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  • About
  • 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.
341

Preliminary design of a modular high altitude balloon power distribution system

Nordqvist, Emil January 2020 (has links)
This thesis conducts research into different rechargeable battery technologies and their applicability to the high altitude balloon flights conducted at Esrange space center. The research focuses on the possible use of lithium ion batteries’, sodium ion batteries, nickel metal hydrate, and Metal hydridelithiumion batteries. Resulting in lithium ion batteries in 18650 cells being recommended. The thesis continues with a modular power distribution system architecture design. The system architecture is established with solarcharging capabilities, up to 1500W peak output power, over 600W continuous output power, multiple output voltages, more than six output channels, remote output power switching, and monitoring of power consumption. A prototype is built from this architecture on which limited testing is performed.The testing shines light on future improvements and displays proof of concept for some parts.
342

L'hétérogénéité spatiale de la topographie et son influence sur le bilan de masse appliqué sur le glacier Saskatchewan

Meunier Cardinal, Gabriel January 2020 (has links) (PDF)
No description available.
343

Mrakodrap " EVO" (Experimentální výškový objekt) / Skyscraper "EVO"

Juřík, Michal January 2013 (has links)
The study offers a solution of a high-altitude object in Brno in the city part called Veveří. There are proposed two towers which are designed in a simple cubic form ( their heights are 154 a 80 metres ) rising from the surrounding buildings. Towers are mutually interconnected by lower object in the same morphology. In the object are situated administrative spaces, hotel, restaurant, coffee bar, penthouse, congress hall, vertical gallery, painters´ incubator and parking house. Particular functions can be connected because of layout plan, or can be used as separate units. The interpretation of the facade of the object is to highlight verticality, due to the raster and increasing reflecting surface of glass segments verticality and evoke by this a feeling of a tower ending in the middle of clouds.
344

Biodiversity of terrestrial small mammals along an altitudinal transect in the Western Soutpansberg, Limpopo Province, South Africa

Munyai, Aubrey 26 February 2015 (has links)
Department of Ecology and Water Resources / MENVM
345

Využití distančních měření při analýze stavu a vývoje srážek / The exploitation of remote sensing for the analysis and progress of rainfalls

Bližňák, Vojtěch January 2011 (has links)
The thesis is divided in two parts. The first part deals with the areal distribution of short-term convective rainfalls with regard to the influence of altitude. Precipitation estimates based on combination of rain gauge and radar data are used for this purpose. Statistical tests proved that the areal distribution of hourly convective rainfalls does not depend on altitude. Besides data containing precipitation events only, all measured data were statistically analysed regardless of the fact whether precipitation occurred or not. In this case it was found out that the relationship between hourly rainfall totals and altitude depends on the considered threshold of rainfall totals. When all data were considered, i.e. a threshold value was set to zero, an increase of rainfall totals well correlated with altitude. The dependence slowly disappeared with an increasing threshold. The areal distribution of 6 hour rainfall totals proved higher values in the area of south Bohemia. The most frequent synoptic patterns were northwest cyclonic situations (NWC) and cyclone over the Central Europe (C). The second part of the thesis is focused on satellite data exploitation, as measured by meteorological satellite Meteosat Second Generation, for convective precipitation estimates. The Convective Rainfall Rate (CRR) algorithm,...
346

Lipidové složení biologických membrán a životní strategie pěvců / Lipid composition of biological membranes and life-histories in songbirds

Šimonová, Kateřina January 2020 (has links)
Differences in the composition of cell membranes are considered to be the physiological mechanism responsible for different metabolic rates, life span and consequently, different life-histories. The membrane pacemaker theory suggests that higher membrane unsaturation may be an important factor responsible for higher metabolic rate and shorter life span of organisms. The alternative hypothesis, on the other hand, assumes that membranes can function as structural antioxidants, and thus that higher membrane unsaturation may be associated with longer life span. The aim of this work was to test how changes in the fatty acid composition of membranes depends on body size, latitude and altitude, within which different life-histories and metabolic rate were observed. Temperate and tropical lowland songbird species were chosen for the models testing the effect of latitude, and only tropical species of songbirds were chosen for the models testing the effect of altitude. Part of the work was molecular sex determination. Using gas chromatography and mass spectrometry, the amount of individual fatty acids contained in red blood cell phospholipids was obtained from blood samples. The results showed that the composition of the membranes in most cases correlates with body size, which also correlates with almost all...
347

Utilisation de l’habitat par le chevreuil (Capreolus capreolus) dans des environnements variables et contrastés / Roe deer (Capreolus capreolus) habitat use in various different environmental conditions

Gaudry, William 18 December 2015 (has links)
Au sein de son aire de répartition, le chevreuil (Capreolus capreolus) rencontre des conditions environnementales variables et contrastées qui engendrent une grande variété de patrons d'utilisation de l'espace. Jusqu'à présent, aucune étude n'a clairement établi un lien entre les différents patrons d'utilisation de l'espace et les conditions environnementales dans lesquelles le chevreuil évolue, ce qui limite notre compréhension des mécanismes impliqués dans le processus de sélection d'habitat. Grâce aux suivis télémétriques de nombreux chevreuils dans 4 sites avec des conditions environnementales fortement variables et contrastées nous avons cherché à établir un lien entre les variations des conditions environnementales et les variations des patrons d'utilisation de l'espace. Ainsi, nous avons démontré qu'en milieu alpin, les chevreuils adaptent l'amplitude de leurs déplacements en fonction des variations spatiales et temporelles de la disponibilité des ressources ainsi qu'en fonction des conditions d'enneigement. Contrairement aux précédentes études sur l'utilisation de l'espace par le chevreuil en milieu de montagne, nous avons montré que les mouvements des chevreuils au sein de notre aire d'étude correspondaient à un processus de sélection d'habitat de troisième ordre (48 cas; 89%) plutôt qu'à de la migration partielle, puisque très peu d'individus (6 cas; 11%) avaient stabilisé leurs déplacements au sein de domaines vitaux distincts au cours des saisons. Par ailleurs, nous avons démontré que le comportement de sélection d'habitat des chevreuils à l'échelle du domaine vital était très variable entre les populations mais également au sein de chaque population. Ainsi dans les forêts les plus pauvres où les ressources sont spatialement séparées au sein de différents habitats, nous avons démontré que les chevreuils étaient contraints de réaliser des compromis, générant des réponses fonctionnelles en sélection d'habitat. Au contraire, dans les habitats les plus riches où les ressources sont disponibles dans toutes les catégories d'habitat, nous n'avons pas observé de réponse fonctionnelle puisque les chevreuils n'étaient pas contraints et donc ne réalisaient pas de compromis. De plus, nous avons démontré que les chevreuils avec une même composition de domaine vital dans différents sites, utilisaient les ressources différemment. Ces résultats démontrent que la façon dont une ressource est utilisée ne dépend pas seulement de son niveau de disponibilité au sein du domaine vital mais varie également en fonction des conditions environnementales. De ce fait, il est impératif de tenir compte des conditions environnementales au sein d'un site pour mieux comprendre les mécanismes impliqués dans l'émergence des différents patrons d'utilisation de l'espace observés chez les ongulés. Enfin, nous avons tenté d'établir un lien entre les variations observées dans les patrons de sélection d'habitat à différentes échelles et la valeur sélective des chevreuils dans les populations de Chizé et de Trois-Fontaines pour lesquelles les données requises étaient disponibles, mais nous n'avons pu mettre en évidence aucun effet du comportement de sélection d'habitat sur la valeur sélective individuelle des femelles / Across its distributional range, the European roe deer (Capreolus capreolus) encounters a wide range of environmental conditions that generate marked differences of space use patterns. However, linking variation in space use by animals in different populations facing contrasted environmental conditions to site-specific conditions has not yet been investigated, which currently limits our understanding of the mechanisms involved in habitat selection. Using data collected on roe deer equiped with VHF and GPS collars in four different sites with contrasted environmental conditions, we aimed to fill this knowledge gap by relating variations in space use by animals in variable environmental conditions. We found that roe deer in Alpine environment adapt the magnitude of their movements to the spatial and temporal variation in resource availability, but also to the amount of snow cover. Contrary to previous studies on roe deer performed in mountain ranges, we showed that roe deer movements in the northern French Alps corresponds to the usage of various habitat components within the home range (third order habitat selection process; 48 cases; 89%) rather than as partial migration because very few (6 cases; 11%) roe deer stabilized their activity in distinct home ranges across seasons. Moreover, we found that roe deer markedly differed in habitat selection within their home range, both within and among populations. Roe deer facing poor environmental conditions with spatially segregated resources should trade one resource for another one, which generates a functional response in habitat selection. At the opposite, roe deer benefiting from rich environmental conditions in their home range do not have to trade one resource for another one and therefore did not display any functional response. In addition, our results suggest that a same habitat composition can lead to widely different space use patterns. These findings demonstrate that the way a given habitat type is used in relation to its availability strongly varies in response to environmental conditions, so that accounting for variation in environmental conditions is required to provide a reliable assessment of the mechanisms involved to shape the diversity of space use patterns we currently observed in ungulates. Finally, we looked for linking observed variation in space use patterns to indivudual fitness of female roe deer in the populations of Chizé and Trois-Fontaines for which the required data were available. However, we did not find any evidence of a positive effect of the intensity of habitat selection on individual female fitness
348

Neural Network Classification Approach to Clutter Removal for UTM-Enabling Low-Altitude Radar Surveillance

Emshoff, Brandon Lane January 2021 (has links)
No description available.
349

HALO-Based Research Conducted by the LIM: previous Campaigns and Plans for the Future

Schmidt, Jörg, Wendisch, Manfred, Wolf, Kevin, Ehrlich, André, Nitzsche, Gunda 13 November 2017 (has links)
This article gives an overview about the activities of the Leipzig Institute of Meteorology (LIM) within the HALO (High Altitude and Long Range Aircraft) Scientific Priority Program (SPP 1294 funded by DFG). HALO offers unique possibilities for atmospheric research and Earth observations. It can carry a scientific payload of up to 3 t, cover a range of 10000 km and reach a ceiling of 15 km. The LIM contributes to the instrumentation of HALO with the Spectral Modular Airborne Radiation measurement sysTem (SMART). SMART was deployed during the first HALO mission TECHNO in 2010. During subsequent five HALO campaigns SMART measurements provided valuable insights regarding cloud properties and the Earth’s radiative budget. Three further missions, which are scheduled for the coming years, will make use of SMART measurements as well. / Dieser Bericht gibt einen Überblick über die Aktivitäten des Leipziger Instituts für Meteorologie (LIM) im HALO Schwerpunktprogramm (SPP 1294 der DFG). HALO bietet einzigartige Möglichkeiten für die Atmosphärenforschung und Erdbeobachtung. Es kann eine wissenschaftliche Nutzlast von 3 t aufnehmen, eine Reichweite von 10000 km zurücklegen und eine maximale Flughöhe von 15 km erreichen. Das LIM trägt zur Instrumentierung von HALO mit dem Spectral Modular Airborne Radiation measurement sysTem (SMART) bei. SMART wurde 2010 bei der ersten HALO Mission TECHNO eingesetzt. In fünf folgenden HALO Kampagnen verschafften SMART Messungen wertvolle Erkenntnisse bezüglich Wolkeneigenschaften und dem Strahlungsbudget der Erde. Drei weitere HALO Missionen, die für die kommenden Jahre geplant sind, werden ebenfalls SMART nutzen.
350

Automated Contingency Management for Passenger-Carrying Urban Air Mobility Operations

Sai V Mudumba (12295691) 19 April 2022 (has links)
<p>As Urban Air Mobility (UAM) is developed and brought into fruition via electric vertical takeoff and landing (eVTOL) vehicles, contingencies associated with this new distributed electric propulsion technology in metropolitan areas must be considered. On the state of knowledge on contingencies for eVTOL vehicles, these can be Epistemological Risks or Ontological Risks. Epistemological Risks include known-knowns (probabilistic risks) and known-unknowns (gaps in knowledge). Ontological Risks include, unknown-knowns (hidden knowledge), unknown-unknowns (fog of ignorance). As UAM operations at large scale do not have as much historical accidents data as General Aviation or Commercial Aviation, it is challenging to estimate its accident failure rate per 100,000 flight hours. While battery thermal runaway, battery energy uncertainty, software issues, and common mode power failures are some failure cases listed in this thesis, it is the undiscovered contingency (i.e., unknown-unknown) or unprepared contingency (i.e., unknown-known), along with other external factors, that can lead to an accident. UAM is expected to operate at 1500 feet AGL and at high frequencies over dense metropolitan areas. In an in-flight emergency at these altitudes, any startle response experienced by on-board or remote pilots can lead to longer response times. This study aims to create a framework for contingency planning and risk mitigation using a Reachable Ground Footprint model for eVTOL aircraft under 100% power failure scenarios in-flight. This framework utilizes all existing, public aerodrome infrastructures in metropolitan areas as potential contingency landing sites. Metrics such as Contingency Landing Assurance Percentage and Cruise Altitude Floor requirement are introduced to quantitatively measuring the safety of any UAM trip and provide recommendations on safe cruising altitudes. A demonstration case in the Chicago Metropolitan Area between DuPage Regional Airport and John H. Stroger Hospital Helipad is shown and discussed. Furthermore, aggregate analysis of 434 UAM trips in Chicago Metropolitan Area between Regional Airports, between Regional and Heliports, and between Heliports is performed, along with sensitivity studies involving wind and turn control restrictions. The results discuss variations in Cruise Altitude Floor, Flight Time, and Energy Consumption of these trips using an eVTOL vehicle.</p>

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