In view of the importance of noise in physiology,information processing and finance,studies on chaos and noise have been undertaken.Detailed studies on the following oscillatory reactions have been undertaken:(i) thiophenol+BrO_3+H_2SO_4,(ii) fructose+BrO_3+H_2SO_4+Ce~(4+),and (iii) iodate+arsenite,which can serve as a model system for this purpose.Aperiodic oscillations have been observed in these systems.Analysis of phase plane plots yields complex attractors,which are quite different from strange attractor indicating the occurrence of random noise.Power spectra also indicate chaos with a broad band not necessarily the deterministic chaos.For the reactions (i) and (iii),a mechanism has been proposed involving precipitation of C_6-H_5-S-C_6H_5 and iodine,respectively;while in case of reaction (ii),gaseous evolution of Br_2 has been invoked.Experimental studies on sedimentation of C_6H_5-S-C_6H_5 and Br_2 evolution confirm that such heterogeneous reactions play an important role in generating noise in oscillations.
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