177 research outputs found
Sequencing and scheduling for non serial permutation flowshops
No full textMost flowshop problems that have been researched have dealt with serial precedence requirements such that the flowshop has become synonymous with the serial assembly line. However, non-serial precedence requirements can also occur for which the resulting problem is still a type of flowshop. This research addresses in particular, non-serial versions of the three standard flowshop problems, namely the intermediate storage, no-intermediate storage and no-wait flowshop scenarios. The outcomes of this research include a number of new and alternative mathematical formulations for finding the optimal sequence of the products to be processed through the non-serial line. Secondly recurrence equations for scheduling purposes have also been developed
A General Framework for Constructive Meta-heuristics
No full textMeta-heuristic search algorithms, by their very nature, are applicable across a range of optimisation problems. In practice however, meta-heuristics have been tailored to solve particular problems. Recent work by Randall and Abramson (2001b)has successfully shown that iterative meta-heuristics, such as simulated annealing and tabu search, can be successfully generalised to solve a range of problems without modification though the use of a uniform representation language. Constructive meta-heuristics, such as ant colony optimisation and generalised random adaptive search procedures, pose more substantial problems to achieve this same level of generalistaion. This paper investigates the issues involved and suggests some measures by which generalisation could be achieved
Modularity in noncopying term rewriting
No full textAbstractIt is known that termination and completeness are not modular properties of term rewriting systems: the disjoint union of terminating (complete) term rewriting systems need not be terminating (complete). In this paper, we introduce a class of “noncopying” term rewriting systems as a new, term-based formalism for a kind of graph rewriting systems, and prove that this class enjoys the modularity of termination and of completeness. Actually, our results are stronger in the sense that the disjointness condition is relaxed for allowing the systems to share constructors and some defined symbols while preserving the main results
Lagrangian dual coordinatewise maximization algorithm for network transportation problems with quadratic costs
No full textSpecificity of hybridization between DNA sequences based on free energy
No full textWe investigated the specificity of hybridization based on a minimum free energy (Delta G(min)) through gel electrophoresis analysis. The analysis, using 94 pairs of sequences with length 20, showed that sequences that hybridize each other can be separated using the constraint Delta G(min) < -14.0, but cannot be separated using the number of base pairs (BP) in the range from 9 to 18. This demonstrates that the Delta G(min) is superior to the BP in terms of the capability to separate specific from non-specific sequences. Furthermore, the comparison between sequence design based on Delta G(min) and that based on the BP, done through a computer simulation, showed that the former outperformed the latter in terms of the number of sequences designed successfully as well as the ratio of successfully designed sequences to the total number of sequences checked
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