Dissertations / Theses on the topic 'Modelling and theoretical studies'
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Bailey, J. "Theoretical modelling studies of aggregation and molecular interactions." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596263.
Full textRabias, Ioannis. "Theoretical and computational modelling studies of conducting polymers." Thesis, University of Surrey, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310151.
Full textPukari, Merja. "Experimental and theoretical studies of nitride fuels." Doctoral thesis, KTH, Reaktorfysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-123521.
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Ahmed, Taher. "Asphalt fatigue failure analysis and modelling : experimental studies and theoretical formulation." Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3002660/.
Full textChua, Alvin J. K. "Topics in gravitational-wave astronomy : theoretical studies, source modelling and statistical methods." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/263652.
Full textDebroux, Noémie. "Mathematical modelling of image processing problems : theoretical studies and applications to joint registration and segmentation." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMIR02/document.
Full textIn this thesis, we study and jointly address several important image processing problems including registration that aims at aligning images through a deformation, image segmentation whose goal consists in finding the edges delineating the objects inside an image, and image decomposition closely related to image denoising, and attempting to partition an image into a smoother version of it named cartoon and its complementary oscillatory part called texture, with both local and nonlocal variational approaches. The first proposed model addresses the topology-preserving segmentation-guided registration problem in a variational framework. A second joint segmentation and registration model is introduced, theoretically and numerically studied, then tested on various numerical simulations. The last model presented in this work tries to answer a more specific need expressed by the CEREMA (Centre of analysis and expertise on risks, environment, mobility and planning), namely automatic crack recovery detection on bituminous surface images. Due to the image complexity, a joint fine structure decomposition and segmentation model is proposed to deal with this problem. It is then theoretically and numerically justified and validated on the provided images
Dirk-Faitakis, Christina B. "Experimental studies and theoretical modelling of an unsteady state biofilter used to treat fluctuating concentrations of an Ã-pinene air emission." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58595.pdf.
Full textBalaceanu, Alexandra. "Information Transfer and Dynamics of Nucleic Acids studied by Theoretical Approaches." Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/665158.
Full text1. Problema de exactitud del campo de fuerza La utilidad y aplicabilidad de las simulaciones de DM para modelar sistemas biomoleculares depende de su capacidad para muestrear suficientemente el espacio conformacional y la descripción correcta del potencial en términos de la forma funcional del campo de fuerza y el conjunto de parámetros. Claramente, el campo de fuerza define la forma del espacio conformacional para un conjunto dado de posiciones atómicas y también el acceso a los mínimos energéticos. Al simular sistemas en equilibrio, especialmente en sistemas bastante estables como el ADN, los campos de fuerza se esfuerzan por generar conjuntos que reproducen sistemas reales y no tiene por qué ser una gran desventaja con el poder de muestreo. En los últimos años, se ha convertido en tarea de los ingenieros informáticos y los desarrolladores de software abordar el problema de lograr escalas de tiempo largas y biológicamente relevantes. La convergencia y reproducibilidad de simulaciones de ADN atomístico con campos de fuerza de última generación, como nuestro parmbsc1, se ha demostrado de forma convincente. También parece que hasta llegar a una revolución significativa, donde los milisegundos de simulación se vuelven rutinarios, los rangos de muestreo actuales cubren por completo las estructuras internas y la dinámica de los ADN-B en esta escala de tiempo. La creciente confianza ha permitido a muchos investigadores utilizar DM para estudios muy detallados sobre la naturaleza dependiente de la secuencia de oligómeros de ADN y sobre el complejo arsenal de mecanismos que rigen su comportamiento. En cualquiera de estos estudios es necesaria una validación cuidadosa de los resultados ya que aún no está del todo claro qué tan bien y en qué grado se reproducen los efectos de secuencia en DM. El hecho de que la última generación de campos de fuerza coincida muy bien entre sí y que se ajusten a los escasos datos experimentales es seguramente muy alentador, pero pasará algún tiempo hasta que se puedan validar pequeñas diferencias en las geometrías de las secuencias. Nuestra propia validación extensiva del campo de fuerza parmbsc1, así como una gran cantidad de otros trabajos que, desde su publicación, se han establecido específicamente para evaluar su rendimiento, o simplemente lo han aplicado con éxito, hablan de una parametrización muy estable capaz de tratar con una amplia gama de ADN. Vale la pena mencionar que en condiciones especiales podrían ser necesarias pequeñas mejoras, lo que podría lograrse con la inclusión de términos de polarización. Sin embargo, hasta la fecha, ningún campo de fuerza ha sido capaz de modelar la polarización sin desestabilizar finalmente el sistema y esto a un costo enorme (un factor de 10) a la velocidad de cálculo. En resumen, con base en el notable desempeño de parmbsc1, nosotros y otros grupos podemos emplearlo con confianza en el estudio detallado de la dinámica del ADN y esperamos que el número de resultados de soporte solo aumente. 2. Dependencia de la secuencia y polimorfismos del ADN-B. Entonces, ¿qué es lo que realmente aprendemos al analizar la variabilidad de conformación del ADN sobre su espacio de secuencia a nivel de los tetrámeros? Está bien establecido que diferentes bps tienen diferentes preferencias con respecto a sus geometrías internas, y hasta cierto punto, el conjunto de reglas heurísticas de Calladine es capaz de dar sentido a estas diferencias. A nivel de bps, algunas secuencias son extremadamente estables, como ApT, y algunas secuencias, como CpG, tienen un equilibrio biestable y convierten entre diferentes disposiciones de sus geometrías internas. Hay casos en que esta frustración puede explicarse por la distribución de cargas, el volumen o la fuerza de sus interacciones de apilamiento y los puentes de hidrógeno, pero en muchos casos requiere una visión más integral, teniendo en cuenta los efectos de secuencia de más alto nivel. En simulaciones de DM de multi-microsegundos, los parámetros de pares intra-base son siempre unimodales ya que los estados alternativos a los que se puede acceder a través de la apertura de la base no se muestrean en esta escala de tiempo. Sin embargo, sus promedios de conjunto muestran diferencias considerables de acuerdo con el cambio en la secuencia. Los parámetros de pares de bases pueden ser bimodales, pero solo en ciertas combinaciones de tetranulceótidos que constituyen aproximadamente el 5% de los casos. Esto puede explicarse teniendo en cuenta que el bps central de una combinación particular de cuatro nucleótidos tiene una preferencia estructural que está en conflicto con la de sus pasos vecinos. Con el fin de minimizar el costo de energía y satisfacer de la mejor manera posible todos los requisitos conformacionales, un bps más flexible poblará varios estados, generalmente un máximo de dos. La optimización de las geometrías entre varios bps generalmente implica reorganizaciones de la red troncal, con el azúcar fosfato actuando como una bisagra que permite la coordinación consecutiva de bps en una coreografía compleja que a menudo involucra otros factores, tales como cambios sutiles en el entorno del solvente. En los ADN-B, la transición principal más importante es BI/BII, que se puede relacionar con la química a través de la fuerza relativa dependiente de la secuencia de puentes de hidrógeno no convencionales que estabilizan las conformaciones BII. En un modelo de tetrámero de ADN-B, las transiciones de la cadena principal de diferentes tetrámeros se traducen en movimientos a lo largo de diferentes grados internos de libertad, dependiendo de la secuencia. Por lo tanto, ahora podemos construir una imagen del espacio conformacional interconectado del ADN como una superposición de secuencias de tetranucleótidos con descriptores estructurales transferibles. Todavía es una cuestión de especulación cómo estas propiedades podrían ser explotadas por proteínas y otras moléculas que se unen al ADN para diferentes funciones biológicas. 3. Transferencia de información a través del ADN. Sin embargo, hay algunos casos especiales en los que el modelo de tetrámero no parece ser suficiente. El CTAG es uno de esos casos que demuestra que, para un tetrámero altamente flexible y polimórfico, la composición de la secuencia de largo alcance puede tener un efecto notable sobre las propiedades estructurales del bps central. Analizar el mecanismo detrás de esta comunicación de largo alcance a través del ADN ha significado más que nada una oportunidad para comprender los raros eventos de modulación de secuencia que podrían ser mucho más generales en casos de distorsiones mayores e inducidas en la hélice. En CTAG pudimos observar la influencia de la secuencia no solo desde el nivel del hexámero, sino incluso más allá, y los datos apuntan a un complejo mecanismo de transferencia de información a través del ADN mediante movimientos coordinados de la cadena principal. En la realización de la función biológica, el ADN a menudo se considera erróneamente como un retículo inerte sobre el cual las proteínas se ensamblan para replicar o transcribir genes. Sin embargo, los experimentos demuestran que la transferencia de información en el ADN puede ocurrir incluso a largas distancias y puede producir efectos alostéricos sobre la unión al ligando. Sin lugar a duda, la unión de proteínas o moléculas pequeñas al ADN puede producir cambios conformacionales acoplados que pueden afectar a un sitio de unión vecino y aumentar su afinidad por la proteína de unión secundaria. Tales cambios no necesitan alterar los promedios del conjunto y solo potencian modificaciones en la forma del pozo de energía en el sitio de unión secundario. Como se ve a partir de la información dinámica proporcionada por una trayectoria de DM, tal vez en más de un caso de parejas de proteínas, el ADN actúa como un cable que transmite pulsos de información originados en el sitio primario de unión que viajan a regiones distantes. Mostramos que los métodos de DM pueden proporcionar explicaciones razonables para los fenómenos de unión cooperativa en el ADN y abren por primera vez la posibilidad de la "alostería sin cambio conformacional" en el reclutamiento de proteínas al ADN. Desde un punto de vista termodinámico, este tipo de enlace cooperativo parece estar impulsado por la entropía. Por lo tanto, el primer evento vinculante congela algunos de los grados de libertad alrededor de su propia región de unión, pero también reduce el costo de entropía asociado al segundo enlace.
Haimad, N. "A theoretical and experimental investigation of the flow performance of automotive catalytic converters." Thesis, Coventry University, 1997. http://curve.coventry.ac.uk/open/items/3f51aa95-571c-73d5-bee3-4b523cab0a1c/1.
Full textKarlsson, Rasmus. "Theoretical and Experimental Studies of Electrode and Electrolyte Processes in Industrial Electrosynthesis." Doctoral thesis, KTH, Tillämpad elektrokemi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-177025.
Full textHeterogen elektrokatalys innebär användningen av fasta material för att minska energimängden som krävs för produktion av kemikalier med hjälp av elektricitet. Heterogen elektrokatalys har en central roll i det moderna samhället, eftersom det möjliggör produktionen av kemikalier såsom klorgas och natriumklorat, som i sin tur används för produktion av t ex konstruktionsmaterial och läkemedel. Vikten av användning av elektrokatalys för produktion av förnybara bränslen, såsom vätgas, växer dessutom i takt med att en övergång till användning av förnybar energi blir allt nödvändigare. I denna avhandling presenteras arbete som utförts för att förstå och förbättra sådana elektrokatalysatorer. En stor del av arbetet har varit fokuserat på selektiviteten mellan klorgas och biprodukten syrgas i klor-alkali och kloratprocesserna. Inom ramen för detta arbete har teoretisk modellering av det dominerande anodmaterialet i dessa industriella processer, den så kallade “dimensionsstabila anoden” (DSA), använts för att föreslå en fundamental anledning till att detta material är speciellt klorselektivt. Vi föreslår att klorselektiviteten kan förklaras av en laddningsöverföring från ruteniumkatjoner i materialet till titankatjonerna i anodytan, vilket aktiverar titankatjonerna. Baserat på en bred studie av ett stort antal andra dopämnen föreslår vi dessutom vilka dopämnen som är bäst lämpade för produktion av aktiva och klorselektiva anoder. Med hjälp av experimentella studier föreslår vi dessutom en koppling mellan kloratbildning och oönskad syrgasbildning i kloratprocessen, och vidare har en bred studie av tänkbara elektrolytföroreningar utförts för att öka förståelsen för syrgasbildningen i denna process. Två studier relaterade till elektrokemisk vätgasproduktion har också gjorts. En experimentell studie av Co-dopad DSA har utförts, och detta elektrodmaterial visade sig vara mer aktivt för vätgasutveckling än en standard-DSA. Vidare har en kombination av experimentell och teoretisk röntgenfotoelektronspektroskopi använts för att öka förståelsen för strukturella förändringar som sker i RuO2 och i det ädelmetallfria elektrodmaterialet MoS2 under vätgasutveckling.
QC 20151119
Fakier, Saajidah. "The effect of inositol-hexakisphosphate (phytate) on urinary risk factors for calcium oxalate urolithiasis in South African population groups with different kidney stone risk profiles : theoretical modelling, in vitro crystallisation experiments and in vivo human studies." Doctoral thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/19975.
Full textO'Donnell, Catherine Lorraine. "Theoretical studies of spin studies." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358639.
Full textIzsak, Robert. "Theoretical modelling of hydrogen transfer reactions." Thesis, Cardiff University, 2010. http://orca.cf.ac.uk/54119/.
Full textXu, Dapeng. "Essays on theoretical credit risk modelling." Thesis, University of Strathclyde, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275173.
Full textHuang, Zhenyu. "Theoretical modelling of railway curve squeal." Thesis, University of Southampton, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442861.
Full textLooney, Padraig. "Theoretical modelling of ultrasound contrast agents." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5921.
Full textStiffell, Peter Barry. "Theoretical modelling of quantum circuit systems." Thesis, University of Sussex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249403.
Full textCarter, Faith. "Theoretical modelling of the sulcated spring." Thesis, Aston University, 1994. http://publications.aston.ac.uk/15291/.
Full textRickard, Gail. "Theoretical modelling of formyl halide hydrolysis." Thesis, University of Bath, 2001. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340930.
Full textAyis, Salma Ahmed. "Modelling unobserved heterogeneity : theoretical and practical aspects." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261592.
Full textLovas, Stéphanie. "Theoretical modelling of two wave-power devices." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/57988.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (p. 161-163).
Many wave energy devices are currently studied. In this thesis we focus on two specific devices: the Oscillating Water Column (OWC), and the buoys. In the first part of this thesis we examine the effects of coastline geometry on the performance of an OWC. Under the assumption of inviscid irrotationnal flow, we develop a linear theory for the velocity potential for the case of a coastline of arbitrary apex angle. Scattering and radiation problems are solved separately using eigenfunctions expansions, and are then combined to study the energy extraction rate. Numerical simulations for a convex and a concave corner are considered and comparison with an OWC at the tip of a thin breakwater and on a straight coast are discussed. Assuming that the multiple-turbine system can be controlled over a wide range of frequencies, we study the effects of fixed chamber size and air compressibility on the optimal power extraction. A simpler way of optimization is then develop and we show that this simpler scheme can achieve almost as high an efficiency as the idealized many-frequency optimization. In the second part of this thesis, we first model theoretically an array of cylinders and then apply the theory developped to an array of buoys. However, numerical difficulties encountered for the array of cylinders have led to the conclusion that the theory developed is numerically inefficient, although it is accurate.
by Stéphanie Lovas.
S.M.
Kohler, Iris. "Graph Theoretical Modelling of Electrical Distribution Grids." DigitalCommons@CalPoly, 2021. https://digitalcommons.calpoly.edu/theses/2301.
Full textForcinito, Mario Alberto. "Theoretical considerations on the modelling of skeletal muscle." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0022/NQ31023.pdf.
Full textHo, Tsz Hang Emily Ting. "Theoretical and computation modelling of polymer seal life." Thesis, Cranfield University, 1993. http://dspace.lib.cranfield.ac.uk/handle/1826/4665.
Full textKebadze, Elizbar. "Theoretical modelling of unbonded flexible pipe cross-sections." Thesis, London South Bank University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326762.
Full textBlasciuc-Dimitriu, Cezar. "Theoretical modelling of Schottky barrier diodes in SiC." Thesis, University of Newcastle Upon Tyne, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405314.
Full textMear-Stone, Leah Isobel. "Theoretical modelling of flow in rotor-stator systems." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.681054.
Full textMaddison, Louise. "Experimental and theoretical modelling of the MAPK pathway." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/experimental-and-theoretical-modelling-of-the-mapk-pathway(46773da5-85dd-4a3f-8e6c-e3559ba04f46).html.
Full textJoarder, Parthasarathi. "Theoretical modelling of global oscillations in solar prominences." Thesis, University of St Andrews, 1994. http://hdl.handle.net/10023/14169.
Full textLinney, Lynda. "Theoretical modelling of transition states for asymmetric processes." Thesis, University of Bath, 1995. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296296.
Full textRuggiero, Guiseppe D. "Theoretical modelling of organic reaction mechanisms in solution." Thesis, University of Bath, 1999. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301536.
Full textGrønsleth, Martin Sigurd. "Theoretical Studies of Unconventional Superconductors." Doctoral thesis, Norwegian University of Science and Technology, Department of Physics, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2174.
Full textThis thesis presents four research papers. In the first three papers we have derived analytical results for the transport properties in unconventional superconductors and ferromagnetic systems with multiple broken symmetries. In Paper I and parts of Paper II we have studied tunneling transport between two non-unitary ferromagnetic spin-triplet superconductors, and found a novel interplay between ferromagnetism and superconductivity manifested in the Josephson effect as a spin- and charge-current in the absence of an applied voltage across the junction. The critical amplitudes of these currents can be adjusted by the relative magnetization direction on each side of the junction. Furthermore, in Paper II, we have found a way of controlling a spin-current between two ferromagnets with spin-orbit coupling. Paper III considers a junction consisting of a ferromagnet and a non-unitary ferromagnetic superconductor, and we show that the conductance spectra contains detailed information about the superconducting gaps and pairing symmetry of the Cooper-pairs.
In the last paper we present a Monte Carlo study of an effective Hamiltonian describing orbital currents in the CuO2 layers of high-temperature superconductive cuprates. The model features two intrinsically anisotropic Ising models, coupled through an anisotropic next-nearest neighbor interaction, and an Ashkin–Teller nearest neighbor fourth order coupling. We have studied the specific heat anomaly, as well as the anomaly in the staggered magnetization associated with the orbital currents and its susceptibility. We have found that in a limited parameter regime, the specific heat anomaly is substantially suppressed, while the susceptibility has a non-analytical peak across the order-disorder transition. The model is therefore a candidate for describing the breakup of hidden order when crossing the pseudo-gap line on the under-doped side in the phase diagram of high-temperature superconductors.
Wei, Yin. "Theoretical Studies in Nucleophilic Organocatalysis." Diss., lmu, 2009. http://nbn-resolving.de/urn:nbn:de:bvb:19-95248.
Full textMohammed, Abdelsalam. "Theoretical Studies of Raman Scattering." Doctoral thesis, KTH, Teoretisk kemi (stängd 20110512), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-28332.
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Blackmore, Robert Sidney. "Theoretical studies in stochastic processes." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25554.
Full textScience, Faculty of
Chemistry, Department of
Graduate
Mitchell, John Blayney Owen. "Theoretical studies of hydrogen bonding." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358697.
Full textFisher, Andrew James. "Theoretical studies of point defects." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252958.
Full textHaller, Lars Jonas Larsson. "Theoretical studies of actinyl bonding." Thesis, University College London (University of London), 2008. http://discovery.ucl.ac.uk/1444217/.
Full textWatmough, Mark Harold. "Theoretical studies in magnetic separation." Thesis, University of Salford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491799.
Full textLin, Zhenyang. "Theoretical studies on cluster compounds." Thesis, University of Oxford, 1989. http://ora.ox.ac.uk/objects/uuid:4afef76e-df5f-4357-9072-f20cb5a3b5d8.
Full text莫錦華 and Kam-wah Mok. "Theoretical studies of diatomic molecules." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31234380.
Full textYang, Jianji. "Theoretical Studies of Optical Metamaterials." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00737379.
Full textKedney, P. J. "Theoretical studies of liquid crystals." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283407.
Full textSimmonds, Paul Stuart John. "Theoretical studies of anisotropic fluids." Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314781.
Full textEdge, Colin Michael. "Theoretical studies of enzyme inhibition." Thesis, University of St Andrews, 1989. http://hdl.handle.net/10023/14388.
Full textBoucher, Benoît. "Theoretical Studies of Thermoelectric Materials." Rennes, Ecole nationale supérieure de chimie, 2017. http://www.theses.fr/2017ENCR0040.
Full textIn the context of worldwide energetic transition, thermoelectricitycan significantly play a part among the new sources of renewableenergy that can be used at different scales and applied to severaldomains, from houses to cars, from air-conditioning to electricityproduction. In order to develop the use of thermoelectricity, thereis a need to better understand the chemical interactions thatgovern these materials and identify new thermoelectric materials. Hence, atomic modeling can help in understanding the structuraland physical properties of these materials as well as theirtransport properties, and suggest new candidates with interestingproperties. With this aim, this thesis work is based on the use ofquantum chemical tools. The first chapter of this manuscript deals with the quantumchemistry methods used. The second chapter reminds somebasics of thermoelectricity and the main class of thermoelectricmaterials. The third chapter focuses on the topological analysis ofthe electronic density of compounds with general formula TM3with T = transition metal of Group-7 to 9 and M = Ga, In, in orderto better understand on one hand the chemical bonding in thethese materials, and on the other hand the semi-conductingproperties of some of them that exhibit thermoelectric properties. The next chapter deals with the structural and transportproperties of some hypothetical materials of general formula TM3,(T = group-6 transition metal, M = Ga, In). Our calculationssuggest an exceptional thermoelectric potential for WGa3. The last two chapters are devoted to molybdenum cluster-basedcompounds. The penultimate part tackles the modeling of thetransport properties of AgxMo9Se11 (3. 4 ≤ x ≤ 3. 9), Ag2Tl2Mo9Se11and Ag3In2Mo9Se11 that contain bi-octahedral Mo9 clusters. Aspecial attention has been paid to the influence of the structuraland computational details. In the last part, we used the resultsobtained for Mo9-based selenides to predict the transportproperties of few molybdenum cluster compounds
Mok, Kam-wah. "Theoretical studies of diatomic molecules /." Hong Kong : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19671969.
Full textKahraman, Osman. "Theoretical studies of constrained membranes." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0109/document.
Full textThe present thesis is devoted to the study of constrained membranes with a focus on biological structures such as growing tissues and the cell membrane. It combines analytical and numerical approaches to investigate the interplay of geometry and mechanics. It also includes some experimental results albeit they are few in number and modest in size. After an introductory chapter, we explore three physical models addressed in three distinct chapters. In the first model, the deformations of growing soft tissues are treated as Gaussian point singularities in two dimensional surfaces. The equilibrium shapes are evaluated for two such defects forming a dipole. The predictions of the theory are also compared to tabletop experiments. The next chapter studies the invaginations of self-avoiding fluid membranes in constrained spaces. To this end, we developed a Finite Element code and performed extensive simulations to construct a geometric phase diagram for a fluid membrane vesicle in a spherical confinement. We also investigate the effects of the membrane's spontaneous curvature and the deformations of the container on the geometry of the invagination. In the fourth chapter of the manuscript, a tubular membrane composed of switchable components is proposed as a model to study conformations of intrinsically curved biological rods. We translated this system to a computational framework based on the Brownian Dynamics method and inquired how global shape emerges from local interactions
Royo, Valls Miquel. "Theoretical modelling of electrons and holes in semiconductor nanostructures." Doctoral thesis, Universitat Jaume I, 2010. http://hdl.handle.net/10803/669140.
Full textTakács, Peter F. "Deformations in Concrete Cantilever Bridges : Observations and Theoretical Modelling." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-112.
Full textThe thesis deals with the deformation problem of segmental, cast-in-place concrete cantilever bridges. This type of bridge has shown some propensity to develop larger deflections than those were predicted in the design calculation. Excessive deflections may lead to deterioration of aesthetics, serviceability problems and eventually early reconstruction of the bridge. Also in the construction stages the deflections have to be properly compensated to achieve the smooth camber in the completed bridge deck.
Deformation prediction in concrete cantilever bridges is not as reliable as it would be necessary due to several factors. The high degree of uncertainty in creep and shrinkage prediction in concrete constitutes the major difficulty. Other factors are the complex segmental construction procedure and the sensitivity of the deformations to variations in the construction schedule, the uncertainty in estimating the frictional loss of prestress and relaxation in the prestressing tendons and uncertainty in estimating model parameters such as temperature and relative humidity.
The doctoral study was initiated with the objective to improve deformation prediction in segmentally cast concrete cantilever bridges and to establish guidelines for deformation analysis based on advanced numerical methods.
A database on observed deformations in three modern long span concrete cantilever bridges in Norway has been established. Two of the bridges were partly constructed from lightweight aggregate concrete. The deformations have been monitored since the construction stages up to the present time. The measurements cover the construction stages and the service life of 14, 8 and 3 years, respectively for the three bridges. The measured deformations are deflections in the superstructure and in one of the bridges, also strain measurements in the piers and the superstructure.
A sophisticated numerical model was created for deformation analysis. The numerical model realistically simulates the segmental construction procedure and the entire life span of the bridge. The effects of the segmental construction method, temporarily supports and constraints and changes in the structure system during construction are taken into account. The model considers the different concrete age from segment to segment, the sequential application of permanent loads and prestressing and the effect of temporary loads. The prestressing tendons are individually modelled with their true profile taking into account the variation of the effective prestressing force along the length of the tendon and with time.
The finite element model consists of beam elements which are based on an advanced beam element formulation. The beam model was verified against a robust two-and-a-half dimensional shell model concerning its general performance and some specific issues. The comparison confirmed the accuracy of the beam model. Existing experimental data on creep and shrinkage in lightweight aggregate concrete and high strength concrete were evaluated in comparison with theoretical models. The main focus was on the CEB-FIP Model Code 1990 and its subsequent extensions. The findings were considered in the numerical studies.
Deformations of the three bridges were computed. The CEB-FIP Model Code 1990 material model was used for concrete for the most part. The elastic moduli were taken from test results where they were available. The creep coefficient and the shrinkage strain of the lightweight aggregate concrete were assumed equal to those of normal density concrete of the same strength. The agreement between the calculated and the measured deformations were satisfactory in view of the large uncertainty involved in theoretical prediction. While moderate differences were observed in most cases, no clear overall tendency toward underor overestimation was found. In subsequent numerical studies, the sensitivity of the deformations to variations in various model parameters was investigated. The B3 model was compared to the CEB-FIP Model Code 1990 in the analysis of one of the bridges, where the latter model showed somewhat better agreement with the measurements.
The last part of the work concerned a robust probabilistic analysis which was based on a Monte Carlo simulation. The objective of the probabilistic analysis was to estimate the statistical properties of the deformation responses. With the distribution function of a given deformation response being known, the confidence limit for the deformation can be determined. It is recommended to design the bridge for the long-time deflection which represents a certain confidence limit (e.g. the 95 % confidence limit) of the response rather than its mean. Such way the risk that the bridge will suffer intolerable deflection over its life span can be minimised.