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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.
1

Proposition d'une nouvelle méthode de conception de cubes SOLAP exploitant des données spatiales vagues / Handling spatial vagueness issues in SOLAP datacubes by introducing a risk-aware approach in their design

Edoh-Alove, Djogbénuyè Akpé 10 April 2015 (has links)
Les systèmes Spatial On-Line Analytical Processing (SOLAP) permettent de prendre en charge l’analyse multidimensionnelle en ligne d’un très grand volume de données ayant une référence spatiale. Dans ces systèmes, le vague spatial n’est généralement pas pris en compte, ce qui peut être source d’erreurs dans les analyses et les interprétations des cubes de données SOLAP, effectuées par les utilisateurs finaux. Bien qu’il existe des modèles d’objets ad-hoc pour gérer le vague spatial, l’implantation de ces modèles dans les systèmes SOLAP est encore à l’état embryonnaire. En outre, l’introduction de tels modèles dans les systèmes SOLAP accroit la complexité de l’analyse au détriment de l’utilisabilité dans bon nombre de contextes applicatifs. Dans cette thèse nous nous proposons d’investiguer la piste d’une nouvelle approche visant un compromis approprié entre l’exactitude théorique de la réponse au vague spatial, la facilité d’implantation dans les systèmes SOLAP existants et l’utilisabilité des cubes de données fournis aux utilisateurs finaux.Les objectifs de cette thèse sont donc de jeter les bases d’une approche de conception de cube SOLAP où la gestion du vague est remplacée par la gestion des risques de mauvaises interprétations induits, d’en définir les principes d’une implantation pratique et d’en démontrer les avantages.En résultats aux travaux menés, une approche de conception de cubes SOLAP où le risque de mauvaise interprétation est considéré et géré de manière itérative et en adéquation avec les sensibilités des utilisateurs finaux quant aux risques potentiels identifiés a été proposée; des outils formels à savoir un profil UML adapté, des fonctions de modification de schémas multidimensionnels pour construire les cubes souhaités, et un processus formel guidant de telles transformations de schémas ont été présentés; la vérification de la faisabilité de notre approche dans un cadre purement informatique avec la mise en oeuvre de l’approche dans un outil CASE (Computed Aided Software Engineering) a aussi été présentée. Pour finir, nous avons pu valider le fait que l’approche fournisse non seulement des cubes aussi compréhensibles et donc utilisables que les cubes classiques, mais aussi des cubes où le vague n’est plus laissé de côté, sans aucun effort pour atténuer ses impacts sur les analyses et les prises de décision des utilisateurs finaux. / SOLAP (Spatial On-Line Analytical Processing) systems support the online multi-dimensional analysis of a very large volume of data with a spatial reference. In these systems, the spatial vagueness is usually not taken into account, which can lead to errors in the SOLAP datacubes analyzes and interpretations end-users make. Although there are ad-hoc models of vague objects to manage the spatial vagueness, the implementation of these models in SOLAP systems is still in an embryonal state. In addition, the introduction of such models in SOLAP systems increases the complexity of the analysis at the expense of usability in many application contexts. In this thesis we propose to investigate the trail of a new approach that makes an appropriate compromise between the theoretical accuracy of the response to the spatial vagueness, the ease of implementation in existing SOLAP systems and the usability of datacubes provided to end users.The objectives of this thesis are to lay the foundations of a SOLAP datacube design approach where spatial vagueness management in itself is replaced by the management of risks of misinterpretations induced by the vagueness, to define the principles of a practical implementation of the approach and to demonstrate its benefits.The results of this thesis consist of a SOLAP datacube design approach where the risks of misinterpretation are considered and managed in an iterative manner and in line with the end users tolerance levels regarding those risks; formal tools namely a suitable UML (Unified Modeling Language) profile, multidimensional schemas transformation functions to help tailored the datacubes to end-users tolerance levels, and a formal process guiding such schemas transformation; verifying the feasibility of our approach in a computing context with the implementation of the approach in a CASE (Computed Aided Software Engineering) tool. Finally, we were able to validate that the approach provides SOLAP datacubes that are not only as comprehensible and thus usable as conventional datacubes but also datacubes where the spatial vagueness is not left out, with no effort to mitigate its impacts on analysis and decision making for end users.
2

Geração de dados espaciais vagos baseada em modelos exatos

Proença, Fernando Roberto 29 May 2013 (has links)
Made available in DSpace on 2016-06-02T19:06:05Z (GMT). No. of bitstreams: 1 5287.pdf: 3924606 bytes, checksum: 935b5a09df26eb1b41df901a189a6e2a (MD5) Previous issue date: 2013-05-29 / Universidade Federal de Sao Carlos / Geographic information systems with the aid of spatial databases store and manage crisp spatial data (or exact spatial data), whose shapes (boundaries) are well defined and have a precise location in space. However, several spatial data do not have precisely known boundaries or have an uncertain location in space, which are called vague spatial data. The boundaries of a given vague spatial data may shrink or extend, therefore, may have a minimum and maximum extension. Clouds of pollution, deforestation, fire outbreaks, route of an airplane, habitats of plants and animals are examples of vague spatial data. In the literature, there are currently vague spatial data models, such as Egg-Yolk, QMM and VASA. However, according to our knowledge, they focus only on the formal aspect of the model definition. Thus, real or synthetic vague spatial data is not available for use. The main objective of this master thesis is the development of algorithms for the generation of synthetic vague spatial data based on the crisp models of spatial data vague Egg-Yolk, QMM and VASA. It was also implemented a tool, called VagueDataGeneration, to assist in the process of generation such data. For both the algorithms and the tool, the user is able to set the properties related to the data type of model, such as size, shape, volume, complexity, location and spatial distribution. By using the proposed algorithms and the VagueDataGeneration tool, researchers can generate large samples of vague spatial data, enabling new research, such as testing indexes for vague spatial data or evaluating query processing over data warehouses that store vague spatial data. The validation of the vague spatial data generation was conducted using a case study with data from vague rural phenomena. / Sistemas de informação geográfica com o auxílio de bancos de dados espaciais armazenam e gerenciam dados espaciais exatos, cujas formas (fronteiras) são bem definidas e que possuem uma localização exata no espaço. Entretanto, vários dados espaciais reais não possuem os seus limites precisamente conhecidos ou possuem uma localização incerta no espaço, os quais são denominados dados espaciais vagos. Os limites de um dado espacial vago podem encolher ou estender, portanto, podem ter uma extensão mínima e máxima. Nuvens de poluição, desmatamentos, focos de incêndios, rota de um avião, habitats de plantas e de animais são exemplos de dados espaciais vagos. Na literatura, atualmente existem modelos de dados espaciais vagos, tais como Egg-Yolk, QMM e VASA. No entanto, segundo o nosso conhecimento, estes enfocam apenas no aspecto formal da definição do modelo. Com isso, dados espaciais vagos reais ou sintéticos não estão disponíveis para uso. O principal objetivo deste trabalho de mestrado consiste no desenvolvimento de algoritmos para a geração de dados espaciais vagos sintéticos baseados nos modelos exatos de dados espaciais vagos Egg-Yolk, QMM e VASA. Também foi implementada uma ferramenta, chamada VagueDataGeneration, para auxiliar no processo de geração desses dados. Nos algoritmos propostos e na ferramenta desenvolvida, o usuário define as propriedades referentes ao tipo de dado de um modelo, tais como tamanho, formato, volume, complexidade, localização e distribuição espacial dos dados espaciais vagos a serem gerados. Por meio do uso dos algoritmos propostos e da ferramenta VagueDataGeneration, os pesquisadores podem gerar grandes amostras de dados espaciais vagos, possibilitando novas pesquisas, como exemplo, testar índices para dados espaciais vagos ou testar técnicas de processamento de consultas em Data Warehouses que armazenam dados espaciais vagos. A validação da geração de dados espaciais vagos foi efetuada usando um estudo de caso com dados de fenômenos rurais vagos.
3

Incorporando dados espaciais vagos em data warehouses geográficos: a proposta do tipo abstrato de dados vaguegeometry

Carniel, Anderson Chaves 09 October 2014 (has links)
Made available in DSpace on 2016-06-02T19:06:18Z (GMT). No. of bitstreams: 1 6327.pdf: 10668384 bytes, checksum: 806ac414d43596c366d93b4bfc0febe0 (MD5) Previous issue date: 2014-10-09 / Universidade Federal de Minas Gerais / A data warehouse is a solution for organizing and storing multidimensional data related to decision-making processes in companies, generating a historical, highly voluminous, subject-oriented and nonvolatile database. A geographic data warehouse (GDW) additio¬nally to the conventional data storage (i.e. numeric and alphanumeric data), stores spatial data as attributes in dimension tables or as measures in fact tables, storing data represented by geometries. Points, lines and polygons are examples of spatial data types. While spatial data currently stored in GDWs are crisp, i.e., they have exact location in the space, strict interiors and well-defined boundaries, geographic applications have required the storage of vague spatial data, which have inaccurate location, inexact interiors or uncertain bounda¬ries. This Master s research aims at incorporating vague spatial data to GDWs. More speci¬fically, we propose and implement a new abstract data type (ADT) called VagueGeometry to represent vague spatial data in the Spatial Database Management System (SDBMS) Post- greSQL/PostGIS. The proposal of the ADT VagueGeometry encompasses the issue of phy¬sical storage for vague spatial data, which are complex and can have several disjoint parts. It also focuses on definitions of operations to handle vague spatial objects, such as vague topological predicates and its operators. Experimental evaluations were conducted in order to assess the performance of the ADT VagueGeometry in comparison to available solutions, such as implementation of vague topological predicates utilizing existing operations of the PostGIS. The proposed ADT VagueGeometry shown reductions in query processing with vague topological predicates from 81.63% to 90.34% in spatial databases and reductions from 92.46% a 95.20% in GDW environments. This Master s project, therefore, advances in the state of art in GDWs to study this gap in the literature. Additionally, fuzzy models to represent vague spatial data was also studied, and as a result, a preliminary proposal of a ADT, called as FuzzyGeometry, was also developed. / Um data warehouse é uma solução para a organização e o armazenamento de dados mul-tidimensionais relacionados a tomada de decisão estratégica em empresas, constituindo um banco de dados histórico, volumoso, orientado ao assunto e não volátil. Um data warehouse geográfico (DWG) adicionalmente ao armazenamento de dados convencionais (tais como dados numéricos e alfanuméricos), armazena dados espaciais como atributos em tabelas de dimensão ou como medidas em tabelas de fatos, ou seja, armazena dados representados por meio de geometrias. Pontos, linhas e polígonos são exemplos de dados espaciais armazena¬dos. Enquanto estes dados armazenados atualmente em DWGs sao crisp, ou seja, possuem localização, interiores e fronteiras bem definidas, aplicações geográficas tem demandado o armazenamento de dados espaciais vagos, os quais possuem localização, interiores ou fronteiras incertas. Esta pesquisa de mestrado visa incorporar dados espaciais vagos em DWGs. Mais especificamente, foi proposto e implementado um novo tipo abstrato de dados (TAD), denominado VagueGeometry, para representar dados espaciais vagos no Sistema Gerenciador de Banco de Dados (SGBD) PostgreSQL com a extensão espacial PostGIS. A proposta do TAD VagueGeometry engloba a proposta de uma forma de armazenamento interna para os dados espaciais vagos, os quais são complexos e podem possuir diversas partes disjuntas. Isso também inclui a definição de operações para manipular objetos espa¬ciais vagos, tais como os relacionamentos topológicos vagos e seus operadores. Avaliações experimentais foram conduzidas para medir o desempenho do TAD VagueGeometry frente a soluções existentes, tal como a implementação de predicados topológicos vagos reuti¬lizando operações existentes do PostGIS. A proposta do TAD VagueGeometry apresentou reduções no tempo de processamento de predicados topológicos vagos de 81,63% a 90,34% em bancos de dados espaciais e reduções de 92,46% a 95,20% em ambientes de DWG. Este trabalho, portanto, avança no estado da arte em DWGs de forma a preencher essa lacuna existente na literatura. Adicionalmente, modelos fuzzy para representação dos dados espa¬ciais vagos também foram estudados e uma proposta preliminar de um TAD, denominado FuzzyGeometry, também foi desenvolvida.

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