying paper describesthe set-up of this autoclave that can be pressurised up to 20 MPa at room temperature and can beheated up to a temperature of 250◦C, due to an externally applied heating sleeve. The second focusof the paper is the investigation of the pressure dependent hydrogen solubility of the martensiticstainless steel 1.4418. The autoclave offers a very fast insertion and exertion of samples and thereforehas significant advantages compared to commonly larger autoclaves. Results of hydrogen chargingexperiments are presented, that were conducted on the Nickel-martensitic stainless steel 1.4418.Cylindrical samples 3 mm in diameter and 10 mm in length were hydrogen charged within theautoclave and subsequently measured using thermal desorption spectroscopy (TDS). The resultsshow how hydrogen sorption curves can be effectively collected to investigate its dependence ontime, temperature and hydrogen pressure, thus enabling, e.g., the deduction of hydrogen diffusioncoefficients and hydrogen pre-charging concepts for material testing.
Soils are complex, evolving systems that simultaneously shape and are shaped by numerous biotic and abiotic factors in a vast web of interactions that creates the conditions for the propagation of life and the maintenance of human societies. Yet, land use and land use change (LULUC) and anthropogenic climate change (CC) are forcing substantial and rapid alterations into soil’s properties and processes, thus affecting the functions and services derived from it. The resulting land degradation (LD) is now spread, according to recent estimates, over nearly 30 % of the world’s total land, mostly on the population dense and impoverished tropics, a zone predicted to withstand the worst impacts of CC. The Atlantic Forest in Brazil is a particularly vulnerable environment, and the unusual drought of 2014-2017 that hit its Southeastern region is likely the harbinger of a progressively drier future.
The way the prelude of what might be an increasingly frequent hazard affected farmers’ livelihoods and natural resources, and the manner in which they reacted to those impacts can thus reveal points of strength and fragility that could be respectively harnessed or addressed to develop a more sustainable agriculture and climate resilience. This master thesis focused on characterizing those impacts and reactions on distinct dairy production systems in two municipalities in Northwestern Rio de Janeiro: Santo Antônio de Pádua and Cambuci. Through interviews and in loci observations, the researcher collected data concerning environmental services (erosion prevention, soil cover and water provision), production variables (inputs and outputs), socio-economic information, farm system management and farmers’ future perspectives. The results show that dairy production systems in the region are heterogeneous and, although they may share common characteristics, drought outcomes were closely tied to the specificities of each farm. Ultimately, outcomes originated from differences in water supply, water demand, and feed availability, their subsequent change by the drought and farmers’ reaction to those changes at each property.
At the case study of the city of Cologne and the neighbouring Rhein‐Erft‐Kreis (a county), selected resilience aspects of critical infrastructure (CI) and cascading effects are analysed concerning major river floods. Using a Geographic Information System, the applicability of the approach is demonstrated using open source software and data, augmented by manual entries. This study demonstrates the feasibility and limitations of analysing lifeline features of interest for disaster risk and emergency management such as roads, bridges and electricity supply. By highlighting interdependencies of emergency services with CI such as roads, cascading effects of interconnected paths are shown. The findings indicate that in an extreme event flood scenario over 2,000 km of roads and eight bridges will be exposed to floods in the area of the rivers Rhine and Erft. This places huge demands on disaster and emergency management institutions and people affected and limits their resiliency.