Abstract: In this paper we present the experiment results of the space correlations of temperature fluctuations when there is and is not temperature gradient. From those results we can see clearly that the temperature fluctuation field is isotropic without temperature gradient, and it is obviously anisotropic with temperature gradient. The temperature correlation along gradient direction ft is obviously larger than the vertical to ft direction. Our experiment results agree with the theory results of D. W. Dunn and W.H. Rend[1].

Key words: hybrid dynamic system, switched linear system, time-delay, controllability, controllable set, switching sequence, switching path