Дисертації з теми "Trace de mobilité"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Trace de mobilité".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Costantini, Hervé. "La mobilité sociale : Modèles et traces." Phd thesis, Conservatoire national des arts et metiers - CNAM, 2012. http://tel.archives-ouvertes.fr/tel-00770978.
Повний текст джерелаTaneez, Mehwish. "Stabilisation d’un sédiment marin pollué en utilisant des résidus de bauxite : évaluation de la mobilité d’éléments trace." Thesis, Nice, 2016. http://www.theses.fr/2016NICE4036/document.
Повний текст джерелаMarine sediments concentrate various pollutants and subsequent sedimentation of harbors and ports require periodic dredging to maintain satisfactory depth of waterways. Direct land deposition of contaminated marine dredged sediments pose risk to the environment due to possible leaching of trace elements. In this context, we aimed to study the feasibility of trace elements stabilization by mixing 5% and 20% of bauxite residues (bauxaline®, bauxsol and neutralized bauxaline®) with composted dredged marine sediment. The treatment efficiency was evaluated by monitoring the leached trace elements concentration and toxicity of sediment leachates. 20% amendment application successfully stabilized cationic pollutants (Cu, Cd, Zn) up to 40-80%, and decreased the toxicity of sediment leachates. Whereas, anionic pollutants (As, Mo) were less immobilized require further investigation
Gounou, Catherine. "Mobilité des éléments traces métalliques dans les sédiments : couplage et comparaison des approches chimique et microbiologique." Thesis, Paris Est, 2008. http://www.theses.fr/2008PEST0074/document.
Повний текст джерелаAntropic activities lead to the metallic contamination of river sediments. Most of trace metals are sorbed on sediments but a part of them can be released into aquatic environment when environmental conditions are modified. This is often due by the autochthonous microbial activity. Microbial activites and their consequences on the mobility of metals have been widely studied in soils. Metals are released through direct or indirect microbial mechanisms. Such studies in the case of sediments are very seldom. However, it can be usefull to understand the microbial mechanisms of metal release in sediments, and particularly for a good management of dredged sediments. In this environmental framework, the aim of this research work was to understand and to evaluate the role of the microbial and chemical mechanisms in the release of metals from river sediments in anaerobic conditions. Firstly, sediments from the Marne and Seine rivers were incubated in anaerobic conditions. A high solubilisation of iron and manganese occurred associated to the solubilisation of trace metals (Co, Cu, Ni, Pb). Meanwhile, organic acids were produced and the medium was acidified. Thus fermentation was supposed to be the main process of microbial metabolism. Furthermore these observations led us to suppose the presence of iron-reducing bacteria. In a second step, the extent of the iron-reducing activity was studied. The main iron-reducing bacteria identified in the Marne sediments belonged to the species Clostridium butyricum and Paenibacillus polymyxa. The use of a geochemical model revealed that fermentation and reduction of iron(III) were the main metabolic pathways. Finally direct (enzymatic reduction) and indirect (complexation with organic acids, acidification) impacts of iron-reducing bacteria on the release of metals were compared. Acidification and organic acids had a weak impact on metal solubility in the range of studied pH (between 6,5 and 5). Enzymatic reduction is the main mechanisms of metal release in anaerobic conditions. Indeed the metallic concentrations can be 40 times higher in the presence of iron-reducing bacteria
Cayèré, Cécile. "Modélisation de trajectoires sémantiques et calcul de similarité intégrés à un ETL." Electronic Thesis or Diss., La Rochelle, 2022. http://www.theses.fr/2022LAROS042.
Повний текст джерелаOver the last decade, we have seen a rise in popularity of mobile applications based on phone location. These applications collect mobility tracks which describe the movement of users overtime. In the DA3T regional project, we hypothesise that the analysis of tourists’ mobility tracks can help planners in the management and enhancement of tourist areas. The objective is to design methods and tools to help analyse these tracks. This thesis focuses on the processing of mobility tracks and proposes a modular platform for creating and executing processing chains on these data. Throughout the modules of a processing chain, the raw mobility track evolves into semantic trajectories. The contributions of this thesis are: (i) a multi-level and multi-aspect semantic trajectory model and (ii) two measures that compute the similarity between two semantic trajectories along spatial, temporal and thematic dimensions. Our model (i) is used as a transition model between modules of a processing chain. We tested it by instantiating semantic trajectories from different datasets of various domains. Our two measures (ii) are integrated in our platform as processing modules. These measures present originalities: one is the combination of sub-measures, each allowing to evaluate the similarity of trajectories on the three dimensions and according to three different levels of granularity, the other is the combination of two bidimensional sub-measures centred around a particular dimension. We evaluated our two measures by comparing them to other measures and to the opinion of geographers
Marcel, Olivier. "Des horizons à la trace : géographie des mobilités de l'art à Nairobi." Thesis, Bordeaux 3, 2014. http://www.theses.fr/2014BOR30061.
Повний текст джерелаThis Ph.D. thesis tackles the places and circulations involved in the making of art in a southern metropolis. It is situated at the crossroads of an urban geography concerned with the social and spatial layout through which this “ordinary” activity is organized, and a geographical approach of art that places actors’ trajectories at the heart of the analysis. Capital city in a postcolonial State, East African metropolis and periphery of the “global archipelagic economy”, Nairobi is a case of the encounter between metropolization and globalization. In the trail of the theories on the worlding of material geography, this study aims at documenting and mapping the reconfigurations of art space triggered by these dynamics. The novelty of this thesis is to assemble the entire range of art scenes and products of a city, using the common thread that is the spatial dimension of their circulations. The material studied (artists’ discourse and curriculum vitae; art centres activity and archive) takes on both the measureable circulations of artists while confronting them to their horizon of accomplishment. These are made up of the persistence of strong rural ties and the connectivity of a globally connected city. The method deployed relies on the notion of traceability and is based on a qualitative survey through observation. An exhibition, a performance, a mobility grant, a visiting curator, collector or benefactor, the daily circulations and socializing of an artist: all these individual, material, ideal or financial movements constitute the raw material of this research. The notion of art mobility is here understood as the articulation between artists’ agency and spatial tactics on the on hand, and the material and institutional means of dealing with distance on the other hand. Art mobility questions the conditions, directions and meanings of these movements as much as the growth of the actors engaged
Tessier, Erwan. "Diagnostic de la contamination sédimentaire par les métaux/métalloïdes dans la rade de Toulon et mécanismes controlant leur mobilité." Thesis, Toulon, 2012. http://www.theses.fr/2012TOUL0003/document.
Повний текст джерелаThis study deals with the assessment of sediment contamination levels by trace metals in the Toulon bay, a semi-closed Mediterranean area submitted to heavy anthropogenic inputs. The sampling of interface cores in 52 points located in thewhole bay allowed establishing a precise mapping of the sedimentary characteristics and the metals/metalloids contents. The obtained results from the surface sediments revealed a significant contamination of the bay (especially for Cu, Hg, Pb and Zn), mainly in the most enclosed parts of the small bay. There, the levels may exceed by several orders of magnitude the limits concerning dredging operations defined by the French legislation. The observed contamination distribution clearly indicated an export from the small to the large bay (normally less exposed) probably governed by hydrodynamic processes, responsible for the contaminated sediment resuspension. The sedimentary profiles of interface cores sampled in contrasted contamination areas revealed the presence of systematic contamination peaks in the first 20 cm. Taking into account the calculated sedimentation rate, this would demonstrate that the Toulon bay was submitted to a strong multi-contamination, probably linked to the 2nd world war. The analysis of interstitial waters (physico-chemical parameters,major, trace metals, and diagenetic tracers) allowed studying trace metals mobility. The obtained profiles appeared mainly controlled by diagenetic mechanisms and showed the major role of the main carrier phases present in the sediments (oxyhydroxides of Fe and Mn, sulphides). The modeling of these profiles led to the determination of the diffusive fluxes at the sediment/water interface, and so, to the action of the sediment as a sink or a source of contamination for the water column.The calculated outgoing diffusive fluxes appeared relatively low in comparison to the total contents measured in the sediment, proving that the main part of the studied trace metals remains in the sediment. Finally, resuspension experiments in lab and on field were performed with the aim to simulate different possible scenarios (storm,nautical traffic, dredging). Under the studied conditions, the remobilization can be low for some trace metals (e.g. As, Hg), but it may contrariwise be quite important for others (e.g. Cd, Cu, Pb) leading to a non-negligible contamination of the water column
Abi, ghanem Carine. ""speciation" des trois elements trace mercure, plomb et cadmium dans les sediments marins des zones cotieres libanaises." Phd thesis, AgroParisTech, 2008. http://pastel.archives-ouvertes.fr/pastel-00005015.
Повний текст джерелаSivry, Yann. "Utilisation des isotopes stables de Cd, Zn, Cu, Ni et Pb pour quantifier le compartiment échangeable des éléments trace métalliques et de δ66Zn pour tracer les contaminations polymétalliques". Phd thesis, Université Paul Sabatier - Toulouse III, 2008. http://tel.archives-ouvertes.fr/tel-00375351.
Повний текст джерелаNafeh, Kassir Lina. "Les métaux lourds dans les engrais phosphatés et les sulfates rejetés par les industries des fertilisants : recherche sur leur transfert et leur mobilité dans les sols libanais." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0332/document.
Повний текст джерелаTo determine the impact and risk of chemical fertilizers, from their manufacture to their amendment, on soil contamination by trace metals, the study of their mobility and transfer would be necessary. The objective of this work was to evaluate the source of soil contamination by trace elements around the industry of chemical fertilizers, and to follow the temporal evolution of mobility and transfer of these elements in the profile of agricultural soil amended by superphosphate (SSP) fertilizers or phosphogypsum. To achieve our objective, we used techniques allowing the determination of structural and mineralogical characterization of collected soil samples, such as X-ray diffraction and electron microscopy. Chemical characterization related to the total concentration of trace and major elements of collected soils was established. As mobility was unstable over time, depending on several physico-chemical parameters such as pH, redox potential, and organic matter content, a sequential extraction was adopted throughout the study over time in the amended soil profile to a depth of 55 cm. In addition, the absorption of trace elements by agricultural crops cultivated over land amended with fertilizer or phosphogypsum was analyzed over time to assess the risk of their transfer to the food chain, especially the human food chain, imposing health hazards. A comparison between the effects of the application of phosphogypsum and phosphate fertilizer was carried out in concluding this work
Qasim, Bashar Hussein. "Détermination, spéciation et biodisponibilité des éléments traces métalliques dans les sols contaminés et technosols." Thesis, Orléans, 2015. http://www.theses.fr/2015ORLE2069/document.
Повний текст джерелаThis thesis dealt with the determination and study of the ecodynamics of trace metals in technosols highly contaminated in metals and metalloids in the context of natural revegetalisation or phytoremediation. Two sequential extraction schemes were used jointly with selective extractions in parallel with the determination of the total metals concentration in soils, the total dissolved metals concentration in the soil pore water, the metals labile pool (DGT) and germination tests with dwarf beans to investigate the speciation, mobility and phytoavailability of (Zn, Pb, Cd, As and Sb) for technosols of two post-mining (La Petite Faye) and industrial (Mortagne du Nord) sites. Additionally, young plants of P. euramericana Dorskamp were cultivated in rhizobox on Mortagne du Nord technosols to investigate the rhizospheric effect on the mobility of metals. Moreover, the effect of nitrogen addition under nitrate and ammonium on the behavior of these metals has been investigated for P. euramericana Dorskamp for the same soils. Despite the high total metals and metalloids concentration in the La Petite Faye soils, the mobility of these potentially toxic elements is limited because of their association with the residual fraction. The phytoavailability is also limited and correlated with the labile pool of technosols. The culture of P. euramericana Dorskamp generated a rhizospheric effect characterized by an increase of the pH and concentration of dissolved organic carbon (DOC) in the soil pore water and a decrease in the total dissolved concentration of metals (Zn, Pb et Cd) in the soil pore water. The addition of nitrogen under nitrate or ammonium respectively increased and decreased the soil pore water pH and in the case of ammonium the DOC also increased and stabilized metals in the rhizosphere in comparison to control soils
Sivry, Yann. "Utilisation des isotopes stables de Cd, Zn, Cu, Ni et Pb pour quantifier le compartiment échangeable des éléments trace métalliques et de delta66Zn pour tracer les pollutions polymétalliques." Toulouse 3, 2008. http://thesesups.ups-tlse.fr/471/.
Повний текст джерелаA multi-elementary spiking method has been is developpeddeveloped in order to simultaneously quantify and caracterizecharacterize simultaneously the labile pools fraction of Cd, Zn, Ni, Cu and Pb in contaminated soils. This method is has been validated by comparison with 1) radioactive Cd spiking data,g Cd and of2) chemical extractions results. In additionFurthermore, an integrated study of Zn isotopic signatures (d66Zn) in various compartments pools of two contaminated ecosystems (zinc smelting sites of Viviez-Decazeville, S. -W. Of France and of Kempen, N. -E of Belgium) has been performed allowing the identification of various allows to assume a coherent scheme of Zn isotopic fractionations during associated to the metallurgical processes. The differents d66Zn ratio observed in between "enriched" and "residual" zinc would be a powerfull tool to identify the metallurgical contaminations origins. These results demonstrate the efficiency of stable isotopes as tracers for contamination processes and sourcescontaminations tracers
Testiati, Eti. "Contamination de sols par des éléments traces métalliques en zone méditerranéenne côtière : études de leur mobilité et du transfert à la phytocénose." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4804/document.
Повний текст джерелаThe overall objective of this thesis was to contribute to the assessment of the level of contamination by trace metals and metalloids (TMM) on the site of Escalette (a former lead smelter in southeastern Marseille). The study of TMM transfer and transport processes on this site, taking into account their mobility in the soil and their transfer to plants, was a specific objective. The mapping of TMM contamination in an extended area around the factory site (on Calanques zone) has clearly highlighted the impact of the former industry. So, on the Escalette site, forms and levels of soil contamination differ from one area to another. Soils formed on the surface of the slag deposits are characterized by high levels of Cu, Zn and Pb, whose mobilizable fractions are significant (2-30%), showing a clear influence of slag. Soils collected near a chimney creeping uphill the slope, present the highest contamination levels in Pb, Sb and As, with from 10 to 30 % of mobilizable fractions. This contamination is linked to emissions through the damaged chimney but also to the degradation of this latter. The potential release of As and Sb from the soils of these two areas requires that these soils must be disposed of in landfills for hazardous wastes and their solubilization in acid medium have highlighted the health risks by ingestion for Pb and As. On areas in near periphery of the smelter, soils are less affected but must be still considered heavily contaminated. G. alypum and R. officinalis were observed on the site. They are tolerant and can accumulate TMM. Concentrations in roots were significantly correlated with the concentrations in soils, except for Cu
Pontoni, Ludovico. "Accumulation and colloidal mobilization of trace heavy metals in soil irrigated with treated wastewater." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1144/document.
Повний текст джерелаReuse of treated wastewater for agricultural purposes is worldwide accepted and practiced to face water scarcity and save high quality resources. Although such practice has undoubtable advantages and is certainly more sustainable respect to the use of fresh water, it is not exempt from severe concerns related to the potential impact on the receiving soil and on the crops of potentially harmful pollutants contained in the reused water at trace levels. Among these pollutants, trace heavy metals (HMs) play a primary role due to their spread presence in the used water and to their persistence once released in the environment. The fate of HMs in the soils can be hardly predicted as mechanisms of mobility through soils are extremely diverse and related to highly complex simultaneous phenomena and chemical equilibria. HMs, in fact, as many other contaminants, are not only partitioned between the solid immobile and the water mobile phases. Indeed, colloids and nanoparticles act as a third mobile phase, with their own rheological properties and velocity. This latter aspect has been one of the main focus of the thesis. In details the thesis describes the results of several experiments conducted irrigating the OECD standard soil with real and/or synthetic wastewater, containing HMs in trace. For each test a specific soil (e.g. varying the organic matter content) and wastewater composition (e.g. varying the metals concentration, the salinity, the organic matter content, or testing real treated wastewaters) has been chosen in order to evaluate the effects of different conditions on the overall HMs fate. The increase of soil organic matter from 2,5 to 10% linearly enhanced the mobility of Cd, Cu and Ni up to a maximum mobility increase of 35.6, 43.7 and 49.19 % for Cd, Cu and Ni, respectively. In most experiments metals accumulated in the top soil layer (0.5 - 1 cm). Nevertheless peaks of contamination were detected at different depths in the soil deeper layers and at different leaching time in the leachates depending on the metal and on the soil and wastewater characteristics. Peaks of metals in the leachate appeared simultaneously with release of organic matter and/or release of silicates, demonstrating outstanding involvement of colloids in metals transport. Sodium concentration (20mM) decidedly reduced colloidal mobilization whereas more than 95 % of the influent metal was detected in the top layer despite the soil organic matter content. Salinity displayed different effects. The irrigation with real treated wastewater with quite high content of Ca and Mg (111 and 134 mg/L, respectively) resulted in higher average release of silicon from the soil inorganic matrix (8.2 mg/L) compared to the low salinity artificial wastewater (1.9 mg/L). Consequently higher mobilization of Cd, Cu, Ni and Zn was observed when the soil was irrigated with real treated wastewater. An advanced spectroscopical characterization of the leachates was performed to identify such colloidal aggregates. The observation of 3D excitation-emission matrix demonstrated in all the leachates samples the presence of fulvic (230-450 nm ex-em fluorescence area) and humic (330-445 nm ex-em) substances. In this context, a novel analytical method was developed to quantify phenolic substances in soil matrices allowing the monitoring of humic matter migration in soil profiles. The novel method was more accurate and more precise respect to the traditional one, allowing to obtain higher recovery of total phenols in peat soil (15.5 % increase) with a decrease of the coefficient of variation (30.1% decrease). Organic water soluble colloids were extracted from the peat used to prepare the OECD standard soil and characterized. Results of size exclusion chromatography highlighted the supramolecular structure of the extracted organic matter. Such structure was further confirmed through fluorescence and 1H-NMR spectroscopy
Varrault, Gilles. "Étude cinétique de l'extraction des métaux traces des sols : application à l'évaluation de l'efficacité de techniques de réhabilitation in situ." Paris 7, 2001. http://www.theses.fr/2001PA077156.
Повний текст джерелаMerrot, Pauline. "Géochimie, spéciation et mobilité des éléments traces métalliques (Fe, Ni, Cr et Mn) au sein des sédiments du lagon de Nouvelle-Calédonie." Electronic Thesis or Diss., Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2019SORUS551.pdf.
Повний текст джерелаNew Caledonia is covered on 33% of ultramafic rocks enriched in trace metals elements (Fe, Ni, Cr, Mn and Co). The erosion of these massifs represents an important source of these trace metals towards the lagoon, partially registered on the World List Heritage by UNESCO for its biodiversity. Understanding the geochemical cycle of these toxic trace metals is essential to evaluate the potential impacts on the biodiversity of this ecosystem. X-ray absorption spectroscopy (XAS) has shown that the contribution of iron sulfides is low, Ni and Fe are bearing by goethite and clays. These latter minerals representing the major phase for the Fe and Ni speciation were identified as chrysotile and green clays: a smectite (nontronite), a mica (glauconite) and a serpentine like a greenalite/berthierine. The clay minerals cycle and the green clay plays a major role in the Fe and Ni cycle, but also in Mn and to a lesser extent in the Cr cycles. The Mn speciation is shared by the clay minerals and the carbonates species whereas Cr is bearing by goethite and chromite inherited of laterite and in lesser extent by clay minerals. Cr is totally present under the reduced form which is the less toxic form. This absence of Cr(VI) is linked to the absence of Mn oxides in sediments avoiding the oxidation of Cr(III) to Cr(VI) and thus limits the impact on the environment. Finally, the chemical extractions of these metals show a relatively low bioavailability of trace metals except for Mn implying an effective long-term trapping for trace metals and thus limiting the environmental impacts even if the concentrations extracted are not negligible and can be threaten the biodiversity of the lagoon
Drapeau, Clémentine. "Mesure et modélisation de la mobilité et de la spéciation des éléments majeurs et traces métalliques au sein de matrices complexes polluées en fonction du pH : application aux sédiments urbains et déchets miniers." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSET007/document.
Повний текст джерелаUrban sediments and mine tailings constitute two potential sources of pollution for the environment, especially surface water or groundwater. The chemical alteration of these solid matrices by contact with a source of acidity or alkalinity via air or water is likely to result in the dissolution of the mineral and organic phases and to induce the mobilization of majors and trace elements. These mechanisms are still poorly described and modeled for this type of very complex matrices. This thesis investigates potential for the mobilization of major and trace metals elements of various contaminated complex matrices, including an urban infiltration basin sediment and two carbonated and non-carbonated mining waste (for the study of contaminated acid mining drainage and contaminated neutral drainage). Besides, pure minerals were used to simulate phase mixture at the laboratory and identify the crossed mechanisms involved in contaminated acid and neutral mine drainage. All these matrices were subjected to acid-base neutralization capacity tests (solids put into contact with a source of protons or alkalinity), with monitoring of the pH (buffer capacity), the conductivity and the elemental release (major and trace metal elements). Experimental data were modeled with the PHREEQC geochemical speciation software. The combination of experimental and modeling approaches, which had very rarely been developed on such complex solid matrices, allowed the identification of (i) the dissolution reactions of the constitutive phases of the polluted matrices with the sorption reactions involved in the mobilization of their major and trace metal elements, (ii) the speciation of the major and trace metal elements in these matrices and in solution in equilibrium with the solid phases. This thesis, therefore, leads to a robust, precise and replicable methodology allowing a fine characterization of liquid and solid phase speciation of metallic pollutants in contaminated matrices. This methodology constitutes a crucial basis for understanding and predicting the evolution of contaminated solids (urban sediments and mining waste) according to different management methods: decontamination, recovery, and recycling
Al-Sid-Cheikh, Maya. "Impact des oxydes de fer naturels et des nanoparticules manufacturées sur la dynamique des éléments traces dans les sols de zones humides." Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S144.
Повний текст джерелаNanoscience is based on changes in particle properties when their diameter is below 100 nm (ie nanoparticles, NPs). Considering the increasing use of such NPs and their discharge into the environment, the assessment of their risks to human health and the environment is a major issue. Underneath the protection of waters and soils, the surface water assessment quality is particularly important, especially in wetlands, where the toxic metals dynamic (e.g. As, Pb, Ni, Cr , Hg) is complex and depends on the redox conditions of the environment. As magnetite (nano-Fe3O4), a natural or manufactured NP, is known for its significant adsorption capacity with heavy metals, their interactions in riparian wetlands with trace metals (TMs) remain critical concerning their direct of indirect impact on trace metals (TMs) mobility. The objective of this thesis was to study the role of manufactured nano-Fe3O4 (~ 10nm) and natural iron oxides on the TMs dynamics in wetland surface waters and soils. Therefore, in a first part considering natural colloidal precipitates from reoxidation products from riparian areas (subject to redox oscillations), a spatial distribution of elements was performed using nanoSIMS isotope mapping (i.e. 75As-, 56Fe16O-, sulfur (32S-) and organic matter (12C14N-), while the sulfur speciation was evaluated X-ray adsorption at K edge of the sulfur (S) (XANES). These analyzes allowed to highlight the interactions between natural iron oxides, natural organic matter (NOM) and a toxic metalloid, As. Our results suggest, with a statistical colocalization of nanoSIMS images, the existence of two interaction types: (1) 12C14N-, 32S-, 56Fe16O- and 75As-, and (2) 12C14N-, 32S- and 75As-. The coexistence of the oxidized and reduced forms of S, confirmed by the XANES analyses might be attributed to the slow oxidation kinetic of MON. Thus, this first part shows that in addition to the known interactions between MON, iron oxides and As, a possible direct interaction between As and NOM through sulfur functional groups (e.g. thiols) are also possible in oxidized environment. In a second part, the effect of nano-Fe3O4 (~ 10 nm) on trace elements (TEs) and colloids mobility in the organomineral horizon of a natural wetland soil was assessed using soil columns. Our results show that the nanoparticles coating influences the mobility of NOM and TMs. Indeed, the TMs mobility increases in presence of naked nano-Fe3O4, suggesting associations where NOM stabilizes the nanoparticles and increase the nanoparticles and associated TMs mobility. This mechanism seems less possible with coated nano-Fe3O4 where MON blocks the coating adsorption sites and therefore the adsorption of metals
Smolinski, Jan. "Une consommation mobile numérisée : suivi des pratiques marchandes assistées avec un smartphone et adaptation des méthodes de recherche." Thesis, Toulouse 2, 2018. http://www.theses.fr/2018TOU20106.
Повний текст джерелаFrom the 1990s onwards, walking spaces gradually integrated digital communication media, creating and thus establishing a continuous flow of information. In this ecosystem, digitally equipped users have gained new powers of interaction with the places they pass through. The smartphone that connects physical space to digital architecture is a mobile medium of choice. Observing it provides the means to show how ubiquitous computing can transform consumers’ mobile experiences. Examining market exchanges occurring in the context of physical-digital mobility amounts to analyzing how digital technologies transform distribution and consumption patterns. The walking space witnesses the accentuation of one-to-one targeting (Peppers and Rogers, 1999), the advent of self-marketing (Cochoy, 2012) and adaptations and improvisations emerging from the course of action. Observing mobile practices requires survey methods capable of capturing moving uses, including the collection of digital traces. Three surveys took digital traces as the way to study mobile digital uses: recording mobile Internet traffic of young adults; extracting logs from advertising campaign using the QR Code system; using a mobile application during a tourist exploration. These fields have also been used to question the use of digital traces in social sciences. The conclusion is that it is worthwhile to use composite methods to make sense of digital traces and clear the grey areas that appear when working on digital data
Kathe, Claudia. "Improving mobility after corticospinal tract injury." Thesis, King's College London (University of London), 2016. https://kclpure.kcl.ac.uk/portal/en/theses/improving-mobility-after-corticospinal-tract-injury(ca3be9d6-a198-42ef-bb32-ab28a59e273c).html.
Повний текст джерелаTon, That Dai Hai. "Gestion efficace et partage sécurisé des traces de mobilité." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLV003/document.
Повний текст джерелаNowadays, the advances in the development of mobile devices, as well as embedded sensors have permitted an unprecedented number of services to the user. At the same time, most mobile devices generate, store and communicate a large amount of personal information continuously. While managing personal information on the mobile devices is still a big challenge, sharing and accessing these information in a safe and secure way is always an open and hot topic. Personal mobile devices may have various form factors such as mobile phones, smart devices, stick computers, secure tokens or etc. It could be used to record, sense, store data of user's context or environment surrounding him. The most common contextual information is user's location. Personal data generated and stored on these devices is valuable for many applications or services to user, but it is sensitive and needs to be protected in order to ensure the individual privacy. In particular, most mobile applications have access to accurate and real-time location information, raising serious privacy concerns for their users.In this dissertation, we dedicate the two parts to manage the location traces, i.e. the spatio-temporal data on mobile devices. In particular, we offer an extension of spatio-temporal data types and operators for embedded environments. These data types reconcile the features of spatio-temporal data with the embedded requirements by offering an optimal data presentation called Spatio-temporal object (STOB) dedicated for embedded devices. More importantly, in order to optimize the query processing, we also propose an efficient indexing technique for spatio-temporal data called TRIFL designed for flash storage. TRIFL stands for TRajectory Index for Flash memory. It exploits unique properties of trajectory insertion, and optimizes the data structure for the behavior of flash and the buffer cache. These ideas allow TRIFL to archive much better performance in both Flash and magnetic storage compared to its competitors.Additionally, we also investigate the protect user's sensitive information in the remaining part of this thesis by offering a privacy-aware protocol for participatory sensing applications called PAMPAS. PAMPAS relies on secure hardware solutions and proposes a user-centric privacy-aware protocol that fully protects personal data while taking advantage of distributed computing. For this to be done, we also propose a partitioning algorithm an aggregate algorithm in PAMPAS. This combination drastically reduces the overall costs making it possible to run the protocol in near real-time at a large scale of participants, without any personal information leakage
Chua, Swee Teen. "Capital mobility, trade, growth and the environment." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324971.
Повний текст джерелаYang, Yingxiang S. M. Massachusetts Institute of Technology. "Understanding human mobility patterns from digital traces." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82863.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (pages 93-102).
Our current digital age is characterized by the shift from traditional industry to an economy based on the information computerization. The sweeping changes brought about by digital computing have provided new data sources for transportation modeling. In this thesis, two mainstream trends in utilizing digital traces in transportation modeling are explored. The first approach is to incorporate mobile phone records and digital map point of interests into commuting flow prediction models such as the gravity model and the radiation model. An extension to the radiation model is proposed to adjust to the different degrees of homogeneity of opportunities when the scale of the study region changes. The density of the point of interests is a suitable proxy for commuting flow attraction rates at all the scales. Moreover, the parameter a in the extension to the radiation model is predictable given the size of the study region. When traditional data sources are not available, mobile phone records is shown to be an ideal alternative. Home and work locations can be inferred at individual level and then aggregated to show its equivalence to the census data. This method is applied to Rwanda, Dominican Republic and Portugal. The second approach is using low-frequency bus GPS records to evaluate transit service. The analysis under such data scarcity requires careful data handling. This thesis demonstrates that how the data pre-processing procedure, namely map-matching and kernel density estimation, step by step turns the raw GPS data into information for service evaluation. Bus service quality is analyzed by measuring statistics of headway and in-vehicle travel time. The headway analysis helps to identify bottlenecks caused by the road network layout and passenger volumes while the comparison of peak vs. off-peak hour travel speed helps to identify bottlenecks caused by traffic conditions. To sum up, the thesis explores new digital data sources and methods in transportation modeling. The purpose is to provide analysis procedures that are of lower costs, higher accuracy and are readily applicable to different countries in the world.
by Yingxiang Yang.
S.M.in Transportation
Ivanovic, Stefan. "Quality based approach for updating geographic authoritative datasets from crowdsourced GPS traces." Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC1068/document.
Повний текст джерелаNowadays, the need for very up to date authoritative spatial data has significantly increased. Thus, to fulfill this need, a continuous update of authoritative spatial datasets is a necessity. This task has become highly demanding in both its technical and financial aspects. In terms of road network, there are three types of roads in particular which are particularly challenging for continuous update: footpath, tractor and bicycle road. They are challenging due to their intermittent nature (e.g. they appear and disappear very often) and various landscapes (e.g. forest, high mountains, seashore, etc.).Simultaneously, GPS data voluntarily collected by the crowd is widely available in a large quantity. The number of people recording GPS data, such as GPS traces, has been steadily increasing, especially during sport and spare time activities. The traces are made openly available and popularized on social networks, blogs, sport and touristic associations' websites. However, their current use is limited to very basic metric analysis like total time of a trace, average speed, average elevation, etc. The main reasons for that are a high variation of spatial quality from a point to a point composing a trace as well as lack of protocols and metadata (e.g. precision of GPS device used).The global context of our work is the use of GPS hiking and mountain bike traces collected by volunteers (VGI traces), to detect potential updates of footpaths, tractor and bicycle roads in authoritative datasets. Particular attention is paid on roads that exist in reality but are not represented in authoritative datasets (missing roads). The approach we propose consists of three phases. The first phase consists of evaluation and improvement of VGI traces quality. The quality of traces was improved by filtering outlying points (machine learning based approach) and points that are a result of secondary human behaviour (activities out of main itinerary). Remained points are then evaluated in terms of their accuracy by classifying into low or high accurate (accuracy) points using rule based machine learning classification. The second phase deals with detection of potential updates. For that purpose, a growing buffer data matching solution is proposed. The size of buffers is adapted to the results of GPS point’s accuracy classification in order to handle the huge variations in VGI traces accuracy. As a result, parts of traces unmatched to authoritative road network are obtained and considered as candidates for missing roads. Finally, in the third phase we propose a decision method where the “missing road” candidates should be accepted as updates or not. This decision method was made in multi-criteria process where potential missing roads are qualified according to their degree of confidence. The approach was tested on multi-sourced VGI GPS traces from Vosges area. Missing roads in IGN authoritative database BDTopo® were successfully detected and proposed as potential updates
Ruggieri, Flavia. "Environmental mobility of potentially toxic trace elements of Andean volcanic ashes." Doctoral thesis, Universitat de Barcelona, 2011. http://hdl.handle.net/10803/39082.
Повний текст джерелаLockwood, Cindy Louise. "Biogeochemical processes and trace element mobility in alkaline waste affected soils." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7555/.
Повний текст джерелаGómez, Tello Alicia. "The european integration process: trade, mobility, and policy." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/384937.
Повний текст джерелаThe European Union is experiencing one of the most complete integration process in the world. Nevertheless, there still exist important social and economic differences among its member states, and these differences could limit the positive effects associated with the integration process. The objective of this dissertation is to examine the benefits and drawbacks of a number of selected features entailed by the European integration process. We focus on three specific aspects: trade integration among EU member states, the free mobility of capital and workers, and the true effectiveness of the Common Agricultural Policy (CAP). In Chapter 2, “What Are the Most Important Partners of the Most Recently Admitted EU Countries,” we investigate whether the fifth EU enlargement (2004) truly generated a trade integration effect for new member states (EU-10). To tackle this question, we build a database by compiling the information referring to trade flows among EU-10 countries and 180 commercial partners during 1999–2011. Though our results show that trade flow intensity between EU-15 and EU-10 countries increased after 2004, the trade integration effect was much stronger within the EU-10 group. This finding confirms that the historical background of EU-10 countries conditioned their trade integration with EU-15 countries, especially in sectors with more technological content. The Chapter 3, “Foreign Direct Investment and Immigration Inflows in Spain,” investigates the determinants of foreign direct investment (FDI) in Spain. This country lost part of its principal attractiveness as an FDI recipient after the EU enlargements to the east. We provide a quantitative assessment of the importance of agglomeration economies, network effects, and labor market composition in attracting FDI. To conduct our analysis, we create a novel database after adapting and merging information from two micro-data sources: one for companies and the other for workers. Our results highlight that incoming foreign investors privilege the hiring of medium-skilled workers rather than high-skilled ones, as is often found in the empirical research of FDI determinants. This result reveals the existence of structural problems in the Spanish business environment—namely, foreign investors are principally attracted by monetary or transitory incentives that make the interest to locate in Spain a temporally limited strategy. Unfortunately, this situation prevents Spain from building and enjoying a qualified business environment that could be able to attract more long-term FDI. Finally, in Chapter 4, “Land Specialization in Spain: The Effects of the Common Agricultural Policy,” we investigate the extent to which the CAP affected the level of agricultural production in Spain. Following Costinot and Donaldson (2012), the pivotal technique of our strategy involves comparing actual output with potential output, the latter of which derives from an optimization problem relying on the Ricardian idea of opportunity cost. Ultimately, our results identify an improvement of the agricultural production efficiency after Spain entered the European Economic Community (1986) and, above all, after the Fischler reform (2003). The 2003 CAP reform broke the linkage between subsidies and production. This provided the right incentives to impulse real production in Spain since made production strategies more connected with the market devices than subsidy requirements. Overall, although our research quantifies the existence of positive effects associated with the European integration process, we also detect specific circumstances in which the effects of integration have been different from the expected ones. However, these weaknesses—most of them associated with the lack of strong economic ties among all member estates—need to be overcome in order to allow the European project progress.
Spilimbergo, Antonio. "Three essays on trade, growth, and labor mobility." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/11954.
Повний текст джерелаAggarwal, Jugdeep K. "The mobility of trace elements and boron isotopes in Icelandic hydrothermal systems." Thesis, University of Bristol, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294571.
Повний текст джерелаSaunders, Ruth. "Investigations of processes controlling trace element mobility in Scottish freshwater loch sediments." Thesis, University of Edinburgh, 2003. http://hdl.handle.net/1842/12901.
Повний текст джерелаBotes, Paul Johannes. "Investigation of mobility of trace elements in river sediments using ICP-OES." Pretoria : [s.n.], 2003. http://upetd.up.ac.za/thesis/available/etd-01182005-091457.
Повний текст джерелаPoole, Jennifer Pamela. "Mobility and information flows in international trade and investment." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3277677.
Повний текст джерелаTitle from first page of PDF file (viewed October 10, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 104-109).
MENGHI, MARTA. "Containers off the track, abitare la mobilità tra logistica ed emergenza." Doctoral thesis, Università degli studi di Genova, 2020. http://hdl.handle.net/11567/1009920.
Повний текст джерелаTolu, Julie. "Spéciation et mobilité du sélénium présent dans les sols à l’état de traces : contribution aux prévisions à long terme." Thesis, Pau, 2012. http://www.theses.fr/2012PAUU3002/document.
Повний текст джерелаA radioactive isotope of selenium was shown to be among the most critical radionuclide forsafety assessment of high level and long lived nuclear waste repository in case of hypotheticalsoil contamination. A methodology was thus developed to determine Se species (speciation)present in soils at trace level (μg kg-1; radiological context) in assessing their leaching andretention phases (distribution). Combined to a 77Se(IV) tracer, kinetically limited processes were shown to be involved in Se retention and chemical transformations in soils, suggesting that native Se behavior is particularly relevant for its long term mobility assessment and modeling. The investigation of native Se speciation and distribution in 29 soils has finally highlighted that soil organic matter impact the nature of Se species susceptible to be leached (organic and colloidal compounds) and the Se mobility (Se stabilization in solid phase via organo-mineral associations)
Pham, Cong S. "Three essays on the mobility and determinants of trade patterns." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2005. http://catalog.hathitrust.org/api/volumes/oclc/76945245.html.
Повний текст джерелаLima, Antonio. "Digital traces of human mobility and interaction : models and applications." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6833/.
Повний текст джерелаSukkariyah, Beshr. "Trace Metals Mobility in Soils and Availability to Plants from a Long-Term Biosolids Amended Soil." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/11098.
Повний текст джерелаPh. D.
Schneider, Arnaud. "Comportement et mobilité des éléments traces métalliques dans des sols environnant une usine de seconde fusion du plomb. Approches expérimentales et modélisation." Thesis, Reims, 2016. http://www.theses.fr/2016REIMS043/document.
Повний текст джерелаThe soil contamination by trace elements (TE) is a major environmental issue which mainly lies in their potential transfers from soils to surface and ground waters and/or to food chain.The main objective of this study was to understand the behaviour of TE in impacted soils located in the vicinity of a lead-acid battery recycling plant (Ardennes, France). In a 17 ha surrounding area, the spatial distribution of TE was performed using portable X-ray fluorescence. It indicated that the soils were mainly contaminated by Pb and, to a lesser degree, by Cd, Cu, Ni, Sb, Sn and Zn. A geostatistical approach enabled to discriminate the natural or anthropogenic sources of most of these TE.Based on the TE mapping, the soil type and the land cover, the behaviour of the TE was studied along six soil profiles. The calculated partition coefficients highlighted a high mobility of the TE which is related to the acidic soil conditions (pH 4-5). Regardless of the studied soil profile, Cd exhibited the highest mobility, followed by Zn, Ni, Pb and Cu. A combined experimental (soil-column Donnan membrane technique) and modelling approach helped to specify that Cd, Ni and Zn occurred as free ions, Pb mainly occurred as free ion and associated to fulvic acids and Cu was mainly associated to fulvic acids in the soil solutions. The distribution of Pb among the soil components of upper soil horizons was also determined using chemical methods (sequential extraction), physical methods (SEM-EDS, Raman microspectroscopy) and modelling. Lead was mainly associated with soil organic matter and to a lesser extent with manganese oxides. None of the Pb-bearing phases potentially emitted by the recycling plant were identified, suggesting a remobilization of Pb in the studied soils after smelter particles deposition. This work emphasizes the importance of studying the soil and its solution to better understand the behaviour of TE, to assess the environmental risks and to suggest remediation strategies
Scherzer, Falk. "Internationalisierung der Wertschöpfungsketten und die Mobilität des Produktionsfaktors Arbeit." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-69053.
Повний текст джерелаDelorme, Arnaud. "Le couplage électrophorèse capillaire-spectromètre de masse à source plasma en tant qu'instrument de spéciation des actinides à l'état de traces." Paris 11, 2003. http://www.theses.fr/2003PA112213.
Повний текст джерелаAn interface between the separation technique (capillary electrophoresis) and the analytical technique (Inductively Coupled Plasma - Mass Spectrometer) was developed. In that sense, bibliographic and parametric studies allowed to define necessary conditions for the good working of both techniques. The results obtained led to the realisation of an interface capillary electrophoresis - inductively coupled plasma mass spectrometer (CE/ICP-MS). This one was experimentally validated on classical separations (alkalines /earth-alkalines and lanthanides) and the detection limit of the analytical system was determined equal to 4x10^(-11) mol. L^(-1) for plutonium. This result exhibits a gain in detection limit of a factor higher than 10^4 compared to the capillary electrophoresis in standard detection (UV). The studies were made in order to check the capacity of the CE /ICP-MS coupling as a speciation instrument for actinides at trace level and to define the associated analytical procedures. The coupling turned out to be a suited instrument for the determination of absolute electrophoretic mobilities at infinite dilution (physico-chemical property which allows to predict the migration time of an ion under an electrical field in a given electrolyte), for the determination of thermodynamic constants and for the separation of different actinide oxidation states in solution
Schindl, Roland [Verfasser]. "Ultra trace analysis and mobility of palladium emissions from automotive catalytic converters / Roland Schindl." Ulm : Universität Ulm. Fakultät für Naturwissenschaften, 2015. http://d-nb.info/1075253357/34.
Повний текст джерелаPetraro, Alessandro. "Clustering di tracce di mobilità per l’identificazione di stili di guida." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13003/.
Повний текст джерелаClark, Rob. "Integration, mobility, and development International trade and organization networks, 1980--2000 /." [Bloomington, Ind.] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3274262.
Повний текст джерелаSource: Dissertation Abstracts International, Volume: 68-07, Section: A, page: 3171. Adviser: Arthur S. Alderson. Title from dissertation home page (viewed Apr. 15, 2008).
Lasley, Katrina. "Chemistry and Transport of Metals from Entrenched Biosolids at a Reclaimed Mineral Sands Mining Site in Dinwiddie County, Virginia." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/33994.
Повний текст джерелаMaster of Science
Düker, Anders. "Natural aquatic colloidal matter : characteristics and impact on the mobility of trace metals and organics /." Linköping : Tema, Univ, 1998. http://www.bibl.liu.se/liupubl/disp/disp98/arts180s.htm.
Повний текст джерелаDevallois, Valérie. "Transferts et mobilité des éléments traces métalliques dans la colonne sédimentaire des hydrosystèmes continentaux." Aix-Marseille 1, 2009. http://www.theses.fr/2009AIX11046.
Повний текст джерелаJaniak, Alexandre. "Essais sur la mobilité géographique, sectorielle et intra-sectorielle en périodes de changement structurel : le rôle du capital humain, du capital social et de l'ouverture aux échanges." Doctoral thesis, Universite Libre de Bruxelles, 2007. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210600.
Повний текст джерелаLe changement structurel est un processus nécessaire qui améliore considérablement les conditions de vie dans nos sociétés. Il peut découler par exemple de l'introduction de nouvelles avancées technologiques qui permettent d'augmenter à long terme la productivité agrégée dans nos économies. En retour, la hausse de la productivité a un impact sur notre consommation de tous les jours. Elle nous permet notamment de vivre dans un plus grand confort. Les individus peuvent alors s'épanouir dans leur ensemble. Il est évident que le changement structurel peut prendre d'autres formes que celle du changement technologique, mais il est souvent issu d'une transformation des forces qui influencent les marchés et en général aboutit à long terme à une amélioration du bien-être global.
Mais le changement structurel est aussi un processus douloureux. Il peut durer plusieurs décennies et, durant cette période, nous sommes beaucoup à devoir en supporter les coûts. Comme nous allons l'illustrer dans ce chapitre introductif, le changement structurel a pour conséquence une modification du rapport aux facteurs de production, ce qui alors mène à modifier l'ensemble des prix relatifs qui caractérisent une économie. En particulier, la modification des prix est due à une transformation des demandes relatives de facteurs. Ces derniers se révèlent alors inutiles à l'exécution de certaines tâches ou sont fortement demandés dans d'autres points de l'économie.
Souvent, le changement structurel entraîne alors un processus de réallocation. Des pans entiers de travailleurs doivent par conséquent se réallouer à d'autres tâches. Les lois du marché les incitent ainsi à devoir s'adapter à un nouveau contexte, mais elles le font pour un futur meilleur.
Cette thèse s'intéresse à cette problématique. Elle suppose que tout processus de changement structurel implique un mouvement de réallocation des facteurs de production, notamment des travailleurs puisqu'il s'agit d'une thèse en économie du travail, mais qu'un tel processus engendre souvent des coûts non négligeables. Elle se veut surtout positive, mais la nature des questions qu'elle pose mène naturellement à un débat normatif. Par exemple, elle cherche des réponses aux interrogations suivantes: comment s'ajuste une économie au changement structurel? Quelle est la nature des coûts associés au changement? Ces coûts peuvent-ils en excéder les gains? Le processus de réallocation en vaut-il vraiment la peine? Les gains issus d'un tel processus sont-ils distribués de manière égale?
La thèse est composée de quatre chapitres qui chacun considère l’impact d’un changement structurel particulier.
Le premier chapitre s’intéresse à l’impact de l’ouverture internationale aux échanges sur le niveau de l’emploi. Il s’appuie sur des travaux récents en économie internationale qui ont montré que la libéralisation du commerce mène à l’expansion des firmes les plus productives et à la destruction des entreprises dont la productivité est moins élevée. La raison de cette dichotomie est la présence d’un coût à l’entrée sur le marché des exports qui a été documentée par de nombreuses études. Certaines entreprises se développent suite à la libéralisation car elles ont accès à de nouveaux marchés et d’autres meurent car elles ne peuvent pas faire face aux entreprises les plus productives. Puisque le commerce crée à la fois des emplois et en détruit d’autres, ce chapitre a pour but de déterminer l’effet net de ce processus de réallocation sur le niveau agrégé de l’emploi.
Dans cette perspective, il présente un modèle avec firmes hétérogènes où pour exporter une entreprise doit payer un coût fixe, ce qui implique que seules les entreprises les plus productives peuvent entrer sur le marché international. Le modèle génère le processus de réallocation que l’ouverture au commerce international suppose. En effet, comme les entreprises les plus productives veulent exporter, elles vont donc embaucher plus de travailleurs, mais comme elles sont également capables de fixer des prix moins élevés et que les biens sont substituables, les entreprises les moins productives vont donc faire faillite. L’effet net sur l’emploi est négatif car les exportateurs ont à la marge moins d’incitants à embaucher des travailleurs du au comportement de concurrence monopolistique.
Le chapitre analyse également d’un point de vue empirique l’effet d’une ouverture au commerce au niveau sectoriel sur les flux d’emplois. Les résultats empiriques confirment ceux du modèle, c’est-à-dire qu’une hausse de l’ouverture au commerce génère plus de destructions que de créations d’emplois au niveau d’un secteur.
Le second chapitre considère un modèle similaire à celui du premier chapitre, mais se focalise plutôt sur l’effet du commerce en termes de bien-être. Il montre notamment que l’impact dépend en fait de la courbe de demande de travail agrégée. Si la courbe est croissante, l’effet est positif, alors qu’il est négatif si elle est décroissante.
Le troisième chapitre essaie de comprendre quels sont les déterminants de la mobilité géographique. Le but est notamment d’étudier le niveau du chômage en Europe. En effet, la littérature a souvent affirmé que la faible mobilité géographique du travail est un facteur de chômage lorsque les travailleurs sans emploi préfèrent rester dans leur région d’origine plutôt que d’aller prospecter dans les régions les plus dynamiques. Il semble donc rationnel pour ces individus de créer des liens sociaux locaux si ils anticipent qu’ils ne déménageront pas vers une autre région. De même, une fois le capital social local accumulé, les incitants à la mobilité sont réduits.
Le troisième chapitre illustre donc un modèle caractérisé par diverses complémentarités qui mènent à des équilibres multiples (un équilibre avec beaucoup de capital social local, peu de mobilité et un chômage élevé et un autre avec des caractéristiques opposées). Le modèle montre également que le capital social local est systématiquement négatif pour la mobilité et peut être négatif pour l’emploi, mais d’autres types de capital social peuvent en fait faire augmenter le niveau de l’emploi.
Dans ce troisième chapitre, une illustration empirique qui se base sur plusieurs mesures montre que le capital social est un facteur dominant d’immobilité. C’est aussi un facteur de chômage lorsque le capital social est clairement local, alors que d’autres types de capital social s’avèrent avoir un effet positif sur le taux d’emploi. Cette partie empirique illustre également la causalité inverse où des individus qui vivent dans une région qui ne correspond pas à leur région de naissance accumulent moins de capital social local, ce qui donne de la crédibilité à une théorie d’équilibres multiples.
Finalement, en observant que les individus dans le Sud de l’Europe semblent accumuler plus de capital social local, alors que dans le Nord de l’Europe on tend à investir dans des types plus généraux de capital social, nous suggérons qu’une partie du problème de chômage en Europe peut mieux se comprendre grâce au concept de capital social local.
Enfin, le quatrième chapitre s’intéresse à l’effet de la croissance économique sur la qualité des emplois. En particulier, il analyse le fait qu’un individu puisse avoir un emploi qui corresponde ou non à ses qualifications, ce qui, dans le contexte de ce chapitre, détermine s’il s’agit de bons ou mauvais emplois.
Ce chapitre se base sur deux mécanismes qui ont été largement abordés par la littérature. Le premier est le concept de « destruction créatrice » qui dit que la croissance détruit de nouveaux emplois car elle les rend obsolètes. Le second est le processus de « capitalisation » qui nous dit que la croissance va créer de nombreux emplois car les entreprises anticipent des profits plus élevés dans le futur.
Alors que des études récentes, suggèrent que la destruction créatrice ne permet pas d’expliquer le lien entre croissance et chômage, ce chapitre montre qu’un tel concept permet de mieux comprendre la relation entre croissance et qualité des emplois.
Avec des données issues du panel européen, nous illustrons que la corrélation entre croissance et qualité des emplois est positive. Nous présentons une série de trois modèles qui diffèrent de la manière suivante :(i) le fait de pouvoir chercher un emploi ou non alors qu’on en a déjà un, (ii) le fait pour une entreprise de pouvoir acquérir des équipements modernes. Les résultats suggèrent que pour expliquer l’effet de la croissance sur la qualité des emplois, la meilleure stratégie est une combinaison entre les effets dits de destruction créatrice et de capitalisation. Alors que le premier effet influence le taux de destruction des mauvais emplois, le second a un impact sur la mobilité du travail des mauvais vers les bons emplois.
Doctorat en Sciences économiques et de gestion
info:eu-repo/semantics/nonPublished
Hindersmann, Iris [Verfasser], and Tim [Akademischer Betreuer] Mansfeldt. "Trace elements in floodplain soils - effects of redox conditions on the mobility of trace elements and volatilization of mercury / Iris Hindersmann. Gutachter: Tim Mansfeldt." Köln : Universitäts- und Stadtbibliothek Köln, 2014. http://d-nb.info/1060190427/34.
Повний текст джерелаMagnani, Antonio. "Simulazione di mobilità in ambito veicolare." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/4581/.
Повний текст джерелаStipanicic, Marquez Fernando. "Essays on International Trade and Innovation." Thesis, Toulouse 1, 2022. http://www.theses.fr/2022TOU10010.
Повний текст джерелаThe Creation and Diffusion of Knowledge: Evidence from the Jet AgeThis paper provides new causal evidence of the impact of air travel time on the creation and diffusion of knowledge. We exploit the beginning of the Jet Age as a quasi-natural experiment. We digitize airlines' historical flight schedules and construct a novel data set of the flight network in the United States. Between 1951 and 1966, travel time between locations more than 2,000 km apart decreased on average by 41%. The reduction in travel time explains 33% of the increase in knowledge diffusion as measured by patent citations. The increase in knowledge diffusion further caused an increase in the creation of new knowledge. The results provide evidence that jet airplanes led to innovation convergence across locations and contributed to the shift in innovation activity towards the South and the West of the United States.Historical Air Travel Times: United StatesIn this paper we present a novel dataset of air travel times in the United States. We have digitized and web-scrapped information on airlines' flight schedules for 13 years in approximately five year intervals covering the period 1951 to 1999. The dataset contains 755 airports and 11,058 directed airport-pair links. We document that between 1951 and 1999, the big drop in travel time of non-stop flights occurred in the period 1956-1961 with the introduction of jet airplanes. We also document the appearance of long-range flights in 1970. Using airline information, we show the expansion of American Airlines and the development of its hubs. We propose to study the Airline Deregulation Act of 1978 as a policy change that may have driven the change from a point-to-point to a hub-and-spoke network.The Geography of Innovation: France 1978-2010In this paper we present a series of facts on the geographic distribution of patenting activity in France in the period 1978 to 2010. During this period we observe that the share of multi-inventor patents that have inventors in multiple departments increased from 38% to 47%. At the same time, the share of those patents with at least one inventor in Paris decreased from 35% to 30%. Therefore, across-department patent collaboration increased at a national level but diverted away from Paris. We also observe that the share of inventors that year-on-year migrate to or from Paris increases over time. These phenomena happened simultaneously with the expansion of high speed railways. We construct a new dataset of yearly train travel time across departments' capitals. Between 1980 and 2018, the introduction of high speed railways led to an average decrease in travel time of more than 20% for capital-pairs located more than 400km apart. We plan to study how changes in travel time affect inventors' collaborations, inventors' teams characteristics and inventors' mobility
Ezzeddine, Oussama. "Mobilité du travail, commerce international et économie géographique : applications empiriques à l’Union européenne." Thesis, Bordeaux 4, 2011. http://www.theses.fr/2011BOR40049/document.
Повний текст джерелаThis PhD thesis aims to explain the weakness of labour mobility in the European Union. In order to do so, we carried out an empirical study which focuses on the relationship between labour mobility and its determinants: salaries, GDP, unemployment rates, distance and international trade. Neither the complementarity observed between labour mobility and trade nor the other variables allow us to explain this weakness. Economic geography offers some explanations by studying the role of market potentials. We show that migrants do not follow market potentials, which provides an explanation to labour mobility weakness in the European Union