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Dissertation
Characterisation of Cold Asphalt Mixtures with the Addition of Active Fillers
(2023)
Climate change, the limited availability of natural resources, and energy crises are putting pressure on the global societies? to employ low-energy and low-emission technologies for road pavement construction. Cold Recycled Materials (CRM) is an efficient and low-impact solution. CRM with Bituminous Emulsion (CRM-BE) is one of the most common types of CRM. CRM-BEs are created at ambient temperature by combining a high amount of Reclaimed Asphalt (RA) with Bitumen Emulsion (BE). BE used in CRM is typically composed ...
Dissertation
Modeling analysis of 21st century climate change projections and their impacts on the hydrology of the Karaj-Jajrood basin, Iran
(2023-12)
Two main rivers, Karaj and Jajrood which provide metropolitan Tehrans’ water, flow in Alborz and Tehran province, respectively. In the last decades, the impact of climate change on temperature and precipitation is tangible in these two provinces. For the Karaj-Jajrood basin, during the period 2003-2012, the minimum temperature increased by 1°C, the maximum temperature by 0.6°C and precipitation decreased by -7%, relative to the average of 1972-2012.
To assess climate change impacts in the region, the Statistical ...
Dissertation
Plastic packaging waste management in Germany: Evaluating and optimizing material flows and environmental impacts
(2023)
Since 1990, the annual plastic packaging consumption by private end users in Germany more than doubled. This trend can be attributed to plastic's advantageous properties such as its low weight, cost-effectiveness, and customizable features. However, plastic packaging is also widely criticized due to its dependency on fossil fuels, short lifespan, and potential contribution to marine littering. The tension between the popularity of plastic packaging and the environ-mental challenges associated with a short-term product ...
Dissertation
Ultrahochleistungsbetone mit Bewehrung aus Formgedächtnismetallen zur Optimierung der Frisch- und Festbetoneigenschaften
(2023-11)
Formgedächtnislegierungen haben die Eigenschaft sich durch einen thermischen oder spannungsinduzierten Impuls an eine zuvor eingeprägte Form zu „erinnern“. Dies beruht auf einer reversiblen Phasenumwandlung von der Niedrigtemperaturphase Martensit zu der Hochtemperaturphase Austenit. Durch diese Eigenschaft und die sich dadurch gebenden Möglichkeiten finden diese Legierungen auch immer mehr Beachtung im Bauingenieurwesen. Dies ist vor allem im Bereich der Energiedissipation und der externen Vorspannung und dem ...
Dissertation
Evaluation of Bitumen-Aggregate Adhesion Bond Based on Surface Free Energy and Comparison with Moisture Sensitivity and Asphalt Performance Tests
(2024)
The adhesion bond between aggregate particles and bitumen plays a crucial role in ensuring the durability of asphalt pavement, and it is influenced by factors such as bitumen-aggregate compatibility, moisture exposure, other environmental conditions, and traffic loads. Failure of the adhesion bond results in the detachment of bitumen from the aggregate surface and leads to stripping in the presence of moisture. This, in turn, leads to the development of macro cracks and disintegration within the asphalt pavement, ...
Dissertation
Three-dimensional hydrodynamic and ecosystem modeling of warm-monomictic reservoirs (Maroon and Abolabbas, Iran) under the impact of 21st century climate change
(2021-11)
Lakes and reservoirs, as the endpoint of their upstream catchment, collect their water as the resultant of the hydrological and ecosystem processes and, thus, act as a gauge of their catchment’s management. Physical processes, e.g. stratification and mixing and propagation of density currents, are the main drivers of the biochemical factors in lakes and reservoirs and are prone to be altered and affected by climate change. Hydrodynamic models are the tools to simulate the behavior of the water body under various ...
Dissertation
Fluoreszenzmikroskopische in-situ-Untersuchungen zu Wechselwirkungen von Fließmitteln und Partikeln in zementären Systemen
(2021)
Effektive rheologiemodifizierende Zusatzmittel sind aus der modernen Betontechnologie nicht mehr wegzudenken. Sei es der wirtschaftlichere, weil schnellere Einbau von fließfähigem Normalbeton oder die Herstellung von hoch- und ultrahochfesten Betonen; die so genannten Fließmittel spielen eine zentrale Rolle beim Einsatz und bei der Entwicklung zeitgemäßer, zementgebundener Baustoffe. Zur detaillierten Untersuchung der Wirkungsmechanismen wurde in dieser Arbeit eine Methode entwickelt, die die Beobachtung der ...
Dissertation
Energy Budget- and Temperature Index- based Calculations of Seasonal Mass Balances and Discharge in the Tropical Glacier Artesonraju and Artesoncocha Basin in the Cordillera Blanca,
Peru
(2020)
The core of the present Doctoral study deals with glacier simulations for calculating mass balance and discharge in the Artesonraju glacier and Artesoncocha basin, in the Cordillera Blanca (CB), Peru. For this purpose, two different models are used. One is an energy-model (EBM) which is physically based and uses energy fluxes measurements on the glaciers, whereas the other one is a temperature index model (TIM) which is empirical and uses mainly temperature and precipitation as its main input data.
An analysis of ...
Dissertation
Behaviour Study of Grouted Connection for Offshore Wind Turbine Structures with Brittle Cement Based Grouts
(2020)
Researches show that the energy demand in the world is significantly increasing and climate change becomes a problematic issue, therefore, the interest in renewable energy is growing extremely fast. Offshore wind energy is one of the most effective renewable sources in Europe and other places in the world. One of the most important parts in the offshore foundation is the grouted connection as it is the first element to be designed in the design of the foundation structure of an offshore wind turbine because the ...
Dissertation
Integrierte hydrologische Modellierung von Oberflächen- und Grundwasser in dem mesoskaligen Einzugsgebiet des Rautenbach, Nordhessen
(2021-07)
In den vergangenen Jahren kam es in Europa vermehrt zu sommerlichen Dürreperioden mit erheblichen Beeinträchtigungen der Ökosysteme sowie für Land- und Forstwirtschaft. Die dadurch zunehmenden Herausforderungen an das Wasserressourcenmanagement fordern ein erweitertes Systemverständnis, welches durch realitätsnahe hydrologische Modellierung gewonnen werden kann.
Integrierte hydrologische Modelle ermöglichen die räumlich und zeitlich differenzierte Abbildung ober- und unterirdischer Abflüsse und derer Wechselwirkungen. ...