Search results for "Spatial"
showing 10 items of 2121 documents
On the property of diffusion in the spatial error model.
2005
International audience; The aim of this paper is to illustrate the property of global spillover effects in the first-order spatial autoregressive error model and the associated diffusion process of spatial shocks. An application is provided on a sample of 145 regions over 1989–1999 and highlights the most influential regions.
Space-time analysis of GDP disparities among European regions : a Markov chains approach
2004
The purpose of this paper is to study the evolution of the disparities between 138 European regions over the 1980-1995 period. We characterize the regional per capita GDP cross-sectional distribution by means of nonparametric estimations of density functions and we model the growth process as a first-order stationary Markov chain. Spatial effects are then introduced within the Markov chain framework using regional conditioning (Quah, 1996b) and spatial Markov chains (Rey, 2001). The results of the analysis indicate the persistence of regional disparities, a progressive bias toward a poverty trap and the importance of geography to explain the convergence process.
Correspondence between regional delineations and spatial patterns in macroinvertebrate assemblages of boreal headwater streams
2002
AbstractGeographical stratification may provide a useful framework for stream management programs, yet most studies testing the utility of such stratifications have been conducted in temperate regions. We studied the correspondence between regional delineations (5 ecoregions, 11 subecoregions), environmental characteristics, and benthic macroinvertebrate assemblages in 156 boreal headwater streams in Finland, using a combination of principal components analysis, nonmetric multidimensional scaling, and discriminant function analysis (DFA). Both stream characteristics and macroinvertebrate assemblage structure showed a closer correspondence to ecoregions than to subecoregions, a pattern partl…
Essay on the integration of interactions in the treatment effect evaluation : the contribution of spatial econometrics methods
2015
This thesis focuses on the integration of interactions in the estimation of the public policy’s effect. Indeed, the estimation standard methods usually rely on strong assumptions that exclude partially or completely the interaction effect both in the selection process of beneficiaries and in the performance of the policy. However, the validity of these assumptions is questionable, particularly in the context of a non-experimental policy because an individual according as it is the beneficiary or not the policy, is not isolated: he interacts with his neighborhood. Thus, the estimated effect of the policy by traditional methods is likely to be biased (underestimation or overestimation) theref…
Nonlocal properties of dynamical three-body Casimir-Polder forces
2005
We consider the three-body Casimir-Polder interaction between three atoms during their dynamical self-dressing. We show that the time-dependent three-body Casimir-Polder interaction energy displays nonlocal features related to quantum properties of the electromagnetic field and to the nonlocality of spatial field correlations. We discuss the measurability of this intriguing phenomenon and its relation with the usual concept of stationary three-body forces.
An Exploratory Spatial Data Analysis of European Regional Disparities, 1980–1995
2003
European integration has stimulated numerous studies of regional economic convergence within the European Union in recent macroeconomic and regional science literature (e.g. Abraham and Von Rompuy 1995; Armstrong 1995a; Neven and Gouyette 1995; Martin 2001). Most of the time, the empirical methods that have been used are identical to the methods employed in international studies. However, spatial effects, particularly spatial autocorrelation and spatial heterogeneity, must be taken into account when analyzing the convergence process at regional scale. There are number of factors — trade between regions, technology, knowledge diffusion and more generally regional spillovers — that lead to ge…
Packet Aggregation in TelosB WSNs: Design, Implementation and Experiments
2016
Master's thesis in Information- and communication technology IKT590 - University of Agder 2016 WSN is an extensive field of research and a core technology which is adopted for monitoring and data assembling, used in various applications. Traditionally in a WSN, communication is performed in the fashion of single packet per transmission which produces high energy consumption and longer delay. Therefore, we introduce a novel approach by designing a system which applies packet aggregation in TelosB sensor motes using Contiki platform. In this approach, we assemble multiple packets together and send them in an aggregated frame towards the sink which can reduce the number of transmissions, energ…
Getting into the groove: Opportunities to enhance the ecological value of hard coastal infrastructure using fine-scale surface textures
2015
Concrete flood defences, erosion control structures, port and harbour facilities, and renewable energy infrastructure are increasingly being built in the world’s coastal regions. There is, however, strong evidence to suggest that these structures are poor surrogates for natural rocky shores, often supporting assemblages with lower species abundance and diversity. Ecological engineering opportunities to enhance structures for biodiversity conservation (and other management goals) are therefore being sought, but the majority of work so far has concentrated on structural design features at the centimetre–meter scale.\ud \ud We deployed concrete tiles with four easily-reproducible fine-scale (m…
The Facilitation of Design Students’ Spatial Perception in Study Process
2015
Spatial thinking is a considerable structural component of design students’ professional competence. Objective of the current study is to evaluate and promote spatial perception of students using in the learning process principles of universal design for learning (UDL). As the result a model for development of design students spatial perception has been developed and approbated.
DRIFTS Sensor: Soil Carbon Validation at Large Scale (Pantelleria, Italy)
2013
A fast and accurate measurement of soil carbon is needed in current scientific issues. Today there are many sensors suitable for these purposes, but choosing the appropriate sensor depends on the spatial scale at which the studies are conducted. There are few detailed studies that validate these types of measures allowing their immediate use. Here it is validated the quick use of a sensor in execution at Pantelleria, chosen for size, use and variability of the parameter measured, to give an operational tool for carbon stocks studies. The DRIFT sensor used here has been validated in the first 60 cm of the soil of the whole island, and it has shown predictivity higher than 90%.