Tesis sobre el tema "Passive traces"
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Devillers, Delphine. "Fiabilisation de la quantification des éléments traces cationiques et anioniques par la technique d'échantillonnage DGT en milieu aquatique naturel". Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0058/document.
Texto completoThe passive sampling DGT technique (Diffusive Gradients in Thin Films) has a lot of benefits (time-weighted average concentrations, low limits of quantification) and would therefore be a useful tool for monitoring studies to quantify trace elements in natural water. However, there are still some limitations and grey areas that put the brakes on the development of the method for regulatory applications. The aim of this work is to identify potential biases and contribute to increase the method reliability. This study shows that a minimized uncertainty on results can be obtained only if elution factors are experimentally determined; however, standard values of 0.8 for Cr(III) and 0.85 for Al(III), Cd(II), Co(II), Cu(II), Ni(II), Pb(II) and Zn(II) are suggested to reduce manipulations while keeping reasonable uncertainty (<10%). Studying the influence of fouling developed on DGT devices showed that the sorption of cations Cd(II), Cu(II) and Pb(II) had, respectively, a slight, moderate and strong impact on their accumulation in DGT samplers and therefore on their quantification. Samplers should then be deployed for less than one week. In contrast, fouling had a negligible impact on oxyanions As(V), Cr(VI), Sb(V) and Se(VI). Finally, a method was developed to simultaneously quantify both Cr oxidation states naturally occurring in natural waters, which are Cr(III), essential to life, and Cr(VI), toxic. Both forms are accumulated in a single DGT sampler before being selectively separated during an elution step. This method is robust for wide ranges of ionic strengths and sulfate concentrations but for a narrower range of pH (4 to 6)
Vystavna, Yuliya. "Environmental and socio-economic determinants, their impacts on trace metals and pharmaceuticals in watercourses : a comparison on two watersheds of France and Ukraine". Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14486/document.
Texto completoThe PhD study focuses on the understanding of processes of the impact of environmental and socio-economic determinants on the occurrence, accumulation and distribution of trace metals and pharmaceuticals in urban watercourses. The research has been based on the analysis of the origin; physico-chemical properties and behavior of trace pollutants. The study was performed in two general steps: (i) monitoring of trace metals and pharmaceuticals in natural waters; (ii) description and analysis of environmental and socio-economic determinants that influence the water chemistry and (iii) evaluation of trace pollutants as environmental and socio-economic indicators. The monitoring of trace metals in natural water was proceed using the combination of passive and grab water sampling techniques, in order to evaluate various forms of elements, sources, seasonal and spatial variations, accumulation and environmental risks associated with the presence of contaminants in the study areas. The monitoring of pharmaceuticals was done using passive sensors to determine their capacity to register chemicals variation in time and adequation to use environmental data for the regional medicament consumption modeling. Monitoring data were also investigated in term of potential applications of trace metals and pharmaceuticals as environmental and socio-economic indicators. Two study sites were chosen: (1) the Kharkiv region in Ukraine where research was focused on the Lopan and Udy rivers of the Seversky Donets water basin and (2) the Bordeaux region in France where water monitoring was done in the Jalle River, Garonne water basin. Sites were mainly selected to represent the water pollution status in different socio-economic regions. General PhD results can be described as follows:1. The methodology for pilot and continuous monitoring of trace elements in the water with combination of traditional (grab) and innovative (passive) sampling procedures help to get data on trace elements presence, accumulation and sources, considering time variations.2. The analysis of trace metals and pharmaceuticals in two river basins of France and Ukraine and determination of environmental factors that impact on the occurrence, accumulation and distribution of these chemicals.3. The establishment of links between regional socio-economic issues and water quality data. The socio-economic and environmental modeling helps us to understand the water pollution process in regional context and give the opportunity to propose contaminants as tracers of anthropogenic activities and water quality assessment.Results of the PhD study are presented in the form of published or submitted peer-reviewed articles
Диссертация «Экологические и социально-экономические факторы распространения металлов и фармацевтических веществ в природных водах: на примере рек Харькова, Украина и Бордо, Франция» на соискание степени Доктора Философии (Environmental Science) подготовлена в рамках договора о научном сотрудничестве и совместном руководстве между Университетом Бордо, Франция и Харьковской национальной академией городского хозяйства, Украина.Актуальность работы связана с сушествующими проблемами мониторинга природных вод, недостатком исследований микро-загрязнителей водотоков как во Франции, так и в Украине, существующим экологическим риском, который возникает при поступлении и накоплении металов и фармацевтических веществ в урбанизированных водотоках, а также возможностью использования химических веществ в качестве экологических и социально – экономических индикаторов. Целью диссертационной работы стало усовершенствование методов мониторинга микро-загрязнителей в природных водах и оценка возможности использования отдельных микро-загрязнителей в качестве экологических и социально-экономических показателей. Предметом исследования являются экологические и социально-экономические факторы, влияющие на распространение металлов и фармацевтических веществ в природных водах. Объектом исследования стали реки Уды и Лопань, Харьковская область, Украина и река Жаль, регион Бордо, Франция.Основные задачи: (1) провести мониторинг рек на различные формы металлов и фармацевтические вещества с применением стандартных и инновационных (пассивных) методов отбора проб; (2) опеределить экологические и социально- экономические факторы, которые влияют на распространение микрозагрязнителей в природных водах; (3) изучить возможность использования металлов и фармацевтических веществ в качестве индикаторов антропогенного загрязнения природных вод.В результате проведенных исследований был: Впервые: (а) осуществлен мониторинг лабильных форм металлов в реках бассейна Северского Донца, в результате которого определены концентрации токсичных металлов в водотоках, источники и количество их поступления; (б) проведен мониторинг фармацевтических веществ в природных водах Украины, (в) определены концентрации и основные источники поступления фармацевтических препаратов и удельные показатели потребления различных медикаментов в Харьковском регионе; Усовершенствованы: (а) методика проведения мониторинга воды за счет применения стандартных и инновационных пассивных методов отбора проб воды в контрастных климатических и гидрологических условиях с целью исследования различных форм загрязнителей и их временных вариаций; (б) балансово-статистическая модель, которая позволяет использовать данные мониторинга природных вод для социально-экономической характеристики регионов – водопользователей; Предложены:(а) система определения геохимического фона рек на основании торий – нормализованных концентраций металлов в донных отложениях; (б) метод использование металлов и фармацевтических веществ в качестве индикаторов поступления сточных вод для идентификации несанкционированных сбросов.Основу диссертационного исследования составили натурные данные полевых исследований рек Харькова и Бордо, которые были организованы и проведены с непосредственным участием автора в 2008 – 2011 гг. Большинство лабораторных анализов было лично проведено автором в сертифицированных лабораториях Университета Бордо и Университета Орлеан, Франция.Диссертация имеет теоретическое и практическое значение для дальнейшего развития мониторинга природных вод, а также повышения уровня экологической и социальной безопасности в регионах. По теме опубликовано 4 статьи в международных журналах с высоким ИМПАКТ фактором, а также 5 статей в изданиях, реглиментированных ВАК Украины и России
Mouttappa, Pramila. "A symbolic-based passive testing approach to detect vulnerabilities in networking systems". Phd thesis, Institut National des Télécommunications, 2013. http://tel.archives-ouvertes.fr/tel-01017860.
Texto completoToumi, Khalifa. "A trust framework for multi-organization environments". Phd thesis, Institut National des Télécommunications, 2014. http://tel.archives-ouvertes.fr/tel-00997693.
Texto completoLelarge, Maria Lidia Meideros Vignol. "Thermochronologie par la méthode des traces de fission d'une marge passive (dôme de Ponta Grossa, se Brésil) et au sein d'une chaîne de collision (zone externe de l'arc alpin, France)". Université Joseph Fourier (Grenoble), 1993. https://tel.archives-ouvertes.fr/tel-00603209.
Texto completoVASSIO, LUCA. "Data Analysis and Modelling of Users’ Behaviour on the Web". Doctoral thesis, Politecnico di Torino, 2018. http://hdl.handle.net/11583/2703665.
Texto completoLe nuove tecnologie e le loro applicazioni modificano il nostro approccio con ciò che ci circonda. L'avvento di Internet, con la sua capillarità e pervasività, è stata la trasformazione più importante e repentina degli ultimi 30 anni. La mia ricerca è stata guidata dalla necessità di capire come le persone interagiscano con il web, di catturare come il web stesso cambi, e di modellare le abitudini e i comportamenti degli utenti. Tracce e registri dell'attività online, altrimenti dette misure passive, offrono informazioni inestimabili per raggiungere questi obiettivi. Grazie a queste tracce, il mio lavoro si concentra nello studiare il comportamento delle persone quando navigano su Internet, da due punti di vista complementari: (i) l'analisi dei dati di navigazione e (ii) i modelli analitici di comportamento. Tuttavia, vi sono molteplici sfide da affrontare: questo tipo di dati, detti \textit{big data}, necessitano di hardware e software scalabili, e dell'introduzione di metodologie e metriche innovative per ottenere informazioni che siano pulite, affidabili e soprattutto utili. L'analisi dati viene eseguita grazie a metodi statistici, di machine learning e di data mining. Inoltre, l'analisi è un prerequisito per costruire dei modelli analitici dei fenomeni studiati, che siano il più possibile aderenti alla realtà. Infine, capire l'applicabilità dei modelli costruiti è un passaggio fondamentale per ottimizzare le prestazioni e capire i possibili scenari. Più in dettaglio, durante il mio dottorato, ho analizzato 3 anni di dati di circa 30\,000 abitazioni, e ne ho ricostruito le attività online. Grazie a ciò, ho potuto mostrare l'evoluzione nell'utilizzo di diversi dispositivi, la struttura intrinseca delle navigazioni e l'interazione con le reti sociali e i motori di ricerca. Ho introdotto dei sistemi automatici per identificare le pagine e i servizi web intenzionalmente richiesti. Ho anche analizzato la costruzione di profili degli utenti, tracciando i loro domini visitati, per poi mostrare come poterli re-identificare nel futuro. Ho modellato le sequenze di siti visti, rappresentandole succintamente in una maniera facilmente interpretabile. Ho mostrato come estrarre automaticamente gruppi di siti web simili in contenuto o strettamente relazionati, e come riunire interessi e trend di utenti singoli o intere comunità. Ho anche modellato l'interazione con i sistemi di raccomandazione, introducendo un modello di comportamento umano che cattura l'impatto della dinamica temporale delle pubblicità mostrate. Infine, ho migliorato sperimentalmente i ricavi di una piattaforma di pubblicità, ottimizzandone i tempi di visualizzazione delle inserzioni. I miei risultati hanno diverse implicazioni per i molteplici attori nel panorama web e per il mondo della ricerca. Seguendo un corretto approccio scientifico, I dataset usati in questa tesi sono resi disponibili in modo anonimizzato per la comunità, in modo da garantire la riproducibilità dei miei risultati. Inoltre, il tema della privacy online in un mondo in forte cambiamento è stato affrontato e analizzato, con l'obiettivo di trovare un compromesso tra il bisogno di ottenere la conoscenza per lo sviluppo delle tecnologie e la necessità di non violare la riservatezza degli individui. Infine, l'attuale trasformazione digitale comporta che tutte le persone e oggetti producono dati che possano essere sfruttati per creare sconvolgenti possibilità. L'analisi dati ci permette di realizzare incredibili trasformazioni non solo di Internet, ma anche nelle nostre città, nella produzione di energia o nell'industria. Sfruttare i comportamenti delle persone che si ottengono attraverso questi dati, modellare e ottimizzare le prestazioni dei sistemi così come ho fatto in questo lavoro, sarà un fattore chiave per progettare le città intelligenti di un futuro molto vicino.
New technologies and services strongly transform our approach with the world. The Internet and its pervasive use was certainly the most dramatic leap in the last 30 years. My research was driven by the need to understand how people interact with the web, capturing its characteristics and changes, and modelling people's inner habits and interactions. Traces and logs of users' behaviours collected in the Internet (i.e., passive measurements) offer invaluable information to obtain this goal. Thanks to these passive traces, my work focuses on studying the behaviour of the users on the Internet, with focus on two complementary aspects: (i) data analytics, and (ii) user modelling. There are many key challenges to face: (big) data requires the use of scalable software and hardware. It demands also the introduction of innovative methodologies and meaningful metric to obtain trustable, filtered, clean and useful information. Data analytics is performed by means of a variety of statistical, machine learning and data mining approaches. Moreover, it is also a pre-requisite for creating analytical models of the studied phenomena, that should be as much as possible adherent to the reality. Lastly, understanding the applicability of derived models is a fundamental step for optimizing performances and understanding possible scenarios. More in details, during my PhD I analyzed 3 years of data of about 30\,000 households. I reconstruct users' online activity. Thanks to this, I was able to highlight device usage evolution, the intrinsic structure of the navigation and the interactions with social networks and search engines. I introduced a new machine learning approach to identify the intentionally visited web-pages and web-sites. Then, I built specific users' profiles, fingerprinting their visited domains, and then I showed how to re-identify users in a future time. I modelled the sequence of the visited web services, representing them in a succinct and interpretable manner. I showed that I can automatically extract groups of similar or likely connected web-sites, and monitor the interests and browsing patterns of single users or communities. I also modelled the user interaction with online recommendation systems, introducing a user behavioural model that captures the impact of the temporal dynamics of shown advertisement. Lastly, I demonstrate how to improve the revenue of an advertisement platform, optimizing the timings when ads are shown to users. My findings have several direct implications to the different Internet actors and to the research community. Following the scientific approach, I made available the anonymized datasets for the community, in order to guarantee the reproducibility of my results. Moreover, I addressed the problem of privacy online in today changing world, with the objective of finding a trade-off between the desire to obtain knowledge for shaping new technologies and the need to not violate the privacy of individuals. Finally, the current digital transformation implicates that everyone and everything produce data that can be exploited to create new disruptive capabilities. Data analytics allows us to realize incredible transformations not only in the web, but also in our cities, in the energy production, and in manufacturing. Exploiting the knowledge of the users' behaviour from these data, modelling and optimizing system performances as I did in my work, will be a key factor for designing near future smart-cities.
Villanueva, Jessica Denila. "Suivi par capteurs passifs des polluants émergents dans les eaux de surface en contexte urbain". Thesis, Bordeaux 1, 2013. http://www.theses.fr/2013BOR14186/document.
Texto completoThe study aimed to assess the water quality of the surface water in differingclimate conditions and management practices. Three interesting sites were chosen, (1)Jalle River and (2) Bordeaux Lac both in France and the (3) Pasig River in thePhilippines. The French sites have rainfall and run-off collectors that directly dischargewater to the water bodies. Pasig River, on the other hand, becomes a waste collector aswaste management and treatment plant are lacking. Trace metals and organics(pesticides, herbicides, pharmaceuticals and drugs) were measured. Conventional andpassive sampling approches were employed. The mass fluxes were obtained in order tocalculate the pollution transport. Physico-chemical properties and the particlecharacteristics, integrating statistical analyses, facilitated in explaining the behavior of themeasured molecules and describing the hydrological system in relation to climatevariability
Veyret, Nathalie. "Traces d'un passage : l'oeuvre de Barbara Pym". Bordeaux 3, 1996. http://www.theses.fr/1996BOR30036.
Texto completoThis study of the works of barbara pym includes for the first time in france the analysis of the author's personal papers deposited at the bodleian library : manuscripts of the novels, her diary, letters, notebooks and conference scripts. The wealth of this material is the starting point for a new study of the novels. The works are the traces of the author's passage in post-var england. Pym's characters are rather dull and lead a quiet unobtrusive life. Pym's world is the world of failure, in which men and women play games but never achieve communication. Love affairs are so dangerous that they are avoided. Solitude sometimes is best company, especially when relieved by the prosaic, mundane pleasures of food for instance. The characters invent a life of their own, in which humdrum tasks play a prominent role. Pym's writing also uses banality to emphasise the tragedy of human life. Simple words bide a profound meaning. Pym achieves this book about nothing flaubert wished for
Fabbroni, Nicoletta <1979>. "Numerical simulations of passive tracers dispersion in the sea". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1733/1/Fabbroni_Nicoletta_Tesi.pdf.
Texto completoFabbroni, Nicoletta <1979>. "Numerical simulations of passive tracers dispersion in the sea". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1733/.
Texto completoSiberlin, Charlotte. "Time-scales of passive tracers in the ocean with paleoapplications". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59790.
Texto completoCataloged from PDF version of thesis.
Includes bibliographical references (p. 131-134).
Quantifying time-responses of the ocean to passive and active tracers is critical when interpreting paleodata from sediment cores. Surface-injected tracers are not spreading instantaneously or uniformly throughout the ocean. To obtain insights into these time-scales, a transition matrix is used to compute successive states of a passive tracer concentration in the global ocean. Times to equilibrium are longer than 1500 years for any one region in the global ocean and, near the equilibrium, concentration gradients give time-lags from hundreds to thousands of years between the Atlantic and Pacific bottom, depending on the injection region and the nature of the boundary condition. Ice volume (glacio-eustatic) corrections to deep-sea and surface values cannot be assumed instantaneous, challenging previous paleodata interpretations from sediment cores. Preliminary results on time-responses of the ocean to active tracers, using a global circulation model limited to the North Atlantic box, show no major differences between a freshwater and a dye input, at least during the first 50 years of the experiment and for a small amount of freshwater.
by Charlotte Siberlin.
S.M.in Climate Physics and Chemistry
Ferrari, Raffaele. "Dispersion of passive and active tracers in the upper ocean /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2000. http://wwwlib.umi.com/cr/ucsd/fullcit?p3035412.
Texto completoMatheu, Nathalie. "Passage à l’écriture, écriture du passage : sur les traces d’adultes migrants en ateliers d’écriture". Thesis, Montpellier 3, 2018. http://www.theses.fr/2018MON30089.
Texto completoFor the last twenty years, writing pedagogy has been enriched in reflection and practice by research, most notably, from linguistics and genetic criticism (Fabre, 1990; Doquet, 2011; Chiss, 2012). These studies, which consider writing within its scriptural dynamic, have examined the construction of the act of writing (Fénoglio & Chanquoy, 2007). In light of the contributions of J. Derrida (1967) and J. Goody (1977/1979), who dismissed the hegemony of logocentric thought, writing can effectively no longer be reduced to a secondary code, a dual representation of thought and the language that gives voice to it. With its specific functions, writing is intertwined with memory, both through anamnesic activation and the informed use of hypomnesic artifacts (writing instruments and media). The double memory game (anamnesis and hypomnesis), which contributes to the process of writing, enables the transition to the written mode by orchestrating a chain that, in a symbolic way, links voice and writing and thus opens inscriptional spaces for the writing subject. This epistemological refection supported the development of experimental instructional sessions, which took the form of writing workshops, designed to support migrant adults’ transition to writing. The workshops were implemented as part of a broader introduction to the language arts (Meschonnic, 1982; Auger & Pierra, 2006; Aden, 2008) in contexts of teaching and learning French as a second language (FSL). This arrangement allowed for the construction of a corpus of 74 textual manuscripts, collected by means of participant observation in the context of volunteer work. The qualitative analysis of data, examined through the application of theory and methods from discourse analysis and textual genetics, was organized around a three-pronged approach to the notions of transition and writing. The examination of graphic marks makes it possible to uncover (1) the initial strategies of FLS writers, (2) their reconsideration of previously written text, notably by means of deletions, which reveal inner dialogism (Bres, 1988) inherent to the production of writing, and (3) the emergence of memories that reconstruct the migrant experience, and which constitute writing in transition
Sundermeyer, Miles Aaron. "Mixing in the North Atlantic tracer release experiment : observations and numerical simulations of Lagrangian particles and passive tracer". Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/57846.
Texto completoIncludes bibliographical references (leaves 89-90).
by Miles Aaron Sundermeyer.
M.S.
Zygalakis, Konstantinos C. "Effective diffusive behaviour for passive tracers and inertial particles : homogenization and numerical algorithms". Thesis, University of Reading, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494970.
Texto completoPoulier, Gaelle. "Etude de l’échantillonnage intégratif passif pour l’évaluation réglementaire de la qualité des milieux aquatiques : application à la contamination en pesticides et en éléments trace métalliques des bassins versants du Trec et de l’Auvézère". Thesis, Limoges, 2014. http://www.theses.fr/2014LIMO0032/document.
Texto completoThe intensive use of pesticides in agriculture and urban activities since the 1950s has led to diffuse contamination of environmental compartments (air, soil, water). The presence of these molecules can lead to toxic effects for biota. The implementation of the Water Framework Directive (WFD) requires the use of an efficient monitoring network, based on reliable sampling and analytical techniques. Nowadays, grab sampling followed by extraction of analytes and chromatographic analysis is the most widespread strategy because of its simplicity of implementation but it also has numerous drawbacks. The crux of the issue lies in the lack of temporal representativeness and the low analytical sensibility. An alternative strategy to overcome some of these problems could be the use of passive samplers. This contribution aims at discuss about the possible application of passive samplers in regulatory monitoring programs. The originality of this work lies in :The variety of tested devices: three different samplers was studied (The Polar Organic Chemical Integrative Sampler (POCIS), the Chemcatcher and the Diffusive Gradient in Thin Film (DGT). Conventional grab sampling strategies were also evaluated.The variety of studied environments: two very different watersheds were selected. The first one presented a high level of contamination; the second had a low contamination in pesticides.The implementation of passive samplers in a real regulatory context, as the selected streams were monitored by the Water Agency for operational control. Data from the Water Agency could therefore be compared with passive sampler data
Pöschke, Patrick. "Influence of Molecular Diffusion on the Transport of Passive Tracers in 2D Laminar Flows". Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19526.
Texto completoIn this thesis, we consider the advection-diffusion-(reaction) problem for passive tracer particles suspended in two-dimensional laminar flow patterns with small thermal noise. The deterministic flow comprises cells in the shape of either squares or cat’s eyes. Rotational motion occurs inside them. Some of the flows consist of sinusoidal regions of straight forward motion. All systems are either periodic or are bounded by walls. One examined family of flows continuously interpolates between arrays of eddies and shear flows. We analyse extensive numerical simulations, which confirm previous theoretical predictions as well as reveal new phenomena. Without noise, particles are trapped forever in single building blocks of the flow. Adding small thermal noise, leads to largely enhanced normal diffusion for long times and several kinds of diffusion for intermediate times. Using continuous time random walk models, we derive analytical expressions in accordance with numerical results, ranging from subdiffusive to superballistic anomalous diffusion for intermediate times depending on parameters, initial conditions and aging time. We clearly see, that some of the previous predictions are only true for particles starting at the separatrix of the flow - the only case considered in depth in the past - and that the system might show a vastly different behavior in other situations, including an oscillatory one, when starting in the center of an eddy after a certain aging time. Furthermore, simulations reveal that particle reactions occur more frequently at positions where the velocity of the flow changes the most, resulting in slow particles being hit by faster ones following them. The extensive numerical simulations performed for this thesis had to be done now that we have the computational means to do so. Machines are powerful tools in order to gain a deeper and more detailed insight into the dynamics of many complicated dynamical and stochastic systems.
Gough, William A. (William Arthur). "Lateral and isopycnal mixing of passive and active tracers in an ocean general circulation model". Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=70297.
Texto completoIn the equilibrium experiments, the isopycnal case has more gyre kinetic energy, a less intense thermohaline circulation, and less interior downwelling than the lateral case. Convection is replaced by enhanced vertical diffusion in the isopycnal case.
In the time dependent passive tracer experiments, the isopycnal case has smaller depth penetration of a surface released tracer. This is likely due to induced recirculation rather than numerical limitations.
The active tracer experiments examine the long term asymmetric behaviour of warm and cold surface anomalies introduced in an abrupt and gradual fashion for the lateral and isopycnal models. The thermal anomalies produce asymmetric transient responses. The abrupt and gradual changes produce the same equilibrium but different transient responses. The isopycnal case responds more rapidly and energetically than the lateral case.
Watkins, Eric Andrew. "Development of Potential Remote Coal Mine Fire Response Measures: Use of Multiple Passive Source Tracers and Simulation of High Expansion Foam Flow in Simulated Gob Material". Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83788.
Texto completoMaster of Science
Hankin, Barry Gwyn. "Modelling the dispersion of a passive tracer in complex open channel flows using random walk, particle tracking techniques". Thesis, Lancaster University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296886.
Texto completoSeo, Daniele. "Avaliação dos teores de Br, Cl, K, Mg, Mn e V em mexilhões Perna perna (Linnaeus, 1758: Mollusca, Bivalvia) coletados no litoral do estado de São Paulo, Brasil". Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-08032013-161647/.
Texto completoThe coastal environment has been heavily altered by multiple environmental impacts of human activities, such as disposal of sewage from urban areas, the release of numerous chemical industries, agriculture and the flow of vessels, which can lead to accidental spills of oil and oil products, fuels and other products transported by sea. In this context, a means of determining concentrations of these potentially toxic substances in the sea water is the biomonitoring by means of different types of bivalves, which have been used by various researchers, in Brazil and other countries. With regard to bivalve mollusks, particularly mussels, their use in monitoring the marine contamination is mainly due to their wide geographic distribution, sessile habit and ability to concentrate toxic metals to 102-105 times in relation to the concentrations detected in water. In the present study, we employed the passive biomonitoring using the Perna perna bivalve mollusk with respect to the elements Br, Cl, K, Mg, Mn and V. These elements were chosen since they can be determined by INAA method (Instrumental Neutron Activation Analysis), by means of short irradiation which provides faster analyzes and also due to their importance from the standpoint of environmental or nutritional studies. The aim of this study was to evaluate the content of Br, Cl, K, Mg, Mn and V in samples of Perna perna mussels (Linnaeus, 1758: Mollusca, Bivalvia) collected in coastal regions of São Paulo subject to anthropogenic contamination (Ponta de Itaipu and Palmas Island, in Santos), comparing the values obtained in sites potentially impacted with the values of the control site in Praia da Cocanha, in Caraguatatuba. The collection points located in São Paulo coast are located in the geographical areas 23º 37\'S - 45° 24\' W (Caraguatatuba) and 23º 57\'S - 46º 20\' W (Santos). The collection of organisms was performed in all seasons of the year, beginning in spring 2008 and ending in winter 2009. The samples were cleaned, crushed, homogenized and dried by lyophilization for further analysis by INAA. The INAA procedure consisted of irradiating aliquots of the samples obtained in powder form in polyethylene envelopes in the nuclear research reactor IEA - R1 of IPEN / CNEN - SP together with synthetic standards of elements. The irradiation time in the reactor was 8 to 10 s under the thermal neutron flux of 6.6 x 1012 n cm-2 s-1. The concentrations of the elements were calculated using the comparative method. The INAA procedure was validated with respect to accuracy and precision, through the analysis of certified reference materials NIST SRM 1566b Oyster Tissue and NIST SRM 2876 Mussel Tissue. The results of these certified reference materials indicated good quality of results with respect to precision and accuracy. The ranges of concentrations (dry basis weight) of the elements obtained in mussels collected in Santos and Praia da Cocanha for the four seasons of the year were: 173.80 to 358.99 mg kg-1 for Br; 45658 ± 1811 to 109166 ± 824 mg kg-1 for Cl; 7043 ± 856 to 12506 ± 675 mg kg-1 for K; 2774 ± 211 to 5691 ± 717 mg kg-1 for Mg; 7.01 ± 0.30 to 29.74 ± 3.32 mg kg-1 for Mn and 0.77 ± 0.02 to 3.43 ± 0.28 mg kg-1 for V. The seasonal and spatial variations of the concentrations of these elements were studied and the values compared to the literature. From the results obtained it can be concluded that the species of Perna perna mussels, can be used as biomonitors of marine contamination.
Bohlin, Pernilla. "Passive sampling of PAHs and some trace organic compounds in occupational and residential air : needs, evaluation and limits /". Göteborg : Institute of Medicine at Sahlgrenska Academy, University of Gothenburg, 2010. http://hdl.handle.net/2077/2.
Texto completoBERSANO, ANDREA. "Analysis of natural circulation and passive systems phenomenology in nuclear plants". Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2829632.
Texto completoJong, Edmund Chime. "Development and Evaluation of a Permeation Plug Release Vessel (PPRV) for the Release of Perfluoromethylcyclohexane (PMCH) in Underground Mine Tracer Gas Studies". Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/24912.
Texto completoPh. D.
JULLIEN, MARIE-CAROLINE. "Dispersion de traceurs passifs dans des experiences de turbulence bidimensionnelle". Paris 6, 2000. http://www.theses.fr/2000PA066236.
Texto completoQuirino, Valquiria Ferraz. "Evaluating the Potential for Estimating Age of Even-aged Loblolly Pine Stands Using Active and Passive Remote Sensing Data". Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/71309.
Texto completoPh. D.
Kumar, Ratnesh. "Segmentation vidéo et suivi d'objets multiples". Thesis, Nice, 2014. http://www.theses.fr/2014NICE4135/document.
Texto completoIn this thesis we propose novel algorithms for video analysis. The first contribution of this thesis is in the domain of video segmentation wherein the objective is to obtain a dense and coherent spatio-temporal segmentation. We propose joining both spatial and temporal aspects of a video into a single notion Fiber. A fiber is a set of trajectories which are spatially connected by a mesh. Fibers are built by jointly assessing spatial and temporal aspects of the video. Compared to the state-of-the-art, a fiber based video segmentation presents advantages such as a natural spatio-temporal neighborhood accessor by a mesh, and temporal correspondences for most pixels in the video. Furthermore, this fiber-based segmentation is of quasi-linear complexity w.r.t. the number of pixels. The second contribution is in the realm of multiple object tracking. We proposed a tracking approach which utilizes cues from point tracks, kinematics of moving objects and global appearance of detections. Unification of all these cues is performed on a Conditional Random Field. Subsequently this model is optimized by a combination of message passing and an Iterated Conditional Modes (ICM) variant to infer object-trajectories. A third, minor, contribution relates to the development of suitable feature descriptor for appearance matching of persons. All of our proposed approaches achieve competitive and better results (both qualitatively and quantitatively) than state-of-the-art on open source datasets
Howell, Jamie Robert. "Learning through stories : An investigation into how Tracks Rites of Passage Programme impacts on the development of young men and their family systems". Thesis, University of Canterbury. Educational Studies and Leadership, 2012. http://hdl.handle.net/10092/7611.
Texto completoFlynn, Ross Christopher. "Persistence of diatoms as trace evidence in clothing fabrics: The effects of active removal (machine washing) and passive removal (time and environment)". Thesis, Flynn, Ross Christopher (2021) Persistence of diatoms as trace evidence in clothing fabrics: The effects of active removal (machine washing) and passive removal (time and environment). Masters by Research thesis, Murdoch University, 2021. https://researchrepository.murdoch.edu.au/id/eprint/63158/.
Texto completoPöschke, Patrick [Verfasser], Igor [Gutachter] Sokolov, Benjamin [Gutachter] Lindner y Marcin [Gutachter] Magdziarz. "Influence of Molecular Diffusion on the Transport of Passive Tracers in 2D Laminar Flows / Patrick Pöschke ; Gutachter: Igor Sokolov, Benjamin Lindner, Marcin Magdziarz". Berlin : Humboldt-Universität zu Berlin, 2018. http://d-nb.info/1185175024/34.
Texto completoBraun, Joanne. "Box Turtles, Terrapene carolina, as Potential Seed Dispersers: Effects of Passage Through Digestive Tracts on Seed Germination". W&M ScholarWorks, 1985. https://scholarworks.wm.edu/etd/1539625298.
Texto completoEricsson, Anton y Anton Erickson. "Does the Active Country Momentum Portfolio Beat the Passive Market Portfolio? : an empirical study on exchange-traded funds". Thesis, Örebro universitet, Handelshögskolan vid Örebro Universitet, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-89230.
Texto completoLesouëf, Dorothée. "Étude numérique des circulations locales à la Réunion : application à la dispersion de polluants". Phd thesis, Université de la Réunion, 2010. http://tel.archives-ouvertes.fr/tel-00633096.
Texto completoLapointe, Frédérique y Frédérique Lapointe. "Tracer son chemin : la transition à la vie adulte des femmes ayant expérimenté l'itinérance". Master's thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/37561.
Texto completoCertains groupes de la population sans domicile fixe sont identifiés comme particulièrement vulnérables. Les femmes et les jeunes adultes en font partie. En plus d’être spécifiquement touchées par certaines formes d’adversité au courant de leur vécu de rue, ces franges minorisées des populations en situation d’itinérance sont rarement représentées dans les politiques sociales et les dénombrements entourant ce phénomène. Le but de cette recherche est de faire entendre les voix de femmes ayant expérimenté l’itinérance sur la façon dont elles vivent ou ont vécu leur transition à la vie adulte. Prenant appui sur la perspective intersectionnelle socioconstructionniste, cette étude a cherché à éclairer leur expérience et leur compréhension de leur situation, tout en mettant en lumière les mécanismes d’oppression et les stratégies de résistance présents dans leur parcours. Misant sur une approche narrative, cette recherche qualitative a été réalisée par le biais d’entretiens individuels auprès de cinq jeunes femmes afin de recueillir le récit personnel de leur passage à la vie adulte. Ainsi, le parcours singulier de chacune de ces femmes de même que les similitudes et les différences entre leurs situations respectives ont été analysées pour mieux comprendre leurs expériences semblables et variables de l’itinérance au cours du passage à la vie adulte. Les résultats décrivent des parcours faits de départs, de nouvelles rencontres et de prises de décisions menant vers diverses situations de revenus et d’hébergement. Au-delà des interprétations qu’elles font de leur vécu respectif, les participantes éclairent les mécanismes d’oppression auxquels elles sont confrontées, incluant diverses formes de mise à l’écart et de violence, ainsi que les stratégies qu’elles emploient pour améliorer leur sort.
Some groups of the homeless population are identified as particularly vulnerable. Women and young adults are part of them. In addition to being specifically affected by certain forms of adversity when they are on the streets, these minority fringes of homelessness are rarely represented in social policies and are not included in the numbers regarding this phenomenon. The purpose of this research is to put forward the experience of transition to adulthood of women who experience, or have experienced, homelessness. Drawing on the intersectional socioconstructionist perspective, this study sought to shed light on their path and understanding of their situation, while highlighting the mechanisms of oppression and the strategies of resistance. Using a narrative approach, this qualitative research was conducted through individual interviews with five young women. Thus, each of these women's unique pathways as well as the similarities and differences between their respective situations were analyzed to better understand their similar and variable experiences of homelessness during the pathway of adult life. The results describe journeys made of departures, new encounters and decision-making leading to various income and housing situations. Beyond the interpretations they make of their experiences, the participants shed light on the oppression mechanisms they face, including various forms of exclusion and violence, as well as the strategies they employ to improve their lives.
Some groups of the homeless population are identified as particularly vulnerable. Women and young adults are part of them. In addition to being specifically affected by certain forms of adversity when they are on the streets, these minority fringes of homelessness are rarely represented in social policies and are not included in the numbers regarding this phenomenon. The purpose of this research is to put forward the experience of transition to adulthood of women who experience, or have experienced, homelessness. Drawing on the intersectional socioconstructionist perspective, this study sought to shed light on their path and understanding of their situation, while highlighting the mechanisms of oppression and the strategies of resistance. Using a narrative approach, this qualitative research was conducted through individual interviews with five young women. Thus, each of these women's unique pathways as well as the similarities and differences between their respective situations were analyzed to better understand their similar and variable experiences of homelessness during the pathway of adult life. The results describe journeys made of departures, new encounters and decision-making leading to various income and housing situations. Beyond the interpretations they make of their experiences, the participants shed light on the oppression mechanisms they face, including various forms of exclusion and violence, as well as the strategies they employ to improve their lives.
Musa, Arshad. "Passive versus active applications of industry exchange traded funds (ETFs) : an empirical investigation on the S&P Global 1200 Index". University of the Western Cape, 2015. http://hdl.handle.net/11394/4912.
Texto completoThe notion of market efficiency posits that stock prices fully reflect all available information in a timely manner. The efficient market hypothesis (EMH) proposed by Fama (1970) systematically rules out the profitability of information driven investing, and implicitly promulgates a passive market capitalisation weighted investment strategy such as indexing. The appeal of passive strategies has largely been driven by the growth of passive tracking instruments, which allow investors to earn underlying index performance by purchasing a single security such as an exchange traded fund (ETF). On the contrary, proponents of behavioural finance suggest that investors are irrational and subject to psychological biases. Furthermore, the noisy market hypothesis of Siegel (2006) asserts that the deviations from the economic ideal of rationality proposed by the EMH, introduces noise in the market which could lead prices to deviate from their intrinsic values. The resultant drag in performance of market capitalisation weighted indices suggests that the optimal cap-weighted market portfolio promulgated by the modern portfolio theory (MPT) of Markowitz (1952), ceases to be the most mean-variance approach to asset allocation. With the goal of testing the applications of ETF’s, this study first evaluates the performance of passive sector ETF’s in the global equity market. In addition, motivated by the potential inefficiencies of capweighted portfolios, the study tests optimisation based asset allocation techniques, and technical analysis based market timing strategies. The study employs the S&P Global 1200 sector indices and their respective sector ETF’s to test their performances and applications in passive and active investment strategies, over the period from July 5th, 2002 to February 6th, 2015. The ETF’s are evaluated based on their tracking ability and price efficiency. All 10 sector ETF’s possess insignificant tracking errors and successfully replicate the performance of their underlying indices. In addition, the globalsector ETF’s are not price efficient over the study period, as they possess persistent price deviations from their net asset values (NAV’s). Furthermore, the ETF trading strategy based on the relationship between ETF returns and price deviations, proves to be effective in outperforming the passive buy and hold strategy in the majority of the sectors. The sector decomposition of the cap-weighted S&P Global 1200 index which is employed as the market proxy, reveals that its sector allocation remains fairly stable throughout the study period. In contrast, the optimal historical sector composition incurs large changes in sector exposure from year to year and provides substantially superior performance relative to the cap-weighted market portfolio. The cap-weighted portfolio tends to overweight cyclical sectors and underweight resilient sectors during major economic downturns. The long-only, long-short and market neutral strategies developed from the S&P Global 1200 index and its constituent sector indices provide exceptional risk-adjusted performance, and more meanvariance efficient portfolios than the cap-weighted market proxy. The relaxation of the longonly constraint also improves the optimised portfolios risk-adjusted performance, mainly through risk reduction benefits. The performance of the optimised global sector based portfolios also resembles the performances of the global style based optimised portfolios developed by Hsieh (2010), thereby suggesting that the two approaches are analogous. The 3 technical market timing strategies tested in this research provide varying results. The sector momentum portfolios experience significant positive returns during bull markets, however the portfolios incur significant drawdowns during periods of economic turmoil such as the 2008 global financial crisis. As a result, all sector momentum portfolios provide inferior risk-adjusted returns relative to the passive cap-weighted buy and hold strategy. The exponential moving average (EMA) trend timing strategy promulgated by Hsieh (2010) provides impressive risk-management attributes and superior risk-adjusted performance relative to passive buy and hold benchmarks. Similarly, the alternative technical charting heuristics trend timing strategy helps reduce drawdowns during market crashes, however the charting strategy provides inferior cost and risk-adjusted performance relative to the capweighted buy and hold approach due to larger timing errors and longer hedging periods in comparison to the EMA strategy. In addition, the global tactical sector allocation (GTSA) model tests the EMA and technical charting trend timing tools in the context of a global sector portfolio, and the model provides outstanding cost and risk-adjusted performances relative to the passive investing alternatives. The portfolio based GTSA model highlights the benefits of portfolio diversification and successfully hedges market exposure during economic downturns.
Liaghati, Tania. "Trace metal geochemistry and weathering mineralogy in a quaternary coastal plain, Bells Creek catchment, Pumicestone Passage, Southeast Queensland, Australia". Thesis, Queensland University of Technology, 2004. https://eprints.qut.edu.au/15998/1/Tania_Liaghati_Thesis.pdf.
Texto completoLiaghati, Tania. "Trace metal geochemistry and weathering mineralogy in a quaternary coastal plain, Bells Creek catchment, Pumicestone Passage, Southeast Queensland, Australia". Queensland University of Technology, 2004. http://eprints.qut.edu.au/15998/.
Texto completoMattos, Igino Zucchi de. "Competição inter familiar: exchange traded funds e fundos de investimentos passivos". reponame:Repositório Institucional do FGV, 2011. http://hdl.handle.net/10438/8532.
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With the ETF going to be used for more sophisticated investors and with the possibility to go on to win representation, either for a passive strategy or strategy combined with more specialized and higher risk assets, this paper seeks to explain and justify the coexistence of these vehicles, which has similar goals, but with different structures. With this objective, the study seeks to analyze the behavior and the effectiveness of passive investment products-funds classified as ETF´s (acronym for Exchange-Traded Fund) and Passive mutual funds in the Brazilian market. Study seeks to benchmark, demonstrating differentiations of products from a technical point of view, validating the behavior of managers and product for final investors. Despite recent academic literature, the study seeks to elucidate potential opportunities and relevant aspects to investors. The objective doesn't include make comparison between active funds and ETF´s in Brazil, only display the figures - returns obtained - in recent periods. Concluding with numeric examples, ETF becomes an attractive to investors as harnessing their potential, the fact this with relevant developments in the markets of Europe and United States, mainly.
Com o ETF passando a ser utilizado por investidores mais sofisticados e com a possibilidade de passar a ganhar representatividade, seja para uma estratégia passiva ou para uma estratégia combinada com ativos de maior risco e mais especializados, este paper busca explicar e justificar a coexistência destes veículos, que tem objetivos semelhantes, mas com estruturas diferentes. Com este objetivo, o estudo busca analisar o comportamento e a eficácia dos produtos passivos de investimentos - fundos classificados como ETF´s (sigla para Exchange-Traded Fund) e Fundos Mútuos Passivos no mercado brasileiro. Buscamos avaliar comparativamente, demonstrando diferenciações dos produtos do ponto de vista técnico, validando o comportamento dos gestores em relação a gestão passiva e de produto para os investidores finais. Apesar de literatura acadêmica recente sobre a comparatividade, o estudo busca elucidar possíveis oportunidades e aspectos relevantes para os investidores. Não é objetivo deste trabalho fazer relação comparativa entre produtos ativos de ações e os ETF´s no Brasil, apenas detalharemos o retorno obtido nos últimos períodos. O trabalho demonstra, com exemplos númericos, que o ETF torna-se um instrumento atrativo aos investidores na medida do aproveitamento de suas potencialidades, fato este com evolução relevante nos mercados da Europa e Estados Unidos, principalmente.
Krepysheva, Natalia. "Transport anormal de traceurs passifs en milieux poreux hétérogènes : équations fractionnaires, simulation numérique et conditions aux limites". Avignon, 2005. http://www.theses.fr/2005AVIG0502.
Texto completoIn a number of disordered porous, solute spreading does not obey Fick's law. The latter describes the evolution of a plume of tracer. When initial data represent a local impulse, the concentration is a Gaussian variance is proportional to time. Experimental data obtained in aquifers have put into evidence qualitatively different behaviors, replacing Gaussians by stable Lévy densities, which also are non increasing functions. But in the large values asymptotics, they behave algebraically, and in general the second moment does not converge. Moreover, stable Lévy densities are the fundamental solutions of a wide class of partial differetial equations, which are space-fractional equations. They resemble heat equation, with the Laplacean being replaced by a derivative of non-integer order. They also rule the evolution of the concentration of a cloud of random walkers performing Lévy flights, wich are more general than Brownian motion, with the jump length density being a stable Lévy law. All these point are detailed in the thesis. The main results concern the spreading of matter in a semi-infinite medium where the motion of tracer particles is described by Lévy flights (on the small scale) except when they meet the boundary. With a reflexive wall, it is necessary to modify the kernel of the fractional derivative on the right hand-side of the equation ruling the evolution of the concentration of walkers. The theoretical result is illustrated by a Monte Carlo simulation, and compared with the numerical discretization of the fractional equation in a semi-infinite medium
Rigaud, Solange. "" La parure : traceur de la géographie culturelle et des dynamiques de peuplement au passage Mésolithique-Néolithique en Europe "". Phd thesis, Université Sciences et Technologies - Bordeaux I, 2011. http://tel.archives-ouvertes.fr/tel-00668694.
Texto completoTrommetter, Guillaume. "Développements analytiques et d’échantillonneurs passifs appliqués aux terres rares et platinoïdes : application aux systèmes aquatiques anthropisés". Thesis, Lille 1, 2020. http://www.theses.fr/2020LIL1R051.
Texto completoAquatic ecosystems are fragile systems, vital for the biosphere and yet subject to numerous, sometimes significant, anthropogenic pressures. Currently, reliable methods allow the quantification and study of the fate of metallic trace elements (Pb, Zn, Cd, etc.) and many organic micropollutants in water and sediments. For other elements such as rare earths or platinum group elements, which are increasingly used by industry, their quantification remains more complex and even uncertain due to their very low concentrations. Their quantification is practically impossible without the use of preconcentration techniques or the development of specific analytical methods to reduce the spectral interferences linked to interferents present in high concentrations in the environment. This research work has allowed (i) to quantify precisely these elements by inductively coupled plasma mass spectrometry combined with the use of a collision/reaction cell by judiciously choosing the gas and its flow applied in the cell ; (ii) to preconcentrate in situ and then determine concentrations ranging from pg L-1 to ng L-1 for platinum group elements, in areas impacted by human activities (road leaching, Pt-based drug releases), by developing passive sampling techniques called "Diffusive Gradients in thin films (DGTs)" based on the use of two different resins, and (iii) to better understand how some of these elements can be used as tracers of urban discharges, particularly in connection with wastewater treatment plants containing domestic and hospital discharges, in addition to the tracers usually used. To this end, the Marque River served as a pilot site for this prospective study during a period of low water levels. These studies made it possible to determine the current concentrations of rare earths and platinum in environments heavily impacted by human activities, making it possible to monitor their evolution and evaluate their potential impact in the future
Leisher, Thomas Kai. "Exchange-Traded Funds: The Unknown Investment Opportunity". Wittenberg University Honors Theses / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wuhonors1617280855446967.
Texto completoVystavna, Yuliya. "Déterminants environnementaux et socio-économiques, leur influence sur les métaux traces et les produits pharmaceutiques dans les cours d'eau : étude comparée sur deux rivières de France et d'Ukraine". Phd thesis, Université Sciences et Technologies - Bordeaux I, 2012. http://tel.archives-ouvertes.fr/tel-00716793.
Texto completoKummer, Larissa. "REMEDIAÇÃO DE SOLOS CONTAMINADOS POR METAIS PESADOS USANDO BIOSSURFACTANTE PRODUZIDO A PARTIR DE RESÍDUO AGROINDUSTRIAL". Universidade Estadual do Oeste do Parana, 2014. http://tede.unioeste.br:8080/tede/handle/tede/190.
Texto completoHigh concentrations of heavy metals in the soil can affect the sustainability of ecosystems and the health of humans and animals. The metal availability in the environment is related to the characteristics of each element, historical and source of contamination, as well as the properties of each soil. The presence of more than one element is common in contaminated areas and their interaction can affect their behavior in the environment. Researches have been developed to study the behavior of metals in different types of soils and thus help in cases of remediation. In recent years, the soil washing with biosurfactant has been presented as a promising method of remediation with little or no effect on the physico-chemical and microbiological characteristics of the soil, but the costs of obtaining this biosurfactant are still high, because most manufacturers use artificial means for production. Thus, this study had the objective of evaluating the remediation potential of the biosurfactant obtained from the fermentation of cassava water through the action of the bacteria Bacillus subtilis. This biosurfactant was characterized as surfactin, an anionic lipopeptide. Soils of different origins were used, one of them typical of the southwestern state of Paraná and the other from the northwest. The soils were first evaluated according to their potential for adsorption of the elements copper, zinc and lead in monometallic and multimetalic conditions, representing non-competitive and competitive conditions respectively. This evaluation was carried out by tests of adsorption and application of the matematical models of Langmuir and Freündlich. Soils were characterized chemically, physically and mineralogically. After that, it was performed the process of artificial contamination of these soils for application in the experiments of soil washing with biosurfactant in different conditions, having pH and concentration of biosurfactant solution as the main variables. Furthermore, it was also assessed the adsorption s capacity for metals by biosurfactant in liquid medium. The results showed that metals have different behaviors related to the adsorption and desorption to soil and to the biosurfactant. The soil type is also very important for the efficiency of metal removal. The clay soil showed higher adsorption capacity and therefore lower capacity of metal removal when compared to the sandy soil. In general, the soils showed the following sequence of adsorption capacity: Pb > Cu > Zn. The Pb was the element that less desorved by the washing process. It can also be concluded that, when soils are contaminated by more than one element at the same time, its ability to leach is greater than when the element is alone in the medium. This situation occurs because of differences between the competitive processes that take place in the active sites. The washing experiments showed that the biosurfactant was not able to improve the efficiency of removal of metals. The results obtained by the control treatments (only pure water) had very similar values to those that contained biosurfactant. When the wash solution containing the biosurfactant was in high concentrations, decrease in removel efficiency was found in some of the samples. Analysis of high performance liquid chromatography showed that the biosurfactant was adsorbed to soil samples, which is the consequence of not observing the effectiveness of the extractor in the removal of metals. It is notable, however, that the surfactin obtained has the potential to bind to metals, since the tests of adsorption to metals was confirmed by experiments. According to the results obtained, it can be inferred that the surfactin has greater potential for metal removal in liquid media than in solid medium, because of the lower possibility of adsorption. In soil, the results indicated potential use of this biosurfactant as stabilizing of metals in methods of remediation "in situ".
Concentrações elevadas de metais pesados no solo podem afetar a sustentabilidade dos ecossistemas e também a saúde dos seres humanos e animais. A disponibilidade do metal no ambiente está relacionada às características de cada elemento, histórico e fonte de contaminação, bem como às propriedades de cada solo. A presença de mais de um elemento em áreas contaminadas é comum e a interação entre eles pode afetar o seu comportamento no ambiente. Diante do problema, pesquisas vêm sendo realizadas a fim de estudar o comportamento dos metais em diferentes tipos de solos e assim auxiliar nos procesos de remediação. Nos últimos anos, a lavagem do solo com biossurfactante tem sido apresentada como um método promissor de remediação com pequeno ou nenhum efeito sobre as características físico-químicas e microbiológicas do solo, porém os custos de obtenção deste biossurfactante ainda são altos, pois a maioria dos fabricantes utiliza meios artificiais para sua produção. Neste sentido, este trabalho teve como objetivo geral avaliar o potencial de remediação do biossurfactante obtido a partir do bioprocessamento da manipueira pela ação de bactérias Bacillus subtilis. Este biossurfactante foi caracterizado como surfactina, um lipopeptídeo aniônico. Foram utilizados solos de origens distintas, sendo um deles típico da região sudoeste do estado do Paraná e outro da região noroeste. Os solos utilizados foram primeiramente avaliados de acordo com o seu potencial de adsorção dos elementos cobre, zinco e chumbo em condições monometálicas e multimetálicas, representando condições não-competitivas e competitivas, respectivamente. Esta avaliação foi feita por meio de testes de adsorção e aplicação de modelos matemáticos de Langmuir e Freündlich. Os solos foram caracterizados química, física e mineralogicamente. A partir de então realizou-se o processo de contaminação artificial destes solos para posterior aplicação dos experimentos de lavagem com o biossurfactante em diferentes condições, sendo as variáveis pH e concentração da solução de biossurfactante como as principais. Além disso, também foi avaliada a capacidade de adsorção dos metais pelo próprio biossurfactante, em meio líquido. Os resultados mostraram que os metais apresentam comportamentos distintos quanto a adsorção e dessorção ao solo e ao biossurfactante. O tipo de solo também é muito importante para a avaliação da eficiência de remoção de metais. O solo argiloso apresentou maior capacidade de adsorção e consequentemente menor capacidade de remoção dos metais quando comparado ao solo arenoso. De modo geral, os solos apresentaram a seguinte sequência de capacidade de adsorção: Pb > Cu > Zn. O Pb foi o elemento que menos dessorveu pelos processos de lavagem. Foi possível também concluir que quando os solos estão contaminados por mais de um elemento ao mesmo tempo, a capacidade de lixiviar-se é maior do que quando o elemento está sozinho no meio. Esta situação ocorre em virtude dos processos competitivos existentes entre os sítios ativos. Os experimentos de lavagem mostraram que o biossurfactante não foi capaz de melhorar a eficiência de remoção dos metais. Os resultados obtidos pelos tratamentos controle (somente água pura) tiveram valores muito semelhantes aos que continham biossurfactante. Quando a solução de lavagem continha o biossurfactante em altas concentrações, foi encontrada, em algumas amostras, queda na eficiência de remoção. Análises de cromatografia líquida permitiram concluir que o biossurfactante foi adsorvido às amostras de solo, sendo esta a consequência da não observação da eficácia do extrator na remoção dos metais. Cabe ressaltar, entretanto, que a surfactina obtida apresenta potencial de ligar-se aos metais, uma vez que os testes de adsorção desta aos metais foi confirmado pelos experimentos realizados. De acordo com os resultados encontrados, pode-se inferir que a surfactina tem maior potencial de remoção de metais em meio líquido do que em meio sólido, devido a menor possibilidade de adsorção na matriz sólida. Em solo, os resultados indicaram potencial de utilização deste biossurfactante como agente de estabilização dos metais em métodos de remediação in situ .
Rodts, Stéphane. "Etude du passage micro-macro pour le transport par diffusion en milieu poreux. Application aux expériences de RMN-GCP". Phd thesis, Ecole des Ponts ParisTech, 2001. http://tel.archives-ouvertes.fr/tel-00005684.
Texto completo1) Observer et identifier les mécanismes physiques via lesquels, dans les matériaux poreux homogènes, les lois microscopiques du transport par diffusion induisent généralement des lois de transport effectives macroscopiques très simples, quelque soit la complexité du réseaux poreux sous jacent.
2) Contribuer à développer le cadre d'interprétation des expériences RMN de Gradient de Champ Pulsé (GCP) pour la mesure de l'autodiffusion dans les fluides confinés dans les systèmes poreux.
Nous étudions le cas académique de la diffusion Fickienne sans adsorption. Nous observons le transport à échelle de longueur fixée, en suivant la cinétique avec laquelle "s'affaisse" par diffusion l'amplitude G(q,t) de "profils de concentration sinusoïdaux" de vecteur d'onde q variable. Vis à vis de la RMN cette approche revient à étudier le propagateur de diffusion G(q,t) - grandeur mesurée par l'expérience - de manière non traditionnelle, c'est à dire, à q fixé en fonction du temps t. A q donné, 3 régimes de temps sont mis en évidence : un régime de temps court de diffusion non confinée, un régime de temps intermédiaire renseignant sur la diffusion à l'échelle de longueur 2pi/q, et un régime de temps long sensible à la "dimensionnalité" de l'espace poral.
Nous caractérisons la cinétique d'affaissement aux temps intermédiaires par un coefficient e diffusion D(q). Son étude théorique et expérimentale en fonction de q dans des systèmes périodiques et/ou désordonnés simples fait apparaître clairement trois phénomènes lors du passage micro-macro : une première interaction avec l'interface, une différentiation brutale du rôle des différents pores, puis une diffusion anormale due à cette différentialité, susceptible de perdurer aux échelles macroscopiques, et suivie par un retour au régime "Fickien".
Une expérience macroscopique de traceur est enfin proposée et développée pour observer ces phénomènes de diffusion anormale dans quelques systèmes modèles.
Dubos, Thomas. "Cascade bidimensionnelle d'un traceur : diagnostic dans l'espace physique et modélisation". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2001. http://tel.archives-ouvertes.fr/tel-00007421.
Texto completoHafsaoui, Aymen. "Peformances de Niveau Applicatif en Environnement Filaire et sans Fil". Phd thesis, Télécom ParisTech, 2011. http://pastel.archives-ouvertes.fr/pastel-00669973.
Texto completoHennequin-Marot, Elisabeth. "Utilisation des réactions nucléaires (neutron, α) et (neutron, proton) pour la détection d'isotopes stables en biologie". Rouen, 1986. http://www.theses.fr/1986ROUES023.
Texto completoRoche, Agnès. "Mise au point et étude d'échantillonneurs diffusifs pour le suivi de l'exposition personnelle aux concentrations atmosphériques de benzène, toluène, éthylbenzène et xylènes BTEX et d'aldéhydes". Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE10018.
Texto completoBhurtun, Pratima. "Dynamique de la qualité des masses d’eau dans le bassin Artois-Picardie : compréhension des mécanismes actuels et prévision des évolutions dans un contexte de changement climatique". Thesis, Lille 1, 2018. http://www.theses.fr/2018LIL1R055.
Texto completoThe River Selle is a non-channelised stream in the Artois-Picardy basin and is considered as a priority waterbody by the Artois-Picardy Water Agency. The aim of this work was to study the spatio-temporal behaviour of several substances at different time scales, ranging from low-frequency (grab sampling, passive samplers) to high-frequency monitoring. More specifically, tracers of pollution reflecting urban, agricultural and industrial contamination (nitrates, phosphates, trace metal elements, pesticides, pharmaceutical residues, dissolved organic matter) were investigated. We confirmed that the River Selle is mainly fed by a nitrate-rich groundwater. Besides, the nitrates and atrazine concentrations in the river water were similar to those found in the groundwater. At the upstream of the river, the land-use is mainly dominated by agriculture whereas most of the urban islets are located at the downstream of the river. Consequently, during dry weather, ultra-trace concentrations of some pesticides and pharmaceutical residues were recorded and phosphate levels often exceeded 0.2 mg L-1. Due to the minor flow input of the wastewater treatment plants into the river, metallic contamination in the River Selle (particularly Gd and Zn) is quite low despite the high concentrations measured in wastewater effluents. Water quality issues during storm events were identified by high-frequency monitoring. Significant but time-limited peaks in phosphorus and organic carbon were observed, while nitrates were diluted. The composition of dissolved organic matter was studied by fluorescence spectroscopy. The spectral signature of different types of water (groundwater, surface water and wastewater effluents) was characterised as well as the origins of this organic matter (autochtonous vs allochthonous). Finally, these results enable to discuss qualitatively the future effects of climate change at a regional scale on the evolution of the water quality of the River Selle