Дисертації з теми "DEMC"
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Bagnara, Maurizio. "Modelling biogeochemical cycles in forest ecosystems: a Bayesian approach." Doctoral thesis, country:IT, 2015. http://hdl.handle.net/10449/25094.
Повний текст джерелаSrivastava, Anurag. "Comparison of Two Algorithms for Removing Depressions and Delineating Flow Networks From Grid Digital Elevation Models." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/34268.
Повний текст джерелаSixty-six watersheds were selected to represent a range of topographic conditions characteristic of the Piedmont and Mountain and Valley regions of Virginia. Analysis was based on USGS 30m DEMs with elevations in integer meters. With few exceptions watersheds fell on single 7.5minute USGS quadrangle sheets, ranged in size from 450 to 3000 hectares, and had average slopes ranging from 3 to 20 percent. ArcView (3.1) with the Spatial Analyst (1.1) extension was used to summarize characteristics of each watershed including slope, elevation range, elevation standard deviation, curvature, channel slope, and drainage density. TOPAZ (ver 1.2) and ArcView were each used to generate a depression-free surface, flow network and watershed area. Characteristics of the areas 'cut' and 'filled' by the algorithms were compared to topographic characteristics of the watersheds. Blue line streams were digitized from scanned USGS 7.5minute topographic maps (DRGs) then rasterized at 30 m for analysis of distance from the derived flow networks.
The removal of depressions resulted in changes in elevation values in 0 - 11% of the cells in the watersheds. The percentage of area changed was higher in flatter watersheds. Changed elevation cells resulted in changes in two to three times as many cells in derivative flow direction, flow accumulation and slope grids. Mean fill depth by watershed ranged from 0 to 10 m, with maximum fill depths up to 40 m. In comparison with ArcView, TOPAZ, on average affected 30% fewer cells with less change in elevation. The significance of the difference between ArcView and TOPAZ decreased as watershed slope increased. A spatial assessment of the modified elevation and slope cells showed that depressions in the DEMs occur predominantly on or along the flow network. Flow networks derived by ArcView and TOPAZ were not significantly different from blue line streams digitized from the USGS quadrangles as indicated by a paired t test. Watershed area delineated by ArcView and TOPAZ was different for almost all watersheds, but was generally within 1%.
Conclusions from this study are: 1) The depressions in 30 m DEMs can make up a significant portion of the area especially for flatter watersheds; 2) The TOPAZ algorithm performed better than ArcView in minimizing the area modified in the process of creating a depressionless surface, particularly in flatter topography; 3) Areas affected by removing depressions are predominantly adjacent to the stream network; 4) For every elevation cell changed, slopes are changed for two to three cells, on average; and 5) ArcView and TOPAZ derived flow networks closely matched the blue line streams.Master of Science
Wöll, Alexander. "Jakub Deml : Leben und Werk (1878-1961) : eine Studie zur mitteleuropäischen Literatur /." Köln : Böhlau, 2006. http://catalogue.bnf.fr/ark:/12148/cb411428140.
Повний текст джерелаPasqualeti, Aniélli Martini. "Investigação da atividade de eletrocatalisadores nanoestruturados para a eletrooxidação de íons BH4- em eletrólito alcalino." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/75/75134/tde-23042013-111531/.
Повний текст джерелаThe direct borohydride fuel cells (DBFC) display a high theoretical cell voltage (1.64) and a high electron number per borohydride ion. Furthermore, the DBFC also presents the advantages of alkaline fuel cells, in which it is possible to use non-noble metal electrocatalysts and, hence, it is economically feasible for practical applications. However the lack of highly efficient electrocatalysts for the borohydride oxidation reaction (BOR) limits the performance of these devices, since its total oxidation, involving the transfer of eight electrons per BH4- ion, competes with parallel reaction pathways with a lower number of exchanged electrons. Recently, theoretical calculations were applied to determine the elementary steps of the reaction kinetics and also to guide metallic electrocatalyst design for borohydride oxidation. Based on the theoretical results, this work aimed at the BOR electrocatalysis investigation on carbon supported nanoparticles, of pure metals, Au/C, Ag/C, Pt/C and Pd/C, and on bimetallic nanoparticles, composed by the combination of these metals. The electrocatalysts were synthesized by chemical and/or impregnation reduction methods, and X-Ray Diffraction, High Resolution Transmission Electron Microscopy and X-Ray Energy Dispersive Spectroscopy techniques were used for their physical characterization. The electrocatalytic activities were studied by steady state polarization curves using rotating disc electrodes. The borohydride hydrolysis, with the production of H2, was monitored in function of the electrode potential by on-line differential electrochemical mass spectrometry. The electrochemical experiments for the pure metal electrocatalysts showed higher electrocatalytic activity for Pd/C, and this was attributed to its high activity for BH3OH- electro-oxidation. The study of BH4- and BH3OH- concentration effect showed that with the increase of concentration, the onset potential shifted to lower values, indicating that the Faradaic currents of borohydride and hydroxyborane electro-oxidation were much higher than the current for the H2 evolution. The increase in the Pd/C load on the electrode led to an increase of the global current reaction at low potentials, which was associated to an increase in total surface area. Among the investigated bimetallic materials, the Pt2Pd/C electrocatalyst presented the higher Faradaic current. The Ag2Pd/C material showed the lower reaction potential onset. Although theoretical calculations pointed out to an increased activity of the Ag-modified Pd/C electrocatalysts in relation to that of pure Pd/C, the electrochemical and mass spectrometry results of this work indicated higher activity for pure Pd/C, and low synergic effect between the Ag and Pd atoms. This was associated to the low degree of interaction between Ag and Pd for the present investigated atomic composition.
Junior, Flávio Colmati. "Estudo de catalisadores de Pt-Sn para o ânodo da célula a combustível de membrana trocadora de prótons alimentada com etanol direto." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/75/75131/tde-27032008-084800/.
Повний текст джерелаCarbon supported Pt-Sn catalysts were prepared by reduction of Pt and Sn precursors with formic acid. The method allowed the efficient preparation of catalysts with low Sn contents (Pt:Sn ratio 9:1) and with high Sn contents (Pt:Sn ratio 1:3. In spite of the fact that Sn was anchored in the material, only part of the Sn is inserted in the fcc structure of Pt. Therefore, a thermal treatment in a reducing atmosphere was necessary to increase the degree of alloy. Thermal treatments were done between 100 and 500 oC and the Pt3Sn material treated at 200 oC showed the best performance in a direct ethanol fuel cell. The thermal treatment at 200 oC allowed an increase of the degree of alloy without modifying the face centered cubic Pt structure and without promoting the coalescence of the nanoparticles anchored on the carbon support. The Pt-Sn catalysts were characterized by X-ray diffraction, X-ray absorption and transmission electron microscopy. The activity for the electro-oxidation of ethanol was evaluated with electrochemical techniques and experiments in a single direct ethanol fuel cell. Studies with Pt single crystals with low and high Miller indices were done to complement the study of the ethanol electro-oxidation.
Goujon, Anne, C. Samir K, Markus Speringer, Bilal Barakat, Michaela Potancoková, Jakob Eder, Erich Striessnig, Ramon Bauer, and Wolfgang Lutz. "A harmonized dataset on global educational attainment between 1970 and 2060 - An analytical window into recent trends and future prospects in human capital development." Cambridge University Press (CUP), 2016. http://dx.doi.org/10.1017/dem.2016.10.
Повний текст джерелаTörnqvist, Martin. "Strukturerat låtskrivande : ett undersökande arbete om låtskrivande." Thesis, Kungl. Musikhögskolan, Institutionen för musik, pedagogik och samhälle, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kmh:diva-2253.
Повний текст джерелаRodrigues, Joaquim Carlos Mendes. "Relatório de estágio no Arquivo da Faculdade de Engenharia da Universidade do Porto : tratamento arquivístico do acervo documental do Departamento de Engenharia Electrónica e de Computadores, com recurso à aplicação informática para gestão integrada de sistemas de arquivo (GISA)." Master's thesis, Universidade de Évora, 2009. http://hdl.handle.net/10174/21053.
Повний текст джерелаDias, Ricardo Rodrigues. "Preparação e caracterização de eletrocatalisadores PtRu, PtSn, PtRh, PtRuRh e PtSnRh para oxidação direta de álcoois em células a combustível tipo PEM utilizando a metodologia da redução por álcool." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-08092009-172849/.
Повний текст джерелаIn this work, Pt/C, PtRh (90:10), PtRh/C (50:50), PtSn/C (50:50), PtRu (50:50)/C, PtRuRh/C (50:40:10) and PtSnRh/C (50:40:10) were prepared by an alcohol-reduction process with metal loading of 20 wt.% using H2PtCl6.6H2O (Aldrich), SnCl2.2H2O (Aldrich),and RhCl2.XH2O (Aldrich) as metals sources and Vulcan XC72 as support. The electrocatalysts were characterized by EDX, XRD and cyclic voltammetry (CV). The electro-oxidation of ethanol was studied by CV, chronoamperomety at room temperature in acid medium and tests at 100 0C on a single cell of a direct methanol or ethanol fuel cell. The EDX analysis showed that the metal atomic ratios of the obtained electrocatalysts were similar to the nominal atomic ratios used in the preparation. The diffractograms of electrocatalysts prepared showed four peaks at approximately 2 =400, 470, 670 and 820, which are associated with the (111), (200), (220) and (311) planes, respectively, of a face cubic-centered (fcc) structure characteristic of platinum and platinum alloys. The average crystallite sizes using the Scherrer equation and the calculated values were in the range of 23 nm. For PtSn/C and PtSnRh/C two additional peaks were observed at 2 = 340 and 520 that were identified as a SnO2 phase. PtSn/C (50:50) and PtSnRh/C (50:40:10) electrocatalyst showed the best performance for ethanol oxidation at room temperature. For methanol oxidation at room temperature PtRu/C, PtSn/C and PtRuRh/C electrocatalysts showed the best performance. Tests at 100 0C on a single cell of a direct ethanol fuel cell PtSnRh/C showed the best performance, for methanol oxidation PtRuRh/C showed the best performance.
Bring, Hedda. "A Digital Elevation Model of the Lövåsen Esker." Thesis, University of Gävle, Department of Technology and Built Environment, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-234.
Повний текст джерелаThe threats imposed by the ongoing climate change become successively more clear. In the municipality of Sandviken the possible rise in water level in the lake Storsjön might cause major problems. This study aims to produce an elevation model over one of the threatened areas so that the effect of different water levels in the lake can be studied in the future.
The area of study consists of an esker cutting straight through the lake Storsjön. The area is densely populated and the size is about 13 hectares.
Measurements were performed, both with GPS, utilizing Network-RTK, and with total station. The formations of the ridge were captured by following the breaklines with a point density of 225 points/ha as an intended goal.
The GPS measurements were transformed into the local coordinate system of Sandviken municipality. The measured coordinates for six control points were compared to the true coordinates. The fit was not perfect, so a Helmert transformation was performed on the plane coordinates. The accuracy of the measurements was below 50 mm after the transformation. Net adjustments in plane and height were performed on the total station measurements. The error ellipses for the station points varied from 2 to 44 mm. The over all point density achieved was 274 points/ha.
Two elevation models were created, one Triangular Irregular Network (TIN) and one interpolated model using a kriging interpolation. Contour lines from both models were produced and compared with each other. The TIN creates a more angular surface and therefore the contour lines are not as smooth as in the interpolated model. Both models showed good resemblance compared with the original data.
Problem relaterade till klimatförändringar blir alltmer uttalade. I Sandvikens kommun kan problem uppstå om vattennivåerna i Storsjön stiger. Syftet med det här examensarbetet var att skapa en höjdmodell över ett av de utsatta områdena för att effekter av en eventuell vattennivåhöjning skall kunna studeras i framtiden.
Området består av en rullstensås som sträcker sig rakt igenom Storsjön. Området är tättbefolkat och ca 13 hektar stort.
Mätningarna utfördes med både GPS och totalstation. Vid GPS-mätningarna utnyttjades Nätverks-RTK. Åsens formationer fångades genom att följa brytlinjer med en estimerad punkttäthet på 225 punkter/ha.
GPS-mätningarna transformerades till Sandvikens lokala koordinatsystem. De mätta koordinaterna för sex kontrollpunkter jämfördes med de sanna koordinaterna. Eftersom de mätta värdena inte passade in perfekt så utfördes en Helmerttransformation av plankoordinaterna. Noggrannheten på mätta värden var inom 50 mm efter transformationen. Nätutjämningar i plan och höjd gjordes på totalstationsmätningarna. Felellipserna för stationspunkterna varierade mellan 2 och 44 mm. Den sammanlagda punkttätheten uppgick till 274 punkter/ha.
Två höjdmodeller framställdes, en TIN-model (Triangular Irregular Network) och en interpolerad model där interpolationsmetoden kriging användes. Höjdkurvor framställda från respektive modell skapades och jämfördes med varandra. Ett TIN ger en mer kantig yta vilket återspeglas i höjdkurvorna som inte är lika jämna som de från den interpolerade modellen. Båda modellerna visade god överensstämmelse med originaldata.
Deml, Karl-Friedrich [Verfasser], and Jens [Akademischer Betreuer] Schlossmann. "Interaktionen von Histamin H1-Rezeptoragonisten und –antagonisten mit dem humanen Histamin H4-Rezeptor / Karl-Friedrich Deml. Betreuer: Jens Schlossmann." Regensburg : Universitätsbibliothek Regensburg, 2012. http://d-nb.info/1023362104/34.
Повний текст джерелаKattirtzi, Michael. "'Challenge and be challenged' : a history of social research capacity and influence in DEFRA and DECC, 2001-2015." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/23492.
Повний текст джерелаSILVA, F. N. A. "Representação política e seus meandros: percepções da relação entre eleitos e eleitores." Universidade Federal do Espírito Santo, 2016. http://repositorio.ufes.br/handle/10/4354.
Повний текст джерелаAnálise da representação política centradanos elementos que constituem os laços conectivos entre representantes e representados. A partir dos objetivos de compreender o fenômeno político da representação e suas formas de desenvolvimento investigou-se a relação entre eleitos e eleitores e seus meandros, com o intuito de saber se a representação acontece ou se vive uma crise, na qual a responsividade de uma parte a outra não ocorre ou não se efetiva. Iniciada com abordagem teórica da representação política, são trazidas as abordagens e aferições dos autores da Política acerca do tema. Feita a apreciação teórica, a representação enquanto fenômeno político é analisada a partir do estudo de três fenômenos que ocorrem em seu bojo: as eleições, o papel dos partidos políticos e a ação dos meios de comunicação de massa. Com a compreensão desses três elementos, suas relações e influências na representação política, buscou-se diagnosticar como o fenômeno se desenvolve e se o mesmo vive um momento de crise ou de redefinição de suas formas de relação. No momento seguinte lança-se mão da pesquisa empírica e a utilização dos resultados obtidos com entrevistas realizadas com ex-representantes que pertenceram ao Poder Legislativo Estadual e membros da sociedade civil organizada capixaba, servindo os resultados obtidos de exemplo para atestar as exposições teóricas e nortear a conclusão acerca da representação no que tange a seu desenvolvimento, à caracterização de suas relações e sua efetividade. Como conclusão apresenta-se os novos caminhos que a representação política passa a traçar na atualidade, como consequência da modificação das formas de comunicação, que expõe outras alternativas além dos meios de mídia de massa, bem como o declínio do papel dos partidos políticos nas relações de intermediação entre o candidato/político e seus eleitores, e a força do capital. A compreensão que se chega do fenômeno da representação política na atualidade é de um quadro de mudanças e adequações, a partir das novas realidades que se apresentam nas relações sociais e políticas, que expõem uma ligação entre representantes e representados que se mantem. E apesar das sinuosidades que se impõem a partir da força do capital e da desigualdade social promovida pela realidade estratos dominantes e dominados, os novos caminhos da representação política apontam pelo perdurar da conexão e responsividade entre mandatários e mandantes, afastando uma ideia de crise.
André, Damien. "Modélisation par éléments discrets des phases d’ ébauchage et de doucissage de la silice." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14501/document.
Повний текст джерелаWhen fused silica optics are submitted to high-power laser (such as megajoule laser or National Ignition Facility) at the wavelength of 351 nm, fused silica optics can exhibit damage, induced by the high amount of energy traversing the part. Current researches have shown that this damage could be initiated on pre-existing sub-surface damages created during the polishing processes. The discrete element method (DEM) is proposed to simulate the polishing process and its impact on sub-surface damage creation
Montane, Juana Maria. "Geophysical Analysis of a Central Florida Karst Terrain using Light Detection and Ranging (LIDAR) and Ground Penetrating Radar (GPR) Derived Surfaces." FIU Digital Commons, 2001. http://digitalcommons.fiu.edu/etd/42.
Повний текст джерелаWonkovich, Mark A. "Evaluation of High-resolution Digital Elevation Models For Creating Inundation Maps." Bowling Green State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1167945221.
Повний текст джерелаOuvrier-Buffet, Patrice. "Modifications physiologiques chez le coureur de demi-fond au cours d'une saison d'entrainement." Clermont-Ferrand 2, 1994. http://www.theses.fr/1994CLF22517.
Повний текст джерелаSaha, Kakoli. "Object-Oriented classification of drumlins from Digital Elevation Models." Kent State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=kent1289558937.
Повний текст джерелаRigueira, Siqueira Fábio. "Soberania em xeque?: a arbitragem internacional privada como método alternativo de resolução de disputas comerciais : um estudo político do caso brasileiro." Universidade Federal de Pernambuco, 2003. https://repositorio.ufpe.br/handle/123456789/1705.
Повний текст джерелаJulgamentos privados de conflitos comerciais entre empresas brasileiras e estrangeiras é mais uma marca da evolução das trocas comerciais entre as nações. Faz parte da constituição de uma nova ordem para o comércio mundial que vem pregando a doutrina do livre comércio entre empresas que negociam suas mercadorias em um mundo globalizado. Uma política voltada para incitar a participação privada na resolução dos conflitos comerciais, através da arbitragem comercial, deu ao governo brasileiro a oportunidade de contribuir com o esforço das pressões internas representadas pelo setor da indústria e comércio, bem como a pressão internacional da UNCITRAL, órgão da ONU (Organização das Nações Unidas). Contudo, a pesquisa notou que a soberania nacionalista brasileira ainda é o principal entrave institucional ao incremento da arbitragem comercial internacional. Mediante uma abordagem crítica registra-se o valor simbólico e conservador da soberania nacional
Fakih, Mahmoud. "Modélisation numérique discrète de la croissance racinaire dans un sol : relation force-forme." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT323/document.
Повний текст джерелаPlant roots play an important role in the growth and development of plants, and it is well known that the mechanical interactions between a growing root and the surrounding soil can have a major impact on root growth and consequently on plant biomass production. These mechanical interactions are one of numerous factors that explain the variability of root architecture, including genetics, environment and developmental instability. But this factor has often been under-estimated. I hypothesize that the heterogeneous structure of soil at the particle scale, demonstrated by the broad distribution of forces, can significantly influence root growth trajectories. This thesis aims at determining how grains in granular soils are reorganized under the action of growing roots, and in return how the resulting forces acting on root tips modify their development, including the kinematics of their trajectories, in order to develop a general biophysical law of root-soil mechanical interactions. I developed a 2D numerical model of root growth in a granular medium using a Discrete Element Model (DEM). The model is able to compute grain-grain and root-grain contact forces within a granular medium. The root system is modelled using chains of connected spheroline elements. The orientation of root growth at every growth step is determined by the dynamics of the whole root under the action of its internal elastic forces and reaction forces exerted by the grains, which are the mechanical interactions that control numerical growth in the model.Parametric studies were carried out in order to (i) estimate the influence of granular structure (grain diameter distribution, cohesion, volume fraction) and root mechanical properties (root bending stiffness) on the axial force signal acting on the root tip, and on the root trajectories and (ii) define general physical laws that can be used further to analyze experimental data. The distribution curves of computed root tip-grain forces normalized by the mean force during a given period of growth were characterized by a decreasing power law for forces below the mean force, and an exponential fall-off for forces above the mean force, thus reflecting the broad distribution of forces inside the granular material. An analysis of the standard deviation of the local deformations of root trajectories resulted in two different regimes with regard root stiffness. In the first regime, soil controlled the root deformation and in the second, the root trajectory was straighter and displaced more significantly the surrounding grains during growth
Telò, Mario Eupolis. "Eupolidis Demi /." Firenze : Le Monnier, 2007. http://www.loc.gov/catdir/toc/casalini06/07585616.pdf.
Повний текст джерелаSingh, Nachatter. "Indian diaspora to Spain demo-spatial analysis and immigrant integration." Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/666821.
Повний текст джерелаDuring the last two decades, accelerated globalization and neoliberal economic policies have facilitated the rapid movement of capital and people around the world. Large-scale migration of people from the developing world (for example, India, which is the largest supplier of labour) to developed countries, the growing contribution of the migrant population in the development of countries of origin and the role played by the diaspora population in global politics has revived the importance of "diasporas" in academic debates and international relations. At present, there is no single source of data that can provide accurate information about all the people or their descendants that make up the diaspora population. In the first part of this dissertation, I focused on the Indian diaspora. First, I analysed different data sources that can be used to measure the size of the diaspora population and the expansion of the current space of the Indian Diaspora, which according to the Indian government has more than 30 million people living in 208 countries. Secondly, I studied the evolution of different diasporas in comparison to each other and the effect of globalization on them. By focusing on the diasporas of India and Mexico, on the one hand I explored the changing attitude of host countries towards their Diaspora population and on the other hand the impact of demographic, economic and political changes on the countries of origin in the future growth of the diaspora communities. And finally, by focusing on Indian immigration (mainly the Sikh community) to Spain, I have studied the creation of different diaspora spaces through the interrelation of immigrants and their internal mobility in the new destination countries. I have also highlighted the transcendence of transnational communication networks in the creation of virtual spaces of the diaspora, which are very dynamic and consist of different levels. Spain is a recent addition to the Indian diaspora. The immigration of Indian workers to southern Europe has elevated its position as a peripheral destination in the Indian diaspora. The second part of this dissertation focuses on the Indian immigrant population in Spain, especially on their sociodemographic profile and spatial distribution. In this part, I analysed the growth of the Indian community in Spain during the last two decades and its level of concentration and residential segregation in different metropolitan cities of Spain. I also studied the exposure of Indian immigrants to the host society and their socioeconomic status compared to other immigrant communities in Spain. The fact that the exponential increase of Indian immigration to Spain is relatively recent and the absence of historical and colonial ties between Spain and India makes this study more interesting as it gives us an opportunity to observe the expansion of the Indian diaspora to virgin territories where they do not share any common history, but now they are contributing to the formation of a very diverse society and heterogeneous neighbourhoods. In the third part of this dissertation, I examined the level of integration of Indian immigrants in different spheres of the host society and the factors responsible for it. As the Sikh population represents the majority of the Indian immigrant population in Spain, I also addressed how the different generations of Sikh immigrants in Spain face the challenge of preserving their identity and peaceful coexistence with the host society.
Del, sorbo Pietro. "Modélisation multi-échelle des tissus secs : Application à l'impact." Thesis, Paris, ENSAM, 2019. http://www.theses.fr/2019ENAM0003/document.
Повний текст джерелаThe current thesis work focused on the development of a predictive numerical model of dry fabrics under high velocity impact.A mature bibliography exists on the subject. The impact phenomenon can be essentially resumed as an energy transfer between the colliding object and the fabric layers. The correct prediction of the fabric ballistic performance by a numerical model is related to the correct representation of the fabric energy evolution and its failure dynamic. Different numerical strategies have been proposed to model a fabric under ballistic impact. Mesoscopic numerical models resulted to be the most popular since they provide a realistic representation of the phenomenon for a reasonable computational cost. This is possible thanks to the main assumption of treating yarns as continuous media.In order to represent a discrete fiber bundle as a continuum an appropriate constitutive behavior have to be formulated. The universally adopted constitutive law accurately describes yarns longitudinal properties but it is limited in the representation of their transverse mechanical behavior. Recent studies have demonstrated how this last point is intrinsically related to fabrics failure and multilayer textiles response, then its correct representation becomes a critical point for an accurate model. The goal of the current work has been to provide a new constitutive model which overcome the limitation of the classic linear elastic approach while keeping unaltered its advantages, i.e. low computational costs and accurate description of yarn longitudinal behavior.The first step of this dissertation was to quantify the yarn cross section effects over textile ballistic properties and the phenomena related to this aspect. In order to provide an answer, two microscopic numerical studies of a single Kevlar yarn transversely impacted have been presented. Results showed how yarn transverse mechanical behavior has a role in failure initialization, while its energetic contribution to the global energy balance is not negligible during the first phases of an impact. The importance of a correct representation of the yarn transverse behavior for a predictive fabric numerical model was then confirmed.Starting from the previous microscopic observations, a consistent yarn continuum model for impact applications has been proposed. An hyperelastic formulation previously developed for static applications has been extended to impact analyses and a novel multiscale approach for the determination of all the material parameters has been introduced. The validation of the hyperelastic approach has been performed comparing the results with those obtained at the microscale. Compared to the classical approach, the introduced constitutive law is actually able to reproduce the evolution of the yarn cross section during the impact while keeping a correct representation of the yarn longitudinal properties. Moreover, the proposed formulation provides new physical measurement to exploit the physic behind the impact and new possibilities in terms of failure modelisation.In the final part of the dissertation, the proposed yarn continuum model is introduced at the fabric level. Results confirmed the observation performed at the yarn level. The proposed hyperelastic approach is able to correctly represent the impact dynamic and fabric energies trends. Moreover, it provides more stability and a better representation of the fabric failure compared to linear elastic approach. The proposed hyperelastic constitutive law and the linear elastic one can be adopted for different portion of the same yarn without occurring into model instabilities and providing accurate results.The yarn mesoscopic model developed in the current work offers new possibilities in terms of failure modelisation and post processing tools. These could be used to develop more accurate fabric model and exploit the phenomena behind fabrics and yarns failure mechanic
Zhou, Yu. "Simulation of High-velocity Penetration for Rigid Projectile into Plain Concrete Target using Discrete Element Method." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/31325.
Повний текст джерелаMaster of Science
Zach, Christine. "Die Erzählmotive der "Crône" Heinrichs von dem Türlin und ihre altfranzösische Quellen : ein kommentiertes Register /." Passau : Wissenschaftsverl. R. Rothe, 1990. http://catalogue.bnf.fr/ark:/12148/cb36658969n.
Повний текст джерелаGutwald, Thomas. "Schwank und Artushof : Komik unter Bedigungen höfischer Interaktion in der "Crone" des Heinrich von dem Türlin /." Frankfurt am Main : Peter Lang, 2000. http://catalogue.bnf.fr/ark:/12148/cb39940375q.
Повний текст джерелаKaiser, Isabel. "Urlaub auf dem Bauernhof : Erlebnisse aus dem Blickwinkel der Wissenschaft /." Hamburg : Diplomica-Verl, 2009. http://deposit.d-nb.de/cgi-bin/dokserv?id=3185288&prov=M&dok_var=1&dok_ext=htm.
Повний текст джерелаBoulangé, Guillaume. "Jacques Demy dispersé : Essai de généalogie artistique raisonnée." Montpellier 3, 2007. http://www.theses.fr/2007MON30007.
Повний текст джерела“ A film is unavoidably a palimpsest” How does a film director inherit ? By which means and what procedures ? To what ends ? A concept such as influence has always been commonly used in all types of arts, but it has rarely been studied itself. The author of Lola, in spite of his unjustified reputation of being a rejected artist, proves to be on the contrary a perfect example in the realm of comparative cinema. Studying his artistic genealogy reveals surprising ancestors and sons. That survey highlighted four different factors as key points in the research and analysis of the different loans, traces or hints of connections to Demy’s works. Key factors that were picked over 80 years of artistic creation allow us to understand the cultural and spiritual basis of a certain community. Firstly returning to the beginning of his works to illustrate the complex relationship that Jaques Demy has with cinema and transmission. Next dissect the signs of his “fraternal” love with wife and fellow film maker Agnès Varda through his movies. Next is looking at his subtle but problematical influence on a few of Nouvelle Vague’s chosen companions. Finally list the miscellaneous forms of his legacy and work out what motivated those who claim being Demy’s heirs. What does one learn from this study of Jaques Demy’s talent and more-over the way his films have been an influence ? We will realise that claiming a filiation with Demy is never disinterested, anything from respect to iconoclasty, but it is first a way to assert one’s identity. Isn’t it the demonstration that his life works must be ranked among masterpieces ?
Deml, Barbara. "Telepräsenzsysteme Gestaltung der Mensch-System-Schnittstelle /." [S.l.] : [s.n.], 2004. http://137.193.200.177/ediss/deml-barbara/meta.html.
Повний текст джерелаMaione, Riccardo. "Modélisation d’un système de pyrogazéification de la biomasse." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0088/document.
Повний текст джерелаThis work is part of the LORVER project, funded by Grand Est Région and FEDER. It aims to create a non-food biomass production chain by using and upgrading brownfields and industrial by-products in Lorraine. One possible valorization process of the produced biomass is a thermochemical pyro-gasification process that would generate heat and electricity. This process, developed by SEA Marconi, involves three different reactors: a rotating drum, for the pyrolysis of wood particles, the heat required being brought by hot steel balls; an Auger for partial oxidation of the char that allows heating the steel balls; a reactor for tar cracking. The aim of this thesis is to develop models that can predict the behavior of the system. 3D models based on DEM or CFD - DEM were designed for the modeling of phenomena involved in the system. The DEM model parameters were first calibrated in a rotating drum. The DEM simulation was able to predict in a satisfactory manner segregation between steel balls and non-spherical wood particles; it also helped to design a 1D thermal and chemical model, on which a sensitivity study has been done. A CFD - DEM model has been coded and validated on a granular rheometer allowing the simulation of the char oxidation reactor, even if this simulation was not possible during the PhD
Aouina, Nizar. "Réduction électrochimique des ions nitrate et nitrite sur électrode de cuivre, en milieu neutre: Apport à la compréhension du mécanisme réactionnel." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2010. http://tel.archives-ouvertes.fr/tel-00462788.
Повний текст джерелаLiekis, Paulius. "Realaus laiko vizualizaciniai metodai demonstracinėse programose." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2005. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2005~D_20050530_120410-12537.
Повний текст джерелаAouina, Nizar. "Réduction électrochimique des ions nitrate et nitrite sur électrode de cuivre, en milieu neutre : apport à la compréhension du mécanisme réactionnel." Paris 6, 2009. http://www.theses.fr/2009PA066323.
Повний текст джерелаШматько, Наталія Михайлівна. "Методичне забезпечення підтримки організаційно-комунікаційної стійкості об'єднання промислових підприємств". Thesis, Центр фінансово-економічних наукових досліджень, 2019. http://repository.kpi.kharkov.ua/handle/KhPI-Press/40879.
Повний текст джерелаMazon, Correa Alves Gustavo. "EFFECTS OF YEAST-DERIVED MICROBIAL PROTEIN ON TRANSITION DAIRY COW HEALTH AND PERFORMANCE." UKnowledge, 2019. https://uknowledge.uky.edu/animalsci_etds/103.
Повний текст джерелаSilva, Wanderson Oliveira da. "ELETROCATÁLISE DA OXIDAÇÃO DE ETANOL SOBRE CATALISADORES À BASE DE PtSnO₂: UM ESTUDO DE DEMS." Universidade Federal do Maranhão, 2013. http://tedebc.ufma.br:8080/jspui/handle/tede/964.
Повний текст джерелаConselho Nacional de Desenvolvimento Científico e Tecnológico
The ethanol oxidation reaction was investigated using on line differential electrochemical mass spectrometry (DEMS) on carbon-supported Pt-SnO2 electrocatalysts at atomic ratio 1:1, 2:1 and 3:1 as a function of ethanol concentration and combined analysis of the reaction products and electrochemical measurements. The materials were prepared by two methods: impregnation/thermal decomposition with and without chemical reduction via sodium borohydride. They were characterized by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) techniques. A comparative study showed that the second method was more efficient to synthesize of these materials, which were chosen for DEMS and electrochemistry studies. Electrochemical measurements showed better faradaic current in lower potentials, indicating better activity to ethanol oxidation on PtSnO₂/C, Pt₂SnO₂/C and Pt₃SnO₂/C catalysts compared to Pt/C E-TEK. Pt/C E-TEK presented the best ratio between the CO₂ and acetaldehyde production in 0.01 mol Lˉ¹ ethanol, showing that this electrode favors the reaction via CO₂ production. When the ethanol concentration is increased, the ratio CO₂ /acetaldehyde decreases for all catalysts studied, mainly for Pt/C E-TEK. This increasing formation of acetaldehyde was largely responsible for the profile of faradaic currents in view of the onset for the formation of acetaldehyde to coincide with the beginning of the ethanol oxidation reaction. In general, the catalysts based on Pt-SnO₂ showed better performances for the ethanol reaction compared to Pt/C E-TEK, thus confirming the ability of SnO₂ to provide oxygen species for oxidize adsorbed intermediates such as CHx and OHads, at lower potentials.
A reação de oxidação de etanol foi investigada usando a espectrometria de massas eletroquímica diferencial on line (DEMS), sobre eletrocatalisadores de Pt-SnO₂ suportados em carbono Vulcan, com razão atômica 1:1, 2:1 e 3:1 em função da concentração de etanol e análises combinadas dos produtos reacionais e medidas de corrente eletroquímica. Os materiais foram preparados por dois métodos: impregnação/decomposição térmica com e sem redução química via borohidreto de sódio. Eles foram caracterizados pelas técnicas de energia dispersiva de raios X (EDX) e difratometria de raios X (DRX). Um estudo comparativo mostrou que o segundo método foi mais eficiente na síntese desses materiais, sendo escolhido para os estudos eletroquímicos e de DEMS. As medidas eletroquímicas mostraram melhores correntes faradáicas em menores potencias, indicando melhor atividade para a oxidação de etanol sobre os catalisadores PtSnO₂/C, Pt₂SnO₂/C e Pt₃SnO₂/C comparado com Pt/C E-TEK. A Pt/C E-TEK apresentou a melhor razão entre CO₂ e acetaldeído em etanol 0,01 mol Lˉ¹, mostrando que esse eletrodo favorece a via de formação de CO₂. Quando a concentração de etanol é aumentada, a razão CO₂/acetaldeído diminui para todos os catalisadores estudados, principalmente Pt/C E-TEK. Esse aumento na formação de acetaldeído foi o grande responsável pelo perfil de corrente faradáica, tendo em vista o início da reação de formação do acetaldeído coincidir com o início da reação de oxidação de etanol. Em geral, os catalisadores à base de Pt-SnO₂ apresentaram melhor desempenho para a reação de oxidação de etanol em relação a Pt/C E-TEK, confirmando assim a capacidade do SnO₂ em fornecer espécies oxigenadas para oxidar intermediários adsorvidos tais como CHx e OHads, em potenciais mais baixos.
Vadluga, Vaidas. "Simulation of dynamic deformation and fracture behaviour of heterogeneous structures by discrete element method." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20080213_082157-83281.
Повний текст джерелаTyrimų sritis ir darbo aktualumas. Kuriant modernias ��vairios paskirties mechanines sistemas, technologijas ir įrangą, svarbiomis tampa jas sudarančios medžiagos. Savaime suprantama, kad žinomos ir naujai kuriamos medžiagos dabar kur kas išsamiau nagrinėjamos daugelyje mokslo šakų, įskaitant ir me-džiagų mechaniką. Visos medžiagos mezo- ir mikrostruktūros požiūriu yra ne-vienalytės. Jų mikroskopinės savybės skirtingos, lyginant su įprastu kontinuu-mu. Medžiagų savybėms tirti dažniausiai taikomi eksperimentiniai metodai. Eksperimentiniais metodais ištirti medžiagos struktūras ir jose vykstančius procesus ir įvertinti tam tikras jų savybes labai brangu. Tai viena priežasčių, kodėl skaitinis modeliavimas tampa realia tyrimų alternatyva. Skaitinį eksperi-mentą galima kartoti daug kartų, valdant bandinio parametrus, išlaikant tas pa-čias sąlygas, ir stebėti reiškiniui būdingus rodiklius visame tūryje. Šiuolaikiniai modeliavimo metodai yra kompleksiniai. Jie jungia fenome-nologines ir statistines idėjas, o matematiniai modeliai sudaromi taikant konti-nuumo mechanikos ir jų diskrečiųjų modelių bei molekulinės dinamikos pri-klausomybes. Diskrečiųjų elementų metodas (DEM) taip pat priskiriamas šiuo-laikinių metodų kategorijai. Jis skirtas kontaktuojančių dalelių sistemų dinami-niam modeliavimui. Kintanti dalelių sistemos topologija – būdingas metodo požymis. Pastaruoju metu DEM jau taikomas kontinuumui modeliuoti ir praktikoje aktualiems irimo uždaviniams spręsti. Reikia pastebėti... [toliau žr. visą tekstą]
Santos, Suelen Silvana dos. "Direcionamento de antígenos para células dendríticas in vivo: uma nova estratégia para o desenvolvimento de vacina na paracoccidioidomicose." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/9/9136/tde-27052015-115437/.
Повний текст джерелаParacoccidioidomycosis (PCM) is the most common systemic mycosis in Brazil. In the last decade, it was demonstrated that antigens can be directly target to the dendritic cells using the antibody αDEC205 in the presence of a maturation stimulus, resulting in the induction of a strong immune response. We found that αDEC205 antibody fused to peptide P10 induced great response by IFN-γ producing cells after a single dose in relation to the administration of P10, although it has been administered in a lower concentration. However, this response was not maintained after second dose of antibody. Animals challenge with P. brasiliensis, after immunization with two doses of the chimeric antibody, produced high levels IFN-γ and IL-4 in lung tissue significantly higher in αDEC/P10 group in relation to the administration of P10, all in the presence of Poly I:C. In therapy assays, we found in the lungs of mice treated with the chimeric antibody, the main organ involved in an animal model of PCM, low concentration of IFN-γ and IL-10 compared to controls. In addition, it became evident that animals treated with αDEC/P10 antibody have a lung tissue much closer to that of non-infected tissue, while in the absence of suitable treatment we find clusters of yeasts and tissue filled with cellular infiltrates. Altogether, these findings show a clinical improvement in treated animals and indicate that targeting of P10 through the chimeric antibody αDEC/P10 in the presence of Poly I:C, is a promising strategy for therapy against P. brasiliensis.
Silva, Dionisio Furtunato da. "Preparação de eletrocatalisadores PtRu/C e PtSn/C utilizando feixe de elétrons para aplicação como anodo na oxidação direta de metanol e etanol em células a combustível de baixa temperatura." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-23092011-155927/.
Повний текст джерелаPtRu/C and PtSn/C electrocatalysts were prepared using electron beam irradiation. The metal ions were dissolved in water/2-propanol and water/ethylene glycol solutions and the carbon support was added. The resulting mixtures were irradiated under stirring. The effect of water/ethylene glycol and water/2-propanol (v/v) ratio, Pt:Ru and Pt:Sn atomic ratios, the irradiation time and dose rate were studied. The obtained materials were characterized by Energy dispersive analysis of X-rays (EDX), X-ray diffraction (XRD), cyclic voltammetry (CV) and Mössbauer spectroscopy. The electro-oxidation of methanol and ethanol were studied by cyclic voltammetry and chronoamperometry using the thin porous coating technique. The electrocatalysts were also tested on the Direct Methanol and Ethanol Fuel Cells. PtRu/C electrocatalysts prepared in water/ethylene glycol showed Pt:Ru atomic ratios different from the nominal ones. The results suggested that part of the Ru(III) ions were not reduced. The obtained materials showed the face-centered cubic (fcc) structure of Pt and Pt alloys with crystallite sizes of 2-3 nm. PtRu/C electrocatalysts prepared in water/2-propanol showed Pt:Ru atomic ratios similar to the nominal ones. The obtained materials also showed the fcc structure of platinum and platinum alloys with crystallite sizes of 3-4 nm. PtSn/C electrocatalysts prepared in water/ethylene glycol and water/2-propanol showed Pt:Sn atomic ratios similar to the nominal ones. The obtained materials showed the platinum (fcc) phase with crystallite sizes in the range of 2 - 4 nm and a SnO2 (cassiterite) phase. The obtained PtRu/C and PtSn/C electrocatalysts showed similar or superior performance for methanol and ethanol electro-oxidation compared to commercial PtRu/C (E-TEK) and PtSn/C (BASF) electrocatalysts.
Spring, Ted. "Uncertainty comparison of Digital Elevation Models derived from different image file formats." Thesis, Högskolan i Gävle, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-17193.
Повний текст джерелаGupta, Prashant. "Verification and validation of a DEM-CFD model and multiscale modelling of cohesive fluidization regimes." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10449.
Повний текст джерелаKrewson, Corey Nicholas. "Near Real-Time Flood Forecasts from Global Hydrologic Forecasting Models." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7476.
Повний текст джерелаMaciel, Karina Almeida. "Fatores de virulência de escherichia coli isoladas de aves abatidas no estado do Tocantins." Universidade Federal do Tocantins, 2016. http://hdl.handle.net/11612/555.
Повний текст джерелаThe poultry sector plays an important role in the Brazilian economy. With the intensification of poultry production comes the need for tools to assist in the correct detection of microrganisms responsible for production losses. Tocantins to own land available and weather conditions such as heat and humidity that enhance the production of this species, also favors the proliferation of pathogens, requiring early diagnosis. Escherichia coli (E. coli) is a Gram-negative bacteria found in the normal microflora of farm animals. However, there are pathogenic species which are responsible for production losses in poultry due to problems such as sentences during slaughter. Currently, these strains are separated into categories according to their virulence factors responsible for the pathogenesis mechanisms, both animal and human. The virulence factors ranging from the release of toxins to the presence of specific genes which provide for the pathogenesis in the host. The correct identification of each category of the bacteria through detecting the presence of virulence factors with the aid of molecular biology plays a critical role in possible decisions prophylaxis and improvement of handling, in order to minimize production losses. Currently, there are few studies that identify intestinal extra injuries caused by poultry E. coli diarrheagenic, so the aim of this study was to demonstrate the association of diseases in poultry with pathotypes of E. coli commonly found in mammals.
Jurca, Ciprian Bogdan. "Synthèse et caractérisation de pérovskites doubles magnétorésistives dérivées de Sr2FeMoO6." Paris 11, 2004. http://www.theses.fr/2004PA112275.
Повний текст джерелаThis work is devoted to the synthesis and physico-chemical characterization of Sr2FeMoO6, Sr2FexM02-xO6 (x = 0. 9-1. 33) and Sr2FeCrxMo1-xO6 (x = 0. 1-0. 25) double perovskites. For Sr2FeMoO6 the solid state synthesis conditions influence the microstructure of the samples and the Fe/Mo order. Successive sintering treatments with intermediate grindings improve the saturation magnetization (3. 8 µB) which became close to the ideal value (4 µB) and the low field magnetoresistance (LFMR) from 1. 58±0. 14 % to 2. 74±0. 01 % (T = 300 K, H = 1 kOe) as a consequence of microstructural changes. The effective magnetic moment values depict the presence of mixed valency states: FeII/MoVI and FeIII/MoV. The Sr2FexMO2-xO6 solid solutions (tetragonal symmetry or cubic for x > 1. 2) are stable for a larger excess of iron than of molybdenum. The Fe/Mo order diminishes when the difference between x and 1 becomes larger and is stabilizing to an equilibrium value alter a high number of sintering treatments for a given x. The Tc arises with x (Fe-Fe couplings stronger than Fe-Mo), but the saturation magnetization is maximum for x = 1. The resistivity enhances with x (delocalized electrons come from molybdenum) presenting thus a stronger dependence of the chemical composition than the microstructure. The magnetoresistance is maximum for x = 1 ; for x = 1. 33 the composition ceases to be a half-metal. For Sr2FeCrxM01-xO6 solid solutions, the increase of chromium content determines the diminution of octahedral sites cationic order and thus a decrease of Tc, magnetization and magnetoresistance
Costa, Márcio Leonardo Monteiro. "Modelos de circulação do mp3-demo através da internet: um estudo de caso sobre música independente no Maranhão." Universidade Federal de Pernambuco, 2008. https://repositorio.ufpe.br/handle/123456789/2971.
Повний текст джерелаEste trabalho analisa o fenômeno da circulação de música independente através da internet a partir da popularização do formato mp3 como padrão de compartilhamento. A dissertação está dividida em duas partes, sendo a primeira, marcada por uma problematização a respeito do novo ambiente comunicacional e suas implicações sobre a livre troca de conteúdos, complementada por uma descrição da situação dos artistas autônomos face às reconfigurações pelas quais passa a indústria da música. Na segunda parte, tomando como opção metodológica o estudo de caso, descreve-se o funcionamento dos espaços mais representativos da internet onde se observa a difusão do mp3-demo. Adotam-se como corpora da pesquisa artistas maranhenses que fazem uso destes espaços visando maior divulgação de seu trabalho. Como resultado, avaliamos as mudanças na cadeia produtiva da música e seus reflexos sobre os modelos autônomos de produção, circulação e consumo
Tsuruta, Naoki. "Improved Particle Method with High-Resolution and Computational Stability for Solid-Liquid Two-Phase Flows." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188536.
Повний текст джерелаNäslund, Allan. "Webbsida och demo-EP." Thesis, Blekinge Tekniska Högskola, Sektionen för teknokultur, humaniora och samhällsbyggnad, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-1475.
Повний текст джерелаThe purpose of this bachelor exam project was to compile a promo package consisting of a website and demo EP with suitable graphic design. The EP has three tracks of electro acoustic instrumental music of varying character, as well as stylistically pure yet suggestive cover artwork. The website is a presentation of myself and my work (not just music), and was built using HTML, PHP, CSS and MySQL.
Detta är en reflektionsdel till en digital medieproduktion.
Terreros, Iñigo. "Modélisation DEM thermo-mécanique d'un milieu continu. Vers la simulation du procédé FSW." Phd thesis, Ecole nationale supérieure d'arts et métiers - ENSAM, 2013. http://pastel.archives-ouvertes.fr/pastel-00996971.
Повний текст джерелаKneib, François. "Force moyenne et fluctuations subies par un obstacle indéformable soumis à l’écoulement confiné d’un milieu granulaire." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI024/document.
Повний текст джерелаThe existing studies dealing with the design of civil-engineering structures against snow avalanches are generally based on force times series that are smoothed over time. However the strong heterogeneity of snow leads to systematic observations of a high level of force fluctuations. This PhD thesis aims at characterizing the force fluctuations exerted on an obstacle that is overflowed by a granular flow. Numerical simulations based on the discrete elements method are implemented to model the interaction between the snow, represented by an assembly of spherical particles, and a rigid motionless wall-like obstacle. A key feature of this work is the broad range of flow regimes investigated, from quasistatic to collisionnal. Two model systems are studied in order to focus on a zone restricted to the upstream of the obstacle, and to allow a full control of the macroscopic flow variables (shearing velocity, confinement pressure, system sizes). The first one confines the grains between four walls from which the top one imposes a constant shearing velocity while the force signals are measured on the wall facing the corresponding displacement. The second system confines the grains between a static bottom wall, a shearing top wall, and a periodic boundary condition in the shear direction, while the wall-like obstacle is fully immersed in the grains. Each system is studied through a time-averaged analysis then the fluctuations are characterized from the instantaneous force time series.The macroscopic inertial number built from the shear velocity and the confinement pressure imposed to the system turns out to be the main control variable of both the mean dynamics and the fluctuations in the systems. An empirical law has been established to predict the mean force transmission on the obstacle as a function of the macroscopic inertial number for each of the two systems, and the measurement of local strain and stress tensors revealed that the granular flow µ(I)-rheological law is respected nearly everywhere in the samples. The autocorrelations of force signals on the obstacle at the mesoscopic scale revealed the presence of a memory effect of both systems at low inertial numbers which vanishes with the transition from the quasistatic to the dense inertial flow regimes. The force distributions at three different spatial scales are also controlled by the macroscopic inertial number: for slow regimes the distributions are tightened and resemble Gaussian shapes, for fast regimes the distributions are rather exponential. Truncated log-normal probability density functions (with three parameters) have been established in order to predict empirically the force distributions on the obstacle.This work contributes to advance the knowledge on both the time-averaged and the fluctuating components of the force exerted on a wall subjected to a granular flow. The results enable to look forward with the modeling of gravity-driven systems approaching real flow conditions, thus allowing a comparison with laboratory experiments and full-scale measurements, with the aim of better designing of civil engineering structures impacted by avalanches
Marechal, Ewen. "Etude du colmatage des systèmes carburant de turboréacteurs par des suspensions denses de particules de glace." Thesis, Paris, ENSAM, 2016. http://www.theses.fr/2016ENAM0002/document.
Повний текст джерелаWater, which exists naturally in jet-engine fuel, may freeze within theaircraft fuel pipes under certain temperatures and flow rates. The ice particles released by these deposits are entrained by the flow, and clog the hydraulics downstream. The understanding of this phenomenon, highlighted by the crash of a Boeing 777 in 2008, is an important issue for the aviation industry. Therefore a device has been designed to reproduce this threat in a controlled and quantified way. Water is atomized in low temperature jet-engine fuel and the droplets crystallize. The resulting slurry clogs different kinds of perforated targets. Temperatures, flow rates and pressure drops are monitored, and the phenomenon is filmed by a high frequency camera. A model was constructed based on these observations and data from literature and feedbacks. For the fluid phase, the incompressible Navier-Stokes equations are solved within a finite volume framework. The pressure-velocity coupling is achieved using the SIMPLE algorithm and high order of accuracy thanks to the MLS method. The solid phase is simulated using discrete elements. The fluid-particle interaction is based on a porous medium approach. A CFD-DEM parallel code has been developed to run the model. The first simulations of flow through granular media are in good agreement with experimental results