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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.
81

Simulação de grandes escalas de escoamentos turbulentos com filtragem temporal via método de volumes finitos / Temporal large eddy simulation of turbulent flows via finite volume method

Laís Corrêa 14 December 2015 (has links)
Este trabalho tem como principal objetivo o desenvolvimento de um método numérico para simulação das grandes escalas de escoamentos turbulentos tridimensionais utilizando uma modelagem de turbulência baseada em filtragem temporal (denominada TLES - Temporal Large Eddy Simulation). O método desenvolvido combina discretizações temporais com ordem de mínima precisão 2 (Adams-Bashforth, QUICK, Runge-Kutta), um método de projeção de ordem 2, com discretizações espaciais também de ordem 2 obtidas pelo método de volumes finitos. Esta metodologia foi empregada na simulação de problemas teste turbulentos como o canal e a cavidade impulsionada, sendo este último resultado simulado pela primeira vez com modelagem TLES. Os resultados mostram uma excelente concordância quando comparado com resultados de simulações diretas (DNS) e dados experimentais, superando resultados clássicos obtidos com formulação LES com filtragem espacial. / The main objective of this work is to develop a numerical method for large eddy simulation of tridimensional turbulent flows using a model based on temporal filtering (TLES - Temporal Large Eddy Simulation). The developed method combines at least 2nd order temporal discretizations (Adams-Bashforth, QUICK, Runge-Kutta), a 2nd order projection method, and 2nd order spatial discretizations obtained by the finite volume method. This methodology was employed to the simulation of turbulent benchmark problems such as channel and lid-driven cavity flows. The latter is simulated for the first time using a TLES turbulence modelling. Results show excellent agreement when compared to Direct Numerical Simulations (DNS) and experimental data, with better results than classical results produced by standard LES formulation with spatial filtering.
82

Přímo volený prezident jako plebiscitární prvek v české politickém systému / The popularly elected president as a plebiscitarian element in the Czech political system

Vostrčil, Jan January 2019 (has links)
The diploma thesis will deal with examining the position of a directly elected president through a plebiscitary approach to the democracy. This approach is based on the idea that contemporary democracy based on vocal power of the people becomes a dangerous fiction in eyes of the theorists of plebiscitarism. Their statements are supported by several trends, among other things, the increasing importance of mass media, or the personalization of politics itself, that significantly reduce means ordinary citizens to participate in political decisions. The Czech Republic is no exception and the introduction of the popular election of the president can be considered as the most visible outcome of these trends. Despite the often negative connotations associated with the notion of plebiscitarism in the past, as well as with certain modifications provided by Jeffrey Green and other contemporary political theorists of plebiscitary democracy, it can be considered as a the most suitable mean of controlling the activities of politicians, even the popularly elected president. The main goal of my diploma thesis is to describe a several theoretical approaches that deal with a plebiscitary democracy as possible alternative to solving issues related to contemporary democracies. These appeals to "the other sense(s)"...
83

Evaluation expérimentale et modélisation de la contamination induite par laser sur les optiques spatiales / Experimental evaluation and modeling of laser-induced contamination on space optics

Gebrayel El Reaidy, Georges 06 December 2018 (has links)
Dans le domaine du spatial, des sources laser à forte puissance sont déjà employées dans le cadre d’activités scientifiques. On peut citer par exemple l’analyse à distance de la composition chimique des roches sur Mars par LIBS (Laser Induced Breakdown Spectroscopy) et le sondage atmosphérique par Lidar (Light Detection And Ranging) pour l’amélioration des prédictions météorologiques. Cependant l’endommagement laser (LID) et la contamination induite par laser (LIC) sur les composants optiques des systèmes demeurent des risques difficiles à anticiper. En ce qui concerne la LIC, l’interaction du flux laser avec les optiques de l’instrument en orbite peut provoquer des dégradations irréversibles, liées à la création de dépôts organiques absorbants qui peuvent induire des endommagements laser dans le temps. L’effet LIC reste donc aujourd’hui un obstacle au développement de sources laser de puissance pour les applications sans maintenance possible et possédant des durées de vie raisonnables. Une étude paramétrique de l’effet LIC est proposée dans cette thèse afin de progresser dans la compréhension des mécanismes mis en jeu / Since their first implementation in satellite systems, lasers have proven to be very versatile devices in space applications. They are key components of a variety of space-based instruments performing altimetry, light detection and ranging, laser sensing, and laser communication. However, laser induced damage (LID) and laser-induced contamination (LIC) of optical surfaces are a major failure risk for space-bound laser instruments. Regarding the LIC effect, the interaction of the laser with slight traces of organic compounds on the optical surface leads to the formation of a highly absorbing nanometric deposit on the laser footprint. Under certain conditions, this deposit may cause laser induced damage. Today, mainly the LIC effect remains an obstacle for the development of reliable and long-living spaceborne lasers. A parametric study concerning this effect was carried out in this work in order to enhance our understanding of the various mechanisms involved
84

Numerická simulace proudění nestlačitelných kapalin metodou spektrálních prvků / Numerical simulation of incompressible fluid flow by the spectral element method

Pokorný, Jan January 2008 (has links)
Tato diplomová práce prezentuje metodu spektrálních prvků. Tato metoda je použita k řešení stacionárního 2-D laminárního proudění Newtonovské nestlačitelné tekutiny. Proudění je popsáno stacionarní Navier-Stokesovou rovnicí. Dohromady s okrajovou pod- mínkou tvoří Navier-Stokesův problém. Na slabou formulaci této úlohy je aplikována metoda spektrálních prvků. Touto discretizací se získá soustava nelineárních rovnic. K obrdžení lineární soustavy je použita Newtonova iterační metoda. Podorobný algorit- mus tvoří jádro Navier-Stokeseva solveru, který je naprogramován v Matlabu. Na závěr jsou pomocí tohoto solveru řešeny dva příklady: proudění v kavitě a obtékání válce. Přík- lady jsou řešeny pro různé Reynoldsovy čísla. První od 1 do 1000 a druhý od 1 do 100.
85

Vícejazykový fonémový rozpoznávač / Multilingual Phoneme Recognizer

Vobr, Vojtěch Unknown Date (has links)
Aim, of this master thesis is training of phoneme recognizer with phoneme set, which have been made by merging of several phoneme sets, which are containted in SpeechDat-E database and find out if this kind of recognizer will have better results than recognizers which were trained on one language. This work also deals with phoneme sets, principles of phoneme recognition using recognizers based on artifical neural networks, language identification and merging of given phoneme sets. Also is described process of training phoneme recognizer and phoneme recognition.
86

Residential Low Impact Development Practices: Literature Review and Multicriteria Decision Analysis Framework for Detached Houses

Sumaiya, Ummay January 2021 (has links)
Low Impact Development (LID) is a sustainable stormwater management approach that aims to control runoff close to its source, mimicking the natural hydrological processes such as infiltration and storage. It is being adopted by many cities, where its implementation is rapidly evolving. The LID practices are small-scale measures; therefore, they need to be widely implemented to impact significantly. The selection of LIDs depends on the land use and characteristics of the area of interest. This study focuses on residential LIDs. First, a systematic and bibliometric literature review is conducted on the residential LIDs articles published up to the year 2020; a total of 94 papers were found in the Web of Science. This review resulted that LID implementation in residential areas still needs to be investigated. To assist the City, engineers, and policy-makers in implementing the suitable LIDs for detached houses, a multi-criteria decision analysis framework incorporating a hydrological model is developed in this study. The commonly used LIDs were identified, which are rain gardens, permeable pavement, rain barrels, soakaways. Seven criteria were selected – runoff depth reduction rate, peak runoff reduction rate, installation cost, maintenance cost, retrofit cost, life cycle, and aesthetical view. For the properties of the single-detached house and LIDs, the standards of Credit Valley Conservation (CVC) and Toronto and Region Conservation Authority (TRCA) were followed. The proposed decision-making framework also was applied to a case study. This framework is still in the preliminary stage, thus holds the potential to convert into a tool that will be handy enough for the homeowners and consume less time. / Thesis / Master of Applied Science (MASc)
87

Global stability analysis of three-dimensional boundary layer flows

Brynjell-Rahkola, Mattias January 2015 (has links)
This thesis considers the stability and transition of incompressible boundary layers. In particular, the Falkner–Skan–Cooke boundary layer subject to a cylindrical surface roughness, and the Blasius boundary layer with applied localized suction are investigated. These flows are of great importance within the aviation industry, feature complex transition scenarios, and are strongly three-dimensional in nature. Consequently, no assumptions regarding homogeneity in any of the spatial directions are possible, and the stability of the flow is governed by an extensive three-dimensional eigenvalue problem. The stability of these flows is addressed by high-order direct numerical simulations using the spectral element method, in combination with a Krylov subspace projection method. Such techniques target the long-term behavior of the flow and can provide lower limits beyond which transition is unavoidable. The origin of the instabilities, as well as the mechanisms leading to transition in the aforementioned cases are studied and the findings are reported. Additionally, a novel method for computing the optimal forcing of a dynamical system is developed. This type of analysis provides valuable information about the frequencies and structures that cause the largest energy amplification in the system. The method is based on the inverse power method, and is discussed in the context of the one-dimensional Ginzburg–Landau equation and a two-dimensional flow case governed by the Navier–Stokes equations. / <p>QC 20151015</p>
88

Guidelines and Principles for Sustainable Land Use Planning: A Study of Low-Impact Development Strategies for Grailville, Ohio

Ghode, Mayura January 2007 (has links)
No description available.
89

Development of Optically-coupled Scanning Tunneling Microscope for Investigation of Multi-pulse Laser Induced Defect States and Time Resolved Dynamics

Rodriguez, Ryan James 22 July 2022 (has links)
No description available.
90

Zobrazení prostého lidu ve vybraných dílech finského kánonu / The picture of common people in selected writings of Finnish canon

Palát, Tomáš January 2012 (has links)
Author's name: Tomáš Palát School: Charles University in Prague, Faculty of Arts Institute of Linguistics and Finno-Ugric Studies Nám. Jana Palacha 2, 116 38 Praha 1 Program: Finnish language Title: The picture of common people in selected writings of Finnish canon Consultant: Mgr. Jan Dlask, Ph.D. Number of pages: 79 + attachments Number of attachments: 1 Year: 2012 Key words: Runeberg, Kianto, common people, rural people, Finnish literary canon, cottager, The tales of ensign Stål, Red line, death, dying, nature, bravery, heroism, patriotism, nationalism, clergy, religion This thesis aims to analyze a picture of common people in two separate well-known Finnish writings. First of them is The tales of ensign Stål from Johan Ludvig Runeberg and second is Red line from Ilmari Kianto. Both works were created in a different time periods. The Finnish society in 19th and in the beginning of 20th century was mostly comprised from relatively poor rural people who typically worked in agriculture and describing life of those people was in the same time period very common topic in Finnish literature. In this thesis the picture of common people is being studied through five main topics. How the common people see dying and death; their relationship towards nature; if they are depicted as brave and heroic or...

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