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Digitale Medien

Comparing networks with differing neural-node functions using transputer-based genetic algorithms (1993)

Jones, Antonia J. ; Macfarlane, D.

Springer

Neural computing & applications 1 (1993), S. 256-267

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ISSN: 1433-3058

Schlagwort(e): Backpropagation ; Genetic algorithms ; Ellipsoidal nodes ; Quadratic nodes ; Speech recognition ; E-task

Quelle: Springer Online Journal Archives 1860-2000

Thema: Informatik , Mathematik

Notizen: Abstract Different neural net node computational functions are compared using feedforward backpropagation networks. Three node types are examined: the standard model, ellipsoidal nodes and quadratic nodes. After preliminary experiments on simple small problems, in which quadratic nodes performed very well, networks of differing nodes types are applied to the speech recognition 104 speaker E-task using a fixed architecture. Ellipsoidal nodes were found to work well, but not as well as the standard model. Quadratic nodes did not perform well on the larger task. To facilitate an architecture independent comparison a transputer-based genetic algorithm is then used to compare ellipsoidal and mixed ellipsoidal and standard networks with the standard model. These experiments confirmed the earlier conclusion that ellipsoidal networks could not compare favourably with the standard model on the 104 speaker E-task. In an evolutionary search in which layer node types were free to adjust ellipsoidal nodes had a tendency to become extinct or barely survive. If the presence of ellipsoidal nodes was enforced then the resulting networks again performed poorly when compared with the standard model.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02098744

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Digitale Medien

23Na NMR in urethane cross-linked polyether solid polymer electrolytes (1994)

Forsyth, M. ; Smith, M. E. ; Meakin, P. ; [weitere]

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 2077-2084

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ISSN: 0887-6266

Schlagwort(e): NMR ; polyether urethane polymer electrolytes ; sodium triflate ; Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Notizen: Sodium triflate/polyether urethane polymer electrolytes ranging in concentration from 0.05 molal to 1.75 molal have been investigated via 23Na static solid-state NMR. Room temperature spectra and spin lattice relaxation times were consistent with a single narrow resonance indicating the presence of only mobile ionic species. The concentration and temperature dependence of relaxation times, chemical shifts, and linewidth have been investigated. The results suggest either a single species or rapid exchange between a number of species (even at temperatures below the glass transition temperature, Tg). The linewidth decreases with increasing concentration of ions and remains temperature independent below Tg. Below Tg a maximum quadrupolar interaction constant of 2 MHz is calculated. The addition of plasticizer to the polymer electrolyte causes significant chemical shift changes that depend on the solvent donicity of the plasticizer. The linewidth and T1 relaxation times also depend on the Tg of the plasticized systems. Previous 23Na NMR literature results are reviewed and qualitative models developed to account for the variation in results. © 1994 John Wiley & Sons, Inc.

Zusätzliches Material: 4 Ill.