This paper uses the 8 broad-band stations' microseism data recorded by the Seismic Monitoring Network of Fujian Province to calculate the vertical correlation coefficient between two stations at intervals of 5 minutes. According to the time intervals technique we obtain the different coefficients and then add the correlative coefficients. Depending on this, we extract the group velocity of Rayleigh waves from the cross correlation of the ambient seismic noise between two seismic stations and figure out the group velocity' spatial distribution. The results show that the signal noise ratio (SNR) increases proportionally to the superposition times, but the results from different days are similar to one another. Synchronously, the arrival-time is also stable and there is no obvious change when coming across typhoons. It is found the velocity of the surface wave is 2.9 - 3.1 km/s in Fujian Province, which is close to the observationally attained value. 相似文献
Followed the proposed ECT procedure that was the injection of 0.75 M CaCl2 solution for 72 h, then 1.5 M KOH solution for 48 h, then sodium silicate solution for 72 h and then deionized water for 168 h, the clay strength can be improved from anode to cathode entirely. To further improve the clay strength, curing the sample for different periods and applying electric field over the sample were studied. The cone resistance, water content, pH value, Ca2+ concentration and the XRD pattern were tested or analyzed in each test. Results show that injection of deionized water was a key phase to produce a full improvement of the treated clay, which cannot be replaced by the application of an electric field only and without injecting water. Curing the treated clay after injecting deionized water can yield a higher clay strength in the cathode area significantly due to pozzolanic reaction but produce a lower clay strength in the anode area because the formed NaOH decomposed the gel structure of the sodium silicate solution. To obtain a better strength after injection of deionized water for 168 h, the treated clay had to be cured for about 28 days, along with a dry anode compartment.
The SWAN wave model is typically designed for wave simulations in the near-shore region and thus is selected for evaluating its applicability on typhoon waves in the coastal waters around Taiwan Island. Numerical calculations on processes of wave heights and periods during the passages of four representative typhoons are compared with measured data from field wave stations on both east and west coasts. The results have shown that waves due to typhoons of paths 2, 3 and 4 can be reasonably simulated on east coastal waters. However, discrepancies increase for the simulated results on west coastal waters because the island's central mountains partly damage the cyclonic structures of the passing-over typhoons. It is also found that the included nested grid scheme in SWAN could improve the accuracy of simulations in coastal waters to facilitate further engineering practices. 相似文献
An iterative robust estimation procedure for correlated observations is proposed, in which the a-prior correlation coefficient
matrix is not updated to alleviate the computational burden. Selection of the downweighting strategy plays a key role in the
proposed method. Two local sensitivity-based strategies, one is based on the uniformly most powerful test statistics, the
other is based on the standardized least squares residuals, are developed and analyzed. Monte Carlo simulations in the GPS
network adjustment scenario demonstrate that, the two strategies can provide a certain resistance against the deteriorating
effect of outlying observations on the parameter estimates; the former downweighting strategy is superior to the latter one,
both in terms of robustness and computational efficiency. 相似文献
A three-point method for estimating wave reflection is proposed to account for monochromatic oblique incident waves propagating over a sloping beach. The amplitudes of reflected wave and incident wave are separated using wave amplitudes measured at three fixed wave gauges with a distance. The applicability of the theory is verified by comparing the simulated results with the available theoretical, numerical and experimental results for the estimation of wave reflection. The sensitivity is also tested to provide a more accurate prediction of the reflection coefficient. 相似文献