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On Bezier surfaces in three-dimensional Minkowski spaceUgail, Hassan, Marquez, M.C., Yilmaz, A. January 2011 (has links)
No / In this paper, we study Bézier surfaces in View the MathML source three-dimensional Minkowski space. In particular, we focus on timelike and spacelike cases for Bézier surfaces. We also deal with the Plateau¿Bézier problem in View the MathML source, obtaining conditions over the control net to be extremal of the Dirichlet function for both timelike and spacelike Bézier surfaces. Moreover, we provide interesting examples showing the behavior of the Plateau¿Bézier problem in View the MathML source and illustrating the relationship between it and the corresponding Plateau¿Bézier problem in the Euclidean space R3.
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On unicity problems of meromorphic mappings of Cn into PN(C) and the ramification of the Gauss maps of complete minimal surfaces / Problèmes d'unicité pour des applications méromorphes de Cn dans CPN et ramification de l'application de Gauss pour des surfaces minimales complètesHa, Pham Hoang 03 May 2013 (has links)
En 1975 H. Fujimoto a généralisé les résultats d’unicité pour des fonctions holomorphes dus à Nevanlinna pour des applications méromorphes de Cn dans CPN. Il a démontré que pour deux applications méromorphes non linéairement dégénérées f et g de Cn dans CPN, si elles ont les mêmes images réciproques, comptées avec leurs multiplicités, par rapport à (3N + 2) hyperplans de CPN en position générale, alors f g. Depuis, ce problème a été étudié d’une manière intensive par H. Fujimoto, W. Stoll, L. Smiley, M. Ru, G. Dethloff-T.V.Tan, D.D.Thai-S.D.Quang, Chen-Yan et d’autres auteurs. En parallèle avec le développement de la théorie de Nevanlinna, la théorie de distribution des valeurs de l’application de Gauss des surfaces minimales dans Rm a été étudiée d’une manière intensive par R.Osserman, S.S. Chern, F. Xavier, H. Fujimoto, S.J. Kao, M. Ru et d’autres auteurs. Dans cette thèse, nous avons continué d’étudier ces problèmes. Nous avons obtenu les résultats principaux suivants: +) Théorèmes d’unicité avec multiplicités tronquées des applications méromorphes de Cn dans CPN ayant les mêmes images réciproques par rapport è (2N + 2) hyperplans de CPN. +) Théorèmes d’unicité avec multiplicités tronquées des applications méromorphes de Cn dans CPN ayant des cibles mobiles et un ensemble d’identité petit. +) Théorèmes d’unicité avec multiplicités tronquées des applications méromorphes de Cn dans CPN ayant des cibles fixes ou mobiles et satisfaisant des conditions sur les dérivées. +) Théorèmes de ramification de l’application de Gauss de certaines classes de surfaces minimales complètes dans Rm (m = 3,4). / In 1975, H. Fujimoto generalized Nevanlinna’s known results for meromorphic fonctions to the case of meromorphic mappings of Cn into PN(C). He proved that for two linearly nondegenerate meromorphic mappings f and g of C into PN(C). if they have the saine inverse images counted with multiplicities for 3N + 2 hyperplanes in general position in PN(C) then f = g. After that, this problem has been studied intensively by a number of mathematicans as H. Fujimoto, W. Stoll, L. Smiley, M. Ru, G. Dethloff - T. V. Tan, D. D. Thai - S. D. Quang, Chen-Yan and so on. Parallel to the development of Nevanlinna theory, the value distribution theory of the Gauss map of minimal surfaces immersed in Rm vas studied by many mathematicans as R. Osserman, S.S. Chern, F. Xavier, H. Fujimoto, S. J. Kao, M. Ru and many other mathematicans. In this thesis, we continuous studing some problems on these directions. The main goals of the thesis are followings. • Unicity theorems with truncated multiplicities of meromorphic mappings of Cn into PN(C) sharing 2N + 2 fixed hyperplanes.• Unicity theorems with truncated multiplicities of meromorphic mappings of Cn into PN(C) for moving targets, and a small set of identity.
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On unicity problems of meromorphic mappings of Cn into PN(C) and the ramification of the Gauss maps of complete minimal surfacesHa, Pham Hoang 03 May 2013 (has links) (PDF)
In 1975, H. Fujimoto generalized Nevanlinna's known results for meromorphic fonctions to the case of meromorphic mappings of Cn into PN(C). He proved that for two linearly nondegenerate meromorphic mappings f and g of C into PN(C). if they have the saine inverse images counted with multiplicities for 3N + 2 hyperplanes in general position in PN(C) then f = g. After that, this problem has been studied intensively by a number of mathematicans as H. Fujimoto, W. Stoll, L. Smiley, M. Ru, G. Dethloff - T. V. Tan, D. D. Thai - S. D. Quang, Chen-Yan and so on. Parallel to the development of Nevanlinna theory, the value distribution theory of the Gauss map of minimal surfaces immersed in Rm vas studied by many mathematicans as R. Osserman, S.S. Chern, F. Xavier, H. Fujimoto, S. J. Kao, M. Ru and many other mathematicans. In this thesis, we continuous studing some problems on these directions. The main goals of the thesis are followings. * Unicity theorems with truncated multiplicities of meromorphic mappings of Cn into PN(C) sharing 2N + 2 fixed hyperplanes.* Unicity theorems with truncated multiplicities of meromorphic mappings of Cn into PN(C) for moving targets, and a small set of identity.
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Entanglement, boundaries and holography / Intrication, bords et holographieBerthiere, Clément 20 December 2017 (has links)
La notion d’entropie d’intrication a eu un profond impact sur la physique théorique, particulièrement depuis ces dix dernières années. D’abord introduite afin expliquer l’entropie des trous noirs, son champ d’application s’est par la suite ouvert à une grande variété de domaines de recherche, de la matière condensée à la gravitation quantique, de l’information quantique à la théorie quantique des champs. Dans ce contexte scientifique effervescent, l’entropie d’intrication apparait comme un outil central et doit donc intensivement être étudiée. A l’origine de cette thèse se trouve le désir de mieux comprendre cette entropie. D’intéressants développements concernant les effets de bord sur l’entropie d’intrication ont vu le jour récemment. Nous proposons donc d’explorer comment le bord d’un espace affecte l’entropie, en particulier dans la situation où la surface d’intrication intersecte ce bord. Nous présentons des calculs explicites de l’entropie d’intrication en espace plat avec bords. Nous montrons que des termes induits par ces bords apparaissent dans l’entropie et nous soulignons le rôle prépondérant que jouent les conditions aux bords. Nous étudions ensuite la contribution de bord dans le terme logarithmique de l’entropie d’intrication en dimensions trois et quatre. Nous calculons en premier lieu ce terme en théorie des champs pour la théorie N = 4 de Yang-Mills, puis nous répétons ce calcul de manière holographique. Nous montrons que ces deux méthodes de calcul donnent le même résultat, si du côté théorie des champs les conditions aux bords préservent la moitié de la supersymétrie et que du côté gravité l’extension du bord dans le bulk est une surface minimale. / The entanglement entropy has had a tremendous and profound impact on theoretical physics, particularly since the last decade. First introduced in an attempt to explain black holes entropy, it has then found applications in a wide range of research areas, from condensed matter physics to quantum gravity, from quantum information to quantum field theory. In this exciting scientific context, the entanglement entropy has thus emerged as a useful and pivotal tool, and as such justifies the need to be intensively studied. At the heart of this thesis therefore lies the desire to better understand the entanglement entropy. Interesting developments during the recent years concern the boundary effects on the entanglement entropy. This dissertation proposes to explore the question of how the presence of spacetime boundaries affects the entropy, specifically in situations where the entangling surface intersects these boundaries. We present explicit calculations of entanglement entropy in flat spacetime with plane boundaries. We show that boundary induced terms appear in the entropy and we emphasize the prominent role of the boundary conditions. We then study the boundary contribution to the logarithmic term in the entanglement entropy in three and four dimensions. We perform the field theoretic computation of this boundary term for the free N = 4 super-gauge multiplet and then repeat the same calculation holographically. We show that these two calculations are in agreement provided that on the field theory side one chooses the boundary conditions which preserve half of the full supersymmetry and that on the gravity side the extension of the boundary in the bulk is minimal.
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Eliptické rovnice v nereflexivních prostorech funkcí / Eliptické rovnice v nereflexivních prostorech funkcíMaringová, Erika January 2015 (has links)
In the work we modify the well-known minimal surface problem to a very special form, where the exponent two is replaced by a general positive parameter. To the modified problem we define four notions of solution in nonreflexive Sobolev space and in the space of functions of bounded variation. We examine the relationships between these notions to show that some of them are equivalent and some are weaker. After that we look for assumptions needed to prove the existence of solution to the problem in the sense of definitions provided. We outline that in the setting of spaces of functions of bounded variation the solution exists for any positive finite parameter and that if we accept some restrictions on the parameter then the solution exists in the Sobolev space, too. We also provide counterexample indicating that if the domain is non-convex, the solution in Sobolev space need not exist. Powered by TCPDF (www.tcpdf.org)
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Superfícies Invariantes no Espaço Homogêneo Sol com Curvatura Constante.Neto., Guilherme Luiz de Oliveira 27 July 2012 (has links)
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Previous issue date: 2012-07-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this paper we studied surfaces with constant mean curvature and surfaces with
constant Gaussian curvature in the Sol space which are invariant under the action of
two one-parameter subgroups of isometries of the ambient space. Furthermore, we
classify the surfaces that satisfy a relationship of type k1 = mk2, where k1 and k2 are
the principal curvatures of the surface and m ∈ R. / O presente trabalho aborda um estudo das superfícies com curvatura média constante
e das superfícies com curvatura Gaussiana constante no espaço Sol que são
invariantes sob a ação de dois grupos a 1-parâmetro de isometrias do espaço ambiente.
Além disso, classificamos as superfícies que satisfazem uma relação do tipo
k1 = mk2, onde k1 e k2 são as curvaturas principais da superfície e m ∈ R.
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Superfícies mínimas de fronteira livre na bola tridimensional / Free Boundary minimal surfaces in the unit 3-ballSantos, Thaynara Cecilia 11 May 2018 (has links)
In this dissertation, we study a characterization of the flat equatorial disk and the critical catenoid in the unitary ball B3 of R3 in terms of its second fundamental form. The work developed here is based on the article “A gap theorem for free boundary minimal surfaces in the three-ball” by Lucas Ambrozio and Ivaldo Nunes. / Nesta dissertação, estudamos uma caracterização do disco equatorial plano e do catenóide crítico na bola unitária B3 do R3 em termos da sua segunda forma fundamental. O trabalho aqui desenvolvido baseia-se no artigo “A gap theorem for free boundary minimal surfaces in the three-ball” de Lucas Ambrozio e Ivaldo Nunes.
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Artificial biomineralisation and metallic soapsCorkery, Robert, robert.corkery@anu.edu.au January 1998 (has links)
In this thesis, geometry is used as a basis for conducting experiments aimed at growing
and arranging inorganic minerals on curved interfaces. Mineralisation is directed using
crystalline and liquid-crystalline metallic soaps and surfactant/water systems as
templates.¶
A review of the history, syntheses, structure and liquid crystallinity of metallic soaps
and other amphiphiles is presented as a foundation to understanding the interfacial
architectures in mesostructured template systems in general.¶
In this study, a range of metallic soaps of varying chain length and cation type are
synthesised and characterised to find potentially useful templates for mineral growth.
These include alkaline-earth, transition metal, heavy metal and lanthanide soaps. These
are systematically characterised using a variety of analytical techniques, including
chemical analyses, x-ray diffraction (XRD) infrared spectroscopy (IR) and differential
scanning calorimetry (DSC). Their molecular and crystal structures are studied using
transmission electron microscopy (TEM), cryo-TEM, electron diffraction (ED), electron
paramagnetic spin resonance (EPR), absorption spectroscopy (UV-VIS), high resolution
laser spectroscopy, atomic force microscopy (AFM), nuclear magnetic resonance
spectroscopy, scanning electron microscopy (SEM), electron dispersive x-ray analysis
(EDXA), thermal gravimetric analysis (TGA) and magnetic measurements. Models for
the molecular and crystal structures of metallic soaps are proposed. The soaps are
predominantly lamellar crystalline or liquid crystalline lamellar rotor phases with tilted
and/or untilted molecular constituents. These display evidence of varying degrees of
headgroup organisation, including superstructuring and polymerisation. A single crystal
structure is presented for a complex of pyridine with cobalt soap. Simple models for
their structure are discussed in terms of their swelling properties in water and oils.
Experiments are also presented to demonstrate the sorbent properties of aluminium
soaps on oil spills.¶
The thermotropic liquid crystallinity of alkaline earth, transition metal, heavy metal and
lanthanide soaps is investigated in detail. This is done to assess their suitability as
templates, and to document their novel thermotropic behaviour, particularly the
relatively unknown lanthanide soaps. Liquid crystalline behaviours are studied using
high-temperature XRD (HTXRD), hot-stage optical microscopy and DSC. Models for a
liquid crystalline phase progression from crystals to anisotropic liquids are discussed in
terms of theories of self-assembly and interfacial curvature. The terminology required
for this is drawn from various nomenclature systems for amphiphilic crystals and liquid
crystals. General agreement with previous studies is reported for known soaps, while
liquid crystallinity is demonstrated in the lanthanide and some non-lanthanide soaps for
the first time. A general phase progression of crystalline lamellar through liquid
crystalline lamellar to non-lamellar liquid crystalline is discussed in terms of models
concerned with the molecular and crystal structures of the soaps and their phase
transitions via headgroup and chain re-arrangements.¶
Experiments aimed at guiding growth of metal sulfides using metallic soaps as
templates are described, and a model for this growth is discussed. Metal sulfides have
been successfully grown by reacting crystalline and liquid crystalline transition metal
and heavy metal soaps with H2S gas at room temperature and at elevated temperature.
These have been characterised using XRD, TEM, ED and IR. Sulfide growth is
demonstrated to be restricted and guided by the reacting soap template architecture.
Zinc, cadmium, indium and lead soaps formed confined nanoparticles within the matrix
of their reacting soap template. In contrast, curved and flat sheet-like structures, some
resembling sponges were found in the products of sulfided iron, cobalt, nickel, copper,
tin and bismuth soaps. A model to explain this behaviour is developed in terms of the
crystal and liquid crystal structures of the soaps and the crystal structures of the metal
sulfide particles.¶
Liquid crystalline iron soaps have been subjected to controlled thermal degradation
yielding magnetic iron oxide nanoparticles. Some XRD and TEM evidence has been
found for formation of magnetic mesostructures in heat-treated iron soaps. Models for
the molecular and liquid crystalline structure of iron soaps, their thermotropic phase
progression and eventual conversion to these magnetic products are discussed.
Systematic syntheses of mesoporous silicates from sheeted clays are discussed.¶The
templates that have been used are cationic surfactants and small, organic molecular
salts. Experiments are reported where a cooperative self-assembly of
surfactant/water/kanemite plus or minus salt and oils yields 'folded sheet materials'
(FSM'S). Templating of kanemite has also been achieved using cobalt cage surfactants.
A theoretical prediction of the specific surface areas and specific volumes of
homologous sets of FSM's gave excellent agreement with measured values. The
geometry and topology of the mesostructures are discussed. A theoretical model is also
discussed regarding the curvature found in the sheets of natural clays , and results of
templating clays and silica using metallic soaps are presented. Experiments and a model for low temperature nucleation and growth of microporous silicalite-1 are described in
terms of silica templating by water clathrates.¶
Finally, the problem of finding minimal surface descriptions of crystal networks is
addressed. Combinatoric methods are used to disprove the existence of possible
embeddings of type I and II clathrate networks in non-self intersecting periodic minimal
surfaces. The crystal network of the clathrate silicate, melanophlogite is successfully
embedded in the WI-10 self-intersecting surface. Details of a previously unreported,
genus-25 periodic surface with symmetry Im3m are discussed.
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Analysis of osteoporosis effect on the mechanical behaviour and morphometry of human cancellous boneMegías Díaz, Raquel 18 July 2024 (has links)
[ES] En esta tesis, el principal objetivo es analizar el efecto de la osteoporosis en el comportamiento mecánico del hueso trabecular. El comportamiento del hueso trabecular se ha abordado desde diferentes enfoques: ensayos experimentales, modelos de elementos finitos (EF) e imagen médica obtenida por micro-CT.
El impacto de la osteoporosis se ha estudiado en distintas escalas. Se ha abordado un estudio a nivel de tejido lamelar del hueso trabecular para estimar las ecuaciones que nos permitan definir las propiedades elásticas y resistentes en función de la densidad mineral ósea y la porosidad del tejido. Estas ecuaciones inferidas en los modelos de EF permitirán estudiar el comportamiento del tejido óseo lamelar abarcando un amplio rango de porosidades y DMOs.
Se ha realizado un estudio de la estructura trabecular y del tejido lamelar utilizando un estereomicroscopio y el FESEM. Al nivel del tejido lamelar, se ha podido observar la disposición de las lamelas en distintas localizaciones, como en las trabéculas y sus intersecciones. Además, se ha podido evaluar la porosidad tisular natural y la producida por enfermedades óseas. Esta información se ha introducido en los modelos EF para definir las propiedades en las muestras. Las ecuaciones elásticas y resistentes estimadas consideran un comportamiento ortótropo y es posible cuantificar cómo afectan la DMO y la porosidad a estas propiedades.
Se ha estudiado el comportamiento mecánico a compresión de muestras humanas de hueso trabecular procedente de cabezas femorales. Estas muestras se clasifican en tres grupos: sano, artrósico y osteoporótico. Estas muestras se han estudiado mediante ensayos experimentales, imagen médica y modelos de EF, permitiendo obtener gran información sobre el comportamiento mecánico del hueso. La respuesta mecánica está muy influenciada por la microarquitectura trabecular. Los resultados obtenidos más relevantes son el módulo aparente, la tensión de fallo y la deformación de fallo. Se han podido generar modelos de EF y estudiar la morfometría de las muestras. Los modelos de EF han permitido estimar las propiedades a nivel de tejido: módulo de Young a nivel de tejido y las deformaciones de fluencia y fallo. Los resultados muestran que a nivel de tejido no se aprecian variaciones en el módulo de Young aunque el hueso presente una patología ósea. Un comportamiento de fluencia similar se ha observado para todos los grupos, con diferencias únicamente en la deformación de fallo.
El estudio morfométrico permite analizar los parámetros morfométricos que diferencian las muestras sanas de las enfermas. Se han correlacionado dichos parámetros con la respuesta mecánica para analizar los que tienen mayor influencia sobre ella. Las correlaciones permiten estimar la respuesta mecánica del hueso utilizando imagen médica sin realizar ensayos experimentales. Los parámetros obtenidos de la respuesta mecánica también se han relacionado entre sí, permitiendo conocer el comportamiento de cada una de las muestras que es diferente según la enfermedad que padecen.
También, se han estudiado muestras bioinspiradas y estructuras TPMS obtenidas mediante fabricación aditiva. Estas muestras se han fabricado con PLA como material de impresión. Las muestras muestran un comportamiento ortótropo como las muestras trabeculares. Los simulantes pueden ser utilizados para hacer estudios previos cuando no se disponga de las muestras óseas. El tratamiento de fracturas óseas de gran tamaño requiere de técnicas no convencionales para la fijación del hueso. Suelen utilizarse andamios óseos con triple periodicidad que tienen como resultado propiedades ortótropas iguales en las tres direcciones ortogonales. Estos sistemas deben disponer de rigideces similares al hueso alrededor del defecto para evitar el aflojamiento del implante. Por ello, se propone una metodología que permite diseñar andamios óseos paciente-específicos que permiten ajustar las propiedades mecánicas ortótropas en función del hueso. / [CA] En esta tesi, el principal objectiu és analitzar l'efecte de l'osteoporosi en el comportament mecànic de l'os trabecular. El comportament de l'os trabecular s'ha abordat des de diferents plantejaments, com són els assajos experimentals, els models d'elements finits (EF) i la imatge mèdica obtinguda per micro-CT.
L'impacte de l'osteoporosi s'ha estudiat en diferents escales. En primer lloc, s'ha abordat un estudi a nivell de teixit lamellar de l'os trabecular per a estimar les equacions que ens permeten definir les propietats elàstiques i resistents en funció de la densitat mineral òssia i la porositat del teixit. Estes equacions inferides en els models d'EF permetran estudiar el comportament del teixit ossi lamel·lar abastant un ampli rang de porositats i DMOs.
S'ha realitzat un estudi de l'estructura trabecular i del teixit lamel·lar utilitzant un estereomicroscopi i el FESEM. Al nivell del teixit lamel·lar, s'ha pogut observar la disposició de les lamel·les en diferents localitzacions, com en les trabècules i les seues interseccions. A més, s'ha pogut avaluar la porositat tissular natural i la produïda per malalties òssies. Tota esta informació ha sigut incorporada als models numèrics per a poder definir les propietats en les mostres trabeculars. Les equacions elàstiques i resistents estimades consideren un comportament ortòtrop i és possible quantificar com afecten la DMO i la porositat a estes propietats.
S'ha estudiat el comportament mecànic a compressió de mostres humanes d'os trabecular procedent de caps femorals i s'han classificat en tres grups: sa, artròsic i osteoporòtic. S'han estudiat mitjançant assajos experimentals, imatge médica i models d'EF, obtenint gran informació sobre el comportament mecànic de l'os. La resposta mecànica està fortament influenciada per la microarquitectura trabecular. Els resultats obtinguts més importants són el mòdul aparent, la tensió de fallada i la deformació de fallada. S'han generat models d'EF i estudiat la morfometria. Els models d'EF han permés estimar les propietats a nivell de teixit: el mòdul de Young a nivell de teixit i les deformacions de fluència i fallada. A nivell de teixit no s'aprecien variacions en el mòdul de Young encara que l'os present una patologia òssia. Un comportament de fluència similar s'ha observat per a tots els grups, amb diferències únicament en la deformació de fallada.
L'estudi de la morfometria ha permés analitzar els paràmetres morfomètrics que diferencien les mostres sanes de les malaltes, i fins i tot a diferenciar entre diferents patologies. S'han correlacionat estos paràmetres amb la resposta mecànica per a analitzar aquells que tenen major influència sobre ella. Les correlacions obtingudes permeten estimar la resposta mecànica de l'os trabecular utilitzant les imatges micro-CT sense necessitat de realitzar assajos experimentals. Els paràmetres obtinguts de la resposta mecànica també s'han relacionat entre si. Estes relacions permeten conéixer el comportament de cadascuna de les mostres que és diferent segons la malaltia que patixen.
També, s'han estudiat mostres bioinspirades i estructures TPMS obtingudes mitjançant fabricació additiva. Estes mostres bioinspirades s'han fabricat amb PLA com a material d'impressió. Les mostres mostren un comportament ortòtrop com les trabeculars. Estos simulants poden ser utilitzats per a fer estudis previs quan no es dispose de les mostres òssies. El tractament de fractures òssies de gran grandària requerix de tècniques no convencionals per a la fixació de l'os. Solen utilitzar-se bastides òssies amb triple periodicitat que tenen com a resultat propietats ortòtropes iguals en les tres direccions ortogonals. Estos sistemes han de disposar de rigideses similars a l'os en el veïnatge del defecte per a evitar l'afluixament de l'implant. S'ha proposat una metodologia que permet dissenyar bastides òssies pacient-específics que permeten ajustar les propietats mecàniques ortòtropes en cada direcció en funció de l'os. / [EN] The main objective of this thesis is to analyse the effect of osteoporosis on the mechanical behaviour of cancellous bone. The behaviour of cancellous bone has been addressed through different approaches: experimental tests, finite element (FE) models and medical imaging obtained by micro-CT.
The impact of osteoporosis has been studied on different scales. Firstly, a study has been undertaken at the lamellar tissue level of trabecular bone to estimate the equations that define the elastic and strength properties as a function of bone mineral density and tissue porosity. These equations are inferred from FE models and allow us to characterise the behaviour of lamellar bone tissue covering a wide range of porosities and BMDs.
A study of the cancellous structure and lamellar tissue has been carried out using a stereomicroscope and FESEM. At lamellar tissue level, it was possible to observe the arrangement of lamellae in different locations, such as trabeculae and at their intersections. In addition, it has been possible to evaluate the natural tissue porosity and that produced by bone diseases. All this information has been incorporated to the numerical models in order to define the properties of cancellous bone samples. The estimated elastic and strength equations consider an orthotropic behaviour and it is possible to quantify how BMD and porosity affect these properties.
On the other hand, the mechanical behaviour under compression of human trabecular bone samples from femoral heads has been studied. These samples are classified into three study groups: healthy, osteoarthrosic and osteoporotic. The samples have been studied using experimental tests, medical imaging obtained and FE models, enabling to obtain a great deal of information regarding the mechanical behaviour of the bone. The trabecular microarchitecture strongly influences the mechanical response. The most important results obtained are the apparent modulus, the failure stress and the failure strain. It was possible to generate FE models and study the morphometry of the specimens. The FE models have made it possible to estimate the properties at the tissue level. The results revealed that at the tissue level, Young's modulus does not vary appreciably, even if the bone shows bone pathology. A similar yield behaviour is observed for all groups, with differences only in the final failure strain.
The morphometry study has enabled to analyse the morphometric parameters that differentiate between healthy and diseased specimens and even to differentiate between different pathologies. The morphometric parameters have been correlated with the mechanical response to analyse those that have the most significant influence on the mechanical response. The correlations obtained make it possible to estimate the mechanical response of trabecular bone using micro-CT images without the need for experimental tests. The parameters obtained from the mechanical response have also been related. These relationships permit to know the behaviour of each of the samples, which is different depending on the disease they suffer.
Finally, bioinspired samples and minimal surface area triple periodic structures obtained by additive manufacturing have been studied. These samples are made of PLA as the printing material. The samples show a similar orthotropic behaviour to the trabecular samples. These simulants can be used for pre-studies when bone samples are not available. The treatment of large bone fractures requires unconventional techniques for bone fixation. Bone scaffolds with triple periodicity that result in equal orthotropic properties in all three orthogonal directions are often used. These systems must have bone-like stiffness in the vicinity of the defect to avoid implant loosening. To this end, a methodology has been proposed to design patient-specific bone scaffolds that allow the orthotropic mechanical properties in each direction to be calibrated according to a specific bone. / The author and the supervisors of this PhD thesis acknowledge the Ministerio de Ciencia e Innovación y Universidades and the European Regional Development Fund (FEDER) for the financial support received through the projects PID2020-118920RB-I00 and PID2020-118480RB-C21 and C22 funded by MCIN/AEI/10.13039/501100011033, and the Generalitat Valenciana for Plan FDEGENT 2018 and Programa PROMETEO/2021/046. / Megías Díaz, R. (2024). Analysis of osteoporosis effect on the mechanical behaviour and morphometry of human cancellous bone [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/206355
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