Дисертації з теми "Porous fibres"
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Lozano, Flavien. "Elaboration de matelas à base de fibres de verre par voie humide." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAI001.
Повний текст джерелаGlass fibre - based mats produced by a wetlaid process have industrial applications as a battery separator and insulation materials (core of vacuum insulation panels). These materials are mainly made with sub-micron fibres which relatively expensive and can present a risk to health. This project is a contribution to the production of glass fibre-based mats by a wet-laid process to add value to coarser fibres, the final product should respect precise specifications. We have been led to study the behavior of glass fibers in different stages of the process and to characterize the resulting mats. We investigated especially the physico-chemical behavior of aqueous suspensions of glass fiber. We have characterized structure properties, the mechanical resistance to traction, the compressibility and the thermal conductivity of fibrous mats. The experimental work has allowed us to give a formulation of the optimized composition and operational conditions of the process so that the final mattress conforms to the specifications. This new composition includes reinforcement fibres in small quantities. It allows improving the mechanical characteristics without affecting the other properties. Finally, we quantified the production costs and compared them to those of the process currently used with coarse fiber (dry-laid production).Keywords: Paper engineering, physical chemistry, porous media, glass fibre, characterization
Forsström, Jennie. "Fundamental Aspects on the Re-use of Wood Based Fibres : Porous Structure of Fibres and Ink Detachment." Doctoral thesis, KTH, Fibre and Polymer Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-84.
Повний текст джерелаIn this work, different aspects on the re-use of wood based fibres have been studied, focusing on ink detachment of flexographic ink from model cellulose surfaces and changes in porous structure of kraft fibres following different treatments. New model systems for evaluation of ink detachment and ink-cellulose interactions were used. Ink detachment was studied using Impinging jet cell equipment, taking into consideration the influence of storage conditions, surface roughness and surface energy of the cellulose substrate. A micro adhesion measurement apparatus (MAMA) was used to directly study ink-cellulose interactions, from which the adhesive properties between ink and cellulose, having various surface energies, could be derived. UV-light, elevated temperatures, longer storage time, decreased surface energy, i.e. making the cellulose surface more hydrophobic, and high surface roughness all negatively affected ink detachment. Attenuated total reflectance - fourier transform infra red (ATR-FTIR) and atomic force microscopy (AFM) was used to evaluate structural and chemical changes of ink and cellulose upon storage at elevated temperature or under UV-light. After storage at elevated temperatures, ATR-FTIR spectra indicated that a hydrolysis or an oxidative reaction took place as a peak at 1710 cm-1 appeared. AFM revealed that storage at elevated temperatures caused the latex particles present in the ink to form a film, most likely due to annealing. Less ink detached from hydrophobic cellulose surfaces. Ink detachment decreased for rougher cellulose substrates due to an increased molecular contact area.
Fibre pore structure and water retaining ability influenced fibre/fibre joint strength and different paper strength properties. Investigations took into account the effect of pulp yield, counter-ion types, pH, salt, hornification and strength enhancing additives. Nuclear magnetic resonance relaxation (NMR), inverse size exclusion chromatography (ISEC) and water retention value (WRV) measured the changes that occur in the fibre wall upon varying the conditions. Each different measuring technique contained unique information such that a combination of the techniques was necessary to give as complete a picture as possible over the changes that occurred in the fibre wall upon varying the conditions for the fibre. A correlation between fibre pore radius and sheet strength properties was found, suggesting that fibres with larger pores allow for a larger molecular contact area between fibres to be formed during drying and consolidation of the paper. Fibre/fibre joint strength, fibre flexibility, and the number of efficient fibre/fibre contacts also controlled sheet strength. The effect of different strength enhancing additives on fibre pore structure and paper strength was investigated. Larger pores in the fibres allowed for additives to penetrate into the fibre wall. Additives with low molecular mass (Mw) penetrated into the fibre wall to a larger extent than additives with a high Mw, causing an embrittlement of the fibre. However, low Mw additives gave higher sheet tensile strength despite a leveling out in strength at high additions, indicating that the fibre wall can only adsorb a limited amount of chemical. Polyallylamine hydrochloride (PAH) and polyelectrolyte complexes (PEC) of PAH and polyacrylic acid (PAA) were added separately to the pulp. PEC significantly improved both tensile strength and Z-strength, whereas PAH alone did not increase the strength properties to the same extent unless the sheets were heated to 150°C for 10 minutes. The results suggested that the effect of PEC was dominated by an improvement in fibre/fibre joint strength, whereas the effect of PAH was significantly affected by an improvement of the intra-fibre bond strength
Forsström, Jennie. "Fundamental aspects on the re-use of wood based fibres : porous structure of fibres and ink detachment /." Stockholm, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-84.
Повний текст джерелаKatsogiannis, Konstantinos A. G. "Single step production of nanoporous electrospun poly(ε-caprolactone) fibres". Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/22929.
Повний текст джерелаCollignon, Brice. "Séchage des bétons réfractaires : expérimentation, modélisation et influence d'un ajout de fibres polymère." Thesis, Vandoeuvre-les-Nancy, INPL, 2009. http://www.theses.fr/2009INPL051N/document.
Повний текст джерелаCastable refractories take a more and more important place in various industries: cement factory, casting, iron and steel making. They consist mainly of aggregates of high-alumina and ultra-low cement. Their permeability is very low and they contain before the first heat-up a residual water content of 4 to 6 % (dry basis). Drying during the first heat-up is a crucial step which sharply influence the refractory in-service performances. On one hand, damaging can occur, and as a consequence will reduce drastically the life time of the plants. On the other hand, particular drying conditions can lead to an explosive spalling of the refractory corresponding to an internal gas pressure steep raise linked to the water saturated vapour pressure raise with temperature. First, a complete thermomechanical characterization between ambient temperature and 500 °C of the unshaped refractory materials has been conducted. Then the mechanisms involved during their drying, on one hand, by an experiment and, on the other hand, by using a simultaneous heat and mass transfer model in porous media have been studied. And last, the impact of adding polymer fibers has been analysed both on the concrete permeability as well as their influence on drying
Loffler, Steven Marc. "Dyeing of cellulose fibres : a case study in structure-transport relationships in heterogeneous porous media." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627033.
Повний текст джерелаShukla, Sushumna. "Membrane distillation with porous metal hollow fibers for the concentration of thermo-sensitive solutions." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20215/document.
Повний текст джерелаThis thesis presents an original approach for the concentration of thermo-sensitive solutions: the Sweep Gas Membrane Distillation (SGMD) process. A new membrane contactor with metallic hollow fibers has been designed and allows the distillation process to be operational at low temperature. Heat is generated in the fibers by the Joule effect, rather than being supplied as latent heat in the liquid bulk. The localized generation of heat results in a reduction of temperature polarization phenomena. The stainless-steel hollow fiber membranes have been synthetized with appropriate structural properties and sufficient mechanical strength. The pore surface of the fibers has been made hydrophobic by the deposition of a thin layer of an elastomer. Moreover, a novel and green method is presented to fabricate alumina and stainless-steel hollow fibers. This method is based on ionic gelation of a biopolymer and completely avoids the use of harmful solvents. By a detailed experimental study of the SGMD the influence of different operational parameters on the process performance has been investigated. The improvements in the flux and the separation efficiency using Joule effect have been successfully demonstrated, even in the case of pervaporation
Salinas-Torres, David. "Tailoring of carbon materials for their use as electrodes in electrochemical capacitors." Doctoral thesis, Universidad de Alicante, 2014. http://hdl.handle.net/10045/45286.
Повний текст джерелаBiasi, Valentin. "Modélisation thermique de la dégradation d’un matériau composite soumis au feu." Thesis, Toulouse, ISAE, 2014. http://www.theses.fr/2014ESAE0034/document.
Повний текст джерелаComposite materials are increasingly used in new generation aircraft structures. Mass and as a consequence fuel savingsencourage aircraft manufacturers to use them optimally. However, these materials can degrade quickly when exposed tosignificant heat fluxes, resulting in a loss of mechanical strength. This problem can be dramatic for passenger safety asmechanical resistance of such innovative structures can not be ensured in case of fire events. Current certification methodsof fire resistance of aeronautical composite materials are mainly based on experiments, that are only representative of thespecific conditions under which they were carried out. The understanding of thermal, chemical and mechanical phenomenaoccurring during the decomposition of these materials, with the support of numerical simulations and experiments, can helpimproving existing methods and optimizing the future aeronautical structures from the design chain. This study deals withthe development and validation of a multi-components and multi-dimensional thermo-chemical model of decomposing compositematerials. It can deal with complex degradations following several decomposition reactions as well as transport ofpyrolysis gases from their formation up to their ejection out of the material. The use of advanced homogenization laws isproposed to account for the chemical transformations on heat and mass transfers occurring in the material. The applicationof the thermo-chemical model to a laser degradation study under known but non-uniform heat flux in a controlled environmentallows to confront the simulation results with experimental measurements and thus validate the multi-componentsapproach. Finally, the numerical analysis of a decomposing composite material submitted to a flame highlights the effectof emitted decomposition gases on the exchanged parietal heat flux
Novotná, Aneta. "Možnosti využití rozptýlené výztuže pro lehké konstrukční betony." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226093.
Повний текст джерелаNam, Gi-moon. "Dynamics of confined biofilaments." Thesis, Strasbourg, 2012. http://www.theses.fr/2012STRAE048/document.
Повний текст джерелаThis PhD is devoted to the mechanics and statistical mechanics of biofilaments and their most widespread model, the Worm-Like Chain (WLC) model, which, as it turns out, needs to be extended. We study the WLC in 2-d in the presence of obstacles closer than their persistence length. We characterize the short time motion by numerical simulations complemented by analytical calculations. Similar concepts serve to describe grafted DNAs swept by the front of a spreading vesicle whose adhesion is promoted by biotin/streptavidin bonds, which constrain the DNAs on narrow paths where they can be imaged. Microtubules (MT), here stabilized by taxol, show features which cannot be rationalized by the WLC and shall be related to their internal structure : i)lateral deflections of a clamped MT correspond to an effective persistence length growing with the MT size ii) MT adopt super-helical shapes. These two points are proven by refined image analysis. We analyze shape transitions correlated along the MT which are compatible with a model based on dimer bi-stability. Finally, a super helical chain model (HWLC) allowing for spontaneous curvature and twist is developed which extends the WLC. When confined to 2-d, the HWLC can adopt a ground state which is circular or wavy with inflection points where twist accumulates, so-called twist-kinks. In the circular case there exist close metastable states, with a small number of twist-kinks, which are hyperflexible
Luminari, Nicola. "Modeling and simulation of flows over and through fibrous porous media." Phd thesis, Toulouse, INPT, 2018. http://oatao.univ-toulouse.fr/20132/1/LUMINARI_Nicola.pdf.
Повний текст джерелаMENESES, J. P. C. "ESTUDO Experimental de Parâmetros de Dosagem e Desempenho de Concreto Asfáltico Poroso Com Adição de Fibras de Bagaço de Cana-de-açúcar." Universidade Federal do Espírito Santo, 2017. http://repositorio.ufes.br/handle/10/9493.
Повний текст джерелаRevestimentos asfálticos porosos, conhecidos como camada porosa de atrito (CPA), são uma técnica bastante difundida internacionalmente, visto suas vantagens sobre pavimentos comuns, principalmente em condições chuvosas, como redução de spray e risco de aquaplanagem, aumento da aderência pneu-pavimento e redução do fenômeno de espelhamento noturno. Em contraponto, um dos problemas da mistura é sua maior susceptibilidade ao escorrimento de ligante, e uma das formas de se minimizar o fenômeno é a utilização de fibras na dosagem. As fibras de bagaço de cana-de-açúcar são uma das opções de fibras, e seu emprego é motivado por questões ambientais, pois as fibras são de origem do resíduo da indústria sucroalcooleira. O Brasil, devido ao seu posicionamento geográfico, apresenta períodos intensamente chuvosos e, dessa forma, o emprego de revestimentos asfálticos porosos se mostra bastante adequado. Todavia, os estudos e aplicações de CPA no país ainda são incipientes, seja por questões de custo e/ou ausência de normas específicas nacionais para dosagem desse tipo de mistura. Deste modo, buscou-se avaliar o comportamento físico e mecânico de CPAs com adição de fibras de celulose (CEL), comumente empregadas para minimizar o escorrimento em CPAs, mas também com fibras de bagaço de cana-de-açúcar (BCA). Devido à ausência de regulamentação nacional, empregou-se para a dosagem a ASTM D7064-13. Além de resistência à abrasão (Los Angeles) e escorrimento de ligante, ensaios mínimos estabelecidos por norma para dosagem de CPA, foram verificados módulo de resiliência (MR), resistência à tração (RT) e permeabilidade, para avaliar o desempenho das misturas. As misturas BCA apresentaram maior valor de escorrimento de ligante, embora o BCA tenha reduzido o escorrimento comparando-se a uma mistura referência (sem fibras). Ainda, menores valores obtidos para relação MR/RT para as misturas BCA, indicaram melhor comportamento de vida de fadiga. Ainda que os resultados de permeabilidade obtidos tenham sido baixos, foi possível concluir que a presença de fibras pode reduzir significativamente o coeficiente de permeabilidade de CPAs. Palavras-chave: asfalto poroso (AP); camada porosa de atrito (CPA); fibras; celulose; bagaço de cana-de-açúcar (BCA); durabilidade; fadiga; drenabilidade.
Cadet, Marine. "Vers la conception d’une biopile enzymatique à glucose/oxygène efficace en milieu biologique." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0260/document.
Повний текст джерелаThe first part of the work presented here focuses on the optimization of an oxygen cathode. First, the use of a new enzyme (BOD from Magnaporthe oryzae) permit to increase the current of reduction of oxygen into water by a factor nine. Then the synthesis of a suitable redox polymer greatly improved the diffusion coefficient of electrons in the hydrogel, resulting in an increase of the current density. Finally we switched from a two-dimensional carbon electrode to a three-dimensional porous gold fiber. After modification of the fiber with the redox hydrogel based on BOD from M. oryzae, we assessed its biocompatibility: in vitro the tests showed the total absence of cytotoxicity and only a very low inflammatory response; in vivo noinfection appeared during the 8 weeks of implantation in mice and the formation of afibrotic capsule around the device reflects its successful integration into the animal tissues.The second part concerns the full biofuel cell, elaborated from the optimized cathode and an adapted GDH-based anode. It could generate up to 240 μW.cm-2 at 5mMglucose in Pipes/CaCl2 buffer. The biofuel cell was then tested in whole human blood. A maximum of 129 μW.cm-2 was obtained in a sample with 8,2 mM glycaemiaunder air. In addition we observed that the delivered power density increased proportionally with the glycaemia of the different blood samples tested, making the biofuel cell both a power source and a glucose biosensor at the same time which had never been shown before
Chaves, Vieira Lins Luanda. "Study and development of electrospun fibers for biotechnology application." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI073.
Повний текст джерелаCurrently, the electrospinning process is also one of the most promising routes for the design and development of polymer fibers. This technique is easy to use, unique, versatile, and low cost, which can be used to create fibers from a variety of starting materials. The structure, chemical and mechanical stability, functionality, and other properties of the fibers can be modified to match end applications. The first goal of this thesis was to develop scaffolds for the field of neural tissue engineering in order to mimic the biological, physical and mechanical properties of the native extracellular matrix. In the first time, the effect of fiber alignment of a biocompatible and fluorinated matrix denoted polyvinylidene fluoride (PVDF) was studied on the behavior of monkey neural stem cells particularly the morphology, cell adhesion and their differentiation in glial or neuronal cells. Secondly, bioabsorbable scaffolds composed of polylactide (PLA) and polyethylene glycol (PEG) polymers were synthesized to investigate the influence of the hydrophilic-hydrophobic balance on the culture of neural stem cells. Finally, an exploratory work was conducted to develop smart textiles based on poly(butylene adipate-co-terephthalate) (PBAT) containing curli as protein, well-known for its ability to chelate metals
Manning, John Peter. "Modèle acoustique d'une couche absorbante composée de fibres Shoddy." Mémoire, Université de Sherbrooke, 2012. http://hdl.handle.net/11143/5515.
Повний текст джерелаBijeljic, Branko. "Flow and mass transfer in fibrous and granular porous media." Thesis, Imperial College London, 2000. http://hdl.handle.net/10044/1/8005.
Повний текст джерелаVallabh, Rahul. "Modeling Tortuosity in Fibrous Porous Media using Computational Fluid Dynamics." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-08062009-153236/.
Повний текст джерелаPalakurthi, Nikhil Kumar. "Direct Numerical Simulation of Liquid Transport Through Fibrous Porous Media." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1406881191.
Повний текст джерелаWilliams, Edward McRae. "A model of the formation of a porous fibrous cake." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06162009-063510/.
Повний текст джерелаVan, Heyningen Martha Catharina. "Investigating the effect of compression on the permeability of fibrous porous media." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86245.
Повний текст джерелаENGLISH ABSTRACT: Fluid flow through porous media plays an important role in a variety of contexts of which filtration is one. Filtration efficiency of fibrous filters depends on the micro-structural characterization of these porous materials and is reflected in the permeability there-of. Compression of fibrous porous media has a significant effect on the permeability. Experimental data indicate that the permeability varies generally with more than an order of magnitude over the narrow porosity range in which the compression takes place. Relative to the amount of experimental studies regarding this phenomenon, there is a scarcity of geometric models in the literature that can account for the effect of compression on the permeability of a fibrous porous medium. Within the context of existing geometric porescale models based on rectangular geometry, a new model is presented and an existing model improved to predict the effect of one-dimensional compression in the streamwise direction. In addition, without compromising on a commitment to mathematical simplicity, empirical data of a non-woven fibrous porous medium was used to highlight the effect of model geometry on its predictive capability. Different mathematical expressions for the relationship between compression and porosity were considered. The permeability is expressed explicitly in terms of the fibre diameter and the compression fraction and implicitly in terms of the porosity. The porosity is incorporated through the relationship between the linear dimensions of the geometric model. The general applicability of the model(s) was validated by making use of data on airflow through a soft fibrous porous material as well as through glass and nylon fibres. The permeability predictions fall within the same order of magnitude as the experimental data. Given the mathematical simplicity of the model(s), the prediction capability is satisfactory. Attention is drawn to assumptions made and model restrictions within the analytical modelling procedure. A general predictive equation is presented for the permeability prediction in which a solid distribution factor is introduced. The proposed models serve as basis for further adaptation and refinement towards prediction capability.
AFRIKAANSE OPSOMMING: Vloei van vloeistowwe deur poreuse media speel ’n belangrike rol in ’n verskeidenheid kontekste waarvan filtrasie een is. Die filtrasie doeltreffendheid van vesel filters hang af van die mikro-strukturele karakterisering van hierdie poreuse materiale en word gereflekteer in die permeabiliteit. Kompressie van veselagtige poreuse media het ’n beduidende effek op die permeabiliteit. Eksperimentele data dui aan dat die verandering in permeabiliteit gewoonlik oor meer as ’n orde grootte strek oor die klein porositeitsinterval waarin die kompressie plaasvind. Relatief tot die aantal eksperimentele studies rakende hierdie verskynsel, is daar ’n tekort aan geometriese modelle in die literatuur wat die effek van kompressie op die permeabiliteit van veselagtige poreuse media in ag kan neem. Binne die konteks van bestaande geometriese kanaal-skaal modelle gebasseer op reghoekige geometrie, is ’n nuwe model voorgestel en ’n bestaande model verbeter om die effek van een-dimensionele kompressie in die stroomsgewyse rigting te voorspel. Sonder om die verbintenis tot wiskundige eenvoud prys te gee, is empiriese data van ’n nie-geweefde veselagtige poreuse medium gebruik om die effek van die geometrie van ’n model op sy voorspellingsvermo¨e uit te lig. Verskillende wiskundige uitdrukkings is oorweeg vir die verband tussen kompressie en porositeit. Die permeabiliteit is eksplisiet uitgedruk in terme van die veseldiameter en die kompressie breukdeel en implisiet in terme van die porositeit. Die porositeit is ge-inkorporeer deur die verhouding tussen die lineêre dimensies van die geometriese model. Die algemene toepaslikheid van die model(le) is gestaaf deur gebruik te maak van data oor lugvloei deur ’n sagte veselagtige poreuse materiaal sowel as deur glas en nylon vesels. Die voorspellings van die permeabiliteit val binne dieselfde groote orde as die eksperimentele data. Gegee die wiskundige eenvoud van die model(le), is die voorspellingsvermoë bevredigend. Aandag is gevestig op aannames wat gemaak is en modelbeperkings binne die analitiese modellerings prosedure. ’n Algemene voorspellingsvergelyking is voorgestel vir die voorspelling van die permeabiliteit waarin ’n vaste stof distribusie faktor geinkorporeer is. Die voorgestelde modelle dien as basis vir verdere aanpassing en verfyning van voorspellingsvermoë.
Badini, G. E. "Investigation of porous glass-like substrates for use in fibre-optic chemical sensors." Thesis, City University London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281842.
Повний текст джерелаNovellani, Marc. "Etude expérimentale et numérique des empilements de fibres : structure et propriétés thermiques." Aix-Marseille 1, 2000. http://www.theses.fr/2000AIX11058.
Повний текст джерелаBarančíková, Miriama. "Vysoce porézní keramické materiály připravené metodou Spark Plasma Sintering." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-442603.
Повний текст джерелаGrena, Benjamin (Benjamin Jean-Baptiste). "Phase separation in thermally-drawn fibers: From porous domains to structured Si-Ge spheres." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111324.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (pages 149-160).
The preform-to-fiber thermal drawing method is a versatile process that allows the fabrication of polymer or glass-based fibers with complex multimaterial internal structures, which grant them functions ranging from optical transmission to chemical detection. However, while a wide range of materials have been successfully drawn in various phases - such as metals, semiconductors, and ferroelectric polymers - the overall structure of the fiber is typically axially-invariant and the incorporation of heterogeneous materials with isotropic microstructures such as porous domains has remained elusive thus far. In this thesis we investigate the use of in-fiber phase separation as a means to control the microstructure of different components within thermally-drawn fibers. In particular we propose a novel method based on controlled phase separation of a polymer solution that we use to embed isotropically porous polymeric domains inside multimaterial fibers. We achieve this by thermal-drawing a hollow polymer preform filled with a liquid polymer solution in its core. We later apply this method to the fabrication and characterization of scaffolds for neural regeneration. In addition, we show that the same principle can also be used to draw a functional lithium-ion fiber battery; a fiber device capable of electrochemical energy storage. Finally, we demonstrate how to produce structured Si-Ge spheres encapsulated within a silica cladding by inducing capillary breakup of a continuous Si-Ge core fiber in a strong axial thermal gradient. The thermal gradient causes a "kinetic phase separation" of the alloy, leading to structured Janus particles.
by Benjamin Grena.
Ph. D.
Klein, Christian. "Etude du procédé de densification par caléfaction de composites C/C, modélisation, optimatisation du contrôle et du bilan énergétique." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0231.
Повний текст джерелаThis work has been carried out in the frame of the study of an industrial process for the manufacturing of carbon/carbon (C/C) composite aircraft brake discs. A porous preform made of carbon fibres is immersed in a liquid precursor and is heated by Radio-Frequency electromagnetic induction. The boiling precursor enters the porous preform and yields a carbon deposit in the hottest zones; this deposit will be the carbon matrix of the composite. A physico-chemical process model is proposed in the aim of ensuring its control and optimisation. The work consisted in developing a numerical solver coupling electromagnetic induction heating with heat, mass and species balances accounting for boiling, diffusion and chemical deposition reactions. The model includes the complete electrical circuit of the heating device: it therefore allows real-time, non-destructive monitoring of the infiltration progress through the evolution of the electrical properties. An original formulation has been designed to simultaneously describe the liquid, the gas and the boiling zone; it has been implemented in a commercial Finite Element software package and validated physically with respect to experimental data, with a good agreement. Finally, the simulation software has been used to propose directions for process improvements, through alterations of the inductive heating device geometry or of the heating power supply program
Serrat, Pierre J. L. "Numerical study of a stokes flow through a fibrous porous medium." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/17926.
Повний текст джерелаTimnak, Azadeh. "GRADIENT POROUS FIBROUS SCAFFOLDS AS A PARADIGM FOR IMMUNOMODULATORY WOUND DRESSINGS." Diss., Temple University Libraries, 2017. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/474843.
Повний текст джерелаPh.D.
Engineering therapeutic approaches to wound healing can be divided into two major categories of fibrous and non-fibrous approaches. There has been significant progress in designing artificial skin products to replace autografting. For patients with non-healing/hard-to-heal wounds, there is an unmet clinical need for inexpensive skin substitutes to be transplanted. In skin regeneration area of research, electrospinning is a very commonly used method of production of grafts for wound healing applications, owing its popularity to the fibrous nature of the resultant product, which mimics the extracellular matrix of the native skin. Despite the high degree of porosity in conventional electrospun scaffolds, the small pore size effectively limits the penetration of cells into the scaffold. Transplantation of such scaffolds with poor cell infiltration abilities may lead to a range of negative consequences, from prolongation of the first/destructive phase of inflammation to rejection of the scaffolds. Several experimental approaches have been developed to generate interfibrillar space in the electrospun scaffolds, including but not limited to modifications of the electrospinning set-up and inclusion of sacrificial components. It has been reported that scaffolds with larger pore diameters in the range of ~ 40-100 μm can modulate, moderate and reduce acute inflammatory responses of the body, by influencing macrophages biological behavior, and direct the course of the wound healing process to the tissue remodeling phase. Macrophages are the major cell component of innate immune system and play critical roles in clearance of pathogens, resolution of inflammation and wound healing following an injury. Macrophages are characterized by their diversity and plasticity. In response to environmental stimuli, they acquire different functional phenotypes of pro-inflammatory (M1) or anti-inflammatory (M2). In this thesis, we developed a novel unique gradient porous structure from a plant-based “green” soy protein isolate (SPI) with improved pore size for macrophages to infiltrate. We further showed the ability of the scaffold to modulate phenotype switch in macrophages in vitro and in vivo. The proposed scaffold, moreover, appeared to support transition of the inflammation process from the destructive to the constructive phase in vivo. Based on the promising results of this thesis, we propose our newly developed scaffold has the ability to be used as a new therapeutic modality for treatment of non-healing chronic wounds.
Temple University--Theses
Powell, Sean K. "A quantitative study of diffusion in quasi-periodic fibre networks and complex porous media." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/92506/12/92506%28thesis%29.pdf.
Повний текст джерелаDuan, Gaigai [Verfasser], and Andreas [Akademischer Betreuer] Greiner. "3D porous sponges from electrospun polymer fibers and their applications / Gaigai Duan ; Betreuer: Andreas Greiner." Bayreuth : Universität Bayreuth, 2017. http://d-nb.info/1139358235/34.
Повний текст джерелаBezik, Cody. "Poly(High Internal Phase Emulsion) Foams and Fibers: Structure-Property Relationships." Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1436458970.
Повний текст джерелаYu, Li. "Multi-Material Fiber Fabrication and Applications in Distributed Sensing." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/99380.
Повний текст джерелаPHD
Langeard, Olivier. "Numerical study of a Navier-Stokes flow through a fibrous porous medium." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/15944.
Повний текст джерелаAshari, Alireza. "Dual-Scale Modeling of Two-Phase Fluid Transport in Fibrous Porous Media." VCU Scholars Compass, 2010. http://scholarscompass.vcu.edu/etd/2326.
Повний текст джерелаAmico, Sandro Campos. "Permeability and capillary pressure in the infiltration of fibrous porous media in resin transfer moulding." Thesis, University of Surrey, 2000. http://epubs.surrey.ac.uk/1011/.
Повний текст джерелаWooddell, Michael Gary. "Increased Functionality Porous Optical Fiber Structures." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/35324.
Повний текст джерелаMaster of Science
Nam, Gi-Moon. "Dynamics of confined biofilaments." Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00976029.
Повний текст джерелаBauer, Alexander Günter. "Direct methanol fuel cell with extended reaction zone anode : PtRu and PtRuMo supported on fibrous carbon." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/913.
Повний текст джерелаWang, Xiaokun. "Fabrication of electrospun fibrous meshes and 3D porous titanium scaffolds for tissue engineering." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/51724.
Повний текст джерелаGondy, Dominique. "Développement de la texture poreuse et variation dimensionnelle des fibres de carbone au cours de leur activation." Mulhouse, 1996. http://www.theses.fr/1996MULH0447.
Повний текст джерелаRahli, Ouamar. "Etude des milieux poreux constitués de fibres rigides : empilements, écoulements et transferts de chaleur." Aix-Marseille 1, 1997. http://www.theses.fr/1997AIX11064.
Повний текст джерелаSantos, Eduardo Pena dos. "Fibres et céramiques mésoporeuses de zircone préparées avec templates de cristaux liquides gonflés." Montpellier 2, 2005. http://www.theses.fr/2005MON20010.
Повний текст джерелаHicks, David Cyprian. "Aligned Continuous Cylindrical Pores Derived from Electrospun Polymer Fibers in Titanium Diboride." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/99423.
Повний текст джерелаMS
Vennat, Elsa. "Étude expérimentale et numérique de l'infiltration de la dentine déminéralisée en surface par des résines composites." Phd thesis, Ecole Centrale Paris, 2009. http://tel.archives-ouvertes.fr/tel-00441341.
Повний текст джерелаCARDOSO, Markos Paulo. "Estudo de fibras porosas com inclusões metálicas para guiamento em THz." Universidade Federal do Pará, 2017. http://repositorio.ufpa.br/jspui/handle/2011/9465.
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CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico
O guiamento de ondas THz tem se mostrado de grande importância na melhoria da performance das configurações de espectroscopia, imagem e sensoriamento. Um dos maiores desafios na concepção dessas estruturas é a mitigação das altas perdas apresentadas pelo meio dielétrico na faixa espectral THz (0.1 até 10 THz). Este trabalho realiza a modelagem numérica de fibras porosas com inclusões de ouro para guiamento em THz. O design dessas interfaces metal-dielétricas é capaz de confinar as ondas THz nas regiões de ar da fibra porosa através da excitação de plasmons de superfície, modos que resultam da interação ressonante entre a radiação eletromagnética incidente e a oscilação coletiva de elétrons livres na superfície metálica. É evidenciado que a partir de um projeto adequado da camada de ouro, as perdas efetivas podem ser reduzidas e uma dispersão cromática zero pode ser alcançada como resultado do acoplamento entre os modos da fibra e os plasmons de superfície.
The guidance of THz waves has been found of great importance to improve the performance of spectroscopy, imaging and sensing setups. One of the major challenges in designing such structures is the mitigation of the high losses presented by dielectric media in the THz spectral range (0.1 up to 10 THz). This work performs an analytical and numerical modeling of porous fibers with gold inclusions for THz guidance. The design of these metal-dieletric interface is capable to confine THz waves in the air region of the porous fiber, through the excitation of surface plasmons, modes that result from the resonant interaction between the incident electromagnetic radiation and the collective oscillation of free electrons on the metal surface. It is shown that from a suitable design of the gold layer, the effective losses can be reduced and a zero chromatic dispersion can be achieved as result of the coupling between the fiber modes and the surfasse plasmons.
Costa, Ana Sara Silva Rodrigues da. "Suportes porosos com topografia de fibras alinhadas para a regeneração neuronal." Master's thesis, Faculdade de Ciências e Tecnologia, 2012. http://hdl.handle.net/10362/8484.
Повний текст джерелаQueiroz, Alex Sander Barros. "Estudo do desempenho de componentes baseados em fibras ópticas especiais: fibras de cristal fotônico e de metamateriais e suas aplicações em comunicações." reponame:Repositório Institucional da UFC, 2015. http://www.repositorio.ufc.br/handle/riufc/14728.
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In this paper we present a numerical study of the Sagnac interferometer based on photonic crystals and optical coupler metamaterial. In the simulation of the interferometer effects of light propagation were analyzed, considering the dispersion of the group velocity (GVD) and third order (TOD), intrapulse Raman scattering, self-slope (self-steepening) and self-modulation phase in the generalized non-linear Schrödinger equation. The first time the study was conducted for four power division ratio of factors incident in one of the device ports and three dimensions for the device ring length. To characterize the system performance, were analyzed the transmission curves, extinction ratio, crosstalk and compression factor of the transmitted pulse. In the second moment, the performance of the non-linear switching was observed for obtaining gate under Pulse Amplitude Modulation (PAM). Exciting the two device input ports with logical levels "0" and "1", observing their behavior in one of the device outputs. Initially, the modulation is varied adjustment parameter (| ε |), obtaining only the logical OR gate. And in a second application, the fixed modulation parameter remained and was varied the phase of the input ports 0 to 2π rad, lying type logic gate OR, AND and XOR. The characteristics of a metamaterial guide that has the real part of electrical permittivity and magnetic permeability negatives were also studied. This metamaterial guide is coupled to a conventional guide, observing the transmission characteristics and critical power of this type of coupler and compared with a conventional coupler. For this analysis we used a decreasing automodulation profile linearly with five minimum, observing a hysteresis behavior.
Neste trabalho foi realizado um estudo numérico do interferômetro de Sagnac baseado em cristais fotônicos e de acoplador óptico de metamaterial. Na simulação do interferômetro foram analisados os efeitos da propagação da luz, considerando-se a dispersão de velocidade de grupo (GVD) e de terceira ordem (TOD), espalhamento Raman intrapulso, auto-inclinação (Self-steepening) e auto-modulação de fase na equação não linear de Schrödinger generalizada. No primeiro momento foi realizado o estudo para quatro fatores de razão de divisão da potência incidente em uma das portas do dispositivo e três dimensões para o comprimento do anel do dispositivo. Para caracterizar o desempenho do sistema, foram analisadas as curvas de transmissão, taxa de extinção, crosstalk e fator de compressão do pulso transmitido. No segundo momento, foi verificada a performance do chaveamento não-linear para obtenção de porta lógica sob Modulação por Amplitude de Pulsos (PAM). Excitando-se as duas portas de entrada do dispositivo com níveis lógicos "0" e "1", observando o seu comportamento em uma das saídas do dispositivo. Inicialmente, variou-se o parâmetro de ajuste da modulação (|ε|), obtendo-se apenas a porta lógica OR. E, em uma segunda aplicação, manteve-se o parâmetro da modulação fixa e variou-se a fase de uma das portas de entrada, de 0 a 2π rad, encontrando-se portas lógicas do tipo OR, AND e XOR. Também foram estudadas as características de um guia metamaterial que possui a parte real da permissividade elétrica e da permeabilidade magnética negativas. Esse guia metamaterial é acoplado com um guia convencional, observando-se as características de transmissão e potência crítica desse tipo de acoplador e, comparando-se com um acoplador convencional. Para essa análise foi utilizado um perfil de automodulação decrescente linearmente com cinco valores mínimo, observando-se um comportamento de histerese.
Cid, Jacques. "Influence des caractéristiques structurales sur le transfert de l'humidité en milieux poreux fibreux sous contraintes mécaniques." Toulouse, INPT, 1990. http://www.theses.fr/1990INPT090H.
Повний текст джерелаDoutres, Olivier Dauchez Nicolas Genevaux Jean-Michel. "Caractérisation mécanique de matériaux fibreux en vibro-acoustique." [S.l.] : [s.n.], 2007. http://cyberdoc.univ-lemans.fr/theses/2007/2007LEMA1015.pdf.
Повний текст джерелаPeng, Ling [Verfasser], and Seema [Akademischer Betreuer] Agarwal. "Bicomponent Porous Fibrous Membranes with Special Fiber Morphologies and Properties / Ling Peng ; Betreuer: Seema Agarwal." Bayreuth : Universität Bayreuth, 2018. http://d-nb.info/1159632944/34.
Повний текст джерела