330 research outputs found
Integration by parts formula for locally smooth laws and applications to sensitivity computations
We consider random variables of the form , where is a
smooth function and , are random variables with absolutely
continuous law . We assume that , , are piecewise
differentiable and we develop a differential calculus of Malliavin type based
on . This allows us to establish an integration by parts
formula , where is a
random variable constructed using the differential operators acting on and
We use this formula in order to give numerical algorithms for sensitivity
computations in a model driven by a L\'{e}vy process.Comment: Published at http://dx.doi.org/10.1214/105051606000000592 in the
Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute
of Mathematical Statistics (http://www.imstat.org
Fundamental Understanding of Scratch and Mar Behavior of Polymers
Scratch behavior on polymeric films was investigated. The effect of film orientation and architecture on scratch resistance was determined. Film orientation was obtained by uniaxial stretching and its architecture was modified by the addition of ethylene comonomers. Model polypropylene (PP) and polyamide (PA) systems were employed to study the effect of laminate structure on scratch resistance. Also, mar behavior on bulk polymeric materials was investigated. The impact of brightness, transparency, and color as well as surface friction and texture on mar visibility resistance was determined. These studies were conducted based on fundamental, experimental, numerical, psychophysical, and statistical approaches. Experimental tests were conducted with accordance to ASTM/ISO standard. They were complemented by numerical simulations performed using a sophisticated FEM model. The psychophysical approach is performed through human observation tests to validate the experimental findings. The obtained data was analyzed using multidimensional scaling (MDS) statistical approach.
Scratch analysis demonstrates that scratch resistance is improved with higher film orientation and lower ethylene content. The FEM analysis shows that this improvement is associated with surface-to-interface shift of stress concentration. It is also found using the parametric analysis that scratch resistance is mainly improved due to higher film hardening coefficient and yield stress, but is insensitive to film modulus. It is also found that PP/PA has better scratch performance than PA/PP. This is mainly due to PP/PA low surface friction and graded structure, where upper PP layer absorbs scratch energy and lower PA layer protects the interface from high stress built-up. Mar analysis demonstrates that mar visibility resistance decreases with green, dark, smooth, and high-friction surfaces. Also, MDS results show that brightness, transparency, and color have respectively considerable, moderate, and insignificant effect on mar perception. Experimental findings indicate that mar visibility resistance can be quantified using the slope variation of mar contrast curve. FEM stress analysis shows that stress concentration is generated at the mar edge, then propagates towards inner mar area repetitively, reflecting stick-slip oscillations observed in experimental mar tests.
The results found in these research studies serve as a practical tool to effectively design polymeric systems with appealing scratch and mar performance
FUNDAMENTALS OF DESIGN SYSTEMS
This thesis project consists of the world of design systems, the benefits that bring to
the organization, teams, users, and the business. We will dive into this new world of
design systems, to understand what are they, how we can establish them, and what
are the rules, foundations, and guidelines that we should stick to. Going through
more details, such as creating colors, typography, spaces, and icon inventories. Not
only that, but we will go through UI patterns which are very important for the
structure of a design system and this will be followed by the process of creating
Rocket Design System.
Having a design system will have a good impact on the business, good team
communications, make the work fast, and keep the organization up to date with
technologies and market changes. That was the reason why Mediaweb Creations
focused on creating "Rocket Design System"which I had the opportunity to work
on during the internship I had with them.
Mediaweb Creations is a company specialized in web development. Founded in
2006, Mediaweb is present in Leiria and Lisbon, Portugal. Their mission is to help
the clients having better user experiences by proving UX/UI Design, Front-End,
and Web Development several services.
The benefits of having a design system in an organization. Especially a web
development related one, having a single source of truth will make the process take
less time, seducing clients with an attractive product, making the teams stronger,
and letting the information flow goes farther
Compound droplets on fibers
Droplets on fibers have been extensively studied in the recent years.
Although the equilibrium shapes of simple droplets on fibers are well
established, the situation becomes more complex for compound fluidic systems.
Through experimental and numerical investigations, we show herein that compound
droplets can be formed on fibers and that they adopt specific geometries. We
focus on the various contact lines formed at the meeting of the different
phases and we study their equilibrium state. It appears that, depending on the
surface tensions, the triple contact lines can remain separate or merge
together and form quadruple lines. The nature of the contact lines influences
the behavior of the compound droplets on fibers. Indeed, both experimental and
numerical results show that, during the detachment process, depending on
whether the contact lines are triple or quadruple, the characteristic length is
the inner droplet radius or the fiber radius
Ăvaluation de la mobilitĂ© des contaminants dans des mĂ©langes rĂ©actifs des filiĂšres de traitement du DMA ferrifĂšre au laboratoire et sur le terrain
Résumé
Le drainage minier acide (DMA), caractĂ©risĂ© par un faible pH et des fortes concentrations en mĂ©taux et en sulfates, est considĂ©rĂ© comme un problĂšme mondial ayant des impacts environnementaux et Ă©cologiques majeurs. Il est gĂ©nĂ©rĂ© par lâoxydation des sulfures mĂ©talliques (ex. pyrite and pyrrhotite) en prĂ©sence dâeau et dâoxygĂšne. Sur les sites miniers abandonnĂ©s, les systĂšmes de traitement passifs, qui sont des processus dâattĂ©nuation pseudo-naturels, sont prĂ©fĂ©rĂ©s pour traiter le DMA ferrifĂšre (Fe-DMA) ou fortement contaminĂ© en fer (>500 mg/L), Ă©tant donnĂ© quâils offrent la possibilitĂ© de rĂ©utiliser des matĂ©riaux Ă faible coĂ»t (tels que les dĂ©chets industriels), consomment moins dâĂ©nergie et amĂ©liorent la qualitĂ© du DMA. NĂ©anmoins, comme le cas des systĂšmes de traitement actifs, les systĂšmes de traitement passifs gĂ©nĂšrent des quantitĂ©s non-nĂ©gligeables de rĂ©sidus riches en mĂ©taux. Une fois excavĂ©s, ces rĂ©sidus prĂ©sentent une stabilitĂ© chimique variĂ©e et qui reste difficile Ă prĂ©dire, puisquâelle dĂ©pend de la qualitĂ© du DMA traitĂ© et de la technologie de traitement utilisĂ©e. Ainsi, afin dâassurer une bonne gestion de ces rĂ©sidus conformĂ©ment aux lois et rĂšglementation, lâĂ©tude au cas par cas demeure souvent nĂ©cessaire pour limiter la mobilisation potentielle des contaminants.
Dans ce contexte, les principaux objectifs de la thĂšse sont les suivants : (1) Ă©valuer la mobilitĂ© des contaminants dans les rĂ©sidus post-traitement collectĂ©s dans une filiĂšre du traitement du Fe-DMA au laboratoire; (2) Ă©valuer la mobilitĂ© des contaminants dans les rĂ©sidus post-traitement collectĂ©s dans une filiĂšre de traitement du Fe-DMA installĂ©e sur le terrain (site Lorraine); et (3) Ă©valuer la performance du traitement par stabilisation/solidification comme mode de gestion durable pour les rĂ©sidus post-traitement de la filiĂšre de terrain. Afin d'atteindre ces objectifs, l'approche mĂ©thodologique adoptĂ©e consistait Ă Ă©chantillonner tout dâabord les rĂ©sidus des deux filiĂšres de traitement, et ensuite les caractĂ©riser pour leurs paramĂštres physicochimiques et minĂ©ralogiques. Par la suite, des tests de lixiviation et essais cinĂ©tiques ont Ă©tĂ© rĂ©alisĂ©s afin dâĂ©valuer la mobilitĂ© potentielle des contaminants et statuer sur la stabilitĂ© des rĂ©sidus post-traitement. Finalement, les rĂ©sidus post-traitement de la filiĂšre sur terrain ont fait lâobjet dâun traitement par stabilisation/solidification. Afin de tester la performance de ce mode de gestion, les rĂ©sidus traitĂ©s ont Ă©tĂ© caractĂ©risĂ©s pour leur minĂ©ralogie et ont subi des tests de lixiviation statique et semi-dynamique pour lâĂ©valuation de leur comportement environnemental. La revue de littĂ©rature rĂ©alisĂ©e a permis de statuer sur le fait que, malgrĂ© l'abondance des Ă©tudes portant sur le traitement passif du Fe-DMA, trĂšs peu dâĂ©tudes ont Ă©valuĂ© le potentiel de mobilitĂ© des contaminants en provenance de ces systĂšmes de traitement. Ăgalement, en fonction de la qualitĂ© du DMA traitĂ© et de la technologie de traitement utilisĂ©e (chimique et/ou biochimique), les rĂ©sidus prĂ©sentaient une stabilitĂ© chimique variable. Ainsi, la revue de littĂ©rature a permis de faire ressortir que la comprĂ©hension des mĂ©canismes et des processus qui contrĂŽlent lâenlĂšvement des mĂ©taux et des sulfates sont nĂ©cessaires pour mieux comprendre et prĂ©dire la mobilitĂ© des contaminants. Toutefois, ces mĂ©canismes nâont pas Ă©tĂ© bien abordĂ©s. Par ailleurs, le comportement gĂ©ochimique des rĂ©sidus sous les diffĂ©rentes conditions dâaltĂ©ration (cycles mouillage/sĂ©chage et cycles gel/dĂ©gel) nâa pas Ă©tĂ© abordĂ© dans la littĂ©rature. Ăgalement, les travaux disponibles nâont pas Ă©tĂ© effectuĂ©s pour traiter les boues des systĂšmes passifs du traitement du DMA.
Dans ce but, la premiĂšre Ă©tape consistait Ă Ă©chantillonner les rĂ©sidus post-traitement provenant de trois unitĂ©s constituant la filiĂšre de traitement du Fe-DMA au laboratoire: une unitĂ© de prĂ©traitement du Fe (CB50), une unitĂ© de traitement des sulfates (RPB) et une unitĂ© de polissage (C50). La caractĂ©risation physicochimique (pH de la pĂąte, humiditĂ© et teneurs en mĂ©taux, en carbone organique, en carbone inorganique, en soufre, etc.) et minĂ©ralogique (DRX, MEB-EDS et XPS) a Ă©tĂ© rĂ©alisĂ©e. Des essais de lixiviation statique en batch unique (TCLP) et en batch parallĂšle (essais de lixiviation Ă pH-dĂ©pendant) ont Ă©galement Ă©tĂ© rĂ©alisĂ©s afin dâĂ©valuer le potentiel de lixiviation des contaminants. Des essais cinĂ©tiques en minicellules dâaltĂ©ration sous des cycles mouillage/sĂ©chage et gel/dĂ©gel ont Ă©tĂ© ensuite rĂ©alisĂ©s pour Ă©valuer le comportement environnemental et gĂ©ochimique de ces rĂ©sidus post-traitement. Les rĂ©sultats ont montrĂ© que tous les rĂ©sidus avaient un potentiel de neutralisation rĂ©siduel Ă©levĂ©, alors que des concentrations importantes en mĂ©taux ont Ă©tĂ© trouvĂ©es dans les rĂ©sidus de lâunitĂ© de prĂ©traitement CB50 (ex. Fe, Al, Mn etc.), tel quâattendu. Le Fe Ă©tait prĂ©cipitĂ© sous forme d'oxy-hydroxydes (goethite, hĂ©matite et magnĂ©tite) et les sulfates Ă©taient retenus sous forme de soufre natif et de gypse. BasĂ© sur les rĂ©sultats du test TCLP, tous les rĂ©sidus ont Ă©tĂ© classĂ©s comme non-dangereux selon les valeurs limites dĂ©finies par lâUSEPA. Cependant, les rĂ©sultats du test de lixiviation Ă pH-dĂ©pendant ont montrĂ© que tout contact avec un milieu acide (8) doit ĂȘtre Ă©vitĂ© afin de limiter la lixiviation potentielle des mĂ©taux et, par consĂ©quent, un stockage Ă pH neutre Ă faiblement basique a Ă©tĂ© recommandĂ©. Par ailleurs, une gĂ©nĂ©ration possible de drainage minier neutre, avec des concentrations Ă©levĂ©es en mĂ©taux (ex. Ba, Ni, Cu, Mn et Zn) pourrait se produire Ă partir de tous les rĂ©sidus Ă la suite des altĂ©rations durant lâessai cinĂ©tique. Ăgalement, les cycles gel/dĂ©gel ont montrĂ© que la lixiviation des mĂ©taux et des sulfates Ă©tait beaucoup plus Ă©levĂ©e par rapport aux cycles mouillage/sĂ©chage. Ceci pourrait renforcer la mobilitĂ© des contaminants une fois que les rĂ©sidus sont dĂ©posĂ©s en surface.
La deuxiĂšme Ă©tape du projet consistait Ă Ă©chantillonner les rĂ©sidus post-traitement provenant de trois unitĂ©s constituant la filiĂšre de traitement du Fe-DMA installĂ©e sur le site minier Lorraine: une unitĂ© de neutralisation de lâaciditĂ© et de prĂ©cipitation partielle des mĂ©taux (RPB1), une unitĂ© de traitement de traitement du Fe (CB) et une unitĂ© de polissage (RPB2). De la caractĂ©risation physicochimique et minĂ©ralogique, des essais de lixiviation statique en batch unique et en batch parallĂšle, comme pour le cas des solides de la filiĂšre au laboratoire, ainsi que des essais cinĂ©tiques (en mini-colonne) ont Ă©tĂ© rĂ©alisĂ©s afin dâĂ©valuer le potentiel de lixiviation des contaminants et le comportement gĂ©ochimique des rĂ©sidus post-traitement. Ăgalement, des calculs de l'Ă©quilibre thermodynamique ont Ă©tĂ© aussi rĂ©alisĂ©s sur les Ă©chantillons dâeaux provenant des piĂ©zomĂštres installĂ©s dans chaque unitĂ© de traitement pour Ă©valuer lâoccurrence de la prĂ©sence de prĂ©cipitĂ©s mĂ©talliques ainsi que leurs formes (ex. carbonates, oxides, hydroxydes, sulfures, etc.). Les rĂ©sultats ont montrĂ© que les rĂ©sidus CB avaient un potentiel de neutralisation Ă©levĂ© par rapport aux autres rĂ©sidus. Ăgalement, tous les rĂ©sidus post-traitement avaient des teneurs Ă©levĂ©es en mĂ©taux (surtout Fe). La modĂ©lisation gĂ©ochimique a suggĂ©rĂ© que le Fe pourrait ĂȘtre prĂ©cipitĂ© sous la forme d'oxydes, d'hydroxydes, d'oxy-hydroxydes, d'hydroxysulfates et de sulfures. Comme pour le cas des rĂ©sidus post-traitement de la filiĂšre au laboratoire, les rĂ©sultats de la caractĂ©risation minĂ©ralogique ont montrĂ© que le Fe se trouvait sous forme d'oxy-hydroxydes (goethite, hĂ©matite et magnĂ©tite), alors que les sulfates se trouvaient sous la forme de soufre natif et de gypse. Les rĂ©sultats du test TCLP ont montrĂ© que tous les rĂ©sidus Ă©taient classĂ©s comme non-dangereux. Ăgalement, les rĂ©sultats de lâessai de lixiviation Ă pH-dĂ©pendant ont indiquĂ© que tous les rĂ©sidus Ă©taient considĂ©rĂ©s comme lixiviables en contact avec le milieu acide ou alcalin et un stockage appropriĂ© Ă pH neutre Ă faiblement basique pourrait ĂȘtre considĂ©rĂ© afin de limiter la mobilitĂ© des mĂ©taux. Quant Ă eux, les rĂ©sultats des essais cinĂ©tiques ont montrĂ© que les rĂ©sidus RPB2 ont gĂ©nĂ©rĂ© un DMA avec de fortes concentrations en mĂ©taux (surtout Fe) et en sulfates, tandis que les rĂ©sidus RPB1 et CB ont gĂ©nĂ©rĂ© un drainage minier neutre avec des concentrations Ă©levĂ©es en certains mĂ©taux (ex. Mn, Ni, Zn, etc.). La troisiĂšme Ă©tape du projet consistait Ă traiter par stabilisation/solidification les rĂ©sidus en provenance de la filiĂšre de traitement sur le terrain. Pour ce faire, trois types de liants ont Ă©tĂ© testĂ©s : le ciment Portland vs liants mĂ©langĂ©s Ă base du ciment Portland avec des additifs pouzzolaniques tels que les scories et les cendres volantes type C. Les solides traitĂ©s par stabilisation/solidification ont Ă©tĂ© caractĂ©risĂ©s du point de vue minĂ©ralogique par DRX, MEB-EDS, FTIR et ATG afin de dĂ©terminer les produits de la rĂ©action dâhydratation du ciment. LâefficacitĂ© du traitement par stabilisation/solidification des rĂ©sidus a Ă©tĂ© Ă©valuĂ©e par une caractĂ©risation mĂ©canique (test de compression uniaxial), ainsi que des tests de lixiviation statique (TCLP, SPLP et CTEU-9) et semi-dynamique (test de lixiviation sur les monolithes). Les rĂ©sultats ont montrĂ© que les phases calcium-silicates-hydrates (C-S-H), les phases calcium-aluminium-silicates-hydrates (C-A-S-H), le monosulfoaluminate et la portlandite Ă©taient les principaux produits d'hydratation dans tous les rĂ©sidus traitĂ©s. Les rĂ©sultats du comportement mĂ©canique ont montrĂ© que tous les rĂ©sidus traitĂ©s respectaient les limites de lâUSEPA pour lâenfouissement. Par ailleurs, bien que les tests de lixiviation statique aient indiquĂ© qu'une concentration Ă©levĂ©e en Ba (> 1mg/L) pouvait ĂȘtre libĂ©rĂ©e de tous les rĂ©sidus traitĂ©s, les rĂ©sultats du test de lixiviation sur les monolithes ont montrĂ© que la concentration en Ba Ă©tait faible (< 1mg/L) dans les lixiviats provenant des rĂ©sidus traitĂ©s Ă base de ciment Portland tout seul ou combinĂ© avec les scories. En outre, les concentrations de tous les mĂ©taux dans les lixiviats des Ă©chantillons stabilisĂ©s Ă©taient infĂ©rieures aux limites fixĂ©es par l'USEPA pour leur enfouissement ou leur Ă©limination dans les sites de dĂ©charge des dĂ©chets non-dangereux. GĂ©nĂ©ralement, le traitement par stabilisation/solidification avec le liant ciment Portland a donnĂ© les meilleures performances en termes de dĂ©veloppement de la rĂ©sistance Ă la compression et d'immobilisation des contaminants. Le prĂ©sent projet a donc permis dâapprofondir les connaissances liĂ©es aux mĂ©canismes de rĂ©tention des contaminants (mĂ©taux et sulfates) et Ă la stabilitĂ© chimique des rĂ©sidus issus des systĂšmes de traitement passif du DMA. LâintĂ©gration du traitement par stabilisation/solidification des rĂ©sidus comme mode de gestion durable, qui a Ă©tĂ© proposĂ© dans cette Ă©tude, constitue Ă©galement un apport scientifique novateur. Enfin, les connaissances et les approches mĂ©thodologiques acquises durant cette Ă©tude pourraient ĂȘtre applicables Ă dâautres rĂ©sidus post-traitement pour mieux anticiper leur comportement, devenir et gestion. Mots clĂ©s : drainage minier acide, traitement passif, rĂ©sidus post-traitement, essais de lixiviation, essais cinĂ©tiques, gel/dĂ©gel, gestion des rejets, stabilisation/solidification.
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Abstract
Acid mine drainage (AMD), characterized by low pH and high concentrations of metals and sulfates, is a worldwide problem with significant environmental and ecological impacts. It is generated by oxidation of sulphides (e.g. pyrite and pyrrhotite) in the presence of water and oxygen. At abandoned mine sites, passive treatment systems, which are pseudo-natural attenuation processes, are preferred for AMD treatment, since they offer the possibility to reuse low-cost materials (e.g. industrial waste), consume less energy and improve the quality of the AMD. Nevertheless, like the case of active treatment systems, passive treatment systems generate not negligible quantities of metal-rich residues. Once excavated, these residues exhibited variable chemical stability, which remained difficult to predict, because it depends on the AMD quality to be treated and the treatment technology used. Thus, to ensure a better management of these residues in accordance with the laws and regulations, the case-by-case study is often necessary to prevent the potential mobilization of contaminants.
In this context, the main objectives of the thesis are the following: (1) to evaluate the mobility of contaminants from post-treatment residues collected in a laboratory Fe-AMD system; (2) to evaluate the mobility of contaminants from post-treatment residues collected in a field-based Fe-AMD system (Lorraine site); and (3) to evaluate the performance of stabilization/solidification treatment as a sustainable management mode for post-treatment residues from the field system. To achieve these objectives, the methodological approach adopted consisted firstly of post-treatment residues sampling from the two treatment systems. Then, the sampled residues were characterized for physicochemical parameters and mineralogy. Afterwards, leaching and kinetic tests were conducted to evaluate the mobility of contaminants from residues. Finally, the post-treatment residues from the field system were subjected to a stabilization/solidification treatment. To evaluate the performance of this management, the treated residues were mineralogically characterized and were subjected to static and semi-dynamic leaching tests to assess their environmental behavior.
The literature review showed that, despite the abundance of studies on the passive treatment of Fe-AMD, very few evaluated the mobility potential of contaminants from these treatment systems. In addition, depending on the quality of the treated AMD and the treatment technology used (chemical and/or biochemical), residues exhibited variable chemical stability. Thus, the literature review highlighted that, understanding the mechanisms and processes that control the removal of metals and sulfates are necessary to better anticipate the mobility of contaminants from passive treatment residues. However, these mechanisms have not been well addressed until now. Moreover, the geochemical behavior of contaminants from the post-treatment residues under different weathering conditions (wetting/drying cycles and freezing/thawing cycles) are not discussed in the literature. Finally, no research has addressed residues treatment from AMD passive treatment systems.
To this end, the first step consisted of residues (CB50, RPB and C50) sampling from a laboratory Fe-AMD passive treatment system. Physicochemical (paste pH, humidity and content of metals, organic carbon, inorganic carbon, sulfur, etc.) and mineralogical characterization (XRD, SEM-EDS and XPS) were carried out. Single batch (TCLP) and parallel batch (pH-dependent leaching test) leaching tests were then conducted to evaluate the leaching potential of contaminants from the collected residues. Kinetic test in weathering cells under wetting/drying and freezing/thawing cycles were also performed to evaluate the geochemical environmental behavior of contaminants from residues. Results showed that all residues had a high residual neutralization potential, whereas significant concentrations of metals (e.g. Fe, Al, Mn etc.) were found in the residues of the pre-treatment unit CB50, as expected. In addition, Fe was precipitated as oxy-hydroxides (goethite, hematite and magnetite), while sulfates were retained in the form of native sulfur and gypsum. Based on the TCLP test, all residues were classified as non-hazardous according to the USEPA limits. The results of the pH-dependent leaching test showed that any contact with acid or alkaline mediums should be avoided to prevent metalsâ release and a storage at neutral to slightly basic pH was recommended. Moreover, a possible generation of neutral mine drainage (e.g. Ba, Ni, Cu, Mn and Zn) could occur from all residues under weathering during kinetic test. Furthermore, freezing/ thawing cycles showed that leaching of metals and sulfates was much higher than wetting/drying cycles, which could enhance the mobility of contaminants once the residues are disposed in surface impoundments or in uncovered disposal facilities.
The second step of the project aimed at residues (RPB1, CB and RPB2) sampling from a field-scale tri-step Fe-AMD passive treatment system installed in the Lorraine mine site. Physicochemical and mineralogical characterization, leaching tests in single batch and in parallel batch, as for the case of the residues of the laboratory treatment system, as well as kinetic tests (in mini-column) were performed to evaluate contaminantsâ leaching potential and geochemical behavior of residues. In addition, the calculation of the thermodynamic equilibrium was also carried out on water samples collected from piezometers installed in each treatment unit to evaluate of the occurrence of metal precipitates as well as their forms (e.g. carbonates, oxides, hydroxides, sulfides, etc.). Results showed that CB residues had higher neutralization potential than other residues. Moreover, all post-treatment residues had high metal content (especially Fe). Geochemical equilibrium modeling suggested that Fe could be precipitated in the form of oxides, hydroxides, oxy-hydroxides, sulfides and hydroxysulfates. As in the case of post-treatment residues from the laboratory system, results of the mineralogical characterization indicated that Fe was in the form of oxy-hydroxides (goethite, hematite and magnetite) and sulfates were in the form of native sulfur and gypsum. The TCLP results showed that all residues were classified as non-hazardous. Furthermore, results of the pH-dependent leaching test showed that all residues were considered leachable in contact with acidic or alkaline mediums, and an appropriate storage at neutral to weakly basic pH must be considered to limit the mobilisation of metals. For their part, kinetic test results showed that PBR2 residues generated acid mine drainage with high concentration of metals (especially Fe) and sulfates, while PBR1 and CB residues generated neutral mine drainage with significant metal concentrations (e.g. Mn, Ni, Zn).
The third step aimed to residues treatment from the field system by stabilization/solidification. To do so, three types of binders were tested: Portland cement vs. mixed binders based on Portland cement with pozzolanic additives such as slag and fly ash type C. Residues treated by stabilization/solidification were mineralogically characterized by XRD, SEM-EDS, IR-DRIFT and TGA to determine the products of cement hydration reaction. The effectiveness of the stabilization/solidification treatment of residues was evaluated by mechanical characterization (uniaxial compressive strength), and static (TCLP, SPLP and CTEU-9) and semi-dynamic (monolithic leaching test) leaching tests. Results showed that calcium-silicates-hydrates (C-S-H), calcium-aluminium-silicates-hydrates (C-A-S-H), monosulfoaluminate and portlandite were the main hydration products in all the treated residues. Results of the mechanical behavior showed that all residues satisfied the threshold of USEPA for landfilling. In addition, although static leaching tests indicated that high Ba concentration could be released from all treated residues, the monolithic leaching test showed that Ba was lowly leached from residues treated with Portland cement only or Portland cement combined with slag. Finally, concentrations of all metals in the leachates of the stabilized samples were below the limits set by the USEPA for landfilling or disposal at non-hazardous waste sites. Overall, the stabilization/solidification treatment with Portland cement gave the best performance in terms of compressive strength development and immobilization of heavy metals.
This present project progressed the knowledge on contaminant retention mechanisms (i.e. metals and sulfates) and on chemical stability of residues from AMD passive treatment systems. The integration of stabilization/solidification treatment of residues as a sustainable management approach, proposed in this study, is also an innovative scientific contribution. Finally, knowledge and methodological approaches learned during this study may be applicable to other post-treatment residues to better anticipate their fate. Keywords: acid mine drainage, passive treatment, post-treatment residues, leaching tests, kinetic tests, freezing/ thawing, waste management, stabilization/solidification
Wing Tip Vortex Development under the Effect of Active Flow Control
L'Ă©tude des tourbillons de bout d'aile est d'une grande importance scientifique en raison des problĂšmes pratiques tels que les distances de sĂ©paration des aĂ©ronefs, les interactions pale/tourbillon dans les hĂ©licoptĂšres, les cavitations des hĂ©lices des navires, etc. RĂ©cemment, des Ă©tudes extensives ont Ă©tĂ© conduites pour amĂ©liorer la comprĂ©hension de la structure du tourbillon, de sa dissipation et de sa persistance par des mĂ©thodes analytiques, numĂ©riques et expĂ©rimentales. Ces Ă©tudes ont principalement portĂ© sur les Ă©coulements Ă nombres de Reynolds (Re) Ă©levĂ©s. Cependant, avec l'Ă©mergence de nouveaux drones, les tourbillons de bout d'aile ont des effets extrĂȘmement nĂ©fastes sur les performances aĂ©rodynamiques des drones pour diffĂ©rentes configurations de vol. Il a Ă©galement Ă©tĂ© montrĂ© dans la littĂ©rature que la dissipation d'un tourbillon de bout d'aile peut ĂȘtre modifiĂ©e et accĂ©lĂ©rĂ©e au moyen de jets synthĂ©tiques (JS). En effet, les JS exercent un certain contrĂŽle sur un Ă©coulement ce qui modifie spatialement et temporellement son dĂ©veloppement. Dans ce travail, plusieurs techniques expĂ©rimentales ont Ă©tĂ© utilisĂ©es pour Ă©tudier les effets du contrĂŽle actif par jets synthĂ©tiques sur le dĂ©veloppement, la diffusion et l'errance du tourbillon, y compris l'anĂ©momĂ©trie Ă fils chauds et la vĂ©locimĂ©trie par imagerie de particules stĂ©rĂ©oscopique (SPIV). Deux ailes rectangulaires avec un profil NACA 0012 ont Ă©tĂ© fabriquĂ©es pour cette Ă©tude et ont Ă©tĂ© testĂ©es pour deux nombres de Reynolds. Dans la premiĂšre configuration expĂ©rimentale, des mesures de pression sur l'intrados de l'aile ont montrĂ© que la sĂ©lection des frĂ©quences d'actionnement dans la gamme de frĂ©quences des instabilitĂ©s de courtes et de longues durĂ©es diminuait les coefficients de pression pour les cas activĂ©s. Des mesures complĂštes par fils chauds ont ensuite Ă©tĂ© effectuĂ©es dans la rĂ©gion de quasi-sillage pour documenter l'effet de l'actionnement du jet synthĂ©tique sur la structure d'un tourbillon de bout d'aile. Les rĂ©sultats suggĂšrent que la configuration de contrĂŽle Ă basse frĂ©quence a permis au JS de pĂ©nĂ©trer dans le tourbillon en apportant des structures turbulentes dans son noyau. La mĂȘme configuration a Ă©tĂ© utilisĂ©e pour l'acquisition des donnĂ©es dans la rĂ©gion du milieu du sillage. Trois configurations de contrĂŽle ont Ă©tĂ© considĂ©rĂ©es pour une Ă©tude comparative sur un tourbillon auto-similaire. Une technique de correction a Ă©tĂ© appliquĂ©e sur tous les cas Ă©tudiĂ©s. Le dĂ©veloppement du tourbillon actionnĂ© a montrĂ© que le mĂ©lange turbulent a Ă©tĂ© amĂ©liorĂ© au niveau de la rĂ©gion interne, entraĂźnait une diffusion accĂ©lĂ©rĂ©e. L'effet d'errance sur la structure et la diffusion d'un tourbillon de bout d'aile a Ă©tĂ© Ă©tudiĂ© en utilisant des mesures de SPIV sur un dispositif expĂ©rimental diffĂ©rent et Ă un nombre de Re diffĂ©rent. La contribution d'errance Ă la diffusion des tourbillons a Ă©tĂ© quantifiĂ©e en utilisant une dĂ©composition orthogonale (POD). Le mouvement cohĂ©rent du tourbillon a Ă©tĂ© extrait Ă partir de la triple dĂ©composition du champ de vitesse corrigĂ©. De plus, d'autres observations sur les mĂ©canismes physiques associĂ©s Ă la diffusion des tourbillons ont Ă©tĂ© identifiĂ©es Ă partir de l'Ă©quation de transport d'enstrophie. Il a Ă©tĂ© dĂ©montrĂ© que la dissipation de l'enstrophie Ă©tait principalement attribuable Ă l'allongement de la vorticitĂ© et Ă la fluctuation du tenseur de dĂ©formation causĂ©e par le JS.Abstract: Wing tip vortex flow is of a great scientific importance because of its effect on practical problems such as landing separation distances for aircrafts, blade/vortex interactions in helicopters, propeller cavitations on ships, etc. Recently, extensive investigations have been conducted to improve the understanding of the tip vortex structure, dissipation and persistence analytically, numerically, and experimentally. Studies on the structure of the wing tip vortex have mainly focused on high Reynolds number flows. However, with the emergence of new unmanned aerial vehicles (UAVs), wing tip vortices have shown to have tremendous detrimental effects on the aerodynamic performance of drones for different flight configurations. It has also been shown in the literature that the dissipation of a wing tip vortex can be altered and accelerated by means of fluidic control schemes. Ex-hibiting zero net-mass-flux at its exit, synthetic jets (SJ) were shown to exert a certain authority on the structure of the flow which spatially and temporally alters its develop-ment. This research used several experimental techniques to study the effects of active control on the development, diffusion and meandering of wing-tip vortices, including hot-wire anemometry and Stereo Particle Image Velocimetry (SPIV). Two rectangular wings with a NACA 0012 profile were fabricated for the use in this research and were tested at two chord based Re,â numbers, namely 8 x 104 and 2 x 105. In the first experimental setup, spanwise pressure measurements on the suction side of the wing showed that the selection of actuation frequencies in the range of frequencies of the long- and short-wave instabilities resulted in decreased pressure coefficients for the actuated cases compared to the natural vortex. Comprehensive hot-wire measurements were then conducted in the near-wake region to document the effect of SJ actuation on the structure of the vortex. The results suggested that the low frequency control configuration allowed the SJ to pen-etrate into the vortex bringing turbulent structures within its core. The same setup was used to collect data in the mid-wake region. Three control configurations were consid-ered for a comparative study on a self-similar vortex. A meandering correction technique was applied on all the cases studied. The streamwise development of the actuated vortex showed that the enhanced turbulent mixing at the inner region of the vortex resulted in an accelerated outward diffusion. The effect of the meandering phenomenon on the structure and diffusion of the vortex was investigated using Stereoscopic PIV measurements on a different experimental apparatus and at a different Re number. The contribution of mean-dering to the vortex decay was quantified using proper orthogonal decomposition (POD). The coherent meandering motion of the vortex was extracted using a triple decomposition of the meandering-corrected velocity field at different downstream positions. In addition, further insight on the physical mechanisms associated with the vortex diffusion were iden-tified from the close examination of the transport equation of the streamwise enstrophy. It was shown that the destruction of enstrophy was mainly attributed to the increased vorticity stretching and the fluctuating strain rate caused by the SJ actuation
Dynamical hybrid modeling of human metabolism
Human metabolism plays a key role in disease pathogenesis and drug action. Half a century of biochemical literature leveraged by the advent of genomics allowed the emergence of computational modeling techniques and the in silico analysis of complex biological systems. In particular, Constraint-Based Reconstruction and Analysis (COBRA) methods address the complexity of metabolism through building tissue-specific networks in their steady state. It is known that biological systems respond to perturbations induced by pathogens, drugs or malignant processes by shifting their activity to safeguard key metabolic functions. Extending the modeling framework to consider the dynamics of these complex systems will bring simulations closer to observable human phenotypes.
In this thesis, I combined physiologically-based pharmacokinetic (PBPK) models with genome-scale metabolic models (GSMMs) to form hybrid genome-scale dynamical models that provide a hypothesis-free framework to study the perturbations induced by one or more perturbagen on human tissues. On a first stage, these methodologies were applied to decipher the absorption of levodopa and amino acids by the intestinal epithelium and allowed to derive a model-based diet for Parkinson's Disease patients. In the next phase, we extended the study to 605 drugs in order to predict the occurrence of gastrointestinal side effects through a machine learning classifier, using a combination of gene expression and metabolic reactions set as features. Finally, the approach upscaled to several tissues, specifically to investigate the genesis of metabolic symptoms in type 1 diabetes and to suggest key metabolic players underlying within and between-individual variability to insulin action. Taken as whole, the integration of two modeling techniques constrained by expert biological knowledge and heterogeneous data types will be a step forward in achieving convergence in human biology
Phasenfeldmodellierung und Simulation des Benetzungsverhaltens von FlĂŒssigkeiten auf festen OberflĂ€chen
Neben experimentellen Untersuchungen sind numerische Simulationen unabdingbar um komplexe Benetzungsprozesse zu erforschen. Je nach Fragestellung kommen verschiedene Simulationsmodelle zum Einsatz, welche die Probleme auf unterschiedlichen Zeit- und LĂ€ngenskalen beschreiben. In den letzten Jahren haben sich Phasenfeldmodelle als effizientes Werkzeug erwiesen, um BenetzungsvorgĂ€nge auf mesoskopischer Skala numerisch zu untersuchen. Der Fokus bisheriger Arbeiten lag jedoch ausschlieĂlich auf Systemen, die lediglich aus einem Tropfen bestehen. In der vorliegenden Arbeit wird ein Phasenfeldmodell mit einer geeigneten Benetzungsrandbedingung vorgestellt, welche es ermöglicht das Verhalten sowohl einzelner als auch mehrerer nicht mischbarer Tropfen auf festen OberflĂ€chen zu beschreiben. FĂŒr Systeme bestehend aus einem Tropfen wird gezeigt, dass die simulierten GleichgewichtszustĂ€nde sehr gut mit der Theorie und mit den Resultaten vorheriger Arbeiten ĂŒbereinstimmen. Des Weiteren konnten mit dem entwickelten Phasenfeldmodell erstmals Gleichgewichtsformen von zusammengesetzten Wasser-Ăl-Tropfen sowohl auf idealen OberflĂ€chen als auch auf zylindrischen Fasern simuliert und mit experimentellen Arbeiten validiert werden. ZusĂ€tzlich wird eine Modellerweiterung vorgestellt, um die Verdunstung eines Tropfens auf chemisch strukturierten OberflĂ€chen zu simulieren. Der Vergleich mit Molekulardynamik- und Lattice-Boltzmann-Simulationen zeigt, dass das entwickelte Phasenfeldmodell die relevanten physikalischen Eigenschaften des Prozesses sehr gut beschreibt und dazu deutlich weniger Rechenaufwand benötigt
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