ALEGRA is a multi-material, arbitrary-Lagrangian-Eulerian (ALE) code for solid dynamics being developed by the Computational Physics Research and Development Department at Sandia +tionat Laboratories. It combines the features of modem Eulerian shock codes, such as CTH, with modem Lagrangian structural analysis codes. With the ALE algorithm, the mesh can be stationary (Eulerian) with the materia...

This paper addresses the problem of generating unstructured meshes with fixed connectivity for large rigid body motion. The proposed approach consists in generating a mesh in computational space for a generic configuration of the moving body. The management of body and mesh motion is then carried out in computational space using a sliding mesh paradigm. Afterwards, the mesh in physical space is...

A new content-based mesh design algorithm for video objects segmentation and tracking is proposed. The algorithm moves the mesh nodes along motion or luminance discontinuities in order to ÿt the objects boundaries. The motion inside adjacent triangular cells is estimated by competitive forward–backward matching. This approach allows the displacements of the nodes without the remeshing of occlus...

This report introduces the emerging Wavelet-based video coding system. Inefficiency of the block-based motion estimation in context of the wavelet coder is discussed in comparison to the mesh-based approach. A progressive mesh refinement technique using multiple layers is proposed also a fast motion estimation based on the redundant wavelet is presented that outperforms a full-search motion est...

We present a method to derive a time-evolving triangle mesh representation from a sequence of binary volumetric data representing an arbitrary motion. Multi-view reconstruction studios use a multiple camera set to turn an actor’s performance into a time series of visual hulls. However, the reconstructed sequence lacks temporal coherence as each frame is generated independently, preventing easy ...

This paper presents a procedure for computing fluid-structure interaction problems when the boundaries of the domain undergo large displacements. The algorithm is based on both mesh motion and mesh adaptation techniques. More specifically, we use a node repositioning algorithm based on an elastic analogy together with a mesh adaptation procedure based on local mesh modifications [1]. This paper...

This paper presents a complete video codec which supports both block-based and mesh-based motion compensation modes. While the mesh-based modes are suitable for spatially continuous representation of in-plane rotations, zooms, and other motions that can be represented by parametric mappings; the block-based modes (especially overlapped block matching) perform better around motion boundaries. Th...

considering the nonlinear hyperelastic or viscoelastic nature of soft tissues has an important effect on modeling results. in medicalapplications, accounting nonlinearity begets an ill posed problem, due to absence of external force. myocardium can be consideredas a hyperelastic material, and variational approaches are proposed to estimate stiffness matrix, which take into account the linearand...

This paper describes a methodology for the simulation of musculoskeletal disorders. Our clinical study is related to osteoarthritis of the hip, a pathogenesis possibly due to impingements. These bone collisions lead to abnormal joint mechanics which is characterized by contact pressure and stress distribution upon the joint cartilages. The proposed methodology combines different approaches from...