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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.
521

Ecologie de Pericopsis elata (Harms) Van Meeuwen (Fabaceae), arbre de forêt tropicale africaine à répartition agrégée / Ecology of Pericopsis elata (Harms) Van Meeuwen, tree of an african tropical forest with clumped distribution

Boyemba Bosela, Faustin 24 August 2011 (has links)
Pericopsis elata is an African forestry species commercialized under the vernacular names afrormosia or assamela. It is one of the principal species commonly exploited for timber in the Democratic Republic of Congo (DRC) and in a lesser extent in Cameroon and Congo. In view of its sustainable resource exploitation, the species is in centre of numerous polemics notably in the European Union. It is one of the rare commercialized species that produce wood, since 1992, as listed in the CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) annex II specifying that “the exploitation of afrormosia necessitate the deliverance and a prior presentation of exploitation permit”. The most important reserves of afrormosia are found in DRC. This doctoral thesis presents the ecology of this particular tree and its behaviour regarding forestry exploitation. It allows to inform the international organisms such as CITES as well as the national policy-makers on the vulnerability of afrormosia and to propose appropriate measures that can avoid future unsustainable/unregulated exploitation activities/Pericopsis elata est une espèce forestière africaine commercialisée sous les noms d’afrormosia ou d’assamela. Elle est une des principales espèces exploitées pour le bois d’œuvre en République Démocratique du Congo (RDC) et dans une moindre mesure au Cameroun et au Congo. Elle est au centre de nombreuses polémiques, notamment dans l’Union européenne, en ce qui concerne la durabilité de son exploitation. C’est une des rares espèces commerciales productrice de bois d’œuvre listée, depuis 1992, dans l’Annexe II de la CITES (Convention sur le commerce international des espèces en danger d’extinction) qui spécifie que « L'exportation d'un spécimen d'une espèce inscrite à l'Annexe II nécessite la délivrance et la présentation préalables d'un permis d'exportation ». Les plus grandes réserves d’afrormosia se trouvent en RDC. Cette thèse de doctorat porte sur l’écologie de cet arbre et sur son comportement vis-à-vis de l’exploitation forestière. Elle permet d’informer les organismes internationaux comme la CITES et les décideurs nationaux sur la vulnérabilité de l’afrormosia et de proposer des mesures à prendre pour que l’espèce ne soit pas menacée par une exploitation mal conduite et non régulée / Doctorat en Sciences / info:eu-repo/semantics/nonPublished
522

Fusion de données hyperspectrales, polarimétriques et angulaires de diffusion : application au diagnostic optique de milieux denses et complexes / Data fusion system for hyperspectral, polarimetric, and angular scattering : application to optical diagnostic of dense and complex media

Ceolato, Romain 08 November 2013 (has links)
Ces travaux de recherche portent sur le développement d'un système original de fusion de données de diffusion électromagnétique et optique par des milieux denses et complexes. La méthode, à la fois théorique, numérique et expérimentale, permet la fusion des signatures de diffusion hyperspectrales, polarimétriques et angulaires d'un milieu d'étude. Un système expérimental multi-capteurs comprenant une source laser supercontinuum est présenté pour mesurer les signatures de diffusion de différentes cibles. Des modèles directs de simulation physique ont aussi été développés via : (i) une approche dite « top-down » qui modélise les signatures à partir de paramètres macroscopiques (ex. rugosité, indices optiques effectifs) ou (ii) une approche dite « bottom-up » qui modélise les signatures à partir de paramètres microscopiques (ex. distribution en taille, géométrie, concentration, indices optiques et structuration des diffuseurs) en résolvant soit l'équation de transfert radiatif ou directement les équations de Maxwell. Des méthodes inverses appliquées sur les signatures mesurées sont développées pour retrouver simultanément les paramètres d’intérêt du milieu analysé. Les avancées de ces travaux permettent une amélioration de la compréhension des phénomènes de diffusion électromagnétiques et optiques par des milieux denses et complexes tels que les surfaces rugueuses, les revêtements, les nanomatériaux, les suspensions colloïdales ou les agrégats fractals d'aérosols ultrafins. Les domaines d'applications de ces travaux sont l'aéronautique (ex. peintures d'aéronefs), l'imagerie aéroportée ou satellite (ex. imagerie active hyperspectrale ou polarimétrique), la sécurité et la défense (ex. matériaux pour la furtivité) ou bien les sciences de l'atmosphère (ex. systèmes LiDAR, suivi de pollution, suies), l'industrie chimique (ex. suspensions colloïdales) ou le biomédical (ex. diagnostic de tumeurs et mélanomes). / This work reports the development of an original data fusion system dedicated to electromagnetic and light scattering by dense and complex media. The dissertation encompasses the theoretical, numerical and experimental studies. The output of the data fusion system is a fused hyperspectral, polarimetric and angular scattering signature. An experimental multi-sensor and supercontinuum laser-based system is presented to measure the scattering signatures for various targets. Direct physical simulation models were developed using a two-level modelling scheme: (i) a top-down approach is used to model signatures from macro-physical parameters, e.g. the surface roughness or the effective refractive index and, (ii) a bottom-up approach is used to model signatures from microphysical parameters, e.g. the size distribution, the geometry, the concentration, the refractive index and the structuration of the scatterers, by solving the radiative transfer equation or directly the Maxwell's equations. Inversion schemes are deployed to retrieve these parameters by inverting the experimental signatures. The advancements described throughout this dissertation will serve to improve understanding of electromagnetic and light scattering by dense and complex media such as rough surfaces, coatings, nanomaterials, colloidal suspension and fractal aggregates of ultrafine aerosols. This study has relevant applications in fields as diverse as aeronautics (e.g. aircraft paint coatings), remote-sensing (e.g. hyperspectral, polarimetric, active or passive imaging), security and defense (e.g. furtive materials), atmospheric science (e.g. black carbon or soot characterization, LiDAR systems), chemical engineering (e.g. colloidal suspensions), or biomedical (e.g. tumor and melanoma diagnostic).
523

Chronic hepatitis C: Liver disease manifestations with regard to respective innate immunity receptors gene polymorphisms / Chronische Hepatitis C: Manifestationen der Lebererkrankung in Bezug auf die relevanten Genpolymorphismen des angeborenen Immunsystems

Askar, Eva 04 July 2011 (has links)
Etwa 3% der Weltbevölkerung sind von dem Hepatitis-C-Virus-Infektion betroffen. Phänotyp der HCV-induzierten Lebererkrankung variiert stark von einem Patienten zum anderen. Die Wahrnehmung der viralen doppelsträngigen RNA (dsRNA) und einzelsträngigen RNA (ssRNA) durch den Toll-like-Rezeptor 3 (TLR3) bzw. TLR7 scheinen an der Früherkennung der Pathogene und an der Wirtsantwort auf viraler Infektion beteiligt zu sein. Darüber hinaus ist die membran-assoziierte Form des Endotoxin-Rezeptor-Bestandteils CD14 (mCD14) mit TLR3 in Intrazellulärräumen kolokalisiert und erweitert die dsRNA-Erkennung und TLR3-Signalleitung. Die vorliegende Arbeit analysiert epidemiologische und klinische Daten von Patienten kaukasischer Abstammung mit einer chronischen Hepatitis C in Bezug auf bestimmte Einzellnukleotidpolymorphismen (SNPs) mit relevanten minor allele frequencies (MAFs) in Genen, die für obengenannte Rezeptoren kodieren. Es wurde keine Assoziation von dem TLR3-Promotor-Polymorphism rs5743305 (T/A) mit TLR3-Genexpression gefunden, weder in peripheren mononukleären Zellen des Blutes (PBMCs) noch in der Leber; keine weitere Korrelation mit epidemiologischen und klinischen Parametern der chronischen Erkrankung waren zu beobachten. Andererseits, T-homozygote Patienten am rs3775291-(C/T)-Polymorphismus (der in Exon 4 lokalisierter nicht-synonymer SNP) zeigen Tendenz zu einer höheren TLR3-Genexpression in der Leber. Außerdem, unter HCV-subtyp-1a-infizierten Patienten sind keine T-Homozygoten zu finden. Im Unterschied zur Lage bei alkoholischer Lebererkrankung wurde in chronischen Hepatitis-C-Patienten keine Assoziation zwischen den Fibrosegrad und CD14-Gen-C-159T-Polymorphismus gefunden. Bei T-homozygoten Patienten wurden jedoch häufiger portale lymphoide Aggregaten gefunden als bei C-Allele-Trägern. Außerdem das Vorhandensein von portalen lymphoiden Aggregaten korrelierte eng mit der Leberentzündung und mit Gallengangsläsionen. Am Ende wurde der funktionelle nicht-synonyme SNP in Exon 3 des X-gekoppelten TLR7 Gens, rs179008/Gln11Leu, untersucht. Die Analyse war auf homo- und hemizygoten Personen, die mittels Allelspezifischentranskriptquantifizierung (ASTQ) in heterozygoten weiblichen Personen eingeordnet wurden, eingeschränkt. Es zeigte sich dabei ein individueller verzerrter Mosaizismus in PBMCs. Das variante T-Allel war nur mit der Anwesenheit der portalen lymphoiden Aggregaten assoziiert. Hepatische Viruslast und Expression der Gene, die bekannterweise bei einer chronischer HCV-Infektion induziert sind, unterschieden sich zwischen Wildtyp- und Variantallelträger nicht. Jedoch eine signifikant niedrigere Expression der interleukin-29 (IL-29)/lambda1 interferon (IFN-λ1) und beider Untereinheiten seines Rezeptors (IL-10 Rβ and IL-28Rα) war bei T-homo- und hemizygoten Patienten zu beobachten. Diese Tatsache könnte eher eine Auswirkung auf die Ansprechbarkeit auf zukünftige IFN- λ-basierte Therapie haben, als auf eine Vorhersage des Ausgangs der gängigen IFN-α-basierten Therapie.
524

Behaviour Of Geosynthetic Reinforced Soil–Aggregate Systems Under Static, Repeated And Cyclic Loads

Nair, Asha M 12 1900 (has links) (PDF)
Efficient road network and connectivity play vital role in the development of any country. Majority of the rural roads are unpaved and connectivity of rural roads is always a major challenge. Unpaved roads are also used for temporary transportation facilities like access roads, haul roads for mines, forest roads and parking lots. Since these roads do not have asphalt surfacing, they are subjected to early failures due to distresses like rutting, pot holes and depressions . Stabilization of unpaved roads using geosynthetics has been proved to be promising in increasing the lifespan of these roads because they facilitate economical, aesthetic and effective design of the roads. Inclusion of geosynthetic layers at the interface of subgrade soil and granular sub-base, reduces the surface heave, ensures a better stress distribution and reduces the stresses transferred to the subgrade soil, as demonstrated by earlier researchers. Wide variety of geosynthetics like woven and nonwoven geotextiles, uniaxial and biaxial geogrids and geocells are used as reinforcement in road sections. Geotextiles improve the strength by interfacial friction, lateral restraint and membrane effect. Geogrids provide additional benefit of interlocking. Geocells are honeycomb shaped geosynthetic cellular confining systems filled with aggregates in which the reinforcement action is derived not only by friction and interlocking, but also by confinement. Load-deformation characteristics of reinforced soil-aggregate systems under static, repeated and cyclic loads is a potential topic of interest considering the fact that the design of geosynthetic reinforced unpaved roads is still under development and experimentation. The objective of the present study is to understand the beneficial use of geosynthetics in unpaved roads and to provide clear insight into the influence of geosynthetics on the cyclic loading characteristics of unpaved roads through laboratory experiments. California Bearing Ratio (CBR) tests were carried out on unreinforced and reinforced soil-aggregate systems to study the effect of various parameters such as type of reinforcement, form of reinforcement, quantity of reinforcement, and water content of the subgrade soil on the load-penetration response of the various systems. Modified CBR tests were also carried out to understand the influence of boundary of the mould and anchorage of reinforcement on the behavior of reinforced soil-aggregate systems. Behavior of unreinforced and reinforced soil-aggregate systems under repeated and cyclic loading is also studied to understand the resilience of the composite systems. From the measured stress-strain response, the elastic and plastic strains developed in various systems are compared. Different moduli such as secant modulus, cyclic modulus and resilient modulus are computed for different systems and compared. To investigate the effectiveness of geosynthetics in improving the load - bearing capacity, repeated load tests were carried out on model sections of unpaved road constructed in a steel test tank of size 750 mm × 750 mm × 620 mm. The effect of various parameters like the form of reinforcement, quantity of reinforcement, height of geocell layer and the position of geocell layer on the load-deformation behaviour of the unpaved model road sections was studied. Static and cyclic triaxial tests were carried out on unreinforced and reinforced granular sub-base materials to understand their stress strain behavior under static and cyclic loading conditions. The influence of quantity and form of reinforcement on the stress-strain behaviour of these materials was studied. From the studies it is observed that the use of reinforcement increases the CBR value of the soil-aggregate systems. Studies with two different sizes of CBR moulds indicated that the boundary effect in the standard CBR mould leads to the overestimation of the CBR value, resulting in unconservative design of road sections. Providing anchorage to the reinforcement in CBR tests did not produce an appreciable change in the load-penetration behavior. From the repeated load tests it was observed that the reinforced systems did not show any improvement in the load-deformation behaviour at low levels of rut depth. At higher rut depths, the reinforced systems developed less plastic settlements and more elastic settlements and low resilient modulus compared to unreinforced systems. From the model tests on unpaved road sections, it was observed that the improvement in the cyclic load resistance of the road due to the inclusion of geocell layer depends on the height of the geocell layer and its position. Increasing the height of geocell layer resulted in improved performance up to certain height of the geocell layer, beyond which, further increase in the height reduced the load resistance because of the inadequate granular overlay thickness and inadequate compaction of aggregate within the geocell pockets. Static and cyclic triaxial tests showed that the geogrid and geocell reinforced granular sub-base material sustained higher peak stresses and exhibited increase in modulus compared to the unreinforced specimens. Results of element and model tests carried out in this study gave important insight into the load-deformation characteristics of reinforced soil-aggregate systems under static, repeated and dynamic loads. The results provide guidelines regarding the selection of type, quantity and configuration of geosynthetic reinforcement while designing unpaved roads and the expected performance of these reinforced unpaved roads.
525

Vlastnosti asfaltových směsí typu SMA s R-materiálem / Properties of asphalt mixtures of SMA-type with RAP

Acuna Subia, Luis Carlos January 2018 (has links)
The aim of the diploma thesis is to verify and compare the properties of bituminous stone mastic asphalt, namely SMA 11S with modified PMB 45 / 80-55 asphalt binder or 50/70 road bitumen binder with rubber granulate. Comparison of properties is performed using functional tests. The thesis is divided into the theoretical and practical part. The theoretical part deals with the familiarization with the use of the SMA mixture, the selected concepts concerning recycling of non-leveled roads are described and described. Attention is paid especially to the recycling of roads in the Czech Republic with an emphasis on hot recycling on the incinerator, which allows increased dosing of Reclaimed Asphalt into asphalt mixtures. In the practical part, the results of the functional tests of the SMA 11S mixture, which have been taken from the test section, are processed and evaluated.
526

Využití asfaltových a betonových recyklátů do pozemních komunikací / The utilization of the asphalt and concrete recycled materials to roads

Žďára, Zbyněk Unknown Date (has links)
This diploma thesis is divided into two parts, theoretical and practical. The is a review om the topic of recycled asphalt pavement and recycled concrete and their possible use in road construction in the theoretical part. The individual chapters deal with describing these materials, their production, and their use in construction layers of pavements. In the next chapters the attention is also paid to their problematic features and foreign experience using these materials in pavements. In the practical part, laboratory samples of recycled asphalt pavement and recycled concrete and their mixtures with cement are tested. The main purpose is to verify the applications of these mixtures of recycled asphalt pavement and recycled concrete in the bonded base layers of the pavement. Another purpose is to compare how these mixtures individual properties with different proportions of both components and different amounts of cement will be different. In the end, the two mixtures with the best properties was selected and the modulus of elasticity was experimentally determined for the possibility of replacing the currently used base layers and the economic evaluation of this design was made.
527

Studium vlivu složení na mechanické vlastnosti vysokohodnotného betonu / Study of the influence of compositon on the mechanical properties of high performance concrete

Veleba, Ondřej January 2008 (has links)
This work is devoted to study the influence of the composition on mechanical properties of high performance concret based on portland cement. 29 samples of high performance concrete (HPC) warying in composition were prepared. The constituents used for HPC preparation were: cement Aalborg White, silica fume, finelly ground blast furnace slag, finelly ground silica, calcinated bauxite and polycarboxylate based superplasticizer. The mechanical parameters (flexural and compressive strength) of the samples were observed after 7 and 28 days of moist curing. Compressive strength values after 28 days were in the range of 92 to 194 MPa and the flexural strength values were in the range of 7 to 23 MPa (without using of fiber reinforcement). The graphs showing mechanical parameters depending on the mixture composition were constructed and consequently evaluated.
528

Využití R-materiálu v krytových vrstvách vozovek / Usage of recycled material in asphalt surface layers

Malá, Markéta January 2016 (has links)
Diploma thesis deals with adding R - material to the wearing asphalt courses, specifically to the SMA 11S. It has two parts – theoretical and practical. The theoretical part describes using R - material in the recycling of roads, different types of recycling and how is this problem handled in the Czech Republic, the practical part deals with the design of three kinds of asphalt mixtures with different added ratios of R – material, describing empirical and functional tests on the bitumen binder and the designed asphalt mixtures and the results of those tests.
529

Importance of substrate quality and clay content on microbial extracellular polymeric substances production and aggregate stability in soils

Olagoke, Folasade K., Bettermann, Antje, Nguyen, Phuong Thi Bich, Redmile-Gordon, Marc, Babin, Doreen, Smalla, Kornelia, Nesme, Joseph, Sørensen, Søren J., Kalbitz, Karsten, Vogel, Cordula 04 June 2024 (has links)
We investigated the effects of substrate (cellulose or starch) and different clay contents on the production of microbial extracellular polymeric substances (EPS) and concomitant development of stable soil aggregates. Soils were incubated with different amounts of montmorillonite (+ 0.1%, + 1%, + 10%) both with and without two substrates of contrasting quality (starch and cellulose). Microbial respiration (CO2), biomass carbon (C), EPS-protein, and EPS-polysaccharide were determined over the experimental period. The diversity and compositional shifts of microbial communities (bacteria/archaea) were analysed by sequencing 16S rRNA gene fragments amplified from soil DNA. Soil aggregate size distribution was determined and geometric mean diameter calculated for aggregate formation. Aggregate stabilities were compared among 1–2-mm size fraction. Starch amendment supported a faster increase than cellulose in both respiration and microbial biomass. Microbial community structure and composition differed depending on the C substrate added. However, clay addition had a more pronounced effect on alpha diversity compared to the addition of starch or cellulose. Substrate addition resulted in an increased EPS concentration only if combined with clay addition. At high clay addition, starch resulted in higher EPS concentrations than cellulose. Where additional substrate was not provided, EPS-protein was only weakly correlated with aggregate formation and stability. The relationship became stronger with addition of substrate. Labile organic C thus clearly plays a role in aggregate formation, but increasing clay content was found to enhance aggregate stability and additionally resulted in the development of distinct microbial communities and increased EPS production.
530

Answering Conjunctive Queries and FO+MOD Queries under Updates

Keppeler, Jens 26 June 2020 (has links)
In dieser Arbeit wird das dynamische Auswertungsproblem über dynamische Datenbanken betrachtet, bei denen Tupel hinzugefügt oder gelöscht werden können. Die Aufgabe besteht darin einen dynamischen Algorithmus zu konstruieren, welcher unmittelbar nachdem die Datenbank aktualisiert wurde, die Datenstruktur, die das Resultat repräsentiert, aktualisiert. Die Datenstruktur soll in konstanter Zeit aktualisiert werden und das Folgende unterstützen: * Teste in konstanter Zeit ob ein Tupel zur Ausgabemenge gehört, * gebe die Anzahl der Tupel in der Ausgabemenge in konstanter Zeit aus, * zähle die Tupel aus der Ausgabemenge mit konstanter Taktung auf und * zähle den Unterschied zwischen der neuen und der alten Ausgabemenge mit konstanter Taktung auf. Im ersten Teil werden konjunktive Anfragen und Vereinigungen konjunktiver Anfragen auf relationalen Datenbanken betrachtet. Die Idee der q-hierarchischen Anfragen (und t-hierarchische Anfragen für das Testen) wird eingeführt und es wird gezeigt, dass das Resultat für jede q-hierarchische Anfrage auf dynamischen Datenbanken effizient in dem oben beschriebenen Szenario ausgewertet werden können. Konjunktive Anfragen mit Aggregaten werden weiterhin betrachtet. Es wird gezeigt, dass das Lernen von polynomiellen Regressionsfunktionen in konstanter Zeit vorbereitet werden kann, falls die Trainingsdaten aus dem Anfrageergebnis kommen. Mit logarithmischer Update-Zeit kann folgende Routine unterstützt werden: Bei Eingabe einer Zahl j, gebe das j-te Tupel aus der Aufzählung aus. Im zweiten Teil werden Anfragen, die Formeln der Logik erster Stufe (FO) und deren Erweiterung mit Modulo-Zähl Quantoren (FO+MOD) sind, betrachtet, und es wird gezeigt, dass diese effizient unter Aktualisierungen ausgewertet können, wobei die dynamische Datenbank die Gradschranke nicht überschreitet, und bei der Auswertung die Zähl-, Test-, Aufzähl- und die Unterschied-Routine unterstützt werden. / This thesis investigates the query evaluation problem for fixed queries over fully dynamic databases, where tuples can be inserted or deleted. The task is to design a dynamic algorithm that immediately reports the new result of a fixed query after every database update. In particular, the goal is to construct a data structure that allows to support the following scenario. After every database update, the data structure can be updated in constant time such that afterwards we are able * to test within constant time for a given tuple whether or not it belongs to the query result, * to output the number of tuples in the query result, * to enumerate all tuples in the new query result with constant delay and * to enumerate the difference between the old and the new query result with constant delay. In the first part, conjunctive queries and unions of conjunctive queries on arbitrary relational databases are considered. The notion of q-hierarchical conjunctive queries (and t-hierarchical conjunctive queries for testing) is introduced and it is shown that the result of each such query on a dynamic database can be maintained efficiently in the sense described above. Moreover, this notion is extended to aggregate queries. It is shown that the preparation of learning a polynomial regression function can be done in constant time if the training data are taken (and maintained under updates) from the query result of a q-hierarchical query. With logarithmic update time the following routine is supported: upon input of a natural number j, output the j-th tuple that will be enumerated. In the second part, queries in first-order logic (FO) and its extension with modulo-counting quantifiers (FO+MOD) are considered, and it is shown that they can be efficiently evaluated under updates, provided that the dynamic database does not exceed a certain degree bound, and the counting, testing, enumeration and difference routines is supported.

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