Results 11 to 20 of about 2,754 (181)
Assessing the role of spatial externalities in the survival of Italian innovative startups
Regional Science Policy &Practice, EarlyView., 2023 Abstract The paper provides novel empirical evidence about the effects of spatial externalities on the survival of innovative startups in Italy. Using geocoded firm‐level data, we build micro‐geographic measures of specialization and diversity that are robust to the modifiable areal unit problem.
Diego Giuliani +4 more
wiley +1 more source
A Diagnostic to Assess the Fit of a Variogram Model to Spatial Data
Journal of Statistical Software, 1996 The fit of a variogram model to spatially-distributed data is often difficult to assess. A graphical diagnostic written in S-plus is introduced that allows the user to determine both the general quality of the fit of a variogram model, and to find ...
Ronald Barry
doaj +1 more source
Remote Sensing, 2023 The analysis of spatiotemporal changes of landscape patterns is of great significance for forest protection. However, the selection of landscape metrics is often subjective, and existing composite landscape metrics rarely consider the effects of spatial ...
Ying Zhang +3 more
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Zoning and uncertainty analysis of heavy metal pollution risk in surface water resources of copper mine by Bayesian analysis and sequential Gaussian simulation [PDF]
علوم محیطی, 2020 Introduction: Industrial and agricultural activities resulting in the production of toxic heavy metals may endanger water quality, public health, and the environment.
Akram Seifi, Hossien Riahi
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Mathematics, 2021 Variogram models are a valuable tool used to analyze the variability of a time series; such variability usually entails a spherical or exponential behavior, and so, models based on such functions are commonly used to fit and explain a time series ...
Francisco Gerardo Benavides-Bravo +4 more
doaj +1 more source
Spatio-temporal mapping of salinity in the heterogeneous coastal aquifer
Applied Water Science, 2019 The interface between freshwater and saltwater in the coastal aquifer is a main factor that is affected by environmental threat and excessive pumping. In this study, a density-dependent numerical model was utilized to simulate the salt distribution of a ...
Ali Ranjbar, Majid Ehteshami
doaj +1 more source
Verification with Variograms [PDF]
Weather and Forecasting, 2009 Abstract The verification of a gridded forecast field, for example, one produced by numerical weather prediction (NWP) models, cannot be performed on a gridpoint-by-gridpoint basis; that type of approach would ignore the spatial structures present in both forecast and observation fields, leading to misinformative or noninformative ...
Caren Marzban, Scott Sandgathe
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Empirical variogram for achieving the best valid variogram
Communications for Statistical Applications and Methods, 2020 Modeling the statistical autocorrelations in spatial data is often achieved through the estimation of the variograms, where the selection of the appropriate valid variogram model, especially for small samples, is crucial for achieving precise spatial prediction results from kriging interpolations. To estimate such a variogram, we traditionally start by
Esam Mahdi +2 more
openaire +2 more sources
A study of soil moisture variability for landmine detection by the neutron technique [PDF]
Nuclear Technology and Radiation Protection, 2007 This paper is focused on the space and temporal variability of soil moisture experimental data acquired at a few locations near landmine fields in the Tuzla Canton, as well as on the quantification of the statistical nature of soil moisture data on a ...
Avdić Senada
doaj +1 more source
Texture feature extraction of coal-rock image based on variogram and local variance image
Gong-kuang zidonghua, 2018 In view of problems of low classification accuracy and algorithmic running efficiency and poor robust property of rotation texture recognition existed in local binary patterns for texture feature extraction of coal-rock, a texture feature extraction ...
HUANG Lei, GUO Chaoya
doaj +1 more source