Search results for "kriging"
showing 10 items of 93 documents
Geoestadística en regiones heterogéneas con distancia basada en el coste
2012
El germen de la presente tesis consistió en un problema aplicado, de ingeniería, al que pensamos que la Estadística como disciplina puede contribuir de manera significativa. Concretamente, se trata de la elaboración de mapas acústicos en entornos urbanos. Resuelto habitualmente de una manera determinista y aproximada, la valoración de la incertidumbre de los resultados es extremadamente deficiente en la mayoría de los casos reales. Este problema, siendo de naturaleza espacial, se puede ver como un problema de predicción geoestadística, a partir de un conjunto de observaciones de campo. La dificultad radica en que el fenómeno se sitúa en un entorno urbano, que posee una importante heterogene…
Telpiskās statistikas metodes programmā R
2015
Bakalaura darbā aplūkota programmas R veiktspēja apstrādāt, analizēt un attēlot telpiska veida datus. Aprakstīti telpisko datu veidi, kā arī to struktūra programmā R. Veikts ieskatas telpiskajos punktu modeļos, kā arī telpiskajā autokorelācijā un interpolācijā. Paņemti dati no Latvijas meteroloģijas centra par relatīvo mitrumu vairākās stacijās. Izpētīta to autokorelācija ar variogrammas palīdzību. Meklēts labākais modelis empīriskajai variogrammai, kā arī veikta interpolācija pēc vairākām metodēm (Tīsena poligonu, inversā attāluma un parastā kriginga) lai iegūtu vērtības vietās, kur mērījumi netika veikti. Tika secināts, ka programma R ir ļoti kompetenta darbībai ar telpiskajiem datiem, re…
Wind speed spatial estimation for energy planning in Sicily: introduction and statistical analysis
2008
Abstract The exploitation of the renewable energy sources plays a key role for achieving the CO 2 emissions reduction targets established by the Kyoto Protocol, as well as for facing the shortage of world fossil fuels reserves. In countries like Italy, with an high potential in terms of wind power generation, an efficient energy planning based on renewables is a very complex task. It encompasses many aspects: the resource availability assessment, the compliance with environmental and legislative constraints and last, but not least, the technical aspects linked to the safe integration to the grid of the intermittent power generated by the wind farms. This paper is the first part of a study a…
Inference of Spatiotemporal Processes over Graphs via Kernel Kriged Kalman Filtering
2018
Inference of space-time signals evolving over graphs emerges naturally in a number of network science related applications. A frequently encountered challenge pertains to reconstructing such dynamic processes given their values over a subset of vertices and time instants. The present paper develops a graph-aware kernel-based kriged Kalman filtering approach that leverages the spatio-temporal dynamics to allow for efficient online reconstruction, while also coping with dynamically evolving network topologies. Laplacian kernels are employed to perform kriging over the graph when spatial second-order statistics are unknown, as is often the case. Numerical tests with synthetic and real data ill…
Geostatistics for Mapping Leaf Area Index over a Cropland Landscape: Efficiency Sampling Assessment
2010
This paper evaluates the performance of spatial methods to estimate leaf area index (LAI) fields from ground-based measurements at high-spatial resolution over a cropland landscape. Three geostatistical model variants of the kriging technique, the ordinary kriging (OK), the collocated cokriging (CKC) and kriging with an external drift (KED) are used. The study focused on the influence of the spatial sampling protocol, auxiliary information, and spatial resolution in the estimates. The main advantage of these models lies in the possibility of considering the spatial dependence of the data and, in the case of the KED and CKC, the auxiliary information for each location used for prediction pur…
Distributed spatial prediction for radio environment maps reconstruction in heterogeneous wireless networks
2017
Las previsiones indican que el tráfico de datos móviles se multiplicará por siete en el periodo de 2016 a 2021, creciendo con una tasa agregada anual del 47%. Para satisfacer esta demanda, tanto la industria como la academia se están centrando en las redes de quinta generación o 5G. Las redes 5G se espera que constituyan un entorno complejo e interconectado, que además proporciones múltiples servicios y aplicaciones a un número masivo de usuarios y máquinas. En este concepto se incluye la necesidad de dar soporte o de crear servicios para el paradigma conocido como el Internet de las Cosas (IoT), donde la visión es la de crear un entorno de todo conectado con todo en todo momento, con aplic…
Mapping a-priori defined plant associations using remotely sensed vegetation characteristics
2014
Abstract Incorporation of a priori defined plant associations into remote sensing products is a major challenge that has only recently been confronted by the remote sensing community. We present an approach to map the spatial distribution of such associations by using plant indicator values (IVs) for salinity, moisture and nutrients as an intermediate between spectral reflectance and association occurrences. For a 12 km 2 study site in the Netherlands, the relations between observed IVs at local vegetation plots and visible and near-infrared (VNIR) and short-wave infrared (SWIR) airborne reflectance data were modelled using Gaussian Process Regression (GPR) (R 2 0.73, 0.64 and 0.76 for sali…
Modelling the Impacts of Wildfire on Ash Thickness in a Short‐Term Period
2013
Ash can provide valuable soil protection. However, ash is also very mobile, and soil protection patterns can be quickly changed, favouring the protection of some areas and exposing others with implications for soil erosion. In this research, the effects of a high severity wildfire on ash thickness were studied, 1 and 15 days after the fire. For this evaluation, several interpolation methods were tested to identify the best spatial predictor of ash distribution. The results showed that 1 day after the fire, ash was thinner in high severity areas. Fifteen days after the fire, ash thickness decreased, and the spatial pattern changed. This implies that evaluation of fire severity based on ash t…
Comparative Analysis of Spatial Interpolation Methods in the Mediterranean Area: Application to Temperature in Sicily
2015
An exhaustive comparison among different spatial interpolation algorithms was carried out in order to derive annual and monthly air temperature maps for Sicily (Italy). Deterministic, data-driven and geostatistics algorithms were used, in some cases adding the elevation information and other physiographic variables to improve the performance of interpolation techniques and the reconstruction of the air temperature field. The dataset is given by air temperature data coming from 84 stations spread around the island of Sicily. The interpolation algorithms were optimized by using a subset of the available dataset, while the remaining subset was used to validate the results in terms of the accur…
Comparing Different approaches - Data mining, Geostatistic, and Deterministic pedology - to assess the Frequency of WRB reference soil groups in the …
2014
Estimating frequency of soil classes in map unit is always affected by some degree of uncertainty, especially at small scales, with a larger generalization. The aim of this study was to compare different possible approaches - data mining, geostatistic, deterministic pedology - to assess the frequency of WRB Reference Soil Groups (RSG) in the major Italian soil regions. In the soil map of Italy (Costantini et al., 2012), a list of the first five RSG was reported in each major 10 soil regions. The soil map was produced using the national soil geodatabase, which stored 22,015 analyzed and classified pedons, 1,413 soil typological unit (STU) and a set of auxiliary variables (lithology, land-use…