Search results for "modeling"
showing 10 items of 4489 documents
TIME : A Translator Compiler for CIS
2002
To build a Cooperative Information System, a first step is to collect schemas of each local database. All the schemas exported from databases are translated and integrated into a cooperative schema, which is used by the final user to query the cooperation “transparently”. In this article, we focus on the definition of tools that are used to build and manage cooperative information systems. These tools enable the automatic or semi-automatic generation of specific translators. The first step of our methodology is a knowledge acquisition step that allows for the data model description of each local database. The second step is to compare all these descriptions in order to organize the correspo…
Contrasting age-specific recruitment and survival at different spatial scales: A case study with the European storm petrel
2009
Evolutionary studies on optimal decisions or conservation guidelines are often derived by generalising patterns from a single population, while inter-population variability in life-history traits is seldom considered. We investigated here how survival and recruitment probabilities changed with age at different geographical scales using the encounter histories of 5523 European storm petrels from three Mediterranean colonies, and also how our estimates of these parameters might be expected to affect population growth rates using population matrix models. We recorded similar patterns among colonies, but also important biological differences. Local survival, recruitment and breeding success inc…
A measurement-based channel model for vehicular communications in tunnels
2014
Wireless Communications and Networking Conference (WCNC), 2014 IEEE, Istanbul, TURQUIE, 06-/04/2014 - 09/04/2014; In this paper, we present a new version of the iterative nonlinear least square approximation (INLSA) algorithm for the design of measurement-based channel simulators. The proposed method aims to match the time-variant impulse response (TVIR) of the simulation model to that of the measured channel. The propagation delays are discerned directly from the measurements, whereas the gains, the Doppler frequencies, and the phases are computed iteratively by minimizing a matching error norm. We evaluate the performance of the proposed method in terms of the approximation of the transfe…
AMUN: An Object Oriented Model For Cooperative Spatial Information Systems
1997
International audience; The diversity of spatial information systems promote the need to integrate heterogeneous spatial or geographic information systems (GIS) in a cooperative environment. We present an on going research project, called ISIS (Interoperable Spatial Information System), which aims to build an environment to support interoperability of GIS by interconnecting spatial data repositories and spatial processing resources. Our solution combines techniques from traditional interoperable information systems, spatial data modeling and distributed object oriented databases. While object oriented data modeling impact has been studied in spatial databases, research in model for distribu…
A spiking network for spatial memory formation: Towards a fly-inspired ellipsoid body model
2013
Neural centers devoted to spatial memory and path integration were largely studied in rats and in different insect species like ants and bees. In this paper a neural-based model for the formation of a spatial working memory is proposed mirroring some peculiarities of the Drosophila central brain and in particular the ellipsoid body. Simulation results are reported opening the way to applications on roving platforms.
Ultimate strain and deformability of elementary flax fibres
2011
Flax fibres possess high specific strength and stiffness, and thus are competitive in terms of mechanical properties with the traditional reinforcing fibres used in polymer-matrix composite materials. The mechanical properties of fibres have considerable variability that needs to be characterized and allowed for in the analysis of mechanical response of composites. In this study, the distribution of ultimate strain of elementary flax fibres and its dependence on gauge length is considered. The applicability of the modified Weibull distribution, used for fibre strength, to fibre ultimate strain is evaluated. A simplified relation of ultimate strain and fibre strength distributions is propos…
Analytical evaluation of structural response for stationary multicorrelated input
1990
Abstract An analytical procedure is presented which can drastically reduce computational effort in the evaluation of the spectral moments of an elastic linear multi-degree-of-freedom system subjected to a stationary multicorrelated input process. The reduction in computer time is possible since the cross-spectral moments of two oscillators can be obtained in recursive manner as a linear combination of the spectral moment of each oscillator taken separately, which is evaluated by means of a very fast numerical technique.
Analysis of pattern recognition by man using detection experiments.
1981
This paper addresses the problem of analyzing biological pattern recognition systems. As no complete analysis is possible due to limited observability, the theoretical part of the paper examines some principles of construction for recognition systems. The relations between measurable and characteristic variables of these systems are described. The results of the study are: 1. Human recognition systems can always be described by a model consisting of an analyzer (FA) and a linear classifier. 2. The linearity of the classifier places no limits on the universal validity of the model. The principle of organization of such a system may be put into effect in many different ways. 3. The analyzer f…
CliffoSor: A Parallel Embedded Architecture for Geometric Algebra and Computer Graphics
2006
Geometric object representation and their transformations are the two key aspects in computer graphics applications. Traditionally, compute-intensive matrix calculations are involved to model and render 3D scenery. Geometric algebra (a.k.a. Clifford algebra) is gaining growing attention for its natural way to model geometric facts coupled with its being a powerful analytical tool for symbolic calculations. In this paper, the architecture of CliffoSor (Clifford Processor) is introduced. ClifforSor is an embedded parallel coprocessing core that offers direct hardware support to Clifford algebra operators. A prototype implementation on an FPGA board is detailed. Initial test results show more …
Performance potential for simulating spin models on GPU
2012
Graphics processing units (GPUs) are recently being used to an increasing degree for general computational purposes. This development is motivated by their theoretical peak performance, which significantly exceeds that of broadly available CPUs. For practical purposes, however, it is far from clear how much of this theoretical performance can be realized in actual scientific applications. As is discussed here for the case of studying classical spin models of statistical mechanics by Monte Carlo simulations, only an explicit tailoring of the involved algorithms to the specific architecture under consideration allows to harvest the computational power of GPU systems. A number of examples, ran…