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The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
provided by the
Networked Digital Library of Theses and Dissertations.
Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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Showing 231 to 233 of 233 (0.026 seconds)| 231 |
Thermal energy management and chemical reaction investigation of micro-proton exchange membrane fuel cell and fuel cell system using finite element modellingMcGee, Seán January 2015 (has links)
Fuel cell systems are becoming more commonplace as a power generation method and are being researched, developed, and explored for commercial use, including portable fuel cells that appear in laptops, phones, and of course, chargers. This thesis examines a model constructed on inspiration from the myFC PowerTrekk, a portable fuel cell charger, using COMSOL Multiphysics, a finite element analysis software. As an educational tool and in the form of zero-dimensional, two-dimensional, and three-dimensional models, an investigation was completed into the geometric construction, air conditions and compositions, and product materials with a best case scenario completed that summarizes the results identified. On the basis of the results of this research, it can be concluded that polyoximetylen and high-density polyethylene were considered as possible materials for the majority of the product, though a more thorough investigation is needed. Air flow of above 10 m/s, air water vapour mass fraction below 50% and initial temperature between 308K and 298K was considered in this best scenario. Suggestions on future expansions to this project are also given in the conclusion.
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Biotopmanagement in Festungsanlagen – Trittsteine und Habitate für die BiotopvernetzungJunghans, Veikko 08 April 2021 (has links)
Durch vegetationsökologische Feldstudien wurde das Biotop- und Arteninventar verschiedener Festungsanlagen des 19. Jahrhunderts in Deutschland, Polen und Litauen untersucht. Ein Ziel der Untersuchung war die Bewertung der Standorte für eine Einbindung in den FFH Biotop-Verbund, ergänzt durch Auswertungen historischer Luftbilder sowie Sentinel2-Fernerkundungsdaten.
Die Festungsanlagen neigten in den letzten Jahrzehnten zu einer Wiederbewaldung durch ausbleibende Nutzung und Pflege der Offenlandbereiche. Innerhalb weniger Jahrzehnte sind vor Ort vor allem stadtwaldähnliche Standorte entstanden. Eine Entwicklung hin zu standorttypischen Ausprägung einer HPNV oder anderer Gesellschaften, die als Biotoptypen nach Anhang I FFH-RL ausweisbar wären, ist an den untersuchten Standorten nicht beobachtet worden. Hohe Biotopqualitäten in Offenland-Standorten sowie anderen Biotoptypen sind nicht beobachtet worden.
Festungen und deren Biotope sind als Novel Ecosystems ausweisbar und wären nur als solche in das Biotopverbundsystem integrierbar. Satellitenbasierte Auswertungen bilden die Kleinräumigkeit der örtlichen Biotopstrukturen –und deren Vielfalt nur bedingt ab. Fehlende Pflege und Nutzung von Festungen sowie aufkommende Waldbestände verursachen eine sukzessive Degradation und Schädigung der Bausubstanz.
Eine naturschutzfachliche Begründung für das grundsätzliche Ausbleiben von Sanierung und Bausubstanzerhalt existiert nicht, auch wenn diese Standorte oftmals Habitate für Arten des Anhang IV der FFH-RL aufweisen. Im Gegensatz, die Pflege und der Erhalt des Kulturerbes „Festungsanlagen“ wird von der europäischen Naturschutz- und vor allem Kulturagenda sogar gefordert, da diese neben noch unspezifiziertem Natur- und Erholungswert auch einen intrinsischen gesamteuropäischen Kulturwert haben. Das muss bei der lokalen Raum- und Naturschutzfachplanung sowie in der regionalen Landespflege berücksichtigt werden. / The biotope and species inventory of various fortifications of the 19th century in Germany, Poland and Lithuania was examined through vegetation-ecological field studies. One aim of the study was to evaluate the locations for integration into the FFH biotope network, supplemented by evaluations of historical aerial photos and Sentinel2 remote sensing data.
Investigated fortifications tended to reforest in recent decades due to the lack of use and maintenance of the open land areas. Within a few decades, urban forest-like sites have developed here at the investigated sites. A development towards site-typical expressions of PNV or other communities, which could be designated as FFH biotopes according to Annex I of the Habitats Directive, has not been observed. High biotope qualities in open land biotopes and other types were not observed
Fortresses and their biotopes can be designated as Novel Ecosystems and should only be integrated as such into the biotope network. Satellite based evaluations only provide a limited picture of the small-scale nature and diversity of local biotope structures. The lack of maintenance and use of fortresses as well as emerging forest stands cause successive degradation and damage to the building fabric.
There is no nature conservation justification for the fundamental lack of remediation and preservation of building fabric, even though these sites often have habitats for species listed in Annex IV of the Habitats Directive. In contrast, the care and preservation of the cultural heritage "fortifications" is even demanded by the European nature conservation and cultural agenda, as they have an intrinsic pan-European cultural value in addition to still unspecified nature and recreational value. This is even reflected by the aim of the Habitats Directive. This must be taken into account in local spatial and nature conservation planning and in regional land management.
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Virtual reality in tourism. Opportunity or pitfall? : Explorative case study of a place-based virtual reality experience of Mariebergsskogen / Virtuell verklighet i turismen. Möjlighet eller fallgrop? : En explorativ fallstudie om en platsbaserade virtuell verklighet upplevelse av MariebergsskogenKubitzek, Barbara January 2021 (has links)
To what extent can virtual reality be used to induce real-life tourism? This question becomes even more relevant in these covid-19 times. However, research on virtual reality concerning tourism has not engaged substantively with this question yet and thus this study seeks to address this question. This thesis is an explorative case study of the development of the prototype of a place-based virtual reality experience of Mariebergsskogen in Karlstad, Sweden. The purpose of this study is to investigate and show how a place-based virtual reality experience can add value to the experience and promotion of Mariebergsskogen. This thesis goes beyond ocularcentrism highlighting the involvement of senses, the whole body and emotions in experiencing a destination. How can a deeper emotional connection to a destination be evoked through virtual reality revealing the characteristics, uniqueness and rootedness of the place? A geomedia approach is taken that combines a sensitivity to place with media to arrive at a multi-dimensional view of Mariebergsskogen considering place representations, engagements and its roots to history. Place is conceptualized by recourse to Lefebvre’s (2011) spatial triad: lived, perceived and imagined that are in a dialectic relationship. The methodological model created has been informed by the project on place-based digital experiences (PDU) at the University of Karlstad in Sweden. Tourists are considered active agents in creating tourism destinations and this study emphasizes their engagement as co-creators in the prototype development process. A methodological model is proposed that combines a place analysis with workshops consisting of a user study and a co-creation workshop supplemented with insights from interviews with virtual reality developers and stakeholders from Region Värmland and Karlstad Municipality.
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