Refine
Year of publication
- 2020 (46) (remove)
Document Type
- Article (27)
- Master's Thesis (9)
- Bachelor Thesis (4)
- Report (3)
- Conference Proceeding (2)
- Working Paper (1)
Language
- English (46) (remove)
Has Fulltext
- yes (46)
Keywords
- Rückversicherung (4)
- Forschungsbericht (3)
- Kölner Forschungsstelle Rückversicherung (3)
- Reinsurance (3)
- Disaster risk management (2)
- Insurance (2)
- Künstliche Intelligenz (2)
- Resilienz (2)
- Risikomanagement (2)
- 60J10 (1)
Faculty
- Fakultät 12 / Institut für Technologie und Ressourcenmanagement in den Tropen und Subtropen (11)
- Angewandte Naturwissenschaften (F11) (5)
- Fakultät 04 / Institut für Versicherungswesen (5)
- Fakultät 09 / Institut für Rettungsingenieurwesen und Gefahrenabwehr (5)
- Fakultät 03 / Institut für Informationswissenschaft (3)
- Fakultät 10 / Advanced Media Institute (3)
- Fakultät 04 / Schmalenbach Institut für Wirtschaftswissenschaften (2)
- Fakultät 07 / Institut für Elektrische Energietechnik (2)
- Fakultät 07 / Institut für Nachrichtentechnik (2)
- Fakultät 10 / Cologne Institute for Digital Ecosystems (2)
One-step preparation of bilayered films from kraft lignin and cellulose acetate to mimic tree bark
(2020)
This contribution presents the development of a dry-cast method for the one-step preparation of bio-based films from wood polymers that mimic the bilayered structure of tree bark, the natural protective layer of the tree. In a simplified view, natural bark can be considered as the superposition of an external homogeneous and non-porous layer (outer bark) and a porous substructure layer (inner bark). This work is a first step for the future development of bio-based biomimetic wood coatings. The film had a bark-like appearance and its total density, bulk density and porosity were similar to values measured in natural bark. Furthermore, the structural characteristics of the studied film, namely specific surface area (BET) and pore size distribution, as well as the performance of the water adsorption ability were investigated and discussed.
This paper introduces CAAI, a novel cognitive architecture for artificial intelligence in cyber-physical production systems. The goal of the architecture is to reduce the implementation effort for the usage of artificial intelligence algorithms. The core of the CAAI is a cognitive module that processes the user’s declarative goals, selects suitable models and algorithms, and creates a configuration for the execution of a processing pipeline on a big data platform. Constant observation and evaluation against performance criteria assess the performance of pipelines for many and different use cases. Based on these evaluations, the pipelines are automatically adapted if necessary. The modular design with well-defined interfaces enables the reusability and extensibility of pipeline components. A big data platform implements this modular design supported by technologies such as Docker, Kubernetes, and Kafka for virtualization and orchestration of the individual components and their communication. The implementation of the architecture is evaluated using a real-world use case. The prototypic implementation is accessible on GitHub and contains a demonstration.
The paper presents results of the modelling of heat transfer at film boiling of a liquid in a porous medium on a vertical heated wall bordering with the porous medium. Such processes are observed at cooling of high-temperature surfaces of heat pipes, microstructural radiators etc. Heating conditions at the wall were the constant wall temperature or heat flux. The outer boundary of the vapor film was in contact with moving or stationary liquid inside the porous medium. An analytical solution was obtained for the problem of fluid flow and heat transfer using the porous medium model in the Darcy–Brinkman and Darcy–Brinkman–Forchheimer approximation. It was shown that heat transfer at film boiling in a porous medium was less intensive than in the absence of a porous medium (free fluid flow) and further decreased with the decreasing permeability of the porous medium. Significant differences were observed in frames of both models: 20% for small Darcy numbers at Da < 2 for the Darcy–Brinkman model, and 80% for the Darcy–Brinkman–Forchheimer model. In the Darcy–Brinkman model, depending on the interaction conditions at the vapor–liquid interface (no mechanical interaction or stationary fluid), a sharp decrease in heat transfer was observed for the Darcy numbers lower than five. The analytical predictions of heat transfer coefficients qualitatively agreed with the data of Cheng and Verma (Int J Heat Mass Transf 24:1151–1160, 1981) though demonstrated lower values of heat transfer coefficients for the conditions of the constant wall temperature and constant wall heat flux.
Stable recombinant mammalian cells are of growing importance in pharmaceutical biotechnology production scenarios for biologics such as monoclonal antibodies, growth and blood factors, cytokines and subunit vaccines. However, the establishment of recombinant producer cells using classical stable transfection of plasmid DNA is hampered by low stable gene transfer efficiencies. Consequently, subsequent selection of transgenic cells and the screening of clonal cell populations are time- and thus cost-intensive. To overcome these limitations, expression cassettes were embedded into transposon-derived donor vectors. Upon the co-transfection with transposase-encoding constructs, elevated vector copy numbers stably integrated into the genomes of the host cells are readily achieved facilitating under stringent selection pressure the establishment of cell pools characterized by sustained and high-yield recombinant protein production. Here, we discuss some aspects of transposon vector technologies, which render these vectors promising candidates for their further utilization in the production of biologics.
Academic search systems aid users in finding information covering specific topics of scientific interest and have evolved from early catalog-based library systems to modern web-scale systems. However, evaluating the performance of the underlying retrieval approaches remains a challenge. An increasing amount of requirements for producing accurate retrieval results have to be considered, e.g., close integration of the system’s users. Due to these requirements, small to mid-size academic search systems cannot evaluate their retrieval system in-house. Evaluation infrastructures for shared tasks alleviate this situation. They allow researchers to experiment with retrieval approaches in specific search and recommendation scenarios without building their own infrastructure. In this paper, we elaborate on the benefits and shortcomings of four state-of-the-art evaluation infrastructures on search and recommendation tasks concerning the following requirements: support for online and offline evaluations, domain specificity of shared tasks, and reproducibility of experiments and results. In addition, we introduce an evaluation infrastructure concept design aiming at reducing the shortcomings in shared tasks for search and recommender systems.
The 13th Annual Meeting of the Sponsoring Group Reinsurance was held 26 June 2020. Due to COVID-19, the event was held online this year. Some 80 representatives of the (re)insurance companies involved in the Sponsoring Group took part in the meeting, along with guests. Offered for the sixth time as part of the Annual Meeting, the Researchers’ Corner gave the seven academic researchers at the Cologne Research Centre for Reinsurance an opportunity to deliver a presentation on the research project each in which each is involved in 2020.
In three sessions – each featuring 2-3 parallel lectures with posters – the most important results of the scientific studies by the Cologne Research Centre for
Reinsurance were presented and discussed. The heterogeneity of the topics
presented by academic staff reflects the dovetailing of Cologne Research Centre with reinsurance practice.
Session 1
a) Manuel Dietmann (M.Sc.): Preventive recovery planning for insurance companies
b) Robert Joniec (M.Sc., FCII, cand. PhD): Capital is fungible, the market is
growing more efficient – But how valid are research results?
c) Jörg Dirks (M.Sc., FCII): Cyber risks in reinsurance – Insurable on a parametric basis through AI?
Session 2
a) Wolfgang Koch (M.Sc., FCII): Trend in sovereign cat pools in emerging and developing economies
b) Fabian Lassen (M.Sc., FCII): Environmental social governance – A look at reinsurers
Session 3
a) Fabian Pütz (M.Sc., PhD): Reinsurance aspects of product recalls in the automobile sector
b) Lihong Wang (M.Sc., FCII): China’s Belt and Road Initiative (BRI) – Its impact
on the global (re)insurance industry
Poster session
a) Fabian Lassen (M.Sc., FCII): Private-public partnership – The solution for the insurability of pandemics?
b) Christian Serries (B.Sc.): Silent Cyber as a challenge for the (re-)
insurance industry
c) Frank Cremer (B.Sc. / FCII): Digital ecosystems – Relevance for reinsurance?
d) Harald Kurtze (B.Sc.): Sharing economy – Impacts for reinsurance?
With the publication series, ‘Proceedings of the Researchers’ Corner’, the Cologne Research Centre for Reinsurance meets the desire for publication of the research results of our scholars together with the accompanying posters and discussions. The titles are reproduced in keeping with the above agenda of the Researchers’ Corner
for the 13th Annual Meeting of the Förderkreis Rückversicherung [Sponsoring Group Reinsurance].
This bachelor thesis addresses the issue of how school resilience can be measured and assessed quantitatively. Schools as social infrastructures have a significant value for society. Yet, on a global scale, they, and therefore the respective community as well, are continuously endangered by a variety of threats such as natural disasters or violence and mental abuse affecting students, parents and school staff. However, these threats differ greatly depending on climatic and geographical conditions as well as on the socio-cultural context of the corresponding community. To strengthen school resilience against potential threats and to ensure education continuity despite the occurrence of these disruptions, a methodology is developed to measure and assess school resilience in conjunction with its specific circumstances. Initially, qualitative and quantitative (composite) indicators are identified and categorised with the help of a Systematic Literature Review and Mayring's Qualitative Content Analysis. These are subsequently developed into a Comprehensive Index for School Resilience (CISR). Building on this, a pre-existing assessment methodology, which uses Likert-Scales arranged in questionnaires to assign quantitative values to the composite indicators, is adapted to operationalise the CISR and by an exemplary application at Europaschule Troisdorf, the methodology is adapted to the socio-cultural conditions in Germany using an expert’s operational and contextual knowledge. The results obtained show that the methodologies and techniques described in current international research can, after an appropriate adaptation, successfully be applied to schools in Germany as well. Nevertheless, by identifying research limitations and errors as well as potential improvements, it is evident that further research and development is needed to provide stakeholders with a decision-making tool to strengthen the resilience of schools in the future, such as an exhaustive supplement to the CISR or the integration of more precise quantification methodologies and techniques.
Emergency management services, such as firefighting, rescue teams and ambulances,are all heavily reliant on road networks. However, even for highly industrialised countries such asGermany, and even for large cities, spatial planning tools are lacking for road network interruptionsof emergency services. Moreover, dependencies of emergency management expand not only onroads but on many other systemic interrelations, such as blockages of bridges. The first challenge thispaper addresses is the development of a novel assessment that captures systemic interrelations ofcritical services and their dependencies explicitly designed to the needs of the emergency services.This aligns with a second challenge: capturing system nodes and areas around road networksand their geographical interrelation. System nodes, road links and city areas are integrated into aspatial grid of tessellated hexagons (also referred to as tiles) with geographical information systems.The hexagonal grid is designed to provide a simple map visualisation for emergency planners andfire brigades. Travel time planning is then optimised for accessing city areas in need by weighingimpaired areas of past events based on operational incidents. The model is developed and testedwith official incident data for the city of Cologne, Germany, and will help emergency managers tobetter device planning of resources based on this novel identification method of critical areas.
In this paper we describe traffic sign recognition with neural networks in the frequency domain. Traffic signs exist in all countries to regulate the traffic of vehicles and pedestrians. Each country has its own set of traffic signs that are more or less similar. They consist of a set of abstract forms, symbols, numbers and letters, which are combined into different signs. Automatic traffic sign recognition is important for driver assistance systems and for autonomous driving. Traffic sign recognition is a subtype of image recognition. The traffic signs are usually recorded by a camera and must be recognized in real time, i.e. assigned to a class. We use neural networks for traffic sign recognition. The special feature of our method is that the traffic sign recognition does not take place in the spatial domain but in the frequency domain. This has advantages because it is possible to significantly reduce the number of neurons and thus the computing effort of the neural network compared to a conventional neural network.
This investigation attempts to understand the eco‐hydrology of, and accordingly suggest an option to manage floodwater for agriculture in, the understudied and data‐sparse ephemeral Baraka River Basin within the hyper‐arid region of Sudan. Reference is made to the major feature of the basin, that is, the Toker Delta spate irrigation scheme. A point‐to‐pixel comparison of gridded and ground‐based data sets is performed to enhance the estimates of rainfall. Analysis of remotely sensed land use/cover data is performed. The results show a significant reduction of the grassland and barren areas explained by a significant expansion of the cropland and open shrubland (invasive mesquite trees) areas in the delta. The cotton sown area is highly dependent on the flooded area and the discharge volume in the delta. However, the area of this major crop has declined since the early 1990s in favour of cultivation of more profitable food crops. Expansion of mesquite in the delta is problematic, taking hold under increased floodwater, and can only be manged by clearance to provide crop cultivation area. There is a great potential for floodwater harvesting during the rainfall season (June to September). A total seasonal runoff volume of around 4.6 and 10.8 billion cubic metres is estimated at 90 and 50% probabilities of exceedance (reliabilities), respectively. Rather than leaving the runoff generated from rainfall events to pass to the Red Sea or be consumed by mesquite trees, a location for runoff harvesting structure in a highly suitable area is proposed. Such a structure will support any policy shifts towards planning and managing the basin water resources for use in irrigating the agricultural scheme.
We examine the impact of the existence on an explicit deposit insurance (DI) scheme and its design features on bilateral cross‐border deposits (CBD) in a gravity model setting. We find that both the absolute quality of a country's DI and its relative quality vis‐à‐vis other countries' DI generally affect depositor behavior. However, during systemic banking crises, cross‐border depositors primarily seek countries with the best DI schemes. Similarly, during the 2008–2009 great financial crisis, the emergency actions taken by the governments, which supply and maintain these safe havens, have led to substantial relocations of CBD. (JEL F34, G18)
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.
To realize a reliable and cost-effective application of high-temperature superconductive (HTS) equipment at high-voltage (HV) levels, the influence of thermally induced gas bubbles on the dielectric strength of different solid insulating materials in liquid nitrogen (LN2) was investigated. A heatable copper tape electrode arrangement was developed simulating HTS tapes with insulation in between. AC breakdown measurements were performed without and with forced boiling on insulating papers, polypropylene laminated paper (PPLP) and polyimide (PI) films. Under nucleate boiling the influence of bubbles on the dielectric strength of all materials was not significant. However under film boiling the dielectric strength of the insulating papers decreased to a level comparable to their dielectric strength in air, demonstrating the insufficient impregnation of porous materials under film boiling. For PI there was no degradation at all. PPLP retained about 70% of its basic dielectric strength in LN2.
Pelleted biomass has a low, uniform moisture content and can be handled and stored cheaply and safely. Pellets can be made of industrial waste, food waste, agricultural residues, energy crops, and virgin lumber. Despite their many desirable attributes, they cannot compete with fossil fuel sources because the process of densifying the biomass and the price of the raw materials make pellet production costly.
Leaves collected from street sweeping are generally discarded in landfills, but they can potentially be valorized as a biofuel if they are pelleted. However, the lignin content in leaves is not high enough to ensure the physical stability of the pellets, so they break easily during storage and transportation. In this study, the use of eucalyptus kraft lignin as an additive in tree-leaf pellet production was studied. Results showed that when 2% lignin is added the abrasion resistance can be increased to an acceptable value. Pellets with added lignin fulfilled all requirements of European standards for certification except for ash content. However, as the raw material has no cost, this method can add value or contribute to financing continued sweeping and is an example of a circular economy scenario.
The increasing public awareness of business related impacts on environmental and social well-being, be it positive or negative, are nowadays key drivers of corporate success. Internal and external business environments exert pressure and force transparency as well as responsible action in terms of resolving environmental and social impacts. In line with this, Porter and Kramer regard business behaviour that addresses societal needs and challenges, as the “new way to achieve economic success”.
However, whereas some companies “remain trapped in an out-dated approach to value creation” and restrict their CSR commitment to the compliance with governmental regulation, others proactively address stakeholder needs. By addressing these needs, companies can benefit from grasping the opportunity of enhanced cost efficiency and lowered risk or gaining competitive advantages through establishing unique value propositions, in a way that meets stakeholder demands. Apart from that, CSR performance can be seen as powerful tool to successfully influence stakeholder perceptions in terms of reputation, and thus an exceptional source of value creation. In addition to this, organisations can profit from win-win-win situations related to syncretic value creation by means of partnering with stakeholders. This, however, implies expanding the focus of cost- and risk-reduction towards increasing competitiveness through creating mutual benefits for environment, society and the economy alike.
Although a growing number of companies have recognised the advantages coming along with Corporate Social Responsibility engagement, the accompanying efforts have not been sufficiently mature yet. Due to the fact that many organizations apply a rather narrow and out-dated approach to value creation, they fail to achieve a balance between environmental, social and economic objectives. This, in turn, implies a restriction in their ability to exploit the full value creation potential that is related to CSR engagement. But even organisations applying a broader perspective of value creation, struggle to internalise the opportunities. This is mainly due the challenge of balancing and integrating economic and non-economic criteria. At the same time, organizations are facing the challenge of getting support from senior management and staff. Thus, in order to profit from adopting a ‘broad perspective’, firms must build a deep understanding of the benefits resulting from mutual value creation. However, the main challenge remains the systematic and strategy related integration of Corporate Social Responsibility strategies into core business processes. In respect to this, organizations have to take into account that “social and environment performance are almost certainly unique to each organization”. Thus, value creation in terms of CSR has to be understood as a highly complex set of cause-an-effect relationships among mediating variables and situational contingencies, which is too specific to rely on poorly structured and generic approaches.
In brief, organisations seem to struggle establishing an understanding that does not consider environmental, social and economic benefits as mutually exclusive. Notwithstanding, that such an understanding is established the complexity of factors influencing Corporate Social Responsibility impedes to balance between economic and non-economic criteria. Furthermore, organisations have difficulties to strategically integrate, manage and measure environmental and social performance drivers as well as outcome measures.
Usage of smart home solutions implies generation, processing, and storage of machine and personal data. Recently made public cases of data breaches and misuse increased peoples’ concerns of data security and decreased the trust in secure data handling and smart home technologies. Hence potential benefits are not exploited. It is therefore necessary to analyse how manufacturers can increase their online trust perception.
Requirements of (potential) customers of web based services for HVAC systems are identified using thematic analysis for 23 conducted interviews using online trust perception literature as basis. Manufacturer independent websites are derived as the most important online touch point for customers with manufacturers and products. Determined content and structure measures for online touch points managed by manufacturers derived to positively influence the manufacturer and manufacturer independent touch points regarding perception of trust. The derived trust concept must be evaluated in the following using the defined evaluation plan.
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.
Enhancing DPCD in Liquid Products by Mechanical Inactivation Effects: Assessment of Feasibility
(2020)
The enhancement of standard dense phase carbon dioxide (DPCD) pasteurization by additional mechanical effects was assessed in this work. These effects were induced during pasteurization by the sudden depressurization in a narrow minitube. The high flow velocities, moderate pressures (40–80 bar) and low temperatures (25–45 °C) lead to intense degasification and shear stress. The inactivation of the test microorganism Escherichia coli DH5α (E. coli DH5α) was determined before and after depressurization in the minitube, representing entirely chemical DPCD via dissolved CO2 and total inactivation comprising the effects of dissolved CO2 and mechanical effects, respectively. Compared to conventional DPCD pasteurization, which is mostly attributed to chemical effects, the additional mechanical effects increased the inactivation efficiency considerably.
The use of nematic liquid crystal (LC) mixtures for microwave frequency applicationspresents a fundamental drawback: many of these mixtures have not been properly characterizedat these frequencies, and researchers do not have an a priori clear idea of which behavior they canexpect. This work is focused on developing a new procedure for the extraction of the main parametersof a nematic liquid crystal: dielectric permittivity and loss tangent at 11 GHz under differentpolarization voltages; splay elastic constantK11, which allows calculation of the threshold voltage(Vth); and rotational viscosityγ11, which allows calculating the response time of any arbitrary device.These properties will be calculated by using a resonator-based method, which is implementedwith a new topology of substrate integrated transmission line. The LC molecules should be rotated(polarized) by applying an electric field in order to extract the characteristic parameters; thus,the transmission line needs to have two conductors and low electric losses in order to preserve theintegrity of the measurements. This method was applied to a well-known liquid crystal mixture(GT3-23002 from MERCK) obtaining the permittivity and loss tangent versus bias voltage curves,the splay elastic constant, and the rotational viscosity of the mixture. The results validate the viabilityof the proposed method.