Dissertations / Theses on the topic 'Structural Regularity'
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1
Sadashiva, Vinod Kota. "Quantifying structural irregularity effects for simple seismic design." Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2010. http://hdl.handle.net/10092/5309.
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This study was initiated to quantify the effect of different degrees of irregularity on
structures designed for earthquake using simplified analysis. The types of irregularity
considered were:
(a) Vertical Irregularity
• Mass
• Stiffness -Strength
(b) Horizontal (Plan) Irregularity
• Diaphragm Flexibility
Simple models were used to allow many analyses to be conducted in a relatively short
time. For vertical irregularity studies, simple shear-type structures were designed
according to the New Zealand design Standard, NZS1170.5, firstly as regular
structures, and then they were redesigned as irregular structures to the same target
drift. Both regular and irregular structures were then subjected to a suite of records,
and vertical irregularity effects evaluated from the difference in response. For the
flexible diaphragm effect study, simple models of structures were developed with: (a)
a rigid diaphragm assumption; and (b) a flexible diaphragm assumption. Flexible
diaphragm effects were evaluated by conducting time-history analyses and comparing
the responses of structures with rigid and flexible diaphragms. A mechanics based
approach was developed to quantify flexible diaphragm effects, which was shown to
produce consistent results with those from time-history analyses.
Relationships between the degree of irregularity and the change in behaviour were
developed. This information facilitates designers and plan checkers to rapidly
evaluate the likely effect of irregularity on structures. It provides guidance as to: (a)
when the effect of structural irregularity can be ignored, and (b) the change in
demands for different degrees of structural irregularity. The relations developed also
provide a rigorous technical basis for future regularity provisions in the NZS1170.5
and other world-wide seismic design codes.
2
Millward, Raymond. "A new adaptive multiscale finite element method with applications to high contrast interface problems." Thesis, University of Bath, 2011. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.544505.
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In this thesis we show that the finite element error for the high contrast elliptic interface problem is independent of the contrast in the material coefficient under certain assumptions. The error estimate is proved using a particularly technical proof with construction of a specific function from the finite dimensional space of piecewise linear functions. We review the multiscale finite element method of Chu, Graham and Hou to give clearer insight. We present some generalisations to extend their work on a priori contrast independent local boundary conditions, which are then used to find multiscale basis functions by solving a set of local problems. We make use of their regularity result to prove a new relative error estimate for both the standard finte element method and the multiscale finite element method that is completely coefficient independent. The analytical results we explore in this thesis require a complicated construction. To avoid this we present an adaptive multiscale finite element method as an enhancement to the adaptive local-global method of Durlofsky, Efendiev and Ginting. We show numerically that this adaptive method converges optimally as if the coefficient were smooth even in the presence of singularities as well as in the case of a realisation of a random field. The novel application of this thesis is where the adaptive multiscale finite element method has been applied to the linear elasticity problem arising from the structural optimisation process in mechanical engineering. We show that a much smoother sensitivity profile is achieved along the edges of a structure with the adaptive method and no additional heuristic smoothing techniques are needed. We finally show that the new adaptive method can be efficiently implemented in parallel and the processing time scales well as the number of processors increases. The biggest advantage of the multiscale method is that the basis functions can be repeatedly used for additional problems with the same high contrast material coefficient.
3
Aroskar, Ashwini. "Limits, Regularity and Removal for Relational and Weighted Structures." Research Showcase @ CMU, 2012. http://repository.cmu.edu/dissertations/144.
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The Szemeredi Regularity Lemma states that any graph can be well-approximated by graphs that are almost random. A well-known application of the Szemeredi Regularity Lemma is in the proof of the Removal Lemma for graphs. There are several extensions of the Regularity Lemma to hypergraphs. Our work builds on known results for k-uniform hypergraphs including the existence of limits, a Regularity Lemma and a Removal Lemma.
Our main tool here is a theory of measures on ultraproduct spaces which establishes a correspondence between ultraproduct spaces and Euclidean spaces. We show the existence of a limit object for sequences of relational structures and as a special case, we retrieve the known limits for graphs and digraphs. We also state and prove a Regularity Lemma, a Removal Lemma and a Strong Removal Lemma for relational structures. The Strong Removal Lemma deals with the removal of a family of relational structures and has applications in property testing.
We have also extended the above correspondence to measurable functions on the ultraproduct and Euclidean spaces. This enabled us to find limit objects for sequences of weighted structures and these can be seen as generalizations of the limits we have obtained for relational structures. We also formulate and prove Regularity and Removal Lemmas for weighted structures.
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Baumgartner, Michael. "Complex causal structures : extensions of a regularity theory of causation /." Bern : Selbstverlag, 2006. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Boo, Woong Jae. "Characterization of thin film properties of melamine based dendrimer nanoparticles." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/1611.
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With the given information that dendrimers have precisely controlled their sizes and spherical structures in the molecular level, the aim of this study is to show that dendrimer particles can become ordered into a self-assembled regular structure due to the nature of their regular sizes and shapes. For this project, melamine based generation 3 dendrimer was used for solution cast of thin films from the dendrimer-chloroform solutions with different casting conditions, i.e. various solution concentrations, casting temperatures, and substrates. As a result of these experiments, unique phenomena of highly ordered uniform 2-D contraction separations were observed during the solvent evaporation from the dendrimer films. The cast films from the concentration of 0.8 wt% and higher exhibit regular 2-D separation contraction patterns and make well-developed regularly arrayed structures due to the interaction between the contraction stresses and adhesion strength between films and substrates. From the DSC tests, both powder and cast film samples of a dendrimer show similar melting behaviors with different areas under the melting peaks. The results of these tests show that dendrimers, when they are in a descent environment that provides dendrimers with molecular mobility due to surface ionic bonding strength, can make a structural order and regularity in their macroscopic structures.
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Behnejad, S. Alireza. "Geometrical data for lattice spatial structures : regularity, historical background and education." Thesis, University of Surrey, 2018. http://epubs.surrey.ac.uk/849532/.
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Dealing with geometrical information has been an important aspect of the knowledge required for construction of a structure. In particular, data generation techniques appropriate for complex geometries are crucial for the design and construction of spatial structures. This may be referred to as ‘Configuration Processing’ and has been the centre of attention for some researchers in the past few decades. A main focus of this thesis is the ‘regularity’ in structural forms and the present research shows that the ‘metric properties’ of structural forms, suggested by the Author, are fundamental for the study of regularity. Metric properties refer to the geometrical information necessary for design, and in particular, construction of lattice spatial structures. To elaborate, the research addresses the following questions: • What are the metric properties for a lattice structure and how can these be evaluated? • What is the definition of regularity for lattice structures and how can this be quantified? • How could the regularity of a lattice structure be improved? The Author is an architect and structural engineer who has been involved in the design and construction of lattice spatial structures for 20 years. The experience of the actual construction over the years has shown that there are advantages in keeping the number of different types of structural components small. In another front, the study of regularity of forms for lattice structures may involve the ‘visual aspects’, ‘arrangements of elements’ or ‘structural components’. The first two aspects are subjective matters and the latter one, that is the focus of the present work, is an objective matter. The present research shows that the metric properties of structural forms are fundamental for the study of component regularity. There are considerable benefits in terms of the construction of structures which have a high degree of regular components. The benefits include savings in time and cost of construction, as well as a reduction in probability of having a wrong arrangement during assembly. In this sense, the present work could be considered as a research of fundamental importance which provides a basis for the knowledge in this field. Most of the examples in the Thesis are single layer lattice structures with straight elements and further research on other types of lattice structures is recommended. This thesis consists of six chapters, the first of which entitled ‘Introduction’ provides background information about the research and discusses the research aims. Chapter 2 on the ‘Literature Review’ concerns the few available publications relevant to the research. The third chapter entitled ‘Metric Properties’ defines a number of geometrical parameters which are being used to generate the geometrical information. Also, the mathematics involved for the necessary calculations are discussed. This chapter is a major contribution of the thesis and to the available knowledge in terms of introduction a set of well defined geometrical parameters for design and construction of lattice spatial structures. Chapter 4 is dedicated to discussion of different aspects of ‘Regularity’ of lattice structures. To begin with, the idea of regularity is elaborated upon and then the concept of ‘regularity indicators’ are discussed. These indicators help to quantify regularity of components. Here again, this chapter presents a novel idea in the field of lattice spatial structures. Another major contribution of this thesis to the general knowledge is Chapter 5 entitled ‘Sphere Packing’. This is a particular technique for configuration processing developed by the Author to improve the member length regularity of lattice structures. An example of the application of the technique for configuration processing of spherical domes is also discussed in details. Moreover, a comparison on the variation of the member lengths of different dome configurations is discussed which shows that around 50% of the members of a dome created by sphere packing technique are with the same length. This proportion of equal length members is considerably higher than that of the other dome configurations (10%-33%). Finally, Chapter 6 provides the conclusions and some important suggestions for the continuation of the research. In addition to the main body of this thesis, copy of the relevant publications by the Author are provided as Annexes in the following three categories: i. Geometrical data generation for lattice spatial structures is the core of the Annexes A to E, then, ii. Annexes F and G are focusing on the education of spatial structures, and finally, iii. Historical background of spatial structures is discussed in the Annexes H and I.
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Goulet-Langlois, Gabriel. "Exploring regularity and structure in travel behavior using Smart Card data." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99546.
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Thesis: S.M. in Transportation, Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2015.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 161-166).
As the economic opportunities fostered by large cities become more diverse, the travel patterns of public transport users become more heterogeneous. From personalized customer information, to improved travel demand models, understanding these heterogeneous travel patterns is useful for a number of applications relevant to public transport agencies. This thesis explores how smart card data can be used to analyze and compare the structure of individual travel patterns observed over several weeks. Specifically, the way in which multiple journeys and activities are ordered and combined into repeated patterns, both by the same individual over time and across individuals is evaluated from the journey sequence of each user. The research is structured around three objectives. First, we introduce a representation of individual travel patterns and develop a measure of travel sequence regularity. The mobility of each individual is modeled as a stochastic process with memory, of which each new realization represents an activity or journey. Entropy rate, a measure of randomness in the stochastic process, is used to quantify repetition in the order of journeys and activities. This analysis reveals that the order of events is an important component of regularity not explicitly captured in previous literature. Second, we develop an approach to identify clusters of travel patterns with similar structure considered with respect to public transport usage and activity patterns. Finally, we present an exploratory evaluation of the associations between the identified clusters and socio-demographic characteristics by linking smart card data to an annual travel diary survey. These three objectives are considered in the context of a practical application using the transactions of a sample of approximately 100,000 users collected between February 10th and March 10th 2015 in London.
by Gabriel Goulet-Langlois.
S.M. in Transportation
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Daghighi, Abtin. "Regularity and uniqueness-related properties of solutions with respect to locally integrable structures." Doctoral thesis, Mittuniversitetet, Avdelningen för ämnesdidaktik och matematik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-21641.
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We prove that a smooth generic embedded CR submanifold of C^n obeys the maximum principle for continuous CR functions if and only if it is weakly 1-concave. The proof of the maximum principle in the original manuscript has later been generalized to embedded weakly q-concave CR submanifolds of certain complex manifolds. We give a generalization of a known result regarding automatic smoothness of solutions to the homogeneous problem for the tangential CR vector fields given local holomorphic extension. This generalization ensures that a given locally integrable structure is hypocomplex at the origin if and only if it does not allow solutions near the origin which cannot be represented by a smooth function near the origin. We give a sufficient condition under which it holds true that if a smooth CR function f on a smooth generic embedded CR submanifold, M, of C^n, vanishes to infinite order along a C^infty-smooth curve \gamma in M, then f vanishes on an M-neighborhood of \gamma. We prove a local maximum principle for certain locally integrable structures.Funding by FMB, based at Uppsala University.
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Franzoni, Lorenzo. "Mechanical behavior of regularly spaced Cross Laminated Timber panels : Modeling and experimental validation in ambient and fire conditions." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1113/document.
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Les panneaux en bois lamellé croisé (en anglais CLT - Cross Laminated Timber) sont des éléments de structure composés de couches en bois collées entre eleese et empilées de façon croisée. Chaque couche est composée de planches en bois juxtaposées et généralement non collées sur leur chants. Dans cette thèse, nous étudions l'influence sur le comportement mécanique des espacements entre planches des panneaux avec une approche par modélisation et expérimentation. Les panneaux CLT standard sont considérés comme des panneaux avec des espacements de très faible dimension par opposition aux panneaux avec espacements importants que nous appelons panneaux innovants. Nous modélisons dans un premier temps le comportement en flexion de panneaux standard à l'aide d'un modèle de couche homogène équivalente basée sur des hypothèses simplifiées de la mécanique d'une couche avec chants collés ou non collés. Nous observons un bon accord entre les résultats de notre modélisation et des résultats expérimentaux issus de la littérature. Des études paramétriques sont ensuite réalisés portant sur certaines propriétés des panneaux.Nous avons ensuite réalisé des essais de flexion 4-points sur des panneaux CLT standard et innovants pour quantifier l'influence des espacements sur la réponse mécanique des panneaux. Il se trouve que l'influence des effets de cisaillement transverse sur le comportement élastique et à la rupture augmente avec l'augmentation des vides dans le panneau.Afin de prendre correctement en compte les effets du cisaillement, les CLT espacés sont modélisés comme des plaques épaisses périodiques à l'aide d'un modèle de plaque d'ordre supérieur. Ce modèle a été appliqué à la géométrie des panneaux CLT espacés avec un schéma d'homogénéisation périodique. Des méthodes simplifiées existantes ont également été comparées avec les résultats des essais et le modèle de plaque. De plus, des résultats d'essais de cisaillement dans le plan des panneaux CLT standard issus de la littérature ont été comparés avec nos résultats. La raideur de flexion des CLT espacés peut être prédite avec des méthodes simples existantes, alors que seule la modélisation que nous proposons permet de prédire le comportement en cisaillement transverse et dans le plan. Finalement, des formules analytiques ont été obtenues pour prédire le comportement élastique des CLT espacés. Ces formules donnent une bonne approximation u comportement des CLT espacés et peuvent être utilisées dans le cadre d'une démarche pratique de dimensionnement.Enfin, une étude concernant l'analyse du comportement au feu des panneaux CLT standard est présentée. La comparaison entre des résultats d'essais au feu et une modélisations avancée et simplifiée a permis de proposer une possible amélioration de la méthode de dimensionnement au feu standardCross Laminated Timber (CLT, or crosslam) panels are engineered timber products composed of layers made of wooden lamellas placed side by side, glued on their upperand lower faces and stacked crosswise. In the present thesis, the influence of lateral spaces between lamellas of each layer on the panel’s mechanical response is investigated with modeling and tests. Both configurations of standard panels having short spaces and innovative CLT panels with large spaces are analyzed.As a first approach, the bending behavior of standard crosslam was modeled by means of an equivalent-layer model based on simplified hypotheses on mechanical properties of laterally glued or unglued layers. The good agreement of the predicted behavior with an experiment of the literature finally allowed an investigation on several CLT properties by means of parameter studies.Then, 4-points bending tests on standard and innovative CLT floors were performed in order to quantify the influence of periodic spaces on the panels' mechanical response. It appears that the influence of transverse shear effects on the elastic and failure behavior of spaced CLT increases with the increasing spaces between boards.In order to take into account transverse shear effects, spaced CLT have been modeled as periodic thick plates by means of a higher-order plate theory for laminated plates. This model has been applied to the geometry of spaced CLT with a periodic homogenization scheme. Existing simplified methods for spaced crosslam were compared as well with refined modeling and test results. Moreover, available in-plane shear tests of the literature have been compared to the modeling results. It appears that the bending behavior of spaced CLT can be predicted with simplified existing approaches, while only the more refined modeling can predict the in-plane and transverse shear behavior. Then, closed-form solutions for predicting spaced CLT elastic behavior were derived in order to encourage the application of spaced CLT panels in modern timber construction.One further study within this thesis concerns the analysis of fire-exposed standard CLT floors. The comparison between test results and both advanced and simplified modeling led to a suggestion for a possible improvement the standard fire design model
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Burtscher, Annegret Yvonne. "Analytic and geometric aspects of spacetimes of low regularity." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066345.
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La théorie de la relativité générale décrit l'effet de la gravitation en termes de géométrie des espaces-temps. La courbure des variétés lorentzienne est liée à l'énergie et l'évolution de la matière (ou du vide) par les équations d'Einstein, un système d'équations différentielles non-linéaires. Dans les années 1950, l'existence locale de solutions des équations d'Einstein a été établie. Motivé par ce résultat, j'étudie l'évolution ainsi que la régularité des espaces-temps. Il est démontré que certaines estimations d'énergie peuvent être contrôlées par des limites unilatérales portant uniquement sur la géométrie. Les estimations de l'énergie Bel-Robinson, par exemple, sont indispensables pour le calcul des critères d'effondrement pour les solutions des équations d'Einstein. Comme un important espace-temps, des modèles astrophysiques avec des sources de fluides parfaits sont considérés. Une théorie d'existence de solutions à symétrie sphérique pour l'équations Einstein-Euler est présenté et on identifie une classe de données initiales non-piégées qui conduit à la formation dynamique de surfaces piégées. Pour permettre des ondes de choc, des solutions à variation bornée sont considérées. Dans ce cadre de là et dans d'autres domaines de la relativité générale, il est crucial de comprendre si et comment la régularité des métriques influe sur la géométrie des espaces-temps. Je propose aussi quelques résultats généraux sur les métriques riemanniennes continues et sur l'algèbre des fonctions généralisées. Cette thèse montre donc que l'espace-temps de faible régularité présentent un large éventail de phénomènes intéressants au cours de leur évolutionThe general theory of relativity describes the effect of gravitation in terms of the geometry of spacetimes. The curvature of Lorentzian manifolds is related to the energy and momentum of matter (or vacuum) by the Einstein equations, a system of nonlinear partial differential equations. In the 1950s the initial value formulation and local existence of solutions to the Einstein equations were established. As of yet the global structure of spacetimes is much less understood. Motivated by this I investigate the evolution as well as the regularity of spacetimes. I show that certain energy estimates can be controlled by one-sided bounds on the geometry only. Estimates of the Bel-Robinson energy, for example, play a crucial role in the derivation of breakdown criteria for solutions of the vacuum Einstein equations. As an important astrophysical model spacetimes with perfect fluid sources are considered. An existence theory for spherically symmetric solutions to the Einstein-Euler equations is presented, and, above all, I identify for the first time a class of untrapped initial data that leads to the dynamical formation of trapped surfaces. To allow for shock waves, solutions are regarded to be of bounded variation. The distributional framework is essential here and in other areas of general relativity, and it is crucial to understand if and how the regularity of metrics influences the geometry of spacetimes. I account for this by deriving some general results on continuous Riemannian metrics and algebras of generalized functions. This thesis thus illustrates that spacetimes of low regularity exhibit a wide range of interesting phenomena during their evolution
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Jared, Debra J. (Debra Jean). "The processing of multisyllabic words : effects of phonological regularity, syllabic structure and frequency." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63367.
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Mach, Philip. "Bifurcating Mach Shock Reflections with Application to Detonation Structure." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20182.
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Numerical simulations of Mach shock reflections have shown that the Mach stem can bifurcate as a result of the slip line jetting forward. Numerical simulations were conducted in this study which determined that these bifurcations occur when the Mach number is high, the ramp angle is high, and specific heat ratio is low. It was clarified that the bifurcation is a result of a sufficiently large velocity difference across the slip line which drives the jet. This bifurcation phenomenon has also been observed after triple point collisions in detonation simulations. A triple point reflection was modelled as an inert shock reflecting off a wedge, and the accuracy of the model at early times after reflection indicates that bifurcations in detonations are a result of the shock reflection process. Further investigations revealed that bifurcations likely contribute to the irregular structure observed in certain detonations.
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Shao, Cheng. "Multi-writer consistency conditions for shared memory objects." Texas A&M University, 2007. http://hdl.handle.net/1969.1/85806.
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Regularity is a shared memory consistency condition that has received considerable attention, notably in connection with quorum-based shared memory. Lamport's
original definition of regularity assumed a single-writer model, however, and is not
well defined when each shared variable may have multiple writers. In this thesis, we
address this need by formally extending the notion of regularity to a multi-writer
model. We have shown that the extension is not trivial. While there exist various
ways to extend the single-writer definition, the resulting definitions will have different
strengths. Specifically, we give several possible definitions of regularity in the presence
of multiple writers. We then present a quorum-based algorithm to implement each of
the proposed definitions and prove them correct. We study the relationships between
these definitions and a number of other well-known consistency conditions, and give
a partial order describing the relative strengths of these consistency conditions. Finally, we provide a practical context for our results by studying the correctness of two
well-known algorithms for mutual exclusion under each of our proposed consistency
conditions.
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Lohse, Ekkehard [Verfasser]. "Design of Regularly Structured Composite Latent Heat Storages for Thermal Management Applications / Ekkehard Lohse." München : Verlag Dr. Hut, 2013. http://d-nb.info/104598910X/34.
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Timm, Thomas [Verfasser], and Wim [Akademischer Betreuer] Martens. "Exploration of Large-Scale SPARQL Query Collections : Finding Structure and Regularity for Optimizing Database Systems / Thomas Timm ; Betreuer: Wim Martens." Bayreuth : Universität Bayreuth, 2020. http://d-nb.info/1205804811/34.
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Zhang, Yun. "Micro-structural and optical investigation of semi-polar (11-22) III-nitrides overgrown on regularly arrayed micro-rods." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/18698/.
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This project aims to systematically study the micro-structure and optical properties of semi-polar (11-22) GaN with a step-change in crystal quality achieved by means of overgrowth on regularly arrayed micro-rods. The optical properties of (11-22) InGaN-based quantum wells grown on such high quality GaN templates have been investigated in comparison with their c-plane counterparts. The overgrowth of semi-polar (11-22) GaN grown is performed using a metal organic chemical vapour deposition (MOCVD) technique on specially designed micro-rod arrays on standard m-plane sapphire. Owing to the specially designed patterns of the micro-rod template, our overgrowth technique effectively mitigates the intrinsic issue of the anisotropic lateral growth rate. Thanks to the massive overgrowth work of semi-polar (11-22) GaN on sapphire which were mainly carried out by Dr. Yipin Gong, I have the chance to investigate the defect reduction mechanism in details by using transmission electron microscopy (TEM) measurements. It has been found that most of the dislocations and the basal stacking faults (BSFs) have been effectively blocked by the SiO2 masks on each micro-rod and then the coalescence processes during the overgrowth. By favouring the growth along the c-direction (the c-direction growth leads to free-defect, while the defects can be penetrated through the growth along the a-direction), the defects as a result of the growth along the a-direction could be blocked. As a type of two-dimensional defect, BSFs can expand within the basal plane, propagating with a component parallel the m-direction. This leads to a distribution of BSF-free regions periodically separated by the BSF regions along the [-1-123] direction. Furthermore, each BSF region typically consists of low density BSF clusters and high density BSF clusters with a periodic distribution along the m-direction. Finally, a defect reduction model has been established in order to study the influence of the micro-patterning on defect reduction. Further investigation was also carried out on the influence of micro-rod diameter on the crystal quality of overgrown semi-polar (11-22) GaN in order to optimize our micro-rod design. It has been found that the BSF density decreases monotonically with increasing micro-rod diameter from 2 to 5 μm, and then starts to be saturated when the micro-rod diameter further increases. However, the dislocation density reduces significantly when the micro-rod diameter increases from 2 to 4 μm, and then increases slightly with further increasing the diameter to 5 μm. In addition, it has been found that it is effective to employ shorter micro-rods to further reduce BSFs, allowing for further improvement in crystal quality. The best crystal quality of the overgrown (11-22) GaN has been achieved by overgrowth on micro-rods with a 4 μm diameter and a 0.4 μm height, corresponding to a dislocation density of 2.0 × 108 cm-2 which is better or at least equivalent to standard c-plane GaN with a similar thickness grown on c-plane sapphire. The best sample achieved so far exhibits a BSF density of 2.8 × 104 cm-1. In this project, a number of advance optical characterization methods have been performed on a large number of semi-polar (11-22) InGaN/GaN MQWs with a wide spectral range of up to yellow spectra region grown on high quality semi-polar GaN, aiming to systemically investigate the mechanisms which form the large Stokes shift that generally occurs to InGaN/GaN MQWs. This is a long-standing issue. The semi-polar (11-22) samples exhibit a lower Stokes shift than their c-plane counterparts, although they show larger exciton localization than their c-plane counterparts. The Stokes shift in the semi-polar samples shows a linear relationship with the emission energy in long wavelength region, but with a smaller gradient compared with that in the c-plane counterparts. The time-resolved photoluminescence (PL) measurements reveal a significant reduction in the piezoelectric fields of the semi-polar sample. It is suggested that the piezoelectric field induced polarization is the major mechanism for causing the large Stokes shift in conventional c-plane InGaN/GaN MQWs.
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Bellingeri, Carlo. "Formules d'Itô pour l'équation de la chaleur stochastique à travers les théories des chemins rugueux et des structures de regularité." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS028.
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Dans cette thèse nous développons une théorie générale pour prouver l’existence de plusieurs formules de Itô sur l’équation de chaleur stochastique unidimensionnelle dirigée par un bruit blanc en espace-temps. Cela revient a définir de nouvelles notions d’intégrales stochastique sur u, la solution de cette EDPS et à obtenir pour toute fonction assez lisse f des nouvelles identités impliquant f(u) et des termes de correction non triviaux. Ces nouvelles relations sont obtenues en utilisant la théorie des structures de régularité et la théorie des chemins rugueux. Dans le premier chapitre nous obtenons une identité intégrale et une différentielle impliquant la reconstruction de certaines distributions modélisées. Ensuite, nous discutons d’une formule générale de changement de variable pour tout chemins Hölderiens dans le contexte des chemins rugueux en le rapportant à la notion d’algèbres quasi-shuffle et à la famille des chemins rugueux dits quasi-géométriques. Enfin nous appliquons les résultats généraux sur les chemins rugueux quasi-géométriques à l’évolution temporelle du processus u. En utilisant le comportement gaussien de u, nous identifions la plupart des termes impliqués dans ces équations avec certaines constructions du calcul stochastiqueIn this thesis we develop a general theory to prove the existence of several Itô formulae on the one dimensional stochastic heat equation driven by additive space-time white noise. That is denoting by u the solution of this SPDE for any smooth enough function f we define some new notions of stochastic integrals defined upon u, which cannot be defined classically, in order to deduce new identities involving f(u) and some non trivial corrections. These new relations are obtained by using the theory of regularity structures and the theory of rough paths. In the first chapter we obtain a differential and an integral identity involving the reconstruction of some modelled distributions. Then we discuss a general change of variable formula over any Hölder continuous path in the context of rough paths, relating it to the notion of quasi-shuffle algebras and the family of so called quasi-geometric rough paths. Finally we apply the general results on quasi-geometric rough paths to the time evolution of u. Using the Gaussian behaviour of the process u, most of the terms involved in these equations are also identified with some classical constructions of stochastic calculus
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Vicente, David. "Modèles de Mumford-Shah pour la détection de structures fines en image." Thesis, Orléans, 2015. http://www.theses.fr/2015ORLE2055/document.
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Cette thèse est une contribution au problème de détection de fines structures tubulaires dans une image2-D ou 3-D. Nous avons plus précisément en vue le cas des images angiographiques. Celles-ci étant bruitées, les vaisseaux ne se détachent pas nettement du reste de l’image, la question est donc de segmenter avec précision le réseau sanguin. Le cadre théorique de ce travail est le calcul des variations eten particulier l'énergie de Mumford-Shah. Cependant, ce modèle n'est adapté qu'à la détection de structures volumiques étendues dans toutes les directions de l’image. Le but de ce travail est donc deconstruire une énergie qui favorise les ensembles qui ne sont étendus que dans une seule direction, cequi est le cas de fins tubes. Pour cela, une nouvelle inconnue est introduite, une métrique Riemannienne,qui a pour but la détection de la structure géométrique de l’image. Une nouvelle formulation de l’énergie de Mumford-Shah est donnée avec cette nouvelle métrique. La preuve de l'existence d'une solution au problème de la minimisation de l’énergie est apportée. De plus, une approximation par gamma-convergence est démontrée, ce qui permet ensuite de proposer et de mettre en oeuvre une implémentation numériqueThis thesis is a contribution to the fine tubular structures detection problem in a 2-D or 3-D image. We arespecifically interested in the case of angiographic images. The vessels are surrounded by noise and thenthe question is to segment precisely the blood network. The theoretical framework of our work is thecalculus of variations and we focus on the Mumford-Shah energy. Initially, this model is adapted to thedetection of volumetric structures extended in all directions of the image. The aim of this study is to buildan energy that favors sets which are extended in one direction, which is the case of fine tubes. Then, weintroduce a new unknown, a Riemannian metric, which captures the geometric structure at each point ofthe image and we give a new formulation of the Mumford-Shah energy adapted to this metric. Thecomplete analysis of this model is done: we prove that the associated problem of minimization is wellposed and we introduce an approximation by gamma-convergence more suitable for numerics. Eventually,we propose numerical experimentations adapted to this approximation
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Araujo, Gabriel Cueva Candido Soares de. "Regularidade e resolubilidade de operadores diferenciais lineares em espaços de ultradistribuições." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/45/45132/tde-08092016-200206/.
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Desenvolvemos novos resultados da teoria dos espaços FS e DFS (espaços de Fréchet-Schwartz e seus duais) e os empregamos ao estudo da seguinte questão: quando certas propriedades de regularidade de um operador diferencial parcial linear (entre fibrados vetoriais Gevrey sobre uma variedade Gevrey) implicam resolubilidade, no sentido de ultradistribuições, do operador transposto? Estudamos esta questão para uma classe de operadores abstratos que contém os operadores diferenciais parciais lineares com coeficientes Gevrey usuais, mas também certas classes de operadores pseudo-diferenciais em variedades compactas, além de certos tipos de operadores de ordem infinita. Neste contexto, obtemos uma nova demonstração de um resultado global em variedades compactas (em que hipoelipticidade Gevrey global de um operador implica resolubilidade global de seu transposto), assim como alguns resultados no caso não-compacto relacionados à propriedade de não-confinamento de singularidades. Na sequência apresentamos algumas aplicações concretas, em particular para operadores de Hörmander, operadores de força constante e sistemas localmente integráveis de campos vetoriais. Analisamos ainda algumas instâncias de uma conjectura levantada em um artigo recente de F. Malaspina e F. Nicola (2014), a qual afirma que, para certos complexos diferenciais naturalmente associados a estruturas localmente integráveis, resolubilidade local no sentido de ultradistribuições (perto de um ponto, em um grau fixado) implica resolubilidade local no sentido de distribuições. Estabelecemos a validade desta conjectura quando o fibrado estrutural cotangente é gerado pelo diferencial de uma única integral primeira.We develop new techniques in the setting of FS and DFS spaces (Fréchet-Schwartz spaces and their strong duals) and apply them to the study of the following question: when regularity properties of a general linear differential operator (between Gevrey vector bundles over a Gevrey manifold) imply solvability of its transpose in the sense of ultradistributions? This question is studied for a class of abstract operators that encompasses the usual partial differential operators with Gevrey coefficients, but also some flavors of pseudodifferential operators on compact manifolds and some classes of operators with infinite order. In this setting, we obtain a new proof of a global result on compact manifolds (global Gevrey hypoellipticity of the operator implying global solvability of the transpose), as well as some results in the non-compact case by means of the so-called property of non-confinement of singularities. We then move to some concrete applications, especially for Hörmander operators, operators of constant strength and locally integrable systems of vector fields. We also analyze some instances of a conjecture stated in a recent paper of F. Malaspina and F. Nicola (2014), which asserts that, in differential complexes naturally arising from locally integrable structures, local solvability in the sense of ultradistributions (near a point, in some fixed degree) implies local solvability in the sense of distributions. We establish the validity of the conjecture when the cotangent structure bundle is spanned by the differential of a single first integral.
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Ouedraogo, Lazare. "Etude de quelques effets de la métamorphose des amphibiens sur certaines protéines et sur la structure hépatique." Paris 13, 1987. http://www.theses.fr/1987PA132022.
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Martin, Jörg. "Refinements of the Solution Theory for Singular SPDEs." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19329.
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Diese Dissertation widmet sich der Untersuchung singulärer stochastischer partieller Differentialgleichungen (engl. SPDEs). Wir entwickeln Erweiterungen der bisherigen Lösungstheorien, zeigen fundamentale Beziehungen zwischen verschiedenen Ansätzen und
präsentieren Anwendungen in der Finanzmathematik und der mathematischen Physik.
Die Theorie parakontrollierter Systeme wird für diskrete Räume formuliert und eine schwache Universalität für das parabolische Anderson Modell bewiesen.
Eine fundamentale Relation zwischen Hairer's modellierten Distributionen und Paraprodukten wird bewiesen: Wir zeigen das sich der Raum modellierter Distributionen durch Paraprodukte beschreiben lässt. Dieses Resultat verallgemeinert die Fourierbeschreibung von Hölderräumen mittels Littlewood-Paley Theorie.
Schließlich wird die Existenz von Lösungen der stochastischen Schrödingergleichung auf dem ganzen Raum bewiesen und eine Anwendung Hairer's Theorie zur Preisermittlung von Optionen aufgezeigt.This thesis is concerned with the study of singular stochastic partial differential equations (SPDEs). We develop extensions to existing solution theories, present fundamental interconnections between different approaches and give applications in financial mathematics and mathematical physics. The theory of paracontrolled distribution is formulated for discrete systems, which allows us to prove a weak universality result for the parabolic Anderson model. This thesis further shows a fundamental relation between Hairer's modelled distributions and paraproducts: The space of modelled distributions can be characterized completely by using paraproducts. This can be seen a generalization of the Fourier description of Hölder spaces. Finally, we prove the existence of solutions to the stochastic Schrödinger equation on the full space and provide an application of Hairer's theory to option pricing.
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Sargent, Gabriel. "Estimation de la structure de morceaux de musique par analyse multi-critères et contrainte de régularité." Phd thesis, Université Rennes 1, 2013. http://tel.archives-ouvertes.fr/tel-00853737.
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Les récentes évolutions des technologies de l'information et de la communication font qu'il est aujourd'hui facile de consulter des catalogues de morceaux de musique conséquents. De nouvelles représentations et de nouveaux algorithmes doivent de ce fait être développés afin de disposer d'une vision représentative de ces catalogues et de naviguer avec agilité dans leurs contenus. Ceci nécessite une caractérisation efficace des morceaux de musique par l'intermédiaire de descriptions macroscopiques pertinentes. Dans cette thèse, nous nous focalisons sur l'estimation de la structure des morceaux de musique : il s'agit de produire pour chaque morceau une description de son organisation par une séquence de quelques dizaines de segments structurels, définis par leurs frontières (un instant de début et un instant de fin) et par une étiquette représentant leur contenu sonore.La notion de structure musicale peut correspondre à de multiples acceptions selon les propriétés musicales choisies et l'échelle temporelle considérée. Nous introduisons le concept de structure "sémiotique" qui permet de définir une méthodologie d'annotation couvrant un vaste ensemble de styles musicaux. La détermination des segments structurels est fondée sur l'analyse des similarités entre segments au sein du morceau, sur la cohérence de leur organisation interne (modèle "système-contraste") et sur les relations contextuelles qu'ils entretiennent les uns avec les autres. Un corpus de 383 morceaux a été annoté selon cette méthodologie et mis à disposition de la communauté scientifique.En termes de contributions algorithmiques, cette thèse se concentre en premier lieu sur l'estimation des frontières structurelles, en formulant le processus de segmentation comme l'optimisation d'un coût composé de deux termes~: le premier correspond à la caractérisation des segments structurels par des critères audio et le second reflète la régularité de la structure obtenue en référence à une "pulsation structurelle". Dans le cadre de cette formulation, nous comparons plusieurs contraintes de régularité et nous étudions la combinaison de critères audio par fusion. L'estimation des étiquettes structurelles est pour sa part abordée sous l'angle d'un processus de sélection d'automates à états finis : nous proposons un critère auto-adaptatif de sélection de modèles probabilistes que nous appliquons à une description du contenu tonal. Nous présentons également une méthode d'étiquetage des segments dérivée du modèle système-contraste.Nous évaluons différents systèmes d'estimation automatique de structure musicale basés sur ces approches dans le cadre de campagnes d'évaluation nationales et internationales (Quaero, MIREX), et nous complétons cette étude par quelques éléments de diagnostic additionnels.
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Ribeiro, Maico Felipe Silva. "Singular Milnor Fibrations." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/55/55135/tde-06072018-115031/.
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In this work we present the most recent developments in the direction of local fibrations structures of analytic singularities. Using techniques and tools from stratification theory we prove structural theorems in the stratified sense, which will be called singular Milnor tube fibration and Milnor-Hamm sphere fibration. In addition, we present algorithms with the purpose of creating a large number of examples in this new setting and compare our results obtained with the current ones found in the literature. Our results generalize all previous result in both cases: in the classical and in the stratified ones.Neste trabalho apresentamos os mais recentes desenvolvimentos na direção de estruturas de fibrações locais de singularidades analíticas. Usando técnicas e ferramentas da teoria de estratificação, provamos alguns teoremas estruturais no sentido estratificado, os quais serão chamados fibração singular de Milnor sobre o tubo e fibração de Milnor-Hamm sobre a esfera. Além disso, apresentamos algoritmos com o intuito de criar uma ampla variedade de exemplos e comparamos nossos resultados com os atuais encontrados na literatura. Nossos resultados generalizam todos os previamente existentes tanto no caso clássico, quanto no sentido estratificado.
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Brites, Alice Dantas. "Monitoramento dos efeitos ecológicos e socioeconômicos da comercialização de produtos florestais não madereiros." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/90/90131/tde-24032011-215203/.
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A comercialização de produtos florestais não madeireiros (PFNMs) popularizou-se como atividade promotora do desenvolvimento socioeconômico de comunidades florestais com baixo impacto ambiental. Há evidências, contudo, de que a exploração possa produzir efeitos ecológicos e socioeconômicos negativos, sugerindo que é necessário monitorar tais iniciativas. A comercialização frequentemente ocorre em áreas remotas e em contextos de pobreza, como é o caso de muitas daquelas da Amazônia brasileira. Desta forma, é necessário que o monitoramento restrinja-se a avaliar os efeitos evidenciados como mais comuns em estudos anteriores. Este estudo revisa e sintetiza as evidências científicas dos efeitos da exploração de PFNMs sobre parâmetros ecológicos e socioeconômicos e, a partir daí, indica aqueles mais relevantes ao monitoramento. O estudo também levanta até que ponto o monitoramento é implementado no contexto da Amazônia brasileira e avalia quais os parâmetros importantes e viáveis de monitoramento neste caso específico. Para isso, foram realizadas revisões sistemáticas da literatura e a consulta a profissionais da área através do método Delphi. Os resultados indicam que efeitos ecológicos negativos são frequentes, principalmente quando se coletam folhas ou cascas. Alterações em órgãos ou processos fisiológicos e a taxa de sobrevivência dos espécimes explorados são parâmetros que devem ser monitorados, em particular quando se coletam frutos e partes vegetativas. Para todos os tipos de PFNMs, o tamanho e a estrutura populacional são parâmetros prioritários ao monitoramento. A riqueza de espécies da comunidade explorada merece atenção, principalmente quando se coletam frutos. Para os aspectos socioeconômicos, efeitos positivos foram mais frequentes que negativos. A contribuição da renda monetária obtida com o comércio na renda total, a regularidade de ingresso desta renda e o papel dos PFNMs como recursos de salvaguarda são parâmetros do capital financeiro prioritários ao monitoramento. Para o capital social, o empoderamento feminino, a coesão de grupo e o acesso aos benefícios gerados pela comercialização devem ser monitorados. Na Amazônia brasileira são poucas as iniciativas de implementação do monitoramento da comercialização de PFNMs. Embora este seja considerado importante, existem dificuldades que derivam principalmente da falta de apoio institucional, políticas de incentivo e de recursos financeiros. Os profissionais participantes do Delphi consideram que os parâmetros ecológicos mais importantes a monitorar neste contexto são o tamanho e a estrutura populacional do recurso explorado, o aumento da taxa de mortalidade, a quantidade total de recurso extraída e a técnica de coleta utilizada. Para os parâmetros econômicos, aspectos do mercado, como o preço pago ao coletor, a demanda e a qualidade do produto, bem como a renda monetária obtida pelos indivíduos são os parâmetros considerados mais importantes. Por fim, para os aspectos sociais, os efeitos na cultura, na qualidade de vida e na organização interna da comunidade foram priorizados. Os profissionais indicam que é viável estabelecer o monitoramento dos parâmetros levantados.Amazon, non-timber forest products, ecological effects, socioeconomic effects, monitoring.
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Pass, Brendan. "Structural Results on Optimal Transportation Plans." Thesis, 2011. http://hdl.handle.net/1807/31893.
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In this thesis we prove several results on the structure of solutions to optimal transportation problems.
The second chapter represents joint work with Robert McCann and Micah Warren; the main result is that, under a non-degeneracy condition on the cost function, the optimal is concentrated on a $n$-dimensional Lipschitz submanifold of the product space. As a consequence, we provide a simple, new proof that the optimal map satisfies a Jacobian equation almost everywhere. In the third chapter, we prove an analogous result for the multi-marginal optimal transportation problem; in this context, the dimension of the support of the solution depends on the signatures of a $2^{m-1}$ vertex convex polytope of semi-Riemannian metrics on the product space, induce by the cost function. In the fourth chapter, we identify sufficient conditions under which the solution to the multi-marginal problem is concentrated on the graph of a function over one of the marginals. In the fifth chapter, we investigate the regularity of the optimal map when the dimensions of the two spaces fail to coincide. We prove that a regularity theory can be developed only for very special cost functions, in which case a quotient construction can be used to reduce the problem to an optimal transport problem between spaces of equal dimension. The final chapter applies the results of chapter 5 to the principal-agent problem in mathematical economics when the space of types and the space of available goods differ. When the dimension of the space of types exceeds the dimension of the space of goods, we show if the problem can be formulated as a maximization over a convex set, a quotient procedure can reduce the problem to one where the two dimensions coincide. Analogous conditions are investigated when the dimension of the space of goods exceeds that of the space of types.
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Chu, Yen-Wei, and 朱彥煒. "Finding Protein Secondary Structure Regularity and Related Applications." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/67312218926236842719.
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博士國立交通大學
資訊科學與工程研究所
94
The author explores protein secondary structure regularity from the perspective of sequences. Regularity is defined in terms of a schema discovered by a cluster-based genetic algorithm. Two steps taken to validate the algorithm were a) finding the weightiness of cluster and b) comparing the approach with data mining methods. Schemata were used to address secondary structure predictions for residues that PSIPRED and PROF could not predict. The results indicate that the proposed schemata can improve prediction accuracy for these residues by approximately 40% and 60% for the CB513 and RS126 data sets, respectively. Furthermore, schemata combine the prediction results of PSIPRED and PROF to improve secondary structure prediction. A bioinformatics teaching plan using a problem-based approach is discussed.
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Ko, Tsung-Hisu, and 柯仲修. "Built-In Self-Test for Regularly Structured Circuits." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/10951418381102750404.
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Ko, Tsung-Hisu. "Built-In Self-Test for Regularly Structured Circuits." 2008. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-3007200816003600.
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Nguyen, Hieu Thao. "Algorithms for structured nonconvex optimization: theory and practice." Doctoral thesis, 2017. http://hdl.handle.net/11858/00-1735-0000-002E-E45C-6.
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Ziegler, Matthew. "Regularly structured design for coping with nanoscale integration complexity /." 2004. http://wwwlib.umi.com/dissertations/fullcit/3144662.
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WEI, CHEN TECK, and 曾大瑋. "Preparation of Silica Microspheres by Sol-Gel Method and Fabrication of Regularly Arrayed, Colloidal Crystal Structure." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/22493125598161497506.
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碩士中國文化大學
材料科學與製造研究所
91
The objectives of this research were two: First, to explore and discuss the synthesized particle diameters by altering reaction temperature condition and reaction time in the preparation of silica microspheres by sol-gel method. Second, we used gravitational sedimentation method, i.e. a bottom-up self-assembly, to obtain regularly arrayed colloidal crystal structure using mono sized SiO2 spherical particles. 1. The preparation of submicron monodispersive silica microspheres by sol-gel method: The synthesis started from tetra-ethyl orthosilicate (TEOS) as precursor, ethanol as reaction solvent, and ammonia solution as catalyst, and processed in basic-catalyzed aqueous medium. After hydrolysis, condensation, cross-linking and gelation reactions, submicron silica microspheres were formed. The synthesis reaction temperature ranged from 0oC~75oC and the reaction time was 2 hours. The particle diameter of the synthesized spheres were analyzed by the particle-size analyser. Experimental results indicated that the size of the synthesized silica microspheres varied from 0.443 mm to 0.625 mm. As the reaction time was increased the diameter of silica microspheres increased (from 0.473 to 0.625mm). As the reaction temperature was increased the diameter of silica microspheres was fond to decrease accordingly (from 0.625 to 0.443mm). 2. Use of mono-sized SiO2 particles for self-assembly of regularly arrayed, colloidal crystal structure: In this work, we used gravitational sedimentation method to assemble SiO2 particles on Si wafer template epitaxially to grow regularly crystal-like structure, and to use the field emission scanning electron microscope (FE-SEM) to observe the packing structure. Experimental results indicated that in different volume fraction (0.5 vol.%~3 vol.%) and sedimentation temperature range (50oC and 100oC, respectively), as the solids fraction was held at 3 vol.% and the sedimentation temperature was 50oC, a larger area (about 250 ´ 250 mm2) of regularly arrayed, colloidal crystal structure was resulted.