Time-space Correlation Research Articles

Turbulence Measurement in Transonic Flow

Two instrumentation systems are presently practical to use in turbulence measurements. The laser velocimeter can measure fluctuating velocities while the hot-wire anemometer, in principle, can be used to obtain both kinematic and thermodynamic fluctuations. In addition, the hot-wire anemometer gives an analog signal output that is convenient for use in time-space correlation studies and spectral analyses. The laser velocimeter has been used successfully in all flow regimes, whereas the hot wire has not been exploited in transonic flows, where the wire response has not been well-understood. The purpose of this Note is to examine the response and calibration of a constant-temperature, hot- wire anemometer in transonic flow and to present turbulence measurements, obtained in a transonic boundary layer.

Forecasting of Earthquakes—Correlation between Deep Foci and Shallow Events in Melanesia

IN the Solomons Region of the S.W. Pacific, the deep focus earthquakes which have been detected since 1912 have been concentrated at the north-western end of the Bougainville–New Ireland, and in a region to the south-east of the Santa Cruz Group. Recent research has established a prima facie case for a systematic time–space correlation between deep foci and sequences of shallower seismic events similar to that found in the New Hebrides by Dr. Claude Blot in the course of several years of detailed investigation of thousands of seismic and volcanic events.

粒子群の時空間的な大きさの統計理論

Universal equations of diffusion are introduced. These equations can be applied to diffusion from a point source with infinite releasing time-interval to relative diffusion from an instantaneous source and to any other types of diffusion. Dependences of eddy diffusivity on time-distribution and spatial dimensions of clusters are clarified.In the course of the derivation of the equations, local time-space correlation of velocities is formulated, as a product of the correlation coefficient and local energy. The equation of local variance of stochastic time series is applied to the local energy in two-dimensional clusters with spatial and time-dimensions, by introducing the virtual one-dimensional scales of the clusters. Taylor's hypothesis about the relations between the Eulerian and Taylor-Karman correlations are made.The universal equations derived are solved numerically and for special cases analytically. The solutions for some cases are calculated and illustrated.