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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
361

Estimación del Valor de Clientes Fidelizados en una Cadena de Supermercados Utilizando Modelos Jerárquicos Bayesianos

Reuse Tello, Felipe Ignacio January 2011 (has links)
El presente trabajo nace del interés por conocer qué tan rentables son los clientes de un supermercado, considerando dinámicas particulares en su comportamiento de compra. Tiene por objetivo principal estimar el valor de los consumidores utilizando la métrica Customer Lifetime Value (CLV), herramienta importante que permite tomar decisiones de marketing más focalizadas. Hasta el momento se han desarrollado algunos trabajos que utilizan modelos econométricos para estimar los montos futuros a gastar por el cliente, pero siempre asumiendo cierta homogeneidad. El principal desafío de esta memoria está en considerar la heterogeneidad que existe en el comportamiento de éstos, para así obtener un CLV a nivel individual. Esto se logra mediante una Regresión Jerárquica Bayesiana, la cual permite obtener parámetros específicos para cada uno de ellos, utilizando tanto la información particular, como también la global de toda la población. De esta manera, se logra captar dinámicas y tendencias particulares del comportamiento de compra individual. La Regresión Jerárquica Bayesiana logra reducir en un 50% el error de predicción incurrido en la Regresión Lineal Grupal, donde este último modelo asume homogeneidad entre los clientes. El ajuste promedio es de buena calidad, ya que explica el 65% de la varianza. El nuevo modelo utilizado permite que las variables para estimar los montos futuros sean significativas, a diferencia de una Regresión Lineal Individual. En este último caso, la baja cantidad de observaciones por cliente impide obtener resultados significativos. Una vez calculado el CLV para el año de pronóstico, se forman Quintiles de clientes, donde los superiores tienen un valor promedio de $911.375, aportando el 45% de la contribución total del supermercado. Por su parte, los menos valiosos tienen un CLV promedio de $75.456, aportando solo el 4% de las ganancias. La principal característica de los clientes más valiosos, es que son bastante inteligentes para comprar, ya que captan fuertemente las promociones ofrecidas. Las acciones de marketing propuestas fueron realizadas para 3 de los grupos formados. El primer Quintil corresponde al grupo constituido mayormente por jóvenes, y el objetivo de las acciones es aumentar su monto y frecuencia de compra. Los Quintiles 4 y 5 corresponden a los grupos con mayor valor, y por lo mismo los esfuerzos se enfocan en potenciar la relación futura con la compañía. Como trabajo futuro, se propone desarrollar modelos más sofisticados para la proyección de las variables predictivas en el periodo de estimación, estudio que probablemente mejoraría los resultados del CLV a nivel individual.
362

Gallium Phosphide Integrated with Silicon Heterojunction Solar Cells

January 2017 (has links)
abstract: It has been a long-standing goal to epitaxially integrate III-V alloys with Si substrates which can enable low-cost microelectronic and optoelectronic systems. Among the III-V alloys, gallium phosphide (GaP) is a strong candidate, especially for solar cells applications. Gallium phosphide with small lattice mismatch (~0.4%) to Si enables coherent/pseudomorphic epitaxial growth with little crystalline defect creation. The band offset between Si and GaP suggests that GaP can function as an electron-selective contact, and it has been theoretically shown that GaP/Si integrated solar cells have the potential to overcome the limitations of common a-Si based heterojunction (SHJ) solar cells. Despite the promising potential of GaP/Si heterojunction solar cells, there are two main obstacles to realize high performance photovoltaic devices from this structure. First, the growth of the polar material (GaP) on the non-polar material (Si) is a challenge in how to suppress the formation of structural defects, such as anti-phase domains (APD). Further, it is widely observed that the minority-carrier lifetime of the Si substrates is significantly decreased during epitaxially growth of GaP on Si. In this dissertation, two different GaP growth methods were compared and analyzed, including migration-enhanced epitaxy (MEE) and traditional molecular beam epitaxy (MBE). High quality GaP can be realized on precisely oriented (001) Si substrates by MBE growth, and the investigation of structural defect creation in the GaP/Si epitaxial structures was conducted using high resolution X-ray diffraction (HRXRD) and high resolution transmission electron microscopy (HRTEM). The mechanisms responsible for lifetime degradation were further investigated, and it was found that external fast diffusors are the origin for the degradation. Two practical approaches including the use of both a SiNx diffusion barrier layer and P-diffused layers, to suppress the Si minority-carrier lifetime degradation during GaP epitaxial growth on Si by MBE were proposed. To achieve high performance of GaP/Si solar cells, different GaP/Si structures were designed, fabricated and compared, including GaP as a hetero-emitter, GaP as a heterojunction on the rear side, inserting passivation membrane layers at the GaP/Si interface, and GaP/wet-oxide functioning as a passivation contact. A designed of a-Si free carrier-selective contact MoOx/Si/GaP solar cells demonstrated 14.1% power conversion efficiency. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2017
363

Dégradation par électromigration dans les interconnexions en cuivre : étude des facteurs d'amélioration des durées de vie et analyse des défaillances précoces / Electromigration degradation in copper interconnects : study of lifetimes improvement factors and early failures analysis

Bana, Franck Lionel 22 November 2013 (has links)
Les circuits intégrés sont partie prenante de tous les secteurs industriels et de la vie couranteactuels. Leurs dimensions sont sans cesse réduites afin d’accroître leurs performances. Cetteminiaturisation s’accompagne notamment d’une densification et d’une complexification du réseaud’interconnexions. Les interconnexions, lignes métalliques chargées de transporter le signalélectrique dans les circuits apparaissent ainsi plus sensibles à la dégradation par électromigration.Ceci, compte tenu des fortes densités de courant qu’elles transportent. Il se trouve donc dans lesnoeuds technologiques avancés, de plus en plus difficile de garantir le niveau de fiabilité requis pourles interconnexions.La réduction de la durée de vie des interconnexions est liée à la fois à la difficulté croissanteà réaliser les étapes de procédés pour les géométries souhaitées et à l’augmentation de la dispersiondes temps à la défaillance. Dans un premier temps, nous avons poussé la compréhension desmécanismes en jeu lors de la dégradation par électromigration. Nous avons ainsi mis en évidence lerôle joué par la microstructure et la composition chimique des lignes de cuivre dans l’augmentationde leur durée de vie. Dans un second volet, l’accent a été porté sur l’amélioration de l’analysestatistique des durées de vie avec un focus sur les défaillances précoces et les distributionsbimodales qu’elles engendrent. De même, la structure multi liens que nous avons mise au pointpermet de répondre à la question fondamentale de l’augmentation de l’échantillonnage de test ;améliorant ainsi la précision aux faibles taux de défaillance pour des projections robustes des duréesde vie. / Integrated circuits are part of our nowadays life as they are presents everywhere; as well as in daily life or industry. They are continuously downscaled to increase their performances. As a result, this downscaling lead to complex interconnects grid architectures. Interconnects which are metal lines carrying electric signal in the circuit are thus more and more sensitive to electromigration failure. This I because of increasingly higher current densities they carry. Obviously, in advanced technology nodes, it is more and more difficult to ensure the reliability level required for interconnects. Interconnects lifetime reduction is linked to increasing difficulty to perform all process steps with these very small features and also to increasing failure times dispersion. In the first part of the work presented here, we deepened the understanding of mechanisms involved during electromigration degradation. We have thus shown the fundamental role played by the microstructure and the chemical composition of the line in increasing its lifetime. The second part of the work dealt with the improvement of statistical analysis of failure times. We thus focused on early failures and the bimodal failure times distributions they generate. As far as that goes, the multilink structure we have designed answers the fundamental question of increase test sampling. This lead then to improved precision at very low failure rates for robust lifetime's extrapolation to use conditions.
364

HOPE - un piège magnétique pour neutron ultra-froid dédié à la mesure du temps de vie du neutron : conception et premières données expérimentales / HOPE - a magnetic ultra-cold neutron trap to measure the neutron lifetime : design and first experimental data

Rosenau, Felix 10 July 2015 (has links)
Le temps de vie du neutron libre joue un rôle important dans la physique des particules comme dans des modèles cosmologiques. Notre connaissance de la valeur précise du temps de vie du neutron est limitée par les incertitudes systématiques des deux méthodes expérimentales couramment utilisées, les méthodes dites de "faisceau" et de "bouteille matérielle". En outre une déviation systématique des valeurs de temps de vie obtenues par les deux méthodes s'est manifestée au cours des dernières décennies.Le projet HOPE fait parti d'une nouvelle génération d'expériences qui cherchent à mesurer le temps de vie du neutron en stockant des neutrons ultra-froids (UCN) dans un potentiel magnéto-gravitationnel. HOPE génère les champs magnétiques nécessaires par une combinaison d'aimants permanents puissants de terre rare, qui produisent des champs magnétiques maximaux d'environ 1.3 T, et un système de bobines supraconductrices. Dans cette thèse je donnerai une description détaillée de l'appareil, des effets systématiques possibles et comment nous envisageons d'étudier et de maîtriser ces effets. Ensuite les résultats d'un premier temps de faisceau, effectué à la source PF2, vont être présentés et discutés. Les résultats sont encourageants puisque nous avons atteint des constants de temps de stockages maximaux de 881(46) s, ce qui indique des pertes d'UCN très faibles pendant la phase du stockage. / The lifetime of the free neutron plays an important role in fundamental particle physics as well as cosmological models. Our knowledge of the precise value of the neutron lifetime is limited by the systematical inaccuracies of the two commonly used experimental approaches, the so called “beam” and “material bottle” methods. Moreover a systematic deviation of the lifetime-values extracted from both methods has become manifest over the past decades.The HOPE project is part of a new generation of experiments that aims to determine the neutron lifetime by storing ultra cold neutrons (UCN) in a combined magneto-gravitational potential. HOPE generates the necessary gradient magnet fields by a combination of highly potent rare-earth permanent magnets with a maximum B-field strength of about 1.3 T and a set of superconducting coils. In this thesis I give a detailed description of the apparatus, possible systematical effects and how we are planning to investigate and cope with those effects. Subsequently the results from a first beamtime at the PF2 source will be presented and discussed. The results are encouraging as we reached a maximum storage-time constants of 881(46) s, indicating a very small UCN loss rate during storage.
365

Rozvoj osobnosti managera, motivace, stimulace a celoživotní učení / Personal development of manager, motivation, stimulation and lifetime learning

CODLOVÁ, Eva January 2009 (has links)
The aim of this diploma work is the specification of approaches to the developement of manager´s personality, the identification of different ways of motivation and stimulation and getting of oppinions of lifetime laerning need. The research work was realized in the companies Farmtec and Kostečka. In the first part of this work are summarized the teoretical knowledge. The used method of data collection was questionairy examination. The characteristic of the both companies follows after the methodology of this work. In the results of the questionairy examination every question is compiled into a chart and a graph, followed by results and a discussion. In the couclusion the most important pieces of knowledge are summarized. The Farmtec company focuses on the knowledge and common sence. Their managers are efficienty motivated and stimulated. They prefer in born abilities to the lifetime learning. The Kostečka company prefers the gradual creation of knowledge. Their managers feel the need of solidarity. The repondents would more motivation anad stimulation, more autonomy and the opportunity to get on thein own.
366

O valor futuro de cada cliente : estimação do Customer Lifetime Value

Silveira, Rodrigo Heldt January 2014 (has links)
A capacidade de o marketing mensurar e comunicar o valor de suas atividades e investimentos tem sido uma das prioridades de pesquisa na área nos últimos anos. Para atingir esse objetivo, a capacidade de mensurar adequadamente os ativos de marketing, como o Customer Lifetime Value e, de forma agregada, o Customer Equity, torna-se essencial, pois esses ativos são considerados os elementos capazes de traduzir em valores monetários o resultado dos diversos investimentos realizados pela área de marketing. Diante da mensuração desses valores, é possível o planejamento e a realização de ações mais precisas por parte dos profissionais de marketing. Sendo assim, no presente estudo objetivou-se construir e aplicar um modelo de estimação de Customer Lifetime Value no modo bottom-up (individual por cliente) em uma amostra de clientes de uma empresa do setor de serviços financeiros. O modelo bayesiano hierárquico aplicado, com três regressões estruturadas conforme o modelo Seemingly Unrelated Regressions (SUR) (ZELNER, 1971), foi construído a partir dos trabalhos de Kumar et al. (2008), Kumar e Shah (2009) e Cowles, Carlin e Connet (1996). Os resultados evidenciaram (1) que o modelo foi capaz de estimar com consistência o valor futuro de 84% dos clientes analisados; (2) que esse valor estimado traduz o potencial de rentabilidade que pode ser esperado futuramente para cada cliente; (3) que a base de clientes pode ser segmentada a partir do Customer Lifetime Value. Diante do conhecimento do valor futuro de cada cliente, se vislumbrou possibilidades de ações que tragam melhorias para gestão de clientes tradicionalmente utilizada, principalmente no que diz respeito à alocação dos recursos de marketing. / The marketing capacity to measure and to communicate the value resultant of its activities and investments has been one of the area top research priorities in the last few years. In order to achieve this objective, the capacity to appropriately measure the marketing assets, as the Customer Lifetime Value and, in aggregate form, the Customer Equity, has been pointed out as essential, because this assets are considered elements capable of translating the result of marketing investments into monetary values. Given the measurement of those values, marketers become able to plan and take more precise actions. Thus, the objective of present study is to build and test a bottom-up Customer Lifetime Value estimation model to a sample of customers from a company of finance services. The bayesian hierarchical model, composed of three regressions structured according to the Seemingly Unrelated Regressions (SUR) model (ZELNER, 1971), was built from the works of Kumar et al. (2008), Kumar and Shah (2009) and Cowles, Carlin and Connet (1996). The results show that (1) the model was capable to estimate with consistency the future value of 84% of the analyzed customers; (2) this estimated future values indicate the potential profitability of each customer; (3) the customer base can be segmented from the Customer Lifetime Value. Given the knowledge obtained about the future value of each customer and the segments established, several actions that can bring improvements to the traditional way of managing customers were suggested, in special those concerning marketing resource allocation.
367

A relação entre Customer equity e capitalização de mercado no setor de telecomunicação brasileiro

Lima, Mauricio Pozzebon de January 2012 (has links)
O moderno conceito de marketing, visto como filosofia empresarial, defende que a empresa deve ser centralizada no cliente, ou seja, ter todas as suas atividades integradas e alinhadas para entregar valor superior para seus consumidores. Até o final da década de 1990 havia uma clara lacuna entre o moderno conceito de marketing e as métricas existentes. Assim, as métricas de customer equity foram concebidas na tentativa de superar esse conflito entre filosofia e realidade prática de marketing. Customer equity pode ser definido como o valor monetário dos clientes enquanto um ativo da empresa, e foi apontado pela literatura como possível responsável pelo aumento da capitalização de mercado em algumas empresas. Esse estudo busca identificar a relação de causalidade entre customer equity, calculado pelo modelo de Gupta et al (2003), e a capitalização de mercado das empresas do setor de comunicação do mercado brasileiro utilizando uma série de modelos. Primeiramente rodou-se um modelo de regressão em painel com efeito aleatório, seguido de uma análise de causalidade Granger. Os resultados, em geral, não convergem com a literatura relacionada. Por fim foram discutidas as implicações gerenciais, limitações e sugestões para pesquisas futuras. / The modern concept of marketing, seen as business philosophy, holds that the firm must be customer centered, that is, all the activities must be integrated and oriented to deliver superior value to its customers. There was a clear gap between the modern concept of marketing and the existing metrics until the end of the 1990’s. Thus, the customer equity metrics were developed trying to overcome the conflict between philosophy and the managerial reality of marketing. Customer equity can be defined as the value of customers as an asset of the firm, and was held as a possible responsible for increasing the market capitalization of several companies. This study aims to identify the causal relationship between customer equity, using the approach proposed by Gupta and Lehmann (2003), and the market capitalization of several Brazilian communication companies. First it was conducted a panel regression analysis with random effects, then a series of Granger causality tests were made. The results, at large, do not converge with the related research. Finally, the limitations, managerial implications and recommendations for future research were discussed.
368

Aprendendo a ser aprendente : novos modos de ser aluno na contemporaneidade

Schnorr, Aline Silveira de Lima January 2011 (has links)
A pesquisa tem como objetivo analisar as principais mudanças que vêm ocorrendo nos modos de ser aluno na contemporaneidade, mostrando como estes se constituem aprendentes frente à chamada “Sociedade da Aprendizagem”. Para isso, utilizei como instrumentos de pesquisa entrevistas e questões narrativas, para uma classe de vinte alunos e um Diário de Campo nas turmas onde exercia a docência, em uma escola privada de Novo Hamburgo/RS. A partir das análises dos dados foi possível condensar as recorrências em três Eixos Temáticos e tecer as seguintes considerações. No primeiro Eixo – O Aprendente Escolar da Infância e as Tecnologias da Informação e Comunicação (TICs) – observei que os alunos mantêm contato intenso com diversas TICs, conformando modos de subjetivação desses novos sujeitos, alunos caracterizados pelas ações multi-tarefas. O tema de casa se mostrou mais uma atividade sem conotação desafiadora e o ato de estudar em casa, nos moldes tradicionais, não faz parte de seus afazeres extra-escolares. No segundo Eixo – Os Saberes Escolares e o Currículo Cultural – percebi que os alunos, ao narrarem seus aprendizados e fazeres na escola, remetem-se prioritariamente aos conteúdos escolares, fazendo poucas relações com outros mundos onde circulam. Há um significativo espaço ocupado pelo Currículo Cultural, e, por conseguinte, na constituição do sujeito aprendente da infância. E, no terceiro Eixo – O Aprendente da Infância, O Currículo Cultural e as Tecnologias da Informação e Comunicação – mostrei a escola fora do foco principal para a busca do conhecimento, mas como lugar qualificado para o aluno aprender como ser aprendente por toda a vida. Por fim, a pesquisa possibilitou concluir que as crianças estão aprendendo a aprender por toda a vida. É como se houvesse um “antigo educando” e um “novo aprendente”: Antes, um sujeito educado para ser educável; agora, um sujeito educado para aprender, entretanto, ambos permanecem co-existindo atualmente. / The research aims to analyze the main changes occurring in the ways of being a student in the contemporary time, showing how these learners are facing the so-called "Learning Society”. For this, I used as research, tools narrative interviews and questions for a class of twenty students and a field journal where I worked as a teacher, in a private school of New Hamburgo / RS. From the data analysis it was possible to condense the three recurrences in the theme and make the following considerations. In the first axis – The childhood learner and the Information and Communication Technologies (ICTs) - noticed that students maintain constant contact with various ICTs, according to modes of subjectivity of these new individuals; students are characterized by multi-tasking actions. The homework was more a challenging activity without connotation and the act of studying at home, in the traditional way, was not part of their extra-school activities. In the second axis - The School Knowledge and the Cultural Curriculum - I realized that students, when describing their learning and actions in school, to refer primarily to educational content, making few relations with other worlds where they circulate. There is a significant space occupied by the cultural curriculum, and therefore the constitution of the childhood learner. And on the third axis - The childhood learner, The Curriculum and Cultural Information and Communication Technologies - showed the school was the main focus for the pursuit of knowledge, but as qualified to the place where the student learn how to be learners for life. Finally, the research allowed me to conclude that children are learning to learn throughout life. It is as if there was a "former student" and a "new learner". Before, a man trained to be teachable, now an individual taught to learn, however, both remain co-existing nowadays.
369

Medida do tempo de vida de estados de Rydberg em átomos frios de 85 Rb / Lifetime measurement of Rydberg states of 85 using a sample of cold atoms

Kilvia Mayre Farias Magalhães 23 July 1999 (has links)
Neste trabalho apresentamos os primeiros resultados sobre medida do tempo de vida de estados de Rydberg utilizando átomos frios confinados em uma armadilha magneto-optica de 85Rb. Medidas de tempo de vida de estados altamente excitados são importantes para o teste de teorias modernas sobre interação átomo-vácuo; desta forma medidas precisas são necessárias. A utilização de átomos frios apresenta várias vantagens quando comparadas com técnicas convencionais. Entre elas podemos citar a possibilidade de observação do sistema atômico por longos períodos (>100 &#181;s), e o controle da densidade de forma eficiente para evitar a manifestação de efeitos indesejáveis (colisões, superradiância) que limitam a precisão da medida. Apresentamos a medida do tempo de vida do estado 27D e 38S e comparamos os resultados experimentais com previsões teóricas de diferentes modelos. Algumas discrepâncias são observadas, o que reforça a necessidade da obtenção de um conjunto maior de medidas incluindo outros níveis para indicar qual modelo teórico é mais próximo da realidade. / In this work we present our first results on lifetime measurement of Rydberg states using cold atoms held in a magneto-optical trap of 85Rb. Lifetime measurements of highly excited states are important for testing modern theories on atom-vaccum interaction, therefore precise measurements are required. The use of cold atoms presents some advantage when compared with conventional techniques. Among them we cam point out the possibility of atomic observation for long periods of time (<100 &#181;s), the atomic density control in order to avoid undesired effects (such collisions and superradiance) which can limit the measurement precision. We present the lifetime measurement of 27D and 38S states and compared the experimental results with theoretical prediction using different models. Some discrepancies are observed, which indicates the need of a large set of measurement for other states in order to indicate the best model.
370

Avaliação econômica de clientes: um estudo exploratório sobre modelos na prática e a capacidade de geração de valor para a empresa e/ou acionistas / Customers\' economical evaluation: an exploratory study on models in practice and the value generation capacity for the company and/or shareholders

Aline Araujo Perini 17 September 2010 (has links)
A configuração do capitalismo atual, a globalização de mercados, o acirramento da concorrência, a velocidade de mudança e os gerentes cada vez mais cobrados por resultados e sustentabilidade das tomadas de decisão têm impelido as empresas a investir cada vez mais em sistemas de relacionamento para conhecer clientes. Os clientes são a mola propulsora de qualquer empresa e sem eles a empresa não possui valor algum. O objetivo desse trabalho foi explorar os fatores que impactam e determinam o valor do cliente para a empresa e/ou acionistas. Com base em fundamentação teórica, foram evidenciadas as principais pesquisas, destacando as contribuições empíricas de cada caso e a contemplação dos vetores de valor para a empresa e/ou acionistas. Resultados sugerem que o advento da tecnologia da informação nas empresas tem proporcionado a produção de conhecimento para a tomada de decisão mais estruturada em relação à gestão de clientes por valor. Foram evidenciadas (9) nove pesquisas sobre análise de padrão de lucratividade, (8) oito sobre otimização de alocação de recursos, (5) cinco sobre aquisição, retenção e efeitos sociais e (4) quatro sobre avaliação de empresas por meio de clientes. Cliente é definido como ativo intangível na medida em que otimiza a utilização dos recursos para a cocriação de valor para a empresa e/ou acionistas. / The current capitalism configuration, markets globalization, tight competitiveness, the change speed, managers more and more called by results and account for their decision have been forcing companies to invest more and more in customer relationship systems. The customers are the bottom line of any company and without them the company doesn\'t possess any value. The objective of this work was to explore the factors that impact and determine the customer\'s value for the company and/or shareholders. Based on theoretical, it was evidenced the mainly researches, dealing with empirical contribution of each case and the value vectors contemplation for company and/or shareholders. Results suggest that the introducing information technology in the companies has been providing the knowledge production for decision models more structured for managing customers by value. Nine researches were evidenced on profitability pattern analysis, eight on optimize resources allocation, five on acquisition and retention and social effects and four about firm evaluation through customers. Customer is defined as in-tangible assets as long as optimizes the utilization of resources for the co-creation of value for the company and/or shareholders.

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