Acta Chimica - Models in Chemistry 130. (1993)

1. szám - RESEARCH ARTICLES - Iordache, O.–Corriou, J. P.–Valentin, G.–Pons, M. N.–Pethő A.: Intermittent interfacial transfer: a dyadic model

2 IORDACHE et al.: INTERMITTENT INTERFACIAL TRANSFER: A DYADIC MODEL various chemical species on these oscillations could be quantitatively studied. The first step is the search for a system exhibiting bursting and intermittencies similar to those recorded as electrophysiological signals. It is expected that some liquid - liquid interfaces regarded as very simple models of bio-membranes will have the same basic properties. Next, it is expected that the effect of added chemicals on the natural and artificial membranes is similar allowing chemical pattern recognition. An interfacial transfer system was studied here consisting of an oil layer of nitrobenzene containing iodine and potassium iodide, imposed between two aqueous phases, one of which contained the surfactant hexadecyl-trimethylammonium bromide. Their properties suggest to use this liquid-liquid system as pattern generators in a neural-like sensor for the detection of complex properties. One of the difficulties in building neural-like systems is to uncover the organizing principles and the corresponding mathematical models that govern these systems [4]. The mathematical model of intermittent interfacial transfer developed here starts from the idea that the intermittent type of transfer results of the superposition of the displacements of particles in a medium structured by a hierarchy of cells. This implies the existence of a hierarchy of time-scales, a well-known feature of far-from equilibrium systems. To take into account this hierarchical organization of interfacial transfer, it is considered that the time has the topology of dyadic ring (see [5], [6], for different approaches to dyadic time). A physically motivated dyadic derivative results. This dyadic model is compared with experiments in terms of Walsh - Fourier analysis ([7], [8]). The dyadic structure of Walsh-Hadamard functions suggests that performing signal analysis with such orthogonal functions would be very promising. The argument of the new frame is based on the occurence of a hierarchy of time scales in non-linear systems and on the natural observation that expressions able to describe pulse-like and intermittent phenomena do not seem to be exponential or sinusoidal ones but, among others, piecewise constant Walsh - Hadamard orthogonal functions ([7], [5]). Preliminary comparisons between theory and experiments are performed using Walsh-Hadamard power spectrum. Finally, potential applications for adaptive sensors are discussed. Acta Chimica Hungarica - MODELS IN CHEMISTRY 130, 1993

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