Opis: This paper presents an efficient method for approximating curves and surfaces. An idea is introduced using a circle, where an arc-intersecting polyline is used instead of the traditional inner-arc polyline. The approach is then generalized to arbitrary 2D curves. The method is extended into 3D, where the approximation of spherical surface is developed based on surface-intersecting facets. Finally, a method is described for approximating the general curved surface. Theoretical analysis and the experimental results showed that the new algorithm requires considerably less geometric data at the same approximation error than the traditional one. Ključne besede:curve, surface, approximation, engineering software Objavljeno: 01.06.2012; Ogledov: 733; Prenosov: 29 Povezava na celotno besedilo

Opis: This paper presents a new chain code based on the eight-direction Freeman code. Each element in the chain is coded as a relative angle difference between it and the previous element. Statistical analysis showed that the probabilities of the Freeman codes differ importantly. Therefore, the Huffman coding was applied. The proposed chain code requires 1.97 bits/code, its chainlength is small, it allows representation of non-closed patterns and is rotationally independent. Ključne besede:computer science, pattern recognition, chain code, Huffman code, object representations, chain code compression Objavljeno: 01.06.2012; Ogledov: 852; Prenosov: 37 Povezava na celotno besedilo

Opis: This paper gives an application of Mawhin’s coincidence degree and matrix spectral theory to a predator-prey model with M-predators and N-preys. The method is different from that used in the previous work. Some new sufficient conditions are obtained for the existence and global asymptotic stability of the periodic solution. The existence and stability conditions are given in terms of spectral radius of explicit matrices which are much different from the conditions given by the algebraic inequalities. Finally, an example is given to show the feasibility of our results. Ključne besede:coincidence degree, Jean Mawhin, predator-prey model, spectral theory Objavljeno: 12.06.2017; Ogledov: 352; Prenosov: 47 Celotno besedilo (2,05 MB)