Volume 26, Issue 2 (2015), pp. 241–258
We propose a normalized parameter for characterization of similarity/dissimilarity of two sequences providing a smoothly varying measure for varying symmetry score. Such a parameter can be used for analysis of experimental data and fitting to a theoretical model, mirror symmetry estimation with respect to a selected or presumed symmetry axis, in particular, in symmetry detection applications where the selected symmetry parameters must be evaluated multiple times. We compare the proposed parameter, as well as several of the well-known distance and similarity measures, on an ensemble of template functions morphing continuously from symmetric to antisymmetric shape. This comparison allows to evaluate different similarity and symmetry measures in a more controlled and systematic setting than a simple visual estimation in sample images.
Pub. online:1 Jan 2006Type:Research ArticleOpen Access
Volume 17, Issue 2 (2006), pp. 207–224
The paper describes the development and performance of parallel algorithms for the discrete element method (DEM) software. Spatial domain decomposition strategy and message passing inter-processor communication have been implemented in the DEMMAT code for simulation of visco-elastic frictional granular media. The novel algorithm combining link-cells for contact detection, the static domain decomposition for parallelization and MPI data transfer for processors exchanging particles has been developed for distributed memory PC clusters. The parallel software DEMMAT_PAR has been applied to model compacting of spherical particles in the rectangular box. Two benchmark problems with different numbers of particles have been solved in order to measure parallel efficiency of the code. The inter-processor communication has been examined in order to improve domain decomposition topology and to achieve better load balancing. The speed-up equal to 11 has been obtained on 16 processors. The parallel performance study has been performed on the PC cluster VILKAS of Vilnius Gediminas Technical University, Lithuania.