This study addresses the recently introduced Traveling Thief Problem (TTP) which combines the classical Traveling Salesman Problem (TSP) with the 0-1 Knapsack Problem (KP). The problem consists of a set of cities, each containing a set of available items with weights and profits. It involves searching for a permutation of the cities to visit and a decision on items to pick. A selected item contributes its profit to the overall profit at the price of higher transportation cost incurred by its weight. The objective is to maximize the resulting profit.We propose a number of problem-specific packing strategies run on top of TSP solutions derived by the Chained Lin-Kernighan heuristic. The investigations provided on the set of benchmark instances prove their rapidity and efficiency when compared with an approximate mixed integer programming based approach and state-of-the-art heuristic solutions from the literature.

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This paper is an empirical study of the application of visual detection and tracking methods to the problem of locating and tracking all AFL players during a game. While most person detection and tracking algorithms are designed for pedestrians, we show that with appropriate modifications, state of the art methods can be adapted to a more challenging domain where motion is significantly more varied and occurs in a much wider area.

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A comprehensive computational strategy for the prediction of crystal structures is presented that has scored an unprecedented 4 in 4 success rate at the 2007 CCDC blind test on crystal structure prediction [1]. Key components of the new approach, implemented in the GRACE software package, are a hybrid method for the accurate calculation of lattice energies, a robust procedure for the parameterization of tailor-made force fields and a novel approach for crystal structure generation. The hybrid method combines DFT calculations by means of the VASP program with an empirical van der Waals correction. It is used for the final lattice energy ranking and acts as a reference standard for force field parameterization. A tailormade force field is derived for each molecule to be considered and used for crystal structure generation as well as for the preparation of second derivative matrices for the final lattice energy optimization with the hybrid method. Based on the known statistical deviation between the tailor-made force field and the hybrid method, a shortlist of crystal structures from a small energy window is selected for the final lattice energy optimization and ranking. In addition to the blind test results, validation studies for 15 organic molecules are presented, including ethane, ethylene, acetylene, methanol, urea, acetic acid, cyclohexane-1,4-dione, paracetamol, CCDC blind test molecules I to VI and a pharmaceutical compound for which crystal structures have been predicted in a blind test fashion. 17 out of the 18 experimentally observed crystal forms of these molecules are found among the first two most stable predicted crystal structures. Predicting the crystal structures of small molecules from energy calculations is of considerable interest for a number of scientific and industrial purposes. However, in the field of polymorphforming pharmaceuticals two main problems arise. One is the high degree of internal flexibility of many of the molecules of interest and the consequential large number of possible conformations. The resulting multitude of packing possibilities can overwhelm even fast computers. The other problem is that many of these structures have similar energies. Exact energy modeling is thus necessary to identify the real structures. We checked possible strategies using aripripazole as a test case. For this compound, a number of polymorphs and various solvates are known, as are their respective crystal structures. By comparing the experimental structures with the calculations on all stages, a number of helpful results were established: 1) Quantum-mechanical (QM) energy calculations on the isolated molecule reduce the number of possible conformations drastically. For aripripazole, seven torsional degrees of freedom allow 2916 minimum conformations. Of these, only 296 remain, once correlation of neighboring torsions is considered. Further reduction is possible, if the influence of hydrogen bonds is considered. 2) The molecule has five potential hydrogen bond acceptor sites, but QM calculations rev...