Home About us Contact
|
Home About us Contact | ||
|
|
||
Whole Model (whole + model)
Selected AbstractsA framework for quad/triangle subdivision surface fitting: Application to mechanical objectsCOMPUTER GRAPHICS FORUM, Issue 1 2007Guillaume Lavoué Abstract In this paper we present a new framework for subdivision surface approximation of three-dimensional models represented by polygonal meshes. Our approach, particularly suited for mechanical or Computer Aided Design (CAD) parts, produces a mixed quadrangle-triangle control mesh, optimized in terms of face and vertex numbers while remaining independent of the connectivity of the input mesh. Our algorithm begins with a decomposition of the object into surface patches. The main idea is to approximate the region boundaries first and then the interior data. Thus, for each patch, a first step approximates the boundaries with subdivision curves (associated with control polygons) and creates an initial subdivision surface by linking the boundary control points with respect to the lines of curvature of the target surface. Then, a second step optimizes the initial subdivision surface by iteratively moving control points and enriching regions according to the error distribution. The final control mesh defining the whole model is then created assembling every local subdivision control meshes. This control polyhedron is much more compact than the original mesh and visually represents the same shape after several subdivision steps, hence it is particularly suitable for compression and visualization tasks. Experiments conducted on several mechanical models have proven the coherency and the efficiency of our algorithm, compared with existing methods. [source] Lithosphere structure of Europe and Northern Atlantic from regional three-dimensional gravity modellingGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2002T. P. Yegorova Summary Large-scale 3D gravity modelling using data averaged on a 1° grid has been performed for the whole European continent and part of the Northern Atlantic. The model consists of two regional layers of variable thickness,the sediments and the crystalline crust, bounded by reliable seismic horizons,the ,seismic' basement and the Moho surface. Inner heterogeneity of the model layers was taken into account in the form of lateral variation of average density depending on the type of geotectonic unit. Density parametrization of the layers was made using correlation functions between velocity and density. For sediments, sediment consolidation with depth was taken into account. Offshore a sea water layer was included in the model. As a result of the modelling, gravity effects of the whole model and its layers were calculated. Along with the gravity modelling an estimation of isostatic equilibrium state has been carried out for the whole model as well as for its separate units. Residual gravity anomalies, obtained by subtracting the gravity effect of the crust from the observed field, reach some hundred mGal (10,5 m s,2) in amplitude; they are mainly caused by density heterogeneities in the upper mantle. A mantle origin of the residual anomalies is substantiated by their correlation with the upper-mantle heterogeneities revealed by both seismological and geothermal studies. Regarding the character of the mantle gravity anomalies, type of isostatic compensation, crustal structure, age and supposed type of endogenic regime, a classification of main geotectonic units of the continent was made. As a result of the modelling a clear division of the continent into two large blocks,Precambrian East-European platform (EEP) and Variscan Western Europe,has been confirmed by their specific mantle gravity anomalies (0 ÷ 50 × 10,5 m s,2 and ,100 ÷,150 × 10,5 m s,2 correspondingly). This division coincides with the Tornquist,Teisseyre Zone (TTZ), marked by a gradient zone of mantle anomalies. In the central part of the EEP (over the Russian plate) an extensive positive mantle anomaly, probably indicating a core of ancient consolidation of the EEP, has been distinguished. To the west and to the east of this anomaly positive mantle anomalies occur, which coincide with a deep suture zone (TTZ) and an orogenic belt (the Urals). Positive mantle anomalies of the Alps, the Adriatic plate and the Calabrian Arc, correlating well with both high-velocity domains in the upper mantle and reduced temperatures at the subcrustal layer, are caused by thickened lithosphere below these structures. Negative mantle anomalies, revealed in the Western Mediterranean Basin and in the Pannonian Basin, are the result of thermal expansion of the asthenosphere shallowing to near-Moho depths below these basins. [source] Mapping sensitivity to land degradation in Extremadura.LAND DEGRADATION AND DEVELOPMENT, Issue 2 2009SW Spain Abstract An assessment of sensitivity to land degradation has been carried out in the Extremadura region, SW Spain, by means of a modelling approach developed by the European Commission funded MEDALUS project (Mediterranean Desertification and Land Use) which identifies such areas on the basis of an index (Environmentally Sensitive Area index, ESA index) that incorporates data on environmental quality (climate, vegetation, soil) as well as anthropogenic factors (management). Two maps of environmental sensitivity (ES) to degradation with different legend resolution (four and eight classes of sensitivity) have been made and tested by comparing classes of the legends with an extensive number (2690) of true field data gathered from plots distributed all over the study region. Independent variables of validation consisted of nine degradation-related types of data and the method tested the performance of the whole model and the statistical separability among classes of sensitivity, as well as the capability of the variables in delimiting the classes. Results showed a good performance of the whole model to both, the map of four and eighth classes of sensitivity. Separation among classes of sensitivity showed a slightly different behaviour of both maps, identifying transitional classes in the map of eight classes where classification could be improved in terms of the ranges of ESA index values assigned to the different classes. Copyright © 2008 John Wiley & Sons, Ltd. [source] The conceptual relationship between health indicators and quality of life: results from the cross-cultural analysis of the EUROHIS field studyCLINICAL PSYCHOLOGY AND PSYCHOTHERAPY (AN INTERNATIONAL JOURNAL OF THEORY & PRACTICE), Issue 1 2005Silke Schmidt The aim of this study was to determine the performance of various health indicators to predict quality of life, mental health and general health from a conceptual point of view. The EUROHIS study (see Nosikov and Gudex, 2003) includes a broad range of health care and health behaviour related indicators, such as preventive care, health care utilization, use of medicine, physical health, mental health, alcohol consumption, physical activity and quality of life. Data on various health indicators and quality of life were collected from 10 countries, amounting to a sample size of 4849 (2750 females and 2099 males). An analytical approach was employed to investigate the interrelationship between indicators of each particular indicator set (such as alcohol consumption) and between conceptually different indicator sets. Regression analyses as well as structural equation modelling were employed, pooled across all countries as well as separately for different groups of countries. Findings indicate a higher extent of cross-cultural variation in health behaviour and the QOL measures than in mental health and physical health. In regression analyses, results showed strong and consistent effects of various health behaviour indicators to predict quality of life (R2 = 0.48), mental health (R2 = 0.48) or general health (R2 = 0.45). However, a differential effect of socio-demographic variables, in particular education, and health behavioural determinants was found in different groups of countries. In the structural equation modelling, good fit indices were observed for the model determining physical and mental health factors by different health behaviour factors. Findings suggest that quality of life rather mediates mental outcomes in this particular set of health indicators in a European sample than functions as an outcome variable. However, it was not possible to include sociodemographic data in the whole model but only in each of the latent factors. This finding still requires replication, both in different clinical groups and in longitudinal data.,Copyright © 2005 John Wiley & Sons, Ltd. [source] | ||||||||||