The study addresses the linear instability of narrow spectra homogeneous seas and its subsequent evolution in time, subject to inhomogeneous disturbances. Specifically, we study unidirectional spectra, where according to the kinetic equation no spectral evolution is expected. In the region of instability, recurrent evolution is discovered. This recurrence is the stochastic counterpart of the Fermi–Pasta–Ulam recurrence obtained for the cubic Schrödinger equation.

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The probability of freak waves in an inhomogeneous ocean is studied by integration of Alber's equation. The special phase structure of the inhomogeneous disturbance, required for instability, is provided by bound waves, generated by the quadratic interaction of the stochastic sea with a deterministic, long swell. The probability of freak waves higher than twice the significant wave height increases by a factor of up to 20 compared to the classical value given by Rayleigh's distribution. The probability of exceptionally high freak waves, with height larger than three times the significant wave height, is shown to increase some 30 000-fold compared to that given by the Rayleigh distribution, which renders their encounter feasible.

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Infrared detectors are probably the most popular device used for transient temperature monitoring of materials deformed in the high strain-rate regime. Embedded thermocouples have also been shown to be suitable for that purpose, especially with poor thermal conductors such as polymers [Rittel, Exp Mech 38(2), 73-79, 1998b]. However, there is no direct comparison between these two techniques. This paper presents experiments during which commercial polycarbonate specimens were deformed dynamically, while the surface and core temperatures were monitored using an infrared detector and embedded thermocouple respectively. An excellent agreement was obtained between the two techniques, confirming the suitability of thermocouples for transient temperature sensing.