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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

A MULTI-FUNCTIONAL PROVENANCE ARCHITECTURE: CHALLENGES AND SOLUTIONS

2013 December 1900 (has links)
In service-oriented environments, services are put together in the form of a workflow with the aim of distributed problem solving. Capturing the execution details of the services' transformations is a significant advantage of using workflows. These execution details, referred to as provenance information, are usually traced automatically and stored in provenance stores. Provenance data contains the data recorded by a workflow engine during a workflow execution. It identifies what data is passed between services, which services are involved, and how results are eventually generated for particular sets of input values. Provenance information is of great importance and has found its way through areas in computer science such as: Bioinformatics, database, social, sensor networks, etc. Current exploitation and application of provenance data is very limited as provenance systems started being developed for specific applications. Thus, applying learning and knowledge discovery methods to provenance data can provide rich and useful information on workflows and services. Therefore, in this work, the challenges with workflows and services are studied to discover the possibilities and benefits of providing solutions by using provenance data. A multifunctional architecture is presented which addresses the workflow and service issues by exploiting provenance data. These challenges include workflow composition, abstract workflow selection, refinement, evaluation, and graph model extraction. The specific contribution of the proposed architecture is its novelty in providing a basis for taking advantage of the previous execution details of services and workflows along with artificial intelligence and knowledge management techniques to resolve the major challenges regarding workflows. The presented architecture is application-independent and could be deployed in any area. The requirements for such an architecture along with its building components are discussed. Furthermore, the responsibility of the components, related works and the implementation details of the architecture along with each component are presented.
2

Causal Inference on Tactical Simulations using Bayesian Structure Learning

Lagerkvist Blomqvist, Karl January 2022 (has links)
This thesis explores the possibility of using Bayesian Structure Learning and Do-Calculus to perform causal inference on data from tactical combat simulations provided by Saab. A four-step approach is considered whose first step is to find a Bayesian Network from the data using Bayesian Structure Learning and Probability Distribution Fitting. These Bayesian Networks describe a set of conditional independencies ambiguously. This ambiguity gives rise to a set of feasible Structural Causal Models that describes feasible causal relationships in the data. The approach then continues in its second step by selecting at least one of these Structural Causal Models that can be utilized for performing causal inference using Do-Calculus and Probabilistic Inference in the approach’s third and fourth steps respectively. The thesis concludes that there exist several difficulties with the approach that together with a lack of a methodology for error estimation reduces the method’s reliability. The recommendation is thus to consider the possibility of performing randomized controlled experiments using the tactical simulator before continuing the development of this approach. / Det här examensarbetet utforskar möjligheten att använda Bayesiansk Strukturinlärning och Do-Calculus för att utföra Kausal Inferens på data från taktiska stridsimuleringar framtagna av Saab. En fyrastegsmetod beaktas vars första steg är att hitta ett Bayesiansk Nätverk genom användandet av Bayesiansk Strukturinlärning och Sannolikhetsfördelnings-anpassning. Dessa Bayesianska Nätverk beskriver en mängd betingade oberoendet i datamängden på ett icke-entydligt sett. Denna icke-entydlighet ger upphov till en mängd av möjliga Strukturella Kausala Modeller som beskriver möjliga kausala strukturer i datamängden. Metodens andra steg fortsätter med att välja minst en av dessa Strukturella Kausala Modeller som kan användas för att åstakomma Kausal Inferens med hjälp av Do-Calculus och Stokastisk Inferens i metodens tredje respektive fjärde steg. Slutsatsen från examensarbetet är att det finns ett flertal svårigheter med metoden som tillsamans med en avsaknad av en feluppskattningsmetodik minskar metodens tillförlitlighet. Rekommendationen är därför att undersöka möjligheten att genomföra kontrollerade slumpmässiga experiment innan metodiken vidareutvecklas.

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