Maximum likelihood estimator ͑MLE͒ for a generalized Cauchy process ͑GCP͒ is studied with the aid of the method of information geometry in statistics. Our GCP is described by the Langevin equation with multiplicative and additive noises. The exact expressions of MLEs are given for the two cases that the two types of noises are uncorrelated and mutually correlated. It is shown that the MLEs for these two GCPs are free from divergence even in the parameter region wherein the ordinary moments diverge. The MLE relations can be regarded as a generalized fluctuationdissipation theorem for the present Langevin equation. Availability of them and of some other higher order statistics is demonstrated theoretically and numerically.

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In order to investigate the possible effect of seismic vibration on two-phase flow dynamics and thermal-hydraulics of a nuclear reactor, experimental tests of adiabatic air-water two-phase flow under low-frequency vibration were carried out in this study. An eccentric cam vibration module operated at low motor speed (up to 390 rpm) was attached to an annulus test section which was scaled down from a prototypic boiling water reactor (BWR) fuel assembly subchannel. The inner and outer diameters of the annulus are 19.1 mm and 38.1 mm, respectively. The two-phase flow operating conditions cover the ranges of 0,03 m/s <(jg) <1.46 m/s and 0.25 m/s <{jf)