Calcium carbonate (CaCO
3
) fillers pre-treated with the increased amount of stearate were used in order to tune the surface energy for a selective filler migration to the interface in immiscible ...styrene-acrylonitrile/ethylene-propylene-diene (SAN/EPDM) polymer blends. Various models were used in order to predict the filler accommodation at the blend interface when the interfacial tension becomes low and the wettability is good. The results showed that under optimal thermodynamic conditions, the filler might act as a compatibilizer and significantly improve the blend morphology. The coarse morphology of the initially immiscible SAN/EPDM changed into a fine blend morphology with the addition of the selected CaCO
3
fillers with optimal surface energy. Due to the problem with filler agglomeration of initially nanosized CaCO
3
fillers, we used masterbatch (MB) compositions for the blend preparation in order to get the better filler distribution. In this paper, the comparison between two types of MB compositions based on SAN and/or EPDM as a surplus phase with the selected filler was made considering the model predictions and its effects on the blend morphology and properties. In the case of using MB(EPDM) in blend preparation, the fine blend morphology resulted in improved mechanical and thermal properties, while with MB(SAN) the coarse blend morphology and worsened properties illustrated the opposite effect.
We present the extension of our previous work on complexity indices for the traveling salesman problem (TSP). Since we study the symmetric traveling salesman problem, the instances are represented by ...complete graphs
G
with distances between cities as the edge weights. A complexity index is an invariant of an instance
I
by which the execution time of an exact TSP algorithm for
I
can be predicted. We consider some subgraphs of
G
consisting of short edges and define several new invariants related to their connected components. For computational experiments we have used the well-known TSP Solver Concorde. Experiments with instances on 50 vertices with the uniform distribution of integer edge weights in the interval 1, 100 show that there exists a notable correlation between the sequences of selected invariants and the sequence of execution times of the TSP Solver Concorde. We provide logical explanations of these phenomena.
In this paper the recently introduced concept of equidistant dimension \(eqdim(G)\) of graph \(G\) is considered. Useful property of distance-equalizer set of arbitrary graph \(G\) has been ...established. For Johnson graphs \(J_{n,2}\) and Kneser graphs \(K_{n,2}\) exact values for \(eqdim(J_{n,2})\) and \(eqdim(K_{n,2})\) have been derived, while for Johnson graphs \(J_{n,3}\) it is proved that \(eqdim(J_{n,3}) \le n-2\). Finally, exact value of \(eqdim(J_{2k,k})\) for odd \(k\) has been presented.
We suggest a new heuristic for solving unconstrained continuous optimization problems. It is based on a generalized version of the variable neighborhood search metaheuristic. Different neighborhoods ...and distributions, induced from different metrics are ranked and used to get random points in the shaking step. We also propose VNS for solving constrained optimization problems. The constraints are handled using exterior point penalty functions within an algorithm that combines sequential and exact penalty transformations. The extensive computer analysis that includes the comparison with genetic algorithm and some other approaches on standard test functions are given. With our approach we obtain encouraging results.
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