Die 10 zuletzt veröffentlichten Dokumente
In diesem Jahresbericht dokumentiert die Kölner Forschungsstelle Rückversicherung ihre
wissenschaftlichen Forschungsprojekte, Publikationen, Vorträge und Veranstaltungen in 2017, um dadurch gegenüber den Freunden und Förderern der Forschungsstelle Rechenschaft über die geleistete Forschungsarbeit abzulegen.
The southeast of Córdoba province used to be originally covered by hundreds of wetlands that got heavily modified or drained in the last few decades. Since wetlands provide various important ecosystem services (ESS) for human well-being, their degradation created several problems in La Picasa basin, among which floods are the most obvious one. The wise use of wetlands is increasingly acknowledged to be part of nature-based solution approaches reducing disaster risk. However, in the study area these approaches remain a relatively new concept to decision makers and the lack of knowledge on their effectiveness and implementation process poses a serious barrier to their adoption.
To overcome this obstacle, this dissertation applies an ESS perspective on the current problems of La Picasa basin and sets it in a context of socio-ecological system (SES) theory. A comprehensive analysis of (1) the role wetlands have played in the historic development of the SES, (2) important stakeholder dynamics that create opportunities or restrictions for the conservation of wetlands and (3) possible management approaches to inverse negative ESS trade-offs and feedback loops, was performed.
Results demonstrate that the current problems of floods have both natural and anthropogenic causes. In this regard, wetlands hold a vital role in the complex historic interactions between the social and ecological drivers of changes in the water balance. Although a social network between stakeholders exists, several conflicts prevent a proper functioning of a basin-wide integrated management concept based on wetland restoration. Nature-based solution approaches, putting wetlands in the center of attention of future management strategies, were found to hold a high potential to reduce the risk of floods and, as a side-effect boost biodiversity and habitat quality in the study area.
In the Mesoamerican forest Selva Maya, multiple driving forces create an imbalance in the sensitive human-nature relation and demand for innovative management strategies for its re-establishment. Within the Guatemalan Maya Biosphere Reserve (MBR), core areas are under strict protective legislation and agricultural activity is permitted only within a bordering buffer zone (BZ), which covers great part of the Guatemalan department Petén. Here, the implementation of agroecological practices by multiple stakeholders aims at tackling the principle driving forces of environmental degradation and thus at reducing the pressure on Central America’s largest tropical forest area. Since 2011, the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) has assisted local stakeholders by carrying out the project “Conservation and sustainable use of the Selva Maya”. This project has offered technical support, cooperated with national institutions, and assisted multiple target groups to nudge agroecological transitions at the household and community level. As the establishment of agroecological systems face main obstacles stemming from the socio-ecological setting of the respective area, the following work presents a context specific analysis for the adaption of established strategies in the MBR BZ. Therefore, it raises the following research questions: What are the current properties of the socio-ecological system that describes the BZ? How has the GIZ’s project nudged and guided agroecological transitions? Which factors have favored or limited the turn to agroecological farming? And finally: Which recommendations derive for the navigation of agroecological transitions? The overall research approach is orientated on the framework of ecosystem stewardship1 and incorporates elements of system theory and resilience science. The framework has been adapted by combining two approaches on different management levels. The social-ecological system approach2 is used to describe the socio-ecological system of the BZ, while the evaluation of the pilot groups‘ AESs follows the Mexican MESMIS3 approach for sustainability assessments. By the integration of both approaches, it is revealed that the socio-economic context impedes or hinders the implementation of agroecological strategies for the majority of farmers. The application of the MESMIS framework has revealed that the installed monitoring mechanism is dysfunctional. Findings further indicate that there is potential for transitions of individual AESs, but they demand investments and support with the current circumstances of reducing farmers’ vulnerability. The rapidly decreasing social and environmental conditions for family farmers in the BZ are most likely not addressed by solutions that the agroecological approach tackles. Recommendations for the immediate improvement of the strategy include adjustments of the project’s proceedings as well as fundamental changes in conservation paradigm and governance to maintain the necessary functionality of the socio-ecological system.
The ‘Energy Crisis’ has become the talk of the town in pretty much every developing and lower developing countries in today’s world. It is characterized by a state where the country’s locally available energy resources are being depleted and it is dependent on imported fuel. The problem is considered as although not parallel, but a descendant of the food crisis in terms of the seriousness of the problems in developing nations essentially in Sub-Saharan Africa (SSA). Ethiopia is one such country which nevertheless going through a rapid scale of development (nearly 11 % annual growth rate as of 2017 according to the World Bank) and also is endowed with an enormous amount of natural resources such as hydro, wind, solar, geothermal energy potential. The Ethiopian power sector is heavily dependent on the country’s hydropower resources. However, it needs to diversify its energy sector and integrate new and other renewable energy sources because, in the longer term, its extreme hydropower dependence may put its power sector vulnerable to natural risks like droughts which are very likely scenarios due to the climate change. Since the lack of access to modern forms of energy services left no choice for the Ethiopians than to continue their traditional biomass use, and it results in unsustainable environmental harm with deforestation, soil erosion, and many others. To address this issue, Ethiopia is taking necessary steps towards climate-friendly industrialization of the economy.
In order to understand this transition, a socio-technical analysis of Ethiopian ambitious transformation from an agrarian society to a climate resilient green society has been presented in this paper. An analytical framework will be formulated as a prerequisite for the study by introducing the theory of Multilevel Perspective (MLP). This theory enables the understanding of three different levels of socio-technical environment namely niches, regime, and landscape in which the respective actors interact with each other to facilitate the process of transition. As a part of laying the groundwork, this thorough analysis constitutes all the country’s energy-related activities and associated energy demands, conversion technologies, current fuel mix, primary energy resources, and energy policies in the Ethiopian energy system. The LEAP analysis results from Mr. Md Alam Mondal and group are summarized to obtain an understanding of the country’s total energy demand scenarios.
Consequently, the actors from each socio-technical level have been identified in the context of Ethiopia and their dynamics of interaction have been explained in order to understand the process of energy system transition of Ethiopia in the direction of diversification of its energy system and hence result in the expansion of new renewable energy sector. Most importantly the assessment suggests that the transition process is majorly driven by top-down forces and intra-level reconfiguration of regime actors. There are no bottom-up forces acting as only a little research and development work takes place in the country to develop new radical changes/technological niches. A developing country like Ethiopia has undoubtedly a bright future ahead with all systems in place and the nature-gifted natural resource potential. The ambitious goals set by the country and the international help from developed allies are definitely working in tandem to ensure their accomplishment. With its guiding vision towards development and the global climate change movement, Ethiopia surely has the potential to lead by example.
La Picasa basin, an interjurisdictional endorreic basin of 5282 km2 located in the “Central Pampa” in Argentina, has suffered repeated flooding caused by an increasing water level of La Picasa lagoon, affecting livelihoods, infrastructure, transportation and agriculture. Although water infrastructure has been built to regulate water excesses, it has not been effective in reducing the flood risk.
To improve the knowledge of the hydrological system, the master’s thesis aimed to develop a water balance model of La Picasa lagoon at a monthly time step between the hydrological years 2007/2008 and 2016/2017. Specifically, the objectives were to identify and quantify the most important components and processes determining its water level, area and volume and to propose hypothetical simulation scenarios based on different pumping operation schemes.
The description of the conceptual model and implementation of a sensitivity analysis allowed to identify the inflow and outflow components of the water balance and quantify their relative contributions, namely precipitation, water discharge from channels, surface runoff from surrounding sub-basins of the lagoon, evaporation and pumping. The performance tests applied to the model during the calibration and validation showed a very good performance. Additionally, two simulation scenarios were proposed, namely potential pumping and adjusted pumping, which reflected different trajectories of the water balance.
The master’s thesis concluded that precipitation and evaporation were the most determinant inflow and outflow components in the water balance of La Picasa lagoon respectively. However, the flooding event in 2016/2017 was caused by a simultaneous reduction of net evaporation and an increase in water discharge, surface runoff and intermittent pumping. The simulation scenarios suggested that an optimal operation of the pumping stations could have been effective to increase the storage capacity of the lagoon. However, during longer humid periods, it might not be enough to outweigh additional inflows.
Die Nutzung von Online-Videos nimmt immer weiter zu und eröffnet neuen Akteuren den Eintritt in diesen, sich entwickelnden Markt. Mediencluster können diesen Trend nutzen, indem sie versuchen, einige dieser neuen Akteure anzuziehen. Gleichwohl ist die Standortentscheidung von Online-Video-Produzenten bisher kaum untersucht. Um mögliche Webvideo-Cluster zu identifizieren, die Struktur der Branche zu untersuchen und Faktoren für die Standortentscheidung aufzudecken, wurden 2.130 Webvideo-Unternehmen, die deutsch- oder englischsprachige Videos auf YouTube, Facebook, Instagram oder Twitch in Deutschland distribuieren, erfasst und befragt. Die meisten Webvideo-Unternehmen haben ihren Sitz in Berlin, Köln, Hamburg oder München. 60 Prozent der Unternehmen agieren als Einzelunternehmer/in (bzw. als Privatperson) und ein Großteil arbeitet kostendeckend bzw. mit einem Gewinnüberschuss. Die räumliche Nähe zur Kreativ- und Medienwirtschaft und die Verfügbarkeit medientechnischer Mitarbeiter am Standort sowie ein urbanes Umfeld und eine gute Infrastruktur sind die wichtigsten Standortfaktoren für die Webvideo-Unternehmen.
Das Ziel der vorliegenden Bachelorarbeit war es, Technologietrends von Enterprise-Resource-Planning (ERP) Systemen zu definieren und anhand eines modernen Produktes vorzustellen. Ein ERP-System unterstützt Unternehmen in der Organisation und Durchführung von sämtlichen Geschäftsprozessen. Zur Untersuchung der wünschenswerten Eigenschaften eines ERP-Systems wurden anhand von Literaturarbeit Anforderungen definiert. Dabei wurde deutlich, dass die Verarbeitung von sämtlichen Geschäftsdaten in Echtzeit einen hohen Stellenwert hat. Hierfür bietet das ERP-System S/4HANA mit verschieden Technologien eine Lösung auf dem Datenbanksystem an. So zeigt ein direkter Performancevergleich zwischen den Datenbanksystemen von S/4HANA und einem aktuellen Konkurrenzprodukt, dass das Verarbeiten von großen Datenmengen in kürzester Zeit möglich ist. Diese Arbeit ist an Fachkreise der Wirtschaftsinformatik und Personengruppen mit Interesse an ERP und Datenbanken Systemen gerichtet.
In dieser Arbeit wurde eine Machbarkeitsstudie zur Speicherung von Wasserstoff in Liquid organic hydrogen carriers (LOHCs) anhand eines gewählten Stoffsystems, Dibenzyltoluen, durchgeführt. Die Arbeit umfasst Bilanzierungen und Auslegungen für eine reversible Hydrierung und Dehydrierung in zwei getrennten Anlagen. Eine class 4-Kostenschätzung bildet die Grundlage für eine Wirtschaftlichkeitsberechnung. So konnten die Technologieziele hinsichtlich der Speicherfähigkeiten nicht realisiert werden. Dennoch zeigen die ermittelten Produktionskosten die Wettbewerbsfähigkeit dieses Ansatzes.
Kontakt: Fabian.Piehl@outlook.com
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.
Risk-based authentication (RBA) is an adaptive security measure to strengthen password-based authentication. RBA monitors additional implicit features during password entry such as device or geolocation information, and requests additional authentication factors if a certain risk level is detected. RBA is recommended by the NIST digital identity guidelines, is used by several large online services, and offers protection against security risks such as password database leaks, credential stuffing, insecure passwords and large-scale guessing attacks. Despite its relevance, the procedures used by RBA-instrumented online services are currently not disclosed. Consequently, there is little scientific research about RBA, slowing down progress and deeper understanding, making it harder for end users to understand the security provided by the services they use and trust, and hindering the widespread adoption of RBA.
In this paper, with a series of studies on eight popular online services, we (i) analyze which features and combinations/classifiers are used and are useful in practical instances, (ii) develop a framework and a methodology to measure RBA in the wild, and (iii) survey and discuss the differences in the user interface for RBA. Following this, our work provides a first deeper understanding of practical RBA deployments and helps fostering further research in this direction.