the Group Steiner Problem asks for a minimumcost tree which contains at least one node from each group N i N i N i . In this paper, we give polynomial-time O O O(k k k )approximation algorithms for any fixed > > > 0. This result improves the previously known O O O(k k k)-approximation. We also apply
An approximation scheme for the rp-process
โ Scribed by J.-F. Rembges; Ch. Freiburghaus; F.-K. Thielemann; H. Schatz; M. Wiescher
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 175 KB
- Volume
- 621
- Category
- Article
- ISSN
- 0375-9474
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โฆ Synopsis
The Rapid Proton Capture Process (rp-process) describes the sequence of responsible nuclear reactions for the thermonuclear energy generation during explosive hydrogen burning on accreting compact objects in binary stellar systems.
In principle, all unstable proton-rich nuclei must be taken into account, but treating each nucleus separately makes numerical simulations which include hydrodynamics inefficient and expensive. Therefore, an accurate approximation scheme for the rp-process is highly desirable. In the present investigation we show how a general understanding of the nuclear reaction flows leads automatically to such a scheme and provides information about the reactions where experimental information from radioactive beam facilities is required.
๐ SIMILAR VOLUMES
We design a polynomial-time approximation scheme for the Steiner tree problem in the plane when the given set of regular points is c-local, i.e., in the minimum-cost spanning tree for the given set of regular points, the length of the longest edge is at most c times the length of the shortest edge.
Given a set of n positive integers and a knapsack of capacity c; the Subset-Sum Problem is to find a subset the sum of which is closest to c without exceeding the value c: In this paper we present a fully polynomial approximation scheme which solves the Subset-Sum Problem with accuracy e in time Oรฐm