Quasi-isotropic (QI) structure for multi-layer fabric panel is believed to be a promising construction to manufacture soft body armour with higher efficiency of ballistic protection based on two hypotheses. The first one is that QI structure panel could involve more secondary yarns in transverse deformation, and the second one is that the more involvement of the secondary yarns could result in the corresponding increase of the energy absorption. However, recent study found that the advantage of QI panel made from Dyneema® woven fabrics was very limited over the aligned panel and potential reasons have not been identified for the lack of systematic studies. Accordingly, this research aims to provide explicit guidance on how to improve the QI structure panels for ballistic protection by studying the mechanisms of aligned and QI panels of multi-layer Dyneema® woven fabrics. The two hypotheses were tested to identify the mechanisms. The ballistic performance of the aligned and QI panels of 2-layer, 3-layer and 4-layer Dyneema® woven fabrics were experimentally investigated using a ballistic test apparatus and a panel clamping system to evaluate the energy absorption of specimens. In order to further study the response of the ballistic panel, a yarn-level Dyneema® woven fabric model was developed. The shear moduli of the yarn (G13 and G23) was found to be the most important elastic constants in simulating ballistic fabrics using orthogonal experiments in this study, and were identified to 0.27GPa and 0.80GPa. The model was agreeably validated by comparing the FE modelling results of multi-layer panels under ballistic impact with the experimental counterparts. Based on this validated model, the areas, shapes of the transverse deformation bases were specifically evaluated. The first hypothesis was verified that the areas of the deformation bases of the back layer fabrics in QI panels of 2-layer, 3-layer, and 4-layer fabric models were more than 10% larger than the areas of the corresponding parts in aligned panel models, especially at medium and late stages. Moreover, the increases of the areas were attributed to the more involvements of the secondary yarns in the deformation, and more circular shapes of the deformation bases of the fabrics in QI panels were identified by using a mathematic measurement method created in this study. The kinetic energy (KE) and total strain energy (IE) evolution of primary yarns and secondary yarns in two panels were further specified. It was found that altering the aligned panel to QI panel not only changed the energy absorption of secondary yarns, also significantly changed that of primary yarns. This indicated that the second hypothesis was not suitable for the cases of panels of the Dyneema® woven fabrics for the influence of the primary yarns after the panel structure changed were neglected. The reason of the alterations of the primary yarns was that the slip-off time or failure time of most primary yarns was changed. The morphology evolution of primary yarns in 2-layer aligned and QI panels were investigated and the results showed that the space between adjacent warp or weft primary yarns and the interactions between some primary yarns and the adjacent primary yarns in another layer significantly affected the slip-off time and failure time of most primary yarns. The influence of these two factors derived from the feature of woven fabrics, which was the crimp. In order to verify the new understanding of the QI ballistic panels from the numerical analysis, a non-crimp fabric, namely Dyneema® SB51, was used to investigate the ballistic performance of the aligned and QI panels. It was found that the energy taken by QI panels was approximately 25% higher than the energy taken by the corresponding aligned panels. This result verifies the analysis conclusion and paves the solid way for further investigation of QI structure panels made up of biaxial fabrics.

This research investigates composite tubes developed with hybrid preform manufacturing techniques of braiding and filament winding (FW). A quadriaxial braid-wound (QBW) preform [(±45°/0°/90°)2/(±45°/0°)] and a triaxial braided (TB60) preform [(±60°/0°)3] were developed. Quasi-isotropic (QI) fibre orientations were selected for both the lay-ups for comparison of mechanical properties. The large diameter of the tubes led to incomplete surface coverage with (±45°/0°)3 braided preforms (TB45). Circumferential distribution of multiple layers improved the coverage by reducing through the thickness resin pockets. Also addition of hoop winding improved the coverage and consolidated the braided preform. The use of braiding together with FW resulted in an improved fibre volume fraction. Also predicting surface coverage was a fundamental interest for a triaxial braided preform. An equation was proposed for cover factor estimation and was verified by using image analysis. Resin infusion of the preforms was carried out and composite tubes were fabricated. During resin infusion of braided preforms wrinkles were formed. A brief study on wrinkle formation was carried out and the reasons of wrinkle formation for braided tubes were identified based on existing literature. Longitudinal tensioning in conjunction with optimization of fibre amount in a layup and over-winding on braid was established to minimize wrinkle formation. This was primarily due to compaction of braided layers with hoop winding. Hence braid-winding has the additional advantage of manufacturing wrinkle free composite tubes. Finally composite tubes were tested under tension and torsion loads. One of the major findings was the effect of hoop winding on transverse deformation of the braid-wound tubes. As axial fibre percentage for QBW tube was less than that of TB45, the tensile strength was compromised. However presence of hoop winding resulted in lower transverse strain contributing to higher tensile modulus of QBW tubes along with lower Poisson's ratio. Although shear modulus of TB60 tube was exceptionally high for its fibre orientation, for QBW tubes, shear modulus was not significantly higher than that of other tubes. An aluminium tube was also tested for comparing the elastic properties of the QI tubes with those of an isotropic material. QBW tubes specific modulus was higher than that of the aluminium. The shear modulus of the QI and aluminium tubes was estimated by applying the theory for isotropic materials. In comparison to aluminium, for QBW tube the differences between estimated and actual shear modulus was higher. However QBW tube properties were in closer relation to those of the aluminium tube than TB60 tubes. Hence a QBW hybrid layup technique has the potential for manufacturing composite tubes without losing comparative composite material properties.

La thèse contient 6 chapitres. Le premier chapitre contient une introduction à la régression linéaire et aux problèmes Lasso et Lasso bayésien. Le chapitre 2 rappelle les algorithmes d’optimisation convexe et présente l’algorithme FISTA pour calculer l’estimateur Lasso. La statistique de la convergence de cet algorithme est aussi donnée dans ce chapitre en utilisant l’entropie et l’estimateur de Pitman-Yor. Le chapitre 3 est consacré à la comparaison des méthodes quasi-Monte Carlo et Monte Carlo dans les calculs numériques du Lasso bayésien. Il sort de cette comparaison que les points de Hammersely donne les meilleurs résultats. Le chapitre 4 donne une interprétation géométrique de la fonction de partition du Lasso bayésien et l’exprime en fonction de la fonction Gamma incomplète. Ceci nous a permis de donner un critère de convergence pour l’algorithme de Metropolis Hastings. Le chapitre 5 présente l’estimateur bayésien comme la loi limite d’une équation différentielle stochastique multivariée. Ceci nous a permis de calculer le Lasso bayésien en utilisant les schémas numériques semi implicite et explicite d’Euler et les méthodes de Monte Carlo, Monte Carlo à plusieurs couches (MLMC) et l’algorithme de Metropolis Hastings. La comparaison des coûts de calcul montre que le couple (schéma semi-implicite d’Euler, MLMC) gagne contre les autres couples (schéma, méthode). Finalement dans le chapitre 6 nous avons trouvé la vitesse de convergence du Lasso bayésien vers le Lasso lorsque le rapport signal/bruit est constant et le bruit tend vers 0. Ceci nous a permis de donner de nouveaux critères pour la convergence de l’algorithme de Metropolis Hastings. / The thesis contains 6 chapters. The first chapter contains an introduction to linear regression, the Lasso and the Bayesian Lasso problems. Chapter 2 recalls the convex optimization algorithms and presents the Fista algorithm for calculating the Lasso estimator. The properties of the convergence of this algorithm is also given in this chapter using the entropy estimator and Pitman-Yor estimator. Chapter 3 is devoted to comparison of Monte Carlo and quasi-Monte Carlo methods in numerical calculations of Bayesian Lasso. It comes out of this comparison that the Hammersely points give the best results. Chapter 4 gives a geometric interpretation of the partition function of the Bayesian lasso expressed as a function of the incomplete Gamma function. This allowed us to give a convergence criterion for the Metropolis Hastings algorithm. Chapter 5 presents the Bayesian estimator as the law limit a multivariate stochastic differential equation. This allowed us to calculate the Bayesian Lasso using numerical schemes semi-implicit and explicit Euler and methods of Monte Carlo, Monte Carlo multilevel (MLMC) and Metropolis Hastings algorithm. Comparing the calculation costs shows the couple (semi-implicit Euler scheme, MLMC) wins against the other couples (scheme method). Finally in chapter 6 we found the Lasso convergence rate of the Bayesian Lasso when the signal / noise ratio is constant and when the noise tends to 0. This allowed us to provide a new criteria for the convergence of the Metropolis algorithm Hastings.

Neste trabalho à feita uma revisÃo das principais propriedades da molÃcula de poliacetileno sob o ponto de vista da teoria de campos. A seguir, estuda-se duas cadeias de poliacetileno acopladas usando o mesmo formalismo e verifica-se que esse sistema apresenta um gap em sua estrutura de bandas. Esse gap de energia à calculado em termos de uma massa efetiva quantizada que depende do acoplamento entre as cadeias de poliacetileno. Quando o acoplamento cessa o gap desaparece e recupera-se o resultado prÃvio de uma simples cadeia nÃo dimerizada. Mostra-se que entÃo hà uma quebra da simetria quiral. O comportamento do poliacetileno acoplado tambÃm à analisado quando existem sÃlitons em sua estrutura. Um formalismo à desenvolvido para mostrar que hà um fenÃmeno oscilatÃrio de natureza quÃntica anÃlogo Ãs oscilaÃÃes de Bloch. A condutividade do sistema à tambÃm calculada. / We review in this work the principal properties of single polyacetylene chain from a theoretical field formalism. Then, we study a coupled polyacetylene chain using the same formalism and verify that this system presents a gap in its electronic band structure. This energy gap is calculated in terms of a quantized effective mass that depends on the coupling between the polyacetylene chains. As the coupling decreases the gap vanishes and we restore the previous results of one single polyacetylene chain not dimerized. We show that there is a chiral broken symmetry. We study also the behavior of coupled polyacetilene in presence of solitons. A formalism is developed to show that there is an oscillatory phenomenon of quantum character analogous to Bloch oscillations. The conductivity of the system is also calculated.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Investigamos os efeitos da interaÃÃo spin-Ãrbita do tipo Rashba e do tipo Dresselhauss e de um potencial com modulaÃÃo periÃdica unidimensional sobre as propriedades fÃsicas de um gÃs de elÃtrons bidimensional, na presenÃa de um campo magnÃtico externo constante e inclinado com respeito a direÃÃo de confinamento. O sistema à caracterizado pelos parÃmetros que determinam a intensidade e direÃÃo do campo magnÃtico, as intensidades das interaÃÃes Rashba e Dresselhaus, a intensidade e periodicidade do potencial e o nÃmero de partÃculas por mÂ. SoluÃÃes da equaÃÃo de SchrÃdinger foram obtidas para diferentes conjuntos de parÃmetros, o que nos permitiu a obtenÃÃo da densidade de estados e energia de Fermi do sistema para cada conjunto. A obtenÃÃo destes resultados possibilitou a anÃlise das condutividades Hall, colisional e difusiva, a energia livre e a magnetizaÃÃo na direÃÃo do campo em funÃÃo da inclinaÃÃo e do mÃdulo do campo externo e a analise da importÃncia relativa da interaÃÃo Zeeman, da interaÃÃo spin-Ãrbita e da modulaÃÃo periÃdica unidimensional sobre estas propriedades. Observamos modulaÃÃes na densidade de estados devidas à interaÃÃo spin-Ãrbita. Este comportamento tambÃm à observado no comportamento dos observÃveis que dependem das variÃveis dinÃmicas do sistema. AlÃm disso, tambÃm observamos que a condutividade Hall à quantizada no caso da ausÃncia da modulaÃÃo periÃdica, interaÃÃo spin-Ãrbita e campo paralelo à direÃÃo de crescimento, podendo assumir somente valores mÃltiplos de eÂ/h. Na presenÃa de uma componente do campo paralela a regiÃo em que o gÃs se encontra confinado ou da interaÃÃo spin-Ãrbita, surgem plateaus intermediÃrios (2n+1)eÂ/(2h) entre quaisquer plateaus de ordem n e n+1. Ao se incluir a modulaÃÃo periÃdica, a condutividade Hall passa a ter valores contÃnuos entre dois plateaus quaisquer. TambÃm obtivemos que a modulaÃÃo periÃdica torna nÃo-nula a contribuiÃÃo da difusÃo para a condutividade.

Dissertação (Mestrado em Engenharia Mecânica) - Centro Universitário FEI, São Bernardo do Campo, 2016.

Nous développons des modèles probabilistes pour l’impression à l’échelle micrométrique. Tenant compte de l’aléa de la forme des points qui composent les impressions, les modèles proposés pourront être ultérieurement exploités dans différentes applications dont l’authentification de documents imprimés. Une analyse de l’impression sur différents supports papier et par différentes imprimantes a été effectuée. Cette étude montre que la grande variété de forme dépend de la technologie et du papier. Le modèle proposé tient compte à la fois de la distribution du niveau de gris et de la répartition spatiale de l’encre sur le papier. Concernant le niveau de gris, les modèles des surfaces encrées/vierges sont obtenues en sélectionnant les distributions dans un ensemble de lois de forme similaire aux histogrammes et à l’aide de K-S critère. Le modèle de répartition spatiale de l’encre est binaire. Le premier modèle consiste en un champ de variables indépendantes de Bernoulli non-stationnaire dont les paramètres forment un noyau gaussien généralisé. Un second modèle de répartition spatiale des particules d’encre est proposé, il tient compte de la dépendance des pixels à l’aide d’un modèle de Markov non stationnaire. Deux méthodes d’estimation ont été développées, l’une approchant le maximum de vraisemblance par un algorithme de Quasi Newton, la seconde approchant le critère de l’erreur quadratique moyenne minimale par l’algorithme de Metropolis within Gibbs. Les performances des estimateurs sont évaluées et comparées sur des images simulées. La précision des modélisations est analysée sur des jeux d’images d’impression à l’échelle micrométrique obtenues par différentes imprimantes. / We develop the probabilistic models of the print at the microscopic scale. We study the shape randomness of the dots that originates the prints, and the new models could improve many applications such as the authentication. An analysis was conducted on various papers, printers. The study shows a large variety of shape that depends on the printing technology and paper. The digital scan of the microscopic print is modeled in: the gray scale distribution, and the spatial binary process modeling the printed/blank spatial distribution. We seek the best parametric distribution that takes account of the distributions of the blank and printed areas. Parametric distributions are selected from a set of distributions with shapes close to the histograms and with the Kolmogorov-Smirnov divergence. The spatial binary model handles the wide diversity of dot shape and the range of variation of spatial density of inked particles. At first, we propose a field of independent and non-stationary Bernoulli variables whose parameters form a Gaussian power. The second spatial binary model encompasses, in addition to the first model, the spatial dependence of the inked area through an inhomogeneous Markov model. Two iterative estimation methods are developed; a quasi-Newton algorithm which approaches the maximum likelihood and the Metropolis-Hasting within Gibbs algorithm that approximates the minimum mean square error estimator. The performances of the algorithms are evaluated and compared on simulated images. The accuracy of the models is analyzed on the microscopic scale printings coming from various printers. Results show the good behavior of the estimators and the consistency of the models.

Dans cette thèse, nous nous intéressons à la mécanique statistique d’une classe d’écoulements “quasi-bidimensionnels”. Nous nous penchons plus particulièrement sur le cas des écoulements tri-dimensionnels axisymétriques, bidimensionnels stratifiés et bidimensionnels magnéto hydrodynamiques. La dynamique de ces écoulements est génériquement décrite par les équations d’évolution d’un champ de vitesses incompressible bidimensionnel,couplées à une équation d’évolution d’un champ scalaire. Ce dernier représente tantôt une température, tantôt un courant électrique, tantôt un mouvement tourbillonnaire transverse. Ces écoulements ont un intérêt géophysique ou astrophysique : ils peuvent être utilisés pour modéliser grossièrement les ouragans, les courants océaniques à l’échelle planétaire, les taches solaires, etc. Ils ont aussi un intérêt plus fondamental.Malgré leur géométrie bidimensionnelle intrinsèque, les écoulements “2D3C” peuvent être en effet tri-dimensionnellement connotés. Dans les cas que l’on regarde, la vorticité n’est pas seulement transportée : elle est aussi étirée. Il n’est ainsi pas évident de savoir si la tendance naturelle des écoulements 2D3C est de s’organiser en structures cohérentes énergétiques à grande échelle comme en deux dimensions, ou plutôt de répartir leur énergie sur les petites échelles comme en trois dimensions. Il n’est a priori pas clair nonplus de savoir si une forme d’énergie (cinétique ou magnétique/tourbillonnaire) y est privilégiée aux dépends de l’autre.Pour répondre à ces questions de manière très générale, nous étudions et décrivons la mécanique statistique d’équilibre des écoulements 2D3C sus-mentionnés, en nous plaçant d’abord dans le cadre des “ensembles d’équilibre absolu” considérés par Robert Kraichnan à la fin des années 1960, puis dans le cadre plus moderne des “mesures microcanoniques stationnaires” introduites par Raoul Robert, Jonathan Miller et Joël Sommeria pour les fluides bidimensionnels au début des années 1990. Les équilibres 2D3C sont décrits dans la première partie de ce manuscript. La seconde partie du manuscript est plus pratique, et également plus spéculative. Nous nous servons d’ outils de la mécanique statistique d’équilibre pour interpréter des données turbulentes expérimentales provenant d’expériences de type Von Kármán . Nous utilisons ensuite des résultats récents de théorie de probabilité pour montrer que des régimes de turbulence quasi-bidimensionnelle (turbulence tri-dimensionnelle avec rotation,turbulence dans des couches savonneuses) ont des propriétés d’invariance conforme statistique, analogues à celles observées dans des systèmes de spins ferromagnétiques au point critique. / The present manuscript deals with the statistical mechanics of some inviscid fluidmodels which are possibly relevant in the context of geophysics and astrophysics. Weinvestigate the case of axially symmetric flows, two-dimensional Boussinesq flows, andtwo-dimensional magneto-hydro fluids. Those flows can be loosely referred to as twodimensionalflows with three components (“2D3C”). In addition to the two-dimensionalvelocity field, they describe the evolution of an additional field variable, which representseither a magnetic current, a salinity, a temperature or a swirl depending on the situation.In common with the dynamics of strictly two-dimensional hydrodynamical flows, thenon-linear dynamics of 2D3C flows is constrained by the presence of an infinite numberof Casimir invariants, which emerge as dynamical invariants in the limit of a vanishingforcing and a vanishing dissipation . In common with three-dimensional flows, the vorticityis not only mixed but also stretched by the dynamics. The additional field may actas a source or a sink of kinetic energy. It is commonly believed that such flows have thepropensity to develop large scale coherent structures. Whether those long lived structuresare equilibrium or metastable structures is however not so clear, nor are the exactconditions of their emergence. The role of the Casimir invariants in constraining those isnot so obvious either.

O modelo de referência para dados de contagem é o modelo de Poisson. A principal característica do modelo de Poisson é a pressuposição de que a média e a variância são iguais. No entanto, essa relação de média-variância nem sempre ocorre em dados observacionais. Muitas vezes, a variância observada nos dados é maior do que a variância esperada, fenômeno este conhecido como superdispersão. O objetivo deste trabalho constitui-se na aplicação de modelos lineares generalizados, a fim de selecionar um modelo adequado para acomodar de forma satisfatória a superdispersão presente em dados de contagem. Os dados provêm de um experimento que objetivava avaliar e caracterizar os parâmetros envolvidos no florescimento de plantas adultas da laranjeira variedade \"x11\", enxertadas nos limoeiros das variedades \"Cravo\" e \"Swingle\". Primeiramente ajustou-se o modelo de Poisson com função de ligação canônica. Por meio da deviance, estatística X2 de Pearson e do gráfico half-normal plot observou-se forte evidência de superdispersão. Utilizou-se, então, como modelos alternativos ao Poisson, os modelos Binomial Negativo e Quase-Poisson. Verificou que o modelo Quase-Poisson foi o que melhor se ajustou aos dados, permitindo fazer inferências mais precisas e interpretações práticas para os parâmetros do modelo. / The reference model for count data is the Poisson model. The main feature of Poisson model is the assumption that mean and variance are equal. However, this mean-variance relationship rarely occurs in observational data. Often, the observed variance is greater than the expected variance, a phenomenon known as overdispersion. The aim of this work is the application of generalized linear models, in order to select an appropriated model to satisfactorily accommodate the overdispersion present in the data. The data come from an experiment that aimed to evaluate and characterize the parameters involved in the flowering of orange adult plants of the variety \"x11\" grafted on \"Cravo\" and \"Swingle\". First, the data were submitted to adjust by Poisson model with canonical link function. Using deviance, generalized Pearson chi-squared statistic and half-normal plots, it was possible to notice strong evidence of overdispersion. Thus, alternative models to Poisson were used such as the negative binomial and Quasi-Poisson models. The Quasi-Poisson model presented the best fit to the data, allowing more accurate inferences and practices interpretations for the parameters.

abstract: 近20年,中国品牌零售业的快速发展使其成为全球第三大零售市场。消费者的需求量在大幅增长，对于本土企业来说，机遇与挑战并存。 对于连锁型品牌零售企业，员工是其产品和服务的载体。而如何做好不同层次的人员的激励体系，并得以踏实的落实和执行，是企业经营中非常关键的环节，也是品牌零售企业在竞争中获取优势的根本保证。另外，由于连锁零售企业基层员工流动性大、总体素质较低，如何对这部分员工实施有效的绩效考核,成为很多连锁零售企业管理人员面临的一个难题。 本文将长期和短期激励作为主要的研究内容。从整体国内企业来看，运转良好的绩效考评体系并不多，大部分企业的绩效考评体系只注重短期激励而忽视了长期激励的作用，绩效考评关注的是目标的实现，与员工的发展相脱节。因此，如何做好品牌企业的激励体系，如何在人才竞争中取得先机，并最大化企业利润，是本文研究的重心。 目前的研究空白在于对连锁型店铺的激励绩效。而考虑到品牌零售中的连锁经营往往涉及到成百上千家门店，涉及到的从业人数较多，因而对门店的激励绩效的成败是关系到企业整体激励绩效好坏的关键。 本文对激励绩效方案的相关理论进行回顾、分析与总结，从委托代理理论、激励理论、交易成本理论和产权理论入手，分析连锁型品牌零售企业的激励绩效特点。连锁型品牌零售企业合伙制本质上与特许经营精神及设计理念一致，而想要改进的正是特许经营中加盟店与总部的博弈与消耗，形成利益共同体，达到企业价值最大化的目标。 通过连锁型品牌零售企业绩效激励的真实案例（永辉超市合伙人制度、拉夏贝尔店铺合伙人制度、康奈零投入型与交股金型两种店铺合伙人制度）分析得出风险共担、超额利润分成的合伙人制度在连锁型品牌零售企业激励绩效方案设计中的可行性及意义，并从中发现了已有实践存在的问题，并提出建议。 店铺合伙人制度激励店长、提高单店销售业绩、减少交易成本、提高管理效率的正向作用毋庸置疑，建议在实践中积极推行与完善。 / Dissertation/Thesis / Doctoral Dissertation Business Administration 2019