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A standard quadratic problem consists of nding global maximizers of a quadratic form over the standard simplex. In this paper, the usual semideenite programming relaxation is strengthened by replacing the cone of positive semideenite matrices by the cone of completely positive matrices (the positive semideenite matrices which allow a factorization F F T(More)
We consider general, typically nonconvex, Quadratic Programming Problems. The Semi-deenite relaxation proposed by Shor provides bounds on the optimal solution, but it does not always provide suuciently strong bounds if linear constraints are also involved. To get rid of the linear side-constraints, another, stronger convex relaxation is derived. This(More)
We use mixed-integer nonlinear programming (MINLP) as the optimization method for determining optimal loading schemes in nuclear reactor fuel management. Contrary to most current methods, which treat the physical core description as a black box, the MINLP approach uses the algebraic equations describing the physical core behavior directly in the(More)
We use a simpliied but still quite realistic model to the nuclear reactor fuel management problem to search for optimal fuel loading schemes. Several adaptations and model adjustments are described that make the model tractable for a general nonlinear mixed-integer solver. Results are compared with results from pairwise interchange optimization. Use of(More)
We brieey describe the most important elements from physics in nuclear reactor fuel management. A simpliied but still rather realistic model is used to generate fuel loading schemes. We describe several tricks and model adjustments that make the model tractable for a general nonlinear mixed-integer solver. Results are compared with results from simulated(More)
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