5 resultados para Spatial data warehouse

em Dalarna University College Electronic Archive


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Denna studie syftar till att undersöka hur en stor organisation arbetar med förvaltning av information genom att undersöka dess nuvarande informationsförvaltning, samt undersöka eventuella förslag till framtida informationsförvaltning. Vidare syftar studien också till att undersöka hur en stor organisation kan etablera en tydlig styrning, samverkan, hantering och ansvars- och rollfördelning kring informationsförvaltning. Denna studie är kvalitativ, där datainsamlingen sker genom dokumentstudier och intervjuer. Studien bedrivs med abduktion och är en normativ fallstudie då studiens mål är att ge vägledning och föreslå åtgärder till det fall som uppdragsgivaren har bett mig att studera. Fallet i denna studie är ett typiskt fall, då studiens resultat kan vara i intresse för fler än studiens uppdragsgivare, exempelvis organisationer med liknande informationsmiljö. För att samla teori till studien så har jag genomfört litteraturstudier om ämnen som är relevanta för studiens syfte: Informationsförvaltning, Business Intelligence, Data Warehouse och dess arkitektur, samt Business Intelligence Competency Center. Denna studie bidrar med praktiskt kunskapsbidrag, då studien ger svar på praktiska problem. Uppdragsgivaren har haft praktiska problem i och med en icke fungerade informationsförvaltning, och denna studie har bidragit med förslag på framtida informationsförvaltning. Förslaget på framtida informationsförvaltning involverar ett centraliserat Data Warehouse, samt utvecklingen utav en verksamhet som hanterar informationsförvaltning och styrningen kring informationsförvaltningen inom hela organisationen.

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We analyze a real data set pertaining to reindeer fecal pellet-group counts obtained from a survey conducted in a forest area in northern Sweden. In the data set, over 70% of counts are zeros, and there is high spatial correlation. We use conditionally autoregressive random effects for modeling of spatial correlation in a Poisson generalized linear mixed model (GLMM), quasi-Poisson hierarchical generalized linear model (HGLM), zero-inflated Poisson (ZIP), and hurdle models. The quasi-Poisson HGLM allows for both under- and overdispersion with excessive zeros, while the ZIP and hurdle models allow only for overdispersion. In analyzing the real data set, we see that the quasi-Poisson HGLMs can perform better than the other commonly used models, for example, ordinary Poisson HGLMs, spatial ZIP, and spatial hurdle models, and that the underdispersed Poisson HGLMs with spatial correlation fit the reindeer data best. We develop R codes for fitting these models using a unified algorithm for the HGLMs. Spatial count response with an extremely high proportion of zeros, and underdispersion can be successfully modeled using the quasi-Poisson HGLM with spatial random effects.

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GPS tracking of mobile objects provides spatial and temporal data for a broad range of applications including traffic management and control, transportation routing and planning. Previous transport research has focused on GPS tracking data as an appealing alternative to travel diaries. Moreover, the GPS based data are gradually becoming a cornerstone for real-time traffic management. Tracking data of vehicles from GPS devices are however susceptible to measurement errors – a neglected issue in transport research. By conducting a randomized experiment, we assess the reliability of GPS based traffic data on geographical position, velocity, and altitude for three types of vehicles; bike, car, and bus. We find the geographical positioning reliable, but with an error greater than postulated by the manufacturer and a non-negligible risk for aberrant positioning. Velocity is slightly underestimated, whereas altitude measurements are unreliable.

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Delineation of commuting regions has always been based on statistical units, often municipalities or wards. However, using these units has certain disadvantages as their land areas differ considerably. Much information is lost in the larger spatial base units and distortions in self-containment values, the main criterion in rule-based delineation procedures, occur. Alternatively, one can start from relatively small standard size units such as hexagons. In this way, much greater detail in spatial patterns is obtained. In this paper, regions are built by means of intrazonal maximization (Intramax) on the basis of hexagons. The use of geoprocessing tools, specifically developed for the processing ofcommuting data, speeds up processing time considerably. The results of the Intramax analysis are evaluated with travel-to-work area constraints, and comparisons are made with commuting fields, accessibility to employment, commuting flow density and network commuting flow size. From selected steps in the regionalization process, a hierarchy of nested commuting regions emerges, revealing the complexity of commuting patterns.