2,579 research outputs found
Topological Susceptibility from Slabs
In quantum field theories with topological sectors, a non-perturbative
quantity of interest is the topological susceptibility chi_t. In principle it
seems straightforward to measure chi_t by means of Monte Carlo simulations.
However, for local update algorithms and fine lattice spacings, this tends to
be difficult, since the Monte Carlo history rarely changes the topological
sector. Here we test a method to measure chi_t even if data from only one
sector are available. It is based on the topological charges in sub-volumes,
which we denote as slabs. Assuming a Gaussian distribution of these charges,
this method enables the evaluation of chi_t, as we demonstrate with numerical
results for non-linear sigma-models.Comment: 23 pages, 8 figures, 6 table
Advancement in Conceptualizing Cross-Border Daily Mobility: the Benelux Context in the European Union
Based on specific characteristics of mobility, the cross-border commuter status still has some ambiguities, whether in legal, geographic, economic or more generally in social or cultural terms. This paper aims at providing theoretical advancement to this specific cross-border mobility, especially through the transfer of a theoretical model using a cross-scale analysis based on two complementary concepts. The first corresponds to âborder confirmingâ and is measured at the macro level, including the economic differentials on both sides of the border. The second concept is called âborder transcendingâ and focuses on the individual level. It is based on the assessment of the psychosocial barriers that may fade as the daily practices of the border rise. This exploratory approach is tested within the European context of Benelux. The results, although they cannot be generalised due to a lack of comparable data, offer research perspectives. So far, the existence of a cross-border catchment area, tested on the Belgian cross-border commuters working in Luxembourg, is a reality for many
An Approach for spatial and temporal data analysis: application for mobility modeling of workers in Luxembourg and its bordering areas
In this paper, we propose a general visual analytic approach to synthesis very large spatial data and discover interesting knowledge and unknown patterns from complex data based on Origin-Destination (OD) matrices. The research studies of Tobler constitute a good basis in this topic. This paper is interested in the proposal of 2 methods entitled respectively ?Weighted Linear Directional Mean: WLDM? and ?DS-WLDM?. The latter incorporates the Dempster-Shafer theory of evidence with WLDM. Both of the developed methods are an extension of ?Linear Directional Mean: LDM? for mobility modeling. With classical techniques such as LDM among others, the results of data mapping are not intelligible and easy to interpret. However with both WLDM and DS-WLDM methods it is easy to discover knowledge without losing a lot of information which is one of the interests of this paper. This proposal is generic and it intends to be applied for data mapping such as for geographical presentation of social and demographic information (e.g. mobility of people, goods and information) according to multiple spatial scales (e.g. locality, district, municipality). It could be applied also in transportation field (e.g. traffic flow). For the application, administrative data is used in order to evaluate spatial and temporal aspects of the daily and the residential mobility of workers in Luxembourg and its bordering areas.Mobility modeling; data mapping; spatial mobility; geographic knowledge discovery; location uncertainty; daily and residential mobility
Impacts de la mobilité résidentielle transfrontaliÚre sur les espaces de la vie quotidienne d'individus actifs du Luxembourg.
Ă partir d'une enquĂȘte effectuĂ©e par le CEPS/INSTEAD et la fondation Forum Europa, cet article analyse le phĂ©nomĂšne de mobilitĂ© rĂ©sidentielle transfrontaliĂšre et son impact sur les dĂ©placements quotidiens. RĂ©alisĂ©e au printemps 2008, cette enquĂȘte porte sur les actifs occupĂ©s rĂ©sidant initialement au Luxembourg qui se sont installĂ©s dans un pays frontalier entre 2001 et 2007, tout en conservant leur emploi au Grand-DuchĂ©. Pour un grand nombre d'entre eux, le dĂ©mĂ©nagement transfrontalier a permis d'accĂ©der Ă un logement plus grand, voire d'en devenir propriĂ©taire. NĂ©anmoins, l'analyse des dĂ©placements quotidiens montre que la plupart de ces personnes a dĂ» consentir Ă de nombreuses concessions en termes de mobilitĂ© pour accĂ©der au logement souhaitĂ©. Cela se ressent particuliĂšrement pour le trajet domicile/travail dont la distance moyenne a doublĂ©, ce qui a renforcĂ© la dĂ©pendance Ă l'automobile des personnes concernĂ©es . En dehors mĂȘme du travail, la localisation des autres activitĂ©s quotidiennes se trouve modifiĂ©e Ă la suite du dĂ©mĂ©nagement. Des indicateurs synthĂ©tiques issus de la gĂ©ostatistique permettent d'analyser la reconfiguration des lieux de ces activitĂ©s. MalgrĂ© la relocalisation de beaucoup d'entre elles autour du nouveau lieu de rĂ©sidence, une certaine inertie des comportements se traduit par le maintien de prĂšs d'une activitĂ© sur trois au Luxembourg. DĂšs lors, la dispersion des espaces d'activitĂ©s augmente pour certains enquĂȘtĂ©s. Elle est liĂ©e Ă la part des activitĂ©s transfĂ©rĂ©es vers le pays de rĂ©sidence, varie fortement selon la nationalitĂ© ; elle est plus forte pour les Luxembourgeois et les Portugais. Les personnes originaires des rĂ©gions frontaliĂšres, qui retournent dans leur pays d'origine, gardent Ă©galement prĂšs d'un quart de leurs activitĂ©s au Grand-DuchĂ© : cela tĂ©moigne de l'importance du lieu de travail dans la structuration des espaces de vie quotidienne et d'un capital spatial dĂ©jĂ mis en Ă©vidence dans le cas d'actifs rĂ©sidant au Luxembourg
The Slab Method to Measure the Topological Susceptibility
In simulations of a model with topological sectors, algorithms which proceed
in small update steps tend to get stuck in one sector, especially on fine
lattices. This distorts the numerical results; in particular it is not
straightforward to measure the topological susceptibility chi_t. We test a
method to measure chi_t even if configurations from only one sector are
available. It is based on the topological charges in sub-volumes, which we
denote as "slab". This enables the evaluation of chi_t, as we demonstrate with
numerical results for non-linear sigma-models and for 2-flavour QCD. In the
latter case, the gradient flow is applied for the smoothing of the gauge
configurations, and the slab method results for chi_t are stable over a broad
range of flow times.Comment: 7 pages, 7 figures, talk presented at the 34th International
Symposium on Lattice Field Theory, 24-30 July 2016, Southampton, UK. Minor
corrections, references added, Fig. 5 replace
Cartographier une enquĂȘte Ă l'Ă©chelle intra-urbaine: bien-ĂȘtre et personnes ĂągĂ©es de la ville de Luxembourg
Cet article a pour objectif dâexposer une dĂ©marche mĂ©thodologique originale. Elle vise, Ă partir dâun Ă©chantillon stratifiĂ© spatialement dâune population enquĂȘtĂ©e, Ă reconstituer la population totale et de la projeter dans lâespace urbain de la ville Ă une Ă©chelle plus petite. Cela permet de donner une dimension gĂ©ographique intra-urbaine aux informations contenues dans les rĂ©sultats dâenquĂȘte. Pour cela, nous nous basons sur lâexemple de lâenquĂȘte « Personnes ĂgĂ©es Ville de Luxembourg », effectuĂ©e en 2002, qui avait pour but dâapprĂ©cier les besoins de ces personnes vivant Ă leur domicile.GIS ; Mapping ; Survey ; Elderly ; Wellbeing
Topology in the 2d Heisenberg Model under Gradient Flow
The 2d Heisenberg model --- or 2d O(3) model --- is popular in condensed
matter physics, and in particle physics as a toy model for QCD. Along with
other analogies, it shares with 4d Yang-Mills theories, and with QCD, the
property that the configurations are divided in topological sectors. In the
lattice regularisation the topological charge can still be defined such
that . It has generally been observed, however, that the
topological susceptibility does not
scale properly in the continuum limit, i.e. that the quantity diverges for (where is the correlation length in
lattice units). Here we address the question whether or not this divergence
persists after the application of the Gradient Flow.Comment: 10 pages, LaTex, 7 figures, 2 tables, talk presented at the XXXI
Reuni\'on Anual de la Divisi\'on de Part\'iculas y Campos de la Sociedad
Mexicana de F\'isica (CINVESTAV, Mexico City
Simulation of land use changes using cellular automata and artificial neural network
This paper presents a method integrating artificial neural network (ANN) in cellular automata (CA) to simulate land use changes in Luxembourg and the areas adjacent to its borders. The ANN is used as a base of CA model transition rule. The proposed method shows promising results for prediction of land use over time. The ANN is validated using cross-validation technique and Receiver Operating Characteristic (ROC) curve analysis, and compared with logit model and a support vector machine approach. The application described in this paper highlights the interest of integrating ANNs in CA based model for land use dynamic simulation.Artificial neural network; Cellular automata; Modelling; Land use changes; Spatial planning and dynamics
Pour une approche normative de lâamĂ©nagement. Simulation de scĂ©narios de dĂ©veloppement rĂ©sidentiel au Luxembourg
National audienceLâobjectif de cette communication est de prĂ©senter les rĂ©sultats obtenus dans le cadre dâun travail de thĂšse (projet COSMELUX, financĂ© par le Fond National de la Recherche du Luxembourg, 2010-2014) dont lâobjectif est de proposer et dâĂ©valuer diffĂ©rents scĂ©narios de croissance rĂ©sidentielle sur le Grand-DuchĂ© du Luxembourg Ă lâhorizon 2030. Les simulations de dĂ©veloppement rĂ©sidentiel ont Ă©tĂ© rĂ©alisĂ©es avec lâapplication MUP-City (Tannier et al., 2012). Les scĂ©narios simulĂ©s ont dâabord Ă©tĂ© Ă©valuĂ©s au moyen de mesures dâaccessibilitĂ© spatiale (distance minimale pour atteindre lâamĂ©nitĂ© la plus proche, nombre dâamĂ©nitĂ©s Ă une distance donnĂ©e, indicateurs de diversitĂ© de lâoffre en amĂ©nitĂ©s) calculĂ©es avec MUP-City
- âŠ