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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.
681

Početnosť a trendy udalostí dažďa na snehovú pokrývku na vybraných meteorologických staniciach v Českej republike / Frequency and trend analysis of rain-on-snow events at selected meteorological stations in the Czech Rebublic

Kakalejčík, Matej January 2017 (has links)
Rain-on-snow events represent a natural hydro-meteorological phenomenon and their occurrence is often associated with floods. Due to the climate change occurrence, rain-on snow events are also changing. The main goal of diploma thesis is to define spatial and temporal occurrence of rain-on-snow events at 16 selected meteorological stations in the Czech Republic between the years 1966-2012. Spatial occurrence of rain-on-snow events is expressed by number of events per meteorological station. Final number of events varies widely even between the stations with similar altitude. Stations with the highest frequency of rain-on-snow events are located in Jizerské hory between 675 and 780 m a.s.l. Temporal occurrence of rain- on-snow events is expressed by number of events per year and month respectively. Time series of rain-on-snow events were analysed by statistical trends to gain information about changes in occurrence over time. Most of the stations proved no statistically significant trend. There was a trend detected only at four out of 16 stations. Three meteorological stations showed a rising trend, whereas one station signalled a decreasing trend. More complex results were produced by the trend analysis of monthly time series of rain-on snow events. Nine stations yielded at least one month with a...
682

Effects of spatially variable plant available water on optimal corn seeding rate – field scale and site-specific approaches

Haag, Lucas A. January 1900 (has links)
Master of Science / Department of Agronomy / Scott A. Staggenborg / Spatial variability in plant available water can be caused by uncontrollable factors such as topography and soil texture as well as controllable factors such as residue management. Research located on the High Plains evaluated the impact of wheat (Triticum aestivum L.) stubble height on snow catch, plant available water at seeding, and optimal corn seeding rates. Treatments consisted of stripper harvest height of 71 cm (28 in.), cut heights of 25 cm (10 in.), and 10 cm (4 in.) Measured snow depths were significantly different among treatments (p<0.0001) with equivalent precipitation of 5.77 (2.27), 3.25 (1.28), and 1.73 cm (0.68 in.) for the stripped, 25 cm, and 10 cm heights respectively. Available soil water at planting increased 24% as stubble height increased from 10 to 71 cm (4 to 28 in) in one year of the study. Two corn hybrids of varying maturity (97 and 108 days) were planted into the stubble treatments at seeding rates ranging from 2.47 to 5.43 plants m[superscript]-2 (10 to 22 000 plants ac[superscript]-1). In the dry year, the long season hybrid responded positively to increasing population in tall stubble and negatively in short stubble. Yield of the short season hybrid increased with increasing stubble height and was mostly unresponsive to population. Grain yields of both hybrids responded positively to increasing plant population in a wet year. Treatments also affected the yield components of yield plant[superscript]-1, kernel weight, and kernels plant[superscript]-1. Managing seeding rates for uncontrollable factors was attempted with small-plot and field scale research across 3 fields in northeast Kansas. A relationship between soil electro-conductivity (EC) and measured water holding capacity values was developed for one study field. This quadratic relationship was significant (p<0.0001) and explained variability in water holding capacity with respect to EC quite well (R[superscript]2=0.6239). Responses from small plots showed that sites differing in population response characteristics could be identified. Field scale data was used to derive a function describing optimal seeding rate with respect to soil EC. In the field under study, optimal seeding rates varied from 3.08 to 8.74 plants m[superscript]-2 (12 500 to 35 375 plants ac-1).
683

Geología de President Head, isla Snow, archipiélago del Sur, Antártica

Israel Omerovic, Lea Sofía January 2015 (has links)
Geóloga / En el siguiente estudio se describe la geología de President Head, una pequeña península libre de hielo que se ubica en el extremo nororiental de isla Snow, en el archipiélago Shetland del Sur. Se realizó una campaña a terreno en el mes de febrero de 2013 con el objetivo de estudiar la evolución paleoambiental de las unidades para contextualizarlas dentro de la paleogeografía propuesta para la región de la península Antártica en el Cretácico Temprano. Para estos fines se elaboró un mapa geológico, se levantaron columnas estratigráficas y se realizó un estudio petrográfico de las rocas aflorantes. Los niveles estratigráficos inferiores de President Head corresponden a una unidad sedimentaria marina de brechas, areniscas, lutitas y fangolitas asociada a una serie de flujos gravitacionales submarinos, a la cual es posible asignar una edad valanginiana media según la presencia de fragmentos de un amonite que correspondería a la género Olcostephanus. Estos estratos se correlacionan con las Formaciones President Beaches o Chester Cone del Grupo Byers en isla Livingston. Separada por una discordancia erosiva de edad valanginiana tardía - barremiana, posiblemente asociada al levantamiento y progresión hacia el oeste del arco volcánico de la península Antártica, se encuentra una unidad volcano-sedimentaria continental, compuesta por una alternancia de lutitas, fangolitas y areniscas, con tobas y conglomerados en niveles superiores. Los niveles finos, depositados probablemente en la llanura de inundación de un pequeño río meándrico, son ricos en fósiles vegetales de Bennettitales principalmente, afines a una edad aptiana - aptiana tardía. La datación de una tufita de la porción inferior de la sucesión mediante el método U/Pb en circones, arrojó una edad albiana temprana (109 ± 1,4 Ma), a partir de lo cual se infiere que esta unidad correspondería a un nivel estratigráficamente superior de la Formación Cerro Negro presente en península Byers (isla Livingston) durante un segundo pulso volcánico. Toda la sucesión se encuentra intruida por numerosos diques, sills y pequeños stocks doleríticos de edad indeterminada (probablemente eocena), asociados al magmatismo Cenozoico que afectó en forma extensiva al archipiélago Shetland del Sur y a la península Antártica. Se concluye que durante el Cretácico Temprano península President Head formó parte de la Cuenca Byers, cuya evolución se encuentra íntimamente ligada al desarrollo del arco volcánico de la península Antártica. Entre el Kimmeridgiano y el Albiano temprano ésta registra una transición discontinua de sedimentación pelágica/hemipelágica a un abanico de talud submarino profundo, seguido de sistemas marinos someros a, finalmente, un ambiente volcánico fluvial y lacustre. Una evolución similar es observada en las islas Adelaida y Alejandro I.
684

Företagsstrategi och kapitalstruktur : en kvantitativ studie om hur företagets strategiorientering påverkar dess kapitalstruktur, med fokus på svensk hälsovårdssektor / Corporate strategy and capital structure : a quantitative study about how a firm’s strategic orientation affects its capital structure, with focus on the Swedish Healthcare industry

Nguyen, Hai, Spasovic, Dejan January 2021 (has links)
Företagsfinansiering är ett väl diskuterat ämne de senaste årtionden. Alla beslut som fattas av företagsledningen innebär finansiella konsekvenser för företaget. Ett av de viktigaste områdena inom företagsfinansiering är kapitalstrukturen, som handlar om hur stor företagets totala skulder är i förhållande till det egna kapitalet. Det finns många faktorer som påverkar företagets kapitalstruktur, nämligen lönsamhet, storlek med flera. Med grund i The pecking order theory samt Miles och Snows typology försöker vi i denna uppsats att förklara sambandet mellan företagsstrategi och kapitalstruktur. Företagen delas in i olika strategier utifrån hur stor andel av sin nettoomsättning respektive företag spenderar på forskning och utveckling. Vår urvalsgrupp består av 54 företag inom hälsovårdsindustri i Sverige. Alla dessa bolag är listade på börsen Nasdaq Stockholm. Utav de här 54 bolagen kunde vi identifiera 12 bolag med försvarare strategi, 36 företag som har prospektör strategi och 6 företag med analyserare strategi. Våra resultat tyder på att företag med försvarare strategi är positivt och statistiskt signifikant relaterade till använding av skulder. Däremot är prospektörer signifikant och negativt relaterade till användning av skuldfinansiering. Dock kunde inte vi hitta något statistiskt säkerställt samband mellan analyserare och skuldfinansiering. Denna uppsats bidrar till ökade förståelser för hur företagsstrategi och kapitalstruktur kan vara relaterade till varandra. / Corporate finance is a well-debated subject over the last decades. All the decisions that are made by corporate managers have financial implications. One of the most important issues in corporate finance is capital structure, which refers to the proportion of total debt a company has compared to its total equity. There are many factors that affect the capital structure of a firm, namely profitability, size, and many other factors. Based on The pecking order theory, and Miles and Snows typology, this bachelor thesis aims to explore how strategy orientations influence the choice of capital structure. Firms are categorized in different strategies based on how much they spend on R&amp;D activities. Our sample consists of 54 Swedish Healthcare companies that are listed on NASDAQ Stockholm. Out of those 54 firms, we could find 12 firms with defender strategy, 36 firms with prospector strategy, and 6 firms with analyzer strategy. Finally, the results of the study show that defenders are significantly and positively related to the use of debt financing. In contrast, prospectors are significantly and negatively related to the use of debt. And lastly, we could not find any statistically significant relationship between analyzers and the use of debt financing. This study contributes to the knowledge about the link between organizational strategy and capital structure.
685

Objekt střediska živočišné výroby / Building of Centre of Livestock Production

Vidová, Miriama January 2019 (has links)
My diploma theisis is focused on design and assessment of structural systém of industrial building in tended for livestock farming. The design is processed in two options. Both oft hem has the same dimensions but cross sections of the supporting elements are changed. Floor plan of the first part is a rectangular shape, dimension is 29,28 m x 24,8 m. Floor plan of the second part is a rectangular shape, dimension is 161,18 m x 46,8 m. Slope of saddle roof is 18°.
686

Víceúčelová sportovní hala / Multi-purpose sports building

Šandor, Peter January 2020 (has links)
The goal of my thesis is the design of a multipurpose sport hall in Litoměřice locality made in two separate variants. Objects ground plan dimensions are 38x38 meters and the height of the object is 16 meters. Used material is S235 steel and C20/25 concrete. The periphery and roof casing of the object is realized from sandwich panels. The carrying construction of the object is made from cross truss, oblong truss and from pillars. Thesis consists of assessing the carrying elements of the construction, selected details and drawing documentation.
687

Zimní stadion v Olomouci / Winter Stadium in Olomouc

Tomčíková, Lucie January 2020 (has links)
The content of the bachelor thesis is static verification and the desing of two options of a roofing of the winter stadium in Olomouc. The object has a rectangular plan of dimension 68 x 100 m, the minimum clearance is given by requirements of the operation of winter sports. Steel construction is made of steel strength class S355. The calculations are made according to valid norms ČSN EN.
688

Ground-based remote sensing of Antarctic and Alpine solid precipitation / Télédétection au sol de précipitations solides antarctiques et alpines

Durán Alárcon, Claudio 23 October 2019 (has links)
Les précipitations solides jouent un rôle crucial dans le système climatique terrestre, ainsi que dans le maintien des écosystèmes et le développement des activités humaines. Les incertitudes associées aux estimations quantitatives des précipitations ainsi que celles concernant les projections des modèles climatiques font de cette composante du cycle hydrologique un sujet de recherche important. La télédétection permet de suivre les précipitations et les nuages dans des régions où les observations in situ sont rares et dispersées, mais avec une résolution temporelle limitée ainsi qu’une zone aveugle près du sol pour les capteurs spatiaux, et une visibilité limitée dans la basse atmosphère en terrain complexe pour les radars au sol. Les objectifs de cette thèse sont les suivants : 1) caractériser les nuages et les précipitations en Antarctique, en détectant la présence d’eau liquide surfondue et de particules de glace près du sol à l'aide d'un lidar 532-nm, polarisé, au sol ; 2) caractériser la structure verticale des précipitations dans deux régions contrastées mais importantes de la cryosphère, l’Antarctique et les Alpes, dans la basse troposphère, en utilisant des radars au sol.Dans cette étude, une méthode de détection des hydrométéores dans les nuages et les précipitations est proposée à l'aide de données lidar complétées par celles d’un <<micro rain radar>> (MRR) en bande K pour améliorer la détection des précipitations, ces deux instruments étant déployés à la station Dumont d'Urville (DDU) en Antarctique de l’Est. Une méthode fondée sur le facteur de dépolarisation lidar, le coefficient de rétrodiffusion atténué et l'utilisation d’un partitionnement en k-moyennes est développée. La classification des particules des nuages et des précipitations permet de documenter la distribution verticale de l'eau liquide surfondue, ainsi que des particules de glace sous différentes formes. La comparaison entre les classifications obtenues depuis le sol et celles obtenues à partir des données satellitaires montre des formes similaires pour la distribution verticale de l'eau liquide surfondue dans les nuages.La structure verticale des précipitations près de la surface est analysée à l'aide des moments Doppler obtenus à partir de trois MRRs situés à DDU, à la station Princess Elisabeth (PE) à l'intérieur de l'Antarctique de l’Est, et à la station du Col de Porte (CDP) dans les Alpes françaises. Ces analyses montrent que le climat local joue un rôle important dans la structure verticale des précipitations. En Antarctique, les forts vents catabatiques soufflant du haut plateau jusqu'à la côte diminuent le facteur de réflectivité radar près de la surface en raison de la sublimation des flocons de neige. Les moments Doppler fournissent aussi de riches informations pour comprendre les processus liés aux précipitations, tels que l'agrégation et le givrage, observés notamment à DDU et au Col de Porte.Les résultats montrent également qu'à l'intérieur du continent Antarctique, une partie significative (47%) des profils de précipitations présentent une sublimation complète avant la surface en raison des conditions atmosphériques sèches, alors que sur la côte de l'Antarctique, cela ne concerne qu’environ un tiers des profils (36%). Dans les Alpes, ce pourcentage est réduit à 15%. La majeure partie de la sublimation est observée en dessous de l'altitude où les profils de CloudSat sont contaminés par la proximité du sol. Par conséquent, ce phénomène ne peut pas être entièrement décelé depuis l'espace avec les capteurs actuels.Cette thèse contribue à l'étude de la structure verticale des précipitations neigeuses dans la basse troposphère ; elle est utile pour l'évaluation des produits de télédétection concernant les précipitations qui peuvent présenter de fortes limitations à la proximité de la surface. / Solid precipitation plays an important role in the Earth's climate system, as well as for the maintenance of ecosystems and the development of human society. The large uncertainty in precipitation estimates and the discrepancies within climate model projections make this component of the hydrological cycle important as a research topic. Remote sensing allows to monitor precipitation and clouds in regions where in-situ observations are scarce and scattered, but with limited temporal resolution and a blind zone close to the ground level for spaceborne sensors, and limited visibility in the lower atmosphere in complex terrain for ground-based radars. The objectives of this dissertation are the following: 1) to characterize cloud and precipitation in Antarctica, detecting the presence of supercooled liquid and ice particles near the ground level using a ground-based 532-nm depolarization lidar; 2) to characterize the vertical structure of the precipitation in two contrasted but important regions of the cryosphere, Antarctica and the Alps, in the low troposphere using ground-based radars.In this study, a cloud and precipitation hydrometeor detection method is proposed using lidar data, complemented with a K-band micro rain radar (MRR) to improve the detection of precipitation, both instruments deployed at the Dumont d'Urville (DDU) station in East Antarctica. A method based on lidar depolarization and attenuated backscattering coefficient and the use of k-means clustering is developed for the particle classification. The classification of cloud and precipitation particles provides the vertical distribution of supercooled liquid water, as well as planar oriented ice and randomly oriented ice particles. The comparison between ground-based and satellite-derived classifications shows consistent patterns for the vertical distribution of supercooled liquid water in clouds.The vertical structure of precipitation near the surface is analyzed using the Doppler moments derived from three MRR profiles at DDU, the Princess Elisabeth (PE) station, at the interior of East Antarctica, and at the Col de Porte (CDP) station, in the French Alps. These analyses demonstrate that local climate plays an important role in the vertical structure of the precipitation. In Antarctica, the strong katabatic winds blowing from the high plateau down to the coast decrease the radar reflectivity factor near the surface due to the sublimation of the snowfall particles. Doppler moments also provide rich information to understand precipitation processes, such as aggregation and riming, as observed at DDU and CDP.The results also show that in the interior of the Antarctic continent a significant part (47%) of the precipitation profiles completely sublimate before reaching the surface, due to the dry atmospheric conditions, while in the coast of Antarctica it corresponds to about the third part (36%). In the Alps, this percentage is reduced to 15%. The major occurrence of particle sublimation is observed below the altitude where CloudSat profiles are contaminated by ground clutter. Therefore, this phenomenon cannot be fully captured from space with the current generation of sensors.This dissertation contributes to the study of the vertical structure of snowfall in the low troposphere, useful for the evaluation of precipitation remote sensing products, which may have severe limitations in the vicinity of the surface.
689

Influence of snow properties on directional surface reflectance in Antarctica

Carlsen, Tim 15 October 2018 (has links)
The significance of the polar regions for the Earth’s climate system and their observed amplified response to climate change indicate the necessity for high temporal and spatial coverage for the monitoring of the reflective properties of snow surfaces and their influencing factors. Therefore, the specific surface area (SSA, as a proxy for snow grain size) and the hemispherical directional reflectance factor (HDRF) of snow were measured for a 2-month period in central Antarctica (Kohnen research station) during austral summer 2013/14. The SSA data were retrieved on the basis of ground-based spectral surface albedo measurements collected by the COmpact RAdiation measurement System (CORAS) and airborne observations with the Spectral Modular Airborne Radiation measurement sysTem (SMART). The snow grain size and pollution amount (SGSP) algorithm, originally developed to analyze spaceborne reflectance measurements by the MODerate Resolution Imaging Spectroradiometer (MODIS), was modified in order to reduce the impact of the solar zenith angle on the retrieval results and to cover measurements in overcast conditions. Spectral ratios of surface albedo at 1280 and 1100 nm wavelength were used to reduce the retrieval uncertainty. The retrieval was applied to the ground-based and airborne observations and validated against optical in situ observations of SSA utilizing an IceCube device. The SSA retrieved from CORAS observations varied between 29 and 96 m2 kg-1. Snowfall events caused distinct relative maxima of the SSA which were followed by a gradual decrease in SSA due to snow metamorphism and wind-induced transport of freshly fallen ice crystals. The ability of the modified algorithm to include measurements in overcast conditions improved the data coverage, in particular at times when precipitation events occurred and the SSA changed quickly. SSA retrieved from measurements with CORAS and MODIS agree with the in situ observations within the ranges given by the measurement uncertainties. However, SSA retrieved from the airborne SMART data underestimated the ground-based results. The spatial variability of SSA in Dronning Maud Land ranged in the same order of magnitude as the temporal variability revealing differences between coastal areas and regions in interior Antarctica. The validation presented in this study provided an unique test bed for retrievals of SSA under Antarctic conditions where in situ data are scarce and can be used for testing prognostic snowpack models in Antarctic conditions. The HDRF of snow was derived from airborne measurements of a digital 180° fish-eye camera for a variety of conditions with different surface roughness, snow grain size, and solar zenith angle. The camera provides radiance measurements with high angular resolution utilizing detailed radiometric and geometric calibrations. The comparison between smooth and rough surfaces (sastrugi) showed significant differences in the HDRF of snow, which are superimposed on the diurnal cycle. By inverting a semi-empirical kernel-driven model for the bidirectional reflectance distribution function (BRDF), the snow HDRF was parameterized with respect to surface roughness, snow grain size, and solar zenith angle. This allows a direct comparison of the HDRF measurements with BRDF products from satellite remote sensing.
690

Stanovení rozsahu sněhové pokrývky z radarových dat / Determination of Snow Cover Area from RADAR imagery

Součková, Jana January 2010 (has links)
This thesis deals with snow cover mapping by using time-series of SAR images of the sensors ENVISAT ASAR and TerraSAR-X. The methodology is based on the so-called Nagler's algorithm, which is based on determination of the change of absorption of radar signal due to the liquid water content in the snow cover. The resulting ratio image is classified into the areas with wet snow or without it according to the selected threshold value. The results are compared with the maps of snow cover derived from MODIS optical data and with data from meteorological stations of CHMI. The main aims of this work are to suggest most suitable conditions (time of the year, weather) for acquisition of reference images, to find the change of the threshold value with respect the chosen reference image and the type of land cover. The same methodology should then be applied on the radar data of shorter wavelength. The obtained results will be further used for improving the methodology of snow cover mapping from SAR data in the Czech Republic.

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