9 research outputs found
Moč soustvarjanja osebne znamke predsedniškega kandidata
This paper describes an improved algorithm for segmentation of green vegetation under uncontrolled illumination conditions and also suitable for resource-constrained real-time applications. The proposed algorithm uses a naïve Bayesian model to effectively combine various manually extracted features from two different color spaces namely RGB and HSV. The evaluation of 100 images indicated the better performance of the proposed algorithm than the vegetation index-based methods with comparable execution time. Moreover, the proposed algorithm performed better than the state-of-the-art EASA-based algorithms in terms of processing time and memory usage.AgricultureIsLif
Energy consistency in homogenisation-based upscaling scheme for localisation in masonry shells
This paper presents an enhanced multi-scale framework for the failure of quasi-brittle thin shells as an improvement of the one proposed in Mercatoris and Massart (Int J Numer Methods Eng 85:1177-1206, 2011). The computational homogenisation-based multi-scale methodology is an attractive solution for heterogeneous materials when their characterisation becomes difficult because of complex evolving behaviour such as damage-induced anisotropy and localisation of degradation. An enhanced upscaling scheme for damage localisation in shell structures is proposed using a periodic computational homogenisation procedure and an energy equivalence between mesostructural material instabilities and aggregate macroscopic cracks. The structural cracking is treated by using embedded strong discontinuities incorporated in the shell formulation, the behaviour of which is deduced by an energetically consistent upscaling scheme. The effects of this energy equivalence are discussed based on results of multi-scale simulations of out-of-plane loaded masonry walls including flexural stair-case failure and compared to the results of direct numerical simulations. A good agreement is observed in terms of the load-bearing capacity and of associated energy dissipation. Based on the homogenisation procedure, the orientation of the structural-scale cracking is detected by means of an acoustic tensor-based failure detection adapted to shell kinematics. A multi-scale bifurcation analysis on a simple loading case is performed in order to discuss the selection of the cracking orientation based on energetic considerations. © 2012 Springer Science+Business Media B.V
Level set-based generation of representative volume elements for the damage analysis of irregular masonry
Multiscale modelling framework for the fracture of thin brittle polycrystalline films: application to polysilicon
A multi-scale approach to bridge microscale damage and macroscale failure: a nested computational homogenization-localization framework
This paper presents a multi-scale modelling approach for bridging the microscale damage and macroscale failure. The proposed scheme evolves from a classical computational homogenization scheme (FE2) towards a discontinuity enriched framework. The classical homogenization approaches typically rely on the separation of scales principle, which is violated as soon as a strain localization band develops within a microstructural volume element (MVE). The newly developed scheme resolves this limitation by considering the bifurcation of the microscale deformation into a continuum ‘bulk’ part and a localization related part. The most distinct feature of the proposed framework is that both, the local macroscale traction-opening response of the cohesive crack and the stress-strain response of the surrounding ‘bulk’, are obtained from a single MVE analysis. The discontinuity enriched macroscale description is formulated to accommodate for the micro-macro coupling. The macroscale boundary value problem and the corresponding implementation are detailed for the use within the embedded discontinuities approach. The presented multi-scale method is demonstrated on a numerical example of a cohesive crack propagation in a macroscopic double notch specimen, with underlying voided microstructure
