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Gondre, Damien. "Numerical modeling and analysis of heat and mass transfers in an adsorption heat storage tank : Influences of material properties, operating conditions and system design on storage performances." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI022/document.
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Le développement de solutions de stockage de l'énergie est un défi majeur pour permettre la transition énergétique d'un mix énergétique fortement carboné vers une part plus importante des énergies renouvelables. La nécessité de stocker de l'énergie vient de la dissociation, spatiale et temporelle, entre la source et la demande d'énergie. Stocker de l'énergie répond à deux besoins principaux : disposer d'énergie à l'endroit et au moment où on en a besoin. La consommation de chaleur à basse température (pour le chauffage des logements et des bureaux) représente une part importante de la consommation totale d'énergie (environ 35 % en France en 2010). Le développement de solutions de stockage de chaleur est donc d'une grande importance, d'autant plus avec la montée en puissance des énergies renouvelables. Parmi les technologies de stockage envisageables, le stockage par adsorption semble être le meilleur compromis en termes de densité de stockage et de maintient des performances sur plusieurs cycles de charge-décharge. Cette thèse se focalise donc sur le stockage de chaleur par adsorption, et traite de l'amélioration des performances du stockage et de l'intégration du système au bâtiment. L'approche développée pour répondre à ces questions est numérique. L'influence des propriétés thermophysiques de l'adsorbant et du fluide sur la densité de puissance d'une part, mais aussi sur la densité de stockage et l'autonomie du système, est étudiée. L'analyse des résultats permet de sélectionner les propriétés des matériaux les plus influentes et de mieux comprendre les transferts de chaleur et de masse au sein du réacteur. L'influence des conditions opératoires est aussi mise en avant. Enfin, il est montré que la capacité de stockage est linéairement dépendante du volume de matériau, tandis que la puissance dépend de la surface de section et que l'autonomie dépend de la longueur du lit d'adsorbant. Par ailleurs, le rapport entre l'énergie absorbée (charge) et relâchée (décharge) est d'environ 70 %. Mais pendant la phase de charge, environ 60 % de la chaleur entrant dans le réacteur n'est pas absorbée et est directement relâchée à la sortie. La conversion globale entre l'énergie récupérable et l'énergie fournie n'est donc que de 25 %. Cela montre qu'un système de stockage de chaleur par adsorption ne peut pas être pensé comme un système autonome mais doit être intégré aux autres systèmes de chauffage du bâtiment et aux lois de commande qui les régissent. Utiliser la ressource solaire pour le préchauffage du réacteur est une idée intéressante car elle améliore l’efficacité de la charge et permet une réutilisation de la part récupérée en sortie pour le chauffage direct du bâtiment. La part stockée sous forme sensible peut être récupérée plusieurs heures plus tard. Le système est ainsi transformé en un stockage combiné sensible/adsorption, avec une solution pour du stockage à long terme et pour du stockage à court termeThe development of energy storage solutions is a key challenge to enable the energy transition from fossil resources to renewable energies. The need to store energy actually comes from a dissociation between energy sources and energy demand. Storing energy meets two principal expectations: have energy available where and when it is required. Low temperature heat, for dwellings and offices heating, represents a high share of overall energy consumption (i.e. about 35 %). The development of heat storage solutions is then of great importance for energy management, especially in the context of the growing part of renewable energies. Adsorption heat storage appears to be the best trade off among available storage technologies in terms of heat storage density and performances over several cycles. Then, this PhD thesis focuses on adsorption heat storage and addresses the enhancement of storage performances and system integration. The approach developed to address these issues is numerical. Then, a model of an adsorption heat storage tank is developed, and validated using experimental data. The influence of material thermophysical properties on output power but also on storage density and system autonomy is investigated. This analysis enables a selection of particularly influencing material properties and a better understanding of heat and mass transfers. The influence of operating conditions is also underlined. It shows the importance of inlet humidity on both storage capacity and outlet power and the great influence of discharge flowrate on outlet power. Finally, it is shown heat storage capacity depends on the storage tank volume, while outlet power depends on cross section area and system autonomy on bed length. Besides, the conversion efficiency from absorbed energy (charge) to released energy (discharge) is 70 %. But during the charging process, about 60 % of incoming heat is not absorbed by the material and directly released. The overall conversion efficiency from energy provided to energy released is as low as 25 %. This demonstrates that an adsorption heat storage system cannot be thought of as a self-standing component but must be integrated into the building systems and control strategy. A clever use of heat losses for heating applications (in winter) or inlet fluid preheating (in summer) enhances global performances. Using available solar heat for system preheating is an interesting option since a part is instantly retrieved at the outlet of the storage tank and can be used for direct heating. Another part is stored as sensible heat and can be retrieved a few hours later. At least, it has the advantage of turning the adsorption storage tank into a combined sensible-adsorption storage tank that offers short-term and long-term storage solutions. Then, it may differ avoidable discharges of the sorption potential and increase the overall autonomy (or coverage fraction), in addition to optimizing chances of partial system recharge
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Hinsley, Steven W. "Maintaining systems-of-systems fit-for-purpose : a technique exploiting material, energy and information source, sink and bearer analysis." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/25465.
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Across many domains, systems suppliers are challenged by the complexity of their systems and the speed at which their systems must be changed in order to meet the needs of customers or the societies which the systems support. Stakeholder needs are ever more complex: appearing, disappearing, changing and interacting faster than solutions able to address them can be instantiated. Similarly, the systems themselves continually change as a result of both external and internal influences, such as damage, changing environment, upgrades, reconfiguration, replacement, etc. In the event of situations unforeseen at design time, personnel (for example maintainers or operators) close to the point of employment may have to modify systems in response to the evolving situation, and to do this in a timely manner so that the system and/or System-of-Systems (SoS: a set of systems that have to interoperate) can achieve their aims. This research was motivated by the problem of designing-in re-configurability to the constituent systems of a SoS to enable the SoS and its systems to effectively and efficiently counter the effects of unforeseen events that adversely affect fitness-for purpose whilst operational. This research shows that a SoS does not achieve or maintain fitness-for-purpose because it cannot implement the correct, timely and complete transfer of Material, Energy and Information (MEI) between its constituents and with its external environment that is necessary to achieve a desired outcome; i.e. the purpose.
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Letant, Sonia. "Transfert d'excitation dans les nanocomposites à base de silicium poreux." Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10117.
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Ce travail a ete consacre a l'etude du transfert d'excitation dans les nanocomposites a base de silicium poreux. Le but etait d'etudier le couplage des porteurs photogeneres dans les nanocristaux de silicium avec leur environnement, liquide, solide ou gazeux. Nous presentons ici l'investigation par des methodes de luminescence continue et resolue dans le temps, de trois structures composites : * le silicium poreux dans sa solution acide de formation : un processus de photodissolution des couches poreuses sous lumiere est mis en evidence et caracterise ; dans ce cas, les porteurs fuient physiquement les cristallites pour participer a la reaction photochimique permettant le passage des atomes de silicium dans la solution. * le silicium poreux impregne de colorants laser : il est demontre que les couches poreuses peuvent etre utilisees comme matrice d'accueil passive (excitation directe des molecules) ou active (transfert d'excitation de la matrice vers les molecules via un couplage dipolaire). * le silicium poreux couvert de liaisons si-h : une conversion de l'energie optique en energie vibrationnelle via un couplage dipolaire entre les porteurs et les vibrations de surface a lieu. Le role important de la surface specifique est alors mis en evidence malgre l'origine quantique de l'emission. Il ressort de cette etude que le silicium poreux, malgre sa faible efficacite quantique, est une bonne matrice d'accueil, grace a sa porosite ouverte et a sa grande surface specifique, et qu'il possede les proprietes d'un donneur d'excitation.
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Johansson, Carl, Amanda Engström, Emil Lundgren, Emma Klåvus, Felix Ekholm, Johan Magnusson, and Tinde Höjer. "Heat transfer in pressed steel powder - Part 1: Temperaturemeasurements in capsules." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-388887.
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Watremez, Michel. "Caractérisations tribologique et thermomécanique de revêtements céramiques élaborés par projection thermique plasma : Application aux disques de freinage ferroviaire a haute énergie." Valenciennes, 1995. https://ged.uphf.fr/nuxeo/site/esupversions/f255ae98-2dc8-4b8c-a98b-4443166ff1b3.
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L'augmentation continue des énergies dissipées durant les freinages notamment des trains à grande vitesse est telle qu'une simple extrapolation des systèmes existants sera insuffisante pour les matériels futurs ; les matériaux de friction des freins à disques actuellement utilisés seraient soumis à des conditions de frottement et a des sollicitations thermomécaniques trop sévères ; il s'avère donc nécessaire de reconsidérer fondamentalement l'ensemble disque-garniture. Les recherches présentées concernent la mise en œuvre de revêtements céramiques et cermets par projection plasma sur des disques afin d'adapter les propriétés de surface aux conditions de frottement tout en limitant la propagation de chaleur vers l'essieu. Différents matériaux de friction ont été testés en configuration de freinage de maintien. Les caractéristiques tribologiques de disques revêtus de cermet nicr-cr#3 c#2 testes avec des garnitures frittées de titanate d'aluminium se sont avérées particulièrement intéressantes ; stabilité du coefficient de frottement, bonne tenue à l'usure et insensibilité a l'humidité. Par contre, l'utilisation de revêtements barrière thermique a la surface du disque accroit la température de la garniture et induit une usure plus conséquente. Il a donc été proposé d'éloigner la barrière thermique de la surface de frottement. Cette stratégie a nécessité la conception de disques multi matériaux composés d'un disque support en alliage d'aluminium avec de part et d'autre, une barrière thermique et un flasque d'acier revêtu de cermet nicr-cr#3 c#2. Cette conception conduit à un allègement notable du disque et permet de limiter efficacement le transfert de chaleur vers l'essieu sans pour autant pénaliser l'usure de la garniture.
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Heinrichs, Jannica. "On Transfer of Work Material to Tools." Doctoral thesis, Uppsala universitet, Tillämpad materialvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-165828.
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Bulk forming and cutting are widely used to shape metals in industrial production. Bulk forming is characterized by large strains, extensive plastic deformation and large surface expansions. Cutting is characterized by high speeds, high pressures and high temperatures. The prevailing conditions during these processes lead to transfer of work material to tools. In bulk forming this is a significant problem. The transferred work material is hardened and becomes harder than the work material, causing galling. This leads to high friction and high forming forces, bad surface finish of the formed products and significant difficulties to produce complicated geometries. In cutting, transfer of work material can be desired for protection of the tool surface. However, the transfer film has to be of the correct type to provide a stable and predictive behaviour during operation. In this thesis the influence from tool material and surface treatment on work material transfer has been studied for both applications, with the use of simplified laboratory test methods followed by extensive surface studies. Both the tendency to, appearance of and chemical composition of work material transfer is evaluated. The results are compared with real industrial examples, to ensure that the correct mechanisms are mimicked. In forming, the problems arise when poor lubrication prevails, due to high forming forces or large surface expansions. The transfer of work material can then be avoided with the use of a galling resistant coating, offering low adhesion. However, the coating has to be as smooth as possible, to avoid activation of the work material and subsequent transfer. In cutting, the desired transfer film can be obtained by choosing the correct cutting parameters. The geometry and material of the fabricated component is often predetermined, setting the general cutting conditions, but the cutting speed influences the formation of the transfer film. Too low speed or too high speed leads to an unstable cutting process and poor surface finish of the piece. The speed intervals for each mechanism are partly determined by the tool material and thus by the tool coating.
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Challansonnex, Arnaud. "Transferts couplés chaleur/masse dans les matériaux de construction biosourcés : investigation expérimentale et théorique du non-équilibre local." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC022/document.
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L’intérêt croissant pour les matériaux biosourcés dans le domaine de la construction se heurte à des difficultés quant à la simulation de leur comportement hygrothermique. En particulier, les matériaux isolants tels que les panneaux de fibres concentrent toutes les difficultés car ils sont peu conducteurs thermiquement, très hygroscopiques et très diffusifs à la vapeur d’eau. Conséquemment, en régime transitoire le couplage chaleur masse est exacerbé et les phases de l’eau ne sont pas à l’équilibre localement.Afin de mettre en évidence ce second phénomène, un nouveau dispositif expérimental a été développé. Il permet de soumettre un échantillon de quelques centimètres d’épaisseur à une perturbation de l’humidité relative sur sa face avant puis de mesurer simultanément l’évolution de l’humidité relative sur sa face arrière et de sa masse. En situation de non-équilibre, il existe un déphasage entre ces deux grandeurs que la formulation de transferts couplés classique n’arrive pas à prédire. Afin d’obtenir une prédiction correcte, une nouvelle formulation a été utilisée. Celle-ci se base sur l’emploi de fonctions mémoires caractérisant la diffusion microscopique. De manière à démontrer la capacité prédictive de la nouvelle formulation, ces fonctions ont été déterminées avec des essais gravimétriques réalisés sur de très petits échantillons à l’aide d’une balance à suspension magnétique. En parallèle, une analyse rigoureuse du couplage chaleur masse dans ces matériaux a permis de souligner l’impact sur leur caractérisation de différents paramètres macroscopiques.L’utilisation de la nouvelle formulation alimentée par les fonctions mémoires et les différents paramètres macroscopiques permet une excellente prédiction de l’humidité relative et de la masse. Cette nouvelle formulation validée expérimentalement est désormais utilisable dans des logiciels de simulation énergétique du bâtimentThe growing interest in biosourced materials in the construction sector is confronted with difficulties in simulating their hygrothermal behavior. Insulating materials such as fiberboard concentrate all the difficulties because they are not very thermally conductive, very hygroscopic and very diffusive to water vapor. Consequently, in transient state, heat and mass coupling is exacerbated, and the phases of water are not in equilibrium locally.In order to highlight this second phenomenon, a new experimental device has been developed. It allows to subject a sample a few centimeters thick to a disturbance of relative humidity on its front face and then to simultaneously measure the evolution of relative humidity on its back face and its mass. In a situation of non-equilibrium, there is a phase shift between these two quantities that the classic coupled transfer formulation cannot predict. In order to obtain a correct prediction, a new formulation was used. It is based on the use of memory functions characterizing microscopic diffusion. In order to demonstrate the predictive capacity of the new formulation, these functions have been determined with gravimetric tests performed on very small samples using a magnetic suspension balance. In parallel, a rigorous analysis of the heat and mass coupling in these materials made it possible to highlight the impact of different macroscopic parameters on their characterization.The use of the new formulation fed by the identified memory functions and the various macroscopic parameters allows an excellent prediction of relative humidity and mass. This new formulation, experimentally validated, can now be used in energy simulation of the building
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Zhu, Yongbao. "Charge transfer in conjugated organometallic materials." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0018/NQ56656.pdf.
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Pathak, Sayali V. "Enhanced Heat Transfer in Composite Materials." Ohio University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1368105955.
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Cross, Robert. "Processing of vertically aligned carbon nanotubes for heat transfer applications." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/31828.
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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Graham, Samuel; Committee Member: Das, Suman; Committee Member: Joshi, Yogendra. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Darolles, Danielle. "Couplages transferts de chaleur et de masse a la surface de materiaux poreux utilises en genie civil lors de sechages en ecoulements turbulents." Toulouse 3, 1987. http://www.theses.fr/1987TOU30080.
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Equations du transfert de chaleur dans le milieu poreux, et definition du coefficient d'echange de masse, avec sa relation au coefficient d'echange de chaleur. Dispositif experimental de sechage et caracteristiques mesurees de l'ecoulement. Experiences realisees de sechage et coefficients calcules d'echange de masse a la surface des echantillons, avec comparaison aux resultats obtenus par un modele de simulation monodimensionnel
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Zhao, Xiaomin. "Formaldehyde mass-transfer properties study." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/51597.
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Formaldehyde, an important feedstock in industrial processes and manufacture, is widely present in numerous consumer products. Emitted by many types of consumer products and indoor materials, indoor air can contain high concentrations of formaldehyde. Exposure to formaldehyde is hazardous to human health. Thus knowledge of formaldehyde mass-transfer properties is critical to efforts to reduce formaldehyde emissions and establish related standards and regulations.
The primary objectives of this project include: 1) documenting and validating procedures and methods for analyzing and measuring formaldehyde mass-transfer characteristics; 2) evaluating and comparing formaldehyde mass-transfer properties in different materials using micro-balance sorption/desorption tests; 3) investigating observed formaldehyde mass-transfer irreversibility and the recently developed formaldehyde polymerization theory.
The procedures and methods for analyzing and measuring formaldehyde mass-transfer characteristics were developed in an effort to minimize experimental variability and were strictly followed during the research. The formaldehyde mass-transfer properties of five polymer materials (polycarbonate, polystyrene, poly(methyl methacrylate), polyethylene and polypropylene) were measured through sorption/desorption testing. Results indicated that formaldehyde solubility was highest in polyethylene while the rate of diffusion was the highest in polypropylene. Results also showed that the diffusion process in the selected polymer materials was irreversible in all cases. Furthermore, additional testing showed no detectable polyformaldehyde formation on polymer surfaces after exposure to formaldehyde. The causes of observed mass-transfer irreversibility need further study.Master of Science
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Mnasri, Faiza. "Étude du transfert de chaleur et de masse dans les milieux complexes : application aux milieux fibreux et à l’isolation des bâtiments." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0169/document.
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Le contexte énergétique international impose de nouvelles orientations au secteur du bâtiment neuf ou en rénovation. Toute nouvelle solution doit être techniquement efficace et respectueuse pour l’environnement. Il s'agit dans ce travail de thèse de réaliser une étude numérique et expérimentale de matériaux de construction biosourcés liés au contexte transfrontalier Lorrain (France-Belgique- Luxembourg). En effet, ce travail intègre une partie du projet européen « Ecotransfaire » mené pour le développement d'une filière durable propre aux éco-matériaux. La sélection des matériaux selon une liste de critères à la fois scientifiques, géographiques et environnementaux a permis de répondre à notre problématique en s'orientant vers l'intégration des matériaux biosourcés pour leurs aspects favorables à l'environnement et à l’efficacité énergétique du bâtiment. Intégrés au bâtiment, ces matériaux sont sujets à plusieurs phénomènes de transfert de chaleur et de masse. Dans un premier temps et pour mieux appréhender ces phénomènes, un modèle de transfert couplé de chaleur, d'air, d'humidité (HAM transfers) est utilisé pour simuler le comportement hygrothermique d’un matériau en bois massif à structure supposée homogène. Ce modèle, mis en œuvre et résolu par la méthode des éléments finis, a été validé par des résultats analytiques retenus dans la littérature. L'étude de sensibilité du modèle au couplage, aux dimensions dans l'espace, aux conditions aux limites et aux variabilités des paramètres d'entrée est également présentée. Une des difficultés de l’utilisation de ce modèle réside dans la prise en considération de l'aspect fortement hétérogène de certains matériaux. Ainsi, dans ce travail, nous proposons une approche de caractérisation d'un composite lignocellulosique hétérogène de structure poreuse. En effet ce matériau est composé de deux constituants bien connus dans le domaine de l’industrie de construction: Le bois et le ciment. Le bois est incorporé sous forme de granulats avec des formes et des tailles irrégulières et le ciment est utilisé comme un liant. Le travail réalisé permet de remonter aux propriétés intrinsèques équivalentes de ce matériau (conductivité thermique et perméabilité à la vapeur) à l’aide des techniques de micro-tomographie. La méthodologie suivie consiste à la détermination de la structure d'échantillon par une prise d'images à l'échelle microscopique. Une fois la structure de l’échantillon générée, une reconstruction de la représentation bidimensionnelle précède la génération de la structure tridimensionnelle à l'aide d’un outil numérique qui permet de déterminer les propriétés équivalentes des domaines reconstruits en 3D. La perméabilité et la conductivité thermique équivalentes sont les deux propriétés évaluées dans cette configuration. Ces deux propriétés dépendent fortement de la porosité et de la distribution des pores dans la phase continue (la phase solide). De plus la composition de ce matériau et les fractions volumiques de chacun de ses constituants influent sur la formation de sa microstructure et par conséquent sur ses propriétés de transferts thermiques et hydriques. L'ensemble des connaissances développées dans ce travail permet une piste sérieuse pour l'élaboration d'un éco-matériau à propriétés contrôlées pour des usages spécifiques dans la construction et la rénovationInternational energy context requires a new orientation to the building sector as in construction or in renovation. Any new solution must be technically efficient and environmentally acceptable. In this thesis, the object is to achieve a numerical and experimental analysis of a building biobased materials. Some of these materials are included from the study of a transborder project to the Lorraine region (France, Belgium and Luxembourg). Indeed an Ecotransfaire project was included in this work. This project has been oriented to the development of a sustainable eco materials chain. A process of analysis has been established in order to select the materials candidates on the basis of scientific, geographical and environmental criteria. The answers are moving towards the integration of bio-based materials. These materials are subject of several heat and mass transfers phenomena. So understanding these mechanisms within a building material has been achieved firstly. This resulted on a coupled model of heat transfer, air, moisture experienced by the HAM model. This model is applied to a wooden building material whose its structure is assumed homogeneous. Then, this model was implemented and solved by the finite element method. Its numerical solution is validated by analytical results available in the literature. The study of sensitivity of the model coupling, dimensions in space, the boundary conditions and the variability of input parameters is also presented. One of the difficulties of using this model is the case of heterogeneous materials. Thus, in this work, we propose an approach of characterization of a heterogeneous lignocellulosic composite material with a porous structure. In fact, this material is composed of two components: Wood and cement. The wood is presented by a shapes aggregates with irregulars sizes and the cement is considered as the binder in the composition. The object was to predict its equivalent intrinsic properties (thermal conductivity and vapor permeability) by using the micro-tomography techniques.The methodology consists to determine the structure of the sample by taking images at the microscopic scale. Once the structure of the sample is generated, we will conduct from a reconstruction of the two-dimensional representation to a three dimensional structure by using a numerical tool which determines the equivalent properties of the 3D reconstructed domain. The permeability as well as the equivalent thermal conductivity are the two properties evaluated in this configuration. These two properties are strongly depend to the porosity and to pore distribution in the continuous phase (the solid one). Moreover the composition of the material and the volume fractions of each components influence the formation of microstructure and consequently the thermal and hydric transfers
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Jakub, Saletra Wojciech. "Transfer of chirality from amphiphiles into materials." Doctoral thesis, Universitat Autònoma de Barcelona, 2013. http://hdl.handle.net/10803/125861.
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En esta tesis ha estudiado la influencia de la geometría de las moléculas en las monocapas de autoensamblaje (SAM) de ácidos quirales, se ha presentado la síntesis de la familia de anfifílicos quirales. Cada compuesto se ha medido con STM en la interfaz grafito-1-phenyloctanano como un único enantiómero y como una mezcla racémica para comprobar la transferencia de quiralidad de molécula a SAM a dos dimensiones. Se ha encontrado que las moléculas con geometría curvada - 1,3Ph y 2,7Naph, forman dominios muy regulares en el caso de enantiómero puro y conglomerado en el caso de la mezcla racémica. Los otros compuestos forman diversos polimorfos (hasta cuatro en el caso de 1,5Naph) o cristales 2D irregulares (2,6Naph), y cuando se ha estudiado la mezcla racémica, se han encontrado las SAM desordenadas o un pseudoracemato para 4,4'Biph.
Las mezclas de los derivados de naftaleno se han estudiado en la interfaz grafito-1-phenyloctano para comprobar si los compuestos son capaces de formar monocapas mixtas, por otra parte las mismas mezclas se han medido con calorimetría de barrido diferencial (DSC) y difracción de rayos X (DRX) para comparar el comportamiento en los sistemas de dos y tres dimensiones. Se ha descubierto que los ácidos forman monocapas mixtas estables, y en un caso se ha observado un comportamiento de solución sólida.
El reconocimiento quiral entre los ácidos anfifílicos se ha comprobado con un amina quiral modelo trans-1,2-diaminociclohexano (DACH) - para descubrir que, en caso del ácido 1,3Ph y 2,7Naph, hay un reconocimiento quiral y la formación diastereoselectiva de un complejo en la interfaz de grafito-1-phenyloctane. En el caso del ácido 2,7Naph and DACH también se ha observado la formación de multicapas. Se ha utilizado el modelado molecular para obtener mejor idea de las fuerzas y el ensamblaje de las moléculas. El ácido 1,3Ph fue elegido para estudiar su capacidad de reconocimento con diversas aminas quirales y aquirales incluyendo compuestos utilizados como medicamentos: Metoprolol, Antenolol y Verpamil. Se ha encontrado, en el caso de Metoprolol que hay una complejación preferencial de uno de los enantiómeros en la interfaz grafito-1-phenyloctano.
Se han usado mezclas de ácidos para comprobar su capacidad para actuar como un agente de resolución en dos sistemas dimensionales, pero no se ha encontrado una evidencia clara de mejoras con respecto a los enatiomeros puros, debido a la adsorción competitiva.
Además se ha llevado a cabo la serie de experimentos de mezclas en masa de ácido 1,3Ph y DACH para comprobar si había un reconocimiento quiral en sistemas tres dimensionales. Las muestras se han comprobado con DSC, XRD y en microscopio óptico polarizado (POM) en un rango de temperaturas para descubrir el comportamiento de fase y el ensamblaje de las moléculas. La quiralidad del compuesto juega un papel determinante en el comportamiento de fase de los materiales.In this thesis study of influence of geometry of the molecules on self-assembly monolayers (SAM) of chiral acids was studied, the synthesis of family of chiral amphiphiles was presented. Each compound was measured with STM at the graphite-1-phenyloctane interface as a single enatiomer and as a racemic mixture to check the transfer of chirality from molecule to two dimensional SAM. It was found that the bent-core molecules – 1,3Ph and 2,7Naph form very regular domains in the case of pure enatiomer and conglomerate in the case of racemic mixture. The other compounds form various polymorphs (up to four in the case of 1,5Naph) or irregular 2D crystals (2,6Naph), and when the racemic mixture was studied, the SAM was disordered or a pseudoracemate was found for 4,4´Biph. The mixtures of the naphthalene derivatives were studied at the graphite-1-phenyloctane interface to check if compounds are capable of forming mixed monolayers, moreover the same mixtures were measured with differential scanning calorimetry (DSC) and X-ray diffraction (XRD) to compare behaviour in two and three dimensional systems. It was discovered that the acids form stable mixed monolayers, and in one case a solid solution behaviour was observed. The chiral recognition between amphiphilic acids was checked with a model chiral amine -1,2 trans-diaminocyclohexane (DACH) - to discover that in case of acid 1,3Ph and 2,7Naph there is a chiral recognition and diastereselective formation of a complex at the graphite-1-phenyloctane interface. In the case of acid 2,7Naph and DACH also formation of multilayers was observed. The molecular modelling was used to get insight into the forces and packing of the molecules. The acid 1,3Ph was chosen to study its capability of binding various chiral and achiral amines including compounds used as medicaments: Metoprolol, Antenolol and Verpamil. It was found in the case of Metoprolol that there is preferential binding of one of the enantiomers at the graphite-1-phenyloctane interface. Also mixtures of acids was checked for their capability to act as a resolving agent in two dimensional systems, but no clear evidence of improvements over the pure were observed because of competitive adsorption. Also the series of experiments of bulk mixtures of acid 1,3Ph and DACH was performed to check if there is a chiral recognition in three dimensional systems. The samples were checked with DSC, XRD and in polarized optical microscope (POM) in a range of temperatures to discover the phase behaviour and packing of molecules. The chirality of the component plays a determining role in the phase behaviour of the materials.
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Preuss, Kathryn Elvia. "Sulfur nitrogen heterocycles as charge transfer materials." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0018/NQ53510.pdf.
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McIvor, S. D. "Heat transfer properties of satellite component materials." Thesis, University of Salford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381718.
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Poorten, Thomas J. "Maternal transfer of antibodies in Xenopus laevis." Electronic thesis, 2008. http://dspace.zsr.wfu.edu/jspui/handle/10339/174.
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Paxson, Adam Taylor. "Advanced materials for enhanced condensation heat transfer." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92168.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 147-164).
This thesis investigates the use of three classes advanced materials for promoting dropwise condensation: 1. robust hydrophobic functionalizations 2. superhydrophobic textures 3. lubricant-imbibed textures We first define the functional requirements of a hydrophobic functionalization for promoting dropwise condensation and use these guidelines to investigate two subclasses of materials: rare-earth ceramics and fluoropolymer films deposited via initiated chemical vapor deposition (iCVD). We show how both materials exhibit robust dropwise behavior, and further subject an iCVD film to an accelerated endurance trial to show how it sustains dropwise condensation throughout a 3-month equivalent trial. Next we combine hydrophobic functionalization with rough texture to obtain superhydrophobic surfaces and identify a self-similar depinning mechanism governing adhesion on surfaces with multiple roughness length scales. We introduce the metric of pinned fraction to show how these surfaces must be designed to minimize adhesion. We then show how dropwise condensation on superhydrophobic surfaces and the ensuing "jumping" behavior consists of not only binary coalescences, but multiple-drop coalescences with tangential departure that result in increased departing mass flux. However, we find that although this mode of condensation is readily achievable when condensing working fluids with high surface tension, such as water, even re-entrant structures that are known to support millimetric droplets of low-surface tension liquids in a superhydrophobic state are not sufficient to promote the dropwise mode of condensation for working fluids with low surface tension. Finally, we extend the applicability of textured surfaces by imbibing solid textures with a lubricant stabilized by capillary wicking. We show how these surfaces, when both solid texture and lubricant are properly designed, can promote dropwise condensation and reduce departing diameter of not only steam, but also of low-surface tension working fluids. In summary, we find that all three classes of surfaces provide significant increases in vapor-side heat transfer coefficient. However, when considering the overall heat transfer coefficient of a surface condenser, we find that most of the benefits of dropwise condensation can be realized by hydrophobic functionalization.
by Adam T. Paxson.
Ph. D.
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Duarte, Rute Catarina Batista de Carvalho. "Materials for energy: opportunities for technology transfer." Master's thesis, Universidade de Aveiro, 2011. http://hdl.handle.net/10773/7567.
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Mestrado em Engenharia QuímicaEnergy is a current topic and although due to different motivations (rising fuel costs, environmental issues or supply security) the main goals are common, consume less energy and find alternatives to fossil fuel based technologies. Nowadays, significant efforts towards the implementation of sustainable energy technologies, by delineating strategies and priorities, as well as through developing supporting mechanisms and building scenarios. In Europe this efforts are being taken in order to meet the ambitious and binding energy and climate change objectives for 2020. In the form of electricity, heat, light, mechanical, biological or chemical, energy will become an always more expensive commodity, and therefore there is a great need to manage this resource effectively. New products made from new advanced materials can have a large impact on the energy field. It is intended with this dissertation to better understand the energy problem nowadays, to explore applicability of materials science towards sustainable energy technologies with potential to commercial deployment and to understand in each way the positioning of the University of Aveiro associate laboratory CICECO – Centre for Research in Ceramics and Composites Materials, the largest Portuguese institute in the field of materials science and engineering, is fulfilling these assumptions. Therefore, this analysis aims at gathering information in order to create a tool for strategic decision making.
A energia é uma temática atual e, apesar das diferentes motivações (o aumento do consumo de combustíveis, as questões ambientais ou de segurança de abastecimento), os principais objetivos são comuns, reduzir o consumo de energia e encontrar formas de energia alternativas aos combustíveis fósseis. Actualmente estão a ser desenvolvidos esforços significativos no sentido da implementação de tecnologias de energia sustentável, delineando para tal estratégias e prioridades, assim como desenvolvendo mecanismos de financiamento e projecção de cenários. Na Europa, estes esforços estão a ser desenvolvidos no sentido de cumprir com os objectivos ambiciosos estabelecidos para 2020, no que respeita a energia e às alterações climáticas. Sob a forma de electricidade, calor, luz, mecânica, biológica ou química, a energia vai se tornar uma comodidade cada vez mais cara e, neste sentido, há uma grande necessidade de gerir este recurso de forma eficaz. Novos produtos resultantes do desenvolvimento de novos materiais avançados poderão ter um impacto significativo na área da energia. Pretende-se com esta dissertação analisar a atual problemática energética, explorar a aplicabilidade da ciência dos materiais em tecnologias energéticas sustentáveis com potencial de comercialização e perceber de que forma o posicionamento do Laboratório Associado da Universidade de Aveiro, CICECO - Centro de Investigação em Materiais Cerâmicos e Compósitos, o maior instituto Português em matéria de engenharia e ciência dos materiais, vai ao encontro desses pressupostos. Deste modo, a presente análise pretende reunir informação de forma a criar uma ferramenta de apoio à decisão em termos de desenvolvimento estratégico.
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Little, Stephen. "Painting in transit : inter-domain transfer and material reformation." Thesis, Goldsmiths College (University of London), 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539865.
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Martínez, López Brais. "Development of new characterization methodologies and modelling of transport properties on plastic materials : application to homologous series of tracers." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20240.
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Les matériaux placés au contact avec des aliments doivent répondre aux critères d'inertie définie par la réglementation européenne, qui fixe les limites de migration des substances qui peuvent être transférés aux aliments. Traditionnellement, ces niveaux de migration étaient déterminés expérimentalement par la mise en œuvre de tests de migration impliquant des moyens analytiques et des délais de temps importants. Récemment et par une évolution de la réglementation, les outils de modélisation ont été validés en tant que moyens d'estimation du niveau de migration des additifs dans les matériaux d'emballage plastiques. Néanmoins, les modèles appliqués nécessitent certains paramètres tels que le coefficient de diffusion (ou diffusivité), le coefficient de transfert de matière et le coefficient de partage. Ces coefficients, en particulier la diffusivité, peuvent être déterminés expérimentalement, ou par la voie de la modélisation prédictive. La microspectroscopie Raman a été utilisée pour développer une méthode de caractérisation du coefficient de diffusion, en utilisant comme matrice polymérique modèle le polystyrène amorphe. Cette méthode a été appliquée à deux familles (série homologue) de molécules qui présentent comme unité fondamentale un noyau benzénique, ceci dans le but de pouvoir établir des relations entre les variations des valeurs de diffusivité dans la matrice polymérique et les caractéristiques géométriques des molécules (volume, longueur, compressibilité) qui décrivent la mobilité des molécules en fonction de leur encombrement. Cette méthode a, par ailleurs, été adaptée de manière à être appliqué au polyéthylène basse densité dans le but d'établir les conditions opératoires qui permettent de caractériser simultanément la diffusivité et le coefficient de transfert de matière. Ce travail a ainsi permis de poser les bases d'un modèle de prédiction de la diffusivité qui repose sur des caractéristiques géométriques et dynamiques des molécules, sans imposer une puissance de calcul importante par rapport aux autres modèles proposés dans la littérature. En outre, ce travail a permis d'étudier la sensibilité des modèles mathématiques par rapport à la régression simultanée de plusieurs variables descriptifs des transferts de matièreFood contact materials must comply with the inertia criteria defined by European regulation, which establishes migration limits for substances that may be transferred into food. Traditionally, migration levels were determined experimentally by performing money and time-consuming migration tests. Recently, modelling tools have been approved to predict migration levels of additives from plastics. However, these models need of certain parameters: the diffusion coefficient or diffusivity, the mass transfer coefficient and the partition coefficient. These coefficients, particularly diffusivity, may be determined experimentally or by predictive modellingRaman microspectroscopy was used to develop a methodology for the characterisation of diffusivity, using amorphous polystyrene as model polymeric matrix. This methodology was applied to two families (homologous series) of molecules presenting the benzenic ring as fundamental unit, with the goal of establishing relationships between diffusivity in the polymeric matrix and geometrical characteristics of the molecules (volume, length, compressibility), describing molecular mobility in function of their hindrance.This method has also been adapted to LLDPE, with the goal of establishing the operating conditions allowing to simultaneously determine both diffusivity and mass transfer coefficient.This work has also allowed to lay the foundations of a diffusivity prediction model, based on geometrical and dynamical characteristics of molecules, without the need of a huge computing power compared to other models present in literature. As well, this work permitted to study the sensitivity of the mathematical models regarding simultaneous regression of several variables used in the description of mass transfer
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Karlsson, Patrik. "The influence of tool steel microstructure on galling." Doctoral thesis, Karlstad universitet, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-61013.
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In sheet metal forming (SMF) of materials such as stainless steels there is a major problem with transfer and accumulation of sheet material to the metal forming tool surface. The problem is known as galling; a sort of severe adhesive wear, which results in severe scratching of produced parts. In this thesis, the overall aim was to gain knowledge of the influence of tool steel microstructure on galling initiation under sliding conditions. It was discovered that material transfer and tool steel damage caused by sheet material flow creating wear-induced galling initiation sites occurred in the early stage of galling. The galling resistance was higher for tool steels with higher matrix hardness due to better resistance to tool steel damage. Initial friction and critical contact pressure to galling was influenced by the strength of the sheet material. Material transfer happened at low pressures and the friction value was high in a case of sheet materials with lower proof strength, possibly due to the sheet contact against the tool steel matrix resulting in high adhesion and quicker tool damage. It was demonstrated that, in addition to hardness of the tool steel matrix and sheet material proof strength, tool steel microstructural features like size, shape, distribution and height of hard phases are important parameters influencing galling. Tool steels comprising homogeneously distributed, small and high hard phases better prevented the contact between sheet material and the tool steel matrix. Thus, a metal to metal contact with high friction was more efficiently avoided, which resulted in better tool performance.
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Liu, Ying. "Nanoscale Thermal Transport at Graphene-Soft Material Interfaces." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/71715.
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Nanocomposites consist of graphene dispersed in matrices of soft materials are promising thermal management materials. A fundamental understanding of the thermal transport at graphene-soft material interfaces is essential for developing these nanocomposites. In this dissertation, thermal transport at graphene-octane interfaces was investigated using molecular dynamics simulations, and the results revealed several important characteristics of such thermal transport.
The interfacial thermal conductance of graphene-octane interfaces were studied first. It was found that the interfacial thermal conductance exhibits a distinct duality: if heat enters graphene from one side of its basal plane and leaves it through the other side, the corresponding interfacial thermal conductance, Gacross, is large; if heat enters graphene from both sides of its basal plane and leaves it at a position far away on its basal plane, the corresponding interfacial thermal conductance, Gnon-across, is small. Gacross is ~30 times larger than Gnon-across for a single-layer graphene immersed in liquid octane. Additional analysis showed that this duality originates partially from the strong, positive correlations between the heat fluxes at the two surfaces of a graphene layer.
The interfacial thermal conductance of the graphene-soft material interfaces in presence of defects in the graphene was then studied. The results showed that the heat transfer at the interfaces is enhanced by defects. Estimations based on effective medium theories showed that the effective thermal conductivity of the graphene-based composites could even be enhanced with defects in graphene when heat transfer at the graphene-soft material interface is the bottleneck for the thermal transport in these composites.
To describe the interfacial thermal transport at graphene interfaces uniformly, a nonlocal constitutive model was proposed and validated to replace the classical Kapitza model. By characterizing the thermal transport properties of graphene interfaces using a pair of thermal conductance, the model affords a uniform description of the thermal transport at graphene interfaces for different thermal transport modes. Using this model, the data interpretation in time domain thermalreflectance (TDTR) measurements was investigated, and the results showed that the interfacial thermal conductance measured in typical TDTR tests is that of the across mode for thin-layered materials.Ph. D.
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Galbraith, Graham H. "Heat and mass transfer within porous building materials." Thesis, University of Strathclyde, 1992. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21508.
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The thermal and structural performance of building elements can be significantly impaired by the presence of excess moisture. At present, designers have available only simplistic steady-state techniques to predict such effects, for example that presented by Glaser in 1959. These simple models recognise moisture transport in vapour form only and do not allow information on material moisture content to be obtained directly. They are also based on the assumption that the material transport properties are independent of the prevailing environmental conditions, whereas they are in fact complex functions of parameters such as relative humidity. This research has been carried out to develop a set of model equations which account for both liquid and vapour transfer through porous structures, and which enable material moisture content profiles to be produced. The equations generated in this work are transient and enable the effects of moisture and thermal capacity to be considered. An experimental investigation has also been carried out to produce a methodology which can be used to obtain the required material properties. These equations and material properties have been combined with realistic boundary conditions to produce a finite difference model which enables simple wall structures to be analysed in terms of temperature, vapour pressure, relative humidity, moisture content and moisture flow rate. The use of this FORTRAN 77 computer code is illustrated by application to traditional and timber-framed wall constructions. The results illustrate the applicability and flexibility of such an approach and confirm the importance of its further development in the future.
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Schmidtmann, Marc. "Hydrogen transfer in hydrogen bonded solid state materials." Thesis, Connect to e-thesis, 2008. http://theses.gla.ac.uk/284/.
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Thesis (Ph.D.) - University of Glasgow, 2008.Ph.D. thesis submitted to the Department of Chemistry, Faculty of Physical Sciences, University of Glasgow, 2008. Includes bibliographical references. Print version also available.
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Gillespie, Peter N. O. "Theory of charge transfer in solar energy materials." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/22771/.
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Vogl, Gregory William. "Comprehensive Theory of Heat Transfer in Heterogeneous Materials." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/30881.
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For over forty years, researchers have attempted to refine the Fourier heat equation to model heat transfer in engineering materials. The equation cannot accurately predict temperatures in some applications, such as during transients in microscale (< 10^-12 s) situations. However, even in situations where the time duration is relatively large, the Fourier heat equation might fail to predict observed non-Fourier behavior. Therefore, non-Fourier models must be created for certain engineering applications, in which accurate temperature modeling is necessary for design purposes.
In this thesis, we use the Fourier heat equation to create a general non-Fourier, but diffusive, equation that governs the matrix temperature in a composite material. The composite is composed of a matrix with embedded particles. We let the composite materials be governed by Fourier's law and let the heat transfer between the matrix and particles be governed by contact conductance. After we make certain assumptions, we derive a general integro-differential equation governing the matrix temperature. We then non-dimensionalize the general equation and show that our model reduces to that used by other researchers under a special limit of a non-dimensional parameter.
We formulate an initial-boundary-value problem in order to study the behavior of the general matrix temperature equation. We show that the thermalization time governs the transition of the general equation from its small-time limit to its large-time limit, which are both Fourier heat equations. We also conclude that our general model cannot accurately describe temperature changes in an experimental sand composite.Master of Science
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Ayaz, Serife. "Development Of A Genetic Material Transfer Approach For Gene Therapy." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/3/12605939/index.pdf.
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This thesis is focused on the development of a gene delivery system, especially for the purpose of DNA vaccination. DNA expression vectors have the potential to be useful therapeutics for a wide variety of applications. A carrier system was designed to realize the delivery of genes to cells and the promotion of controlled adequate expression in the target cells. The low gene delivery efficiency observed with systems composed of polyplexes is mainly due to low stability of polycation e.g polyethylenimine-DNA complexes and inability of most of the complexes to the reach nucleus after entering the cells. The encapsulation of polyethylenimine-DNA complexes inside the alginate microspheres was expected to provide protection from nuclease-based attack, thereby, increasing the stability of the complex and also to achieve controlled release of the complex at the target tissue.
In this study, controlled release of complexes from alginate microspheres was studied with DNA staining. In Tris-HCl buffer, the release of PEI-DNA complexes were completed in 48 h, however in cell culture medium (DMEM) 18 % of complexes were released in 48 h because of presence of Ca+2 ions in DMEM. Also, in order to provide mucosal gene delivery for mucosal immunization polyethylene glycol (PEG) was introduced into the composition of microspheres and the two systems were compared in terms of release kinetics of the complexes. In the presence of PEG, release of PEI-DNA complexes from alginate microspheres in the cell culture medium (DMEM) were enhanced and 50 % of PEI-DNA were released from the microspheres in 48 h. To understand the effect of the PEG on the surface of microspheres zeta potential analysis and microscopic examination were carried out. By increasing percentage of PEG (0, 15, 30, 50) in microspheres, less negative zeta potential value were measured. Mucoadhesion of alginate and PEG-alginate microspheres were evaluated by using modified microbalance method, and in the presence of PEG enhancement of mucoadhesion was observed. In this way a gene delivery system with a possible route through mucosa of tissues was prepared.
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Rosner, Martin Siegfried. "Boron as a tracer for material transfer in subduction zones." Phd thesis, [S.l. : s.n.], 2003. http://pub.ub.uni-potsdam.de/2003/0030/rosner.pdf.
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Kim, Yunjo. "Two-dimensional material based layer transfer of thin film devices." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111747.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 40-42).
The semiconductor industry has mainly centered around silicon-based technology due to its associated cost advantage stemming from the abundance of the element and well-established fabrication infrastructures. However, there exists a plethora of compound semiconductors that offer unique electronic properties that can enable high performance devices superior to silicon for a wide range of device applications. Unfortunately, compound semiconductors industries have seen limited adoption in industries except in occasions where silicon-based technology cannot be used. This is mainly due to the rarity and high production costs associated with alternative semiconductor wafers. There have been many proposals that attempt to reduce the cost of production of these compound semiconductors by offering reusable wafers. In this scheme, the wafer is used as a platform to fabricate devices, the device layer is subsequently exfoliated from the wafer via a layer transfer allowing for the wafer to be re-used for continuous fabrication of thin-film devices. However, the layer transfer techniques that have been proposed so far often damages the wafer substrate, limiting their reusability and adding additional costs for surface refurbishment processes. This thesis proposes a novel layer transfer process, termed two-dimensional material based layer transfer (2DLT), which prepares thinfilm semiconductors by facile mechanical exfoliation to yield a clean wafer surface requiring minimal surface treatment. Moreover, this process can be applied to a wide range of material systems, suggesting a universal layer transfer process. The 2DLT process discussed in this work is enabled by a novel concept of semiconductor epitaxy, termed remote epitaxy. This thesis explores remote epitaxial growth of compound semiconductors on a graphene coated substrates and exfoliation of epitaxial films grown on graphene. Due to the atomic-thickness of graphene and weak van der Waals interaction on the surface of graphene, semiconductor adatoms on the surface of graphene can be made to register to the substrate for growth of single crystalline semiconductor films. In addition, the weak interactions at the interface of graphene provides a well-defined cleavage plane for facile mechanical exfoliation of the epitaxial film. This thesis investigates the conditions and mechanisms that facilitate remote epitaxy in order to identify the fabrication processes that enable 2DLT for compound semiconductors. The materials grown via remote epitaxy exhibited comparable properties to that of epitaxial films grown by conventional homoepitaxy, this has been demonstrated by fabrication of thin-film light emitting diodes (LEDs) and metal-semiconductor field-effect transistors (MESFETs), the results of which are presented in this work.
by Yunjo Kim.
S.M.
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Kim, Tongbeum. "Fluid-flow and heat-transfer in a lattice-frame material." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616470.
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Perry, Mark Joseph. "Analysis of resin transfer molding: Material characterization, molding and simulation /." The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1382637062.
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Saidi, Meriem. "Etude des transferts hygrothermiques dans un matériau écologique." Thesis, Perpignan, 2018. http://www.theses.fr/2018PERP0043.
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Ce travail concerne une étude expérimentale du comportement hygrothermique de matériaux bio-sourcés sous la forme de briques de terre comprimée (BTC) et de briques de terre stabilisée (BTS). Nous avons déterminé les propriétés thermo-physiques et les isothermes de sorption de ces matériaux et évalué l'influence de l'ajout de stabilisants chimiques (ciment et chaux), sur leurs conductivités thermiques et leurs capacités hygroscopiques. Cette étude est complétée par une modélisation et une simulation numérique des transferts de chaleur et de masse dans une cavité ventilée dont l'une des parois verticales est composée de BTC. Les transferts hygrothermiques dans la paroi, assimilée à un milieux poreux, et dans la cavité ventilée sont décrits respectivement par le modèle de Luikov et les équations classiques de la convection mixte. Ces équations de transferts sont résolues par une méthode implicite aux différences finie, la méthode itérative de Gauss-Seidel et l'algorithme de Thomas. Nous avons analysé l'influence de la température, de l'humidité relative et de la vitesse de l'air ambiant, la densité du flux de chaleur appliqué sur la face externe de la paroi ainsi que la nature du matériau bio-sourcé sur les transferts hygrothermiques dans cette paroi et l'écoulement d'air dans la cavité. Les résultats montrent que la stabilisation chimique augmente la conductivité thermique de la BTC et réduit sa capacité de sorption. L'accroissement de la densité du flux de chaleur appliqué sur la face externe de la paroi de BTC provoque une augmentation des transferts de chaleur par mode latent et sensible entre la face interne de cette paroi et l'air qui s'écoule dans la cavitéThis work concerns an experimental study of the hygrothermal behavior of compressed earth bricks (CEB) and stabilized earth bricks (SEB). We determined its thermo-physical properties and sorption isotherms and evaluated the impact of the chemical stabilizers (cement and lime) addition on their thermal conductivities and hygroscopic capacities. This study is complemented by a modeling and numerical simulations of heat and mass transfers in a ventilated cavity one of its vertical walls is composed of CEB. The heat an mass transfers in this wall, assimilated to a porous medium, and in the ventilated cavity are respectively described by the Luikov model and the mixed convection equations. The transfer equations are solved using an implicit finite difference method, the Gauss–Seidel method and the Thomas algorithm. We have analyzed the effects on the heat and mass transfers within this wall and in the cavity of the temperature and relative humidity air, the inlet air velocity in the cavity and the heat flux density applied on the external face of the vertical wall composed of CEB. These results show that chemical stabilization increase the thermal conductivity of CEB and leads to a reduction in moisture sorption capacity. The increase of the heat flux density applied to the external face of the wall composed of CEB leads to an augmentation of the latent and sensible heat transfers between the inner face of this wall and the air flowing in the cavity
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Motedayen, Ali Akbar. "Novel stratified self-assembled Polyehtylene-Organoclay films for food packaging." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT156.
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Inspiré par la technique couche par couche traditionnelle (LBL), Ce travail de thèse démontre le premier effort pour développer une nouvelle méthodologie pour l’auto-assemblage des multicouches sur la base des interactions hydrophobes et d'adsorption physique pour fabriquer des films composites stratifié en Polyéthylène (LLDPE) - organoargile (OMMT). Contrairement à la technique LbL électrostatique, ici, les films multicouches ont été synthétisés en partant d'un substrat de polymère non polaire/non chargé et successivement le dépôt de couches d’organo-argile apolaire et de couches de PE non polaires/non chargés avec des dépôts répétitifs qui se suivent. La variation alternative de l'angle de contact (85° en moyenne pour l’organo-argile et 107° pour les couches de PE) a confirmé la profilométrie et les résultats de la microscopie électronique à balayage, ainsi que le modèle de croissance linéaire, la formation très stratifiée réussie de bicouches répétitives composées de 450 nm couches d’organo-argiles et 2,25 µm couches de PE. Ultérieurs essais de caractérisation ont été effectués pour évaluer l'effet de la variation des principaux paramètres de processus identifiés (concentration, température, les étapes de rinçage et de séchage, et le type de solvant), sur la formation et la croissance d'épaisseur des films. En conséquence, la forte dépendance de l'auto-assemblage aux paramètres du procédé testés a été montrée par les résultats expérimentaux obtenus. Les propriétés de barrière des films multicouches ont également été évaluées par la caractérisation de la perméabilité à la vapeur d'eau, à l'oxygène (O2) et au dioxyde de carbone (CO2), ainsi que la sorption de la vapeur d'eau. Un revêtement de 5 bicouches (OMMT/PE) (~ 14 µm d'épaisseur) a réduit la perméabilité à l'O2 d'un film de PE de 160 µm d'épaisseur de 84,4% et la perméabilité au CO2 de 70%, tandis que la perméabilité a la vapeur d’eau a été réduite de 45%. Ces réductions de perméabilité obtenues par seulement l’ajout de 2,4% (v/v) de nano-argile se sont révélés être significativement plus élevée par rapport aux valeurs de réduction rapportées dans la littérature pour les nanocomposites dispersés préparés à base de PE/organo-argile. Cette connaissance peut être utilisée dans la mise en place d'une approche pour produire des micro/nanostructures stratifiés ayant des propriétés de barrière sur mesure pour l'application dans l'emballage alimentaireInspired by the traditional Layer-by-Layer (LbL) assembly technique, this PhD study demonstrates the first effort to develop a novel methodology for multilayer self-assembly on the basis of hydrophobic interactions and further physical adsorption to fabricate stratified Polyethylene(LLDPE)-organoclay(OMMT) nano-enabled composite film. In contrary to the electrostatic LbL technique, here, the multilayer films were synthesized by starting from an uncharged apolar polymer substrate and successively depositing apolar organoclay and uncharged apolar PE layers with subsequent repeating depositions. The alternate variation of contact angle (85° average for organoclay and 107° for PE layers) confirmed the profilometry and the scanning electron microscopy results as well as the linear growth pattern, i.e. the successful highly stratified assembly of repetitive bilayers comprised of 450 nm organoclays and 2.25 µm PE layers. Further characterization tests were performed to evaluate the effect of the main identified process parameters (concentration, temperature, rinsing and drying steps, and solvent type) variation on the formation and thickness growth of the films. As a consequence, the high dependence of the self-assembly’s growth to the tested process parameters was showed by the obtained experimental results. The barrier properties of the multilayer films were also evaluated by characterizing the Water vapour, Oxygen (O2), and Carbon dioxide (CO2) permeability as well as the water vapour sorption. A 5-bilayer (OMMT/PE) coating (∼14 µm thick) reduced the O2 permeability of a 160 µm-thick PE film by 84.4% and the CO2 permeability by 70%, while the WVP was reduced by 45%. These permeability reductions obtained by only 2.4 v/v % of nanoclay addition level were found to be significantly greater compared to the reduction values reported in the literature for prepared blend PE/organoclay nanocomposites. This knowledge can be used in the establishment of an approach to produce stratified micro/nanostructures with tailored barrier properties for food packaging application
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Zerdane, Serhane. "Exploring photoswitching pathways in photomagnetic materials with ultrafast optical and X-ray spectroscopies." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S150/document.
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Ce travail de thèse porte sur l’étude de la dynamique femtoseconde de photo-commutation de matériaux moléculaires bistables, à l’aide d’expériences pompe-sonde basées sur les spectroscopies optiques et rayons X. Une partie des expériences a été réalisée sur synchrotron et X-FEL (X-ray Free Electron Laser). La première partie de la thèse, qui est consacrée à l’étude de systèmes à transition de spin non-octaédriques, a révélé différents chemins de transformations sur la surface de potentiel, associés à différents mécanismes de changement d’état électronique et modulant la cohérence de la dynamique structurale pilotant le processus. La seconde partie porte sur l’étude d’analogues du bleu de Prusse (CoFe) où les expériences ultra-rapides ont permis de d’étudier les dynamiques de transformation autour des sites de fer et de cobaltThis thesis focuses on the study of the femtosecond photoswitching dynamic in the bistable molecular materials, using the pump-probe experiments which are based on the optical and x-ray spectroscopies. Part of these experiments was performed at synchrotron and X-FEL (X-ray Free Electron Laser). The first part of the thesis, which is devoted to the study of non-octahedral spin transition systems, revealed different pathways of transformation on the potential surface. The second part focuses on the study of the Prussian Blue Analogues (CoFe), where the ultra-fast experiments allowed to follow the dynamics around the two metal ions
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Nouri, Nima. "Radiative Conductivity Analysis Of Low-Density Fibrous Materials." UKnowledge, 2015. https://uknowledge.uky.edu/me_etds/66.
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The effective radiative conductivity of fibrous material is an important part of the evaluation of the thermal performance of fibrous insulators. To better evaluate this material property, a three-dimensional direct simulation model which calculates the effective radiative conductivity of fibrous material is proposed. Two different geometries are used in this analysis.
The simplified model assumes that the fibers are in a cylindrical shape and does not require identically-sized fibers or a symmetric configuration. Using a geometry with properties resembling those of a fibrous insulator, a numerical calculation of the geometric configuration factor is carried out. The results show the dependency of thermal conductivity on temperature as well as the orientation of the fibers. The calculated conductivity values are also used in the continuum heat equation, and the results are compared to the ones obtained using the direct simulation approach, showing a good agreement.
In continue, the simulated model is replaced by a realistic geometry obtained from X-ray micro-tomography. To study the radiative heat transfer mechanism of fibrous carbon, three-dimensional direct simulation modeling is performed. A polygonal mesh computed from tomography is used to study the effect of pore geometry on the overall radiative heat transfer performance of fibrous insulators. An robust procedure is presented for numerical calculation of the geometric configuration factor to study energy-exchange processes among small surface areas of the polygonal mesh.
The methodology presented here can be applied to obtain accurate values of the effective conductivity, thereby increasing the fidelity in heat transfer analysis.
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Weng, Haoyue. "Multidimensional Modeling of Pyrolysis Gas Transport Inside Orthotropic Charring Ablators." UKnowledge, 2014. https://uknowledge.uky.edu/me_etds/50.
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During hypersonic atmospheric entry, spacecraft are exposed to enormous aerodynamic heat. To prevent the payload from overheating, charring ablative materials are favored to be applied as the heat shield at the exposing surface of the vehicle. Accurate modeling not only prevents mission failures, but also helps reduce cost. Existing models were mostly limited to one-dimensional and discrepancies were shown against measured experiments and flight-data. To help improve the models and analyze the charring ablation problems, a multidimensional material response module is developed, based on a finite volume method framework. The developed computer program is verified through a series of test-cases, and through code-to-code comparisons with a validated code. Several novel models are proposed, including a three-dimensional pyrolysis gas transport model and an orthotropic material model. The effects of these models are numerically studied and demonstrated to be significant.
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Ianniciello, Lucia. "Etude du comportement thermique d'une batterie électrochimique thermorégulée par matériaux à changement de phase pour le véhicule électrique." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEM020/document.
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La gestion thermique des batteries Li-ion pour le véhicule électrique est essentielle, pour assurer une autonomie et une durée de vie optimales de ces batteries. Habituellement, des circuits d'air ou de liquide de refroidissement sont utilisés comme systèmes de gestion thermique. Cependant, ces systèmes sont coûteux en termes d'investissement et d'exploitation et doivent être dimensionnés sur la puissance maximale à extraire. L'utilisation de matériaux à changement de phase (MCP) pour l’absorption sous forme de chaleur latente de la chaleur à dissiper peut représenter une alternative moins coûteuse et plus facile à utiliser. En effet, les MCP peuvent stocker passivement la chaleur excédentaire produite et être utilisés en tant que systèmes passifs. Cependant, les MCP présentent de nombreux inconvénients comme la difficulté de décharger l’énergie thermique stockée, ce qui limite l’aptitude du système au cyclage, ou encore leur conductivité thermique peu élevée qui limite les capacités d’échange. Pour résoudre le problème de la régénération des MCP, un système actif supplémentaire peut être ajouté, dimensionné sur une puissance modérée; l'ensemble devient alors un système semi-passif. Dans cette étude, un système de gestion thermique composé d'un MCP et d’air en convection forcée est évalué. Ce système permet de coupler les avantages de ces deux techniques. Une modélisation du système est développée pour une cellule de batterie. Une comparaison avec de l’air uniquement, en convection forcée, montre l'utilité du MCP. Pour augmenter la capacité d’échange du MCP, un matériau à haute conductivité thermique peut être ajouté au MCP, ce qui permet d’obtenir un composite ayant une conductivité thermique plus élevée. Des composites basés sur les MCP étudiés et des nanostructures de carbone sont élaborés, leur conductivité thermique est mesurée. Ensuite, un système expérimental simulant la dissipation d’une cellule de batterie est construit et utilisé pour évaluer le MCP seul, le MCP inclus dans une mousse métallique et le meilleur composite obtenu. Enfin, pour se rapprocher des conditions réelles, un modèle représentant un stack entier de batterie est développé, des simulations sont produites et les résultats obtenus sont commentésLi-ion battery thermal management is essential for electric vehicles (EVs), to ensure an optimal autonomy and lifespan of those batteries. Usually, air or coolant circuits are employed as thermal management systems. However, those systems are expensive in terms of investment and operating costs and must be dimensioned on the maximal power to be extracted. The use of phase change materials (PCMs) as latent heat storage medium allowing the absorption of the heat to be dissipated as latent heat may represent an alternative cheaper and easier to operate. In fact, PCMs can passively store the excess heat produced by a device and be used as passive systems. However, PCMs have several drawbacks like the difficulty to discharge the stored thermal load which limits the system’s cyclability or their low thermal conductivity which limits their heat transfer capacity. To solve the problem of the PCM regeneration, an additional active system can be added, dimensioned on a moderate power; the whole becomes a semi-passive system. In this study, a thermal management system composed of a PCM and forced air convection is evaluated. This system permits to combine the respective advantages of the two techniques. A model of the system is developed for one battery cell. A comparison with forced air convection only points out the usefulness of the PCM. To overcome the PCM low thermal conductivity, a highly conductive material can be added to the PCM permitting to obtain a composite with a higher thermal conductivity. Composites based on the PCMs studied and carbon nanostructures are elaborated, and their thermal conductivity is measured. Then, an experimental system permitting to simulate the dissipation of a battery cell is build and used to evaluate the PCM alone, the PCM embedded in metal foam and the better obtained composite. Finally, to be closer to the real conditions, a model representing an entire battery stack is developed, simulations are produced and the obtained results are discussed
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Szabo, Tamas. "Energy transfer at gas-liquid interface towards energetic materials /." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4797.
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Thesis (Ph. D.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on February 29, 2008) Vita. Includes bibliographical references.
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Mann, Sandra Elizabeth. "Studies of charge transfer in electrophotographic and related materials." Thesis, University of Exeter, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303920.
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Huang, Yi Ph D. Massachusetts Institute of Technology. "Electrically-tunable near-field heat transfer with ferroelectric materials." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92139.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 75-80).
Radiative heat transfer at small separations can be enhanced by orders of magnitude via the use of surface phonon polariton or plasmon polariton waves. This enhancement has potential applications in different devices, such as thermal emitters, thermal rectifiers, thermophotovoltaic and thermoelectric energy conversion systems. In this thesis, the author explores the tunable optical properties of ferroelectric materials to manipulate the near-field radiative heat transfer between two surfaces, aiming at the active control of near-field radiation heat transfer. Soft mode hardening of ferroelectric thin films induced by environmental changes, such as temperature and electric field, is widely used as a basis for tunable and switchable electrical and optical devices. However, this mechanism has not yet been examined for heat transfer applications. Using the fluctuation-dissipation theorem and the Dyadic Green's function method, the author shows via simulation that the magnitude and spectral characteristics of radiative heat transfer can be tuned via an externally applied electric field and temperature. Ways are explored to maximize the tuning contrast and discuss the trade-off between maximizing tunability and heat transfer. Our simulation results suggest that ferroelectrics can be used to develop new types of tunable nano-scale devices for thermal and energy conversion applications.
by Yi Huang.
S.M.
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Sayar, Sepideh. "Heat Transfer During Melting and Solidification in Heterogeneous Materials." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/36147.
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A one-dimensional model of a heterogeneous material consisting of a matrix with embedded separated particles is considered, and the melting or solidification of the particles is investigated. The matrix is in imperfect contact with the particles, and the lumped capacity approximation applies to each individual particle. Heat is generated inside the particles or is transferred from the matrix to the particles coupled through a contact conductance. The matrix is not allowed to change phase and energy is either generated inside the matrix or transferred from the boundaries, which is initially conducted through the matrix material. The physical model of this coupled, two-step heat transfer process is solved using the energy method.
The investigation is conducted in several phases using a building block approach. First, a lumped capacity system during phase transition is studied, then a one-dimensional homogeneous material during phase change is investigated, and finally the one-dimensional heterogeneous material is analyzed. A numerical solution based on the finite difference method is used to solve the model equations. This method allows for any kind of boundary conditions, any combination of material properties, particle sizes and contact conductance. In addition, computer programs, using Mathematica, are developed for the lumped capacity system, homogeneous material, and heterogeneous material. Results show the effects of control volume thickness, time step, contact conductance, material properties, internal sources, and external sources.Master of Science
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Tilahun, Muluken. "Experimental Investigation of Hyperbolic Heat Transfer in Heterogeneous Materials." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36509.
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In previous studies, evidence of thermal wave behavior was found in heterogeneous materials. Thus, the overall goal of this study was to experimentally verify those results, and develop a parameter estimation scheme to estimate the thermal properties of various heterogeneous materials. Two types of experiments (Experiments 1 and 2) were conducted to verify the existence or non-existence of thermal wave behavior in heterogeneous materials. In Experiment 1 sand, ion exchanger, and sodium bicarbonate were used as test materials, while processed meat (bologna) was used in Experiment 2. The measured temperature profiles of the samples were compared with the parabolic and hyperbolic heat conduction model results. The values of thermal diffusivity and thermal conductivity were obtained using the Box-Kanemasu parameter estimation method which is based on the comparison between temperature measurements and the solutions of the theoretical model. Overall, no clear experimental evidence was found to justify the use of hyperbolic heat conduction models rather than parabolic for the materials tested. Further comprehensive experimentation using different heating rates is warranted to definitely identify the accurate type of heat conduction process associated with such materials, and to describe the physical mechanisms which produce wave-like heat conduction in heterogeneous materials.Master of Science
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Pierce, Matthew Ryan. "Microvascular Heat Transfer Analysis in Carbon Fiber Composite Materials." University of Dayton / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1280944914.
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Moss, Kathryn Clare. "Novel intramolecular charge transfer materials and their optoelectronic properties." Thesis, Durham University, 2012. http://etheses.dur.ac.uk/3375/.
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A summary of aspects of the literature surrounding organic donor-acceptor systems for a variety of optoelectronic applications (OLEDs, OFETs, OPVs) is presented with a particular focus on two key moieties; 9,9-dialkylfluorene (F) and dibenzothiophene-S,S-dioxide (S). The development of these “building blocks” into novel systems capable of intramolecular charge transfer, i.e. donor-acceptor containing materials, is then discussed. The syntheses and photophysics of a number of novel fluorescent ambipolar trimers based on F and/or S are presented which allow investigations to be performed into the excited state behaviour of the systems. Tuning of the emission colour is demonstrated from deep blue to green by varying the strength of the donor and/or by manipulating the extent of conjugation through the systems. Related trimers are investigated which exhibit the unusual phenomenon of (low temperature) phosphorescence from all-organic systems. Development of the F/S trimers into polymers gives systems which are capable of emitting white light and all-fluorescent white-emitting devices are presented. Following on from this, the use of F as a molecular bridge between donor (ferrocene) and acceptor (C60) moieties is presented, with the aim of modulating charge transfer between the two by varying the linker between ferrocene and F as well as the length of the fluorene bridge. The synthesis and electrochemical behaviour of the compounds is discussed and photophysical studies are currently being undertaken. Finally, random co-polymers of F, S and related analogues are presented to investigate the morphology of such systems with regard to beta phase formation. A number of F and/or S based systems are also presented with the aim of finding novel high triplet energy host materials for OLEDs. The syntheses and photophysical studies of these materials are discussed. Overall, the work demonstrates the great potential of F and S in donor-acceptor systems for a wide variety of optoelectronic applications.
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Fedorenko, O. O., and J. K. Warchoł. "Structural and mass transfer characteristics of carbon-fiber materials." Thesis, Київський національний університет технологій та дизайну, 2017. https://er.knutd.edu.ua/handle/123456789/6750.
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Alkhado, Luqman, and Youcef Boussaa. "Heat transfer tests on EPS material and massive timber wall component." Thesis, Högskolan Dalarna, Energiteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:du-28673.
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Timber walls are known to be an energy efficient component in the building envelope. These building elements are essential in the passive design and have been pointed out to their ability to regulate the indoor climate and reduce energy demand. Heat transfer measurements of thermal transmittance value of Iso-timber wall component have been performed with the climate chamber at three temperature differences. The influence of temperature variations on the thermal conduction of the wall were investigated. The temperature on the warm side was kept at room temperature 20 °C while the cold side temperature was decreased from 0 C to -20 C during the tests. As the temperature difference is increased, the thermal transmittance value of the timber wall component decreased slightly due to decrease in the thermal conductivity value. The effect of density and porosity on the thermal conductivity may be related to the presence of air voids and cell boundaries inside the timber wall. Results have showed that the U-value of the timber wall component decreases at higher temperature differences which indicates the higher degree of insulation of the timber wall component.
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Iyer, Nandini 1974. "Material transfer associated with the contact between polymer and silicon surfaces." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/51564.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1998.Includes bibliographical references (leaves 126-129).
Material transfer due to the contact of surfaces is encountered in a wide variety of engineering applications. One of these is the backside contamination of silicon wafers due to contact with polymer vacuum chucks during spin coating. The present research investigates material transfer associated with this contact. The contact between the silicon wafer and the vacuum chuck was idealized as pin-on-flat interaction and an experimental apparatus was fabricated based on this model. Material transfer from a variety of solid polymers (UHMWPE, Teflon, KEL-F, PMMA, PEEK, and Nylon 66) was studied and characterized by Scanning Electron Microscopy, Atomic Force Microscopy, Optical Microscopy and computer image analysis. This was augmented with studies of material transfer from polymeric films (Polyethylene, Teflon, and Kapton) and ceramics (quartz, sapphire and ruby). The variables of interest for the material transfer phenomenon were identified using analysis of elastic contacts (Hertzian) and adhesion. Experimental results suggest that the material transfer was affected by the contact area that forms between the polymer and the silicon substrate and by the contact pressure at the surface asperities. At low loads, contact area and pressure decreases causing less transfer. There is a linear relationship between the total particle area and the Hertzian contact area. For elastic contacts, the effect of surface roughness is not pronounced. Friction and surface energy also appear to be weak variables in the material transfer phenomenon. The Young's moduli of the polymers also affect material transfer. The number of particles transferred and the total particle area decreased with an increase in Young's modulus. No material transfer was observed with Kapton, quartz, sapphire and ruby. Material transfer was also inhibited with the use of a small amount of lubricant.
by Nandini Iyer.
S.M.
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Abada, Fella. "Transport d'humidité en matériaux poreux en présence d'un gradient de température : caractérisation expérimentale." Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10135.
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Ce travail de these porte sur des etudes experimentales relatives aux transferts monodimensionnels d'humidite sous differents gradients thermiques dans des materiaux poreux qui sont: le beton autoclave non expanse, la vermiculite, deux roches extraites de carrieres (rouffach et rorschach) servant a la restauration de monuments historiques. Un dispositif experimental est utilise pour le suivi continu des evolutions de teneurs en eau (methode gammametrique) et de temperatures (sondes thermiques) durant des essais de condensation et de sechage. L'objectif principal de ce travail est la determination des coefficients de transfert pour chaque materiau, determination basee sur la theorie classique du transfert de masse et de chaleur de de vries. Les coefficients de transfert sont calcules par un procede de regression entre les variables mesurees: flux de masse, gradient de temperature et gradient de teneur en eau, on donne leurs evolutions avec la teneur en eau et pour differentes temperatures. D'autres experiences sont aussi realisees donnant les conductivites thermiques et les isothermes d'adsorption permettant, ainsi, d'acquerir des informations sur le comportement des materiaux vis a vis du transfert de chaleur et de vapeur d'eau
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Cheung, Wai Lam. "Bulking of charged pellets of polymeric materials." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261854.
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