Search results for "mathematics"
showing 10 items of 22031 documents
Three solutions for a two-point boundary value problem with the prescribed mean curvature equation
2015
The existence of at least three classical solutions for a parametric ordinary Dirichlet problem involving the mean curvature operator are established. In particular, a variational approach is proposed and the main results are obtained simply requiring the sublinearity at zero of the considered nonlinearity.
Critical points in open sublevels and multiple solutions for parameter-depending quasilinear elliptic equations
2014
We investigate the existence of multiple nontrivial solutions of a quasilinear elliptic Dirichlet problem depending on a parameter $\lambda>0$ of the form $$ -\Delta_pu=\lambda f(u)\quad\mbox{in }\ \Omega,\quad u=0\quad\mbox{on }\ \partial\Omega, $$ where $\Omega\subset \mathbb{R}^N$ is a bounded domain, $\Delta_p$, $1 < p < +\infty$, is the $p$-Laplacian, and $f: \mathbb{R}\to \mathbb{R}$ is a continuous function satisfying a subcritical growth condition. More precisely, we establish a variational approach that when combined with differential inequality techniques, allows us to explicitly describe intervals for the parameter $\lambda$ for which the problem under consideration admits nontri…
A mechanism for ejecting a horseshoe from a partially hyperbolic chain recurrence class
2022
We give a $C^1$-perturbation technique for ejecting an a priori given finite set of periodic points preserving a given finite set of homo/hetero-clinic intersections from a chain recurrence class of a periodic point. The technique is first stated under a simpler setting called Markov iterated function system, a two dimensional iterated function system in which the compositions are chosen in Markovian way. Then we apply the result to the setting of three dimensional partially hyperbolic diffeomorphisms.
Toward a real-time tracking of dense point-sampled geometry
2012
4 pages; International audience; In this paper, we address the problem of tracking temporal deformations between two arbitrary densely sampled point-based surfaces. We propose an intuitive and efficient resolution to the point matching problem within two frames of a sequence. The proposed method utilizes two distinct space partition trees, one for each point cloud, which both are defined on a unique discrete space. Our method takes advantage of multi-resolution concerns, voxel adjacency relations, and a specific distance function. Experimental results obtained from both simulated and real reconstructed data sets demonstrate that the proposed method can handle efficiently the tracking proces…
SAMSLAM: Simulated Annealing Monocular SLAM
2013
This paper proposes a novel monocular SLAM approach. For a triplet of successive keyframes, the approach inteleaves the registration of the three 3D maps associated to each image pair in the triplet and the refinement of the corresponding poses, by progressively limiting the allowable reprojection error according to a simulated annealing scheme. This approach computes only local overlapping maps of almost constant size, thus avoiding problems of 3D map growth. It does not require global optimization, loop closure and back-correction of the poses.
3D Image Based Modelling Using Google Earth Imagery for 3D Landscape Modelling
2019
In recent years SfM technique experiments have been innumerable and increasingly refined under metric profiles. The techniques rely on photographic datasets of the objects or landscapes which can require in most cases time consuming and expensive surveys. Recently however there have been increases in the available 3D data of sites worldwide on the Google Earth (GE) platform. This paper presents a unique experimentation that considers integrating readily available datasets from GE and images taken during surveys on ground level for 3D replication without the use of expensive aerial surveys. This will enable practitioners the ability to more easily create 3D models of cultural heritage signif…
Localization of 2D Cameras in a Known Environment Using Direct 2D-3D Registration
2014
International audience; In this paper we propose a robust and direct 2D-to- 3D registration method for localizing 2D cameras in a known 3D environment. Although the 3D environment is known, localizing the cameras remains a challenging problem that is particularly undermined by the unknown 2D-3D correspondences, outliers, scale ambiguities and occlusions. Once the cameras are localized, the Structure-from-Motion reconstruction obtained from image correspondences is refined by means of a constrained nonlinear optimization that benefits from the knowledge of the scene. We also propose a common optimization framework for both localization and refinement steps in which projection errors in one v…
Teacher Training for Children with Autism Spectrum Disorders in Finland
2019
This chapter first provides a short description of the historical background and development of special education teacher training in Finland. The relationship between special education and teaching pupils with autism spectrum disorder (ASD) is covered by chronologically presenting the main events, turning points, publications, and people that have had a significant effect on the education of pupils with ASD in Finland. This is followed by a description of the organization of teacher training, in general, and the particular characteristics of teaching pupils with ASD. In the context of ASD, it is essential to examine questions concerning the link between learning as social practice and the …
Frequency of co‐teaching in different teacher categories
2010
Co‐teaching – or the use of more than one teacher in a classroom – has been commonly recommended as a means to promote inclusive education. The aim of the present study was to survey the actual frequency of co‐teaching among different teacher categories in the comprehensive school level in one Finnish city. The data were collected through a questionnaire answered by two representative samples of teachers including 117 resource room teachers in the first survey, and 317 teachers of various teacher categories in the second. The results showed that co‐teaching was a widespread phenomenon among resource room teachers and special class teachers but less frequent among other teacher groups. Overa…
Early numeracy in low‐performing young children
2009
The aim of this study was to explore the early numeracy of low‐performing young children. The mean age of the children was six years and four months. The 511 participants belonged to three groups: multi‐language children, children with special educational needs and children with average performance. The results showed that there were significant group differences in early numeracy: the children in the reference group had better relational and counting skills than those with a multi‐language background and those with special educational needs. Some differences were found in counting skills between the children with multi‐language background and those with special educational needs. Finally, …