Narrow Results

To understand the dynamic response of transversely isotropic material under explosion load, the analysis is done with the help of ABAQUS software and the constitutive equations of transversely isotropic material with different angle of isotropic section. The result is given: when the angle of isotropic section is settled, the velocity and acceleration of measure points decrease with the increasing distance from the explosion borehole. The velocity and acceleration in the loading direction are larger than those in the normal direction of the loading direction and their attenuation are much faster. When the angle of isotropic section is variable, the evolution curves of peak velocity and peak acceleration in the loading direction with the increasing angles are notching parabolic curves. They get their minimum values when the angle is equal to 45 degree. But the evolution curves of peak velocity and peak acceleration in the normal direction of the loading direction with the increasing angles are overhead parabolic curves. They get their maximum values when the angle is equal to 45 degree.

The main sequence relations of saccades stated that the duration was linearly correlated to the saccadic amplitude for a wide range, whereas the peak velocity correlated exponentially to the amplitude with saturation occurred at 30°-40°. Skewness was used efficiently in delineating the asymmetry between the acceleration and deceleration phases of the saccadic velocity profiles. It can be estimated from the shape parameter obtained by applying gamma function to the velocity profile. The relationship between peak velocity and skewness was derived according to the following observations. (1) At the same target amplitude and under the similar test conditions, data from previous investigations showed that great intra- and inter-subject variation of the peak velocity and the skewness were always observed. (2) Although the velocity was substantially decreased and the duration greatly increased, accuracy was not affected with the saccadic amplitude was almost unchanged for the subjects after diazepam had been taken. (3) The duration of acceleration phase is almost unchanged for different amplitudes.

Fifteen normal subjects (range 21 to 26 years with mean of 23.6) without history of neurological disease were recruited and tested in this study. Electro-oculograph (EOG) was used for recording the eye movements with amplitudes ranging from 10° to 60°. The results show that the data were highly correlated to the derived peak velocity and skewness relation with correlation coefficient (R) as high as 0.66-0.92 for great amplitudes (>30°). This study provides an alternative method in quantitative analysis of saccadic dynamics