• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 21
  • 7
  • 6
  • 4
  • 3
  • 3
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 55
  • 8
  • 7
  • 6
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 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.
11

An economic analysis of adjusted gross Revenue-Lite insurance on farm income variability for southeast Kansas farms

Saffert, Andrew Thomas January 1900 (has links)
Master of Science / Department of Agricultural Economics / Jeffery R. Williams / In today’s production agricultural sector, managing risk is essential to insuring the economic well being and sustainability of successful enterprises. Considering the inherent risks present in today’s agricultural arena, risk management has become the central focus of discussions for policy makers and producers alike. Therefore the objective of this research paper is to examine the impact a whole-farm adjusted gross revenue insurance risk management program (AGR-Lite) has on reducing farm income variability using historical farm level data for Southeast Kansas farms. A panel data set of actual farm level income data was compiled to evaluate the impact of AGR-Lite on farm income variability for 219 Southeast Kansas farms. Although actual income tax records were not available annual data over the period 1993 to 2005 from the Kansas Farm Management Association was used to reproduce the essential information a farm manager would need from IRS form 1040 schedule F and inventory records to purchase AGR-Lite (Langemeier, 2003). Income distributions for each farm from 1999 to 2005 were calculated for two strategies; the farm manager did not insure and the manager insured each year using AGR-Lite as a stand-alone product. The AGR-Lite insurance strategy assumed a 75% coverage level and 90% payment rate. The income distributions were compared using three premium scenarios. In general, the results of this study reveal participation in the AGR-Lite program, in most instances, reduced standard deviation, Coefficient of Variation (CV), and Downside Risk (DR). Additionally average minimums and Certainty Equivalents (CE) were increased with the product. The following results reflect application of Actuarially Fair Average Rate for farms with Indemnities (AFARI), which is believed to reflect actual market performance. Additionally the following reflects results using Net Farm Income (NFI). Results reveal that purchasing AGR-Lite reduced standard deviations 7.01%, 11.34%, 0.29%, and 2.53% for total, crop, livestock, and dairy farms assuming AFARI. However beef farms were the lone category to sustain a 0.81% standard deviation increase. Despite reductions in absolute variability, relative risk (CV) increased 18.94%, 17.12%, 53.84%, and 3.19% for total, livestock, beef, and dairy. Crop farms were the only category to generate a CV reduction (9.52%). Under AFARI crop farms generated the largest minimum increase, reducing downside risk, by 69.97%. For total and dairy farm categories average minimums increased 62.93% and 0.60%. The remaining farm categories, livestock and beef, yielded 65.07% and 57.03% reductions to average minimum.
12

Improving Dynamic Navigation Algorithms

Yue, Weiya, Ph.D. 30 September 2013 (has links)
No description available.
13

Cooperation between LTE and emergent DVB technologies for an efficient delivery of mobile TV / Coopération entre LTE et DVB pour une solution de TV mobile optimisée

Abdel-Razzac, Amal 14 January 2015 (has links)
La coopération entre les réseaux de diffusion classiques et les réseaux mobiles cellulaires pour une distribution commune de la télévision mobile est actuellement l'un des éléments clé discutés dans le cadre des nouvelles technologies de diffusion mobile; surtout l'extension mobile de la deuxième génération de diffusion de la télévision numérique terrestre (DVB-T2 Lite) et son suiveur le DVB-Next Generation Handheld (DVB-NGH).En fait, ces technologies de diffusion visent à coopérer avec la récente technologie de téléphonie mobile, connue sous le nom de Long Term Evolution (LTE) qui permet la diffusion de la TV Mobile grâce au protocole de diffusion des services multimédia dans les réseaux de téléphonie mobile (de nature unicast à priori) et connu sous le nom de enhanced-Multimedia Broadcast and Multicast Service feature (e-MBMS).Bien que la coopération entre les réseaux de diffusion DVB et ceux de téléphonie mobile n'est pas un nouveau sujet et a été étudiée avec l'introduction de la technologie de diffusion mobile précédente, connue sous le nom DVB-Handheld (DVB-H), la plupart des travaux traitants ce sujet ont considéré un scénario avec une zone de couverture commune entre le réseau de diffusion et celui cellulaire et ont évalué cette coopération en terme des gains de capacité apportés par DVB au réseau cellulaire et en terme d'amélioration de la fiabilité de transmission apportée par les réseaux cellulaire au DVB grâce à la possibilité des retransmissions unicast. / The broadcast/cellular cooperation for a common delivery of Mobile TV is at the heart of the emerging mobile broadcast technologies, namely the mobile extension of the second generation digital video broadcasting for terrestrial reception (DVB-T2 Lite) and its follower DVB-Next Generation Handheld (DVB-NGH). These broadcast technologies aim to cooperate with the Long Term Evolution (LTE), as the latter is intended to be the bearer of Mobile TV thanks to its enhanced-Multimedia Broadcast and Multicast Service feature (e-MBMS). Even though the 3GPP/DVB cooperation is not a new topic and was investigated with the introduction of the previous DVB technology, known as DVB-Handheld (DVB-H), most of the works addressing this issue considered a common service area covered by both DVB and cellular systems and focused solely on the impact of such cooperation in terms of capacity gains brought by 3GPP and error repair gains brought by DVB. This strategy was judged to be expensive since a new and very dense DVB network was needed. In order to overcome this problem and decrease as much as possible the need for a new broadcast network, we propose in this thesis a hybrid DVB/LTE network with a coverage extension strategy, where the LTE system, planned for almost a universal coverage, is used to deliver Mobile TV in areas not covered by recent DVB-T2 Lite (or eventually DVB-NGH) network. In this context, we explore two main issues:1. Mobile TV services have to share LTE resources with other higher priority services such as voice traffic. The dynamicity of the latter will impact the Quality of Service (QoS) of Mobile TV. We propose a new QoS-based planning for the hybrid DVB/LTE so as to guarantee an acceptable watching experience without over-dimensioning the LTE system. We derive using Markov chain analysis and hitting time theory, several QoS metrics pertaining to mobile TV performance, such as interruption frequency and duration.2. A new business model which clarifies the relationships between the different actors of the ecosystem namely DVB and LTE operators as well as the TV channel providers and constructs the service area from an economic point of view is needed. In fact, the absence of a clear and viable economic model that resolves the monetary conflicts between cellular and broadcast operators was one of the main drawbacks behind the failure of the first attempt of mobile TV delivery by cooperating UMTS/DVB-H. We develop in this thesis a profit sharing strategy for the cooperative network, using coalition game concept Shapley value and Nash equilibrium for a self-enforcing strategy. We further develop a new framework using real option theory coupled with coalition games for investment decision in mobile TV networks (whether an operator should enter the mobile TV market and, if yes, when to do so) and show how operators can incorporate the uncertainties related to demand and network operation costs. We propose a bi-level dynamic programming algorithm to solve numerically the developed real option game.
14

Musil, Wittgenstein : l'Homme du possible / Musil, Wittgenstein : the Man of possibility

Fasula, Pierre 13 April 2013 (has links)
Au chapitre 4 de "L' Homme sans qualités", Musil présente son personnage principal, Ulrich, comme doué d'un sens du possible, qu'il définit ainsi : "L'homme qui en est doué, par exemple, ne dira pas : ici s'est produite, va se produire, doit se produire telle ou telle chose; mais il imaginera : ici pourrait, devrait se produire telle ou telle chose; et quand on lui dit d'une chose qu'elle est comme elle est, il pense qu’elle pourrait aussi bien être autre. Ainsi pourrait-on définir simplement le sens du possible comme la faculté de penser tout ce qui pourrait être "aussi bien", et de ne pas accorder plus d'importance à ce qui est qu'à ce qui n'est pas » (L''Homme sans qualités, §4). De manière générale, nous examinons ce sens du possible, dans ses différentes mises en œuvre, à l'aune des remarques conceptuelles de Wittgenstein sur la possibilité. Dans le domaine théorique, l'interprétation de la thèse de Musil sur Mach permet de montrer que, par comparaison avec la démarche scientifique, le sens du possible est la capacité à penser non seulement toutes les possibilités réelles mais aussi toutes les possibilités concevables, et ce par opposition à l'induction et à la recherche de causes. Dans le domaine de la conduite de la vie, la lecture philosophique d'un roman de Musil permet de montrer que le sens du possible est non pas la solution mais l'expression du problème de la vie juste (« comment dois-je vivre ?"). Enfin, dans une dernière partie, on rapporte le sens du possible au développement d'utopies, c'est-à-dire des vies et des hommes concevables mais pas nécessairement possibles en vertu de la réalité. / In the fourth chapter of "The Man without qualities", Robert Musil presents his main character, Ulrich, as endowed with a « sense of possibility» : "Whoever has it does not say, for instance : Here this or that has happened, will happen, must happen; but he invents : here this or that might, could or ought to happen. If he is told that something is the way it is, he will think : well, it could probably just as well be otherwise. So the sense of possibility could be defined outright as the ability to conceive of everything there might be just as well, and to attach no more importance to what it is than to what is not." (The Man without qualities, §4). ln a general way, on studies this sense of possibility, in its various applications, in relation with Wittgenstein's conceptual remarks. ln the theoretical field, the Interpretation of Musil's PhD on Mach allows to think that, by comparison with the scientific method, the sense of possibility is the ability to think not only all the real possibilities, but also the conceivable possibilities, by contrast with induction and research of causes. ln the field of the conduct of lite, the philosophical reading of the novel allows to think that the sense of possibility is not the solution but the expression of the problem of the right life. Finally, in the last part, one relates the sense of possibility to the development of utopias, of men and lifes conceivable but not necessarily possible by virtue of reality.
15

Caracteriza??o morfol?gica e sedimentologica da plataforma, continental brasileira adjacente aos munic?pios de Fortim, Aracati e Icapu?- CE

Oliveira, Patricia Reis Alencar 13 May 2009 (has links)
Made available in DSpace on 2015-03-13T17:08:23Z (GMT). No. of bitstreams: 1 PatriciaRAO.pdf: 5281930 bytes, checksum: 67be620244094cfb2196749d05935973 (MD5) Previous issue date: 2009-05-13 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The study area is located on the Brazilian Continental Shelf adjacent to Cear? State, inserted in the submerged Potiguar Basin. This area was submitted to extensional efforts during Upper Cretaceous, associated to the begining of the rifting that resulted in African and South American Continent separation. The main goal of this research was to better understand the sedimentary and geomorphological characteristics of the continental shelf adjacent to Fortim, Aracati and Icapu? (Cear? State). The used data base included geophysical (sides scan sonar and bathymetry studies) and sedimentological survey, associated to satellite image processing and interpretation. Inferences about suspended material and longshore drift was possible using satellite images, and differente bedforms were characterized such as: different kinds of dunes (longitudinal, cross and oblique), bioclastic banks, paleochannels, flat and rock bottom. The researched area comprehended about 2509,13 km2, where 6 different sedimentary facies, based on sediment composition and texture, could be recognized, such as: Bioclastic Sand, Siliciclastic Sand, Biosiliciclastic Sand, Bioclastic gravel, Biosiliciclastic sand with granule and gravel, and Silicibioclastic sand with granule and gravel. The integration of bathymetric, satellite image, side scan sonar and sedimentological data allow us a better characterization of this continental shelf area, as to advance in the knowledge of the continental shelf of the state of Ceara, a very important area to the oil industry because of its potential exploration and e exploitation, and to environmental survey as well / A ?rea em estudo compreende a Plataforma Continental Cearense inserida no contexto tect?nico e sedimentar da Bacia Potiguar, por??o submersa. Regi?o formada por esfor?os extensionais durante o Cret?ceo Inferior, associados ao in?cio do rifteamento que resultaria na separa??o das placas sul-americana e africana. Objetivando contribuir para um maior conhecimento das caracter?sticas sedimentol?gicas e geomorfol?gicas da plataforma continental adjacente aos munic?pios de Fortim, Aracati e Icapu? (CE). Foram realizado coleta, interpreta??o e integra??o de dados do sonar de varredura lateral, imagem de sat?lite, batimetria e amostras de sedimentos superficiais. Infer?ncias quanto ao material em suspens?o e deriva litor?nea foram obtidas a partir do processsamento digital de imagens (PDI), enquanto a caracteriza??o das fei??es do fundo marinho, tais como: dunas longitudinais, dunas transversais e dunas obliquas, bancos de sedimentos biocl?sticos, paleocanais submersos, leito plano e fundo rochoso foram obtidas a partir da integra??o de dados batim?tricos sonogr?ficos e PDI. Quanto a sedimentologia, com base na composi??o e textura, foram identificados na ?rea em estudo 6 f?cies sedimentares, abrangendo uma ?rea total de 2509,13 Km2, sendo elas: Areias Biocl?sticas, Areia Silicicl?stica, Areias Biosilicicl?sticas, Areia Cascalhosa Biocl?stica, Areia Cascalhosa Biosilicicl?stica e Areias Cascalhosas Silicibiocl?sticas; al?m de rochas praiais (beachrocks) e fundo rochoso. A integra??o entre os dados batim?tricos, PDI, sonogr?ficos e sedimentol?gicos, mostrou-se apropriada para a caracteriza??o morfol?gica e sedimentol?gica da Plataforma Continental da ?rea em estudo, desta forma avan?ando no conhecimento da Plataforma Continental Cearense, regi?o de interesse para a ind?stria do petr?leo tanto no ponto de vista da explota??o e explora??o de hidrocarbonetos, como tamb?m ambiental
16

Par?metros f?sico-qu?micos de estrelas nos campos de exoplanetas do sat?lite corot

?ngel, Cristi?n Andr?s Cort?s 02 December 2010 (has links)
Made available in DSpace on 2014-12-17T15:14:52Z (GMT). No. of bitstreams: 1 CristianACA_TESE.pdf: 1637371 bytes, checksum: 286a3a156c7aca7fdba8233b49b7891f (MD5) Previous issue date: 2010-12-02 / A rota??o estelar ? um dos mais importantes observ?veis da evolu??o estelar. Neste sentido, o sat?lite CoRoT representa uma oportunidade ?nica de medir os per?odos rotacionais para uma amostra de estrelas estatisticamente robusta, oferecendo dados absolutamente necess?rios para o estudo da rota??o e seu papel na evolu??o estelar. Para conseguir isto, um passo fundamental ? a caracteriza??o f?sica e qu?mica das estrelas observadas pelo CoRoT, especificamente devido ao fato de que o c?lculo de per?odos rotacionais confi?veis ? um trabalho dif?cil sem a ajuda dos par?metros estelares. Desta forma, foi elaborado um importante seguimento observacional das estrelas nos campos do CoRoT do anticentro LRa01 e do centro LRc01, permitindo a correta identifica??o dos per?odos que reflitam a modula??o rotacional. Nesta tese de doutorado s?o apresentados os resultados de tal seguimento. Par?metros f?sicos e qu?micos, tais como temperatura efetiva Teff , gravidade superficial log(g), velocidade de microturbul?ncia Vmic, abund?ncia de ferro [Fe/H], velocidade de rota??o projetada Vsin(i), e abund?ncia de l?tio A(Li) s?o apresentados para uma amostra de 116 estrelas dos campos CoRoT. Elas se encontram em diferentes est?gios evolutivos, desde a sequ?ncia principal (SP) at? o ramo das gigantes vermelhas (GV). As observa??es foram feitas utilizando os espectr?grafos UVES (VLT) e HYDRA (CTIO). Para a deriva??o de tais par?metros foram utilizados o programa TurboSpectrum e os modelos de atmosfera de MARCS. Paralelamente, velocidades rotacionais Vsin(i) foram obtidas a partir do ajuste dos perfis observados e sint?ticos das linhas de ferro e por meio de uma calibra??o de fun??o de correla??o cruzada (CCF). Per?odos rotacionais Prot para 77 estrelas da amostra foram obtidos a partir das curvas de luz do sat?lite CoRoT. Extensas tabelas destes par?metros e seus respectivos erros s?o apresentadas. Foram encontradas diferen?as nas distribui??es de Teff , [Fe/H] e est?gios evolutivos entre os diferentes campos do CoRoT, indicando poss?veis efeitos de sele??o na amostra, assim como a exist?ncia de diferentes popula??es estelares do disco Gal?ctico. Por outro lado, o comportamento rotacional e as abund?ncias de l?tio n?o apresentam diferen?as entre estrelas de par?metros f?sicos similares, mas que pertencem a diferentes campos do CoRoT. A partir da an?lise de temperaturas, foi encontrada uma maior extin??o por avermelhamento para estrelas do CoRoT localizadas no campo LRc01, assim como um gradiente deste valor em fun??o da dist?ncia. Os resultados mostram que as abund?ncias de l?tio, as velocidades de rota??o e os per?odos rotacionais apresentam o mesmo comportamento descrito na literatura. Por outro lado, ? apresentada pela primeira vez a rela??o que existe entre o l?tio e o per?odo de rota??o em diferentes est?gios evolutivos, mostrando, tal como era esperado, que ambas as grandezas possuem uma anticorrela??o. Tamb?m ? apresentada a evolu??o simult?nea da rota??o e do l?tio, e foram calculadas rela??es que permitem obter valores m?dios de A(Li) como fun??o da temperatura efetiva e do per?odo rotacional. Os dados apresentados nesta tese de doutorado representam um importante ponto de partida para serem utilizados como uma amostra de calibra??o para diferentes programas no contexto da miss?o do sat?lite CoRoT, uma vez que a lista de estrelas aqui analisadas s?o parte das mais brilhantes que comp?em o campo Exo do CoRoT
17

Natal tamb?m civiliza-se: sociabilidade, lazer e esporte na Belle ?poque Natalense (1900-1930)

Marinho, Marcia Maria Fonseca 27 June 2008 (has links)
Made available in DSpace on 2014-12-17T15:25:09Z (GMT). No. of bitstreams: 1 MarciaMFM.pdf: 873217 bytes, checksum: 3a842bd95e03d8fe86e011af8c46979b (MD5) Previous issue date: 2008-06-27 / Les initiatives du gouvernement ayant pour finalit? une r?organisation de la structure urbaine de la ville au d?but du XX?me si?cle refl?tent le d?sir v?cu par les membres de l'?lite locale d'encadrer Natal dans les moules des grands centres urbains de la m?me p?riode. Les ?lites d?siraient transformer Natal dans une ville moderne. Dans ce but, le gouvernement s'est engag? dans la reformulation de quelques espaces physiques de la ville. N?anmoins, il fallait aussi d autres que les transformations urbaines, la ville devrait passer par des r?formes sociales. De cette fa?on, ces groupes ont cr??es des nouvelles institutions et espaces de sociabilit? qui affirmeraient la capitale de l'?tat comme une ville moderne. Les institutions formelles avaient un r?le imortant dans la construction de cette nouvelle ville convoit?e par l'?lite locale. Ainsi, ? travers celles-ci, se diffusaient des nouvelles pratiques sociales qui seraient refl?t?es dans les espaces urbains. Dans des places tels, des caf?s, des clubs et associations sportives, l'?lite se distinguait du populaire. Dans ces places, leurs pratiques ?taient l?gitim?es, en contrepoint avec les pratiques populaires. C ?tait dans les clubs et par les activit?s pratiqu?es par leurs membres que les id?als de l'?lite circulaient, c ?tait par l? que l'?lite se formait et se transformait. De cette fa?on, les aspirations d'un groupe social refl?taient dans l'organisation sociale des espaces de la ville / As iniciativas do governo no sentido de uma reorganiza??o da estrutura urbana da cidade no in?cio do s?culo XX refletem o desejo vivido pelos membros da elite local de enquadrar Natal nos moldes dos grandes centros urbanos do in?cio do mesmo per?odo. Desejava-se transformar Natal numa cidade moderna. Nesse sentido, o governo empenhou-se na reformula??o de alguns espa?os f?sicos da cidade. No entanto, era preciso tamb?m que, al?m das transforma??es urbanas, a cidade passasse por reformas sociais. Desta forma, esses grupos criaram novas institui??es e espa?os de sociabilidade que afirmariam a capital do Estado como uma cidade moderna. As institui??es formais tinham um papel importante na constru??o dessa nova cidade almejada pela elite local. Pois, atrav?s dessas, difundiam-se novas pr?ticas sociais que seriam refletidas nos espa?os urbanos. Em lugares como caf?s, clubes e associa??es esportivas, a elite se distinguia do popular. Nesses lugares, suas pr?ticas eram legitimadas, em contraponto com as pr?ticas populares. Eram nos clubes e nas atividades praticadas pelos seus membros que os ideais da elite circulavam. Era l? que a elite se formava e se transformava. Dessa forma, as aspira??es de um grupo social se refletiam na organiza??o social dos espa?os da cidade
18

Fungování center Basic a LITE v České republice / The Functioning of the centers Basic and LITE in the Czech Republic

ŘÁDOVÁ, Lucie January 2011 (has links)
This thesis deals with analysis of the functioning of the tutorial centres Basic and language schools LITE. In the theory part there are alternative streams in education stated which are connected with these centres and Applied Scholastics is introduced which Basic and LITE are its part. It is also stated the standing of Applied Scholastics in the world. In the practical part is described study technology used in the centres Basic and LITE in general and then I looked more closely into the classes of Basic and LITE and described my observation. The research describes the functioning of these institutions in the Czech Republic. I also describe other activities of the centers and I think of positives and negatives of these classes.
19

Textlayout och prestation : Skrollning eller anpassad textstorlek i en mobil applikation

Lind, Simon January 2013 (has links)
Mobila applikationer för smarttelefoner är ett område som har expanderat under de senaste åren. Den lilla skärmen på smarttelefonen leder till att användare vanligtvis måste skrolla för att komma åt ytterligare information. Tidigare forskning har visat att skrollning påverkar läsförståelsen och minnet negativt. Denna studie har utvärderat detta fenomen genom att låta 67 frivilliga deltagare utföra tre uppgifter med en mobil applikation för smarttelefoner. Testet utformades med betingelserna skrolla och minskad textstorlek, för att rymma all text på en skärm. Datat samlades in via ett elektroniskt frågeformulär. Resultaten från denna studie visade att deltagarnas prestation vid skrollning var signifikant bättre för sökuppgiften och läsförståelseuppgiften. Det motsäger tidigare forskning och kan förklaras av att användarnas vanor kring smarttelefoner kan ha förändrats. Fortsatt forskning bör göras för att få en djupare förståelse för hur olika faktorer och vanor påverkar prestationen för smarttelefoner. / The market of mobile applications for smartphones has expanded during the last years. The small display on the smartphone results in the user having to scroll to get further information. Some studies have shown lower performance in reading comprehension and memory tasks when scrolling. This study investigated this phenomenon by letting 67 volunteers perform three tasks on a mobile application for smartphones. Scrolling and minimized font size to fit the screen were the conditions studied. The data were collected through an internet survey. The results of this study showed that performance for scrolling were significantly higher for the search task and the reading comprehension task. Contrary to earlier findings, this may be explained by changed habits and preferences with smartphones. Further research on performance and usage for smartphones is needed to gain further understanding.
20

Inconsistency and uncertainty handling in lightweight description logics / Dynamique des croyances et gestion de l'incertitude dans des logiques de description légères DL-Lite

Bouraoui, Zied 05 June 2015 (has links)
Cette thèse étudie la dynamique des croyances et la gestion de l’incertitude dans DL-Lite, une des plus importantes familles des logiques de description légères. La première partie de la thèse porte sur la gestion de l’incertitude dans DL-Lite. En premier lieu, nous avons proposé une extension des principaux fragments de DL-Lite pour faire face à l’incertitude associée aux axiomes en utilisant le cadre de la théorie des possibilités. Cette extension est réalisée sans engendrer des coûts calculatoires supplémentaires. Nous avons étudié ensuite la révision des bases DL-Lite possibilistes en présence d’une nouvelle information. Enfin, nous avons proposé un opérateur de fusion lorsque les assertions de ABoxsont fournies par plusieurs sources d’information ayant différents niveaux de priorité. La deuxième partie de la thèse traite le problème de la gestion d’incohérence dans les bases de connaissances DL-Lite. Nous avons étudié, tout d’abord, comment raisonner à partir d’une base DL-Lite standard avec des ABox multiples en introduisant les notions de modificateurs et de stratégies d’inférence. La combinaison des modificateurs et de stratégies d’inférence fournit une liste exhaustive des principales techniques de gestion de l’incohérence. Nous avons proposé ensuite une approche, basée sur un critère de cardinalité, de sélection des réparations, et nous avons identifié les stratégies appropriées pour la gestion de l’incohérence pour les bases DL-Lite stratifiées. Enfin, nous avons effectué une analyse comparative, suivie par des étudesexpérimentales, des différentes techniques de gestion d’incohérence proposées. Finalement, un outil de représentation et de raisonnement à partir des bases DL-Lite possibiliste est réalisé. / This thesis investigates the dynamics of beliefs and uncertainty management in DL-Lite, one of the most important lightweight description logics. The first part of the thesis concerns the problem of handling uncertainty in DL-Lite. First, we propose an extension of the main fragments of DL-Lite to deal with the uncertainty associated with axioms using a possibility theory framework without additional extra computational costs. We then study the revision of possibilistic DL-Lite bases when a new piece of information is available. Lastly, we propose a min-based assertional merging operator when assertions of ABox are provided by several sources of information having different levels of priority. The second partof the thesis concerns the problem of inconsistency handling in flat and prioritized DL-Lite knowledge bases. We first propose how to reason from a flat DL-Lite knowledge base, with a multiple ABox, which can be either issued from multiple information sources or resulted from revising DL-Lite knowledge bases. This is done by introducing the notions of modifiers and inference strategies. The combination of modifiers plus inference strategies can be mapped out in order to provide a principled and exhaustive list of techniques for inconsistency management. We then give an approach based on selecting multiple repairs using a cardinality-based criterion, and we identified suitable strategies for handling inconsistencyin the prioritized case. Lastly, we perform a comparative analysis, followed by experimental studies, of the proposed inconsistency handling techniques. A tool for representing and reasoning in possibilistic DL-Lite framework is implemented.

Page generated in 0.0575 seconds