Dissertations / Theses on the topic 'Surface energy'
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Chen, Yizhou. "Adhesion of Spider Glue on Different Surface Energy and Surface Potential Surfaces." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1462227997.
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Bråmå, Erik. "Strain Energy of Bézier Surfaces." Thesis, Linköpings universitet, Matematik och tillämpad matematik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-145645.
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Bézier curves and surfaces are used to great success in computer-aided design and finite element modelling, among other things, due to their tendency of being mathematically convenient to use. This thesis explores the different properties that make Bézier surfaces the strong tool that it is. This requires a closer look at Bernstein polynomials and the de Castiljau algorithm. To illustrate some of these properties, the strain energy of a Bézier surface is calculated. This demands an understanding of what a surface is, which is why this thesis also covers some elementary theory regarding parametrized curves and surface geometry, including the first and second fundamental forms.
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Zhang, Jinhong. "Surface Forces between Silica Surfaces in CnTACl Solutions and Surface Free Energy Characterization of Talc." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/29997.
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In general, the stability of suspension can be studied using two methods. One is to directly measure the forces between two interacting surfaces in media. The other is to study the interfacial surface free energies of the particles in suspension.
Direct surface force measurements were conducted between silica surfaces in octadecyltrimetylammonium chloride (C₁₈TACl) solutions using an Atomic Force Microscope (AFM). The results showed that the hydrophobic force existed in both air-saturated and degassed C₁₈TACl solutions. The attraction decreased with NaCl addition, and was the strongest at the point of charge neutralization (p.c.n.) of silica substrate.
The force measurement results obtained in CnTACl solutions showed that the attractions decayed exponentially and became the maximum at the p.c.n.'s. The decay lengths (D) increased with surfactant chain length. The measured forces were fitted to a charged-patch model of Miklavic et al. (1994) with rather large patch sizes. It was also found that the decay length decreased linearly with the effective concentration of the CH2/CH3 groups raised to the power of -1/2. This finding is in line with the model of Eriksson et al. (1989). It suggested that the long-range attractions are hydrophobic forces originating from the changes in water structure across a hydrophobic surface-solution interface.
For the TiO₂/water/TiO₂ system, the Hamaker constant was found to be 4±1×10-20 J. The force curves obtained in the TiO₂/CnTACl system showed a repulsion-attraction-repulsion transition with increasing surfactant concentration. The long-range attraction observed between TiO₂ surfaces in CnTACl solutions reached maximum at the p.c.n., and the decay length increased with chain length.
In present work, the thin-layer wicking technique was used to determine the surface free energy (γs) and its components of talc samples. The results showed that the basal surfaces of talc are weakly basic while the edge surfaces are acidic. The effect of chemicals on the surface free energies of talc was systemically studied. The results showed that CMC (carboxymethyl cellulose sodium salt) and EO/PO (ethylene oxide/propylene oxide) co-polymers made talc surface hydrophilic by increasing the surface free energies, especially γLW and γ -. SOPA (sodium polyacrylate) increased greatly the zeta-potentials instead of the surface free energies.Ph. D.
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Mouncey, Simon Patrick. "Low energy ion-surface interactions." Thesis, Queen's University Belfast, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333823.
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Tozer, David James. "Analytic derivatives of potential energy surface." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338023.
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Yildirim, Ismail. "Surface Free Energy Characterization of Powders." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/27525.
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Microcalorimetric measurements and contact angle measurements were conducted to study the surface chemistry of powdered minerals. The contact angle measurements were conducted on both flat and powdered talc samples, and the results were used to determine the surface free energy components using Van Oss-Chaudhury-Good (OCG) equation. It was found that the surface hydrophobicity of talc increases with decreasing particle size. At the same time, both the Lifshitz-van der Waals (gSLW) and the Lewis acid-base (gSAB) components (and, hence, the total surface free energy (gS)) decrease with decreasing particle size. The increase in the surface hydrophobicity and the decrease in surface free energy (gS) can be attributed to preferential breakage of the mineral along the basal plane, resulting in the exposure of more basal plane surfaces to the aqueous phase.
Heats of immersion measurements were conducted using a flow microcalorimeter on a number of powdered talc samples. The results were then used to calculate the contact angles using a rigorous thermodynamic relation. The measured heat of immersion values in water and calculated contact angles showed that the surface hydrophobicity of talc samples increase with decreasing particle size, which agrees with the direct contact angle measurements. A relationship between advancing water contact angle qa, and the heat of immersion (-DHi) and surface free energies was established. It was found that the value of -DHi decrease as qa increases.
The microcalorimetric and direct contact angle measurements showed that acid-base interactions play a crucial role in the interaction between talc and liquid. Using the Van Oss-Chaudhury-Goodâ s surface free energy components model, various talc powders were characterized in terms of their acidic and basic properties. It was found that the magnitude of the Lewis electron donor, gS-, and the Lewis electron acceptor, gS+, components of surface free energy is directly related to the particle size. The gS- of talc surface increased with decreasing particle size, while the gS+ slightly decreased. It was also found that the Lewis electron-donor component on talc surface is much higher than the Lewis electron-acceptor component, suggesting that the basal surface of talc is basic.
The heats of adsorption of butanol on various talc samples from n-heptane solution were also determined using a flow microcalorimeter. The heats of adsorption values were used to estimate % hydrophilicity and hydrophobicity and the areal ratios of the various talc samples. In addition, contact angle and heat of butanol adsorption measurements were conducted on a run-of-mine talc sample that has been ground to two different particle size fractions, i.e., d50=12.5 mm and d50=3.0 mm, respectively. The results were used to estimate the surface free energy components at the basal and edge surfaces of talc. It was found that the total surface free energy (gS) at the basal plane surface of talc is much lower than the total surface free energy at the edge surface. The results suggest also that the basal surface of talc is monopolar basic, while the edge surface is monopolar acidic. The results explain why the basicity of talc surface increases with decreasing particle size as shown in the contact angle and microcalorimetric measurements.
Furthermore, the effects of the surface free energies of solids during separation from each other by flotation and selective flocculation were studied. In the present work, a kaolin clay sample from east Georgia was used for the beneficiation tests. First, the crude kaolin was subjected to flotation and selective flocculation experiments to remove discoloring impurities (i.e., anatase (TiO2) and iron oxides) and produce high-brightness clay with GE brightness higher than 90%. The results showed that a clay product with +90% brightness could be obtained with recoveries (or yields) higher than 80% using selective flocculation technique. It was also found that a proper control of surface hydrophobicity of anatase is crucially important for a successful flotation and selective flocculation process. Heats of immersion, heats of adsorption and contact angle measurements were conducted on pure anatase surface to determine the changes in the surface free energies as a function of the surfactant dosage (e.g. hydroxamate) used for the surface treatment. The results showed that the magnitude of the contact angle and, hence, the surface free energy and its components on anatase surface varies significantly with the amount of surfactant used for the surface treatment.Ph. D.
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Harris, Adrian F. "Relationship between surface texture, surface energy and adhesion using grit blasting." Thesis, Oxford Brookes University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284758.
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Cutts, Ross Evan. "Experimental investigation of the influence of surface energy and pore fluid characteristics on the behavior of partially saturated coarse-grained soils." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29724.
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Thesis (M. S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2010.Committee Chair: Susan E. Burns; Committee Member: Glenn J. Rix; Committee Member: J. Carlos Santamarina. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Domínguez, Álvarez Noemí. "Device and strategy for surface energy measurement." Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/463330.
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In this Ph.D. Thesis, we have developed a new measurement method to measure the contact angle and the surface energy in hydrophobic samples with a device based on confocal technology. This new measurement method incorporates the correction of the effect of the roughness of the surface in the contact angle measurement.
The developed measurement method includes the measurement with the confocal device of the Developed Interfacial Area Ratio (Sdr) of the surface under study as well as several parameters of a liquid drop placed on the surface, such as the height and the apparent diameter of the drop. On the other hand, the developed measurement method also includes three mathematical models to calculate the contact angle from a combination of the height (h) and the apparent diameter (L) of the drop measured by the confocal device, and the volume of the dispensed drop (V) indicated by the liquid dispenser. We have verified the validity of each mathematical model by evaluating the introduced error in the calculation of the contact angle.
A validation study has also been performed by comparing the calculated contact angles by means of the developed mathematical model that uses exclusively the height and the apparent width of the drop measured with the confocal device with the contact angles measured by a current commercial contact angle meter applying the height-width fitting method. This allowed us to verify the developed measurement method to calculate contact angles on different hydrophobic samples.
Furthermore, we have corrected the effect of the surface roughness of a subset of hydrophobic samples on the calculated contact angles according to Wenzel’s model. Our method uses the Sdr parameter measured with the confocal device to calculate the roughness ratio factor required to correct the calculated contact angle with the effect of the roughness.
Finally, by doing the measurement with water and diiodomethane, we have evaluated the total surface energy as well as its dispersive and polar components according to OWRK’s method from the previously corrected contact angles, obtaining accurate surface energy values.
Therefore, we can conclude that the work reported in this Ph.D. Thesis has been able to demonstrate the validity of the developed measurement methodology for evaluating the contact angle and the surface energy on hydrophobic samples with a confocal device. The advantage of this new technique is that it allows to take into account and correct the effect of the roughness in the evaluation of the surface energy, using a single device.En esta Tesis doctoral hemos desarrollado un nuevo método de medida para medir el ángulo de contacto y la energía superficial en muestras hidrofóbicas con un equipo basado en tecnología confocal. Este nuevo método de medida incorpora la corrección del efecto de la rugosidad de la superficie en la medida del ángulo de contacto. El método de medida desarrollado incluye la medida con el equipo confocal de un parámetro que mide el área real que se está midiendo, por lo que incluye la rugosidad y es conocido como Sdr por sus siglas en inglés, y además diversos parámetros de una gota que es depositada sobre la superficie a medir, tal como son la altura y el diámetro aparente de la gota. Por otro lado, el método de medida desarrollado también incluye tres modelos matemáticos que permiten calcular el ángulo de contacto a partir de la combinación de la altura (h) y el diámetro aparente (L) de la gota medidos con el equipo confocal, y también el volumen de la gota dispensada (V) indicado por el dispensador de líquidos. Hemos verificado la validez de cada uno de los modelos matemáticos mediante la evaluación del error introducido por esto parámetros en el cálculo del ángulo de contacto. También hemos realizado un estudio de validación comparando los ángulos de contacto calculados mediante el modelo matemático que únicamente utiliza h y L medidos con el equipo confocal, con los ángulos de contacto medidos por un medidor de ángulos de contacto comercial que se puede encontrar actualmente en el mercado, aplicando el método de ajuste conocido como altura-anchura (height-width). Esto nos permitió verificar el método de medida desarrollado para calcular ángulos de contacto en diferentes muestras hidrofóbicas. Además, hemos corregido el efecto de la rugosidad de la superficie según el modelo de Wenzel en los ángulos de contacto calculados para un subconjunto de muestras hidrofóbicas. Nuestro método utiliza el parámetro Sdr medido con el equipo confocal para calcular el factor de rugosidad requerido para corregir el efecto de la rugosidad de la superficie en el ángulo de contacto calculado. Finalmente, midiendo con agua y diyodometano, hemos podido evaluar la energía superficial total, así como también sus componentes dispersiva y polar de acuerdo con el método de OWRK a partir de los ángulos de contacto corregidos anteriormente, obteniendo como resultado valores de la energía superficial muy preciosos. Por lo tanto, podemos concluir que con el trabajo presentado en esta Tesis doctoral hemos sido capaces de demostrar la validez del método de medida desarrollado para evaluar el ángulo de contacto y la energía superficial en muestras hidrofóbicas con un equipo confocal. La ventaja de esta nueva técnica es que permite tener en cuenta y corregir el efecto de la rugosidad de una superficie en la evaluación de su energía superficial utilizando un único equipo de medida
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Marasli, Necmettin. "The measurement of solid-liquid surface energy." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260154.
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Elsawy, Karim Mohamed. "Mapping the potential energy surface of biomolecules." Thesis, University of York, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428480.
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Bullins, Kenneth Wayne. "Potential Energy Surface around the Tropylium Ion." Digital Commons @ East Tennessee State University, 2005. https://dc.etsu.edu/etd/1044.
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The formation of the tropylium ion, C7H7+, in the mass spectrum of toluene is a chemical process that has been studied extensively in the past. The advances in computational power of personal computers have made the investigation of the pathway to form this ion and its subsequent decomposition feasible at a fairly high level of theory. The calculations that we performed were at the HF/6-31G (d, p) and the B3LYP/6-311++G (2d) levels. This work will show areas of the potential energy surface around the highly symmetric tropylium ion to give a glance of possible mechanisms for its formation and decomposition. Our results have confirmed some of the mechanisms reported in the literature, and in addition new areas are explored in the report.
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Ozcan, Canturk. "Surface Free Energy Evaluation, Plasma Surface Modification And Biocompatibility Studies Of Pmma." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607414/index.pdf.
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PMMA is a widely used biomaterial especially in the fields of orthopedia, orthodontia and ophthalmology. When biocompatibility is considered, modification of the biomaterials’
surface may be needed to optimize interactions of the biomaterial with the biological environment. After the surface modifications one of the most important changes that occur is the change in the surface free energy (SFE). SFE is an important but an obscure property of the material and evaluation methods with different assumptions exist in the literature. In this study, SFE of pristine and oxygen plasma modified PMMA films were calculated by means of numerous theoretical approaches (Zisman, Saito, Fowkes, Berthelot, Geometric and Harmonic Mean and Acid-Base) using numerous liquids and the results were compared to each other to elucidate the differences of methods. Dispersive, polar, acidic and basic components of the SFE were calculated by the use of different liquid couples and triplets with the application of Geometric and Harmonic mean methods and Acid-Base approach. The effect of SFE and the components of SFE on the cell attachment efficiencies were examined by using fibroblast cells. It was observed that with the treatment of oxygen plasma, cell attachment capability and hydrophilicity of PMMA surfaces were altered depending on the applied power and duration of the plasma.
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Lee, Chee-kwan. "Modelling of flexible surfaces using a point mass system /." [Hong Kong : University of Hong Kong], 1992. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13204889.
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Raspal, Vincent. "Élaboration de surfaces nanostructurées d'alumine, caractérisation et modélisation de la mouillabilité." Thesis, Clermont-Ferrand 1, 2013. http://www.theses.fr/2013CLF1PP02/document.
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Au cours de ce travail, nous avons décrit et mis en œuvre la fabrication de surfaces nanostructurées d’alumine par anodisation de feuilles d’aluminium de très grande pureté. Les paramètres morphologiques caractérisant la membrane d’oxyde que sont le diamètre des pores, leur profondeur et leur espacement sont finement contrôlés par les paramètres expérimentaux. Ces surfaces nanotexturées ont permis l’étude approfondie de l’interaction solide-liquide au sein des pores et de la physique de la ligne de contact devant composer avec les nano-aspérités de surface. Ces deux éléments ont pu être appréhendés par des mesures d’angles de contact à l’équilibre et d’hystérésis de mouillage. La modélisation des résultats a montré l’inadéquation des modèles classiques de CASSIE, WENZEL ou de capillarité à cette situation. L’adjonction du terme controversé de tension de ligne permet de bonnes prévisions. Nous montrons que cette interprétation n’est pas unique ; une diminution de l’énergie de surface due à la forte courbure des pores conduit à des résultats identiques. Une investigation théorique a été menée par l’intégration des forces de VAN DER WAALS. La baisse de l’énergie de surface est prévue mais dans des proportions insuffisantes. Le modèle peut être amélioré. Les mesures d’hystérésis ont dévoilé le pouvoir adhésif des surfaces nanoporeuses. À cause des forces de capillarité dans les pores, la ligne de contact ne peut jamais reculer. Les angles d’avancée ont montré que la ligne de contact a une épaisseur négligeable devant la dizaine de nanomètre. Elle peut en outre parfaitement contourner les pores, imprimant de fortes courbures à l’interface liquide-gaz à la base de la goutte. Sa forme tridimensionnelle a été abordée au travers d’un modèle numérique restant à perfectionnerIn this work, we have described and carried out the fabrication of nanostructured alumina surfaces by anodizing highly pure aluminum foils. The pore diameter, depth and spacing are finely controled through experimental parameters. These nanotextured surfaces allowed a thorough study of the solid-liquid interactions within the pores and of the contact-line constrained by the surface nanoasperities. Equilibrium contact-angle and wetting hysteresis measurements were helpful to apprehend them. Modeling the results has revealed the inability of classical CASSIE, WENZEL and capillarity models to properly match the situation. Adding the controversial line-tension term solves the problem and provides good predictions. Anyway, this interpretation is not unique. A lower surface energy within the pores due to their strong curvature yields the same modeling quality. This case has been theoretically investigated through the integration of VAN DER WAALS’ forces. A surface-energy decrease has been calculated but it is not as strong as required. The model still can be improved. Hysteresis measurements have highlighted the nanoporous surfaces are strongly adhesive. Because of the pore size, the capillarity is very marked and keeps the contact line from receding. The advancing contact angles have shown that the contact-line thickness is negligible with respect of ten nanometres. In addition, it can circumvent the pore openings which involves strong liquid–gas interface curvatures at the drop base. The three-dimensional liquid–gas interface shape has been studied with a numerical model that still has to be enhanced
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Zhao, Xujun. "Surface loading and rigid indentation of an elastic layer with surface energy effects." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/12598.
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With the growing interest in nanotechnology, it is becoming important to understand the nanoscale mechanics to achieve successful design and fabrication of nanoscale devices. However, the classical continuum theory is not directly applicable to the analysis of nanoscale domains due to size-dependent behavior of nanostructures. Since the surface-to-volume ratio of a nanoscale domain is relatively high compared to that of a macro-scale domain, the energy associated with atoms at or near a free surface is different from that of atoms in the bulk. The effect of surface free energy therefore needs to be considered. Ultra-thin film/substrate systems, which are encountered in applications involving nanocoatings, nanotribology and material characterization based on nano-indentation, may be analyzed using modified continuum elasticity theory incorporating surface energy effects.
This thesis presents a set of analytical solutions for elastic field of a layer of nanoscale thickness bonded to a rigid base under surface loading and indentation by a rigid body. Surface energy effects are accounted for by using Gurtin-Murdoch elasticity theory. Fourier and Hankel integral transforms are used to solve the two- and three- dimensional boundary-value problems involving non-classical boundary conditions associated with the generalized Young-Laplace equation. In the case of a two-dimensional semi-infinite medium, the solutions can be expressed in closed form. The elastic field is found to depend on the layer thickness and surface elastic constants, and the influence of surface energy is shown to be more significant under a horizontal load than under a vertical load. A characteristic length scale related to the surface material properties can be identified for the present class of problems. The solution for the indentation problem is considered for flat, conical and spherical rigid indenters. The mixed boundary-value problem corresponding to a rigid indenter is formulated in terms of a dual integral equation system that is solved by using numerical quadrature. Selected numerical results are presented to show the influence of the indenter shape, surface properties and size-dependency of response.
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Whittaker, Kipp 1980. "A finite element surface tension model with forces based on surface energy minimization." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/89934.
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Porter, Stephen Christopher. "Synthesis, surface characterization, and biointeraction studies of low-surface energy side-chain polyetherurethanes /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/9845.
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Asp, Grönhagen Klara. "Phase-field modeling of surface-energy driven processes." Doctoral thesis, KTH, Metallografi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11036.
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Surface energy plays a major role in many phenomena that are important in technological and industrial processes, for example in wetting, grain growth and sintering. In this thesis, such surface-energy driven processes are studied by means of the phase-field method. The phase-field method is often used to model mesoscale microstructural evolution in materials. It is a diffuse interface method, i.e., it considers the surface or phase boundary between two bulk phases to have a non-zero width with a gradual variation in physical properties such as energy density, composition and crystalline structure. Neck formation and coarsening are two important diffusion-controlled features in solid-state sintering and are studied using our multiphase phase-field method. Inclusion of Navier-Stokes equation with surface-tension forces and convective phase-field equations into the model, enables simulation of reactive wetting and liquid-phase sintering. Analysis of a spreading liquid on a surface is investigated and is shown to follow the dynamics of a known hydrodynamic theory. Analysis of important capillary phenomena with wetting and motion of two particles connected by a liquid bridge are studied in view of important parameters such as contact angles and volume ratios between the liquid and solid particles. The interaction between solute atoms and migrating grain boundaries affects the rate of recrystallization and grain growth. The phenomena is studied using a phase-field method with a concentration dependent double-well potential over the phase boundary. We will show that with a simple phase-field model it is possible to model the dynamics of grain-boundary segregation to a stationary boundary as well as solute drag on a moving boundary. Another important issue in phase-field modeling has been to develop an effective coupling of the phase-field and CALPHAD methods. Such coulping makes use of CALPHAD's thermodynamic information with Gibbs energy function in the phase-field method. With the appropriate thermodynamic and kinetic information from CALPHAD databases, the phase-field method can predict mictrostructural evolution in multicomponent multiphase alloys. A phase-field model coupled with a TQ-interface available from Thermo-Calc is developed to study spinodal decomposition in FeCr, FeCrNi and TiC-ZrC alloys.QC 20100622
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Quinn, Paul. "Surface structure determination by medium energy ion scattering." Thesis, University of Warwick, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247980.
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Tang, Kah Beng-Kirel. "Excitation of surface systems by low energy electrons." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627598.
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Wang, Kuilong. "Surface science studies of electrochemical energy storage devices." Case Western Reserve University School of Graduate Studies / OhioLINK, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=case1056555985.
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Asp, Grönhagen Klara. "Phase-field modeling of surface-energy driven processes." Stockholm : Materialvetenskap, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11036.
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Bigelow, Alan W. "Energy Distribution of Sputtered Neutral Atoms from a Multilayer Target." Thesis, University of North Texas, 2000. https://digital.library.unt.edu/ark:/67531/metadc2657/.
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Energy distribution measurements of sputtered neutral particles contribute to the general knowledge of sputtering, a common technique for surface analysis. In this work emphasis was placed on the measurement of energy distribution of sputtered neutral atoms from different depths. The liquid Ga-In eutectic alloy as a sample target for this study was ideal due to an extreme concentration ratio gradient between the top two monolayers. In pursuing this study, the method of sputter-initiated resonance ionization spectroscopy (SIRIS) was utilized. SIRIS employs a pulsed ion beam to initiate sputtering and tunable dye lasers for resonance ionization. Observation of the energy distribution was achieved with a position-sensitive detector. The principle behind the detector's energy resolution is time of flight (TOF) spectroscopy. For this specific detector, programmed time intervals between the sputtering pulse at the target and the ionizing laser pulse provided information leading to the energy distribution of the secondary neutral particles. This experiment contributes data for energy distributions of sputtered neutral particles to the experimental database, required by theoretical models and computer simulations for the sputtering phenomenon.
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Carpenter, Michael William. "Characterizing the chemistry of yellow-poplar surfaces exposed to different surface energy environments using DCA, DSC, and XPS." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=858.
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Thesis (M.S.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains viii, 182 p. : ill. (some col.) Includes abstract. Includes bibliographical references (p. 107-114).
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Mapledoram, Leigh David. "Quantitative surface structural determination by low energy electron diffraction." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338267.
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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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Wilson, Leslie Hoipkemeier. "Bioresponse to polymeric substrates effect of surface energy, modulus, topography, and surface graft copolymers /." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0011624.
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Wang, Guanyu. "The Dynamics of Gas-Surface Energy Transfer in Collisions of Diatomic Gases with Organic Surfaces." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/51179.
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Understanding interfacial interactions at the molecular level is important for interpreting and predicting the dynamics and mechanisms of all chemistry processes. A thorough understanding of the interaction dynamics and energy transfer between gas molecules and surfaces is essential for the study of various chemical reactions. The collisions of diatomic molecules on organic surfaces are crucial to the study of atmospheric chemistry. Molecular beam scattering experiments performed in ultra-high vacuum chambers provide insight into the dynamics of gas-surface interactions.
Many questions remain to be answered in the study of gas-surface interfacial chemistry. For example, what affects the energy transfer between gas molecules and surfaces? How do intermolecular forces affect the interfacial interaction dynamics? We have approached these questions by scattering diatomic gas molecules from functionalized self-assembled monolayers (SAMs). Our results indicate that the intermolecular forces between gas molecules and surfaces play an important role in the energy transfer processes. Moreover, the stronger the intermolecular forces, the more often the incident molecules come into thermal equilibrium with the surface. Furthermore, most of the previous approaches toward understanding gas-surface interaction dynamics considered the interactions as independent incidents. By scattering O2, N2, CO and NO on both CH3- and OH- terminated SAM, we found a correlation between the gas-surface interactions and a bulk property, solubility. Both being strongly affected by intermolecular forces, the gas-surface energy transfer and solubility of gases in surface-similar solvents (water for OH-SAM, n-hexane for CH3-SAM) have a positive correlation. This correlation facilitates the understanding of interfacial dynamics at the molecular level, and helps predict the outcome of the similar-size gas collisions on surfaces.Master of Science
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Jensen, Erik Troels. "Low energy electron scattering studies of molecules at surfaces." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334137.
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Lamprou, Dimitrios A. "Towards the determination of surface energy at the nanoscale." Thesis, University of Portsmouth, 2009. https://researchportal.port.ac.uk/portal/en/theses/towards-the-determination-of-surface-energy-at-the-nanoscale(8a0a17be-dab5-4e5d-8026-ecf57e88e7e7).html.
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Surface energy, the work required to generate the surface of a solid or liquid, is an important property influencing a wide range of interfacial processes. This property determines physical interactions between phases, e.g., the degree of hydrophilicity of a solid surface and the surface adhesion of biological entities including bacteria and cells. The determination of surface energy by means of liquid/solid contact angle goniometry is well established, although only averaged values on the macro scale can be obtained and there may be practical limitations of the method, e.g., materials where liquid penetration occurs. The main aim of the research work described in this thesis has been to develop a technique to determine surface energy using atomic force microscopy, where the measurement may be obtained at a resolution of the order of the probing tip radius (50- 90 nm). To produce suitable substrate materials of known surface chemistry, self-assembled alkanethiol structures on gold have been prepared. Contact angle goniometry, atomic force microscopy, and infrared spectroscopy have been used to investigate the surface-preparation and solution-deposition conditions for the reproducible formation of the self-assembled molecular structures on gold-coated tips and substrates for atomic force microscopy. Procedures have been established for removing adsorbed material, including self-assembled monolayers, and for producing clean gold substrates. Preliminary data show that surface-saturated self-assembled monolayers form reproducibly on prolonged (> 16 h) exposure of gold-coated glass substrates to ethanolic solutions of lD-functionalised alkanethiols in the concentration range 80 - 160 mmol dm-3. The data also show that exposure for 16 h to alkanethiol concentrations in the range 160-240 mmol dm-3 promote bilayer formation whereas concentrations of 240-320 mmol dm-3 result in the deposition of multilayers, the average orientation of which is parallel to that of the first molecular layer; the use of parent I-undecanethiol solutions at concentrations of 1-80 mmol dm-3 results in incomplete monolayer coverage. The self-assembled alkanethiol structures deposited on gold from ethanolic solutions have been found to be susceptible to both chemical and structural changes: ethanol provides a medium for the formation of S-alkyl hydrogen thiocarbonates and related compounds via reaction with dissolved atmospheric CO2. Deposition from ethanolic solutions results in multilayered structures, incorporating these thiocarbonates and thiocarbonate-derived compounds, which at room temperature are susceptible to time-dependent structural rearrangement and molecular migration. To assess the applicability of the atomic force microscopy method for determining surface energy, forces of adhesion have been measured for interactions involving self-assembled molecular structures or polymer-film structures that had each been deposited onto gold-coated glass substrates and onto the probing, gold-coated cantilever. The data have been fitted into mathematical models that allow the calculation of surface energy by considering the work done for the separation of the identically coated contacting surfaces. The obtained surface energy values are in close agreement with those from corresponding contact-angle determinations, highlighting the potential usefulness of the technique for the study of surfaces at a resolution level approaching 1000 atoms. Comparative studies have shown that the employment of the atomic force microscopy technique may be preferable for the study of materials that are susceptible to penetration by liquids or for the investigation of small samples « contact angle drop diameter).
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Ahmad, Naveed. "Asphalt mixture moisture sensitivity evaluation using surface energy parameters." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/13421/.
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Asphalt mixture is mainly used for the construction of roads throughout the world. Large amounts of capital are spent for construction and maintenance of roads. Water is one of the major contributors towards the damage of the road structure. It is considered as the worst enemy of a pavement structure by directly causing a distress or indirectly magnifying a distress and hence damaging the road structure. Asphalt mixture loses its strength in the presence of water either through loss of cohesion within the bitumen or loss of adhesive bond between bitumen and aggregate. All the conventional techniques that are used for the determination of the moisture susceptibility of an asphalt mixture assess the material as a whole by using some mechanical testing technique without taking into account the individual physicochemical characteristics of both the bitumen and the aggregates. The surface energy properties of the materials, which are used to quantify their interfacial adhesion, play an important role in the final adhesive bond strength between these materials. The aim of this research is to produce detailed experimental techniques to measure the surface energy properties of bitumen and aggregate, and then combine them with a mechanical moisture sensitivity test procedure. This can greatly contribute towards the development of a powerful material screening protocol/tool for selection of bitumen-aggregate combinations that are less susceptible to moisture damage. This thesis describes the work that was carried out towards the development of a physico-chemical laboratory at the Nottingham Transportation Engineering Centre (NTEC). Four types of equipment were used, namely goniometer and dynamic contact angle analyser for determining the surface energy properties of the bitumen samples, and the dynamic vapour sorption and microcalorimeter systems for the surface energy properties of the aggregates. Large amount of material testing was carried out with these equipment and testing protocols were developed and improved over the course of experimental work. It was found that the dynamic contact angle technique and dynamic vapour sorption technique provides consistent results for bitumen and aggregates respectively as compared to the other two test equipment. The surface energy properties of the bitumen and the aggregates were then combined thermodynamically to determine the adhesive bond strength between the two materials, and the reduction in the adhesive properties if water is introduced into the system. The results showed that these thermodynamic properties generally correlate well with the moisture damage performance of these combinations from the laboratory testing. SATS mechanical test technique was used to determine the moisture susceptibility of different bitumen-aggregate combinations. The virgin material and the recovered material from the SATS tested cores were tested for the surface energy properties. It was found that the surface energy properties combined with SATS results can be used, with some exceptions, to identify compatible bitumen-aggregate combinations and hence improved moisture damage performance of the resulting asphalt mixture.
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Medendorp, Clare Aubrey. "ATOMIC FORCE MICROSCOPY METHOD DEVELOPMENT FOR SURFACE ENERGY ANALYSIS." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_diss/185.
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The vast majority of pharmaceutical drug products are developed, manufactured, and delivered in the solid-state where the active pharmaceutical ingredient (API) is crystalline. With the potential to exist as polymorphs, salts, hydrates, solvates, and cocrystals, each with their own unique associated physicochemical properties, crystals and their forms directly influence bioavailability and manufacturability of the final drug product. Understanding and controlling the crystalline form of the API throughout the drug development process is absolutely critical. Interfacial properties, such as surface energy, define the interactions between two materials in contact. For crystal growth, surface energy between crystal surfaces and liquid environments not only determines the growth kinetics and morphology, but also plays a substantial role in controlling the development of the internal structure. Surface energy also influences the macroscopic particle interactions and mechanical behaviors that govern particle flow, blending, compression, and compaction. While conventional methods for surface energy measurements, such as contact angle and inverse gas chromatography, are increasingly employed, their limitations have necessitated the exploration of alternative tools. For that reason, the first goal of this research was to serve as an analytical method development report for atomic force microscopy and determine its viability as an alternative approach to standard methods of analysis. The second goal of this research was to assess whether the physical and the mathematical models developed on the reference surfaces such as mica or graphite could be extended to organic crystal surfaces. This dissertation, while dependent upon the requisite number of mathematical assumptions, tightly controlled experiments, and environmental conditions, will nonetheless help to bridge the division between lab-bench theory and successful industrial implementation. In current practice, much of pharmaceutical formulation development relies on trial and error and/or duplication of historical methods. With a firm fundamental understanding of surface energetics, pharmaceutical scientists will be armed with the knowledge required to more effectively estimate, predict, and control the physical behaviors of their final drug products.
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Midgley, B. "Evaluation of adhesion energetics involving low surface energy films." Thesis, University of Bradford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373227.
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Wang, Zhi. "Mineral scale formation-aspects of surface energy and adhesion." Thesis, University of Leeds, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434828.
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Robinson, Ian. "Structure and surface energy of fatty acid LB films." Thesis, University of Exeter, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236526.
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Farnham, Taylor A. "Hydrate formation and adhesion on low surface energy materials." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104142.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 43-44).
Clathrate hydrates are ice-like solid substances that often form inside oil and gas pipelines and are responsible for flow blockages, sometimes leading to catastrophic disasters. Minimizing hydrate adhesion and accumulation of solids on pipelines can effectively address this problem. In this thesis, we reduce the adhesion of cyclopentane hydrates by promoting the formation of a cyclopentane barrier film between the hydrate and the solid surface. The presence of this liquid film depends on the spreading coefficient of cyclopentane on the solid in the presence of water. Through a systematic modification of the surface chemistry of the solid surface using two different silanes, we correlate the wettability of water and cyclopentane to the adhesion of cyclopentane hydrates. We demonstrate negligible hydrate formation and adhesion on octadecyltrichlorosilane-coated surfaces via macroscopic visualization, surface tilt and adhesion measurements. The use of the spreading coefficient as a design parameter could further advance the development of effective, passive, hydrate-repelling surfaces.
by Taylor A. Farnham.
S.M.
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Moorthy, Kavitha. "EFFECT OF SURFACE ENERGY OF FIBERS ON COALESCENCE FILTRATION." University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1185554340.
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Herrmann-Stanzel, Roland. "Energy Accommodation from Surface Catalyzed Reactions in Air Plasmas." ScholarWorks @ UVM, 2019. https://scholarworks.uvm.edu/graddis/1012.
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Accurate knowledge of heat transfer to materials in recombining plasmas is needed to improve heat shield designs. A lack of understanding of the chemical component of surface heating motivates the use of conservative assumptions with regards to surface catalysis in the design of thermal protection systems (TPS) that detrimentally impact payload capability. Chemical heating is the release of potential energy from recombining reactive species on the surface to form molecules. For a stable surface interacting with partially-dissociated air, the chemical heating component is due to surface-catalyzed recombination reactions of atomic O and N to produce molecular O2, N2, and NO. Unfortunately, heat flux measurements provide no fundamental information about the surface recombination pathways involved, or how the energy reaches the surface. Rather, they give a total heating rate.
This work has taken steps to advance the current poor understanding about the chemical energy transport to and from material surfaces in high-temperature, recombining plasmas. A combination of spatially resolved laser-based diagnostics and emission spectroscopy was used to measure the number densities and gradients of the reactants (N, O), the products (NO, N2) and the energy distribution of recombined molecules (NO, N2) in the boundary layer adjacent to a plasma heated material. Laser excitation can probe individual species by electronic state (atoms) and by electronic, vibrational and rotational states (molecules). Emission can probe the radiative emission for a range of species and electronic, vibrational and rotational states of both atoms and molecules. These measurements of spatial variations in species concentrations through the boundary layer are directly related to near-surface gas-phase chemistry and energy exchange and have provided experimental information that was not currently available. Results provide the initial steps to determine recombination rates and the energy deposited on the surface due to surface catalyzed recombination of atomic nitrogen and oxygen in air plasma.
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Yeh, Yun-Peng. "Surface engineering for biological recognition." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/4585.
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The underlying idea of this thesis is that the surface chemical and morphological nature of bacterial strains uniquely differentiates one from another and hence can be used as the basis for their identification and control. It follows that their interactions with an artificial substratum uniquely characterize them. In principle, potentially it is easier and faster to evaluate the interfacial energy between a bacterium and a substratum than to characterize its genome or determine molecular biomarkers characteristic of the strain, hence validation of this thesis opens the way to rapid screening and diagnosis. Auxiliary to this main idea, an advanced metrology for evaluating the interfacial energies has been developed, exploiting the power of kinetic analysis.
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Griffiths, Catherine Ruth. "Theoretical studies of potential energy functions." Thesis, University of Sussex, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285349.
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Sauerhammer, Björn. "New frontiers in surface structure determination using low energy electron diffraction : surface reconstructions, complex adsorbates and a chiral surface." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620335.
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Gao, Fang [Verfasser], and Oliver [Akademischer Betreuer] Ambacher. "Towards surface-enlarged diamond materials : creation of surface-enlarged diamond electrodes for electrochemical energy applications." Freiburg : Universität, 2016. http://d-nb.info/1119717663/34.
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Rodríguez-Urdaneta, Alejandro. "Geographical Mapping of the Building Envelope Surface Optimal Optical Properties Minimizing the Energy used to Maintain Indoor Conditions." Thesis, Högskolan Dalarna, Energiteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:du-35491.
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Several studies have shown that the buildings envelope optical properties are important in terms of energy use and thermal comfort level. However, no study has been found in regard of the optimal optical properties for the building envelope. Moreover, developments in the coil-coating industry have made possible to design cost effective optical selective surfaces for the construction sector. Based on the above mentioned, this study pretends to map the envelope optimal optical properties minimizing the energy use for large-open-volume buildings locates in Stockholm, Copenhagen, Liverpool, Amsterdam, Berlin, Vienna, Bern, Rome, and Madrid.A building could be seen as a very complex solar energy conversion system, which is very difficult to describe accurately. Nonetheless, it is possible to use Building Energy Simulation (BES) tools to model, to some extent, its thermal performance under many simplistic assumptions. The simulation tool TRNSYS 17 and the optimization tool GenOpt were selected for this study. Additionally, detailed small-open-volume building thermal performance data, obtained during passive measurements from the steel manufacturer SSAB, in Borlänge-Sweden, were used to assess the methodology for the creation of the large-open-volume simulation models. The variations in large-open-volume building design around Europe are not well documented, which constitutes one of the major impediments for this research. However, detailed European historical building U-value data from the European Union project called iNSPiRe made it possible to achieve the objective of this study.The simulation work showed, that the building envelope optimal optical properties are related to the magnitude of the heating and cooling loads. Consequently, GenOpt was used to plot the sensitivity of the building envelope optimal optical properties to the ratio between the heating demand and the total energy demand (Qheat/Qtotal). In regard to the large-open-volume building optimal optical properties in the selected locations, it was found that the allocation of optimal optical properties does not lead to significant energy savings in locations with relatively low solar availability and high thermal insulation levels. Nonetheless, a final envelope optical properties study for a small-open-volume building model based on three existing buildings differing only on their optical properties was made for 243 world-capital cities. The simulations reinforced the results for the large-open-volume building in the European locations, and additionally showed huge energy savings potential for most of the world capital cities. This investigation restates the results obtained by Joudi (2015), “Possible energy savings by the smart choice of optical properties on the interior and exterior surfaces of the building.”Varios estudios han demostrado que las propiedades ópticas de las envolturas delos edificios son importantes en términos de consumo energético y de nivel deconfort térmico. Sin embargo, no se ha encontrado estudio alguno con respecto alas propiedades ópticas óptimas para las envolturas de los edificios.Conjuntamente, los desarrollos en la industria de bobinas metálicas revestidas hanhecho posible diseñar superficies selectivas rentables para el sector de laconstrucción. Basándose en lo anteriormente expuesto, este estudio pretendemapear las propiedades ópticas óptimas de la envoltura que minimizan el uso deenergía para edificios de gran volumen abierto localizados en Estocolmo,Copenhague, Liverpool, Ámsterdam, Berlín, Viena, Berna, Roma y Madrid.Un edificio podría ser visto como un sistema de conversión de energía solar muycomplejo, que es muy difícil de describir con precisión. No obstante, es posibleutilizar las herramientas de Simulación de Energía de Edificios (BES) para modelar,hasta cierto punto, su rendimiento térmico bajo una considerable cantidad desuposiciones simplistas. El programa de simulación TRNSYS 17 y el programa deoptimización GenOpt fueron seleccionadas para este estudio. Adicionalmente, conel fin de evaluar la metodología utilizada para la creación de los modelos desimulación para edificios de gran volumen abierto, se utilizaron datos detallados derendimiento térmico de edificios de pequeño volumen abierto, obtenidos durantemediciones pasivas del fabricante de acero SSAB, en Borlänge-Suecia. Lasvariaciones en el diseño de edificios de gran volumen abierto en toda Europa noestán bien documentadas, lo que constituye uno de los principales impedimentospara esta investigación. Sin embargo, los datos detallados y en orden cronológicode los niveles de aislamiento térmico (U-value) en la construcción europea,recopilados por el proyecto de la Unión Europea llamado iNSPiRe, permitieronalcanzar el objetivo de este estudio.El trabajo de simulación demostró que las propiedades ópticas óptimas de laenvoltura del edificio están relacionadas con la magnitud de las cargas decalefacción y refrigeración. En consecuencia, GenOpt fue utilizado para graficar lasensibilidad de las propiedades ópticas óptimas de la envolvente del edificio conrespecto a la proporción entre la demanda de calefacción y la demanda total deenergía (Qheat/Qtotal). En cuanto a las propiedades ópticas óptimas del edificio degran volumen abierto en las ubicaciones seleccionadas, se encontró que laasignación de propiedades ópticas óptimas no conduce a ahorros de energíasignificativos en ubicaciones con disponibilidad solar relativamente baja y altosniveles de aislamiento térmico. Sin embargo, un último estudio de propiedadesópticas de envolvente para un modelo de construcción de pequeño volumen abiertobasado en tres edificios existentes que difieren sólo en sus propiedades ópticas serealizó para 243 capitales mundiales. Las simulaciones reforzaron los resultadospara el edificio de gran volumen abierto en las localidades europeas, y ademásmostraron un enorme potencial de ahorro de energía para la mayoría de lascapitales mundiales. Esta investigación reitera los resultados obtenidos por Joudi (2015), "Posibles ahorros de energía por la elección inteligente de propiedadesópticas en las superficies interiores y exteriores del edificio".
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Mi, Changwen. "Nanoparticles under the influence of surface/interface elasticity." Laramie, Wyo. : University of Wyoming, 2006. http://proquest.umi.com/pqdweb?did=1296091581&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Bahramian, Anohe. "Evaluating surface energy components of asphalt binders using Wilhelmy Plate and Sessile Drop Techniques." Thesis, KTH, Väg- och banteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-117463.
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In this Study, the surface energy was investigated for six penetration grade 70/100 bitumen binders. Wilhelmy Plate and the Sessile Drop were used to determine the contact angles. The purpose of this study was to compare the Wilhelmy Plate method with the Sessile Drop method, and to compare the significance of Owens-Wendt model with the significance of Acid Base model by correlating surface energy components. Better R2 –values were found for surface energy components by using the Owens-Wendt model than by using the Acid Base model. It was concluded here that Owens-Wendt model is a better model for determining surface energy components of bituminous binders than the Acid Base model since bituminous binders have low energy surfaces. For both instruments: When using Diiodomethane as a probe liquid the biggest variations among the binders were observed. When using water as a probe liquid the least variations among the binders were observed. The advancing contact angles for water determined for these six bitumen binders using the Wilhelmy plate method do not exceed the 90 degree by much, suggesting that bitumen is not extremely hydrophobic. The Sessile Drop method offers a faster and more convenient way to measure the surface energy components of bitumen binders than the Wilhelmy Plate method.
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Holmes, Daniel John. "Surface structure determination by surface extended X-ray absorption fine structure and low energy electron diffraction." Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235773.
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Balog, Richard. "Low energy electrons as a soft tool for surface modification." [S.l. : s.n.], 2004. http://www.diss.fu-berlin.de/2004/263/index.html.
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Wang, Xiangjun. "Surface Energy Patterning and Optoelectronic Devices Based on Conjugated Polymers." Doctoral thesis, Linköpings universitet, Biomolekylär och Organisk Elektronik, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7065.
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The work presented in this thesis concerns surface energy modification and patterning of the surfaces of conjugated polymers. Goniometry and Wilhelmy Balance techniques were used to evaluate the surface energy or wettability of a polymer’s surface; infrared reflectionabsorption spectroscopy (IRAS) was used to analyse the residuals on the surface as modified by a bare elastomeric stamp poly(dimethylsiloxane) (PDMS). The stamp was found to be capable of modifying a polymer surface. Patterning of a single and/or double layer of conjugated polymers on the surface can be achieved by surface energy controlled dewetting. Modification of a conjugated polymer film can also be carried out when a sample is subjected to electrochemical doping in an aqueous electrolyte. The dynamic surface energy changes during the process were monitored in-situ using the Wilhelmy balance method. This thesis also concerns studies of conjugated polymer-based optoelectronics, including light-emitting diodes (PLEDs), that generate light by injecting charge into the active polymer layer, and solar cells (PSCs), that create electrical power by absorbing and then converting solar photons into electron/hole pairs. A phosphorescent metal complex was doped into polythiophene to fabricate PLEDs. The energy transfer from the host polymer to the guest phosphorescent metal (iridium and platinum) complex was studied using photoluminescence and electroluminescence measurements performed at room temperature and at liquid nitrogen temperature. PSCs were prepared using low-bandgap polyfluorene copolymers as an electron donor blended with several fullerene derivatives acting as electron acceptors. Energetic match is the main issue affecting efficient charge transfer at the interface between the polymers and the fullerene derivatives, and therefore the performance of the PSCs. Photoluminescence, luminescence quenching and the lowest unoccupied molecular orbital (LUMO) together with the highest occupied molecular orbital (HOMO) of the active materials in the devices were studied. A newly synthesized fullerene, that could match the low-bandgap polymers, was selected and used as electron acceptor in the PSCs. Photovoltaic properties of these PSCs were characterised, demonstrating one of the most efficient polymer:fullerene SCs that generate photocurrent at 1 μm.On the day of the defence the status of article number III was Manuscript and article VII was Accepted.
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Castera, Philippe. "Energy coupling mechanisms in pulsed surface discharges for flow control." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2015. http://www.theses.fr/2015ECAP0041/document.
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Ce travail s'intéresse aux effets mécaniques créés par les décharges de surface et à leur efficacité comme actionneur. Une géométrie particulière d'électrodes permet de créer de manière pulsée un filament linéaire de plasma et de le chauffer très rapidement par effet Joule (à raison de plusieurs Joules en moins d'une microseconde). Ce chauffage rapide entraîne la formation d'ondes de choc qui peuvent interagir avec l'écoulement ambiant.Nous étudions le comportement électrique de la décharge de surface afin d'évaluer l'énergie déposée dans le filament de plasma par effet Joule. Pour ce faire, nous réalisons une étude paramétrique sur la configuration du circuit et nous déterminons les principaux paramètres qui pilotent la dynamique de la décharge. Différents modèles de résistance sont utilisés dans un code de simulation du circuit électrique, et leurs prédictions du courant et du dépôt d'énergie sont confrontées aux mesures expérimentales.Des mesures spectroscopiques dans différentes configurations de circuit donnent accès à certaines propriétés de la décharge comme la densité électronique, qui atteint des valeurs de 2x1018 cm-3. Le rayon du canal est également mesuré par imagerie rapide. Les ondes de chocs créées par la décharge de surface sont visualisées en imagerie Schlieren pour plusieurs configurations de circuit. Ces ondes de chocs créent une impulsion proportionnelle à l'énergie déposée dans la décharge. Nos développons un modèle de choc pour décrire la trajectoire du choc et pour calculer l'impulsion communiquée par la décharge de surface. Le modèle est en bon accord avec les mesures expérimentales et la décharge de surface a une efficacité mécanique de 0.12mNs/J pour notre configuration d'étude. Nous terminons cette étude en comparant cet actionneur potentiel avec d'autres actionneurs courants et proposons plusieurs pistes pour de futurs travauxIn this study, we investigate the mechanical effects generated by pulsed surface discharges and their efficiency as an actuator. Using a specific electrode configuration, it is possible to create a short-lived, pulsed, rectilinear plasma channel and to heat it up rapidly (several Joules in less than a microsecond) through Joule heating. This fast energy deposition causes the formation of shock waves that can then interact with the surrounding flow.We study the electrical behavior of the pulsed surface discharge to assess the energy deposited in the plasma channel through Joule heating. To do so, we perform a parametric study on the circuit configuration and identify the main parameters driving the discharge dynamics. Several resistance models are implemented in a numerical description of the electrical circuit and their predictions of the current and deposited energy are compared with experimental measurements.Spectroscopic measurements in different circuit configurations give access to some of the plasma properties such as the electron number density that can reach values up to 2x1018 cm-3. Fast imaging also gives insight into the plasma channel radius. The shock waves generated by the pulsed surface discharge in different circuit configurations are visualized through Schlieren imaging. These shock waves generate an impulse that increases linearly with the energy deposited in the discharge. We develop a shock model to describe the shock trajectory and to compute the impulse imparted by the pulsed surface discharge. The model is in good agreement with our measurements and the pulsed surface discharge is found to have a mechanical efficiency of 0.12 mNs/J for our setup configuration. We conclude this study by comparing the proposed pulsed surface discharge actuator with other common designs and offer some directions for future studies