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Massoud, Chadi. "Evaluation de la filtration glomérulaire par IRM". Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20037.
Pełny tekst źródłaThis study seeks to assess the Glomerular Filtration Rate (GFR) in the human kidney by MRI. To quantitatively estimate this parameter requires monitoring of the intrarenal kinetics of Gd after its bolus injection. To achieve this goal, we have developed under IDEA Siemens a SR-FLASH T1-weighted MRI sequence which can follow dynamic NMR signal changes after a bolus injection of Gd. This sequence has a centric phase-encoding scheme, and thus the image contrast was determined at the beginning of the acquisition period. Subsequently, we have implemented an IR-FLASH (with centric phase-encoding scheme) sequence to measure the longitudinal relaxation time in the absence of any injection of Gd ; this parameter is required to convert NMR signal intensities into Gd concentrations. knowing that the relation between the NMR signal intensities and the Gd concentrations is not linear, we have proposed two novel methods and yet fast and robust for conversion of the NMR signal intensities into local Gd concentration. This allowed us to estimate the temporal evolution of Gd concentrations in both kidneys and aorta. The fit of these concentrations measurements by a two-compartments model describing the function of the kidney allowed us to calculate the GFR of each kidney in a population of five subjects with normal renal function
Lefebvre, Xavier. "Etude des modèles de transfert en nanofiltration : application du modèle hybride basé sur les équations de Nernst-Planck étendues par le développement du logiciel de simulation "nanoflux"". Montpellier 2, 2003. http://www.theses.fr/2003MON20082.
Pełny tekst źródłaBornaz, Saloua. "Modèle de variation de la texture du beurre et effet de modifications physiques et chimiques de la composition". Vandoeuvre-les-Nancy, INPL, 1994. http://www.theses.fr/1994INPL031N.
Pełny tekst źródłaLabbez, Christophe. "Etude du transport et de la rétention de solutés neutres et ioniques par le modèle DSPM : membranes de nano- et d'ultra-filtration fine". Besançon, 2002. http://www.theses.fr/2002BESA2044.
Pełny tekst źródłaModeling of the matter transport through a charged microporous medium is a necessary step to understand and control the selectivity of a nanofiltration membrane. In this work, a model based on the application of the extended Nernst-Planck equation and the assumption of a modified Donnan equilibrium at both membrane/solution interfaces is developed. Besides the analysis of transport mechanisms, the model allows to relate a membrane's microscopic structural and charge properties to the solute retentions. The effective pore radius (rp) and effective volume charge (X) of nanofiltration membranes could be then determined by fitting the experimental retention of neutral and charged solutes. The comparison of the predicted values of the membrane X and rp with those determined from independent measurements does not allow to conclude definitively on the validity of the model. Results show that a charge regulation phenomenon occurs inside the membrane pores
Boucquemont, Julie. "Modèles statistiques pour l'étude de la progression de la maladie rénale chronique". Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0411/document.
Pełny tekst źródłaThe objective of this thesis was to illustrate the benefit of using advanced statistical methods to study associations between risk factors and chrouic kidney disease (CKD) progression. In a first time, we conducted a literature review of statistical methods used to investigate risk factors of CKD progression, identified important methodological issues, and discussed solutions. In our sec ond work, we focused on survival analyses and issues with interval-censoring, which occurs when the event of interest is the progression to a specifie CKD stage, and competing risk with death. A comparison between standard survival models and the illness-death mode! for interval-censored data allowed us to illustrate the impact of modeling on the estimates of both the effects of risk factors and the probabilities of events, using data from the NephroTest cohort. Other works fo cused on analysis of longitudinal data on renal function. We illustrated the interest of linear mixed mode! in this context and presented its extension to account for sub-populations with different trajectories of renal function. We identified five classes, including one with a strong decline and one with an improvement of renal function over time. Severa! perspectives on predictions bind the two types of analyses presented in this thesis
Herterich, James George. "Mathematical models in water filtration". Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:73036408-fbc5-497a-a99f-b8da3dbca0a5.
Pełny tekst źródłaBarbounaki, Stavroula. "Modélisation et traitement numérique des impulsions électriques générées par le passage des globules rouges à travers des micropores". Paris 5, 1997. http://www.theses.fr/1997PA05S030.
Pełny tekst źródłaAksamit, Anna Natalia. "Temps aléatoires, grossissement de filtration et arbitrages". Thesis, Evry-Val d'Essonne, 2014. http://www.theses.fr/2014EVRY0007/document.
Pełny tekst źródłaThis thesis treats the problems settled in elargement of filtration theory. It consists of two parts.The first part is devoted to random times. We study the properties of different classes of random times from enlargement of filtration point of view.The second part concerns the study of the stability of the non-arbitrage condition under anlargement of filtration. We are mainly interested in no bounded profit with bounded risk condition. We study absence of arbitrage in the case progressive enlargement up to random time. Then we look at the case of initial enlargement with random variable satisfying Jacod's hypothesis
Frappart, Matthieu. "Traitement d'effluents modèles de l'industrie laitière par filtration dynamique". Compiègne, 2006. http://www.theses.fr/2006COMP1651.
Pełny tekst źródłaLn an environmental context, the dairy industry must find new solutions to treat this process waters which, although not toxic, have a strong polluting capacity because of the raw material losses (lactose, milk proteins). The membrane processes are weIl adapted to this type of application. Studies were carried out in nanofiltration and reverse osmosis in order to produce a reusable water or water which can be rejected into the natural environment according to rejection standards. These studies, carried out on vibrating and rotating systems avoiding the fouling of membranes and thus maintaining their performances in terms of fluxes and retentions, have permitted, in nanofiltration, to obtain a rejectable water, whereas the classical crossflow systems do not allow it, and to reach, in reverse osmosis, specific characteristics of reuse (boiler feed water for example)
Mahnic̆-Kalamiza, Samo. "Effects of electrical and thermal pre-treatment on mass transport in biological tissue". Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2247/document.
Pełny tekst źródłaAn electric field of sufficient strength can cause an increase of conductivity and permeability of cell membrane. Effect is known as electroporation and is attributed to creation of aqueous pathways in the membrane. Quantifying mass transport in connection with electroporation of biological tissues is an important goal. The ability to fully comprehend transport processes has ramifications in improved juice extraction and improved selective extraction of compounds from plant cells, improved drug delivery, and solutions to environmental challenges. While electroporation is intensively investigated, there is a lack of models that can be used to model mass transport in complex structures such as biological tissues with relation to electroporation. This thesis presents an attempt at constructing a theoretical mathematical description – a model, for studying mass (and heat) transfer in electroporated tissue. The model was developed employing conservation and transport laws and enables coupling effects of electroporation to the membrane of individual cells with the resulting mass transport or heat transfer in tissue. An analytical solution has been found though the model can be extended with additional dependencies to account for the phenomenon of electroporation, and solved numerically. Thesis comprises five peer-reviewed papers describing electroporation in the food industry, model creation for the problem of diffusion, translation of the model to the mathematically-related case of juice expression, model validation, as well as suggestions for possible future development, extension, and generalization. An additional chapter is dedicated to transfer of heat in tissue
Wu, Dong Li. "Density models and applications to counterparty credit risk". Thesis, Evry-Val d'Essonne, 2013. http://www.theses.fr/2013EVRY0035/document.
Pełny tekst źródłaThis thesis is about density models of default times and applications to credit and counterparty risk. The rest part is a theoretical contribution to the study of projections on different filtrations of the Radon-Nikodym density of a measure change. The main result is a characterization of the measure changes preserving immersion in a density setup, obtained by application of our projection formulas. The second part is about an informational dynamization of the Gaussian copula model of portfolio credit risk, resulting in a density model of default times suitable to del with dynamic issues such as hedging of CDO through CDS or counterparty risk on credit derivatives. Here the main contributions are the introduction of the dynamic perspective, which allows one to give a theoretical justification to the Gaussian copula bump sensitivities used by practioners, and the application to CVA computations on CDS
So, Wing Kin. "Development of low-cost membrane module for direct sewage filtration /". View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202007%20SO.
Pełny tekst źródłaFLEISCHMAN, GREGORY JOSEPH. "FLUID FILTRATION FROM CAPILLARY NETWORKS (MICROCIRCULATION, MATHEMATICAL MODELING)". Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/187998.
Pełny tekst źródłaWong, Katherine Wing-Shan. "Design of a small-scale continuous linear motion pharmaceutical filtration module". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/60210.
Pełny tekst źródłaCataloged from PDF version of thesis.
Includes bibliographical references (p. 50).
A new small-scale continuous linear motion pharmaceutical filtration prototype was designed, fabricated, and tested. The goal of this unit is to filter an Active Pharmaceutical Ingredient (API) from a mixture of API molecules, ethyl acetate, and possible contaminants. This unit is important in the development of a small-scale continuous pharmaceutical manufacturing process by Novartis, which would lower costs and increase product flexibility and production. A compliant blade is mounted onto a linear guide assembly and driven by a stepper motor to filter the API mixture through a porous metal filter. The mixture enters into the middle of the filtration unit; the excess ethyl acetate and dissolved contaminants are pulled through the filter by a vacuum pump, leaving the desired API molecules on the filter surface. The API is then moved across the filter by the blade to output collectors at either end. The unit itself takes up 0.03 cubic meters, an eighth of the size of the current equivalent production model. This unit has been tested to successfully filter the API from the rest of the mixture and will help determine if a rotary or linear style filtration system should be used as the final design.
by Katherine Wing-Shan Wong.
S.B.
Argillier, Jean-François. "Filtration de macromolecules flexibles a travers des micropores modeles". Paris 6, 1989. http://www.theses.fr/1989PA066541.
Pełny tekst źródłaXie, Jing. "Models for filtration during drilling, completion and stimulation operations /". Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3008475.
Pełny tekst źródłaBorel, Philippe. "Etude expérimentale et modélisation de la filtration centrifuge : application au dimensionnement des essoreuses". Toulouse, INPT, 1986. http://www.theses.fr/1986INPT006G.
Pełny tekst źródłaKhabthani, Sondes. "Modélisation mathématique et numérique du problème de filtration tangentielle". Paris 6, 2010. http://www.theses.fr/2010PA066055.
Pełny tekst źródłaVigneswaran, Saravanamuthu. "Contribution à la modélisation des phénomènes de filtration dans la masse". Toulouse, INPT, 1987. http://www.theses.fr/1987INPT047G.
Pełny tekst źródłaHabibi, Sepideh. "Caractérisation multi-échelles d'un système de filtration en présence d'un biofilm". Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2014. http://www.theses.fr/2014ECAP0042/document.
Pełny tekst źródłaDuring a membrane filtration process, a liquid medium is filtered through a membrane(selective barrier). The applied driving force between two sides of the membrane can be a gradient of pressure, temperature or a chemical/electrical potential.In pressure driven filtration processes (application of a pressure gradient as driving force between two sides of the membrane), certain components of the liquid medium pass through the membrane, while others are retained at the membrane surface. These processes are widely used as separation techniques in different industrial fields like waste water treatment, biotechnology, food and pharmacy. Compared to conventional techniquesof separation (distillation, crystallization, ...), membrane processes offer more compact installations with more optimized operational costs. Moreover, membrane processes are mainly performed in absence of chemical additives and phase change. In this work we focus on the pressure-driven microfiltration membrane processes.The main disadvantage of these processes is the continuous accumulation of particles on the membrane surface. This affects the membrane selectivity, modifies the quality and the quantity of the liquid passing through the membrane and leads to an increase of energy costs. Membrane fouling occurs in all types of membrane processes and therefore is known as the major obstacle for widespread use of these processes. Different techniques are used to overcome the effects of fouling on the membrane performance : physical-chemical treatment of used membranes, modification of the operational conditions (tangential flow of the feed solution to the membrane is often applied for minimizing the particle accumulation to the membrane surface), use of membranes less susceptible to fouling, etc. Depending on the nature of the treated solutions, the deposited particles are highly variable. Microorganisms, natural organic matter such as proteins, polysaccharides, humid substances, inorganic oxides and salts contribute notably to membrane fouling.It should be noted that membrane fouling problem is a multi-physics (hydrodynamics,mass transport, physics, chemistry), multi-scale (different length scales are involved:molecules, pores and membrane surface) and time dependent (evolution of the membrane microstructure and the molecule-surface interactions) phenomena.In the last decades, a huge number of experimental studies have been invested to understand fouling mechanisms. It has been pointed out that membrane physicochemical properties, solution chemistry and operational conditions are the three major factors affecting the fouling mechanisms. In parallel, theoretical models have been proposed to confirm/describe the experimental observations.Modeling of membrane fouling is an essential tool for assessing the fouling mechanisms. It helps predicting the membrane performance and consequently finding adapted strategies to prevent their modification during the filtration process.In general, the models can be classified into two main categories: mass transport models which focus on solute permeation during the filtration process, and fouling models based on particle or solute blocking within the membrane porous structure. In most of the cases, models depend strongly on the empirical or semi-empirical parameters and thus remain phenomenological. Two main objectives have been set for the present work: 1. Get a better understanding of the membrane fouling mechanisms during filtration of a liquid medium containing suspended microorganisms. It should be pointed out that several Industrial streams and wastewaters belong to this kind of effluents.2. Propose a macroscopic model describing the observed fouling mechanisms. [...]
Kalliokoski, J. (Juha). "Models of filtration curve as a part of pulp drainage analyzers". Doctoral thesis, Oulun yliopisto, 2011. http://urn.fi/urn:isbn:9789514294273.
Pełny tekst źródłaTiivistelmä Paperimassasulpun suotauttaminen on paperinvalmistuksen avainprosesseja. Sitä on mitattu monenlaisilla analysaattoreilla ja kuvattu sekä fysikaalisilla että kokeellisilla matemaattisilla malleilla. Tämän tutkimuksen päätavoite on kehittää suotautuvuusanalysaattorin kokeellista matemaattista mallia. Tutkimuksessa viiran halkaisija (10 cm) sekä näytteen määrä (1000 cm3), sakeus (0.3 %) ja lämpötila (20 ˚C) olivat suunnilleen samat kuin Canadian standard freeness –analysaattorissa. Järjestelmä mittasi suotautettua tilavuutta, suotauttavaa painetta ja suodoksen sakeutta. Suotautuspaineet olivat 80 kPa:n ali- ja ylipaineen väliltä. Testattavana oli hioketta, painehioketta ja termohierrettä sekä kemiallista massaa, joiden freeness oli 30 ml:sta 600 ml:aan. Analysaattoriin rakennettu vakiointijärjestelmä sääti näytteen sakeuden, tilavuuden ja lämpötilan niin tarkasti halutuiksi, että näiden vaihtelu ei olisi muuttanut freeness-arvoa edes prosenttia. Suureiden kehittymiselle johdettiin kaavat. Niiden avulla voidaan laskea ne näytteen arvoalueet, joilta halutut tavoitearvot voidaan saavuttaa. Optisesti mitattu suodoksen sakeus riippui massatyypistä ja hiipui lähes nollaksi ennen kuin 150 ml oli suotautettu. Suotautus muutti optisesti aktiivisen hienoaineen osuutta. Tämän työn suodoskäyrän mallissa aika (t) on verrannollinen suotautetun tilavuuden (V) kokeellisen potenssiin: Ve = kt. Mallinnuksen ajaksi lisätään apuparametri (Ve = kt+V0e), jotta suotautuksen alku ei huononna mallia. Sovituksen korrelaatiokerroin oli yli 0.999. Eksponentin arvo vaihteli vähän yli yhdestä melkein kolmeen, joten Darcyn lain mukainen eksponentin arvo 2 osoittautui erikoistapaukseksi. Mallin ja painemittauksen avulla lasketut ominaisresistanssit muuttuivat suotautuksen kuluessa ja riippuivat myös massatyypistä. Mallin avulla voitiin laskea näytteen freeness sekä suodattaa mittauskohinaa
Bouzerar, Roger. "Filtration dynamique dans un module plan à disque rotatif : Application à des suspensions minérales". Compiègne, 1999. http://www.theses.fr/1999COMP1202.
Pełny tekst źródłaOgnier, Stéphanie. "Contribution pour le contrôle dynamique du colmatage en bioréacteur à membranes". Montpellier 2, 2002. http://www.theses.fr/2002MON20143.
Pełny tekst źródłaHamdi, Chaima. "Applications de l’homologie persistante pour la reconnaissance des formes". Mémoire, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/10675.
Pełny tekst źródłaBENALI, ABDALLAH. "Filtration a travers une membrane : analyse et simulation de modeles de diffusion-convection". Reims, 1998. http://www.theses.fr/1998REIMS036.
Pełny tekst źródłaBoichot, Raphael. "Filtration des particules issues des moteurs Diesel par matrices fibreuses plongées dans un champ électrique". Chambéry, 2005. http://www.theses.fr/2005CHAMS008.
Pełny tekst źródłaThe filtration of diesel particulate matter is a major industrial and environmental stake, since the discovery of carcinogenic effects of this kind of particles and the advent of Euro IV (2005) and Euro V (2008-2010) regulations. The aim of this study is to point out the industrial practicability of filtration of this particles by a fibrous media immersed in an electric field. The global shape of this process is a wire-to-cylinder electrostatic precipitator with an porous earth collecting electrode, the whole flow passing through it. It was shown that this process is essentially an agglomerator and not a filter, and that it allows an increase by 50 of the mean diameter of particles. The process, by its completely new and original shape, allows to work with only several millisecondes of residence time. The energetic intensity is so important that the whole volume is compatible with an installation on vehicles. On a technical point of view, the efficiency of this electrostatic agglomerator depends only little on the fibrous matrices or high voltage electrodes used. It is in return very influenced by the quality of electric insulation by ceramic plugs between the canning and high voltage electrodes, and by the discharge polarity. During the last tests with a very optimised agglomerator, we obtain a decrease of 90% in number of the submicronic particulate matter (on a NEDC cycle), with a fuel over-consumption of less than 1%, which corresponds to an "volumic energy” of about 1 Joule per litre. A mathematical model of agglomerator was constructed during this study, integrating the last recent improvements in numeric simulation of Maxwell's equations in presence of space charge, integrating the particle turbulence and taking into account the fractal dimension of diesel aerosol particles. The process is nowadays in an advanced industrialisation stage
Genty, Joël. "Modélisation et simulation dynamique du couplage bioréaction-filtration : application aux fermentations alcoolique et lactique". Châtenay-Malabry, Ecole centrale de Paris, 1992. http://www.theses.fr/1992ECAP0262.
Pełny tekst źródłaMallikarachchi, Thanuja D. "Performance Models for Manufactured Stormwater Best Management Practices with Sedimentation and Filtration in Series". Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1547131754278262.
Pełny tekst źródłaLiu, Ming Gang. "Étude de la texture des membranes et de leur interaction avec des suspensions au cours d'une filtration dynamique". Compiègne, 1992. http://www.theses.fr/1992COMPD496.
Pełny tekst źródłaKadel, Sabita. "Impact of physicochemical properties of filtration membranes on peptide migration and selectivity during electrodialysis with filtration membranes : development of predictive statistical models and understanding of mechanisms involved". Doctoral thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/66602.
Pełny tekst źródłaDuring electrodialysis with filtration membranes (EDFM), charged peptides selectively migrate through filtration membranes (FMs) to their respective anionic (ARC) or cationic (C + RC) peptide recovery compartments. Consequently, the type of interactions occurring between FM and peptide at the interface, due to their physicochemical properties, must have significant impact on overall EDFM performances (peptide migration and selectivity). Therefore, the main objective of this doctoral thesis was to investigate the major FM properties that contribute to peptide-membrane interactions at the interface, which either facilitates or hinders global migration and selective separation of peptides during EDFM, and to understand the mechanisms involved behind those interactions. Thus, in this study, 16 FMs, characterized in terms of their physicochemical properties (zeta potential, conductivity, hydrophilic/hydrophobic nature of the surface and pores, thickness, roughness, porosity and percentage of macropores distribution in filtrating layer) were tested during EDFM to simultaneously separate anionic and cationic peptides from a well-characterized complex whey protein hydrolysate. In the first study, 6 FMs were tested, differing in terms of membrane materials, including one ultrafiltration (polyethersulfone (PES)) as a control and 5 microfiltration ( one polyvinylidene fluoride (PVDF) and four polyvinyl chloride (PVC)-silica: two functionalized (sulfonyl or amino) or two non-functionalized). Redundancy analysis (RDA) and multivariate regression analysis demonstrated that at least two FM properties among zeta potential, pore/surface hydrophilicity, porosity and roughness significantly impacted the migration of any charged peptide. In addition, the important effect of pore size on peptide selectivity was also reported. Finally, predictive statistical models that link each peptide migration with significant FM properties were proposed. In the second study, which was carried out on PES membranes with a wide range of molecular weight cut-offs (MWCOs) (5 kDa to 300 kDa), a linear relation was noticed between MWCO and global peptide migration (GPM) to both recovery compartments. However, the selective peptide migration to A - RC or C + RC was found to be influenced by the vi MWCO of FMs as well as physicochemical properties (charge and molecular weight (MW)) of peptides. For instance, the migration of a peptide having low MW and low charge (positive or negative) was favored when a FM with small MWCO was used, while the opposite was observed for a peptide having high MW and high charge. In the third study, the effect of combination of membrane material (PAN, PES and PVDF)/MWCO (30 and 50 kDa) on peptide migration and selectivity was first studied. The simple effect of membrane material and MWCO on GPM to C+ RC was observed, while the combined effect of membrane materials/MWCO on GPM to A - RC and selective peptide migration to both recovery compartments was observed. Secondly, a RDA was performed on the data obtained for all the selective FMs tested in this doctoral research, which demonstrated the significant impact of zeta potential, conductivity, roughness and percentage of macropores distribution in the filtrating layer of FMs on GPM. Concerning selective peptide migration, in addition to the aforementioned FM properties, the significant impact of contact angle was noticed for at least one anionic and/or cationic peptide migration to their respective recovery compartments. These significant FM properties were found to trigger different interactions such as electrostatic, size exclusion and hydrophilic/hydrophobic between FM and peptide at the interface resulting in either facilitation or inhibition of peptide migration. Finally, global predictive statistical models were developed for GPM and each individual peptide migration to ARC and/or C+ RC based on these significant FM properties, which allow the estimation of their migration behavior when FMs having a wide range of physicochemical properties are used during EDFM. The results obtained in this Ph.D. thesis demonstrated, for the first time, the significant correlation between physicochemical properties of FMs, and peptide migration and selectivity during EDFM. The predictive models developed in this study can be used for the range of peptides and FMs tested. Moreover, the types of interactions occurring between FMs and peptide at the interface, and mechanisms and explanations proposed in this study can be applied to understand all types of peptide/membrane interactions. Validation of such models vii by using different sources of hydrolysates or different FMs or a hydrolysate produced by other enzymes will be the main perspectives of this research work.
Marais, Pierre Charl. "The hydrodynamic characterisation of an axial-flow membrane module". Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52531.
Pełny tekst źródłaENGLISH ABSTRACT: The hydrodynamics of a hollow fibre membrane module for the ultrafiltration of potable water were investigated. The purpose was to use a hydrodynamic model to predict the permeate flux for modules of various dimensions. Various models were considered, but most of them could not account for important effects such as macroscopic radial gradients and wet fibre expansion, found in hollow-fibre membrane modules. The Porous Medium Model was found to be a suitable model and it was used together with a finite element software package, Fastflo, to solve for the pressure distributions inside the membrane modules and predict permeate flux. The permeability of the membranes was obtained using a combination of numerical and experimental procedures and was found to be 2.3 x 10-13m. A cost analysis was performed to find the most economical module dimensions (outer diameter and length) for any required product flow rate. It was assumed that the cost of the fibres and module housing comprised the capital cost, while the operating cost consisted of the pumping energy. A capital recovery factor of 0.3 was used to convert capital costs to a yearly cost. It was found that the optimum module dimensions are an outer diameter of between 90mm and 160mm and a length of 0.6m. Finally the pressure distributions on the lumen and shell sides during both cross-flow filtration and backwash were examined. Shade plots proved useful for identifying possible areas of stagnant flow, as well as indicating where backwash is the most effective.
AFRIKAANSE OPSOMMING: Die hidrodinamika binne-in 'n holvesel membraanmodule vir die ultrafiltrasie van drinkwater is ondersoek. Die doel was om 'n hidrodinamiese model te gebruik om die permeaatvloed vir modules van verskeie dimensies te voorspel. Verskillende modelle is oorweeg, maar die meeste kon nie belangrike faktore soos makroskopiese radiale drukqradiente of nat veselverlenging in ag neem nie. Die Poreuse Medium Model was die mees geskikte model en is gebruik saam met Fastf/o, 'n sagteware pakket wat gegrond is op die eindige element metode, om vergelykings vir die drukverspreiding binne-in die module op te los en permeaatvloed te voorspel. Die permeabiliteit van die membrane is verkry met behulp van numeriese en eksperimentele prosedures en 'n waarde van 2.3 x 10-13 m is bepaal. Hierna is 'n koste-analise uitgevoer om die mees ekonomiese module afmetings (Iengte en buitedeursnit) te bepaal vir 'n gegewe produk vloeitempo. Daar is aanvaar dat kapitaalkoste bestaan uit die koste van vesels en module-omhulsel, terwyl bedryfskoste bereken is deur die hoeveelheid energie benodig om die pomp aan te dryf. 'n Kapitaalherwinningsfaktor van 0.3 is gebruik om kapitaalkoste om te skakel na 'n jaarlikse koste. Die optimum module afmetings is 'n lengte van 0.6m en 'n buite-deursnit van tussen 90mm en 160mm. Laastens is die drukverspreidings tydens beide kruisvloeifiltrasie en die terugspoelproses ondersoek. Areas van stagnante vloei kan deur middel van skadu-grafieke geYdentifiseer word, terwyl dit ook moontlik is om die terugspoelproses te optimeer.
Tenailleau, Véronique. "Etude comparative de la capacite de filtration de divers masques chirurgicaux : synthese bibliographique et resultats d'une methode experimentale realisee sur differents modeles". Strasbourg 1, 1991. http://www.theses.fr/1991STR15081.
Pełny tekst źródłaBenmachou, Kader. "Étude et modélisation du colmatage d'un filtre plissé". Toulouse, INPT, 2005. https://hal.science/tel-04582023.
Pełny tekst źródłaThe purpose of this work is to develop an approach to simulate numerically the behaviour of the pleated filters, and thus limit the number of experimental tests. The first part of this work concerns the analysis and the modelling of filtration through fibrous media. An experimental study relating to the microstructure of fibrous media and its filtration capacities was carried out. Then, assuming that the particles are captured by sieving, a clogging model was developed. This model describes well the two successive phases of clogging observed in the experiments namely depth filtration and cake filtration. In a second part, the fluid flow, the particle transport and capture are studied and modelled in an elementary pleat and within the complete filter. The validation of the model is carried out by considering both experimental results and CFD simulations using Fluent®. The results are discussed according to the geometrical characteristics of the filter element
Ben, Hassan Ines. "Analyse multi-échelle de la filtration sur microsive de particules modèles inertes et biologiques : caractérisation in situ du dépôt par microscopie confocale". Phd thesis, INSA de Toulouse, 2014. http://tel.archives-ouvertes.fr/tel-01073549.
Pełny tekst źródłaXie, Xiaomin. "Investigation of Local and Global Hydrodynamics of a Dynamic Filtration Module (RVF Technology) for Intensification of Industrial Bioprocess". Thesis, Toulouse, INSA, 2017. http://www.theses.fr/2017ISAT0020/document.
Pełny tekst źródłaThis thesis focuses on the understanding and the control of dynamic interactions between physical and biological mechanisms considering an alternative membrane separation into industrial bioprocess. It aims to carry scientific knowledge related to the control of bioreaction considering complex hydrodynamics and retention-permeation locks specific to membrane separation. A dynamic filtration technology, called Rotating and Vibrating Filtration (RVF), was investigated. It consists of filtration cells in series including two flat disc membranes fixed onto porous substrates in the vicinity of a three-blade impeller attached to a central shaft. This simple mechanical device runs continuously and generates a high shear stress as well as a hydrodynamic perturbation in the narrow membrane-blade gap. Several scientific and technical locks motivating this work are to characterize and to quantify (i) the velocity fields locally and instantaneously, (2) the shear stresses at membrane surface and (3) the mechanical impact on microbial cells.To this end, experiments and numerical simulations have been performed to investigate the hydrodynamics at global and local scales under laminar and turbulent regimes with Newtonian fluids under biotic and abiotic environment. For global approach, investigation of Residence Time Distribution (RTD) and thermal balance was carried out and compared to the previous global study (power consumption and friction curves). Analytical study of distribution functions was conducted and statistical moments were calculated and discussed. A systemic analysis was used to describe the hydrodynamic behaviors of the RVF module. Combining Computational Fluid Dynamics (CFD) and RTD observations, it leads to demonstrate dysfunctioning conditions and area. For the local approach, Particle Image Velocimetry (PIV) was be carried out in both horizontal and vertical planes and compared to CFD simulation. PIV preliminary study was conducted with a trigger strategy to access through angle-resolved measurements to an averaged velocity field. PIV further study were performed with a non-trigger strategy and applied to Proper Orthogonal Decomposition (POD) analysis in order to identify the coherent structure of the flow by decomposing the organized and turbulent fluctuations. For the bioprocess application, an exploratory work characterized the effect of Dynamic Filtration on prokaryote cell population (Escherichia coli) by quantifying cell integrity or damage as a function of time and rotation speed during filtration process in turbulent regime
Doubrovine, Nathalie. "Influence d'un écoulement instationnaire intermittent sur les performances d'un procédé de filtration tangentielle". Toulouse, INSA, 1992. http://www.theses.fr/1992ISAT0043.
Pełny tekst źródłaLeyrat-Maurin, Anne. "Modélisation du passage d'une capsule dans une constriction : application à la filtration érythrocytaire". Compiègne, 1993. http://www.theses.fr/1993COMPD570.
Pełny tekst źródłaIlina, Tatiana. "Modèles pseudo-diphasiques de transport facilité des colloïdes en milieux faiblement perméables". Thesis, Vandoeuvre-les-Nancy, INPL, 2007. http://www.theses.fr/2007INPL001N/document.
Pełny tekst źródłaThe aim of this PhD thesis is to create and to develop a colloid suspension transport model in the saturated porous media that will be able to detect and to predict the apparition of the difference between water and suspension velocity; to distinguish cases of acceleration and of deceleration of the colloidal particles and also to calculate the two velocities using the initial information on the properties of porous media and of particles. We are proceeded by two different manners. Firstly, we are proposed an analytical method of calculation of enhancement velocity factor that can be introduced in the classic colloid transport model that is single-phase one. Secondly, we are proposed a new phenomenological mathematical approach to describe a colloid transport. To develop this approach, we are used the fact that two velocities appear automatically in the two-phase transport model. Thus our model must be similar to two-phase one. Therefore, for our mathematical model we are refused the traditional approach that assumes a transport of a single-phase liquid
Esch, Lukas Hendrik [Verfasser]. "Der Einfluss extrazellulärer Strömungspotentiale auf die glomeruläre Filtration : eine Untersuchung am Modell der Ratte / Lukas Hendrik Esch". Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2014. http://d-nb.info/1052161057/34.
Pełny tekst źródłaFoto, Bienvenu Armand Éric. "Elaboration d'un pilote de filtration horizontale pour la potabilisation de l'eau dans les pays en voie de développement : aspects (bio) physico-chimiques". Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10006/document.
Pełny tekst źródłaThe objective of this thesis concerned the elaboration of a horizontal flow filtration pilot in Central African Republic because of a lack of potable waters in this country. In the conception of this pilot, treatment processes which should be chosen for riverine water purification, have to be low energy cost and easy to be implemented. Taking into account these considerations, we decided to employ the low-filtration method with the sand as the adsorbent. Indeed, this latter is known to behave as a natural adsorbent through hydrogeological processes in sols. After itemizing pluviometric data. it was shown that ground-waters possessed good water quality, whereas aquifers in low depths were found to be instead contaminated. A pilot was built by respecting the recommendations established by Eaux de Paris located at Bangui Performances and quality of treated waters were followed up, and the data obtained during the running were found to be in good accordance first with potable-water criteria with a water production of 400L/h and second with water-quality norms which were usually recommended for a raw water before its chlorination. Modelisation tests on the transit of water in the pilot were carried out using MODFLOW. For model calibration, it was used the dye Fluorescein as a tracer. The adsorption properties of sand in this pilot were studied owing to the combined use of the techniques:SEM/EDS;BET;ICP-AES;CHNS;UV/visible. In comparison with the starting sand used in the construction of the pilot, all the data showed clearly that the adsorption capacity of this sand increases with time owing to surface modifications and clays and iron oxides / hydroxides depositions in cracks
Mtibaa, Mohamed. "Οptimisatiοn de cοuplage Ρrοcédé/Ρrοpriétés/Fiabilité des Structures en Μatériaux Cοmpοsites Fοnctiοnnels". Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMLH03.
Pełny tekst źródłaThis research focuses on the challenges and interactions between the manufacturing processes (Resin Transfer Molding ‘RTM’ and Compression Resin Transfer Molding ‘CRTM’), the mechanical properties, and the reliability of composite material structures; more specifically the functional composites. A number of numerical models have been developed for simulating the suspension (resin + particles) impregnation through the fibrous medium (fibers) in the RTM and CRTM processes. These models are validated by comparing their results with experimental, semi-analytical, and analytical ones from the literature. A parametric study is carried out to demonstrate the impact of various process parameters on particles’ distribution in the final composite. Moreover, a comparison between the injection and compression modes is done. The results of this part show that the distribution of particles in the final part depends on the initial concentration, the distance travelled, and the initial fibers’ volume fraction. However, it is independent of the parameters values of injection and compression. It is also observed that the CRTM process with imposed pressure injection and imposed force compression represents the most favorable scenario for producing composite parts.For the purpose of controlling the final particles’ distribution in the composite material, manufactured by the RTM process, two key steps have been identified. The first step consists in a sensitivity analysis that examines three parameters: the temporal evolution of the initial injected particles’ concentration, the injection pressure field and the initial fibers’ porosity. The conclusions indicate a minimal impact of the initial porosity and the injection pressure field; while the evolution of the initial concentration of the injected particles has a dominant effect. In a second step, an optimization algorithm is implemented in the numerical model of the RTM process. It is used to determine the optimal configuration of the initial injected particles’ concentration’s evolution; in order to approximate the particles’ distribution in the final composite to the desired profiles. The obtained results from the genetic algorithm provide a very satisfactory control of this distribution. To complete this section, a model, estimating the mechanical properties of the manufactured part, is developed. It is found that there is a positive correlation between the particles’ fraction and certain mechanical properties, namely the elastic modulus E11 and E22, and the shear modulus G12 and G23. Nevertheless, the Poisson’s ratio (Nu12) is inversely proportional to the particles’ fraction. Also, the shear module G12 is the most significantly influenced by this fraction.Following this, the control of the mechanical properties of the composite parts, manufactured by the CRTM process, is targeted, and compared to the results of the RTM process. The conclusions reveal that the RTM process offers a better control of these properties. Whereas, the CRTM process improves considerably the mechanical properties of the parts due to its compression phase, which increases the fibers’ volume fraction and consequently enhances these properties.Finally, a static analysis is conducted based on the developed numerical model that uses the finite element method (Ansys APDL). This model is combined with those of the CRTM process and the mechanical properties calculation. An optimization algorithm is integrated in our global model to adapt the mechanical properties of the composite part according to the configuration (cantilever or simply supported) and the load distribution. Moreover, it minimizes the composite part’s weight and ensures the respect of the predetermined mechanical constraints such as the maximum deformation limit. The obtained results correspond perfectly to these objectives
Gervais, Pierre-Colin. "Études expérimentale et numérique du colmatage de filtre plissé". Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0007/document.
Pełny tekst źródłaPleated filters are widely used in air treatments because of the advantageous effective surface to overall dimension ratio they offer. Their major drawback though resides in their reduced lifetime which still needs to be controlled. Indeed, when clogging, the pressure drop considerably increases, the filtration flow is then no longer maintained which might lead to the deterioration of the media. It is then crucial to characterize the evolution of the pressure drop under operating conditions in order to best design these equipments. Part of our work consisted in studying how the operating conditions influence the geometry of the deposit. To do so, we used Single-Photon Emission Computed Tomography (SPECT), a non-destructive imaging technique that keeps intact the particle structuring. The visualization of aerosol deposit at the beginning of the filtration process allows observing preferential particle deposition on the whole height of the pleat. A numerical approach was used to study the permeability of bimodal fibrous media and we experimentally studied the local velocity as well as the biphasic flow inside pleated filter media. Comparison between experiments and simulations allowed us to validate the Geodict code for a wide range of media properties and velocities. Regarding bimodal fibrous media, the fast data acquisition has allowed testing several existing models which resulted in classifying them in a unique way. If the experimental results on the initial deposition in pleated filters are encouraging, those related to beforehand clogging point to several improvements regarding the technique we used
Wu, Ching-Tang. "Construction of Brownian Motions in Enlarged Filtrations and Their Role in Mathematical Models of Insider Trading". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät II, 1999. http://dx.doi.org/10.18452/14364.
Pełny tekst źródłaIn this thesis, we study Gaussian processes generated by certain linear transformations of two Gaussian martingales. This class of transformations is motivated by nancial equilibrium models with heterogeneous information. In Chapter 2 we derive the canonical decomposition of such processes, which are constructed in an enlarged ltration, as semimartingales in their own ltration. The resulting drift is described in terms of Volterra kernels. In particular we characterize those processes which are Brownian motions in their own ltration. In Chapter 3 we construct new orthogonal decompositions of Brownian ltrations. In Chapters 4 to 6 we are concerned with applications of our characterization results in the context of mathematical models of insider trading. We analyze extensions of the nancial equilibrium model of Kyle [42] and Back [7] where the Gaussian martingale describing the insider information is specified in various ways. In particular we discuss the structure of insider strategies which remain inconspicuous in the sense that the resulting cumulative demand is again a Brownian motion.
Guillot, Geneviève. "Transport de macromolécules en solution à travers des membranes poreuses modèles". Paris 11, 1986. http://www.theses.fr/1986PA112297.
Pełny tekst źródłaAn experimental study of the transport of solutions of flexible polymer chains through membranes with fine pores is presented in this work, for pores and polymers of comparable sizes. Membranes have been prepared by heavy ion irradiation of polycarbonate films, followed by chemical etching which reveals the irradiation latent tracks into cylindrical pores spanning the film (5 to 100 microns). The pore radius has been controlled by direct observation under a scanning electron microscope, and by conductivity and permeability measurements. The diffusion of large polystyrene chains (weights larger than one million) dissolved in ethyl acetate has been followed across these membranes, by measuring the solution concentrations by absorption spectroscopy. For dilute solutions, the measured diffusion coefficient can be described by a hard sphere model. However chains of size larger than the pore size diffuse more rapidly than hard spheres, moreover their diffusion coefficient increases drastically with concentration. We attribute this acceleration to the increase of the partition coefficient between the inside and outside of the pore, due to the chain flexibility which allows the chains to elongate to enter the pore, and to the larger repulsion between chains at higher concentrations. This effect has also been observed with solutions of mixtures of large and small chains of the same chemical composition. Some preliminary results of filtration experiments are also reported, about the amount of transported polymer and about the evolution of the membrane permeability after filtration. They confirm model suggested by S. Daoudi and F. Brochard (1978) for chain transport by elongation under flow at the pore entrance
Mellal, Mounir. "Application de la filtration dynamique à la microfiltration des suspensions et à la séparation des oligosaccharides par ultra et nanofiltration". Compiègne, 2006. http://www.theses.fr/2006COMP1656.
Pełny tekst źródłaSome microbial oligosaccharides of small degrees of polymerisation (DP) between 3 and 7 have interesting biological properties. These oligosaccharides are purified and fractionated easily at pilot scale, but the obtained amounts with the classical methods such as chromatography are not suitable for industrial applications. So it is necessary to find a new process in order to produce large quantities. Membrane processes are suitable for this type of separations. We have investigated the fractionation of oligogalacturonanes and oligoglucuronanes in order to obtain oligomers with different and low polymerisation degrees. Ours studies were performed in a rotating disk system to avoid membrane fouling and to maintain its flux and rejection performance. We used ultrafiltration and nanofiltration processes to obtain oligomers with 5
Foto, Bienvenu Armand Éric. "Elaboration d'un pilote de filtration horizontale pour la potabilisation de l'eau dans les pays en voie de développement : aspects (bio) physico-chimiques". Electronic Thesis or Diss., Lille 1, 2015. http://www.theses.fr/2015LIL10006.
Pełny tekst źródłaThe objective of this thesis concerned the elaboration of a horizontal flow filtration pilot in Central African Republic because of a lack of potable waters in this country. In the conception of this pilot, treatment processes which should be chosen for riverine water purification, have to be low energy cost and easy to be implemented. Taking into account these considerations, we decided to employ the low-filtration method with the sand as the adsorbent. Indeed, this latter is known to behave as a natural adsorbent through hydrogeological processes in sols. After itemizing pluviometric data. it was shown that ground-waters possessed good water quality, whereas aquifers in low depths were found to be instead contaminated. A pilot was built by respecting the recommendations established by Eaux de Paris located at Bangui Performances and quality of treated waters were followed up, and the data obtained during the running were found to be in good accordance first with potable-water criteria with a water production of 400L/h and second with water-quality norms which were usually recommended for a raw water before its chlorination. Modelisation tests on the transit of water in the pilot were carried out using MODFLOW. For model calibration, it was used the dye Fluorescein as a tracer. The adsorption properties of sand in this pilot were studied owing to the combined use of the techniques:SEM/EDS;BET;ICP-AES;CHNS;UV/visible. In comparison with the starting sand used in the construction of the pilot, all the data showed clearly that the adsorption capacity of this sand increases with time owing to surface modifications and clays and iron oxides / hydroxides depositions in cracks
Lefèvre, Delphine. "Étude expérimentale, modélisation et simulation de la filtration lors de l'écoulement d'une résine chargée de particules à travers un renfort fibreux dans les technologies LCM". Lille 1, 2007. http://www.theses.fr/2007LIL10144.
Pełny tekst źródłaMaranges, Claude. "Etude de l'influence d'un jet instationnaire turbulent sur les performances de la filtration tangentielle : application aux bioréacteurs à membranes". Toulouse, INSA, 1995. http://www.theses.fr/1995ISAT0033.
Pełny tekst źródłaGérard, Maryline. "Études des interactions entre les solutés et la membrane lors de l'hydrolyse enzymatique de l'hémoglobine bovine dans un réacteur couplé à un module d'ultrafiltration". Compiègne, 1998. http://www.theses.fr/1998COMP1132.
Pełny tekst źródłaPapet, Sébastien. "Etude de la synthèse de matériaux inorganiques en milieu CO2 supercritique. Application à l'élaboration de membranes minérales de filtration tangentielle". Montpellier 2, 2000. http://www.theses.fr/2000MON20116.
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