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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.
41

Caracterização do processo de fusão - fissão em sistemas nucleares / Characterization of the process of fusion - fission in nuclear systems

Anjos, Roberto Meigikos dos 29 September 1992 (has links)
Medidas das seções de choque de fusão, de processos fortemente amortecidos e de espalhamento elástico foram realizadas para os sistemas 16,17,18O + 10,11B e 19F + 9Be no intervalo de energia de bombardeio compreendido entre 22 ELAB64 Mev. São apresentadas evidências de que processos binários fortemente amortecidos observados nestes sistemas originam-se preferencialmente de um processo de fusão-fissão e não de um mecanismo de orbiting dinuclear. A importância relativa do processo de fusão-fissão nestes sistemas muito leves é comprovada pelos resultados experimentais, que indicam a ocorrência de um processo de fissão de um núcleo composto estatisticamente equilibrado, assim como por cálculos de modelos teóricos. Os números atômicos e os de massa dos produtos de reação e dos resíduos de evaporação foram identificados usando-se duas câmaras de ionização e um sistema de tempo de voo. / Cross sections for fusion, strongly energy-damped processes and elastic scattering were measured for the 16 ,17, 18O + 10 11B and 19F + 9Be systems in the energy range 22 ELAB 64 HeV. Evidence that the fully energy-damped binary products observed in these reactions originate from a fusion-fission process, rather than through a deep-inelastic orbiting mechanism, is presented. The relative importance of the fusion-fission process in these very light systems is supported by experimental results which points towards the fission of a statistically equilibrated compound nucleus and also by model calculations. Charges and masses of the reaction products and evaporation residues were indentified using two ionization chamber and a time-of-flight system.
42

Caracterização do processo de fusão - fissão em sistemas nucleares / Characterization of the process of fusion - fission in nuclear systems

Roberto Meigikos dos Anjos 29 September 1992 (has links)
Medidas das seções de choque de fusão, de processos fortemente amortecidos e de espalhamento elástico foram realizadas para os sistemas 16,17,18O + 10,11B e 19F + 9Be no intervalo de energia de bombardeio compreendido entre 22 ELAB64 Mev. São apresentadas evidências de que processos binários fortemente amortecidos observados nestes sistemas originam-se preferencialmente de um processo de fusão-fissão e não de um mecanismo de orbiting dinuclear. A importância relativa do processo de fusão-fissão nestes sistemas muito leves é comprovada pelos resultados experimentais, que indicam a ocorrência de um processo de fissão de um núcleo composto estatisticamente equilibrado, assim como por cálculos de modelos teóricos. Os números atômicos e os de massa dos produtos de reação e dos resíduos de evaporação foram identificados usando-se duas câmaras de ionização e um sistema de tempo de voo. / Cross sections for fusion, strongly energy-damped processes and elastic scattering were measured for the 16 ,17, 18O + 10 11B and 19F + 9Be systems in the energy range 22 ELAB 64 HeV. Evidence that the fully energy-damped binary products observed in these reactions originate from a fusion-fission process, rather than through a deep-inelastic orbiting mechanism, is presented. The relative importance of the fusion-fission process in these very light systems is supported by experimental results which points towards the fission of a statistically equilibrated compound nucleus and also by model calculations. Charges and masses of the reaction products and evaporation residues were indentified using two ionization chamber and a time-of-flight system.
43

Verification of asynchronous concurrency and the shaped stack constraint

Kochems, Jonathan Antonius January 2014 (has links)
In this dissertation, we study the verification of concurrent programs written in the programming language Erlang using infinite-state model-checking. Erlang is a widely used, higher order, dynamically typed, call-by-value functional language with algebraic data types and pattern-matching. It is further augmented with support for actor concurrency, i.e. asynchronous message passing and dynamic process creation. With decidable model-checking in mind, we identify actor communicating systems (ACS) as a suitable target model for an abstract interpretation of Erlang. ACS model a dynamic network of finite-state processes that communicate over a fixed, finite number of unordered, unbounded channels. Thanks to being equivalent to Petri nets, ACS enjoy good algorithmic properties. We develop a verification procedure that extracts a sound abstract model, in the form of an ACS, from a given Erlang program; the resulting ACS simulates the operational semantics of the input. Using this abstract model, we can conservatively verify coverability properties of the input program, i.e. a weak form of safety properties, with a Petri net model-checker. We have implemented this procedure in our tool Soter, which is the first sound verification tool for Erlang programs using infinite-state model-checking. In our experiments, we find that Soter is accurate enough to verify a range of interesting and non-trivial benchmarks. Even though ACS coverability is Expspace-complete, Soter's analysis of these verification problems is surprisingly quick. In order to improve the precision of our verification procedure with respect to recursion, we investigate an extension of ACS that allows pushdown processes: asynchronously communicating pushdown systems (ACPS). ACPS that satisfy the empty-stack constraint (a pushdown process may receive only when its stack is empty) are a popular subclass of ACPS with good decision and complexity properties. In the context of Erlang, the empty stack constraint is unfortunately not realistic. We introduce a relaxation of the empty-stack constraint for ACPS called the shaped stack constraint. Stacks that fit the shape constraint may reach arbitrary heights. Further, a process may execute any communication action (be it process creation, message send or retrieval) whether or not its stack is empty. We prove that coverability for shaped ACPS, i.e. ACPS that satisfy the shaped constraint, reduces to the decidable coverability problem for well-structured transition systems (WSTS). Thus, shaped ACPS enable the modelling and verification of a larger class of message passing programs. We establish a close connection between shaped ACPS and a novel extension of Petri nets: nets with nested coloured tokens (NNCT). Tokens in NNCT are of two types: simple and complex. Complex tokens carry an arbitrary number of coloured tokens. The rules of a NNCT can synchronise complex and simple tokens, inject coloured tokens into a complex token, and eject all tokens of a specified set of active colours to predefined places. We show that the coverability problem for NNCT is Tower-complete, a new complexity class for non-elementary decision problems introduced by Schmitz. To prove Tower-membership, we devise a geometrically inspired version of the Rackoff technique, and we obtain Tower-hardness by adapting Stockmeyer's ruler construction to NNCT. To our knowledge, NNCT is the first extension of Petri nets (belonging to the class of nets with an infinite set of token types) that is proven to have primitive recursive coverability. This result implies Tower-completeness of coverability for ACPS that satisfy the shaped stack constraint.
44

Modèles conjoints pour données longitudinales et données de survie incomplètes appliqués à l'étude du vieillissement cognitif

Dantan, Etienne 08 December 2009 (has links)
Dans l'étude du vieillissement cérébral, le suivi des personnes âgées est soumis à une forte sélection avec un risque de décès associé à de faibles performances cognitives. La modélisation de l'histoire naturelle du vieillissement cognitif est complexe du fait de données longitudinales et données de survie incomplètes. Par ailleurs, un déclin accru des performances cognitives est souvent observé avant le diagnostic de démence sénile, mais le début de cette accélération n'est pas facile à identifier. Les profils d'évolution peuvent être variés et associés à des risques différents de survenue d'un événement; cette hétérogénéité des déclins cognitifs de la population des personnes âgées doit être prise en compte. Ce travail a pour objectif d'étudier des modèles conjoints pour données longitudinales et données de survie incomplètes afin de décrire l'évolution cognitive chez les personnes âgées. L'utilisation d'approches à variables latentes a permis de tenir compte de ces phénomènes sous-jacents au vieillissement cognitif que sont l'hétérogénéité et l'accélération du déclin. Au cours d'un premier travail, nous comparons deux approches pour tenir compte des données manquantes dans l'étude d'un processus longitudinal. Dans un second travail, nous proposons un modèle conjoint à état latent pour modéliser simultanément l'évolution cognitive et son accélération pré-démentielle, le risque de démence et le risque de décès. / In cognitive ageing study, older people are highly selected by a risk of death associated with poor cognitive performances. Modeling the natural history of cognitive decline is difficult in presence of incomplete longitudinal and survival data. Moreover, the non observed cognitive decline acceleration beginning before the dementia diagnosis is difficult to evaluate. Cognitive decline is highly heterogeneous, e.g. there are various patterns associated with different risks of survival event. The objective is to study joint models for incomplete longitudinal and survival data to describe the cognitive evolution in older people. Latent variable approaches were used to take into account the non-observed mechanisms, e.g. heterogeneity and decline acceleration. First, we compared two approaches to consider missing data in longitudinal data analysis. Second, we propose a joint model with a latent state to model cognitive evolution and its pre-dementia acceleration, dementia risk and death risk.
45

Étude des trajectoires d’usage de substances psychoactives chez l’adolescent et l’adulte jeune : Exploration de la théorie de l’escalade / Psychoactive substance use itineraries among adolescents and young adults : exploration of Gateway theory

Mayet, Aurélie 19 June 2012 (has links)
Selon la théorie de l'escalade, l'usage de tabac ou d'alcool est associé à l'usage de cannabis, qui peut lui-même conduire à l'usage d’autres drogues illicites (ADI). L'objectif de notre étude était de décrire les transitions entres usages de drogues licites, de cannabis et d’ADI. Les données de deux enquêtes en population générale (ESCAPAD pour l’adolescent et Baromètre santé pour l’adulte jeune (année 2005)) ont été utilisées. Les âges rapportés d’initiation des différentes substances ont permis de définir les étapes d’usages. L’analyse des transitions entre substances a été réalisée grâce aux modèles structuraux et aux modèles multi-états de Markov en prenant en compte certains cofacteurs. Les données recueillies ont permis de décrire un processus d'usage de substances partant des drogues licites et menant vers les ADI via le cannabis. Ces résultats étaient compatibles avec la théorie de l'escalade décrite par Kandel en 1975 et étaient renforcés par certains critères : force/stabilité des associations, effet dose-réponse, cohérence avec la littérature et relation temporelle. La théorie qui se dégage de nos travaux pourrait être celle d’opportunités en chaîne, l’apprentissage de la première substance psychoactive étant conditionné à son accessibilité et susceptible d’offrir des opportunités ultérieures d’usages d’autres substances. Il est cependant important de souligner que la théorie de l’escalade, si elle semble correspondre à la majorité des séquences d’usages observées, est actuellement remise en question par certains auteurs qui lui préfèrent l’idée d’un facteur de vulnérabilité commun aux addictions. / According to Gateway theory, tobacco or alcohol uses may lead to cannabis use, which may itself lead to initiation with other illicit drugs (OID). The aim of this study was to study the transitions between use of licit drugs, cannabis and OID. Data from two large population-based surveys (ESCAPAD for adolescents and Baromètre santé for young adults (year 2005)) were used. Self-reported ages at initiation of several substance uses permitted to define different stages of use. The analyses of transition between uses were performed using structural equation models and Markov multi-states models, taking into account some cofactors. Results of this study permitted to describe a drug use stage process, mediated by cannabis and susceptible to lead to OID use. These results were in accordance with the Gateway theory described by Kandel in 1975 and satisfied to some criteria: strength and stability of associations, dose-response trend, coherence with previous research and temporal relation. The theory which emerge from our research could be a “string of opportunities”, OID experiment being a consequence of initial opportunity to use the more accessible illicit drug, cannabis. However, it is important to mention that the Gateway theory, despite compatible with the majority of sequences of uses observed, is presently questioned by some authors which prefer the theory of a common vulnerability factor to addictions.
46

Metodologia evolutiva para previsão inteligente de séries temporais sazonais baseada em espaço de estados não-observáveis / EVOLUTIONARY METHODOLOGY FOR INTELLIGENT FORECAST SERIES SEASONAL TEMPORAL STATE SPACE-BASED NON-OBSERVABLE

Rodrigues Júnior, Selmo Eduardo 26 January 2017 (has links)
Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-07-03T18:32:31Z No. of bitstreams: 1 SelmoRodrigues.pdf: 1374245 bytes, checksum: 96afcfa04ba5cc18c4db55e4c92cdf23 (MD5) / Made available in DSpace on 2017-07-03T18:32:31Z (GMT). No. of bitstreams: 1 SelmoRodrigues.pdf: 1374245 bytes, checksum: 96afcfa04ba5cc18c4db55e4c92cdf23 (MD5) Previous issue date: 2017-01-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / This paper proposes a new methodology for modelling based on an evolving Neuro-Fuzzy Network Takagi-Sugeno (NFN-TS) for seasonal time series forecasting. The NFN-TS use the unobservable components extracted from the time series to evolve, i.e., to adapt and to adjust its structure, where the number of fuzzy rules of this network can increase or reduced according the components behavior. The method used to extract the components is a recursive version developed in this paper based on the Spectral Singular Analysis (SSA) technique. The proposed methodology has the principle divide to conquer, i.e., it divides a problem into easier subproblems, forecasting separately each component because they present dynamic behaviors that are simpler to forecast. The consequent propositions of fuzzy rules are linear state space models, where the states are the unobservable components data. When there are available observations from the time series, the training stage of NFN-TS is performed, i.e., the NFN-TS evolves its structure and adapts its parameters to carry out the mapping between the components data and the available sample of original time series. On the other hand, if this observation is not available, the network considers the forecasting stage, keeping its structure fixed and using the states of consequent fuzzy rules to feedback the components data to NFN-TS. The NFN-TS was evaluated and compared with other recent and traditional techniques for forecasting seasonal time series, obtaining competitive and advantageous results in relation to other papers. This paper also presents a case study of proposed methodology for real-time detection of anomalies based on a patient’s electrocardiogram data. / Esse trabalho propõe uma nova metodologia para modelagem baseada em uma Rede Neuro- Fuzzy Takagi-Sugeno (RNF-TS) evolutiva para a previsão de séries temporais sazonais. A RNF-TS considera as componentes não-observáveis extraídas a partir da série para evoluir, ou seja, adaptar e ajustar sua estrutura, sendo que a quantidade de regras fuzzy dessa rede pode aumentar ou ser reduzida conforme o comportamento das componentes. O método utilizado para extrair as componentes é uma versão recursiva desenvolvida nessa pesquisa baseada na técnica de Análise Espectral Singular (AES). A metodologia proposta tem como princípio dividir para conquistar, isto é, dividir um problema em subproblemas mais fáceis de lidar, realizando a previsão separadamente de cada componente já que apresentam comportamentos dinâmicos mais simples de prever. As proposições do consequente das regras fuzzy são modelos lineares no espaço de estados, sendo que os estados são os próprios dados das componentes não-observáveis. Quando há observações disponíveis da série temporal, o estágio de treinamento da RNF-TS é realizado, ou seja, a RNF-TS evolui sua estrutura e adapta seus parâmetros para realizar o mapeamento entre os dados das componentes e a amostra disponível da série temporal original. Caso contrário, se essa observação não está disponível, a rede aciona o estágio de previsão, mantendo sua estrutura fixa e usando os estados dos consequentes das regras fuzzy para realimentar os dados das componentes para a RNF-TS. A RNF-TS foi avaliada e comparada com outras técnicas recentes e tradicionais para previsão de séries temporais sazonais, obtendo resultados competitivos e vantajosos em relação a outras pesquisas. Este trabalho apresenta também um estudo de caso da metodologia proposta para detecção em tempo-real de anomalias baseada em dados de eletrocardiogramas de um paciente.
47

Sur l’utilisation des modèles multi-états pour la mesure et la gestion des risques d’un contrat d’assurance / On the use of multi-state models to measure and manage the risks of an insurance contract

Guibert, Quentin 07 December 2015 (has links)
La mise en place de Solvabilité II conduit les actuaires à s'interroger sur la bonne adéquation entre modèles et données. Aussi, cette thèse a pour objectif d'étudier plusieurs approches statistiques, souvent méconnues des praticiens, permettant l'utilisation de méthodes multi états pour modéliser et gérer les risques individuels en assurance. Le Chapitre 1 présente le contexte général de cette thèse et permet de faire positionner ses principales contributions. Nous abordons les concepts de base liés à l'utilisation de modèles multi-états en assurance et décrivons les techniques d'inférence classiques adaptées aux données rencontrées, qu'ils soient markoviens ou non-markoviens. Pour finir, nous présentons comment il est possible d'utiliser ces modèles pour la gestion des risques de crédit. Le Chapitre 2 se concentre sur l'utilisation de méthodes d'inférence non-paramétriques pour la construction de lois d'incidence en assurance dépendance. Puisque plusieurs causes d'entrée sont susceptibles d'intervenir et d'intéresser les actuaires, nous nous concentrons sur une méthode utilisée pour l'estimation de modèles multi-états markoviens en temps continu. Nous comparons, dans un second temps, ces estimateurs à ceux utilisés classiquement par les praticiens tires de l'analyse de survie. Cette seconde approche peut comporter des biais non négligeables car ne permettant pas d'appréhender correctement l'interaction possible entre les causes. En particulier, elle comprend une hypothèse d'indépendance ne pouvant être testée dans le cadre de modèles à risques concurrents. Notre approche consiste alors à mesurer l'erreur commise par les praticiens lors de la construction de lois d'incidence. Une application numérique est alors considérée sur la base des données d'un assureur dépendance / With the implementation of the Solvency II framework, actuaries should examine the good adequacy between models and data. This thesis aims to study several statistical approaches, often ignored by practitioners, enabling the use of multi-state methods to model and manage individual risks in insurance. Chapter 1 presents the general context of this thesis and positions its main contributions. The basic tools to use multi-state models in insurance are introduced and classical inference techniques, adapted to insurance data with and without the Markov assumption, are presented. Finally, a development of these models for credit risk is outlined. Chapter 2 focuses on using nonparametric inference methods to build incidence tables for long term care insurance contracts. Since there are several entry-causes in disability states which are useful for actuaries, an inference method for competing risks data, seen as a Markov multi-state model in continuous time, is used. In a second step, I compare these estimators to those conventionally used by practitioners, based on survival analysis methods. This second approach may involve significant bias because the interaction between entry-causes cannot be appropriately captured. In particular, these approaches assume that latent failure times are independent, while this hypothesis cannot be tested for competing risks data. Our approach allows to measure the error done by practitioners when they build incidence tables. Finally, a numerical application is considered on a long term care insurance dataset
48

Understanding and explaining social welfare policies in developing nations

Bhuiyan, Md. Mahmudur 12 January 2016 (has links)
Over the last five decades, a rich literature on the welfare state has developed. Multiple theories and models seek to explain the contemporary welfare state, including structural functionalist, structural-Marxist and Marxist perspectives, culturalist approaches, pluralist analyses, neo-institutionalist theories, power resources theory, Harold Wilensky and Lebeaux’s dual model, Richard Titmuss’s tri-polar model, and Gøsta Esping-Andersen’s tri-polar model, all designed to account for the emergence of and variations among welfare states. However, these theories and models originated within the developed world, and empirical examinations of these theories are largely restricted within this part of the world. The welfare state literature is too confined to the West today. This study examines key welfare state theories and models in the contexts of developing and least developed nations employing a combination of quantitative, qualitative, and comparative methodologies. It suggests that social policies and programs in the developing nations can be systematically understood in the light of mainstream Western theories and models of the welfare state. Therefore, in addition to challenging current practices that limit the study of the welfare state within particular geographical areas, the research presented here provides rationale for increased efforts to understand welfare policies and programs in developing nations. This will increase our knowledge about the applicability of theories in the developing world and will enrich the understanding of the developed world, and thus contribute to the advancement of welfare state scholarship. / February 2016
49

Temple Construction, Iconography, and Royal Identity In the Eastern Kalacuri Dynasty

Masteller, Kimberly Adora 23 October 2017 (has links)
No description available.
50

肺癌之研究及保單設計 / Study and price insurance for the lung cancer

葉步釩, Ye, Bu Fan Unknown Date (has links)
本次研究使用全民健康保險研究資料庫2005承保抽樣歸人檔(LHID2005),共40萬人的承保資料,針對肺癌患者的特徵進行分析,並與美國國家癌症研究所的肺癌資料作比較,罹患肺癌的人數都呈現男性多於女性,罹癌年齡的最高峰同樣落在65歲至74歲。 接著,將門診處方及治療明細檔和住院醫療費用清單明細檔進行彙整,整理出肺癌患者在2005年至2012年之間的門診費用以及住院費用,並比較不同項目的差距及特徵,門診費用以用藥明細點數最高,住院花費前五名的項目為葯費、病房費、放射線診療費、檢查費以及治療處置費。 最後,建構肺癌治療的多重型態模型,治療方式包含手術治療、放射線治療、化學治療,估計不同狀態之間的轉換力,進而算出五年定期躉繳肺癌保單之純保費。 / This study used Longitudinal Health Insurance Database 2005 (LHID2005) from Taiwan’s National Health Insurance Research Database (NHIRD). Screening the 400,000 insured of NHIRD to select the lung and bronchus cancer patients. This study analyzed and described their characteristics. Furthermore, it compared Taiwan’s lung and bronchus cancer data with the data in the United States derived from National Cancer Institute of the USA. The results revealed that the number of male patients is more than female patients and lung cancer is most frequently diagnosed among people aged 65-74 in both countries. Another aim was to sum up the lung cancer medical cost in 2005 to 2012 from NHIRD database, including ambulatory care expenditures by visits and inpatient expenditures by admissions. The highest cost of outpatients was medicine fee. The top five inpatient expenditures were medicine fee, ward fee, radiation therapy fee, inspection fee and therapeutic treatment fee. Finally, this study constructed a multiple state model of lung cancer treatment, including surgery, radiotherapy, chemotherapy. Estimating the transition intensities from multiple state model to calculate the pure premium of a five-year lung cancer policy.

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