Efficient algorithms for selection of recovery points in tree taskmodels

Efficient solutions to the problem of optimally selecting recovery points are developed. The solutions are intended for models of computation in which task precedence has a tree structure and a task may fail due to the presence of faults. An algorithm to minimize the expected computation time of the task system under a uniprocessor environment has been developed for the binary tree model. The algorithm has time complexity of O(N₂), where N is the number of tasks, while previously reported procedures have exponential time requirements. The results are generalized for an arbitrary tree model     

Ternary iron alloys for permanent magnetic materials

Iron-based rare-earth ternary alloys with a high energy product came into prominence recently as permanent magnetic materials. Also, a large number of iron-based ternary phase diagrams were critically evaluated and published recently as monographs under the auspices of the International Programme for Alloy Phase Diagram Data. This review presents a brief comparison of the data on crystal structures of ternary compounds and the corresponding phase diagrams for a number of ternary iron rare-earth (RE) X series: B-Fe-RE, C-Fe-RE, Fe-N-RE, Al-Fe-RE, Co-Fe-RE, Fe-Ni-RE, and Fe-RE(1)-RE(2). It is hoped that this exercise will aid in pinpointing discrepancies and planning future investigations on ternary compounds and phase equilibria in unexplored systems.