State of the art thermal barrier coatings (TBCs) for gas turbine applications comprise (7 wt.%) yttria partially stabilized zirconia (7YSZ). 7YSZ offers a range of attractive functional properties – low thermal conductivity, high thermal expansion coefficient and high in-plane strain tolerance. However, as turbine entry temperatures are raised, the performance of 7YSZ coatings will be increasingly affected by sintering and environmental contamination, by calcia-magnesia-alumina-silica (CMAS) deposits. The effect of sintering-induced stiffening on the driving force for spallation of plasma-sprayed (PS) TBCs was investigated. Spallation lifetimes of TBC specimens sprayed onto alumina substrates were measured. A simple fracture mechanics approach was employed in order to deduce a value for the strain energy release rate. The critical strain energy release rate was found to be constant, and if this value had been known beforehand, then the rationale presented here could be used for prediction of coating lifetime. The effect of vermiculite (VM) and volcanic ash (VA) contamination on the sintering-induced spallation lifetime of PS TBCs was also investigated. The presence of both VM and VA was found to accelerate the rise in their Young’s modulus with sintering. Spallation results show that coating lifetime may be significantly reduced, even at relative low addition levels, due to the loss of strain tolerance caused by the penetration of glassy deposits. This result gives a clear insight into the role CMAS plays in destabilizing TBCs. Finally, the adhesion characteristics of ingested volcanic ash were studied using a small jet engine. The effects of engine speed and particle size were investigated. Deposition on turbine surfaces was assessed using a borescope. Deposition mainly occurred on the nozzle guide vane and blade platform. A numerical model was used to predict particle acceleration and heating in flight. It was observed that larger particles are more likely to adhere because they have greater inertia, and thus are more likely to impact surfaces. The temperature of the larger particles at the end of its flight was predicted to be below its softening point. However, since the component surface temperatures are expected to be hotter, adhesion of such particles is probable, by softening/melting straight after impact.

La prédiction des durées de vie des pièces de structures aéronautiques a toujours été une problématique à la fois complexe et capitale dans ce domaine de l’industrie. Néanmoins, la majorité des tests existant à l’heure actuelle cherche à évaluer la capacité des matériaux à résister aux sollicitations mécaniques notamment en fatigue. Les problématiques liées à l’endommagement causé par l’environnement comme la corrosion sont encore mal comprises. En effet, bien que certains tests permettent de détecter et de caractériser cet endommagement, aucun outil fiable de prédiction des vitesses de propagation des défauts de corrosion intergranulaire n’existe. Ainsi, actuellement, un défaut de corrosion détecté induit systématiquement un changement de la pièce. Les travaux de cette thèse s’inscrivent dans cette problématique ; ils ont pour but de comprendre les phénomènes de corrosion intergranulaire sur l’alliage d’aluminium 2024, le plus utilisé dans le secteur aéronautique, et d’étudier les cinétiques de propagation des défauts de corrosion. L’étude s’appuie sur une approche multi-échelle des processus de corrosion, des états microstructuraux et de l’influence de l’hydrogène. Ce projet s’inscrit également dans une dynamique de collaboration avec Airbus Group et l’Université de Bourgogne dans le cadre du projet ANR M-SCOT (Multi-Scale Corrosion Testing ANR-14-CE07-0027-01). / Nowadays, cracks kinetics is a key point in aircraft risk and reliability analysis. In particular, the propagation of corrosion defects is of special interest and could promote an early mechanical crack initiation. However, today most of the tests are calibrated to control mechanical damage and do not take into account the propagation of the corrosion defects. Indeed, when a corrosion defect is observed, the airplane part is automatically changed which leads to high manufacturing costs. The aim of this work is to understand the intergranular corrosion mechanisms and to study the propagation kinetics of the corrosion defects in an aeronautical reference alloy, i.e. the 2024-T351 aluminium alloy. A multiscale approach of the corrosion processes, the microstructural states as well as hydrogen influence was performed. This work is supported by ANR-14-CE07-0027-01 – M-SCOT: Multi Scale COrrosion Testing.

The main goal of the diploma thesis is the description and comparison of existing methods for calculating the customer lifetime value at a firm. Second, minor goal is based on the comparison to choose a suitable method of calculation for an application in a real business unit. The used methodology contains detailed research of available foreign academic literature. Building on that a comparison of the methods based on selected criteria is conducted. Results of a questionnaire survey are used in the last chapter to provide specific sugestions for the possible marketing applications of CLV approach and calculation in a specific business unit.

This thesis deals with another possible approach to segmentation of the customer base in the surveyed company than the one currently used. Specifically, the issue of lifetime customer value is discussed. A review shows several possible approaches and some selected models will be applied to the customer base in the practical part of thesis. Work addresses not only the application of selected models, but especially the comparison of analysis results with the original segmentation. The aim is to track changes in segmentation after applying these models and provide the proof that this metric is an appropriate evaluation component in segmentation for a particular company. An integral part are therefore recommendations for management and sales representatives. Calculations are performed in Excel. At the end of each chapter are specific achievements and comparisons with the initial segmentation. The result of this work is to suggest several models of customer lifetime value calculation that the company may apply to benefit from when creating a new segmentation model.

Spectrum efficiency and energy efficiency are two important attributes driving innovation in wireless communication. Efficient spectrum utilization and sharing with multiple access techniques and using under-utilized spectra by cognitive radios is the current focus due to the scarcity and cost of the available radio spectrum. Energy efficiency to increase operating time of portable handheld devices like smartphones that handle simultaneous voice/video streaming and web browsing and battery powered nodes in a sensor network where battery capacity determines the lifetime of the network is another area attracting researchers. The focus of this thesis is the spectral efficiency of multicarrier code division multiple access (CDMA) in wireless ad-hoc networks. Furthermore, energy efficiency to maximize lifetime of a network are also studied.In a multicarrier CDMA system inter-carrier interference (ICI) due to carrier frequency offset and multiple access interference (MAI) are two major factors that deteriorate the performance. Previous work in this area has been mostly focused on simulation results due to the complexity of the analysis due to the large number of random variables involved. Taking into account accurate statistical models for ICI and MAI that account for the correlation between adjacent subcarriers, this thesis presents new mathematical analysis for the spectral efficiency of multicarrier CDMA communication systems over a frequency selective Rayleigh fading environment. We analyze and compare three multicarrier CDMA schemes which are multicarrier CDMA, multicarrier direct-sequence CDMA and multitone CDMA. We also present simulation results to confirm the validity of our analysis. We also analyze the performance of three simple multiple access techniques or coexistence etiquettes in detail, which are simple to implement and do not require any central control. Accurate interference models are developed and are used to derive accurate expressions for packet error rates in the case of direct sequence CDMA and slotted packet transmission schemes. These results are then used to study the performance of the coexistence etiquettes and compare them with each other. Finally we present a new joint node selection and power allocation strategy that increases lifetime of an ad-hoc network where nodes cooperate to enable diversity in transmission.

Les conditions de fonctionnement rencontrées dans la problématique de nouvelles générations d'alternateurs automobiles avec des chargements variables et un environnement mécanique complexe déformable ont un effet non négligeable sur le comportement mécanique du roulement et par conséquent sur sa durée de vie. Il est proposé dans ce travail une approche permettant de prendre en compte ces paramètres dans l'estimation de la durée de vie des roulements. La répartition des efforts obtenue des considérations statiques sont utilisés dans un modèle dynamique simplifié permettant de déterminer de l'état de contrainte au cours du temps dû au passage de billes sur la piste de roulement. L'approche multi-échelle de Dang Van couplée à une loi de cumul d'endommagement a permis de déterminer le nombre de cycles avant l'apparition des premiers signes de fatigue. La dernière phase du travail concerne l'aspect expérimental qui a montré que le phénomène de fatigue n'est pas la seule cause de dégradation des roulements montés dans les alternateurs automobiles. / The operating conditions encountered in the new generations of automotive alternators with variable loads and a deformable complex mechanical environment have a significant effect on the mechanical behavior of the bearing and hence its fatigue lifetime. An approach that takes into account these parameters in the ball bearing fatigue lifetime has been proposed in this work. The load distribution obtained from static considerations are used in a simplified dynamic model in order to determine the time-dependent stress state due to ball rolling on the raceway. The Dang Van multiscale approach coupled with a damage law was applied to determine the number of cycles before the apparition of the first signs of fatigue. The last phase of work involves the experimental aspect that shows that the fatigue phenomenon is not the only cause of degradation of bearings mounted in automotive alternators.

This Diploma thesis deals with measuring the effectiveness of marketing investments on the real model used by Royal Philips Electronics. Firstly, on the basis of qualitative research conducted through semi-structured personal interviews with marketing managers in Philips and participation in two marketing projects in the company, it determines the advantages, disadvantages and restrictive elements of the current model. Then in the theoretical context, it is compared with the practices of other companies which are one of the conclusions of the qualitative interviews. The result is a proposal of current model's improvements of measuring ROI marketing investments.

A questão da produtividade das atividades de marketing é um antigo debate da disciplina, porém ganhou destaque nos anos 1990 a partir de uma conjuntura que propiciou questionamentos sobre a eficácia e eficiência dos departamentos de marketing das empresas. Argumentou-se que o marketing deveria ir além das métricas tradicionais e explicitar as consequências de marketing para todos os stakeholders. Nesse sentido, os conceitos de customer equity e customer lifetime value têm se mostrado promissores em fazer a conexão marketing-finanças a partir de uma série de estudos iniciados nos anos 1990. Desde então foram elaboradas inúmeras modelagens a fim de mensurar a contribuição das ações de marketing empiricamente. De fato, evidências apontam para uma real contribuição de marketing dentro da empresa, seja pelo valor da marca, da clientela, da satisfação, lealdade entre outros. No entanto, a diversidade de modelos pode significar um entrave na padronização de cálculo e não existem pesquisas que estudem o impacto do modelo escolhido nos resultados da estimação nem sua implicação para tomada de decisão. A presente tese visou investigar até que ponto existe modelo dependência na estimação do customer equity e customer lifetime value, já que os resultados impactam diretamente na estratégia a ser utilizada pela gerência e, consequentemente, no desempenho da empresa A partir da classificação dos modelos foram comparados aqueles chamados de determinísticos, um grupo de modelos com características semelhantes e implementação simplificada. Os resultados indicam que, no caso da utilização do customer equity para avaliação financeira da empresa a estimação apresenta grande variabilidade, o que indica modelo dependência e a necessidade de aprofundamento metodológico, principalmente em negócios com alta heterogeneidade de margens e retenções. O ciclo de vida do cliente, por sua vez apresenta modelo dependência no que diz respeito a estratégia gerencial para maximizar o mesmo, sendo a seguinte: nos modelos de projeção infinita a retenção de clientes apresenta “prêmio” crescente no ciclo de vida esperado, enquanto que margens de contribuição tem peso maior em ambientes com retenção menor que 50% aproximadamente. Modelos com projeção finita, no entanto, não apresentam essa característica, sendo a retenção sempre a causar maior impacto marginal no valor do ciclo de vida esperado. Esses resultados fornecem evidências para concluirmos que existe modelo dependência na estimação de tais métricas. / The marketing productivity is an old debate in the field and has gained substantial attention since 1990’s as a product of a context that raised questions about the real contribution of marketing, its efficiency and efficacy. Managers argued that marketing should demonstrate its effects beyond traditional metrics and making them available to all business’ stakeholders. In this sense, customer equity and customer lifetime value has been used to make the connection between marketing and finance by 1990’s until now. In fact, research has shown that marketing contributes to firm value by elevating brand equity, customer loyalty and satisfaction, customer equity, among others. However, the large number of customer equity and customer lifetime models can be a difficulty on finding standard methodology, and there are no studies that compare model’s impact on results. This study aims to investigate the dependency of the models in estimating customer equity and customer lifetime value and its consequence on strategy adoption by managers. Starting from a classification proposal, a group of deterministic models were chosen to be compared. Results show that using customer equity for valuation purposes is model dependent, since models present great estimation variability, especially in a heterogeneous context. Customer lifetime value does produce divergent strategies and has model dependency as well: on models of infinite projection retention rates have increasing effect on expected customer lifetime values, but margins are preferred until a retention threshold of fifty percent. This does not occur within a model with finite projection, which retention rates has always more impact than margins. The sum of this results offer evidence that, indeed, model dependency on estimating customer equity and customer lifetime value exists.

The purpose of this study was to develop an instrument that measures self-efficacy perceptions of physical educators towards teaching lifetime physical activities. This Physical Educator Efficacy Scale for Teaching Lifetime Physical Activities (PEES-LPA), was validated through expert review, and pilot procedures, and exploratory factor analysis (EFA). EFA revealed a six-factor model that accounted for 67.8% of the total observed score variance (PAF extraction/Varimax rotation). Additionally, results demonstrated: (a) factors showing simple structure that aligns with related literature, (b) high factor scores (>.40) with no double loadings, (c) efficacy items relating to Net/Wall activities and Target activities loading together, and (d) internal consistency showed to be very high for both the full model (.95) and each individual factor (.92-.95). The PEES-LPA appears demonstrate accptable reliability and validity, though further analysis needs be explored for items that may influence multicollinearity and normality.

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