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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.
221

Distúrbios ondulatórios de leste no nordeste brasileiro: climatologia e modelagem numérica / Easterly waves Disturbances over Northeast Brazil: Climatology and Numerical Modeling.

Helber Barros Gomes 22 October 2012 (has links)
Uma climatologia de 21 anos dos Distúrbios Ondulatórios de Leste (DOLs) sobre a região NEB foi realizada com o intuito de obter um melhor entendimento dos processos dinâmicos e sinóticos do ciclo de vida destes sistemas, incluindo gênese, crescimento/decaimento, trajetória e dissipação. Adicionalmente, foi avaliada a eficiência do modelo de mesoescala WRF em simular este tipo de sistema. A identificação dos DOLs foi obtida de forma subjetiva através de imagens de satélite no canal infravermelho e campos de linhas de corrente e vorticidade relativa nos níveis de 1000, 850, 700, 500 e 200 hPa da reanálise do ERA-Interim. Neste período foram identificados 518 eventos de DOLs, onde 97% (3%) dessas ondas atingiram (não atingiram) a região do NEB, 64% (36%) foram convectivas (não convectivas) e 14% (86%) atingiram a região da Amazônia. Os principais sistemas que deram origem aos DOLs foram: Zona de Convergência Intertropical (ZCIT), Vórtice Ciclônico de Altos Níveis (VCAN), Frentes Frias (FF) e conglomerados convectivos provenientes da costa oeste da África (AF). Além destes, a interação entre os sistemas AF/FF, AF/ZCIT, AF/VCAN e ZCIT/FF estiveram associadas a sua formação. Em média, foram observadas aproximadamente 25 ondas por ano, com máxima (mínima) frequência compreendida entre os meses de Março a Agosto (Setembro a Fevereiro) e, com pronunciada variabilidade interanual. O ciclo de vida dos DOLs foi avaliado de forma objetiva a partir de um método automático de identificação e rastreio (TracKH), onde dos 518 eventos identificados na análise subjetiva, conseguiu capturar 342 ondas ( ~ 66%). A partir desta detecção, uma análise foi feita no nível 850 hPa para determinar as características típicas do seu ciclo de vida, que mostra um pico proeminente entre as longitudes de 35°W e 15°W e latitudes de 20°S e 5°N associado a densidade de gênese. A trajetória e dissipação se concentraram sobre a costa leste do NEB, entre os estados de Alagoas e Rio Grande do Norte, porém a dissipação diminuía a medida que adentrava ao continente. Os padrões sinóticos associados aos DOLs foram analisados através da anomalia de composição durante o período de máxima (úmido) e mínima (seco) frequência desde 3 dias antes até um dia após os DOLs atingirem a costa do NEB. Durante o período úmido, a circulação associada aos DOLs apresentou anomalia ciclônica e confluente, vorticidade negativa e convergência até médios níveis, enquanto que em 200 hPa apresentou apenas a característica do cavado. Por outro lado, para o período seco, estas características foram observadas somente em baixos níveis. Anomalias negativas de movimentos verticais e temperatura e positivas de umidade foram observadas associadas aos DOLs nas duas estações, porém atingindo maiores altitudes durante o período seco. A composição de precipitação indicou que os DOLs são responsáveis por um acréscimo de 16% (4%) durante a estação úmida (seca). As características típicas dessas ondas foram: período médio de 8 (73) dias, comprimento de onda de aproximadamente 4500 (5500) km e velocidade de fase da ordem de 6,5 (0,9) m.s-1, para o período úmido (seco). O modelo WRF simulou os padrões sinóticos, a precipitação e as características típicas associadas aos DOLs de forma coerente, sendo comparado aos resultados do Climate Forecast System Reanalysis (CFSR), porém com maior intensidade, para os eventos de 11 e 17 de junho de 2006. / A 21-year climatology of Easterly Wave Disturbances (EWDs) over NEB region was constructed in order to obtain a better understanding of dynamic and synoptic processes life cycle of these systems, including genesis, growth / decay, trajectory and dissipation. Moreover, we evaluated the efficiency of WRF mesoscale model to simulate this type of system. The identification of EWDs was obtained subjectively through satellite images in infrared channel and fields of streamlines and relative vorticity at the levels 1000, 850, 700, 500 and 200 hPa from ERA-Interim reanalysis. During this period, 518 EWDs were identified, where 97% (3%) of these waves hit (not hit) the NEB region, 64% (36%) were convective (non-convective) and 14% (86%) reached the Amazon region. The main systems that gave rise to DOLs were: Intertropical Convergence Zone (ITCZ), Upper-Tropospheric Cyclonic Vortices (UTCV), Cold Fronts (FF) and convective clusters from the west coast of Africa (AF). In addition, the interaction between systems AF/FF, AF/ITCZ, AF/UTCV and ITCZ/FF were associated with their formation. On average, we observed approximately 25 waves per year, with maximum (minimum) frequency between the months of March to August (September to February) and, with pronounced interannual variability. The life cycle of EWDs was evaluated objectively using an automatic method for the identification and tracking (TracKH). From the 518 events identified in the subjective analysis, TracKH was able to capture 342 waves (~ 66%). From this detection, an analysis was made at 850 hPa level to determine the characteristics of their life cycle, which shows a prominent peak around of 35°W-15°W and 20°S-5°N associated with density genesis. The trajectory and dissipation have concentrated over east coast of the NEB, between the states of Alagoas and Rio Grande do Norte, but the dissipation decreased once the systems enter the continent. The synoptic patterns associated with EWDs were analyzed by composing anomaly during the period of maximum (wet) and minimum (dry) frequency from 3 days before until one day after the EWDs reaching the NEB coast. During the wet period, the circulation presented cyclonic and confluent anomaly, negative vorticity and convergence at all levels except at 200 hPa which only showed a trough characteristic while for the dry season, this feature was only observed at low levels. Negative anomalies of vertical movements and temperature and positive humidity associated with EWDs were observed in both seasons, but reaching higher elevations during the dry period. The precipitation composition indicated that the EWDs are responsible for an increase of 16% (4%) during the wet season (dry). Typical characteristics of these waves were: mean period of 8 (73) days, wavelength of about 4500 (5500) km and phase velocity of about 6.5 (0.9) m.s-1 for the wet period (dry). The WRF model simulated the synoptic patterns, precipitation and the typical features associated with EWDs in a coherently manner when compared to the results of the Climate Forecast System Reanalysis (CFSR), but with greater intensity to the events of 11 and 17 June 2006.
222

Studie zvýšení rychlosti v úseku Boří les - Hrušovany nad Jevišovkou / Study of Speed Increasing for the Boří les - Hrušovany nad Jevišovkou Track Section

Grenar, Filip January 2014 (has links)
The aim of this work is to study track speed increase in section between Boří les – Hrušovany nad Jevišovkou – line Břeclav – Znojmo. In terms of this work directional and height adjustment is beig suggested. The ambition was to ensure basic accessibility of this area within existing range. The study was prepared and respects costs.
223

Rekonstrukce žst. Hrušovany u Brna / Upgrading of Hrušovany u Brna Railway Station

Ječmínková, Michaela January 2014 (has links)
The aim of this thesis is to present a design of the reconstruction of platforms. The proposed solution fulfills the requirements of the accessibility by people with reduced mobility and low vision. Three new platforms with height of 550 mm (measured from rail level) were designed to meet above requirements. The need of additional modifications, e.g. reconstruction of drainage network, was also taken into consideration. Solution also takes reopening of the railway from Hrušovany u Brna to Židlochovice into account.
224

Analýza strukturních elementů DNA / Analysis of DNA Structure Elements

Knytl, Marek January 2013 (has links)
The aim of this master's thesis is the design and implementation of tool trackAnalysis for statistical analysis of DNA structure elements. The positions of individual elements in genome are obtained in the form of the track, and with these positions the tool performs a set of analyzes, including randomness test of track, test examining distances between track and genes, detection of clusters and overlaps. The indivudual tests results can be linked together. The results will be displayed in the form of a list, a graph or a new annotation track. An important part of this thesis is also testing the resulting tool on a set of real data.
225

Návrh zdvoukolejnění železniční tratě v úseku Chlumec nad Cidlinou - Hradec Králové / Design of double-tracking study of the track section Chlumec nad Cidlinou - Hradec Králové

Hlávka, Miloslav January 2016 (has links)
Diploma thesis studies a possibility of doubling track between Chlumec nad Cidlinou and Hradec Králové. It proposes some solutions which differ in the lenght of the track section where track speed is increased to 160 kmph. Also, the possibilities of elimination of railway crossings with the roads of any category are examined and overview of costs for construction.
226

Výpočtová analýza jízdního chování vozidla / Computational Analysis of Vehicle Handling

Doležal, Kamil January 2016 (has links)
The diploma thesis deals with computational analysis of driving behavior of a vehicle. The first section summarizes and explains the basic parameters of steering geometry. Next section covers the tests which are used to study driving behavior of vehicles. The practical part consists of computational model that is able to simulate and evaluate tests of step steer input.
227

Stack Number, Track Number, and Layered Pathwidth

Yelle, Céline 09 April 2020 (has links)
In this thesis, we consider three parameters associated with graphs : stack number, track number, and layered pathwidth. Our first result is to show that the stack number of any graph is at most 4 times its layered pathwidth. This result complements an existing result of Dujmovic et al. that showed that the queue number of a graph is at most 3 times its layered pathwidth minus one (Dujmovic, Morin, and Wood [SIAM J. Comput., 553–579, 2005]). Our second result is to show that graphs of track number at most 3 have layered pathwidth at most 4. This answers an open question posed by Banister et al. (Bannister, Devanny, Dujmovic, Eppstein, and Wood [GD 2016, 499–510, 2016, Algorithmica, 1–23, 2018]).
228

Nízko teplotní vývoj granulitů jižní části moldanubické zóny Českého masivu / Low-temperature evolution of granulites in the Moldanubian Zone of the southern Bohemian Massif

Kořínková, Dagmar January 2010 (has links)
The Variscan orogeny occured during Devonian to Carboniferous convergence between peri- Gondwanan crustal segments and the northern European plate (Baltica). Due to the convergence, Bohemian Massif represents the easternmost and largest exposure in the European Variscan belt. In the southern part of the Bohemian Massif, the Moldanubian Zone consists of several crustal segments with different polyphase tectonometamorphic histories. Moldanubian Zone is considered to represent the Variscan orogenic root, being surrounded by rigid and less metamorphosed blocks to the NW and SE. Structurally highest unit of the Moldanubian Zone is the Gföhl Unit, which is built by heterogeneous assemblage of high-pressure crustal and upper-mantle rocks comprising granulites, peridotites, pyroxenites and eclogites exhumed during Variscan orogeny. The apatite samples studied in my diploma thesis come from different types of granulites from the Blanský les granulite massif (BLGM) located SW of the town of České Budějovice. BLGM is the largest granulite body of the southern Bohemian Massif, is an integral part of the Gföhl Unit. BLGM consists mainly of calc-alkaline high-pressure felsic garnet ± kyanite granulites, which enclose up to several kilometers long lenses of ultrabasic rocks, numerous boudins of mafic...
229

Design of railway bridges considering LCA

Thiebault, Vincent January 2010 (has links)
Environmental awareness has strongly increased these last years, especially in the developed countries where societies have become increasingly preoccupied by the natural resource depletion and environmental degradation. At the same time, the increasing mass transportation demand throughout the European Union requires the development of new infrastructures. Life Cycle Assessment is increasingly used to provide environmental information for decision-makers, when a choice is to be made about the transportation mode to be implemented on a given route. In a life-cycle perspective, not only the environmental pressure of the operation of vehicles but also the burden from the infrastructure, in particular bridges as key links of the road and railway networks, has to be assessed when comparing transportation modes. Based on an extensive literature review, a simplified quantitative LCA is implemented in order to compare the environmental performance of two railway bridge designs. It is meant to be useful at an early stage in the design process, when no detailed information about the bridge is available, and when rough environmental estimations are needed. The Excel based model covers the entire life-cycle of the bridge, from raw material extraction to construction materials recycling and disposal. Various assumptions and omissions are made to narrow the scope of the analysis. For instance, processes that are found insignificant in the literature are omitted, and only a limited set of relevant emissions and impacts to the environment is considered. The model provides fully transparent results at the inventory and impact assessment level. The streamlined approach is tested by comparing the environmental burden throughout the life-cycle of a steel-concrete composite railway bridge on a single span, equipped with either a ballasted or a fixed concrete single track. The results show that the environmental impacts of the fixed track alternative are lower than that of the ballasted track alternative, for every impact categories. In a sustainable development perspective, it would thus have been preferable to install a fixed track over the bridge to reduce its overall impact on the environment by about 77%. The raw material phase is found decisive in the life-cycle of both alternatives. The frequency of the replacement of the track is identified as a key environmental parameter, since the road traffic emissions during bridge closure nearly overwhelmed the other life-cycle stages.
230

Numerical modelling of high-speed railway transition zone

Norberg, Karl January 2022 (has links)
Transition zones are changes in the track structure, detected by an abrupt deviationin track stiffness and/or differential settlements. One inevitable transition zone is thebridge approach. This study has investigated in this transition zone, adapted for highspeed,ballastless track. The aim was to observe the general behaviour of the transitionzone including its critical components, and to compare different measures, transitionconstructions, to manage with the eventual problems. A base model, called Nullmodel,was developed using the 3D finite element method to evaluate the behaviour of thetransition zone. Based on the Nullmodel, six comparative models have been created,including different types of transition constructions within the substructure. New forthis study is that it investigates the overall behaviour of the transition zone, and alsothe substitution of subballast in combination with approach blocks.For the general behaviour of the transition zone, the results have shown that theballastless track does not behave as a traditional ballasted track. Furthermore,the direction of travel affects the magnitude of different dynamical parameters.Comparing different transition constructions, replacing the subballast with ahydraulically bonded layer in combination with an approach block with cementbounded granular material is found to be the best alternative. Finally, the invertedapproach block is found to be an equally good, or better, mitigative measure incomparison with the regular approach block.

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