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Now showing items 231-240 of 246
Preprint
Convergence analysis of time-discretization schemes for rate-independent systems
(2017-12-21)
It is well known that rate-independent systems involving nonconvex energy functionals in general do not allow for time-continuous solutions even if the given data are smooth. In the last years, several solution concepts were proposed that include discontinuities in the notion of solution, among them the class of global energetic solutions and the class of BV-solutions. In general, these solution concepts are not equivalent and numerical schemes are needed that reliably approximate that type of solutions one is ...
Dissertation
Experimental and numerical Investigations of Tracer- and Density- dependent Transport in highly stochastic heterogeneous porous Media and Evaluation of transverse Macrodispersion
(2017-11-27)
Experimentelle und numerische Untersuchungen der dichteabhängigen Strömung und des Transportes gelöster Stoffe in einem sandbepackten Labortank sind wichtig für das Verständnis des Prozesses der Erneuerung von Aquifer. Am Hydrauliklabor der Universität Kassel werden solche Experimente zur Analyse von Makrodispersionseffekte auf eine Frisch-Salzwasser-Grenzfläche innerhalb der heterogen gepackten Sandstruktur mit vorgegebenen stochastischen Eigenschaften in einem Plexiglastank mit den Maßen 9.8×0.1 × 1.225 m durchgeführt. ...
Dissertation
Untersuchung der Verstärkung bestehender Stahlbetonkonstruktionen unter Nutzung Ultrahochfesten Betons (UHPC) im Vergleich zu herkömmlichen Verstärkungsmaßnahmen
(2017-12-07)
Aufgrund des hohen Anteils instandsetzungsbedürftiger Gebäude in Syrien spielen Verstärkungsmaßnahmen eine große Rolle im Bauingenieurwesen. Dabei wird den wirtschaftlichen Aspekten besondere Bedeutung beigemessen. Maßnahmen der Gebäudeverstärkung beruhen in Syrien fast nur auf dem Verfahren der Verstärkung durch Stahlbauteile. Für die Verstärkung und Sanierung bestehender Bauwerke und Bauteile sind in Deutschland verschiedene Methoden, wie z. B. Anbringen zusätzlicher Stahlprofile, Kleben von Stahl-, CFK- oder ...
Dissertation
Effects of mild water restriction on digestion and nitrogen metabolism in a desert adapted goat breed
(2017-04-26)
Water is the main challenge facing animal husbandry in arid and semi-arid regions of the globe. These areas are characterized by a long dry season lasting between 6 and 8 months. At certain times during the long dry period, water can be so scarce that animals may face severe water shortages. Many studies have been conducted to highlight how ruminants cope during these times of severe water deprivation. Yet, livestock are much more often exposed to mild water shortages for several months in a year. Only a few studies ...
Aufsatz
Adoption of an improved bean seed variety and consumption of beans in rural Madagascar: Evidence from a randomised control trial
(Kassel University Press, 2017-10-20)
This paper studies access to, and adoption of improved seed, as well as the diffusion of improved seed information in a remote area of central Madagascar. The analysis is based on panel data gathered from 2012 to 2014 from 390 households in three villages. In 2013, a randomised control trial was applied. Half of the 390 households were randomly assigned to receive improved lima bean seed (Phaseolus lunatus), which were specifically bred for dry regions. Of the seed-receiving households, 50 % were randomly assigned ...
Aufsatz
Veganism as a Virtue: How compassion and fairness show us what is virtuous about veganism
(Department of Organic Food Quality and Food Culture at the University of Kassel, Germany and Federation of German Scientists (VDW), 2017-10-16)
With millions of animals brought into existence and raised for food every year, their negative impact upon the environment and the staggering growth in the number of chronic diseases caused by meat and dairy diets make a global move toward ethical veganism imperative. Typically, utilitarians and deontologists have led this discussion. The purpose of this paper is to propose a virtuous approach to ethical veganism. Virtue ethics can be used to construct a defense of ethical veganism by relying on the virtues of ...
Dissertation
Conservation agriculture in organic farming: Impacts on weeds and plant-parasitic nematodes during the transition
(2017-10-12)
Der Bodenschutz ist eine der wichtigsten Anforderungen an die Landwirtschaft im 21. Jahrhundert. Daher sind nicht-wendende Bodenbearbeitungssysteme, basierend auf dem Anbau von Untersaaten und Zwischenfrüchten, verstärkt in den Fokus der europäischen Agrarwirtschaft geraten. Allerdings können diese neuartigen Systeme das Spektrum und die Abundanz gewisser Krankheiten, Schädlinge und Unkräuter grundlegend verändern. Ein Beispiel ist die Zunahme von Unkräutern und ihren Samenbanken während der Übergangsphase von ...
Dissertation
Amount, composition and turnover of organic matter in topsoils and subsoils under mature beech forest
(2017-12-15)
Two-third of the terrestrial carbon (C) is stored in soils, and up to 63 % of the soil organic C (SOC) is stored in subsoils (i.e. below 30 cm soil depth). Forest soils account for nearly 70 % of the global SOC, demonstrating their great importance regarding the global carbon cycle. The higher average age of the OC stored in subsoil indicates that the subsoil OC is more stable against microbial decomposition. The capability of soil to stabilize OC is affected by substrate characteristics (e.g. size, distribution, ...
Masterarbeit
Free decay testing of a semisubmersible offshore floating platform for wind turbines in model scale
(2017-12-20)
Wind turbines can be installed on floating platforms in order to use wind resources, which blow above the deep sea. The presented research investigates the hydrodynamic behaviour of the Olav Olsen Concrete Star floater in free decay motion. The floater is a new design of a semisubmersible offshore floating platform for wind turbines. The thesis describes the physical free decay testing of a 1/40 plastic scale model in a water basin as well as numerical simulations of the same test cases with the aero-hydro-servo-elastic ...
Dissertation
Zweiachsige Hybriderregung von Synchronmaschinen
(2017-04-25)
Neue Anwendungsfelder von geregelten elektrischen Antrieben, wie beispielsweise die Windenergie und die Elektromobilität, führen zu einer stetig steigenden Nachfrage nach wartungsfreien Systemen mit langen Betriebszeiten. Der Preisverfall der Leistungselektronik bei immer höheren Wirkungsgraden ermöglicht durch geeignete Topologien und entsprechende Regelung deutliche Energieeinsparung beim Betrieb elektrischer Antriebe.
In der Elektromobilität stellen im Besonderen gegensinnige Anforderungen, wie hohe Effizienz bei ...