9,313 research outputs found
Computational Performance Evaluation of Two Integer Linear Programming Models for the Minimum Common String Partition Problem
In the minimum common string partition (MCSP) problem two related input
strings are given. "Related" refers to the property that both strings consist
of the same set of letters appearing the same number of times in each of the
two strings. The MCSP seeks a minimum cardinality partitioning of one string
into non-overlapping substrings that is also a valid partitioning for the
second string. This problem has applications in bioinformatics e.g. in
analyzing related DNA or protein sequences. For strings with lengths less than
about 1000 letters, a previously published integer linear programming (ILP)
formulation yields, when solved with a state-of-the-art solver such as CPLEX,
satisfactory results. In this work, we propose a new, alternative ILP model
that is compared to the former one. While a polyhedral study shows the linear
programming relaxations of the two models to be equally strong, a comprehensive
experimental comparison using real-world as well as artificially created
benchmark instances indicates substantial computational advantages of the new
formulation.Comment: arXiv admin note: text overlap with arXiv:1405.5646 This paper
version replaces the one submitted on January 10, 2015, due to detected error
in the calculation of the variables involved in the ILP model
Giant Resonances based on Unitarily Transformed Two-Nucleon plus Phenomenological Three-Nucleon Interactions
We investigate giant resonances of spherical nuclei on the basis of the
Argonne V18 potential after unitary transformation within the Similarity
Renormalization Group or the Unitary Correlation Operator Method supplemented
by a phenomenological three-body contact interaction. Such Hamiltonians can
provide a good description of ground-state energies and radii within
Hartree-Fock plus low-order many-body perturbation theory. The standard Random
Phase Approximation is applied here to calculate the isoscalar monopole,
isovector dipole, and isoscalar quadrupole excitation modes of the 40Ca, 90Zr,
and 208Pb nuclei. Thanks to the inclusion of the three-nucleon interaction and
despite the minimal optimization effort, a reasonable agreement with
experimental centroid energies of all three modes has been achieved. The role
and scope of the Hartree-Fock reference state in RPA methods are discussed.Comment: v2: 11 pages, incl. 3 figures; extended discussion and outlook; to
appear in J.Phys.
Dynamical entanglement purification using chains of atoms and optical cavities
In the framework of cavity QED, we propose a practical scheme to purify
dynamically a bipartite entangled state using short chains of atoms coupled to
high-finesse optical cavities. In contrast to conventional entanglement
purification protocols, we avoid CNOT gates, thus reducing complicated pulse
sequences and superfluous qubit operations. Our interaction scheme works in a
deterministic way, and together with entanglement distribution and swapping,
opens a route towards efficient quantum repeaters for long-distance quantum
communication.Comment: 13 pages, 6 figures, revised version with incorporated erratu
Process model based development of disassembly tools
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Disassembly processes require flexible tools for loosening and handling operations. Today, disassembly processes demand a great deal of manual labour and a vast variety of tools. Partly destructive tools which generate and use new acting surfaces are able to increase the economic viability owing to their flexibility and their promotion of the reuse of components. This article describes selected methods of acting surface generation and their application for prototypical tools.DFG, SFB 281, Demontagefabriken zur Rückgewinnung von Ressourcen in Produkt- und Materialkreisläufe
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