Fault tolerant parallel pattern recognition

The general capabilities of fault tolerant computations in one-way and two-way linear cellular arrays are investigated in terms of pattern recognition. The defective processing elements (cells) that cause the misoperations are assumed to behave as follows. Dependent on the result of a self-diagnosis they store their working state locally such that it becomes visible to the neighbors. A non-working (defective) cell cannot modify information but is able to transmit it unchanged with unit speed. Arrays with static defects run the self-diagnosis once before the actual computation. Subsequently no more defects may occur.In case of dynamic defects cells may fail during the computation. We center our attention to patterns that are recognizable very fast, i.e. in real-time, but almost all results can be generalized to arbitrary recognition times in a straightforward manner. It is shown that fault tolerant recognition capabilities of two-way arrays with static defects are characterizable by intact one-way arrays and that one-way arrays are fault tolerant per se. For arrays with dynamic defects it is proved that the failures can be compensated as long as the number of adjacent defective cells is bounded. Arbitrary large defective regions (and thus fault tolerant computations) lead to a dramatically decrease of computing power. The recognizable patterns are those of a single processing element, the regular ones. CR Subject Classification (1998): F.1, F.4.3, B.6.1, E.1, B.8.1, C.

Massively parallel pattern recognition with link failures

The capabilities of reliable computations in linear cellular arrays with communication failures are investigated in terms of pattern recognition. The defective processing elements (cells) that cause the misoperations are assumed to behave as follows. Dependent on the result of a self-diagnosis of their communication links they store their working state locally such that it becomes visible to the neighbors. A defective cell is not able to receive information via one of its both links to adjacent cells. The self-diagnosis is run once before the actual computation. Subsequently no more failures may occur in order to obtain a valid computation. We center our attention to patterns that are recognizable very fast, i.e. in real-time. It is well-known that real-time one-way arrays are strictly less powerful than real-time two-way arrays, but there is only little known on the range between these two devices. Here it is shown that the sets of patterns reliably recognizable by real-time arrays with link failures are strictly in between the sets of (intact) one-way and (intact) two-way arrays. Hence, the failures cannot be compensated in general but, on the other hand, do not decrease the computing power to that one of one-way arrays. CR Subject Classification (1998): F.1, F.4.3, B.6.1, E.1, B.8.1, C.

Optimization technique for problems with an inequality constraint

General technique uses a modified version of an existing technique termed the pattern search technique. New procedure called the parallel move strategy permits pattern search technique to be used with problems involving a constraint

The contribution of 211 particles to the mechanical reinforcement mechanism of 123 superconducting single domains

Hardness and fracture toughness of Dy-123 single-domains were studied by Vickers micro-indentation. A significant anisotropy of the mechanical properties was observed. Hardness tests give higher values when performed in (001) planes rather than in planes parallel to the c-axis. Moreover cracks pattern around the indentation follows preferential orientation in planes parallel to the c-axis whereas a classical ''four-cracks'' pattern is observed in the (001) planes. It has been possible to show the crucial role played by the 211-particles in the deviating mechanism of cracks and the relevance of the 211-particle distribution high homogeneity in the material.Comment: 14 pages, including 5 figures and 1 Table. submitted to Supercond. Sci. Techno